Educatable media determination system for inkjet printing

ABSTRACT

A system of classifying incoming media entering an inkjet or other printing mechanism is provided to identify the media without requiring any special manufacturer markings. The incoming media is optically scanned using a blue-violet light to obtain both diffuse and specular reflectance data, from which a media signature is generated. The generated signature is compared with known signatures for different media types to classify the incoming media, and a corresponding print mode is selected. Finally, the selected print mode for the classified incoming media is stored for future reference. Thus, a consumer can teach the printing mechanism to recognize new types of media. For borderline media falling between two categories, the printer remembers which category was selected previously, and then applies the same print mode to the next borderline media to provide a visually consistent output. A printing mechanism constructed to implement this method is also provided.

INFORMATION

DETAILED DESCRIPTION OF THE INVENTION

RELATED APPLICATIONS

This is a continuation-in-part application of pending U.S. patent application Ser. No. 09/676,100, filed on Sep. 29, 2000, which is a continuation-in-part application of pending U.S. patent application Ser. No. 09/607,206, filed on Jun. 28, 2000, which is a continuation-in-part application of U.S. patent application Ser. No. 09/430,487, filed on Oct. 29, 1999, now U.S. Pat. No. 6,325,505 which is a continuation-in-part application of U.S. patent application Ser. No. 09/183,086, filed on Oct. 29, 1998, which is a continuation-in-part application of 08/885,486, filed Jun. 30, 1997 U.S. Pat. No. 6,036,298, issued on Mar. 14, 2000, all having one inventor in common.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmented perspective view of one form of an inkjet printing mechanism, here an inkjet printer, including one form of an optical sensing system of the present invention for gathering information about an incoming sheet of media entering a printzone portion of the printing mechanism.

FIG. 2 is a schematic side elevational view of one form of an advanced media type determination optical sensor of the printer of FIG. .

FIG. 3 is a graph of the specular light output of the media type determination of sensor FIG. 2, which uses a blue-violet colored LED.

FIG. 4 is a bottom plan view of the media type optical sensor of FIG. 2, taken along lines — thereof.

FIG. 5 is a side elevational view of the lens assembly of FIG. .

FIG. 6 is a top plan view of one form of a lens assembly of the media optical sensor of FIG. .

FIG. 7 is a bottom plan view of the lens assembly of FIG. .

FIG. 8 is a flow chart illustrating the manner in which the optical sensor of FIG. 2 may be used to distinguish transparency media without tape, GOSSIMER photo media, transparency media with a tape header, and plain paper from each other.

FIG. 9 is a graph of the direct current (DC) level diffuse reflectance versus media type for all plain papers, including an entry for transparencies (“TRAN”) and one without the tape header, labeled “TAPE,” as well as GOSSIMER photo papers, labeled “GOSSIMER#1 and GOSSIMER #2.

FIG. 10 is a graph of the Fourier spectrum components, up to component for the GOSSIMER photo media.

FIG. 11 is a graph of the Fourier spectrum components, up to component for the representative plain paper provided by MoDo Datacopy, labeled “MODO” in FIG. .

FIG. 12 is a graph of the sum of the Fourier spectrum components for all of the media shown in FIG. .

FIG. 13 is a graph of the Fourier spectrum components, up to component for a transparency with a tape header, indicated as “TAPE” in FIG. .

FIG. 14 is a graph of the summed third, sixteenth, seventeenth and eighteenth Fourier spectrum components for the plain paper media shown in FIG. 9, in addition to that of the TAPE header across a transparency indicated as “TRAN.”

FIG. 15 is a flow chart of one form of a method for determining which major category of media, e.g., plain paper, premium paper, photo paper or transparency, is entering the printzone of the printer of FIG. 1, as well as determining specific types of media within major media categories, such as distinguishing between generic premium paper, matte photo premium paper, and prescored heavy greeting card stock.

FIG. 16 is a flow chart of the “collect raw data” portion of the method of FIG. .

FIG. 17 is a flow chart of the “massage data” portion of the method of FIG. .

FIG. 18 is a flow chart of the “verification” and “select print mode” portions of the method of FIG. .

FIG. 19 is a flow chart of a data weighting and ranking routine used in both the “verification” and “select print mode” portions of the method of FIG. .

FIGS. 20-23 together form a flow chart which illustrates the “major category determination” and “specific type determination” portions of the method of FIG. 15, specifically with:

FIG. 20 showing transparency determination;

FIG. 21 showing glossy photo determination;

FIG. 22 showing matte photo determination; and

FIG. 23 showing plain paper and premium paper determination.

FIG. 24 is an enlarged schematic side elevational view of the media type optical sensor of FIG. 2, shown monitoring a sheet of plain paper or transparency media entering the printzone of the printer of FIG. .

FIG. 25 is an enlarged schematic side-elevational view of the media type sensor of FIG. 2, shown monitoring a sheet of photo media with a uniform coating entering the printzone of the printer of FIG. .

FIG. 26 is an enlarged schematic side-elevational view of the media type sensor of FIG. 2, shown monitoring a sheet of photo media with an irregular coating entering the printzone of the printer of FIG. .

FIGS. 27-33 are graphs of the raw data accumulated during the “collect raw data” portion of the method of FIG. 14, specifically with:

FIG. 27 showing data for a very glossy photo media;

FIG. 28 showing data for a glossy photo media;

FIG. 29 showing data for a matte photo media;

FIG. 30 showing data for a plain paper media, specifically, a Gilbert® Bond;

FIG. 31 showing data for a premium media

FIG. 32 showing data for HP transparency media with a tape header; and

FIG. 33 showing data for transparency media without a tape header.

FIGS. 34-39 are graphs of the Fourier spectrum components, up to component , specifically with:

FIG. 34 showing the matte photo media diffuse reflection;

FIG. 35 showing the matte photo media specular reflection;

FIG. 36 showing the very glossy photo media diffuse reflection;

FIG. 37 showing the very glossy photo media specular reflection;

FIG. 38 showing the plain paper media diffuse reflection; and

FIG. 39 showing the plain paper media specular reflection.

FIG. 40 is a graph of the diffuse spatial frequencies of several generic media, including plain paper media, premium paper media, matte photo media, glossy photo media, and transparency media.

FIG. 41 is a graph of the specular spatial frequencies of several generic media, including plain paper media, premium paper media, matte photo media, glossy photo media, and transparency media.

FIG. 42 is a graph of the diffuse spatial frequencies of several specific photo media, including photo media with swellable and porous ink retention layers.

FIG. 43 is a graph of the specular spatial frequencies of several specific photo media, including photo media with swellable and porous ink retention layers.

FIG. 44 is a flow chart illustrating one form of a two-stage media determination system of the present invention for operating the sensor of FIG. .

FIG. 45 is a flowchart of a user-educatable media identification system of the present invention.

FIG. 46 is a flowchart of an automatic media identification system of the present invention which identifies borderline media falling between two media categories or types.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 illustrates an embodiment of an inkjet printing mechanism, here shown as an inkjet printer , constructed in accordance with the present invention, which may be used for printing for business reports, correspondence, desktop publishing, artwork, and the like, in an industrial, office, home or other environment. A variety of inkjet printing mechanisms are commercially available. For instance, some of the printing mechanisms that may embody the present invention include plotters, portable printing units, copiers, cameras, video printers, and facsimile machines, to name a few. For convenience the concepts of the present invention are illustrated in the environment of an inkjet printer which may find particular usefulness in the home environment.

While it is apparent that the printer components may vary from model to model, the typical inkjet printer includes a chassis surrounded by a housing or casing enclosure , the majority of which has been omitted for clarity in viewing the internal components. A print media handling system feeds sheets of print media through a printzone . The print media may be any type of suitable sheet material, such as paper, card-stock, envelopes, fabric, transparencies, mylar, and the like, with plain paper typically being the most commonly used print medium. The print media handling system has a media input, such as a supply or feed tray into which a supply of media is loaded and stored before printing. A series of conventional media advance or drive rollers (not shown) powered by a motor and gear assembly may be used to move the print media from the supply tray into the printzone for printing. After printing, the media sheet then lands on a pair of retractable output drying wing members , shown extended to receive the printed sheet. The wings momentarily hold the newly printed sheet above any previously printed sheets still drying in an output tray portion before retracting to the sides to drop the newly printed sheet into the output tray . The media handling system may include a series of adjustment mechanisms for accommodating different sizes of print media, including letter, legal, A-4, envelopes, etc. To secure the generally rectangular media sheet in a lengthwise direction along the media length, the handling system may include a sliding length adjustment lever , and a sliding width adjustment lever to secure the media sheet in a width direction across the media width.

The printer also has a printer controller, illustrated schematically as a microprocessor , that receives instructions from a host device, typically a computer, such as a personal computer (not shown). Indeed, many of the printer controller functions may be performed by the host computer, by the electronics on board the printer, or by interactions therebetween. As used herein, the term “printer controller ” encompasses these functions, whether performed by the host computer, the printer, an intermediary device therebetween, or by a combined interaction of such elements. A monitor coupled to the computer host may be used to display visual information to an operator, such as the printer status or a particular program being run on the host computer. Personal computers, their input devices, such as a keyboard and/or a mouse device, and monitors are all well known to those skilled in the art.

The chassis supports a guide rod that defines a scan axis and slideably supports an inkjet printhead carriage for reciprocal movement along the scan axis , back and forth across the printzone . The carriage is driven by a carriage propulsion system, here shown as including an endless belt coupled to a carriage drive DC motor . The carriage propulsion system also has a position feedback system, such as a conventional optical encoder system, which communicates carriage position signals to the controller . An optical encoder reader may be mounted to carriage to read an encoder strip extending along the path of carriage travel. The carriage drive motor then operates in response to control signals received from the printer controller . A conventional flexible, multi-conductor strip may be used to deliver enabling or firing command control signals from the controller to the printhead carriage for printing, as described further below.

The carriage is propelled along guide rod into a servicing region , which may house a service station unit (not shown) that provides various conventional printhead servicing functions. To clean and protect the printhead, typically a “service station” mechanism is mounted within the printer chassis so the printhead can be moved over the station for maintenance. For storage, or during non-printing periods, the service stations usually include a capping system which hermetically seals the printhead nozzles from contaminants and drying. Some caps are also designed to facilitate priming by being connected to a pumping unit that draws a vacuum on the printhead. During operation, clogs in the printhead are periodically cleared by firing a number of drops of ink through each of the nozzles in a process known as “spitting,” with the waste ink being collected in a “spittoon” reservoir portion of the service station. After spitting, uncapping, or occasionally during printing, most service stations have an elastomeric wiper that wipes the printhead surface to remove ink residue, as well as any paper dust or other debris that has collected on the printhead.

In the printzone , the media receives ink from an inkjet cartridge, such as a black ink cartridge and three monochrome color ink cartridges , and , secured in the carriage by a latching mechanism , shown open in FIG. . The cartridges - are also commonly called “pens” by those in the industry. The inks dispensed by the pens - may be pigment-based inks, dye-based inks, or combinations thereof, as well as paraffin-based inks, hybrid or composite inks having both dye and pigment characteristics.

The illustrated pens - each include reservoirs for storing a supply of ink therein. The reservoirs for each pen - may contain the entire ink supply on board the printer for each color, which is typical of a replaceable cartridge, or they may store only a small supply of ink in what is known as an “off-axis” ink delivery system. The replaceable cartridge systems carry the entire ink supply as the pen reciprocates over the printzone along the scanning axis . Hence, the replaceable cartridge system may be considered as an “on-axis” system, whereas systems which store the main ink supply at a stationary location remote from the printzone scanning axis are called “off-axis” systems. In an off-axis system, the main ink supply for each color is stored at a stationary location in the printer, such as four refillable or replaceable main reservoirs , , and , which are received in a stationary ink supply receptacle supported by the chassis . The pens , , and have printheads , , and , respectively, which eject ink delivered via a conduit or tubing system from the stationary reservoirs - to the on-board reservoirs adjacent the printheads -.

The printheads - each have an orifice plate with a plurality of nozzles formed therethrough in a manner well known to those skilled in the art. The nozzles of each printhead - are typically formed in at least one, but typically two linear arrays along the orifice plate, aligned in a longitudinal direction perpendicular to the scanning axis . The illustrated printheads - are thermal inkjet printheads, although other types of printheads may be used, such as piezoelectric printheads. The thermal printheads - typically include a plurality of resistors which are associated with the nozzles. Upon energizing a selected resistor, a bubble of gas is formed which ejects a droplet of ink from the nozzle and onto a sheet of paper in the printzone under the nozzle. The printhead resistors are selectively energized in response to firing command control signals received via the multi-conductor strip from the controller .

Optical Media Type

Determination Sensor

FIG. 2 illustrates one form of an optical media type determination sensor or “media sensor” constructed in accordance with the present invention. The sensor includes a casing or base unit may be supported by the printhead carriage in a variety different ways known to those skilled in the art. The sensor has an illuminating element, here, a blue-violet light emitting diode (LED) which has an output lens . Extending from the LED are two input leads and which may be electrically coupled to conductors in a printed circuit board (not shown) secured to an exterior portion of the body to deliver sensor signals back to the printer controller . The printed circuit board and flexible conductors may be used to couple the sensor to an electronics portion (not shown) of the carriage . The sensor signals then pass from the carriage through the multi-conductor strip , which carries power and communication signals between the controller and the carriage . A lens assembly is supported by the casing , with the lens assembly being described in greater detail below with respect to FIGS. 5-7.

The media sensor preferably uses a blue-violet LED which emits an output spectrum shown in FIG. 3 as graph . The blue-violet LED has a peak wavelength of around nanometers, and a dominant wavelength of nanometers, yielding a more violet output than the blue LED described in U.S. Pat. No. 6,036,298, recited in the Related Applications section above, which had a peak wavelength of around 470 nanometers. Several reasons for this change in the illumination component of the media sensor will be described near the end of the Detailed Description section. The LED includes a negative lead frame which is electrically coupled to the conductor . The LED also has a die mounted within a reflector cup , which is supported by the negative lead frame . The die is used to produce the blue-violet wavelength light of graph emitted by the LED when energized. A positive lead frame is electrically coupled to conductor , and serves to carry current therethrough when the LED is turned on. Preferably, the negative lead frame , the die , the cup , and the positive lead frame are all encapsulated in a transparent epoxy resin body which is conformed to define the output lens as an integral dome lens that directs light from the die into rays which form an illuminating beam . One preferred manner of operating the LED , including illumination routines, is described in detail in U.S. Pat. No. 6,036,298, recited in the Related Applications section above

The media sensor also has two filter elements and , which lay over portions of the lens assembly . These filters and may be constructed as a singular piece, although in the illustrated embodiment two separate filters are shown. The filters and have a blue pass region where the low wavelength blue-violet LED light, with a wavelength of 360-510 nm, passes freely through the filters and , but light of other wavelengths from other sources are blocked out. Preferably, the filter elements and are constructed of a 1 mm (one millimeter) thick sheet of silicon dioxide (glass) using conventional thin film deposition techniques, as known to those skilled in the art.

The optical sensor also includes a diffuse photodiode that includes a light sensitive photocell which is electrically coupled to an amplifier portion (not shown) of the photodiode . The photodiode has input lens , which emits light to the light sensitive photocell . The photocell is preferably encapsulated as a package fabricated to include the curved lens which concentrates incoming light onto the photocell . The photodiode also has three output leads , and which couple the output from amplifier to electrical conductors on the printed circuit board (not shown) to supply photodiode sensor signals to the controller , via electronics on the carriage and the multi-conductor flex strip . While a variety of different photodiodes may be used, one preferred photodiode is a light-to-voltage converter, which may be obtained as part no. TSL257 from Texas Analog Optical Systems (TAOS) of Dallas, Tex.

The optical sensor also includes a second specular photodiode ′ that may be constructed as described for the diffuse photodiode , with like components on the specular photodiode having the same item numbers as the diffuse photodiode, by carrying a “prime” designator (′) similar to an apostrophe. Preferably, the casing is constructed so that the LED is optically isolated from the photodiodes , ′ to prevent light emitted directly from the LED from being perceived by the photocells , ′. Thus, the outbound light path of the LED is optically isolated from the inbound light path of the photodiode .

The media sensor also has two field of view controlling elements, such as field stops and . The field stops and , as well as the filters and , are held in place by various portions of the casing , and preferably, the field stops and are molded integrally with a portion of the casing . The field stops and are preferably located approximately tangent to the apex of the input lenses , ′ of the photodiodes , ′, respectively. In the illustrated embodiment, the field stops , define field of view openings or windows and , respectively.

FIG. 4 shows the orientation of the field stop windows and with respect to the scanning axis . In the illustrated embodiment, the field stop windows and are rectangular in shape, with the specular window having a major axis which is approximately parallel to the scanning axis , and the diffuse field stop window having a major axis which is substantially perpendicular to the scanning axis . The specular field stop has window oriented with a minor axis which in the illustrated embodiment is colinear with the major axis of the diffuse field stop window . This orientation of the field stop windows , allows the diffuse photodiode to collect data which may be distinguished from that collected by the specular photodiode ′.

FIG. 2 illustrates the light paths through the lens assembly as a sheet of media , here illustrated as paper, is scanned by sensor . The LED generates the output beam , which is aimed toward an illuminated area of the media by first passing through the lens assembly as an illuminating beam . The media produces two reflected beams, one, a diffuse reflected beam and a specular reflected beam ′. The diffuse and specular reflected beams , ′ pass through the filter elements , , respectively to form the respective diffuse and specular filtered beams and ′. The diffuse reflected light beam has a flame-like scattering of rays arranged in a Lambertian distribution. The specular beam ′ is reflected off the media at the same angle that the incoming light beam impacts the media, according to the well known principle of optics: “angle of incidence equals angle of reflection.” In the illustrated embodiment, the angle of incidence and the angle reflection are selected to be around 55°.

FIGS. 5-7 illustrate the construction of the lens assembly , which may be made of an optical plastic material molded with lens elements formed therein. FIG. 5 shows an LED output lens as having a diffractive lens element formed along a top surface of the lens . The diffractive lens is located directly beneath the LED output beam . FIG. 6 illustrates a bottom view of the lens assembly which has a bottom surface facing down toward the media . Opposite the diffractive lens element , the LED output lens has a Fresnel lens element formed along the lower surface . FIG. 5 best shows a diffuse lens as having a photodiode input lens element projecting outwardly from the lower surface . Preferably, the lens is a convex aspheric condenser lens. FIG. 6 illustrates another portion of the diffuse lens as having an upper or output lens element which is directly opposite the input element . While the output element may be a flat extension of the upper surface of the lens , in some embodiments, contouring of the upper surface may be desired to improve the optical input to the photodiode lens . Preferably, the photodiode output element is also a diffractive lens, which may be constructed as described above for the upper diode lens element to provide correction of chromatic aberrations of the primary input lens element .

The specular photodiode ′ receives the filtered specular beam ′. To accommodate this incoming specular reflectance beam ′ the lens assembly has a specular lens with an incoming Fresnel lens element ′, and an outgoing diffractive lens element ′, which may be constructed as described above for lens elements and , respectively. It is apparent to those skilled in the art that other types of lens assemblies may be used to provide the same operation as lens assembly . For instance, the specular lens element ′ may be constructed with an aspheric refractive incoming lens element, and an outgoing aspheric refractive lens element or an outgoing micro-Fresnel lens. A detailed discussion of the operation of these lens elements is described in U.S. Pat. No. 6,036,298, recited in the Related Applications section above, or may be found in most basic optics textbooks.

A few definitions may be helpful at this point:

“Radiance” is the measure of the power emitted by a light source of finite size expressed in W/sr-cm2 (watts per steradian—centimeters squared).

“Transmission” is measure of the power that passes through a lens in terms of the ratio of the radiance of the lens image to the radiance of the original object, expressed in percent.

“Transmittance” is a spectrally weighted transmission, here, the ratio of the transmitted spectral reflectance going through the lens, e.g. beam , to the incident spectral reflectance, e.g. beam ′.

“Specular reflection” is that portion of the incident light that reflects off the media at an angle equal to the angle at which the light struck the media, the angle of incidence.

“Reflectance” is the ratio of the specular reflection to the incident light, expressed in percent.

“Absorbance” is the converse of reflectance, that is, the amount of light which is not reflected but instead absorbed by the object, expressed in percent as a ratio of the difference of the incident light minus the specular reflection, with respect to the incident light.

“Diffuse reflection” is that portion of the incident light that is scattered off the surface of the media at a more or less equal intensity with respect to the viewing angle, as opposed to the specular reflectance which has the greatest intensity only at the angle of reflectance.

“Refraction” is the deflection of a propagating wave accomplished by modulating the speed of portions of the wave by passing them through different materials.

“Index of refraction” is the ratio of the speed of light in air versus the speed of light in a particular media, such as glass, quartz, water, etc.

“Dispersion” is the change in the index of refraction with changes in the wavelength of light.

Basic Media Type Determination System

FIG. 8 illustrates one form of a preferred basic media type determination system as a flow chart, constructed in accordance with the present invention, which may be used in conjunction with the optical sensor of FIG. . The first step of this media-type determination method consists of starting the media pick routine where a fresh sheet of media is picked by the media handling system from the input tray . This fresh sheet of media is then moved into the printzone in step . After the media pick routine is completed, the LED of the optical sensor is illuminated, and in step this illumination is adjusted to bring the signal received from an unprinted portion of the media up to a near-saturation level of the analog to digital (A/D) converter, which is on the order of 5 volts. This A/D converter is within the controller , and during data acquisition this A/D converter is enabled and allowed to acquire the output signal of the photodiode .

Once the illumination of the LED has been adjusted in a scanning step , the optical sensor is scanned across the media by carriage to collect reflectance data points and preferably, to record these data points at every positional encoder transition along the way, with this positional information being obtained through use of the optical encoder strip (FIG. ). Thus, the data generated in the scanning and collecting step consists of both positional data and the corresponding reflectance data, with the reflectance and position being in counts. For instance, for the reflectance, twelve bits, or 212 which equals 4096 counts, are equally distributed over a 0-5 Volt range of the A/D converter. Thus, each count is equal to 5/4096, or 1.2 mV (millivolts). The light (reflectance from the media is captured by the LVC (light-to-voltage converter) and provides as an output an analog voltage signal which is translated by the analog-to-digital converter into a digital signal expressed in counts. The position on the media (e.g., paper) is also expressed in counts derived from the 600 quadrature transitions per inch of the encoder in the illustrated embodiment, although it is apparent to those skilled in the art that other transitions per inch, or per some other linear measurement, such as centimeters, may also be used. Thus, a position count of in the illustrated embodiment translates to a location on the paper or other media of 1200/600 position counts, or 2.0 inches (5.08 centimeters) from the start of the scan. Preferably, the media is scanned a single time and then the data is averaged in step . step -During the scanning and collecting step , the field of view of the optical sensor is placed over the media with the media resting at the top of form position. In this top of form position, for a transparency supplied by the Hewlett-Packard Company, which has a tape header across the top of the transparency, this implies that the tape header is being scanned by the sensor .

Since the A-D conversions used during the scanning and collecting step is triggered at each state transition of the encoder strip , the sampling rate has spatial characteristics, and occurs typically at 600 samples per inch in the illustrated printer . During the scan, the carriage speed is preferably between 2 and 30 inches per second. The data collected during step is then stored in the printer controller , and is typically in the range of a 0-5 volt input, with 9-bit resolution. At the conclusion of the scanning, the data acquisition hardware signals the controller that the data collection is complete and that the step of averaging the data points may then be performed.

The media type determination system then performs a spatial frequency media identification routine to distinguish whether the media sheet that has been scanned is either a transparency without a header tape, photo quality media, a transparency with a header tape, or plain paper. The first step in the spatial frequency media identification routine is step , where a Fourier transform is performed on all of the data to determine both the magnitude and phase of each of the discrete spatial frequency components of the data recorded in step . In the illustrated embodiment for printer , the data record consists of 4000 samples, so the Fourier components range from 0-4000. The magnitude of the first sorted component is the direct current (DC) level of the data.

If a transparency without a tape header is being examined, this DC level of the data will be low. FIG. 9 is a graph of the DC level of reflectance for a group of plain papers which were studied, with the abbreviation key being shown in Table 1 below. Also shown in FIG. 9 are the DC levels of reflectance for transparencies with a header tape, labeled “TAPE,” as shown by bar and for that without the tape header, labeled as “TRAN”, as shown by bar in graph .

Also included in the DC level reflectance graph of FIG. 9 are two types of Gossimer photo paper, labeled GOSSIMER# and GOSSIMER#, as shown by bars and , respectively in graph . The remainder of the bars in graph indicate varying types of plain paper, as shown in Table 1 below, of which bar is used for MoDo DataCopy plain paper media, labeled as “MODO”. From a review of graph , it is seen that the low level of light passing through the transparency without a tape header at bar is readily distinguishable from the remainder of the reflectance values for the other types of media, which is because rather than the light being reflected back to the photo sensor , it passes through the transparency. Thus, in step , a determination is made based on the DC level of the reflectance data which, if it is under a reflectance of 200 counts then a YES signal is generated to provide a transparency without tape signal to the controller , which then adjusts the printing routine accordingly for a transparency. If instead, the DC level of the data collected is greater than 200 counts, then a NO signal is generated and further investigation takes place to determine which of the other types of media may be present in the printzone. Note that step of comparing the reflectance data may also be performed before the Fourier transform step , since the Fourier spectrum values are not needed to determine whether or not the media is a regular transparency without tape.

So if the media is not a transparency without a tape header, a determination is then made whether the media is a photo quality media. To do this, a Fourier spectrum component graph is used, as shown in FIG. 10, along with a Fourier spectrum component graph for plain paper, here the MoDo Datacopy brand of plain paper shown in FIG. . Before delving into an explanation of this analysis, an explanation of the units for the spatial frequency label along the horizontal axis of these graphs (as well as for the graph in FIG. 13) is in order. The spatial frequency components are the number of cycles that occur within the scan data collected in the scan media step of FIG. . For the examples illustrated herein, the length of the data sample was selected to be 4000 samples. As discussed above, in the illustrated embodiment, the data is sampled at 600 samples per inch of movement of the sensor . A spatial frequency that completes 30 cycles within the length of the scan data would therefore have an equivalent spatial frequency found according to the equation:

In the illustrated embodiment, a data scan of 4000 samples is equivalent to a traverse of 6.6 inches across the media which is the scan distance used herein, from the equation:

From the comparison of graphs and , it is seen that the magnitudes of the spectrum components above the count n equals eight (n=8) are much greater in the plain paper spectrum of graph then for the photo media in graph . Thus, in step the spectral components from 8-30 are summed and in a comparison step , it is determined that if the sum of the components 8-30 is less than a value, here a value of 25, a YES signal is generated. In response to the YES signal, step generates a signal which is provided to the controller so the printing routines may be adjusted to accommodate for the photo media. Note that in FIGS. 10 and 11, several of the components having a count of less than eight (n<8) have frequency magnitudes which are greater than the maximum value shown on graphs and , but they are not of interest in this particular study, so their exact values are immaterial to our discussion here.

Fourier spectrum component graphs such as and may be constructed for all of the different types of media under study. FIG. 12 shows a graph of the sum of the magnitude of components 8-30 for each of the different types of plain paper and photo media. Here we see the GOSSIMER# and GOSSIMER# photo medias having their summed components shown by bars and . It is apparent that the magnitude of the photo media summed components and is much less than that for any of the remaining plain paper medias, including the bar for the MoDo Datacopy media. Thus, returning to the flow chart of FIG. 8, in response to the sum components step in a comparison step the magnitude of the sum of components 8-30 is compared, and if less than the value of 25 a YES signal is generated.

However, if the media in printzone is not photo media, the decision step generates a NO signal having determined that the media is not a transparency without a header tape and not photo media it then remains to be determined whether the media is either a transparency with a header tape or plain paper. FIG. 13 is a graph of the Fourier spectrum components for a transparency with a tape header, with a tape header being shown below the graph and having starting and ending points and also being indicated. Over the duration of the scan, there are three HP logos encountered and roughly seventeen directional arrows , indicating which way a user should insert the media into the printer. These logos and arrows create a media signature in the spectrum as can be seen from an analysis of graph . As can be seen from a review of the graph , the third component and the seventeenth component are much larger than those in the plain paper spectrum of the respective third and seventeenth components and in graph of FIG. 11 (note that the vertical scale on graph in FIG. 13 is fragmented, and the magnitude of the third component is at a value above 800.). Due to positioning errors at the beginning of the scan, which are compensated in step where the data points are averaged, the sixteenth and eighteenth components and , respectively, of graph are much larger than the sixteenth and eighteenth components and , for the plain paper in graph . Consequently, the sixteenth and eighteenth components are also contained within this unique frequency signature.

Returning to flow chart of FIG. 8, in step the magnitude of the components of the third, sixteenth, seventeenth and eighteenth spectrums are summed, with these resulting sums being shown in graph of FIG. . The sum for the tape is shown as bar , which is clearly of a much greater magnitude than the various plain papers, such as bar for the MoDo Datacopy plain paper. Thus, a decision may then be made in step , to determine whether the sum of the frequency sub-components , , and performed by step is greater than 1300 if so, a YES signal is delivered to indicate that the media is a transparency with a tape header, and this information is then transferred by step to the printer controller for subsequent processing and adjustment of the printing routines. However, if the decision by step is that the sum is less than 1300, then a NO signal is generated which is then sent to a decision block indicating plain paper is in the printer, and the default plain paper print mode may be used by the controller .

Advanced Media Determination System

FIG. 15 illustrates one form of a preferred advanced media type determination system as a flow chart, constructed in accordance with the present invention. In describing this advanced media determination system , first an overview of the system operation will begin with respect to FIG. . Next will be a description of several more general portions of the determination system with respect to FIGS. 16-19, followed by a detailed description of the heart of the determination method with respect to FIGS. 20-23. Following a description of the method, FIGS. 24-26 will be used to explain how the media sensor of FIG. 2 is used in the determination routines of FIGS. 20-23, followed by graphical examples of several different types of media studied, with respect to FIGS. 27-39. In FIGS. 40 through 43, the spatial frequencies of light collected by the media type determination sensor are studied to show how system determines which type of media is entering the printzone of printer . Finally, FIG. 44 will be used to describe a preferred two-stage media determination system which speeds printer throughput (pages per minute) when printing on plain paper.

1. System Overview

Returning to FIG. 15, the advanced media determination system is shown in overview as having a first collect raw data step . Following collection of the raw data, a massage data routine is performed to place the data collected in step into a suitable format for further analysis. Following the massaging data step, comes a major category determination step and a specific type determination step . The major and specific determination steps and are interlaced, as will be seen with respect to FIGS. 20-23. For instance, once a major category determination is made, such as for premium paper media, then a further determination may be made as to which specific type of premium media is used. However, to arrive at the major determination step for premium media, the routine must first have discarded the possibilities that the media might be a transparency, a glossy photo, a matte photo, or a plain paper media. After the method has made a specific type determination in step , a verification step is performed to assure that the correct specific determination has been made. Following the verification step , the determination system then has a select print mode step , which correlates the print mode to the specific type of media which is entering the printzone . In response to the selection of print mode step , the system then concludes with a print step , where printing instructions are sent to the printheads - to print an image in accordance with the print modes selected in step .

2. Collect Raw Data Routine

Now that the construction of the media sensor is understood, its use will be described with respect to the collection of raw data routine , which is illustrated in detail in FIG. . In a first step of routine , the blue-violet LED is turned on, and the brightness of the LED is adjusted. Following step , in a scanning step , the printhead carriage transports the media sensor across the printzone , parallel to the scanning axis . During the scanning step , the media surface is spatially sampled and both the diffuse reflected light components , and the specular reflected light components ′ are collected at every state transition as the carriage optical encoder reads markings along the encoder strip . These diffuse and specular reflectance values are stored as analog-to-digital (A/D) counts to generate a set of values for the reflectances at each encoder position along the media. In some implementations, it may be desirable to scan the media several times to produce an averaged data set, although typically only one scan of the media is required to produce good results.

During this scanning step , the sheet of media is placed under the media sensor at the “top of form” position. For an HP transparency media with a tape header , as shown in FIG. 13, the tape is within the field of view, even though at this point the tape is located along the undersurface of the media. Indeed, even though the tape header is facing away from the sensor , as well as away from sensor in the basic media type determination method (FIG. ), the markings , on the tape header are viewable by sensor , and may be used to identify this media as described above in method .

In a final checking step of the raw data collection routine , a high level look or check is performed to determine whether all of the data collected during step is actually data which lies on the media surface. For instance, if a narrower sheet of media is used (e.g. A-4 sized media or custom-sized greeting card media) than the standard letter-size media for which printer is designed, some of the data points collected during the scanning step will be of light reflected from the media support member, also known as a platen or “pivot,” which forms a portion of the media handling system . Thus, any data corresponding to the pivot is separated in step from the data corresponding to the sheet of media, which is then sent on as a collected raw data signal to the massage data routine .

During the analog to digital conversion portion of the scanning step , the A-to-D conversion is triggered at each state transition of the carriage positional encoder which monitors the optical encoder strip . In this manner, the data is collected with a spatial reference, that is, spatial as in “space,” so the data corresponds to a particular location in space as the carriage moves sensor across the printzone . For the illustrated printer the sampling rate typically occurs at the rate of 600 samples per inch (1524 samples per centimeter). During this scanning step , preferably the speed of the carriage is between two and thirty inches per second (5.08 to 76.2 centimeters per second). One preferred analog-to-digital conversion is over a 0-5 volt range, with a 9-bit resolution.

3. Massage Data Routine

FIG. 17 illustrates the details of the massage data routine , which generates a set of four signals as outputs which are sent to the major category determination routine . In two steps, averages of the incoming data are found. Specifically, in a “find specular average” step , and a “find diffuse average” step , the averages for all of the incoming specular raw data and diffuse raw data, respectively, are found. The specular average step produces a specular average signal , also indicated by the letter “A” in FIG. 17, which is provided as an input to the major category determination routine . The diffuse average step produces a specular average signal , also indicated by the letter “B” in FIG. 17, which is provided as an input to the major category determination routine .

The other major operations performed by the massage data routine are preformed in a “generate specular reflectance graph” step , and in a “generate diffuse reflectance graph” step . In step , the collected raw data is arranged with the diffuse and specular reflectance values referenced to the same spatial position with respect to the pivot or platen.

The steps of generating the specular and diffuse reflectance graphs , each produce an output signal, and , which are received by two conversion steps and , respectively. In step , the aligned data is passed through a Hanning or Welch's fourth power windowing function. Following this manipulation, a discrete fast Fourier transform may be performed on the windowed data to produce the frequency components for the sheet of media entering the printzone . In each of steps and , the graphs are produced in terms of magnitude versus (“vs.”) position, such as the graphs illustrated in FIGS. 27-33, discussed further below. The specular spatial frequency, shown as a bar chart of frequency versus the magnitude2 (magnitude squared), which is an output signal , also labeled as letter “S,” which is supplied to the major category determination routine . In step , the incoming data is converted to a diffuse spatial frequency, shown as a bar chart of frequency versus the magnitude2, to produce an output signal , also labeled as letter “D,” which is supplied to the major category determination routine . Examples of the graphical data provided by the conversion steps and are shown in FIGS. 34-39, discussed further below.

Thus, during the massage data routine , a Fourier transform is performed on the collected raw data to determine the magnitude and phase of each of the discrete spatial frequency components of the recorded data for each channel, that is, channels for the specular and diffuse photodiodes ′, . Typically this data consists of a record of 1000-4000 samples. The Fourier components of interest are limited by the response of the photodiodes , ′ to typically less than 100 cycles per inch. The magnitude of the first order component is the DC (direct current) level of the data. This DC level is then used to normalize the data to a predetermined value that was used in characterizing signatures of known media which has been studied. A known media signature is a pre-stored Fourier spectrum, typically in magnitude values, for both the specular and diffuse channels for each of the media types which are supported by a given inkjet printing mechanism, such as printer .

4. Verification and Selection of Print Mode Routines

FIG. 18 illustrates the details of the verification and select print mode steps , of the media determination system . Here we see the verification step receiving incoming data from the specific type determination step . This incoming data is first received by a “make assumption” step , with this assumption regarding the specific media type. Step yields an assumed specific type signal , which is received by a “determine the quality fit” step . The determine the quality fit step is used to test the correctness of the assumption made in step . In a look-up step , a table of the various type characteristics for each specific type of media is consulted, and data corresponding to the assumed media type of signal is provided to the quality fit step as a reference data signal . The quality fit step processes the reference values and the assumed media type signal and provides an output signal to the select print mode routine .

The output signal from the verification step is received by a comparison step , where it is determined whether the assumption data matches the reference data . If this data does indeed match, a YES signal is issued by the comparison step to a “select print mode” step . Step then selects the correct print mode for the specific type of media and issues a specific print mode signal to the print step . However, if the comparison step determines that the media type assumed step does not have characteristics which match the reference data , then a NO signal is issued. The NO signal is then sent to a “select default print mode” step . The default print mode selection step then issues a default print mode signal , corresponding to the major type of media initially determined, and then the incoming sheet is printed in step according to this default determination.

5. Types of Media

At this point, it may be helpful to describe the various major types of media which may be determined using system , along with giving specific examples of media which falls into the major type categories. It must be noted that only a few of the more popular medias have been studied, and their identification incorporated into the specifics of the illustrated determination system . Indeed, this is a new frontier for printing, and research is continuing to determine new ways to optically distinguish one type of media from another. The progress of this development routine is evidenced by the current patent application, which has progressed from a basic media determination routine described in the parent application, to this more advanced routine which we are now describing. Indeed, other medias remain yet to be studied, and further continuing patent applications are expected to cover these determination methods which are so far undeveloped.

Table 2 shows the print modes assigned by media type:

In the first major type category of plain paper, a variety of different plain papers have been listed previously with respect to Table 1, with the specific type of plain paper shown in graphs , and being a Gilbert® Bond media, as a representative of these various types of plain paper.

Several different types of media fall within the premium category, and several of these premium papers have coatings placed over an underlying substrate layer. The coatings applied over premium medias, as well as transparency medias and glossy photo medias, whether they are of a swellable variety or a porous variety, are known in the art as an ink retention layer (“IRL”). The premium coatings typically have porosities which allow the liquid ink to pool inside these porosities until the water or other volatile components within the ink evaporate, leaving the pigment or dye remaining clinging to the inside of each cavity. One group of premium papers having such porosities are formed by coating a heavy plain paper with a fine layer of clay. Premium papers with these clay coatings are printed using the “2,2” print mode.

Another type of premium paper has a slightly glossy appearance and is formed by coating a plain paper with a swellable polymer layer. Upon receiving ink, the coating layer swells. After the water or other volatile components in the ink composition have evaporated, the coating layer then retracts to its original conformation, retaining the ink dyes and pigments which are the colorant portions of the ink composition. This swellable type of media is printed with a “2,3” print mode. Another type of media which falls into the premium category is pre-scored greeting card stock, which is a heavy smooth paper without a coating. However, the heavy nature of the greeting card media allows it to hold more ink than plain paper before the greeting card stock begins to cockle (referring to the phenomenon where media buckles as the paper fibers become saturated, which can lead to printhead damage if the media buckles high enough to contact the printhead). Thus, greeting card stock may be printed with a heavier saturation of ink for more rich colors in the resulting image, than possible with plain paper. The print mode selected for greeting card stock is designated as “2,4”.

The third major category used by the determination system is photographic media. The various photo medias studied this far typically have a polymer coating which is hydroscopic, that is, the coating has an affinity for water. These hydroscopic coatings absorb water in the ink, and as these coating absorb the ink they swell and hold the water until it evaporates, as described above with respect to the slightly glossy premium media. The Gossimer paper which has a print mode selection of “3,0” is a glossy media, having a swellable polymer coating which is applied over a polymer photobase substrate, which feels like a thick plastic base. Another common type of photo media is a combination media, which has a print mode of “3,1”. This combination media has the same swellable polymer coating as the Gossimer media, but instead, the combination media has this coating applied over a photo paper, rather than the polymer substrate used for Gossimer. Thus, this combination photo media has a shiny polymer side which should be printed as a photo type media, and a plain or dull side, which should be printed under a premium print mode to achieve the best image.

The very glossy photo media which is printed according to print mode “3,2” is similar to the Gossimer media. The very shiny media uses a plastic backing layer or substrate like the Gossimer, but instead applies two layers of the swellable polymer over the substrate, yielding a surface finish which is much more glossy than that of the Gossimer media.

The final major media type studied were transparencies, which have not been studied beyond the two major categories described with respect to the basic media determination system , specifically, HP transparencies or non-HP transparencies. Further research may study additional transparencies to determine their characteristics and methods of distinguishing such transparencies from one another but this study has yet to be undertaken.

Before returning to discussion of the determination method , it should be noted that the various print modes selected by this system do not affect the normal quality settings, e.g., Best, Normal, Draft, which a user may select. These Best/Normal/Draft quality choices affect the speed with which the printer operates, not the print mode or color map which is used to place the dots on the media. The Best/Normal/Draft selections are a balance between print quality versus speed, with lower quality and higher speed being obtained for draft mode, and higher quality at a lower speed being obtained for the Best mode. Indeed, one of the inventors herein prefers to leave his prototype printer set in draft mode for speed, and allow the media determination system to operate to select the best print mode for the type of media being used.

For example, when preparing for a presentation and making last minute changes to a combination of transparencies for overhead projection, premium or photo media for handouts, and plain paper for notes which the presenter is using during a speech, all of these images on their varying media may be quickly generated at a high quality, without requiring the user to interrupt the printing sequence and adjust for each different type of media used. Indeed, the last statement assumes that the user may have the sophistication to go into the software driver program screen and manually select which type of media has been placed in the printer's supply tray . Unfortunately, the vast majority of users do not have this sophistication, and typically print with the default plain paper print mode on all types of media, yielding images of acceptable, but certainly not optimum print quality which the printer is fully capable of achieving if the printer has information input as to which type of media is to be printed upon. Thus, to allow all users to obtain optimum print quality matched to the specific type of media being used, the advanced media determination system is the solution, at least with respect to the major types of media and the most popular specific types which have thus far been studied.

6. Weighting and Ranking Routine

Before delving into the depths of the major and specific media type determination routines , a weighting and ranking routine will be described with respect to FIG. . This weighting and ranking routine is performed during the quality fit step of the verification routine . The specific type of assumption signal is first received by a find error step . The find error step refers to a subtable of the type characteristics table . The subtable contains the average or reference values for each spatial frequency, for each specific media type that has been studied. The find error step then compares the value of the spatial frequency measured with the reference value of that spatial frequency with each of the values for a corresponding frequency stored in table for each media type, and during this comparison generates an error value, that is, the difference between the frequency value measured versus the value of the corresponding frequency for each media type. The resulting error signals are sent to a weight assigning step .

The weight assigning step then refers to another subtable of the look-up table . The subtable stores the standard deviation which has been found during study at each spatial frequency for each type of media. The assigning step then uses the corresponding standard deviation stored in table to each of the errors produced by step . Then all of the weighted errors produced by step are ranked in a ranking step . After the ranking has been assigned by step , the ranking for each media type are summed in the summing step . Of course, on this first pass through the routine, no previous values have been accumulated by step .

Following the summing step , comes a counting step , or the particular frequency X under study is compared to the final frequency value n. If the particular frequency X under study has not yet reached the final frequency value n, the counting step issues a NO signal . The NO signal has been received by an incrementing step , where the frequency under study X is incremented by one (“X=X+1”). Following step , steps through are repeated until each of the frequencies for both the spatial reflectance and the diffuse reflectance have been compared with each media type by step , then assigned a weighting factor according to the standard deviation for each frequency and media type by step , ranked by step , and then having the ranking summed in step .

Upon reaching the final spatial frequency N, the counting step finds that the last frequency N has been reached (X=N) and a YES signal is issued. Upon receiving this YES signal , a selection step then selects the specific type of media by selecting the highest number from the summed ranking step . This specific type is then output as signal from the verification block . It is apparent that this weighting and ranking routine may be used in conjunction with various portions of the determination method to provide a more accurate guess as to the type of media entering the printzone .

During the weighting and ranking routine , for a standard letter-size sheet of media analyzing both the specular and diffuse readings for a given sheet of media, a total of 84 events are compared for both the specular and diffuse waveforms for each media type. It is apparent that, while the subject media entering the printzone has been compared to each media type by incrementing the frequency, other ways could be used to generate this data, for instance by looking at each media type separately, and then comparing the resulting ranking for each type of media rather than incrementing by frequency through each type of media. However, the illustrated method is preferred because it more readily lends itself to the addition of new classifications of media as their characteristics are studied and compiled.

Each component of the pre-stored Fourier spectrum for each media type has an associated deviation which was determined during the media study. The standard deviations stored in the look-up table of FIG. 19 are preferably arrived at by analyzing the spectra over many hundreds of data scans for many hundreds of pages of each specific type of media studied. The difference between each component of the fresh sheet of media entering the printzone and each component of the stored signatures is computed in the find error step of FIG. . The ratio (“x′) of the error to the standard deviation is then determined. If this ratio is found to be less than two (x<2), the error is then weighted by a factor of one (1). If this ratio is found to be between two and three (2<×3), then the error is weighted by a factor of two (2). If this ratio is found to be greater then three (x>3), then the error is weighted by a factor of four (4). This “weighting” of step then takes into account the statistical set for each of the characterized media types which have been studied. In the illustrated embodiment, the media type with the lowest weighted error is assigned a ranking of three (3) points. The media type with the second lowest error is assigned a ranking of two (2) points, and the media type with the third lowest error is given a ranking of one (1) point, as shown in FIG. .

The media type having the highest sum of the ranking points across all of the specular and diffuse frequency components is then selected as the best fit for characterizing the fresh sheet of media entering the printzone . The select print mode routine then selects the best print mode, which is delivered to the printing routine where the corresponding rendering and color mapping is performed to generate an optimum quality image on the particular type of media being used.

7. Major Category & Specific Type

Media Type Determination Routines

Having dispensed with preliminary matters, our discussion will now turn to the major category determination and the specific type determination routines and . This discussion will cover how the routines and are interwoven to provide information to multiple verification and select print mode steps, ultimately resulting in printing an image on the incoming sheet of media according to a print mode selected by routine to produce an optimum image on the sheet, in light of the available information known. FIGS. 20-23 together describe the major category and specific type determination routines and .

Referring first to FIG. 20, the massage data routine is shown as first supplying the specular and diffuse spatial frequency data and to a match signature step . Step receives an input signal from a major category look-up table . Table contains both specular and diffuse spatial frequency information for a generic glossy finish media and a generic dull finish media. The term “generic” here means an average or a general category of information, basically corresponding to a gross sorting routine. The match signature routine then compares the incoming massaged data for both the specular and diffuse reflectances and with the reference values from table , and then produces a match signal . In a comparison step , the question is asked whether the incoming matched data corresponds to media having a dull finish. If it does, a YES signal is issued to a plain paper, premium paper, or a matte photo branch routine . The photo branch routine issues an output signal , which is further processed as described with respect to FIG. 22 below. However, if the dulled determination step determines that the match signature output signal is not dull, a NO signal is issued to a photo or transparency decision branch .

The photo or transparency branch sends a data signal carrying the massaged specular and diffuse spatial frequency data and to another match signature step . A second major category look-up table supplies an input to the second match signature step . The data supplied by table is specular and diffuse spatial frequency information for two types of media, specifically a generic photo finish media, and a generic transparency media. The match signature step then determines whether the incoming data corresponds more closely to a generic photo finish data, or a generic transparency data according to a gross sorting routine. An output of the match signature step is supplied to a comparison step , which asks whether the match signature output signal corresponds to a transparency. If not, a NO signal is issued to a glossy photo or a matte photo branch .

However, if the match signature output corresponds to a transparency, then the comparison step issues a YES signal . For the yes transparency signal is received by a ratio generation step . In response to receiving the YES signal , the ratio generation step receives the average specular (A) signal , and the average diffuse (B) signal from the massage data routine . From these incoming signals and , the ratio generation step then generates a ratio of the diffuse average to the specular average (B/A) multiplied by to convert the ratio to a percentage, which is supplied as a ratio output signal . In a comparison step , the value of the ratio signal is compared to determine if the ratio B/A as a percentage is less than a value of 80 per cent (with the “%” sign being omitted in FIG. 20 for brevity). If not, the comparison step issues a NO signal to the glossy photo or matte photo branch .

Thus, the average specular and diffuse data are used as a check to determine whether the transparency determination was correct or not. If the ratio that the diffuse averaged to the specular average is determined by step to be less than 80, a YES signal is then supplied to a verification step . The verified step may be performed as described above with respect to FIG. . During this verification routine, an assumption is made according to step that the media in the printzone is a transparency, and if the verification routine determines that it indeed is, a YES signal is issued. The YES signal is received by a select transparency mode step , which issues a transparency print signal to initiate a transparency step . The print mode selected by step corresponds to a “4,0” print mode, here selecting the default value for a transparency.

If a Hewlett-Packard transparency is identified, as described above with respect to FIG. 13, then a custom print mode may be employed for the specific HP transparency media, as described above with respect to the basic media determination system , resulting in a “4,1” print mode. If the verification step determines that the media in the printzone is not a transparency, then a NO signal is issued. Upon receiving the NO signal , a select default step chooses the default premium print mode, and issues a print signal . Upon receiving signal , a print step then prints upon the media according to the generic premium media print mode “2,0”.

FIG. 21 begins with the glossy photo or matte photo branch from FIG. 20, which issued an output signal , carrying through the massaged specular and diffuse spatial frequency data (S and D) signals and . This input signal is received by a determination step which determines whether the incoming data corresponds to a specific type of glossy media or a specific type of matte photo media. To accomplish this, a specific media look-up table provides an input signal to the determination step . Table contains reference data corresponding to the specular and diffuse spatial frequencies corresponding to various types of glossy photo media and matte photo media, illustrated in table as “glossy A”, “glossy B”, and so on through “matte A”, “matte B”, and so on. Several types of glossy photo media and matte photo media were described above with respect to Table 2.

Once the determination step finds a suitable match from the values stored in table , an output signal is issued to a comparison step . The comparison step asks whether the incoming signal is for a matte photo media. If so, a YES signal is issued. The YES signal is then delivered to the plain paper/premium paper/matte photo branch , as shown in FIGS. 20 and 22. If the comparison step finds that the output of determination step does not correspond to a matte photo, then a NO signal is issued. The NO signal delivers the specular and diffuse spatial frequency data to another determination step . Step determines which specific type of glossy photo media is entering the printzone using data received via signal from a glossy photo look-up table . While tables and are illustrated in the drawings as two separate tables, it is apparent that the determination step could also query table to obtain glossy photo data for each specific type.

After step determines which specific type of glossy photo media is in the printzone , a signal is issued to a verification routine which proceeds to verify the assumption as described above with respect to FIGS. 18 and 19. If the verification routine finds that the determination step is correct, a YES signal is issued to a select specific glossy photo print mode step . The selection step generates a print mode signal which initiates a print step . The printing step then prints upon the sheet of glossy photo media using the print mode corresponding to the selected media, here according to “3,0” print mode for Gossimer media, a “3,1” print mode for the combination media, and a “3,2” print mode for the very glossy photo media.

If the verification routine finds that the determination step was wrong regarding the specific type of glossy photo selected, a NO signal is issued. In response to receiving the NO signal , a select default step selects a generic glossy photo print mode and issues signal to a print step . The print step then prints upon the media according to a generic print mode, here selected as “3,0” print mode.

Travelling now to FIG. 22, we see the plain paper/premium paper/matte photo branch receiving an input signal from FIG. 20, and another input signal from FIG. . Both signals and carry the specular and diffuse spatial frequency data for the media entering printzone . In response to receiving either signal or , the branch issues an output signal carrying the spatial frequency data to a match signature routine . The match signature routine reviews reference data received from a look-up table where data is stored for a generic dull finish media and a generic matte photo finish media. When the matching step has completed analyzing the incoming data with respect to the data stored in table , an output signal is issued.

A comparison step reviews the output signal to determine whether the matching step found the incoming media to have a matte finish. If not, the comparison step issues a NO signal which is delivered to a plain paper/premium paper branch . In response to receiving the NO signal , branch issues an output signal which transitions to the last portion of the major and specific type determination routines , shown in FIG. . Before leaving FIG. 22 we will discuss the remainder of the steps shown there.

If the comparison step determines that the matching step found the incoming media to have a matte finish, a YES signal is issued. A determination step receives the YES signal , and then determines which specific type of matte photo media is entering the printzone . The determining step receives a reference data signal from a matte photo look-up table , which may store data for a variety of different matte photo medias. Note that while table is shown as a separate table, the determination step could also consult the specific media look-up table of FIG. 21 to obtain this data. Note that for the purposes of illustration, data is shown in both tables and for a “Matte A” and “Matte B” media, to date the characteristics for only a single matte photo media has been identified, and further research is required to generate reference data to allow identification of other types of matte photo media.

Following the completion of the determination step , an output signal is issued to a verification routine . If the verification routine determines that the correct type of matte photo media has been identified, a YES signal is issued. In response to the YES signal , a selecting step chooses which specific matte photo print mode to use, and then issues a signal to a printing step . The printing step then uses a “2,1” print mode when printing on the incoming sheet. If the verification routine finds that the determination step was in error, a NO signal is issued. A selecting step responds to the incoming NO signal by selecting a default matte photo print mode. After the selection is made, step issues an output signal to a printing step . In the printing step , the media is then printed upon using the default print mode, here a “2,0” print mode which corresponds to the default print mode for premium paper in the illustrated embodiment.

Turning now to FIG. 23, the plain paper/premium paper branch is shown issuing an output signal which includes data for both the specular and diffuse spatial frequency of the media entering the printzone . In response to receiving signal , a matching step compares the incoming data with reference data received via a signal from a look-up table . The look-up table stores data corresponding to a generic plain finish media, and a generic premium finish media. The matching step then decides whether the incoming data more closely corresponds to a plain paper media, or a premium paper and issues an output signal . In a comparison step , the question is asked whether the output of the matching step corresponds to a premium paper. If not, then a NO signal is issued to a determination step .

The determination step uses reference data received via a signal from a plain paper look-up table . The look-up table may store data corresponding to different types of plain paper media which have been previously studied. Once the determination step decides which type of plain paper is entering the printzone, an output signal is issued. A verification routine receives the output signal and then verifies whether or not the sheet of media entering the printzone actually corresponds to the type of plain paper selected in the determination step . If the verification step finds that a correct selection was made, a YES signal is issued to a selecting step . In the selecting step , a print mode corresponding to the specific type of plain paper media identified is chosen, and an output signal is issued to a printing step . The printing step then prints on the incoming media sheet according to a “0,1” print mode.

If the verification step finds that the determination step was in error, a NO signal is issued to a selecting step . In the selecting step , a default plain paper print mode is selected, and an output signal is issued to a printing step . In the printing step , the incoming sheet of media is printed upon according to a “0,” default print mode for plain paper.

Returning to the premium comparison step , if the media identified in the match signature step is found to be a premium paper, a YES signal is issued. In response to receiving the YES signal , a determination step then determines which specific type of premium media is in the printzone . To do this, the determination step consults reference data received via signal from a premium look-up table . Upon determining which type of specific premium media is entering the printzone , the determination step issues an output signal . Upon receiving signal , a verification step is initiated to determine the correctness of the selection made by step . If the verification step determines that yes indeed a correct determination was made by , a YES signal is issued to a selecting step . The selecting step then selects the specific premium print mode corresponding to the specific type of premium media identified in step . After the selection is made, an output signal is issued to a printing step . The printing step then prints upon the incoming sheet of media according to the specific premium print mode established by step , which may be a “2,2” print mode corresponding to premium media having a clay coating, a “2,3” print mode corresponding to a plain paper having a swellable polymer layer, or “2,4” print mode corresponding to a heavy greeting card stock, in the illustrated embodiments.

If the verification step finds that the determination step was in error, a NO signal is issued to a selecting step . In the selecting step , a default premium print mode is selected and an output signal is issued to another printing step . In the printing step , the incoming sheet of media is printed upon according to a default print mode of “2,0”.

8. Operation of the Media Sensor

The next portion of our discussion delves into one preferred construction of the media sensor (FIG. 2) and the differences between the advanced media type detection system and the earlier basic media type determination system .

The basic media determination system only uses the diffuse reflectance information. The basic system extracted more information regarding the unique reflectance properties of media by performing a Fourier transform on the diffuse data. The spatial frequency components generated by the basic method characterized the media adequately enough to group media into generic categories of (1) transparency media, (2) photo media, and (3) plain paper. One of the main advantages of the basic method was that it used an existing sensor which was already supplied in a commercially available printer for ink droplet sensing. A more advanced media type determination was desired, using the spatial frequencies of only the diffuse reflectance with sensor was not adequate to uniquely identify the specific types of media within the larger categories of transparency, photo media and plain paper. The basic determination system simply could not distinguish between specialty media, such as matte photo media, and premium media. To make these specific type distinctions, more properties needed to be measured, and in particular properties which related to the coatings on the media surface. The manner chosen to gather information about these additional properties was to collect the specular reflectance light ′, as well as the diffuse reflectance light .

In the advanced media sensor uses a blue-violet LED which has an output shown in FIG. 3 as graph . In graph , we see the blue-violet LED has a peak amplitude output at about 428 nanometers. The output also extends down to approximately 340 nanometers, into the ultraviolet range past the end of the visible range, which is around 400 nanometers, with a dominant wavelength of 464 nanometers. While the illustrated peak wavelength of 428 nanometers is shown, it is believed that suitable results may be obtained with an LED having a peak wavelength of 400-430 nanometers.

The short wavelength of the blue-violet LED serves two important purposes in the collecting raw data routine . First, the blue-violet LED produces an adequate signal from all colors of ink including cyan ink, so the sensor may be used for ink detection, as described in U.S. Pat. No. 6,036,298, recited in the Related Applications section above. Thus, the diffuse reflection measured by photodiode of sensor may still be used for performing pen alignment. The second purpose served by the blue-violet LED is that the shorter wavelengths, as opposed to a 700-1100 nanometer infrared LED, is superior for detecting subtleties in the media coding, as described above with respect to Table 2.

FIG. 24 shows the media sensor scanning over the top two millimeters of a sheet of media entering the printzone . Here we see an incoming beam generating a specular reflectance beam which passes through the field stop window to be received by the specular photodiode ′. A second illuminating beam of light is also shown in FIG. 24, along with its specular reflectance beam . As mentioned above, recall that the specular beam has an angle of reflection which is equal to the angle of incidence of the illuminating beam, with respect to a tangential surface of the media at the point of illumination. The sheet of media is shown in FIG. 24 as being supported by a pair of cockle ribs and , which project upwardly from a table-like portion of the platen or pivot . The cockle ribs , support the media in the printzone , and provide a space for printed media which is saturated with ink to expand downwardly between the ribs, instead of upwardly where the saturated media might inadvertently contact and damage the printhead.

Some artistic license has been taken in configuring the views of FIGS. 24-26, and with respect to the orientation of the media sensor . The cockle ribs and are orientated correctly to be perpendicular to the scan axis ; however, the LED and sensors , ′ are oriented perpendicular to their orientation in the illustrated embodiment of printer . FIG. 4 shows the desired orientation of the media sensor in printer with respect to the XYZ coordinated axis system.

As the incoming sheet of media rests on the ribs , peaks are formed in the media over the ribs, such as peak , and valleys are also formed between the ribs, such as valley . The incoming beam impacting along the valley has an angle of incidence , and the specular reflected beam has an angle of reflection , with angles and being equal. Similarly, the incoming beam has an angle of incidence , and its specular reflected beam has an angle of reflection , with angles and being equal. Thus, as the incoming light beams , are moved across the media as the carriage moves the media sensor across the media in the direction of the scanning axis , the light beams , traverse over the peaks , and through the valleys which causes the specular reflectance beams and to modulate with respect to the specular photodiode ′. Thus, this interaction of the media with the cockle ribs , on the media support platen generates a modulating set of information which may be used by the advanced determination method to learn more about the sheet of media entering the printzone .

9. Energy Information

Information to identify an incoming sheet of media may be gleaned by knowing the amount of energy supplied by the LED and the amount of energy which is received by the specular and diffuse photodiodes ′, . For example, assume that the media in FIG. 24 is a transparency. In this case, some of the incoming light from beam passes through the transparency as a transmissive beam . Thus, the amount of energy left to be received by the diodes and ′ is less than for the case of plain paper for instance. In between the plain paper and the transparency paper is the reflectance of the glossy photo media, which has a shinier surface that yields more specular energy to be received by diode ′, than a diffuse energy to be received by photodiode .

These differences in energy are shown in Table 3 below and provide one way to do a gross sorting of the media into three major categories.

Furthermore, by knowing the input energy supplied by the blue-violet LED , and the output energy received by the specular and diffuse sensors and ′, the value of the transmittance property of the media may be determined, that is the amount of energy within light beam which passes through media sheet (see FIG. ). The magnitude of the transmittance is equal to the input energy of the incoming beam , minus the energy of the specular reflected beam and the diffuse reflected beam, such as light in FIG. . After assembly of the printer , during initial factory calibration, a sheet of plain paper is fed into the printzone , and the amount of input light energy from the LED is measured, along with the levels of energy received by the specular and diffuse sensors ′ and . Given these known values for plain paper, the transmittance for photo paper and transparency media may then be determined as needed. However, rather than calculating the transmissivity of photo papers and transparency media, the preferred method of distinction between plain or premium paper, photo paper and transparency media is accomplished using the information shown in Table 3.

Thus in the case of a transparency, the majority of the diffuse energy travels directly through the transparency, with any ink retention layer coating over the transparency serving to reflect a small amount of diffuse light toward the photodiode . The shiny surface of the transparency is a good reflector of light, and thus the specular energy received by photodiode ′ is far greater than the energy received by the diffuse photodiode . This energy signature left by these broad categories of media shown in Table 3 may be used in steps and of the determination system . The energy ratios effectively dictate the magnitude of the frequency components. For a given diffuse and specular frequency, the energy balance may be seen by comparing their relative magnitudes.

10. Media Support Interaction Information

As mentioned above with respect to FIG. 24, interaction of the media with the printer's media support structure, here the pivot, may be used to gather information about the incoming sheet of media. In other implementations, this information may be gathered in other locations by supporting the media sensor with another printing mechanism component, and backing the media opposite the sensor with a component having a known surface irregularity which imparts a degree of bending to the media, as well as changing the apparent transmissivity of the media. For instance, in plotters using media supplied in a continuous roll, a cutter traverses across the media following a print job to sever the printed sheet from the remainder of the supply roll. The sensor may be mounted on the cutter carriage to traverse the media, although such a system may require the leading edge of the incoming sheet to be moved rearwardly into a top-of-form position under the printheads following scanning. Indeed, in other implementations, it may be desirable to locate the media scanner remote from the printzone , such as adjacent the media supply tray, or along the media path between the supply tray and the printzone , provided that the media was located between the sensor and a backing or support member having a known surface irregularity opposite the media sensor .

In the illustrated printer , the cockle ribs and generate a modulating signature as the sensor passes over peaks and valleys on the media sheet . The degree of bending of the media sheet over the ribs and is a function of the media's modulus of elasticity (Young's Modulus). Thus, the degree of bowing in the media sheet may be used to gather additional information about a sheet entering the printzone .

For example, some premium media have the same surface properties as plain paper media, such as the greeting card media and adhesive-backed sticker media. However, both the sticker media and the greeting card media are thicker than convention plain paper media so the bending signatures of these premium medias are different than the bending signature of plain paper. In particular, the spatial frequency signatures are different at the lower end of the spatial frequency spectrum, particularly in the range of 1.4 to 0.1 cycles per inch. In this lower portion of the spatial frequency spectrum, lower amplitudes are seen for the thicker premium media as well as for glossy photo and matte photo medias. Thus, the signature imparted by the effect of the cockle ribs , may be used to distinguish premium media and plain paper, such as in steps of the determination system . It is apparent that other printing mechanisms using different media support strategies in the printzone , other than ribs and or other configurations of media support members may generate their own unique set of properties which may be analyzed to impart a curvature to the media at a known location (S) and this known information then used to study the degree of bending imparted to the different media types.

11. Surface Coating Information

While the effect of the cockle ribs , is manifested in the lower spatial frequencies, such as those lower than approximately 10 cycles per inch, the effect of the surface coatings is seen by analyzing the higher spatial frequencies, such as those in the range of 10-40 cycles per inch. FIG. 25 illustrates a coated sheet of media , having a backing sheet or substrate and a coating , such as an ink retention layer of a swellable material, or of a porous material, several examples of which are discussed above with respect to Table 2. In FIG. 25, we see one incoming light beam which travels through the coating layer and the substrate , and is reflected off of the rib as a specular reflected beam . Another incoming beam from the blue-violet LED is shown generating three different types of reflected beams: (1) a group of diffuse beams which are received by the diffuse sensor , (2) an upper surface reflected specular beam which is received by the specular sensor ′, and (3) a boundary layer specular reflected beam which is formed when a portion of the incoming beam goes through the coating layer and reflects off a boundary defined between the substrate and the coating layer . This boundary may also be considered to be the upper surface of the substrate layer .

The characteristics provided by the boundary reflected beam may be used to find information about the type of coating which has been applied over the substrate layer . For example, the swellable coatings used on the glossy photo media and the slightly glossy premium media described above with respect to Table 2 are typically plastic polymer layers which are clear, to allow one to see the ink droplets trapped inside the ink retention layer . Different types of light transmissive solids and liquids have different indices of refraction, which is a basic principle in the study of optics. The index of refraction for a particular material, such as glass, water, quartz, and so forth is determined by the ratio of the speed of light in air versus the speed of light in the particular media. That is, light passing through glass moves at a slower rate than when moving through air. The slowing of the light beam entering a solid or liquid is manifested as a bending of the light beam at the boundary where the beam enters the media, and again at the boundary where the light beam exits the optic media. This change can be seen for a portion of the incoming light beam . Rather than continuing on the same trajectory as the incoming beam , beam is slowed by travel through the coating layer and thus progresses at a more steep angle toward the boundary layer than the angle at which the incoming beam encountered the exterior surface of coating layer . The angle of incidence of the incoming beam is then equal to the angle of reflection of the reflected beam with respect to the boundary layer . As the reflected beam exits the coating layer , it progresses at a faster rate in the surrounding air, as indicated by the angle of the remainder of the reflected beam .

Now that the index of refraction is better understood, as the ratio of the speed of light in air versus the speed of light in a particular medium, this information can be used to discover properties of the coating layer . As mentioned above, “dispersion” is the change in the index of refraction with changes in the wavelength of light. In plastics, such as the polymer coatings used in the glossy photo media and some premium medias, this dispersion increases in the ultra-violet light range. Thus, the use of the blue-violet LED instead of the blue LED advantageously accentuates this dispersion effect. Thus, this dispersion effect introduces another level of modulation which may be used to distinguish between the various types of glossy photo media as the short wavelength ultra-violet light (FIG. 3) accentuates the change in the angle of the exiting beam , and this information is then used to distinguish specific photo glossy medias. This modulation of the dispersion may be used in step of the media determination system .

Note in FIG. 24, that the transmissive beam has been drawn with a bit of artistic license, in the fact that the angle of incidence has been ignored as the transmissive beam is shown going straight through the sheet , although it is now better understood that a more correct illustration which show a steeper path through the sheet of media than through the surrounding air. Before moving on, one further point should be noted concerning the effect of the ribs , on the information collected by the media sensor . FIG. 24 shows the transmissive beam travelling through the sheet of media between ribs and , whereas FIG. 25 shows an incoming beam being reflected off of rib as the specular reflected beam . While the media shown in FIG. 25 is a coated substrate, even plain paper will reflect light off of the ribs as shown for beam . Thus, more light is seen by the specular sensor ′ when the sensor passes over a rib , then the amount of light received when the sensor passes through a valley between the ribs. The lower energy received when traversing a valley is due to the fact that not all of the energy supplied by the incoming beam is reflected to sensor ′ at , because some of the incoming energy passes through the media in the form of the transmissive beam . Thus, the variations in energy levels received by the specular sensor ′ varies with respect to the presence or absence of ribs , .

FIG. 26 illustrates two other methods by which the various types of media may be classified using the determination system . In FIG. 26 we see a multi-layered sheet of media , which has a backing or substrate layer and a clear swellable coating layer . Here we see a substrate layer which has a rough surface, forming a rough boundary between the coating layer and the substrate . Depending upon at which point an incoming beam of light impacts the boundary layer , the resulting reflected specular beam has a high modulation as the beam traverses over the rough boundary layer as moved by carriage parallel to the scanning axis . The media in FIG. 26 has a rough backing layer, whereas the illustrated media in FIG. 25 has a backing layer which performs a smooth internal boundary . As described above with respect to Table 2, Gossimer media has a swellable polymer coating which is applied over a polymer photo substrate, with the substrate having a smooth surface more resembling media of FIG. . The very glossy media which has two layers of a polymer coating over a plastic backing substrate also has a smooth boundary layer as shown in FIG. . However, the combination photo media has the same polymer coating as the Gossimer media, but this coating is applied over a photo paper, which may have rougher boundary more closely resembling boundary layer in FIG. . Thus, this information about the boundary layer may be used to distinguish between specific types of photo media, such as in step (FIG. 21) of the determination system .

The other phenomenon that may be studied with respect to FIG. 26 is the characteristics of the specular beam reflecting off of the upper surface of the coating layer . In FIG. 26, an incoming light beam is shown reflecting off of an upper surface of the coating layer , to produce a specular reflected beam . As mentioned above, the ink retention layers formed by coatings, such as coating are clear layers, which are typically applied using rollers to spread the coating over the substrate . In the medias under study thus far, it has been found that different manufacturers use different types of rollers to apply these coating layers . The uniqueness of each manufacturer's rollers imparts a unique signature to the upper surface of the coating layer . That is, during this coating application process, the rollers create waves or ripples on the surface , as shown in FIG. . These ripples along the coating upper surface have low magnitude, high frequency signatures which may be used to distinguish the various glossy photo media types.

Alternatively, rather than looking for specific modulation signatures in the specular spatial frequency graph, the ripples formed in the upper surface also impart a varying thickness to the ink retention layer . This varying thickness in the coating layer produces changes in the boundary reflected beam , as the incoming beam and the reflected beam traverse through varying thicknesses of the ink retention layer . It should be noted here, that the swellable coatings on the photo medias, such as the Gossimer media, the combination media, and the very glossy photo media experience this rippling effect along the coating upper surface . In contrast, the porous coatings used on the premium medias, such as the matte photo media, or the clay coated media are very uniform coatings, having substantially no ripple along their upper surfaces, as shown for the media sheet in FIG. . Thus, the surface properties of the coatings may be used to distinguish the swellable coatings which have a rippled or rough upper surface from the porous premium coatings which have very smooth surface characteristics. The one exception in the premium category of Table 2 is the slightly glossy media which has a swellable ink retention layer like coating of FIG. 26, but which is applied over a plain paper. This slightly glossy media having a swellable ink retention layer (IRL) applied over plain paper may be distinguished from media having a swellable IRL over photo paper by comparing the rough nature of the plain paper and with the smoother surface of the photo paper at the boundary layer in FIG. . Alternatively, the peaks and valleys formed by ribs and may be used to make this distinction, knowing that the photo paper substrate is stiffer and bends less than the plain paper substrate when traveling through the printzone , yielding different reflectance signatures.

Another advantage of using the ultra-violet LED , is that refraction through the polymer coating layers , increases as the wavelength of the incoming light beams decreases. Thus, by using the shorter wavelength ultra-violet LED (FIG. ), the refraction is increased. As the thickness of the coating thickens, or the index of the refraction varies, for instance due to composition imperfections in the coating, the short wavelength ultra-violet light refracts through a sufficient angle to move in and out of the field of view of the specular sensor ′. As shown in FIGS. 4, and -, the specular field stop has the window oriented with the minor axis aligned along a central axis of the sensor . Thus, the specular field stop provides a very small field of view in the axis of illumination, which is shown parallel to the page in FIGS. 24-26. Thus, this modulation of the specular reflected beams , and is more acutely sensed by the specular photodiode ′ as these beams move in and out of the field stop window .

12. Raw Data Analysis

Now it is better understood how the advanced media determination system uses the data collected by the media sensor , several examples of raw data collected for various media types will be discussed with respect to FIGS. 27-33. The next section will discuss the resulting Fourier spectrum components which are generated from this raw data in the massaging data routine .

FIG. 27 shows the raw data collected during routine for the very glossy photo media. Here we see the specular data curve . FIG. 27 also shows a diffuse curve . FIG. 28 shows the raw data for a glossy photo media, and in particular Gossimer, with a specular data being shown by curve , and the diffuse data being shown by curve . FIG. 29 shows the raw data for a matte photo media, with the specular data being shown as curve , and the diffuse data shown as curve . FIG. 30 shows the raw data for a plain paper media, specifically Gilbert® bond media, with the specular data being shown as curve , and the diffuse data being shown as curve . FIG. 31 shows the raw data for a premium media, with the specular data being shown as curve , and the diffuse data being shown as curve . FIG. 32 shows the raw data for HP transparency media, with the specular data being shown as curve , and the diffuse data being shown as curve . FIG. 33 shows the raw data for a generic transparency media, with the specular data being shown as curve , and the diffuse data being shown as curve .

As described above with respect to Table 2, the very glossy photo media has two layers of a swellable polymer applied over a plastic backing substrate layer, resembling the media in FIG. . The specular curve of the very glossy photo media (FIG. 27) has much greater swings in amplitude than the specular curve for the glossy (Gossimer) photo media of FIG. 28 due to the double polymer coating layer on the very glossy media. Thus, the specular curves and may be used to distinguish the very glossy photo media from glossy photo media, while the diffuse and are roughly the same magnitude and shape, although the very glossy photo media curve has a slightly greater amplitude than the glossy photo media diffuse curve .

In comparing the curves of FIGS. 27 and 28 with the matte photo curves of FIG. 29, it can be seen that the specular reflectance curve for the photo media resides at a much lower amplitude than either of the photo media specular curves and . Moreover, there is less variation or amplitude change within the matte photo specular curve , which is to be expected because the porous coating over the matte photo substrate, which is a paper substrate, has a much smoother surface than the swellable coatings applied over the glossy and very glossy photo media, as discussed above with respect to FIGS. 25 and 26. The diffuse curve for the matte photo media is of similar shape to the diffuse curves and for the very glossy and glossy photo medias, although the amplitude of the matte photo diffuse curve is closer to the amplitude of the very glossy diffuse curve .

FIG. 30 has curves and which are very different from the curves shown in FIGS. 27-29. One of the major differences in the curves of FIG. 42 versus the curves of FIGS. 27-29 is that the specular curve is lower in magnitude than the diffuse curve , which is the opposite of the orientations shown in FIGS. 27-29 where the specular curves , and are of greater amplitude than the diffuse curves , and , respectively. Indeed, use of the relative magnitudes of the specular and diffuse curves of FIGS. 27-30 has been described above with respect to Table 3. Another significant difference in the plain paper curves - is the similarity in wave form shapes of the specular and diffuse curves , . In FIGS. 27-29, there is a vast difference in the shapes of the specular curves , and versus the diffuse curves , and .

FIG. 31 shows the reflectances for a premium media. While the premium specular and diffuse curves and most closely resemble the plain paper curves and of FIG. 30, they can be distinguished from one another, and indeed they are in the match signature step of FIG. 23. A close examination of the specular curves and shows that the premium specular curve is much smoother than the plain paper specular curve . This smoother curve is to be expected due to the smoother IRL surface coating on the premium media versus the rougher non-coated plain paper.

At this point it should be noted that the relative magnitudes of the specular and diffuse curves may be adjusted to desired ranges by modifying the media sensor . For instance, by changing the size of the field stop windows and , more or less light will reach the photodiode sensors ′ and , so the magnitude of the resulting reflectance curves will shift up or down on the reflectance graphs -. This magnitude shift may also be accomplished through other means, such as by adjusting the gain of the amplifier circuitry. Indeed, the magnitude of the curves may be adjusted to the point where the specular and diffuse curves actually switch places on the graphs. For instance in FIG. 31, by downsizing the specular field stop window , the magnitude of the specular curve may be dropped from the illustrated 475-count range to a position closer to the 225-count range. Such a change in the field stop size or the amplifier gain would of course also affect the other reflectance curves in FIGS. 27-30 and -.

FIGS. 32 and 33 show the reflectances of an HP transparency media with a tape header , and a transparency media without a tape header, respectively. FIG. 32 shows a specular curve and a diffuse curve . FIG. 33 shows a specular curve , and a diffuse curve . In both FIGS. 32 and 33, the specular curves and lie above the diffuse curves and . However, the magnitude of the signals received by the transparency with reflective tape in FIG. 32 are much greater than the magnitudes of the transparency without the reflective tape in FIG. 33, which is to be expected due to the transmissive loss through the transparency without tape, leaving less light to be received by sensors and ′ when viewing a plain transparency.

Besides the relative magnitudes between the graphs of FIGS. 32 and 33 there is a vast difference in the diffuse waveform and , although the specular waveforms have roughly the same shape, with the location of ribs , being shown at wave crest in FIGS. 32 and 33. Regarding the diffuse waveforms and , the HP transparency media with the tape header has a relatively level curve because the undersurface of the tape is reflecting the incoming beams back up toward the diffuse sensor . The diffuse waveform of FIG. 33 is more interesting due to the transmissive loss experienced by the incoming beam, such as beam in FIG. 24, losing energy in the form of the transmissive beam leaving less energy available to reflect off the media surface upwardly into the diffuse sensor . Indeed, the locations of the valleys between ribs and are shown at point in FIG. 33, and the ribs are shown at point .

Another interesting feature of the media support structure of printer is the inclusion of one or more kicker members in the paper handling system . These kickers are used to push an exiting sheet of media onto the media drying wings . To allow these kicker members to engage the media and push an exiting sheet out of the printzone, the platen is constructed with a kicker slot, such as slot shown in FIG. . As the optical sensor transitions over slot , the transmissive loss caused by beam increases, leaving even less light available to be received by the diffuse sensor , resulting in a very large valley or canyon appearing in the diffuse waveform at location .

Thus, from a comparison of the graphs of FIGS. 27-33, a variety of distinctions may be easily made to separate the various major categories of media by merely analyzing the raw data collected by sensor .

. Spatial Frequency Analysis

To find out more information about the media, the massage data routine uses the raw data of FIGS. 27-33 in steps and to generate the Fourier spectrum components, such as those illustrated in FIGS. 34-39. In steps and , the massage data routine generated the curves shown in FIGS. 27-33. FIGS. 34 and 35 show the Fourier spectrum components for the diffuse reflection and the specular reflection, respectively, of a premium media, here the matte photo media. FIGS. 36 and 37 show the Fourier spectrum components for the diffuse reflection and the specular reflection, respectively, of a premium media, here the very glossy photo media. FIGS. 38 and 39 show the Fourier spectrum components for the diffuse reflection and the specular reflection, respectively, of a premium media, here the plain paper media, specifically, Gilbert® bond.

In comparing the graphs of FIGS. 34-39, remember to compare the values for the diffuse reflection with the other diffuse reflection curves (FIGS. 34, and ) and to compare the specular reflection curves with other specular reflection curves (FIGS. 35, and ). For instance, to distinguish between the matte photo media and the very glossy photo media, the frequency of 10 cycles per inch for the specular curves of FIGS. 35 and 37 may be compared. In FIG. 35, the matte photo has a frequency magnitude of around 10 counts as shown at item number in FIG. . In comparison, in FIG. 37 for the very glossy photo media, the frequency magnitude at a spatial frequency of 10 cycles per inch is nearly a magnitude of 42 counts, as indicated by item number in FIG. .

A better representation of the Fourier spectrum components for five basic media types is shown by the graphs of FIGS. 40 and 41. In the graphs of FIGS. 40 and 41, the various data points shown correspond to selected frequency magnitude peaks taken from generic bar graphs like those shown in FIGS. 34-39 for the Fourier spectrum components. Thus, the points shown in the graphs of FIGS. 40 and 41 represent maximum frequency magnitudes corresponding to selected spatial frequencies up to 40 cycles per inch, which comprises the useful data employed by the advanced determination system . In FIGS. 40 and 41, selected spectrum components are shown for five generic types of media: plain paper media, premium media, matte photo media, glossy photo media, transparency media, each of the graphs in FIGS. 40 and 41 has a left half corresponding to low spatial frequency values, toward the left, and high frequency spatial values toward the right, with the border between the low frequency and high frequency portions of each graph occurring around 10 or 20 cycles per inch

Now that the roadmap of the media determination method has been laid out with respect to FIGS. 15-23, as well as the intricacies of the manner in which information is extracted from the media with respect to FIGS. 24-39, the interrelation between the roadmap and these intricacies will be described. Indeed, to draw on the roadmap analogy, the various branches in the major category determinations and specific type determinations of FIGS. 20-23 may be considered as branches or forks in the road, with the various schemes used to make these determinations considered to be points of interest along our journey.

Table 4 below lists some of our various points of interest and destinations where our journey may end, that is ending by selecting a specific type of media.

The graphs of FIGS. 40-43 have been broken down into four quadrants, with generic diffuse spatial frequency graphs of FIGS. 40 and 42 having: (1) a first drant which has a low frequency and high magnitude, (2) a second drant which has a high frequency and high magnitude, (3) a third drant which has a low frequency and low magnitude, and a fourth drant which has a high frequency and low magnitude. The generic specular spatial frequency graphs of FIGS. 41 and 43 have four quadrants: (1) a first drant which has a low frequency and a low magnitude, (2) a second quadrant which has a high frequency and high magnitude, (3) a third quadrant which a low frequency and high magnitude, and a fourth quadrant which has a high frequency and low magnitude.

By comparing the data for the various types of media shown in the graphs of FIGS. 40-43, the determinations made in operations #3-10 of Table 4 may be determined. Other more basic data as described earlier is used to determine whether an incoming sheet of media is a transparency (Δ), with or without a tape header as described earlier, according to operations #1 and #2 of Table 4. Table 5 below shows which quadrant of which graph is used to determine the media types of operations #3-10 of Table 4.

In the third operation (#3) of Table 4, the distinction between glossy photo media and matte photo media may be made by examining the data in quadrant of FIG. 40, or in quadrants and of FIG. . In FIG. 40, the magnitude of the matte photo spatial frequencies (X) are greater than the magnitude of the glossy photo spatial frequencies (⋄). Perhaps even better than FIG. 40, the difference is shown in FIG. 41 for the specular spatial frequencies, where we find the matte photo spatial frequencies (X) falling within quadrant , and the glossy photo (⋄) spatial frequencies falling in quadrant . Thus, while the information supplied by the diffuse sensor may be used to make a determination between glossy and matte photos, as shown in FIG. 41, a much clearer distinction is made using the data collected by the specular sensor ′, as shown with respect to FIG. .

In operation #4 of Table 4, the method distinguishes between plain paper versus premium paper versus matte photo. This distinction may be accomplished again using the data in quadrant of FIG. . In quadrant , we see the matte photo (X) spatial frequencies are far greater in magnitude than the plain paper (□) spatial frequencies, and the premium paper (∘) spatial frequencies. Thus, the selection of matte media in operation #4 is quite simple.

In operations #5 and #6 of Table 4, the characteristics of plain paper and premium paper are compared. Referring to the diffuse spatial frequency graph of FIG. 40, the premium paper (∘) spatial frequencies appear in quadrant , whereas the plain paper (□) spatial frequencies appear in quadrant .

Following operation #6 of Table 4, a sheet of media entering the printzone has been classified according to its major category type: transparency (with or without a header tape), glossy photo media, matte photo media, premium paper, or plain paper. Note that in the original Table 2 above, matte photo was discussed as a sub-category of premium medias, but to the various characteristics of matte photo media more readily lend themselves to a separate analysis when working through the major category and specific type determination routines and , as illustrated in detail with respect to FIGS. 20-23.

Following determination of these major categories, to provide even better results in terms of the image ultimately printed on a sheet of media, it would be desirable to make at least two specific type determinations. While other distinctions may be made between specific types of media, such as between specific types of plain paper (FIG. 23, table ) in practice so far, no particular advantage has been found which would encourage different printing routines for the different types of plain paper media because basically, of the plain paper medias studied thus far, they all provide comparable results when printed upon according to a plain paper default print mode (“0,0”), as shown in step of FIG. . However, if in the future it becomes desirable to tailor print routines for different types of plain paper, the method has been designed to allow for this option, by including steps and to allow for tailored plain paper print modes (FIG. ). Two of the major categories, specifically matte photo and glossy photo lend themselves better to specific type media determinations, allowing for different print modes.

The specific type determinations will be made according to the data shown in FIGS. 42 and 43. Thus, operations #7 and #8 of Table 4 are used to distinguish matte photo medias having swellable coatings from those having porous coatings. The matte photo (X) data from FIGS. 40 and 41 has been carried over into FIGS. 42 and 43. The matte photo data depicted with the X's in FIGS. 40-43 is for a swellable coating, or ink retention layer (“IRL”). The specular frequencies for a matte photo media with a porous coating or IRL is shown in FIGS. 42 and 43 as ▴. While the specular data of FIG. 43 could be used to distinguish the matte photo swellable coatings (X) from the porous coatings (▴), the diffuse data shown in quadrant lends itself to an easier distinction. In quadrant , we see the swellable coating matte photo (X) spatial frequencies as having a magnitude greater than the matte photo porous coated media (♦). Thus, the information in quadrant best lends itself for making the determination of operations #7 and #8 in Table 4.

The other desired specific type media distinction is between glossy photo media (Gossimer) and very glossy photo media (double polymer IRL coatings). While the diffuse data of FIG. 42 could be used to determine the distinction between the very glossy media () and the glossy Gossimer media (*), an easier distinction is made with respect to the specular data shown in FIG. . As shown in quadrant , the very glossy () specular frequencies have a greater magnitude than the glossy Gossimer (*) spatial frequencies. Thus, the data shown in quadrant allows for the distinctions made in the ninth and tenth operations #9 and #10 of Table 4.

Two-Stage Media

Determination System

In implementing the advanced media determination system of FIGS. 15-23, it occurred to the inventors that there may be a way to increase the speed of the routine , allowing users to receive their hardcopy output faster after initiating a print job. Since the vast majority of users most often use plain paper (even people printing photographic images on photo paper typically run a sheet of plain paper through first to proof the print job before printing the final version on more expensive photo media), it would be desirable to be able to quickly identify the plain paper in a single scanning pass of sensor , then employ a detailed multi-pass scanning routine to more accurately identify the other media types. FIG. 44 illustrates such a two-stage media determination system constructed in accordance with the present invention, which may be used in conjunction with the advanced media determination system of FIGS. 15-23, to accomplish these objectives.

The two-stage media determination system includes a first or preliminary sorting stage , and a second or detailed follow-up sorting stage . In the first sorting stage , in an optimization step the LED of sensor is optimized in intensity for reading plain paper . In the preferred embodiment, this optimization step merely uses the brightness previously determined during a standard calibration sequence which occurs upon printing a pen calibration sheet, such as occurs routinely after replacement of one of the inkjet pens -, although a custom calibration for the incoming sheet may be employed as described in further detail below with respect to the second stage . Following the optimization step , in a single sweep step , the carriage traverses once in a single sweep across the printzone , with the sensor collecting both specular and diffuse data during this single sweep. In a comparison step , both the specular and diffuse data are analyzed to determine whether they are within range of the sensors and ′ to determine whether a good set of readable and interpretable specular and diffuse data was found in the single sweep step . If indeed, both the specular and diffuse data are within range, a YES signal is generated and provided as an input to a match signature and select print mode step . The match signature and select print mode step then proceeds according to the media determination system as described with respect to FIGS. 15-23, eventually resulting in a print step, represented collectively as print step , which may include any of the print steps , , , , , , , , or .

Returning to the top of FIG. 44, if the range comparison step finds that the specular and/or diffuse data is not within a useable range, a NO signal is issued to initiate the second sorting stage of the two-stage media determination system . The second stage provides for separate optimal gathering of specular and diffuse data, which may be collected in either order, but here are illustrated with the diffuse data being collected first. While the first stage may take on the order of five seconds from step through an ultimate printing step, labeled collectively as print step , progression through both the first and second stages to an ultimate printing step may take on the order of 10-20 seconds, but may result in a more accurate set of data being collected, as a portion of the collecting raw data step , than may be available on a single pass sweep of step .

In the two-stage media sorting system , in the first stage , the intensity of the light source, here the blue-violet LED , is optimized for plain paper in a manner similar to the turning on and brightness adjustment step of FIG. . Preferably the LED intensity is adjusted to allow the signals generated by both the specular and diffuse reflectances ′, reflected from an incoming sheet to fall within the mid-span range of the analog-to-digital (A/D) converter, which, as mentioned above, has a near-saturation level on the order of five volts. The illustrated A/D converter is within the controller , and during data acquisition this A/D converter is enabled to acquire the output signals of the specular and diffuse photodiodes ′, .

Thus, if the data gathered during a single sweep step has saturated the A/D converter, then the second stage is initialized upon receiving the NO signal . In the illustrated embodiment, a calibrating step begins in response to the NO signal to recalibrate the LED for the particular type of media entering the printzone . To carry out the calibrating step , the sensor first takes a “peek” or quick look at the incoming media. Preferably, the carriage moves the sensor to a location along the printzone where a maximum diffuse brightness may be measured. This maximum brightness location will depend on the configuration of the media support platen, and may be empirically determined by the printer designer using a trial and error method, which in the illustrated embodiment resulted in a location near one of the cockle ribs , . Once the carriage is at the desired location, the brightness of the LED is gradually increased in a step-wise fashion from zero (the off condition) until the A/D converter is saturated. Once the saturation brightness is determined, the brightness of the LED is reduced at least one step to arrive at a maximum brightness value for measuring diffuse data on the particular type of media entering the printzone . To increase the chance of gathering useable data on the next pass, the calibrating step may then reduce the LED brightness another increment below this new maximum value, which in the illustrated embodiment is a 5% reduction to a value of 95% of the maximum brightness value just determined. Following LED calibration , in a scanning and data collection step , the carriage carries the sensor across the incoming media while sensor collects data concerning the diffuse reflectance beam at this 95% LED brightness value.

Following the scanning and collecting step , in a comparison step it is determined whether the diffuse data is within the range of the A/D converter. If the data is still saturating the A/D converter, a NO signal is issued. Then in a checking step , it is determined whether the brightness of the LED is at a minimum value, such as a floor of 12% of the maximum value found in step . If the LED is not at this minimum level, a NO signal issued. In a brightness reduction step , in response to receiving signal , the brightness of the LED used in the previous scan is reduced by 10% in intensity, and the scanning and collecting step is repeated.

Steps , , and repeat if the data is beyond the range of the A/D converter, with the reduction step reducing the brightness of LED in 10% increments from the value used in the last iteration, until this value falls below a selected level, here selected as 55% of the maximum value found in step . Upon dropping below this 55% threshold, then the reduction step reduces the intensity of LED to 25% of the maximum value found in step . If after another scan and collect step is performed, the NO signal is again issued, then the brightness of the LED is reduced to 12% of the maximum value found in step .

If following the scanning and collecting step at a 12% brightness level, upon again reaching the comparison step , since 12% in the illustrated embodiment has been selected as the minimum level, a YES signal is generated. The YES signal then activates a select default print mode step . In the illustrated embodiment, the default print mode corresponds to generic plain paper print mode, corresponding to step in FIG. 23, resulting in a print step , which correlates with the “print (“0,0”)” print mode of step in FIG. .

If during one of the passes through steps -, the comparison step determines that the collected data is within a useable range, then a YES signal is issued. In response to the YES signal , a specular data collection routine is initiated. As mentioned above, the specular and diffuse data collection routines of the second stage may occur in either order, or they may occur simultaneously if processing capabilities permit. The specular data collection portion of the second stage may proceed in much the same way as the diffuse data collection routine of steps -. Here for the specular data gathering, a calibration step begins in response to the YES signal and finds the maximum intensity for the LED in exactly the same manner as described above for the diffuse calibration in step . Note that in some implementations, differing locations along the printzone may be empirically found to generate maximum specular and diffuse reflectance values for use in steps and . Once this maximum specular brightness without saturating the A/D converter is found, the calibration step then reduces the LED to 95% of this maximum before moving on to a first try at a scanning and collecting specular data step .

Following this initial specular LED calibration of step , the scanning and collecting step is performed with the carriage traversing the optical sensor across the printzone to collect specular data in step . Following this data collection step , a comparison step then determines whether the specular data collected is in range, that is, whether a good signal which did not saturate the A/D converter was obtained. If not, a NO signal is issued and in a checking step , it is determined whether the intensity of the LED is at a minimum level, here selected as 12% of the maximum value found in step . If the LED is not at the selected minimum brightness, a NO signal is generated to a brightness reduction step .

In the illustrated embodiment, the brightness of the LED is reduced in the same increments as described above for the diffuse data LED brightness reduction . It is apparent that different steps in LED brightness reduction may be made to collect the diffuse and specular data, although testing has indicated that good results are obtained by making the illustrated intensity step reductions. In the illustrated embodiment, the minimum LED level is 12%, and when this level is found by the checking step , a YES signal is issued. In response to the YES signal , the select default print mode step is activated as described above, resulting in selection of the plain paper print mode in the illustrated embodiment, terminating the method with print step .

The reason for the gradual reduction of the LED brightness in steps and is that more accurate, larger amplitude data is obtained with the maximum illumination intensity, provided that the A/D converter is not saturated so the data is useless. Thus, better resolution is obtained by using the maximum brightness of LED to generate stronger signals for the specular and diffuse sensors ′, . Furthermore, use of the two-stage media determination system advantageously allows for a quick look for plain paper in the single sweep step , which may also advantageously result in generating good useable data in some instances for determining other types of media, such as photo media, speeding printing. Activation of the second stage advantageously allows for highly accurate data collection for the specialty medias, resulting in media signatures with greater resolution being passed onto the media determination system , as indicated by steps and in FIG. .

As mentioned above, if only the first stage is used, in current implementations, a print job may begin within five seconds after the print job is initiated, in contrast to a wait on the order of 10-20 seconds for detailed media analysis by the second stage . Thus, if plain paper is screened during the first stage in the majority of cases, printing occurs in ½ to ¼ of the time required for specialty media identification using the multi-pass second stage . Indeed, the first stage may also be referred to as a “single pass sensor mode,” with the second stage being referred to as a “multi-pass sensor mode.” That is, at a minimum the second stage steps may be: the calibration step , the scanning and collecting step , the comparison step , followed by issuance of a YES signal , the calibrating step followed by the specular scan and data collection step , and finally the comparison step issuing a YES signal . In the slowest operation of the illustrated second stage , the diffuse data may be repeatedly scanned through repetition of steps , , and over a total of seven different LED brightness. Following collection of the diffuse data in the slowest operation of the illustrated two-stage method , the specular data may then be collected in a similar seven step process by repetition of steps , , , and through the same, or different, LED intensity reductions, before eventually resulting in either a YES signal or a default YES signal to initiate printing.

Educatable Media

Determination System

While the printer manufacturers may develop automatic media identification systems for the more common types of media as described above, it would be desirable to have a media identification system which is educatable or teachable, to identify new media categories introduced by a user. For example, some users may have specialized stationery, or some regions may favor particular types of media, such as a talc-coated media often used in India and surrounding regions. Another older type of media used with manual typewriters was referred to in the United States as “onion skin,” and it is conceivable that some users may have a supply of onion skin on hand which they wish to use with their inkjet printers. While the basic and advanced media identification systems , described above are centered around identifying currently popular groups of media for inkjet printers, it would be desirable to have an inkjet printer which is capable of identifying other specialized types of media, and applying a best matched print mode consistently to these uncharacterized types of media when they are continually encountered.

FIG. 45 illustrates one form of an educatable or learning media identification system , constructed in accordance with the present invention, which a user may teach how to identify new types of print media and then print on this new type of media with a selected print mode when encountered in the future. In a starting step , a user starts the “teach mode” method, preferably by interaction with a personal computer or host interface, which may be a portion of the printer driver circuitry or supplied as a special software upgrade application. Alternatively, the printer may be equipped with a special teach mode button, or other user interface which a user selects to perform the start step . For the purposes of discussion, the illustrated embodiment of the educatable media identification system will be described in terms of a software application run on a user's personal computer or host computer, which generates display screens having instructions and various selections available for a user to choose. It is apparent to those skilled in the art that the particular computer display screen configuration may take on a variety of different forms which may be used to implement the educatable media identification method .

Following the starting step , the system includes an acquiring step , where the signature of the custom media of interest is acquired. The acquiring step has two basic steps, first a collecting step , which is followed by a processing step . Preferably, the user interface or display screen instructs the user to load a selected number of sheets of the custom media into the input tray of the printer . In the illustrated example, the collecting step indicates that raw data should be collected for “X” custom sheets, with the X being selected as sheets for the purposes of discussion. It is apparent that if a greater number of sheets is used for the raw data collection step , better results may be obtained, while the use of fewer sheets may also be beneficial to generate a reliable signature, although increased reliability will be obtained by generating a signature based on a greater number of sample sheets.

After a user signals the printer that the custom media is loaded for test, the printer then picks and scans each sheet and collects the raw data for the test media in step . Preferably, the collecting step is done in a multi-pass sampling routine, similar to that described for the second stage in FIG. . Alternatively, the collecting step may be conducted as described above for the collecting raw data step of FIG. . This collected data is then transferred to the host computer or to the printer controller for processing to form a custom media signature in step .

The processing step processes the collected raw data to form a custom media signature, similar to the signatures generated by the inventors when developing the basic and advanced media determination systems , . Preferably, the processing step performs a Fourier transform on the collected raw data and a data averaging routine, similar to the performing step and the averaging step of FIG. . Alternatively, the processing step may be conducted according to the data massaging step of FIG. 17, where the specular and diffuse reflectance graphs are generated and then converted to the specular and diffuse spatial frequency signatures. Indeed, the reflectance graphs and the spatial frequency charts may both be used in a matching signature and selecting print mode step . The matching and selecting step may operate as described above for the basic and advanced media determination systems , , such as in the match signature steps , , and .

Advantageously, in the educatable media determination system , additional resources beyond those stored within the look-up tables of method may be consulted for reference media signatures. A reference media signature look-up table may include printer look-up tables , which collectively refers to all of the media signatures stored within the advanced system , including look-up tables , , , , , and . Another source of reference media signatures within table may be available on the user's computer, indicated collectively as look-up Table 1016 in FIG. . The reference signatures within table may be stored on the host computer, within the printer driver residing within the host computer, or supplied with the software application being operated from the host computer, which typically today is provided on a CD ROM compact disc storage media. Another source of reference signatures within the look-up table may be within an internet or web based look-up table , which a user's computer may consult automatically, or when directed by the user.

It is apparent that in progressing from the printer look-up tables , to the computer based tables , and then finally to the internet web based tables , that greater flexibility and more selections are available with each step. While the printer look-up tables are restricted in most instances to those available at the time of manufacturing printer , upon purchasing the teachable system as a software upgrade, for instance in the form of a CD ROM, additional signatures may be supplied which were available at the time of recording the software application of method . As new media signatures are identified, the most flexible way for a manufacturer to make these new signatures available to users is by storing them on an internet website in tables , from which a user may download the signatures onto their host computer, or allow their host computer to interactively consult with these reference tables to search for a media signature match.

In one preferred embodiment, the printer controller , whether resident in the printer or in the host computer, on a periodic basis either directly or remotely polls the internet website tables for updates to the signature file and/or for updated print modes, including new color map databases and the like. If newly posted updates are detected by the controller , they are automatically downloaded and appended to all future printjobs to be available to the printer for signature comparison. Updated print modes may replace earlier print modes stored in the printer look-up table .

After the matching step sorts through the various reference media signatures within table , after a given amount of searching either based on time, number of signatures to analyze, or upon completion of consulting all the available reference signatures, in a comparison step , the question is then asked whether step found a reference signature which matches the custom media signature generated in step . If an exact matching signature was not found, then step issues a NO signal , which is delivered to a sample printing step . The sample printing step then prints a variety of different print modes on the custom media, with these print modes being selected from the available reference media signatures stored within table .

If the matching query step determines that step indeed found a match to one of the reference signatures of table , then a YES signal is issued. Preferably, the YES signal activates a showing step , which then displays for the user which matching signature was found. In another querying step , the user is then asked by the software application whether the user approves of the matched signature. For instance, a user may not approve of a signature which erroneously found stationery having reflective fibers within the media to be a transparency. In such a case, the user will then disapprove of the selection and a NO signal will be issued. In response to receiving the NO signal , the sample printing step is activated to print a sample of the various types of print modes available. While these print samples generated by step may be printed with only one sample per sheet of media, most users prefer to have several print samples displayed on a single piece of media, for instance as described in U.S. Pat. No. 6,039,426 for a “Simplified Print Mode Selection Method and Apparatus,” currently assigned to the present assignee, the Hewlett-Packard Company. In a selecting step , the user then examines the print samples generated by the printing step , and through the use of the host computer interface may select a desired print mode. If the user selects a print mode, a YES signal is issued.

Alternatively, if in the querying step , the user approves of the signature match shown in step , then a YES signal is issued. Upon receiving either the YES signal , or the YES signal indicating a user-selected print mode in step , a storing step then stores the matched custom signature and print mode. This storing step may store the matched signature and print mode either within the printer controller , indicated in a storing step , or on the host computer, indicated by a computer storing step . While storing the matched signature on the printer controller in step may slightly speed later computations and matching of the custom media signature, storing of this information on the host computer is also quite feasible. If this media signature and print mode information is stored on the host computer in step , then when initiating all future printing routines, this media signature and print mode information may be downloaded to the printer at the beginning of each print job along with other resource manager information. While downloading this information at the beginning of each print job may seem burdensome or laborious, indeed transmitting all of this information to the printer takes approximately one second or less using current printing and computing technologies.

Following the storing step , in an ending step , the teach mode sequence is ended and a printing step is initiated to performing selected print job on the new custom media, or other print media as identified by the media determination system .

Thus, using the educatable teach mode media determination system , customers are able to teach the printer how to recognize media of their choice, and to assign a selected print mode to this custom media when encountered in the future. The print modes assigned may vary in a variety of different features, such as the amount of ink put down, the color map used, the halftoning routines employed, and the number of print passes used, such as those employing a shingling ink application system. The selected print mode may also contain information about the location of the new media supply. For instance, if a specialized business card sized supply tray, or a snap-shot sized photo media supply tray is used to store the custom media, then the selected print mode instructs the media handling system to pull the next sheet from the specialized supply tray.

In an alternative embodiment, the signature matching step may first look to the printer look-up tables , but if the user does not like any of the print modes on the custom media, then a NO signal is issued. In response to the NO signal , in this optional alternative system, a repeat of the matching step is performed in the repeating step . In this repeat, the matching step may then look to the computer based tables , followed by a repeat of steps , , and possibly or and , followed by another repetition if the user does not select one of the computer based print modes of the repeating step . In this third round, the matching step would then look to a broader base of reference signatures, specifically in the illustrated example, the internet web-based tables . Of course if additional resources were available where reference media signatures may exist, then the repeating step will cause the matching step to increment through these additional media reference signature tables. In the illustrated example, following the internet web-based table matching , the NO step would no longer be available for the user, or the system may increment back through the printer look-up tables , followed by the computer based tables , etc.

In an alternative embodiment, the user may initiate a printer calibration procedure through interaction with the software application for instance. After the printer controller has received new signature and print mode updates, either from the internet tables or from another software upgrade source, such as tables , the user initiates this calibration process. The user first identifies the media type which they desire to use to generate a list of supported media types. Following this selection, the user then loads a selected number of samples of this media which the printer then picks and scans to generate a new custom media signature, as described above for the aquiring step . This new signature is then linked to a color map and print mode that has been delivered via the external source, so in the future when this particular custom media is detected it is immediately mapped to the linked color map and print mode. Thus, the user-initiated teaching mode allows a user to select a desired print mode to match a custom print media, and then to store this match through steps , or where the match is available for future use.

FIG. 46 illustrates an alternate embodiment of an educatable media identification system , constructed in accordance with the present invention, to identify borderline media falling between two known types of print media. In the advanced media determination system described above with respect to FIGS. 15-23, there is no memory within the system for remembering which print mode was used on a previous sheet or sheets. Due to variations between printers and media, it is common to find certain media that have signatures which fall between the reference signatures for two different types of media.

For example, it is common for the properties of a measured unknown new media to be halfway between a printer's definition of plain paper and a specialty or coated paper, such as between plain and premium paper in FIG. . The media determination system needs to make a selection between either premium or plain paper in step , and for this borderline media, the results are inconsistent. For the first sheet in a print job, the printer may determine that it is a premium sheet so the entire job is printed using a premium print mode, while for the next sheet in the stack, the printer may determine the media is a plain paper so the next print job is printed using a plain paper print mode, resulting in different print modes being used on the same media. Thus, the resulting image from print job to print job varies, and users find this printer behavior to be very confusing, resulting in a non-uniform print behavior and varying print quality on a given type of media.

Most users would appreciate consistent printer-to-media use interaction, even though not optimal, for instance if the determination system decides that a piece of premium paper is a plain paper, the plain paper print mode would not be optimal, but the results would be consistent from print job to print job rather than varying print modes from one print job to the next. Most consumers would prefer this consistency from job to job in the overall product. Moreover, besides all of the print jobs having the same appearance or print quality, each page of a job will take approximately the same amount of time to print, instead of printing one job with a faster plain paper print mode, and another job with a slower premium paper print mode. Thus, the consistent printing results even though they may not be the optimal print results, are preferred by most users, rather than oscillating back and forth between two different print modes from print job to print job.

Returning now to FIG. 46, the self-taught media determination system first shows the major category determination step , as including four substeps, where decisions are made between various types of media, with a transparency versus default premium determination being made in step , a glossy versus matte photo (abbreviated as “Matte” in the drawings) determination being made in step , a matte photo versus plain paper versus premium paper determination being made in step , and a premium versus plain paper determination being made in step (see FIGS. and -). The self-taught determination system also dovetails into the specific type media determination step , which has various verifying steps including a glossy photo verification step , a matte photo verification step , a premium media determination step , and a plain paper determination step (see FIGS. and -).

Whenever the advanced media determination system processes through one of the major category determination verifying steps , , or , this data is transmitted via signal to a determination step . Similarly, when the specific media type determination step passes through any of the verifying steps , , or , this data is transmitted via signal to the determining step . The determining step then determines how close the media signature of the verifying steps , , , , , , or is to the reference signatures of the particular verifying step. Following the determination step , a comparison step then activates to determine whether the new media signature is on the borderline between the two sets of reference signatures. For instance, in exercising the determination step , if it is determined that a new media signature is passing through step is on the borderline between being glossy print media and matte print media, then the comparing step issues a YES signal . If the new media signature is not a borderline signature between two groups of reference values, then the querying step issues a NO signal , and in a proceeding step the media determination method then proceeds as described above with respect to FIGS. 15-23.

If the new media signature is on the borderline between two different types or categories of media, then the YES signal initiates a storing step , where the new media signature is stored, along with the print mode selected by the determination system corresponding to this new media in a look-up table . While this self-educating media determination system may be used in conjunction with the user operated teach mode determination system , either through being downloaded from the web, or supplied as the new application on a CD ROM powered by the host computer, or downloaded thereon. Preferably this self-teaching system is supplied along with future releases of the advanced media determination system , and thus is totally transparent to a user. If provided as an upgrade, the look-up table may be stored on the host computer, as described above with respect to step of FIG. . Instead, if the self-teaching system is supplied with new releases of the advanced media determination system , then preferably the look-up table is located within the printer controller .

For the next sheet of media entering the printzone, in an acquiring step , the signature of the next piece of incoming media is collected and processed, such as according to the acquiring media signature step of FIG. 45, perhaps through the use of the second stage data collection step of FIG. . Following acquisition of the signature of the next incoming media in step , a comparing step then compares the signatures of this next sheet of media with the previously stored media signatures residing within the look-up table , as indicated by signal . Following this comparing step , in a querying step , it is asked whether this next media signature matches one of the previous new media signatures stored in table . If the matching step determines that this next sheet of incoming media has a signature which does not match any of the previously stored signatures in table , then a NO signal is issued. In response to the NO signal , the proceeding step is activated, and the advanced media determination system is then continued. If the matching step finds a match between the next media signature and one of the previously stored new signatures within table , then a YES signal is issued.

In response to the YES signal , a selecting step is then issued to select the same print mode for this next incoming sheet as was previously selected and stored within look-up table for an earlier printed sheet. Thus, if in this borderline situation, initiating from the major category determination step determine that the incoming media was plain paper rather than premium paper, then a plain paper print mode is selected, either a default print mode of step , or a specific plain paper print mode of step , as shown in FIG. . Following the selecting step , a printing step occurs, printing on this next sheet of incoming media with either the default plain paper print mode of step , or the specifically selected plain paper print mode of step . If instead the previous sheet determination indicated that a premium print mode was selected according to table , then the selecting step would select a premium print mode, specifically the same print mode selected for the previous sheet, resulting in step being conducted according to either the default premium print mode , or a specific premium print mode of step (FIG. ).

Thus, using the self-teaching media determination system , when a new media signature is read by the sensor , the specific signature just read is stored in the printer's memory or look-up table in the preferred embodiment. When the signature is read on the next incoming sheet, prior to printing according to the advanced determination system of FIGS. 15-23, it will instead be first compared in steps to see whether it is a borderline signature, and if so, then compared in step with the recently stored signatures and print modes in table . If a match is found in the comparison step , then this next incoming sheet of media will be printed according to the same print mode used for the previous sheet, as stored in the look-up table .

Thus, by employing the self-teaching media identification system , stable consistent media detection results from page to page in a given print job are provided in a given printer . In the illustrated example, the signatures stored in table are stored in a temporary memory, which is then erased when the printer is powered off, so the collection of new media signatures would begin again when the printer is turned back on. This occasional clearing of the memory accommodates variations over time in the media sensor , as well as variations in the new borderline media signatures, which may vary from ream to ream for a particular type of media. Alternatively, the value stored within table may be placed in permanent memory which would not be lost during a power down sequence, if such an application proves useful in some implementations. Furthermore, while the look-up table may be structured to carry a single group of media signatures, a more advantageous system might allow several different types of media signatures to be stored within table to accommodate users which switch between several different media types on a routine basis. Allowing for multiple different types of signatures to be stored within table allows the user to receive consistent results on a regular basis when switching between different types of media which they commonly use.

Conclusion

Thus, a variety of advantages are realized using the advanced media determination system of FIGS. 15-23, as well as the advantages realized using the more simple basic determination method of FIG. . Indeed, preferably portions of the basic method of FIG. 8 are incorporated into and used in the advanced detection system , specifically, the identification of a transparency without a header tape. While the basic media determination system was able to sort out photo media from plain paper, and able to distinguish transparencies with and without a tape header, a more advanced media determination system was desired to distinguish between various types of premium paper and various types of photo medias. This desire to identify the various types of premium and photo medias was spurred on by a desire to provide users with photographic quality images. While the current printer drivers do allow users to go into the program and select a specific type of media, it has been found that most users lack the sophistication to enter the program and make these determinations. Often though it is not a matter of lack of sophistication, but users may also suffer from a lack of time to make such a selection, as well as simply not knowing which type of photo media or premium media which they have in their hand to print upon. Whatever the reason, for simplicity of use, an automatic media determination system which selects the optimum print modes for the type of media entering the printzone is desired, and the advance determination system accomplishes these objectives.

Furthermore, use of the media sensor advantageously is both a small compact unit, which is economical, lightweight, and easily integrated into existing printer architectures. Another advantage of the advanced media determination system , and the use of the media sensor , is that the system does not require any special markings to be made on a sheet of media. Earlier systems required the media suppliers to place special markings on the media which were then interpreted by a sensor, but unfortunately these markings would often run into the printed image, resulting in undesirable print artifact defects.

Additionally, the media sensor may also be used for detecting printed ink droplets, to assist in pen alignment routine as described above with respect to the monochromatic sensor described in U.S. Pat. No. 6,036,298, recited in the Related Applications section above. Furthermore, the advanced determination system operates without requiring absolute calibration at the factory for each type of media because the measurements made by the sensor are relative measurements, with the only factory calibration needed revolving around the use of plain paper media, as mentioned above. Thus, a variety of advantages are realized using the advanced media determination system , in conjunction with the illustrated blue-violet media sensor and the educatable media identification system , to provide consumers with a fast, economical, easy to use printing unit, which provides outstanding print quality outputs without user intervention.

A variety of advantages are also realized using the educatable media determination systems, whether the user-activated teach mode system is used, or the self-taught determination system is used. Indeed, both the teach mode system and the self-taught system may be employed together, allowing a user to teach the printer about a specific new type of custom media using the method , or if the particular user lacks the sophistication to implement the teach mode, then the printer can accommodate new or borderline medias by making a best guess, and then applying the same best guess print mode to subsequent sheets of the new type of media. Use of both of the educatable media identification systems and provides users with consistent print modes for custom or borderline print medias.

Moreover, use of the teach mode system allows users to select what they consider to be the best print mode for a type of media to accommodate personal preferences which may vary from those selected by the advanced determination system of FIGS. 15-23, or from the print modes selected by the self-taught system . Furthermore, use of the teach mode system allows customers to upgrade their printers with the ability to recognize new media types over time, whether these new media signatures are introduced through the user's computer and table , or from manufacturer upgradable sources supplied on the internet via web-based tables . When the advanced media determination system was originally developed, the most common types of inkjet media was characterized and sorted into these various major categories and specific types or subsets of the major categories. This initial sorting routine of the advanced system was done to accommodate variations in printers and in the optical sensor . Thus, use of the teach mode identification system allows users to upgrade their particular printer to recognize a specific type of new media and to apply the print mode which a user considers to be the best fit when encountering this custom media in the future.

CLAIMS

1. A method of classifying incoming media entering a printing mechanism, comprising: optically scanning a printing surface of the incoming media to gather specular and diffuse reflectance data; comparing the specular and diffuse reflectance data with known values for different media types to classify the incoming media as one type thereof; generating information about said incoming media during or after said scanning; selecting a print mode corresponding to said one type; and storing said selected print mode and said generated information for the classified incoming media.

2. A method according to claim 1 wherein: the method further includes generating a media signature for the incoming media from the gathered specular and diffuse reflectance data; and said comparing comprises comparing the generated media signature for the incoming media with media signatures for said different media types.

3. A method according to claim 1 wherein: said optically scanning comprises optically scanning a group of incoming media each having substantially identical printing surface characteristics to gather specular and diffuse reflectance data for said group; method further includes generating a group media signature for said group from the gathered specular and diffuse reflectance data; and said comparing comprises comparing the generated group media signature with media signatures for said different media types to classify the group of incoming media as one type thereof.

4. A method according to claim 3 wherein said optically scanning said group of incoming media each having substantially identical printing surface characteristics is initiated by a user.

5. A method according to claim 1 wherein said comparing comprises comparing the specular and diffuse reflectance data with known values stored within a controller portion of the printing mechanism.

6. A method according to claim 1 wherein said comparing comprises comparing the specular and diffuse reflectance data with known values stored within a host computing device in communication with the printing mechanism.

7. A method according to claim 1 wherein said comparing comprises comparing the specular and diffuse reflectance data with known values stored at an internet website accessed by a host computing device in communication with the printing mechanism.

8. A method according to claim 1 wherein said comparing comprises: comparing the specular and diffuse reflectance data with known values stored within a controller portion of the printing mechanism; thereafter if no suitable classification was found, comparing the specular and diffuse reflectance data with known values stored within a host computing device in communication with the printing mechanism; and thereafter if no suitable classification was found, comparing the specular and diffuse reflectance data with known values stored at an internet website accessed by the host computing device.

9. A method according to claim 1 wherein said comparing comprises comparing the specular and diffuse reflectance data with known values stored within a controller portion of the printing mechanism, with known values stored within a host computing device in communication with the printing mechanism, and with known values stored at an internet website accessed by the host computing device.

10. A method according to claim 1 further including determining whether a suitable classification was made during said comparing.

11. A method according to claim 10 further including, when said determining determines that an unsuitable classification was made during comparing, printing samples of available print modes for user selection and classification of the incoming media.

12. A method according to claim 11 wherein said storing comprises storing a user selected print mode and user classification of the incoming media.

13. A method according to claim 10 further including, when said determining determines that a suitable classification was made during said comparing, printing a sample of the print mode corresponding to said one type.

14. A method according to claim 13 further including verifying user approval of the printed sample.

15. A method according to claim 14 further including, following user disapproval during said verifying, printing samples of available print modes for user selection and classification of the incoming media.

16. A method according to claim 15 wherein said storing comprises storing a user selected print mode and user classification of the incoming media.

17. A method according to claim 1 wherein said storing comprises storing a form of the gathered data for the classified incoming media.

18. A method according to claim 17 wherein: the method further includes generating a media signature for the incoming media from the gathered specular and diffuse reflectance data; said comparing comprises comparing the generated media signature for the incoming media with media signatures for said different media types; and said form of storing comprises storing the generated media signature for the incoming media.

19. A method according to claim 1 wherein: said comparing comprises comparing the specular and diffuse reflectance data with known values for previously classified incoming media; and when the incoming media is classified as one of said previously classified incoming media, said selecting comprises selecting the print mode corresponding to said previously classified incoming media.

20. A method according to claim 1 wherein the method further includes updating said known values.

21. A method according to claim 20 wherein said updating comprises updating said known values with known values for additional media types.

22. A method according to claim 20 wherein said updating comprises updating print modes corresponding to at least some of said different media types.

23. A method according to claim 20 wherein said updating comprises updating said known values with new values obtained by a host computing device in communication with the printing mechanism.

24. A method according to claim 20 wherein said updating comprises updating said known values with new values obtained from an internet website accessed by a host computing device in communication with the printing mechanism.

25. A method according to claim 23 wherein said updating occurs automatically without user intervention.

26. A method according to claim 1 further including determining whether the gathered data for the incoming media is between known values for first and second media types, and classifying the incoming media as the first media type.

27. A method according to claim 26 further comprising storing the gathered data and the classification of the incoming media as the first media type.

28. A method according to claim 27 wherein: said comparing comprises comparing the specular and diffuse reflectance data with known values for previously classified incoming media as the first media type; and when the incoming media is classified as the previously classified incoming media which was classified as the first media type, and said selecting comprises selecting the print mode corresponding to the first media type.

29. A method according to claim 1 wherein said optically scanning comprises illuminating the incoming media with a blue-violet light.

30. A printing mechanism, comprising: a frame which defines a printzone; a printhead which prints a selected image on a printing surface of media in the printzone in response to a printing signal; a media sensor which optically scans the printing surface of incoming media entering the printzone to gather specular and diffuse reflectance data; and a controller which compares the specular and diffuse reflectance data with known values for different media types to classify the incoming media as one type thereof, selects a print mode corresponding to said one type, generates the printing signal for the selected image in response to the selected printmode, generates information about said incoming media, and stores said generated information and said selected print mode.

31. A printing mechanism according to claim 30, wherein the controller generates a media signature for the incoming media from the gathered specular and diffuse reflectance data, and compares the generated media signature for the incoming media with media signatures for said different media types.

32. A printing mechanism according to claim 30, wherein in response to user initiation, the controller compiles specular and diffuse reflectance data for a group of incoming media each having substantially identical printing surface characteristics, and generates a group media signature from said compiled data.

33. A printing mechanism according to claim 32, wherein the controller stores the group media signature and the selected printmode corresponding thereto with said known values for comparison with future incoming media signatures.

34. A printing mechanism according to claim 32, the controller compares the group media signature with known values for different media types to classify said group as one media type.

35. A printing mechanism according to claim 32, wherein the controller generates the printing signal to print samples of available print modes for a user to select a group print mode to correspond to said group, and in response to said user selection, the controller stores the group print mode as the selected printmode.

36. A printing mechanism according to claim 30, wherein the known values are stored within the controller which is a portion of the printing mechanism.

37. A printing mechanism according to claim 30, wherein the known values are stored within a host computing device in communication with the controller.

38. A printing mechanism according to claim 30, wherein the known values are stored on an internet website accessed by a host computing device in communication with the controller.

39. A printing mechanism according to claim 38, wherein the known values used by the controller are periodically updated from the internet website.

40. A printing mechanism according to claim 30, wherein the controller determines whether the gathered data for the incoming media is between known values for first and second media types, and classifies the incoming media as the first media type.

41. A printing mechanism according to claim 40, wherein the controller stores the gathered data and the classification of the incoming media as the first media type with said known values for comparison with further incoming media.

42. A method according to claim 30 wherein the media sensor comprises an illuminating element which emits a blue-violet light.

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