Liquid crystal type rear-projection television with a reduced cabinet depth

• US 5,278,595 A
• Filed: 10/06/1992
• Issued: 01/11/1994
• Est. Priority Date: 10/07/1991
• Status: Expired due to Fees

• Current Assignee: Pioneer Electronics (USA) Incorporated (Pioneer Corporation)
• Original Assignee: Pioneer Electronics (USA) Incorporated (Pioneer Corporation)
• Inventors: Nishida, Masami, Yoshida, Tadashi, Izawa, Masataka
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Dowling, William C.
• Application Number:
  US07/957,007
• Time in Patent Office: 462 Days
• Field of Search: 353/37, 353/31, 353/74, 353/77, 353/78, 353/98, 353/99, 353/119, 358/60, 358/231
• US Class Current: 353/78
• 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

A liquid crystal projector is obliquely disposed in a lower front portion of a cabinet. A first mirror for reflecting light beams of R, G and B coming from the liquid crystal projector is disposed obliquely with respect to the top-bottom, right-left and front-rear directions of the cabinet. A second mirror is disposed so as to be inclined toward a screen. With this configuration, the optical axis of the light beams that extends from the liquid crystal projector to the screen is folded back three-dimensionally. In the liquid crystal projector, the optical axis of a condensing reflector may be slightly inclined from the central axis of a projection lens.

Claims

1. A liquid crystal type rear-projection television comprising:

a liquid crystal projector including light source means, liquid crystal panels for red, green and blue and a projection lens, for producing light beams of red, green and blue that carry a color image by passing while light provided by the light source means through the liquid crystal panels, and for outputting the light beams through the projection lens;

at least two mirrors for sequentially reflecting the light beams coming from the liquid crystal projector; and

a screen for receiving, at its rear surface, the light beams reflected from a last one of the at least two mirrors to display the color image at its front surface;

wherein the liquid crystal projector and the at least two mirrors are arranged so that an optical axis of the light beams extending from the liquid crystal projector to the screen is folded back three-dimensionally; and

wherein at least one of the at least two mirrors is arranged obliquely with respect to all of top-bottom, right-left and front-rear directions.

2. The liquid crystal type rear-projection television of claim 1, wherein the liquid crystal projector is disposed so as to deviate from a center of the rear-projection television in the right-left direction.

3. The liquid crystal type rear-projection television of claim 1, wherein at least one of the at least two mirrors has an irregular tetragon reflection plane.

4. The liquid crystal type rear-projection television of claim 1, wherein an optical axis of the light source means is inclined from a central axis of the projection lens of the liquid crystal projector.

5. The liquid crystal type rear=projection television of claim 4, wherein the liquid crystal projector further includes a first three-color separating/combining prism device for separating the white light provided from the light source means into three light beams to be input to the respective liquid crystal panels, and a second three-color separating/combining prism device for combining the light beams provided from the respective liquid crystal panels to form a single light beam carrying the color image.

6. A liquid crystal type rear-projection television comprising:

a liquid crystal projector including light source means, liquid crystal panels for red, green and blue and a projection lens, for producing light beams of red, green and blue that carry a color image by passing white light provided by the light source means through the liquid crystal panels, and for outputting the light beams through the projection lens;

at least two mirrors for sequentially reflecting the light beams coming from the liquid crystal projector; and

a screen for receiving, at its rear surface, the light beams reflected from a last one of the at least two mirrors to display the color image at its front surface;

wherein the liquid crystal projector and the at least two mirrors are arranged so that an optical axis of the light beams extending from the liquid crystal projector to the screen is folded back three-dimensionally; and

wherein the at least two mirrors consist of first and second mirrors, and wherein the optical axis of the light beams is expressed as;

space="preserve" listing-type="equation">Nm.sub.2 =aNm.sub.1 +bY

where a and b are constants, Nm₁ is a vector along a normal of the first mirror, Nm₂ is a vector along a normal of the second mirror, and Y is a vector along a shorter axis of the second mirror.

7. A method of displaying a color image in a liquid crystal type rear-projection television, comprising the steps of:

arranging a liquid crystal projector, at least two mirrors and a screen so that an optical axis of a light beam extending from the liquid crystal projector to the screen via the at least two mirrors is folded back three-dimensionally and that at least one of the at least two mirrors is arranged obliquely with respect to all of top-bottom, right-left, and front-rear directions;

producing light beams of red, green and blue that carry a color image by the liquid crystal projector;

sequentially reflecting the light beams coming from the liquid crystal projector by the at least two mirrors; and

projecting the light beams reflected from a last one of the at least two mirrors to a rear surface of the screen to display the color image at its front surface.