Flexible Capacitive Sensor Array

• US 20120098783A1
• Filed: 04/21/2011
• Published: 04/26/2012
• Est. Priority Date: 10/12/2010
• Status: Active Grant

• Current Assignee: Parade Technologies, Ltd.
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Badaye, Massoud, Landry, Greg
• Granted Patent: US 9,459,736 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• 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

A method for detecting force applied to a capacitive sensor array and compensating for coordinate inaccuracy due to force includes receiving a plurality of capacitance measurements from the capacitive sensor array, where the plurality of capacitance measurements includes a first capacitance measurement and a second capacitance measurement, and detecting pressure on the capacitive sensor array based on a comparison between the first capacitance measurement and the second capacitance measurement.

Claims

1. A method, comprising:

receiving a plurality of capacitance measurements from a capacitive sensor array, wherein the plurality of capacitance measurements includes at least a first capacitance measurement and a second capacitance measurement; and

detecting deformation of the capacitive sensor array based on a comparison between the first capacitance measurement and the second capacitance measurement.

2. The method of claim 1, wherein the comparison comprises determining a ratio between the first capacitance measurement and the second capacitance measurement.

3. The method of claim 1, wherein the comparison comprises determining a difference between the first capacitance measurement and the second capacitance measurement.

4. The method of claim 1, wherein the plurality of capacitance measurements indicate a location of a contact at a surface of the capacitive sensor array, and wherein the first capacitance measurement corresponds to a first sensor element closer to the contact than a second sensor element corresponding to the second capacitance measurement.

5. The method of claim 4, wherein at least two sensor elements are situated between a sensor element corresponding to the second capacitance measurement and a sensor element corresponding to the first capacitance measurement.

6. The method of claim 1, wherein a magnitude of the first capacitance measurement is the greatest magnitude of the plurality of capacitance measurements.

7. The method of claim 1, further comprising selecting the second capacitance measurement based on a magnitude of the second capacitance measurement relative to magnitudes of the other capacitance measurements.

8. The method of claim 1, further comprising selecting the second capacitance measurement based on a distance between a first sensor element corresponding to the first capacitance measurement and a second sensor element corresponding to the second capacitance measurement.

9. The method of claim 1, further comprising:

when the deformation is not detected, calculating a touch location based on the plurality of capacitance measurements;

transmitting the touch location; and

in response to detecting the deformation, stopping calculation of the touch location.

10. The method of claim 9, further comprising in response to detecting the deformation, transmitting a last known touch location.

11. The method of claim 9, wherein the plurality of capacitance measurements is acquired during a transient time period following a touch at the touch sensing surface and a stable time period following the transient time period, and wherein the calculation of the touch location is performed based on a subset of the plurality of capacitance measurements acquired during the stable time period.

12. The method of claim 1, further comprising, in response to detecting the deformation, calculating a corrected touch location based on a magnitude of the detected deformation.

13. The method of claim 12, wherein calculating the corrected touch location comprises:

identifying a compensation profile corresponding to the detected deformation based on the compensation profile, calculating a corrected measurement for each of the plurality of capacitance measurements.

14. An apparatus, comprising:

a capacitive sensor input configured to receive a plurality of capacitance measurements from a capacitive sensor array, wherein the plurality of capacitance measurements includes at least a first capacitance measurement and a second capacitance measurement; and

a processing unit coupled with the capacitive sensor input, wherein the processing unit is configured to detect deformation of the capacitive sensor array based on a comparison between the first capacitance measurement and the second capacitance measurement.

15. The apparatus of claim 14, wherein the processing unit performs the comparison by calculating a ratio between the first capacitance measurement and the second capacitance measurement.

16. The apparatus of claim 14, wherein a magnitude of the first capacitance measurement is the greatest magnitude of the plurality of capacitance measurements.

17. The apparatus of claim 14, further comprising a lookup table coupled with the processing unit, wherein the lookup table is configured to store at least one compensation profile, and wherein the processing unit is further configured to, in response to detecting the deformation, calculate a corrected touch location based on the at least one compensation profile.

18. An apparatus, comprising:

an array of sensor elements;

a capacitance sensor coupled with the array of sensor elements, wherein the capacitance sensor is configured to measure a plurality of capacitance measurements from the array of sensor elements;

a processing logic coupled with the capacitance sensor, wherein the processing logic is configured to detect deformation of the array of sensor elements based on the plurality of capacitance measurements.

19. The apparatus of claim 18, wherein the processing logic is further configured to detect the deformation based on comparing a first capacitance measurement of the plurality of capacitance measurements with a second capacitance measurement of the plurality of capacitance measurements.

20. The apparatus of claim 18, wherein the processing logic is further configured to transmit a last known touch location to a host in response to detecting the deformation.