Hard press rejection

• US 9,043,183 B1
• Filed: 10/21/2013
• Issued: 05/26/2015
• Est. Priority Date: 03/11/2013
• Status: Active Grant

• Current Assignee: Parade Technologies, Ltd.
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Ksondzyk, Petro, Ahn, Jae-Bum
• Primary Examiner(s): Le, John H
• Application Number:
  US14/059,200
• Time in Patent Office: 582 Days
• Field of Search: 702 81- 85, 702/94, 702/95, 702/98, 702/104, 702/156, 345/173, 345/174
• US Class Current: 702/156
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• 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 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• 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

Techniques for hard press rejection are described herein. In an example embodiment, a touch area on a sensor array is determined, where the touch area corresponds to a detected object and is associated with multiple signal values. A slope value for the detected object is computed based on a ratio of a signal distribution value in the touch area to a metric indicating a size of the touch area with respect to the sensor array. The slope value is compared to a threshold in order to determine whether to accept or to reject the detected object, and the detected object is rejected based on the comparison.

Claims

1. A method for hard press rejection, the method comprising:

accessing, by a processing device, a set of signal values associated with an object that is detected on a sensor array during a scan operation;

determining, by the processing device, a touch area and parameters thereof corresponding to the detected object on the sensor array, wherein the touch area is associated with multiple signal values from the set of signal values;

computing, by the processing device, a slope value for the detected object based at least on the parameters of the touch area; and

rejecting, by the processing device, the detected object based at least on a comparison of the slope value to a threshold, wherein the threshold is set to a value that is greater than slope values caused by hard presses and less than slope values caused by other objects.

2. The method of claim 1, wherein the threshold is set to the value that is equal to or greater than 110% of the maximum of the slope values caused by the hard presses.

3. The method of claim 1, wherein the other objects include normal fingers and large conductive objects.

4. The method of claim 1, wherein the parameters of the touch area include a signal distribution value in the touch area and a size metric indicating a size of the touch area.

5. The method of claim 4, wherein the slope value is computed based on a ratio of the signal distribution value to the size metric.

6. The method of claim 1, wherein computing the slope value by the processing device comprises one or more of:

normalizing the slope value; and

scaling the slope value.

7. The method of claim 1, wherein the multiple signal values represent a contact by the detected object with the sensor array, wherein the contact is not preceded by another contact which corresponds to the detected object and which was detected in a previous scan operation.

8. The method of claim 1, further comprising:

receiving a plurality of measurements that are measured from the sensor array during the scan operation; and

deriving, by the processing device, the set of signal values from the plurality of measurements.

9. The method of claim 1, wherein the detected object is one of a non-conductive object, a finger in a leather glove, and a plastic cover being pressed into the sensor array.

10. The method of claim 1, wherein the sensor array is one of a mutual capacitance sensor array and a self-capacitance sensor array.

11. A non-transitory firmware storing a set of instructions that comprise firmware instructions which, when executed by a computing device, cause the computing device to perform operations comprising:

accessing a set of signal values associated with an object that is detected on a sensor array during a scan operation;

determining a touch area and parameters thereof corresponding to the detected object on the sensor array, wherein the touch area is associated with multiple signal values from the set of signal values;

computing a slope value for the detected object based at least on the parameters of the touch area; and

rejecting the detected object based at least on a comparison of the slope value to a threshold, wherein the threshold is set to a value that is greater than slope values caused by hard presses and less than slope values caused by other objects.

12. The non-transitory firmware of claim 11, wherein the threshold is set to the value that is equal to or greater than 110% of the maximum of the slope values caused by the hard presses.

13. The non-transitory firmware of claim 11, wherein the other objects include normal fingers and large conductive objects.

14. The non-transitory firmware of claim 11, wherein the parameters of the touch area include a signal distribution value in the touch area and a size metric indicating a size of the touch area.

15. The non-transitory firmware of claim 14, wherein the slope value is computed based on a ratio of the signal distribution value to the size metric.

16. The non-transitory firmware of claim 11, wherein the firmware instructions that cause computing the slope value comprise instructions which, when executed by the computing device, cause the computing device to perform one or more of:

normalizing the slope value; and

scaling the slope value.

17. The non-transitory firmware of claim 11, wherein the multiple signal values represent a contact by the detected object with the sensor array, wherein the contact is not preceded by another contact which corresponds to the detected object and which was detected in a previous scan operation.

18. The non-transitory firmware of claim 11, wherein the firmware instructions further comprise instructions which, when executed by the computing device, cause:

receiving a plurality of measurements that are measured from the sensor array during the scan operation; and

deriving the set of signal values from the plurality of measurements.

19. The non-transitory firmware of claim 11, wherein the detected object is one of a non-conductive object, a finger in a leather glove, and a plastic cover being pressed into the sensor array.

20. The non-transitory firmware of claim 11, wherein the sensor array is one of a mutual capacitance sensor array and a self-capacitance sensor array.