Liquid crystal display projector

Abstract

A liquid crystal display projector comprising a light source, a group of mirrors, liquid crystal display devices, a projection lens, a main body containing the light source, group of mirrors, liquid crystal display devices and projection lens, and a mechanism whereby the projection lens is allowed to retract into and protrude from the main body. The projection lens comprises an outer cylinder having a ring-like shape; a drive motor with a gear; a ring-like intermediate cylinder with a first cam groove, second cam groove and gearwork provided on the exterior thereof with the gearwork meshing with the gear of the drive motor and is installed on the inner side of the outer cylinder so as to be made movable by sliding; a first inner cylinder having a first axis to fit in the first cam groove and fits with the inner surface of the intermediate cylinder in the front portion thereof so as to be movable by sliding according to the movement of the first axis caused by the rotation of the first cam groove; a second inner cylinder having a second axis to fit in the second cam groove and fits toward the back of the inner surface of the intermediate cylinder so as to be movable by sliding according to the movement of the second axis caused by the rotation of the second cam groove; and a plurality of lenses installed in the cylinders at specified positions. The projection lens operates such that driving of the drive motor causes the intermediate cylinder to rotate and the rotation of the intermediate cylinder allows the projection lens to zoom by extending and retracting the first inner cylinder.