Capacitive sensing apparatus having varying depth sensing elements

• US 7,737,953 B2
• Filed: 08/19/2004
• Issued: 06/15/2010
• Est. Priority Date: 08/19/2004
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Mackey, Bob Lee
• Primary Examiner(s): Awad; Amr
• Assistant Examiner(s): SIM, YONG H
• Application Number:
  US10/922,574
• Publication Number:
  US 20060038791A1
• Time in Patent Office: 2,126 Days
• Field of Search: 345/173, 345/174, 345/177, 345/178, 178/18.01, 178/18.06, 178/18.03
• 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 sensing device comprising:

a first sensing element having varying depth relative to a capacitive sensing reference surface, said varying depth comprising a waveform;

a second sensing element substantially parallel to said first sensing element, and having varying depth relative to said capacitive sensing reference surface, said varying depth of said second sensing element comprising a waveform that is phase shifted by a value with respect to said waveform of said first sensing element; and

a third sensing element substantially parallel to said first sensing element, and having varying depth relative to said capacitive sensing reference surface, said varying depth of said third sensing element comprising a waveform that is phase shifted by a second value with respect to said waveform of said first sensing element such that said first sensing element, said second sensing element, and said third sensing element comprise waveforms of three differing phases,

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.

2. The capacitive sensing device of claim 1, 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.

3. The capacitive sensing device of claim 1, wherein:

said waveform of said second sensing element is phase shifted from said waveform of said first sensing element by one third of a period; and

said waveform of said third sensing element is phase shifted from said waveform of said first sensing element by two thirds of a period.

4. The capacitive sensing device of claim 1, 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.

5. The capacitive sensing device of claim 1, wherein said first sensing element, said second sensing element, and said third sensing element each comprises a conductive trace.

6. The capacitive sensing device of claim 1, 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.

7. The capacitive sensing device of claim 1, wherein:

said varying depth of said first sensing element comprises a sinusoidal waveform;

said varying depth of said second element comprises a sinusoidal waveform offset from said sinusoidal waveform of said varying depth of said first sensing element; and

said varying depth of said third sensing element comprises a sinusoidal waveform offset from said sinusoidal waveform of said varying depth of said first sensing element and said sinusoidal waveform of said varying depth of said second sensing element.

8. The capacitive sensing device of claim 1, further comprising:

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

9. The capacitive sensing device of claim 1, 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.

10. The capacitive sensing device of claim 1, wherein said first, second, and third sensing elements are utilized as part of a capacitive touch pad device.

11. The capacitive sensing device of claim 4, wherein said position is determined using a trigonometric function.

12. The capacitive sensing device of claim 5, 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.

13. The capacitive sensing device of claim 9, 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.

14. A portable electronic device comprising:

a capacitive sensor;

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 having an offset substantially 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 having an offset substantially 4π

/3 radians from said sine (θ

) waveform of said first sensing element, 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.

15. The portable electronic 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 not parallel to said first axis.

16. The portable electronic device of claim 14, 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.

17. The portable electronic device of claim 14, wherein said first location along said first axis is determined using a trigonometric function.

18. The portable electronic device of claim 14, further comprising:

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

19. 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, a second sensing element and a third sensing element, wherein said first sensing element, said second sensing element, and said third sensing element are conductive and lie substantially along a first orientation such that said first sensing element comprises a waveform that is substantially sin (θ

), said second sensing element comprises a waveform that is substantially sin(θ

+120 degrees), and said third sensing element comprises a waveform that is substantially sin(θ

+240 degrees), and each of said first sensing element, said second sensing element, and said third sensing element is configured to provide information corresponding to a first location along said first orientation.

20. The method as recited in claim 19, wherein said first orientation is substantially linear.

21. The method as recited in claim 19, wherein said first orientation is non-linear.

22. The method as recited in claim 19, further comprising:

backfilling said first sensing element with a material.

23. The method as recited in claim 19, wherein said first sensing element and said second sensing element each forms at least a portion of a loop.