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 light pipe includes a plate-like member having light output means formed in its upper surface so that light incident on an incidence side surface of the plate-like member is exited from the lower surface of the plate-like member through the light output means, an adhesive layer having a refractive index lower than that of the plate-like member, and (i) an anti-reflection layer made of a circularly polarizer and bonded to a lower surface of the plate-like member through the adhesive layer or (ii) a light-diffusing layer having a surface of fine prismatic structures and bonded to a lower surface of the plate-like member through the adhesive layer. A plane light source unit includes at least one light source disposed on one side surface of the light pipe. A reflection type liquid-crystal display device includes the plane light source unit and a liquid-crystal cell including a reflection layer disposed on the light output side of the plane light source unit.

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 liquid-crystal cell substrate constituted by a sheet which has a thickness in a range of from 0.1 to 1 mm and is made of a resin with a glass transition temperature of not lower than 130° C. and provided with light output means on one of upper and lower surfaces of the sheet so that light incident on a side surface is delivered out of the one of the upper and lower surfaces through the light output means. Liquid-crystal cells constituted by two cell substrates, and a liquid crystal enclosed in between the two cell substrates, wherein one of the two cell substrates is constituted by a liquid-crystal cell substrate. A liquid-crystal display device constituted by such liquid-crystal cells.

Abstract: An optical film in which a polarizing plate and a retardation film are laminated so that an absorbing axis of the polarizing plate and a slow axis of the retardation film may be perpendicular or may be parallel to each other, wherein a value Nz represented by Nz=(nx1−nz1)/(nx1−ny1) satisfies a range of 0.4 through 0.6, and an in-plane retardation Re1=(nx1−ny1)×d1 is 200 through 350 nm, where, a direction of the retardation film in which an in-plane refractive index within the film surface concerned gives a maximum is defined as X-axis, a direction perpendicular to X axis is defined as Y-axis, a thickness direction of the film is defined as Z-axis, refractive indexes in axial direction are defined as nx1, ny1, nz1, respectively, and a thickness of the film is defined as d1 (nm), may realize an easily viewable display with high contrast ratio in a wide range when applied to a display system, preferably used for a liquid crystal display operating in IPS mode.

Abstract: An optical film having a laminate of three birefringent films A, B and C, the birefringent film A exhibiting dispersion and exhibiting Nz of from 0.4 to 0.6, the birefringent film B exhibiting larger dispersion than that of the birefringent film A and exhibiting smaller Re that that of the birefringent film A and Nz of from 0.4 to 0.6, the birefringent film C exhibiting Re of from 200 to 350 nm and exhibiting Nz of from 0.6 (not inclusively) to 0.9, the birefringent films A and B having slow axes crossing each other perpendicularly when Re=(nx−ny)d and Nz=(nx−nz)/(nx−ny) in which nx, ny and nz are refractive indices of each birefringent film in three-dimensional directions X, Y and Z, and d is the thickness of the birefringent film.

Abstract: An optical film in which a retardation film is laminated on one side of a polarizing plate, in which a transparent protective film is laminated on both sides of a polarizer, so that an absorbing axis of the polarizing plate and a slow axis of the retardation film may be perpendicular or may be parallel to each other, wherein a value Nz represented by Nz=(nx1−nzi)/(nx1−ny1) satisfies a range of 0.4 through 0.

Abstract: A diffusing adhesive layer has a light-transmissible adhesive layer dispersively containing colorless light-transmissible particles so as to exhibit light diffusing characteristic. The light diffusing characteristic of the diffusing adhesive layer is not higher than 10% in terms of a light diffusion factor which is defined as 100×I30/I10 when I30 is the intensity of light transmitted in a direction inclined by 30 degrees relative to a direction of perpendicular transmission of perpendicularly incident light, and I10 is the intensity of light transmitted in a direction inclined by 10 degrees relative to the direction of perpendicular transmission of perpendicularly incident light. Another diffusing adhesive layer has a total light transmission factor of not lower than 85% and a direct transmission factor of not higher than 30%. In an optical member, one of the diffusing adhesive layers is provided on an optical material having at least a polarizing plate or a retarder plate.

Abstract: A liquid-crystal display device has a light pipe, a light source, a reflection layer, a light diffusion layer, and a liquid-crystal shutter. The light pipe is provided with light output means formed on an upper surface thereof. The light source is disposed near to an incident side surface of the light pipe so that light incident on the light pipe from the light source is delivered from a lower surface of the light pipe through the light output means. The reflection layer is disposed on the lower surface of the light pipe so that reflected light of the output light is transmitted through the upper surface. The light diffusion layer has polarization-keeping characteristic. The liquid-crystal shutter is disposed on the upper surface of the light pipe through the light diffusion layer, the liquid-crystal shutter including liquid-crystal cells and at least one polarizing plate.

Abstract: A light pipe in which light incident on an incident side surface (13) is outputted from a lower surface (12) through a light output means formed on an upper surface (11), the direction of the largest intensity of the light outputted from the lower surface is within an angle of 30 degrees to a normal line with respect to a reference plane of the lower surface, the largest intensity of light leaking from the upper surface in the direction within the angle of 30 degrees is not higher than 1/5 as high as the largest intensity at the lower surface, and the light pipe has a hard coat layer-on the upper surface so that light incident on the lower surface is transmitted from the upper surface; a surface light source device having a light source disposed on the incident side surface of the light pipe; and a reflection type liquid-crystal display device having a liquid-crystal cell provided with a reflection layer disposed on the lower surface side of the surface light source.

Abstract: A diffusing adhesive layer has a light-transmissible adhesive layer dispersively containing colorless light-transmissible particles so as to exhibit light diffusing characteristic. The light diffusing characteristic of the diffusing adhesive layer is not higher than 10% in terms of a light diffusion factor which is defined as 100×I30/I10 when I30 is the intensity of light transmitted in a direction inclined by 30 degrees relative to a direction of perpendicular transmission of perpendicularly incident light, and I10 is the intensity of light transmitted in a direction inclined by 10 degrees relative to the direction of perpendicular transmission of perpendicularly incident light. Another diffusing adhesive layer has a total light transmission factor of not lower than 85% and a direct transmission factor of not higher than 30%. In an optical member, one of the diffusing adhesive layers is provided on an optical material having at least a polarizing plate or a retarder plate.

Abstract: A polarizing plate comprising a polarizer and a transparent protective film at least one surface of the polarizer via an adhesive layer, wherein an applied layer comprising a polymer having a hydroxyl group is formed on a surface of the transparent protective film that is adhered to the polarizer, and the adhesive layer is formed by an adhesive comprising an isocyanate adhesive, has no problem concerning saponification processing and has a good adhesive property between a polarizer and a transparent protective film.

Abstract: An optical film including: a birefringent film A having Re of from 200 to 350 nm and Nz of from 0.6 to 0.9; and a birefringent film B having Re of from 100 to 175 nm and Nz of from 0.3 to 0.7, and laminated on the birefringent film A so that optical axes of the birefringent films A and B intersect each other, in which Re and Nz are given by the relations (nx−ny)d=Re and (nx−nz)/(nx−ny)=Nz, nx, ny and nz are refractive indices of corresponding one of the birefringent films A and B in two directions in a plane of the birefringent film and in a direction of the thickness of the birefringent film, and d is the thickness of the birefringent film. A polarizer including: an optical film defined above; and a film having a polarizing function and laminated on the birefringent film A side of the optical film.

Abstract: An iodine-PVA polarizing element 30 &mgr;m thick is dried by heating at 50° C. for 30 minutes to thereby obtain a polarizing element having a moisture content of 4.9% by weight. A pair of 100 &mgr;m-thick norbornene resin films (tradename “ARTON” made by JSR Corporation) used as protective films are stuck to opposite surfaces of the obtained polarizing element through layers of PVA adhesive agents which are applied on the pair of nonbornene resin films respectively and dried. Thus, a polarizer is obtained.

Abstract: A liquid-crystal cell substrate constituted by a sheet which has a thickness in a range of from 0.1 to 1 mm and is made of a resin with a glass transition temperature of not lower than 130° C. and provided with light output means on one of upper and lower surfaces of the sheet so that light incident on a side surface is delivered out of the one of the upper and lower surfaces through the light output means. Liquid-crystal cells constituted by two cell substrates, and a liquid crystal enclosed in between the two cell substrates, wherein one of the two cell substrates is constituted by a liquid-crystal cell substrate. A liquid-crystal display device constituted by such liquid-crystal cells.

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 optically compensatory polarizer has a polarizer and an optically compensating film. The polarizer includes an absorption type polarizing element and transparent protective layers provided on opposite sides of the absorption type polarizing element, each of the transparent protective layers exhibiting an in-plane retardation of not larger than 10 nm and a thicknesswise retardation in a range of from 30 to 70 nm. The optically compensating film is laminated on one or each of opposite surfaces of the polarizer so that a slow axis of each optically compensating film crosses an absorption axis of the polarizer perpendicularly, and exhibits an in-plane retardation in a range of from 80 to 200 nm and Nz=(nx−nz)/(nx−ny) in a range of from −0.2 to 0.

Abstract: An optical film having a laminate of three birefringent films A, B and C, the birefringent film A exhibiting dispersion and exhibiting Nz of from 0.4 to 0.6, the birefringent film B exhibiting larger dispersion than that of the birefringent film A and exhibiting smaller Re that that of the birefringent film A and Nz of from 0.4 to 0.6, the birefringent film C exhibiting Re of from 200 to 350 nm and exhibiting Nz of from 0.6 (not inclusively) to 0.9, the birefringent films A and B having slow axes crossing each other perpendicularly when Re=(nx−ny)d and Nz=(nx−nz)/(nx−ny) in which nx, ny and nz are refractive indices of each birefringent film in three-dimensional directions X, Y and Z, and d is the thickness of the birefringent film.

Abstract: An optical film having a laminate of a birefringent film A exhibiting refractive index dispersion in accordance with wavelength of light and a birefringent film B exhibiting larger refractive index dispersion in accordance with the wavelength of light than the refractive index dispersion of the birefringent film A, wherein the two birefringent films A and B are laminated on each other so that slow axes of the two birefringent films A and B cross each other perpendicularly in the condition that the two birefringent films A and B are combined with each other so that Re of the birefringent film A is larger than that of the birefringent film B and the sum of Nz of the birefringent film A and Nz of the birefringent film B is in a range of from 0.7 to 1.

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.