Resistive force sensor with capacitive discrimination

• US 20090019949A1
• Filed: 07/17/2007
• Published: 01/22/2009
• Est. Priority Date: 07/17/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Zadesky, Stephen, Rothkopf, Fletcher R.
• Granted Patent: US 9,654,104 B2
• Time in Patent Office: Days
• US Class Current: 73/862.530
• CPC Class Codes: G06F 2203/0382 Plural input, i.e. interface arrangements in which a plurality of input device of the same type are in communication with a PC
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 17/9625 using a force resistance transducer
• CPC Class Codes: H03K 2217/94026 Automatic threshold calibration; e.g. threshold automatically adapts to ambient conditions or follows variation of input
• CPC Class Codes: H03K 2217/96031 Combination of touch switch and LC display
• CPC Class Codes: H03K 2217/96054 Double function: touch detection combined with detection of a movable element

Abstract

A resistive force sensor with capacitive discrimination is disclosed. According to an example of the disclosure, a sensor is directed to detect resistance and capacitance in an alternating fashion, the resistance indicating a force being applied to an input area of a device, and the capacitance indicating a proximity of a body part to the input area of the device, and the detected resistance and capacitance are utilized to determine whether the body part has pressed the input area of the device.

Claims

1. A method, comprising:

switching operation of a sensor between a first operation mode and a second operation mode, wherein

when operating in the first operation mode, the sensor provides a first output responsive to a force applied by an object, and

when operating in the second operation mode, the sensor provides a second output responsive to a proximity of the object.

2. The method of claim 1, further comprising

receiving the first output when the sensor is operating in the first operation mode, and

receiving the second output when the sensor is operating in the second operation mode.

3. The method of claim 2, further comprising

activating an input state based on changes in the first and second received outputs.

4. The method of claim 3, wherein the activation of the input state indicates that a user has pressed an input area of a device.

5. The method of claim 1, wherein the object is a finger.

6. A method, comprising:

directing a sensor to detect resistance and capacitance in an alternating fashion,

the resistance indicating a force being applied to an input area of a device, and

the capacitance indicating a proximity of a body part to the input area of the device; and

utilizing the detected resistance and capacitance to determine whether the body part has pressed the input area of the device.

7. The method of claim 6, wherein the sensor alternates between resistance detection and capacitance detection every 25 milliseconds or less.

8. The method of claim 6, wherein the utilizing of the detected resistance and capacitance comprises

determining whether the detected resistance exceeds a threshold amount of resistance, and

determining whether the detected capacitance exceeds a threshold amount of capacitance.

9. The method of claim 8, further comprising

if the threshold amounts of resistance and capacitance are determined to have been exceeded, activating a state indicating the body part has pressed the input area of the device.

10. The method of claim 9, further comprising

deactivating the state if the state is activated and a subsequently detected capacitance falls below the threshold amount of capacitance.

11. The method of claim 9, further comprising

deactivating the state if the state is activated and a subsequently detected resistance falls below the threshold amount of resistance.

12. The method of claim 8, further comprising

receiving a request to resize the input area of the device;

and

adjusting the threshold amount of capacitance in response to the resize request.

13. The method of claim 8, further comprising

receiving a request to resize the input area of the device;

and

adjusting the threshold amount of resistance in response to the resize request.

14. A method for sensing force with capacitive discrimination, comprising:

receiving from one or more sensors one or more signals indicating levels of force and proximity detected at an input area of a housing;

determining whether the detected level of force exceeds a threshold amount of force;

determining whether the detected level of proximity exceeds a threshold amount of proximity; and

if the threshold amounts of force and proximity are determined to have been exceeded, activating a state indicating user input at the input area of the housing.

15. The method of claim 14, wherein the one or more signals indicating the detected levels of force are received from the same one or more sensors from which the one or more signals indicating the detected levels of proximity are received.

16. The method of claim 14, wherein the one or more signals indicating the detected levels of force are received from different sensors from which the one or more signals indicating the detected levels of proximity are received.

17. The method of claim 14, further comprising

receiving from any of the one or more sensors a subsequent level of proximity detected at the input area of the housing;

and

deactivating the state if the subsequently detected level of proximity falls below the threshold amount of proximity.

18. The method of claim 14, further comprising

receiving from any one of the one or more sensors a subsequent level of force detected at the input area of the housing;

and

deactivating the state if the subsequently detected level of force falls below the threshold amount of force.

19. The method of claim 14, further comprising

if the threshold amount of proximity is determined to have been exceeded, disabling functionality that adjusts a force baseline to match levels of force indicated in signals received from the one or more sensors.

20. The method of claim 14, further comprising

receiving from any of the one or more sensors a subsequent level of proximity detected at the input area of the housing;

and

if the subsequently detected level of proximity falls below the threshold amount of proximity, enabling functionality that adjusts a force baseline to match levels of force indicated in signals received from the one or more sensors.

21. The method of claim 14, wherein the activating of the state comprises

sending a signal indicating that a virtual button displayed on the input area of the housing has been pressed.

22. An apparatus, comprising:

a housing;

a sensor configured to detect both resistance and capacitance; and

a processor configured to determine whether a surface of the housing has been pressed based on changes in both resistance and capacitive detected by the sensor.

23. The apparatus of claim 22, wherein the processors is positioned on a circuit board to which the sensor is attached.

24. The apparatus of claim 22, wherein the processor is not positioned on a circuit board to which the sensor is attached.

25. The apparatus of claim 24, wherein the processor is a central processor responsible for running the apparatus.

26. The apparatus of claim 22, wherein the processor

controls the sensor, and

is configured to interface between the sensor and a central processor responsible for running the apparatus.

27. The method of claim 22, wherein the surface of the housing comprises a rigid material.

28. The method of claim 22, wherein the surface of the housing is fabricated from glass.

29. A device comprising:

a sensor having at least a first mode and a second mode, the sensor providing in the first mode a first output associated with force applied to the sensor by a digit, the sensor providing in the second mode a second output associated with proximity to the sensor of a digit, and

a processor configured to process the first output and the second output and detect application of a force on the sensor by a digit located near the sensor.

30. A method comprising:

operating a sensor in a first mode providing a first output associated with force applied to the sensor by a digit,

operating the sensor in a second mode providing a second output associated with proximity to the sensor of a digit, and

processing the first output and the second output and detecting application of a force on the sensor by a digit located near the sensor.

31. A method comprising:

providing a sensor having at least a first mode and a second mode, the sensor providing in the first mode a first output associated with force applied to the sensor by a digit, the sensor providing in the second mode a second output associated with proximity to the sensor of a digit, and

providing a processor configured to process the first output and the second output and detect application of a force on the sensor by a digit located near the sensor.