Electrooptical liquid crystal system containing dual frequency liquid crystal mixture
First Claim
1. An electrooptical liquid crystal system comprising:
- a dual frequency liquid crystal mixture having a cross-over frequency fc and an optically transparent polymeric medium positioned between two electrode layers, said layers each being optionally attached to substrates;
wherein the ordinary refractive index of said liquid crystal mixture essentially agrees with the refractive index of said polymeric medium nm, the quotient of the mass of said liquid crystal mixture and of the mass of the polymeric medium is 1.5 or more, or said ordinary refractive index of said liquid crystal mixture essentially agrees with the refractive index of said polymeric medium nm and said quotient is 1.5 or more;
wherein said system has a reduced transmission in the on-state compared to the off-state;
wherein said system is obtained by polymerization of a composition containing said dual frequency liquid crystal mixture and a precursor of said polymeric medium; and
during curing of said composition, an electrical field exhibiting a frequency below said cross-over frequency fc of said dual frequency liquid crystal mixture is applied to said composition whereby the molecules of said dual frequency liquid crystal mixture are aligned essentially in the direction of said electrical field.
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Abstract
The invention relates to an electrooptical liquid crystal system
which contains a dual frequency liquid crystal mixture and a further optically transparent polymeric medium between two electrode layers which optionally may be attached to substrates,
in which the ordinary refractive index of the liquid crystal mixture essentially agrees with the refractive index of the polymeric medium nm and/or in which the quotient of the mass of the liquid crystal mixture and of the mass of the polymeric medium is 1.5 or more,
which has a reduced transmission in the on-state compared to the off-state, and
which is obtained by polymerization of a composition containing the dual frequency liquid crystal mixture and a precursor of the polymeric medium,
characterized in that an electrical field is applied during the curing process which exhibits a frequency below the cross-over frequency of the dual frequency liquid crystal mixture so that the molecules of the dual frequency liquid crystal mixture are aligned essentially into the direction of the electrical field.
107 Citations
21 Claims
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1. An electrooptical liquid crystal system comprising:
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a dual frequency liquid crystal mixture having a cross-over frequency fc and an optically transparent polymeric medium positioned between two electrode layers, said layers each being optionally attached to substrates; wherein the ordinary refractive index of said liquid crystal mixture essentially agrees with the refractive index of said polymeric medium nm, the quotient of the mass of said liquid crystal mixture and of the mass of the polymeric medium is 1.5 or more, or said ordinary refractive index of said liquid crystal mixture essentially agrees with the refractive index of said polymeric medium nm and said quotient is 1.5 or more; wherein said system has a reduced transmission in the on-state compared to the off-state; wherein said system is obtained by polymerization of a composition containing said dual frequency liquid crystal mixture and a precursor of said polymeric medium; and during curing of said composition, an electrical field exhibiting a frequency below said cross-over frequency fc of said dual frequency liquid crystal mixture is applied to said composition whereby the molecules of said dual frequency liquid crystal mixture are aligned essentially in the direction of said electrical field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A process for preparing of an electrooptical liquid crystal system comprising:
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inserting a composition containing a dual frequency liquid crystal mixture, a precursor of an optically transparent polymeric medium, and optionally a reactive liquid crystalline component between electrode layers, said electrode layers each being optionally attached to substrates; said dual frequency liquid crystal mixture having a cross-over frequency fc ; wherein the ordinary refractive index of said liquid crystal mixture essentially agrees with the refractive index of said polymeric medium nm, the quotient of the mass of said liquid crystal mixture and of the mass of the polymeric medium is 1.5 or more, or said ordinary refractive index of said liquid crystal mixture essentially agrees with the refractive index of said polymeric medium nm and said quotient is 1.5 or more; applying a voltage to said electrode layers, said voltage exhibiting a frequency below said cross-over frequency fc of said dual frequency liquid crystal mixture whereby the molecules of said dual frequency liquid crystal mixture are aligned essentially in the direction of the electrical field formed by the application of said voltage; and polymerizing said precursor while maintaining said electrical field, to obtain said system wherein said system has a reduced transmission in the on-state compared to the off-state.
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21. An electrooptical liquid crystal system comprising:
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a dual frequency liquid crystal mixture having a cross-over frequency fc and an optically transparent polymeric medium positioned between two electrode layers, said layers each being optionally attached to substrates; wherein the ordinary refractive index of said liquid crystal mixture essentially agrees with the refractive index of said polymeric medium nm, the quotient of the mass of said liquid crystal mixture and of the mass of the polymeric medium is 1.5 or more, or said ordinary refractive index of said liquid crystal mixture essentially agrees with the refractive index of said polymeric medium nm and said quotient is 1.5 or more; wherein said system exhibits its highest transmission in the off-state and reduced transmission in the on-state; wherein said system is obtained by polymerization of a composition containing said dual frequency liquid crystal mixture and a precursor of said polymeric medium; and during curing of said composition, an electrical field exhibiting a frequency below said cross-over frequency fc of said dual frequency liquid crystal mixture is applied to said composition whereby the molecules of said dual frequency liquid crystal mixture are aligned essentially in the direction of said electrical field.
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Specification