Abstract: A CRT display apparatus including a CRT having an electron gun is disclosed. The electron gun includes a cathode, and a G1 electrode, a G2 electrode and a G3 electrode disposed in that order for drawing electrons from the cathode. The electron gun further includes a modulating electrode disposed between the G2 electrode and the G3 electrode. The CRT display apparatus is provided with a controller for controlling a value of a voltage applied to the modulating electrode in order to suppress or interrupt an electron beam flowing from the cathode to a screen of the CRT.

Abstract: For use in a beam index color cathode ray tube (CRT), a multi-beam group electron gun directs first and second groups of vertically aligned electron beams on respective parallel, horizontally aligned color phosphor stripes on the CRT's display screen. Each group of electron beams includes three beams, one for each of the three primary colors of red, green and blue. The first and second electron beam groups are horizontally offset from one another, with the upper, intermediate and lower electron beams in each group tracing the same horizontal phosphor stripe as the beams scan the display screen and with a time delay provided to synchronize the video information of both electron beam groups. A color video signal is provided either to a respective cathode or to a respective segmented conductive portion containing a beam passing aperture in the electron gun's G1 control grid for individually modulating each beam with color video image information.

Abstract: Discharge current limiting resistors are provided in respective high-voltage supply lines for distributing high voltages produced by a high-voltage distributor to the anodes of respective CRTs. As a result, a discharge current coming from a high-voltage capacitor that is part of a total discharge current flowing into a CRT where an abnormal discharge has occurred can be reduced to ½ of that in the conventional case and discharge currents coming from coating capacitances of the remaining CRTs that is another part of the total discharge current can be inhibited.

Abstract: A resistive voltage divider is responsive to a parabolic voltage developed in an S-shaping capacitor of a deflection circuit operating at a selected deflection frequency. The voltage divider includes a controllable resistive network for automatically selecting an attenuation factor of the voltage divider in accordance with the selected deflection frequency. An amplifier responsive to the attenuated parabolic voltage generates at an output terminal of the amplifier a periodic output voltage that is capacitively coupled to a focus electrode to produce a dynamic focus voltage. In a first embodiment, the controllable resistive network includes a photoresistor that provides automatic gain control. In an alternative, second embodiment, the voltage divider is switched.

Abstract: A vertical deflection circuit for a color picture tube apparatus, which reduces a white horizontal belt-like area that appears near vertical center of a color picture tube screen, caused by the operation of a convergence correction circuit using switching characteristics of a diode. The circuit comprises a vertical deflection yoke and a vertical linearity correction circuit connected to the vertical deflection yoke. The vertical deflection yoke has a vertical deflection coil, a convergence correction circuit using a diode as a switch, and a vertical coma aberration correction coil. An impedance of the vertical linearity correction circuit varies within a range where a vertical deflection current is in the vicinity of 0 A so as to reduce an impedance of the vertical deflection circuit.

Abstract: A display device which displays an image on a cathode-ray tube screen based on video information decoded from a signal-compressed digital broadcast signal. The video information contains fields having a number of scanning lines which may change from field to field, potentially causing vertical jitter in the displayed image. A circuit prevents the vertical jitter by setting a same vertical scanning start position of an electron beam on the screen for all of the fields regardless of the number of scanning lines. The circuit may be a clamp circuit which clamps a vertical ramp waveform; or a control circuit which controls a direct current level of the vertical ramp waveform when the number of scanning lines in a current field is different from a reference number of scanning lines; or an amplitude control circuit which performs feedback control of an amplitude of the vertical ramp waveform.

Abstract: A color cathode-ray tube has a fluorescent body film having picture elements of three colors. A shadow mask provided for the color cathode-ray tube is a color selection electrode and is installed close to the fluorescent face. An electron gun includes a cathode, a first electrode and a second electrode for discharging three electron beams in parallel and in a common plane. Further, the electron gun includes the main lens, which contains several electrodes that focus the three electron beams on the fluorescent face. The average diameter D of the vertical and the horizontal dimensions of the electron beam pass hole in the first electrode, the first electrode thickness T, and the space B between the electron beam pass hole in the first electrode and the electron beam pass hole in the second electrode are defined in an area that is surrounded by four straight lines that are expressed by the following relations, where A=D3/T: 100A=154B+17, 1000A=1420B+17, A=0.6, B=0.08.

Abstract: Display apparatus includes a kinescope cathode current sensor (18) coupled to a load (200) for developing a beam current measurement pulse during a beam current measurement interval. Overshoots in the pulses are suppressed by a pulse correction circuit (300) comprising a first capacitor (Ca) coupled from the load circuit (200) to a source of reference potential (Gr) via a switch (Q300); and a control circuit (Ca, Ra, Rb), responsive to the presence of the overshoot, for closing the switch for a predetermined length of time and for opening the switch otherwise.

Abstract: A video imaging apparatus includes a cathode-ray tube including a focus electrode. A source of a first parabolic signal at a frequency related to a deflection frequency, selected from a plurality of frequencies, has an amplitude determined in accordance with the selected frequency. A control circuit has an input coupled to the source of the first parabolic signal for generating an output signal. The output signal is for maintaining the amplitude of the first parabolic signal for the plurality of deflection frequencies. An amplifier, that is responsive to the output signal, is coupled to the focus electrode for amplifying the parabolic signal to generate a dynamic focus voltage at the focus electrode.

Abstract: An electron gun of a cathode ray tube includes an electron beam generating unit and a main lens unit. The electron beam generating unit includes a cathode, a first grid electrode and a second grid electrode, and the main lens unit is formed of plural electrode members and a final accelerating electrode disposed downstream thereof and supplied with a high voltage. A final main lens is formed between the final accelerating electrode and one of the electrode members adjacent thereto. An electrostatic quadrupole lens is formed in a first space between adjacent ones of the electrode members, one of which is supplied with a first focus voltage of a fixed value, another of which is supplied with a second focus voltage synchronized with electron beam deflection, wherein the first and second focus voltages are higher than a second grid electrode voltage.

Abstract: A video imaging apparatus includes a source of a blanking signal that is indicative when a blanking interval occurs in a video signal. A delay circuit including a horizontal line counter is responsive to the blanking signal and to a signal at the horizontal rate for delaying the blanking signal by a multiple number of horizontal periods to generate a delayed signal. A dynamic focus voltage generator includes a switch responsive to the delayed signal for applying a dynamic focus voltage to a focus electrode, when the switch is at a first state, and for disabling the application of the dynamic focus voltage, when the switch is at a second state. An end time of the interval, during which the dynamic focus voltage is disabled, is determined in accordance with an output signal of the counter.

Abstract: A video format adaptive electron beam control for causing the spot size of the electron beam to increase for a low resolution signal and for low resolution portions of a high resolution signal, and for causing the spot size of the electron beam to decrease for high resolution portions of the high resolution signal.

Abstract: A system and method for controlling an electron beam in accordance with the present invention includes an electron gun, a cathode ray tube with a faceplate, a deflection drive, a pair of positioning electrodes, an electron beam controller, and a pair of capacitors. The electron gun generates an electron beam in the cathode ray tube which is deflected in a desired direction towards and between at least one pair of positioning electrodes formed on the inner surface of the faceplate. Each of the positioning electrodes generates a position signal which is capacitively coupled by the capacitors to the electron beam controller. The electron beam controller adjusts the deflection of the electron beam in response to the position signals. The capacitors comprise a pair of first and second capacitor plates which are separated by the cathode ray tube. The first capacitor plates are disposed on opposing sides of an inner surface of the cathode ray tube adjacent to the faceplate.

Abstract: A high-voltage generator includes a high-voltage unit (1) and a further voltage generating unit (2) for generating DC high voltages (UF1, UF2), the voltage generating unit (2) including an adjustment unit (3) for adjusting a DC high-voltage (UF1, UF2) in an adjusting range between a lower and an upper limit voltage. In order to enable an as low as possible electric strength of the adjustment unit (3) and to reduce the impedance of the voltage generating unit (2), a DC voltage of between 100% and 200% of the upper limit voltage is applied to one connection point of the adjustment unit (3) whereas a DC voltage of between 50% and 100% of the lower limit voltage is applied to the other connection point of the adjustment unit (3).