Liquid crystal display device

• US 20010052891A1
• Filed: 03/06/2001
• Published: 12/20/2001
• Est. Priority Date: 11/13/1998
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Yoshihara, Toshiaki, Makino, Tetsuya, Kiyota, Yoshinori, Shiroto, Hironori
• Granted Patent: US 6,828,954 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• 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 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• 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 display device including a liquid crystal panel having a plurality of liquid crystal pixels and a plurality of switching elements provided to correspond to the respective liquid crystal pixels; a back-light, disposed on the rear face of the liquid crystal panel, for emitting red, green and blue lights in a time-divided manner; and a data driver and a scan driver for switching the respective switching elements according to red, green and blue data of the respective pixels, in which the light emitting area of the back-light is divided into a plurality of light emitting areas and the intensity of light to be emitted from each of the divided light emitting areas is adjusted by a back-light control circuit and drive power source so as to compensate for differences in the light transmittance of the liquid crystal panel.

Claims

1. A liquid crystal display device comprising a liquid crystal panel having a plurality of liquid crystal pixels and a plurality of switching elements provided to correspond to said respective liquid crystal pixels;

and a back-light, disposed in a rear face of said liquid crystal panel, for emitting three colored lights in a time-divided manner, for providing a color display by driving said switching elements to be on/off according to data of three colors of said respective liquid crystal pixels, causing said back-light to emit the lights in a time-divided manner in synchronism with the on/off driving and scanning said respective liquid crystal pixels during the emission of the lights in a time-divided manner, said liquid crystal display device being characterized in that a light emitting area of said back-light is divided into a plurality of areas, and the intensity of light to be emitted from each of the divided light emitting areas differs from each other.

2. The liquid crystal display device as set forth in

claim 1

, comprising a switching circuit for switching each of the divided light emitting areas of said back-light to emit light or put out light in synchronism with scanning of each of said liquid crystal pixels.

3. The liquid crystal display device as set forth in

claim 1

, wherein said back-light includes a light source divided into parts corresponding to the respective divided light emitting areas.

4. The liquid crystal display device as set forth in

claim 1

, comprising a control circuit for controlling the intensity of light to be emitted from each of the divided light emitting areas of said back-light in synchronism with scanning of each of said liquid crystal pixels.

5. The liquid crystal display device as set forth in

claim 1

, comprising a control circuit for controlling the intensity of light to be emitted from each of the divided light emitting areas of said back-light according to the light transmittance of each of display areas of said liquid crystal panel corresponding to each of the divided light emitting areas.

6. The liquid crystal display device as set forth in

claim 1

, wherein the light-emitting time of each of said three colored lights is not more than {fraction (1/180)} second.

7. The liquid crystal display device as set forth in

claim 1

, wherein said back-light comprises LEDs for emitting three colored lights, respectively, a diffusing plate for diffusing light emitted by said LEDs, and a light guiding plate for guiding light emitted by said LEDs to one face of said liquid crystal panel.

8. The liquid crystal display device as set forth in

claim 1

, wherein a liquid crystal material of said liquid crystal panel is a ferroelectric liquid crystal material or an antiferroelectric liquid crystal material.

9. The liquid crystal display device as set forth in

claim 2

, wherein said back-light includes a light source divided into parts corresponding to the respective divided light emitting areas.

10. The liquid crystal display device as set forth in

claim 2

, comprising a control circuit for controlling the intensity of light to be emitted from each of the divided light emitting areas of said back-light in synchronism with scanning of each of said liquid crystal pixels.

11. The liquid crystal display device as set forth in

claim 2

, comprising a control circuit for controlling the intensity of light to be emitted from each of the divided light emitting areas of said back-light according to the light transmittance of each of display areas of said liquid crystal panel corresponding to each of the divided light emitting areas.

12. The liquid crystal display device as set forth in

claim 3

, comprising a control circuit for controlling the intensity of light to be emitted from each of the divided light emitting areas of said back-light in synchronism with scanning of each of said liquid crystal pixels.

13. The liquid crystal display device as set forth in

claim 3

, comprising a control circuit for controlling the intensity of light to be emitted from each of the divided light emitting areas of said back-light according to the light transmittance of each of display areas of said liquid crystal panel corresponding to each of the divided light emitting areas.

14. The liquid crystal display device as set forth in

claim 4

, comprising a control circuit for controlling the intensity of light to be emitted from each of the divided light emitting areas of said back-light according to the light transmittance of each of display areas of said liquid crystal panel corresponding to each of the divided light emitting areas.

15. The liquid crystal display device as set forth in

claim 9

, comprising a control circuit for controlling the intensity of light to be emitted from each of the divided light emitting areas of said back-light in synchronism with scanning of each of said liquid crystal pixels.

16. The liquid crystal display device as set forth in

claim 9

, comprising a control circuit for controlling the intensity of light to be emitted from each of the divided light emitting areas of said back-light according to the light transmittance of each of display areas of said liquid crystal panel corresponding to each of the divided light emitting areas.

17. The liquid crystal display device as set forth in

claim 10

, comprising a control circuit for controlling the intensity of light to be emitted from each of the divided light emitting areas of said back-light according to the light transmittance of each of display areas of said liquid crystal panel corresponding to each of the divided light emitting areas.

18. The liquid crystal display device as set forth in

claim 12

, comprising a control circuit for controlling the intensity of light to be emitted from each of the divided light emitting areas of said back-light according to the light transmittance of each of display areas of said liquid crystal panel corresponding to each of the divided light emitting areas.

19. The liquid crystal display device as set forth in

claim 15

, comprising a control circuit for controlling the intensity of light to be emitted from each of the divided light emitting areas of said back-light according to the light transmittance of each of display areas of said liquid crystal panel corresponding to each of the divided light emitting areas.