Sensing method using self-capacitance and mutual-capacitance alternatively to reduce touch noises

1. A sensing method using self-capacitance and mutual-capacitance alternatively to reduce touch noises in a capacitive multi-touch system including a capacitive touch panel, a first driving and sensing device, a second driving and sensing device, and a control device, wherein the first driving and sensing device and the second driving and sensing device respectively has a first work mode and a second work mode, and the first driving and sensing device and the second driving and sensing device perform a self-capacitance sensing at the first work mode and perform a mutual-capacitance sensing at the second work mode, the sensing method comprising the steps of:

(A) initializing the first driving and sensing device and the second driving and sensing device by the control device;

(B) configuring the first driving and sensing device and the second driving and sensing device as the first work mode or the second work mode to alternatively perform the self-capacitance sensing and the mutual-capacitance sensing on the capacitive touch panel for finding a first possible touch point range or a second possible touch point range, wherein, in step (B), the control device configures the first driving and sensing device and the second driving and sensing device as the first work mode to perform at least one self-capacitance sensing on the capacitive touch panel for producing a self-capacitance image raw data, and the control device configures the first driving and sensing device and the second driving and sensing device as the second work mode to perform at least one mutual-capacitance sensing on the capacitive touch panel for producing a mutual-capacitance image raw data;

(C) determining whether there is a range conjunction between the first possible touch point range and the second possible touch point range; and

(D) producing a possible touch point range conjunction when there is the range conjunction, and calculating coordinates of touch points based on the possible touch point range conjunction.

2. The method as claimed in claim 1 , wherein when the step (C) determines that there is no range conjunction, the step (B) is performed.

3. The method as claimed in claim 2 , further comprising a step of:

(E) outputting the coordinates of touch points.

4. The method as claimed in claim 1 , wherein the control device determines whether the self-capacitance image raw data is greater than a first threshold so as to find the first possible touch point range in step (B).

5. The method as claimed in claim 1 , wherein, in step (B), the control device determines whether the mutual-capacitance image raw data is greater than a second threshold so as to find the second possible touch point range.

6. The method as claimed in claim 1 , wherein the control device configures the first driving and sensing device and the second driving and sensing device as the first work mode to perform the self-capacitance sensing on the capacitive touch panel for producing the first possible touch point range, and configures the first driving and sensing device and the second driving and sensing device as the second work mode to perform the mutual-capacitance sensing on the capacitive touch panel for producing the second possible touch point range in step (B).

7. The method as claimed in claim 1 , wherein the control device configures the first driving and sensing device and the second driving and sensing device as the second work mode to perform the mutual-capacitance sensing on the capacitive touch panel for producing the first possible touch point range, and configures the first driving and sensing device and the second driving and sensing device as the first work mode to perform the self-capacitance sensing on the capacitive touch panel for producing the second possible touch point range in step (B).

8. The method as claimed in claim 4 , wherein the capacitive touch panel has m first conductor lines distributed in a first direction and n second conductor lines distributed in a second direction, and the self-capacitance image raw data has an amount of m+n records, where m and n are each an integer greater than one.

9. The method as claimed in claim 5 , wherein the capacitive touch panel has m first conductor lines distributed in a first direction and n second conductor lines distributed in a second direction, and the mutual-capacitance image raw data has an amount of m*n records, where m and n are each an integer greater than one.

10. The method as claimed in claim 2 , wherein step (C) further calculates distance between each element of the first possible touch point range and each element of the second possible touch point range so as to produce the possible touch point range conjunction.

11. The method as claimed in claim 10 , wherein step (C) sequentially calculates distance between each element of the first possible touch point range and each element of the second possible touch point range, and determines that the element of the first possible touch point range is an element of the possible touch point range conjunction when there is the distance calculated to be zero.

12. The method as claimed in claim 11 , wherein step (C) determines that each element of the first possible touch point range is not an element of the possible touch point range conjunction when there is no distance calculated to be zero.