High brightness full color image light valve projection system

• US 4,127,322 A
• Filed: 12/05/1975
• Issued: 11/28/1978
• Est. Priority Date: 12/05/1975
• Status: Expired due to Term

• Current Assignee: JVC Americas Corporation (JVC Kenwood Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Grinberg, Jan, Jacobson, Alexander D., Boswell, Donald D., Sprotbery, Donald E.
• Primary Examiner(s): Stephan, Steven L.
• Application Number:
  US05/637,906
• Time in Patent Office: 1,089 Days
• Field of Search: 353/31, 353/34, 353/37, 353/120, 353/121, 353/122, 350/160 LC, 178/7.88, 358/56, 358/59, 358/61, 358/62
• 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

Abstract

There is disclosed an electro-optical system for real time projection of very high brightness, full color pictorial images from television or other program sources onto a large display screen from a set of three reflection type AC driven field effect mode birefringent liquid crystal light valves each of which modulates a primary color component video image onto a collimated beam of polarized light of a given primary color by modulating the polarization state thereof. In order to achieve very high brightness without overheating the system it is necessary that none of the optical elements forming the projection beam optical system absorb light in carrying out their function. Hence all projection beam optical processes are non-absorptive to first order. The light valves are devices that receive and reflect projection light from an independent high power light source while modulating onto the reflected light video images derived from a low level light source such as a cathode ray tube. The modulation onto the projection beam is achieved by modulating the state of polarization thereof. One such device is used for the red portion of the video image, a second for the green portion and a third for the blue portion. The optical system derives light from a white projection light source, polarizes it, splits it into the three primary colors, directs the three colored beams to the three light valves respectively for image modulation, collects the light that has been modulated by the light valves, recombines the three beams, and projects them onto the screen with sufficient registration to create full color range for the full color image. The optical system uses only a single projection lens and a single polarizing/analyzing beam splitter/recombiner and suitable dichroic mirrors. There is thus provided a simple, compact low weight, high brightness and high efficiency full color light valve image projection system for the projection of high brightness, full color, real time dynamic or static imagery which may include provision for overlay legends or other information as well as possible steroscopic or three dimensional perception by the viewer.

Claims

1. In an electro-optical system for projecting in real time very high brightness, full color images from television or other program sources onto a display screen, said system being of the type which additively synthesizes said images by superposition of at least three different primary images and which uses only projection beam optical processes which are non-absorptive to first order in order to avoid overheating the system, the improvement comprising:

(a) light source means for providing a collimated beam of white projection light;

(b) a single polarizer-analyzer beam splitter-recombiner multirefractive layer means positioned to receive said collimated projection light for polarizing and splitting it on a first pass therethrough and for analyzing it on a second pass therethrough for all three of said primary color images;

(c) single projection lens means for projecting said full color image to said display screen;

(d) dichroic mirror means for first separating collimated unmodulated polarized white light leaving said multirefractive layer means into three beams of collimated polarized light of different primary colors to be polarization state modulated and reflected, said dichroic mirror means then passing the three reflected modulated primary color collimated beams back to said multirefractive layer means for analyzing and recombining said three primary color beams to pass a resultant collimated full color image modulated beam from said single multirefractive layer beam splitter-recombiner means to said single projection lens means for forming said full color image; and

(e) first, second and third reflection type polarization state modulation means for spatially modulating a primary color component video image in real time onto each of said first, second and third collimated beams of polarized light of first, second and third primary colors respectively received from said dichroic mirror means by modulation of the state of polarization of the light in said respective beams and for reflecting said three beams back to said multirefractive layer means to be polarization analyzed and recombined into said full color image for projection by said single projection lens means, the optical path length from said projection lens 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 formed separately at each of said three reflection and modulation means in said respective collimated light beams to form said full color image without the interposition of any other lens means in the optical path between said projection lens means and said reflection and modulation means.

2. A system as in claim 1 wherein said light source means comprises an arc discharge lamp positioned between a collimating lens and a collimating mirror, said mirror, said lamp and said collimating lens being positioned in sequence on a first optic axis on a first side of said multirefractive layer means to direct said collimated projection light onto said multirefractive layer polarizing beam splitter means.

3. A system as in claim 2 wherein said projection lens means comprises a single projection lens and wherein said collimating lens in said light source and said single projection lens are the only lenses in said system.

4. A system as in claim 1 wherein said projection lens means comprises a single projection lens.

5. A system as in claim 1 wherein:

(a) said light source means and said multirefractive layer means are positioned on a first optic axis the direction of which is defined by the beam direction of a first polarization state component of said collimated projection light beam which on said first pass is transmitted through said multirefractive layer means; and

(b) said single projection lens means is positioned on a second optic axis for projecting said full color image along said second optic axis to said display screen, said second optic axis intersecting said first optic axis at said multirefractive layer means, said second optic axis extending in a direction defined by the beam direction of a second polarization state component of said collimated projection light beam which on said first pass is reflected by said multirefractive layer means and which polarization state is complementary to the polarization state of said transmitted beam.

6. A system as in claim 5 wherein said first, second and third reflection and modulation means each comprises a reflection type A.C. field effect mode liquid crystal light valve means, said system further including means for optically coupling each of said first, second and third liquid crystal light valve means to a cathode ray tube for deriving therefrom said video image which is modulated onto said beam of polarized light by said light valve.

7. A system as in claim 5 wherein said first and second optic axes intersect orthogonally at substantially the center of said multirefractive layer means, each making an angle of 45°

with said multirefractive layer means.

8. A system as in claim 1 wherein said first, second and third reflection and modulation means each comprises a reflection type A.C. field effect mode liquid crystal light valve means.

9. A system as in claim 8 and further including means for optically coupling each of said first, second and third liquid crystal light valve means to a cathode ray tube for deriving therefrom said video image which is modulated onto said beam of polarized light by said light valve.

10. In an electro-optical system for projecting in real time very high brightness, full color images from television or other program sources onto a display screen, said system being of the type which additively synthesizes said images by superposition of at least three different primary images and which uses only projection beam optical processes which are non-absorptive to first order in order to avoid overheating the system, the improvement comprising:

(a) light source means for providing a collimated beam of white projection light;

(b) a single polarizer-analyzer beam splitter-recombiner multirefractive layer means positioned to receive said collimated projection light for polarizing and splitting it on a first pass therethrough and for analyzing it on a second pass therethrough for all three of said primary color images;

said light source means and said multirefractive layer means being positioned on a first optic axis the direction of which is defined by the beam direction of a first polarization state component of said collimated projection light beam which on said first pass is transmitted through said multirefractive layer means;

said light source means being positioned on said first optic axis on a first side of said multirefractive layer means to transmit a beam of unpolarized light along said first optic axis, said multirefractive layer means making an angle 45°

with said first optic axis and transmitting a beam of white polarized light of "P" polarization state along said first optic axis and reflecting a beam of white polarized light of "S" polarization state complementary to said "P" state along said second optic axis;

(c) single projection lens means for projecting said full color image to said display screen;

said single projection lens means being positioned on a second optic axis for projecting said full color image along said second optic axis to said display screen, said second optic axis intersecting said first optic axis at said multirefractive layer means, said second optic axis extending in a direction defined by the beam direction of a second polarization state component of said collimated projection light beam which on said first pass is reflected by said multirefractive layer means and which polarization state is complementary to the polarization state of said transmitted beam;

(d) dichroic mirror means for first separating collimated unmodulated polarized white light leaving said multirefractive layer means into three beams of collimated polarized light of different primary colors to be polarization state modulated and reflected, said dichroic mirror means then passing the three reflected modulated primary color collimated beams back to said multirefractive layer means for analyzing and recombining said three primary color beams to pass a resultant collimated full color image modulated beam from said single multirefractive layer beam splitter-recombiner means to said single projection lens means for forming said full color image;

said dichroic mirror means comprising first and second dichroic mirrors positioned on said first optic axis at an angle of 45°

thereto on the second side of said multirefractive means opposite the first side, said first dichroic mirror reflecting light of a first of said primary colors and transmitting light of a second and third of said primary colors to said second dichroic mirror, said second dichroic mirror reflecting light of a second of said primary colors and transmitting light of a third of said primary colors;

(e) first, second and third reflection type polarization state modulation means for spatially modulating a primary color component video image in real time onto each of said first, second and third collimated beams of polarized light of first, second and third primary colors respectively received from said dichroic mirror means by modulation of the state of polarization of the light in said respective means and for reflecting said three beams back to said multirefractive layer means to be polarization analyzed and recombined into said full color image for projection by said single projection lens means;

said first, second and third reflection and modulation means each comprising a reflection type A.C. field effect mode liquid crystal light valve means, said system further including means for optically coupling each of said first, second and third liquid crystal light valve means to a cathode ray tube for deriving therefrom said video image which is modulated onto said beam of polarized light by said light valve;

said first and second liquid crystal light valve means being positioned on optic axes parallel to said second optic axis to receive and reflect light of said first and second primary colors respectively and said third liquid crystal light valve means being positioned on said first optic axis to receive and reflect light of said third primary color; and

,

(f) the optical path length from said projection lens means along any of said three primary colored 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 superposes the three primary colored component images formed separately at each of said three reflection and modulation means in said respective collimated light beams to form said full color image without the interposition of any other lens means in the optical path between said projection lens means and said reflection and modulation means.

11. A system as in claim 10 and further including a fourth liquid crystal light valve means positioned orthogonally to said second optic axis to receive said polarized light of "S" state reflected from said multirefractive layer means to modulate said light with overlay information to be superimposed on the full color image produced by said first, second and third liquid crystal light valve means.

12. A system as in claim 10 and further including

(a) third and fourth dichroic mirror means, said third dichroic mirror means being positioned at an angle of 45°

to said second optic axis to receive the "S" polarization state light reflected from said multireflective layer means and said fourth dichroic means being positioned parallel to said third dichroic means on a third optic axis parallel to said first optic axis and intersecting said second optic axis substantially at the center of said third dichroic mirror means;

said third dichroic mirror means transmitting said first primary color light and reflecting light of said second and third primary colors, said fourth dichroic mirror means reflecting light of said second primary color and transmitting light of said third primary color; and

(d) fourth, fifth and sixth liquid crystal light valve means respectively positioned to receive said first primary color light transmitted by said third dichroic mirror, said second primary color light reflected by said fourth dichroic mirror, and said third primary color light transmitted by said fourth dichroic mirror means.

13. A system as in claim 12 wherein video information representing a left eye view of a given image is modulated onto said primary color light beams by said first, second and third liquid crystal light valve means and corresponding video information representing a right eye view is modulated onto said primary color light beams by said fourth, fifth and sixth liquid crystal light valve means, said system thereby projecting onto said screen an image containing stereoscopic three dimensional information which may be viewed as such through lenses for the left and right eyes having respectively orthogonal polarization directions.

14. In an electro-optical system for projecting in real time very high brightness, full color images from television or other program sources onto a display screen, said system being of the type which additively synthesizes said images by superposition of at least three different primary images and which uses only projection beam optical processes which are non-absorptive to first order in order to avoid overheating the system, the improvement comprising:

(a) light source means for providing a collimated beam of light projection light;

(b) a single polarizer-analyzer beam splitter recombiner multirefractive means positioned to receive said collimated projection light for polarizing and splitting it on a first pass therethrough and for analyzing it on a first pass therethrough for all three of said primary color images;

said light source means and said multirefractive layer means being positioned on a first optic axis the direction of which is defined by the beam direction of a first polarization state component of said collimated projection light beam which on said first pass is transmitted through said multirefractive layer means;

said light source means being positioned on said first optic axis on a first side of said multirefractive layer means to transmit a beam of unpolarized light along said first optic axis, said multirefractive layer means making an angle of 45°

with said first optic axis and transmitting a beam of white polarized light of "P" polarization state along said first optic axis and reflecting a beam of white polarized light of "S" polarization state complementary to said "P" state along said second optic axis;

(c) single projection lens means for projecting said full color image to said display screen;

said single projections lens means being positioned on a second optic axis for projecting said full color image along said second optic axis to said display screen, said second optic axis intersecting said first optic axis at said multirefractive layer means, the second optic axis extending in a direction defined by the beam direction of a second polarization state component of said collimated projection light beam which on said first pass is reflected by said multirefractive layer means and which polarization state is complementary to the polarization state of said transmitted beam;

(d) dichroic mirror means for first separating collimated unmodulated polarized white light leaving said multirefractive layer means into three beams of collimated polarized light of different primary colors to be polarization state modulated and reflected, said dichroic mirror means then passing the three reflected modulated primary color collimated beams back to said multirefractive layer means for analyzing and recombining said three primary color beams to pass a resulting collimated full color image modulated beam from said single multirefractive layer beam splitter recombiner means to said single projection lens means for forming said full color image;

said dichroic mirror means comprising first dichroic mirror means positioned on said second optic axis orthogonally thereto to receive "S" polarization light and second and third dichroic means positioned on said first optic axis to receive "P"polarization state light transmitted by said multirefractive layer means, said second dichroic mirror means making an angle of 45°

with said first optic axis and said third dichroic mirror means being orthogonal with said first optic axis, said first dichroic mirror means transmitting light of said first primary color and reflecting light of said second and third primary color, said second dichroic mirror means reflecting light of said second primary color and transmitting light of said first and third primary colors to said third dichroic mirror means, said third dichroic mirror means transmitting light of said third primary color and reflecting light of said first and second primary colors;

(e) first, second and third reflection polarization state modulation means for spatially modulating the primary color component video image in real time onto each of said first, second and third collimated beams of polarized light of first, second and third primary colors respectively received from said dichroic mirror means by modulation of the state of polarization of the light in said respective beam and for reflecting said three beams back to said multirefractive layer means to be polarization analyzed and recombined into said full color image for projection by said single projection lens means;

said first, second and third reflection modulation means each comprising a reflection type A.C. field effect mode liquid crystal light means, said system further including means for optically coupling each of said first, second and third liquid crystal light valve means to a cathode ray tube for deriving therefrom said video image which is modulated onto said beam of polarized light by said light valve; and

,

(f) said first, second and third liquid crystal light valve means being respectively positioned to receive said light of said first primary color transmitted along said second optic axis by said first dichroic mirror means, to receive light of said second primary color reflected from said second dichroic mirror means along said first optic axis, and to receive light of said third primary color transmitted by said third dichroic mirror means on said first optic axis;

the optical path length from said projection lens 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 superposes the three primary color component images formed separately at each of said three reflection and modulation means in said respective collimated light beams to form said full color image without the interposition of any other lens means in the optical path between said projection lens means and said reflection and modulation means.

15. A system as in claim 14 and further including a quarter waveplate positioned orthogonally to said first optic axis between said light source means and said multirefractive layer means.