Optical system for liquid crystal projector

• US 5,389,982 A
• Filed: 07/01/1993
• Issued: 02/14/1995
• Est. Priority Date: 12/26/1990
• Status: Expired due to Fees

• Current Assignee: Goldstar Jewellery LLC
• Original Assignee: Goldstar Jewellery LLC
• Inventors: Lee, Seung G.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Dowling, William C.
• Application Number:
  US08/084,448
• Time in Patent Office: 593 Days
• Field of Search: 353/30, 353/31, 353/33, 353/34, 353/37, 353/69, 353/70, 353/20, 359/40, 359/63, 359/70, 359/48
• US Class Current: 353/37
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10

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. The light source emits a light having spectral characteristics in that the radiation of the red light element thereof is less intense than those of the green and the blue light elements, for thereby improving the color tone of the image. The polarized light prism and the reflection liquid crystal panels causes the optical path of the optical system to be shorter, for thereby improving the resolution of the color of the image and for also simplifying the construction of the optical system.

Claims

1. An optical system for a liquid crystal projector, comprising:

a light source of high luminance for emitting a light;

a polarized light prism for separating the light into polarized light of visible rays of three components having been emitted from said light source by reflection and transmitting the light in accordance with the polarized light of visible rays of three components, said polarized light prism being disposed at a front of said light source and spaced apart from said light source by a predetermined distance;

first reflecting means for selectively reflecting one component of the polarized light of visible rays of three components from said polarized light prism and allowing the two remaining components to pass therethrough;

second reflecting means for reflecting one of the two remaining components of the polarized light of visible rays of three components from said polarized light prism toward a first liquid crystal display panel by a first reflection mirror and reflecting the other of the two remaining components toward said polarized light prism by a second liquid crystal display panel;

composing means for composing the incident light having been reflected by said first and second reflecting means thereto into a composed color image; and

projecting means for projecting said composed color image on a screen, said projecting means being arranged at a side of said polarized light prism;

said first reflecting means including,

a first liquid crystal display for transmitting a polarized light transmitted from said polarized light prism, and

a reflection mirror for transmitting a component besides a predetermined color component and reflecting a predetermined color component of the polarized light transmitted from said liquid crystal display, said reflection mirror being disposed at a rear surface of said liquid crystal display.

2. An optical system according to claim 1, wherein said first reflection mirror reflects only said one component of the polarized light of visible rays of three components reflected by the polarized light prism at a predetermined angle and said second reflecting means includes,

a first reflecting panel for transmitting or reflecting said one of the polarized light of visible rays of three components being reflected by said first reflection mirror, and

a second reflecting panel for transmitting or reflecting one of the two components besides said one component of the polarized light of visible rays of three components from said first reflection mirror.

3. An optical system according to claim 2, wherein said first reflection mirror is mounted between the polarized light prism and the second reflecting panel at a 45°

inclination to the light incident thereto.

4. An optical system according to claim 2, wherein said first reflecting panel includes:

a liquid crystal display for transmitting a light of said one component of the polarized light of visible rays of three components reflected by said first reflection mirror; and

a reflection mirror for reflecting the light being transmitted through the second liquid crystal display to said first reflection mirror in an opposite direction to light incident to said second liquid crystal display, said reflection mirror being disposed at a rear surface of the second liquid crystal display.

5. An optical system according to claim 2, wherein said second reflecting panel includes:

a liquid crystal display for transmitting a light having two-color components being transmitted from said first reflection mirror; and

reflection mirror for reflecting a predetermined color component of light which is transmitted through said second liquid crystal display, selectively, to said first reflection mirror, said reflection mirror being disposed at a rear surface of said liquid crystal display.