Flexible capacitive sensor array

• US 9,459,736 B2
• Filed: 04/21/2011
• Issued: 10/04/2016
• Est. Priority Date: 10/12/2010
• Status: Active Grant

• Current Assignee: Parade Technologies, Ltd.
• Original Assignee: Parade Technologies, Ltd.
• Inventors: Badaye, Massoud, Landry, Greg
• Primary Examiner(s): Ghebretinsae, Temesgh
• Assistant Examiner(s): Jansen, II, Michael J
• Application Number:
  US13/091,132
• Publication Number:
  US 20120098783A1
• Time in Patent Office: 1,993 Days
• Field of Search: 345/174
• US Class Current: 1/1
• 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 plurality of sensor elements of a capacitive sensor array, wherein the plurality of capacitance measurements includes a first capacitance measurement measured by a first sensor element of the capacitive sensor array and

a second capacitance measurement measured by a second sensor element of the capacitive sensor array, wherein the second sensor element is within a same set of rows or columns separated by a predetermined distance from the first sensor element;

wherein a flexible touch-sensing surface includes a flexible overlay, a flexible substrate, and the plurality of sensor elements of the capacitive sensor array, the plurality of sensor elements being positioned between the flexible substrate and the flexible overlay;

wherein the flexible touch-sensing surface overlays a display panel without a shield layer being provided against capacitive coupling between the plurality of sensor elements and the display panel;

determining whether deformation of the flexible touch-sensing surface is detected based on a comparison between the first capacitance measurement being a highest magnitude value of the plurality of capacitance measurements and the second capacitance measurement being a second magnitude value;

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

when the deformation is detected, compensating for touch coordinate inaccuracies caused by the deformation.

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 the touch location of a contact at the touch-sensing surface, 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, further comprising selecting the second capacitance measurement based on a magnitude of the second capacitance measurement relative to magnitudes of the other capacitance measurements.

7. 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.

8. The method of claim 1, further comprising:

transmitting the touch location; and

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

9. The method of claim 8, wherein compensating for the touch coordinate inaccuracies comprises, in response to detecting the deformation, transmitting a last known touch location.

10. The method of claim 8, 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.

11. The method of claim 1, wherein compensating for the touch coordinate inaccuracies comprises, in response to detecting the deformation, calculating a corrected touch location based on a magnitude of the detected deformation.

12. The method of claim 11, wherein calculating the corrected touch location comprises:

identifying a compensation profile corresponding to the detected deformation; and

calculating a corrected measurement for each of the plurality of capacitance measurements based on the compensation profile.

13. An apparatus, comprising:

a flexible touch-sensing surface including a flexible overlay, a flexible substrate, and a plurality of sensor elements of a capacitive sensor array, the plurality of sensor elements being positioned between the flexible substrate and the flexible overlay;

wherein the flexible touch-sensing surface overlays a display panel without a shield layer being provided against capacitive coupling between the plurality of sensor elements and the display panel;

a capacitive sensor input configured to receive a plurality of capacitance measurements from the capacitive sensor array, wherein the plurality of capacitance measurements includes a first capacitance measurement from a first sensor element of the capacitive sensor array and a second capacitance measurement from a second sensor element of the capacitive sensor array, wherein the second sensor element is within a same set of rows or columns separated by a predetermined distance from the first sensor element; and

a processing unit coupled with the capacitive sensor input, wherein the processing unit is configured to;

determine whether deformation of the flexible touch-sensing surface is detected based on a comparison between the first capacitance measurement being a highest magnitude value of the plurality of capacitance measurements and the second capacitance measurement being a second magnitude value;

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

when the deformation is detected, compensate for touch coordinate inaccuracies caused by the deformation.

14. The apparatus of claim 13, wherein the processing unit performs the comparison by calculating a ratio between the first capacitance measurement and the second capacitance measurement.

15. The apparatus of claim 13, 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.

16. An apparatus, comprising:

a flexible touch-sensing surface including a flexible overlay, a flexible substrate, and

an array of sensor elements, the array of sensor elements being positioned between the flexible substrate and the flexible overlay;

wherein the flexible touch-sensing surface overlays a display panel without a shield layer being provided against capacitive coupling between the array of sensor elements and the display panel;

a capacitance sensor coupled with the array of sensor elements, wherein the capacitance sensor is configured to take a plurality of capacitance measurements from the array of sensor elements, wherein the plurality of capacitance measurements includes a first capacitance measurement from a first sensor element of the array of sensor elements and a second capacitance measurement from a second sensor element of the array of sensor elements, and wherein the second sensor element is within a same set of rows or columns separated by a predetermined distance from the first sensor element;

a processing logic coupled with the capacitance sensor, wherein the processing logic is configured to;

determine whether deformation of the flexible touch-sensing surface is detected based on a comparison between the first capacitance measurement being a highest magnitude value of the plurality of capacitance measurements and the second capacitance measurement being a second magnitude value;

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

when the deformation is detected, compensate for touch coordinate inaccuracies caused by the deformation.

17. The apparatus of claim 16, wherein the processing logic is further configured to transmit a last known touch location to a host in response to detecting the deformation.