Method for improving positioned accuracy for a determined touch input

• US 7,746,325 B2
• Filed: 05/06/2002
• Issued: 06/29/2010
• Est. Priority Date: 05/06/2002
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Roberts, Jerry B.
• Primary Examiner(s): Kumar; Srilakshmi K
• Application Number:
  US10/140,209
• Publication Number:
  US 20030206162A1
• Time in Patent Office: 2,976 Days
• Field of Search: 345173-179, 178 181- 185, 178 191- 195, 340/712
• US Class Current: 345/173
• 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

Abstract

An approach for accurately determining touch location on a touch screen is provided. According to one aspect, a touch signal shape may be correlated with a level of touch-induced touch signal error present in the touch signal. The touch signal shape is associated with a preferred time for obtaining touch signal information to determine the touch location. Touch signal location information is acquired in response to detecting the touch signal shape in the touch signal. The location of the touch is determined from the acquired touch signal information.

Claims

1. A method for determining a touch location on a touch screen, comprising;

acquiring a touch signal corresponding to a touch on the touch screen;

detecting the first occurrence of a predetermined shape in the touch signal, the predetermined shape being associated with low signal error and based on a slope or a rate of change of the touch signal;

determining touch location using touch signal information obtained in response to detecting the predetermined shape.

2. The method of claim 1, wherein acquiring the touch signal further comprises acquiring a signal indicative of a touch force.

3. The method of claim 1, wherein detecting the first occurrence of the predetermined shape comprises detecting a preferred time for obtaining touch signal information to determine touch location.

4. The method of claim 3, wherein detecting the preferred time comprises detecting a time when touch signal errors in the touch signal are minimal.

5. The method of claim 3, wherein detecting the preferred time comprises detecting a time when damping effect errors in the touch signal are minimal.

6. The method of claim 3, wherein detecting the preferred time comprises detecting a time when inertial effect errors in the touch signal are minimal.

7. The method of claim 1, wherein detecting the first occurrence of the predetermined shape comprises detecting a predetermined relative slope of the touch signal.

8. The method of claim 7, wherein detecting the predetermined relative slope comprises dividing a slope of the touch signal at a particular time by a magnitude of the touch signal at the particular time.

9. The method of claim 7, wherein detecting the first occurrence of the predetermined shape comprises detecting the first occurrence of the relative slope falling below a predetermined value.

10. The method of claim 7, wherein detecting the first occurrence of the predetermined shape comprises detecting the first occurrence that the relative slope changes sign.

11. The method of claim 7, wherein detecting the first occurrence of the predetermined shape comprises detecting the first occurrence of a touch signal point halfway through an interval of the touch signal for which the relative slope is less than a predetermined value.

12. The method of claim 8, wherein detecting the first occurrence of the predetermined shape comprises detecting the first occurrence of a touch signal point following a predetermined delay interval after the relative slope falls below a predetermined value.

13. The method of claim 1, wherein using a fixed threshold to determine that the touch signal represents a valid touch input further comprises determining that the touch signal exceeds a predetermined magnitude before detecting the first occurrence of a predetermined shape in the touch signal.

14. The method of claim 1, wherein using a fixed threshold to determine that the touch signal represents a valid touch input further comprises examining the touch signal to detect a rise of the touch signal above a predetermined magnitude after detecting the first occurrence of the predetermined shape in the touch signal.

15. The method of claim 3, further comprising obtaining touch location information if the preferred time is not detected after a predetermined interval and if the touch is deliberately slow.

16. The method of claim 3, further comprising masking a touch signal output until a current touch condition is removed if the preferred time is not detected after a predetermined interval and if the touch is not deliberately slow.

17. The method of claim 16, wherein the current touch condition is removed when the touch signal magnitude falls below a predetermined magnitude.

18. The method of claim 3, further comprising determining a series of touch locations after the preferred time is detected if the touch is a continuing touch.

19. The method of claim 18, wherein the further step of determining a series of touch locations after the preferred time is detected if the touch is a continuing touch comprises masking a touch location output when the relative slope falls below a predetermined range around zero.

20. The method of claim 18, further comprising reporting as a touch location output a first touch location in the series of touch locations until a predetermined time interval has elapsed.

21. The method of claim 18, further comprising reporting as a touch location output a first touch location in the series of touch locations until the touch location is calculated to be a predetermined distance from the first touch location.

28. The method of claim 21, wherein detecting the first occurrence of the touch signal shape comprises detecting a preferred time for obtaining touch signal information to determine touch location.

22. A method for determining a touch location on a touch screen, comprising:

associating a predetermined touch signal shape with a low touch signal error and based on a slope or a rate of change of the touch signal;

acquiring a touch signal corresponding to a touch on the touch screen;

detecting the first occurrence of the predetermined touch signal shape in the touch signal; and

determining touch location using touch signal information obtained in response to detecting the predetermined touch signal shape.

23. The method of claim 22, wherein acquiring the touch signal corresponding to the touch on the touch screen further comprises acquiring a signal indicative of a touch force.

24. The method of claim 22, wherein detecting the first occurrence of a touch signal shape comprises detecting a predetermined relative slope of the touch signal.

25. The method of claim 22, wherein associating the touch signal shape with the level of touch signal error comprises associating the touch signal shape with a reduced level of touch signal error in comparison to a maximum touch signal error.

26. The method of claim 22, wherein associating the touch signal shape with the level of touch signal error comprises detecting a time when damping effect errors in the touch signal are minimal.

27. The method of claim 22, wherein associating the touch signal shape with the level of touch signal error comprises detecting a time when inertial effect errors in the touch signal are minimal.

29. A method for determining a touch location on a touch screen, comprising;

associating a touch signal shape with a local minimum in touch-induced error;

acquiring a touch signal arising from a touch on the touch screen;

determining a particular time at which the touch signal shape is present in the touch signal by analyzing a slope or rate of change in the touch signal; and

determining touch location using touch signal information obtained at the particular time.

30. The method of claim 29, wherein the acquiring a touch signal arising from a touch comprises acquiring a signal indicative of a touch force.

31. The method of claim 29, wherein determining the particular time at which the touch signal shape is present in the touch signal comprises determining a preferred time for obtaining touch signal information to determine touch location.

32. The method of claim 29, wherein associating the touch signal shape with the local minimum in touch-induced error present in the touch signal comprises associating the touch signal shape to a time during the touch signal that damping effect errors are minimal.

33. The method of claim 29, wherein associating the touch signal shape with the local minimum in touch-induced error present in the touch signal comprises associating the touch signal shape to a time during the touch signal that inertial effect errors are minimal.

34. The method of claim 29, wherein associating the touch signal shape with the local minimum in touch-induced error present in the touch signal further comprises associating a predetermined relative slope of the touch signal with the local minimum in touch-induced error present in the touch signal.

41. The method of claim 34, wherein detecting the preferred time comprises detecting a time when inertial effect errors in the touch signal are minimal.

35. A method for determining a touch location on a touch screen, comprising:

acquiring a touch signal indicative of a force due to a touch on the touch screen;

detecting a touch signal shape within an interval of the touch signal associated with maximum touch force, the touch signal shape being associated with low signal error and determined using slope or a rate of change of the touch signal; and

determining touch location using touch signal information obtained in response to detecting the touch signal shape.

36. The method of claim 35, wherein detecting the touch signal shape within the interval of the touch signal associated with maximum touch force comprises detecting the touch signal shape within an interval beginning with the application of a touch and ending when a slope of the touch signal falls below a predetermined value.

37. The method of claim 35, wherein detecting the touch signal shape within the interval of the touch signal associated with maximum touch force comprises detecting the touch signal shape within an interval beginning with the application of a touch and ending when a magnitude of the touch signal falls below a predetermined value.

38. The method of claim 35, wherein detecting a touch signal shape within the interval of the touch signal associated with maximum touch force comprises detecting a preferred time for obtaining touch signal information to determine touch location.

39. The method of claim 38, wherein detecting the preferred time comprises detecting a time when touch signal errors in the touch signal are minimal.

40. The method of claim 38, wherein detecting the preferred time comprises detecting a time when damping effect errors in the touch signal are minimal.

42. The method of claim 35, wherein detecting the touch signal shape within the interval of the touch signal associated with maximum touch force comprises detecting a predetermined relative slope of the touch signal.

43. A method for determining touch location on a touch screen comprising;

acquiring a touch signal representative of a touch on the touch screen, the touch signal having an error related to the rate of change of the touch signal;

detecting a particular time for obtaining touch signal information for determining touch location based on a slope or the rate of change of the touch signal that relates to a low signal error; and

determining the touch location using touch signal information obtained at the particular time.

44. A touch screen system, comprising;

a touch surface;

a plurality of touch sensors, each of the touch sensors physically coupled to the touch surface and producing a sensor signal in response to a touch applied to the touch surface; and

a control system, coupled to the touch sensors and receiving the sensor signals, the control system acquiring a touch signal corresponding to a touch on the touch screen, detecting a first occurrence of a touch signal shape in the touch signal, the touch signal shape being associated with low signal error and based on a slope or a rate of change of the touch signal; and

determining touch location using touch signal information obtained in response to detecting the touch signal shape.

45. The system of claim 44, wherein the touch sensors comprise force sensors.

46. The system of claim 44, wherein the touch sensors comprise capacitive force sensors.

47. The system of claim 44, wherein the touch surface is substantially rectangular with one of the plurality of touch sensors located at each corner of the touch screen.

48. The system of claim 47, wherein each touch sensor produces a sensor signal indicative of a force of a touch sensed at a location of the touch sensor.

49. The system of claim 44, wherein the control system derives one or more touch signals by combining one or more sensor signals.

50. The system of claim 44, wherein the control system comprises a filter for filtering touch signals produced by the touch sensors.

51. The system of claim 50, wherein the filter comprises a digital filter.

52. The system of claim 51, wherein the digital filter comprises a finite impulse response filter or an infinite impulse filter.

53. The system of claim 44, wherein the touch signal shape used to determine the touch location comprises a slope of the touch signal calculated by the processor.

54. The system of claim 44, wherein the processor calculates a relative slope of the touch signal as the slope of the touch signal at a particular time divided by a magnitude of the touch signal at the particular time.

55. A touch screen display system, comprising;

a force sensitive touch screen system including a touch surface and a plurality of touch sensors, each of the touch sensors physically coupled to the touch surface and producing a touch signal in response to a touch force applied from a touch to the touch surface;

a control system coupled to the touch sensors and receiving the sensor signals, the control system detecting a first occurrence of a touch signal shape in the touch signal by at least using a slope or a rate of change of the touch signal, the touch signal shape being associated with low signal error; and

determining touch location using touch signal information a display for displaying information through the touch screen system.

56. The system of claim 55, wherein the display is a liquid crystal display, a light emitting diode display, a plasma display, an organic electroluminescent display, or a cathode ray tube display.

57. The system of claim 55, wherein the touch sensors comprise force sensors.

58. The system of claim 55, wherein each touch sensor produces a sensor signal indicative of a force of a touch sensed at a location of the touch sensor.

59. The system of claim 55, wherein the control system derives one or more touch signals by combining one or more sensor signals.

60. A display system, comprising:

a force sensitive touch screen system including a touch surface and a plurality of touch sensors, each of the touch sensors physically coupled to the touch surface and producing a touch signal in response to a touch force applied from a touch to the touch surface;

a control system, coupled to the touch sensors and receiving the sensor signals, the control system detecting a first occurrence of a touch signal shape in the touch signal, the touch signal shape being associated with low signal error and determined with reference to a slope of rate of change of the touch signal; and

determining touch location using touch signal information obtained in response to detecting the touch signal shape;

a display for displaying information; and

a processor coupled to the display and the touch screen system for processing data to be displayed on the display and information received from the touch screen system.

61. The system of claim 60, wherein the display displays information through the touch screen.

62. The system of claim 60, wherein the display is a liquid crystal display, a light emitting diode display, a plasma display, an organic electroluminescent display, or a cathode ray tube display.

63. The system of claim 60, wherein the processor receives information regarding a touch made on the touch screen relative to information displayed on the display.

64. The system of claim 60, wherein the touch sensors comprise force sensors.

65. The system of claim 60, wherein each touch sensor produces a sensor signal indicative of a force of a touch sensed at a location of the touch sensor.

66. The system of claim 60, wherein the control system derives one or more touch signals by combining one or more sensor signals.

67. The system of claim 60, further comprising:

one or more data storage devices coupled to the processor for storing data;

one or more input devices for transferring information to the processor; and

one or more output devices for transferring information from the processor.

68. The system of claim 60, further comprising one or more interfaces for coupling the system to one or more networks.

69. A system for determining the location of a touch on a touch screen, comprising:

means for acquiring a touch signal indicative of a force due to a touch on the touch screen;

means for detecting a first occurrence of a predetermined shape in the touch signal, the predetermined shape being associated with low signal error and detected with reference to a slope or rate of change of the touch signal; and

means for determining touch location using touch signal information obtained in response to detecting the predetermined touch signal shape.

70. The method of claim 69, wherein means for acquiring the touch signal further comprises means for acquiring a signal indicative of a touch force.

71. The method of claim 69, wherein means for detecting the first occurrence of the touch signal shape comprises means for detecting a preferred time for obtaining touch signal information to determine touch location.

72. The method of claim 71, wherein means for detecting the preferred time comprises means for detecting a time when touch signal errors in the touch signal are minimal.

73. The method of claim 69, wherein means for detecting the first occurrence of the touch signal shape comprises means for detecting a predetermined relative slope of the touch signal.

74. A system for determining the location of a touch on a touch screen, comprising:

means for associating a predetermined touch signal shape with a low level of touch signal error and detected with reference to a slope or rate of change of the touch signal;

means for acquiring a touch signal corresponding to a touch on the touch screen;

means for detecting a first occurrence of the predetermined signal shape in the touch signal; and

means for determining touch location using touch signal information obtained in response to detecting the predetermined touch signal shape.

75. A system for determining a touch location on a touch screen, comprising:

means for acquiring a touch signal indicative of a force due to a touch on the touch screen;

means for detecting a touch signal shape within an interval of the touch signal associated with maximum touch force, the touch signal shape associated with low signal error and detected with reference to a slope or rate of change of the touch signal; and

means for determining touch location using touch signal information obtained in response to detecting the touch signal shape.

76. A non transient computer readable medium configured with executable instructions for causing one or more computers to perform a method of determining the location of a touch on a touch screen, the method comprising:

acquiring a touch signal indicative of a force due to a touch on the touch screen;

detecting a first occurrence of a predetermined shape in the touch signal, the predetermined shape associated with low signal error and calculated with reference to a slope or a rate of change of the touch signal; and

determining touch location using touch signal information obtained in response to detecting the touch signal shape.