| 摘要 |
An optical film having a desired wavelength dispersion characteristic, a low photoelastic coefficient and a desired Nz coefficient. The optical film is formed from a copolymer and meets the following conditions (i) to (v):
(i) the thickness (d) is 20 to 80 µm;
(ii) the following formulas (1) and (2) are satisfied: 0.6 < R 450 / R 550 < 1 1.01 < R 650 / R 550 < 1.40
(R(450), R(550) and R(650) are retardations within the plane of the film at respective wavelengths);
(iii) R(550) is 120 to 160 nm;
(iv) the birefringence (”n) is not less than 1.5 x 10 -3 ; and
(v) the Nz coefficient represented by the following formula. (4) is 1.18 to 2.40: Nz = n x - n z / n x - n y
(n x , n y and n z are 3-dimensional birefringences of the film). |
