Hughes Aircraft Company

Arno G Ledebuhr

Jan Grinberg

Murray S Welkowsky

William P Bleha

Philip G Reif

Nobuo J Koda

Phillip G Reif

Nubuo J Koda

Donald E Sprothbery

A compact optical system 10 for use with a single light valve full color system. The compact optical system 10 includes a prepolarizing beamsplitter 12 which extracts a beam of horizontally polarized light form an unpolarized/analyzer 14. The polarizer/analyzer 14 transmits the beam to a first dichroic separator 16 which transmits the red and green components and reflects the blue component toward a first fold mirror 18. The mirror 18 reflects the beam of blue light to a first fold prism 22 and to a first region 21 of a liquid crystal layer 19 of a light valve 23. A second dichroic separator 20 reflects the red beam component toward a second fold prism 24 and transmits the green component to a third fold prism 26. The prisms 24 and 26 direct the red and green beams toward second and third regions 25 and 27, respectively. The blue, red and green beams of horizontally polarized light incident on the first, second and third regions 21, 25 and 27 of the surface 19 are then polarization modulated by first, second and third CRTs 30a,b,c, focused on the photosensitive layer 29. The polarization modulated beams of vertically polarized light returned from the light valve are recombined into a single beam that is converted into a brightness modulated beam which is projected by projection optics 40 comprising a single optical lens providing a high brightness, full color image on a viewing screen.

Compact optical system for a single light valve full-color projector

A projection apparatus 30 with internal image registration is disclosed herein. The projection apparatus 30 of the present invention includes a light valve arrangement 58, 60, 62 for providing an image beam and an alignment beam, with the alignment beam having a predetermined spatial relationship with the image beam. The image beam is projected onto an external screen 20 by a projection lens 46. The present invention further includes a photodetector assembly 46, 48, 50 for generating a control signal in response to the position of the alignment beam. The image beam is aligned with the projection lens 46 by a light valve control circuit responsive to the control signal.

Full-color light valve projection apparatus having internal image

A color sequential illumination system (10) for a single light valve full-color projector is disclosed herein. The inventive color sequential system (10) is operative to illuminate a light valve (28) in response to an input beam. A prepolarizer arrangement (11, 13) polarizes optical energy of a first band of wavelengths within the input beam in a first state, and polarizes optical energy of a second band of wavelengths within the input beam in a second state. The system (10) includes a first liquid crystal switch (14), in optical alignment with the prepolarizer arrangement (11, 13), for selectively rotating the polarization states of optical energy within the first and second wavelength bands. A polarizer filter (18, 20), in optical alignment with the first liquid crystal switch (14), filters optical energy within the second wavelength band polarized in the predetermined state. A second liquid crystal switch (16), in optical alignment with the polarizer filter (18 20), selectively rotates the polarization states of optical energy within the first and second wavelength bands. The inventive system (10) also includes a broadband polarizer (24), in optical alignment with the second liquid crystal switch (16), for directing optical energy polarized in a predetermined state to the light valve (28).

Optical system for illuminating a light valve

An optical system is disclosed which includes a first color selective prepolarizer 16 for separating light from a source into first and second beams. The first beam consists of light of a first color having a first polarization state, and the second beam consists of light of second and third colors having a first polarization state, and light of the first, second and third colors having a second polarization state. A second color selective prepolarizer 22 is provided for separating the second beam into third and fourth beams. The third beam consists of light of the second and third colors having the second polarization state. The fourth beam consists of light of the first color having the second polarization state and light of the second and third colors having the first polarization state. A main polarizer/analyzer 30 is included for separating the fourth beam into fifth and sixth beams. The fifth beam consists of light of the first color having the second polarization state and the sixth beam consists of light of the second and third colors having the first polarization state. A dichroic separator 42 is provided for separating the sixth beam into seventh and eighth beams. The seventh beam consists of light of the second color having the first polarization state and the eighth beam consists of light of the third color having the first polarization state. The invention directs the fifth, seventh and eighth beams, consisting of green, red and blue light respectively in parallel relation toward a single light valve. Polarization modulated light is returned from the light valve for full color projection.

Compact optical system for a single light valve projector using two axes

A simple, less costly prepolarizing prism assembly for a four color liquid crystal light valve image projector is disclosed. The invention is a unitary assembly which provides a combined beam of light having a first component of a first color and first polarization state and a second component of a second color and a second polarization state. The invention includes a first color filter for reflecting, from an input beam of unpolarized white light, light of a third color and transmitting light of the first and second colors in a combined beam along a first optical path. A first prepolarizer is mounted on the first filter for extracting, from the combined beam, light of a second color and the first polarization state. A second prepolarizer is mounted on the first prepolarizer for extracting, from the combined beam, light of a first color and the second polarization state.

Unitary prepolarizing prism assembly for a four color liquid crystal

A liquid crystal light valve projector is disclosed which includes source illumination appratus which images an illumination aperture at the liquid crystal light valves, and further includes light valve imaging apparatus for relaying the light valve images to a wide angle projection lens having a short back focal length. The disclosed liquid crystal light valve projector utilizes air separated dichroic color separator for providing primary color illumination to the light valves.

Optical layout for a three light valve full-color projector employing a

An electron beam addressed liquid crystal light valve (LCLV) produces an AC voltage across a liquid crystal layer from a single polarity electron beam, and exhibits very high resolution. A thin layer of partially conductive material is deposited on a support membrane on the electron beam side of the liquid crystal. A conductive, electron beam permeable sheet is formed on the back of the partially conductive layer. Electrons from the beam are absorbed by the partially conductive layer, and then flow back out to the conductive sheet to produce an AC voltage prior to the next electron beam scan. The conductive sheet is connected in circuit with a transparent electrode which provides a voltage reference on the readout side of the liquid crystal. The device is designed with electrical parameters that produce a discharge rate from the partially conductive layer fast enough to complete an AC cycle between successive electron beam scans, but slow enough for the liquid crystal to respond and produce an image. A separate mirror can be provided to reflect the readout beam back through the liquid crystal, or the conductive sheet can itself serve as a mirror.

Electron beam addressed liquid crystal light valve with input sheet

A full-color projector system is disclosed, wherein a single light valve is employed to modulate red, green and blue illumination beams in accordance with the respective primary color components of the image. Separate but proximately located red, green and blue output projection beams are provided by a prism assembly. First, second and third periscopes are provided to separate the projection beams at the output of the prism assembly and direct the respective projection beams into first, second and third teleconcentric projection lens for convergence at a projection aperture.

Prism assembly with three periscopes and projection lenses for a single

A color sequential illumination system for a liquid crystal light valve is disclosed. The invention operates with no moving parts and provides for the sequential illumination of a light valve with at least two beams of different colors. The rate is fast enough that the colors fuse together and the viewer sees a composite color image. The system includes a prepolarizer and dichroics for providing a first beam along a first optical path having a first color and a first polarization state and a second beam along a second optical path having a second color and said first polarization state. An optical switch is provided for selectively transmitting the first and second beams by sequentially changing the polarization state of each. Associated optical components are provided for directing the first and second beams onto the liquid crystal light valve.

Color sequential illumination system for a liquid crystal light valve

An optical system for a full color liquid crystal light valve image projector is provided. The invention includes a first prepolarizer for separating from a first beam light of first and second colors and a first polarization state and a second prepolarizer for separating from the first beam light of a third color and a second polarization state. The resultant first beam contains light of a third color and first polarization state and light of first and second colors and second polarization state. A polarization selective beamsplitter is provided in the optical path of the first beam for transmitting, in a second beam, light in the first beam having the first polarization state and reflecting, in a third beam, light in the first beam having the second polarization state. A color selective beamsplitter is included for transmitting, in a fourth beam, light in the third beam having a first color and for reflecting, in a fifth beam, light in the third beam having a second color. In the illustrative embodiments, the invention includes first and second reflective surfaces for reflecting the second and fifth beams respectively into a parallel coplanar relation with the fourth beam. The invention permits the light valves and associated CRT assemblies to be located in a parallel coplanar relation. The present invention thereby provides a compact design for a liquid crystal light valve image projection systems.

Liquid crystal image projection with multicolor prepolarizing system

An electron beam addressed crystal light valve (LCLV) produces an AC voltage across a liquid crystal layer from a single polarity electron beam, and exhibits very high resolution. A mirror and a thin layer of partially conductive material are deposited on a support membrane on the electron beam side of the liquid crystal. The partially conductive layer is divided into a series of pixel elements by a conductive matrix which faces the electron beam. Electrons from the beam are absorbed by the partially conductive layer to establish a negative voltage across the liquid crystal, and then flow out to the conductive matrix to produce an AC voltage prior to the next electron beam scan. The conductive matrix is connected in circuit with a transparent electrode which provides a voltage reference on the readout side of the liquid crystal. The elements of the device are designed with electrical parameters that produce a discharge rate from the partially conductive layer fast enough to complete an AC cycle between successive electron beam scans, but slow enough for the liquid crystal to respond and produce an image.

Electron beam addressed liquid crystal light valve

A prism assembly for a single light valve, full-color projector is disclosed. The prism assembly is adapted to polarize and separate the white illumination light into the three primary colors. Three separate input images corresponding to the information for the red, green and blue components of the full image are applied to separate regions of the light valve photoresponsive layer. The prism assembly comprises three channels, one for each of the primary colors. Each channel polarizes the illumination light into P-polarized colored light which is reflected onto the region of the light valve corresponding to the respective input image. The illumination light in each channel is reflected by the respective region of the light valve as respective beams each including an image bearing component of one polarization state and a second beam component of the opposite polarization state. The respective image bearing components are separated from the second components by respective analyzers and are passed into a periscope and projection lens assembly to converge the three separate images at a projection aperture.

Prism assembly for a single light valve full-color projector

A liquid crystal light valve projector is disclosed which includes a first color separator responsive to unmodulated polarized light for reflecting light of a first primary color, for transmitting the remaining portion of the incident unmodulated polarized light, and for internally reflecting incident light; a transparent plate window for transmitting incident unmodulated polarized light to the first color separator and for internally reflecting the light of the first primary color reflected by the first color separator; a second color separator responsive to the light transmitted by the first color separator for reflecting light of a second primary color and for transmitting the remaining portion of the incident light which includes a third primary color, whereby the second color separator reflects the light of the second primary color to the first color separator which internally reflects such second primary color light; and light modulators respectively responsive to the light of the first, second, and third primary colors.

Growing community of inventors

Pleasanton, CA, United States of America

Arno G Ledebuhr