To provide a retardation film capable of properly adjusting even phase difference when seen from an oblique direction, having uniformity of in-plane optical characteristics, and also having such uniform optical compensation ability as to ensure no local contrast reduction even in a large liquid crystal display device.
The retardation film comprises one film and ensures a larger frontal phase difference Re at a longer wavelength. The angle between a slow axis direction in the film surface and a flow direction of the film is within ±1.5°. A refractive index in the flow direction of the film at a wavelength of 586.7 nm is larger than a refractive index in the width direction of the film. With respect to a refractive index nx in the slow axis direction in the film surface, a refractive index ny in a quick axis direction and a refractive index nz in the thickness direction, value calculated by (nx-nz)/(nx-ny) is 1.00 to <1.20. In a range 100 mm square in the film surface, a standard deviation of phase difference values measured at 100 points is ≤0.50, and a photoelastic coefficient is 3.0×10-11 m2/N.
SHIRAFUJI FUMIAKI
KURIMOTO KENJI
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