In-plane field type liquid crystal display device comprising a structure which is prevented from charging with electricity

• US 5,870,160 A
• Filed: 10/03/1996
• Issued: 02/09/1999
• Est. Priority Date: 10/12/1995
• Status: Expired due to Term

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi, Ltd.
• Inventors: Kinugawa, Kiyoshige, Yanagawa, Kazuhiko, Ohta, Masuyuki, Ashizawa, Keiichiro, Matsuyama, Shigeru, Mishima, Yasuyuki, Konishi, Nobutake, Ogawa, Kazuhiro, Yanai, Masahiro
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US08/720,780
• Time in Patent Office: 859 Days
• Field of Search: 349/110, 349/59, 349/111, 349/96, 349/141
• US Class Current: 349/141
• CPC Class Codes: G02F 1/133331 Cover glasses
• CPC Class Codes: G02F 1/133334 Electromagnetic shields
• CPC Class Codes: G02F 1/133512 Light shielding layers, e.g. black matrix G02F1/136209 takes precedence
• 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 1/136204 Arrangements to prevent high voltage or static electricity failures

Abstract

Even when a high potential such as of static electricity is applied from the outside of the liquid crystal display panel, the display image is prevented from becoming abnormal. When a black matrix of a resin composition having a large resistivity is used, the positions of the polarizer plates, black matrix, sealing portion and open region of the housing are defined to prevent the light from leaking through the periphery of the effective pixel region. The leakage of backlight that cannot be prevented by the black matrix only is prevented by the polarizer plates and the housing, a transparent electrically conductive film having a sheet resistivity of not larger than 2×10¹⁴ Ω/□ is formed over, under, or inside the polarizer plate, and the electrically conductive film is electrically connected to the electrically conductive housing.

Claims

1. A liquid crystal display device comprising a switching element, a pixel electrode and a counter electrode formed in a unit pixel over a first substrate of two substrates which are so disposed as to be opposed to each other with a liquid crystal layer provided therebetween, at least one of the two substrates being transparent, an electric field being generated between said pixel electrode and said counter electrode substantially in parallel with the first substrate for modulating light passing through the liquid crystal layer,

wherein a black matrix having a resistivity not smaller than 10⁶ Ω

·

cm is formed between the two substrates, and an electrically conductive layer having a light-transmitting property formed over a surface of the at least one transparent substrate at a viewed side thereof which is opposite to the liquid crystal layer side of the at least one transparent substrate, and is formed over a pixel-forming region;

wherein both of the two substrates are transparent, a backlight unit is disposed under the first substrate, and the substrate at the viewed side is a second substrate of the two substrates;

wherein the electrically conductive layer has a sheet resistivity no greater than 2×

10¹⁴ Ω

/□

; and

wherein the electrically conductive layer is formed by dispersing electrically conductive particles in a material for bonding a polarizer plate to said second transparent substrate.

2. A liquid crystal display device according to claim 1, wherein the electrically conductive particles are carbon particles.

3. A liquid crystal display device according to claim 1, wherein the electrically conductive particles are particles containing any one of ITO, SnO₂ or In₂ O₃, or a mixture thereof.

4. A liquid crystal display device comprising a switching element, a pixel electrode and a counter electrode formed in a unit pixel over a first substrate of two substrates which are so disposed as to be opposed to each other with a liquid crystal layer provided therebetween, at least one of the two substrates being transparent, an electric field being generated between said pixel electrode and said counter electrode substantially in parallel with the first substrate for modulating light passing through the liquid crystal layer,

wherein a black matrix having a resistivity not smaller than 10⁶ Ω

·

cm is formed between the two substrates, and an electrically conductive layer having a light-transmitting property formed over a surface of the at least one transparent substrate at a viewed side thereof which is opposite to the liquid crystal layer side of the at least one transparent substrate, and is formed over a pixel-forming region;

wherein both of the two substrates are transparent, a backlight unit is disposed under the first substrate, and the substrate at the viewed side is a second substrate of the two substrates;

wherein the electrically conductive layer has a sheet resistivity no greater than 2×

10¹⁴ Ω

/□

; and

wherein the electrically conductive layer is an electrically conductive sheet interposed between the second transparent substrate and a polarizer plate.

5. A liquid crystal display device comprising a switching element, a pixel electrode and a counter electrode formed in a unit pixel over a first substrate of two substrates which are so disposed as to be opposed to each other with a liquid crystal layer provided therebetween, at least one of the two substrates being transparent, an electric field being generated between said pixel electrode and said counter electrode substantially in parallel with the first substrate for modulating light passing through the liquid crystal layer,

wherein a black matrix having a resistivity not smaller than 10⁶ Ω

·

cm is formed between the two substrates, and an electrically conductive layer having a light-transmitting property formed over a surface of the at least one transparent substrate at a viewed side thereof which is opposite to the liquid crystal layer side of the at least one transparent substrate, and is formed over a pixel-forming region;

wherein both of the two substrates are transparent, a backlight unit is disposed under the first substrate, and the substrate at the viewed side is a second substrate of the two substrates;

wherein the electrically conductive layer has a sheet resistivity no greater than 2×

10¹⁴ Ω

/□

; and

wherein the electrically conductive layer is a transparent electrically conductive film interposed between the second transparent substrate and a polarizer plate.

6. A liquid crystal display device comprising a switching element, a pixel electrode and a counter electrode formed in a unit pixel over a first substrate of two substrates which are so disposed as to be opposed to each other with a liquid crystal layer provided therebetween, at least one of the two substrates being transparent, an electric field being generated between said pixel electrode and said counter electrode substantially in parallel with the first substrate for modulating light passing through the liquid crystal layer,

wherein a black matrix having a resistivity not smaller than 10⁶ Ω

·

cm is formed between the two substrates, and an electrically conductive layer having a light-transmitting property formed over a surface of the at least one transparent substrate at a viewed side thereof which is opposite to the liquid crystal layer side of the at least one transparent substrate, and is formed over a pixel-forming region; and

wherein said liquid crystal display device further comprises an electrically conductive housing having an opening for exposing a display area, and said electrically conductive layer is connected to said housing via an electrically conductive material having a sheet resistivity no greater than 2×

10⁸ Ω

/□

.

7. A liquid crystal display device according to claim 6, wherein the electrically conductive material is an electrically conductive rubber.

8. A liquid crystal display device according to claim 6, wherein the electrically conductive material is a silver paste.

9. A liquid crystal display device according to claim 6, wherein the electrically conductive material is a metal foil tape.

10. A liquid crystal display device according to claim 6, wherein the electrically conductive material is an organic material containing at least one of electrically conductive beads and electrically conductive fibers.

11. A liquid crystal display device comprising a switching element, a pixel electrode and a counter electrode formed in a unit pixel over a first substrate of two substrates which are so disposed as to be opposed to each other with a liquid crystal layer provided therebetween, and further comprising a backlight unit located under said first substrate, and an electrically conductive housing having an open region including a display area, electric field being generated between said pixel electrode and said counter electrode substantially in parallel with the first substrate for modulating light passing through the liquid crystal layer,

wherein a black matrix made of a resin composition having a resistivity of not smaller than 10⁶ Ω

·

cm is formed between a second substrate of the two substrates and the liquid crystal layer, an electrically conductive layer having a light-transmitting property is formed over a pixel-forming region and over a surface of the second substrate on a side thereof opposite to the liquid crystal layer, and a polarizer plate is disposed over said second substrate side, which polarizer plate is larger than the open region of the electrically conductive housing.

13. A liquid crystal display device according to claim 11 or 12, wherein said substrates are transparent are connected by a sealing member, and at least part of the outer circumference of said black matrix is formed inside the region where the sealing member is formed.

14. A liquid crystal display device according to claim 11, wherein the width of an overlap of said polarizer plate on the housing is at least 0.5 mm.

15. A liquid crystal display device according to claim 11, wherein the ends of said polarizer plate are spaced inwardly from the ends said second substrate by more than 0.5 mm.

16. A liquid crystal display device according to claim 11 or 12, wherein said polarizer plate has a sheet resistivity no greater than 2×

10¹⁴ Ω

/□

, and said polarizer plate is electrically connected to the housing.

17. A liquid crystal display device according to claim 11 or 12, wherein an electrically conductive transparent layer having a sheet resistivity no greater than 2×

10¹⁴ Ω

/□

is formed on the upper side of said polarizer plate, is electrically connected to the housing.

18. A liquid crystal display device according to claim 11 or 12, wherein a electrically conductive transparent film having a sheet resistivity no greater than 2×

10¹⁴ Ω

/□

is formed between said polarizer plate and said transparent substrate, and said electrically conductive transparent film is electrically connected to the housing.

19. A liquid crystal display device according to claim 16, wherein said polarizer plate is connected to the housing via an electrically conductive material having a resistance no greater than 1 ×

10³ Ω

.

20. A liquid crystal display device according to claim 11 or 12, wherein an electrically conductive film is connected to the housing via an electrically conductive material having a resistance no greater than 1×

10³ Ω

.

21. A liquid crystal display device according to any one of claim 11 or 12, wherein polarizer plates are provided on both substrates, the axis of polarization of the polarizer plates being deviated by about 90 degrees relative to each other.

22. A liquid crystal display device according to claim 11, wherein said light-shielding spacer is made of an electrically conductive material having a sheet resistivity no greater than 1 ×

10⁸ Ω

/□

.

12. A liquid crystal display device comprising a switching element, a pixel electrode and a counter electrode formed in a unit pixel on a first substrate of two substrates which are so disposed as to be opposed to each other with a liquid crystal layer provided therebetween, and further comprising a backlight unit provided under said first substrate, and an electrically conductive housing having an open region including a display area, an electric field being generated between said pixel electrode and said counter electrode substantially in parallel with the first substrate for modulating light passing through the liquid crystal layer,

wherein a black matrix made of a resin composition having a resistivity of not smaller than 10⁶ Ω

·

cm is formed between a second substrate of the two substrates and the liquid crystal layer, an electrically conductive layer having a light-transmitting property is formed over a pixel-forming region and over a surface of the second substrate on a side thereof opposite to the liquid crystal layer, a polarizer plate is disposed over said second substrate, which polarizer plate is smaller than the open region of the electrically conductive housing, and a light-shielding spacer is so formed as to cover a gap between said polarizer plate and the open region of the housing and so as to be overlapped on the polarizer plate and the housing.

23. A liquid crystal display device comprising a liquid crystal display panel and a backlight unit, the liquid crystal display panel further comprising a pixel electrode and a counter electrode formed in a unit pixel between two transparent substrates which are arranged so as to be opposed to each other with the liquid crystal layer provided therebetween, an electric field being generated between the pixel electrode and the counter electrode substantially in parallel with the first substrate for modulating light passing through the liquid crystal layer,

wherein a transparent protective plate is further arranged on one transparent substrate at a viewed side thereof with a gap formed therebetween;

and

wherein the liquid crystal display panel and the backlight unit are contained in an electrically conductive housing, and the protective plate is supported by the housing.

24. A liquid crystal display device comprising a liquid crystal display panel and a backlight unit, the liquid crystal display panel further comprising a pixel electrode and a counter electrode formed in a unit pixel between two transparent substrates which are arranged so as to be opposed to each other with the liquid crystal layer provided therebetween, an electric field being generated between the pixel electrode and the counter electrode substantially in parallel with the first substrate for modulating light passing through the liquid crystal layer,

wherein a transparent protective plate is further arranged on one transparent substrate at a viewed side thereof with a gap formed therebetween;

wherein said conductive plate is provided with an electrically conductive film;

wherein said electrically conductive film is a grounded film; and

wherein the liquid crystal display panel and the backlight unit are contained in an electrically conductive housing, the protective plate is supported by the housing, and the electrically conductive film is connected to the housing.

25. A liquid crystal display device comprising a switching element, a pixel electrode and a counter electrode formed in a unit pixel over a first substrate of two substrates which are so disposed as to be opposed to each other with a liquid crystal layer provided therebetween, at least one of the two substrates being transparent, an electric field being generated between said pixel electrode and said counter electrode substantially in parallel with the first substrate for modulating light passing through the liquid crystal layer,

wherein an electrically conductive layer having a light transmitting property is formed over a surface of the at least one transparent substrate at a viewed side thereof which is opposite to the liquid crystal layer side of the at least one transparent substrate, and is formed over a pixel-forming region.

26. A liquid crystal display device according to claim 25, wherein both of the two substrates are transparent, a backlight unit is disposed under the first substrate, and the substrate of the viewed side is a second substrate of the two substrates.

27. A liquid crystal display device according to claim 25, wherein the electrically conductive layer has a light transmission factor of at least 34%.

28. A liquid crystal display device according to claim 25, wherein the electrically conductive layer has a sheet resistivity no greater than 2×

10¹⁴ Ω

/□

.

29. A liquid crystal display device according to claim 28, wherein the electrically conductive layer is formed by dispersing electrically conductive particles in a material for bonding a polarizer plate to a second transparent substrate of the two substrates.

30. A liquid crystal display device according to claim 29, wherein the electrically conductive particles are carbon particles.

31. A liquid crystal display device according to claim 29, wherein the electrically conductive particles are particles containing any one of ITO, SnO₂ or In₂ O₃, or a mixture thereof.

32. A liquid crystal display device according to claim 25, wherein the electrically conductive layer is an electrically conductive sheet interposed between a second transparent substrate of the two substrates and a polarizer plate.

33. A liquid crystal display device according to claim 25, wherein said electrically conductive layer is a transparent electrically conductive film interposed between a second transparent substrate of the two substrates and a polarizer plate.

34. A liquid crystal display device according to claim 25, wherein the electrically conductive layer is a transparent electrically conductive film formed on a surface of a polarizer plate.

35. A liquid crystal display device according to claim 25, wherein the electrically conductive layer is a transparent electrically conductive film formed inside a polarizer plate.

36. A liquid crystal display device according to any one of claims 33, 34 and 35, wherein the transparent electrically conductive film is a film containing as a chief component, any one of ITO, SnO₂ or In₂ O₃.

37. A liquid crystal display device according to claim 35, wherein the electrically conductive layer is a grounded layer.

38. A liquid crystal display device having a plurality of switching elements comprising:

a pair of substrates in which at least one of the pair of substrates is transparent;

a liquid crystal layer interposed between said pair of substrates; and

an electrode structure formed on one of said pair of substrates for generating an electric field having a major component substantially in parallel with said one of said pair of substrates;

wherein an electrically conductive layer having a light transmitting property is formed over a surface of the at least one transparent substrate at a viewed side thereof which is opposite to the liquid crystal layer side of the at least one transparent substrate and is formed over a pixel-forming region.

39. A liquid crystal display device having a plurality of switching elements comprising:

a pair of substrates in which at least one of the pair of substrates is transparent;

a liquid crystal layer interposed between said pair of substrates; and

an electrode structure formed on one of said pair of substrates for generating an electric field having a major component substantially in parallel with said one of said pair of substrates;

wherein an electrically conductive layer having a light transmitting property is formed over a surface of the at least one transparent substrate at a viewed side thereof which is opposite to the liquid crystal layer side of the at least one transparent substrate and is formed over a pixel-forming region so as to enable proper image display by said liquid crystal display device.

40. A liquid crystal display device having a plurality of switching elements comprising:

a pair of substrates;

a liquid crystal layer interposed between said pair of substrates; and

an electrode structure formed on one of said pair of substrates for generating an electric field having a major component substantially in parallel with said one of said pair of substrates, the generation of the electric field substantially in parallel with said one of said pair of substrates being disturbed by static electricity externally applied to the liquid crystal display device,

wherein an electrically conductive layer having a light transmitting property is formed over a surface of the other of said pair of substrates at a viewed side thereof which is opposite to the liquid crystal layer side of said one of said pair of substrates, and is formed over a pixel-forming region so as to substantially prevent disturbance of the generation of the electric field substantially in parallel with said one of said pair of substrates by externally applied static electricity.

41. A liquid crystal display device having a plurality of switching elements comprising:

a pair of substrates;

a liquid crystal layer interposed between said pair of substrates; and

an electrode structure formed on one of said pair of substrates for generating an electric field having a major component substantially in parallel with said one of said pair of substrates;

wherein a viewed surface of a screen of the liquid crystal display device becomes distorted when the screen is rubbed in at least one status of the screen, an electrically conductive layer having a light transmitting property being formed over a surface of the other of said pair of substrates at a viewed side thereof which is opposite to the liquid crystal layer side of said one of said pair of substrates, and is formed over a pixel-forming region so as to substantially prevent the viewed surface of the screen of the liquid crystal display device from becoming distorted when rubbed, and thereby enabling proper image display.

42. A liquid crystal layer device according to claim 41, wherein the distortion of the screen is that the screen becomes whitish in regions where the screen is rubbed.

43. A liquid crystal layer device according to claim 42, wherein the at least one status of the screen includes a black status.

44. A liquid crystal display device having a plurality of switching elements comprising:

a pair of substrates;

a liquid crystal layer interposed between said pair of substrates;

an electrode structure formed on one of said pair of substrates for generating an electric field having a major component substantially in parallel with said one of said pair of substrates; and

a transparent electrically conductive layer formed on another of said pair of substrates at a viewed side which is opposite to the liquid crystal side;

wherein a distance between said electrode structure and said electrically conductive layer is at least ten times larger than the distance between electrodes of said electrode structure.

45. A liquid crystal display device according to claim 44, wherein said electrode structure includes a pixel electrode and a counter electrode.

46. A liquid crystal display device according to claim 45, wherein the distance between said pixel electrode and said counter electrode is in a range of several microns to several tens of microns.

47. A liquid crystal display device according to claim 45, wherein the thickness of said another of said pair of substrates is about one millimeter.

48. A liquid crystal display device according to claim 44, wherein said electrically conductive layer includes particles containing any one of ITO, SnO₂, In₂ O₃ and a mixture thereof.

49. A liquid crystal display device having a plurality of switching elements comprising:

a pair of substrates;

a liquid crystal layer interposed between said pair of substrates; and

an electrode structure formed on one of said pair of substrates for generating an electric field having a major component substantially in parallel with said one of said pair of substrates;

wherein an ITO film is formed as a transparent electrically conductive film on another of said pair of substrates at a viewed side which is opposite to the liquid crystal layer side.

50. A liquid crystal display device according to claim 49, wherein said electrode structure includes a pixel electrode and a counter electrode.

51. A liquid crystal display device according to claim 49, wherein said transparent electrically conductive film is a sputtered film.

52. A liquid crystal display device according to claim 49, wherein said liquid crystal layer has a thickness larger than 2.8 μ

m and smaller than 4.5 μ

m.

53. A liquid crystal display device according to claim 52, wherein said electrode structure includes a pixel electrode a counter electrode.

54. A liquid crystal display device according to claim 52, wherein said transparent electrically conductive film is a sputtered film.

55. A liquid crystal display device having a plurality of switching elements comprising:

a pair of substrates;

a liquid crystal layer interposed between said pair of substrates;

an electrode structure formed on one of said pair of substrates for generating an electric field having a major component substantially in parallel with said one of said pair of substrates; and

a polarizer plate disposed above another of said pair of substrates;

wherein said polarizer plate is coated with a transparent electrically conductive layer formed at a viewed side of said polarizer plate which is opposite to the liquid crystal layer side.

56. A liquid crystal display device according to claim 55, wherein said transparent electrically conductive layer include particles containing any one of ITO, SnO₂, In₂ O₃ and a mixture thereof.

57. A liquid crystal display device according to claim 56, wherein said transparent electrically conductive layer is an ITO layer having a resistivity smaller than 2×

10¹⁴ Ω

/□

.

58. A liquid crystal display device having a plurality of switching elements comprising:

a pair of substrates;

a liquid crystal layer interposed between said pair of substrates;

an electrode structure formed on one of said pair of substrates for generating an electric field having a major component substantially in parallel with said one of said pair of substrates; and

a polarizer plate disposed above another of said pair of substrates;

wherein said polarizer plate includes an ITO layer as an electrically conductive layer.

59. A liquid crystal display device according to claim 58, wherein said transparent electrically conductive layer include particles containing any one of ITO, SnO₂, In₂ O₃ and a mixture thereof.

60. A liquid crystal display device according to claim 59, wherein said ITO layer has a resistivity smaller than 2×

10¹⁴ Ω

/□

.

61. A liquid crystal display device having a plurality of switching elements comprising:

a pair of substrates;

a liquid crystal layer interposed between said pair of substrates;

an electrode structure formed on one of said pair of substrates for generating an electric field having a major component substantially in parallel with said one of said pair of substrates;

an electrically conductive layer formed on another of said pair of substrates at a viewed side which is opposite to the liquid crystal layer; and

polarizer plates provided on both of said pair of substrates;

wherein rubbing directions for said substrates extend in parallel between said pair of substrates, and axes of polarization of said polarizer plates are deviated by about 90 degrees relative to each other.

62. A liquid crystal display device according to claim 61, wherein one of said rubbing directions extends in parallel with an axis of polarization of one of said polarizer plates.

63. A liquid crystal display device according to claim 62, wherein said liquid crystal display device has a birefringence mode.

64. A liquid crystal display device according to claim 61, wherein said liquid crystal display device has a display mode of a normally-black mode.