Modular sensor systems with elastomeric connectors

ABSTRACT

Described are modular water sensors designed to speed assembly and otherwise improve manufacturability. Various sensors, modules, and cables communicate via connector systems that employ elastomeric conductors to establish and maintain electrical contact between perpendicular wiring-board surfaces. The elastomeric conductors are held in place using easily assembled systems of clips and retainers.

INFORMATION

DETAILED DESCRIPTION OF THE INVENTION

DETAILED DESCRIPTION

The present invention addresses the demand for systems and methods that speed assembly and otherwise improve manufacturability without sacrificing quality or performance. The novel systems and methods are described with reference to modular groundwater sensor assemblies, but are not limited to such systems.

FIGS. 2A-2C depict a wiring board that serves as a connector half in accordance with one embodiment. Wiring board easily attaches to a number of electrical components to provide for external connectivity. FIG. 2A is a plan view of a first surface of wiring board , including a plurality of concentric conductors disposed on an insulating substrate; FIG. 2B is a side view; and FIG. 2C is a plan view of a second surface, including a plurality of conductors electrically connected to conductors by a plurality of vias . A first pair of indentations accept a clip, as noted below, and a second pair of indentations allow clearance for moving wiring board past some protrusions, similar to dimples of FIG. 1, during installation.

FIG. 3 is a plan view of an elastomeric support , a clip in the depicted embodiment, for attaching wiring board to a second wiring board. Clip is of an insulating material, such as DELRIN, and in this embodiment includes a pair of bays , clip ends , a pair of slots , and a hole .

FIG. 4A depicts a connector system in which clip of FIG. 3 is attached to wiring board of FIG. 2; FIG. 4B depicts the same connector system from the side. A length of elastomeric conductor is disposed between clip and the bottom surface of wiring board , and a pair of elastomeric conductors are press fitted into respective bays . Elastomeric conductor conducts electricity in a direction normal to the page and normal to the bottom surface of wiring board , but does not conduct electricity in a direction illustrated as from left to right in FIG. A. Elastomeric conductors conduct electricity in a direction normal to the page and from left to right, but do not conduct electricity normal to the bottom surface of wiring board ; however, elastomeric conductors need not be non-conductive in any direction for purposes of the depicted embodiment. Suitable elastomeric conductors are available from Fujipoli of Cranford, N.J., under the trademark ZEBRA. Elastomeric conductors employing strips of gold wrapper around a silicone substrate are relatively expensive but provide low-impedance, corrosion-resistant contacts. Other flexible, directionally conductive materials might also be used.

Conductors on the top surface of wiring board are concentric to provide rotational contact, but need not be concentric in embodiments that do not support rotational connections. Conductors on the other side of wiring board are not concentric, but can be in other embodiments. For example, clip can be replaced with a support that does not require a particular wiring board orientation; e.g., a support can be attached to the periphery of wiring board or through a hole in the center of wiring board in a manner that allows wiring board to rotate on its axis.

FIGS. 5A and 5B depict alternate sides of a printed circuit board (PCB) adapted for use with connector system of FIGS. 4A and 4B. PCB includes a plurality of pads extending along an edge, each pad corresponding to one of conductors on the second side of wiring board (FIG. C). The opposite side of PCB ′ also includes a plurality of pads . In this embodiment, each pad connects to a corresponding one of pads by way of a corresponding via . The pad configurations on each side of board are bilaterally symmetrical. In this embodiment, traces connect symmetrical pairs of pads so that the symmetry is electrical as well as physical.

FIGS. 6A and 6B depict views of a circuit module , including a pair of PCBs (FIGS. 5A and 5B) mounted to a connector system (FIGS. A and B). Each of a pair of fasteners (e.g., screws or rivets) extends through a hole in boards , a slot in clip , a pair of washers , and a nut . This hardware is fastened so the pads on one side of each board contact elastomeric conductors and . In selecting the materials and arrangement of fasteners , care should be taken to prevent short circuits on the associated wiring boards. In one embodiment in which hole is relatively close to wiring-board traces, washers are of TEFLON.

Returning briefly to FIG. 3, wiring boards with concentric conductors may be fastened to clip via a single fastener through hole and corresponding holes in the associated PCBs. The fastener could be tight enough to provide secure electrical connections but loose enough to allow the wiring board to pivot with respect to the PCBs. Connectors thus formed are self-leveling. In other embodiments, the ones of hole and slots not used to secure boards to clip can support elastomeric conductors that extend between opposing boards in the manner of conductors . Spherical elastomeric conductors might be, suitable for some such embodiments.

In the example of FIGS. 6A and 6B, pads (FIG. 5B) contact the elastomeric conductors, but board might also be flipped over so that pads provide the requisite electrical contact. The physical and electrical symmetry of boards reduce the possibility of assembly errors because boards can be positioned with either side against clip . Boards may provide the same or different functionality.

As noted above, elastomeric does not conduct electricity in a direction from left to right, or vice versa. Pads and are thus connected to respective conductors on the bottom of wiring board but are electrically isolated from one another. Components on wiring board (e.g. IC ) can therefore communicate electrical signals to external components (not shown) via the concentric rings of wiring board (FIG. A). Due to the symmetry of the pads on wiring board , elastomeric can be made to extend across only half of wiring board . Clip can be modified to accommodate the shorter elastomeric. Such connections require a shorter length of elastomeric conductor, and are therefore less expensive.

The second wiring board illustrates how module can be expanded to include more than one PCB. Additional PCBs can likewise be stacked to further increase the amount of board space without appreciably increasing the length or cross-sectional area of module . Support safely and simply interconnects PCBs and wiring board .

FIGS. 7A-7C depict an example of how module can communicate with a sensor housing . Sensor housing might include one or more of a number of types of sensors (not shown), such as those that produce a measure of pressure, temperature, pH, oxidation-reduction potential, dissolved oxygen, specific ion concentrations, or a combination of one or more of these. Whatever the sensor(s), in this example the sensor communicates signals via a pair of wires . Each of wires is soldered or otherwise connected to conductors of a wiring board A similar to wiring board of FIGS. 2A-2C. A circular, insulating retainer disposed across the face of wiring board A includes a slot supporting a length of elastomeric conductor . Elastomeric conductor extends through retainer to make contact with each concentric conductor of wiring board A and with the corresponding concentric conductors on the surface of a second wiring board B, also similar to wiring board of FIGS. 2A-2C.

FIG. 7B depicts the top surface of wiring board B of module and the bottom surface of sensor housing , including retainer and elastomeric conductor . Retainer includes a recess surrounding elastomeric conductor . Recess prevents elastomeric conductor from being overly compressed, and consequently reduces wear and increases the life of elastomeric conductor . The radial symmetry of concentric conductors on wiring board B allows sensor housing and module to rotate relative to one another, during assembly, for example.

FIG. 7C depicts a module housing that rotatably attaches to sensor housing . One or more dimples mate with threads on sensor housing . Dual O-rings provide a watertight seal between sensor housing and module housing . In the depicted embodiment, module housing is conductive, for example, is of stainless steel or titanium. Elastomeric conductors extend from the sides of module to make physical and electrical contact with the inside surfaces of housing when module is installed. Bays , detailed in FIG. 3, hold elastomeric conductor in a shape that facilitate insertion of module into housing . Elastomeric conductors thus connect module to e.g. earth ground or solution ground. Slots , discussed above in connection with FIG. 2A, allow module to bypass interior protrusions formed by one or more dimples , and thus facilitate assembly.

FIGS. 8A and 8B depict a manner of combining a plurality of modules in accordance with another embodiment. FIG. 8A depicts a symmetrical wiring board that includes a number of holes and pads . Similar pads on the opposite side (not shown) are connected to pads using a collection of respective vias . FIG. 8B depicts a multi-module system in which two modules are interconnected using board of FIG. A. Fasteners and respective non-conductive washers extend through holes in modules and holes in board so pads of board provide electrical connection between the corresponding pads on modules . The assembly of FIG. 8B can be soldered, but this is not required. This example shows two modules connected together, but the system may include more or fewer. Further, wiring board need not be reversible or symmetrical, and one or more of vias may be omitted to allow different signals on opposite board traces.

FIG. 9 depicts a wiring board in accordance with an embodiment that includes a split conductor having two electrically isolated portions (the respective conductor on the opposite side is similarly split). The two portions remain electrically isolated until wiring board is brought into contact with another connector half, e.g. another similar wiring board or an elastomeric disk or strip. This embodiment is useful, for example, for modules that include batteries and battery-powered components. One power terminal of the battery module might be connected to the battery-powered components via the split conductor . The battery-powered modules thus remain disconnected from the battery until the system is assembled, advantageously increasing module shelf life. An exemplary embodiment is discussed below in connection with FIG. .

FIG. 10 depicts an embodiment of a retainer supporting a length of elastomeric conductor . Retainer includes a slot supporting elastomeric conductor and a recess allowing conductor to expand under pressure. Quality elastomeric conductors are expensive, so conductor is limited to about half the diameter of an associated wiring-board surface to reduce cost. In other embodiments, a disk of elastomeric material is used in place of retainer and elastomeric conductor .

FIG. 11A depicts an exemplary sensor assembly for use with some embodiments. Sensor assembly has two major components, a conductivity sensor and a protective guard . FIGS. 11B and 11C detail conductivity sensor and protective guard , respectively.

Referring to FIG. 11B, in this example sensor measures the conductivity of e.g. water from a first platinum electrode to a second platinum electrode . Electrodes and are connected to two conductors (FIG. 2) of a wiring board recessed in a connector support . Electrodes and are supported in an insulating rod of e.g. Teflon™ joined to wiring board via connector support and a pin or setscrew . Sensor also includes a plastic band or O-ring and spring , the purposes of which are explained below in connection with FIG. .

Sensor is shown with a plurality of lines representing parallel current paths from electrode to electrode . The shape of current paths depends on the placement of sensor . For example, some of the paths are altered if sensor is placed against the side of a well, and all paths may be changed with bore diameter. Guard (FIG. 1C) is thus designed both to facilitate insertion into a well, protect sensor and provide a fixed cavity that constrains the shape of paths to reduce measurement variations.

Sensor guard includes a window and a hole that together allow the fluid of interest to contact both electrodes and . A pair of internal O-rings forms a watertight seal between the inside of guard and the outside of cylinder . An additional pair of O-ring's and threads mate with a cylindrical component housing (see FIG. and related text).

FIG. 12A is a cross-sectional exploded view of a cable assembly in accordance with one embodiment. Cable assembly includes an end cap , a setscrew , a pair of washers , a pair of O-rings , a band , a cable body , a cable retainer , a wiring board , a retainer , and a piece of elastomeric conductor that extends through a slot (not shown) in retainer . The materials used to form the various components of cable assembly differ for different applications. In one embodiment, cable cap is TEFLON, setscrew , washers , and ring are stainless steel, and cable body is KYNAR. An additional pair of O-rings and threads mate with a cylindrical component housing as explained below in connection with FIG. . Band can be used for decoration or labeling. Cable retainer should not have hard, sharp edges that might damage cable . In one embodiment, retainer is soft polyethylene.

FIG. 12B depicts cable assembly assembled and including a cable . Setscrew is tightened into cable body to compress O-rings against cable , which provides a watertight seal. End cap is then threaded over exposed threads of setscrew . The constituent conductors of cable extend through retainer , loop around and back through retainer , and are soldered to wiring board , wiring board of FIG. 2 in one embodiment. Conventional potting compounds can be added to the cavity in which retainer resides for improved water resistance and cable-pullout strength. External O-rings form a watertight seal with an associated housing, as depicted in FIG. . FIG. 12C depicts setscrew from the perspective of end cap . One end of setscrew includes a pair of flats that mate with a conventional wrench during assembly.

FIG. 13 is an exploded view of a sensor system that includes various components, systems, and modules analogous to ones described above, like-labeled elements being the same or similar. A detailed discussion of above-described elements is omitted here for brevity.

Sensor system illustrates how a pair of modules and can be stacked between cable body and sensor assembly within a housing . When installed, as shown in FIG. 13B, spring of sensor assembly exerts a compressive force on the stack to establish the requisite electrical contact between opposing connectors. Spring may not be required if the various components within the stack are held to close tolerances.

Module is included to show how split ring connector of FIG. 9 is used in accordance with one embodiment. Module includes a button-type battery with a positive terminal connected to component via a pair of split pads, each of which is in electrical contact with split conductor (FIG. ). Due to the split, the positive power-supply terminal of battery remains disconnected from component until the elastomeric conductor of cable body is brought into contact with wiring board . At that time, the center conductor of wiring board (FIG. 2) of cable body provides a path for current between the halves of split conductor , and consequently between the positive power-supply terminal and component .

Other aspects of system are evident in FIG. B. For example, O-ring of sensor assembly is not a seal, but centers connector support within housing ; the elasticity of O-ring allows support to bypass the interior protrusions corresponding to dimples .

The types of connections illustrated herein are illustrative and not limiting. For example, contact between opposing wiring boards may be accomplished without an elastomeric conductor, or with two or more elastomeric conductors. Further, each of the elements described in the foregoing figures can be made from various materials and by various methods. The selection of materials and manufacturing techniques, dictated chiefly by particular applications and economic considerations, are well within the ability of those of skill in the art.

While the present invention has been described in connection with specific embodiments, variations of these embodiments will be obvious to those of ordinary skill in the art. For example, the foregoing connector systems are not limited to ground- or surface-water applications, or even sensor applications. Still other variations will be readily apparent to those of skill in the art. Therefore, the spirit and scope of the appended claims should not be limited to the foregoing description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 (prior art) is an exploded view of a system that can be adapted for monitoring water quality in e.g. lakes, rivers, ponds, tanks, and groundwater.

FIGS. 2A-2C depict a wiring board in accordance with one embodiment.

FIG. 3 is a plan view of an elastomeric support , a clip in the depicted embodiment, for attaching wiring board to a second wiring board.

FIGS. 4A and 4B are front and side views, respectively, of a connector system in which clip of FIG. 3 is attached to wiring board of FIG. .

FIGS. 5A and 5B depict alternate sides of a printed circuit board (PCB) adapted for use with connector system of FIGS. 4A and 4B.

FIGS. 6A and 6B depict views of a circuit module , including a pair of PCBs (FIGS. 5A and 5B) mounted to a connector system (FIGS. A and B).

FIGS. 7A-7C depict an example of how module can communicate with a sensor housing .

FIGS. 8A and 8B depict a manner of combining a plurality of modules in accordance with another embodiment.

FIG. 9 depicts a wiring board in accordance with an embodiment that includes a split conductor having two electrically isolated portions.

FIG. 10 depicts an embodiment of a retainer supporting a length of elastomeric conductor .

FIGS. 11A, B, and C depict an exemplary sensor assembly for use with some embodiments.

FIG. 12A is a cross-sectional exploded view of a cable assembly in accordance with one embodiment.

FIG. 12B depicts cable assembly assembled and including a cable .

FIG. 13 is an exploded view of a sensor system in accordance with one embodiment.

CLAIMS

1. A connector system comprising: a. a first wiring board having: i. a first wiring-board surface supporting a first plurality of conductors; and ii. a second wiring-board surface supporting a second plurality of conductors extending in a first plane; iii. wherein at least one of the first plurality of conductors is electrically connected to a corresponding one of the second plurality of conductors; b. a second wiring board having a third wiring-board; surface supporting a third plurality of conductors extending in a second plane substantially perpendicular to the first plane; c. an elastomeric conductor disposed between the first and second wiring boards in contact with ones of the second plurality of conductors extending in the first plane and ones of the third plurality of conductors extending in the second plane substantially perpendicular to the first plane; and d. a support connected to the first and second wiring boards and holding the elastomeric conductor against the second and third wiring-board surfaces.

2. The connector system of claim 1, wherein the support clips to the first wiring board.

3. The connector system of claim 1, further comprising a third wiring board having a fourth wiring-board surface extending in parallel with the second plane and supporting a fourth plurality of conductors, wherein at least one of the fourth plurality of conductors electrically connects to at least one of the third plurality of conductors via the elastomeric conductor.

4. The connector system of claim 1, wherein the first plurality of conductors are concentric.

5. The connector system of claim 1, wherein the first wiring board further includes recesses receiving the support.

6. The connector system of claim 1, further comprising at least one fastener attaching the support to the second wiring board.

7. The connector system of claim 1, further comprising a second elastomeric conductor disposed against the first plurality of conductors.

8. The connector system of claim 7, further comprising a retainer disposed against the first plurality of conductors and supporting the second elastomeric conductor.

9. The connector system of claim 1, further comprising a housing encompassing the first and second wiring boards.

10. The connector system of claim 9, the housing including an interior protrusion, the first wiring board further comprising recesses providing clearance for bypassing the protrusion.

11. The connector system of claim 9, the housing including an interior protrusion, the first wiring board further comprising recesses providing clearance to bypass the protrusion.

12. The connector system of claim 9, further comprising a second conductor contacting the housing and at least one of the third plurality of conductors.

13. The connector system of claim 9, further comprising a second conductor contacting the housing and at least one of the third plurality of conductors.

14. The connector system of claim 13, wherein the second conductor is elastomeric.

15. The connector system of claim 13, wherein the support holds the second conductor against the housing.

16. The connector system of claim 13, wherein the second conductor is elastomeric.

17. A water monitoring system comprising: a. a cylindrical component housing having a sensor end and a cable end; b. a sensor assembly connected to the sensor end of the housing, the sensor assembly including a connector half; and c. a circuit module disposed within the housing and including: i. a first wiring board having: 1) a first wiring-board surface supporting a first plurality of conductors in physical contact with the connector half of the sensor assembly; and 2) a second wiring-board surface supporting a second plurality of conductors, wherein at least one of the first plurality of conductors is electrically connected to a corresponding one of the second plurality of conductors; ii. a second wiring board having a third wiring-board surface extending in a second plane substantially perpendicular to the first plane and supporting a third plurality of conductors; iii. an elastomeric conductor disposed between the first and second wiring boards in contact with ones of the second and third pluralities of conductors; and iv. a support connected to the first and second wiring boards and holding the elastomeric conductor against the second and third wiring-board surfaces.

18. The connector system of claim 17, wherein the support clips to the first wiring board.

19. The connector system of claim 17, wherein the circuit module further includes a third wiring board having a fourth wiring-board surface extending in parallel with the second plane and supporting a fourth plurality of conductors, wherein at least one of the fourth plurality of conductors electrically connects to at least one of the second and third pluralities of conductors via the elastomeric conductor.

20. The connector system of claim 17, wherein the first plurality of conductors are concentric.

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