Abstract: A polyimide film having a biaxial optical anisotropy and excellent durability is provided. A solution of polyimide having an imidization ratio of 98% to 100% is applied onto a plastic base, and then the solution is dried, thus forming a polyimide coating. Subsequently, the polyimide coating is stretched together with the plastic base so as to satisfy nx>ny>nz, wherein nx and ny indicate a refractive index in a direction exhibiting a maximum refractive index within a plane and that in a direction perpendicular thereto and nz indicates a refractive index in a thickness direction.

Abstract: A method of manufacturing a birefringent film is provided, by which a birefringent film including a liquid crystal compound birefringent layer and another birefringent layer can be manufactured so as to have a reduced thickness in a reduced number of process steps. In the manufacturing method, a non-liquid crystal polymer birefringent layer that has been subjected to an aligning treatment is used as an alignment layer for a liquid crystal compound. According to the manufacturing method, the process step of separately preparing an alignment layer and the need for the additional alignment layer can be eliminated, thereby allowing the total thickness of the birefringent film to be reduced.

Abstract: The present invention provides a laminated retardation plate that shows an excellent viewing angle property when used in a liquid crystal display, and that can be decreased in thickness. The laminated retardation plate is formed by laminating an optically anisotropic layer (A) made of a polymer having an in-plane retardation of 20-300 nm and a ratio between a thickness direction retardation and the in-plane retardation of not less than 1.0, and an optically anisotropic layer (B) made of a non-liquid crystalline polymer such as polyimide having an in-plane retardation of not less than 3 nm and a ratio between a thickness direction retardation and the in-plane retardation of not less than 1.0. The thus obtained laminated retardation plate shows excellent optical properties, e.g., an in-plane retardation (Re) of 10 nm or more, and a difference between a thickness direction retardation and the in-plane retardation of 50 nm or more.

Abstract: An optical sheet constituted by a retardation film; and a transparent layer provided on one of opposite surfaces of the retardation film. The retardation film exhibits Nz=(nx?nz)/(nx?ny) in a range of from 0.6 to 0.9 and (nx?ny)d in a range of from 200 to 350 nm in which d is a thickness of the retardation film, nz is a refractive index in a direction of a Z axis expressing a direction of the thickness d of the retardation film, nx is a refractive index in a direction of an X axis expressing a direction of the retardation film in a plane perpendicular to the Z axis while the X axis also expresses a direction of the highest in-plane refractive index, and ny is a refractive index in a direction of a Y axis expressing a direction of the retardation film perpendicular both to the Z axis and to the X axis. The transparent layer has a thickness not larger than 10 ?m and exhibits refractive index anisotropy of nx?ny>nz.

Abstract: It is an object of the present invention to provide a method for manufacturing a birefringent film that can reduce the amount of a remaining solvent in the birefringent film without degrading appearance uniformity or an alignment in its thickness direction. The method of the present invention for manufacturing an optical film includes the steps of coating a base with a polymer solution obtained by dissolving a polyimide-containing polymer in a solvent so as to form a coating film; and drying the coating film so as to form a birefringent film, in which the drying step includes at least two stages of drying processes. The drying step preferably include two stages of the drying processes, and a temperature in the former stage of the drying process is preferably lower than a temperature in the latter stage of the drying process. If adding a step of providing the birefringent film with an anisotropy of a refractive index in an in-plane direction, a birefringent film with an optical biaxiality can be manufactured.

Abstract: An optical member has a polarizer, a viewing angle compensating plate, and an adhesive layer which has a refractive index ND20 not lower than 1.485 and through which the polarizer and the viewing angle compensating plate are laminated on each other. A liquid-crystal display device has at least one optical member defined above, a liquid-crystal cell, and an adhesive layer which has a refractive index ND20 not lower than 1.485 and through which the optical member is bonded onto at least one of opposite surfaces of the liquid-crystal cell.

Abstract: The present invention provides a transparent optical film that has excellent optical characteristics for realizing the uniform retardation distribution and restraining rainbow-colored irregularities. The optical film, which is obtained by laminating a birefringent layer (a) on a transparent film (b), satisfies all the following formulae (I), (II) and (III). ?n(a)>?n(b)×10??(I) 1<(nx?nz)/(nx?ny)??(II) 0.0005<?n(a)?0.5??(III) In the above formulae (I), (II) and (III), ?n(a) and ?n(b) denote respectively birefringent indexes of the birefringent layer (a) and the transparent film (b). The signs of nx, ny and nz indicate refractive indexes in an X-axis direction, a Y-axis direction and a Z-axis direction in the birefringent layer (a), respectively.

Abstract: An elliptically polarizing plate, comprising a polarizer, a first optical anisotropic layer having positive refractive index anisotropy and an optical axis of the anisotropy that is tilted, and a second optical anisotropic layer having negative refractive index anisotropy and an optical axis that is tilted, have accurate retardation compensation of a liquid crystal cell, and the liquid crystal display maintains a display contrast having a sufficient visibility when the viewing angle is changed and which does not generate colorization.

Abstract: The present invention provides a birefringent optical film having a high orientation for easily obtaining a desired retardation value and also a small photoelastic coefficient. The birefringent optical film includes at least two kinds of polymer materials.

Abstract: The present invention provides a birefringent optical film having a high orientation for easily obtaining a desired retardation value and also a small photoelastic coefficient. The birefringent optical film includes at least two kinds of polymer materials.

Abstract: An optical sheet is constituted by: a retardation film; and a transparent layer provided on one of opposite surfaces of the retardation film. The retardation film exhibits Nz=(nx−nz)/(nx−ny) in a range of from 0.4 to 0.6, both not inclusively, and (nx−ny)d in a range of from 200 to 350 nm when nx>ny in which d is the thickness of the retardation film, nz, nx and ny are a refractive index in a direction of the thickness d of the retardation film, a refractive index in a direction of the retardation film in the same plane as the direction of nx, and a refractive index in a direction of the retardation film in the same plane as the direction of nx, respectively. The transparent layer has a thickness not larger than 10 &mgr;m and exhibits refractive index anisotropy of nx≈ny>nz.

Abstract: A laminated optical device is a laminate formed of a polarizing layer having a thickness of not larger than 5 &mgr;m, and at least one birefringent layer including either a solid film of oriented liquid crystal or a polymer layer containing oriented liquid crystal. A liquid-crystal display apparatus includes a liquid-crystal display panel, and at least one laminated optical device defined above and disposed on one of opposite surfaces of the liquid-crystal display panel.

Abstract: An optical sheet constituted by a retardation film; and a transparent layer provided on one of opposite surfaces of the retardation film. The retardation film exhibits Nz=(nx =nz)/(nx=ny) in a range of from 0.1 to 0.4 and (nx−ny)d in a range of from 200 to 350 nm in which d is a thickness of the retardation film, nz is a refractive index in a direction of a Z axis expressing a direction of the thickness d of the retardation film, nx is a refractive index in a direction of an X axis expressing a direction of the retardation film in a plane perpendicular to the Z axis while the X axis also expresses a direction of the highest in-plane refractive index, and ny is a refractive index in a direction of a Y axis expressing a direction of the retardation film perpendicular both to the is Z axis and to the X axis. The transparent layer has a thickness not larger than 10 &mgr;m and exhibits refractive index anisotropy of nx˜ny>nz.

Abstract: A laminated optical device is a laminate formed of a polarizing layer having a thickness of not larger than 5 &mgr;m, and at least one birefringent layer including either a solid film of oriented liquid crystal or a polymer layer containing oriented liquid crystal. A liquid-crystal display apparatus includes a liquid-crystal display panel, and at least one laminated optical device defined above and disposed on one of opposite surfaces of the liquid-crystal display panel.

Abstract: An elliptically polarizing plate, comprising a polarizer, a first optical anisotropic layer having positive refractive index anisotropy and an optical axis of the anisotropy that is tilted, and a second optical anisotropic layer having negative refractive index anisotropy and an optical axis that is tilted, have accurate retardation compensation of a liquid crystal cell, and the liquid crystal display maintains a display contrast having a sufficient visibility when the viewing angle is changed and which does not generate colorization.

Abstract: An optical member has a polarizer, a viewing angle compensating plate, and an adhesive layer which has a refractive index ND20 not lower than 1.485 and through which the polarizer and the viewing angle compensating plate are laminated on each other. A liquid-crystal display device has at least one optical member defined above, a liquid-crystal cell, and an adhesive layer which has a refractive index ND20 not lower than 1.485 and through which the optical member is bonded onto at least one of opposite surfaces of the liquid-crystal cell.

Abstract: An optical device including a laminate of cholesteric liquid-crystal layers in which the wavelength ranges of selective reflection of circularly polarized light beams are out of visible light region and which are combined so that circularly polarized light beams transmitted through the cholesteric liquid-crystal layers to be left-handed and right-handed are inverted to each other. A liquid-crystal display apparatus including a vertically aligned liquid-crystal cell, polarizers disposed on opposite surfaces of the liquid-crystal cell, and one or two optical devices defined above and interposed between the liquid-crystal cell and either or each of the polarizers.

Abstract: An optical sheet constituted by a retardation film; and a transparent layer provided on one of opposite surfaces of the retardation film. The retardation film exhibits Nz=(nx=nz)/(nx=ny) in a range of from 0.1 to 0.4 and (nx−ny)d in a range of from 200 to 350 nm in which d is a thickness of the retardation film, nz is a refractive index in a direction of a Z axis expressing a direction of the thickness d of the retardation film, nx is a refractive index in a direction of an X axis expressing a direction of the retardation film in a plane perpendicular to the Z axis while the X axis also expresses a direction of the highest in-plane refractive index, and ny is a refractive index in a direction of a Y axis expressing a direction of the retardation film perpendicular both to the is Z axis and to the X axis. The transparent layer has a thickness not larger than 10 &mgr;m and exhibits refractive index anisotropy of nx∓ny>nz.

Abstract: An optical sheet is constituted by: a retardation film; and a transparent layer provided on one of opposite surfaces of the retardation film. The retardation film exhibits Nz=(nx−nz)/(nx−ny) in a range of from 0.4 to 0.6, both not inclusively, and (nx-ny)d in a range of from 200 to 350 nm when nx>ny in which d is the thickness of the retardation film, nz, nx and ny are a refractive index in a direction of the thickness d of the retardation film, a refractive index in a direction of the retardation film in the same plane as the direction of nx, and a refractive index in a direction of the retardation film in the same plane as the direction of nx, respectively. The transparent layer has a thickness not larger than 10 &mgr;m and exhibits refractive index anisotropy of nx≈ny>nz.

Abstract: An optical sheet constituted by a retardation film; and a transparent layer provided on one of opposite surfaces of the retardation film. The retardation film exhibits Nz=(nx−nz)/(nx−ny) in a range of from 0.6 to 0.9 and (nx−ny)d in a range of from 200 to 350 nm in which d is a thickness of the retardation film, nz is a refractive index in a direction of a Z axis expressing a direction of the thickness d of the retardation film, nx is a refractive index in a direction of an X axis expressing a direction of the retardation film in a plane perpendicular to the Z axis while the X axis also expresses a direction of the highest in-plane refractive index, and ny is a refractive index in a direction of a Y axis expressing a direction of the retardation film perpendicular both to the Z axis and to the X axis. The transparent layer has a thickness not larger than 10 &mgr;m and exhibits refractive index anisotropy of nx≈ny>nz.