摘要:
A quarter wavelength plate for reducing the dependence of a retardation value on an incident beam angle in optically anisotropic crystals. The quarter wavelength plate is formed of optically anisotropic crystals in a thickness of 0.1 mm to 0.5 mm. The quarter wavelength plate can contribute to a reduction in the dependence of the retardation value on the angle at which a light beam impinges on the quarter wavelength plate, and to a reduction in color shading caused by a rise in temperature. A reflection type liquid crystal display device which employs the quarter wavelength plate can enhance the luminance and contrast.
摘要:
A projection display according to the present invention reduces the size of a light beam in the optical path of an illumination optics from the periphery to change the amount of light incident on a video display device and the angle of such incidence, thereby making a plurality of image brightness/contrast combinations selectable. Further, the present invention changes the revolving speed of a projection display cooling fan and the adjustment value settings for the video display device's electrical characteristics in accordance with the aperture.