[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
提供一种液晶显示器用光学薄膜,该薄膜在制造过程中可控制较大范围的透射光延迟,在液晶显示器中使用时,可获得良好的视角补偿效果,如防止真黑显示中的漏光或掉色(着色),以及在所有方向上实现高对比度。
[解决问题的方法]
本发明的光学薄膜包括由环烯烃
树脂制成的薄膜(a)层和由聚
酰亚胺树脂或聚醚
酰亚胺树脂制成的薄膜(b)层,其中最好满足以下公式(1)和(2):(1) 200 nm ≦ Rth ≦ 1,000 nm;(2) 0 ≦ R550 ≦ 200 nm,其中 Rth 和 R550 分别代表波长为 550 nm 时薄膜厚度方向的延迟和薄膜平面内的延迟。