Projection optical system, magnification projection optical system, magnification projection apparatus, and image projection apparatus

Abstract

A projection optical system for use in an image projection apparatus illuminating a lightbulb forming an image in accordance with a modulating signal with illumination light from a light source is disclosed. The projection optical system includes first and second optical systems arranged along an optical path defining an upstream-downstream direction in the order described from upstream to downstream on the downstream side of the lightbulb. The first optical system includes at least one dioptric system and has positive power. The second optical system includes at least one reflecting surface having power and has positive power. The image formed by the lightbulb is formed as an intermediate image in the optical path, and the intermediate image is magnified and projected.

1 - 23 . (canceled) 
   
   
       24 : A magnification projection optical system that guides a light beam from an image display panel to a screen in an upstream-downstream direction, projects the light beam from a direction inclined to a normal of the screen, and forms on the screen a magnified version of an image displayed on the image display panel, wherein:
 a position and a shape of an intermediate image of the image display panel formed with negative magnification by light beams traveling from the image display panel to the screen are substantially identical to a position and a shape, respectively, of an intermediate image of the screen formed with negative magnification by light beams traveling from the screen to the image display panel.   
   
   
       25 : The magnification projection optical system as claimed in  claim 24 , comprising:
 a reflection optical system including a plurality of reflecting surfaces; and   a transmission optical system including a plurality of transmitting surfaces.   
   
   
       26 : The magnification projection optical system as claimed in  claim 25 , further comprising a diaphragm,
 wherein one of the reflecting surfaces, on which a light beam passing through the diaphragm is made incident first, has negative power.   
   
   
       27 : The magnification projection optical system as claimed in  claim 26 , wherein another one of the reflecting surfaces, which another one is subsequent to the one having negative power, has positive power. 
   
   
       28 : The magnification projection optical system as claimed in  claim 25 , wherein:
 the reflecting surfaces of the reflection optical system have power and include at least one rotationally asymmetric reflecting surface; and   the transmitting surfaces of the transmission optical system have refractive power and include at least one aspheric surface.   
   
   
       29 : The magnification projection optical system as claimed in  claim 28 , wherein the rotationally asymmetric reflecting surface is positioned at a furthest downstream end of the second optical system in a projection optical path. 
   
   
       30 : The magnification projection optical system as claimed in  claim 25 , wherein the transmission optical system includes a rotationally asymmetric transmitting surface having refractive power. 
   
   
       31 : The magnification projection optical system as claimed in  claim 25 , wherein the transmission optical system has an optical axis set to be decentered with respect to a position of the image display panel in a plane including a light guide path. 
   
   
       32 : The magnification projection optical system as claimed in  claim 25 , wherein the reflection optical system is formed as a unit. 
   
   
       33 : A magnification projection apparatus that: displays an image on an image display panel; illuminates the image display panel with light from a light source; and by a magnification projection optical system, guides a light beam from the image display panel to a screen in an upstream-downstream direction, projects the light beam from a direction inclined to a normal of the screen, and forms on the screen a magnified version of the image displayed on the image display panel, wherein:
 the magnification projection optical system comprises a reflection optical system and a transmission optical system;   the reflection optical system includes a plurality of reflecting surfaces having power and includes at least one rotationally asymmetric reflecting surface; and   the transmission optical system includes a transmitting surface having refractive power and includes at least one aspheric surface.   
   
   
       34 : A magnification projection apparatus that: displays an image on an image display panel; illuminates the image display panel with light from a light source; and by a magnification projection optical system, guides a light beam from the image display panel to a screen in an upstream-downstream direction, projects the light beam from a direction inclined to a normal of the screen, and forms on the screen a magnified version of the image displayed on the image display panel, wherein:
 the magnification projection optical system comprises:
 a transmission optical system including a plurality of transmitting surfaces; 
 a reflection optical system including a plurality of reflecting surfaces; and 
 a diaphragm; and 
 one of the reflecting surfaces, on which a light beam passing through the diaphragm is made incident first, has negative power. 
   
   
   
       35 : A magnification projection apparatus that: displays an image on an image display panel; illuminates the image display panel with light from a light source; and by a magnification projection optical system, guides a light beam from the image display panel to a screen in an upstream-downstream direction, projects the light beam from a direction inclined to a normal of the screen, and forms on the screen a magnified version of the image displayed on the image display panel, wherein:
 a position and a shape of an intermediate image of the image display panel formed with negative magnification by light beams traveling from the image display panel to the screen are substantially identical to a position and a shape, respectively, of an intermediate image of the screen formed with negative magnification by light beams traveling from the screen to the image display panel.   
   
   
       36 - 76 . (canceled)