Optical compensating sheet, polarizing plate, and liquid crystal display device

Abstract

The object of the present invention is to provide an optical compensation sheet for improving the display quality of a liquid crystal display device, a polarizing plate having the optical compensation sheet, and a liquid crystal display device. An optical compensation sheet is composed of cellulose acylate film, wherein the in-plane retardation value Re of the cellulose acylate film is: 0nm≤Re<20nm, the thickness d is: 10μm<d<85μm, and the sound velocity measured in the film plane The minimum value of V min and maximum V max The average value (V min +V max ) / 2 is: 2.2km / sec<(V min +V max ) / 2<2.5km / sec, and the ratio V of the maximum value and the minimum value of the sound velocity measured in the film surface max / V min For: 1.01<V max / V min <1.12. Another optical compensation sheet is composed of a cellulose acylate film and an optically anisotropic layer formed of a liquid crystal compound, wherein the above liquid crystal compound is provided on the above cellulose acylate film, wherein the in-plane of the cellulose acylate film The in-plane retardation value Re of cellulose acylate film is: 0nm≤Re<20nm, the thickness d is: 10μm<d<85μm, and the minimum value V of the sound velocity measured in the film plane min and maximum V max The average value (V min +V max ) / 2 is: 2.2km / sec<(V min +V max ) / 2<2.5km / sec, and the ratio V of the maximum value and the minimum value of the sound velocity measured in the film surface max / V min For: 1.01<V max / V min <1.12.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 200410061869.3 submitted on June 25, 2004. technical field [0002] The present invention relates to an optical compensation sheet for improving the viewing angle (also referred to as viewing angle) of a liquid crystal display device, a polarizing plate (also referred to as a polarizer) using the optical compensation sheet, and a liquid crystal display device. Background technique [0003] A liquid crystal display device usually consists of a liquid crystal cell, a polarizing plate, and an optical compensation film (retardation plate). In a transmissive liquid crystal display device, two polarizers are installed on both sides of the liquid crystal unit, and one or two optical compensation sheets are disposed between the liquid crystal unit and the polarizer. For a reflective liquid crystal display device, a reflective plate, a liquid crystal unit, an optical compensation sheet, and a polari...

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Problems solved by technology

[0017] In order to respond to the demand for cost reduction due to weight reduction and improvement in productivity, thinning of the transparent support is also strongly desired, but the strength is reduced due to thinning, and it is practically used especially when used in a large liquid crystal display device. question on

Such a problem cannot be fully solved according to the current proposal, and it is strongly desired to increase the strength of the support, but if the strength of the support is only increased, the problems of poor optical properties and reduced visibility will arise.

[0018] In addition, in a liquid crystal display device composed of a large display panel of 20 inches or more, it will be found that there are problems that have not been fully studied in the prior art.

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