Patent ID: 7327519

Claim:
A projector comprising: an illumination optical system that illuminates a spatial light modulator, the spatial light modulator includes a modulating unit that modulates the light based on an image signal and outputs a modulated light; a refracting part that refracts the modulated light; and a flat part that transmits the modulated light, wherein the modulating unit includes a plurality of pixels that are arranged in a matrix; and a light-shielding portion between each of the pixels, the refracting part is a prism group that is composed of a plurality of prism elements, each of the prism elements having at least a refracting surface, the modulated light from one of the pixels is incident on at least a portion of the prism group, the prism group is arranged in a substantially periodic manner, with number of the periods being 15 or less per a unit area, wherein the unit area is a circular area on the prism group; and a projection optical system that is disposed after the spatial light modulator, the projection optical system including a projection lens that projects the light from the spatial light modulator to display an image on a screen, wherein the unit area on the prism group is determined by an F-number of the projection optical system when an F-number of the illumination optical system is equal to or larger than the F-number of the projection optical system, and the unit area is determined by the F-number of the illumination optical system when the F-number of the illumination optical system is smaller than the F-number of the projection optical system, and the refracting surface, being formed to have an angle with respect to a reference surface that is orthogonal to an optical axis, is configured to refract the modulated light which entered into the refracting surface so that an image of the pixel is superposed over an image of the light-shielding portion on the screen at a predetermined distance from the prism group through the projection lens.