Optical block for high brightness full color video projection system

• US 4,191,456 A
• Filed: 03/08/1979
• Issued: 03/04/1980
• Est. Priority Date: 03/08/1979
• Status: Expired due to Term

• Current Assignee: JVC Americas Corporation (JVC Kenwood Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Colles, Joseph H., Reinsch, Stephen J., Scofield, David D., Purdy, Stephen J., Hong, Byung S.
• Primary Examiner(s): Stephan, Steven L.
• Application Number:
  US06/018,691
• Time in Patent Office: 362 Days
• Field of Search: 353/31, 353/34, 353/37, 350/156, 350/173, 350/342, 358/56, 358/61
• US Class Current: 353/31
• 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 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

An improved optical block for use in a high brightness, full color image projection system of the type wherein high intensity (acrhomatic) projection light is modulated by a full color image composed of a plurality of monochromatic images applied to a plurality of polarization modulating light valves. A polarizer accepts the achromatic, unpolarized output of a high intensity source. Light of a preferred polarization orientation emergent therefrom is directed by the polarizer to a two level array of polarization-sensitive dichroic filters and wavelength-tuned biprisms. Input level dichroic filters separate the incoming unmodulated light into a plurality of component wavelength bands and direct each to a wavelength-tuned biprism. Each biprism directs the selected bandwidth of polarized light to the reflective surface of a light valve. Light reflected therefrom is altered in polarization in the presence of the chromatic component of the full color image and passes to the second or output level of the optical block. Polarization selective dichroic filters in the output level combine the polarization-modulated chromatic components into a high brightness, full color modulated image and direct the image to projection optics.

Claims

1. An improved optical block for use in a high brightness full color video projector of the type wherein a beam of collimated white light from a high intensity source is modulated with the primary color components of at least three video sources by means of a first, second and third reflection type polarization state modulation means, each of said means for spatially modulating a primary color component video image in real time, said optical block comprising:

(a) a first polarizing means positioned to receive said collimated projection light for prepolarizing said light along a first plane and a second plane, said first and second planes being mutually orthogonal and for directing said light polarized along said first plane and said light polarized along said second plane along mutually orthogonal paths;

(b) means for projecting said full color image;

(c) input filter means located on a first level for separating collimated unmodulated polarized white light leaving said first polarizing means into three beams of collimated polarized light of different primary colors;

(d) relay mirror means for redirecting said three beams of collimated polarized light of different primary colors in a direction perpendicular to said first level;

(e) first, second and third wavelength-tuned polarizer/analyzers located on a second level and positioned to receive said three beams of collimated polarized light of different primary colors;

(f) said first, second and third wavelength tuned polarizer/analyzers being arrayed to direct said three beams of collimated polarized light of different primary colors to the surface of said first, second and third reflection type polarization state modulation means so that the state of polarization of the light in said beams is modulated by the primary color component video images and each reflected to one of said wavelength-tuned polarizer/analyzers to be polarization analyzed;

(g) output filter means located on a second level positioned to receive the image modulated portion of said polarization-analyzed beams so as to recombine said three beams into said full color image for projection by said means for projecting said full color image, the optical path length from said means along any of said three primary color beams to the reflection and modulation means for modulating said beam being equal to said path length along any other of said beams and said reflection and modulation means being positioned so that said projection lens means simultaneously images and superimposes the three primary color component images 55 formed separately at each of said reflection and modulation means in said respective collimated light beams to form said full color image without the interposition of any lens in the optical path between said means for projecting said full color image and said reflection and modulation means.

2. An improved optical block as defined in claim 1 additionally characterized in that said input filter means have a first polarization orientation and said output filter means have a second polarization orientation.

3. An improved optical block as defined in claim 2 wherein said means for projecting said full color image comprises a single projection lens.

4. An improved optical block as defined in claim 2 additionally characterized in that said input filter means comprises two dichroic filters which lie along and are oriented 45 degrees with respect to one of the two mutually orthogonal optical paths of the light polarized along a first plane and a second plane by said first polarizing means.

5. An improved optical block as defined in claim 4 additionally characterized in that said output filter means comprises two dichroic filters which lie in and are oriented 45 degrees with respect to an optical path between one of said three wavelength-tuned polarizer/analyzers and said means for projecting said full color image.

6. An improved optical block for use in a high brightness full color video projector of the type wherein a beam of collimated white light from a high intensity source is modulated with the primary color components of at least three video sources by means of a first, second and third reflection type polarization state modulation means, each of said means for spatially modulating a primary color component video image in real time, said optical block comprising:

(a) a first polarizing multi-refractive layer means positioned to receive said collimated projection light for prepolarizing said light along a first plane and a second plane, said first and second planes being mutually orthogonal and for directing said light polarized along said first plane and said light polarized along said second plane along mutually orthogonal paths;

(b) a single projection lens for projecting said full color image;

(c) input dichroic filter means having a first polarization orientation and located on a first level for separating collimated unmodulated polarized white light leaving said first multirefractive layer into three beams of collimated polarized light of different primary colors, said means comprising two dichroic filters which lie along and are oriented 45 degrees with respect to one of the two mutually orthogonal optical paths of the light polarized along a first plane and a second plane by said first polarizing multi-refractive layer;

(d) relay mirror means for redirecting said three beams of collimated polarized light of different primary colors in a direction perpendicular to said first level;

(e) first, second and third wavelength-tuned polarizer/analyzer multi-refractive layers located on a second level and positioned to receive said three beams of collimated polarized light of different primary colors;

(f) said first, second and third wavelength tuned polarizer/analyzer multi-refractive layers being arrayed to direct said three beams of collimated polarized light of different primary colors to the surface of said first, second and third reflection type polarization state modulation means so that the state of polarization of the light in said beams is modulated by the primary color component video images and each reflected to one of said wavelength-tuned multi-refractive layer means to be polarization analyzed;

(g) output dichroic filter means having a second polarization orientation and located on a second level positioned to receive the image modulated portion of said polarization-analyzed beams so as to recombine said three beams into said full color image for projection by said projection lens, said means comprising two dichroic filters which lie in and are oriented 45 degrees with respect to an optical path between one of said three wavelength-tuned multi-refractive layer means and said projection lens, the optical path length from said projection lens along any of said three primary color beams to the reflection and modulation means for modulating said beam being equal to said path length along any other of said beams and said reflection and modulation means being positioned so that said projection lens means simultaneously images and superimposes the three primary color component images formed separately at each of said reflection and modulation means in said respective collimated light beams to form said full color image without the interposition of any other lens in the optical path between said projection lens and said reflection and modulation means.