Technique for increasing the sensitivity of capacitive sensor arrays

• US 9,507,465 B2
• Filed: 07/25/2006
• Issued: 11/29/2016
• 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): Boddie, William
• Assistant Examiner(s): Shapiro, Leonid
• Application Number:
  US11/493,350
• Publication Number:
  US 20080024455A1
• Time in Patent Office: 3,780 Days
• Field of Search: 345/161, 345/173, 345/156
• US Class Current: 1/1
• 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. The technique includes logically grouping capacitance sensors of an array of capacitance sensors into sensor groups. The sensor groups each include at least two capacitance sensors of the array of capacitance sensors. Values indicative of a capacitance for each of the sensor groups are measured. The measured values are then analyzed to determine a location of a user interaction with the array of capacitance sensors.

Claims

1. A method comprising:

electrically coupling capacitance sense electrodes of a capacitive sense array into a first group of a plurality of groups, each of the plurality of groups comprising two or more capacitance sense electrodes, wherein the capacitive sense array is configured to sense capacitance indicative of a touch proximate the capacitive sense array;

measuring, at a first time, a first single value of a capacitance of the first group comprising the two or more capacitance sense electrodes;

electrically coupling the capacitance sense electrodes of the capacitive sense array into a second group of the plurality of groups, wherein the first group and the second group of the plurality of groups are different groups and comprise at least one capacitance sense electrode in common;

measuring a second single value of a capacitance of the second group at a second time, the second time being different from the first time; and

analyzing at least the first single value and the second single value to determine a location of a user interaction with the capacitive sense array.

2. The method of claim 1, wherein electrically coupling the capacitance sense electrodes comprises sequentially connecting, during scanning, each of the plurality of groups to a shared capacitance sensor circuit.

3. The method of claim 1, further comprising:

assigning the first single value to a particular capacitance sense electrode within the first group; and

assigning the second single value to a particular capacitance sense electrode within the second group.

4. The method of claim 3, wherein the first group and the second group each comprises physically adjacent capacitance sense electrodes.

5. The method of claim 4, wherein the first group and the second group each comprises an odd number of the capacitance sense electrodes, wherein assigning the first single value comprises assigning the first single value to a middle capacitance sense electrode of the first group, and wherein assigning the second single value comprises assigning the second single value to a middle capacitance sense electrode of the second group.

6. The method of claim 1, wherein analyzing the first single value and the second single value comprises interpolating a center of the location of the user interaction with the plurality of groups based on the first single value and the second value.

7. The method of claim 1, wherein the capacitance sense electrodes of the capacitive sense array are part of a linear slider of a user interface.

8. The method of claim 1, wherein the capacitance sense electrodes of the capacitive sense array are part of a circular slider of user interface.

9. The method of claim 1, wherein the capacitance sense electrodes of the capacitive sense array are part of a touch pad of a user interface.

10. The method of claim 1, further comprising:

scanning, discretely and individually, each of the capacitance sense electrodes of the capacitive sense array; and

determining an approximate location of the user interaction based on the scanning,

wherein measuring the first single value and measuring the second single value comprises measuring a capacitance for a portion of the plurality of groups localized about the approximate location to more precisely determine the location after the discretely and individually scanning of each of the capacitance sense electrodes, wherein the portion of the plurality of groups is less than all of the plurality of groups of the capacitive sense array.

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

electrically couple, by the processing device, capacitance sense electrodes of a capacitive sense array into a first group of a plurality of groups, each of the plurality of groups comprising two or more capacitance sense electrodes, wherein the capacitive sense array is configured to sense capacitance indicative of a touch proximate the capacitive sense array;

measure, at a first time, a first single value of a combined capacitance of the first group comprising the two or more capacitance sense electrodes;

electrically couple the capacitance sense electrodes of the capacitive sense array into a second group of the plurality of groups, wherein a first group and a second group of the plurality of groups are different groups and comprise at least one capacitance sense electrode in common;

measure a second single value of a combined capacitance of the second group at a second time, the second time being different from the first time; and

analyze at least the first single value and the second single value to determine a location of a user interaction with the capacitive sense array.

12. The non-transitory machine-readable medium of claim 11, wherein the first group and the second group each comprise physically adjacent capacitance sense electrodes.

13. The non-transitory machine-readable medium of claim 11, the processing device further to:

scan, discretely and individually, each of the capacitance sense electrodes of the capacitive sense array; and

determine an approximate location of the user interaction based on the scanning,

wherein to measure the first single value and measure the second single value the processing device to measure a capacitance for a portion of the plurality of groups localized about the approximate location to more precisely determine the location after the discretely and individually scanning of each of the capacitance sense electrodes, wherein the portion of the of the plurality of groups is less than all of the plurality of groups within the capacitive sense array.

14. An apparatus comprising:

a processing device;

a user interface comprising capacitance sense electrodes of a capacitive sense array coupled to the processing device, wherein the capacitive sense array is configured to sense capacitance indicative of a touch proximate the capacitive sense array; and

a memory unit coupled to the processing device, the memory unit having stored therein instructions that when executed by the processing device cause the processing device to;

electrically couple the capacitance sense electrodes of the capacitive sense array into a first group of a plurality of groups, each of the plurality of groups comprising two or more capacitance sense electrodes;

measure, at a first time, a first single value of a combined capacitance of the first group comprising the two or more capacitance sense electrodes;

electrically couple the capacitance sense electrodes of the capacitive sense array into a second group of the plurality of groups, wherein the first group and the second group of the plurality of groups are different groups and comprise at least one capacitance sense electrode in common;

measure a second single value of a combined capacitance of the second group at a second time, the second time being different from the first time; and

analyze at least the first single value and the second single value to determine a location of a user interaction with the capacitive array.

15. The apparatus of claim 14, wherein the first group and the second group each comprise physically adjacent capacitance sense electrodes.

16. The apparatus of claim 14, wherein the processing device comprises:

a capacitance sensor circuit coupled to the capacitive sense array and configured to measure the first single value and the second single value; and

an analog multiplexer bus coupled to the capacitance sensor circuit and configured to sequentially couple the plurality of groups to the capacitance sensor circuit.

17. The apparatus of claim 16, wherein the capacitance sensor circuit comprises a relaxation oscillator circuit.

18. The apparatus of claim 17, wherein the user interface is at least one of a linear slider, a circular slider, or a touch pad.