Patent ID: 7445345

Claim:
An optical display device that displays an image by modulating light from a light source based on display image data, comprising: an optical separation unit that divides light from the light source into light of a plurality of different specific wavelength regions, and that is composed of a prism having a polyhedron shape containing first through fourth side faces and in which a film is formed that reflects or transmits light of a specific wavelength region so as to divide light from the light source that has entered from the first side face into three different specific wavelength regions and radiate said resolved light from the second through fourth side faces; a plurality of first optical modulation elements that respectively control the light propagation characteristics of resolved light from the optical separation unit; a light synthesis unit that synthesizes light from the plurality of first optical modulation elements, and that is composed of a prism having a polyhedron shape containing first through fourth side faces and in which a film is formed that reflects or transmits light of a specific wavelength region so as to synthesize light that has entered from the second to fourth side faces and radiate said synthesized light from the first side face; a light transmission unit that is provided so as to transmit the resolved light respectively radiated from the second through fourth side faces of the optical separation unit to the second through fourth side faces of the light synthesis unit, and so that the optical path lengths of the three specific wavelength regions of resolved light are each equal or nearly equal; a second optical modulation element that controls the light propagation characteristics of the synthesized light synthesized by the light synthesis unit, the second optical modulation element including a plurality of pixels controlling the light propagation characteristics independently; and at least one relay element that transmits an optical image formed on the first optical modulation elements to the second optical modulation element, wherein, each of the optical separation unit and the light synthesis unit comprises a first dichroic film and a second dichroic film, the first dichroic film of the optical separation unit and the first dichroic film of the light synthesis unit are in substantially the same plane, and the second dichroic film of the optical separation unit and the second dichroic film of the light synthesis unit are in substantially the same plane.