Force Determination Based on Capacitive Sensing

• US 20150370376A1
• Filed: 02/06/2014
• Published: 12/24/2015
• Est. Priority Date: 02/08/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: RICHARDS, Peter W., DINH, Richard Hung Minh, HARLEY, Jonah A., HUPPI, Brian Q., LEUNG, Omar Sze, SHAH, Dhaval N., GRUNTHANER, Martin P., HOTELLING, Steven P., CHRISTOPHY, Miguel C, KATIYAR, Vivek, TAN, Tang Yew, BUTLER, Christopher J., DE JONG, Erik G., SARTEE, Ming, QIAO, Rui, MARTISAUSKAS, Steven J., HOEN, Storrs T., HOOTON, Lee E., SPRAGGS, Ian A., COHEN, Sawyer I., PAKULA, David A.
• Granted Patent: US 10,386,970 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 2203/04105 Pressure sensors for measuring the pressure or force exerted on the touch surface without providing the touch position
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells

Abstract

A device configured to determine the location and magnitude of a touch on a surface of the device. The device includes a transparent touch sensor that is configured to detect a location of a touch on the transparent touch sensor. The device also includes a force-sensing structure disposed at the periphery of the transparent touch sensor. The force sensor includes an upper capacitive plate and a compressible element disposed on one side of the upper capacitive plate. The force sensor also includes a lower capacitive plate disposed on a side of the compressible element that is opposite the upper capacitive plate.

Claims

1. An electronic device comprising:

a transparent touch sensor configured to detect a location of a touch on the transparent touch sensor;

a force-sensing structure disposed at the periphery of the transparent touch sensor, wherein the force-sensing structure comprises;

an upper capacitive plate;

a compressible element disposed on one side of the upper capacitive plate; and

a lower capacitive plate disposed on a side of the compressible element that is opposite the upper capacitive plate.

2. The electronic device of claim 1, wherein compressible element of the force-sensing structure is configured to compress in response to a touch force on the transparent touch sensor.

3. The electronic device of claim 2,

wherein the upper capacitive plate and lower capacitive plate are operatively coupled to force-sensing circuitry configured to detect changes in capacitive coupling between the upper capacitive plate and the lower capacitive plate due to compression of the compressible element, and

wherein the force-sensing circuitry is further configured to produce a signal that corresponds to a magnitude of the touch force on the transparent touch sensor.

4. The electronic device of claim 1, wherein the force-sensing structure is a first force-sensing structure disposed along a first edge of the periphery of the transparent touch sensor, the electronic device further comprising:

a second force-sensing structure disposed along a second edge of the periphery of the transparent touch sensor, the second force-sensing structure comprising an upper capacitive plate, a lower capacitive plate, and a compressible element disposed between the upper and lower capacitive plates; and

force-sensing circuitry operatively coupled to the first and second force-sensing structures and configured to detect changes in capacitive coupling due to deflection of the first and second force-sensing structures, wherein the force-sensing circuitry is further configured to produce a signal that corresponds to a magnitude the touch force on the transparent touch sensor.

5. The electronic device of claim 1,

wherein the force-sensing structure is a first force-sensing structure disposed along a first edge of the periphery of the transparent touch sensor, the electronic device further comprising:

a second force-sensing structure disposed along a second edge of the periphery of the transparent touch sensor;

a third force-sensing structure disposed along a third edge of the periphery of the transparent touch sensor; and

a fourth force-sensing structure disposed along a fourth edge of the periphery of the transparent touch sensor,

wherein the second, third, and fourth force-sensing structures each comprise an upper capacitive plate, a lower capacitive plate, and a compressible element disposed between the upper and lower capacitive plates.

6. The electronic device of claim 1, wherein the transparent touch sensor is a capacitive touch sensor that includes sense circuitry configured to determine the location of the touch on the transparent touch sensor.

7. The electronic device of claim 1, further comprising:

an enclosure having an opening and a bezel surrounding the opening;

a display element disposed within the enclosure and viewable through the opening of the enclosure, wherein;

the transparent touch sensor is disposed at the periphery of the display element.

8. The electronic device of claim 1, further comprising:

an electrical connector tail for electrically connecting the force-sensitive structure to force-sensing circuitry, the electrical connector tail comprising;

a first circuit layer having a first flexible dielectric layer and a first flexible conductive layer electrically connected with the first capacitive plate,

a second circuit layer having a second flexible dielectric layer and a second flexible conductive layer electrically connected with the second capacitive plate, and

an end portion configured to be detachably connected to a circuit component, wherein the end portion includes a void region between the first circuit layer and the second circuit layer,

wherein the void region does not include the compressible element.

9. The electronic device of claim 8, wherein the void region is formed by removing a portion of the compressible element in the end portion of the electrical connector tail.

10. A method of determining the magnitude of force for a touch on a touch device, the method comprising:

transmitting a signal to a force sensor, wherein the force sensor comprises a first and second capacitive plate separated by a compressible member;

measuring a first capacitance between the first and second capacitive plate of the force sensor;

receiving a touch on a surface of the touch device;

measuring a second capacitance between the first and second capacitive plate of the force sensor; and

calculating an estimated force of the received touch based on the first and second measured capacitances.

11. The method of claim 10, wherein transmitting the signal comprises transmitting a series of charge pulses to either the first or second capacitive plate of the force sensor.

12. A method of manufacturing a force sensor, the method comprising;

obtaining a first circuit layer comprising a first flexible conductive layer and a first flexible dielectric layer;

obtaining a second circuit layer comprising a second flexible conductive layer and a second flexible dielectric layer;

forming a laminate structure comprising a compressible layer disposed between the first and second circuit layers;

cutting the laminate structure to form a force sensor having an electrical connector tail; and

removing the compressible layer in an end portion of the electrical connector tail.

13. The method of claim 12, wherein the laminate structure is formed by:

laminating the compressible layer to the first circuit layer using a first bonding adhesive layer;

laminating the compressible layer and the first circuit layer to the second circuit layer using a second bonding adhesive layer, wherein the first and second bonding layer do not extend into the end portion of the connector tail.

14. The method of claim 12,

wherein obtaining the first circuit layer comprises:

forming the first flexible conductive layer on the first flexible dielectric layer,

forming a first capacitive plate that is electrically connected to the first flexible conductive layer, and

wherein obtaining the second circuit layer comprises;

forming the second flexible conductive layer on the second flexible dielectric layer,

forming a second capacitive plate that is electrically connected to the second flexible conductive layer,

wherein the first and second capacitive plates are separated by the compressible layer and form part of a force sensor for determining the magnitude of a touch.

15. The method of claim 12, wherein the first circuit layer includes at least two flexible conductive layers and wherein the second circuit layer includes at least two flexible conductive layers.

16. A touch device, including

a relatively rigid cover element coupled to one or more force sensors;

said force sensors responsive to a displacement of one or more edges of said cover element;

wherein an applied force at a particular location on said cover element provides a force along said one or more edges; and

wherein a sense circuit in said touch device is responsive to said force to determine a location and a magnitude of said applied force.

17. A touch device as in claim 16, wherein

said circuit in said touch device is responsive to said force sensors to determine a centroid of said applied force;

said circuit in said touch device is responsive to said centroid determine one or more locations of applied force; and

said circuit in said touch device is responsive to said centroid of applied force and said one or more locations of applied force to determine one or more measures of applied force.

18. A touch device, including

a relatively deformable cover element coupled to one or more force sensors;

said force sensors responsive to a displacement of one or more locations within a touch area said cover element;

wherein an applied force at a particular location on said cover element provides a force at one or more corresponding locations responsive to said cover element; and

wherein a circuit in said touch device is responsive to said force to determine both said particular location and an amount of said applied force.

19. A method of operating a touch device, the method comprising:

applying a force to a cover element of the device;

measuring, using a sense circuit, a displacement at one or more edges of the cover element; and

computing, using a processor, a location and a magnitude of the applied force based on the measured displacement.

20. A force-sensing structure, comprising:

an upper body;

an upper capacitive plate connected to the upper body;

a lower body;

a lower capacitive plate connected to the lower body; and

a deformable middle body connected to one of the upper body and the upper capacitive plate, the deformable middle body further connected to one of the lower body and the lower capacitive plate.