Projection device

• US 5,028,121 A
• Filed: 11/15/1989
• Issued: 07/02/1991
• Est. Priority Date: 06/19/1987
• Status: Expired due to Fees

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Seibel, Jorg, Baur, Gunter, Pickelmann, Lutz
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): GROSS, ANITA P
• Application Number:
  US07/439,386
• Time in Patent Office: 594 Days
• Field of Search: 350/331 R, 350/337, 353/20, 353/31, 353/33, 353/34, 353/81, 353/82, 353/84, 353/122
• US Class Current: 349/9
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

A projector has a light source (1) for producing a parallel beam of white light (4); two dichroic prisms (21, 22) each having two dichroic colour-splitting layers, which on three of their sides have three liquid crystal light valve arrangements (23, 24, 25, 26, 27, 28) associated with different components of the color image; a lens (8) through which the color image components produced by the light valve arrangements (23 to 28) can be projected together on to a screen. The light valve arrangements (23 to 28) associated with the two dichroic prisms operate by reflection. Each of the two dichroic prisms (21, 22) is coupled with one of the outlets of a polarizing beam splitter (10), said outlets being associated with different polarizing directions. The polarizing beam splitter (10) distributes the beam of white light (4, 6) to the two dichroic prisms (21, 22) and directs the light of the activated image points travelling back from the two dichroic prisms into the lens (8).

Claims

1. A projection device comprising:

light generating means for generating a white parallel light beam bundle;

a polarizing beam divider having at least two outputs allocated to different polarization directions;

at least two dichroic prisms respectively coupled to said outputs, each said dichroic prism including two dichroic color divider layers and three reflectively operating liquid crystal light valve arrangements allocated to three different color image separations, each said light valve arrangement having a matrix of driven image lines for forming a plurality of activatable image points for selectively reflecting color image separated light; and

an objective through which the reflected color image separated light from the activated image point is projected.

2. Device according to claim 1, wherein said beam divider is a McNeille prism.

3. Device according to claim 2, characterized in that the beam divider is housed in a cuvette filled with a highly refractive liquid.

4. Device according to claim 1, wherein said light valve arrangements have a reflecting layer on the side facing away from the dichroic prisms.

5. Device according to claim 1, wherein color filters are provided between said light valve arrangements and said dichroic prisms.

6. Device according to claim 1, wherein said two dichroic prisms are tilted to one another by 90 degrees and are coupled with sides of said beam divider oriented to one another by 90 degrees.

7. Device according to claim 1, wherein said beam divider is housed in a cuvette filled with a highly refractive liquid.

8. Device according to claim 1, wherein said beam divider includes a beam divider plate which extends along a diagonal in a cuvette that is filled with a highly refractive liquid and in which on both sides of the beam divider plate there are provided highly refractive wedge prisms.

9. Device according to claim 1, wherein said projections of the image lines of all six light valve arrangements cover one another.

10. Device according to claim 1, wherein the projections of the driven image lines of the light valve arrangement of a first said dichroic prism lie between the projections of the image lines of the light valves allocated to a second said dichroic prism.

11. Device according to claim 10, wherein the light valves allocated to said first dichroic prism and the light valves allocated to said second dichroic prism present a second partial image of a three-dimensional image with driven lines of different polarization direction.

12. Device according to claim 1, wherein the projections of the driven image lines of the light valves of a first said dichroic prism lie on the projections of the image lines of the light valves of a second said dichroic prism.