Patent ID: 6839103

Claim:
An elliptically polarizing plate comprising a laminate of: a polarizer having a first planar side and an opposing planar side and comprising a polarizer film having a thickness of from about 5 to about 80 μm, and optionally including a protective layer having a thickness which is less than about 500 μm; a first anisotropic optical layer having a first planar side and an opposing second planar side, said layer being made from a first material that is a calamitic liquid crystal which has a thickness of from about 0.5 to about 500 μm and optionally includes a substrate having thickness of from about 0 to about 500 μm, said first anisotropic optical layer having a positive refractive index anisotropy and an optical axis that is tilted relative to the plane of the polarizer and which has a retardation Re=(nx−ny)×d within the plane of the layer of from about 10 to about 1000 nm and a retardation Rth=(nx−nz)×d in the direction of the thickness of from about −400 to about 900 nm wherein the effective indexes in two directions within the plane is set to nx and ny, the refractive index in the thickness direction is set to nz, and th thickness is d; a second anisotropic optical layer having a first planar side and an opposing second side and said layer being made from a second material that is a discotic liquid crystal which has a thickness of from about 0.5 to about 500 μm and optionally includes a substrate having a thickness of from about 0 to about 500 μm, and said second anisotropic optical layer having a negative refractive index anisoptropy and an optical axis that is tilted relative to the plane of the polarizer and which has a retardation Re=(nx−ny)×d within the plane of the layer of from about 1 to about 500 nm and a retardation Rth=(nx−nz)×d in the direction of the thickness of from about 0 to about 700 nm; and one of the planar sides of the polarizer being laminated directly or by means of an intermediate adhesive layer to the first planar side of the first anisotropic optical layer and the second planar side of the second anisotropic layer being laminated directly or by means of an intermediate adhesive layer to the first planar side of the second anisotropic layer, and the second layer being oriented so that the optical plane of the second layer is substantially orthogonal to the optical plane of the first optical layer.