# Patent

## Title
Proximity switch assembly having varying size electrode fingers

## Abstract

A proximity switch is provided having a sensing pad and a proximity sensor disposed near a perimeter of the sensing pad to generate an activation field proximate to the sensing pad. The proximity sensor includes a plurality of interdigitated electrode fingers having differing lengths and spacings. The switch may be integrally formed as a lamp and proximity switch assembly.

## Background
FIELD OF THE INVENTION
The present invention generally relates to lamps and switches therefor, and more particularly relates to a lamp assembly having a proximity switch.
BACKGROUND OF THE INVENTION
Automotive vehicles are typically equipped with various user actuatable switches for operating devices including powered windows, headlights, windshield wipers, moonroofs or sunroofs, interior lighting, radio and infotainment devices, and various other devices. Generally, these types of switches need to be actuated by a user in order to activate or deactivate a device or perform some type of control function. Proximity switches, such as capacitive switches, employ one or more proximity sensors to generate a sense activation field and sense changes to the activation field indicative of user actuation of the switch, typically caused by a user's finger in close proximity or contact with the sensor. Capacitive switches are typically configured to detect user actuation of the switch based on comparison of the sense activation field to a threshold.
Automotive lamp assemblies typically include a separate mechanical switch for activating the lighting device. Some lamp assemblies include a depressible lamp assembly that moves to activate a push switch to turn the light on and off. With the availability of proximity switches, a proximity switch may be employed to control activation of the light device. It would be desirable to provide for a proximity switch which is easy to package and use and does not interfere with the lighting function or other switches.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a proximity switch is provided. The proximity switch includes a sensing pad and a proximity sensor disposed near a perimeter of the sensing pad. The proximity sensor generates an activation field proximate to the sensing pad. The proximity sensor includes a plurality of interdigitated electrode fingers having differing lengths and spacings.
According to another aspect of the present invention, a proximity switch is provided that includes a sensing pad and a proximity sensor disposed near a perimeter of the sensing pad. The proximity sensor includes inner electrode fingers interdigitated and electrically coupled to outer electrode fingers to generate an activation field proximate to the sensing pad. The inner and outer electrode fingers have a different length and spacing on one side of the sensing pad as compared to another side of the sensing pad.
According to a further aspect of the present invention, a lamp and proximity switch assembly is provided. The lamp and proximity switch assembly includes a lens having a transparent window and a light source disposed to illuminate light through the transparent window of the lens. The lamp and proximity switch assembly also includes a proximity sensor disposed near a perimeter of the transparent window and generating an activation field proximate to the transparent window. The proximity sensor includes a plurality of interdigitated electrode fingers having differing lengths and spacings.
These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a perspective view of a passenger compartment of an automotive vehicle having an overhead console employing a pair of lamp and proximity switch assemblies, according to one embodiment;
FIG. 2 is an enlarged view of the overhead console with lamp and proximity switch assemblies shown in FIG. 1;
FIG. 3 is an enlarged view of one lamp and proximity switch assembly having a proximity switch arrangement, according to one embodiment;
FIG. 4 is a cross-sectional view taken through line IV-IV of FIG. 3 illustrating the lamp and switch assembly in relation to a user's finger;
FIG. 5 is a front view of the lamp and proximity switch assembly shown in FIG. 3 with the sensor electrode assembly shown in solid lines;
FIG. 6 is a perspective view of the lamp and proximity switch assembly further illustrating the activation field;
FIG. 7 is a graph illustrating the signal response associated with the proximity switch shown in FIG. 3 as a user's finger moves diagonally across the switch; and
FIG. 8 is a front view of a lamp and switch assembly having an alternative proximity switch arrangement, according to another embodiment.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to a detailed design; some schematics may be exaggerated or minimized to show function overview. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
Referring to FIGS. 1 and 2, the passenger compartment interior of an automotive vehicle 10 is generally illustrated having a pair of lamp and switch assemblies 20 and a plurality of proximity switches 24 assembled in an overhead console 12, according to one embodiment. The vehicle 10 generally includes the overhead console 12 assembled to the headliner on the underside of the roof or ceiling at the top of the vehicle passenger compartment, generally above the front passenger seating area. Each of the pair of lamp and switch assemblies 20 provides an integral assembly of a lamp and a proximity switch 22 for activating a light source to turn the lamp on and off. Each lamp and proximity switch assembly 20 includes a lens 32 having a light transparent window, a light source disposed behind the lens to illuminate light through the transparent window of the lens, and a proximity switch 22 having one or more proximity sensors disposed near a perimeter of the transparent window of the lens and generating an activation field proximate to the transparent field of the lens to sense activation of the proximity switch to control activation of the light source. In the embodiment shown, the proximity switch 22 is integrally assembled as part of the lamp assembly in which the transparent window of the lens serves as a sensing pad. The user may contact the sensing pad or come into close proximity therewith to be detected by the activation field. However, it should be appreciated that the proximity switch 22 may be assembled separate from the lamp assembly and employ its own sensing pad and may control any of a number of devices or functions.
A user may activate the light source by activating the proximity switch integrally provided with the lamp and switch assembly 20. The lamp may serve as an interior map or reading lamp to provide interior lighting to the vehicle 10, according to one embodiment. The lamp and switch assembly 20 may also serve as a dome lamp to provide lighting in the interior of the vehicle 10. It should be appreciated that the lamp may serve to provide lighting to the interior of the vehicle for other uses and the lamp and switch assembly 20 may be located elsewhere on the vehicle 10. For example, the lamp and switch assembly 20 may be located in the headliner, a visor, a grab handle, a center console, or elsewhere on the vehicle 10.
Each proximity switch 22 provided in each lamp and switch assembly 20 is shown and described herein as a capacitive switch, according to one embodiment. Each proximity switch 22 includes a proximity sensor that provides a sense activation field to sense contact or close proximity of an object, such as a user's finger, in close relation to the proximity sensor, such as a tap or swiping motion by a user's finger. Thus, the sense activation field generated by the proximity sensor of each proximity switch is a capacitive field in the exemplary embodiment, and the user's finger has electrical conductivity and dielectric properties that cause a change or disturbance in the sense activation field as should be evident to those skilled in the art. However, it should also be appreciated by those skilled in the art that additional or alternative types of proximity sensors can be used, such as, but not limited to, inductive sensors, optical sensors, temperatures sensors, resistive sensors, the like, or a combination thereof. Exemplary proximity sensors are described in the Apr. 9, 2009, ATMEL® Touch Sensors Design Guide, 10620 D-AT42-04/09, the entire reference hereby being incorporated herein by reference.
A plurality of proximity switches 24 are also shown generally arranged close to one another in the overhead console 12. The various proximity switches 24 may control any of a number of vehicle devices and functions, such as controlling movement of a sunroof or moonroof 16, controlling movement of a moonroof shade 18, controlling activation of one or more lighting devices, and controlling various other devices and functions. While the lamp and switch assembly 20 with proximity switch 22 and proximity switches 24 are shown located in an overhead console 12, it should be appreciated that the assembly 20 and proximity switches 22 and 24 may be located elsewhere on the vehicle 10, such as in the dash panel, on other consoles such as a center console, integrated into a touch screen display for a radio or infotainment system such as a navigation and/or audio display, or located elsewhere onboard the vehicle 10 according to various vehicle applications.
The proximity switches 24 are shown and described herein as capacitive switches, according to one embodiment. Each proximity switch 24 includes one or more proximity sensors that provide a sense activation field to sense contact or close proximity of a user in close relation on to the one or more proximity sensors, such as a tap or swiping motion by a user's finger. Thus, the sense activation field of each proximity switch 24 is a capacitive field in the exemplary embodiment and the user's finger has electrical conductivity and dielectric properties that cause a change or disturbance in the sense activation field as should be evident to those skilled in the art.
Referring to FIGS. 3 and 4, the lamp and switch assembly 20 is generally illustrated having a lens 32 made of a transparent material integrally molded as part of the overhead console 12. The transparent window 32 of the lens is light transmissive to allow visible light waves to pass through the transparent window. A lamp or light source 30 is disposed above the transparent window of the lens 32 to illuminate light through the transparent window of the lens 32. The light source 30 may include a light emitting diode (LED) mounted to a circuit board, according to one embodiment. Other light sources such as an incandescent bulb or combination of one or more light sources may be employed, according to other embodiments. The lens 32 may be integrally formed as part of the overhead console 12 and having the transparent window formed therein, according to one embodiment. In this embodiment, the transparent window may be molded as part of or into a polymeric material forming the overhead console 12. According to other embodiments, the lens 32 may be formed as a separate component and assembled to the overhead console 12. In such embodiments, the lens 32 may be fixedly mounted to the overhead console 12 via fasteners, adhesive or other mounting connection and generally does not move relative to the overhead console 12.
The lamp and proximity switch assembly 20 includes a proximity switch 22 disposed near a perimeter of the transparent window of the lens 32. The proximity switch 22 has a proximity sensor 23 for generating an activation field 26 proximate to the transparent window 32 to sense activation of the proximity switch 22 to control activation of the light source 30, according to one embodiment. In the embodiment shown, the proximity switch 22 has a single proximity sensor 23 configured to extend on all four sides of the lens 32 to substantially surround the transparent window of the lens 32. In this embodiment, the proximity switch 22 substantially surrounds the lens 32 to generate an activation field 26 generally across substantially the entire bottom surface of the lens 32 and below the lens 32 as seen in FIGS. 3 and 4. In other embodiments, the proximity sensor 23 may extend on two or three sides of the sensing pad.
According to one embodiment, the proximity sensor 23 is applied as an electrically conductive ink onto a substrate shown as the upper side of the overhead console 12 about the perimeter of the lens 32. The conductive ink forms electrodes 40 and 50 that serve to provide a capacitance which produces the activation field 26. It should be appreciated that other forms of capacitive sensors may be employed to generate the activation field 26. It should be appreciated that the activation field 26 generated by the proximity switch 22 extends below the transparent window of the lens 32 to enable an object, such as a user's finger 28, hand or other body part to enter the activation field 26 to activate the light source 32 on and off. When an object, such as finger 28 sufficiently engages the activation field 26 below the sensing pad, e.g., lens 32, a disturbance in the activation field 26 is detected such that activation of the proximity switch 22 is initiated so as to either switch the light source 32 on or switch the light source 32 off
Referring to FIGS. 3, 5 and 6, the electrode configuration of the proximity sensor 23 is illustrated, according to one embodiment. Sensor 23 includes an outer electrode 40 having inward extending fingers or plates 42, and an inner electrode 50 having outer extending fingers or plates 52. Electrode fingers 42 are interdigitated with electrode fingers 52 to provide a capacitive coupling between the outer electrode 40 and inner electrode 50. The capacitive coupling produces the activation field 26. The plurality of interdigitated electrode fingers 42 and 52 have different lengths and spacings between interdigitated fingers as described herein so as to configure the activation field 26 to exhibit less interference with the other nearby proximity switches 24.
The outer electrode 40 is shown substantially surrounding the inner electrode 42, and both the inner and outer electrodes 50 and 40 surround the perimeter of the transparent window of lens 52 which serves as a sensing pad. The outer electrode 60 is coupled to a first signal line 60, while the inner electrode 50 is coupled to a second signal line 60. A pulsed drive input signal (e.g., voltage) is applied to one of signal lines 60 and 62, and an output voltage proportional to the capacitance is received on the other of signal line 60 and 62. The input voltage provides a charge coupling on one of the inner and outer electrodes while the other of the inner and outer electrodes provides a signal indicative of the capacitive coupling between the inner and outer electrodes 40 and 50. The output signal and the input signal may be processed by control circuitry, such as a controller, to determine whether an object, such as a user's finger, is sufficiently interacting with the activation field 26 to activate the proximity switch 22.
The proximity switch 22 employs a proximity sensor 23 disposed near a perimeter of the sensing pad, shown as lens 32, and generates an activation field 26 proximate to the sensing pad. The proximity sensor includes a plurality of interdigitated electrode fingers having differing lengths and spacings. As seen in this embodiment, the interdigitated electrode fingers 42 and 52 have a first length and a first spacing therebetween along the portion of the electrodes 40 and 50 on the bottom and left sides of lens 32 which are adjacent to neighboring proximity switches 24. The length and spacing between the interdigitated fingers 42 and 52 is greater on the top and right sides of lens 32 where there are no other nearby proximity switches to interfere with the activation field 26. The second length L of electrode fingers 52 and 42 and the second spacing S between the interdigitated electrode fingers on the top and right sides is substantially greater than the first length L and first spacing S on the bottom and left sides so as to create a variable length and spacing electrode configuration. By varying the length and spacing of the electrode fingers 42 and 52, the activation field 26 may be shaped so it does not extend far enough out from the sensing pad or lens 32 to interfere with the adjacent proximity switches 24 and yet provides a sufficient coverage across the entire sensing pad or lens 32 due to the longer length and spacing of interdigitated fingers on the opposite side.
It should be appreciated that the activation field 26 is generally constrained to the region below the transparent window of the lens 32 such that it does not interfere with nearby proximity switches 24. The nearby proximity switches 24 are shown assembled to the overhead console 12 near the lamp assembly 20. The proximity switches 24 each have a proximity sensor 25 that may be formed as a conductive ink applied onto a substrate such as the upper surface of the polymeric overhead console 12. It should be appreciated that proximity sensor 25 may be otherwise formed as a pre-assembled pad. The proximity switches 24 are disposed at a distance sufficiently away from the lamp and switch assembly 20 and switch 22.
In the embodiment shown, the proximity sensor 23 is disposed near a perimeter of the sensing pad or lens 32 such that the proximity sensor substantially surrounds the sensing pad or lens 32. Thus, the proximity sensor 23 and electrodes 40 and 50 extends around the left, right, top and bottom sides of the sensing pad or lens 32. It should be appreciated that other sensing pad and electrode configurations may be employed having various shapes and extending along two or more sides of the sensing pad. In addition, it should be appreciated that the proximity sensor 23 may be formed on the lens 32, according to another embodiment.
According to one example, the shorter length electrode fingers may have a first length of 1 mm, whereas the longer length electrode fingers may have a second length of 8 mm. The first spacing between the shorter length electrode fingers 1 mm, whereas the second spacing between the longer length electrode fingers of 5 mm. Additionally, the thickness of the electrode fingers or plates may vary, such that the shorter electrode fingers having a closer spacing are thinner than the electrode fingers that have a longer length and longer spacing therebetween. According to one example, the shorter electrode fingers may have a 1 millimeter thickness as compared to a 4 millimeter thickness for the longer length and spaced electrode fingers.
Referring to FIG. 7, a signal response 70 generated by the proximity sensor is shown illustrating the capacitance output as a Δ count value as a function of distance from center of the sensing pad as a user slides a finger diagonally from the bottom left side (corner) of the proximity switch 22 to the upper right side (corner) of the proximity switch 22 as seen in FIG. 5. As the finger approaches the activation field on the bottom left corner, the A count value increases as the finger moves toward the center and reaches a peak near the center of the interdigitated fingers and then ramps down to a lower value as the finger proceeds to move towards the center. At the center, there is sufficient strength in the activation signal to allow a user to activate the switch. As the finger continues to move from the center toward the upper right corner, the signal ramps back up and peaks in the vicinity of the interdigitated fingers and thereafter proceeds to ramp down as the finger reaches the upper right corner and goes beyond. As seen by the example, the shorter length and shorter spacing electrode fingers results in a smaller signal which contains the activation field to a smaller region that does not interfere with nearby switches, whereas the longer length and longer spacing electrode fingers provides a greater signal with a greater area of coverage sufficient to cover the large sensing pad as shown on the upper right side.
Referring to FIG. 8, a lamp and switch assembly 20 is illustrated having the switch 22 and sensor 23 configured in an alternative configuration, according to a second embodiment. In this embodiment, sensor 23 includes the outer electrode 40 and inner electrode 50 configured with interdigitated electrode fingers 42 and 52, respectively having a length and spacing therebetween that varies linearly along each side of the lamp lens 32 or sensing pad. Starting in the bottom left corner of the sensor 22, the electrode fingers 42 and 52 increase in length and in spacing therebetween in the direction toward the right side below lens 32 and from the bottom to the top on the left side of lens 32. The electrode fingers 42 and 52 likewise increase in length from the upper left side to the right side above lens 32 and from the bottom right side to the top right side on the right side of lens 32. The change in length and spacing between the interdigitated electrode fingers 42 and 52 is shown as continuously increasing in size along each side of the lens 32. However, it should be appreciated that the variations in length and spacing between electrode fingers 42 and 52 may otherwise be configured, according to other embodiments.
Accordingly, a proximity switch 22 is provided which has a plurality of interdigitated electrode fingers having different lengths and spacings so as to configure the activation field to prevent interference with nearby switches or sensors. The difference in length and spacing between the interdigitated electrode fingers is particularly useful for a large sensing pad, such as when utilized as a sensor or switch for activating a lamp that is integrally built into the lamp assembly. However, it should be appreciated that the proximity switch 22 may be employed for other switches, particularly for larger switches which have neighboring switches or sensors nearby that could cause potential interference.
It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present invention, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.

## Claims

1. A proximity switch comprising:
a sensing pad; and
a proximity sensor disposed near a perimeter of the sensing pad and generating an activation field proximate to the sensing pad, said proximity sensor comprising first electrode fingers having multiple lengths interdigitated with second electrode fingers having multiple lengths, wherein differing spacings exist between adjacent first and second electrode fingers.

2. The proximity switch of claim 1, wherein the first and second electrode fingers are electrically coupled to generate the activation field.

3. The proximity switch of claim 2, wherein the first and second electrode fingers extends on first and second sides of the sensing pad, wherein the first and second electrode fingers on the first side of the sensing pad have a first length and a first spacing between adjacent electrode fingers and the first and second electrode fingers on the second side of the sensing pad have a second length and a second spacing between adjacent electrode fingers, wherein the second length is greater than the first length and the second spacing is greater than the first spacing.

4. The proximity switch of claim 3, wherein the first side is opposite the second side.

5. The proximity switch of claim 1, wherein the first and second electrode fingers extend from one end of one side to an opposite end, wherein the first and second electrode fingers on said one end have a first length and a first spacing between adjacent electrode fingers and the first and second electrode fingers on the opposite end have a second length and a second spacing between adjacent electrode fingers, wherein the second length is greater than the first length and the second spacing is greater than the first spacing.

6. The proximity switch of claim 1, wherein the proximity sensor substantially surrounds the perimeter of the sensing pad.

7. The proximity switch of claim 1, wherein the proximity switch is employed on a vehicle.

8. The proximity switch of claim 1, wherein the proximity sensor comprises a capacitive sensor.

9. The proximity switch of claim 1, wherein the switch is provided as an assembly comprising a lens having a transparent window and a light source disposed to illuminate light through the transparent window of the lens, wherein the transparent window comprises the sensing pad.

10. A proximity switch comprising:
a sensing pad; and
a proximity sensor disposed substantially around a perimeter of the sensing pad and comprising inner electrode fingers interdigitated and electrically coupled to outer electrode fingers to generate an activation field proximate to the sensing pad, wherein the inner and outer electrode fingers each have different lengths and different spacings exist between adjacent electrode fingers on one side of the sensing pad as compared to another side of the sensing pad.

11. The proximity switch of claim 10, wherein the proximity switch comprises a capacitive sensor and the activation field comprises a capacitive field.

12. The proximity switch of claim 10, wherein the inner and outer electrode fingers on one side of the sensing pad have a first length and a first spacing therebetween and the inner and outer electrode fingers proximate to another side of the sensing pad have a second length and a second spacing therebetween, wherein the second length is greater than the first length and the second spacing is greater than the first spacing.

13. A lamp and proximity switch assembly comprising:
a lens having a transparent window;
a light source disposed to illuminate light through the transparent window of the lens; and
a proximity sensor disposed substantially around a perimeter of the transparent window and generating an activation field proximate to the transparent window, said proximity sensor comprising a plurality of interdigitated electrode fingers having differing lengths and spacings between adjacent electrode fingers.

14. The assembly of claim 13, wherein the plurality of interdigitated electrode fingers comprises first electrode fingers and second electrode fingers, wherein the first and second electrode fingers are interdigitated and electrically coupled to generate the activation field.

15. The assembly of claim 14, wherein the plurality of interdigitated electrode fingers extends on first and second sides of the sensing pad, wherein the first and second electrode fingers on the first side of the sensing pad have a first length and a first spacing and the first and second electrode fingers on the second side of the sensing pad have a second length and a second spacing, wherein the second length is greater than the first length and the second spacing is greater than the first spacing.

16. The assembly of claim 15, wherein the first side is opposite the second side.

17. The assembly of claim 13, wherein the plurality of interdigitated electrode fingers extend from one end of one side to an opposite end, wherein the electrode fingers on said one end have a first length and a first spacing and the electrode fingers on the opposite end have a second length and a second spacing, wherein the second length is greater than the first length and the second spacing is greater than the first spacing.

18. The assembly of claim 13, wherein the proximity sensor substantially surrounds the perimeter of the transparent window.

19. The assembly of claim 13, wherein the assembly is employed on a vehicle.

20. The assembly of claim 13, wherein the proximity sensor comprises a capacitive sensor.