Liquid crystal display device and method for driving the same

• US 20060164379A1
• Filed: 12/29/2005
• Published: 07/27/2006
• Est. Priority Date: 12/30/2004
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Hong, Hee Jung, Oh, Eui Yeol
• Granted Patent: US 8,760,382 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• 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

Abstract

A liquid crystal panel includes a plurality of display regions that correspond to the division images. The number of the division images can be set with consideration of the number of lamps covering the display regions. The average brightness of an entire image is compared with the average brightness of the division images so as to vary brightness of each division image according to a comparison result. Light that corresponds to the varied brightness is illuminated to each display region. Therefore, a dark division image is displayed darker and a bright division image is displayed brighter in the image of one frame, thereby enhancing a contrast ratio and reducing power consumption.

Claims

1. A liquid crystal display (LCD) device, comprising:

an LCD panel having a plurality of display regions for displaying a plurality of division images divided from a predetermined image;

a controller to control brightness of each of the plurality of division images; and

an illuminating portion including a plurality of lamps to emit light, which corresponds to the brightness, to each of the plurality of display regions under control of the controller.

2. The LCD according to claim 1, wherein the predetermined image is an image of one frame.

3. The LCD according to claim 1, wherein the controller includes:

a first calculator to calculate average brightness of the predetermined image;

an image dividing part to divide the image into the plurality of division images;

a second calculator to calculate average brightness of the plurality of division images; and

a comparing portion to compare the average brightness of the predetermined image with the average brightness of each of the plurality of division images and to vary the brightness of the each of the plurality of division images according to a comparison result.

4. The LCD according to claim 3, further comprising a division setting part to set the number of the plurality of division images.

5. The LCD according to claim 4, wherein the division setting part sets the number of the plurality of division images with consideration of the number of the plurality of lamps for covering the plurality of display regions that correspond to the plurality of division images.

6. The LCD according to claim 3, wherein the comparing portion generates a drive signal to increase the brightness of the division image when the average brightness of the division image is greater than the average brightness of the predetermined image.

7. The LCD according to claim 3, wherein the comparing portion generates a drive signal to maintain the brightness of the division image when the average brightness of the division image is greater than the average brightness of the predetermined image.

8. The LCD according to claim 3, wherein the comparing portion generates a drive signal to decrease the brightness of the division image when the average brightness of the division image is smaller than the average brightness of the predetermined image.

9. The LCD according to claim 1, wherein the illuminating portion includes:

a driver to generate a driving voltage according to the brightness of the each of the plurality of division images; and

a backlight unit to emit the light that corresponds to the driving voltage associated with the brightness of the each of the plurality of division images.

10. The LCD according to claim 9, wherein the backlight unit includes a plurality of lamp groups covering the plurality of display regions.

11. The LCD according to claim 1, wherein the lamps comprise a plurality of CCFLs, EEFLs or LEDs.

12. A method for driving an LCD, comprising:

controlling brightness of each of a plurality of division images divided from the predetermined image;

illuminating light corresponding to the brightness of the each of the plurality of division images; and

displaying the each of the plurality of division images using the corresponding light.

13. The method according to claim 12, the brightness controlling includes:

calculating average brightness of the predetermined image;

dividing the predetermined image into the plurality of division images;

calculating average brightness of the plurality of division images; and

comparing the average brightness of the predetermined image with the average brightness of each of the plurality of division images and varying the brightness of the each of the plurality of division images according to a comparison result.

14. The method according to claim 13, further comprising setting the number of the division images with consideration of the number of lamps for covering the display regions that correspond to the division images.

15. The method according to claim 14, wherein the lamps comprise a plurality of CCFLs or EEFLs or LEDs.

16. The method according to claim 13, wherein the varying of the brightness includes generating a drive signal to increase the brightness of the division image when the average brightness of the division image is greater than the average brightness of the entire image.

17. The method according to claim 13, wherein the varying of the brightness includes generating a drive signal to maintain the brightness of the division image when the average brightness of the division image is greater than the average brightness of the entire image.

18. The method according to claim 13, wherein the varying of the brightness includes generating a drive signal to lower the brightness of the division image when the average brightness of the division image is smaller than the average brightness of the entire image.

19. The method according to claim 12, wherein the illuminating of light includes:

generating a driving voltage according to the brightness of the each of the plurality of division images; and

generating light that corresponds to the driving voltage associated with the brightness of the each of the plurality of division images.