PHYSICAL FORCE CAPACITIVE TOUCH SENSORS

• US 20130126325A1
• Filed: 01/17/2013
• Published: 05/23/2013
• Est. Priority Date: 09/01/2009
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Microchip Technology Incorporated
• Inventors: Curtis, Keith, Duvenhage, Fanie
• Granted Patent: US 9,543,948 B2
• Time in Patent Office: Days
• US Class Current: 200/5.A
• CPC Class Codes: H01H 25/04 Operating part movable angularly in more than one plane, e.g. joystick
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 17/975 using a capacitive movable element
• CPC Class Codes: H03K 2217/96066 Thumbwheel, potentiometer, scrollbar or slider simulation by touch switch
• CPC Class Codes: H03K 2217/960755 Constructional details of capacitive touch and proximity switches
• CPC Class Codes: H03K 2217/960785 with illumination

Abstract

A physical force capacitive touch sensor comprises a capacitive sensor element on a substrate, a physically deformable electrically insulating spacer over the capacitive sensor element and a conductive deformable plane over the physically deformable electrically insulating spacer. A protective deformable fascia may be placed over the conductive deformable plane to provide an environmental seal for physical and weather protection, but is not essential to operation of the capacitive touch sensor. Back lighting is accomplished through a light transmissive layer(s) in the capacitive touch sensor. When the conductive deformable plane is displaced toward the capacitive touch sensor element, the capacitance value of the capacitive touch sensor element changes and that change may be detected and used as an actuation signal.

Claims

1. A physical force capacitive touch sensor, comprising:

a substrate;

a capacitive sensor element on a face of the substrate;

a substantially non-deformable spacer on the substrate that surrounds the capacitive sensor element; and

an electrically conductive plane proximate to the capacitive sensor element;

wherein when a mechanical force is applied to the electrically conductive plane it is biased toward the capacitive sensor element, whereby the capacitive sensor element changes capacitance value.

2. The physical force capacitive touch sensor according to claim 1, wherein the electrically conductive plane is flexibly deformable.

3. The physical force capacitive touch sensor according to claim 1, further comprising a flexible cover over the electrically conductive plane, wherein when the mechanical force is applied to the flexible cover the electrically conductive plane is biased toward the capacitive sensor element.

4. The physical force capacitive touch sensor according to claim 3, further comprising a pedestal between the flexible cover and the electrically conductive plane.

5. The physical force capacitive touch sensor according to claim 3, wherein a deformable space around the capacitive sensor element is created by the flexible cover and the substantially non-deformable spacer, wherein the flexible cover is light transmissive and the deformable space comprises a light source, wherein the light source is preferably at least one light emitting diode (LED).

6. The physical force capacitive touch sensor according to claim 1, wherein at least one of the electrically conductive plane, the capacitive sensor element, the substrate is light transmissive and the substantially non-deformable spacer is light inhibitive.

7. The physical force capacitive touch sensor according to claim 3, further comprising a light source for illuminating a face of the flexible cover.

8. The physical force capacitive touch sensor according to claim 7, wherein the light source is located between the electrically conductive plane and the flexible cover or between the electrically conductive plane and the capacitive sensor element or between the capacitive sensor element and the substrate or on an opposite face of the substrate from which the capacitive sensor element is located, whereby light shines through the substrate to illuminate the flexible cover.

9. The physical force capacitive touch sensor according to claim 3, further comprising an alpha-numeric emblem on the flexible cover to indicate a function of an associated capacitive sensor element.

11. The physical force capacitive touch sensor according to claim 3, wherein the electrically conductive plane is a layer of Indium Tin Oxide (ITO) disposed on a face of the flexible cover or a layer of Antimony Tin Oxide (ATO) disposed on a face of the flexible cover or a layer of Graphene disposed on a face of the flexible cover.

12. The physical force capacitive touch sensor according to claim 7, wherein the light source is an electroluminescent (EL) layer or an organic light emitting diode (OLED) layer or an electrophoretic coating of light emitting material.

13. The physical force capacitive touch sensor according to claim 1, wherein the capacitive sensor element is coupled to an input of a capacitance value measurement circuit and the electrically conductive plane is coupled to a power supply common or ground, or

wherein the capacitive sensor element is coupled to a first input of a capacitance value measurement circuit, the electrically conductive plane is coupled to a second input of the capacitance value measurement circuit, and a switch is coupled to the electrically conductive plane and a power supply common or ground, wherein when the switch is closed the electrically conductive plane is coupled to the power supply common or ground and when open the electrically conductive plane is operational with the second input of the capacitance value measurement circuit.

14. The physical force capacitive touch sensor according to claim 1, wherein the substrate and the capacitive sensor element are fabricated from a printed circuit board.

15. The physical force capacitive touch sensor according to claim 1, wherein the substrate is glass, plastic, metallic, or nonmetallic.

16. A user interface having a plurality of physical force capacitive touch sensors, said user interface comprising:

a substrate;

a plurality of capacitive sensor elements on a face of the substrate;

a substantially non-deformable spacer surrounding each one of the plurality of capacitive sensor elements; and

an electrically conductive plane having portions thereof proximate to respective ones of the plurality of capacitive sensor elements;

wherein when a mechanical force is applied to at least one portion of the electrically conductive plane it is biased toward the respective at least one of the plurality of capacitive sensor elements, whereby the at least one of the plurality of capacitive sensor elements changes capacitance value.

17. The user interface according to claim 16, wherein the plurality of capacitive sensor elements are arranged in a matrix.

18. A capacitive touch sensor arrangement, comprising:

a substrate;

a plurality of capacitive sensor elements linearly or circularly arranged on a face of the substrate or arranged in a matrix on a face of the substrate;

a substantially non-deformable spacer on the substrate that surrounds the plurality of capacitive sensor elements; and

an electrically conductive deformable plane proximate to the plurality of capacitive sensor elements;

wherein when a mechanical force is applied to a portion of the electrically conductive plane it is biased toward at least one of the plurality of capacitive sensor elements, whereby the at least one of the plurality of capacitive sensor elements changes capacitance value.

10. The physical force capacitive touch sensor according to claim 19, wherein the alpha-numeric emblem is silk screened onto the flexible cover or the alpha-numeric emblem is embossed into the flexible cover or the alpha-numeric emblem is stamped onto the flexible cover.

19. The capacitive touch sensor arrangement according to claim 18, further comprising a flexible cover over the electrically conductive deformable plane, and a light source for illuminating a face of the flexible cover, wherein the flexible cover and the electrically conductive deformable plane are light transmissive, wherein when the mechanical force is applied to the flexible cover the electrically conductive deformable plane is biased toward at least one of the plurality of capacitive sensor elements.

20. The capacitive touch sensor arrangement according to claim 19, further comprising a plurality of mini-pedestals located between the flexible cover and the electrically conductive deformable plane.

21. The capacitive touch sensor arrangement according to claim 20, wherein the plurality of mini-pedestals are round, square, or rectangular.

22. The capacitive touch sensor arrangement according to claim 18, further comprising a light source for illuminating a face of the electrically conductive deformable plane.

23. The capacitive touch sensor arrangement according to claim 18, further comprising a capacitive measurement circuit having a plurality of inputs coupled to respective ones of the plurality of capacitive sensor elements, and a digital processor coupled to the capacitive measurement circuit and providing force positional information based upon determination of capacitance values of certain ones of the plurality of capacitive sensor elements, wherein the digital processor and the capacitive measurement circuit are part of a microcontroller.

24. A physical force capacitive touch key, comprising:

a substrate;

first and second capacitive sensor elements on a face of the substrate;

a substantially non-deformable spacer on the substrate that surrounds the first and second capacitive sensor elements; and

an electrically conductive plane proximate to the first and second capacitive sensor elements, wherein the electrically conductive plane may be flexibly deformable, wherein the electrically conductive plane may be light transmissive;

wherein when a mechanical force is applied to the electrically conductive plane it is biased toward the first and/or the second capacitive sensor elements, whereby at least one of the first and second capacitive sensor elements changes capacitance value.

25. The physical force capacitive touch key according to claim 24, further comprising a flexible cover over the electrically conductive plane, wherein the flexible cover may be light transmissive, wherein when the mechanical force is applied to the flexible cover the electrically conductive plane is biased toward the first and/or the second capacitive sensor elements.

26. The physical force capacitive touch key according to claim 25, further comprising a pedestal between the flexible cover and the electrically conductive plane.

27. The physical force capacitive touch key according to claim 25, wherein a deformable space around the first and second capacitive sensor elements is created by the flexible cover and the substantially non-deformable spacer.

28. The physical force capacitive touch key according to claim 25, further comprising a light source for illuminating a face of the flexible cover.

29. The physical force capacitive touch key according to claim 24, further comprising:

a capacitive measurement circuit having a plurality of inputs coupled to the first and the second capacitive sensor elements; and

a digital processor coupled to the capacitive measurement circuit and providing force positional information based upon determination of capacitance values of the first and second capacitive sensor elements, wherein the digital processor and the capacitive measurement circuit are part of a microcontroller.

30. A physical force capacitive touch joystick, comprising:

a substrate;

at least three capacitive sensor elements on a face of the substrate;

a substantially non-deformable spacer on the substrate that surrounds the least three capacitive sensor elements;

a pedestal; and

an electrically conductive plane attached to the pedestal and proximate to the at least three capacitive sensor elements;

wherein when a mechanical force is applied to the electrically conductive plane it is biased toward at least one of the at least three capacitive sensor elements, whereby at least one of the at least three capacitive sensor elements changes capacitance value.

31. The physical force capacitive touch joystick according to claim 30, further comprising a joy stick attached to the pedestal, wherein when a mechanical motion is applied to the joy stick the mechanical force is applied to the electrically conductive plane.

32. A capacitive touch cylindrical sensor, comprising:

a substrate formed into a cylinder;

a plurality of capacitive sensor elements arranged on an face of the cylindrical substrate;

a substantially non-deformable spacer on the substrate that surrounds the plurality of capacitive sensor elements; and

an electrically conductive deformable cylindrical sleeve proximate to the plurality of capacitive sensor elements;

wherein when a mechanical force is applied to a portion of the electrically conductive deformable cylindrical sleeve it is biased toward at least one of the plurality of capacitive sensor elements, whereby the at least one of the plurality of capacitive sensor elements changes capacitance value.

33. The capacitive touch slider according to claim 32, further comprising a flexible cover over the electrically conductive deformable cylindrical sleeve, wherein when the mechanical force is applied to the flexible cover the electrically conductive deformable cylindrical sleeve is biased toward at least one of the plurality of capacitive sensor elements.