SENSE ELECTRODE DESIGN

• US 20110096016A1
• Filed: 10/26/2009
• Published: 04/28/2011
• Est. Priority Date: 10/26/2009
• Status: Active Grant

• Current Assignee: Neodrón Limited (Atlantic IP Services Limited)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Yilmaz, Esat
• Granted Patent: US 9,916,045 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• 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
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A touch sensitive device includes a plurality of sense electrodes arranged in a pattern to receive charge from drive electrodes. The pattern of sense electrodes has extreme portions having worst case charge transfer times, wherein the worst case charge transfer time at multiple extreme portions is substantially equal.

Claims

1. A touch sensitive device comprising:

a plurality of drive electrodes;

a plurality of sense electrodes arranged in a pattern to receive charge from the drive electrodes, the pattern having extreme portions having charge transfer times, wherein the charge transfer times at multiple extreme portions are substantially equal to a worst case charge transfer time.

2. The touch sensitive device of claim 1 wherein the sense electrodes are formed of transparent conductive layers.

3. The touch sensitive device of claim 2 wherein each sense electrode is formed of a spine having multiple width crossbars coupled to the spine.

4. The touch sensitive device of claim 3 wherein the crossbars are arranged with increasing width from a point of their corresponding spine to couple to sense circuitry.

5. The touch sensitive device of claim 1 wherein the extreme portions are varied in width to achieve the worst case charge transfer time.

6. A sense electrode for a touch sensitive device, the sense electrode comprising:

a spine;

multiple width crossbars coupled to the spine, wherein the crossbars are arranged with increasing width from a point of the spine to couple to sense circuitry.

7. The sense electrode of claim 6 wherein the point of the spine to couple to sense circuitry is at one end of the spine.

8. The sense electrode of claim 6 wherein the spine has two ends, both of which are adapted to couple to sense circuitry and wherein the crossbars are arranged with increasing width from both ends of the spine such that the widest crossbar is approximately halfway between the ends of the spine.

9. The sense electrode of claim 6 wherein each crossbar on a spine has at least one tip that is furthest from the spine, and wherein the charge transfer time from the tips to the end of the spine to couple to sense circuitry does not exceed a predetermined threshold.

10. The sense electrode of claim 9 wherein the predetermined threshold is determined to ensure a desired charge transfer time is not exceeded.

11. The sense electrode of claim 6 wherein a worst case charge transfer time from each tip to the end of the spine to couple to sense circuitry is substantially equal.

12. The sense electrode of claim 6 wherein a width of the spine increases with distance from the end of a spine to couple to sense circuitry.

13. The sense electrode of claim 12 wherein the width of the spine increases incrementally from the end of the spine to couple to sense circuitry.

14. The sense electrode of claim 6 wherein a width of the spine increases incrementally from each end of the spine to couple to sense circuitry such that the widest part of the spine is approximately halfway between the ends of the spine.

15. A touch sensitive device comprising:

a layer of longitudinal adjacent drive electrodes separated from each other by a gap, the layer to be positioned above a display;

a layer of sense electrodes, the sense electrodes formed in the shape of spines running transverse to the drive electrodes and having different width crossbars running in the same direction as the drive electrodes.

16. The touch sensitive device of claim 15 wherein the electrodes are formed of a transparent conductive material and the crossbars increase in width with distance from an end of a spine to couple to sense circuitry.

17. The touch sensitive device of claim 16 wherein each crossbar on a spine has at least one tip that is furthest from the spine, and wherein a worst case charge transfer time from the tips to the end of the spine to couple to sense circuitry does not exceed a predetermined threshold.

18. The touch sensitive device of claim 17 wherein the predetermined threshold is determined to ensure a desired charge transfer time is not exceeded.

19. The touch sensitive device of claim 17 wherein the worst case charge transfer time to each tip is substantially equal.

20. The touch sensitive device of claim 16 wherein a width of the spine increases with distance from the end of a spine to couple to sense circuitry.

21. The touch sensitive device of claim 20 wherein the width of the spine increases incrementally from the end of the spine to couple to sense circuitry.

22. The touch sensitive device of claim 15 wherein each spine has two ends, both of which are adapted to couple to sense circuitry and wherein the crossbars are arranged with increasing width from both ends of the spine such that the widest crossbar is approximately halfway between the ends of the spine.

23. The touch sensitive device of claim 22 wherein the width of the spine increases incrementally from each end of the spine such that the widest part of the spine is approximately halfway between the ends of the spine.

24. A method comprising:

forming a layer of longitudinal adjacent drive electrodes separated from each other by a gap, the layer providing a shield from electric fields from a display; and

forming a layer of sense electrodes separated from the drive electrodes, the sense electrodes formed in the shape of spines running transverse to the drive electrodes and having different width crossbars running in the same direction as the drive electrodes.

25. The method of claim 24 wherein the crossbars increase in width with distance from ends of the spines to couple to sense circuitry.