Managing power consumption of force sensors

• US 9,965,092 B2
• Filed: 05/18/2016
• Issued: 05/08/2018
• Est. Priority Date: 05/18/2016
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Smith, John Stephen
• Primary Examiner(s): Mehmood, Jennifer
• Assistant Examiner(s): Azongha, Sardis F
• Application Number:
  US15/158,548
• Publication Number:
  US 20170336902A1
• Time in Patent Office: 720 Days
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/3262 Power saving in digitizer or tablet
• 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 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

A force-responsive sensor incorporating a force-sensitive element is in communication with a power controller. The power controller changes one or more performance characteristics associated with the force-responsive sensor. A performance characteristic can include a bias voltage or current, a duty cycle, a sampling rate, and so on. The performance characteristic(s) can be changed in response to a touch event or based on an operational setting of the force-responsive sensor (or an electronic device incorporating the force-responsive sensor). Regulation of the performance characteristic(s) reduces power consumption of the force-responsive sensor.

Claims

1. An electronic device comprising:

an input surface;

a force-responsive sensor coupled to the input surface and comprising an array of strain-sensitive elements, each associated with a different portion of the input surface;

a circuit coupled to each of the strain-sensitive elements; and

a power controller coupled to the circuit and configured to selectively enable a subset of the strain-sensitive elements in response to a touch event detected on the input surface, the subset of the strain-sensitive elements selected based on a location of the touch event;

wherein

the power controller is configured to change a duty cycle of the circuit to a first duty cycle if the location is near an edge of the input surface or to a second duty cycle if the location is near a center of the input surface.

2. The electronic device of claim 1, wherein the touch event is detected by a touch sensor positioned below the input surface.

3. The electronic device of claim 1, wherein the circuit is a readout circuit.

4. The electronic device of claim 1, wherein the power controller is further configured to change the duty cycle in response to the detected touch event.

5. The electronic device of claim 4, wherein:

the circuit comprises a drive circuit; and

the duty cycle is associated with an amplifier of the drive circuit.

6. The electronic device of claim 4, wherein the power controller is further configured to change the duty cycle based, at least in part, on the location.

7. The electronic device of claim 1, wherein the first duty cycle is greater than the second duty cycle.

8. A method of operating a force-responsive sensor comprising:

detecting a touch event on an input surface of an electronic device;

determining a subset of force-sensitive elements associated with a force-responsive sensor and proximate to the touch event;

activating each force-sensitive element of the subset of force-sensitive elements;

changing a performance characteristic of a drive circuit configured to apply a drive signal to each force-sensitive element of the subset of force-sensitive elements, the performance characteristic based on the proximity of the touch event to an edge of the input surface.

9. The method of claim 8, wherein the performance characteristic of the drive circuit is a duty cycle associated with an amplifier of the drive circuit.

10. The method of claim 8, wherein the operation of changing the performance characteristic of the drive circuit comprises increasing a duty cycle of the drive circuit.

11. The method of claim 8, wherein at least one force-sensitive element of the subset of force-sensitive elements is a strain-sensitive element.

12. The method of claim 8, wherein the performance characteristic is based, at least in part, on an operational setting of the electronic device.

13. An electronic device comprising:

an input surface;

a touch sensor positioned below the input surface;

a force-responsive sensor positioned below the input surface and comprising an array of strain-sensitive elements arranged in a pattern below the input surface; and

a power controller coupled to the force-responsive sensor and the touch sensor, the power controller configured to;

set a first performance characteristic of the force-responsive sensor in response to a touch detected at an edge of the input surface; and

set a second performance characteristic of the force-responsive sensor in response to a touch detected at a center of the input surface.

14. The electronic device of claim 13, further comprising an amplifier coupled to the force-responsive sensor and configured to amplify a sense signal output by the force-responsive sensor.

15. The electronic device of claim 13, wherein:

the power controller is configured to disable the force-responsive sensor in response to the touch sensor determining that a touch event has ended.

16. The electronic device of claim 13, further comprising:

a drive circuit comprising a signal source coupled to the force-responsive sensor.

17. The electronic device of claim 16, wherein:

the first performance characteristic is an amplifier duty cycle; and

the power controller is configured to change a signal source duty cycle of the signal source in response a touch detected at an edge of the input surface.

18. The electronic device of claim 13, wherein the first performance characteristic is an increased duty cycle.

19. The electronic device of claim 13, wherein at least one strain-sensitive element of the array of strain-sensitive elements is a resistive sensor.