FORCE SENSING WITHIN DISPLAY STACK

• US 20170277296A1
• Filed: 06/30/2016
• Published: 09/28/2017
• Est. Priority Date: 03/24/2016
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: REYNOLDS, Joseph Kurth, VANDERMEIJDEN, Tom, TANEMURA, Tetsuo
• Granted Patent: US 10,795,509 B2
• Time in Patent Office: Days
• 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 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0414 using force sensing means to determine a position
• CPC Class Codes: G06F 3/04142 the force sensing means being located peripherally, e.g. disposed at the corners or at the side of a touch sensing plate
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

Embodiments described herein include an input device and associated processing system for sensing force applied by input objects. The input device comprises a display device comprising a plurality of layers formed as a display stack, the display stack including a top surface. The input device further comprises one or more strain gauges disposed within the display stack and configured to detect force applied to the top surface, and a processing system configured to perform display updating using the display device and to perform force sensing using the one or more strain gauges.

Claims

1. An input device for sensing force applied by input objects, the input device comprising:

a display device comprising a plurality of layers formed as a display stack, the display stack including a top surface;

one or more strain gauges disposed within the display stack and configured to detect force applied to the top surface; and

a processing system configured to perform display updating using the display device and to perform force sensing using the one or more strain gauges.

2. The input device of claim 1, wherein the one or more strain gauges are arranged to form at least one strain gauge bridge disposed within the display stack.

3. The input device of claim 2, wherein the at least one strain gauge bridge comprises two strain gauge bridges, the input device further comprising a plurality of routing electrodes coupling the processing system with the two strain gauge bridges, wherein at least one of the plurality of routing electrodes is shared by the two strain gauge bridges.

4. The input device of claim 1, further comprising:

a plurality of sensor electrodes arranged to at least partly overlap a display region of the display device, wherein the processing system is further configured to perform capacitive sensing of input objects using the plurality of sensor electrodes.

5. The input device of claim 4, wherein each of the one or more strain gauges comprises one or more sensor electrodes selected from the plurality of sensor electrodes, and wherein the selected one or more sensor electrodes are configured to perform force sensing and capacitive sensing.

6. The input device of claim 5, wherein the plurality of sensor electrodes comprises a plurality of transmitter electrodes and a plurality of receiver electrodes configured to perform capacitive sensing, wherein each of the one or more strain gauges comprises one or more transmitter electrodes selected from the plurality of transmitter electrodes.

7. The input device of claim 4, wherein at least one of the one or more strain gauges are disposed outside of the display region.

8. The input device of claim 4, wherein at least one of the one or more strain gauges and at least one of the plurality of sensor electrodes are disposed on a same layer of the display stack.

9. The input device of claim 4, wherein each of the plurality of sensor electrodes comprises at least one common electrode of a plurality of common electrodes of the display device, the plurality of common electrodes configured to perform capacitive sensing and display updating.

10. The input device of claim 1, wherein the one or more strain gauges are disposed at an interface between adjacent first and second layers of the display stack, wherein the first layer overlaps the second layer to form a staggered interface, wherein the one or more strain gauges are disposed at the staggered interface.

11. The input device of claim 10, further comprising:

a supporting member interfaced with one of the first and second layers at the staggered interface.

12. The input device of claim 1, wherein a first layer of the display stack comprises:

a feature configured to concentrate strain at the interface of the feature and an adjacent member of the display device, wherein at least one of the one or more strain gauges is disposed proximate to the interface.

13. The input device of claim 1, wherein the processing system is further configured to transition the input device out of a predefined low power mode upon sensing force applied by an input object.

14. The input device of claim 1, wherein the one or more strain gauges are formed from an optically transmissive conductive material.

15. A processing system for an input device with a display device, the input device comprising one or more strain gauges configured to sense force applied by input objects, the processing system comprising:

display driver circuitry configured to update the display device;

capacitive sensing circuitry configured to operate a plurality of sensor electrodes of the input device to acquire capacitive sensing data; and

force sensing circuitry configured to acquire force sensing data using the one or more strain gauges,

wherein the one or more strain gauges are formed using one or more sensor electrodes selected from the plurality of sensor electrodes, and wherein the selected one or more sensor electrodes are configured to perform force sensing and capacitive sensing.

16. The processing system of claim 15, wherein the plurality of sensor electrodes includes a plurality of transmitter electrodes and a plurality or receiver electrodes configured to perform capacitive sensing, wherein each of the one or more strain gauges comprises one or more transmitter electrodes selected from the plurality of transmitter electrodes.

17. The processing system of claim 15, wherein the force sensing circuitry and the capacitive sensing circuitry include shared circuitry.

18. The processing system of claim 15, wherein the force sensing circuitry is further configured to refine the acquired force sensing data based on the acquired capacitive sensing data.

19. The processing system of claim 15, wherein the processing system is configured to transition the input device out of a predefined low power mode upon sensing force applied by an input object.

20. The processing system of claim 15, wherein each of the plurality of sensor electrodes comprises at least one common electrode of a plurality of common electrodes of the display device, wherein the plurality of common electrodes are configured to perform capacitive sensing and display updating.

21. A display device comprising:

a plurality of layers formed as a display stack, the display stack including a top surface;

a plurality of display electrodes disposed within the display stack and configured to be driven by a processing system to perform display updating; and

one or more strain gauges disposed within the display stack and configured to detect force applied to the top surface based on signals driven by the processing system.