TOUCH PANEL AND METHOD OF REDUCING NOISE COUPLED BY A COMMON VOLTAGE OF A TOUCH PANEL

• US 20120146920A1
• Filed: 03/28/2011
• Published: 06/14/2012
• Est. Priority Date: 12/14/2010
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation
• Inventors: Lin, Jian-Hong, Chuang, Ching-Hua, Guo, Wen-Rei
• Granted Patent: US 8,508,503 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• 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
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

A touch panel includes a touch sensor, a liquid crystal panel, and a reverse circuit. The reverse circuit receives common voltage ripples of the liquid crystal panel, and outputs reversed common voltage ripples after reversing the common voltage ripples. After the touch sensor receives the reversed common voltage ripples, the touch sensor outputs a sensing signal according to the reversed common voltage ripples.

Claims

1. A touch panel, comprising:

a touch sensor for outputting at least one sensing signal corresponding to at least one object when the at least one object touches the touch panel;

a liquid crystal panel comprising a common electrode, the liquid crystal panel used for executing at least one corresponding operation according to the at least one sensing signal; and

a reverse circuit having a first terminal coupled to the liquid crystal panel for receiving common voltage ripples of the common electrode of the liquid crystal panel coupled to the touch sensor, and a second terminal coupled to the touch sensor for outputting reversed common voltage ripples;

wherein the touch sensor is located on the liquid crystal panel.

2. The touch panel of claim 1, wherein the reverse circuit comprises an inverter.

3. The touch panel of claim 1, wherein the reverse circuit comprises:

a first amplifier having a first input terminal coupled to the first terminal of the reverse circuit for receiving the common voltage ripples, a second input terminal, and an output terminal coupled to the second input terminal of the first amplifier;

a capacitor having a first terminal coupled to the output terminal of the first amplifier, and a second terminal;

a first resistor having a first terminal coupled to the second terminal of the capacitor, and a second terminal;

a second amplifier having a first input terminal for receiving a reference voltage, a second input terminal coupled to the second terminal of the first resistor, and an output terminal coupled to the second terminal of the reverse circuit for outputting the reversed common voltage ripples; and

a second resistor having a first terminal coupled to the second input terminal of the second amplifier, and a second terminal coupled to the output terminal of the second amplifier.

4. The touch panel of claim 1, wherein the reverse circuit is located on a printed circuit board outside the liquid crystal panel, and the printed circuit board is electrically connected to the liquid crystal panel.

5. The touch panel of claim 1, wherein the liquid crystal panel comprises:

a polarizer for absorbing polarized light having a predetermined direction, and outputting polarized light orthogonal to the predetermined direction;

a color filter below the polarizer having a plurality of pixels, wherein each pixel has a red sub-pixel, a green sub-pixel, and a blue sub-pixel;

a control circuit array for providing a pixel voltage corresponding to the pixel;

a color filter indium tin oxide (ITO) below the color filter for controlling turning-on of the red sub-pixel, the green sub-pixel, and the blue sub-pixel according to the pixel voltage; and

a liquid crystal array below the color filter indium tin oxide for twisting a plurality of liquid crystal molecules corresponding to the pixel according to the pixel voltage;

wherein the control circuit array is below the liquid crystal array, the color filter indium tin oxide is located between the color filter and the liquid crystal array, and the liquid crystal array is located between the control circuit array and the color filter indium tin oxide.

6. The touch panel of claim 5, wherein the control circuit array and the color filter indium tin oxide are coupled to the common electrode of the liquid crystal panel.

7. The touch panel of claim 5, wherein the first terminal of the reverse circuit is coupled to the color filter indium tin oxide, and the second terminal of the reverse circuit is coupled to the touch sensor.

8. The touch panel of claim 5, wherein the first terminal of the reverse circuit is coupled to the control circuit array, and the second terminal of the reverse circuit is coupled to the touch sensor.

9. The touch panel of claim 5, wherein the control circuit array is electrically connected the color filter indium tin oxide by a conductive adhesive.

10. The touch panel of claim 5, wherein the touch sensor is integrated into the color filter.

11. The touch panel of claim 1, wherein the touch sensor is integrated into a color filter.

12. A method of reducing noise coupled by a common voltage of a touch panel, the method comprising:

a reverse circuit receiving common voltage ripples of a liquid crystal panel;

the reverse circuit reversing the common voltage ripples;

the reverse circuit outputting reversed common voltage ripples;

a touch sensor receiving the reversed common voltage ripples; and

the touch sensor outputting a sensing signal according to the reversed common voltage ripples.

13. The method of claim 12, wherein the reverse circuit receiving the common voltage ripples is the reverse circuit receiving the common voltage ripples through a color filter indium tin oxide of the liquid crystal panel.

14. The method of claim 12, wherein the reverse circuit receiving the common voltage ripples is the reverse circuit receiving the common voltage ripples through a control circuit array of the liquid crystal panel.