Liquid crystal display device and method of fabrication
AssigneeSeiko Epson Corporation
InventorsHiroshi Wada, Shinji Wada, Chiyoaki Iijima
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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 while light in the OFF state and appears black in the ON state.
Claims38
A liquid crystal display device, comprising:
- a first 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 polarized having an axis 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 for compensating for the elliptical polarization of the light passing through the liquid crystal cell to produce substantially linear polarized light leaving the device.
A liquid crystal device comprising two polarizers, a first twisted nematic liquid crystal cell having two electrode substrates, and a second twisted nematic crystal cell which is disposed between a first of the two electrode substrates and a first of two polarizers;
- the second of the two electrode substrates adjacent to the second of the two polarizers wherein the first and second twisted nematic liquid crystal cells have nematic liquid crystal materials twisted in different directions;
- the nematic liquid crystal material of the first twisted nematic crystal cell having a twist angle of between 170.degree. to 350.degree. and a birefringence and layer thickness whose product is between 0.6 and 1.5 micrometers;
- each of the two electrode substrates having a rubbing direction, each of the two polarizers having a polarizing axis and the second twisted nematic crystal cell having an optical axis;
- a rubbing direction of the second of the two electrode substrates and the direction of the polarizing axis of the second of the two polarizers being angularly displaced from each other by between about 30.degree. and 60.degree.;
- the direction of the optical axis of the second twisted nematic crystal cell being angularly displaced from the direction of the polarizing axis of the first of the two polarizers by between about 30.degree. and 60.degree. and the direction of the optical axis of the second twisted nematic crystal cell being angularly displaced from the rubbing direction of the first of the two electrode substrates by between about 80.degree. and 100.degree..
A method of fabricating a liquid crystal display device, comprising:
- displacing a twisted nematic liquid crystal material having a twist angle of greater than 120.degree. in the space between two electrode substrates to form a cell;
- placing a first optically anisotropic means which is without electrodes adjacent to one of the two electrode substrates;
- and
- sandwiching the liquid crystal cell and the optically anisotropic means between two polarizers.
An electro-optical device for use in combination with a voltage source comprising:
- liquid crystal cell means including a twisted nematic liquid crystal material for producing a colored display in response to application of a voltage from the voltage source across the liquid crystal material, characterized by parameters including a twist angle and the product of refractive index anisotropy .DELTA.n and layer thickness d;
- and
- compensating means adjacent to the liquid crystal cell means for compensating for color of said display and having a twist angle differing in magnitude from the magnitude of the twist angle of the liquid crystal cell means.
Dependencies are inferred from the claim text.