Abstract: A power source apparatus for a display is provided, which comprises a voltage generating section capable of controlling outputting or output termination of one or more predetermined output voltages, and a switching section provided between an output terminal of the predetermined output voltage and a predetermined reference potential terminal. The switch section is turned from OFF to ON when the voltage generating section performs the output termination control.

Abstract: The vertical/horizontal amplitude control device for controlling a vertical amplitude and a horizontal amplitude of an image display device for displaying a video signal includes a brightness level detector for detecting a brightness level of the video signal, a vertical amplitude controller for controlling the vertical amplitude based on the brightness level, and a horizontal amplitude controller for controlling the horizontal amplitude based on the brightness level. The device controls the vertical and horizontal amplitudes into constant without a delay from a change of a video signal even when the brightness level of the video signal abruptly changes.

Abstract: Disclosed is a deflection yoke mounted around a glass bulb of a CRT so as to cover a predetermined area of the glass bulb. The predetermined area is where an outer shape of the glass bulb smoothly goes from circular to substantially rectangular along a tube axis of the CRT. The deflection yoke includes a horizontal deflection coil disposed in a shape to fit with the outer shape of the glass bulb, and a funnel-shaped ferrite core disposed to surround the horizontal deflection coil. The inner shape of the ferrite core is circular throughout a length of the ferrite core.

Abstract: An apparatus and method for removing horizontal moire of a cathode-ray tube (CRT) monitor system, wherein horizontal moire can be completely removed even when the moire that occurs in an upper portion of the monitor is different from the moire that occurs in a lower portion of the monitor. In one aspect of the invention, a method for removing horizontal moire in a cathode ray tube (CRT) monitor comprises generating moire correction data in synchronization with a vertical synchronous signal, the moire correction data comprising a sawtooth waveform, adjusting one of a direct current (DC) component, an alternating current (AC) component, and both the DC and AC component, of the moire correction data, outputting the adjusted moire correction data for every other horizontal scan line in synchronization with an odd-numbered or an even-numbered horizontal synchronous signal, and delaying a horizontal drive signal in response to the output adjusted moire correction data.

Abstract: A method and apparatus used to step and correct the position of raster lines in a sinusoidal or zig-zag deflection system. By combining the magnetic flux generated with a rotation “twister” coil and a vertical deflection coil, scan lines can be uniformly spaced and separated nearly to their ends. Accordingly, the magnetic flux generated with the twister coil is adjusted going in the left to right direction then reversed in polarity and readjusted while returning from right to left. It is this controlled twister flux that combines with the linear vertical deflection flux to straighten and then step each scan line to produce an aligned raster.

Abstract: A control circuit of a power supply delivering a supply current to an inductor connected in series with the horizontal deflection yoke of a cathode ray tube display, the inductor being the primary coil of a transformer operatively connected for delivering a rectified low-pass filtered biasing voltage to the anode of the display, the low-pass filtering having a first time constant corresponding to the duration of a plurality of pictures, the control circuit having feedback circuitry for generating a monitoring voltage substantially proportional to the biasing voltage and for controlling the supply current to keep the monitoring voltage equal to a reference voltage; and feedforward circuitry for measuring the cathode current and for adding to the monitoring voltage a compensation voltage corresponding to the cathode current, low-pass filtered with a second time constant corresponding to the duration of a small number of lines and high-pass filtered with the first time constant.

Abstract: The vertical/horizontal amplitude control device for controlling a vertical amplitude and a horizontal amplitude of an image display device for displaying a video signal includes a brightness level detector for detecting a brightness level of the video signal, a vertical amplitude controller for controlling the vertical amplitude based on the brightness level, and a horizontal amplitude controller for controlling the horizontal amplitude based on the brightness level. The device controls the vertical and horizontal amplitudes into constant without a delay from a change of a video signal even when the brightness level of the video signal abruptly changes.

Abstract: An apparatus and method for removing horizontal moire of a cathode-ray tube (CRT) monitor system, wherein horizontal moire can be completely removed even when the moire that occurs in an upper portion of the monitor is different from the moire that occurs in a lower portion of the monitor. In one aspect of the invention, a method for removing horizontal moire in a cathode ray tube (CRT) monitor comprises generating moire correction data in synchronization with a vertical synchronous signal, the moire correction data comprising a sawtooth waveform, adjusting one of a direct current (DC) component, an alternating current (AC) component, and both the DC and AC component, of the moire correction data, outputting the adjusted moire correction data for every other horizontal scan line in synchronization with an odd-numbered or an even-numbered horizontal synchronous signal, and delaying a horizontal drive signal in response to the output adjusted moire correction data.

Abstract: A deflection yoke device includes a deflection yoke for deflecting electron beams in horizontal and vertical directions, the electron beams being emitted from an electron gun of a color cathode ray tube; coma correcting coils positioned on an electron gun side of the deflection yoke so as to be opposed to each other in such a manner that the electron beams pass therebetween; and a pair of cores around which the coma correcting coils are wound, wherein a sliding mechanism is further provided for allowing each of the coma correcting coils to be slidable with respect to the corresponding core. Therefore, a misconvergence can be corrected by a simplified configuration without reducing a sensitivity of the coma correcting coils.

Abstract: A method and device are described for detecting whether a flash (F) has occurred in the high voltage part of a combined high voltage and horizontal deflection circuit (100) in an apparatus comprising a cathode ray tube (CRT), such as for instance a television set, a monitor, etc. The possible flash is detected by checking the fly-back pulse (70) of the horizontal deflection circuit (16) for deviations that reflect the occurrence of a flash. One possible distortion indicative for the occurrence of a flash is bouncing of the fly-back pulse. Another possible distortion indicative for the occurrence of a flash is collapse of the fly-back pulse. Another possible deviation indicative for the occurrence of a flash is a substantial decrease of the storage time (&tgr;S) of the line deflection transistor (30).

Abstract: A color display device includes a color cathode ray tube having a phosphor screen, a color selection electrode and an electron gun for projecting plural in-line electron beams toward the phosphor screen, a deflection device for deflecting the electron beams horizontally and vertically, an electron beam correction apparatus including a correction coil wound around the tube axis, a deflection circuit for driving the deflection device, and an electron beam correction circuit for supplying to the electron beam correction apparatus a generally rectangular-wave signal having a period equal to two times a period of the vertical deflection of the electron beams and in synchronism with the vertical deflection of the electron beams.

Abstract: The cathode ray tube apparatus comprises a main lens constructed by focus, intermediate, and final acceleration electrodes. The main lens includes a focusing area positioned in a side of the focus electrode, and a diverging area positioned in a side of the final acceleration electrode. A focusing force curve expressing the focusing force along the tube-axis direction in the focusing area has two convex parts respectively being at first and second levels, and a concave part provided between the convex parts and being at a third level sufficiently lower than the first and second levels. The third level is set to a lowermost level at which a focusing or diverging force is not substantially effected on the electron beam. An intermediate electrode having a non-circular shaped hole is positioned near an area of the lowermost level.

Abstract: A dual-gun, single neck CRT focuses two beams, with significantly differing energies, onto a secondary emission target while maintaining compatibility with a standard fourteen-rotation stem and achieving FTU in excess of 95%. A pair of Einzel guns (write and erase) are mounted in parallel and aligned in the vertical direction rather than the horizontal inside the CRT. The write and erase guns are configured to share a common second accelerator electrode, a common final accelerator electrode, mounting beads and a magnetic deflection yoke. The guns' focus voltages are independently adjusted so that both the write and erase beams have the same focal length.

Abstract: In order to accurately measure a low current bias in an automatic kine bias (AKB) circuit during several video lines that immediately follow vertical retrace, dynamic focus is interrupted by deactivating a dynamic focus voltage amplifier. The amplifier draws its power from a horizontal flyback transformer. In order to avoid a horizontal transient which may occur when the dynamic focus voltage amplifier is reactivated after being deactivated during a vertical blanking interval, the dynamic focus amplifier draws a current during vertical blanking which approximates the average current drawn during vertical scan.

Abstract: A grid kick circuit for applying beam cut-off bias to the grid of a kinescope to provide spot burn protection. The circuit includes a first switching circuit having an output coupled to a first electrode of a grid kick capacitor and a second switching circuit having an output coupled to a second electrode of the capacitor and the grid. When beam blanking is not desired, charging current is supplied to the capacitor through a first current path from a first voltage source while the second switching circuit regulates the voltage at a second electrode of the capacitor and the grid. Current for the second switching circuit is provided by a second current path which is coupled to the first voltage source and is independent of the first path.

Abstract: A field emission display includes an array of emitter sites, a grid for controlling electron emission from the emitter sites, and a display screen. The field emission display also includes a control circuit for controlling the grid for preventing emission to grid. The control circuit includes a high impedance grid bias path, and a low impedance grid bias path. In addition, the control circuit includes a sensing-switching circuit for sensing an anode voltage at the display screen, and switching from the high impedance to the low impedance grid bias path upon detection of a threshold anode voltage. An alternate embodiment control circuit is configured to provide a programmable delay during enabling of the grid to insure that the display screen reaches the threshold voltage prior to electron emission. An alternate embodiment field emission display includes a focus ring that is controlled to prevent emission to grid.

Abstract: A CRT driving circuit includes a cathode control circuit for controlling a cathode voltage of a CRT on the basis of a video signal created by a video circuit, a power supply circuit for creating a power supply voltage for each of the cathode control circuit and the video circuit, a switch circuit provided between the power supply circuit and the cathode control circuit, and a monitor control circuit for on/off controlling the switch circuit and the power supply circuit on the basis of a power-on/off externally inputted signal. In response to the power-on/off signal, when the monitor control circuit switches the switch circuit and the power supply circuit into an off-state, it turns off the power supply circuit later than the switch circuit. Even after a power-switch is turned off, the video signal is supplied to the cathode control circuit so that the cathode control circuit continues its on-state.

Abstract: An apparatus for automatically stabilizing the black level of a displayed picture when (1) an automatic black level stabilizing function is OFF, (2) black level error occurs between at an ON state and at an OFF state and (3) black level variation and picture disturbance occurs during activation and deactivation of the automatic black level stabilizer. Black level variations when the automatic black level stabilizer are OFF is controlled by processing a cathode current in a negative feedback loop and controlling a CRT grid voltage, storing a divided grid voltage during a converging period and processing the grid voltage in another negative feedback loop in order to adjust the grid voltage to an ON state value.

Abstract: A monitor protection system comprise a display power management signaling (DPMS) operating unit for performing a predetermined power control; a horizontal deflection detecting circuit for detecting a horizontal deflection signal from a horizontal deflection circuit; a vertical deflection detecting circuit for detecting a vertical deflection signal from a vertical deflection circuit; and a control circuit for determining whether the horizontal deflection signal and the vertical deflection signal are normal, and generating a predetermine control signal to run the DPMS operating unit in order to observe the conditions of horizontal/vertical synchronization signals continuously, and protect a CRT monitor independently from the horizontal/vertical synchronization input conditions.

Abstract: A method is provided for reducing a residual spot on a cathode ray tube when a power supply is turned off. The method is executed by applying a holding voltage being no less than the value of the voltage enabling to enhance the back raster luminance and a cut-off voltage, or a voltage of a lower value, to a second grid electrode while the anode voltage is lowered to a predetermined voltage value when the main power supply is turned off.

Abstract: A kinescope video driver includes a series connection of a main cascode transistor coupled to a cathode of a cathode ray tube and a video signal amplifying transistor. A second cascode transistor is coupled between the main cascode transistor and the video signal amplifying transistor. The second transistor is coupled to the video signal amplifying transistor through a short wire conductor and to the main cascode transistor through a long wire conductor.

Abstract: A high voltage generation circuit incorporates the horizontal circuit of a cathode ray tube (CRT) monitor. The horizontal circuit comprises a horizontal output transistor, a retrace capacitor coupled in parallel with the horizontal output transistor, a damping diode which clamps the minimum voltage at the drain of the transistor to approximately ground potential, and a flyback transformer. The primary winding of the flyback transformer is coupled between a terminal where a DC power supply B+ is applied and the drain of the horizontal output transistor. A second transformer is provided between the retrace capacitor and the ground for producing a voltage at the secondary winding thereof each time a free oscillation occurs between the damping interval Td of the damper diode and the conduction interval Ton of the horizontal output transistor.

Abstract: A spot killer circuit for a CRT is capable of thoroughly removing any spot persistence and prevents damage to the fluorescent body of the CRT due to inaccurate horizontal and vertical deflection. When the power cord is unplugged, or when the display device is turned off (for example, via remote control key input), the bias voltage of the first grid G1 and the electric potential of the cathode are controlled so as to completely suppress any residual beam current flowing in the CRT. In the case of an inaccuracy (such as total failure) in either the horizontal deflection or the vertical deflection signals, the bias voltage of the first grid and the electric potential of the cathode are controlled to suppress the CRT beam current just as in the case of power shut off. This prevents damage of the fluorescent body in the CRT due to the inaccurate deflection operation.

Abstract: An analog circuit controller having fewer signal paths and elements is disclosed herein. A microcomputer has a first D/A converter for generating control voltages variable into a plurality of levels in a time-divided manner and a second D/A converter for generating switching signals of various levels each indicative of the type of a control voltage. The analog circuit controller receives the outputs of the first and second D/A converters and responds to the output of the second D/A converter to select the necessary circuit to be controlled to which the control voltage is to be applied. As a result, a plurality of circuits to be controlled can be controlled through only two signal lines.

Abstract: A display system includes a kinescope. A horizontal scan detector is coupled to a source of a horizontal scan current signal and detects a loss of horizontal scanning. In addition, a vertical scan detector is coupled to a source of a vertical scan current signal including a feedback path and detects a loss of vertical scanning. A vertical feedback detector is also coupled to the vertical scan current signal source, and detects a failure of the feedback path in the vertical scan current signal source. A controllable kinescope driver circuit, coupled to the kinescope, the horizontal scan detector, the vertical scan detector and the vertical feedback detector, blanks the kinescope if the horizontal scan detector detects a loss of horizontal scanning, the vertical scan detector detects a loss of vertical scanning or the vertical feedback detector detects a failure of the feedback path.

Abstract: A method for improving brightness uniformity reduces a decrease of light towards the edges of a display screen (10) of a display tube (1). The extent of the decrease of light particularly depends on an increase of the thickness of the glass of the display screen (10) from the center of the display screen (10) to its edges, and on a transmission of the glass. This decrease of light is corrected by causing the deflection rate to decrease (C1, Cs) from the center of the display screen (10) towards its edges.

Abstract: A horizontal deflection circuit includes circuitry for protecting the horizontal output transistor from failure due to an over-current condition. The circuitry includes a current detector for detecting the current in the collector-emitter path of the horizontal output transistor, and a interrupter for interrupting the drive signal to the horizontal output transistor when the detected current exceed a predetermined level.

Abstract: A spot removing circuit for a display device is disclosed. The spot removing circuit comprises a rectifying and smoothing portion for rectifying and smoothing the voltage outputted from a flyback transformer, a capacitor for charging a voltage supplied from a power supply and discharging the charged voltage when the power supply switch is turned off, and a grid control portion for supplying a grid terminal with the voltage outputted from the rectifying and smoothing portion when a power supply switch is turned on and for supplying the grid terminal with the voltage discharged from the capacitor plus the output voltage from the rectifying and smoothing portion when the power supply switch is turned off so that a spot can be prevented from appearing on a display screen when the power supply switch of the display device is turned off.

Abstract: This specification concerns cathode ray tube display apparatus comprises a cathode ray tube display screen (10). A beam generator (60,30) is provided for generating at least one electron beam in the cathode ray tube display screen (10) to produce a video image. Also provided is a line timebase circuit (40) for generating a line deflection signal to sequentially address the or each electron beam to successive pixels on the screen (10) in a line of a raster, and a frame timebase circuit (50) for generating an alternating frame deflection signal for sequentially addressing the or each electron beam to successive lines of the raster. The apparatus further comprises a standby circuit (110) connected to the line and frame timebase circuits (40,50).

Abstract: In a horizontal deflection circuit output stage, a retrace pulse voltage is developed in a primary winding of a flyback transformer and transformer-coupled to a secondary winding and rectified for developing a high voltage. A portion of the transformer-coupled rectified voltage is combined in a voltage divider with a second rectified voltage. The second rectified voltage is produced in a peak rectifier from the retrace pulse voltage in the primary winding in a manner that bypasses the secondary winding. A screen grid voltage is developed at a terminal of the voltage divider. A change in beam current loading produces variations in opposite sense in the combined rectified voltages in a manner to regulate the screen grid voltage.

Abstract: Known display devices include a video signal processing circuit with a black level setting circuit. This black level setting circuit measures the black level of the video signal, for example, during the field retrace interval by making use of an extra output of the video output stage. However, the measured black level has a line-frequency interference component which is caused by a parasitic capacitance in the display tube. The line-frequency interference component is fully compensated for by coupling one side of a secondary winding of a transformer, required for the focusing voltage to be generated, to a first capacitor, the other terminal of which is connected to the measuring input of the black level setting circuit, and by coupling at least a second and a third capacitor across the secondary winding of the transformer.

Abstract: To avoid burn in a scanning cathode ray tube, the address of the scanning spot at each clock period is recorded in a memory. During each frame period, the logarithms of the number of occurrences of each address are fed to a peak detector. The peak value is used to determine a maximum allowable beam current for the next frame. In another embodiment, the number of occurrences of each address during a line period is monitored and if this number exceeds a given number the CRT is blanked.

Abstract: A scanning circuit which utilizes blanking pulses between flyback pulses in a display device includes a line blanking circuit which prevents the generation of spurious blanking pulses by ringing in the blanking pulses. The line blanking circuit includes a capacitor for storing a reference voltage. A comparator is responsive to the reference voltage and to the flyback pulses and provides the blanking pulses when the flyback pulses exceed the reference voltage. The comparator is prevented from resetting for a preselected time period after the falling edge of the blanking pulse and spurious blanking pulses can not be generated during the preselected time period.

Abstract: An active amplifier is responsive to a vertical parabola voltage developed across a trace or S-shaping capacitor for developing a DC voltage at an increased voltage level than can be obtained by rectifying the parabola voltage. The increased voltage level is developed in a capacitor, during part of the period of each scan. The capacitor is discharged through a parallel resistor. During normal scanning, the capacitor voltage, alternately, increases and decreases, but remains above a threshold level as detected by a comparator. Upon scan loss, the capacitor discharges below the threshold and the comparator triggers blanking of the kinescope driver. In this way, the phosphors of a cathode ray tube of a television, especially a projection television, are protected from burning due to a loss of electron beam deflection.

Abstract: A circuit for protecting a cathode ray tube screen from damage by an electron beam includes a semiconductor switch device having an input coupled to a signal related to a deflection signal for the electron beam. The switch device is coupled to a voltage supply and the circuit further includes a charge storage device coupled to the switch device and further coupled to a control grid of the cathode ray tube. The charge storage device is charged through the switch device by the voltage supply when the deflection signal is present at a control input of the switch device. The switch device decouples the supply voltage from the charge storage device when the deflection signal is not present and places a negative blanking voltage developed on the charge storage device across the control grid when the deflection signal is not present to cut-off beam current in the cathode ray tube.

Abstract: A digital blanker for scanned displays is provided which turns off the electron beam on a Cathode Ray Tube whenever the beam is in a pre-defined area on the screen. A high speed analog to digital converter is utilized to digitize the position of either a raster or randomly scanned CRT beam. Once the beam position is digitized, the resulting number is used as an address to an EPROM. The data in the EPROM is coded to cause the CRT beam to be blanked if the beam is positioned in the predefined area where blanking is required.

Abstract: A television receiver includes a kinescope spot burn protection circuit comprising a capacitor coupled between a source of blanking signal and a control grid of the kinescope for applying negative grid cut-off bias to the kinescope in response to the blanking signal. The amplifier is of the cascode type having a minimum output voltage for peak white levels of a video signal applied to the cathode. The protection circuit includes a potential divider for biasing the kinescope at a positive voltage level related to the minimum output voltage of the amplifier during normal operation of the receiver to maximize the brightness of displayed images.

Abstract: A source of kine supply voltage is coupled to a video amplifier that drives a cathode of a cathode ray tube of a projection television receiver via a self biasing diode. When, due to, for example, a fault condition, the kine supply voltage is lost, the self biasing diode decouples the cathode of the cathode ray tube from a supply return terminal of an ultor supply voltage to form a high impedance, low capacitance at the cathode of the cathode ray tube. A beam current develops a self biasing voltage at the cathode of the cathode ray tube that substantially reduces the beam current to provide protection against a damage to a screen of the cathode ray tube.

Abstract: A voltage at a control grid of a cathode ray tube is generated at a blanking level to provide beam current blanking when horizontal deflection loss occurs. The control grid voltage at the blanking level is developed in a capacitor prior to an instant in which the horizontal deflection loss occurs. When the capacitor voltage is applied to the control grid to provide the blanking level, the capacitor is discharged slowly. To maintain the capacitor charged, prior to such instant when horizontal deflection is lost, the capacitor voltage is not applied to the control grid as long as the horizontal deflection is normal, regardless of whether vertical deflection loss occurs. Either horizontal deflection loss or vertical deflection loss will disable a video driver stage that controls the cathode of the cathode ray tube for providing additional beam current blanking capability.

Abstract: Three vertical deflection windings of corresponding three deflection yokes that are mounted on three cathode ray tubes of a projection video are coupled in series through corresponding three connector pairs. Three horizontal deflection windings of the corresponding three deflection yokes are coupled in parallel through the corresponding three connector pairs. When any of the three connector pairs is left disengaged, a disabling signal that is indicative of a loss of a vertical deflection current in the series coupled vertical deflection windings is generated. The disabling signal is coupled to a corresponding video driver of each of the cathode ray tubes for providing beam current blanking to protect the screens of the tubes against a screen burn damage.

Abstract: The present invention provides an improvement in a color display system. The system includes a cathode-ray tube having an electron gun for generating and directing three electron beams along paths toward a screen of the tube. The gun includes electrodes comprising a beam forming region, electrodes for forming a prefocus lens and electrodes for forming a main focusing lens. The system also includes a magnetic field deflection yoke. The improvement comprises means for applying a dynamic signal to one of the electrodes forming the prefocus lens when electron beam current drops below a predetermined level. The dynamic signal is a maximum voltage when there is no deflection of the electron beams and decreases in voltage to a minimum at maximum horizontal deflection of the electron beams.

Abstract: A video display monitor operable at different horizontal deflection frequencies incorporates a circuit that produces an electron gun control grid potential that compensates for screen grid potential changes due to changes in operating frequency. A sawtooth signal is generated that has a peak to peak amplitude determined in response to the deflection frequency. The sawtooth signal is peak detected to produce a direct voltage, for the control grid, that varies in response to the horizontal deflection frequency.

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: A cathode ray tube (CRT) display arrangement including protection means for protecting the screen of the CRT (1) against excessive heating, by the electron beam, e.g. due to failure of the beam deflection drive circuits (5), the protection means comprising an electronic storage means (27 to 41) having storage locations in which are stored values indicative of the temperature at different locations on the CRT screen, and means (7) for controlling the electron beam current in dependence on the contents of the storage means.

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: 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: A circuit for preventing burn-in spots on the picture screen 23 of a visual display 2 comprising an electron beam 19 that is intensity modulated and positioned controlled by way of a deflection system 21, 22 as, for example, for a scanning electron microscope. The protection to prevent burn-in spots utilizes a circuit wherein the signal input 24 of at least one deflection system 21 is electrically connected to a differentiator which produces an output that is connected to the first input of a comparator which also receives a reference voltage and the comparator output is switched to the input of a retriggable trigger circuit so as to control the intensity of the electron beam 19 and thus prevent burn-in on the picture screen.

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 cathode ray tube protection circuit for a projection TV generates a signal which may be used to blank the tubes in response to a loss or reduction in beam deflection. Signals representative of vertical and horizontal deflection currents are provided. A reference signal is combined with the deflection representative signals to provide a signal having a predetermined amplitude. If the deflection current changes in any of the deflection yokes, the combined signal will change in amplitude. This change in amplitude is detected and used to generate a disabling or blanking signal for the kine driver circuits.