Light conducting unit, illumination apparatus, and projection type display apparatus

Abstract

A light conducting unit is disposed between a light source and a region which is to be illuminated. In addition, a light conducting unit includes a polygonal prism made from a first medium with a first coefficient of refraction, a first light conducting unit which directs light to be incident upon a first surface of the polygonal prism, and a second light conducting unit upon which light emitted from a second surface of the polygonal prism is incident, wherein the polygonal prism includes a reflective device which reflects light which is incident into the polygonal prism from the first surface towards the second surface, and a second medium with a second coefficient of refraction which is less than the first coefficient of refraction is provided at the first surface and the second surface.

1 . A light conducting unit disposed between a light source and a region which is to be illuminated, comprising: 
 a polygonal prism made from a first medium with a first coefficient of refraction;    a first light conducting unit which directs light to be incident upon a first surface of the polygonal prism; and    a second light conducting unit upon which light emitted from a second surface of the polygonal prism is incident;    wherein the polygonal prism comprises a reflective device which reflects light which is incident into the polygonal prism from the first surface towards the second surface, and    a second medium with a second coefficient of refraction which is less than the first coefficient of refraction is provided at the first surface and the second surface.    
   
   
       2 . A light conducting unit according to  claim 1 , wherein the polygonal prism is a triangular prism.  
   
   
       3 . A light conducting unit according to  claim 1 , wherein the first light conducting unit and the second light conducting unit are made in a tubular shape from at least one reflective body with a light reflective surface facing inwards, 
 interiors of the first light conducting unit and the second light conducting unit are filled with the second medium, and    surfaces of the first light conducting unit and the second light conducting unit which are not provided with the reflective body constitute an incidence surface and an emission surface.    
   
   
       4 . A light conducting unit according to  claim 1 , 
 wherein the first light conducting unit and the second light conducting unit are made in the shape of posts from a third medium with a third coefficient of refraction,    the third coefficient of refraction is greater than the coefficient of refraction of the medium which surrounds the first light conducting unit and the second light conducting unit, and    the second medium is disposed between the first light conducting unit and the first surface, and between the second light conducting unit and the second surface.    
   
   
       5 . A light conducting unit according to  claim 4 , wherein gaps between the first light conducting unit and the first surface, and between the second light conducting unit and the second surface, are greater than the product of the wavelength of the light which is being propagated through the first and second light conducting units, and the second coefficient of refraction.  
   
   
       6 . A light conducting unit according to  claim 4 , 
 wherein a first convex portion is provided at approximately a central portion of a surface of the first light conducting unit which opposes the first surface,    a second convex portion is provided at approximately a central portion of a surface of the second light conducting unit which opposes the second surface, and    the first convex portion and the first surface are in mutual contact, and    the second convex portion and the second surface are in mutual contact.    
   
   
       7 . A light conducting unit according to  claim 3 , wherein a reflection prevention device which suppresses the reflection of light is provided upon at least one of the first surface, the second surface, and the incidence surfaces and the emission surfaces of the first light conducting unit and of the second light conducting unit.  
   
   
       8 . A light conducting unit according to  claim 7 , wherein the reflection prevention device is a reflection prevention layer.  
   
   
       9 . An illumination apparatus comprising: 
 a light source; and    a light conducting unit according to  claim 1 , located between the light source and a region which is to be illuminated.    
   
   
       10 . A projection type display apparatus comprising: 
 an illumination apparatus according to  claim 9;     a light modulation device which modulates the light which has been emitted from the illumination apparatus; and    a projection device which projects the light which has been modulated by the light modulation device.    
   
   
       11 . An illumination apparatus comprising: 
 a light source which emits light for illumination;    a light concentration device which concentrates light from the light source to a predetermined angular range; and    a light uniformization device formed from a transparent material in the shape of a post, and which has, at least at one of its ends, an inclined end surface which defines an angle of inclination of approximately 45° with respect to the axis of the post shape,    wherein the light uniformization device totally internally reflects the light from the inclined end surface, when the light passes through the light concentration device and along the post shape.    
   
   
       12 . An illumination apparatus according to  claim 11 , 
 wherein the post shaped transparent light uniformization device is formed in a post shape which has a first pair of side surfaces which are mutually parallel, and a second pair of side surfaces which are mutually parallel and are also orthogonal to the first pair of side surfaces, and    the inclined end surface is orthogonal to the first pair of side surfaces and defines an angle of approximately 45° with respect to the second pair of side surfaces.    
   
   
       13 . An illumination apparatus according to  claim 12 , wherein the post shaped transparent light uniformization device, at least at one end of its four cornered post shaped rod integrator main body, is formed as a right angled prism portion with the inclined end surface being its side surface corresponding to the hypotenuse.  
   
   
       14 . An illumination apparatus according to  claim 11 , wherein the post shaped transparent light uniformization device is formed from a glass material with a coefficient of refraction such as to implement total internal reflection at the inclined end surface for the predetermined angular range and the angle of inclination.  
   
   
       15 . An illumination apparatus according to  claim 12 , wherein the light concentration device conducts the light from the light source into the light uniformization device via a transparent window surface portion upon a one of the second pair of side surfaces which is opposed to the inclined end surface.  
   
   
       16 . An illumination apparatus according to  claim 15 , wherein the light concentration device causes at least a major portion of the light from the light source to be incident via the transparent window surface portion upon the inclined end surface either directly or indirectly.  
   
   
       17 . An illumination apparatus according to  claim 12 , wherein the light uniformization device is reflected the light which has passed along the post shape from the inclined end surface, and emits the light to the outside via a transparent window surface portion upon one of the second pair of side surfaces which is opposed to the inclined end surface.  
   
   
       18 . An illumination apparatus according to  claim 11 , wherein the light source is a solid-state light source.  
   
   
       19 . A projection type display apparatus comprising: 
 an illumination apparatus according to  claim 11;     a spatial light modulation device which is illuminated by illumination light which has been emitted from the illumination apparatus, and which modulates the illumination light to produce an optical image; and    a projection optical system which projects the optical image produced by the spatial light modulation device.    
   
   
       20 . A projection type display apparatus comprising: 
 a plurality of illumination apparatuses for various colors, each of which is an illumination apparatus according to  claim 11;     for each of the various colors, a spatial light modulation device which is illuminated by the illumination light of its corresponding color which has been emitted from the corresponding one of the illumination apparatuses, and which modulates the illumination light to produce an optical image of the corresponding color;    a light combination optical system which combines the optical images of the various colors modulated by the spatial light modulation devices of the corresponding colors; and    a projection optical system which projects an optical image produced by the combination by the light combination optical system.