Projection-type display apparatus

Abstract

A projection-type display apparatus ( 1 ) is comprised of an illumination optical system ( 2 A), a color separating system ( 4 ) for separating a white beam (W) from the illumination optical system into color beams (R, G, B), three liquid crystal panels ( 5 R, 5 G, 5 B) for modulating the separated color beams, a light guide system ( 9 ) located on an optical path of the beam (G) having the longest optical path among the separated color beams respectively incident on the three light valves, a dichroic prism ( 6 ) for synthesizing the beams modulated through the liquid crystal panels, and a projection lens ( 7 ) for projecting the synthesized and modulated beam onto a screen ( 8 ). The illumination optical system ( 2 A) is provided with a uniform illumination optical device ( 3 ) for converting the white beam into a uniform rectangular beam. Since the dichroic prism, which is an optical element rotationally symmetrical about the center axis of a projection optical system, is employed as a color synthesizing system and the uniform illumination optical device for restricting unevenness in color and luminous intensity is incorporated in the illumination optical system, it is possible to realize a display apparatus which causes little unevenness in color and luminous intensity and has a high illumination efficiency.

What is claimed is:  
     
         1 . A projector, comprising: 
 a light source;    color separating means for separating a light beam emitted from said light source into a plurality of color beams;    a plurality of light valves for modulating said separated color beams;    light guide means located on an optical path of a color beam having a longest optical path length, the color beams being separated by said color separating means and respectively incident on said light valves;    color synthesizing means for synthesizing a projection beam from said color beams modulated through said light valves;    a projection lens for projecting said projection beam into a screen;    uniform illumination optical means interposed on an optical path between said light source and said color separating means for converting said light beam emitted from said light source into a uniform beam; and    a plurality of condenser lenses located respectively in outputting portions of said color separating means for outputting said color beams, the condenser lenses converting said color beams separated by said color separating means into almost collimated beams.    
     
     
         2 . A projector according to  claim 1 , wherein said light valves are liquid crystal panels, and a pixel pitch of each of said liquid crystal panels is approximately 50 μm or less.  
     
     
         3 . A projector according to  claim 1 , wherein said uniform illumination optical means has at least one lens plate comprising a plurality of lenses.  
     
     
         4 . A projector according to  claim 3 , wherein said uniform illumination optical means comprises a first lens plate and a second lens plate.  
     
     
         5 . A projector, comprising: 
 a light source;    color separating means for separating a light beam emitted from said light source into a plurality of color beams;    a plurality of condenser lenses located respectively in outputting portions of said color separating means for outputting said color beams, the condenser lenses converting said color beams separated by said color separating means into almost collimated beams;    a plurality of light valves for modulating said separated color beams;    light guide means located on an optical path of a color beam having a longest optical path length, the color beams being separated by said color separating means and respectively incident on said light valves;    color synthesizing means for synthesizing a projection beam from said color beams modulated through said light valves;    a projection lens for projecting said projection beam onto a screen; and    polarized beam conversion means for converting the light beam emitted from said light source into one kind of polarized light.    
     
     
         6 . A projector according to  claim 5 , wherein uniform illumination optical means is interposed on an optical path between said light source and said color separating means for converting said light beam emitted from said light source into a uniform beam.  
     
     
         7 . A projector according to  claim 5 , wherein said polarized beam conversion means comprises: 
 polarized beam separating means for separating a random polarized beam from said light source into two kinds of linearly polarized beams; and    polarization plane rotating means for rotating a polarization plane of one of said two kinds of linearly polarized beams through a 90 degree angle so that one kind of polarized light is emitted from said polarized beam conversion means.    
     
     
         8 . A projector, comprising: 
 a light source emitting a light beam;    a uniform illumination optical device that converts said light beam emitted from said light source into a uniform beam;    a color separating optical system that separates the beam emitted from said light source into a plurality of color beams;    a plurality of condenser lenses located respectively in outputting portions of said color separating optical system, the condenser lenses converting said color beams into almost collimated beams;    a plurality of light valves that modulate said separated color beams;    a light guide system located on an optical path of a color beam having a longest optical path length; and    a color synthesizing system that synthesizes said color beams into a projection beam.    
     
     
         9 . The projector according to  claim 8 , further comprising a projection lens that projects said projection beam.  
     
     
         10 . The projector according to  claim 8 , wherein said light valves are liquid crystal panels, and a pixel pitch of each of said liquid crystal panels is approximately 50 μm or less.  
     
     
         11 . The projector according to  claim 8 , wherein said uniform illumination optical device has at least one lens plate comprising a plurality of lenses.  
     
     
         12 . A projector according to  claim 11 , wherein said uniform illumination optical device comprises a first lens plate and a second lens plate.  
     
     
         13 . A projector, comprising: 
 a light source emitting a light beam;    a polarized beam conversion device that converts the light beam emitted from said light source into a light beam having a single polarization type;    a color separating optical system that separates the light beam into a plurality of color beams;    a plurality of condenser lenses located respectively in outputting portions of said color separating optical system, the condenser lenses converting said color beams into almost collimated beams;    a plurality of light valves that modulate said separated color beams;    a light guide system located on an optical path of a color beam having a longest optical path length; and    a color synthesizing system that synthesizes said color beams into a projection beam.    
     
     
         14 . The projector of  claim 13 , further comprising a projection lens that projects said projection beam.  
     
     
         15 . The projector according to  claim 13 , further comprising a uniform illumination optical device interposed on an optical path between said light source and said color separating optical system that converts said light beam having a single polarization type into a uniform beam.  
     
     
         16 . The projector according to  claim 13 , wherein said polarized beam conversion device comprises: 
 a polarized beam separating device that separates a random polarized beam from said light source into two kinds of linearly polarized light beams; and    a polarization plane rotating device that rotates a polarization plane of one of said two kinds of linearly polarized light beams through a 90 degree angle so that said light beam having a single polarization type is emitted from said polarized beam conversion device.