Display device, driving method of the same, and electronic device

• US 20060038501A1
• Filed: 08/11/2005
• Published: 02/23/2006
• Est. Priority Date: 08/23/2004
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Koyama, Jun, Yamazaki, Shunpei
• Granted Patent: US 8,194,006 B2
• Time in Patent Office: Days
• US Class Current: 315/169.300
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• 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 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3216 using a passive matrix
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3266 Details of drivers for scan electrodes
• CPC Class Codes: G09G 3/3275 Details of drivers for data electrodes

Abstract

A light emitting element has a property that a luminance changes when an environment temperature changes. In view of this, the invention provides a display device which suppresses the influence of variations of a current value supplied to a light emitting element caused by a temperature change. In particular, luminance variations caused by a temperature gradient in a pixel portion due to a heat generated from a source signal line driver circuit are suppressed. In a display device including a gate signal line provided in a row direction, a source signal line provided in a column direction, and a light emitting element in a pixel portion arranged in matrix corresponding to the gate signal line and the source signal line, a column of monitor elements is provided beside the pixel portion, a constant current is supplied to each row of the monitor elements, and a voltage generated at the monitor element for each row of pixels is applied to light emitting elements of the corresponding row.

Claims

1. A display device comprising:

a pixel portion comprising;

a first light emitting element; and

a second light emitting element; and

a voltage source circuit comprising;

a first circuit operationally connected to the first light emitting element; and

a second circuit operationally connected to the second light emitting element,

wherein the first circuit supplies a first voltage to the first light emitting element, and the second circuit supplies a second voltage to the second light emitting element, and

wherein the first voltage is lower than the second voltage, when a temperature of the first element is higher than a temperature of the second element.

2. A display device comprising:

a first signal line driver circuit electrically connected to n first signal lines;

a second signal line driver circuit electrically connected to m second signal lines;

a pixel portion comprising (n×

m) pixels arranged in matrix corresponding to the n first signal lines and the m second signal lines, wherein each of the (n×

m) pixels includes a light emitting element; and

a voltage source circuit comprising;

m monitor elements arranged beside the pixel portion;

i current sources each of which supplies a current to corresponding j monitor elements of the m monitor elements; and

k amplifiers,

wherein each of the k amplifiers generates a first voltage according to a second voltage generated at each of corresponding (m/k) monitor elements,

wherein each of the k amplifiers applies the first voltage to each of (n×

m/k) light emitting elements included in corresponding (m/k) rows of the (n×

m) pixels,

wherein each of n and m is a natural number, and

wherein each of i, j and k is a natural number less or equal to m.

8. The display device according to claim 2,

wherein the first signal line driver circuit is a source signal line driver circuit, and

wherein the second signal line driver circuit is a gate signal line driver circuit.

14. The display device according to claim 2,

wherein each of the (n×

m) pixels further includes a thin film transistor.

20. The display device according to claim 2,

wherein the light emitting element has a layer containing an organic compound sandwiched by a first electrode formed of a part of corresponding one of the n first signal lines and a second electrode formed of a part of corresponding one of the m second signal lines.

26. The display device according to claim 2,

wherein each of the k amplifiers is a voltage follower circuit.

32. The display device according to claim 2,

wherein the pixel portion is formed of pixels with a plurality of color components;

and

wherein the monitor element and the amplifier are provided for each of the color components.

38. The display device according to claim 2,

wherein the m monitor element and the (n×

m) light emitting elements are EL elements.

44. An electronic device having the display device according to claim 2 in a display portion.

3. A display device comprising:

a first signal line driver circuit electrically connected to n first signal lines;

a second signal line driver circuit electrically connected to m second signal lines;

a pixel portion comprising (n×

m) pixels arranged in matrix corresponding to the n first signal lines and the m second signal lines, wherein each of the (n×

m) pixels includes a light emitting element; and

a voltage source circuit comprising;

m monitor elements arranged beside the pixel portion;

i current sources each of which supplies a current to corresponding j monitor elements of the m monitor elements; and

k amplifiers,

wherein each of the k amplifiers generates a first potential according to a second potential generated at each of anodes of corresponding (m/k) monitor elements,

wherein each of the k amplifiers applies the first potential to each of anodes of (n×

m/k) light emitting elements included in corresponding (m/k) rows of the (n×

m) pixels,

wherein each of n and m is a natural number, and

wherein each of i, j and k is a natural number less or equal to m.

9. The display device according to claim 3,

wherein the first signal line driver circuit is a source signal line driver circuit, and

wherein the second signal line driver circuit is a gate signal line driver circuit.

15. The display device according to claim 3,

wherein each of the (n×

m) pixels further includes a thin film transistor.

21. The display device according to claim 3,

wherein the light emitting element has a layer containing an organic compound sandwiched by a first electrode formed of a part of corresponding one of the n first signal lines and a second electrode formed of a part of corresponding one of the m second signal lines.

27. The display device according to claim 3,

wherein each of the k amplifiers is a voltage follower circuit.

33. The display device according to claim 3,

wherein the pixel portion is formed of pixels with a plurality of color components;

and

wherein the monitor element and the amplifier are provided for each of the color components.

39. The display device according to claim 3,

wherein the m monitor element and the (n×

m) light emitting elements are EL elements.

45. An electronic device having the display device according to claim 3 in a display portion.

4. A display device comprising:

a first signal line driver circuit electrically connected to n first signal lines;

a second signal line driver circuit electrically connected to m second signal lines;

a pixel portion comprising (n×

m) pixels arranged in matrix corresponding to the n first signal lines and the m second signal lines, wherein each of the (n×

m) pixels includes a light emitting element; and

a voltage source circuit comprising;

m monitor elements arranged beside the pixel portion;

i current sources each of which supplies a current to corresponding j monitor elements of the m monitor elements; and

k amplifiers,

wherein each of the k amplifiers generates a first potential according to a second potential generated at each of anodes of corresponding (m/k) monitor elements,

wherein each of the k amplifiers applies the first potential to each of anodes of (n×

m/k) light emitting elements included in corresponding (m/k) rows of the (n×

m) pixels,

wherein each of the m monitor elements is connected in parallel to each of n light emitting element included in a corresponding row of (n×

m) pixels,

wherein each of n and m is a natural number, and wherein each of i, j and k is a natural number less or equal to m.

10. The display device according to claim 4,

wherein the first signal line driver circuit is a source signal line driver circuit, and

wherein the second signal line driver circuit is a gate signal line driver circuit.

16. The display device according to claim 4,

wherein each of the (n×

m) pixels further includes a thin film transistor.

22. The display device according to claim 4,

wherein the light emitting element has a layer containing an organic compound sandwiched by a first electrode formed of a part of corresponding one of the n first signal lines and a second electrode formed of a part of corresponding one of the m second signal lines.

28. The display device according to claim 4,

wherein each of the k amplifiers is a voltage follower circuit.

34. The display device according to claim 4,

wherein the pixel portion is formed of pixels with a plurality of color components;

and

wherein the monitor element and the amplifier are provided for each of the color components.

40. The display device according to claim 4,

wherein the m monitor element and the (n×

m) light emitting elements are EL elements.

46. An electronic device having the display device according to claim 4 in a display portion.

5. A display device comprising:

a first signal line driver circuit electrically connected to n first signal lines;

a second signal line driver circuit electrically connected to m second signal lines;

a pixel portion comprising (n×

m) pixels arranged in matrix corresponding to the n first signal lines and the m second signal lines, wherein each of the (n×

m) pixels includes a light emitting element; and

a voltage source circuit comprising;

m monitor elements arranged beside the pixel portion;

m current sources each of which supplies a current to corresponding one of the m monitor elements; and

m amplifiers,

wherein each of the m amplifiers generates a first voltage according to a second voltage generated at corresponding one of the m monitor elements,

wherein each of the m amplifiers applies the first voltage to each of n light emitting elements included in a corresponding row of the (n×

m) pixels, and

wherein each of n and m is a natural number.

11. The display device according to claim 5,

wherein the first signal line driver circuit is a source signal line driver circuit, and

wherein the second signal line driver circuit is a gate signal line driver circuit.

17. The display device according to claim 5,

wherein each of the (n×

m) pixels further includes a thin film transistor.

23. The display device according to claim 5,

wherein the light emitting element has a layer containing an organic compound sandwiched by a first electrode formed of a part of corresponding one of the n first signal lines and a second electrode formed of a part of corresponding one of the m second signal lines.

29. The display device according to claim 5,

wherein each of the m amplifiers is a voltage follower circuit.

35. The display device according to claim 5,

wherein the pixel portion is formed of pixels with a plurality of color components;

and

wherein the monitor element and the amplifier are provided for each of the color components.

41. The display device according to claim 5,

wherein the m monitor element and the (n×

m) light emitting elements are EL elements.

47. An electronic device having the display device according to claim 5 in a display portion.

6. A display device comprising:

a first signal line driver circuit electrically connected to n first signal lines;

a second signal line driver circuit electrically connected to m second signal lines;

a pixel portion comprising (n×

m) pixels arranged in matrix corresponding to the n first signal lines and the m second signal lines, wherein each of the (n×

m) pixels includes a light emitting element; and

a voltage source circuit comprising;

m monitor elements arranged beside the pixel portion;

m current sources each of which supplies a current to corresponding one of the m monitor elements; and

m amplifiers,

wherein each of the m amplifiers generates a first potential according to a second potential generated at an anode of corresponding one of the m monitor elements,

wherein each of the m amplifiers applies the first potential to each of anodes of n light emitting elements included in a corresponding row of the (n×

m) pixels, and

wherein each of n and m is a natural number.

12. The display device according to claim 6,

wherein the first signal line driver circuit is a source signal line driver circuit, and

wherein the second signal line driver circuit is a gate signal line driver circuit.

18. The display device according to claim 6,

wherein each of the (n×

m) pixels further includes a thin film transistor.

24. The display device according to claim 6,

wherein the light emitting element has a layer containing an organic compound sandwiched by a first electrode formed of a part of corresponding one of the n first signal lines and a second electrode formed of a part of corresponding one of the m second signal lines.

30. The display device according to claim 6,

wherein each of the m amplifiers is a voltage follower circuit.

36. The display device according to claim 6,

wherein the pixel portion is formed of pixels with a plurality of color components;

and

wherein the monitor element and the amplifier are provided for each of the color components.

42. The display device according to claim 6,

wherein the m monitor element and the (n×

m) light emitting elements are EL elements.

48. An electronic device having the display device according to claim 6 in a display portion.

7. A display device comprising:

a first signal line driver circuit electrically connected to n first signal lines;

a second signal line driver circuit electrically connected to m second signal lines;

a pixel portion comprising (n×

m) pixels arranged in matrix corresponding to the n first signal lines and the m second signal lines, wherein each of the (n×

m) pixels includes a light emitting element; and

a voltage source circuit comprising;

m monitor elements arranged beside the pixel portion;

m current sources each of which supplies a current to corresponding one of the m monitor elements; and

m amplifiers,

wherein each of the m amplifiers generates a first potential according to a second potential generated at an anode of corresponding one of the m monitor elements,

wherein each of the m amplifiers applies the first potential to each of anodes of n light emitting elements included in a corresponding row of the (n×

m) pixels,

wherein each of the m monitor elements is connected in parallel to each of n light emitting element included in a corresponding row of (n×

m) pixels, and

wherein each of n and m is a natural number.

13. The display device according to claim 7,

wherein the first signal line driver circuit is a source signal line driver circuit, and

wherein the second signal line driver circuit is a gate signal line driver circuit.

19. The display device according to claim 7,

wherein each of the (n×

m) pixels further includes a thin film transistor.

25. The display device according to claim 7,

wherein the light emitting element has a layer containing an organic compound sandwiched by a first electrode formed of a part of corresponding one of the n first signal lines and a second electrode formed of a part of corresponding one of the m second signal lines.

31. The display device according to claim 7,

wherein each of the m amplifiers is a voltage follower circuit.

37. The display device according to claim 7,

wherein the pixel portion is formed of pixels with a plurality of color components;

and

wherein the monitor element and the amplifier are provided for each of the color components.

43. The display device according to claim 7,

wherein the m monitor element and the (n×

m) light emitting elements are EL elements.

49. An electronic device having the display device according to claim 7 in a display portion.

50. A display device comprising:

a first heat dissipation layer over a first substrate; and

a pixel portion having a light emitting element of which resistance changes by a temperature change and a driver circuit provided in a periphery of the pixel portion over the first heat dissipation layer, and

wherein the pixel portion is sandwiched by the first substrate and a second substrate.

52. The display device according to claim 50,

wherein heat conductivity of the first heat dissipation layer is 10 to 300 W/mK.

54. The display device according to claim 50,

wherein the first heat dissipation layer is a layer containing aluminum nitride.

56. The display device according to claim 50,

wherein the first heat dissipation layer is a layer containing aluminum nitride oxide (AlN_xO_y).

58. The display device according to claim 56,

wherein the aluminum nitride oxide contains 0.1 to 30 atomic % of oxygen (O).

60. The display device according to claim 50,

wherein a second heat dissipation layer is formed over an outer surface of the second substrate.

62. The display device according to claim 60,

wherein the second heat dissipation layer is a metal film.

64. The display device according to claim 62,

wherein the metal film is a film containing copper.

66. An electronic device having the display device according to claim 50 in a display portion.

51. A display device comprising:

a first heat dissipation layer over a first substrate; and

a pixel portion having a light emitting element of which resistance changes by a temperature change and a driver circuit formed of a thin film transistor provided in a periphery of the pixel portion over the first heat dissipation layer,

wherein the pixel portion is sandwiched by the first substrate and a second substrate.

53. The display device according to claim 51,

wherein heat conductivity of the first heat dissipation layer is 10 to 300 W/mK.

55. The display device according to claim 51,

wherein the first heat dissipation layer is a layer containing aluminum nitride.

57. The display device according to claim 51,

wherein the first heat dissipation layer is a layer containing aluminum nitride oxide (AlN_xO_y).

59. The display device according to claim 57,

wherein the aluminum nitride oxide contains 0.1 to 30 atomic % of oxygen (O).

61. The display device according to claim 51,

wherein a second heat dissipation layer is formed over an outer surface of the second substrate.

63. The display device according to claim 61,

wherein the second heat dissipation layer is a metal film.

65. The display device according to claim 63,

wherein the metal film is a film containing copper.

67. An electronic device having the display device according to claim 51 in a display portion.

68. A driving method of a display device comprising:

a pixel portion formed of a plurality of light emitting elements of which resistance changes by a temperature change,

wherein a lower voltage is applied to a light emitting element of a high temperature and a higher voltage is applied to a light emitting element of a low temperature when a temperature gradient occurs in a surface of the pixel portion.