Single layer multi-state ultra-fast cholesteric liquid crystal device and the fabrication methods thereof

• US 6,674,504 B1
• Filed: 10/01/2001
• Issued: 01/06/2004
• Est. Priority Date: 09/29/2000
• Status: Active Grant

• Current Assignee: Kent Optronics, Inc.
• Original Assignee: Kent Optronics, Inc.
• Inventors: Li, Le, Yang, Deng-Ke
• Primary Examiner(s): Kim, Robert H.
• Assistant Examiner(s): Di Grazio, Jeanne A.
• Application Number:
  US09/968,191
• Time in Patent Office: 827 Days
• Field of Search: 349/185, 349/169, 349/175
• US Class Current: 349/169
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: C09K 19/586 Optically active dopants; chiral dopants
• CPC Class Codes: C09K 19/60 Pleochroic dyes
• CPC Class Codes: G02F 1/13476 in which at least one liquid crystal cell or layer assumes a scattering state
• CPC Class Codes: G02F 1/13718 based on a change of the texture state of a cholesteric liquid crystal
• CPC Class Codes: G02F 1/13775 Polymer-stabilized liquid crystal layers

Abstract

A device and method of manufacturing a single layer multi-state ultra-fast cholesteric liquid crystal includes two optically transparent states with a liquid crystal arranged therebetween, and changing the optical states of the liquid crystal ranging from one state to any combination of broadband reflection, tunable narrow band reflection, light scattering, and transparency in accordance with a voltage applied to the device. A surfactant can be added to reduce the response time and a dichroic dye may be added to include the property of light absorption and reduce the bandwidth. The device can provide any and all of the aforementioned optical states for infrared light, visible light, and ultra-violet light. The desired outputs can be formed according to need, so that predetermined optical states can operate with either no voltage or a particular voltage or voltage range.

Claims

1. A cholesteric crystal device comprising:

two optically transparent substrates;

a liquid crystal having portions adapted for producing a plurality of optical states, said liquid crystal being arranged between the two optically transparent substrates;

means for changing optical states of respective portions of said liquid crystal to produce a range of respective optical states including all optical states produced by said liquid crystal ranging from one state to any combination of broadband reflection, tunable narrow band reflection, light scattering, and transparency in accordance with an amount of voltage applied across said means for changing optical states.

2. The device according to claim 1, wherein said means for changing comprises:

a first electrode electrically connected to a first of said two optically transparent substrates, and

a second electrode electrically connected to a second of said two optically transparent substrates.

3. The device according to claim 1, wherein said portions of said liquid crystal having respective polymer concentrations for producing a particular predetermined optical state at a predetermined voltage applied by said means for changing optical states.

4. The device according to claim 3, wherein said liquid crystal is a composite material consisting of a crosslinkable liquid crystal material, a chiral additive, and a photo initiator.

5. The device according to claim 3, wherein said liquid crystal is a composite material comprising a crosslinkable liquid crystal material, a chiral additive, and a photo initiator.

6. The device according to claim 4, wherein said crosslinkable liquid crystal material comprises a nematic liquid crystal.

7. The device according to claim 4, wherein said crosslinkable liquid crystal material comprises a left-handed cholesteric liquid crystal.

8. The device according to claim 4, wherein said crosslinkable liquid crystal material comprises a right-handed cholesteric liquid crystal.

9. An electro-optically active device comprising two cholesteric crystal devices according to claim 4, comprising a first cholesteric crystal device comprising a right-handed cholesteric liquid crystal, and a second cholesteric crystal device comprises a left-handed cholesteric liquid crystal.

10. The device according to claim 9, further comprising a third liquid crystal device comprising a nematic liquid crystal.

11. The device according to claim 1, wherein said device only produces a light scattering state when no voltage is applied to said means for changing optical states.

12. The device according to claim 1, wherein said device only produces a light scattering state according to a predetermined nonzero voltage value being applied to said means for changing optical states.

13. The device according to claim 4, wherein said device only produces a light scattering state when no voltage is applied to said means for changing optical states.

14. The device according to claim 4, wherein said device only produces a light scattering state according to a predetermined nonzero voltage value being applied to said means for changing optical states.

15. The device according to claim 4, wherein the composite material of said liquid crystal includes a dichroic dye.

16. An electro-optically active device comprising two cholesteric crystal devices according to claim 15, comprising a first cholesteric crystal device comprising a right-handed cholesteric liquid crystal, and a second cholesteric crystal device comprises a left-handed cholesteric liquid crystal.

17. The device according to claim 14, wherein said device produces a light absorbing state when no voltage is applied to said means for changing optical states.

18. The device according to claim 14, wherein said device produces a light absorbing state according to a predetermined nonzero voltage value being applied to said means for changing optical states.

19. The device according to claim 2, the first electrode and the second electrode comprise Indium-Tin-Oxide (ITO).

20. The device according to claim 1, wherein said two substrates are coated with rubbed polyimide.

21. The device according to claim 3, wherein at least one portion of said portions of liquid crystal comprises a planar texture when no voltage is applied by said means for changing optical states.

22. The device according to claim 21, wherein said planar texture has a tilted helix.

23. The device according to claim 3, wherein at least one portion of said portions of liquid crystal comprises a planar texture when a nonzero voltage is applied by said means for changing optical states.

24. The device according to claim 23, wherein said planar texture has a tilted helix.

25. The device according to claim 3, wherein at least one portion of said portions of liquid crystal is comprises a focal conical state when no voltage is applied by said means for changing optical states.

26. The device according to claim 3, wherein at least one portion of said portions of liquid crystal comprises a focal conical state when a nonzero voltage is applied by said means for changing optical states.

27. The device according to claim 3, wherein at least one portion of said portions of liquid crystal comprises a homeotropic texture when no voltage is applied by said means for changing optical states.

28. The device according to claim 1, wherein the tunable narrow band reflection has a shifted wavelength.

29. The device according to claim 3, wherein the tunable narrow band reflection has a shifted wavelength.

30. The device according to claim 28, wherein the shifted wavelength has a blue shift.

31. The device according to claim 29, wherein the shifted wavelength has a blue shift.

32. The device according to claim 1, wherein an optical state of the liquid crystal scatters light in the visible range and reflects light in the infrared range.

33. The device according to claim 32, wherein the infrared range is a near-infrared range.

34. The device according to claim 33, wherein the near-infrared range has wavelengths ranging from approximately 800 nm to 1,200 nm.

35. The device according to claim 3, in an optical state of the liquid crystal scatters light in the visible range and reflects light in the infrared range.

36. The device according to claim 35, wherein the infrared range is a near-infrared range.

37. The device according to claim 36, wherein the near-infrared range has wavelengths ranging from approximately 800 nm to 1,200 nm.

38. The device according to claim 4, wherein an optical state of the liquid crystal scatters light in the visible range and reflects light in the infrared range.

39. The device according to claim 38, wherein the infrared range is a near-infrared range.

40. The device according to claim 39, wherein the near-infrared range has wavelengths ranging from approximately 800 nm to 1,200 nm.

41. The device according to claim 10, wherein an optical state of the liquid crystal scatters light in the visible range and reflects light in the infrared range.

42. The device according to claim 41, wherein the infrared range is a near-infrared range.

43. The device according to claim 42, wherein the near-infrared range has wavelengths ranging from approximately 800 nm to 1,200 nm.

44. The device according to claim 11, wherein an optical state of the liquid crystal scatters light in the visible range and reflects light in the infrared range.

45. The device according to claim 44, wherein the infrared range is a near-infrared range.

46. The device according to claim 45, wherein the near-infrared range has wavelengths ranging from approximately 800 nm to 1,200 nm.

47. The device according to claim 15, wherein an optical state of the liquid crystal scatters light in the visible range and reflects light in the infrared range.

48. The device according to claim 47, wherein the infrared range is a near-infrared range.

49. The device according to claim 48, wherein the near-infrared range has wavelengths ranging from approximately 800 nm to 1,200 nm.

50. The device according to claim 1, wherein optical states of portions of the liquid crystal both scatters and reflects light in the infrared range.

51. The device according to claim 1, wherein near-infrared light is scattered, and infrared light having wavelengths ranging from approximately 1,200 nm to 1,600 nm is reflected.

52. The device according to claim 3, wherein optical states of portions of the liquid crystal both scatters and reflects light in the infrared range.

53. The device according to claim 52, wherein near-infrared light is scattered, and infrared light having wavelengths ranging from approximately 1,200 nm to 1,600 nm is reflected.

54. The device according to claim 4, wherein optical states of portions of the liquid crystal both scatters and reflects light in the infrared range.

55. The device according to claim 54, wherein near-infrared light is scattered, and infrared light having wavelengths ranging from approximately 1,200 nm to 1,600 nm is reflected.

56. The device according to claim 10, wherein optical states of portions of the liquid crystal both scatters and reflects light in the infrared range.

57. The device according to claim 56, wherein near-infrared light is scattered, and infrared light having wavelengths ranging from approximately 1,200 nm to 1,600 nm is reflected.

58. The device according to claim 11, wherein optical states of portions of the liquid crystal both scatters and reflects light in the infrared range.

59. The device according to claim 58, wherein near-infrared light is scattered, and infrared light having wavelengths ranging from approximately 1,200 nm to 1,600 nm is reflected.

60. The device according to claim 15, wherein optical states of portions of the liquid crystal both scatters and reflects light in the infrared range.

61. The device according to claim 60, wherein near-infrared light is scattered, and infrared light having wavelengths ranging from approximately 1,200 nm to 1,600 nm is reflected.

62. The device according to claim 9, further comprising a third cholesteric liquid crystal device arranged between said first cholesteric crystal device and said second cholesteric crystal device.

63. The device according to claim 62, wherein said first cholesteric liquid crystal device includes a first dichroic dye.

64. The device according to claim 63, wherein said second cholesteric liquid crystal device includes a second dichroic dye.

65. The device according to claim 64, wherein said third cholesteric liquid crystal device includes a third dichroic dye.

66. The device according to claim 1, wherein an optical state of the liquid crystal reflects ultra-violet light.

67. The device according to claim 3, wherein an optical state of the liquid crystal reflects ultra-violet light.

68. The device according to claim 4, wherein an optical state of the liquid crystal reflects ultra-violet light.

69. The device according to claim 9, wherein an optical state of at least one liquid crystal reflects ultra-violet light.

70. The device according to claim 15, wherein an optical state the liquid crystal reflects ultra-violet light.

71. The device according to claim 1, wherein an optical state of the liquid crystal reflects visible light.

72. The device according to claim 3, wherein an optical state of the liquid crystal reflects visible light.

73. The device according to claim 4, wherein an optical state of the liquid crystal reflects visible light.

74. The device according to claim 9, wherein an optical state at least one liquid crystal reflects visible light.

75. The device according to claim 15, wherein an optical state of the liquid crystal reflects visible light.

76. The device according to claim 1, wherein an optical state of the liquid crystal reflects IR light.

77. The device according to claim 3, wherein an optical state of the liquid crystal reflects IR light.

78. The device according to claim 4, wherein an optical state of the liquid crystal reflects IR light.

79. The device according to claim 9, wherein an optical state at least one liquid crystal reflects IR light.

80. The device according to claim 15, wherein an optical state of the liquid crystal reflects IR light.

81. The device according to claim 1, wherein an optical state of the liquid crystal scatters ultra-violet light.

82. The device according to claim 3, wherein an optical state of the liquid crystal scatters ultra-violet light.

83. The device according to claim 4, wherein an optical state of the liquid crystal scatters ultra-violet light.

84. The device according to claim 9, wherein an optical state of at least one liquid crystal scatters ultra-violet light.

85. The device according to claim 15, wherein an optical state of the liquid crystal scatters ultra-violet light.

86. The device according to claim 1, wherein an optical state of the liquid crystal scatters visible light.

87. The device according to claim 3, wherein an optical state of the liquid crystal scatters visible light.

88. The device according to claim 4, wherein an optical state of the liquid crystal scatters visible light.

89. The device according to claim 9, wherein an optical state of at least one liquid crystal scatters visible light.

90. The device according to claim 15, wherein an optical state of the liquid crystal scatters visible light.

91. The device according to claim 1, wherein an optical state of the liquid crystal scatters IR light.

92. The device according to claim 3, wherein an optical state of the liquid crystal scatters IR light.

93. The device according to claim 4, wherein an optical state of the liquid crystal scatters IR light.

94. The device according to claim 9, wherein an optical state of at least one liquid crystal scatters IR light.

95. The device according to claim 15, wherein an optical state of the liquid crystal scatters IR light.

96. The device according to claim 15, wherein an optical state of the liquid crystal absorbs ULTRA-VIOLET light.

97. The device according to claim 16, wherein an optical state of at least one liquid crystal absorbs ULTRA-VIOLET light.

98. The device according to claim 15, wherein an optical state of the liquid crystal absorbs VISIBLE light.

99. The device according to claim 16, wherein an optical state of at least one liquid crystal absorbs VISIBLE light.

100. The device according to claim 1, further comprising a surfactant.

101. The device according to claim 4, further comprising a surfactant.

102. The device according to claim 15, further comprising a surfactant.

103. The device according to claim 16, further comprising a surfactant.

104. The device according to claim 16, wherein an optical state of said first cholesteric liquid crystal absorbs visible light, and an optical state of said second cholesteric liquid crystal absorbs ultraviolet light.

105. The device according to claim 9, wherein an optical state of said first cholesteric liquid crystal absorbs visible light, and an optical state of said second cholesteric liquid crystal absorbs infrared light.

106. The device according to claim 9, wherein an optical state of said first cholesteric liquid crystal absorbs infrared light, and an optical state of said second cholesteric liquid crystal absorbs ultraviolet light.

107. The device according to claim 10 that absorbs infrared light, visible light, and ultraviolet light.

108. The device according to claim 107 that absorbs infrared light, visible light, and ultraviolet light at a first predetermined voltage applied to said means for changing optical states, and absorbs no more than two of infrared light, visible light, and ultra violet light at a second predetermined voltage applied to said means for changing optical states.

109. The device according to claim 4, wherein the photo initiator is a visible photo initiator.

110. The device according to claim 4, wherein the photo initiator is a UV photo initiator.

111. An electro-optically active device comprising two identical cholesteric devices according to claim 4, and a half-wavelength retarder being arranged between the two cholesteric crystal devices.

112. The device according to claim 111, wherein an optical state of at least one the liquid crystal reflects ultra-violet light.

113. The device according to claim 111, wherein an optical state of at least one the liquid crystal scatters ultra-violet light.

114. The device according to claim 111, wherein an optical state of at least one the liquid crystal reflects visible light.

115. The device according to claim 111, wherein an optical state of at least one the liquid crystal reflects IR light.

116. The device according to claim 111, wherein an optical state of at least one the liquid crystal scatters visible light.

117. The device according to claim 111, wherein an optical state of at least one the liquid crystal scatters IR light.

118. The electro-optically active device according to claim 9, further comprising a half-wavelength retarder being arranged between the two cholesteric crystal devices.

119. The device according to claim 118, wherein an optical state of at least one the liquid crystal reflects ultra-violet light.

120. The device according to claim 118, wherein an optical state of at least one the liquid crystal scatters ultra-violet light.

121. The device according to claim 118, wherein an optical state of at least one the liquid crystal reflects visible light.

122. The device according to claim 118, wherein an optical state of at least one the liquid crystal reflects IR light.

123. The device according to claim 118, wherein an optical state of at least one the liquid crystal scatters IR light.

124. An electro-optically active device comprising two identical cholesteric devices according to claim 15, and a half-wavelength retarder being arranged between the two cholesteric crystal devices.

125. The device according to claim 15, wherein an optical state of the liquid crystal absorbs IR light.

126. The device according to claim 16, wherein an optical state of at least one liquid crystal absorbs IR light.

127. The device according to claim 124, wherein an optical state of at least one the liquid crystal absorbs IR light.

128. The device according to claim 16, wherein an optical state of at least one the liquid crystal absorbs IR light.

129. The device according to claim 124, wherein an optical state of at least one the liquid crystal absorbs VISIBLE light.

130. The device according to claim 124, wherein an optical state of at least one the liquid crystal absorbs ULTRA-VIOLET light.

131. The electro-optically active device according to claim 16, further comprising a half-wavelength retarder being arranged between the two cholesteric crystal devices.

132. The device according to claim 131, wherein an optical state of at least one the liquid crystal absorbs VISIBLE light.

133. The device according to 124, wherein an optical state of at least one the liquid crystal absorbs ULTRA-VIOLET light.

134. The device according to claim 1, wherein said means for changing optical states comprises electrodes which are patterned.

135. The device according to claim 3, wherein the first and second electrodes are patterned.

136. The device according to claim 9, wherein the first and second electrodes are patterned.

137. The device according to claim 15, wherein the first and second electrodes are patterned.

138. The device according to claim 111, wherein the first and second electrodes are patterned.

139. The device according to claim 118, wherein the first and second electrodes are patterned.

140. The device according to claim 1, wherein said means for changing optical states comprises electrodes which are pixilated.

141. The device according to claim 3, wherein the first and second electrodes are pixilated.

142. The device according to claim 9, wherein the first and second electrodes are pixilated.

143. The device according to claim 15, wherein the first and second electrodes are pixilated.

144. The device according to claim 91, wherein the first and second electrodes are pixilated.

145. The device according to claim 98, wherein the first and second electrodes are pixilated.

146. The device according to claim 101, wherein the first and second electrodes are pixilated.

147. The device according to claim 122, wherein the first and second electrodes are pixilated.

148. The device according to claim 123, wherein the first and second electrodes are pixilated.

149. The device according to claim 124, wherein the first and second electrodes are

150. A method for producing a cholesteric crystal device comprising the steps of:

(a) providing two optically transparent substrates to form a cell;

(b) providing a liquid crystal having portions adapted for producing a plurality of optical states, said liquid crystal being arranged between the two optically transparent substrates;

(c) providing means for changing optical states of respective portions of said liquid crystal to produce a range of respective optical states including all optical states produced by said liquid crystal ranging from one state to any combination of broadband/reflection, tunable narrow band reflection, light scattering, and transparency in accordance with an amount of voltage applied across said means for changing optical states.

151. The method according to claim 150, wherein the liquid crystal provided in step (b) comprises wherein said liquid crystal is a composite material consisting of a crosslinkable liquid crystal material, a chiral additive, and a photo initiator.

152. The method according to claim 150, wherein the liquid crystal further comprises a first dichroic dye, and said range of respective optical states includes light absorption.

153. The method according to claim 150, wherein the photo initiator operates under visible light.

154. The method according to claim 150, wherein the photo initiator operates under UV light.

155. The method according to claim 150, wherein the liquid crystal is adapted for producing a plurality of optical states in step (b) by:

(i) preparing the composite mixture material;

(ii) filling the composite mixture the cell, said cell having an Indium-Tin-Oxide (ITO) and rubbed polyimide coating; and

(iii) exposing the cell to ultraviolet light for a predetermined period for photo polymerization.

156. The method according to claim 153, wherein the liquid crystal is adapted for producing a plurality of optical states in step (b) by:

(i) preparing the composite mixture material;

(ii) filling the composite mixture in the cell, said cell having an Indium-Tin-Oxide (ITO) and a rubbed polyimide coating; and

(iii) exposing the cell to visible light a predetermined period for photo polymerization.

157. The method according to claim 155, wherein the cell has more of a rubbed polyimide coating on a first of said two substrates than on a second of said two substrates.

158. The method according to claim 156, wherein the cell has more of a rubbed polyimide coating on a first of said two substrates than on a second of said two substrates.

159. A method for producing an electro-optically active device comprising three cholesteric liquid crystal devices comprising the liquid crystal according to claim 151, said method comprising:

providing a right-handed multi-state cholesteric liquid crystal (CLC) device;

providing a left-handed multi-state cholesteric liquid crystal device (CLC); and

providing a third liquid crystal device arranged between said right-handed CLC device and said left handed CLC device; and

is introducing a dichroic dye into said third liquid crystal device.

160. A method for producing an electro-optically active device comprising three cholesteric liquid crystal devices comprising the liquid crystal according to claim 152, said method comprising:

providing a right-handed multi-state cholesteric liquid crystal (CLC) device;

providing a left-handed multi-state cholesteric liquid crystal device (CLC); and

providing a third liquid crystal device arranged between said right-handed CLC device and said left handed CLC device; and

introducing a second dichroic dye into said one of said liquid crystal devices of said electro-optically active device.

161. The method according to claim 160, further comprising:

introducing a third dichroic dye so that all three of the liquid crystal devices have a dichroic dye, wherein each of the dichroic dyes have different concentrations.

162. The method according to claim 161, wherein the means for changing the optical states includes providing voltages ranging from zero to a predetermined value.

163. The method according to claim 161, wherein the means for changing the optical states includes providing voltages ranging from zero to a predetermined value.

164. The method according to claim 162, wherein the means for changing the optical states includes providing voltages ranging from zero to a predetermined value.

165. The method according to claim 159, wherein the means for changing the optical states includes providing voltages ranging from zero to a predetermined value.

166. The method according to claim 160, wherein the means for changing the optical states includes providing voltages ranging from zero to a predetermined value.

167. The method according to claim 161, wherein the means for changing the optical states includes providing voltages ranging from zero to a predetermined value.

168. The method according to claim 160, further comprising (d) introducing a surfactant for reducing response time.

169. The method according to claim 160, further comprising introducing a surfactant for reducing response time.

170. The method according to claim 162, further comprising introducing a surfactant for reducing response time.