Method and apparatus for driving liquid crystal display

• US 20010004252A1
• Filed: 11/30/2000
• Published: 06/21/2001
• Est. Priority Date: 11/30/1999
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Shin, Hyun Ho, Park, Jong Jin
• Granted Patent: US 7,154,462 B2
• Time in Patent Office: Days
• US Class Current: 345/92
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/063 Waveforms for resetting the whole screen at once
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3677 suitable for active matrices only

Abstract

Driving a liquid crystal display device to eliminate a residual image upon realization of a moving picture. A first signal is applied to liquid crystal pixel cells for charging thereof during a beginning of a frame. A second signal is applied to the liquid crystal pixel cells for discharging thereof during an ending of the frame. Accordingly, a residual image on a screen can be eliminated.

Claims

1. A method of driving a liquid crystal display having liquid crystal pixel cells arranged at each intersection between a plurality of gate lines and a plurality of data lines in a matrix type and being driven with thin film transistors, said method comprising:

applying a first signal to the liquid crystal pixel cells for charging thereof during a beginning of a frame; and

applying a second signal to the liquid crystal pixel cells for discharging thereof during an ending of the frame.

2. The method according to

claim 1

, wherein each of the liquid crystal pixel cells includes a liquid crystal layer formed of any one of a ferro-electric liquid crystal and an anti-ferro-electric liquid crystal.

3. The method according to

claim 1

, wherein each of the liquid crystal pixel cells includes a liquid crystal layer formed of a twisted nematic liquid crystal having a response speed of less than 10 ms.

4. The method according to

claim 1

, further comprising the step of:

applying a gate pulse to the gate lines twice during the frame to sequentially apply the first signal and the second signal to the liquid crystal pixel cells.

5. A driving apparatus for a liquid crystal display having liquid crystal pixel cells arranged in a matrix at each intersection between a plurality of gate lines and a plurality of data lines and being driven with thin film transistors, said apparatus comprising:

a data driver to apply a first signal to the liquid crystal pixel cells for charging thereof during a beginning of a frame and to apply a second signal to the liquid crystal pixel cells for discharging thereof during an ending of the frame; and

a gate driver to apply a gate pulse signal with at least two gate pulses to the gate lines during the frame to sequentially apply the first signal and the second signal to the liquid crystal pixel cells.

6. The driving apparatus according to

claim 5

, wherein each of the liquid crystal pixel cells includes a liquid crystal layer formed of any one of a ferro-electric liquid crystal and an anti-ferro-electric liquid crystal.

7. The driving apparatus according to

claim 5

, wherein each of the liquid crystal pixel cells includes a liquid crystal layer formed of a twisted nematic liquid crystal having a response speed of less than 10 ms.

8. The driving apparatus according to

claim 5

, wherein the gate driver generates a gate pulse at a start of the frame and a mid-point of the frame.

9. The driving apparatus according to

claim 5

, further comprising:

a data compressor to compress the first signal synchronized with the frame front region of the frame; and

a data controller to write the second signal during the ending of the frame to apply the second signal to the data driver.

10. The driving apparatus according to

claim 9

, further comprising:

a memory to input and output the first signal at a different speed under a control of the data controller to compress the first signal.

11. A method of operating a liquid crystal cell comprising:

charging a liquid crystal cell during a beginning portion of a frame; and

completely discharging the liquid crystal cell before an end of the frame.

12. The method according to

claim 11

, wherein a period of discharging of the liquid crystal cell is short relative to a period that the liquid crystal cell is completely discharged.

13. A method of charging a liquid crystal cell comprising:

applying any one of a positive and negative charges to a pixel electrode of the liquid crystal cell during a beginning of a frame;

applying no charge to the pixel electrode of the liquid crystal cell during an ending of the frame; and

applying an opposite charge compared with a beginning of previous frame to the pixel electrode of the liquid crystal cell during a beginning of the next frame.

14. A method of driving a liquid crystal display (LCD) device comprising at least one thin film transistor (TFT), the method comprising:

activating the TFT of a pixel element at least twice during a one frame interval.

15. The method of

claim 14

, wherein the step of activating the TFT comprises:

applying a gate pulse signal to the TFT connected to a pixel element, the gate pulse signal having at least two gate pulses within a one frame interval; and

applying a video data signal to the pixel element in accordance with the gate pulse signal to charge the pixel element.

16. The method of

claim 15

, wherein at least one of the gate pulses is applied at a mid-point of the frame interval.

17. The method according to

claim 15

, wherein the step of applying the video data signal comprises:

applying any one of the positive and negative charges to the pixel element during a beginning of a frame;

applying no charge to the pixel element during an ending of the frame; and

applying an opposite charge compared with a beginning of previous frame to the pixel element during a beginning of the next frame.

18. An apparatus for driving a liquid crystal display device comprising at least one thin film transistor (TFT), comprising:

a gate driver to apply a gate pulse signal to the TFT connected to a pixel element, the gate pulse signal having at least two gate pulses within a one frame interval; and

a data driver to apply a video data signal to the pixel element in accordance with the gate pulse signal to charge the pixel element.

19. The apparatus of

claim 18

, wherein the gate driver comprises a plurality of gate drive circuits connected together in series.