Transparent film and optical compensatory film, polarizing plate and liquid-crystal display device employing it

Abstract

A novel transparent film is disclosed. Re (lambda) and Rth (lambda) of the film defined by the following formulae (I) and (II) satisfy the following formulae (III) and (IV):(I) Re (lambda) = (nx - ny) x d,(II) Rth (lambda) = {(nx + ny) / 2 - nz} x d, (III) <= 0 <= || Re (630) || <= 50, (IV) Rth (400) x Rth (700) <= 0, and <= 0 || Rth (700) - Rth (400) || <= 150,wherein Re (lambda) means an in-plane retardation value at a wavelength lambda nm (unit: nm); Rth (lambda) means a thickness-direction retardation value at a wavelength lambda nm (unit: nm); nx means a refractive index in the in-plane slow-axis direction; ny means a refractive index in the in-plane fast-axis direction; nz means a refractive index in the film thickness direction; and d means a thickness of the film.

Description

technical field

[0001] The present invention relates to a transparent film, an optical compensation sheet, a polarizing plate and a liquid crystal display device using the film. Background technique

[0002] A liquid crystal display device generally includes a liquid crystal cell and a polarizing plate. The polarizing plate has a protective film and a polarizing film, and can be obtained, for example, by dyeing a polarizing film formed of a polyvinyl alcohol film with iodine, stretching it, and laminating protective films on both sides thereof. In general, a transmissive liquid crystal display device may include such polarizing plates mounted on both sides of a liquid crystal cell, and may also have one or more optical compensation films provided therein. A reflective liquid crystal display device generally includes a reflector, a liquid crystal element, one or more optical compensation films, and a polarizer mounted in sequence. A liquid crystal...

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