Patent ID: 6667835
Filing Date: 2003-12-23
Classification: G02B,G02F

Abstract:
An optical film comprising a laminate of first, second and third birefringent films, said first birefringent film exhibiting refractive index dispersion in accordance with a wavelength of light and exhibiting Nz of from 0.4 to 0.6, said second birefringent film exhibiting larger refractive index dispersion in accordance with the wavelength of light than that of said first birefringent film and exhibiting smaller Re than that of said first birefringent film and Nz of from 0.4 to 0.6, said third birefringent film exhibiting Re of from 200 to 350 nm and exhibiting Nz of from 0.6, not inclusively, to 0.9, said first and second birefringent films having slow axes crossing each other perpendicularly when Re=(nxâˆ’ny) d and Nz=(nxâˆ’nz)/(nxâˆ’ny) in which nz is a refractive index of each birefringent film in a direction of a Z axis expressing a direction of a thickness of said birefringent film, nx is a refractive index of said birefringent film in a direction of an X axis expressing a direction of a maximum refractive index of said birefringent film in a plane perpendicular to said Z axis, ny is a refractive index of said birefringent film in a direction of a Y axis expressing a direction perpendicular both to said X axis and to said Z axis, and d is the thickness of said birefringent film.