METHOD OF A TOUCH PANEL DETERMINING MULTI-TOUCH

• US 20120139849A1
• Filed: 04/14/2011
• Published: 06/07/2012
• Est. Priority Date: 12/03/2010
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation
• Inventors: Syu, Shen-Sian, Yu, Ya-Yun
• Granted Patent: US 8,810,531 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• 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 3/041661 using detection at multiple resolutions, e.g. coarse and fine scanning; using detection within a limited area, e.g. object tracking window

Abstract

In a method of a touch panel determining multi-touch, the touch panel can determine if a sensing channel having a local minimum of a sensing value is the last sensing channel having the sensing value, or determine if sensing channels having the sensing value larger than a threshold generated according to a maximum are successive sensing channels, so as to determine the number of touch points on the touch panel. In addition, the touch panel can find a first local maximum and a second local maximum from the sensing values of the sensing channels, and compare the first local maximum and the second local maximum with a first reference and a second reference, so as to confirm the number of touch points on the touch panel.

Claims

1. A method of determining multi-touch in a touch panel, the method comprising:

utilizing a plurality of sense channels to detect touch points on the touch panel for generating corresponding sense values;

finding a local minimum of the sense values of the plurality of sense channels according to slope variation of sense values of two neighboring sense channels of the plurality of sense channels;

determining when the sense channel having the local minimum is the last sense channel having a sense value; and

determining number of touch points on the touch panel according to a result of determining whether the sense channel has the local minimum.

2. The method of claim 1, further comprising:

determining that the touch panel has one touch point thereon when the sense channel having the local minimum is the last sense channel having a sense value.

3. The method of claim 1, further comprising:

determining that the touch panel has two touch points thereon when the sense channel having the local minimum is not the last sense channel having a sense value.

4. The method of claim 1, wherein the step of finding the local minimum of the sense values of the plurality of sense channels according to the slope variation of the sense values of the two neighboring sense channels of the plurality of sense channels comprises:

determining sense value of a sense channel to be a local minimum when slope variation of sense values of the sense channel and neighboring previous and following sense channels of the sense channel changes from a negative value to a positive value.

5. The method of claim 1, further comprising:

estimating sense values of sense channels on either side of the sense channel having the local minimum according to slope of the sense values of the sense channel having the local minimum and the neighboring previous and following sense channels of the sense channel having the local minimum.

6. The method of claim 1, further comprising:

finding a first local maximum and a second local maximum from sense values of the plurality of sense channels; and

comparing the first local maximum and the second local maximum with a first reference and a second reference for confirming the number of touch points on the touch panel.

7. The method of claim 6, further comprising:

confirming the touch panel has two touch points when the first local maximum and the second local maximum are greater than the first reference;

maintaining the determined number of touch points when the first local maximum is greater than the first reference, and the second local maximum is between the first reference and the second reference;

confirming the touch panel has one touch point when the first local maximum is greater than the first reference, and the second local maximum is less than the second reference;

maintaining the determined number of touch points when the first local maximum is between the first reference and the second reference, and the second local maximum is greater than the first reference;

maintaining the determined number of touch points when the first local maximum and the second local maximum are between the first reference and the second reference;

confirming the touch panel has one touch point when the first local maximum is between the first reference and the second reference, and the second local maximum is less than the second reference;

confirming the touch panel only has one touch point when the first local maximum is less than the second reference, and the second local maximum is greater than the first reference;

confirming the touch panel has one touch point when the first local maximum is less than the second reference, and the second local maximum is between the first reference and the second reference; and

confirming the touch panel has one touch point when the first local maximum and the second local maximum are less than the second reference.

8. The method of claim 6, further comprising:

comparing the first local maximum and the second local maximum with a threshold for calculating touch point coordinates of the touch points on the touch panel according to a comparison result.

9. The method of claim 1, further comprising:

determining the touch panel has two touch points when a sense value generated by a sense channel between the plurality of sense channels is approximately zero.

10. A method of determining multi-touch in a touch panel, the method comprising:

utilizing a plurality of sense channels to detect touch points on the touch panel for generating corresponding sense values;

finding a maximum of the sense values of the plurality of sense channels;

generating a first threshold according to the maximum;

finding sense channels of the plurality of sense channels having sense value greater than the first threshold; and

determining when the sense channels having sense value greater than the first threshold are consecutive sense channels for determining number of touch points on the touch panel.

11. The method of claim 10, further comprising:

determining the touch panel has two touch points when separation between the sense channels having sense value greater than the first threshold is greater than a predetermined number of sense channels.

12. The method of claim 10, further comprising:

determining the touch panel has one touch point when the sense channels having sense value greater than the first threshold are consecutive sense channels.

13. The method of claim 10, further comprising:

generating a second threshold according to the maximum when the sense channels having sense value greater than the first threshold are consecutive sense channels;

finding sense channels of the plurality of sense channels having sense value greater than the second threshold; and

determining when the sense channels having sense value greater than the second threshold are consecutive sense channels for determining number of touch points on the touch panel.

14. The method of claim 10, further comprising:

finding a first local maximum and a second local maximum from the sense values of the plurality of sense channels; and

comparing the first local maximum and the second local maximum with a first reference and a second reference for confirming the number of touch points on the touch panel.

15. The method of claim 14, further comprising:

confirming the touch panel has two touch points when the first local maximum and the second local maximum are greater than the first reference;

maintaining the determined number of touch points when the first local maximum is greater than the first reference, and the second local maximum is between the first reference and the second reference;

confirming the touch panel has one touch point when the first local maximum is greater than the first reference, and the second local maximum is less than the second reference;

maintaining the determined number of touch points when the first local maximum is between the first reference and the second reference, and the second local maximum is greater than the first reference;

maintaining the determined number of touch points when the first local maximum and the second local maximum are between the first reference and the second reference;

confirming the touch panel has one touch point when the first local maximum is between the first reference and the second reference, and the second local maximum is less than the second reference;

confirming the touch panel only has one touch point when the first local maximum is less than the second reference, and the second local maximum is greater than the first reference;

confirming the touch panel has one touch point when the first local maximum is less than the second reference, and the second local maximum is between the first reference and the second reference; and

confirming the touch panel has one touch point when the first local maximum and the second local maximum are less than the second reference.

16. The method of claim 14, further comprising:

comparing the first local maximum and the second local maximum with a threshold for calculating touch point coordinates of the touch points on the touch panel according to a comparison result.

17. The method of claim 10, further comprising:

determining the touch panel has two touch points when a sense value generated by a sense channel between the plurality of sense channels is approximately zero.

18. A method of determining multi-touch in a touch panel, the method comprising:

utilizing a plurality of sense channels to detect touch points on the touch panel for generating corresponding sense values;

determining number of touch points on the touch panel;

finding a first local maximum and a second local maximum from the sense values of the plurality of sense channels; and

comparing the first local maximum and the second local maximum with a first reference and a second reference for confirming the number of touch points on the touch panel.

19. The method of claim 18, further comprising:

confirming the touch panel has two touch points when the first local maximum and the second local maximum are greater than the first reference;

maintaining the determined number of touch points when the first local maximum is greater than the first reference, and the second local maximum is between the first reference and the second reference;

confirming the touch panel has one touch point when the first local maximum is greater than the first reference, and the second local maximum is less than the second reference;

maintaining the determined number of touch points when the first local maximum is between the first reference and the second reference, and the second local maximum is greater than the first reference;

maintaining the determined number of touch points when the first local maximum and the second local maximum are between the first reference and the second reference;

confirming the touch panel has one touch point when the first local maximum is between the first reference and the second reference, and the second local maximum is less than the second reference;

confirming the touch panel only has one touch point when the first local maximum is less than the second reference, and the second local maximum is greater than the first reference;

confirming the touch panel has one touch point when the first local maximum is less than the second reference, and the second local maximum is between the first reference and the second reference; and

confirming the touch panel has one touch point when the first local maximum and the second local maximum are less than the second reference.

20. The method of claim 18, further comprising:

comparing the first local maximum and the second local maximum with a threshold for calculating touch point coordinates of the touch points on the touch panel according to a comparison result.

21. The method of claim 18, further comprising:

determining the touch panel has two touch points when a sense value generated by a sense channel between the plurality of sense channels is approximately zero.