Liquid crystal display device

• US 7,773,182 B2
• Filed: 12/01/2006
• Issued: 08/10/2010
• Est. Priority Date: 12/05/2005
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kimura, Hajime, Uochi, Hideki
• Primary Examiner(s): WONG, TINA MEI SENG
• Application Number:
  US11/566,005
• Publication Number:
  US 20070126969A1
• Time in Patent Office: 1,348 Days
• Field of Search: None
• US Class Current: 349/141
• CPC Class Codes: G02F 1/133345 Insulating layers G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/134372 for fringe field switching [FFS] where the common electrode is not patterned
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/136209 Light shielding layers, e.g. black matrix, incorporated in the active matrix substrate, e.g. structurally associated with the switching element
• CPC Class Codes: G02F 1/136222 Colour filters incorporated in the active matrix substrate
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: G02F 1/136286 Wiring, e.g. gate line, drain line
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 2201/121 common or background
• CPC Class Codes: G02F 2201/123 pixel
• CPC Class Codes: G02F 2201/124 interdigital

Abstract

It is an object of the present invention to apply a sufficient electrical field to a liquid crystal material in a horizontal electrical field liquid crystal display device typified by an FFS type. In a horizontal electrical field liquid crystal display, an electrical field is applied to a liquid crystal material right above a common electrode and a pixel electrode using plural pairs of electrodes rather than one pair of electrodes. One pair of electrodes includes a comb-shaped common electrode and a comb-shaped pixel electrode. Another pair of electrodes includes a common electrode provided in a pixel portion and the comb-shaped pixel electrode.

Claims

1. A liquid crystal display device, comprising:

a first common electrode;

an insulating layer provided over the first common electrode;

a pixel electrode and a second common electrode provided over the insulating layer; and

a liquid crystal material provided over the pixel electrode and the second common electrode,

wherein tilting of the liquid crystal material is controlled by an electrical field between the pixel electrode and the first common electrode, and by an electrical field between the pixel electrode and the second common electrode.

2. The liquid crystal display device, according to claim 1, wherein the pixel electrode is comb-shaped.

3. The liquid crystal display device according to claim 1, wherein the first common electrode is comb-shaped.

4. The liquid crystal display device according to claim 1, wherein the second common electrode is comb-shaped.

5. The liquid crystal display device according to claim 1, wherein the pixel electrode is formed of a transparent material.

6. The liquid crystal display device according to claim 1, wherein the first common electrode is formed of a transparent material.

7. The liquid crystal display device according to claim 1, wherein the second common electrode is formed of a transparent material.

8. A liquid crystal display device, comprising:

an insulating substrate;

a thin film transistor formed over the insulating substrate;

a first common electrode provided in a same layer as a semiconductor layer of the thin film transistor;

an insulating layer provided to cover the first common electrode;

a pixel electrode and a second common electrode provided over the insulating layer; and

a liquid crystal material provided over the pixel electrode and the second common electrode,

wherein the first common electrode and the second common electrode are electrically connected, and

tilting of the liquid crystal material is controlled by an electrical field between the pixel electrode and the first common electrode, and an electrical field between the pixel electrode and the second common electrode.

9. The liquid crystal display device according to claim 8, wherein the thin film transistor includes a crystalline semiconductor layer.

10. The liquid crystal display device according to claim 8, further comprising:

a passivation layer provided over the first common electrode and the thin film transistor,

a color filter provided over the first common electrode with the passivation layer therebetween, and

a black matrix provided over the thin film transistor with the passivation layer therebetween.

11. The liquid crystal display device according to claim 8, further comprising:

a passivation layer provided over the first common electrode and the thin film transistor,

a color filter provided over the first common electrode and the thin film transistor with the passivation layer therebetween,

a counter substrate provided to face the insulating substrate, and

a black matrix provided over the counter substrate.

12. The liquid crystal display device according to claim 8, further comprising:

a passivation layer provided over the thin film transistor,

a color filter provided over the passivation layer,

a first common electrode provided over the color filter, and

a black matrix provided over the thin film transistor with the passivation layer therebetween.

13. The liquid crystal display device, according to claim 8, wherein the pixel electrode is comb-shaped.

14. The liquid crystal display device according to claim 8, wherein the first common electrode is comb-shaped.

15. The liquid crystal display device according to claim 8, wherein the second common electrode is comb-shaped.

16. The liquid crystal display device according to claim 8, wherein the pixel electrode is formed of a transparent material.

17. The liquid crystal display device according to claim 8, wherein the first common electrode is formed of a transparent material.

18. The liquid crystal display device according to claim 8, wherein the second common electrode is formed of a transparent material.

19. A liquid crystal display device, comprising:

an insulating substrate;

a thin film transistor formed over the insulating substrate;

a first common electrode provided in a same layer as source and drain electrodes in the thin film transistor;

a conductive layer connected to the first common electrode;

an insulating layer provided over the first common electrode and the conductive layer;

a pixel electrode and a second common electrode provided over the insulating layer; and

a liquid crystal material provided over the pixel electrode and the second common electrode,

wherein tilting of the liquid crystal material is controlled by an electrical field between the pixel electrode and the first common electrode, and an electrical field between the pixel electrode and the second common electrode.

20. The liquid crystal display device according to claim 19, wherein the thin film transistor includes a crystalline semiconductor layer.

21. The liquid crystal display device according to claim 19, further comprising:

a passivation layer provided over the first common electrode and the thin film transistor,

a color filter provided over the first common electrode with the passivation layer therebetween, and

a black matrix provided over the thin film transistor with the passivation layer therebetween.

22. The liquid crystal display device according to claim 19, further comprising:

a passivation layer provided over the first common electrode and the thin film transistor,

a color filter provided over the first common electrode and the thin film transistor with the passivation layer therebetween,

a counter substrate provided to face the insulating substrate, and

a black matrix provided over the counter substrate.

23. The liquid crystal display device according to claim 19, further comprising:

a passivation layer provided over the thin film transistor,

a color filter provided over the passivation layer,

a first common electrode provided over the color filter, and

a black matrix provided over the thin film transistor with the passivation layer therebetween.

24. The liquid crystal display device, according to claim 19, wherein the pixel electrode is comb-shaped.

25. The liquid crystal display device according to claim 19, wherein the first common electrode is comb-shaped.

26. The liquid crystal display device according to claim 19, wherein the second common electrode is comb-shaped.

27. The liquid crystal display device according to claim 19, wherein the pixel electrode is formed of a transparent material.

28. The liquid crystal display device according to claim 19, wherein the first common electrode is formed of a transparent material.

29. The liquid crystal display device according to claim 19, wherein the second common electrode is formed of a transparent material.

30. A liquid crystal display device, comprising:

an insulating substrate;

a thin film transistor formed over the insulating substrate;

a first common electrode provided in a same layer as a semiconductor layer of the thin film transistor;

a conductive layer connected to the first common electrode;

an insulating layer provided over the first common electrode and the conductive layer;

a pixel electrode and a second common electrode provided over the insulating layer; and

a liquid crystal material provided over the pixel electrode and the second common electrode,

wherein tilting of the liquid crystal material is controlled by an electrical field between the pixel electrode and the first common electrode, and an electrical field between the pixel electrode and the second common electrode.

31. The liquid crystal display device according to claim 30, wherein the thin film transistor includes a crystalline semiconductor layer.

32. The liquid crystal display device according to claim 30, further comprising:

a passivation layer provided over the first common electrode and the thin film transistor,

a color filter provided over the first common electrode with the passivation layer therebetween, and

a black matrix provided over the thin film transistor with the passivation layer therebetween.

33. The liquid crystal display device according to claim 30, further comprising:

a passivation layer provided over the first common electrode and the thin film transistor,

a color filter provided over the first common electrode and the thin film transistor with the passivation layer therebetween,

a counter substrate provided to face the insulating substrate, and

a black matrix provided over the counter substrate.

34. The liquid crystal display device according to claim 30, further comprising:

a passivation layer provided over the thin film transistor,

a color filter provided over the passivation layer,

a first common electrode provided over the color filter, and

a black matrix provided over the thin film transistor with the passivation field between the pixel electrode and the first common electrode, and an electrical field between the pixel electrode and the second common electrode.

35. The liquid crystal display device, according to claim 30, wherein the pixel electrode is comb-shaped.

36. The liquid crystal display device according to claim 30, wherein the first common electrode is comb-shaped.

37. The liquid crystal display device according to claim 30, wherein the second common electrode is comb-shaped.

38. The liquid crystal display device according to claim 30, wherein the pixel electrode is formed of a transparent material.

39. The liquid crystal display device according to claim 30, wherein the first common electrode is formed of a transparent material.

40. The liquid crystal display device according to claim 30, wherein the second common electrode is formed of a transparent material.

41. A liquid display device, comprising:

an insulating substrate;

a gate electrode formed over the insulating substrate;

a first common electrode formed in a same layer as the gate electrode;

an insulating layer provided to cover the gate electrode and the first common electrode;

a semiconductor layer provided over the gate electrode with the insulating layer therebetween;

source and drain electrodes provided over the semiconductor layer;

a conductive layer provided to be in contact with the first common electrode;

a pixel electrode connected to one of the source and drain electrodes;

a second common electrode connected to the first common electrode with the conductive layer therebetween; and

a liquid crystal material provided over the pixel electrode and the second common electrode,

wherein tilting of the liquid crystal material is controlled by an electrical field between the pixel electrode and the first common electrode, and an electrical field between the pixel electrode and the second common electrode.

42. The liquid crystal display device according to claim 41, wherein the semiconductor layer is an amorphous semiconductor layer.

43. The liquid crystal display device according to claim 41, further comprising:

a passivation layer provided over the first common electrode and the gate electrode;

a color filter provided over the first common electrode with the passivation layer therebetween, and

a black matrix provided over the source and drain electrodes.

44. The liquid crystal display device, according to claim 41, wherein the pixel electrode is comb-shaped.

45. The liquid crystal display device according to claim 41, wherein the first common electrode is comb-shaped.

46. The liquid crystal display device according to claim 41, wherein the second common electrode is comb-shaped.

47. The liquid crystal display device according to claim 41, wherein the pixel electrode is formed of a transparent material.

48. The liquid crystal display device according to claim 41, wherein the first common electrode is formed of a transparent material.

49. The liquid crystal display device according to claim 41, wherein the second common electrode is formed of a transparent material.

50. A liquid crystal display device, comprising:

an insulating substrate;

a gate electrode formed over the insulating substrate;

a conductive layer provided in a same layer as the gate electrode;

a first common electrode provided in contact with the conductive layer;

an insulating layer provided to cover the gate electrode and the first common electrode;

a semiconductor layer provided over the gate electrode with the insulating layer therebetween;

source and drain electrodes provided over the semiconductor layer;

a pixel electrode connected to one of the source and drain electrodes;

a second common electrode connected to the first common electrode; and

a liquid crystal material provided over the pixel electrode and the second common electrode,

wherein tilting of the liquid crystal material is controlled by an electrical field between the pixel electrode and the first common electrode, and an electrical field between the pixel electrode and the second common electrode.

51. The liquid crystal display device according to claim 50, wherein the semiconductor layer is an amorphous semiconductor layer.

52. The liquid crystal display device according to claim 50, further comprising:

a passivation layer provided over the first common electrode and the gate electrode;

a color filter provided over the source and drain electrodes and the first common electrode with the passivation layer therebetween,

a counter substrate provided to face the insulating substrate, and

a black matrix provided over the counter substrate.

53. The liquid crystal display device, according to claim 50, wherein the pixel electrode is comb-shaped.

54. The liquid crystal display device according to claim 50, wherein the first common electrode is comb-shaped.

55. The liquid crystal display device according to claim 50, wherein the second common electrode is comb-shaped.

56. The liquid crystal display device according to claim 50, wherein the pixel electrode is formed of a transparent material.

57. The liquid crystal display device according to claim 50, wherein the first common electrode is formed of a transparent material.

58. The liquid crystal display device according to claim 50, wherein the second common electrode is formed of a transparent material.