Liquid crystal image projection with multicolor prepolarizing system

• US 4,749,259 A
• Filed: 05/15/1987
• Issued: 06/07/1988
• Est. Priority Date: 05/15/1987
• Status: Expired due to Term

• Current Assignee: Victor Company of Japan Limited (JVC Kenwood Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Ledebuhr, Arno G.
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/013,479
• Time in Patent Office: 389 Days
• Field of Search: 350/331 R, 350/337, 350/342, 350/403, 350/401, 350/402, 350/408, 350/173, 350/174, 358/225, 358/226, 358/232, 358/237, 353/31, 353/33, 353/37, 353/20
• US Class Current: 349/8
• 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
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

An optical system for a full color liquid crystal light valve image projector is provided. The invention includes a first prepolarizer for separating from a first beam light of first and second colors and a first polarization state and a second prepolarizer for separating from the first beam light of a third color and a second polarization state. The resultant first beam contains light of a third color and first polarization state and light of first and second colors and second polarization state. A polarization selective beamsplitter is provided in the optical path of the first beam for transmitting, in a second beam, light in the first beam having the first polarization state and reflecting, in a third beam, light in the first beam having the second polarization state. A color selective beamsplitter is included for transmitting, in a fourth beam, light in the third beam having a first color and for reflecting, in a fifth beam, light in the third beam having a second color. In the illustrative embodiments, the invention includes first and second reflective surfaces for reflecting the second and fifth beams respectively into a parallel coplanar relation with the fourth beam. The invention permits the light valves and associated CRT assemblies to be located in a parallel coplanar relation. The present invention thereby provides a compact design for a liquid crystal light valve image projection systems.

Claims

1. An optical system for a full color liquid crystal light valve image projector comprising:

a first prepolarizer for separating from a first beam light of first and second colors and a first polarization state;

a second prepolarizer for separating from said first beam light of a third color and a second polarization state so that the first beam contains light of a third color and first polarization state and light of first and second colors and second polarization state;

a polarization selective beamsplitter for transmitting, in a second beam, light in said first beam having said first polarization state and reflecting, in a third beam, light in said first beam having said second polarization state; and

a color sensitive beamsplitter for transmitting, in a fourth beam, light in said third beam having a first color and for reflecting, in a fifth beam, light in said third beam having a second color.

2. The optical system of claim 1 including first and second reflective surfaces for reflecting said second and fifth beams respectively into a parallel coplanar relation with said fourth beam.

3. The optical system of claim 2 wherein said first prepolarizer is mounted in an optical orientation which is normal to that of said second prepolarizer, said polarization selective beamsplitter and said color selective beamsplitter.

4. An optical system for a full color liquid crystal light valve image projector comprising:

a first prepolarizer for separating from a first beam light of a first color and a first polarization state;

a second prepolarizer for separating from said first beam light of second and third colors and a second polarization state so that the first beam contains light of a first color and second polarization state and light of second and third colors and first polarization state;

a polarization selective beamsplitter for transmitting, in a second beam, light in said first beam having said first polarization state and reflecting, in a third beam, light in said first beam having said second polarization state; and

a color sensitive beamsplitter for transmitting, in a fourth beam, light in said second beam having said second color and for reflecting, in a fifth beam, light in said second beam having said third color.

5. The optical system of claim 4 including first and second reflective surfaces for reflecting said third and fifth beams respectively into a parallel coplanar relation with said fourth beam.

6. The optical system of claim 5 wherein said first prepolarizer is mounted in an optical orientation which is normal to that of said second prepolarizer, said polarization selective beamsplitter and said color selective beamsplitter.

7. A full color liquid crystal light valve image projection system comprising:

means for providing an incident beam of unpolarized white light;

a unitary optical arrangement comprising;

a first prepolarizer for separating from a first beam light of first and second colors and a first polarization state;

a second prepolarizer for separating from said first beam light of a third color and a second polarization state so that the first beam contains light of a third color and first polarization state and light of first and second colors and second polarization state;

a polarization selective beamsplitter for transmitting, in a second beam, light in said first beam having said first polarization state and reflecting, in a third beam, light in said first beam having said second polarization state;

a color selective beamsplitter for transmitting, in a fourth beam, light in said third beam having a first color and for reflecting, in a fifth beam, light in said third beam having a second color;

first and second reflective surfaces for reflecting said second and fifth beams respectively into a parallel coplanar relation with said fourth beam;

first, second and third parallel, coplanar liquid crystal light valves for modulating the polarization states of said fourth, fifth, and second beams respectively and for reflecting said polarization modulated fourth, fifth and second beams to said polarization selective beamsplitter for recombination into a single output beam; and

a projection lense for displaying images contained in said output beam.

8. The full color liquid crystal light valve image projection system of claim 7 wherein said first prepolarizer is mounted in an optical orientation which is normal to that of said prepolarizer, said polarization selective beamsplitter and said color selective beamsplitter.

9. A full color liquid crystal light valve image projection system comprising:

means for providing an incident beam of unpolarized white light;

a unitary optical arrangement comprising;

a first prepolarizer for separating from a first beam light of a first color and a first polarization state;

a second prepolarizer for separating from said first beam light of second and third colors and a second polarization state so that the first beam contains light of a first color and second polarization state and light of second and third colors and first polarization state;

a polarization selective beamsplitter for transmitting, in a second beam, light in said first beam having said first polarization state and reflecting, in a third beam, light in said first beam having said second polarization state;

a color selective beamsplitter for transmitting, in a fourth beam, light in said second beam having said second color and for reflecting, in a fifth beam, light in said second beam having said third color;

first and second reflective surfaces for reflecting said third and fifth beams respectively into a parallel coplanar relation with said fourth beam;

first, second and third parallel, coplanar liquid crystal light valves for modulating the polarization states of said third, fourth, and fifth beams respectively and for reflecting said polarization modulated third, fourth and fifth beams to said polarization selective beamsplitter for recombination into a single output beam; and

a projection lense for displaying images contained in said output beam.

10. The full color liquid crystal light valve image projection system of claim 9 wherein said first prepolarizer is mounted in an optical orientation which is normal to that of said second prepolarizer, said polarization selective beamsplitter and said color selective beamsplitter.