Abstract: A cathode-ray display for displaying a trace has a memory to store portions of digitized input signal. An analogue signal is created from the memory and is added to a ramp signal corresponding to the ramp signal utilized to control the field scanning of the cathode-ray display. A further high frequency signal is added to the superimprosed analogue signal and ramp signal. The resultant combined signal is supplied to voltage discrimination means which control a switch which, in turn, controls the electron gun of the cathode-ray display.

Abstract: A cathode ray tube brightness control circuit includes a resistor bridge network in one arm of which is a controlled voltage level point and the other arm of which includes a brightness adjustment potentiometer. A negative feedback amplifier has its input connected to the voltage level point and its output to one end of the bridge across which a brightness control voltage supply is connected. The voltage of the supply may be adjusted to vary the range of brightness control.

Abstract: A polychromatic cathode ray tube includes a screen formed by a single layer of a crystalline semiconductor material which luminesces in visible light when excited by an electron beam. The color of luminescence is varied by modulating the heat energy imparted to the layer by the electron beam.

Abstract: A color CRT includes a screen to effect display by being illuminated by electron beams and at least one grid for controlling a character of the display on the screen. A horizontal deflection coil is provided on the color CRT for horizontal deflection of the electron beams. A vertical deflection coil is provided on the color CRT for vertical deflection of the electron beams. A horizontal deflection circuit supplies a horizontal deflection current to the horizontal deflection coil. A vertical deflection circuit supplies a vertical deflection current to the vertical deflection coil. A horizontal parabolic waveform voltage generator generates a horizontal parabolic waveform voltage with the level thereof increasing for positions from the center to the edges of the screen according to the horizontal deflection current in synchronism to the horizontal deflection.

Abstract: The graphic processor output dynamic range corrector system according to the present invention includes an input adapter for receiving a brightness signal from a graphic processor, an attenuator with an adjustable attenuation coefficient connected to the output of the input adapter, a reference voltage generator with an adjustable voltage level, a summing circuit for receiving output signals from the attenuator and reference voltage generator and for producing a corrected brightness signal, and decoding logic circuits connected to a computer connected to the graphic processor via an input interface, and connected to the attenuator and the reference voltage generator to control adjustment of the attenuation coefficient of the attenuator and the reference voltage level of the generator. The correction generator can be used in a brightness contrast analysis instrument equipped with a CRT to display stimuli at various spatial and time frequencies.

Abstract: The computer monitor of the invention is divided into the Composite Signal Mode and the Transistor-Transistor Logic Signal Mode types depending on the computer circuit design. The compatible monitor is comprised of a composite monitor circuit adapted to the Composite Signal Mode and a transistor-transistor logic monitor circuit adapted to the Transistor-Transistor Logic Signal Mode. It includes circuits for correcting the electrical characteristics to operate on both the composite and transistor-transistor logic computer time charts. Those circuits include a horizontal shaft circuit which is connected to the horizontal oscillation/drive circuit, a vertical shift circuit is connected to the vertical oscillation/output circuit and a flyback transformer circuit. The invention also includes a circuit selecting switch integrated with a plurality of switches for freely selecting one of the computer output signals by manual switching in accordance with the mode of the computer output signal.

Abstract: Method for driving a picture tube and circuit assembly for executing the method. Video screens of recent construction have a thickness of the glass increasing towards the corners for reasons of mechanical stability, for this reason and because of the differing absorption of the emitted light through the glass, uneven illumination of the video screen results. For even illumination of the video screen a variable correction voltage is superimposed on the voltage difference at the electrodes of the picture tube which determine the beam current synchronously to the deflection of the cathode beam, the level of the correction voltage being automatically adjustable to the thickness of the glass at the respective location of the cathode beam. The drive method can be used for all picture tubes constructed in accordance with the construction principle mentioned.

Abstract: A photocathode current sensing circuit (58) is provided to adjust the electron accelerating voltage to a cone (32) and a phosphor screen (34) on an image intensifier tube (26). The voltage is adjusted by an anode power supply (60) which is responsive to the photocathode current sensing circuit (58). As light strikes the photocathode (28), a current (56) is generated. The current (56) is directly proportional to the intensity of light striking the photocathode (28). As the light and the current (56) decrease, the sensing circuit (58) controls the power supply (60) to provide a higher voltage to the cone (32) and the screen (34). By increasing the voltage to the cone (32) and the screen (34) the electrons are provided with more acceleration and, therefore, are intensified for viewing on the screen (34). An increase in light operates oppositely and decreases the intensity on the screen (34).

Abstract: An RGB video output drive amplifier is provided with current limiting circuitry at the base of the driver circuit. In a preferred embodiment, the driver circuit comprises a drive transistor with associated biasing circuits. The base of the drive transistor is coupled to a current limiting circuit to shunt excess current from the base of the transistor and to block additional input current at or near the level representative of the driver transistor reaching its saturation mode. Excess current is dissipated through associated resistance in the base circuit and while diode means prevent high input signals from driving the drive transistor into saturation. Maintaining the drive transistor at or below its saturation level pevents flaring in the resulting video picture display. No appreciable storage charge is built up during the short periods which the drive transistor may enter saturation in response to rapid transients provided through a transient response circuit in parallel with the current limiting circuit.

Abstract: Improved gain control in a photomultiplier tube having a plurality of dynode stages is achieved through manual or automatic change of the bias voltage on at least one of the several dynodes between the anode and cathode of the tube. By such means, maximum tube gain change is obtained with a minimum of bias voltage swing.

Abstract: An electrical circuit compensates for spatial variations in the light transmittance of the target surface (45) of an electron beam-addressed liquid crystal light valve (10). Such variations in light transmittance, which stem in part from the position dependent angle of incidence of the writing beam electrons and position dependent alignment layer variations arising out of manufacturing process limitations, affect the ability to achieve a monotonic gray scale luminance over the display surface. The compensating circuit adjusts the amount of beam current of the writing electron beam by varying the gain and offset voltage of the video signal, which modulates the writing beam current. This is accomplished by applying the X and Y scan position signals to a correction signal generator (102), which produces gain correction and offset correction signals whose magnitudes vary in response to instantaneous scan position of the writing electron beam on the target surface of a particular light valve.

Abstract: When controlling the working point of video output stages in monitors, data display cathode ray tubes (CRTs) (10) and the like, in which the scanning raster is applied to the screen of the CRT entirely on the visible portion of the screen, and to permit control of the working point of the video output stage by strobing the beam current at a high brightness level, the vertical deflection of the beam during not-needed lines is so controlled that the beam is deflected beneath a still remaining frame or beyond the phosphor layer of the screen. The deflection is obtained by an additional auxiliary deflection pulse derived, for example, from a monostable multivibrator (45) receiving a pulse close to the beginning of the selected line, and superimposing its pulse to the deflection of the deflection current for the vertical coil 42.

Abstract: An XY display transition intensifier increases the intensity of an electron beam of a CRT device when the deflection voltages are changing, indicating a transition between dots on the CRT display. The absolute values of the rate of change of the deflection voltages are determined and summed. The resulting output voltage is applied to the intensity grid of the CRT device to increase the intensity of the electron beam.

Abstract: In a horizontal drive circuit for a video display, means are provided for sensing the horizontal output pulse used to energize the high voltage sweep transformer and, in turn, the electrodes and deflection coils in a cathode ray tube (CRT). Horizontal output pulse height which represents not only the voltage applied to the CRT, but also retrace pulse duration is detected and utilized to terminate the video output when the horizontal pulse voltage level exceeds a predetermined value. Because this approach uses the collector pulse output of the horizontal output transistor to detect high voltage conditions, video shutdown during unsafe CRT operation is available not only for excessive peak voltage conditions, but also for improper retrace time operation due, for example, to sweep transformer malfunction.

Abstract: An electron beam detecting electrode is provided laterally outside an effective picture area, to detect a beam current amount and vertical position of the electron beam. An amount of the electron beam current and a position of the electron are controlled by utilizing an output signal of the electron beam detecting electrode, and a uniform brightness and a uniform distance between horizontal scanning lines are obtainable.

Abstract: A circuit for controlling a CRT including a control which monitors tube parameters and adjusts the nominal cut-off level of the tube cathode current accordingly, sensing when the control is near an extreme of its range of adjustment and responsive to the sensing to change a control signal applied to a grid of the tube so as to bring the nominal cut off level control loop within its range of adjustment.

Abstract: A disclosed last-line overscan system and method allow for sampling of video display characteristics such as RGB cathode currents during each frame of displayed video for an underscanned video monitor without distortion of the visual display. Detection of the initiation of the vertical sync signal operates to overscan the last display line by driving the trace off the visual display area and away from the active raster. Sampling may then occur during an interval in which no visual display is possible thereby preventing distortion of visual information and preventing undesired brightness in the active raster. Subsequent to the interval for sampling of the RGB beam currents, vertical retrace is effectuated for display of the succeeding video frame.

Abstract: A digital-to-analog converter comprises a current source for supplying a current of predetermined magnitude to a circuit node, and a switch connected to the circuit node, and defining a first current path leading to a reference potential terminal and a second current path leading to an output terminal. The switch has an input terminal, at which it receives a first digital signal of one binary digit for conversion to analog form, and also has a reference terminal, and has a first condition, when the voltage at the reference terminal is higher than that at the input terminal, in which the current supplied to the circuit node is delivered to the output terminal, and a second condition, when the voltage at the reference terminal is lower than that at the input terminal, in which the current is delivered to the reference potential terminal.

Abstract: A flat matrix cathode-ray tube (CRT) in which the brightness of a display picture can be readily adjusted according to environmental brightness. In the flat matrix CRT, the grid electrodes are made up of the scanning electrodes and the data electrodes which form the matrix structure with the scanning electrodes, and the pulse voltage for gradations required are applied selectively to the scanning electrodes and the data electrodes so that the picture elements determined by the scanning electrodes and the data electrodes to which the pulse voltage are selectively applied are caused to emit light. Slots the number of which is determined in correspondence to the number of gradations selected, are provided either in the waveforms of the voltages applied to the scanning electrodes or in the waveforms of the voltages applied to the data electrodes in such a manner that the slots occur at regular intervals.

Abstract: A system for stabilizing the cathode emissions of an in-line gun cathode ray tube includes subsystems functionally identical to one another linked to each of the cathodes of an in-line gun cathode ray tube. During the time that the CRT beam is retracing vertically, each subsystem imposes a fixed, predetermined voltage on a cathode in the cathode ray tube, samples the current flowing to the cathode, compares the sampled current to a predetermined, desired reference current for the cathode, develops a differential signal representing the difference, if any, between the sampled current and the reference current, and then drives the current flowing to the cathode from its actual value to its predetermined, reference value so as to maintain a predetermined, desired ratio of the currents flowing to each of the cathodes.

Abstract: In an image pickup tube including a cathode, a first grid electrode disposed as a next stage of the cathode and provided with an aperture, a second grid electrode disposed as a next stage of the first grid electrode and provided with an aperture, and a photoconductive target, the first grid electrode is operated by a voltage positive with respect to the cathode. To control the amount of the electron beam of the image pickup tube, a voltage corresponding to a signal current obtained from the photoconductive target of the image pickup tube or to a return beam from the photoconductive target is applied to the second grid electrode in such a manner that a polarity of the applied voltage is opposite to a polarity of a signal charge generated on the photoconductive target.

Abstract: A circuit arrangement for the control of at least one beam current in a picture tube (9) contains a cut-off point control which on the occurrence of a given reference level in the picture signal adjusts the beam current in one sampling interval to a preset value. A trigger circuit (19) and a logic network (22) are provided to prevent picture interference during start-up of the picture tube (9) due to the beam currents which slowly rise as the hot cathodes (8; 801, 802, 803) heat up and due to the cut-off point control which responds only after the build-up of these beam currents.

Abstract: Control circuit for use with an image pickup tube permits highlights of an image to be scanned appropriately by a scanning electron beam by increasing the beam current fed to the cathode of the image pickup tube and prevents unwanted oscillations typically found when such beam currents are increased. The control circuit first determines whether the output from the image pickup tube exceeds a predetermined level and produces a control signal to be added to the normal beam current and also uses this control signal to control a vertical deflection circuit to shift the scanning electron beam upwardly toward a region on the photoelectric transducer of the image pickup tube that has already been scanned, thereby providing negative feedback and preventing unacceptable oscillations in the output signal.

Abstract: In field emission systems having beam current regulation by use of modulating field strengths from a control or Wehnelt electrode adjacent the emission electrode, the varying field strengths produce a focus instability of the emitted beam. By the precise spacing of the emission tip, Wehnelt electrode and first accelerating electrode, and by the precise aperture diameters of the Wehnelt and first accelerating electrodes, the beam focus remains stabilized for modulating field strength variations.

Abstract: A method of producing uniformity of emission a characteristics of a plurality of electron beam sources in a cathode ray tube, by deriving and storing data values for producing respective correction voltages to be applied to modify the emission characteristics. Each data value is obtained by sensing a current which flows through one of the control electrodes when a high voltage electrode is set to a relatively low potential, comparing this current with a reference value and storing the difference for use in subsequently producing a correction voltage. Data values are derived during successive time intervals, with corresponding correction voltages being successively applied to achieve feedback operation, for greater correction accuracy.

Abstract: A transistor with its collector connected to a point near the screen grid in the resistor network which feeds voltage from the high voltage rectifier of a picture tube to the screen grid electrode and its emitter connected to ground has two control circuits connected to its base electrode. The first control circuit (56) is a threshold circuit responsive to a voltage proportional to the beam current of the picture tube for making the control transistor provide a short circuit between the picture tube screen grid and ground, and thereby preventing a burnout when there is persistent excessive beam current. The second control circuit (58) acts on the base electrode of the control transistor to set the screen grid voltage of the picture tube at a desired value in normal operation, for example in accordance with the pulse width of a train of pulses of settable pulse width.

Abstract: A system for correcting display distortion caused by CRT beam current changes in an oscilloscope system is disclosed. A Z-axis signal proportional to the CRT beam current is multiplied by two factors adjustable for either or both of X and Y axes and then added to the respective axis deflection signal which controls CRT beam deflection, thereby providing improved display quality.

Abstract: By application of a predetermined period of relatively higher magnitude of electron beam emission from the cathode of the electron gun to the anode maintained at high voltage the potential gradient on the inside of the neck portion of a cathode ray tube is stabilized and the phenomenon of electron beam drift is thus suppressed effectively.

Abstract: A video display terminal is provided with controls which permit independent adjustment of the background information and the foreground information. Each control comprises an adjustable constant current source connected to one of two branches of a differential amplifier. One branch of the differential amplifier is employed to control the background intensity and the other branch of the differential amplifier is employed to control the foreground intensity.

Abstract: A scanning CRT control system is disclosed in which horizontal sync pulses are used to develop a pulse signal that provides an input to a transformer circuit also receiving a relatively low DC power supply input signal. The transformer circuit develops a very high DC voltage connected to a CRT screen while also providing a relatively lower voltage power supply signal that is utilized to develop the power supply signal provided to a video driver that controls beam excitation for the CRT. A compensation circuit is provided between the transformer circuit and a power supply terminal of the video driver such that a compensating signal is provided at the transformer circuit in accordance with each horizontal video scan line. The compensating signal has a frequency corresponding to the horizontal sweep frequency and a magnitude that varies in accordance with the average current loading of each individual horizontal scan line.

Abstract: A digital oscilloscope provides sine interpolation between sampled data points and includes means for intensifying the cathode-ray-tube display to emphasize portions of the cathode-ray-tube trace corresponding to original samples while deemphasizing portions of the trace representing interpolated information.

Abstract: A television camera capable of correcting shadings caused by digital registration faculty employed in a multi-tube type color television camera. The television camera comprises differentiating circuits for generating differentiated waves of correction waveforms used for adjusting registration, and non-linear circuits for processing the differentiated waves. Outputs of the non-linear circuits control the gain of a video signal circuit so that components responsible for the generation of shadings can be removed from a video signal.

Abstract: A temperature compensated G2 grid drive circuit for use with a video display having a high voltage section supplying a high voltage signal to a cathode, filament and G2 grid of a CRT, wherein the high voltage section has a negative temperature coefficient, includes an input terminal for receiving the high voltage signal and a temperature compensating circuit coupled between the input terminal and the G2 grid of the CRT. The temperature compensating circuit is characterized as having a slightly positive temperature coefficient for maintaining the brightness of the video display substantially constant by driving the G2 grid for compensating for variations with temperature in the high voltage signal supplied to the cathode, filament and G2 grid.

Abstract: In a video monitor for display alphanumeric data on a kinescope display screen, a kinescope driver transistor receives binary video data signals at a low impedance emitter input electrode and provides high level video data output signals to the kinescope from a collector output electrode. A source of adjustable control voltage is coupled to the base electrode of the driver transistor for varying the intensity of the data display.

Abstract: For an ultra high resolution color picture tube display, a level-shifting circuit is interposed between each of the three video output amplifiers and the three picture tube cathodes receiving video drive. In the level-shifting circuit, d.c. control voltages from adjustment potentiometers are applied to a voltage-controlled current source which provides voltage-compliant control input to a current-controlled voltage source which provides the adjustable d.c. offset voltage interjected between each video output amplifier and a corresponding picture tube cathode, providing individual background adjustment and brightness tracking adjustment compensation for cutoff spreads between the three picture tube guns and providing user brightness control action all independent of operating bias point voltages in the video amplifiers, so that they can be design-optimized for maximum bandwidth to achieve ultra high resolution.

Abstract: A brightness control circuit for a color display tube comprises voltage regulating means for varying a voltage between an input terminal and an output terminal thereof in dependence on an externally supplied voltage control signal are provided between cathodes of a color display tube corresponding to primary color signals and an output end of the color display tube drive circuit for supplying drive currents to the individual cathodes of the color display tube, and voltage control signal generating means connected to the voltage regulating means for supplying the voltage control or adjusting signals to the voltage regulating means. The voltage control signal generating means include two regulating means, i.e. first regulating means for changing simultaneously all the voltage control signals supplied to the voltage regulating means corresponding to the primary color signals and second regulating means for varying individually the voltage control signals for each of the color signals.

Abstract: A video monitor includes an image displaying kinescope which exhibits a temperature dependent conduction characteristic that results in declining light output and image brightness during an initial warm-up period, from a time soon after the system is initially energized to a time several minutes later when steady-state operation is reached. To counteract the declining kinescope light output during the warm-up interval, a compensation circuit having a time constant characteristic which approximates the kinescope conduction characteristic during the warm-up interval causes the kinescope to exhibit increasing light output and image brightness during the warm-up interval. Thus substantially uniform light output is produced over the warm-up interval.

Abstract: An intensity modulation circuit for a cathode-ray display device. Designating circuitry produces digital signals representative of at least two areas of the display of the cathode-ray tube. Analog signal producing circuitry produces from said digital signal analog video signals having at least two brightness grades, one of said grades being associated with each of said areas of display. Intensity modulation circuitry is coupled to the analog signal producing circuitry for varying the amplification of the analog video signal in at least one but not all of said grades. Output amplification circuitry receives the analog video signals and drives the cathode-ray tube in response thereto.

Abstract: Electro-optical tube alignment apparatus having a monitor for monitoring shading of the tube image, an adjustment device for adjusting tube target bias voltage so that shading is introduced into the image and is monitored by the monitor, and a control for varying tube alignment until a minimum average shading is monitored. Also beam current setting apparatus in which switch devices are provided to switch off the beam current during field scans so that the target charge during setting exceeds that produced by an operational peak light level. Methods associated with the apparatus are also provided.

Abstract: A multiplexed display interference compensation system for minimizing the apparent intensity modulation of an oscilloscope waveform display caused by closely spaced, individually imperceptible interruptions of the waveform required to maintain refreshed readout display is provided. The system includes a charge pump circuit for adding a current pulse to a waveform intensity control signal in response to a control signal from display multiplex control so as to increase the waveform intensity just after the interruption.

Abstract: In order to vary the brightness of the display produced by a cathode ray tube, a digital brightness control circuit is provided that utilizes a source of cathode control voltage connected to the cathode of the cathode ray tube, a brightness selector circuit which is connected to a digital counter, and a resistance network connected to the counter and the cathode control voltage source which is effective to vary in discrete increments the brightness of the cathode ray tube.

Abstract: A display apparatus including a modular type display tube having a cathodoluminescent screen, elongate thermionic or P-N electron emitters, a channel plate electron multiplier and an apertured control plate between the emitters and the multiplier. The control plate has a plurality of switching electrodes on the side facing the emitter and a set of brightness electrodes on the opposite side and extending transversely to the switching electrodes. In order to compensate for variations in emission from the emitters, the brightness voltage to the brightness electrodes is turned-off and emission variations are measured by scanning using the switching electrodes. Correction voltages are computed and applied together with the modulation signal in synchronism with the scanning of the switching electrodes. An apertured shielding plate is provided to prevent the switching voltages at the switching electrodes from affecting the emissions from the emitters.

Abstract: A color television receiver includes a color picture tube having three electron guns including cathodes and heaters therefor, respectively, and an automatic cutoff adjusting circuit for adding a reference voltage signal substantially at a black level to a luminance signal during an interval beginning substantially at the end of a vertical blanking period, and for detecting cathode currents flowing toward the cathodes during the above-described interval to control cathode voltages for the cathodes for keeping the cathode currents at a predetermined level by way of feedback of voltages proportional to the cathode currents. There is provided a circuit for applying a positive voltage to each of the heaters during the above-described interval to reduce a potential difference between the heater and corresponding one of the cathodes to thereby lower a leakage current flowing between the cathode and the heater.

Abstract: A digital video display system wherein the various characters to be displayed are displayed in the form of images of the complete character rather than the standard dot-matrix pattern of the prior art. A character generator in the display system stores signals representing the various characters to be displayed which are retrieved from storage in response to a character code. The signals are in the form of a binary code having a sufficient number of bits to represent a different number of levels of gray-scale or luminance values for the various picture elements making up the character image. The binary codes thus retrieved from storage are supplied to a video synthesizer that generates the video signal to display the character images which may be displayed in a number of different modes including white-on-black, black-on-white, black-on-gray, and white-on-gray as well as different combinations of such modes to represent a cursor.

Abstract: A waveform storage and display system particularly useful in digital oscilloscopes is provided in which successive waveforms of a repetitive signal are compared with a reference waveform, and upon detection of a difference or change within the waveform, the changed waveform is automatically stored. In addition to the conventional acquisition and display waveform memories, a reference-waveform and a changed-waveform memories are provided. Once a reference waveform is selected and stored, comparison of subsequent successive waveforms to detect changes is achieved under microprocessor control. Several display modes to provide a visual indication of changes may be implemented.

Abstract: A system for sequentially refreshing segments of the stored voltage characteristics of electron guns includes a clock gate. The clock gate passes clock pulses to a counter which refreshes the stored voltage signals. After a predetermined number of counts, the counter inhibits the clock gate until a vertical blank pulse enables the clock gate and the counter resumes counting.

Abstract: A waveform measurement system includes a feature in which a readout of an absolute ground-reference voltage at a particular selectable time point along a waveform is provided. A ground reference potential is sampled and stored, and the instantaneous voltage value of the waveform at the time point is arithmetically combined with the reference potential to provide the measurement. Intensified dots, as well as horizontal volts cursors, are generated and displayed on the waveform at the ground reference and selected instantaneous voltage value positions.

Abstract: The output delivered by a transducer having an integral power law transfer characteristic is stabilized by controlling output signal components related to the operating bias and gain of the transducer circuit. A test input signal comprising a sine-wave is applied to the transducer. The fundamental and integral harmonic components are filtered from the resulting output signal. The transducer is stabilized by restoring in sequence the amplitude of the harmonic and fundamental components to predetermined values respectively related to desired operating gain and bias conditions. A typical transducer is a cathode ray tube.

Abstract: A variable color cathodoluminescent manganese activated zinc silicate phosphor is disclosed. The zinc silicate host is modified by the addition of small amounts of aluminum and phosphorus. Variation in the current density of the cathode ray excitation produces emission varying from green to blue. The method of making the phosphor and a cathode ray tube device employing the phosphor is also disclosed.

Abstract: In an image pick-up tube including a diode-type electron gun having a cathode electrode which emits a scanning electron beam and a control electrode which regulates the current of the electron beam at the cathode electrode and through which there is a control electrode current flow during operation of the tube, and a target electrode from which a video output current signal is obtained in correspondence to incident light from an object image projected on the target electrode as the latter is scanned by the electron beam; a beam control voltage signal is generated in response to the video output current signal, the beam control voltage signal is supplied to the control electrode of the electron gun for regulating the current of the electron beam at the cathode electrode, the control electrode current is detected during operation of the tube, and the generation of the beam control voltage signal is controlled in response to a signal corresponding to the detected control electrode current and which preferably de