Multi-dimensional optical disk

ABSTRACT

The present invention provides an optical disk with pits and/or bumps which each contain a plurality of facets. Each facet of each pit and/or bump is intended for separate read back as an individual ‘side’ of the optical disk (much as vinyl records had two ‘sides’ for separate playback). The separate ‘sides’ of the optical disk formed by separate facets of each pit and/or bump can be read back either simultaneously or serially, either by a corresponding plurality of laser beams, or by a common laser beam which is positioned to a first orientation with respect to a rotating track to focus on a first set of facets of each pit and/or bump, and then repositioned to focus on a second set of facets of the same set of pits and/or bumps and thus to read a second ‘side’ of the optical disk. The technique may be extended to provide a single optical disk and even a single track of the optical disk with even more than two ‘sides’ by using three-, four- or five-sided pyramidal-shaped pits and/or bumps.

INFORMATION

DETAILED DESCRIPTION OF THE INVENTION

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present invention provides an optical disk with tracks which are formed by multi-faceted pits (and/or bumps) which each contain a plurality of facets.

Each pit (or bump) is multifaceted, i.e., they each have at least two sides, e.g., relatively flat and reflective sides. Each side of the pit (or bump), depending upon its shape, represents either a HIGH bit level, or a LOW bit level.

Each facet of each pit and/or bump is intended for individual read back, either separately as individual ‘sides’ of the optical disk (much as the much older technology of vinyl records had two ‘sides’ for separate playback), or substantially simultaneously or serially to provide two bits of data from each pit or bump.

A plurality of laser beams are directed at respective sides of the pit (or bump), one toward a corresponding side of the pit (or bump) on the optical disk to determine a bit condition of each side. The separate facets of the pits or bumps can be read back using the corresponding plurality of laser beams appropriately placed to each measure a reflection or non-reflection of a laser beam from the same facet position of each pit or bump.

Alternatively, a common laser beam can be moveable between positions. A first position places the laser beam in position (e.g., a 0° orientation with respect to the rotation of the track) to measure reflection from a first facet position of each pit or bump as it rotates through a focal point of the laser, and a second position (e.g., a 180° orientation with respect to the rotation of the track) to place the laser beam in an opposite position to measure reflection from a second, opposite facet position of each pit or bump.

Thus, a first ‘side’ of an optical disk can be played by positioning the laser in a first orientation, and then a second ‘side’ of the optical disk can be played without removing the optical disk by repositioning the laser in a second orientation.

The technique and apparatus in accordance with the principles of the present invention may be extended to provide a single optical disk and even a single track of the optical disk with even more than two ‘sides’ by using three-, four- or five-sided pyramidal-shaped pits and/or bumps.

FIG. 1A shows a cross-sectional view of a portion of a track of an optical disk including a plurality of multi-faceted pits, in accordance with the principles of the present invention. FIG. 1B shows a bottom view of the optical disk shown in FIG. 1A (presuming that the pits open toward the bottom of the optical disk).

In particular, in FIGS. 1A and 1B, an optical disk includes a track comprising a plurality of multi-faceted pits -. For instance, a first pit is formed by a triangular-shaped pit having two opposing 45° angled facets , . This pit comprises two bits of data information, e.g., a ‘00’.

A second pit comprising two similarly angled facets , also includes two bits of data information, e.g., a ‘00’.

The third pit includes a first 45° angled facet , but is missing an opposing 45° angled facet and instead includes a 90° facet (i.e., is missing the 45° angled facet). Thus, the third pit indicates, e.g., a ‘01’.

The fourth pit is missing the first 45° angled facet, but includes the opposing 45° angled facet , indicating, e.g., a ‘10’.

The fifth pit includes both opposing 45° angled facets , , indicating, e.g., a ‘00’.

The sixth pit includes only the second 45° angled facet , and thus indicates, e.g., a ‘01’.

The seventh pit shown in FIGS. 1A and 1B is missing both opposing 45° angled facets, indicating, e.g., a ‘11’.

FIGS. 2A to D depict the positioning of two separate laser beams to separately read the individual facets of each multi-faceted pit, in accordance with the principles of the present invention.

In particular, FIG. 2A shows the separate read back of two facets , of a multi-faceted pit including both opposing 45° angled facets , . The two facets , may be simultaneously read by two separate lasers , as shown in FIG. A. Alternatively, a singular laser beam may be repositioned between the position of the first laser beam and the position of the second laser beam to separately read a stream of data bits (one from each pit) comprised in the first facet of a plurality of multi-faceted pits of a track. Then, at a later time, a second ‘side’ of the optical disk can be read by reading a stream of data bits (one from each pit) comprised in the second facet of the plurality of multi-faceted pits of a track.

FIG. 2B shows the separate read back of two facets , of a multi-faceted pit including only a first 45° angled facet , and the absence of a second angled facet indicated by the presence of a 90° lip .

FIG. 2C shows the separate read back of two facets , of a multi-faceted pit including only a second 45° angled facet , and the absence of a first angled facet indicated by the presence of a 90° lip .

FIG. 2D shows the separate read back of two facets , of a multi-faceted pit including neither opposing 45° angled facet indicated by the presence of essentially no pit.

Note that it is desirable to avoid interference in the reception of a reflected laser beam by the opposing laser because of the approximately 90° relationship between laser beams , . One technique is to use lasers of differing wavelengths. Another technique is to laterally rotate the laser beams to avoid direct reflections from impinging on the detector of the opposite laser system. Of course, if a single laser beam is used and repositioned for separate read back of only one set of facets (first or second facets) at a time, interference between separate laser systems will not be a design consideration.

Individual bits are encoded two at a time into two-sided triangular-shaped pits or bumps. Thus, two bits are represented within a single pit or on a single bump. In another embodiment, four-sided pyramidal-shaped pits or bumps are used to encode four bits of digital data within each pyramidal-shaped pit or bump. The technique and apparatus can be implemented using three-sided pyramidal-shaped pits or bumps, five-sided pyramidal shaped pits or bumps, etc., allowing a plurality of bits to be represented within each pit or bump. The plurality of bits in each pit or bump are read back by a corresponding number of laser beams.

Thus, with a same density of pits or bumps used in conventional optical disks, twice the amount of information can be contained within an optical disk using two-sided triangular-shaped pits and two laser beams, or even four times the amount of information can be achieved using four-sided pyramidal-shaped pits or bumps.

In accordance with the principles of the present invention, the multiple sides of each pit or bump may be read by separate laser beams either simultaneously, or in quick sequence allowing greater flexibility in placement of the lasers and corresponding optics. Preferably, the laser beams from the plurality of laser beams are arranged non-orthogonal with respect to the surface of the optical disk

In another embodiment, an optical disk may be made to have a plurality of ‘side’ by changing a direction of a laser beam with respect to the rotation of the optical disk.

For instance, a laser beam may be placed in a 0° orientation with respect to the rotation of the track such that a first side of each pit or bump can be read. In this position, the laser beam will be used to read only one side of each pit or bump.

Thereafter, to read a second ‘side’ of the optical disk, the laser beam is moved to an opposite orientation, e.g., a 180° orientation with respect to the rotation of the track such that a second side of each pit or bump can be read.

FIG. 3 shows that for the same area of contact of the laser beam on the optical disk, the use of multi-faceted pits and/or bumps can result in marked improvements in data density, e.g., a 141% improvement as compared with certain prior art techniques.

In particular, as shown in FIG. 3, because of the 45° angling of the reflective portion of the pit:

α=4χ

β=χ√{square root over (2)}

According, the single laser embodiment (using only one facet of the multi-faceted pit and a single laser beam) improves data density by 141% as follows:

Utilizing the full advantage of the invention by either implementing two laser systems or by implementing a repositionable single laser system, the data density can be improved 282% based on a similarly sized conventional optical disk, shown as follows:

FIG. 4 depicts a track comprising a plurality of multi-faceted pits , , , , each multi-faceted pit - having a four-sided pyramidal shape, in accordance with the principles of the present invention. While FIG. 4 depicts a four-sided pyramidal shape, the principles of the present invention relate equally to other shaped polygonal pits or bumps, e.g., to three-sided, five-sided, etc. pyramidal shaped pits or bumps.

The presence or formation of a particular facet in any pit represents a particular logic level of a data bit, while the absence of a particular facet in any pit represents the opposite logic level of a data bit. Using a four-sided pyramidal shaped pit, each pit can contain four bits of data (i.e., a half byte, or a nibble).

As shown in FIG. 4, the first pit includes all four facets , , , , representing corresponding bits (e.g., a logic ‘0’) of four separate ‘sides’ of the optical disk. Alternatively, the four facets may represent four bits or a symbol in a serial data stream, e.g., ‘0000’.

Similarly, as shown in FIG. 4, the second pit does not include a first facet , but does include the remaining three facets , , . Thus, the second pit might represent the symbol ‘1000’. Likewise, the third pit might represent the symbol ‘0001’, and the fourth pit the symbol ‘0100’.

FIG. 5 shows an example embodiment simultaneously positioning four separate lasers - having four laser beams - adapted to read a reflection or non-reflection from each of four corresponding four facets , , , of a four-sided pyramidal pit, in accordance with the principles of the present invention.

While the four lasers - are shown in simultaneous positioning, the principles of the present invention relate equally to any or all of the four lasers - being positionable in the shown position, with a retreat position allowing operation of the opposing laser. Alternatively, FIG. 5 can be used to depict the approximate orientation of the various lasers - with respect to the traveling direction of the track of the optical disk, depicted by the arrow in FIG. .

If using bump technology, the four laser beams can be arranged to not cross paths. Moreover, it is preferred to angle the facets at 45° with respect to the surface of the optical disk, such that the opposing laser beams will cross orthogonally to one another. To further or alternatively minimize interference between opposing lasers (e.g., between laser # and laser #), lasers of different wavelengths may be implemented.

Note that the distance between any laser and its corresponding facet can be the same for each of the multiple facets of a multiple-facet pit, in accordance with the principles of the present invention.

If a three-sided, four-sided, five-sided, etc. pyramidal pit or bump structure is used in the optical disk, a third, fourth and/or fifth side, respectively, can be read by corresponding re-positioning of the laser beam relative to the side of each pit or bump which is to be read.

Preferably, the shape of each pit or bump will take into account the relationship with the rotation of the track. For instance, when the laser beam is in a 0° or 180° orientation with respect to the rotation of the track, the track will be coming directly at or receding directly from the source of the laser beam, allowing a flat reflective surface to be used as the corresponding side of the pit or bump. However, when the laser beam is in a 90° or 270° orientation to read, e.g., the third and fourth sides of each pit or bump and thus a third and fourth side of the optical disk, the sides may need to be lengthened depending upon the speed of the rotation.

FIG. 6 shows the positioning of two lasers (or the re-positioning of a single laser) to detect the multi-bit information from each multi-faceted bump of a track formed on the surface of an optical disk, in accordance with the principles of the present invention.

In particular, in FIG. 6, a first laser is positioned to measure a first facet position of each bump on an optical laser disk , while a second laser is positioned to measure a second facet position of each bump on the laser disk.

As shown in FIG. 6, the presence of a 45° angled facet in a particular facet position indicates a particular bit level, e.g., a logic ‘1’, while the absence of the 45° angled facet in the particular facet position indicates the opposite bit level, e.g., a logic ‘0’.

While the invention has been described with reference to the exemplary embodiments thereof, those skilled in the art will be able to make various modifications to the described embodiments of the invention without departing from the true spirit and scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present invention will become apparent to those skilled in the art from the following description with reference to the drawings, in which:

FIG. 1A shows a cross-sectional view of a portion of a track of an optical disk including a plurality of multi-faceted pits, in accordance with the principles of the present invention. FIG. 1B shows a bottom view of the optical disk shown in FIG. 1A (presuming that the pits open toward the bottom of the optical disk).

FIGS. 2A to D depict the positioning of two separate laser beams to separately read the individual facets of each pit, in accordance with the principles of the present invention. In particular, FIG. 2A shows the separate read back of two facets of a multi-faceted pit including both opposing 45° angled facets, FIG. 2B shows the separate read back of two facets of a multi-faceted pit including only a first 45° angled facet, FIG. 2C shows the separate read back of two facets of a multi-faceted pit including only a second 45° angled facet, and FIG. 2D shows the separate read back of two facets of a multi-faceted pit including neither opposing 45° angled facet.

FIG. 3 shows that for the same area of contact of the laser beam on the optical disk, the use of multi-faceted pits and/or bumps can result in marked improvements in data density, e.g., a 141% improvement as compared with certain prior art techniques.

FIG. 4 depicts a track comprising a plurality of multi-faceted pits, each multi-faceted pit having a four-sided pyramidal shape, in accordance with the principles of the present invention.

FIG. 5 shows an example embodiment simultaneously positioning four separate lasers having four laser beams adapted to read a reflection or non-reflection from each of four corresponding four facets of a four-sided pyramidal pit, in accordance with the principles of the present invention.

FIG. 6 shows the positioning of two lasers (or the re-positioning of a single laser) to detect the multi-bit information from each multi-faceted bump of a track formed on the surface of an optical disk, in accordance with the principles of the present invention.

FIG. 7 shows a cross sectional view of a conventional optical disk containing a series of pits along a track path.

FIG. 8 shows the bit density in a conventional optical disk, wherein each pit represents a single bit.

CLAIMS

1. An optical disk having a generally planar surface, comprising: a plurality of multi-faceted irregularities forming a data track on said planar surface; and a plurality of facets in each multi-faceted irregularities, each of said plurality of facets being encoded with a data bit by an angling of said facet with respect to a surface of said optical disk; wherein each of said multi-faceted irregularities includes at least two facets.

2. The optical disk having a generally planar surface according to claim 1, wherein: each of said plurality of multi-faceted irregularities comprises a pit.

3. The optical disk having a generally planar surface according to claim 1, wherein: each of said plurality of multi-faceted irregularities comprises a bump.

4. The optical disk having a generally planar surface according to claim 1, wherein: said plurality of multi-faceted irregularities are regularly spaced along said data track.

5. The optical disk having a generally planar surface according to claim 1, wherein: each of said plurality of irregularities contains at least two data bits of information.

6. The optical disk having a generally planar surface according to claim 1, wherein: said optical disk is a compact disk (CD).

7. The optical disk having a generally planar surface according to claim 1, wherein: said optical disk is a digital video disk (DVD).

8. An optical disk having a generally planar surface, comprising: a plurality of multi-faceted irregularities forming a data track on said planar surface; and a plurality of facets in each multi-faceted irregularities, each of said plurality of facets being encoded with a data bit by an angling of said facet with respect to a surface of said optical disk; wherein each of said plurality of facets is adapted for reflection of a separate laser beam.

9. The optical disk having a generally planar surface according to claim 8, wherein: each of said laser beams impinge said irregularity from a different angle.

10. An optical disk having a generally planar surface, comprising: a plurality of multi-faceted irregularities forming a data track on said planar surface; and a plurality of facets in each multi-faceted irregularities, each of said plurality of facets being encoded with a data bit by an angling of said facet with respect to a surface of said optical disk; wherein each of said multi-faceted pits includes at least four facets.

11. An optical disk reading system, comprising: a first laser to present a laser beam to a first facet of each of a plurality of multi-faceted pits of a data track formed in said optical disk; and a second laser to present a laser beam to a second facet of each of said plurality of multi-faceted pits of said data track.

12. The optical disk reading system according to claim 11, wherein: said first laser and said second laser are adapted to present said respective laser beams to each of said plurality of multi-faceted pits substantially simultaneously.

13. The optical disk reading system according to claim 11, wherein: said first laser and said second laser are adapted to present said respective laser beams to each of said plurality of multi-faceted pits substantially serially.

14. The optical disk reading system according to claim 11, wherein: said first laser is a substantially same distance from said first facet as said second laser is from said second facet.

15. An optical disk reading system, comprising: a laser having at least two reading positions; a first reading position of said laser being adapted for presenting a laser beam to a first facet of each of a plurality of multi-faceted pits of a data track formed in said optical disk, said laser beam impinging said first facet from a first angle; and a second reading position of said laser being adapted for presenting said laser beam to a second facet of each of said plurality of multi-faceted pits of said data track, said laser beam impinging said second facet from a second angle different from said first angle.

16. The optical disk reading system according to claim 15, wherein: said laser in said first reading position reads a first stream of data from said plurality of multi-faceted pits; and said laser in said second position reads a second stream of data from said plurality of multi-faceted pits.

17. An optical disk, comprising: a plurality of multi-faceted bumps forming a data track; and a plurality of facets on each multi-faceted bump, each of said plurality of facets being encoded with a data bit by an angling of said facet with respect to a surface of said optical disk; wherein each of said plurality of facets are adapted for reflection of a separate laser beams.

18. An optical disk, comprising: a plurality of multi-faceted bumps forming a data track; and a plurality of facets on each multi-faceted bump, each of said plurality of facets being encoded with a data bit by an angling of said facet with respect to a surface of said optical disk; wherein each of said laser beams impinge said bump from a different angle.

19. The optical disk according to claim 18, wherein: each of said plurality of bumps contain at least two data bits of information.

20. The optical disk according to claim 18, wherein: said optical disk is a compact disk (CD).

21. The optical disk according to claim 18, wherein: said optical disk is a digital video disk (DVD).

22. A method of reading separate data streams from an optical disk, comprising: positioning a laser beam to read a status of a first facet of each of a plurality of pits in a track of said optical disk; and repositioning said laser beam to read a status of a second facet of each of said plurality of pits.

23. The method of reading separate data streams from an optical disk according to claim 22, wherein: said status read by said laser beam relates to an angle of said first facet.

24. A method of reading separate data streams from an optical disk, comprising: reflecting a first laser beam from a first facet of each of a plurality of pits in a track of said optical disk to read a first stream of data bits from said plurality of pits; and reflecting a second laser beam from a second facet of each of said plurality of pits to read a second stream of data from said plurality of pits.

25. Apparatus for reading separate data streams from an optical disk, comprising: means for positioning a laser beam to read a status of a first facet of each of a plurality of pits in a track of said optical disk; and means for repositioning said laser beam to read a status of a second facet of each of said plurality of pits.

26. The apparatus for reading separate data streams from an optical disk according to claim 25, wherein: said status read by said laser beam relates to an angle of said first facet.

27. Apparatus for reading separate data streams from an optical disk, comprising: means for reflecting a first laser beam from a first facet of each of a plurality of pits in a track of said optical disk to read a first stream of data bits from said plurality of pits; and means for reflecting a second laser beam from a second facet of each of said plurality of pits to read a second stream of data from said plurality of pits.

28. A method of reading separate data streams from an optical disk, comprising: providing a first laser beam to read a status of a first facet of each of a plurality of pits in a track of said optical disk, said first facet of each of said plurality of pits comprising a first data stream of said optical disk; and providing a second laser beam to read a status of a second facet of each of said plurality of pits, said second facet of each of said plurality of pits comprising a second data stream of said optical disk.

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