LIQUID CRYSTAL DISPLAY DEVICE AND ELECTRONIC APPARATUS

• US 20060262066A1
• Filed: 05/09/2006
• Published: 11/23/2006
• Est. Priority Date: 05/20/2005
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Koyama, Jun, Kimura, Hajime, Fukumoto, Ryota, Tanada, Yoshifumi, Osame, Mitsuaki, Yamazaki, Shunpei, Yanai, Hiromi
• Granted Patent: US 9,159,291 B2
• Time in Patent Office: Days
• US Class Current: 345/98
• CPC Class Codes: G09G 2310/0294 Details of sampling or holding circuits arranged for use in a driver for data electrodes
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2340/0428 Gradation resolution change
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2370/08 Details of image data interface between the display device controller and the data line driver circuit
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

The liquid crystal display device performs display by changing the number of gray scales depending on external light intensity, and switches the display mode in accordance with a content to be displayed on a display. By controlling a display mode-specific video signal generation circuit depending on external light intensity, an inputted video signal is outputted as an analog value, is outputted with a digital value of a binary, or is outputted with a multiple digital value. As a result, display gradation of a pixel changes timely. Accordingly, a clear image can be displayed. For example, a display device which secures visibility can be obtained in a wide range from under fluorescent light in a dark place or indoor to under outdoor sunlight.

Claims

1. A liquid crystal display device comprising:

a plurality of pixels provided in matrix, each of which comprises a liquid crystal element;

a gate driver for supplying gate signals to the plurality of pixels;

a source driver for supplying any one of analog video signals and digital video signals to the plurality of pixels; and

a display mode-specific video signal generation circuit,

wherein the display mode-specific video signal generation circuit supplies the analog video signals to the source driver in a first display mode,

wherein the display mode-specific video signal generation circuit supplies the digital video signals to the source driver in a second display mode, and

wherein the first display mode and the second display mode are switched according to an external light intensity.

2. The liquid crystal display device according to claim 1, further comprising a DA converter for supplying the analog video signals.

3. The liquid crystal display device according to claim 1, wherein the digital video signals are binary signals.

4. The liquid crystal display device according to claim 1, wherein the digital video signals are multiple-valued signals.

5. An electronic apparatus comprising the liquid crystal display device according to claim 1.

6. A liquid crystal display device comprising:

a substrate;

a plurality of liquid crystal elements over the substrate, provided in matrix;

a gate driver over the substrate;

a source driver over the substrate;

a display mode-specific video signal generation circuit comprising;

an output terminal a electrically connected to the source driver;

a video signal input terminal;

a first switch;

a second switch, wherein the first switch and the second switch are connected in parallel between the output terminal and the video signal input terminal;

a circuit for converting analog video signals to digital video signals, wherein the circuit and the second switch are connected in series between the output terminal and the video signal input terminal; and

a display mode control circuit electrically connected to a control terminal of each of the first switch and the second switch;

a controller electrically connected to the display mode control circuit; and

a optical sensor electrically connected to the controller.

7. The liquid crystal display device according to claim 6, further comprising a DA converter electrically connected to the video signal input terminal.

8. The liquid crystal display device according to claim 6, wherein the optical sensor is provided over the substrate.

9. The liquid crystal display device according to claim 6, wherein the optical sensor is electrically connected to the controller via an amplifier.

10. The liquid crystal display device according to claim 6, wherein the optical sensor comprises a plurality of sensor elements.

11. The liquid crystal display device according to claim 6, wherein the optical sensor comprises a photoelectric converter.

12. An electronic apparatus comprising the liquid crystal display device according to claim 6.

13. A liquid crystal display device comprising:

a substrate;

a plurality of liquid crystal elements over the substrate, provided in matrix;

a gate driver over the substrate;

a source driver over the substrate;

a display mode-specific video signal generation circuit comprising;

an output terminal a electrically connected to the source driver;

a video signal input terminal;

a first switch;

a second switch;

a third switch, wherein the first switch, the second switch and the third switch are connected in parallel between the output terminal and the video signal input terminal;

a binarization circuit, wherein the binarization circuit and the second switch are connected in series between the output terminal and the video signal input terminal;

a multiple-valued circuit, wherein the multiple-valued circuit and the third switch are connected in series between the output terminal and the video signal input terminal; and

a display mode control circuit electrically connected to a control terminal of each of the first switch, the second switch and the third switch;

a controller electrically connected to the display mode control circuit; and

a optical sensor electrically connected to the controller.

14. The liquid crystal display device according to claim 13, further comprising a DA converter electrically connected to the video signal input terminal.

15. The liquid crystal display device according to claim 13, wherein the optical sensor is provided over the substrate.

16. The liquid crystal display device according to claim 13, wherein the optical sensor is electrically connected to the controller via an amplifier.

17. The liquid crystal display device according to claim 13, wherein the optical sensor comprises a plurality of sensor elements.

18. The liquid crystal display device according to claim 13, wherein the optical sensor comprises a photoelectric converter.

19. An electronic apparatus comprising the liquid crystal display device according to claim 13.

20. A method for driving a liquid crystal display device comprising the steps of:

detecting an external light intensity;

selecting any one of a first display mode and a second display mode, according to the external light intensity;

supplying an analog video signal to a source driver in the first display mode;

supplying a digital video signal to the source driver in the second display mode;

changing a voltage applied to a liquid crystal element, according to supplied one of the analog video signal and the digital video signal.

21. The liquid crystal display device according to claim 20, wherein the analog video signal is a signal converted from an original digital signal.

22. The liquid crystal display device according to claim 20, wherein the detected external light intensity is converted to an electric signal.

23. The liquid crystal display device according to claim 22, wherein the electronic signal is amplified.

24. An electronic apparatus comprising the liquid crystal display device according to claim 20.

25. A method for driving a liquid crystal display device comprising the steps of:

detecting an external light intensity;

selecting any one of a first display mode, a second display mode and a third display mode, according to the external light intensity;

supplying an analog video signal to a source driver in the first display mode;

supplying a multiple value video signal to the source driver in the second display mode;

supplying a binary video signal to the source driver in the third display mode;

changing a voltage applied to a liquid crystal element, according to supplied one of the analog video signal, the multiple value video signal and the binary video signal.

26. The liquid crystal display device according to claim 25, wherein the analog video signal is a signal converted from an original digital signal.

27. The liquid crystal display device according to claim 25, wherein the detected external light intensity is converted to an electric signal.

28. The liquid crystal display device according to claim 27, wherein the electronic signal is amplified.

29. An electronic apparatus comprising the liquid crystal display device according to claim 25.