Physical force capacitive touch sensors

• US 9,543,948 B2
• Filed: 01/17/2013
• Issued: 01/10/2017
• Est. Priority Date: 09/01/2009
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Microchip Technology Incorporated
• Inventors: Curtis, Keith, Duvenhage, Fanie
• Primary Examiner(s): MILLER, DANIEL R
• Application Number:
  US13/743,678
• Publication Number:
  US 20130126325A1
• Time in Patent Office: 1,454 Days
• Field of Search: 737/24, 733/04.C
• US Class Current: 1/1
• 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 comprising an array of electrodes;

a cover comprising a first section forming a substantially non-deformable spacer on the substrate that surrounds the capacitive sensor element and a second section forming a flexible cover covering the capacitive sensor element;

an electrically conductive plane coupled with the flexible cover via an array of pedestals and being proximate to the capacitive sensor element and being arranged to at least partially cover each electrode in said array of electrodes;

wherein a density of pedestals in the array of pedestals coupled between the flexible cover and the electrically conductive plane is greater than a density of electrodes in the array of electrodes; and

wherein when a mechanical force is applied to the flexible cover, the flexible cover and electrically conductive plane are 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 cover is a single piece cover and the electrically conductive plane is a part of the single piece cover.

3. The physical force capacitive touch sensor according to claim 1, 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.

4. The physical force capacitive touch sensor according to claim 1, wherein the substantially non-deformable spacer is light inhibitive.

5. The physical force capacitive touch sensor according to claim 1, further comprising an alpha-numeric emblem on the flexible cover to indicate a function of an associated capacitive sensor element.

6. The physical force capacitive touch sensor according to claim 5, 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.

7. The physical force capacitive touch sensor according to claim 1, 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.

8. The physical force capacitive touch sensor according to claim 1, further comprising a light source, 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.

9. The physical force capacitive touch sensor according to claim 1, wherein the other electrode of the capacitive sensor element is coupled to an input of a capacitance value measurement circuit.

10. 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.

11. The physical force capacitive touch sensor according to claim 1, wherein the light transmissive substrate comprises glass or plastic.

12. The physical force capacitive touch sensor according to claim 1, wherein the pedestals are round, square, or rectangular.

13. The physical force capacitive touch sensor according to claim 1, wherein the plurality of capacitive sensor elements are arranged to form a ring and the electrically conductive plane is ring-shaped.

14. The physical force capacitive touch sensor according to claim 1, further comprising a light source for illuminating a face of the flexible cover.

15. The physical force capacitive touch sensor according to claim 14, 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.

16. The physical force capacitive touch sensor according to claim 1, wherein one of the first and second electrodes is coupled with a supply common or ground and the electrically conductive plane is electrically floating.

17. The physical force capacitive touch sensor according to claim 1, wherein the first and second electrodes are configured to be selectively coupled with a capacitance measurement device and the electrically conductive plane is coupled with a supply common or ground.

18. The physical force capacitive touch sensor according to claim 1, further comprising a switch coupled with the electrically conductive plane, wherein in a first operating mode the switch couples the electrically conductive plane and a power supply common or ground, and in a second operating mode, the switch couples the electrically conductive plane with the capacitance value measurement circuit.

19. A capacitive touch sensor arrangement, comprising:

a substrate;

an array of capacitive sensor electrodes linearly or circularly arranged on a face of the substrate or arranged in a matrix on a face of the substrate;

a cover comprising a first section forming a substantially non-deformable spacer on the substrate that surrounds the array of capacitive sensor electrodes and a second section forming a flexible cover covering the array of capacitive sensor elements; and

a continuous electrically conductive deformable plane coupled with the flexible cover and being proximate to the array of capacitive sensor electrodes and being arranged to at least partially cover each capacitive sensor electrode in said array of capacitor sensor electrodes;

an array of mini-pedestals located between the flexible cover and the electrically conductive deformable plane;

wherein a density of mini-pedestals in the array of mini-pedestals between the flexible cover and the electrically conductive deformable plane is greater than a density of capacitive sensor electrodes in the array of capacitive sensor electrodes; and

wherein when a mechanical force is applied to a region of the electrically conductive plane, the electrically conductive plane is biased toward at least one of the capacitive sensor elements physically aligned with the region of the continuous electrically conductive plane, whereby the at least one of the capacitive sensor elements changes capacitance value.

20. The capacitive touch sensor arrangement according to claim 19, further comprising 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.

21. The capacitive touch sensor arrangement according to claim 19, wherein the mini-pedestals are round, square, or rectangular.

22. The capacitive touch sensor arrangement according to claim 19, further comprising a light source for illuminating a face of the electrically conductive deformable plane.

23. The capacitive touch sensor arrangement according to claim 19, further comprising a capacitive measurement circuit having a plurality of inputs coupled to respective ones of the plurality of capacitive sensor electrodes, 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 electrodes, wherein the digital processor and the capacitive measurement circuit are part of a microcontroller.

24. A physical force capacitive touch key, comprising:

a substrate;

an array of capacitive sensor elements including first and second capacitive sensor elements on a face of the substrate such that a gap is formed between the first and second capacitive sensor elements;

a cover comprising a first section forming a substantially non-deformable spacer on the substrate that forms a cavity including at least the first and second capacitive sensor elements and a second section forming a flexible cover covering at least the first and second capacitive sensor elements; and

a continuous flexibly-deformable electrically conductive plane coupled with the flexible cover via an array of pedestals and being arranged to at least partially cover each capacitor sensor element in the array of capacitive sensor elements including the first and second capacitive sensor elements;

wherein a density of pedestals in the array of pedestals coupled between the flexible cover and the electrically conductive plane is greater than a density of capacitive sensor elements in the array of capacitive sensor elements; and

wherein when a mechanical force is applied to a first region of the continuous flexibly-deformable electrically conductive plane, the electrically conductive plane is biased toward the first capacitive sensor element, whereby the first capacitive sensor element changes capacitance value; and

wherein when the mechanical force is applied to a second region of the continuous flexibly-deformable electrically conductive plane, the electrically conductive plane is biased toward the second capacitive sensor element, whereby the second capacitive sensor element changes capacitance value.

25. The physical force capacitive touch key according to claim 24, further comprising a flexible cover over the continuous flexibly-deformable electrically conductive plane, wherein the flexible cover is light transmissive, wherein when the mechanical force is applied to the flexible cover the electrically conductive plane is biased toward at least one of the first or second capacitive sensor elements.

26. 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.

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

28. 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.

29. A physical force capacitive touch joystick, comprising:

a substrate;

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

a cover comprising a first section forming a substantially non-deformable spacer on the substrate that forms a cavity including array of the least three capacitive sensor elements and a second section forming a flexible cover covering the array of at least three capacitive sensor elements;

an array of pedestal structures spaced apart from each other and coupled with the flexible cover; and

a continuous electrically conductive plane attached to the array of spaced-apart pedestal structures and proximate to the array of at least three capacitive sensor elements and being arranged to at least partially cover each capacitive sensor element in said array of at least three capacitor sensor elements;

wherein a density of pedestal structures in the array of pedestal structures between the flexible cover and the continuous electrically conductive plane is greater than a density of capacitive sensor elements in the array of capacitive sensor elements; and

wherein when a mechanical force is applied to the continuous electrically conductive plane, the continuous electrically conductive plane is biased toward a subset of one or more of the array of at least three capacitive sensor elements based on a location of the mechanical force applied to the continuous electrically conductive plane, whereby the subset of the array of at least three capacitive sensor elements changes capacitance value.

30. The physical force capacitive touch joystick according to claim 29, further comprising a joy stick attached to at least one of the pedestal structures, wherein when a mechanical motion is applied to the joy stick the mechanical force is applied to the electrically conductive plane.

31. A capacitive touch cylindrical sensor, comprising:

a substrate formed into a cylinder;

a plurality of capacitive sensor elements arranged in a circular arrangement on a substrate;

a cover comprising a first section forming a substantially non-deformable spacer on the substrate that forms a cavity including the plurality of capacitive sensor elements and a second section forming a flexible cover covering the plurality of capacitive sensor elements; and

a continuous electrically conductive deformable structure coupled with the flexible cover via an array of pedestals and having a circular shape and arranged proximate to the plurality of capacitive sensor elements and being arranged to at least partially cover each capacitive sensor element in said plurality of capacitor sensor elements;

wherein a density of pedestals in the array of pedestals coupled between the flexible cover and the continuous electrically conductive plane is greater than a density of the plurality of capacitive sensor elements; and

wherein when a mechanical force is applied to a portion of the continuous electrically conductive deformable structure having the circular shape, the continuous electrically conductive deformable structure 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.

32. The capacitive touch slider according to claim 31, further comprising a flexible cover over the electrically conductive deformable structure, wherein when the mechanical force is applied to the flexible cover the electrically conductive deformable structure is biased toward the at least one of the plurality of capacitive sensor elements.