Patent ID: 7345725

Claim:
An optical compensation film comprising a support exhibiting optical biaxiality, on which at least one optically anisotropic layer is provided, wherein: (i) the optically anisotropic layer is formed by orienting molecules of a liquid crystalline compound in a manner that an average tilt angle of the molecules is not more than 4 degrees followed by fixing the orientation of the liquid crystal molecules; (ii) in-plane retardation values of the optical compensation film Ro(λ) given by Formula (1) are as follows: Ro(589): 40-130 nm Ro(600): 35-125 nm Ro(630): 35-120 nm; (iii) an out-of-plane retardation value in a thickness direction of the optical compensation film Rt(λ) represented by Formula (2) is in the range of 120-400 nm when measured at wavelengths of 500-630 nm; (iv) Ro(589), Ro(600) and Ro(630) satisfy Formula (3); and (v) a ratio of R 70 (589)/Ro(589) is 1.25-1.40 and a ratio of R 50 (589)/Ro(589) is 1.10-1.25, R 70 (589) being a retardation value of the optical compensation film measured by a method of: (a) placing the film parallel to a reference plane; (b) rotating the film 70 degrees on an in-plane delayed phase axis of the film; and (c) measuring the retardation value from a direction perpendicular to the reference plane at a wavelength of 589 nm; R 50 (589) being a retardation value of the optical compensation film measured by the same method as R 70 (589) except that the film being rotated 50 degrees on the in-plane delayed phase axis of the film; and the in-plane delayed phase axis representing an axis of a direction giving a maximum in-plane retardation value: Ro (λ)=( nx (λ)− ny (λ))× d Formula (1) Rt (λ)=(( nx (λ)+ ny (λ))/2 −nz (λ))× d Formula (2) 1.0< B< 7.0 Formula (3) B =( Ro (589)− Ro (630)/( Ro (600)− Ro (630) nx(λ) representing a refractive index in a x direction which gives a maximum refractive index in the plane of the optical compensation film; ny(λ) representing a refractive index in a y direction which is orthogonal to the x direction in the plane of the optical compensation film; nz(λ) representing a refractive index in the thickness direction of the optical compensation film; λ representing a wavelength (nm) at which each measurement is carried out; and d representing a thickness (nm) of the optical compensation film.