DISPLAY DEVICE AND ELECTRONIC APPARATUS

• US 20110181786A1
• Filed: 05/10/2006
• Published: 07/28/2011
• Est. Priority Date: 05/20/2005
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yanai, Hiromi, Kimura, Hajime, Osame, Mitsuaki, Fukumoto, Ryota, Tanada, Yoshifumi, Koyama, Jun, Yamazaki, Shunpei
• Granted Patent: US 8,059,109 B2
• Time in Patent Office: Days
• US Class Current: 348/671
• CPC Class Codes: G09G 2310/0259 with use of an analog or digital ramp generator in the column driver or in the pixel circuit
• CPC Class Codes: G09G 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/02 Graphics controller able to handle multiple formats, e.g. input or output formats
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/2077 by a combination of two or more gradation control methods
• CPC Class Codes: G09G 3/2092 Details of a display terminals using a flat panel, the details relating to the control arrangement of the display terminal and to the interfaces thereto suitable for both CRT and flat panel G09G5/003; specific for a CRT G09G1/165
• CPC Class Codes: G09G 3/3275 Details of drivers for data electrodes

Abstract

To provide a display device whose display can be recognized even in dark places or under the strong outside light. The display device performs display by controlling the number of gray scales in accordance with the intensity of outside light, which means a display mode can be switched in accordance with the data to be displayed on the display screen. A video signal generation circuit is controlled in each display mode in such a manner that it directly outputs an input video signal with an analog value, outputs a signal with a binary digital value, or outputs a signal with a multivalued digital value. As a result, gray scales displayed in pixels are timely changed. Accordingly, clear images can be displayed while maintaining high visibility in various environments, in the wide range from, for example, dark places or indoors (e.g., under a fluorescent lighting) to outdoors (e.g., under the sunlight).

Claims

1. A display device including a matrix arrangement of a plurality of pixels, comprising:

a source driver;

a gate driver;

a video signal generating circuit comprising a level converter circuit; and

a pixel portion,

wherein the display device displays at least one of a first image in accordance with a first display mode and a second image in accordance with a second display mode in the pixel portion,

wherein the first display mode and the second display mode are switched in accordance with an intensity of outside light in such a manner that an analog signal is supplied to the source driver in the first display mode, while a digital signal is supplied to the source driver in the second display mode,

wherein the video signal generating circuit is configured to supply the analog signal to the source driver by inputting a video signal to a D/A converter in the first display mode, and

wherein the video signal generating circuit is configured to supply the digital signal by outputting a video signal with a most significant bit to the source driver in the second display mode.

5. The display device according to claim 1, wherein the display device is an EL display.

9. An electronic apparatus comprising the display device according to claim 1.

15. The display device according to claim 1, wherein the display device is driven by using an analog gray scale method.

21. The display device according to claim 1, wherein the intensity of outside light is detected by an optical sensor.

39. The display device according to claim 1,

wherein the pixel portion comprises a transistor, and

wherein the transistor is configured to operate in a saturation region in the first display mode and to operate in a linear region in the second display mode.

2. A display device including a matrix arrangement of a plurality of pixels, comprising:

a source driver;

a gate driver;

a video signal generating circuit comprising a level converter circuit; and

a pixel portion,

wherein the display device displays at least one of a first image in accordance with a first display mode and a second image in accordance with a second display mode in the pixel portion,

wherein the first display mode and the second display mode are switched in accordance with an intensity of outside light in such a manner that an analog signal is supplied to the source driver to be supplied to the pixel portion in the first display mode, while a digital signal is supplied to the source driver to be supplied to the pixel portion in the second display mode,

wherein the video signal generating circuit is configured to supply the analog signal to the source driver by inputting a video signal to a D/A converter in the first display mode, and

wherein the video signal generating circuit is configured to supply the digital signal by outputting a video signal with a most significant bit to the source driver in the second display mode.

6. The display device according to claim 2, wherein the display device is an EL display.

10. An electronic apparatus comprising the display device according to claim 2.

16. The display device according to claim 2, wherein the display device is driven by using an analog gray scale method.

22. The display device according to claim 2, wherein the intensity of outside light is detected by an optical sensor.

40. The display device according to claim 2,

wherein the pixel portion comprises a transistor, and

wherein the transistor is configured to operate in a saturation region in the first display mode and to operate in a linear region in the second display mode.

3. A display device including a matrix arrangement of a plurality of pixels, comprising:

a source driver;

a gate driver;

a video signal generating circuit comprising a level converter circuit; and

a pixel portion,

wherein the display device displays at least one of a first image in accordance with a first display mode and a second image in accordance with a second display mode in the pixel portion,

wherein the video signal generating circuit is configured to supply an analog signal to the source driver by inputting a video signal to a D/A converter in the first display mode,

wherein the video signal generating circuit is configured to supply a digital signal by outputting a video signal with a most significant bit to the source driver in the second display mode, and

wherein the first display mode and the second display mode are switched in accordance with an intensity of outside light.

7. The display device according to claim 3, wherein the display device is an EL display.

11. An electronic apparatus comprising the display device according to claim 3.

17. The display device according to claim 3, wherein the display device is driven by using an analog gray scale method.

23. The display device according to claim 3, wherein the intensity of outside light is detected by an optical sensor.

27. The display device according to claim 23, further comprising a controller configured to control the video signal generating circuit based on an output of the optical sensor.

31. The display device according to claim 27, further comprising an amplifier configured to amplify an electric signal output from the optical sensor and to supply the amplified signal to the controller.

35. The display device according to claim 3, further comprising:

a display mode controlling circuit; and

a binarization circuit.

37. The display device according to claim 3, further comprising:

a display mode control circuit.

41. The display device according to claim 3,

wherein the pixel portion comprises a transistor, and

wherein the transistor is configured to operate in a saturation region in the first display mode and to operate in a linear region in the second display mode.

4. A display device including a matrix arrangement of a plurality of pixels, comprising:

a source driver;

a gate driver;

a video signal generating circuit comprising a level converter circuit; and

a pixel portion,

wherein the display device displays at least one of a first image in accordance with a first display mode and a second image in accordance with a second display mode in the pixel portion,

wherein the video signal generating circuit supplies is configured to supply an analog signal to the source driver to be supplied to the pixel portion by inputting a video signal to a D/A converter in the first display mode,

wherein the video signal generating circuit is configured to supply a digital signal by outputting a video signal with a most significant bit to the source driver to be supplied to the pixel portion in the second display mode, and

wherein the first display mode and the second display mode are switched in accordance with an intensity of outside light.

8. The display device according to claim 4, wherein the display device is an EL display.

12. An electronic apparatus comprising the display device according to claim 4.

18. The display device according to claim 4, wherein the display device is driven by using an analog gray scale method.

24. The display device according to claim 4, wherein the intensity of outside light is detected by an optical sensor.

28. The display device according to claim 24, further comprising a controller configured to control the video signal generating circuit based on an output of the optical sensor.

32. The display device according to claim 28, further comprising an amplifier configured to amplify an electric signal output from the optical sensor and to supply the amplified signal to the controller.

36. The display device according to claim 4, further comprising:

a display mode controlling circuit; and

a binarization circuit.

38. The display device according to claim 4, further comprising:

a display mode control circuit.

42. The display device according to claim 4,

wherein the pixel portion comprises a transistor, and

wherein the transistor is configured to operate in a saturation region in the first display mode and to operate in a linear region in the second display mode.

13. A driving method of a display device including a matrix arrangement of a plurality of pixels, a source driver, and a gate driver, comprising the steps of:

switching between a first display mode and a second display mode in accordance with an intensity of outside light;

supplying an analog signal to the source driver by inputting a video signal to a D/A converter in the first display mode; and

supplying a digital signal to the source driver by outputting a video signal with a most significant bit through a level converter circuit in the second display mode.

19. The driving method according to claim 13, wherein the display device is driven by using an analog gray scale method.

25. The driving method according to claim 13, wherein the intensity of outside light is detected by an optical sensor.

29. The driving method according to claim 25, further comprising controlling a video signal generating circuit based on an output of the optical sensor by a controller.

33. The driving method according to claim 29, further comprising:

amplifying an electric signal output from the optical sensor by an amplifier; and

supplying the amplified signal to the controller.

43. The driving method according to claim 13,

wherein each of the plurality of pixels comprises a transistor,

wherein the transistor operates in a saturation region in the first display mode, and

wherein the transistor operates in a linear region in the second display mode

14. A driving method of a display device including a matrix arrangement of a plurality of pixels in a pixel portion, a source driver, and a gate driver, comprising the steps of:

switching between a first display mode and a second display mode in accordance with an intensity of outside light;

supplying an analog signal to the source driver to be supplied to the pixel portion by inputting a video signal to a D/A converter in the first display mode; and

supplying a digital signal to the source driver to be supplied to the pixel portion by outputting a video signal with a most significant bit through a level converter circuit in the second display mode.

20. The driving method according to claim 14, wherein the display device is driven by using an analog gray scale method.

26. The driving method according to claim 14, wherein the intensity of outside light is detected by an optical sensor.

30. The driving method according to claim 26, further comprising controlling a video signal generating circuit based on an output of the optical sensor by a controller.

34. The driving method according to claim 30, further comprising:

amplifying an electric signal output from the optical sensor by an amplifier; and

supplying the amplified signal to the controller.

44. The driving method according to claim 14,

wherein each of the plurality of pixels comprises a transistor,

wherein the transistor operates in a saturation region in the first display mode, and

wherein the transistor operates in a linear region in the second display mode.