Capacitive sensing apparatus having varying depth sensing elements

• US 20060038791A1
• Filed: 08/19/2004
• Published: 02/23/2006
• Est. Priority Date: 08/19/2004
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Mackey, Bob Lee
• Granted Patent: US 7,737,953 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes

Abstract

One embodiment in accordance with the invention includes a capacitive sensor apparatus that includes a first sensing element having substantially constant width along its length and configured to have varying capacitive coupling to an object proximate to a capacitive sensing reference surface, along a first axis of the capacitive sensing reference surface. The length of the first sensing element is oriented along the first axis. The capacitive sensor apparatus can include a second sensing element having substantially constant width along its length and configured to have varying capacitive coupling to the object proximate to the capacitive sensing reference surface along the first axis. The length of the second sensing element is oriented along the first axis. The first and second sensing elements are conductive, and are configured to provide information corresponding to a spatial location of the object relative to the first axis of the capacitive sensing reference surface.

Claims

1. A capacitive sensor apparatus comprising:

a first sensing element having substantially constant width along its length and configured to have varying capacitive coupling to an object proximate to a capacitive sensing reference surface, along a first axis of said capacitive sensing reference surface, wherein said length of first sensing element is oriented along said first axis; and

a second sensing element having substantially constant width along its length and configured to have varying capacitive coupling to said object proximate to said capacitive sensing reference surface along said first axis, said length of said second sensing element oriented along said first axis, wherein said first sensing element and said second sensing element are conductive, and are configured to provide information corresponding to a spatial location of said object relative to said first axis of said capacitive sensing reference surface.

2. The capacitive sensor apparatus of claim 1, wherein said capacitive coupling associated with said first sensing element varies with varying distance of portions of said first sensing element with respect to said capacitive sensing reference surface.

3. The capacitive sensor apparatus of claim 2, wherein said capacitive coupling associated with said second sensing element varies with varying distance of portions of said second sensing element with respect to said capacitive sensing reference surface, said varying distance of said portions of said first sensing element different from said varying distance of said portions of said second sensing element.

4. The capacitive sensor apparatus of claim 3, wherein said first sensing element and said second sensing element each comprises a strip of conductive material.

5. The capacitive sensor apparatus of claim 4, wherein said strip of conductive material of said first sensing element is substantially straight and decreases in distance relative to said capacitance sensing surface along said first axis and wherein said strip of conductive material of said second sensing element is substantially straight and increases in distance relative to said capacitance sensing surface along said first axis.

6. The capacitive sensor apparatus of claim 4, wherein said strip of conductive material of said first sensing element and said strip of conductive material of said second sensing element are twisted about a common axis.

7. The capacitive sensor apparatus of claim 1, wherein:

said capacitive coupling of said first sensing element comprises a first waveform; and

said capacitive coupling of said second sensing element comprises a second waveform.

8. The capacitive sensor apparatus of claim 7, wherein:

said capacitive coupling of said first sensing element comprises a first phase; and

said capacitive coupling of said second sensing element comprises a second phase different from said first phase.

9. The capacitive sensor apparatus of claim 1, wherein said capacitive coupling of said first sensing element and said capacitive coupling of said second sensing element each comprises a sinusoidal waveform.

10. The capacitive sensor apparatus of claim 1, wherein said capacitive coupling of said first sensing element varies with variations in the dielectric constant between said capacitive sensing reference surface and portions of said first sensing element.

11. The capacitive sensor apparatus of claim 10, wherein said capacitive coupling of said second sensing element varies with variations in the dielectric constant between said capacitive sensing reference surface and portions of said second sensing element, said variations in the dielectric constant for said first sensing element different from said variations in the dielectric constant for said second sensing element.

12. The capacitive sensor apparatus of claim 1, wherein said first sensing element and said second sensing element separately provide said information corresponding to said spatial location of said object.

13. The capacitive sensor apparatus of claim 1, further comprising:

a third sensing element having a length oriented along said first axis and configured to provide information corresponding to a spatial location of said object relative to a second axis of said capacitive sensing reference surface.

14. A capacitive sensing device comprising:

a first sensing element having varying depth relative to a capacitive sensing reference surface;

a second sensing element substantially parallel to said first sensing element, and having varying depth relative to said capacitive sensing reference surface; and

a third sensing element substantially parallel to said first sensing element, and having varying depth relative to said capacitive sensing reference surface, wherein said first sensing element, second sensing element, and third sensing element are configured to provide information corresponding to a position of an object proximate to said capacitive sensing reference surface along a first axis of said capacitive sensing reference surface.

15. The capacitive sensing device of claim 14, wherein:

portions of said first sensing element are configured to have a capacitive coupling with respect to said object wherein said capacitive coupling varies along said first axis;

portions of said second sensing element are configured to have a capacitive coupling with respect to said object wherein said capacitive coupling varies along said first axis; and

portions of said third sensing element are configured to have a capacitive coupling with respect to said object wherein said capacitive coupling varies along said first axis.

16. The capacitive sensing device of claim 14, wherein:

said first sensing element has varying depth comprising a waveform;

said second sensing element has varying depth comprising a waveform that is offset from said waveform of said first sensing element by one third of a period; and

said third sensing element has varying depth comprising a waveform that is offset from said waveform of said first sensing element by two thirds of a period.

17. The capacitive sensing device of claim 14, wherein said position is determined using a signal corresponding to said first sensing element, a signal corresponding to said second sensing element, and a signal corresponding to said third sensing element.

18. The capacitive sensing device of claim 17, wherein said position is determined using a trigonometric function.

19. The capacitive sensing device of claim 14, wherein said first sensing element, said second sensing element, and said third sensing element each comprises a conductive trace.

20. The capacitive sensing device of claim 19, wherein each said conductive trace is disposed above a substrate, wherein a side of said substrate comprises channels of varying depths, said varying depths defining a unique depth profile for each of said first, second, and third sensing elements.

21. The capacitive sensing device of claim 14, wherein at least one of said first sensing element, second sensing element, and third sensing element is used for determining a second position along a second axis substantially perpendicular to said first axis.

22. The capacitive sensing device of claim 14, wherein:

said first sensing element has varying depth comprising a first sinusoidal waveform;

said second sensing element has varying depth comprising a second sinusoidal waveform offset from said first sinusoidal waveform; and

said third sensing element has varying depth comprising a third sinusoidal waveform offset from said first sinusoidal waveform and said second sinusoidal waveform.

23. The capacitive sensing device of claim 14, further comprising:

a fourth sensing element utilized for determining a second position along a second axis that is non-parallel to said first axis.

24. The capacitive sensing device of claim 14, further comprising:

a fourth sensing element having varying depth;

a fifth sensing element having varying depth;

a sixth sensing element having varying depth, wherein said fourth, fifth, and sixth sensing elements are substantially parallel to said first sensing element, and are configured for determining said position along said first axis.

25. The capacitive sensing device of claim 24, wherein at least one of said first, second, third, fourth, fifth, and sixth sensing elements is configured for determining a second position along a second axis, said second axis not parallel to said first axis.

26. The capacitive sensing device of claim 14, wherein said first, second, and third sensing elements are utilized as part of a capacitive touch pad device.

27. A portable electronic device comprising:

a processor coupled with said capacitive sensor, wherein said capacitive sensor comprises;

a first sensing element having varying depth comprising a sine (θ

) waveform;

a second sensing element having varying depth comprising a sine (θ

) waveform shifted by 2π

/3 radians from said sine (θ

) waveform of said first sensing element; and

a third sensing element having varying depth comprising a sine (θ

) waveform shifted from said sine (θ

) waveform of said first sensing element by 4π

/3 radians, wherein said first sensing element, second sensing element, and third sensing element are each conductive and substantially parallel to a first axis, wherein said first sensing element, second sensing element and third sensing element are configured to provide information corresponding to a first position along said first axis.

28. The portable electronic device of claim 27, wherein at least one of said first sensing element, second sensing element, and third sensing element is used for determining a second position along a second axis not parallel to said first axis.

29. The portable electronic device of claim 27, wherein said first location along said first axis is determined using signals from said first sensing element, said second sensing element, and said third sensing element.

30. The portable electronic device of claim 27, wherein said first location along said first axis is determined using a trigonometric function.

31. The portable electronic device of claim 27, further comprising:

a fourth sensing element utilized to determine a second location along a second axis that is substantially perpendicular to said first axis.

32. A capacitive sensor device comprising:

a first sensing element configured to have varying capacitive coupling to an object proximate to a capacitive sensing reference surface; and

a second sensing element configured to have varying capacitive coupling to said object proximate to said capacitive sensing reference surface, wherein said first sensing element and said second sensing element are conductive, and are configured to provide information corresponding to a spatial location of said object proximate to a curve on said capacitive sensing reference surface.

33. The capacitive sensor device of claim 32, wherein said first sensing element and said second sensing element are oriented in a substantially linear manner.

34. The capacitive sensor device of claim 32, wherein said first sensing element and said second sensing element are oriented in a non-linear manner.

35. The capacitive sensor device of claim 34, wherein said non-linear manner comprises a curve.

36. The capacitive sensor device of claim 34, wherein said non-linear manner comprises a loop.

37. The capacitive sensor device of claim 32, wherein said capacitive coupling associated with said first sensing element varies with varying distance of portions of said first sensing element with respect to said capacitive sensing reference surface.

38. The capacitive sensor device of claim 37, wherein said capacitive coupling associated with said second sensing element varies with varying distance of portions of said second sensing element with respect to said capacitive sensing reference surface, said varying distance of said portions of said first sensing element different from said varying distance of said portions of said second sensing element.

39. The capacitive sensor device of claim 32, wherein said first sensing element and said second sensing element each comprises a strip of conductive material.

40. A method for establishing a position-varying capacitive coupling between a conductive object proximate to a capacitive sensing reference surface and a conductive trace, said method comprising:

providing a plurality of channel patterns in a substrate, said channel patterns varying in depth; and

depositing a conductive material onto said channel patterns to form a first sensing element and second sensing element, wherein said first sensing element and second sensing element are conductive and lie substantially along a first orientation and each of said first sensing element and second sensing element is configured to provide information corresponding to a first location along said first orientation.

41. The method as recited in claim 40, wherein said first orientation is substantially linear.

42. The method as recited in claim 40, wherein said first orientation is non-linear.

43. The method as recited in claim 40, wherein:

said first sensing element comprises a first waveform; and

said second sensing element comprises a second waveform.

44. The method as recited in claim 40, further comprising:

backfilling said first sensing element with a material.

45. The method as recited in claim 40, wherein said first sensing element and said second sensing element each forms at least a portion of a loop.