Resistive force sensor with capacitive discrimination

• US 9,654,104 B2
• Filed: 07/17/2007
• Issued: 05/16/2017
• Est. Priority Date: 07/17/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Rothkopf, Fletcher R., Zadesky, Stephen P.
• Primary Examiner(s): JOSEPH, DENNIS P
• Application Number:
  US11/826,645
• Publication Number:
  US 20090019949A1
• Time in Patent Office: 3,591 Days
• Field of Search: 345173-177
• 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;

using a combination of the first and second outputs and corresponding force and proximity activation thresholds to determine whether the object has pressed an input area of a device; and

using the second output to determine whether to adjust a force baseline in accordance with the first output, wherein the force baseline is different from the activation thresholds and represents the level of force detected in the sensor when no force is being applied to the sensor.

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, further comprising

de-activating the input state based on further changes in the first and second received outputs.

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

6. 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;

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;

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

determining whether to adjust a force baseline in accordance with the detected levels of force based on the detected level of proximity indicated in the one or more signals, wherein the force baseline is different from the threshold amounts of force and proximity and represents the level of force detected in the sensor when no force is being applied to the sensor.

7. The method of claim 6, 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.

8. The method of claim 6, 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.

9. The method of claim 6, 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.

10. The method of claim 6, 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.

11. The method of claim 6, further comprising

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

12. The method of claim 6, further comprising

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

and

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

13. The method of claim 6, 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.

14. 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 an object, the sensor providing in the second mode a second output associated with proximity to the sensor of the object, and

a processor capable of processing the first output and the second output and determining whether the object has pressed an input area of the device based on a combination of the first and second outputs and corresponding force and proximity activation thresholds, the processor further capable of determining whether to adjust a force baseline in accordance with the first output based on the second output, wherein the force baseline is different from the activation thresholds and represents the level of force detected in the sensor when no force is being applied to the sensor.

17. The device of claim 14, wherein the processor is further configured to receive the first and second outputs from the sensor and activate or de-activate an input state based on changes in the first and second outputs.

18. The device of claim 14, wherein the processor is further configured to determine whether the first output exceeds a threshold amount of force and the second output exceeds a threshold amount of proximity.

19. The device of claim 18, wherein the processor is further configured to activate an input state if the threshold amounts of force and proximity are determined to have been exceeded.

15. A method comprising:

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

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

processing the first output and the second output to determine whether the object has pressed an input area of a device based on a combination of the first and second outputs and corresponding force and proximity activation thresholds, and determine whether to adjust a force baseline in accordance with the first output based on the second output, wherein the force baseline is different from the activation thresholds and represents the level of force detected in the sensor when no force is being applied to the sensor.

16. 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 an object, the sensor providing in the second mode a second output associated with proximity to the sensor of the object, and

providing a processor capable of processing the first output and the second output and determining whether the object has pressed an input area of a device based on a combination of the first and second outputs and corresponding force and proximity activation thresholds, the processor further capable of determining whether to adjust a force baseline in accordance with the first output based on the second output, wherein the force baseline is different from the activation thresholds and represents the level of force detected in the sensor when no force is being applied to the sensor.