[Problems] To provide an optical film for a liquid crystal display, in which a wide range of a retardation of transmitted light can be controlled in manufacturing and good viewing angle compensation effects on such as preventing light leakage or color dropout (coloring) in true black display and achieving a high contrast in all directions can be obtained when used in liquid crystal display.
[Means for Solving Problems] The optical film of the invention includes a film (a) layer made of a cyclic olefin resin and a film (b) layer made of a polyimide resin or a polyetherimide resin, wherein following formulae (1) and (2) are preferably satisfied: (1) 200 nm≦Rth≦1,000 nm and (2) 0≦R550≦200 nm, wherein Rth and R550 represent the retardation in the direction of film thickness and the in-plane retardation of the film, respectively, at wavelength of 550 nm.
[问题] 提供一种适用于液晶显示器的光学膜,可以在制造过程中控制传输光的广泛延迟范围,并在真正的黑色显示中实现良好的视角补偿效果,例如防止光泄漏或颜色丢失(着色),并在所有方向上实现高对比度。
[解决问题的方法] 本发明的光学膜包括由环烯烃
树脂制成的膜(a)层和由聚
酰亚胺树脂或聚醚
酰亚胺树脂制成的膜(b)层,其中以下公式(1)和(2)最好满足:(1)200 nm≦Rth≦1,000 nm和(2)0≦R550≦200 nm,其中Rth和R550分别表示在550 nm波长下膜的厚度方向延迟和面内延迟。