Liquid crystal display device and method for operating the same

• US 20030122772A1
• Filed: 12/27/2002
• Published: 07/03/2003
• Est. Priority Date: 12/29/2001
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Park, Jong Jin, Son, Hyeon Ho
• Granted Patent: US 7,012,598 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2320/0209 Crosstalk reduction, i.e. to reduce direct or indirect influences of signals directed to a certain pixel of the displayed image on other pixels of said image, inclusive of influences affecting pixels in different frames or fields or sub-images which constitute a same image, e.g. left and right images of a stereoscopic display
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A method for operating a liquid crystal display having a panel with a back light includes applying a first gate signal starting a real data period followed by a second gate signal starting a black data period sequentially to gate lines of the panel, applying actual picture data signals to data lines of the panel during the real data period and reset data signals to the data lines of the panel during the black data period to drive cells of the panel during a frame along a gate line and controlling a ratio of the real data period to the black data period for a subsequent frame.

Claims

1. A method for operating a liquid crystal display having a panel with a back light comprising the steps of:

applying a first gate signal starting a real data period followed by a second gate signal starting a black data period sequentially to gate lines of the panel;

applying actual picture data signals to data lines of the panel during the real data period and reset data signals to the data lines of the panel during the black data period to drive cells of the panel during a frame along a gate line; and

controlling a ratio of the real data period to the black data period for a subsequent frame.

2. The method according to claim 1, wherein the step of controlling the ratio includes the step of:

decreasing the black data period of a next frame, if a present frame has a bright picture data.

3. The method according to claim 1, wherein the step of controlling the ratio includes the step of:

increasing the black data period of a next frame, if a present frame has a dark picture data.

4. The method according to claim 1, wherein the step of controlling a ratio includes the step of:

increasing the black data period of a next frame, if prior frames have a fast picture speed.

5. The method according to claim 1, wherein the step of controlling a ratio includes the step of:

decreasing the black data period of the next frame, if prior frames have a slow picture speed.

6. A method for operating a liquid crystal display (LCD) having a back light part with a plurality of light emission elements connected to respective power source terminals, the method comprising the steps of:

providing a gate signal sequentially to a plurality of gate lines such that all the thin film transistors along each gate line are turned on;

providing one of a reset data signal and actual picture data signal through each of the turned on thin film transistors;

controlling the power source terminals to turn off a light emission element corresponding to a gate line receiving a reset data signal and to turn on a light emission element corresponding to a gate line receiving an actual picture data signal.

7. A method for operating a liquid crystal display (LCD) panel having a plurality of gate lines and a plurality of data lines that cross each other in which a plurality of light emission elements are in correspondence to the gate lines of the LCD panel, the method comprising the steps of:

applying a gate signal sequentially to the gate lines;

applying a data signal to the data lines synchronized to the gate signal in each frame;

controlling a black data period of a subsequent frame based upon a state of a present frame; and

turning off the light emission elements corresponding gate lines in a black data period.

8. The method according to claim 7, wherein the black data period is reduced in a subsequent frame if a present frame has a relatively bright picture data.

9. The method according to claim 7, wherein the black data period is increased in the next frame if the present frame has a relatively dark picture data.

10. The method according to claim 7, wherein a number of the turned off light emission elements is reduced if the black data period is reduced.

11. The method according to claim 7, wherein a number of the turned off light emission elements is increased if the black data period is increased.

12. The method according to claim 7, wherein the black data period is increased in a subsequent frame if prior frames have a relatively fast picture speed.

13. The method according to claim 7, wherein the black data period is reduced in a subsequent frame if prior frames have a relatively slow picture speed.

14. The method according to claim 7, wherein a number of the turned off light emission elements is reduced if the black data period is reduced.

15. The method according to claim 7, wherein a number of the turned off light emission elements is increased if the black data period is increased.

16. A liquid crystal display device comprising:

a panel having a plurality of gate lines running in parallel in one direction and a plurality of data lines running in parallel perpendicular to the gate lines;

gate input drivers for providing gate signals to the gate lines;

data input drivers for providing data signals to the data lines; and

a back light unit having a plurality of light emitting elements parallel to the gate lines, wherein at least one of the light emitting elements are turned off for a time interval corresponding to a data signal provided to pixels along at least one gate line corresponding to the at least one light emitting element.

17. The device according to claim 16, a position that the at least one of the light emitting elements that is turned off appears to move in a vertical direction as time goes by.