Sensing method and calibration method for a capacitive touch panel

• US 9,104,277 B2
• Filed: 11/15/2010
• Issued: 08/11/2015
• Est. Priority Date: 11/19/2009
• Status: Expired due to Fees

• Current Assignee: Elan Microelectronics Corporation
• Original Assignee: Elan Microelectronics Corporation
• Inventors: Wang, Tsun-Min, Huang, Chun-Chung
• Primary Examiner(s): RABINDRANATH, ROY P
• Application Number:
  US12/946,230
• Publication Number:
  US 20110115743A1
• Time in Patent Office: 1,730 Days
• Field of Search: 345/173, 345/178
• US Class Current: 1/1
• 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

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, wherein each first trace corresponds to at least two of the stimulus regions;

sensing the first plurality of stimulus regions by providing a first signal for sensing the first traces and a second signal for stimulating the second traces, and by providing the first signal for sensing the second traces 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;

respectively deriving first ADC values and second ADC values of the stimulus regions according to a result of sensing the plurality of stimulus regions, the first calibration parameters and 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;

wherein the second signal is not simultaneously provided to all the first traces or all the second traces.

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

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 providing a third signal for stimulating at least one of the first traces adjacent to a sensed first trace.

10. The sensing method of claim 9, wherein the third signal is a voltage signal or a current signal.

11. The sensing method of claim 9, wherein the third signal is in phase with the first signal.

12. The sensing method of claim 9, wherein the third signal is out of phase with the first signal.

13. The sensing method of claim 9, wherein the third signal is a common voltage.

14. 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.

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

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

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

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

19. The sensing method of claim 1, wherein the step of providing the first signal for sensing the second traces 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.

20. The sensing method of claim 19, wherein the third signal is a voltage signal or a current signal.

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

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

23. The sensing method of claim 19, wherein the third signal is a common voltage.

24. 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.

25. The sensing method of claim 24, wherein the third signal is a voltage signal or a current signal.

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

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

28. The sensing method of claim 24, wherein the third signal is a common voltage.

29. 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.

30. The sensing method of claim 29, 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.

31. The sensing method of claim 30, 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.

32. The sensing method of claim 30, 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.

33. The sensing method of claim 1, wherein each of the first traces has one first calibration parameter and each of the second traces has one second calibration parameter.

34. The sensing method of claim 1, wherein the first signal and the second signal are AC signals.

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 providing a third signal for stimulating at least one of the first traces adjacent to a sensed first trace.

44. The sensing method of claim 43, wherein the third signal is a voltage signal or a current signal.

45. The sensing method of claim 43, wherein the third signal is in phase with the first signal.

46. The sensing method of claim 43, wherein the third signal is out of phase with the first signal.

47. The sensing method of claim 43, wherein the third signal is a common voltage.

48. 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.

49. The sensing method of claim 48, wherein the third signal is a voltage signal or a current signal.

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

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

52. The sensing method of claim 48, wherein the third signal is a common voltage.

53. 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.

54. The sensing method of claim 35, wherein each of the first traces has one calibration parameter.

55. The sensing method of claim 35, wherein the first signal and the second signal are AC signals.

56. 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:

obtaining respective ADC values of the first traces, each of which is performed by sensing one of a plurality of stimulus regions on one first trace, the sensing of one stimulus region comprising the steps of providing a first signal for sensing the first trace and stimulating a part of the second traces;

determining a calibration parameter for each first trace according to the respective ADC values of the first traces; and

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

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

58. The calibration method of claim 56, wherein each of the first signal and the second signal is a current signal.

59. The calibration method of claim 56, wherein the first signal is a voltage signal and the second signal is a current signal.

60. The calibration method of claim 56, wherein the first signal is a current signal and the second signal is a voltage signal.

61. The calibration method of claim 56, wherein the second signal is in phase with the first signal.

62. The calibration method of claim 56, wherein the second signal is out of phase with the first signal.

63. The calibration method of claim 56, wherein the second signal is a common voltage.

64. The calibration method of claim 56, 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.

65. The calibration method of claim 64, wherein the third signal is a voltage signal or a current signal.

66. The calibration method of claim 64, wherein the third signal is in phase with the first signal.

67. The calibration method of claim 64, wherein the third signal is out of phase with the first signal.

68. The calibration method of claim 64, wherein the third signal is a common voltage.

69. The calibration method of claim 56, 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.

70. The calibration method of claim 69, wherein the third signal is a voltage signal or a current signal.

71. The calibration method of claim 69, wherein the third signal is in phase with the first signal.

72. The calibration method of claim 69, wherein the third signal is out of phase with the first signal.

73. The calibration method of claim 69, wherein the third signal is a common voltage.

74. The sensing method of claim 56, wherein the first signal and the second signal are AC signals.