Deformation Compensating Compliant Material

• US 20160195441A1
• Filed: 05/26/2015
• Published: 07/07/2016
• Est. Priority Date: 01/07/2015
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Sauers, Jason C., Chen, Po-Jui, Bushnell, Tyler S.
• Granted Patent: US 9,863,822 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01L 1/142 using capacitors
• CPC Class Codes: G01L 1/26 Auxiliary measures taken, or devices used, in connection with the measurement of force, e.g. for preventing influence of transverse components of force, for preventing overload

Abstract

A force sensor includes compliant material that is configured to stay within a maximum uncompressed dimension in a first direction when compressed in a second direction. The first direction may be perpendicular to the second direction. The compliant material may stay within the maximum uncompressed dimension when compressed by expanding into one or more gaps defined in the compliant material. Such gaps may be defined on an external surface of the compliant material and/or internal to the compliant material. The gaps may be formed using a variety of different processes during or after formation of the compliant material.

Claims

1. A force sensor, comprising:

sensor plates;

compliant material positioned between the sensor plates that;

has a maximum dimension in a first direction when uncompressed;

varies in shape between an uncompressed state and a compressed state; and

is configured to stay within the maximum dimension when compressed in a second direction;

wherein the first direction is perpendicular to the second direction.

2. The force sensor of claim 1, wherein the compliant material defines a gap.

3. The force sensor of claim 2, wherein the compliant material has a dimension in the first direction less than the maximum dimension when uncompressed corresponding to a location of the gap.

4. The force sensor of claim 2, wherein the compliant material:

expands into the gap when compressed;

or

eliminates the gap.

5. The force sensor of claim 2, wherein the gap is defined:

on an external surface of the compliant material;

or

internal to the compliant material.

6. The force sensor of claim 2, wherein a portion of the compliant material defining the gap has a curved surface when the compliant material is uncompressed.

7. The force sensor of claim 1, wherein the compliant material comprises multiple layers arranged in a stepped configuration.

8. The force sensor of claim 7, wherein the multiple layers have different dimensions.

9. A compressible assembly, comprising:

a force sensor comprising first and second conductive plates;

a compressible material positioned between the conductive plates that;

has a maximum dimension when uncompressed;

varies in shape between an uncompressed state and a compressed state;

defines at least one internal void space within the compressible material;

defines at least an edge of an internal void space into which the compressible material enters upon compression; and

expands to no greater than the maximum dimension and into the internal void space when force is applied to a surface of the compressible material;

wherein a direction of expansion of the compressible material is perpendicular to a plane defined by at least one of the first and second conductive plates.

10. The compressible assembly of claim 9, wherein the force sensor comprises a capacitive force sensor.

11. The compressible assembly of claim 9, wherein the force sensor comprises a resistive force sensor.

12. The compressible assembly of claim 9, wherein the compressible material comprises silicone.

13. The compressible assembly of claim 9, wherein the compressible material comprises foam.

14. The compressible assembly of claim 9, wherein sides of the compressible material perpendicular to the plane are flat.

15. A method for compensating for deformation in a force sensor, comprising:

assembling the force sensor including sensor plates;

including compliant material in the force sensor between the sensor plates, the compliant material varying in shape between a compressed state and an uncompressed state and having a maximum dimension in a direction when uncompressed; and

configuring the compliant material to stay within the maximum dimension when compressed perpendicular to the direction.

16. The method of claim 15, wherein said configuring the compliant material comprises defining a gap in the compliant material.

17. The method of claim 16, wherein said defining the gap comprises:

compressing the compliant material such that a portion of the compliant material expands beyond the maximum dimension; and

removing the portion of the compliant material such that the gap is defined when the compliant material is uncompressed.

18. The method of claim 16, wherein said defining the gap comprises forming the compliant material to include the gap.

19. The method of claim 16, wherein said defining the gap comprises:

forming the compliant material; and

removing a portion of the compliant material to define the gap.

20. The method of claim 16, further comprising incorporating the force sensor into an electronic device wherein the sensor plates contact a housing of the electronic device in the direction perpendicular to compression of the compliant material.