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US 4,909,606 AGranted
Liquid crystal display device
AssigneeSeiko Epson Corporation
InventorsHiroshi Wada, Shinji Wada, Chiyoaki Iijima
Life of this patent
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Abstract
A liquid crystal display device and method of fabrication thereof includes a first twisted nematic liquid crystal cell and an optically anisotropic material sandwiched between two polarizers. A second twisted nematic liquid crystal cell or polymer film serves as the optically anisotropic material. The optically anisotropic material may be disposed on one or both sides of the first twisted nematic liquid crystal. The optically anisotropic material compensates for the elliptical polarization of the light passing through the liquid crystal cell so that the device transmits white light in the OFF state and appears black in the ON state.
Claims29
A liquid crystal display device, comprising:
- a twisted nematic liquid crystal display cell including a pair of spaced apart opposed transparent substrates with transparent electrodes selectively disposed thereon, the opposed substrates each having a liquid crystal orientation direction, a twisted nematic liquid crystal material having a twist angle greater than 120.degree. disposed in the space between the substrates;
- a linear polarizer having axes of polarization disposed on each side of the liquid crystal cell, at least one axis of polarization at an angle to the orientation direction of the adjacent electrode substrate so that incident linearly polarized light passing through the polarizer causes birefringence in the liquid crystal material and emits an elliptically polarized light from the cell;
- and
- at least one optically anisotropic means disposed between the liquid crystal cell and one polarizer, each optically anisotropic means having an optically anistropic substance, the optically anisotropic means for compensating for the elliptical polarization of the light passing through the liquid crystal cell to produce substantially linear polarized light leaving the device;
- wherein the twisted nematic liquid crystal material of the liquid crystal cell and the optically anisotropic substance of at least one optically anisotropic means maintain the following relationship:
- 0. 86.ltoreq.T.sub.A /T.sub.B .ltoreq.1.15
- in which T.sub.A is the nematic-isotropic phase transition temperature of the optically anisotropic substance in degrees Kelvin and T.sub.B is the nematic-isotropic phase transition temperature of the twisted nematic liquid crystal material in degrees Kelvin.
4 more elements
A liquid crystal display device, comprising:
- twisted nematic liquid crystal display cell including a pair of spaced apart opposed transparent substrates with transparent electrodes selectively disposed thereon, the opposed substrates each having a liquid crystal orientation direction, a twisted nematic liquid crystal material having a twist angle greater than 120.degree. disposed in the space between the substrates;
- a linear polarizer having axes of polarization disposed on each side of the liquid crystal cell, at least one axis of polarization at an angle to the orientation direction of the adjacent electrode substrate so that incident linearly polarized light passing through the polarizer causes birefringence in the liquid crystal material and emits an elliptically polarized light from the cell;
- and
- at least one optically anisotropic means disposed between the liquid crystal cell and one polarizer, the optically anisotropic means having a negative dielectric anisotropy and for compensating for the elliptical polarization of the light passing through the liquid crystal cell to produce substantially linear polarized light leaving the device.
1 more element
A liquid crystal display device, comprising:
- a twisted nematic liquid crystal display cell including a pair of spaced apart opposed transparent substrates with transparent electrodes selectively disposed thereon, the opposed substrates each having a liquid crystal orientation direction, a twisted nematic liquid crystal material having a twist angle greater than 120.degree. disposed in the space between the substrates;
- a linear polarizer having axes of polarization disposed on one side of the liquid crystal cell, at least one axis of polarization at an angle to the orientation direction of the adjacent electrode substrate so that incident linearly polarized light passing through the polarizer causes birefringence in the liquid crystal material and emits an elliptically polarized light from the cell;
- and
- at least one polarized polymer film means disposed adjacent the other side of the liquid crystal cell, the polarized polymer film means for compensating for the elliptical polarization of the light passing through the liquid crystal cell to produce substantially linear polarized light leaving the device.
1 more element
A liquid crystal display device, comprising:
- a twisted nematic liquid crystal display cell including a pair of spaced apart opposed transparent substrates with transparent electrodes selectively disposed thereon, the opposed substrates each having a liquid crystal orientation direction, a twisted nematic liquid crystal material having a twist angle greater than 120.degree. disposed in the space between the substrates;
- and
- two polarized polymer film means having axes of polarization and disposed on each side of the liquid crystal cell, each axis of polarization at an angle to the orientation direction of the adjacent electrode substrate so that incident linearly polarized light passing through one of the polarized film means causes birefringence in the liquid crystal material and emeits an elliptically polarized light from the cell;
- the other of said polarized polymer film means operable for compensating for the elliptical polarization of the light passing through the liquid crystal cell so that substantially linear polarized light is produced by the device.
1 more element
Dependencies are inferred from the claim text.