Rotatable projection lens and projector

Abstract

A projection lens is separated by a second mirror into a first optical system that is disposed so as to be closer to an image forming panel and a second optical system that includes the second mirror and is disposed so as to be closer to a screen which is a projection surface. The second optical system is held rotatably around a second optical axis with respect to the first optical system by a first rotation mechanism. A rotation angle of the second optical system with respect to the first optical system is detected by a first sensor. Atilt angle of the projected image on the projection surface by the rotation angle is obtained by a tilt correction section, and the display position of the image to be displayed on the image forming panel is corrected according to the tilt angle.

What is claimed is: 
     
         1 . A projector comprising:
 a casing;   an image forming panel in the casing; and   a projection lens projecting an image on the image forming panel onto a projection surface, and being attached to the casing of the projector, the projection lens comprising:   a first mirror to bend a first optical axis to a second optical axis;   a second mirror to bend the second optical axis to a third optical axis;   a first optical system including the first mirror and disposed on the image forming panel side with respect to the second mirror in an optical path;   a second optical system including the second mirror and disposed on the projection surface side with respect to the first optical system in the optical path;   a first rotation mechanism holding the second optical system rotatably around the second optical axis with respect to the first optical system;   a second rotation mechanism holding the first optical system rotatably with respect to the casing; and   a barrel through which light of the second optical axis passes, and   wherein a tip of the projection lens is located inside the casing from an end of the casing in a side view, in a case where the barrel follows a vertical direction at a first position.   
     
     
         2 . The projector according to  claim 1 ,
 wherein the second optical system includes an emission lens emitting the image,   wherein the projection lens is movable from the first position to a second position by a rotation of the first rotation mechanism,   wherein the vertical direction includes a first side and a second side opposing to the first side,   wherein the projection lens projects the image through a region of the first side of the emission lens, in a case in which the projection lens is at the first position, and   wherein the projection lens projects the image through a region of the second side of the emission lens, in a case in which the projection lens is at the second position.   
     
     
         3 . The projector according to  claim 1 ,
 wherein the projection lens is movable between a third position in which the barrel extends to one side of the second direction and a fourth position in which the barrel extends to the other side of the second direction, upon rotation of the second rotation mechanism.   
     
     
         4 . The projector according to  claim 2 ,
 wherein the projection lens is movable between the third position and the fourth position without contacting the casing, upon rotation of the second rotation mechanism.   
     
     
         5 . The projector according to  claim 3  further comprising:
 a shift mechanism, 
 wherein the shift mechanism is disposed in the casing and shifts the projection lens including the second rotation mechanism in the first direction or the second direction 
 
     
     
         6 . The projector according to  claim 1 ,
 wherein the barrel has a first lens and a second lens closer to the first mirror than the first lens, and a diameter of the second lens is larger than a diameter of the first lens.   
     
     
         7 . The projector according to  claim 2 ,
 wherein the barrel has a first lens and a second lens closer to the first mirror than the first lens, and a diameter of the second lens is larger than a diameter of the first lens.   
     
     
         8 . The projector according to  claim 1 , further comprising:
 a tilt correction section for correcting a tilt of an image due to the rotation of the first rotation mechanism.   
     
     
         9 . The projector according to  claim 2 , further comprising:
 a tilt correction section for correcting a tilt of an image due to the rotation of the first rotation mechanism.   
     
     
         10 . The projector according to  claim 3 , further comprising:
 a tilt correction section for correcting a tilt of an image due to the rotation of the first rotation mechanism.   
     
     
         11 . The projector according to  claim 4 , further comprising:
 a tilt correction section for correcting a tilt of an image due to the rotation of the first rotation mechanism.   
     
     
         12 . The projector according to  claim 5 , further comprising:
 a tilt correction section for correcting a tilt of an image due to the rotation of the first rotation mechanism.   
     
     
         13 . The projector according to  claim 1 , further comprising:
 a first sensor for detecting a rotation angle of the second optical system with respect to the first optical system by the first rotation mechanism.   
     
     
         14 . The projector according to  claim 1 , further comprising:
 an operation switch provided in the casing for rotating the first rotation mechanism or the second rotation mechanism.   
     
     
         15 . The projector according to  claim 4 , wherein the shift mechanism shifts the projection lens including the second rotation mechanism in the first direction and the second direction. 
     
     
         16 . The projector according to  claim 1 , wherein the second optical system includes an emission lens emitting the image, and a diameter of the emission lens is the biggest in diameters of lenses of the first optical system and the second optical system. 
     
     
         17 . The projector according to  claim 1 , wherein the projection lens forms an intermediate image from a light of the image forming panel, and projects the intermediate image onto the projection surface. 
     
     
         18 . The projector according to  claim 1 ,
 wherein the second rotation mechanism is rotatable on a plane formed by a first direction, which is a horizontal direction, and a second direction, which is the vertical direction,   wherein the projection lens is capable of projecting an image onto a projection surface on the first direction side and a projection surface on a third direction side crossing the first direction and the second direction,   wherein the projection lens is capable of projecting an image onto a projection surface on the second direction side by the rotation of the second rotation mechanism that causes the barrel to follow the horizontal direction and the rotation of the first rotation mechanism.