Abstract: Multipurpose projector having a detachable projecting unit including a body having a sheet of transparent glass disposed in the top part thereof and an attaching recess at one side of an optical system region therein; a projecting unit attachable into the attaching recess or disposable right over the transparent glass by means of rotatable post attached to the body at the user's option; a liquid crystal display projector part having a light source disposed movably in a vertical direction in rear part of the optical system in the body, a first focusing lens for focusing the light emitted from the light source, a liquid crystal panel for receiving light focused by the first focusing lens, and a zoom lens; an overhead projector part disposed in the optical system in the body having a second focusing lens, a plurality of total reflection mirrors for deflecting a path of the light focused by the second focusing lens at a right angle from a horizontal direction to a vertical direction, and a Fresnel lens detachably

Abstract: An optical system of a liquid crystal projector includes a metal halide lamp as a light source of a high luminance, a polarized light prism for separating the light from the metal halide lamp into respective light elements of the visible rays in accordance with spectral characteristics of the light, a heat absorption filter for filtering off other rays except for the visible rays from the light in order to remove heat which is generated from the other rays, reflection liquid crystal panels which are each arranged at the front side or at a side of the polarized light prism and having a red, green or blue light reflection mirror mounted on the rear surface thereof, and a projection lens for composing the incident light elements from the liquid crystal panels into a composed color image and then projecting the composed color image on a screen.

Abstract: An optical system for an LCD projector comprising an illuminating device, an infrared filter, an optical system and a projecting lens comprises a 45.degree. horizontally inclined blue light tranmission filter, a 45.degree. horizontally inclined green light reflection mirror, a 45.degree. horizontally inclined red image reflection mirror, a 45.degree. horizontally inclined blue image transmission filter, three total reflection mirrors, three condensing lenses, three LCD panels, and separates red, green and blue light elements from the light having been transmitted through the infrared filter, then reemerging an image in respective colors by using the separated red, green and blue light elements in order to compose the reemerged image.