Three lamp, three light valve projection system

• US 5,654,775 A
• Filed: 12/27/1995
• Issued: 08/05/1997
• Est. Priority Date: 12/27/1995
• Status: Expired due to Fees

• Current Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Original Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Inventors: Brennesholtz, Matthew Scott
• Primary Examiner(s): LEE, MICHAEL
• Application Number:
  US08/579,657
• Time in Patent Office: 587 Days
• Field of Search: 348/742, 348/743, 348/744, 348/750, 348/761, 348/756, 348/757, 348/758
• US Class Current: 348/742
• 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 9/3155 for controlling the light source light source control per se H05B35/00 – H05B47/00; control of an illumination source for displays in general G09G3/3406
• CPC Class Codes: H04N 9/3164 using multiple light sources

Abstract

In a three lamp, three light valve projection system, the lamps are energized sequentially in a three phase illumination cycle. The light therefrom is separated by an optical system composed of a three by three array of nine mirrors, all but one of which must be dichroic, to produce red, green, blue color sequential illumination of each light valve. Each light valve, which is controlled by a different control signal derived from an input video signal, is illuminated by a different color sequence such that during each phase of the illumination cycle, each light valve is illuminated by a different color. When the output beams from the light valves are converged over the same area of a screen, the phases of the illumination cycle occur at the field rate of the input video signal, whereas, when the output beams are arranged to produce a tiled image, the phases of the illumination cycle occur at three times the field rate.

Claims

1. A projection system in which three output light beams are formed for projection on a screen in accordance with an illumination cycle having three phases for displaying a video image in response to an input video signal, said system comprising:

three light sources which are sequentially activatable during respective different phases of the illumination cycle;

three light valves positioned for controlling respective different ones of the output light beams in response to said input video signal; and

an optical system intermediate the three light sources and the three light valves for separating light from each light source into three colors and directing the light of each color separated from the same light source to a different one of the three light valves, in a manner that each light valve sequentially receives input light in a different sequence of the three colors during the illumination cycle.

2. The projection system as claimed in claim 1, further comprising means for converging the three output light beams projected onto the screen and wherein the phases of the illumination cycle occur at the field rate of the input video signal.

3. The projection system as claimed in claim 1, further comprising means for tiling the three output light beams projected onto the screen and wherein the illumination cycle occurs at the field rate of the input video signal.

4. The projection system as claimed in claim 1, wherein said optical system has a same optical path length from each of the three light sources to each of the three light valves.

5. The projection system of claim 4, further comprising another optical system intermediate the light valves and the screen providing a same optical path length from each of the three light valves to the screen.

6. The projection system as claimed in claim 2, wherein said optical system has a same optical path length from each of the three light sources to each of the three light valves.

7. The projection system of claim 6, further comprising another optical system intermediate the light valves and the screen providing a same optical path length from each of the three light valves to the screen.

8. The projection system as claimed in claim 3, wherein said optical system has a same optical path length along nine optical paths directed from each of the three light sources to each of the three light valves.

9. The projection system of claim 4, further comprising another optical system intermediate the light valves and the screen providing a same optical path length from each of the three light valves to the screen.

10. The projection system as claimed in claim 1, further comprising:

means for sequentially activating the three light sources during the respective different phases of the illumination cycle; and

means for converting the input video signal to three different color sequential control signals, each controlling a different one of the three light valves.

11. The projection system as claimed in claim 2, further comprising:

means for sequentially activating the three light sources during the respective different phases of the illumination cycle; and

means for converting the input video signal to three different color sequential control signals, each controlling a different one of the three light valves.

12. The projection system as claimed in claim 3, further comprising:

means for sequentially activating the three light sources during the respective different phases of the illumination cycle; and

means for converting the input video signal to three different color sequential control signals, each controlling a different one of the three light valves.