Polarizing element for separating natural light into reflected and transmitted polarized light, and liquid-crystal display device comprising such a polarizing element

摘要

A liquid-crystal display device having a polarizing element, an optical element, a polarized light supply unit, and liquid-crystal cells. The polarizing element has a function of separating natural light into reflected and transmitted light composed of polarized light, wherein the half-reflecting wavelength measured at each position within the surface of the polarizing element falls within ±10 nm relative to the half-reflecting average wavelength, wherein the half-reflecting wavelength is a wavelength which is located at the long or short wave side of the wavelength exhibiting maximum reflectivity on the basis of a spectrum of reflected light in a predetermined wave range in which the natural light is separated into the reflected light and the transmitted light, and wherein the half-reflecting wavelength is defined as the wavelength which exhibits a reflectivity of 50% with respect to the maximum reflectivity, the half-reflecting average wavelength being the average of the half-reflecting wavelengths measured over the surface of the element. The optical element is a laminate of the polarizing element and of an absorption type polarizing plate. The polarized light supply unit has a surface light source provided with a reflection layer, and either one of the polarizing element and the optical element is disposed above the surface light source. The liquid-crystal cells are disposed on the light output side of the polarized light supply unit.