Liquid crystal display and method of driving same

• US 20060001817A1
• Filed: 09/06/2005
• Published: 01/05/2006
• Est. Priority Date: 11/17/1995
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Nishi, Takeshi, Yamazaki, Shunpei
• Granted Patent: US 7,616,282 B2
• Time in Patent Office: Days
• US Class Current: 349/141
• CPC Class Codes: G02F 1/13306 Circuit arrangements or driving methods for the control of single liquid crystal cells G02F1/132, G02F1/133382 take precedence
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• 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 1/13454 Drivers integrated on the active matrix substrate G02F1/136277 takes precedence
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence
• CPC Class Codes: G02F 2203/02 reflective

Abstract

There is disclosed a lightweight and small liquid crystal display which achieves low power consumption and in which the optical anisotropy of the liquid crystal material is compensated for in order to enhance the viewing angle characteristics and the response speed of the liquid crystal material. Display electrodes and a common electrode are formed on one of the substrates. The orientation of the liquid crystal material is of the HAN (hybrid alignment nematic) type. This compensates for the optical anisotropy of the liquid crystal material and improves the response speed.

Claims

1-24. -24. (canceled)

25. A liquid crystal display device comprising:

a first substrate;

a thin film transistor formed over the first substrate;

a transparent pixel electrode electrically connected to the thin film transistor;

a transparent common electrode;

an insulating film interposed between the transparent pixel electrode and the transparent common electrode;

a second substrate opposed to the first substrate; and

a liquid crystal layer interposed between the first substrate and the second substrate,

wherein the thin film transistor, the transparent pixel electrode and the transparent common electrode are located between the first substrate and the liquid crystal layer, and

wherein the liquid crystal layer is driven by a voltage applied between the transparent display electrode and the transparent common electrode.

34. A liquid crystal display device according to claim 25, wherein the insulating film is a single layer.

43. A liquid crystal display device according to claim 25, wherein the transparent common electrode is formed above the transparent pixel electrode.

52. A liquid crystal display device according to claim 25, wherein the insulating film comprises a silicon nitride film.

61. A liquid crystal display device according to claim 25, wherein the transparent pixel electrode comprises indium tin oxide.

70. A liquid crystal display device according to claim 25, wherein the transparent common electrode comprises indium tin oxide.

79. A liquid crystal display device according to claim 25, wherein the common electrode and the pixel electrode do not overlap with each other.

91. A liquid crystal display device according to claim 25, wherein the liquid crystal display device is a reflective type liquid crystal display.

100. A liquid crystal display device according to claim 25, wherein the liquid crystal display device is driven by an optically compensated birefringence mode.

26. A liquid crystal display device comprising:

a first substrate;

a thin film transistor formed over the first substrate;

a transparent display electrode electrically connected to the thin film transistor;

a transparent common electrode;

a passivation film formed over the thin film transistor, the passivation film interposed between the transparent display electrode and the transparent common electrode;

a second substrate opposed to the first substrate; and

a liquid crystal layer interposed between the first substrate and the second substrate,

wherein the thin film transistor, the transparent display electrode and the transparent common electrode are located between the first substrate and the liquid crystal layer, and

wherein the liquid crystal layer display device is driven by a voltage applied between the transparent display electrode and the transparent common electrode.

35. A liquid crystal display device according to claim 26, wherein the insulating film is a single layer.

44. A liquid crystal display device according to claim 26, wherein the transparent common electrode is formed above the transparent display electrode.

53. A liquid crystal display device according to claim 26, wherein the insulating film comprises a silicon nitride film.

62. A liquid crystal display device according to claim 26, wherein the transparent display electrode comprises indium tin oxide.

71. A liquid crystal display device according to claim 26, wherein the transparent common electrode comprises indium tin oxide.

80. A liquid crystal display device according to claim 26, wherein the common electrode and the display electrode do not overlap with each other.

92. A liquid crystal display device according to claim 26, wherein the liquid crystal display device is a reflective type liquid crystal display.

101. A liquid crystal display device according to claim 26, wherein the liquid crystal display device is driven by an optically compensated birefringence mode.

27. An IPS mode liquid crystal display device comprising:

a first substrate;

a thin film transistor formed over the first substrate;

a transparent pixel electrode electrically connected to the thin film transistor;

a transparent common electrode, the transparent common electrode isolated from the transparent pixel electrode;

a second substrate opposed to the first substrate; and

a liquid crystal layer interposed between the first substrate and the second substrate,

wherein the thin film transistor, the transparent pixel electrode and the transparent common electrode are located between the first substrate and the liquid crystal layer.

36. A liquid crystal display device according to claim 27, wherein the insulating film is a single layer.

45. A liquid crystal display device according to claim 27, wherein the transparent common electrode is formed above the transparent pixel electrode.

54. A liquid crystal display device according to claim 27, wherein the insulating film comprises a silicon nitride film.

63. A liquid crystal display device according to claim 27, wherein the transparent pixel electrode comprises indium tin oxide.

72. A liquid crystal display device according to claim 27, wherein the transparent common electrode comprises indium tin oxide.

81. A liquid crystal display device according to claim 27, wherein the common electrode and the pixel electrode do not overlap with each other.

93. A liquid crystal display device according to claim 27, wherein the liquid crystal display device is a reflective type liquid crystal display.

102. A liquid crystal display device according to claim 27, wherein the liquid crystal display device is driven by an optically compensated birefringence mode.

28. A liquid crystal display device comprising:

a first substrate;

a thin film transistor formed over the first substrate;

a pixel electrode electrically connected to the thin film transistor;

a transparent common electrode;

an insulating film interposed between the transparent pixel electrode and the transparent common electrode;

a second substrate opposed to the first substrate; and

a liquid crystal layer interposed between the first substrate and the second substrate,

wherein the thin film transistor, the transparent pixel electrode and the transparent common electrode are located between the first substrate and the liquid crystal layer, and

wherein the liquid crystal layer is driven by an electric field produced between the transparent pixel electrode and the transparent common electrode.

37. A liquid crystal display device according to claim 28, wherein the passivation film is a single layer.

46. A liquid crystal display device according to claim 28, wherein the transparent common electrode is formed above the transparent pixel electrode.

55. A liquid crystal display device according to claim 28, wherein the passivation film comprises a silicon nitride film.

64. A liquid crystal display device according to claim 28, wherein the transparent pixel electrode comprises indium tin oxide.

73. A liquid crystal display device according to claim 28, wherein the transparent common electrode comprises indium tin oxide.

82. A liquid crystal display device according to claim 28, wherein the common electrode and the pixel electrode do not overlap with each other.

88. A liquid crystal display device according to claim 28, wherein directions of the produced electric field comprises at least a lateral direction.

94. A liquid crystal display device according to claim 28, wherein the liquid crystal display device is a reflective type liquid crystal display.

103. A liquid crystal display device according to claim 28, wherein the liquid crystal display device is driven by an optically compensated birefringence mode.

29. A liquid crystal display device comprising:

a first substrate;

a thin film transistor formed over the first substrate;

a transparent display electrode electrically connected to the thin film transistor;

a transparent common electrode;

a passivation film formed over the thin film transistor, the passivation film interposed between the transparent display electrode and the transparent common electrode;

a second substrate opposed to the first substrate; and

a liquid crystal layer interposed between the first substrate and the second substrate,

wherein the thin film transistor, the transparent display electrode and the transparent common electrode are located, between the first substrate and the liquid crystal layer, and

wherein the liquid crystal display device is driven by an electric field produced between the transparent display electrode and the transparent common electrode.

38. A liquid crystal display device according to claim 29, wherein the passivation film is a single layer.

47. A liquid crystal display device according to claim 29, wherein the transparent common electrode is formed above the transparent display electrode.

56. A liquid crystal display device according to claim 29, wherein the passivation film comprises a silicon nitride film.

65. A liquid crystal display device according to claim 29, wherein the transparent display electrode comprises indium tin oxide.

74. A liquid crystal display device according to claim 29, wherein the transparent common electrode comprises indium tin oxide.

83. A liquid crystal display device according to claim 29, wherein the common electrode and the display electrode do not overlap with each other.

89. A liquid crystal display device according to claim 29, wherein directions of the produced electric field comprises at least a lateral direction.

95. A liquid crystal display device according to claim 29, wherein the liquid crystal display device is a reflective type liquid crystal display.

104. A liquid crystal display device according to claim 29, wherein the liquid crystal display device is driven by an optically compensated birefringence mode.

30. An IPS mode liquid crystal display device comprising:

a first substrate;

a thin film transistor formed over the first substrate;

a transparent pixel electrode electrically connected to the thin film transistor;

a transparent common electrode, the transparent common electrode isolated from the transparent pixel electrode;

a second substrate opposed to the first substrate; and

a liquid crystal layer interposed between the first substrate and the second substrate,

wherein the thin film transistor, the transparent pixel electrode and the transparent common electrode are located between the first substrate and the liquid crystal layer, and

wherein the liquid crystal layer is driven by an electric field produced between the transparent pixel electrode and the transparent common electrode.

39. A liquid crystal display device according to claim 30, wherein the passivation film is a single layer.

48. A liquid crystal display device according to claim 30, wherein the transparent common electrode is formed above the transparent pixel electrode.

57. A liquid crystal display device according to claim 30, wherein the passivation film comprises a silicon nitride film.

66. A liquid crystal display device according to claim 30, wherein the transparent pixel electrode comprises indium tin oxide.

75. A liquid crystal display device according to claim 30, wherein the transparent common electrode comprises indium tin oxide.

84. A liquid crystal display device according to claim 30, wherein the common electrode and the pixel electrode do not overlap with each other.

90. A liquid crystal display device according to claim 30, wherein directions of the produced electric field comprises at least a lateral direction.

96. A liquid crystal display device according to claim 30, wherein the liquid crystal display device is a reflective type liquid crystal display.

105. A liquid crystal display device according to claim 30, wherein the liquid crystal display device is driven by an optically compensated birefringence mode.

31. A liquid crystal display device comprising:

a first substrate;

a thin film transistor comprising amorphous silicon formed over the first substrate;

a transparent pixel electrode electrically connected to the thin film transistor;

a transparent common electrode;

an insulating film interposed between the transparent pixel electrode and the transparent common electrode;

a second substrate opposed to the first substrate; and

a liquid crystal layer interposed between the first substrate and the second substrate,

wherein the thin film transistor, the transparent pixel electrode and the transparent common electrode are located between the first substrate and the liquid crystal layer, and

wherein the liquid crystal layer is driven by a voltage applied between the transparent display electrode and the transparent common electrode.

40. A liquid crystal display device according to claim 31, wherein the insulating film is a single layer.

49. A liquid crystal display device according to claim 31, wherein the transparent common electrode is formed above the transparent pixel electrode.

58. A liquid crystal display device according to claim 31, wherein the insulating film comprises a silicon nitride film.

67. A liquid crystal display device according to claim 31, wherein the transparent pixel electrode comprises indium tin oxide.

76. A liquid crystal display device according to claim 31, wherein the transparent common electrode comprises indium tin oxide.

85. A liquid crystal display device according to claim 31, wherein the common electrode and the pixel electrode do not overlap with each other.

97. A liquid crystal display device according to claim 31, wherein the liquid crystal display device is a reflective type liquid crystal display.

106. A liquid crystal display device according to claim 31, wherein the liquid crystal display device is driven by an optically compensated birefringence mode.

32. A liquid crystal display device comprising:

a first substrate;

a thin film transistor comprising amorphous silicon formed over the first substrate;

a transparent display electrode electrically connected to the thin film transistor;

a transparent common electrode;

a passivation film formed over the thin film transistor, the passivation film interposed between the transparent display electrode and the transparent common electrode;

a second substrate opposed to the first substrate; and

a liquid crystal layer interposed between the first substrate and the second substrate,

wherein the thin film transistor, the transparent display electrode and the transparent common electrode are located between the first substrate and the liquid crystal layer, and

wherein the liquid crystal display device is driven by a voltage applied between the transparent display electrode and the transparent common electrode.

41. A liquid crystal display device according to claim 32, wherein the insulating film is a single layer.

50. A liquid crystal display device according to claim 32, wherein the transparent common electrode is formed above the transparent display electrode.

59. A liquid crystal display device according to claim 32, wherein the insulating film comprises a silicon nitride film.

68. A liquid crystal display device according to claim 32, wherein the transparent display electrode comprises indium tin oxide.

77. A liquid crystal display device according to claim 32, wherein the transparent common electrode comprises indium tin oxide.

86. A liquid crystal display device according to claim 32, wherein the common electrode and the display electrode do not overlap with each other.

98. A liquid crystal display device according to claim 32, wherein the liquid crystal display device is a reflective type liquid crystal display.

107. A liquid crystal display device according to claim 32, wherein the liquid crystal display device is driven by an optically compensated birefringence mode.

33. An IPS mode liquid crystal display device comprising:

a first substrate;

a thin film transistor comprising amorphous silicon formed over the first substrate;

a transparent pixel electrode electrically connected to the thin film transistor;

transparent common electrode, the transparent common electrode isolated from the transparent pixel electrode;

a second substrate opposed to the first substrate; and

a liquid crystal layer interposed between the first substrate and the second substrate,

wherein the thin film transistor, the transparent pixel electrode and the transparent common electrode are located between the first substrate and the liquid crystal layer.

42. A liquid crystal display device according to claim 33, wherein the insulating film is a single layer.

51. A liquid crystal display device according to claim 33, wherein the transparent common electrode is formed above the transparent pixel electrode.

60. A liquid crystal display device according to claim 33, wherein the insulating film comprises a silicon nitride film.

69. A liquid crystal display device according to claim 33, wherein the transparent pixel electrode comprises indium tin oxide.

78. A liquid crystal display device according to claim 33, wherein the transparent common electrode comprises indium tin oxide.

87. A liquid crystal display device according to claim 33, wherein the common electrode and the pixel electrode do not overlap with each other.

99. A liquid crystal display device according to claim 33, wherein the liquid crystal display device is a reflective type liquid crystal display.

108. A liquid crystal display device according to claim 33, wherein the liquid crystal display device is driven by an optically compensated birefringence mode.