Low loss liquid crystal modulator for coloring and shaping a light beam

• US 5,040,877 A
• Filed: 12/04/1987
• Issued: 08/20/1991
• Est. Priority Date: 12/04/1987
• Status: Expired due to Fees

• Current Assignee: Institute Jozef Stefan, Kent State University
• Original Assignee: Kent State University
• Inventors: Marin, Bojan, Pirs, Janez, Blinc, Robert, Musevic, Igor, Zumer, Slobodan, Pirs, Silva, Kopac, Samo, Doane, J. William
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): GROSS, ANITA P
• Application Number:
  US07/128,986
• Time in Patent Office: 1,355 Days
• Field of Search: 350/334, 350/335, 350/337, 350/331 R, 353/34, 353/48, 353/49, 353/122, 353/31
• US Class Current: 349/10
• 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

The invention provides a low loss liquid crystal modulator for coloring and shaping a light beam wherein liquid crystal light modulators provide continuous variation in color and intensity output by controlled scattering; the liquid crystal light modulators comprise addressable sheets of light-wave-length size liquid crystal occlusious in a transparent matrix; the modulators employ nematic liquid crystal exhibiting positive dielectric anisotropy; the modulator is employed in varying and coloring output beams to allow for colored data or video transmission; images produced may vary in time as is required for, e.g., color television; the modulator is employed in color projectors for both data and video projection, for color printing, and for colored stage illumination. Low loss transmission of the modulators provides for bright images which can be viewed under high ambient illumination.

Claims

1. A low light loss color projector operative in a transmissive mode to project colored light comprising:

a) means for separating white light into three unpolarized light channels, each channel being a different color;

b) liquid crystal light modulating means in each of said light channels;

i) said liquid crystal light modulating means comprising a transmissive polymer dispersed liquid crystal; and

unpolarized light;

c) addressing means for addressing said liquid crystal light modulating means to selectively control scattering and transmission of said light channels.

2. A color projector according to claim 1 wherein said addressing means comprises a plurality of segmented electrodes.

3. A color projector according to claim 1 wherein said addressing means comprises an active matrix.

4. A color projector according to claim 1 wherein said means for separating white light into color are mirrors including dichroic mirrors arranged upstream from said liquid crystal light modulating means.

5. A color projector according to claim 4 including optical means associated with each channel downstream of said liquid crystal light modulating means for combining the emitted light into a colored projection beam.

6. A low light loss color projector operative in a transmissive mode to project colored light comprising:

a) means for separating white light into three unpolarized light channels, each channel being a different color;

b) transmissive polymer dispersed nematic liquid crystal light modulating means in each said light channels, said liquid crystal light modulating means being operative in one mode to transmit light and in another mode to scatter light; and

c) a laser for addressing said modulating means to selectively control scattering and transmission of said light channels.

7. A low light loss color projector operative in a transmissive mode to project colored light comprising:

a) means for separating white light into three unpolarized light channels, each channel being a different color;

b) transmissive liquid crystal light modulating means in each of said light channels, said liquid crystal light modulating means consisting essentially of a transmissive polymer dispersed liquid crystal and being operative in one mode to transmit light and in another mode to scatter light;

c) addressing means for addressing said modulating means to selectively control scattering and transmission of said light beams; and

d) a plurality of rotating mirrors downstream of said liquid crystal light modulating means.

8. A low light loss color projector operative in a transmissive mode to project colored light comprising:

a) means for separating white light into three unpolarized light channels, each channel being a different color;

b) transmissive polymer dispersed nematic liquid crystal light modulating means in each of said light channels, said liquid crystal light modulating means being operative in one mode to transmit light and in another mode to scatter light; and

c) addressing means for addressing said modulating means to selectively control scattering and transmission of said light beams;

d) said three light channels being oriented so that light emitted from the channels converges to form a colored image at a distance from said modulating means.

9. A color projector operative in a transmissive mode for modulating a beam of white light comprising:

a) means including at least two dichroic means aligned in the path of the beam of white light for separating the beam of white light into three unpolarized light channels, each channel being a different color;

b) liquid crystal light modulating means in each of the light channels, the liquid crystal light modulating means being operative in one mode to transmit unpolarized light and in another mode to scatter unpolarized light;

c) addressing means for addressing the liquid crystal light modulating means for selectively controlling scattering and transmission in the light channels to form three differently-colored virtual images; and

d) means for combining the virtual images into a projection beam including at least two dichroic means aligned in the path of the projection beam.

10. A color projector according to claim 9 wherein the liquid crystal light modulating means comprises a transmissive polymer dispersed liquid crystal.

11. A low loss color projector operative in a transmissive mode to project colored light comprising:

a) first optical means for separating white light into three unpolarized light beams, each beam being a different color;

b) first liquid crystal light beam modulating means containing a transmissive polymer dispersed liquid crystal positioned downstream of said first optical means, said light beam modulating means being operative to scatter unpolarized light in one mode and to transmit unpolarized light in another mode;

c) first addressing means for controlling the modulation of light by said light beam modulating means;

d) second optical means for recombining said beams into an output beam downstream of said light beam modulating means;

e) liquid crystal output beam modulating means containing a transmissive polymer dispersed liquid crystal positioned to receive and modulate said output beam, said output beam modulating means being operative to scatter light in one mode and to transmit light in another mode;

f) a second addressing means for selectively controlling the transmission and scattering of light by said output beam modulating means.

12. A projector according to claim 11 including a photosensitive medium positioned in the output beam downstream of said output beam modulating means.

13. A projector according to claim 11 acting in a frame sequential mode wherein said first liquid crystal light beam modulating means comprises shuttering means operative in one mode to scatter one of said light beams and in another mode to transmit one of said light beams.

14. A low light loss color projector operative in a transmissive mode to project colored light comprising:

a) first optical means for separating white light into three unpolarized light channels, each channel being a different color;

b) transmissive polymer dispersed nematic liquid crystal light modulating means in each of said light channels, said liquid crystal light modulating means being operative in one mode to transmit light and in another mode to scatter light;

c) addressing means for addressing said modulating means to selectively control scattering and transmission of light in said light channels to form three virtual images;

d) second optical means for recombining the virtual images into a colored projection beam; and

e) additional liquid crystal light modulating means arranged to modulate said colored projection beam, said additional liquid crystal light modulating means being operative in one mode to transmit light and in another mode to scatter light.

15. A low light loss color projector operative in a transmissive mode to project colored light comprising:

a) first optical means for separating white light into three unpolarized light channels, each channel being a different color;

b) transmissive polymer dispersed nematic liquid crytal light modulating means in each of said light channels, said liquid crystal light modulating means being operative in one mode to transmit light and in another mode to scatter light;

c) addressing means for addressing said modulating means to selectively control scattering and transmission of light in said light channels to form three virtual images;

d) second optical means for recombining the virtual images into a colored projection beam; and

e) a photosensitive medium positioned in the colored projection beam.

16. A frame sequential projector comprising:

a) a first optical system for separating white light into three light beams, each beam being a different color;

b) three liquid crystal light shutters, one in each of said light beams, said liquid crystal light shutters being operative in one mode to scatter one of said light beams and in another mode to transmit said one of said light beams;

c) first addressing means for addressing each of said light shutters to one of scatter and transmit said one of said light beams, thereby defining a colored output beam;

d) a liquid crystal light modulator for receiving and modulating said colored output beam, said modulator being operative to transmit and scatter light;

e) a second optical system downstream of said modulating means for directing said colored output beam onto the liquid crystal modulator; and

f) second addressing means for addressing said liquid crystal light modulator to define an image by transmitting light from said output beam incident on one of an addressed or unaddressed portion of said light modulator and scattering light incident on another of said addressed and unaddressed portions of said light modulator.

17. A projector according to claim 16 wherein one of said first and second optical systems comprises a plurality of mirrors.

18. A projector according to claim 16 wherein one of said liquid crystal light shutter or said liquid crystal light modulator comprises a transmission polymer dispersed liquid crystal.

19. A low loss method for projecting a colored output beam comprising:

a) separating white light into color and forming three unpolarized light beams so that each of said beams is a different color;

b) selectively transmitting each of said beams through liquid crystal light modulating means, said liquid crystal light modulating means comprising a transmissive polymer dispersed liquid crystal and being operative in one mode to transmit light therethrough and in another mode to scatter light;

c) addressing said liquid crystal light modulating means to selectively control scattering and transmitting of said light beams; and

d) directing at least one of said beams onto a rotating mirror downstream of said liquid crystal light modulating means.

20. A low loss method for projecting a colored output beam comprising:

a) separating white light into color and forming three unpolarized light beams so that each of said beams is a different color;

b) selectively transmitting each of said beams through liquid crystal light modulating means, said liquid crystal light modulating means comprising a transmissive polymer dispersed liquid crystal and being operative in one mode to transmit light therethrough and in another mode to scatter light;

c) addressing said liquid crystal light modulating means to selectively control scattering and transmitting of said light beams;

d) directing the light beams onto mirrors including dichroic mirrors downstream of said liquid crystal light modulating means so that the light transmitted through said liquid crystal light modulating means is combined into a colored projection beam;

e) directing the projection beam onto an additional liquid crystal light modulator, said additional liquid crystal light modulator comprising a transmissive polymer dispersed liquid crystal and

f) addressing said additional liquid crystal light modulator to selectively transmit and scatter the projection beam.

21. A low loss method for projecting a colored output beam comprising:

a) separating white light into color and forming three unpolarized light beams so that each of said beams is a different color;

b) selectively transmitting each of said beams through a polymer dispersed liquid crytal light modulating means, said liquid crystal light modulating means being operative in one mode to transmit light therethrough and in another mode to scatter light; and

c) addressing said liquid crystal light modulating means to selectively control scattering and transmitting of said light beams;

d) combining the light beams into a colored projection beam downstream of the liquid crystal light modulating means; and

e) positioning a photosensitive medium in the path of said projection beam.

22. A low loss method for projecting a colored output beam comprising:

a) separating white light into color and forming three upolarized light beams so that each of said beams is a different color;

b) selectively transmitting each of said beams through liquid crystal light modulating means, said liquid crystal light modulating means comprising a transmissive polymer dispersed liquid crystal and being operative in one mode to transmit light therethrough and in another mode to scatter light; and

c) directing a laser onto a surface of said liquid crystal light modulating means to selectively control scattering and transmitting of said light beams.

23. A low loss method for projecting a colored output beam comprising:

a) directing white light onto upstream mirrors including dichroic mirrors to form three unpolarized light beams of different color;

b) directing the light beams onto filters to enhance the color of each light beam;

c) selectively transmitting each of said beams through liquid crystal light modulating means, said liquid crystal light modulating means comprising a transmissive polymer dispersed liquid crystal and being operative in one mode to transmit light therethrough and in another mode to scatter light;

d) addressing said liquid crystal light modulating means to selectively control scattering and transmitting of said light beams; and

e) directing the light beams onto downstream mirrors including dichroic mirrors downstream of said filters so that the light transmitted through said liquid crystal light modulating means is combined into a colored projection beam.