SENSING CIRCUIT OF A TOUCH PANEL AND OPERATION METHOD OF A SENSING CIRCUIT OF A TOUCH PANEL

• US 20130342496A1
• Filed: 08/16/2012
• Published: 12/26/2013
• Est. Priority Date: 06/21/2012
• Status: Abandoned Application

• Current Assignee: HannStar Display Corporation
• Original Assignee: Kun-Hua Tsai
• Inventors: Tsai, Kun-Hua
• Application Number:
  US13/586,883
• Publication Number:
  US 20130342496A1
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/044 by capacitive means

Abstract

A sensing circuit includes a capacitor array, a comparator, and a processing unit. The comparator compares a detection voltage of each sensing unit with a common voltage of the touch panel to generate a corresponding comparison result. The processing unit generates a corresponding adjustment signal according to the corresponding comparison result. The capacitor array executes a corresponding operation on a present exponent n to generate a corresponding compensation capacitor according to the corresponding adjustment signal, and the capacitor array generates a present compensation capacitor according to a previous compensation capacitor generated by the capacitor array and the corresponding compensation capacitor. Thus, the present invention not only can quickly make a compensation capacitor generated by the capacitor array converge toward capacitor variation generated by the sensing unit, but can also reduce a delay problem of compensating capacitor caused by environmental noise interference.

Claims

1. A sensing circuit of a touch panel, comprising:

a capacitor array for coupling to a plurality of sensing units of the touch panel;

a comparator coupled to each sensing unit of the touch panel and the capacitor array for comparing a detection voltage of the sensing unit with a common voltage of the touch panel to generate a corresponding comparison result; and

a processing unit for generating a corresponding adjustment signal to the capacitor array according to the corresponding comparison result;

wherein the capacitor array executes a corresponding operation on a present exponent n to generate a corresponding compensation capacitor according to the corresponding adjustment signal, and the capacitor array generates a present compensation capacitor according to a previous compensation capacitor generated by the capacitor array and the corresponding compensation capacitor, wherein n is an integer larger than or equal to 0.

2. The sensing circuit of claim 1, wherein the detection voltage is determined according to capacitor variation of the sensing unit and the present compensation capacitor.

3. The sensing circuit of claim 2, wherein the detection voltage is equal to the common voltage when the capacitor variation of the sensing unit is equal to the present compensation capacitor.

4. The sensing circuit of claim 2, wherein the detection voltage is smaller than the common voltage when the capacitor variation of the sensing unit is greater than the present compensation capacitor.

5. The sensing circuit of claim 2, wherein the detection voltage is greater than the common voltage when the capacitor variation of the sensing unit is smaller than the present compensation capacitor.

6. The sensing circuit of claim 2, wherein the capacitor array executing the corresponding operation on the present exponent n to generate the corresponding compensation capacitor according to the corresponding adjustment signal comprises:

the capacitor array starts to increase the present compensation capacitor from an initial value, wherein the initial value is equal to 0; and

the comparator generates a first comparison result, the processing unit generates a first adjustment signal to the capacitor array according to the first comparison result, and the capacitor array progressively increases the present exponent n to generate the compensation capacitor corresponding to 2ⁿ⁺¹ according to the first adjustment signal when the detection voltage is smaller than the common voltage of the touch panel.

7. The sensing circuit of claim 2, wherein the capacitor array generating the present compensation capacitor according to the previous compensation capacitor generated by the capacitor array and the corresponding compensation capacitor comprises:

the capacitor array adds the compensation capacitor corresponding to 2ⁿ⁺¹ to the previous compensation capacitor generated by the capacitor array to generate the present compensation capacitor.

8. The sensing circuit of claim 7, wherein the comparator does not generate the corresponding comparison result when the detection voltage is equal to the common voltage.

9. The sensing circuit of claim 7, wherein the capacitor array executing the corresponding operation on the present exponent n to generate the corresponding compensation capacitor according to the corresponding adjustment signal comprises:

the comparator generates a second comparison result, the processing unit generates a second adjustment signal to the capacitor array according to the second comparison result, and the capacitor array progressively decreases the present exponent n to generate the compensation capacitor corresponding to 2<sup>n−

1</sup> according to the second adjustment signal when the detection voltage is greater than the common voltage of the touch panel.

10. The sensing circuit of claim 9, wherein the capacitor array generating the present compensation capacitor according to the previous compensation capacitor generated by the capacitor array and the corresponding compensation capacitor comprises:

the capacitor array subtracts the compensation capacitor corresponding to 2<sup>n−

1</sup> from the previous compensation capacitor generated by the capacitor array to generate the present compensation capacitor.

11. The sensing circuit of claim 10, wherein the comparator does not generate the corresponding comparison result when the detection voltage is equal to the common voltage.

12. The sensing circuit of claim 10, wherein the capacitor array executing the corresponding operation on the present exponent n to generate the corresponding compensation capacitor according to the corresponding adjustment signal comprises:

the comparator generates the first comparison result, the processing unit generates the first adjustment signal to the capacitor array according to the first comparison result, and the capacitor array progressively decreases the present exponent n to generate the compensation capacitor corresponding to 2<sup>n−

1</sup> according to the first adjustment signal when the detection voltage is smaller than the common voltage of the touch panel.

13. The sensing circuit of claim 12, wherein the capacitor array generating the present compensation capacitor according to the previous compensation capacitor generated by the capacitor array and the corresponding compensation capacitor comprises:

the capacitor array adds the compensation capacitor corresponding to 2<sup>n−

1</sup> to the previous compensation capacitor generated by the capacitor array to generate the present compensation capacitor.

14. The sensing circuit of claim 13, wherein the comparator does not generate the corresponding comparison result when the detection voltage is equal to the common voltage.

15. The sensing circuit of claim 13, wherein the capacitor array executing the corresponding operation on the present exponent n to generate the corresponding compensation capacitor according to the corresponding adjustment signal comprises:

the comparator generates the second comparison result, the processing unit generates the second adjustment signal to the capacitor array according to the second comparison result, and the capacitor array progressively decreases the present exponent n to generate the compensation capacitor corresponding to 2<sup>n−

1</sup> according to the second adjustment signal when the detection voltage is greater than the common voltage of the touch panel.

16. The sensing circuit of claim 15, wherein the capacitor array generating the present compensation capacitor according to the previous compensation capacitor generated by the capacitor array and the corresponding compensation capacitor comprises:

the capacitor array subtracts the compensation capacitor corresponding to 2<sup>n−

1</sup> from the previous compensation capacitor generated by the capacitor array to generate the present compensation capacitor.

17. The sensing circuit of claim 16, wherein the comparator does not generate the corresponding comparison result when the detection voltage is equal to the common voltage.

18. An operation method of a sensing circuit of a touch panel, the sensing circuit comprising a capacitor array, a comparator, and a processing unit, the method comprising:

the comparator comparing a detection voltage of each sensing unit of the touch panel with a common voltage of the touch panel to generate a corresponding comparison result;

the processing unit generating a corresponding adjustment signal to the capacitor array according to the corresponding comparison result;

the capacitor array executing a corresponding operation on a present exponent n to generate a corresponding compensation capacitor according to the corresponding adjustment signal, wherein n is an integer larger than or equal to 0; and

the capacitor array generating a present compensation capacitor according to a previous compensation capacitor generated by the capacitor array and the corresponding compensation capacitor.

19. The operation method of claim 18, wherein the detection voltage is determined according to capacitor variation of the sensing unit and the present compensation capacitor.

20. The operation method of claim 19, wherein the detection voltage is equal to the common voltage when the capacitor variation of the sensing unit is equal to the present compensation capacitor.

21. The operation method of claim 19, wherein the detection voltage is smaller than the common voltage when the capacitor variation of the sensing unit is greater than the present compensation capacitor.

22. The operation method of claim 19, wherein the detection voltage is greater than the common voltage when the capacitor variation of the sensing unit is smaller than the present compensation capacitor.

23. The operation method of claim 19, wherein the capacitor array executing the corresponding operation on the present exponent n to generate the corresponding compensation capacitor according to the corresponding adjustment signal comprises:

the capacitor array starting to increase the present compensation capacitor from an initial value, wherein the initial value is equal to 0; and

the comparator generating a first comparison result, the processing unit generating a first adjustment signal to the capacitor array according to the first comparison result, and the capacitor array progressively increasing the present exponent n to generate the compensation capacitor corresponding to 2ⁿ⁺¹ according to the first adjustment signal when the detection voltage is smaller than the common voltage of the touch panel.

24. The operation method of claim 23, the capacitor array generating the present compensation capacitor according to the previous compensation capacitor generated by the capacitor array and the corresponding compensation capacitor comprises:

the capacitor array adding the compensation capacitor corresponding to 2ⁿ⁺¹ to the previous compensation capacitor generated by the capacitor array to generate the present compensation capacitor.

25. The sensing circuit of claim 24, further comprising:

the comparator does not generate the corresponding comparison result when the detection voltage is equal to the common voltage.

26. The operation method of claim 24, wherein the capacitor array executing the corresponding operation on the present exponent n to generate the corresponding compensation capacitor according to the corresponding adjustment signal comprises:

the comparator generating a second comparison result, the processing unit generating a second adjustment signal to the capacitor array according to the second comparison result, and the capacitor array progressively decreasing the present exponent n to generate the compensation capacitor corresponding to 2<sup>n−

1</sup> according to the second adjustment signal when the detection voltage is greater than the common voltage of the touch panel.

27. The operation method of claim 26, wherein the capacitor array generating the present compensation capacitor according to the previous compensation capacitor generated by the capacitor array and the corresponding compensation capacitor comprises:

the capacitor array subtracting the compensation capacitor corresponding to 2<sup>n−

1</sup> from the previous compensation capacitor generated by the capacitor array to generate the present compensation capacitor.

28. The sensing circuit of claim 27, further comprising:

the comparator does not generate the corresponding comparison result when the detection voltage is equal to the common voltage.

29. The operation method of claim 27, wherein the capacitor array executing the corresponding operation on the present exponent n to generate the corresponding compensation capacitor according to the corresponding adjustment signal comprises:

the comparator generating the first comparison result, the processing unit generating the first adjustment signal to the capacitor array according to the first comparison result, and the capacitor array progressively decreasing the present exponent n to generate the compensation capacitor corresponding to 2<sup>n−

1</sup> according to the first adjustment signal when the detection voltage is smaller than the common voltage of the touch panel.

30. The operation method of claim 29, wherein the capacitor array generating the present compensation capacitor according to the previous compensation capacitor generated by the capacitor array and the corresponding compensation capacitor comprises:

the capacitor array adding the compensation capacitor corresponding to 2<sup>n−

1</sup> to the previous compensation capacitor generated by the capacitor array to generate the present compensation capacitor.

31. The sensing circuit of claim 30, further comprising:

the comparator does not generate the corresponding comparison result when the detection voltage is equal to the common voltage.

32. The operation method of claim 30, wherein the capacitor array executing the corresponding operation on the present exponent n to generate the corresponding compensation capacitor according to the corresponding adjustment signal comprises:

the comparator generating the second comparison result, the processing unit generating the second adjustment signal to the capacitor array according to the second comparison result, and the capacitor array progressively decreasing the present exponent n to generate the compensation capacitor corresponding to 2<sup>n−

1</sup> according to the second adjustment signal when the detection voltage is greater than the common voltage of the touch panel.

33. The operation method of claim 32, wherein the capacitor array generating the present compensation capacitor according to the previous compensation capacitor generated by the capacitor array and the corresponding compensation capacitor comprises:

the capacitor array subtracting the compensation capacitor corresponding to 2<sup>n−

1</sup> from the previous compensation capacitor generated by the capacitor array to generate the present compensation capacitor.

34. The sensing circuit of claim 33, further comprising:

the comparator does not generate the corresponding comparison result when the detection voltage is equal to the common voltage.