Edge accuracy in a capacitive sense array

• US 9,116,581 B2
• Filed: 09/01/2011
• Issued: 08/25/2015
• Est. Priority Date: 08/24/2011
• Status: Active Grant

• Current Assignee: Parade Technologies, Ltd.
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Peng, Tao, Chai, Min Chin
• Primary Examiner(s): Koval, Melissa
• Assistant Examiner(s): Miller, Daniel
• Application Number:
  US13/223,702
• Publication Number:
  US 20130049771A1
• Time in Patent Office: 1,454 Days
• Field of Search: 178/18.06, 178/19.03, 324658-690, 341/33, 345/173, 345/174
• US Class Current: 1/1
• CPC Class Codes: G01R 27/2605 Measuring capacitance capacitive sensors G01D5/24
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer

Abstract

A capacitive sense array configured to improve edge accuracy in detecting a presence of a conductive object is described. In one embodiment, a capacitive sense array includes at least a first set of sense elements having non-homogenous pitches disposes in a first longitudinal axis of the capacitive sense array. The pitch includes width of the sense elements and spacing between the sense elements.

Claims

1. A capacitive sense array, the array comprising:

a first set of sense elements having a plurality of non-homogenous pitches, the first set of sense elements disposed in a first longitudinal axis of the capacitive sense array, wherein a pitch of a sense element of the first set of sense elements comprises a width of the sense element and a spacing between the sense element and an adjacent sense element of the first set of sense elements, wherein the sense element is not directly coupled to any other of the first sense elements through a conductor, the width of the sense element is different from a width of the adjacent sense element, and spacing between a plurality of sense elements of the first set of sense elements is non-homogenous.

2. The capacitive sense array of claim 1, wherein widths of greater than two of the sense elements are non-homogenous.

3. The capacitive sense array of claim 1, wherein widths of greater than two of the sense elements are non-homogenous.

4. The capacitive sense array of claim 1, wherein the first set of sense elements comprises a first sense element having a pitch smaller than a pitch of another sense element of the first set of sense elements.

5. The capacitive sense array of claim 4, wherein the first sense element is an edge sense element disposed closer to an edge of the capacitive sense array than any other of the sense elements of the first set of sense elements.

6. The capacitive sense array of claim 4, wherein the other sense element of the first set of sense elements is an inner sense element disposed closer to a center of the capacitive sense array than an edge sense element of the first set of sense elements, the edge sense element disposed closer to an edge of the capacitive sense array than the inner sense element.

7. The capacitive sense array of claim 1, further comprising a second set of sense elements disposed in a second longitudinal axis of the capacitive sense array, wherein said second longitudinal axis is perpendicular to the first longitudinal axis.

8. The capacitive sense array of claim 7, further comprising a processing device coupled to the capacitive sense array, wherein the processing device is to detect a presence of a conductive object, the processing device is further to use the first set of non-homogenous pitch sense elements as one of transmission (Tx) sense elements and receive (Rx) sense elements and the second set of sense elements as the other one of the Tx sense elements and the Rx sense elements.

9. A capacitive sense array, the array comprising:

a first set of sense elements having a plurality of non-homogenous first pitches, the first set of sense elements comprised of a conductive material and disposed in a first longitudinal axis of the capacitive sense array, wherein each of the first pitches comprises a first width of one of the sense elements of the first set of sense elements and a first spacing between the one of the sense elements and an adjacent sense element of the first set of sensor elements, wherein the one of the sense elements is not coupled, through the conductive material, to the adjacent sense element, and wherein a spacing between the one of the sense elements and an edge of the capacitive sensor array is smaller than a spacing between at least two of the sense elements of the first set of sense elements; and

a second set of sense elements having non-homogenous second pitches disposed in a second longitudinal axis of the capacitive sense array, wherein the second longitudinal axis is substantially perpendicular to the first longitudinal axis, wherein the second pitch comprises a second width of one of the sense elements of the second set of sense elements and a second spacing between one of the sense elements of the second set of sense elements and an adjacent sense element of the second set of sense elements, wherein each of the sense elements is associated with a separate conductive trace to a sensing circuit.

10. The capacitive sense array of claim 9, wherein the first widths of the first set of sense elements are non-homogenous and the second widths of the second set of sense elements are non-homogenous.

11. The capacitive sense array of claim 9, wherein the first widths of the first set of sense elements are non-homogenous and the second widths of the second set of sense elements are homogenous.

12. The capacitive sense array of claim 9, wherein the spacing between the first set of sense elements is non-homogenous and the spacing between the second set of sense elements is homogenous.

13. The capacitive sense array of claim 9, wherein the spacing between the first set of sense elements is non-homogenous and the spacing between the second set of sense elements is non-homogenous.

14. The capacitive sense array of claim 9, wherein the first set comprises at least a first sense element whose greatest width is smaller than that of at least one of other sense elements of the first set, and wherein the second set comprises at least a second sense element whose greatest width is smaller than that of at least one of other sense elements of the second set.

15. The capacitive sense array of claim 14, wherein the first sense element is a first edge sense element disposed closest to an edge of the capacitive sense array in the first longitudinal axis, and wherein the second sense element is a second edge sense element disposed closest to an edge of the capacitive sense array in the second longitudinal axis.

16. The capacitive sense array of claim 14, wherein the first sense element is a first inner sense element disposed closer to a center of the capacitive sense array than an edge sense element disposed closest to an edge of the capacitive sense array in the first longitudinal axis, and wherein the second sense element is a second inner sense element disposed closer to a center of the capacitive sense array than an edge sense element disposed closest to an edge of the capacitive sense array in the second longitudinal axis.

17. The capacitive sense array of claim 9, further comprising a processing device coupled to the capacitive sense array, wherein the processing device is to detect a presence of a conductive object, the processing device is further to use the first set of non-homogenous pitch sense elements as one of transmission (Tx) sense elements and receive (Rx) sense elements and the second set of non-homogenous pitch sense elements as the other one of the Tx sense elements and the Rx sense elements.