Liquid crystal display device with a polymer between liquid crystal regions

• US 5,473,450 A
• Filed: 04/27/1993
• Issued: 12/05/1995
• Est. Priority Date: 04/28/1992
• Status: Expired

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Kuratate, Tomoaki, Awane, Katunobu, Majima, Kenji, Yamada, Nobuaki, Onishi, Noriaki, Kondo, Masahiko, Hirai, Toshiyuki, Shinomiya, Tokihiko, Fujimori, Kohichi, Kohzaki, Shuichi
• Primary Examiner(s): Gross, Anita Pellman
• Application Number:
  US08/054,454
• Time in Patent Office: 952 Days
• Field of Search: 359/51, 359/52, 359/62
• US Class Current: 349/84
• CPC Class Codes: G02F 1/133377 Cells with plural compartments or having plurality of liquid crystal microcells partitioned by walls, e.g. one microcell per pixel
• CPC Class Codes: G02F 1/133711 by organic films, e.g. polymeric films
• CPC Class Codes: G02F 1/133757 with different alignment orientations

Abstract

A liquid crystal display device of the present invention includes: two substrates facing each other, at least one of the substrates being transparent; electrodes disposed on inside surfaces of the respective substrates; a display medium which is provided between the two substrates and formed of polymer walls containing a polymer as their main component and liquid crystal regions containing liquid crystal as their main component; and a plurality of pixels, wherein the liquid crystal regions are partitioned by the polymer walls and are close to the substrates, portions of the liquid crystal regions close to the substrates being in parallel with the substrates, an interval a between the center of one liquid crystal region and the center of an adjacent liquid crystal region in a direction along the surface of the substrate is within a width of one pixel along the direction, and 80% or more of the intervals a satisfy the relationship: 3b/2>a>b/2, where b is an average of the intervals a.

Claims

1. A liquid crystal display device comprising:

two substrates facing each other, at least one of the substrates being transparent;

electrodes disposed on inside surfaces of the respective substrates;

a display medium which is provided between the two substrates and formed of polymer walls and liquid crystal regions partitioned by the polymer walls; and

a plurality of pixels,

wherein an interval a between a center of one liquid crystal region and a center of an adjacent liquid crystal region in a direction along a surface of the substrate is within a width of one pixel along the direction, and 80% or more of the intervals a satisfy the relationship;

3b/2>

a>

b/2, where b is an average of the intervals a.

2. A method for manufacturing a liquid crystal display device having a plurality of pixels, comprising the steps of:

providing a mixture containing a photopolymerizable compound and a liquid crystal material between a pair of substrates, two substrates facing each other, at least one of the substrates being transparent, electrodes being disposed on inside surfaces of the respective substrates; and

irradiating light to the mixture with a light intensity distribution in which light intensity of at least one portion of each pixel is 90% or less of a maximum illuminance in a circular area which corresponds to 10 times the pixel area and whose center is situated in a center of the pixel.

3. A method for manufacturing a liquid crystal display device according to claim 2, wherein a photomask having a pattern with regularity is placed on the transparent substrate, and light is irradiated through the photomask to the mixture provided between the substrates.

4. A method for manufacturing a liquid crystal display device according to claim 3, wherein the pattern with regularity is formed on the photomask, and the pattern covers 30% or more of at least each pixel.

5. A method for manufacturing a liquid crystal display device according to claim 3, wherein the pattern with regularity is formed on the photomask, a minimum repeating unit of the pattern has a size within a circle having a diameter in the range of 1 μ

m to 50 μ

m, and an interval between a center of one unit and a center of an adjacent unit is in the range of 1 μ

m to 50 μ

m.

6. A method for manufacturing a liquid crystal display device according to claim 2, wherein the photomask having a pattern with regularity is placed inside one of the substrates, and light is irradiated through the photomask to the mixture provided between the substrates.

7. A method for manufacturing a liquid crystal display device according to claim 6, wherein the pattern with regularity is formed on the photomask, and the pattern covers 30% or more of at least each pixel.

8. A method for manufacturing a liquid crystal display device according to claim 7, wherein the pattern with regularity is formed on the photomask, a minimum repeating unit of the pattern has a size within a circle having a diameter in the range of 1 μ

m to 50 μ

m, and an interval between a center of one unit and a center of an adjacent unit is in the range of 1 μ

m to 50 μ

m.

9. A liquid crystal display device comprising:

two substrates facing each other, at least one of the substrates being transparent, electrodes disposed on inside surfaces of the respective substrates; and

a display medium which is provided between the two substrates and formed of polymer walls containing a polymer as their main component and liquid crystal regions containing liquid crystal as their main component;

wherein the liquid crystal regions are partitioned by the polymer walls and are close to the substrates, portions of the liquid crystal regions close to the substrates being in parallel with the substrates.

10. A liquid crystal display device according to claim 9, wherein an orientation direction of a plurality of liquid crystal molecules contained in each of the liquid crystal regions is concentric along the polymer walls within a plane which is in parallel with the substrates.

11. A liquid crystal display device according to claim 9, wherein each of the liquid crystal regions has a plurality of liquid crystal domains and an orientation direction of each of the liquid crystal domains is concentric along the polymer walls within a plane which is in parallel with the substrates.

12. A liquid crystal display device according to claim 9, wherein each of the liquid crystal regions has an inside liquid crystal domain situated in a center thereof, a polymer region surrounding an outside of the inside liquid crystal domain, and a plurality of outside liquid crystal domains surrounding an outside of the polymer region;

and the respective outside liquid crystal domains are aligned in a radial manner within a plane which is in parallel with the substrates.

13. A liquid crystal display device according to claim 9, wherein the liquid crystal regions have a plurality of liquid crystal domains, and an orientation direction of each of the liquid crystal domains is different within a plane which is in parallel with the substrates.

14. A liquid crystal display device according to claim 9, wherein the liquid crystal regions have a polymer region positioned in the center thereof and a plurality of liquid crystal domains surrounding an outside of the polymer region, and the respective liquid crystal domains are aligned in a radial manner within a plane which is in parallel with the substrates.

15. A liquid crystal display device according to claim 9, comprising a plurality of pixels, wherein the liquid crystal regions are provided in at least one pixel.

16. A liquid crystal display device according to claim 15, wherein at least one liquid crystal region contained in the at least one pixel has a size of 30% or more of the pixel size.

17. A liquid crystal display device according to claim 15, wherein an orientation direction of a plurality of liquid crystal molecules contained in each of the liquid crystal regions is concentric along the polymer walls within a plane which is in parallel with the substrates.

18. A liquid crystal display device according to claim 15, wherein each of the liquid crystal regions has a plurality of liquid crystal domains, and an orientation direction of each of the liquid crystal domains is concentric along the polymer walls within a plane which is in parallel with the substrates.

19. A liquid crystal display device according to claim 15, wherein the liquid crystal regions have an inside liquid crystal domain positioned in a center thereof, a polymer region surrounding an outside of the inside liquid crystal domain, and a plurality of outside liquid crystal domains surrounding an outside of the polymer region;

and the respective outside liquid crystal domains are aligned in a radial manner within a plane which is in parallel with the substrates.

20. A liquid crystal display device according to claim 15, wherein the liquid crystal regions have a plurality of liquid crystal domains, and an orientation direction of each of the liquid crystal domains is different within a plane which is in parallel with the substrates.

21. A liquid crystal display device according to claim 15, wherein the liquid crystal regions have a polymer region positioned in a center thereof and a plurality of liquid crystal domains surrounding an outside of the polymer region;

and the respective liquid crystal domains are aligned in a radial manner within a plane which is in parallel with the substrates.

22. A liquid crystal display device according to claim 9, comprising a plurality of pixels, wherein two or more of the liquid crystal regions are entirely or partially provided in one pixel.

23. A liquid crystal display device according to claim 22, wherein the pixel has a longitudinal side of 200 μ

m or more.

24. A liquid crystal display device according to claim 22, wherein an orientation direction of a plurality of liquid crystal molecules contained in the liquid crystal regions are concentric along the polymer walls within a plane which is in parallel with the substrates.

25. A liquid crystal display device according to claim 22, wherein each of the liquid crystal regions has a plurality of liquid crystal domains, and an orientation direction of each of the liquid crystal domains is concentric along the polymer walls within a plane which is in parallel with the substrates.

26. A liquid crystal display device according to claim 22, wherein each of the liquid crystal domains has an inside liquid crystal domain positioned in a center thereof, a polymer region surrounding an outside of the inside liquid crystal domain, and a plurality of liquid crystal domains surrounding an outside of the polymer region;

and the respective outside liquid crystal domains are aligned in a radial manner within a plane which is in parallel with the substrates.

27. A liquid crystal display device according to claim 22, wherein the liquid crystal region has a plurality of liquid crystal domains, and an orientation direction of each of the liquid crystal domains is different within a plane which is in parallel with the substrates.

28. A liquid crystal display device according to claim 22, wherein each of the liquid crystal regions has a polymer region positioned in a center thereof and a plurality of liquid crystal domains surrounding an outside of the polymer region, and the respective liquid crystal domains are aligned in a radial manner within a plane which is in parallel with the substrates.

29. A liquid crystal display device according to claim 9, wherein a plurality of liquid crystal molecules contained in each of the liquid crystal regions are aligned in a helical manner along a helical axis which is vertical with respect to the substrates.

30. A liquid crystal display device according to claim 29, wherein the plurality of .liquid crystal molecules contained in each of the liquid crystal regions are provided with a helical pitch of 15 μ

m to 100 μ

m.

31. A liquid crystal display device according to claim 9, wherein d×

Δ

n is in the range of 0.4 μ

m to 1.1 μ

m; and

a distance between the substrates is in the range of 3 μ

m to 10 μ

m, where d is a thickness between horizontal portions in each of the liquid crystal regions and Δ

n is anisotropy of refractive index thereof.

32. A liquid crystal display device according to claim 9, wherein the display medium has a structure in which a liquid crystalline compound is fixed in the vicinity of an interface between the liquid crystal region and the polymer wall.

33. A liquid crystal display device according to claim 32, wherein anisotropy of dielectric constant Δ

ε

_L of the liquid crystal region and anisotropy of dielectric constant Δ

ε

_p of the liquid crystalline compound have a relationship of Δ

ε

_L ×

Δ

ε

_p <

0.

34. A liquid crystal display device according to claim 32, wherein the liquid crystalline compound has at least one of a fluorine atom and a chlorine atom and the liquid crystal region is formed from a liquid crystal material having at least one of fluorine atom and a chlorine atom in its molecule.

35. A liquid crystal display device according to claim 34, wherein the liquid crystalline compound has an optically active group in its molecule and the liquid crystal region is formed from ferroelectric liquid crystal.

36. A liquid crystal display device according to claim 32, wherein the polymer walls are formed in a liquid crystal state.

37. A liquid crystal display device according to claim 36, wherein the liquid crystal regions and the polymer walls contain a dichroic dye.

38. A liquid crystal display device according to claim 32, wherein the polymer walls are formed in a liquid crystal state, and the polymer walls and the liquid crystal regions are in the same orientation when no voltage is applied to the display medium.

39. A liquid crystal display device according to claim 38, wherein at least one of the substrates has an orientation film in contact with the display medium, and the polymer walls and the liquid crystal regions are in the same orientation, based on the orientation film.

40. A liquid crystal display device according to claim 39, wherein the liquid crystal regions and the polymer walls contain a dichroic dye.

41. A liquid crystal display device according to claim 9, wherein anisotropy of dielectric constant Δ

_L of the liquid crystal region and anisotropy of dielectric constant Δ

ε

_p of the liquid crystalline compound have a relationship of Δ

ε

_L ×

Δ

ε

_p <

0.

42. A liquid crystal display device according to claim 9, wherein a remaining monomer ratio obtained from infrared absorption caused by a double bond between carbons in the polymer wall and infrared absorption caused by a carbonyl group of an ester in the polymer wall is 10% or less.

43. A liquid crystal display device according to claim 9, wherein a light-intercepting mask is placed on one of the substrates so that light-intercepting portions of the mask cover portions where the substrate and the polymer walls are in contact with each other.

44. A liquid crystal display device according to claim 43, wherein the light-intercepting mask is placed so that the light-intercepting portions thereof cover 50% or more of the respective portions where the substrate and the polymer walls are in contact with each other.

45. A liquid crystal display device according to claim 9, wherein orientation films are respectively formed on the electrodes mounted on the substrates.

46. A liquid crystal display device according to claim 45, wherein the orientation films are uniaxially aligned by an orientation treatment.

47. A liquid crystal display device according to claim 45, wherein at least one of the orientation films contain a photopolymerization initiator.

48. A liquid crystal display device according to claim 9, wherein a polarizing plate is provided outside of at least one of the substrates.

49. A method for manufacturing a liquid crystal display device having a plurality of pixels, comprising the steps of:

providing a mixture containing a photopolymerizable compound and a liquid crystal material between a pair of substrates, two substrates facing each other, at least one of the substrates being transparent, and electrodes being disposed on inside surfaces of the respective substrates, thereby forming a cell; and

irradiating the mixture with light under the condition that intensity of light is reduced in predetermined portions of the mixture, thereby forming a display medium between the substrates, the display medium having polymer walls containing a polymer as their main component and liquid crystal regions containing liquid crystal as their main component.

50. A method for manufacturing a liquid crystal display device according to claim 49, wherein the predetermined portions correspond to at least one pixel, whereby the liquid crystal regions are provided in at least one pixel.

51. A method for manufacturing a liquid crystal display device according to claim 49, wherein an area of each of the predetermined portions corresponds to 30% or more of each pixel area, whereby at least one liquid crystal region contained in the pixel is made 30% or more of the pixel area.

52. A method for manufacturing a liquid crystal display device according to claim 49, wherein means for reducing intensity of light is a photomask, and the photomask is placed on the side of the display medium of one of the substrates.

53. A method for manufacturing a liquid crystal display device according to claim 49, wherein the mixture is irradiated with light through a photomask, the photomask having a plurality of masking portions for forming the liquid crystal regions and each of the masking portion having at least one light transmission hole at least in a center thereof, whereby liquid crystal domains are formed in a radial manner in each of the liquid crystal regions.

54. A method for manufacturing a liquid crystal display device according to claim 53, using a photomask having masking portions for forming the liquid crystal regions, each of the masking portions having a light transmission hole in a center thereof and light transmission slits disposed in a radial manner around the transmission hole.

55. A method for manufacturing a liquid crystal display device according to claim 49, wherein the mixture is irradiated with light while alternating a light-irradiating period and a non light-irradiating period.

56. A method for manufacturing a liquid crystal display device according to claim 49, wherein the mixture further contains a compound having effects for suppressing photopolymerization.

57. A method for manufacturing a liquid crystal display device according to claim 49, wherein the display medium having walls containing a polymer as their main component and liquid crystal regions containing liquid crystal as their main component is formed between the substrates by irradiating light to all of the portions or part thereof excluding the pixels.

58. A method for manufacturing a liquid crystal display device according to claim 57, wherein light which is irradiated to all of the portions or part thereof excluding the pixels is linear light.

59. A method for manufacturing a liquid crystal display device according to claim 57, wherein light irradiation to all of the portions or part thereof excluding the pixels is conducted while spot light in a dot shape is moved.

60. A method for manufacturing a liquid crystal display device according to claim 49, wherein means for reducing intensity of light is an insulating film formed on the electrode of one of the substrates, and the display medium having walls containing a polymer as its main component and liquid crystal regions containing liquid crystal as its main component is formed between the substrates by irradiating light to the mixture from the side of the substrate on which the insulating film is formed.

61. A method for manufacturing a liquid crystal display device according to claim 49, wherein the step of forming a cell is conducted by attaching the two substrates after providing the mixture on one of the substrates.

62. A method for manufacturing a liquid crystal display device according to claim 49, wherein polarizing plates are formed on external surfaces of the two substrates.

63. A method for manufacturing a liquid crystal display device having a plurality of pixels, comprising the steps of:

forming an orientation film containing a photopolymerization initiator on at least one of a pair of substrates, two substrates facing each other, at least one of the substrates being transparent, and electrodes being disposed on inside surfaces of the respective substrates;

subjecting the substrate on which the orientation film is formed to a rubbing treatment in one direction;

providing a mixture containing a photopolymerizable compound and a liquid crystal material between the pair of substrates after the rubbing treatment; and

forming a display medium having polymer walls containing a polymer as their main component and liquid crystal regions containing liquid crystal as their main component by curing the photopolymerizable compound.

64. A method for manufacturing a liquid crystal display device according to claim 63, wherein the photopolymerizable compound contained in the mixture contains a liquid crystalline compound having at least one polymerizable functional group in its molecule.

65. A method for manufacturing a liquid crystal display device according to claim 64, wherein a compound having a polymerizable functional group, at least one of a fluorine atom and a chlorine atom in its molecule is used as the liquid crystalline compound, and a liquid crystal material having at least one of a fluorine and a chlorine atom in its molecule is used for the liquid crystal regions.

66. A method for manufacturing a liquid crystal display device according to claim 65, wherein a compound having a polymerizable functional group and an optically active group in its molecule is used as the liquid crystalline compound, and ferroelectric liquid crystal is used for the liquid crystal regions.

67. A method for manufacturing a liquid crystal display device according to claim 63, wherein UV-rays are irradiated to the mixture so that portions where the liquid crystal regions are to be formed become weak light-irradiated regions, thereby optically polymerizing the photopolymerizable compound.

68. A method for manufacturing a liquid crystal display device according to claim 67, wherein means for forming weak light-irradiated regions is a photomask, and the photomask is placed on the side of the display medium of one of the substrates.

69. A method for manufacturing a liquid crystal display device according to claim 63, wherein the step of forming a cell is conducted by attaching the two substrates after providing the mixture on one of the substrates.

70. A method for manufacturing a liquid crystal display device according to claim 63, wherein polarizing plates are formed on external surfaces of the two substrates.

71. A method for manufacturing a liquid crystal display device having a plurality of pixels, comprising the steps of:

forming a thin film pattern containing a photopolymerization initiator on one surface of at least one of a pair of substrates, the substrates respectively having electrodes and at least one of the substrates being transparent;

providing a mixture containing a polymerizable compound and a liquid crystal material between the pair of substrates, at least one of the substrates having the thin film pattern, thereby forming a cell; and

forming a display medium between the substrates by curing the polymerizable compound, the display medium having polymer walls containing a polymer as their main component and liquid crystal regions containing liquid crystal as their main component.

72. A method for manufacturing a liquid crystal display device according to claim 71, wherein the polymerization initiator is a photopolymerization initiator, the polymerizable compound is a photopolymerizable compound, a photomask allowing 50% or more of the thin film pattern to be exposed is placed outside of one of the substrates, and light is irradiated to the photopolymerizable initiator and the photopolymerizable compound through the photomask to cure the photopolymerizable compound.

73. A method for manufacturing a liquid crystal display device according to claim 72, wherein the photopolymerizable compound contained in the mixture contains a liquid crystalline compound having at least one kind of polymerizable functional group at its molecule.

74. A method for manufacturing a liquid crystal display medium according to claim 73, wherein a compound having a polymerizable functional group, and at least one of a fluorine atom and a chlorine atom in its molecule is used as the liquid crystalline compound;

and a liquid crystal material having at least one of a fluorine atom and a chlorine atom in its molecule is used for the liquid crystal regions.

75. A method for manufacturing a liquid crystal display device according to claim 73, wherein a compound having a polymerizable functional group and an optically active group in its molecule is used as the liquid crystalline compound and ferroelectric liquid crystal is used for the liquid crystal regions.

76. A method for manufacturing a liquid crystal display device according to claim 71, wherein UV-rays are irradiated to the mixture so that portions where the liquid crystal regions are to be formed become weak light-irradiated regions, thereby optically polymerizing the polymerizable compound.

77. A method for manufacturing a liquid crystal display device according to claim 71, wherein the polymerization initiator is a heat polymerization initiator, the polymerizable compound is a heat polymerizable compound, and the heat polymerization initiator and the mixture are heated to cure the heat polymerizable compound.

78. A method for manufacturing a liquid crystal display device according to claim 71, wherein the step of forming a cell is conducted by attaching the two substrates after providing the mixture on one of the substrates.

79. A method for manufacturing a liquid crystal display device according to claim 71, wherein polarizing plates are formed on external surfaces of the two substrates.

80. A method for manufacturing a liquid crystal display device having a plurality of pixels, comprising the steps of:

providing a mixture between a pair of substrates facing each other, thereby forming a cell, at least one of the substrates being transparent, electrodes being disposed on inside surfaces on the respective substrates, the mixture containing a liquid crystal material, a polymerizable liquid crystalline material having a liquid crystalline functional group in its molecule, a polymerizable compound, and a polymerization initiator, anisotropy of dielectric constant Δ

ε

_L of the liquid crystal material and anisotropy of dielectric constant Δ

ε

_p of the polymerizable liquid crystalline material having a relationship of Δ

ε

_L ×

Δ

ε

_p <

0, and

forming a display medium between the substrates by polymerizing the polymerizable compound, the display medium having polymer walls containing a polymer as their main component and liquid crystal regions containing liquid crystal as their main component, providing the liquid crystalline functional groups in the liquid crystal regions to fix a liquid crystalline polymer on the polymer walls.

81. A method for manufacturing a liquid crystal display device according to claim 80, wherein the polymerizable compound is a photopolymerizable compound, the polymerization initiator is a photopolymerization initiator, and the polymerizable compound is optically polymerized.

82. A method for manufacturing a liquid crystal display device according to claim 81, wherein UV-rays are irradiated to the mixture so that portions where the liquid crystal regions are to be formed become weak light-irradiated regions, thereby optically polymerizing the mixture.

83. A method for manufacturing a liquid crystal display device according to claim 82, wherein means for forming the weak light-irradiated regions is a photomask, and the photomask is placed on the side of the display medium of one of the substrates.

84. A method for manufacturing a liquid crystal display device according to claim 80, wherein the polymerizable compound is a heat polymerizable compound, the polymerization initiator is a heat polymerization initiator, and the polymerizable compound is polymerized by heating.

85. A method for manufacturing a liquid crystal display device according to claim 80, wherein a compound having at least one of a fluorine atom and a chlorine atom in its molecule is used as the liquid crystal material and the polymerizable liquid crystalline material.

86. A method for manufacturing a liquid crystal display device according to claim 80, wherein the step of forming a cell is conducted by attaching the two substrates after providing the mixture on one of the substrates.

87. A method for manufacturing a liquid crystal display device according to claim 80, wherein the step of forming a cell comprises the steps of:

coating the mixture onto one of the substrates, the mixture further containing a solvent capable of homogeneously dissolving the liquid crystal material and the polymerizable liquid crystalline material;

removing the solvent from the mixture coated onto one of the substrates by evaporation to provide the liquid crystalline functional groups in the liquid crystal regions, thereby fixing a liquid crystalline compound on the polymer walls; and

placing the other substrate on the substrate on which the mixture is coated.

88. A method for manufacturing a liquid crystal display device according to claim 80, wherein polarizing plates are formed on external surfaces of the two substrates.

89. A method for manufacturing a liquid crystal display device having a plurality of pixels, comprising the steps of:

providing a mixture between a pair of substrates facing each other, thereby forming a cell, at least one of the substrates being transparent, electrodes being disposed on inside surfaces of the respective substrates, the mixture containing a liquid crystal material, a photopolymerizable compound, a photopolymerization initiator, and a radical generating agent;

irradiating light to the mixture to cause a phase separation, thereby obtaining a state in which liquid crystal regions are dispersed in the polymer walls; and

thermally decomposing the radical generating agent by heating the display medium.

90. A method for manufacturing a liquid crystal display device according to claim 89, wherein UV-rays are irradiated to the mixture so that portions where the liquid crystal regions are to be formed become weak light-irradiated regions, thereby optically polymerizing the polymerizable compound.

91. A method for manufacturing a liquid crystal display device according to claim 90, wherein means for forming the weak light-irradiated regions is a photomask, and the photomask is placed on the side of the display medium of one of the substrates.

92. A method for manufacturing a liquid crystal display device according to claim 89, wherein a liquid crystal material of at least one of a fluorine type and chlorine type is used as the liquid crystal material.

93. A method for manufacturing a liquid crystal display device according to claim 89, wherein the photopolymerizable compound contains a photopolymerizable liquid crystal compound.

94. A method for manufacturing a liquid crystal display device according to claim 89, wherein the step of forming a cell is conducted by attaching the two substrates after providing the mixture on one of the substrates.

95. A method for manufacturing a liquid crystal display device according to claim 89, wherein polarizing plates are formed on external surfaces of the two substrates.