Multiple fingers touch sensing method using matching algorithm

• US 8,194,051 B2
• Filed: 12/15/2009
• Issued: 06/05/2012
• Est. Priority Date: 12/15/2009
• Status: Active Grant

• Current Assignee: Silicon Integrated Systems Corporation (Silicon Integrated Systems Corporation Taiwan)
• Original Assignee: Silicon Integrated Systems Corporation (Silicon Integrated Systems Corporation Taiwan)
• Inventors: Yang, Shao-Sheng, Wu, Hung Wei, Chen, Chiung-Fu
• Primary Examiner(s): Tzeng, Fred
• Application Number:
  US12/638,966
• Publication Number:
  US 20110141054A1
• Time in Patent Office: 903 Days
• Field of Search: 345/174, 345/178
• US Class Current: 345/174
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment

Abstract

A touch sensing method for detecting positions of touching is disclosed. In the present invention, a reference touch profile is provided. A variable ideal combination profile indicating multiple touches is obtained by synthesizing a plurality of reference touch profiles at different positions. The variable ideal combination profile is matched with a sensing signal. Actual touch positions can be identified from the sensing signal when the matching of the variable ideal combination profile with the sensing signal is optimal.

Claims

1. A touch sensing method for detecting touching to a touch sensor, the method comprising:

providing a reference touch profile indicating an ideal touch;

extracting a sensing signal from the touch sensor;

matching the reference touch profile with the sensing signal to find an optimal result by moving the reference touch profile; and

identifying a position of touching from the reference touch profile in correspondence to the optimal result.

2. The method of claim 1 further comprising setting a searching range, wherein the searching range is defined by setting a signal amplitude threshold to the sensing signal, a position of a centroid of the reference touch profile falling within the searching range when being moved.

3. The method of claim 2, wherein the matching step comprises:

moving the reference touch profile progressively by a searching step by changing the position of the centroid of the reference touch profile within the searching range; and

comparing the reference touch profile with the sensing signal whenever the reference touch profile is moved by one searching step so as to obtain an optimal result.

4. The method of claim 2, wherein the matching step comprises:

selecting a beginning point within the searching range for searching, the beginning point indicating a specific position for the centroid of the reference touch profile; and

comparing the reference touch profile with the sensing signal beginning with a state in which the position of the centroid of the reference touch profile is at the beginning point by using a fast searching method so as to find the optimal result.

5. The method of claim 4, wherein the fast searching method is implemented by a Steepest Gradient Searching Method.

6. The method of claim 4, wherein the fast searching method is implemented by a Three Steps Searching Method.

7. The method of claim 1, wherein the matching step to find an optimal result is implemented by correlating the reference touch profile with the sensing signal to find the maximum result as the optimal result.

8. The method of claim 1, wherein the matching step to find an optimal result is implemented by calculating a difference between of the reference touch profile and the sensing signal to find the minimum result as the optimal result.

9. The method of claim 8, wherein the difference is calculated by using an SAD (sum of absolute difference) algorithm.

10. The method of claim 8, wherein the difference is calculated by using an MSE (mean square error) algorithm.

11. A touch sensing method for detecting multiple touches to a touch sensor, the method comprising:

providing a reference touch profile indicating an ideal touch;

extracting a sensing signal from the touch sensor;

synthesizing a plurality of the reference touch profiles to compose an ideal combination profile;

matching the ideal combination profile with the sensing signal by changing positions of centroids of the reference touch profiles composing the ideal combination profile so as to find an optimal result; and

identifying positions of touching from the ideal combination profile in correspondence to the optimal result.

12. The method of claim 11, further comprising setting a searching range, wherein the searching range is defined by setting a signal amplitude threshold to the sensing signal;

and positions of centroids of the reference touch profiles composing the ideal combination profile falling within the searching range when being changed.

13. The method of claim 12, wherein a sub-range for changing the position of the centroid of each reference touch profile is determined from the searching range.

14. The method of claim 12, wherein the matching step comprises:

varying the ideal combination profile progressively by a searching step by changing positions of the centroids of the reference touch profiles composing the ideal combination profile within the searching range; and

comparing the ideal combination profile with the sensing signal whenever one of the positions of the centroids of the reference touch profiles is changed by one searching step to synthesize the ideal combination profile so as to obtain an optimal result.

15. The method of claim 12, wherein the matching step comprises:

selecting a beginning point within the searching range for searching, the beginning point indicating specific positions for the centroids of the reference touch profiles composing the ideal combination profile; and

comparing the ideal combination profile with the sensing signal beginning with a state in which the centroids of the reference touch profiles meet the beginning point by using a fast searching method so as to find the optimal result.

16. The method of claim 15, wherein the fast searching method is implemented by a Steepest Gradient Searching Method.

17. The method of claim 15, wherein the fast searching method is implemented by a Three Steps Searching Method.

18. The method of claim 11, wherein the matching step to find an optimal result is implemented by correlating the ideal combination profile with the sensing signal to find the maximum result as the optimal result.

19. The method of claim 11, wherein the matching step to find an optimal result is implemented by calculating a difference between of the ideal combination touch profile and the sensing signal to find the minimum result as the optimal result.

20. The method of claim 19, wherein the difference is calculated by using an SAD (sum of absolute difference) algorithm.

21. The method of claim 19, wherein the difference is calculated by using an MSE (mean square error) algorithm.

22. A touch sensing method for detecting touching to a touch sensor, the method comprising:

providing a reference touch profile indicating an ideal touch;

extracting a sensing signal from the touch sensor;

identifying a touch region from the sensing signal, at least one touch occurring in the touch region;

identifying how many touches has occurred in the touch region;

matching the reference touch profile with the sensing signal to find an optimal result by moving the reference touch profile when it is determined that there is only one touch in the touch region while synthesizing a plurality of the reference touch profiles to compose an ideal combination profile and matching the ideal combination profile with the sensing signal by changing positions of centroids of the reference touch profiles composing the ideal combination profile so as to find the optimal result when it is determined that there are plural of touches in the touch region; and

identifying a position or positions of touching from the reference touch profile or the ideal combination profile in correspondence to the optimal result.