Patent ID: 7079204

Claim:
A laminated optical film comprising: an optical film ( 1 ) obtained by stretching a polymer film comprising a polycarbonate resin and a styrene resin, wherein a photoelastic coefficient is 2.0×10 −11 to 6.0×10 −11 m 2 /N, and a three dimensional refractive index is controlled so that an Nz coefficient expressed with Nz=(nx 1 −nz 1 )/(nx 1 −ny 1 ) may satisfy a relationship of Nz≦0.9, and a front retardation (Re)=(nx 1 −ny 1 )×d 1 may satisfy a relationship of Re≧80 nm, when a direction where a refractive index in a film plane gives a maximum is defined as X-axis, a direction perpendicular to the X-axis as Y-axis, a thickness direction of the film as Z-axis, and when refractive indexes in each axial direction are defined as nx 1 , ny 1 , and nz 1 , respectively, and a thickness of the film as d 1 (nm); an optical film ( 2 ) showing optically positive uniaxial property that satisfies a relationship of nx 2 >ny 2 ≅nz 2 , when a direction where a refractive index in a film plane gives a maximum is defined as X-axis, a direction perpendicular to X-axis as Y-axis, a thickness direction of the film as Z-axis, and when refractive indexes in each axial direction are defined as nx 2 , ny 2 , and nz 2 , respectively; and an optical film ( 3 ) formed of a material showing optically negative uniaxial property, and the material being tilting aligned.