Method for manufacture of reflecting mirror, reflecting mirror, illumination device, and projector

Abstract

An auxiliary reflecting mirror is manufactured by heating the central portion of a quartz glass tube and compressing the central portion by pushing two end portions of the quartz glass tube so that the wall thickness of the central portion thickens, accommodating the quartz glass tube after thickening the wall thickness of the central portion in a mold having inner surfaces formed to the reflecting surface shape, which is to be formed in an auxiliary reflecting mirror, and forming an expanded portion by expanding the central portion, of which the wall thickness was thickened, by introducing a gas from the two ends of the quartz glass tube, cutting the quartz glass tube in at least the central portion of the expanded portion, evaporating a reflecting film on the outer surface of the expanded portion and forming a reflecting surface.

1 . A method for the manufacture of a reflecting mirror of an illumination device, including a light-emitting tube and the reflecting mirror to reflect a light from the light-emitting tube, the method comprising: 
 heating a central portion of a quartz glass tube and compressing the central portion by pushing two end portions of the quartz glass tube so that the wall thickness of the central portion thickens;    accommodating the quartz glass tube after thickening the wall thickness of the central portion in a mold having an inner surface formed to a reflecting surface shape, which is to be formed in a reflecting mirror, and forming an expanded portion by expanding the central portion, of which the wall thickness was thickened, by introducing a gas from the two ends of the quartz glass tube;    cutting the quartz glass tube in at least the central portion of the expanded portion; and    evaporating a reflecting film on the outer surface of the expanded portion and forming a reflecting surface.    
     
     
         2 . The method for the manufacture of a reflecting mirror according to  claim 1 , further comprising: 
 cutting both end portions of cylindrical portions extending outwardly from the two ends of the expanded portion in addition to cutting the vicinity of the central portion of the expanded portion of the quartz glass tube, and providing cylindrical mounting support portions to fix to the light-emitting tube.    
     
     
         3 . A reflecting mirror manufactured by the method for the manufacture of a reflecting mirror according to  claim 1 .  
     
     
         4 . A reflecting mirror manufactured by the method for the manufacture of a reflecting mirror according to  claim 2 .  
     
     
         5 . An illumination device, comprising: 
 a light-emitting tube; and    a reflecting mirror to reflect the light from the light-emitting tube toward an illumination region, the reflecting mirror being manufactured by the method for the manufacture of a reflecting mirror according to  claim 1 .    
     
     
         6 . An illumination device, comprising: 
 a light-emitting tube; and    a reflecting mirror to reflect the light from the light-emitting tube toward an illumination region, the reflecting mirror being manufactured by the method for the manufacture of a reflecting mirror according to  claim 2 .    
     
     
         7 . An illumination device, comprising: 
 a light-emitting tube;    a main reflecting mirror to reflect the light from the light-emitting tube toward an illumination region; and    an auxiliary reflecting mirror to reflect the light from the light-emitting tube toward the main reflecting mirror, the auxiliary reflecting mirror being manufactured by the method for the manufacture of a reflecting mirror according to  claim 1 .    
     
     
         8 . An illumination device, comprising: 
 a light-emitting tube;    a main reflecting mirror to reflect the light from the light-emitting tube toward an illumination region; and    an auxiliary reflecting mirror to reflect the light from the light-emitting tube toward the main reflecting mirror, the auxiliary reflecting mirror being manufactured by the method for the manufacture of a reflecting mirror according to  claim 2 .    
     
     
         9 . A projector, comprising: 
 the illumination device according to  claim 5 ,    a light modulation device to modulate the luminous flux emitted from the illumination device according to an image information; and    a projection optical system to project the luminous flux modulated by the light modulation device.    
     
     
         10 . A projector, comprising: 
 the illumination device according to  claim 6 ,    a light modulation device to modulate the luminous flux emitted from the illumination device according to an image information; and    a projection optical system to project the luminous flux modulated by the light modulation device.    
     
     
         11 . A projector, comprising: 
 the illumination device according to  claim 7 ,    a light modulation device to modulate the luminous flux emitted from the illumination device according to an image information; and    a projection optical system to project the luminous flux modulated by the light modulation device.    
     
     
         12 . A projector, comprising: 
 the illumination device according to  claim 8 ,    a light modulation device to modulate the luminous flux emitted from the illumination device according to an image information; and    a projection optical system to project the luminous flux modulated by the light modulation device.