Abstract: A pixellated light valve projector with optical image resizing, comprising: a) a lamp and optical integrator for generating a rectangular beam of light according to a predetermined aspect ratio; b) a pixellated panel for generating a rectangular image of a video signal in any one of a plurality of native pixel formats; c) a relay optical system intermediate the optical integrator and the pixellated panel for automatically concentrating the light onto the image in accordance with the one of the plurality of native pixel formats; d) a projection screen; and e) a projection lens for projecting the image onto the projection screen so that the projected image fills the projection screen in accordance with the one of the plurality of native pixel formats while image brightness level is maintained by concentrating the light onto the image on the pixellated panel.

Abstract: An automatic convergence system for correcting misregistration of component color images in a projection video display unit. The system comprises control circuitry for generating target characters onto a projection surface, and a locator assembly for aiming a photosensor array at the displayed target images by means of a pair of stepper motors. The photosensor array detects the position of the target images and conveys this information to a microprocessor which in response calculates appropriate correction signals for application to vertical and horizontal convergence coils of the display system for effecting convergence of the component color images.

Abstract: In a digital convergence circuit within a video display system, an interpolation circuit for multiplying first and second predetermined correction values corresponding to a pair of sample points by a plurality of respective first and second weighting coefficient values corresponding to successive additional sample points (i) intermediate the first and second sample points. Circuitry is provided for detecting the number (N) of successive additional sample points (i) and in response generating a first address signal representative thereof. Further circuitry is provided for generating successive count address signals corresponding to the successive additional sample points (i). A memory is included for receiving the first and successive count address signals and in response generating respective ones of the first weighting coefficient values .alpha. in accordance with the relation .alpha.=i/N.

Abstract: An ambient light rejecting quad photodiode sensor having compensation diodes connected with reverse polarity to respective quadrant photodiodes within the sensor, the compensation diodes being located outside of the area of illumination. By direct connection of compensation diodes in reverse polarity to each quadrant of the quad photodiodes, a large boost in signal to noise ratio is achieved for eliminating the effects of ambient room light as well as sensor dark current.

Abstract: A cascode mirror video amplifier for generating equal amplitude and opposite phase signals for driving a cathode and control grid of a cathode ray tube. The video amplifier comprises a pair of common base amplifiers connected via equal valued resistances to a pair of opposite polarity power sources. A common emitter amplifier is connected intermediate the pair of cascaded common base amplifiers and functions as a voltage control current source for receiving an input signal and in response generating a common current signal within each of the pair of common base amplifiers such that equal amplitude and opposite phase voltage signals are generated across the respective resistances. A pair of emitter follower stages apply the voltage across the resistance pair to the electron source cathode and control grid respectively while isolating the load capacitance of the cathode ray tube from each of the common base amplifiers.

Abstract: A liquid crystal light valve is provided which comprises a pair of glass cover plates. Transparent electrodes are located on the interfaces of each cover plate. The electrodes are electrically connected to alternating current sources. Insulating films are placed on either side of a liquid crystal material to provide electrical and chemical isolation between the liquid crystal and the electrodes. Spacers are employed to maintain a suitable gap between the insulating films and to prevent the liquid crystal from escaping. Positioned on the side of the liquid crystal from which writing light enters the light valve are, respectively, a dielectric mirror, a light blocking layer and a photoactive layer. According to the present invention, the photoactive layer comprises hydrogenated amorphous silicon which is configured as a photodiode with a junction layer facing the writing light.

Abstract: A system and method are provided for controlling a characteristic of an optical image generated by a video projection system of the type wherein illumination light is passed through a polarizing means and then directed to a light modulation device which receives a light image and provides an polarization modulated optical image as outgoing light, the outgoing light being passed through a projection lens to display the optical image. According to the present invention, a portion of the outgoing light is sampled and the sampled portion is directed to a detector which detects characteristics of the outgoing light. The detected characteristics are then compared with the corresponding desired characteristics exhibited by a test pattern image. The differences between the detected characteristics and the desired characteristics are measured and the measured differences are utilized to generate correction factors for controlling the outgoing light such that the outgoing light exhibits the desired characteristics.

Abstract: An optical system and method for image sampling in a video projection system is provided. A beam of illumination light is passed through a first beam-splitting polarizer to provide a first beam of a first polarization state and a second beam of a second polarization state. The first beam is passed through a second beam-splitting polarizer which is oriented at 90.degree. with respect to the first prism. The light from the second prism is then provided to a modulation device which produces a polarization modulated image in reflected outgoing light. The reflected outgoing light is passed through the second prism such that a first portion is directed to an image display screen and a second portion, which contains an image sample, is directed toward the first prism. The image sample is reflected by the first prism and provided to an image detector which detects characteristics of the sample. The detected characeristics are utilized to control the outgoing light.

Abstract: A color video projector of the type employing red, green and blue cathode ray tubes, dichroic mirrors and a final single lens through which the red, green and blue light from the CRTs is projected on a screen exhibits non-uniform color temperature across the width of the screen. Compensating waveforms for the red, green and blue video signals are generated and multiplied with the respective red, green and blue contrast signals, the products then being multiplied with the red, green and blue video signals respectively and applied to the cathodes (or grids) of the red, green and blue CRTs respectively to provide a more uniform color temperature across the width of the screen.

Abstract: A wide frequency range, switched-band, output signal from an oscillator is obtained by dividing the overall oscillator bandwidth into two bands having an overlapping band of frequencies. An input signal that triggers the oscillator also is supplied to a frequency-to-voltage converter. The magnitude of its output signal is compared to a reference signal in a comparator, and a control signal having a certain characteristic is derived when the input signal is in the high band of frequencies. When the input signal is in the low band, the control signal has a characteristic that is different from the first-mentioned characteristic. Switching takes place in the overlapping band of frequencies. The control signal is applied to a switching device that adds or removes impedance, e.g., capacitance from the capacitive part of the, for example, resistive-capacitive, frequency-determining network of the oscillator depending upon the characteristic of the control signal.

Abstract: The output voltage of a variable output voltage power supply is supplied to the deflection system of a raster scanned CRT and is controlled by a frequency responsive control signal generator so as to maintain peak to peak deflection current substantially constant despite scanning frequency variations. Picture width and/or height may be controlled in this way.

Abstract: A top-to-bottom focussing arrangement which maintains convergence is provided for a video projector employing separate red, green and blue cathode ray tubes (CRT's) and a dichroic mirror assembly. Each CRT has a mounting bracket, and the mounting bracket is pivotably mounted with respect to the dichroic mirror assembly to permit changes in the inclination of the longitudinal axis of the CRT to be effected. Simultaneous and equal changes in the inclinations of the longitudinal axes of the CRT's are effected by means of a rotatable member having rigid connecting arms pivotably connected thereto and pivotably connected to the mounting brackets.

Abstract: A vector generator includes a linear charge pump in the form of a DAC with a constant but variable current output that can charge a capacitor connected between the output and one of the input terminals of an operational amplifier. A second constant current generator having an output current one-half that of the maximum output current of the DAC and of opposite polarity also is provided for charging the capacitor, the constant current generators being so connected to the capacitor that it can be charged either positively or negatively. A switching network controls whether the capacitor is charging or not depending on the state of the switching network. A second DAC with a constant but variable output voltage is provided and produces an output indicative of the coordinate of the vector to be drawn. The voltage on the capacitor is compared to the output voltage of the second DAC, and, when they are equal, a control signal is produced that changes the state of the switch to terminate charging of the capacitor.

Abstract: A video amplifier is provided whose mode of operation varies depending on the level of the video signal from a condition where maximum positive voltage is applied to the cathode of the cathode ray tube (CRT) to ensure blanking, through operation as a differential amplifier, and finally to operation as a common emitter amplifier over the full brightness level range of the display on the CRT screen.

Abstract: The input voltage to the deflection system of a raster scanned CRT is made variable and is controlled by a feedback network in such a way that the width of the raster remains constant regardless of scanning frequency variations.

Abstract: The frequency of operation of a tuned flyback type transformer is controlled by a voltage controlled oscillator whose output frequency varies with EHT in such a way that EHT tends to stay constant despite beam current or input voltage variations.

Abstract: There is provided a self-aligning bearing assembly for a motor. The bearing assembly includes a housing member for securing to the motor, the housing member defining a bearing seat within a recess cavity larger than the bearing seat. A spherical bearing is seated in the seat, and a porous oil-retaining pad surrounds the bearing. A spring element with a central opening is in contact with the spherical bearing remote from the seat, and a closure member for the recess in the housing member is provided to enclose the pad, the spherical bearing, and the spring. The closure member and the housing member have a snap-fit together, the snap-fit being provided by outwardly projecting elongate ribs on one of the members, and elongate recesses on the other. The recesses are wider than the ribs, so that a certain degree of play between them is possible.

Abstract: Unmodulated baseband video signals such as those of a TV game are supplied to a television receiver through a system which provides high isolation between the signal source and the internal circuits of the receiver when disabled. When this system is enabled, the internal video detector of the receiver is disabled by being clamped off and the unmodulated video signals are injected into the receiver video circuitry beyond the detector.

Abstract: A method and system for remotely controlling the desired channel and volume selections of a television receiver and other like devices are disclosed herein. The system comprises a transmitter, receiver and information detector, the latter incorporating logic circuitry. The transmitter converts the selection information to ultrasonic signals, and the receiver converts the ultrasonic signals to pulses applicable to logic circuitry. The logic circuitry is adapted to the television receiver so as to apply the selection information to the television receiver and thereby achieve the desired selection.

Abstract: A brush holder and brush assembly for a dynamoelectric machine is constructed in such a way that the holder can be moulded in one piece of electrical insulating material. The holder has an opening which receives the rotating part of the machine to be contacted by current carrying brushes. The holder includes at least two oppositely disposed brush holding housings each having an end wall remote from the aforesaid opening and being open on two opposite sides thereof. Each housing also has two spaced apart side walls facing each other and extending from the end wall, the end of the housing opposite the end wall being open and opening into the aforementioned opening which receives the rotating part of the machine. Ribs extend inwardly from the side walls of the housings and run between the two ends of the housings. These ribs extend into recesses in the side walls of current carrying brushes that are mounted in the housings with the brushes engaging the side walls of the housings.