Patent ID: 8237898

Claim:
A bi-axial retardation compensation film having n x >n y >n z , R in =(n x −n y )×d>0 and R th =(n z −n y )×d<0, wherein n x and n y are in-plane refractive indexes, n z is a thickness refractive index, R in is a in-plane retardation, R th is a thickness retardation and d is a thickness, wherein a wavelength dispersion (R in,400 /R in,550 ) is in the range of 0.4˜0.9 at wavelengths of 400 nm and 550 nm, and a wavelength dispersion (R in,700 /R in,550 ) is in the range of 1.1˜1.8 at wavelengths of 700 nm and 550 nm, wherein R in,400 , R in,550 and R in,700 are in-plane retardations at wavelengths of 400 nm, 550 nm and 700 nm.