Abstract: An electron gun for a cathode ray tube has a cathode structure, a control electrode, a screen electrode, focusing electrodes, and a final accelerating electrode. R, G, and B electron apertures of one pair of the focusing electrodes face each other to form a quadrupole lens unit, to which an AC voltage having a relatively low peak or a static voltage is applied to converge R, G, and B electron beams into one point, even when the electron beams deviate to the corner of a screen. Asymmetrical enlargement portions are included in the rims of each of the R and B electron beam apertures.

Abstract: A main lens of an electron gun of a cathode ray tube is provided. The main lens for receives a plurality of parallel and co-planar electron beams emitted by the electron gun. The lens focuses each electron beam along a respective one of a plurality of focal axes incident to a display surface. A first grid electrode is positioned substantially orthogonally with respect to the plurality of electron beams, the grid electrode includes a plurality of apertures.

Abstract: An electron gun for a color cathode ray tube including a triode consisting of a cathode, a control electrode and a screen electrode, and first and second focus electrodes facing each other and installed sequentially from the triode, for forming quadrupole lenses for focusing and accelerating an electron beam emitted from the triode, wherein three first-elongated electron beam passing holes slanting in one direction at a predetermined angle with respect to the longitudinal axis are formed on the facing surface of the first focus electrode, and three second-elongated electron beam passing holes slanting in a direction opposite to that of the first-elongated electron beam passing holes at a predetermined angle with respect to the longitudinal axis are formed on the facing surface of the second focus electrode, and wherein a dynamic focus voltage synchronized with a deflection signal is applied to the first focus electrode and a focus voltage is applied to the second focus electrode.

Abstract: An in-line three beam electron gun for a color cathode ray tube comprising a cathode for emitting electron beams, a control electrode and a screen electrode, first through fourth focusing electrodes and an accelerating electrode, wherein the third focusing electrode has vertically elongated electron beam apertures to form a quadrupole lens, and the fourth focusing electrode has circular electron beam apertures. A first uni-potential lens is formed between the first and second focusing electrodes, a second uni-potential lens is formed between the second and third focusing electrodes, a quadrupole lens is formed between the third and fourth focusing electrodes and a main leans is formed between the fourth electrode and the accelerating electrode, when a static voltage is applied to the first and second focusing electrodes and a dynamic focusing voltage synchronous to a deflection signal is applied to the third and fourth focusing electrodes.

Abstract: A three in-line beam type color CRT includes a focus electrode and an anode. The focus electrode includes a first focus sub-electrode supplied with a first fixed focus voltage and a second focus sub-electrode supplied with a second fixed voltage superposed with a dynamic voltage synchronized with beam deflection, and the first and second focus sub-electrodes form a quadrupole lens therebetween. Two side electron beams are deflected toward a center electron beam with increasing dynamic voltage in the quadrupole lens. An axial distance Lgf (mm) from a cathode side end of the first focus sub-electrode to an anode side end of the second focus sub-electrode, an axial distance Ls (mm) from the end of the second focus sub-electrode to the phosphor screen, and a useful diagonal dimension D (mm) of the phosphor screen satisfy 0.06×Ls (mm)≦Lgf (mm)≦26 (mm) and 1.50≦D/Ls≦1.70.

Abstract: A dynamic focus coil produces different selected ampere-turns while consuming constant power and therefore maintaining constant temperature. The focus coil comprises a set of coils that all consume the same power. A selected subset of coils (e.g. two or three) are energized at any given time, the subset being selected to produce the desired focus adjustment. Illustratively, the coils all have the same resistance and are driven by current having the same magnitude and selectable polarity. An alternative embodiment contains a “coarse” set of coils having selected values of ampere turns and a “fine” set of coils having values of ampere turns that fill in between the values of the coarse set.

Abstract: A resistor for an electron gun assembly, for applying a resistor-divided voltage to an electrode provided in the electron gun assembly, comprises an insulative substrate, at least two first resistor elements disposed at predetermined positions on the insulative substrate, and a second resistor element having a predetermined pattern which electrically connects the first resistor elements. The resistor has a structure in which an effective length of the second resistor element between the first resistor elements varies in accordance with a position of the second resistor element relative to the first resistor elements.

Abstract: In the electron gun assembly of a cathode ray tube, a main electron lens portion is formed by a fifth grid to an eighth grid, and incorporates a quadrupole lens. The fifth grid receives a voltage obtained by superposing, on a voltage as a reference voltage, a dynamic voltage that parabolically changes with an increase when the electron beam is deflected amount of the electron beam. The sixth grid receives a voltage obtained by superposing, on a voltage as a reference voltage, a dynamic voltage that parabolically changes with an increase when the electron beam is deflected amount of the electron beam. The seventh grid receives the voltage, while the eighth grid receives an anode voltage.

Abstract: A color CRT is driven by focusing and accelerating an electron beam emitted from a cathode by forming electron lenses including a quadrupole lens by applying a predetermined voltage to the cathode of an electron gun installed in a neck portion of a funnel and each of electrodes, focusing the electron beam on a fluorescent film by applying a voltage having a horizontal dynamic waveform having a ratio of slopes of 6.85 or more between a unilateral area of 90% and a unilateral area of 50% of a raster area to which a video signal of an image is applied, to at least one of the electrodes forming the quadrupole lens, synchronized with a horizontal deflection signal of a deflection yoke installed at a cone portion of the funnel, in order to deflect an electron beam emitted from the electron gun and scan the deflected electron beam onto the fluorescent film of a panel sealed to the funnel, and forming an image by having the deflected electron beam land on the fluorescent film and excite the fluorescent film.

Abstract: A display apparatus including a CRT provided with an electron gun having a focusing electrode which is applied with a dynamic focusing voltage for focusing electrons drawn from a cathode of the CRT is disclosed. The display apparatus includes a dynamic focusing circuit for producing the dynamic focusing voltage by superimposing, on a dc voltage supplied from outside, an ac voltage which has a waveform varying in synchronization with horizontal and vertical deflections of an electron beam flowing to a fluorescent screen on the anode. The display apparatus further includes a compensator for lowering the dc voltage supplied to the dynamic focusing circuit by a predetermined value while a brightness signal indicative of brightness of a screen of the CRT exceeds a threshold value.

Abstract: An electron gun assembly forms an electron beam generator, pre-focusing lens, sub-lens, and main lens. The sub-lens has a weaker horizontal focusing power than the vertical one, and the main lens has a stronger horizontal focusing power than the vertical one. When the electron beam is not deflected, a first quadrupole lens is formed between the pre-focusing lens and sub-lens, and a second quadrupole lens is formed between the sub-lens and-main lens. At least one grid forming each of the first and second quadrupole lenses receives a dynamic focusing voltage which parabolically changes in synchronism with the deflection magnetic field and becomes higher when the electron beam is deflected than when it is not deflected.

Abstract: A focus electrode is constituted by a first type of focus electrode group to which a first focus voltage is applied, and a second type of focus electrode group to which a second focus voltage is applied. Between the first type of focus electrode group and the second type of focus electrode group are formed a lens at least having a lens action for correcting the field curvature and an electrostatic quadrupole lens. The center axes of the outer electron beam passage holes in the first type of focus electrode forming the lens at least having a lens action for correcting the field curvature are deviated on a horizontal plane from the center axes of the outer electron beam passage holes in the second type of focus electrode. The electrostatic quadrupole lens produces dissimilar intensities for the outer electron beams and for the center electron beam.

Abstract: A color cathode-ray tube including a main lens section comprising an anode to which an anode voltage is applied, and a focus electrode. The focus electrode has first type of focus electrode group to which a first focus voltage is applied, and a second type of focus electrode group to which a second focus voltage is applied which is obtained by superposing on a predetermined voltage a voltage that changes depending upon the deflecting amount of the electron beams. Between the first type of focus electrode group and the second type of focus electrode group are formed in a dynamic lens and an electrostatic quadrupole lens. Three electron beam passage holes are formed in the electrodes that form the dynamic lens and the centers for the outer electron beam passage holes in the first type of focus electrode group are deviated relative to the centers of the outer electron beam passage holes in the second type of focus electrode group in the horizontal direction.

Abstract: A focusing circuit (1) for generating a focus control signal for a cathode ray tube (3) has a modulation input (4) for influencing the focus control signal, which focus control signal contains a measure for an envelope of excursions of horizontal scan lines across the cathode ray tube. The focusing circuit (1) comprises a load control circuit (5) for influencing the focus control signal, and having a control input (6) coupled to the modulation input (4) for influencing the focus control signal by load control variation in dependence on a desired focus control signal modulation. The load control circuit (5) may comprise a current source and/or a voltage source and/or controllable impedance that have a control input for coupling to a modulation output of a synchronization processor (7).

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: 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: An electron gun for a cathode ray tube includes a triode portion composed of three cathodes arranged in a horizontal line, and control and screen electrodes sequentially placed next to the cathode. First to fourth focusing electrodes are sequentially arranged one after another next to the screen electrode. The first focusing electrode has a first side facing the screen electrode and a second side facing a second focusing electrode. Three circular-shaped beam passage holes are formed in both sides of the first focusing electrode. The second focusing electrode has a first side facing the first focusing electrode and a second side facing the third focusing electrode. Three vertically elongated beam passage holes are formed in the first side facing the first focusing electrode and three circular-shaped beam passage holes are formed in the second side facing the third focusing electrode.

Abstract: A color cathode ray tube including a panel section having a phosphor layer formed on an internal surface thereof, a neck portion having an electron gun assembly for emission of three electron beams therein, and a funnel section connecting the panel section and the neck portion. The electron gun assembly includes three cathodes and a plurality of grid electrodes disposed along a tube axis. The grid electrodes includes at least one plate-shaped electrode which has a fixed support structure. The plate-shaped electrode has three bulged portions along an electron beam passage, a first electron beam passage hole being formed in a respective bulged portion and a second electron beam passage being hole formed in a top face portion of a respective bulge portion. A diameter of the first electron beam passage hole is greater than a diameter of the second electron beam passage hole.

Abstract: An electron gun of a color cathode ra tube includes (1) a beam forming region having cathodes, a G1 electrode and a G2 electrode and (2) a main lens formed of plural electrodes including a G3 electrode supplied with a fixed focus voltage and an accelerating electrode. The main lens includes a final lens formed between the accelerating electrode and an electrode opposing the accelerating electrode and configured so that outer electron beats are deflected toward a trajectory of a center electron beam and a lens strength of the final lens weakens with beam deflection The electron gun also has at least one multipole lens located between the final lens and the beam forming region and configured so as to change a cross sectional shape of the electron beams with beam deflection, and a lens formed between a pair of electrodes located between the final lens and the beam forming region and having axially spaced opposing surfaces each having opposing center beam apertures and opposing outer beam apertures.

Abstract: A three in-line beam type color CRT includes a focus electrode and an anode. The focus electrode includes a first focus sub-electrode supplied with a first fixed focus voltage and a second focus sub-electrode supplied with a second fixed voltage superposed with a dynamic voltage synchronized with beam deflection, and the first and second focus sub-electrodes form a quadrupole lens therebetween. Two side electron beams are deflected toward a center electron beam with increasing dynamic voltage in the quadrupole lens. An axial distance Lgf (mm) from a cathode side end of the first focus sub-electrode to an anode side end of the second focus sub-electrode, an axial distance Ls (mm) from the end of the second focus sub-electrode to the phosphor screen, and a useful diagonal dimension D (mm) of the phosphor screen satisfy 0.06×Ls (mm) ≦Lgf (mm)≦26 (mm) and 1.50≦D/Ls≦1.70.

Abstract: An electron gun for a color cathode ray tube includes a triode unit, a main lens unit, and first and second auxiliary electrodes. The triode unit includes plural cathodes arrayed in a first direction and first and second electrodes each having corresponding plural electron beam passing holes corresponding to the respective cathodes. The main lens unit finally focuses and accelerates an electron beam and includes a third electrode forming a pre-focus lens with the second electrode. The first auxiliary electrode is coupled to one side surface of the second electrode facing the first electrode. The second auxiliary electrode is coupled to the other side surface of the second electrode facing the third electrode. With this arrangement, a beam spot of uniform size can be formed on the entire surface of a screen.

Abstract: In a self-convergent type color cathode ray tube apparatus, three in-line electron beams emitted from an electron gun assembly are deflected by non-uniform magnetic fields generated by a deflection yoke and thus self-converged onto a screen. The electron gun assembly has a second grid and a third grid. First and second auxiliary grids are disposed between the second and third grids. A dynamic voltage varying in synchronism with deflection of the electron beams is applied to the first auxiliary grid situated on the second grid side. A fixed voltage is applied to the second auxiliary grid situated on the third grid side. Accordingly, the second grid, the first and second auxiliary grids and the third grid form an electron lens such that a higher astigmatism is provided by focusing in a direction perpendicular to a direction of arrangement of the three electron beams than by focusing in the direction of arrangement of the three electron beams and the degree of the astigmatism is dynamically varied.

Abstract: A color cathode ray tube has G1-G5 electrodes and an anode. The G5 electrode is divided into sub-electrodes supplied alternately with a first fixed focus voltage and a second focus voltage which is a second fixed voltage superposed with a dynamic voltage, at least one electrostatic quadrupole lens is formed between adjacent ones of the sub-electrodes, and two of the sub-electrodes are supplied with the second focus voltage. The following inequalities are satisfied: 0.0625×L (mm)≦B−20A/(3&phgr;)≦22.0 mm, L (mm)≦352 mm, where A is an axial length of the G4 electrode, &phgr; (mm) is an average diameter of a center aperture in the G4 electrode, B (mm) is a length from a cathode side end to a phosphor screen side end of said G5 electrode to the phosphor screen.

Abstract: A color cathode-ray tube apparatus comprises an electron gun structure for generating three electron beams arranged in line, the three electron beams comprising a center beam and a pair of side beams. The electron gun structure forms a main lens for ultimately focusing the three electron beams on a phosphor screen. The main lens is formed by a focus electrode, an additional electrode and an anode electrode which are arranged in a direction of traveling of electron beams.

Abstract: A color cathode ray tube having an electron gun including a beam forming region for generating a plurality of electron beams from cathodes and directing the plurality of electron beams toward a phosphor screen along initial paths in a horizontal plane, and a main lens for focusing the plurality of electron beams on the phosphor screen. The main lens including a final lens configured so that the plurality of electron beams are focused in both horizontal direction and a vertical direction with outer electron beams among the plurality of electron beams being deflected toward a trajectory of a center electron beam among the plurality of electron beams, and a lens strength thereof being weakened with an increase in an amount of deflection of the plurality of electron beams.

Abstract: A dynamic focusing circuit of a monitor system capable of easily compensating a defocusing of a screen which often occurs in the monitor system which adopts a CRT. When vertical and horizontal parabolic signals is output from oscillation signal generating section, first and second amplifying sections amplify the vertical and horizontal parabolic signals, respectively, and output vertical and horizontal parabolic amplification signals, respectively. Signal mixing section mixes the vertical and horizontal parabolic amplification signals respectively output from the first and second amplifying section to apply a dynamic focusing signal to a focusing electrode. Accordingly, delay and distortion of the signal caused by the stray-capacitance of the transformer does not occur. Also, the waveform of the dynamic focusing signal is stably maintained even though the user changes a vertical or a horizontal size of the screen of the monitor system.

Abstract: A color picture tube of the present invention comprises three in-line cathodes (1a, 1b, 1c) aligned in the horizontal direction, a first focussing electrode (4) supplied with a focus voltage, a second focussing electrode (5) supplied with a dynamic voltage that changes in accordance with a deflection angle of the electron beams, a final accelerating electrode (7) supplied with an anode voltage, an intermediate auxiliary electrode (6) arranged between the second focussing electrode (5) and the final accelerating electrode (7). The intermediate auxiliary electrode (6) is supplied with a voltage between the voltage of the second focussing electrode (5) and the anode voltage. A non-axisymmetric electrostatic lens for focussing electron beams in the horizontal direction and diverging them in the vertical direction is formed between the first and second focussing electrodes (5, 6). The power of the non-axisymmetric electrostatic lens changes in accordance with a deflection angle of the electron beam.

Abstract: A compensation device for convergence drift used in a CRT, including a convergence electrode attached on an outer surface of a neck portion, an inducement means for inducing static electricity from a voltage to be supplied for an inner graphite layer, and a connecting member formed between the convergence electrode and the inducement means to supply high potential from the inducement means to the convergence electrode. As the convergence electrode provides high potential generated from the inducement means to the neck portion, the compensation device decreases the potential difference between grid electrodes and the neck portion. Thus, the compensation device makes the electric fields, which cause the charges to be accumulated, to weaken so that the convergence drift is effectively reduced.

Abstract: A color cathode ray tube having an electron gun including an electron beam generating portion arrayed in a horizontal direction for generating three electron beams, and a main lens for focusing the three electron beams from the electron beam generating portion upon a fluorescent face. A final stage of the main lens is formed between a focusing electrode and an accelerating electrode. The focusing electrode is divided into at least two focusing electrode parts. A quadrupole electron lens is formed for each of the electron beams between a first focusing electrode part and a second focusing electrode part, and the strength of the quadrupole electron lens for the central electron beam is different from the strength of the quadrupole electron lens for the side electron beams.

Abstract: A color cathode ray tube includes a phosphor screen, an in-line type electron gun having an electron beam generating section for projecting three electron beams arranged in parallel with each other in a horizontal plane toward the phosphor screen, a focus electrode, and an anode adjacent to the focus electrode and forming a main lens in cooperation with the focus electrode for focusing the electron beams on the phosphor screen. The focus electrode includes at least a first focus sub-electrode and a second focus sub-electrode on the order named from the cathode, the first focus sub-electrode and the second focus sub-electrode forming an electrostatic quadrupole lens therebetween.

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: 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 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: A method and device for reducing moiré by preventing the production of the second harmonic of the video signal Nyquist frequency. A nonlinear function is applied to one of a) a digital video signal having a nonlinearity between an electrical video signal and luminance, and b) an analog video signal to create an output signal having a linearity between the electrical signal and luminance. The output signal is displayed on a display having a linearity between the electrical signal and luminance.

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: A focus electrode 4 is constituted by first type of focus electrode groups 43, 45 to which a first focus voltage is applied, and second type of focus electrode groups 44, 46 to which a second focus voltage is applied. Between the first type of focus electrode groups and the second type of focus electrode groups are formed a lens for correcting the field curvature and an electrostatic quadruple lens. The center axes of the outer electron beam passage holes in the first type of focus electrode forming the lens for correcting the field curvature are deviated on a horizontal plane from the center axes of the outer electron beam passage holes in the second type of focus electrode. The electrostatic quadruple lens produces dissimilar intensities for the outer electron beams and for the center electron beam.

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: 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 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: An electron gun assembly which integrates electronics required to power the electron gun and the electron gun itself in one module in a high voltage operating environment. The assembly has four major sections: interface cables; electronic circuits (active and high voltage); the electron emitter; and a mechanical enclosure for the assembly. The electronics portion of the assembly has two distinct sections: an active electronics section (which contains digital to analog converters, interface to a control computer, and analog outputs terminals to control the high voltage electronics) and a high voltage electronics section (which contains high-voltage multiplying circuits and feedback and filtering elements). These two sections are electrically connected and are present within an internal box at one end of the assembly, or alternately, the high voltage electronics section is disposed below the active electronics section and outside the internal box.

Abstract: A color cathode ray tube includes a panel section having an internal surface with a phosphor layer formed thereon and a neck portion accommodating therein an electron gun assembly for emission of a plurality of electron beams plus a funnel section connecting the panel section and the neck portion together, wherein the electron gun assembly is designed to have a plate-shaped electrode with a plurality of electron beam passage holes corresponding in the number to the electron beams. The plate electrode has cylindrical bulged portions projecting in a way corresponding to the plurality of electron beams, each of which portion has its top face in which an electron beam opening or hole is formed. The present invention provides a color cathode ray tube comprising a readily manufacturable high-resolution electron gun assembly.

Abstract: An AKB interface apparatus in a display system (10), includes a video signal processing IC (12) having outputs coupled via respective kinescope driver ICs (18,20,22) to respective kinescope cathodes (K1,K2,K3) for display of a color image, the signal processing IC having an input 27 for receiving an AKB input signal, the driver ICs having respective outputs (28,30,32) providing respective cathode current indicating signals (RP,GP,BP) An interface circuit (100) couples the cathode current indicating signals to the AKB input of the signal processing IC. The interface circuit comprises a load circuit (110) for generating a load voltage (Vo) in response to at least one of the cathode current indicating signals. A leakage correction circuit (130), responsive to said load voltage (Vo), feeds back a leakage correction current (Io) to the load circuit.

Abstract: A color cathode ray tube includes a phosphor screen, cathodes, a G1 electrode, a G2 electrode, a G4 electrode, a G5 electrode and an anode for focusing the electron beams on the phosphor screen. The G5 electrode is divided into plural sub-electrodes arranged to be supplied alternately with a first focus voltage and a second focus voltage, at least one electrostatic quadrupole lens is formed between two of the sub-electrodes supplied with the first and second focus voltages, respectively, at least one lens for correcting curvature of the image field is formed between two of the sub-electrodes supplied with the first and second focus voltages, respectively. The G4 electrode, the G5 electrode and the phosphor screen satisfy following inequalities: 0.0625×L (mm)≦B−20A/(3&phgr;)≦22.

Abstract: A field emission display (100, 200, 300) includes a plurality of offset phosphors (126) and a cathode plate (110). Cathode plate (110) has a plurality of non-electron-emissive structures (112), a plurality of electron-emissive pixels (108), and a plurality of focusing electrodes (106). Offset phosphors (126) are aligned one each with non-electron-emissive structures (112) of cathode plate (110). Focusing electrodes (106) are disposed to cause a plurality of emission currents (134), which are generated by electron-emissive pixels (108), to be directed one each toward offset phosphors (126). Ions liberated from offset phosphors (126) are received by non-electron-emissive structures (112) of cathode plate (110), thereby ameliorating ion bombardment of electron-emissive pixels (108).

Abstract: An inline type electron gun assembly has a main lens for focusing three electron beams on a phosphor screen. A resistor is arranged in a cathode ray tube. A voltage obtained by dividing a high voltage with the resistor is applied to an intermediate electrode. Voltages of a focusing electrode, the intermediate electrode, and a final accelerating electrode that constitute the main lens are determined to increase sequentially. Electron beam holes in the intermediate electrode on the focusing electrode side, and electron beam holes in the intermediate electrode on the final focusing electrode side form vertically elongated holes longer in the vertical direction than in the horizontal direction. Electron beam holes in the focusing electrode on the intermediate electrode side and electron beam holes in the final accelerating electrode on the intermediate electrode side form open holes having no side wall portions.

Abstract: A dynamic focus circuit enables ideal focusing characteristics to be obtained across the entire screen of a wide-angled cathode ray tube, by generating a dynamic focus voltage having a flat-bottomed waveform through the addition of a simple circuit to a conventional analog circuit. If an S-shaping voltage method is used, the voltage of a signal induced in a secondary coil of a step-up transformer for raising the voltage of a parabolic waveform signal having a horizontal deflection period switches the gain for converting the parabolic waveform signal to a dynamic focus voltage, according to whether the induced voltage exceeds a specified reference value. If the induced voltage does not exceed the specified reference value, the parabolic waveform signal is converted to the dynamic focus voltage at a gain of less than one.

Abstract: An internal resistor within a color cathode ray tube (CRT) is connected to a voltage source and is coupled across a G4 grid and a G6 grid of the CRT's multi-grid quadrupole (QPF) electron gun. De-coupling the G4 grid from the G2 grid in the electron gun's prefocus lens and operating the G4 grid at a higher voltage as used in the gun's high voltage main focus lens moves the equivalent lens of the prefocus and main focus lenses toward the CRT's display screen and reduces electron beam magnification and spot size for improved video image definition and focusing.

Abstract: A video imaging apparatus includes a source of a periodic dynamic focus voltage blanking signal. A dynamic focus voltage amplifier includes a switch responsive to the dynamic focus voltage blanking 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 to provide for automatic kine bias measurement. A second switch responsive to the focus voltage blanking signal is coupled to the amplifier for applying a current to a stage of the amplifier, when the dynamic focus voltage is disabled. The applied current adjusts the focus voltage, to a level closer to that established immediately after the dynamic focus voltage is enabled for reducing a transient condition.

Abstract: A direct current focus voltage applied to a focus electrode of a cathode ray tube that produces a blue image is set to slightly defocus the blue image for increasing the blue beam spot size. The increase in the blue beam spot reduces the saturation and allows brighter blue and increased blue video drive range. A passive network is coupled between an ultor electrode and the focus electrode to provide tracking of focus voltage-to-ultor voltage ratio. The tracking prevents voltage fluctuation of the ultor voltage produced by video loading from disturbing uniform defocussing in the entire blue image.

Abstract: In a dynamic focus circuit for a CRT, a first saw wave generating circuit generates a first saw wave signal in reponse to a horizontal synchronization signal, and a first amplifier amplifies the first saw wave signal with a first gain. Also, a first differential amplifier, amplifies the difference in voltage between the output signal of the first amplifier and a first reference voltage signal, and a first multiplier, calculates a square value of the output signal of the first differential amplifier to generate a horizontal parabolic signal. Similarly, a vertical parabolic signal is generated by a second saw wave circuit, a second amplifier, a second differential amplifier and a second multiplier. The horizontal parabolic signal and the vertical parabolic signal are added by an adder to generate a focus control signal.