Single layer multi-touch capacitive sensor

1. A method for operating a capacitive sensing device, the method comprising:

providing a substrate having a plurality of pairs of conductive traces formed thereon, each of the plurality of pairs of conductive traces comprising a first conductive trace having at least one sub-trace and a second conductive trace having at least one sub-trace, wherein within each of the plurality of pairs of conductive traces at least one sub-trace of the first conductive trace is interleaved with at least one sub-trace of the second conductive trace, each sub-trace of the first and second conductive traces having a variable width from a first end to a second end thereof;

measuring a capacitance variation of a plurality of the first conductive traces and a plurality of the second conductive traces, wherein the capacitance variation of at least some of the second conductive traces is measured before the capacitance variation for all of the plurality of first conductive traces is measured; and

determining a position coordinate in a two-dimensional coordinate system on the capacitive sensing device based on the measuring a capacitance variation of a plurality of the first conductive traces and a plurality of the second conductive traces.

2. The method of claim 1 , wherein the measuring a capacitance variation of a plurality of the first conductive traces and a plurality of the second conductive traces comprises:

measuring the capacitance variation of the first conductive trace and the second conductive trace within a first of the plurality of pairs of conductive traces; and

measuring the capacitance variation of the first conductive trace and the second conductive trace within a second of the plurality of pairs of conduct traces after the measuring the capacitance variation of the first conductive trace and the second conductive trace within the first of the plurality of pairs of conductive traces.

3. The method of claim 1 , wherein the measuring a capacitance variation of a plurality of the first conductive traces and a plurality of the second conductive traces comprises measuring a capacitance variation of one of the plurality of the first conductive traces and one of the plurality of second conductive traces in an alternating manner.

4. The method of claim 1 , further comprising:

if a change in the measured capacitance variation of the plurality of the first conductive traces and the plurality of the second conductive traces exceeds a predetermined threshold, re-measuring the capacitance variation of the plurality of the first conductive traces and the plurality of the second conductive traces; and

determining the position coordinate in the two-dimensional coordinate system on the capacitive sensing device based on the re-measured capacitance variation of the plurality of the first conductive traces and the plurality of the second conductive traces.

5. The method of claim 4 , wherein the change in the measured capacitance variation is an increase in the measured capacitance variation.

6. The method of claim 4 , wherein the change in the measured capacitance variation is a decrease in the measured capacitance variation.

7. The method of claim 1 , wherein the plurality of pairs of conductive traces are arranged in a plurality of rows, and wherein at least one sub-trace of the first and second conductive traces are substantially aligned with the plurality of rows.

8. The method of claim 7 , wherein the first conductive traces and the second conductive traces each comprises a plurality of protrusions extending from the at least one sub-trace thereof in a direction that is substantially perpendicular to the plurality of rows.

9. The method of claim 8 , wherein the plurality of protrusions extending from the sub-traces of the first conductive traces extend into one of the sub-traces of the second conductive traces, and the plurality of protrusions extending from the sub-traces of the second conductive traces extend into one of the sub-traces of the first conductive traces.

10. The method of claim 9 , wherein the plurality of protrusions extending from the sub-traces of the first conductive traces are electrically insulated from the sub-traces of the second conductive traces, and the plurality of sub-traces extending from the sub-traces of the second conductive traces are electrically insulated from the sub-traces of the first conductive traces.

11. A capacitive sensing device comprising:

a capacitive sensing array comprising:

a substrate; and

a plurality of pairs of conductive traces formed on the substrate, each of the plurality of pairs of conductive traces comprising a first conductive trace having at least one sub-trace and a second conductive trace having at least one sub-trace, wherein within each of the plurality of pairs of conductive traces at least one sub-trace of the first conductive trace is interleaved with at least one sub-trace of the second conductive trace, each sub-trace of the first and second conductive traces having a variable width from a first end to a second end thereof; and

a processing device coupled to the capacitive sensing array, the processing device being configured to:

measure a capacitance variation of a plurality of the first conductive traces and a plurality of the second conductive traces, wherein the capacitance variation of at least some of the second conductive traces is measured before the capacitance variation for all of the plurality of first conductive traces is measured; and

determine a position coordinate in a two-dimensional coordinate system on the capacitive sensing device based on the measuring a capacitance variation of a plurality of the first conductive traces and a plurality of the second conductive traces.

12. The capacitive sensing device of claim 11 , wherein the plurality of pairs of conductive traces are arranged in a plurality of rows, and wherein at least one sub-trace of the first and second conductive traces are substantially aligned with the plurality of rows.

13. The capacitive sensing device of claim 12 , wherein the first conductive traces and the second conductive traces each comprises a plurality of protrusions extending from the sub-traces thereof in a direction that is substantially perpendicular to the plurality of rows.

14. The capacitive sensing device of claim 13 , wherein the plurality of protrusions extending from the sub-traces of the first conductive traces extend into one of the sub-traces of the second conductive traces, and the plurality of protrusions extending from the sub-traces of the second conductive traces extend into one of the sub-traces of the first conductive traces.

15. The capacitive sensing device of claim 14 , wherein the plurality of protrusions extending from the sub-traces of the first conductive traces are electrically insulated from the sub-traces of the second conductive traces, and the plurality of protrusions extending from the sub-traces of the second conductive traces are electrically insulated from the sub-traces of the first conductive traces.

16. A method for operating a capacitive sensing device, the method comprising:

providing a substrate having a plurality of pairs of conductive traces formed thereon, the plurality of pairs of conductive traces being arranged in a plurality of rows, each of the plurality of pairs of conductive traces comprising a first conductive trace having at least one sub-trace and a second conductive trace having at least one sub-trace, wherein within each of the plurality of pairs of conductive traces at least one sub-trace of the first conductive trace is interleaved with at least one sub-trace of the second conductive trace, each sub-trace of the first and second conductive traces having a variable width from a first end to a second end thereof and being substantially aligned with the plurality of rows;

measuring a capacitance variation of a plurality of the first conductive traces and a plurality of the second conductive traces in an alternating manner; and

determining the presence of an object relative to the substrate based on the measuring a capacitance variation of a plurality of the first conductive traces and a plurality of the second conductive traces.

17. The method of claim 16 , further comprising:

if a change in the measured capacitance variation of the plurality of the first conductive traces and the plurality of the second conductive traces exceeds a predetermined threshold, re-measuring the capacitance variation of the plurality of the first conductive traces and the plurality of the second conductive traces in an alternating manner; and

determining the presence of an object relative to the substrate based on the re-measured capacitance variation of the plurality of the first conductive traces and the plurality of the second conductive traces.

18. The method of claim 16 , wherein the presence of the object relative to the substrate is only determined if a combined capacitance variation of at least two of the plurality of first and second conductive traces exceeds a predetermined threshold.

19. The method of claim 16 , wherein when the measured capacitance variation corresponds to one of the plurality of first and second conductive traces located at an interior of the plurality of pairs of conductive traces, the presence of the object relative to the substrate is only determined if the measured capacitance variation exceeds a first threshold, and when the measured capacitance variation corresponds to one of the plurality of first and second conductive traces located at an edge of the plurality of pairs of conductive traces, the presence of the object relative to the substrate is only determined if the measured capacitance variation exceeds a second threshold, wherein the second threshold is greater than the first threshold.

20. The method of claim 16 , wherein the first conductive traces and the second conductive traces each comprises a plurality of protrusions extending from the at least one sub-trace thereof in a direction that is substantially perpendicular to the plurality of rows.