SLM-base color projection display having multiple SLM's and multiple projection lenses

• US 6,643,069 B2
• Filed: 08/28/2001
• Issued: 11/04/2003
• Est. Priority Date: 08/31/2000
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Dewald, Duane Scott
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): TRA, TUYEN Q
• Application Number:
  US09/940,978
• Publication Number:
  US 20020030893A1
• Time in Patent Office: 798 Days
• Field of Search: 359/621, 359/619, 359/625, 359/629, 359/627, 359/631, 353/35, 353/48, 353/34, 353/49, 353/30, 353/31
• US Class Current: 359/629
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• 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 unit (20, 30) for color projection display system that has three SLMs (21, 31) and three projection lenses (27, 37). Each SLM (21, 31) receives light of a different primary color, which it modulates to form images for that color. Each SLM (21, 31) and its associated projection lens (27, 37) provides a “channel” for that color of the final image, with the channels being converged out of the projection lenses (27, 37) to the viewing screen.

Claims

1. An optical unit for a spatial light modulator (SLM)-based color projection display system having a white light source, comprising:

three SLMs, each operable to receive light of a different primary color and to generate images of that color;

a filter at the face of each of at least two of the SLMs, each said filter operable to filter the light from said source such that it provides one of the colors to that SLM and reflects light of other colors;

a projection lens associated with each SLM, each said projection lens operable to receive the images generated by its associated SLM and to direct the images to a viewing plane; and

wherein said projection lenses are positioned such that the images from each said projection lens converge at the viewing plane.

2. The optical unit of claim 1, wherein said SLMs are digital micro mirror devices.

3. A method of generating a color projection display, comprising the steps of:

addressing three spatial light modulators (SLMs) with image data for images of a different primary color;

providing a white light source beam;

filtering the source beam such that each SLM is illuminated with light of one of the primary colors by placing each filter is placed at the face of the associated SLM, such that it transmits the color associated with that SLM and reflects other colors;

using a different projection lens associated with each SLM to direct the images to a viewing plane; and

positioning the projection lenses such that the images converge at the viewing plane.

4. The method of claim 3, wherein the SLMs are digital micro mirror devices.

5. The method of claim 3, further comprising the step of placing at least one additional filter along the path from the source to any of the projection lenses, the additional filter operable to filter out wavelengths of light not desired to reach the viewing plane.

6. The method of claim 3, wherein the filtering step is performed such that the filters receive the light from the source in an order that requires a filter associated with only two of the SLMs.

7. The method of claim 3, wherein the filtering step is performed such that the filters receive the light from the source in an order that requires a filter associated with each of the SLMs.

8. An optical unit for a spatial light modulator (SLM)-based color projection display system having a white light source, comprising:

three SLMs, each operable to receive light of a different primary color, and to generate images of that color;

a filter at the face of at least two of the SLMs, each filter operable to transmit the light from the source to the SLM such that it provides one of the colors to that SLM and each filter operable to reflect light of other colors;

two reflector units, each reflector unit operable to receive light reflected by the filter of the preceding SLM and to reflect light to the filter of the next SLM, such that the reflector units direct light from the source along an angular optical path from a first SLM to a second SLM and to a third SLM; and

a projection lens associated with each SLM, each projection lens operable to receive the images generated by its associated SLM and to direct the images to a viewing plane; and

wherein the projection lenses are positioned such that the images from each projection lens converge at the viewing plane.

9. The optical unit of claim 8, wherein a first filter is placed at the face of the first SLM and a second filter is placed at the face of the second SLM, each filter operable to transmit light of a different primary color such that the light reflected from the second filter has the color associated with the third SLM.

10. The optical unit of claim 8, wherein a filter is placed at the face of each SLM, each filter operable to transmit a color associated with that SLM.