Method for Scanning Projective Capacitive Touch Panel, Storage Medium and Apparatus for Scanning Projective Capacitive Touch Panel

• US 20110175835A1
• Filed: 01/19/2011
• Published: 07/21/2011
• Est. Priority Date: 01/21/2010
• Status: Abandoned Application

• Current Assignee: TPK Touch Solutions (Xiamen) Inc. (TPK Holding Co., Ltd.)
• Original Assignee: TPK Touch Solutions (Xiamen) Inc. (TPK Holding Co., Ltd.)
• Inventors: Wang, Wanqiu
• Application Number:
  US13/009,847
• Publication Number:
  US 20110175835A1
• 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 3/041662 using alternate mutual and self-capacitive scanning
• 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

The present invention relates to a method for scanning a projective capacitive touch panel including: A. scanning each first-axis electrode arranged along a first-axis and each second-axis electrode arranged along a second-axis, then obtaining the first-axis electrode and the second-axis electrode whose self capacitance changes; B. detecting the mutual capacitance at each intersection between the first-axis electrode and the second-axis electrode whose self capacitance changes to determine whether the mutual capacitance changes, then the area where the mutual capacitance changes being taken as a touched area. The present invention also relates to a storage medium storing instructions of implementing above method and an apparatus that implements the above method.

Claims

1. A method for scanning a projective capacitive touch panel, comprising:

A- scanning each first-axis electrode arranged along a first-axis and each second-axis electrode arranged along a second-axis by a controller, then obtaining the first-axis electrode and the second-axis electrode whose self capacitance changes;

B- detecting mutual capacitance at each intersection between the first-axis electrode and the second-axis electrode which electrodes'"'"' self capacitance changes to determine whether the mutual capacitance changes, then area where the mutual capacitance changes being taken as a touched area.

2. The method according to claim 1, wherein the process of obtaining the first-axis electrode and the second-axis electrode whose self capacitance changes according to step A comprises:

comparing a current self capacitance of each of the first-axis electrode and the second-axis electrode with a preset reference self capacitance of the respective first-axis electrode and second-axis electrode;

obtaining the first-axis electrode and the second-axis electrode whose current self capacitance satisfies a preset condition.

3. The method according to claim 2, wherein the process of obtaining the current self capacitance comprises:

charging each of the first-axis electrode and the second-axis electrode;

discharging each of the first-axis electrode and the second-axis electrode to a reference capacitor correspondingly connected to the first-axis electrode and the second-axis electrode;

obtaining the current self capacitance of the first-axis electrode and the second-axis electrode when the process of discharging is completed.

4. The method according to claim 2, wherein the preset reference self capacitance of each of the first-axis electrode and the second-axis electrode is an average value of multiple initial self capacitance obtained from repeated initialization scanning of each of the first-axis electrode and the second-axis electrode correspondingly.

5. The method according to claim 4, wherein the initialization scanning comprises:

charging each of the first-axis electrode and the second-axis electrode;

discharging each of the first-axis electrode and the second-axis electrode to a reference capacitor correspondingly connected to each of the first-axis electrode and the second-axis electrode;

obtaining the initial self capacitance of each of the first-axis electrode and the second-axis electrode when the process of discharging is completed.

6. The method according to claim 2, wherein the preset condition is difference of the self capacitance to the preset reference self capacitance is greater than a preset threshold value.

7. The method according to claim 1, wherein the process of determining whether the mutual capacitance changes comprises:

comparing a current mutual capacitance at each intersection with a preset reference mutual capacitance at the intersection;

obtaining the area where the current mutual capacitance satisfies a preset condition.

8. The method according to claim 7, wherein the process of obtaining the current mutual capacitance comprises:

charging each of the second-axis electrode whose self capacitance changes;

collecting electric charges induced in the first-axis electrode and converting the electric charges to voltage value, according to which obtaining the current mutual capacitance at the intersection.

9. The method according to claim 7, wherein the preset reference mutual capacitance at the intersection is an average value of multiple initial mutual capacitance obtained from initialization scanning of the intersection repeatedly.

10. The method according to claim 9, wherein the initialization scanning comprises:

charging each of the second-axis electrode;

collecting electric charges induced in the first-axis electrode and converting the electric charges to voltage value, according to which obtaining the initial mutual capacitance at the intersection.

11. The method according to claim 7, wherein the preset condition is difference of the current mutual capacitance to the preset reference mutual capacitance at the intersection is greater than a preset threshold value.

12. The method according to claim 1 further comprising:

calculating centroid of the touched area.

13. The method according to claim 1, wherein if the self capacitance of any of the first-axis electrode or the second-axis electrode does not change, repeat step A.

14. A storage medium for storing a set of instructions to perform a method for scanning a projective capacitive touch panel, the method comprising:

A- scanning each first-axis electrode arranged along a first-axis and each second-axis electrode arranged along a second-axis, then obtaining the first-axis electrode and the second-axis electrode whose self capacitance changes;

B- detecting mutual capacitance at each intersection between the first-axis electrode and the second-axis electrode whose self capacitance changes to determine whether the mutual capacitance changes, then area where the mutual capacitance changes being taken as a touched area.

15. A system for scanning a projective capacitive touch panel, comprising:

a scanning module for detecting self capacitances of first-axis electrodes and second-axis electrodes;

a controlling module for determining whether the self capacitances change and controlling the scanning module to detect a mutual capacitance at an intersection between the first-axis electrode and the second-axis electrode if the self capacitance of the first-axis electrode and the second-axis electrode changes and determining a touched area defined by the intersection having a changed mutual capacitance.