Liquid crystal projector with an illumination optical system

Abstract

A liquid crystal projector includes an illumination optical system provided with a light source, first and second lens arrays arranged in this order from the light source, a liquid crystal panel, and a polarization changing optical system arranged between the first and second lens arrays. This makes it possible to install the polarization changing optical system and the optical integrator in a smaller space.

What is claimed is:  
     
         1 . An illumination optical system for illuminating a surface to be illuminated, comprising: 
 a light source which emits a beam of light;    a first lens array and a second lens array arranged in this order from the light source, the first and second lens arrays each having a plurality of lenses; and    a polarization changing optical system, arranged between the first and second lens arrays, for separating light having a predetermined polarization component from incident light, the polarization changing optical system including a polarized beam splitting surface and a full reflection surface.    
     
     
         2 . A liquid crystal projector as claimed in    claim 1   , wherein the second lens array includes twice as many lenses as the first lens array.  
     
     
         3 . An illumination optical system as claimed in    claim 1   , wherein the polarized beam splitting surface is disposed adjacent to the full reflection surface.  
     
     
         4 . An illumination optical system for illuminating a surface to be illuminated, comprising: 
 a light source which emits a beam of light;    a first lens array and a second lens array arranged in this order from the light source, the first and second lens arrays each having a plurality of lenses; and    a polarization changing optical system for separating light having a predetermined polarization component from incident light, the polarization changing optical system including a polarized beam splitting surface and a full reflection surface, the first lens array being arranged between the light source and the polarization changing optical system.    
     
     
         5 . A liquid crystal projector as claimed in    claim 4   , wherein the second lens array includes twice as many lenses as the first lens array.  
     
     
         6 . An illumination optical system as claimed in    claim 4   , wherein the polarized beam splitting surface is disposed adjacent to the full reflection surface.  
     
     
         7 . An illumination optical system for illuminating a surface to be illuminated, comprising: 
 a light source which emits a beam of light;    a first lens array and a second lens array arranged in this order from the light source, the first and second lens arrays each having a plurality of lenses;    a polarization changing optical system, arranged more toward the light source than the second lens array, for separating a first light having a first polarization component and a second light having a second polarization component; and    a half-wave plate, arranged in the vicinity of the second lens array, for changing the polarization of the second light to the first polarization.    
     
     
         8 . An illumination optical system as claimed in    claim 7   , wherein the polarization changing optical system is arranged between the first lens array and the second lens array.  
     
     
         9 . An illumination optical system as claimed in    claim 7   , wherein the second lens array includes twice as many lenses as the first lens array.  
     
     
         10 . An illumination optical system as claimed in    claim 7   , wherein the polarized beam splitting surface is disposed adjacent to the full reflection surface.  
     
     
         11 . An illumination optical system as claimed in    claim 7   , wherein the polarization changing optical system is made of a material having a property of birefringence.  
     
     
         12 . An illumination optical system for illuminating a surface to be illuminated, comprising: 
 a light source which emits light;    a first lens array and a second lens array arranged in this order from the light source, the first and second lens arrays each having a plurality of lenses, wherein luminous flux divided by the first lens array are superimposed by the second lens array so as to improve uniformity of illuminance provided by the illumination optical system; and    a polarization changing optical system arranged between the first and second lens arrays, the polarization changing optical system including a polarized beam splitting surface and a full reflection surface.    
     
     
         13 . An illumination optical system as claimed in    claim 12   , wherein the second lens array includes twice as many lenses as the first lens array.  
     
     
         14 . An illumination optical system as claimed in    claim 12   , wherein the polarized beam splitting surface is disposed adjacent to the full reflection surface.  
     
     
         15 . An illumination optical system for illuminating a surface to be illuminated, comprising: 
 a light source which emits light;    a first lens array and a second lens array arranged in this order from the light source, the first and second lens arrays each having a plurality of lenses, wherein luminous flux divided by the first lens array are superimposed by the second lens array so as to improve uniformity of illuminance provided by the illumination optical system; and    a polarization changing optical system, the first lens array being arranged between the light source and the polarization changing optical system.    
     
     
         16 . A liquid crystal projector as claimed in    claim 15   , wherein the second lens array includes twice as many lenses as the first lens array.  
     
     
         17 . An illumination optical system as claimed in    claim 15   , wherein the polarized beam splitting surface is disposed adjacent to the full reflection surface.  
     
     
         18 . An illumination optical system for illuminating a surface to be illuminated, comprising: 
 a light source which emits light;    a first lens array and a second lens array arranged in this order from the light source, the first and second lens arrays each having a plurality of lenses, wherein luminous flux divided by the first lens array are superimposed by the second lens array so as to improve uniformity of illuminance provided by the illumination optical system;    a half-wave plate arranged in the vicinity of the second lens array; and    a polarization changing optical system, arranged more toward the light source than the second lens array, the polarization changing optical system including a polarized beam splitting surface and a full reflection surface.    
     
     
         19 . A liquid crystal projector as claimed in    claim 18   , wherein the polarization changing optical system is arranged between the first lens array and the second lens array.  
     
     
         20 . A liquid crystal projector as claimed in    claim 18   , wherein the second lens array includes twice as many lenses as the first lens array.  
     
     
         21 . An illumination optical system as claimed in    claim 18   , wherein the polarized beam splitting surface is disposed adjacent to the full reflection surface.  
     
     
         22 . An illumination optical system as claimed in    claim 18   , wherein the polarization changing optical system is made of a material having a property of birefringence.  
     
     
         23 . An illumination optical system for illuminating a surface to be illuminated, comprising: 
 a light source which emits a beam of light;    a first lens array and a second lens array arranged in this order from the light source, the first and second lens arrays each having a plurality of lenses; and    a polarization changing optical system, arranged at a position in the illumination optical system selected from the group of (1) between the first and second lens arrays, (2) such that the first lens array is arranged between the light source and the polarization changing optical system, and (3) arranged more toward the light source than the second lens array, said polarization changing optical system for separating light having a predetermined polarization component from incident light, said polarization changing optical system including a polarized beam splitting surface and a full reflection surface.