Projection display apparatus
Liquid crystal projector
System for controlling contrast in projection displays
Light-source device and projection type display device Patent #: 6631997
AbstractA projector-type image display device includes a liquid crystal display device for forming an image, an illumination optical system for illuminating the liquid crystal display device with light from a light source, a projection optical system for projecting an image from the liquid crystal display device, and a diaphragm member disposed on at least one of the illumination optical system and the projection optical system. An aperture is formed in the diaphragm member, and the aperture has a shape such that the f-numbers at a plurality of directions from the at least one optical system are different f-numbers, according to contrast properties of each direction of the liquid crystal display device.