Reflective liquid crystal device
AssigneeSharp Kabushiki Kaisha
InventorsMartin David Tillin, Michael John Towler, Kirstin Ann Saynor, Sandra Gilmour
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Abstract
A reflective liquid crystal device comprises a polariser and a mirror between which are disposed several retarder. At least one of the retarders is a variable liquid crystal element whose optic axis is switchable so as to switch the device between a reflective sate and a non-reflective state. In the non-reflective state, the total retardance of the retarders between the polariser and the mirror is equal to an odd number of quarter wavelengths for a wavelength at or adjacent the middle of the visible spectrum.
Claims47
A reflective liquid crystal device, comprising:
- a linear polariser;
- a polarisation preserving reflector;
- and
- a retarder arrangement,
- wherein the retarder arrangement includes at least three retarders, a first of which is disposed between the polariser and the reflector, a second of which is disposed between the first retarder and the reflector, and a third of which is disposed between the second retarder and the reflector, at least one of the first, second and third retarders including a liquid crystal layer which is switchable to achieve a non-reflective state of the reflective liquid crystal device, in which the retardation of the retarder arrangement is equal to (2n+1)λ/4 where n is an integer and λ is a wavelength of visible light, and a reflective state of the reflective liquid crystal device.
A reflective liquid crystal device, comprising:
- a linear polariser;
- a polarisation preserving reflector;
- and
- a retarder arrangement including a first retarder disposed between the polariser and the reflector and a second retarder disposed between the first retarder and the reflector, at least one of the first and second retarders including an untwisted liquid crystal layer which is switchable to achieve a non-reflective state of the reflective liquid crystal device, in which the retardation of the retarder arrangement is equal to (2n+1)λ/4 where n is an integer and λ is a wavelength of visible light, and a reflective state of the reflective liquid crystal device,
- wherein the first retarder includes the liquid crystal layer and has an optic axis which rotates during switching by a predetermined angle about the normal direction of light passage.
Dependencies are inferred from the claim text.