Touch-control liquid crystal display background of the invention

• US 7,737,940 B2
• Filed: 08/28/2007
• Issued: 06/15/2010
• Est. Priority Date: 09/01/2006
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation
• Inventors: Liu, Chun-ting, Hung, Chi-mao, Tsai, Kun-hua, Huang, Yi-pai, Lai, Ming-sheng, Chiang, Min-feng, Liu, Po-yuan, Chang, Ting-jui, Wu, Jeng-fang, Tsao, Cheng-han, Wang, Chih-wei, Chen, Yen-ting
• Primary Examiner(s): Shankar; Vijay
• Application Number:
  US11/846,405
• Publication Number:
  US 20080055267A1
• Time in Patent Office: 1,022 Days
• Field of Search: 345 87-104, 345204-215, 345/690
• US Class Current: 345/104
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells

Abstract

A liquid crystal display includes a source driver, a gate driver, a plurality of pixel units, a plurality of detecting circuits, and a decision unit. Each pixel unit includes a switch transistor and a liquid crystal capacitor. When turned on by a scan signal generated by the gate driver, the switch transistor conducts a data signal voltage generated by the source driver to the liquid crystal capacitor, to adjust alignment of liquid crystal molecules. Each detecting circuit is electrically connected to one pixel unit, and includes a first transistor, a second transistor, a third transistor and a sensor unit. The first transistor conducts a constant voltage to the sensor unit when turned on, and generates a dynamic voltage when turned off. Based on the dynamic voltage, the second transistor generates a dynamic current. The third transistor conducts the dynamic current to the decision unit when turned on. The decision unit determines the position of one detecting circuit by comparing the dynamic currents output by the plurality of detecting circuits.

Claims

1. A liquid crystal display, comprising:

a source driver generating a data signal voltage;

a gate driver generating a scan signal;

a plurality of pixel units arranged in a matrix, each pixel unit comprising a switch transistor for conducting the data signal voltage when turned on by the scan signal, and a liquid crystal capacitor having one end coupled to the switch transistor and the other end coupled to a common voltage end, the liquid crystal capacitor adjusting the arrangement of liquid crystal molecules disposed therein according to the data signal voltage;

a plurality of detecting circuits, each electrically connected to one pixel unit, each detecting circuit comprising;

a first transistor coupled to a constant voltage terminal and conducting a predetermined constant voltage from the constant voltage terminal when turned on by a control signal;

a sensor unit coupled to the first transistor for generating a dynamic voltage;

a second transistor coupled to the sensor unit for generating a dynamic current according to the dynamic voltage; and

a third transistor coupled to the second transistor for conducting the dynamic current when turned on; and

a decision unit coupled to the plurality of detecting circuits for determining the source of the dynamic currents by comparing all the dynamic currents output by the plurality of detecting circuits.

2. The liquid crystal display as claimed in claim 1, wherein the sensor unit is a variable capacitor.

3. The liquid crystal display as claimed in claim 2, wherein the variable capacitor generates a corresponding dynamic voltage according to its capacitance variation.

4. The liquid crystal display as claimed in claim 3, wherein terminals of the variable capacitor are respectively coupled to the first transistor and the common voltage end.

5. The liquid crystal display as claimed in claim 1, wherein the control signal is a scan signal exerted on the next array of pixel units by the gate driver.

6. The liquid crystal display as claimed in claim 1, further comprising a control signal generator, the control signal generator being coupled to a control terminal of the first transistor for generating and transmitting the control signal to the first transistor.

7. The liquid crystal display as claimed in claim 1, wherein the second transistor has a first terminal coupled to a second terminal of the third transistor, a second terminal coupled to the common voltage end, and a control terminal coupled to the sensor unit.

8. The liquid crystal display as claimed in claim 7, wherein the decision unit comprises a plurality of integrating circuits each for outputting a voltage according to the dynamic current, and a decision-making unit for comparing the output voltages of the integrating circuits and thus determining the source of the dynamic currents.

9. The liquid crystal display as claimed in claim 1, wherein the third transistor has a control terminal coupled to a control terminal of the switch transistor.

10. A liquid crystal display, comprising:

a source driver generating a data signal voltage;

a gate driver generating a scan signal;

a plurality of pixel units arranged in a matrix, each pixel unit comprising a switch transistor for conducting the data signal voltage when turned on by the scan signal, and a liquid crystal capacitor adjusting the arrangement of a plurality of liquid crystal molecules according to the data signal voltage;

a plurality of detecting circuits each electrically connected to one pixel unit, each detecting circuit including a first transistor coupled to a constant voltage terminal and conducting a constant voltage from the constant voltage terminal when turned on by a control signal voltage, a sensor unit coupled to the first transistor for generating a dynamic voltage, and a second transistor coupled to the sensor unit for generating a dynamic current according to the dynamic voltage when turned on; and

a decision unit coupled to the plurality of detecting circuits for determining the source of the dynamic currents by comparing all the dynamic currents outputted by the plurality of detecting circuits.

11. The liquid crystal display as claimed in claim 10, wherein the sensor unit is a variable capacitor.

12. The liquid crystal display as claimed in claim 11, wherein the variable capacitor generates a dynamic voltage according to capacitance variation of the variable capacitor.

13. The liquid crystal display as claimed in claim 12, wherein both terminals of the variable capacitor are respectively coupled to the first transistor and the common voltage end.

14. The liquid crystal display as claimed in claim 10, wherein the control signal voltage is a scan signal exerted on the next array of pixel units by the gate driver.

15. The liquid crystal display as claimed in claim 10, further comprising a control signal generator, the control signal generator being coupled to a control terminal of the first transistor for generating and transmitting the control signal voltage to the first transistor.

16. The liquid crystal display as claimed in claim 10, wherein the second transistor has a first terminal coupled to the decision unit, a second terminal coupled to the sensor unit and the first transistor, and a control terminal coupled to the switch transistor.

17. The liquid crystal display as claimed in claim 10, wherein the decision unit comprises a plurality of integrating circuits each for outputting a voltage according to the dynamic current, and a decision-making unit for comparing the output voltages of the integrating circuits and thus determining the source of the dynamic currents.

18. A liquid crystal display, comprising:

a source driver generating a data signal voltage;

a gate driver generating a scan signal;

a plurality of pixel units arranged in a matrix, each pixel unit comprising a switch transistor for conducting the data signal voltage when turned on by the scan signal, and a liquid crystal capacitor adjusting the arrangement of a plurality of liquid crystal molecules according to the data signal voltage;

a plurality of detecting circuits each electrically connected to one pixel unit, each detecting circuit comprising;

a sensor unit for generating a dynamic voltage, a transistor for generating a dynamic current according to the dynamic voltage when turned on by a control signal voltage; and

a conversion circuit for converting the dynamic current into a decision voltage signal; and

a decision-making unit determining the position of one of the plurality of detecting circuits by comparing the decision voltage signals output by the plurality of detecting circuits.

19. The liquid crystal display as claimed in claim 18, wherein the sensor unit is a variable capacitor.

20. The liquid crystal display as claimed in claim 19, wherein the variable capacitor generates a dynamic voltage according to capacitance variation of the variable capacitor.

21. The liquid crystal display as claimed in claim 20, wherein both terminals of the variable capacitor are respectively coupled to the transistor and the common voltage end.

22. The liquid crystal display as claimed in claim 18, wherein the transistor has a control terminal coupled to a control terminal of the switch transistor.

23. The liquid crystal display as claimed in claim 18, wherein the conversion circuit comprises:

an operational amplifier having a first input terminal coupled to a constant voltage terminal, a second input terminal and an output terminal;

a switch unit coupled between the second input terminal and the output terminal of the operational amplifier; and

a feedback capacitor coupled to the transistor for converting the dynamic current into the decision voltage signal when the switch unit is turned on.