Spontaneous light emitting device and driving method thereof

• US 20020033783A1
• Filed: 09/07/2001
• Published: 03/21/2002
• Est. Priority Date: 09/08/2000
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Koyama, Jun
• Granted Patent: US 7,053,874 B2
• Time in Patent Office: Days
• US Class Current: 345/82
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/048 using evaluation of the usage time
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/30 using electroluminescent panels
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3275 Details of drivers for data electrodes

Abstract

A counter 102 counts the accumulated lighting time or the accumulated lighting time and the intensity of lighting of each pixel by a first image signal 101A and stores them in a volatile memory 103 or a nonvolatile memory 104. A correction circuit 105 corrects the first image signal based on the correction data stored previously in a correction data storage section 106 in accordance with the degree of the degradation of each spontaneous light emitting element by the use of the accumulated lighting time or the accumulated lighting time and the intensity of lighting, and produces a second mage signal 101B. By the second image signal 101B, a display unit 107 can provide a uniform screen having no variation in luminance even if the light emitting elements in a part of the pixels are degraded.

Claims

1. A spontaneous light emitting device to which an image signal is inputted to display an image, the device comprising:

a unit for detecting the accumulated lighting time of each pixel;

a unit for storing the accumulated lighting time; and

a unit for correcting the image signal according to the stored accumulated lighting time,

wherein the image is displayed by the use of the corrected image signal.

2. A device according to claim 1, wherein a correction of addition relative to the image signal written in the pixel having the spontaneous light emitting element which is not degraded is made to the image signal written in the pixel having the spontaneous light emitting element which is degraded.

3. A device according to claim 1, wherein a correction of subtraction relative to the image signal written in the pixel having the spontaneous light emitting element which is most degraded is made to the image signal written in the pixel having the spontaneous light emitting element which is a little degraded or the pixel having the spontaneous light emitting element which is not degraded.

4. A device according to claim 1, wherein the memory unit or the memory circuit is a static type memory circuit (SRAM).

5. A device according to claim 1, wherein the memory unit or the memory circuit is a dynamic type memory circuit (DRAM).

6. A device according to claim 1, wherein the memory unit or the memory circuit is a ferroelectric memory circuit (FeRAM).

7. A device according to claim 1, wherein the memory unit or the memory circuit is an electrically erasable programmable read-only, nonvolatile memory (EEPROM).

8. A device according to claim 1, wherein the detection unit, the memory unit, and the correction unit are constituted by the external circuits of the spontaneous light emitting device.

9. A device according to claim 1, wherein the detection unit, the memory unit, and the correction unit are formed on the same insulator as the spontaneous light emitting device.

52. An electronic gear using a spontaneous light emitting device according to claim 1.

10. A spontaneous light emitting device to which an image signal is inputted to display an image, the device comprising:

a unit for detecting the accumulated lighting time and the intensity of lighting of each pixel;

a unit for storing the accumulated lighting time and the intensity of lighting; and

a unit for correcting the image signal according to the accumulated lighting time and the intensity of lighting, which are stored,

wherein the image is displayed by the use of the corrected image signal.

11. A device according to claim 10, wherein a correction of addition relative to the image signal written in the pixel having the spontaneous light emitting element which is not degraded is made to the image signal written in the pixel having the spontaneous light emitting element which is degraded.

12. A device according to claim 10, wherein a correction of sub traction relative to the image signal written in the pixel having the spontaneous light emitting element which is most degraded is made to the image signal written in the pixel having the spontaneous light emitting element which is a little degraded or the pixel having the spontaneous light emitting element which is not degraded.

13. A device according to claim 10, wherein the memory unit or the memory circuit is a static type memory circuit (SRAM).

14. A device according to claim 10, wherein the memory unit or the memory circuit is a dynamic type memory circuit (DRAM).

15. A device according to claim 10, wherein the memory unit or the memory circuit is a ferroelectric memory circuit (FeRAM).

16. A device according to claim 10, wherein the memory unit or the memory circuit is an electrically erasable programmable read-only, nonvolatile memory (EEPROM).

17. A device according to claim 10, wherein the detection unit, the memory unit, and the correction unit are constituted by the external circuits of the spontaneous light emitting device.

18. A device according to claim 10, wherein the detection unit, the memory unit, and the correction unit are formed on the same insulator as the spontaneous light emitting device.

20. A device according to claim 19, wherein a correction of addition relative to the image signal written in the pixel having the spontaneous light emitting element which is not degraded is made to the image signal written in the pixel having the spontaneous light emitting element which is degraded.

21. A device according to claim 19, wherein a correction of subtraction relative to the image signal written in the pixel having the spontaneous light emitting element which is most degraded is made to the image signal written in the pixel having the spontaneous light emitting element which is a little degraded or the pixel having the spontaneous light emitting element which is not degraded.

22. A device according to claim 19, wherein the memory unit or the memory circuit is a static type memory circuit (SRAM).

23. A device according to claim 19, wherein the memory unit or the memory circuit is a dynamic type memory circuit (DRAM).

24. A device according to claim 19, wherein the memory unit or the memory circuit is a ferroelectric memory circuit (FeRAM).

25. A device according to claim 19, wherein the memory unit or the memory circuit is an electrically erasable programmable read-only, nonvolatile memory (EEPROM).

26. A device according to claim 19, wherein the counter section, the memory circuit, and the signal correction section are constituted by the external circuits of the spontaneous light emitting device.

27. A device according to claim 19, wherein the counter section, the memory circuit, and the signal correction section are formed on the same insulator as the spontaneous light emitting device.

28. A device according to claim 19, wherein the spontaneous light emitting device is an EL display.

29. A device according to claim 19, wherein the spontaneous light emitting device is a PDP display.

30. A device according to claim 19, wherein the spontaneous light emitting device is a FED display.

53. An electronic gear using a spontaneous light emitting device according to claim 10.

54. An electronic gear using a spontaneous light emitting device according to claim 19.

19. A spontaneous light emitting device to which an image signal is inputted to display an image, the device comprising:

a degradation correction unit including;

a counter section for sampling a first image signal and periodically detecting the lighting time of a spontaneous light emitting element of each pixel;

a memory circuit for accumulating and storing the lighting time of the spontaneous light emitting element of each pixel, which is detected by the counter section; and

a signal correction section for correcting the first image signal according to the accumulated lighting time of the spontaneous light emitting element of each pixel, which is accumulated and stored in the memory circuit, and for outputting a second image signal; and

a display unit for displaying the image by the second image signal.

31. A spontaneous light emitting device to which an image signal is inputted to display an image, the device comprising:

a degradation correction unit including;

a counter section for sampling a first image signal and periodically detecting the lighting time and the intensity of lighting of a spontaneous light emitting element of each pixel;

a memory circuit for accumulating and storing the lighting time and the intensity of lighting of the spontaneous light emitting element of each pixel, which are detected by the counter section; and

a signal correction section for correcting the first image signal according to the accumulated lighting time and the intensity of lighting of the spontaneous light emitting element of each pixel, which are accumulated and stored in the memory circuit, and for outputting a second image signal; and

a display unit for displaying the image by the second image signal.

32. A device according to claim 31, wherein the spontaneous light emitting device for displaying an n-bit gradation (n:

natural number, n≧

2) further comprises a driving circuit for performing an (n+m)- bit signal processing (m;

natural number), and wherein the image signal written in the pixel having a spontaneous light emitting element, which is not degraded, displays the gradation by an n-bit image signal, and wherein a correction of gradation is made, by the use of an m-bit image signal, to the image signal written in the pixel having a spontaneous light emitting element, which is degraded, whereby the luminance of the spontaneous light emitting element which is not degraded is made equal to that of the spontaneous light emitting element which is degraded.

33. A device according to claim 31, wherein a correction of addition relative to the image signal written in the pixel having the spontaneous light emitting element which is not degraded is made to the image signal written in the pixel having the spontaneous light emitting element which is degraded.

34. A device according to claim 31, wherein a correction of subtraction relative to the image signal written in the pixel having the spontaneous light emitting element which is most degraded is made to the image signal written in the pixel having the spontaneous light emitting element which is a little degraded or the pixel having the spontaneous light emitting element which is not degraded.

35. A device according to claim 31, wherein the memory unit or the memory circuit is a static type memory circuit (SRAM).

36. A device according to claim 31, wherein the memory unit or the memory circuit is a dynamic type memory circuit (DRAM).

37. A device according to claim 31, wherein the memory unit or the memory circuit is a ferroelectric memory circuit (FeRAM).

38. A device according to claim 31, wherein the memory unit or the memory circuit is an electrically erasable programmable read-only, nonvolatile memory (EEPROM).

39. A device according to claim 31, wherein the counter section, the memory circuit, and the signal correction section are constituted by the external circuits of the spontaneous light emitting device.

40. A device according to claim 31, wherein the counter section, the memory circuit, and the signal correction section are formed on the same insulator as the spontaneous light emitting device.

41. A device according to claim 31, wherein the spontaneous light emitting device is an EL display.

42. A device according to claim 31, wherein the spontaneous light emitting device is a PDP display.

43. A device according to claim 31, wherein the spontaneous light emitting device is a FED display.

55. An electronic gear using a spontaneous light emitting device according to claim 31.

44. A method for driving a spontaneous light emitting device to which an image signal is inputted to display an image, the method comprising the steps of:

sampling a first image signal and periodically detecting, by a counter section, the lighting time of a spontaneous light emitting element of each pixel;

accumulating and storing, by a memory circuit, the lighting time of the spontaneous light emitting element of each pixel, which is detected by the counter section; and

correcting the first image signal and outputting a second image signal, by a signal correction section, according to the accumulated lighting time of the spontaneous light emitting element of each pixel, which is accumulated and stored by the memory circuit; and

displaying the image by the second image signal.

45. A method according to claim 44, wherein the spontaneous light emitting device for displaying an n- bit gradation (n:

natural number, n≧

2) further comprises a driving circuit for performing an (n+m)-bit signal processing, and wherein the image signal written in the pixel having a spontaneous light emitting element which is not degraded displays the gradation by an n-bit image signal, and wherein a correction of gradation is made to the image signal written in the pixel having an spontaneous light emitting element which is degraded by an m-bit signal, whereby the luminance of the spontaneous light emitting element which is not degraded is made equal to that of the spontaneous light emitting element which is degraded.

46. A method according to claim 44, wherein a correction of addition relative to the image signal written in the pixel having the spontaneous light emitting element which is not degraded is made to the image signal written in the pixel having the spontaneous light emitting element which is degraded.

47. A method according to claim 44, wherein a correction of subtraction relative to the image signal written in the pixel having the spontaneous light emitting element which is most degraded is made to the image signal written in the pixel having the spontaneous light emitting element which is little degraded or the pixel having the spontaneous light emitting element which is not degraded.

49. A method according to claim 48, wherein the spontaneous light emitting device for displaying an n-bit gradation (n:

natural number, n≧

2) further comprises a driving circuit for performing an (n+m)-bit signal processing, and wherein the image signal written in the pixel having a spontaneous light emitting element which is not degraded displays the gradation by an n-bit image signal, and wherein a correction of gradation is made to the image signal written in the pixel having an spontaneous light emitting element which is degraded by an m-bit signal, whereby the luminance of the spontaneous light emitting element which is not degraded is made equal to that of the spontaneous light emitting element which is degraded.

50. A method according to claim 48, wherein a correction of addition relative to the image signal written in the pixel having the spontaneous light emitting element which is not degraded is made to the image signal written in the pixel having the spontaneous light emitting element which is degraded.

51. A method according to claim 48, wherein a correction of subtraction relative to the image signal written in the pixel having the spontaneous light emitting element which is most degraded is made to the image signal written in the pixel having the spontaneous light emitting element which is little degraded or the pixel having the spontaneous light emitting element which is not degraded.

56. An electronic gear using a method for driving a spontaneous light emitting device according to claim 44.

48. A method for driving a spontaneous light emitting device to which an image signal is inputted to display an image, the method comprising the steps of:

sampling a first image signal and periodically detecting, by a counter section, the lighting time and the intensity of lighting of a spontaneous light emitting element of each pixel;

accumulating and storing, by a memory circuit, the lighting time and the intensity of lighting of the spontaneous light emitting element of each pixel, which are detected by the counter section; and

correcting the first image signal and outputting a second image signal, by a signal correction section, according to the accumulated lighting time and the intensity of lighting of the spontaneous light emitting element of each pixel, which are accumulated and stored in the memory circuit; and

displaying the image by the second image signal.

57. An electronic gear using a method for driving a spontaneous light emitting device according to claim 48.