Hughes Aircraft Company

Hughes-jvc Technology Corporation

Other

United States of America As Represented by the Secretary of the Air Force

Alan R Henderson

Ralph J Gagnon

Christopher S Sexton

Richard M Filia

Josef K Holy

John P Sheppard

An LCLV projection system (10) includes color separation dichroic mirrors (50, 52) positioned between a group of reflective liquid crystal light valves (38, 40, 42) and a polarizer analyzer (26) which enables a single projection lens (34) to project all colors via a light beam of single linear polarization with a high degree of contrast, efficiency and color separation. The polarizer analyzer (26) directs a light beam with a single polarization state to a pair of dichroic filters (50, 52) which separate the beam into three different colors that are sent to three different reflective liquid crystal light valves (38, 40, 42). The light valves reflect the respective colored light beams with change in polarization state back to the dichroic mirrors (50, 52) which combine the three colors into a single combined multi-color beam that is fed through the polarizer analyzer (26) to a single system projection lens (34). The polarizer analyzer (26) and dichroic mirrors (50, 52) are enclosed in a fluid filled enclosure (28) containing an optical fluid which has an index of refraction substantially the same as that of the substrate of the dichroic mirrors (50, 52), for effectively increasing the back focal length of the projection lens (34).

Immersed dichroic system for single projection lens liquid crystal video

Color separation dichroic mirrors (40,42) positioned between a group of reflective liquid crystal light valves (26,28,30) and a polarization analyzer (14) enable a single projection lens (18) to project all colors via a light beam of single linear polarization with a high degree of contrast, efficiency and color separation. The polarization analyzer (14) directs a light beam with a single polarization state to a pair of dichroic color filters (40,42) which separate the beam into three different colors that are sent to three different reflective liquid crystal light valves (26,28,30). The light valves reflect the respective colored light beams with change of polarization state back to the dichroic mirrors (40,42) which combine the three colors into a single combined multi-color beam that is fed through the polarization analyzer (14) to a single system projection lens (18).

Single projection lens color projection system

A video projection system employs a reflective light valve (10) that is optically addressed by an image from a cathode ray tube (12) and provides an output image for projection by means of a high intensity reading light directed to the output face of the liquid crystal light valve. Improved reading illumination is provided by scanning the face of the liquid crystal light valve (10) with a narrow beam of light (80) that moves across the liquid crystal in synchronism with the scanning image from the writing CRT (12). The scanned narrow band (80) of illumination is provided by a circular sequence of three quasi cylindrical lens (56, 58, 60) or mirrors (56a, 58a, 60a) mounted on a rotating wheel (52) and which may be made of sequentially different colors to provide a color display. Rotation of the lens or mirror bearing wheel (52) is synchronized with the vertical sync of the CRT scan, as are the index positions of each of the three lens or mirror segments on the wheel.

Scanned illumination for light valve video projectors

Arc lamp output stability is improved by use of negative feedback which stabilizes arc position and intensity. Position and intensity of an image of the arc are sensed by optical sensors to control electromagnets which shift arc position so as to decrease wander and to control lamp current to decrease arc intensity variation.

Arc lamp stabilization

A system for automatically achieving convergence of the individual color images emitted by a color projector (11). The system employs a test pattern generator (71) which generates a number of test patterns which are identical for each CRT of the projector (11). The test patterns are scanned across a light sensor (83) which produces an output signal each time a portion of the test pattern crosses the sensor (83). The output signal causes a scanner processor (91) to latch the positions at which respective crossings are detected. The differences in position of the respective test patterns at each location examined by the sensor (83) represents misconvergence of the individual color images at the respective location. These differences are determined and interpolated by an image processor (61) and stored in a memory (63) to generate correction signals for correcting the misconvergence. The same apparatus is also used to automatically correct for misconvergence during projector operation by examining test pattern disparities in small blacked out areas around points stored in memory during the initial misconvergence adjustment. Spatial gray scale correction is also automatically achieved by generating a correction signal which cancels the amplitude offset variations between spatial illumination profiles of flat field test patterns at 100% and 1% amplitude levels. Video gain adjustment is automatically achieved by generating a correction signal which cancels the amplitude offset variations between spatial illumination profiles of flat field test patterns at 100% and 60% amplitude levels.

Automatic image correction method and apparatus for projectors utilizing

A multiple cavity waveguide laser is formed of a pair of face to face contiguous dielectric blocks 70, 72, in the facing surfaces of which are formed pairs of mating waveguide grooves 78, 80, 82, 84, having an electrode partition 92 sealed to and between the adjacent mating blocks to separate one pair of waveguide cavities from another, thereby forming four closely spaced waveguide cavities. In another embodiment, the partition 26 between the two dielectric blocks 10, 12 is thin conductive material, and dielectric partitions 36, 38 are provided between cavities of each pair in a single dielectric block. The internal surfaces 40, 42, 44, 46 of each cavity opposite the common electrode 26 are plated with an electrically conductive material, and suitable electrical connections 56, 58, 18 are made from the internal electrodes to the exterior of the blocks. The two blocks 10, 12 are fixed to one another by a brazing and sealing compound 18 on their surfaces, which brazing compound may form part of the electrical connection from the internal electrodes. Mirrors common to all four cavities are mounted to the ends 62, 64 of the blocks, and radio frequency energy is coupled to the internal electrodes for excitation of the lasing gas within the cavities.

Clustered waveguide laser

A multiple cavity waveguide laser is formed of a pair of face to face contiguous dielectric blocks 70, 72in the facing surfaces of which are formed pairs of mating waveguide grooves 78, 80, 82, 84having an electrode partition 92 sealed to and between the adjacent mating blocks to separate one pair of waveguide cavities from another, thereby forming four closely spaced waveguide cavities. In another embodiment, the partition 26 between the two dielectric blocks 10, 12 is thin conductive material, and dielectric partitions 36, 38 are provided between cavities of each pair in a single dielectric block. The internal surfaces 40, 42, 44, 47 of each cavity opposite the common electrode 26 are plated with an electrically conductive material, and suitable electrical connections 56, 58, 18 are made from the internal electrodes to the exterior of the blocks. The two blocks 10, 12 are fixed to one another by a brazing and sealing compound 18 on their surfaces, which brazing compound may form part of the electrical connection from the internal electrodes. Mirrors common to all four cavities are mounted to the ends 62, 64 of the blocks, and radio frequency energy is coupled to the internal electrodes for excitation of the lasing gas within the cavities.

An up-down counter is fed pulses generated manually and/or automatically from either or any of two or more command sources. Gating circuitry ahead of the up-down counter may be used to enable counts from only one source at a time. The output of the counter represents the magnitude of the parameter to be controlled. The purpose is to transfer control of a parameter to any of several command sources without changing the value of the parameter, thereby achieving 'stepless' switching. Only one counter is needed regardless of the number of command sources, no synchronizing circuitry is required, and switching is provided with no steps or delays. Multiple command sources may be active simultaneously when command source input gating is not used ahead of the up-down parameter magnitude counter.

Stepless pulse count switching

Damage to the phosphorescent screen of a cathode ray tube (CRT) by an electron beam is minimized by preventing the display of a stationary image on the screen. This is accomplished by superimposing or adding to each of the normal electron beam deflecting voltages an additional triangular offset waveform, with the combined effect of the offset waveforms being to constantly move the entire electron scan pattern over an infrequently recurring path at a slow enough rate to be imperceptible to the viewer.

CRT display anti-burn circuit

In accordance with one disclosed embodiment, a continuous steel belt passed around two pulleys which are disposed so that the belt is in contact with a magnetic strip bonded to the surface of a conveyor. A rotary measuring device, such as photoelectric encoder, is attached to the shaft of one of said pulleys and the output signals from the encoder provide an accurate measurement of the linear travel of the conveyor.

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Carlsbad, CA, United States of America

Alan R Henderson