Touch location determination with error correction for sensor movement

• US 20060227114A1
• Filed: 03/30/2005
• Published: 10/12/2006
• Est. Priority Date: 03/30/2005
• Status: Abandoned Application

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Geaghan, Bernard O., Lessard, Bruce A.
• Application Number:
  US11/093,895
• Publication Number:
  US 20060227114A1
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 1/1647 including at least an additional display G06F1/1692 takes precedence
• CPC Class Codes: G06F 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 2203/04107 Shielding in digitiser, i.e. guard or shielding arrangements, mostly for capacitive touchscreens, e.g. driven shields, driven grounds
• CPC Class Codes: G06F 3/04142 the force sensing means being located peripherally, e.g. disposed at the corners or at the side of a touch sensing plate
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0444 using a single conductive element covering the whole sensing surface, e.g. by sensing the electrical current flowing at the corners

Abstract

Touch location determination is enhanced by correcting for errors that arise due to touch panel movement. A touch sensitive device includes a capacitive touch sensor configured to generate signals indicative of a location of a capacitively coupled touch on a touch surface. An error correction sensor generates a signal associated with movement of the capacitive touch sensor. Touch location is determined using the touch location signals and the error signal.

Claims

1. A touch sensitive device, comprising:

a capacitive touch sensor configured to generate signals indicative of a location of a capacitively coupled touch on a touch surface;

an error correction sensor configured to generate a signal associated with an error in the touch location signals, the error associated with movement of the capacitive touch sensor; and

a processor configured to determine the touch location based on the touch location signals and the error signal.

2. The device of claim 1, wherein the error correction sensor comprises a capacitive sensor.

3. The device of claim 1, wherein the error correction sensor comprises a force sensor.

4. The device of claim 1, wherein the error correction sensor comprises a bending wave sensor.

5. The device of claim 1, where the error correction sensor is further configured to sense a force of the touch on the touch surface.

6. The device of claim 1, further comprising a display visible through the touch surface.

7. The device of claim 1, wherein:

the capacitive touch sensor comprises an electrode layer disposed on one side of a substrate; and

the error correction sensor comprises one or more electrodes disposed on an opposite side of the substrate.

8. The device of claim 7, wherein the one or more electrodes comprise a continuous electrode disposed on a peripheral portion of the substrate.

9. The device of claim 7, wherein the one or more electrodes comprise a plurality of discrete electrodes disposed on a peripheral portion of the substrate.

10. The device of claim 7, wherein the electrode layer is driven with an AC signal.

11. The device of claim 7, wherein the one or more electrodes are driven with an AC signal.

12. The device of claim 7, wherein the one or more electrodes are configured to shield portions of the electrode layer from EMI.

13. The device of claim 7, wherein the one or more electrodes are configured to reduce capacitive coupling between the electrode layer and conductive structures of the touch sensitive device.

14. A method for determining a location of a touch on a touch surface;

comprising;

generating touch signals from a capacitively coupled touch on the touch surface;

generating an error signal associated with an error in the touch signals, the error associated with movement of the touch surface; and

determining the touch location based on the touch signals and the error signal.

15. The method of claim 14, wherein generating the error signal comprises measuring a change in capacitance responsive to movement of a touch sensor used to generate the touch signals.

16. The method of claim 14, wherein determining the touch location comprises adjusting the touch signals based on the error signal.

17. The method of claim 14, further comprising measuring a touch force using the error signal.

18. The method of claim 14, further comprising calibrating the touch surface using the error signal.

19. A touch sensitive device, comprising:

means for generating touch signals associated with a change in capacitance responsive to the touch on the touch surface;

means for generating an error signal associated with an error in the touch signals; and

means for determining the touch location based on the touch signals and the error signal.

20. The touch sensitive device of claim 19, further comprising means for measuring a touch force using the error signal.