Compliant material for protecting capacitive force sensors and increasing capacitive sensitivity

Patent metadata

Field	Value
Publication number	US-11275475-B2
Application number	US-202117141658-A
Country	US
Kind code	B2
Filing date	Jan 5, 2021
Priority date	Apr 30, 2019
Publication date	Mar 15, 2022
Grant date	Mar 15, 2022

Abstract

A compliant material, such as a conductive foam, is positioned in the dielectric or capacitive gap between drive and sense electrodes and/or other conductive elements of a capacitive and/or other force sensor, such as a TFT or other display element and a sensor assembly. The compliant material prevents damage by preventing and/or cushioning contact. The compliant material may be conductive. By being conductive and being positioned between the electrodes while still being separated from one or more of the electrodes, the compliant material also shortens the effective electrical distance between the electrodes. As a result, the force sensor may be more sensitive than would otherwise be possible while being less vulnerable to damage.

First claim

What is claimed is:

1. An electronic device, comprising:
a housing;
an electronic component coupled to the housing;
an electrode positioned within the housing and capacitively coupled to the electronic component across an air gap defined between the electrode and the electronic component;
a processing unit operative to estimate an amount of a force that deforms the electronic component based, at least in part, on a change in capacitance between the electronic component and the electrode; and
a conductive compliant material positioned in the housing within the air gap between the electronic component and the electrode.

2. The electronic device of claim 1 , wherein the electronic component is operable to contact the conductive compliant material during deformation.

3. The electronic device of claim 1 , wherein the electronic component remains separate from the conductive compliant material during deformation.

4. The electronic device of claim 1 , wherein the conductive compliant material is coupled to at least one of:
the electronic component; or
the electrode.

5. The electronic device of claim 1 , further comprising a midplate coupled to the housing between the electrode and the electronic component wherein the conductive compliant material is coupled to the midplate.

6. The electronic device of claim 1 , wherein the conductive compliant material is coupled to the electrode by a conductive adhesive.

7. The electronic device of claim 1 , further comprising an insulating material coating the conductive compliant material.

8. An electronic device, comprising:
a component that defines an external surface of the electronic device;
a force sensor that is operable to measure a force exerted on the component that changes a capacitive gap of the force sensor, the force sensor including a first electrode coupled to the component and a second electrode coupled to a substrate across an air gap; and
a compliant material positioned in the air gap that:
includes a conductive portion; and
absorbs at least a portion of the force.

9. The electronic device of claim 8 , wherein the compliant material comprises the conductive portion and a nonconductive portion.

10. The electronic device of claim 8 , wherein the compliant material includes:
a first conductive material connected to the second electrode of the force sensor; and
a second conductive material that functions as a shield electrode.

11. The electronic device of claim 10 , wherein the compliant material further includes insulating material separating the first conductive material and the second conductive material.

12. The electronic device of claim 8 , wherein the compliant material comprises at least one of:
a conductive foam;
a silicone gasket;
an air loop gasket;
a fabric; or
a conductive adhesive.

13. The electronic device of claim 8 , wherein the compliant material is compressible.

14. The electronic device of claim 8 , wherein the compliant material has a thickness of 250-950 microns.

15. An electronic device, comprising:
a housing;
a first electrode that is operable to deform when a force is exerted;
a second electrode that is separated from the first electrode by a gap;
a processing unit that is operable to detect a change in capacitance between the first electrode and the second electrode when the first electrode deforms; and
a conductive compliant material positioned in the gap and electrically connected to a first of the first electrode and the second electrode, the conductive compliant material separated from a second of the first electrode and the second electrode in an absence of the force and contacted by the second of the first electrode and the second electrode when the force is exerted.

16. The electronic device of claim 15 , wherein the first of the first electrode and the second electrode is resistively coupled to the conductive compliant material.

17. The electronic device of claim 15 , wherein the first of the first electrode and the second electrode is capacitively coupled to the conductive compliant material.

18. The electronic device of claim 15 , further comprising a shield electrode capacitively coupled to the conductive compliant material.

19. The electronic device of claim 18 , further comprising a nonconductive material separating the shield electrode and the conductive compliant material.

20. The electronic device of claim 19 , wherein the nonconductive material separates the first of the first electrode and the second electrode and the conductive compliant material.

Assignees

• Apple Inc

Inventors

• Bechstein Daniel J
• Petty Collin R
• Grunthaner Martin P
• Joyce Andrew W
• Matthews John R
• Gupta Pavan O
• Lin Albert

Classifications

• G06F3/0445 Primary

  using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer · CPC title