Patent ID: 7532283

Claim:
A liquid crystal display device comprising a pair of polarization plates each including a polarizer and a pair of protective layers laminated over the polarizer to protect the latter, the transmission axes of the polarizers being orthogonal to each other, and a liquid crystal plate disposed between the polarization plates and including a liquid crystal layer having the molecules thereof aligned parallel with the absorption axis of one of the polarization plates, wherein: each of the protective layers in the pair of polarization plate is a uniaxial retardation film whose thickness is d TAC0 , laminated over at least the liquid crystal layer, having the optical axis thereof extended in the direction of its thickness and which is generally isotropic in a plane perpendicular to the thickness direction to perform as a negative retardation film whose thickness-directional refractive index nzt is smaller than an in-plane-directional refractive index nxy; and there is disposed between the liquid crystal plane and any one of the polarization plates a biaxial retardation film of thickness d RF that compensates the dependence upon the viewing angle of the protective layer upon which light forming an angle with the viewing-angular direction is incident, wherein the biaxial retardation film has a refractive index of nx>nz>ny and generally meets a relation nz=(nx+ny)/2 (where nz is a refractive index in the direction of thickness, nx is maximum refractive index in a plane perpendicular to the thickness direction and ny is a refractive index in a direction perpendicular to a direction for the maximum refractive index nx and thickness direction for a refractive index nz); and on the assumption that with a predetermined wavelength λ in the visible light domain, the in-plane light path length difference Δnd RF of the retardation film is (nx−ny)d RF and absolute value Δnd TAC0 of the negative light path length difference of the protective layers is (nxy−nzt)d TAC0 , the direction of the retardation film for the maximum refractive index nx coincides with the direction in which the liquid crystal molecules are aligned for the abnormal light refractive index and the plane-directional light path length difference Δnd RF of the retardation film is given nearly by the following equation: Δ ⁢ ⁢ nd RF = λ 2 ⁢ ⁢ π [ π - 2 ⁢ ⁢ tan - 1 ⁡ ( 4 ⁢ ⁢ π λ ⁢ Δ ⁢ ⁢ nd TAC ⁢ ⁢ 0 ) ] .