POLARIZER, POLARIZATION LIGHT SOURCE AND IMAGE DISPLAYUNIT USING THEM

摘要

A polarizer capable of efficiently reflecting an obliquely-transmitting light toward a light source without compromise in transmitting polarization characteristics of a vertically-incident light. A C plate having an oblique phase difference with respect to light inclining at at least 30° of at least lambda/8 is disposed between at least two layers of reflection circular polarizer where selective reflection wavelength bands of polarization are overlap each other. A combination of a reflection linear polarizer and a 1/4 wavelength plate may be used instead of the reflection circular polarizer. Alternatively, a combination of two layers of reflection linear polarizer and two layers of 1/4 wavelength plate (Nz>=2) disposed therebetween can give a similar effect. Further, a combination of two layers of reflection linear polarizer and a 1/2 wavelength plate (Nz>=1.5) disposed therebetween may be used. When reflection linear polarizers are used, they must be pasted together with their axis directions set at a specified angle. The polarizer is preferably used in various imasge display units such as liquid crystal display units and organic EL display units.