Liquid crystal display device, optical compensatory sheet, and polarizer and liquid crystal display device employing the same

Abstract

A liquid crystal display device comprising a liquid crystal panel in which liquid crystals having negative dielectric anisotropy are interposed between upper substrate and lower substrate that have been vertically oriented on the surface, the orientation of the liquid crystals being almost vertical with no applied voltage, almost horizontal when a predetermined voltage is applied, and tilted when a smaller voltage than the predetermined voltage is applied; a first polarizer and a second polarizer disposed on both sides of the liquid crystal panel such that the absorption axes of the polarizers are perpendicular to each other; a first retardation film disposed between the liquid crystal panel and the first polarizer; and a second retardation film disposed between the liquid crystal panel and the second polarizer, wherein the polarizer comprises a polarizing film and a pair of protective films having the polarizing film in between, and wherein at least one of the protective films is a cellulose acylate film satisfying: 0 = Re(630) = 10 and |Rth(630)| = 25.

Description

technical field [0001] The present invention relates to a liquid crystal display device having excellent display characteristics and viewing angle characteristics. [0002] The present invention also relates to an optical compensation sheet having improved color shift when the viewing angle is oblique to the front in a dark state, a polarizer using the optical compensation sheet, and a liquid crystal display device using the polarizer. Background technique [0003] Because of its toughness and flame retardancy, cellulose acylate films are commonly used for photographic supports and various optical materials. In particular, in recent years, cellulose acylate films have been frequently used as optically transparent films for liquid crystal display devices. Cellulose acylate films have high optical transparency and high optical isotropy, and thus serve as excellent optical materials for devices involving polarization such as liquid crystal display devices. Therefore, cellulos...

AI Technical Summary

Problems solved by technology

However, even these methods require bonding a plurality of films, and thus are not satisfactory from the viewpoints of thickness reduction and production cost reduction

Furthermore, there are problems in that light leakage in the oblique direction of the polarizer in the dark state cannot be completely suppressed in the visible light region, and the expansion of the viewing angle is insufficient

More importantly, it is difficult to completely compensate light leakage for the entire wavelength range of visible light at the incident angle with respect to the oblique direction of the polarizer in the dark state, and thus there is a problem that azimuthal direction dependence of chromatic aberration occurs

A method of preventing light leakage by controlling the dispersion of the retardation film has also been proposed (see JP-A 2002-221622), but there is a problem that the difference between the dispersion of the in-plane retardation and the dispersion of the thickness direction retardation is not considered, and suppressing Lack of light leaks

Therefore, the performance is unsatisfactory from the viewpoint of improving chromatic aberration in the case of a viewing angle tilted from the front in a dark state

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