DISPLAY DEVICE AND ELECTRONIC DEVICE

• US 20060273999A1
• Filed: 05/16/2006
• Published: 12/07/2006
• 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, Osame, Mitsuaki, Fukumoto, Ryota, Tanada, Yoshifumi, Yamazaki, Shunpei, Yanai, Hiromi
• Granted Patent: US 7,636,078 B2
• Time in Patent Office: Days
• US Class Current: 345/81
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2310/0283 Arrangement of drivers for different directions of scanning
• CPC Class Codes: G09G 2310/0289 Details of voltage level shifters arranged for use in a driving circuit
• 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 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/001 using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background slide projectors per se G03B23/00 = 42 HP
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: H10K 59/1216 the pixel elements being capacitors
• CPC Class Codes: H10K 59/13 comprising photosensors that control luminance

Abstract

It is an object of the present invention to provide a display device in which images can be seen under a dark place to intense external light. In the display device, display is performed by changing the gray scale number depending on external light intensity, and display modes can be switched depending on contents displayed on the screen. An analog mode and a digital mode are switched depending on external light intensity. In an analog digital switching circuit, when a video signal is an analog value, a signal is outputted to a pixel array without any change and, when the video signal is a digital value, the signal is outputted to a circuit that performs a digital operation such as a latch circuit. Consequently, display gray scales of a pixel are changed appropriately. Accordingly, a clear image can be displayed. For example, it is possible to ensure visibility in a wide range of a dark place or under indoor florescent light to outdoor sun light.

Claims

1. A display device comprising:

a plurality of pixels formed over a substrate; and

a source driver and a gate driver formed over the substrate,

wherein the source driver includes a circuit that supplies an either signal of a digital value or an analog value to the plurality of pixels depending on an external light intensity.

2. A display device according to claim 1, wherein the external light is detected by a photosensor.

3. A display device according to claim 1, wherein the plurality of pixels are arranged in matrix.

4. A display device according to claim 1, wherein the display device is an EL display device.

5. A display device according to claim 1, wherein the display device is incorporated in at least one selected from the group consisting of a video camera, a digital camera, a computer, an image reproducing device, a goggle type display, and a cellular phone.

6. A display device comprising:

a plurality of pixels formed over a substrate,

wherein the display device includes at least a first display mode and a second display mode,

wherein an analog signal is supplied to the plurality of pixels in the first display mode,

wherein a digital signal is supplied to the plurality of pixels in the second display mode, and

wherein the first and the second display modes are switched depending on an external light intensity.

7. A display device according to claim 6, wherein the external light is detected by a photosensor.

8. A display device according to claim 6, wherein the plurality of pixels are arranged in matrix.

9. A display device according to claim 6, wherein the display device is an EL display device.

10. A display device according to claim 6, wherein the display device is incorporated in at least one selected from the group consisting of a video camera, a digital camera, a computer, an image reproducing device, a goggle type display, and a cellular phone.

11. A display device comprising:

a plurality of pixels formed over a substrate, each of the plurality of pixels including a light-emitting element,

wherein the display device includes at least a first display mode and a second display mode,

wherein an analog signal is supplied to the plurality of pixels in the first display mode,

wherein a digital signal is supplied to the plurality of pixels in the second display mode,

wherein the display modes are switched depending on an external light intensity, and

wherein a voltage supplied to the light-emitting element is different in the first and the second display modes.

12. A display device according to claim 11, wherein the external light is detected by a photosensor.

13. A display device according to claim 11, wherein the plurality of pixels are arranged in matrix.

14. A display device according to claim 11, wherein the display device is an EL display device.

15. A display device according to claim 11, wherein the display device is incorporated in at least one selected from the group consisting of a video camera, a digital camera, a computer, an image reproducing device, a goggle type display, and a cellular phone.

16. A display device comprising:

a plurality of pixels formed over a substrate, each of the plurality of pixels including a light-emitting element and a transistor,

wherein the display device includes at least a first display mode and a second display mode,

wherein a first electrode of the light-emitting element and one of source and drain electrodes of the transistor are electrically connected with each other,

wherein an analog signal is supplied to the plurality of pixels in the first display mode,

wherein a digital signal is supplied to the plurality of pixels in the second display mode,

wherein the first and the second display modes are switched depending on an external light intensity, and

wherein a voltage between a second electrode of the light-emitting element and the other of the source and drain electrodes of the transistor is different in the first and the second display modes.

17. A display device according to claim 16, wherein the external light is detected by a photosensor.

18. A display device according to claim 16, wherein the plurality of pixels are arranged in matrix.

19. A display device according to claim 16, wherein the display device is an EL display device.

20. A display device according to claim 16, wherein the display device is incorporated in at least one selected from the group consisting of a video camera, a digital camera, a computer, an image reproducing device, a goggle type display, and a cellular phone.

21. A display device comprising:

a photosensor;

a display mode switching control circuit electrically connected to the photosensor;

a plurality of pixels; and

a source driver comprising a shift register and an analog digital switching circuit, wherein a video signal is input to the analog digital switching circuit.

22. A display device according to claim 21, wherein the plurality of pixels are arranged in matrix.

23. A display device according to claim 21, wherein the display device is an EL display device.

24. A display device according to claim 21, wherein the display device is incorporated in at least one selected from the group consisting of a video camera, a digital camera, a computer, an image reproducing device, a goggle type display, and a cellular phone.

25. A display device comprising:

a photosensor;

a display mode switching control circuit electrically connected to the photosensor;

a plurality of pixels; and

a source driver comprising a shift register and an analog digital switching circuit, wherein a video signal is input to the analog digital switching circuit, and

wherein the display mode switching control circuit supplies a display mode control signal to the analog digital switching circuit.

26. A display device according to claim 25, wherein the plurality of pixels are arranged in matrix.

27. A display device according to claim 25, wherein the display device is an EL display device.

28. A display device according to claim 25, wherein the display device is incorporated in at least one selected from the group consisting of a video camera, a digital camera, a computer, an image reproducing device, a goggle type display, and a cellular phone.

29. A driving method of a display device comprising a plurality of pixels, a source driver and a gate driver, each formed over a substrate, the method comprising:

supplying an either signal of a digital value or an analog value to the plurality of pixels depending on an external light intensity.

30. A driving method according to claim 29, wherein the external light is detected by a photosensor.

31. A driving method according to claim 29, wherein the plurality of pixels are arranged in matrix.

32. A driving method according to claim 29, wherein the display device is an EL display device.

33. A driving method according to claim 29, wherein the display device is incorporated in at least one selected from the group consisting of a video camera, a digital camera, a computer, an image reproducing device, a goggle type display, and a cellular phone.

34. A driving method of a display device comprising a plurality of pixels, a source driver and a gate driver, each formed over a substrate, the method comprising:

switching a display mode between a first display mode and a second display mode depending on an external light,

wherein an analog signal is supplied to the plurality of pixels in the first display mode and a digital signal is supplied to the plurality of pixels in the second display mode

35. A driving method according to claim 34, wherein the external light is detected by a photosensor.

36. A driving method according to claim 34, wherein the plurality of pixels are arranged in matrix.

37. A driving method according to claim 34, wherein the display device is an EL display device.

38. A driving method according to claim 34, wherein the display device is incorporated in at least one selected from the group consisting of a video camera, a digital camera, a computer, an image reproducing device, a goggle type display, and a cellular phone.