Apparatus for projecting colored images

• US 5,398,081 A
• Filed: 06/07/1993
• Issued: 03/14/1995
• Est. Priority Date: 06/07/1993
• Status: Expired due to Fees

• Current Assignee: Raychem Corporation (TE Connectivity Limited)
• Original Assignee: Raychem Corporation (TE Connectivity Limited)
• Inventors: Jones, Philip J.
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): LEE, MICHAEL
• Application Number:
  US08/074,570
• Time in Patent Office: 645 Days
• Field of Search: 358/60-63, 358/59, 358/55, 358/231-233
• US Class Current: 348/742
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• CPC Class Codes: G02B 27/149 using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes
• 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 color projection display uses a dichroic cube for modulating the color of light reaching the imaging element of the display. This way, a colored image may be projected by frame sequential technique, but with the use of only a single imaging element.

Claims

1. An apparatus for projecting a colored image onto a screen, comprising:

light source means for generating white light;

image cell means on which an image to be displayed may be formed, which image cell means imparts an image to be displayed to light reaching the image cell means from the light source means;

color modulator means for modulating the color of the light reaching the image cell means from the light source means, the color modulator means being optically positioned between the image cell means and the light source means and comprising a dichroic cube for separating white light from the light source means into plural component colored light beams and light valve means for controlling which of the plural component light beams exits the color modulator means and reaches the image cell means;

controller means for controlling the image formed on the image cell means and the color of the light exiting the color modulator means, the controller means synchronizing the formation of images on the image cell means and the modulation of light color by the color modulator means such that the color of the light reaching the image cell means at a particular time corresponds to the color of the image formed on the image cell means at that particular time; and

projection lens for projecting imaged light from the image cell means onto a screen;

wherein the light valve means comprises reflector means associated with each colored light beam, each reflector means being independently controllably reflective or non-reflective, to affect whether each respective component colored light beam is reflected or not by the reflector means and forms part of the exiting light beam, thereby determining the color of the light exiting the dichroic cube.

2. An apparatus according to claim 1, wherein the image cell means is a reflective image cell means.

3. An apparatus according to claim 1, wherein the image cell means is a transmissive image cell means.

4. An apparatus according to claim 1, further comprising prism means positioned in front of the dichroic cube for increasing the divergence between the light entering and exiting the dichroic cube means.

5. An apparatus according to claim 1, further comprising a focusing means for focusing light entering the dichroic cube to a disk of least diameter at the reflector means.

6. An apparatus according to claim 1, wherein the reflector means comprises encapsulated liquid crystal material and a reflective surface means positioned therebehind.

8. An apparatus according to claim 6, wherein the image cell means is a transmissive image cell means.

9. An apparatus according to claim 1, wherein the image cell means is divided into a plurality of segments on each of which a portion of an image may be independently formed and each reflector means is divided into a plurality of segments, each of which may be independently controlled to be reflective or non-reflective, and is associated with a segment of the image cell means;

the controller means synchronizing the reflectivity of each segment of the reflector means to correspond to the presence or not of image information on the associated segment of the image cell means and the color of that image.

10. An apparatus according to claim 9, wherein the image cell means is a reflective image cell means.

11. An apparatus according to claim 9, wherein the image cell means is a transmissive image cell means.

12. An apparatus according to claim 9, further comprising prism means positioned in front of the dichroic cube means for increasing the divergence between the light entering and exiting the dichroic cube.

13. An apparatus according to claim 9, further comprising a focussing means for focussing light entering the dichroic cube to a disk of least diameter at the reflector means.

14. An apparatus according to claim 9, wherein the reflector means comprises encapsulated liquid crystal material and a reflective surface means positioned therebehind.

15. An apparatus according to claim 14, wherein the image cell means is a reflective image cell means.

16. An apparatus according to claim 14, wherein the image cell means is a transmissive image cell means.

7. An apparatus according to claim 7, wherein the image cell means is a reflective image cell means.