Patent ID: 8354148

Claim:
An optical compensation polarizing plate comprising: a first transparent protective film; a polarizer; a second transparent protective film; and an optical compensation layer in this order, wherein at least one of the first and second transparent protective films is a cellulose acylate film having a retardation value in plane Re (nm) and a retardation value in film thickness direction Rth (nm) which fulfill the following formulae (I) and (II), and Nz and Re 1 defined by the following formulae (III) and (IV), of the optical compensation layer fulfill the following formulae (V) and (VI): |Re|≦2 (I) |Rth|≦5 (II) Nz=( nx 1 −nz 1 )/( nx 1 −ny 1 ) (III) Re 1 =( nx 1 −ny 1 )× d 1 (IV) 0.45≦Nz≦0.6 (V) 100≦Re 1 ≦350 (VI) wherein Re 1 is a retardation value in plane (nm) at a wavelength of 590 nm; Nz is an Nz factor at a wavelength of 590 nm; nx 1 is a refractive index along a slow axis in a film plane; ny 1 is a refractive index along a direction perpendicular to the slow axis in a film plane; nz 1 is a refractive index along a thickness direction of the film; and d 1 is a thickness of the film (nm), wherein the at least one of the first and second transparent protective films contains at least one compound being capable of lowering the retardation value in a film thickness direction Rth within a range fulfilling both of the following formulae (IX) and (X), and wherein the at least one compound being capable of lowering the retardation value in a film thickness direction Rth is present in an amount which fulfills formula (X): (Rth( A )−Rth(0))/ A≦ 1.0 (IX) 0.1≦ A≦ 30 (X) wherein Rth(A) is Rth (nm) of a film containing A % of the compound being capable of lowering Rth; Rth(0) is Rth (nm) of a film containing no compound being capable of lowering Rth; and A is a mass (%) of the compound referring to a mass of polymers employed as film material as 100.