Tapered capsense structure

• US 20070271399A1
• Filed: 05/18/2006
• Published: 11/22/2007
• Est. Priority Date: 05/18/2006
• Status: Active Grant

• Current Assignee: Wistron Corporation
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Peng, Tao, Qin, Zheng
• Granted Patent: US 8,121,283 B2
• Time in Patent Office: Days
• US Class Current: 710/1
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• 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

A touchpad has interleaved conductive traces across a touchpad surface. Each conductive trace has a first end and a second end. The width of the first end is larger than the width of the second end. The interleaved conductive traces have a first group of conductive traces alternated with a second group of conductive traces.

Claims

1. An apparatus, comprising:

a plurality of interleaved conductive traces of a touchpad,

wherein each conductive trace has a first end and a second end, the width of the first end being larger than the width of the second end.

2. The apparatus of claim 1, wherein the plurality of interleaved conductive traces comprises a first group of conductive traces alternated with a second group of conductive traces.

3. The apparatus of claim 2, wherein the first end of the first group of conductive traces is adjacent to the first end of the second group of conductive traces.

4. The apparatus of claim 3, wherein the width of each conductive trace of the first group of conductive traces at the first end is larger than the width of each conductive trace of the second group of conductive traces at the first end.

5. The apparatus of claim 4, wherein the width of each conductive trace of the first group of conductive traces decreases gradually from the first end of the first group of conductive traces to the second end of the first group of conductive traces.

6. The apparatus of claim 5, wherein the width of each conductive trace of the second group of conductive traces increases gradually from the first end of the second group of conductive traces to the second end of the second group of conductive traces.

7. The apparatus of claim 2, wherein one or more conductive trace of the first group of conductive traces is in the shape of a triangle, and one or more conductive trace of the second group of conductive traces is in the shape of a triangle.

8. The apparatus of claim 1, wherein the plurality of interleaved conductive traces are substantially in a same plane.

9. The apparatus of claim 2, wherein the first group of conductive traces is on a first plane, wherein the second group of conductive traces is on a second plane parallel to the first plane.

10. The apparatus of claim 1, comprising:

a circuit board having a first side and a second side, the plurality of interleaved conductive traces formed on the first side; and

a processing device coupled to the second side of the circuit board.

11. The apparatus of claim 10, wherein each conductive trace is coupled to a corresponding capacitive sensing pin of the processing device.

12. The apparatus of claim 10, wherein the plurality of interleaved conductive traces form a single layer on the first side of the circuit board.

13. The apparatus of claim 10, comprising:

an overlay coupled to the plurality of interleaved conductive traces with a non-conductive adhesive layer.

14. A method for manufacturing a touchpad, comprising:

providing a circuit board having a first side and a second side;

forming on a plane, a plurality of interleaved conductive traces of a touchpad on the first side of the circuit board,

wherein each conductive trace has a first end and a second end, the width of the first end being larger than the width of the second end.

15. The method of claim 14, comprising:

coupling a processing device to the second side of the circuit board.

16. The method of claim 15, comprising:

connecting each conductive trace to a corresponding capacitive sensing pin of the processing device.

17. The method of claim 14, wherein the plurality of interleaved conductive traces comprises a first group of conductive traces alternated with a second group of conductive traces.

18. A method for operating a touchpad, comprising:

providing a single layer of a plurality of interleaved conductive traces of a touchpad, each conductive trace having a first end and a second end, the width of the first end being larger than the width of the second end;

measuring a capacitance variation of a conductive trace;

comparing a capacitance variation of at least one adjacent conductive trace to the conductive trace; and

determining a two-dimensional coordinate position on the touchpad based on the comparison.

19. The method of claim 18, comprising:

determining a first axis position of the touchpad based on the measurement; and

determining a second axis position of the touchpad using the comparison.

20. An apparatus, comprising:

means for measuring a two-dimensional coordinate position on a touchpad,

wherein the means for measuring are substantially in a same plane.