Technique for increasing the sensitivity of capacitive sense arrays

• US 10,133,432 B2
• Filed: 10/28/2016
• Issued: 11/20/2018
• Est. Priority Date: 07/25/2006
• Status: Active Grant

• Current Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Lee, Mark R., Seguine, Ryan D.
• Primary Examiner(s): HARRIS, DOROTHY H
• Application Number:
  US15/338,180
• Publication Number:
  US 20170090626A1
• Time in Patent Office: 753 Days
• CPC Class Codes: G01D 5/2417 by varying separation
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/04847 Interaction techniques to control parameter settings, e.g. interaction with sliders or dials

Abstract

A technique for operating a capacitive sensor array is described. The technique includes measuring a first capacitance of a first set of electrodes at a first time, measuring a second capacitance of a second set of electrodes at a second time, and calculating a position of a conductive object based on a relative magnitude of the first capacitance and the second capacitance. The first set and the second set includes at least one electrode in common and at least one electrode that is not in common.

Claims

1. A method comprising:

measuring a first capacitance of a first plurality of electrodes at a first time, wherein the measured first capacitance is indicative of a first combined capacitance of the first plurality of electrodes;

measuring a second capacitance of a second plurality of electrodes at a second time, wherein the measured second capacitance is indicative of a second combined capacitance of the second plurality of electrodes and wherein the first plurality of electrodes and the second plurality of electrodes comprises at least one electrode in common and at least one electrode that is not in common; and

calculating a position of a conductive object based on a relative magnitude of the measured first capacitance and the measured second capacitance.

2. The method of claim 1, further comprising:

electrically coupling the first plurality of electrodes in a first group; and

electrically coupling the second plurality of electrodes in a second group, wherein the first group and the second group are different but comprise at least one common electrode that is in the first group and the second group.

3. The method of claim 2, wherein the electrically coupling the first plurality of electrodes in the first group and electrically coupling the second plurality of electrodes are performed sequentially to a capacitance measurement circuit.

4. The method of claim 1, further comprising:

assigning the measured first capacitance to one of the first plurality of electrodes in the first group; and

assigning the measured second capacitance to one of the second plurality of electrodes in the second group.

5. The method of claim 1, wherein the first plurality of electrodes comprises physically adjacent electrodes.

6. The method of claim 1, further comprising assigning the measured first capacitance to an intermittent electrode of the first plurality of electrodes that are physically adjacent electrodes.

7. The method of claim 6, wherein the first plurality of electrodes comprises an odd number of electrodes and the intermittent electrode is a middle electrode with at least a first electrode adjacent to the middle electrode in a first direction and a second electrode adjacent to the middle electrode in a second direction.

8. The method of claim 1, wherein the calculating the position comprises determining a center of the conductive object using the measured first capacitance and the measured second capacitance.

9. The method of claim 1, wherein the first plurality of electrodes and the second plurality of electrodes are part of a linear slider.

10. The method of claim 1, wherein the first plurality of electrodes and the second plurality of electrodes are part of a circular slider.

11. The method of claim 1, wherein the first plurality of electrodes and the second plurality of electrodes are part of a touch surface of a user interface.

12. The method of claim 1, further comprising:

individually scanning each electrode of a capacitive sense array comprising at least the first plurality of electrodes and the second plurality of electrodes;

determining an approximate location of the conductive object based on the individually scanning; and

based on the approximate location, selecting the first plurality of electrodes and the second plurality of electrodes for localized scanning at the approximate location, wherein the localized scanning comprises the measuring the first capacitance and the measuring the second capacitance.

13. A non-transitory machine-readable medium that stores instructions that when executed by a processing device cause the processing device to:

measure a first capacitance of a first plurality of electrodes at a first time, wherein the measured first capacitance is indicative of a first combined capacitance of the first plurality of electrodes;

measure a second capacitance of a second plurality of electrodes at a second time, wherein the measured second capacitance is indicative of a second combined capacitance of the second plurality of electrodes and wherein the first plurality of electrodes and the second plurality of electrodes comprises at least one electrode in common and at least one electrode that is not in common; and

calculate a position of a conductive object based on a relative magnitude of the measured first capacitance and the measured second capacitance.

14. The non-transitory machine-readable medium of claim 13, wherein the processing device is further to:

individually scan each electrode of a capacitive sense array comprising at least the first plurality of electrodes and the second plurality of electrodes;

determine an approximate location of the conductive object based on the individually scanning; and

based on the approximate location, select the first plurality of electrodes and the second plurality of electrodes for localized scanning at the approximate location.

15. An apparatus comprising:

a processing device;

a user interface device operatively coupled to the processing device, wherein the user interface device comprises a first plurality of electrodes and a second plurality of electrodes, wherein the first plurality of electrodes and the second plurality of electrodes comprises at least one electrode in common and at least one electrode that is not in common, wherein the processing device is configured to;

measure a first capacitance of the first plurality of electrodes at a first time, wherein the measured first capacitance is indicative of a first combined capacitance of the first plurality of electrodes;

measure a second capacitance of the second plurality of electrodes at a second time, wherein the measured second capacitance is indicative of a second combined capacitance of the second plurality of electrodes; and

calculate a position of a conductive object based on a relative magnitude of the measured first capacitance and the measured second capacitance.

16. The apparatus of claim 15, wherein the processing device comprises:

a capacitance measurement circuit coupled to the first plurality of electrodes to measure the first capacitance at the first time and the second plurality of electrodes to measure the second capacitance at the second time; and

an analog multiplexer bus coupled to the capacitance measurement circuit and selectively coupled to the first plurality of electrodes at the first time and the second plurality of electrodes at the second time.

17. The apparatus of claim 16, wherein the analog multiplexer bus is configured to:

electrically couple the first plurality of electrodes in a first group; and

electrically couple the second plurality of electrodes in a second group, wherein the first group and the second group are different but comprise at least one electrode that is in the first group and the second group.

18. The apparatus of claim 17, wherein the analog multiplexer bus is configured to electrically couple the first plurality of electrodes in the first group and electrically couple the second plurality of electrodes sequentially to the capacitance measurement circuit.

19. The apparatus of claim 15, wherein the first plurality of electrodes comprises physically adjacent electrodes.

20. The apparatus of claim 15, wherein the first plurality of electrodes and the second plurality of electrodes are part of a linear slider or a circular slider.