Arrangement for projection displays employing reflective light valves

• US 5,658,060 A
• Filed: 08/15/1996
• Issued: 08/19/1997
• Est. Priority Date: 01/10/1995
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Dove, Derek Brian
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US08/698,297
• Time in Patent Office: 369 Days
• Field of Search: 353/31, 353/33, 353/34, 353/37, 353/81, 353/94, 353/20, 359/40, 359/48, 359/49
• US Class Current: 353/33
• 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

Optical arrangements for a high definition projection display using reflective light valves. Separate polarizing means are placed in proximity to respective separate reflective light valves tuned to the color to be modulated. A combining prism assembly combines the light reflected from each valve and directs the light onto a projection display.

Claims

1. An apparatus for projecting a plurality of colors of light comprising:

a plurality of sources for each of said plurality of colors of light;

a plurality of spacial light modulators each corresponding to one of said colors of light;

a plurality of polarization means for directing each of said plurality of colors of light in a predetermined polarization onto each corresponding spacial light modulator at an angle which is perpendicular to said spacial light modulator, each of said polarization means being located directly against each corresponding spacial light modulator; and

a means for combining said plurality of colors of light reflected from said spacial light modulators into a combined beam, said polarization means being located between said combining means and said spacial light modulators.

2. The apparatus of claim 1 wherein said plurality of sources of colors of light include a source of blue light, a source of red light, and a source of green light, said plurality of spacial light modulators includes a first spacial light modulator, a second spacial light modulator, and a third spacial light modulator, said plurality of directing means includes a first means for directing said red light in a predetermined polarization onto said first spacial light modulator, a second means for directing said blue light in a predetermined polarization onto said second spacial light modulator;

and a third means for directing said green light in a predetermined polarization onto said third spacial light modulator, and wherein said combining means includes means for combining said red light reflected from said first spacial light modulator, said blue light reflected from said second spacial light modulator and said green light reflected from said third spacial light modulator into said combined beam.

3. The apparatus of claim 1, further including a means for projecting said combined beam onto a screen.

4. The apparatus of claim 1, wherein said apparatus is an apparatus for projecting a color image onto a screen.

5. The apparatus of claim 1, wherein said plurality of means for directing each of said plurality of colors of light in a predetermined polarization includes a plurality of polarizing beam splitting prisms.

6. The apparatus of claim 1, wherein said means for combining said plurality of colors includes a color combining prism assembly having a plurality of input faces for receiving reflected light of each of said plurality of colors in a corresponding input face.

7. The apparatus of claim 1, wherein each of said plurality of means for directing each of said plurality of colors of light in a predetermined polarization are in close proximity to each of said corresponding spacial light modulators.

8. The apparatus of claim 3, wherein said combining means is positioned between said projection means and said plurality of polarization means so that light traverses said combining means in one direction only.

9. The apparatus of claim 6, wherein said color combining prism assembly is comprised of three solid glass prisms arranged to form two internal reflecting surfaces for combining three colors of light.

10. The apparatus of claim 1, wherein said means for combining said plurality of colors includes a dichroic cross prism assembly for combining three color components received in three separate input faces and outputting the combined beam through an output face.

11. The apparatus of claim 1, wherein said means for combining said plurality of colors includes a plurality of dichroic mirror prisms.

12. The apparatus of claim 11, wherein said plurality of dichroic mirror prisms includes one of said prisms for reflecting a first color and one of said prism for reflecting a second color and transmitting a third color.

13. The apparatus of claim 1, further including a plurality of field lenses each positioned between said spacial light modulators and said polarization means.

14. The apparatus of claim 1, wherein each of said plurality of means for directing each of said plurality of colors of light in a predetermined polarization are attached to each of said corresponding spacial light modulators.