SENSING METHDO AND CALIBRATION METHOD FOR A CAPACITIVE TOUCH PANEL

• US 20110115743A1
• Filed: 11/15/2010
• Published: 05/19/2011
• Est. Priority Date: 11/19/2009
• Status: Active Grant

• Current Assignee: Elan Microelectronics Corporation
• Original Assignee: Elan Microelectronics Corporation
• Inventors: HUANG, CHUN-CHUNG, WANG, TSUN-MIN
• Granted Patent: US 9,104,277 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

Stimulus regions are defined based on the traces of a capacitive touch panel. A first signal is applied to a first trace in a first direction under a second signal applied to a second trace in a second direction to stimulate the second trace, to sense a stimulus region for an ADC value thereof. Calibration parameters for the traces are determined according to the ADC values of the traces without being touched, and are stored for later sensing the traces for position calculation and multi-finger calculation.

Claims

35. A sensing method for a capacitive touch panel having a plurality of first traces in a first direction and a plurality of second traces in a second direction, the sensing method comprising the steps of:

defining a plurality of stimulus regions based on the first traces and the second traces;

providing a first signal for sensing the first traces and a second signal for stimulating the second traces;

obtaining and storing calibration parameters for the first traces;

deriving ADC values of the stimulus regions using the calibration parameters; and

storing the ADC values of the stimulus regions for multi-finger calculation to locate real points.

36. The sensing method of claim 35, wherein each of the first signal and the second signal is a voltage signal.

37. The sensing method of claim 35, wherein each of the first signal and the second signal is a current signal.

38. The sensing method of claim 35, wherein the first signal is a voltage signal and the second signal is a current signal.

39. The sensing method of claim 35, wherein the first signal is a current signal and the second signal is a voltage signal.

40. The sensing method of claim 35, wherein the second signal is in phase with the first signal.

41. The sensing method of claim 35, wherein the second signal is out of phase with the first signal.

42. The sensing method of claim 35, wherein the second signal is a common voltage.

43. The sensing method of claim 35, wherein the step of providing a first signal for sensing the first traces and a second signal for stimulating the second traces comprises the step of using a one-to-one, one-to-many, many-to-one or many-to-many combination for sensing and stimulating the first traces and the second traces respectively.

44. The sensing method of claim 35, wherein the step of providing a first signal for sensing the first traces and a second signal for stimulating the second traces comprises the step of providing a third signal for stimulating at least one of the first traces adjacent to a sensed first trace.

45. The sensing method of claim 35, wherein the step of providing a first signal for sensing the first traces and a second signal for stimulating the second traces comprises the step of providing a third signal for stimulating the rest of the first traces other than the sensed first trace.

46. The sensing method of claim 44, wherein the third signal is a voltage signal or a current signal.

47. The sensing method of claim 45, wherein the third signal is a voltage signal or a current signal.

48. The sensing method of claim 44, wherein the third signal is in phase with the first signal.

49. The sensing method of claim 45, wherein the third signal is in phase with the first signal.

50. The sensing method of claim 44, wherein the third signal is out of phase with the first signal.

51. The sensing method of claim 45, wherein the third signal is out of phase with the first signal.

52. The sensing method of claim 44, wherein the third signal is a common voltage.

53. The sensing method of claim 45, wherein the third signal is a common voltage.

54. The sensing method of claim 35, wherein the step of obtaining and storing calibration parameters for the first traces comprises the steps of:

sensing one of the stimulus regions on each of the first traces without being touched for object-absent ADC values thereof;

deriving the calibration parameters according to the object-absent ADC values such that the ADC values will fall within a level range when the stimulus regions are not touched.

55. A sensing method for a capacitive touch panel having a plurality of first traces in a first direction and a plurality of second traces in a second direction, the sensing method comprising the steps of:

defining a plurality of stimulus regions based on the first traces and the second traces;

providing a first signal for sensing the first traces and a second signal for stimulating the second traces;

obtaining and storing calibration parameters for the first traces;

identifying an object touching any of the first traces;

deriving ADC values of all stimulus regions on the traces touched by the object using the calibration parameters; and

locating a real point for the object according to the ADC values.

1. A sensing method for a capacitive touch panel having a plurality of first traces in a first direction and a plurality of second traces in a second direction, the sensing method comprising the steps of:

defining a plurality of stimulus regions based on the first traces and the second traces;

providing a first signal for sensing the first traces and a second signal for stimulating the second traces;

providing the first signal for sensing the second trace and the second signal for stimulating the first traces;

obtaining and storing first calibration parameters for the first traces and second calibration parameters for the second traces;

deriving first ADC values of the stimulus regions using the first calibration parameters;

deriving second ADC values of the stimulus regions using the second calibration parameters; and

storing the first ADC values and the second ADC values of the stimulus regions for position calculation or multi-finger calculation to locate a real point.

3. The sensing method of claim 1, wherein each of the first signal and the second signal is a current signal.

4. The sensing method of claim 1, wherein the first signal is a voltage signal and the second signal is a current signal.

5. The sensing method of claim 1, wherein the first signal is a current signal and the second signal is a voltage signal.

6. The sensing method of claim 1, wherein the second signal is in phase with the first signal.

7. The sensing method of claim 1, wherein the second signal is out of phase with the first signal.

8. The sensing method of claim 1, wherein the second signal is a common voltage.

9. The sensing method of claim 1, wherein the step of providing a first signal for sensing the first traces and a second signal for stimulating the second traces comprises the step of using a one-to-one, one-to-many, many-to-one or many-to-many combination for sensing and stimulating the first traces and the second traces respectively.

10. The sensing method of claim 1, wherein the step of providing the first signal for sensing the second trace and the second signal for stimulating the first traces comprises the step of using a one-to-one, one-to-many, many-to-one or many-to-many combination for sensing and stimulating the first traces and the second traces respectively.

11. The sensing method of claim 1, wherein the step of providing a first signal for sensing the first traces and a second signal for stimulating the second traces comprises the step of providing a third signal for stimulating at least one of the first traces adjacent to a sensed first trace.

12. The sensing method of claim 1, wherein the step of providing a first signal for sensing the first traces and a second signal for stimulating the second traces comprises the step of providing a third signal for stimulating the rest of the first traces other than the sensed first trace.

13. The sensing method of claim 1, wherein the step of providing the first signal for sensing the second trace and the second signal for stimulating the first traces comprises the step of providing a third signal for stimulating at least one of the second traces adjacent to a sensed second trace.

14. The sensing method of claim 1, wherein the step of providing the first signal for sensing the second trace and the second signal for stimulating the first traces comprises the step of providing a third signal for stimulating the rest of the second traces other than the sensed second traces.

15. The sensing method of claim 11, wherein the third signal is a voltage signal or a current signal.

16. The sensing method of claim 12, wherein the third signal is a voltage signal or a current signal.

17. The sensing method of claim 13, wherein the third signal is a voltage signal or a current signal.

18. The sensing method of claim 14, wherein the third signal is a voltage signal or a current signal.

19. The sensing method of claim 11, wherein the third signal is in phase with the first signal.

20. The sensing method of claim 12, wherein the third signal is in phase with the first signal.

21. The sensing method of claim 13, wherein the third signal is in phase with the first signal.

22. The sensing method of claim 14, wherein the third signal is in phase with the first signal.

23. The sensing method of claim 11, wherein the third signal is out of phase with the first signal.

24. The sensing method of claim 12, wherein the third signal is out of phase with the first signal.

25. The sensing method of claim 13, wherein the third signal is out of phase with the first signal.

26. The sensing method of claim 14, wherein the third signal is out of phase with the first signal.

27. The sensing method of claim 11, wherein the third signal is a common voltage.

28. The sensing method of claim 12, wherein the third signal is a common voltage.

29. The sensing method of claim 13, wherein the third signal is a common voltage.

30. The sensing method of claim 14, wherein the third signal is a common voltage.

31. The sensing method of claim 1, wherein the step of obtaining and storing first calibration parameters for the first traces and second calibration parameters for the second traces comprises the steps of:

sensing one of the stimulus regions on each of the first traces without being touched for first object-absent ADC values thereof;

deriving the first calibration parameters according to the first object-absent ADC values such that the first ADC values will fall within a first level range when the stimulus regions are not touched;

sensing one of the stimulus regions on each of the second traces without being touched for second object-absent ADC values thereof; and

deriving the second calibration parameters according to the second object-absent ADC values such that the second ADC values will fall within a second level range when the stimulus regions are not touched.

32. The sensing method of claim 31, wherein the position calculation comprises the step of:

calculating with the first ADC values of the stimulus regions to extract a first difference between the first ADC values and the first level range;

calculating with the second ADC values of the stimulus regions to extract a second difference between the second ADC values and the second level range;

locating a real point according to the first difference and the second difference.

33. The sensing method of claim 32, wherein the step of calculating with the first ADC values of the stimulus regions to extract a first difference between the first ADC values and the first level range comprises the step of accumulating, averaging or weighted averaging the first ADC values of the stimulus regions to generate the first difference.

34. The sensing method of claim 32, wherein the step of calculating with the second ADC values of the stimulus regions to extract a second difference between the second ADC values and the second level range comprises the step of accumulating, averaging or weighted averaging the second ADC values of the stimulus regions to generate the second difference.

56. The sensing method of claim 55, wherein each of the first signal and the second signal is a voltage signal.

57. The sensing method of claim 55, wherein each of the first signal and the second signal is a current signal.

58. The sensing method of claim 55, wherein the first signal is a voltage signal and the second signal is a current signal.

59. The sensing method of claim 55, wherein the first signal is a current signal and the second signal is a voltage signal.

60. The sensing method of claim 55, wherein the second signal is in phase with the first signal.

61. The sensing method of claim 55, wherein the second signal is out of phase with the first signal.

62. The sensing method of claim 55, wherein the second signal is a common voltage.

63. The sensing method of claim 55, wherein the step of identifying an object touching any of the first traces comprises the steps of:

sequentially scanning the first traces for sensing one of the stimulus regions on each sensed first trace for extracting ADC values thereof based on the calibration parameters; and

comparing the ADC values with a threshold value for identifying the trace having an ADC value greater than the threshold value as being touched by the object.

64. The sensing method of claim 55, wherein the step of identifying an object touching any of the first traces comprises the steps of:

sequentially scanning the first traces for sensing one of the stimulus regions on each sensed first trace until a first trace having an ADC value calibrated with the calibration parameters is detected greater than a threshold; and

directly sensing all the stimulus regions on each of the next several first traces to the one having the calibrated ADC value greater than the threshold for extracting ADC values thereof based on the calibration parameters.

65. The sensing method of claim 55, wherein the step of identifying an object touching any of the first traces comprises the steps of:

sequentially scanning a portion of the first traces in a jumping manner for sensing one of the stimulus regions on each sensed first trace until a first trace having an ADC value calibrated with the calibration parameters is detected greater than a threshold; and

directly sensing all the stimulus regions on each of the next several first traces in the jumping manner to the one having the calibrated ADC value greater than the threshold for extracting ADC values thereof based on the calibration parameters.

66. The sensing method of claim 55, wherein the step of providing a first signal for sensing the first traces and a second signal for stimulating the second traces comprises the step of using a one-to-one, one-to-many, many-to-one or many-to-many combination for sensing and stimulating the first traces and the second traces respectively.

67. The sensing method of claim 55, wherein the step of providing a first signal for sensing the first traces and a second signal for stimulating the second traces comprises the step of providing a third signal for stimulating at least one of the first traces adjacent to a sensed first trace.

68. The sensing method of claim 66, wherein the third signal is a voltage signal or a current signal.

70. The sensing method of claim 66, wherein the third signal is in phase with the first signal.

71. The sensing method of claim 67, wherein the third signal is in phase with the first signal.

72. The sensing method of claim 66, wherein the third signal is out of phase with the first signal.

73. The sensing method of claim 67, wherein the third signal is out of phase with the first signal.

74. The sensing method of claim 66, wherein the third signal is a common voltage.

75. The sensing method of claim 67, wherein the third signal is a common voltage.

76. The sensing method of claim 55, wherein the step of providing a first signal for sensing the first traces and a second signal for stimulating the second traces comprises the step of providing a third signal for stimulating the rest of the first traces other than the sensed first trace.

77. The sensing method of claim 55, wherein the step of obtaining and storing calibration parameters for the first traces comprises the steps of:

sensing one of the stimulus regions on each of the first traces without being touched for object-absent ADC values thereof;

deriving the calibration parameters according to the object-absent ADC values such that the ADC values will fall within a level range when the stimulus regions are not touched.

68-1. The sensing method of claim 67, wherein the third signal is a voltage signal or a current signal.

78. A calibration method for a capacitive touch panel having a plurality of first traces in a first direction and a plurality of second traces in a second direction, the calibration method comprising the steps of:

providing a first signal for sensing the first traces and a second signal for stimulating the second traces;

sensing one of a plurality of stimulus regions defined on the first traces without being touched for an ADC value;

determining calibration parameters for the first traces from the ADC value such that the calibrated ADC value will fall within a level range when the stimulus regions are not touched; and

storing the calibration parameters for later sensing for ADC values of the first traces.

2. The sensing method of claim 1, wherein each of the first signal and the second signal is a voltage signal.

79. The calibration method of claim 78, wherein each of the first signal and the second signal is a voltage signal.

80. The calibration method of claim 78, wherein each of the first signal and the second signal is a current signal.

81. The calibration method of claim 78, wherein the first signal is a voltage signal and the second signal is a current signal.

82. The calibration method of claim 78, wherein the first signal is a current signal and the second signal is a voltage signal.

83. The calibration method of claim 78, wherein the second signal is in phase with the first signal.

84. The calibration method of claim 78, wherein the second signal is out of phase with the first signal.

85. The calibration method of claim 78, wherein the second signal is a common voltage.

86. The calibration method of claim 78, wherein the step of providing a first signal for sensing the first traces and a second signal for stimulating the second traces comprises the step of using a one-to-one, one-to-many, many-to-one or many-to-many combination for sensing and stimulating the first traces and the second traces respectively.

87. The calibration method of claim 78, wherein the step of providing a first signal for sensing the first traces and a second signal for stimulating the second traces comprises the step of providing a third signal for stimulating at least one of the first traces adjacent to a sensed first trace.

88. The calibration method of claim 78, wherein the step of providing a first signal for sensing the first traces and a second signal for stimulating the second traces comprises the step of providing a third signal for stimulating the rest of the first traces other than the sensed first trace.

89. The calibration method of claim 87, wherein the third signal is a voltage signal or a current signal.

90. The calibration method of claim 88, wherein the third signal is a voltage signal or a current signal.

91. The calibration method of claim 87, wherein the third signal is in phase with the first signal.

92. The calibration method of claim 88, wherein the third signal is in phase with the first signal.

93. The calibration method of claim 87, wherein the third signal is out of phase with the first signal.

94. The calibration method of claim 88, wherein the third signal is out of phase with the first signal.

95. The calibration method of claim 87, wherein the third signal is a common voltage.

95-2. The calibration method of claim 88, wherein the third signal is a common voltage.