Projection display
View Patent ↗A projection type image display apparatus is provided which includes a housing to hold an optical system including multi-lenses, a polarized-light conversion element and the color separation portion. The housing operates to provide an optical path between a light source, located outside the housing, and penetration-type image display elements and an optical synthesizing portion also located outside of the housing.
1. An optical unit, comprising:
a light source;
first and second multi-lenses for equalizing intensities of lights from said light source;
a polarized-light conversion element for unifying polarization directions of the lights from said first and second multi-lenses;
a color separation portion for separating the lights from said polarized-light conversion element into a plural number of colors;
a plurality of transmission-type image display elements, each being disposed corresponding to each of said plural number of light colors;
an optical synthesizing portion, for synthesizing the lights from said plurality of transmission-type image display elements, different surfaces of said optical synthesizing portion being attached with one of said plurality of transmission-type image display elements, respectively, in such a manner that the transmission-type image display elements can be freely attached and detached;
a seat portion, including a plurality of projection frame portions, on which one face of the optical synthesizing portion is mounted to permit accurate positioning of the optical synthesizing portion;
a projection lens for projecting light from said optical synthesizing portion;
a supporting portion for supporting said optical synthesizing portion thereon; and
a housing for disposing said first and second multi-lenses, said polarized-light conversion element and said color separation portion therein, wherein said housing is sealed by said first multi-lens, said housing including a recessed portion in an outer wall of the housing, said recessed portion being located adjacent to said projection lens and including a collimator lens being located in said recessed portion,
wherein said plurality of transmission-type image display elements and said optical synthesizing portion are located in said recessed portion, outside of said housing to facilitate easy access for accurately attaching the transmission-type image display elements and for easily detaching the transmission-type image display elements, as desired for repair or replacement,
wherein said optical synthesizing portion includes cross dichroic prisms,
wherein said cross dichroic prisms include jigs, disposed corresponding to each of said plurality of transmission-type image display elements, each of which is comprised of a metal plate and includes a projection, and wherein said plurality of transmission-type image display elements are attached on said jigs,
wherein, on one surface of the seat portion, a projection portion is formed for positioning said cross dichroic prisms, and on another surface thereof being mounted said cross dichroic prisms abutting on a surface different from a surface on which said plurality of transmission-type image display elements are attached,
further comprising a member for absorbing reflection light upon said projection lens between said cross dichroic prisms and said projection lens, and
wherein said member for absorbing reflection light is comprised of a reflection-type polarization plate and an absorption-type polarization plate located substantially parallel to one another between the cross dichroic and the projection lens.
2. The optical unit according to claim 1 ,
wherein said plural numbers of colors include R-color, G-color and B-color.
3. The optical unit according to claim 1 ,
wherein the light source is located outside the housing.