Liquid crystal display device and driving method thereof

• US 20070285365A1
• Filed: 02/28/2007
• Published: 12/13/2007
• Est. Priority Date: 06/13/2006
• Status: Abandoned Application

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Ki-Chan
• Application Number:
  US11/712,645
• Publication Number:
  US 20070285365A1
• Time in Patent Office: Days
• US Class Current: 345/87
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• 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, comprising a plurality of pixels, a data driver and a sense signal generator, where each of the pixels comprises a switch coupled to a data line and a liquid crystal capacitor. The liquid crystal capacitor is coupled to the switch and its capacitance is varied in response to external touch. The gate driver provides a gate signal to the pixel and the data driver provides data voltage to a data line. The sense signal generator generates a sensing signal by sensing a capacitance of the liquid crystal capacitor.

Claims

1. A liquid crystal display, comprising:

a data line;

a gate line;

a data driver having an output terminal for applying a data voltage to the data line during a display period;

a gate driver for applying a gate voltage to the gate line;

a pixel comprising a liquid crystal capacitor coupled to a switching transistor, wherein the liquid crystal capacitor is charged to a voltage via the switching transistor which is coupled to the gate line and the data line;

a sense signal generator having an input and being adapted to sense a capacitance value of the liquid crystal capacitor and generate a sense signal; and

a first switch operable to selectively couple the sense signal generator to the liquid crystal capacitor.

2. The liquid crystal display according to claim 1 wherein the sense signal generator comprises a switched capacitor amplifier.

3. The liquid crystal display according to the claim 2, wherein the switched capacitor amplifier comprises:

an input node;

an amplifier having a first input terminal, a second input terminal and a an output terminal;

a first capacitor coupled between the first input terminal and the input node;

a second capacitor coupled between the first input terminal and the second node which is an output terminal of the amplifier;

a second switch for selectively connecting the first node to the second input terminal; and

a third switch for selectively connecting the first input terminal to the output terminal.

4. The liquid crystal display according to the claim 3, wherein the first switch couples the liquid crystal capacitor to the input node during a sensing period.

5. The liquid crystal display according to the claim 4, wherein the first switch is operable to connect the data line to the switching transistor during a time other than during the sensing period.

6. The liquid crystal display according to the claim 2, wherein the switched capacitor amplifier amplifies a capacitance variation of the liquid crystal capacitor.

7. The liquid crystal display according to the claim 1, wherein the displaying period may comprise a sensing period.

8. A liquid crystal display, comprising:

a plurality of data lines;

a plurality of gate lines;

a display panel having an upper substrate and a lower substrate for displaying image;

a plurality of pixels arranged in a matrix in a pixel area, in which each pixel group has a plurality of pixels;

a data driver having output terminals for applying data voltages to associated data lines;

a gate driver for applying gate voltages to associated gate lines;

a sense signal generator coupled to the pixel groups and positioned on the lower substrate;

a plurality of first switches operable to selectively couple the sense signal generator to the pixels; and

a comparing circuit coupled to an output of the sense signal generator.

9. The liquid crystal display according to the claim 8, wherein the sense signal generator comprises a plurality of sensing circuits.

10. The liquid crystal display according to the claim 9, wherein each sense circuit comprises:

an input node;

an amplifier having a first input terminal, a second input terminal and a an output terminal;

a first capacitor coupled between the first input terminal and the input node;

a second capacitor coupled between the first input terminal and the second node which is an output terminal of the amplifier;

a second switch for selectively connecting the first node to the second input terminal; and

a third switch for selectively connecting the first input terminal to the output terminal.

11. The liquid crystal display according to the claim 10, wherein the plurality of first switches is commonly coupled to the first node during a sensing period.

12. The liquid crystal display according to the claim 10, wherein the plurality of first switches is commonly coupled to the output terminals of the data driver except during a sensing period.

13. A driving method of liquid crystal display, comprising:

connecting an output terminal of a data driver to a data line by using a first switch;

providing a data voltage from the data driver to a pixel which includes a liquid crystal capacitor;

selectively connecting a sense circuit to the pixels;

sensing a capacitance of the liquid crystal capacitor;

amplifying the data voltage by using the capacitance;

generating a sensing signal in response to the amplified data voltage; and

comparing the sensing signal with the data voltage in a comparing circuit.

14. A driving method of liquid crystal display according to the claim 13, wherein sensing the capacitance is performed during a sensing period.

15. A driving method of liquid crystal display according to the claim 13, further comprising storing the data voltage to a storage capacitor.

16. A driving method of liquid crystal display according to the claim 13, further comprising disconnecting the sense circuit from the pixels after sensing the capacitance.