Iterative method for determining touch location

• US 20060152499A1
• Filed: 01/10/2005
• Published: 07/13/2006
• Est. Priority Date: 01/10/2005
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Roberts, Jerry B.
• Granted Patent: US 7,499,039 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0436 in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate

Abstract

A touch sensitive device uses an iterative method for determining the location of a touch on a touch sensitive surface. The touch sensitive device includes a touch plate and a plurality of sensors configured to sense vibrations propagating in the touch plate. Signals responsive to the vibrations caused by the touch are generated. The touch location is approximated and the signals are adjusted using the approximate touch location. The touch location is determined using the adjusted signals.

Claims

1. A method for detecting a touch location on a touch sensitive device having a touch plate and a plurality of vibration sensors configured to sense vibrations propagating in the touch plate, the method comprising:

generating signals responsive to the vibrations, the vibrations caused by a touch to the touch plate; and

determining the touch location, comprising;

approximating the touch location;

adjusting the signals using the approximate touch location; and

determining the touch location using the adjusted signals.

2. The method of claim 1, wherein determining the touch location comprises iteratively determining the touch location.

3. The method of claim 2, wherein iteratively determining the touch location comprises iteratively determining the touch location to a predetermined touch location accuracy.

4. The method of claim 2, wherein iteratively determining the touch location comprises iteratively adjusting the signals towards an exact reconstruction.

5. The method of claim 1, wherein approximating the touch location comprises:

defining a plurality of possible touch locations;

adjusting the signals using each of the possible touch locations; and

approximating the touch location as one of the possible touch locations using the adjusted signals.

6. The method of claim 5, wherein defining the plurality of possible touch locations comprises defining an array of possible touch locations, the array sized to cover an active area of the touch screen.

7. The method of claim 5, wherein approximating the touch location comprises approximating the touch location as a possible touch location associated with a more accurate adjusted signal.

8. The method of claim 1, further comprising:

defining a plurality of possible touch locations based on the approximate touch location; and

adjusting the signals using each of the possible touch locations, wherein determining the touch location comprises determining the touch location based on the signals adjusted using each of the possible touch locations.

9. The method of claim 8, wherein defining the plurality of possible touch locations comprises defining an array of possible touch locations, the array defined relative to the approximate touch location.

10. The method of claim 8, wherein determining the touch location based on the signals adjusted using each of the possible touch locations comprises determining the touch location based on a measure of probable accuracies of the signals adjusted using each of the possible touch locations.

11. The method of claim 1, wherein approximating the touch location comprises approximating the touch location based on arrival times of the vibrations at each of the vibration sensors.

12. The method of claim 1, wherein:

adjusting the signals comprises adjusting a phase of the signals at a selected frequency; and

determining the touch location comprises determining the touch location using the phase-adjusted signals.

13. The method of claim 12, wherein the selected frequency is phase-adjusted with respect to a center frequency of a frequency passband.

14. The method of claim 12, wherein the selected frequency is phase-adjusted with respect to a frequency associated with a peak signal energy.

15. A touch sensing device, comprising:

a touch plate;

a plurality of touch sensors coupled to the touch plate, the touch sensors configured to generate signals responsive to vibrations caused by a touch on the touch plate; and

a touch location processor coupled to the plurality of sensors and configured to approximate the touch location, adjust the signals using the approximate touch location, and determine the touch location using the adjusted signals.

16. The device of claim 15, wherein:

the touch plate comprises a frequency dispersive medium; and

the touch location processor is configured to correct the signals for frequency dispersion.

17. The device of claim 15, wherein the plurality of touch sensors comprises a plurality of piezoelectric sensors.

18. The device of claim 15, wherein the touch location processor is configured to iteratively define possible touch locations and adjust the signals based on the possible touch locations to determine the touch location.

19. The device of claim 15, wherein the touch location processor is configured to define a plurality of possible touch locations, adjust the signals using each of the possible touch locations, and determine the touch location as one of the possible touch locations using the adjusted signals.

20. The device of claim 19, wherein the touch location processor is configured to define one or more arrays of possible touch locations.

21. The device of claim 20, wherein an initial array is sized to cover an active area of the touch screen.

22. The device of claim 19, wherein the processor is configured to determine the touch location based on a measure of probable accuracies of the adjusted signals.

23. The device of claim 15, wherein the processor is configured to adjust a phase of the signals at a selected frequency and determine the touch location using the phase-adjusted signals.

24. The device of claim 15, further comprising a display coupled to the touch sensitive device.

25. The device of claim 15, further comprising:

a display coupled to the touch sensitive device; and

a host processor coupled to the display and the touch sensitive device.

26. An apparatus for detecting a touch location on a touch sensitive device having a touch plate and a plurality of vibration sensors configured to sense vibrations propagating in the touch plate, the method comprising:

means for generating signals responsive to the vibrations, the vibrations caused by a touch to the touch plate; and

means for determining the touch location, comprising;

means for approximating the touch location;

means for adjusting the signals using the approximate touch location; and

means for determining the touch location using the adjusted signals.

27. The apparatus of claim 26, further comprising means for iteratively determining the touch location.

28. The apparatus of claim 26, further comprising:

means for defining a plurality of possible touch locations;

means for adjusting the signals using each of the possible touch locations; and

means for approximating the touch location as one of the possible touch locations using the adjusted signals.

29. The apparatus of claim 26, further comprising:

means for defining a plurality of possible touch locations based on the approximate touch location;

means for adjusting the signals using each of the possible touch locations; and

means for determining the touch location based on the signals adjusted using each of the possible touch locations.

30. The apparatus of claim 29, further comprising means for defining an array of possible touch locations, the array defined relative to the approximate touch location.

31. The apparatus of claim 29, further comprising means for determining the touch location based on a measure of probable accuracies of the signals adjusted using each of the possible touch locations.

32. The apparatus of claim 26, further comprising:

means for adjusting a phase of the signals at a selected frequency; and

means for determining the touch location using the phase-adjusted signals.