Abstract: A switchable color filter (10) develops with the use of a single electro-optic switching device positioned between first and second polarizing filter means (14 and 16) an output of three desaturated colors that define an area (54) in color space. The switching device comprises a variable optical retarding means (12) that includes a variable optical retarder (18) and a quarter-wave plate (20). The first and second filter means pass light rays of three primary colors. The variable optical retarding means selectively provides zero, quarter-wave, and half-wave retardation of light rays passing through it to develop the three output colors. The quarter-wave plate is positioned such that it forms a circular analyzer for one of the three primary colors when the variable optical retarder provides quarter-wave retardation. Each of the three output colors is a mixture of at least two of the primary colors.

Abstract: A high-speed power amplifier for driving inductive loads is capable of operating at frequencies of at least 270 kHz. The drive amplifier includes an oscillator that develops a continuous square-wave signal having relatively short transition times and a regulated 50% duty cycle. The oscillator output signal is applied to a filar-wound impedance transformer whose response time characteristics do not change substantially the transition time characteristics of the oscillator output signal. The impedance transformer circuit includes a pair of transistors operating in a push-pull configuration simultaneously to maintain the relatively short transition times of the oscillator output signal and to develop the high-current transformer output signal needed to drive a power transistor switch. The power amplifier is designed to provide a base current signal that promotes better dissipation of the power generated in the power transistor as it operates at high switching speeds.

Abstract: A display system (10) receives from a light source (12) a sequence of images, each representing a different depth plane of a subject, and selectively reflects each image from its corresonding one of plural light direction modulators (16 and 18) to synthesize a three-dimensional image of the subject. Each modulator is positioned along an axis (20) at a location that corresponds to a different depth plane. Each modulator reflects the first image incident to it and transmits the succeeding images in the sequence. In a display system having N+1 depth plane images, each of N modulators comprises a variable optical retarder (34) and a liquid crystal chiral cell (36). The N modulators reflect left-circularly polarize light and transmit right-circularly polarized light. An N+1 modulator preferably comprises a liquid crystal chiral cell and reflects light incident to it. An alternative embodiment (50) develops full color images.

Abstract: A field sequential color display system (10) employs a liquid crystal device operating as a variable optical retarder (12) which is positioned in front of the screen (40) of a raster scanned cathode ray tube (38) to develop a high quality multicolored image. The liquid crystal device is divided into upper and lower cell segments (34 and 36) to decrease the time between successive color fields. Each cell segment has a separate electrode structure (30 and 32) and a common electrode structure (22) and is separately commanded by a switching circuit (46) to a predetermined optical retardation state when the electron beam scans the portion of the screen covered by the cell segment. The switching circuit provides signals in a predetermined time sequence to the cell segments to minimize the optical cross talk between them and thereby minimize the spurious transmission of colored light from the display system.

Abstract: A microprocessor stepper motor drive uses a single acceleration/deceleration profile regardless of the final velocity of the device being driven. A first down counter stores the desired final velocity from a microprocessor. An acceleration/deceleration profile is stored in a storage device and added to the desired final velocity to produce a smooth velocity profile.

Abstract: A high-speed electro-optical light gate (40) includes a pair of matched variable optical retarders (54 and 56) positioned between a pair of light polarizing filters (42 and 44) to promote rapid switching between optical transmission states for light rays of the wavelength to which the variable optical retarders are tuned. The projections (62 and 66) of the optic axes of the variable optical retarders are orthogonally aligned so that the response time characteristics of the transitions between optical transmission states of the light gate reflect only the turn-on time response characteristic of the variable optical retarders. A field sequential color display system (78) incorporates a switchable color filter (80) which utilizes the alignment configuration of the variable optical retarders of the light gate to provide light output states of white light and light of three different colors to form an image in full color.

Abstract: A post-deflection accelerating and scan expansion lens system (10) is disclosed which may be used in a cathde ray tube (12). The lens system comprises an accelerating and scan expansion lens (70) of the quadrupole type including a pair of coaxial cylindrical electrodes (72, 74) and first and second compensating lenses (66, 78) on opposite ends thereof to provide a bright image of the desired size in sharp focus and great detail on a fluorescent screen in such tube. The first compensating lens (66) is supported adjacent the input of the accelerating and scan expansion lens to provide a linear magnification of the amount of electron beam deflection produced by the vertical and horizontal deflection plates (46, 48 and 50, 52).

Abstract: An enchanced luminance field sequential color image display system having an image source for providing a sequence of monochrome images. The monochromatic light images are formed of first, second and third different spectral colors. A liquid crystal switching system having crossed color selective polarizers is used to transmit the second and third colors with a first direction of polarization and to transmit the first and third colors with an orthogonal direction of polarization. A liquid crystal retarder is used to rotate the direction of polarization of light incident from the crossed polarizers by ninety degrees when the retarder is in its OFF state and to transmit the light substantially unchanged when the retarder is in its ON state. The light is then coupled to an analyzing system which in one embodiment is a neutral polarizer that transmits either the second and third colors or the first and third colors, depending on the state of the liquid crystal retarder.

Abstract: A method and an apparatus provide an optical switching system (10) which provides independent of viewing angle two system optical transmission states of substantially contaminant-free light. The system includes first and second light gates (12 and 12') of which each has associated therewith contaminant light intensity patterns (48 and 66) with points of local maxima (54, 56, 58, 60, 68, and 70) and local minima (62 and 72) in two system optical transmission states. The contaminant light intensity patterns are oriented so that the points of local maxima and minima of the contaminant light intensity patterns of one of the light gates generally align with the respective points of local minima and maxima of the contaminant light intensity patterns of the other light gate. The alignment of contaminant light intensity patterns blocks the transmission of contaminant light in two system optical transmission states, and thereby provides improved viewing angle performance.

Abstract: A field sequential color display system incorporates a color switch which includes a zero to half-wave optical retarder and pleochroic filters to provide an image with high color contrast and resolution over a broad range of display sizes. In a preferred embodiment, a liquid crystal cell which operates between two states of optical retardation comprises the variable retarder to provide a color switch with substantially reduced optical response times.

Abstract: A liquid crystal cell (100) includes a chiral additive in the liquid crystal material (106) to operate the cell as a rapid starting, high-speed variable optical retarder. The cell is fabricated so that the surface noncontacting directors (116 and 118) of the opposed surfaces of the director alignment layers (112 and 112') of the electrode structures (102 and 104) are tilt-biased in opposite directions. This surface contacting director configuration induces rapid surface noncontacting director (120a, 120b, 120c, 120d, 120e) relaxation without optical bounce when the cell is switched from the field aligned ("ON") state to the partly relaxed ("OFF") state. The chiral additive prevents an inactive cell from relaxing to the splayed topological state, thereby enabling switching operation without a warm-up delay and preventing the surface of the cell from having a mottled appearance when it remains unused.

Abstract: A method and an apparatus provide an optical switching system (100) which maintains essentially constant transmissivity at its maximum value and develops independent of viewing angle two system optical transmission states of substantially contaminant-free light. The system includes first and second light gates (102 and 104) of which each has associated therewith contaminant light intensity patterns (48 and 66) with points of local maxima (54, 56, 58, 60, 68, and 70) and local minima (62 and 72) in two system optical transmission states. Quarter-wave plates (134 and 136) are positioned between the light gates to develop circular polarization of light propagating between them. The presence of circularly polarized light maintains the system transmissivity at its maximum value while the relative orientation of the light gates is changed to align their contaminant light intensity patterns to block the transmission of contaminant light, and thereby improve the viewing angle performance.

Abstract: An electron beam deflection structure (10) of the traveling wave type includes first and second deflection members (52 and 58) positioned on opposite sides of and extending along the path of an electron beam (26) to deflect the beam in response to deflection signals applied to the deflection members. In a preferred embodiment, both deflection members are of a meander line type which include a plurality of deflection plate segments (74, 76) connected in series by a plurality of lead portions (78) to form a pair of transmission lines, each transmission line having a characteristic impedance that tends to vary with distance along the path of the electron beam due to a flared spacing between the output portions of the deflection members. Pitch compensation including different pitches for the first and second deflection members increases and maintains substantially uniform the characteristic impedance of each transmission line to prevent reflection of the deflection signal back toward the input end of the line.