Patent ID: 7466382

Claim:
A liquid crystal display in IPS mode, wherein an optical film is arranged on a cell substrate on a viewing side, a polarizing plate comprising a transparent protective film laminated on both sides of a polarizer is arranged on a cell substrate opposite to the viewing side, and an extraordinary refractive index direction of a liquid crystalline substance in a liquid crystal cell and an absorption axis of the polarizing plate are parallel, in a state where voltage is not applied, wherein the optical film is a laminate in which plural retardation films are laminated on one side of a polarizing plate obtained by laminating a transparent protective film on both sides of a polarizer so that a retardation film (a) and a retardation film (b) are laminated in this order from the polarizing plate side so that the slow axes of the plural retardation films are parallel to one another and the absorption axis of the polarizing plate is parallel to the slow axes of the two retardation films, an Nz value expressed by Nz=(nx 1 −nz 1 )/(nx 1 −ny 1 ) is in the range of from 0.72 to 0.78 for the retardation film (a) and in the range of from 0.22 to 0.28 for retardation film (b), and an in-plane retardation Re 1 expressed by Re 1 =(nx 1 −ny 1 )×d 1 is in the range of from 200 to 350 nm, where in each of the plural retardation films, a direction along with the refractive index in the film plane is maximum is defined as the X-axis, a direction perpendicular to the X-axis as the Y-axis, the thickness direction of the film as the Z-axis, and where refractive indices in each axial direction are defined as nx 1 , ny 1 , and nz 1 , respectively, and the thickness of the film as d 1 (nm), wherein the transparent protective film laminated on at least one side of the polarizing plate comprises a thermoplastic resin (A) having a substituted and/or non-substituted imide group in a side chain and a thermoplastic resin (B) having substituted and/or non-substituted phenyl group, and nitrile group in a side chain; and wherein an in-plane retardation expressed by Re 2 =(nx 2 −ny 2 )×d 2 is 20 nm or less, and a thickness direction retardation expressed by Rth={(nx 2 +ny 2 )/2−nz 2 }×d 2 is 30 nm or less, where in the transparent protective film laminated on at least one side of the polarizing plate, a direction along with the refractive index in the film plane is maximum is defined as the X-axis, a direction perpendicular to the X-axis as the Y-axis, the thickness direction of the film as the Z-axis, and where refractive indices in each axial direction are defined as nx 2 , ny 2 , and nz 2 , respectively, and the thickness of the film as d 2 (nm), and wherein the optical film is arranged so that the retardation films are laminated on the liquid crystal cell-side of the polarizing plate.