Abstract: Disclosed is an image misconvergence correction apparatus having a correction value generation unit for calculating a convergence correction value to correct misconvergence occurring when a video signal is scanned on a display device; an amplification unit for performing D-class amplification with respect to the convergence correction value; a convergence yoke mounted in the display device to control a path of electron beams corresponding to the video signal based on the convergence correction value amplified in the amplification unit; and a feedback sensing unit for differentially amplifying a voltage value for electric current passing through the convergence yoke, and feeding back the differentially amplified voltage value to the correction value generation unit.

Abstract: An image distortion correction apparatus is disclosed which can correct misconvergence using a D-class amplifier. The image distortion correction apparatus has an image processor for detecting an image signal and horizontal/vertical synchronous signals from a signal received from an external source; a distortion value calculator for calculating a misconvergence value occurring when the image signal is scanned based on the horizontal/vertical synchronous signals; a correction value calculator for calculating a convergence correction value of a pulse waveform to correct misconvergence of the image signal based on the misconvergence value; an amplifier for performing a D-class amplification with respect to the convergence correction value; and a convergence yoke fixed to a cathode ray tube (CRT) for controlling a path of an electron beam corresponding to the image signal based on the convergence correction value amplified in the amplifier.

Abstract: In a color display device, apparatus and method are provided to produce a convergence correction signal based on digital convergence correction values. The data rate by which the data is supplied to the apparatus varies, depending on the area of the display corresponding to the digital convergence correction values being supplied.

Abstract: An image distortion compensating apparatus controls a convergence yoke, and includes a compensation value generator for calculating a convergence compensation value for compensating a convergence distortion which occurs while an image signal is emitted onto a display apparatus, the compensation value generator outputting the convergence compensation value after compensating for a phase and a gain of the convergence yoke; an amplifier for D-class amplifying of the convergence compensation value; and a convergence yoke attached to the display apparatus for controlling a path of electron beams corresponding to the image signal, based on the convergence compensation value as amplified at the amplifier.

Abstract: A cathode ray tube including a tube realized through a face panel, a funnel, and a neck; a color selection apparatus including a shadow mask having a an effective area with apertures and a mask frame supporting the shadow mask; an electron gun mounted in the neck and emitting electron beams; a deflection apparatus generating a magnetic field to deflect the electron beams; and a moire compensation circuit performing moire compensation, wherein the color selection apparatus satisfies the following condition, 0.76 ≥ Ke Ko ≥ 0.

Abstract: A deflecting yoke apparatus comprising first and second frame coils configured to correct a vertical horizontal misconvergence first and second main coils and first and second sub-coils which are wound around a core and configured to deflect in a vertical direction electron beams which have passed through a magnetic field generated by the first and second frame coils, a first deflecting current supply portion configured to pass a serriform deflecting current to the first and second main coils, and a second deflecting current supply portion configured to supply to the first and second sub-coils through a first and second diodes connected in parallel so as to have opposed directions a deflecting current which is supplied to the first and second main coils by the first deflecting current supply portion.

Abstract: Electron gun for cathode ray tube comprising aligned in series along an axis XX′ an electron-emitting cathode K, electrodes G1 and G2 for the formation of an electron beam, a prefocusing electron lens G3, G4, G5, a first quadripolar device G7, G8 electrically controlled in a dynamic manner in synchronism with the screen scan so as to correct beam focusing defects at the screen edge, a main electron lens G8-G9 making it possible to focus the electron beam onto a screen.

Abstract: The object of the present invention is to provide a field emission device that emits an electron beam bundle whose spot profile on a display screen has as little distortion as possible, and that maintains a stable electron emission property regardless of the length of a driving time, a CRT apparatus equipped with such field emission device, and a production method of such CRT apparatus. The field emission device (10) has, on a surface of a substrate (11), a plurality of cathode electrodes (12) parallel to each other, an insulation layer (13), and a plurality of extraction electrodes (14) parallel to each other, in the stated order, the cathode electrodes (12) and the extraction electrodes (14) being orthogonal to each other and so yielding a plurality of crossover regions. At the crossover regions, electron emission zones (15) each made up of four emitters (16) are formed.

Abstract: A group of an upper coma correction coil and an upper four-pole coil is positioned in opposition to a group of a lower coma correction coil and a lower four-pole coil, with respect to an electron beam. A first circuit is composed of a circuit in which the lower four-pole coil and a first diode are connected in series is connected in parallel to the upper coma correction coil. A second circuit is composed of a circuit in which the upper four-pole coil and a second diode are connected in series is connected in parallel to the lower coma correction coil. The first circuit and the second circuit connected in series compose a YH correction circuit. The first diode and the second diode are positioned so as to have opposite polarities. Vertical deflection current is diverted to the YH correction circuit.

Abstract: An image processing apparatus is disclosed by which correction of convergence and correction of distortion of an image can be performed with a high degree of accuracy. Correction data to be used for correction of position errors of the three colors of red, green and blue obtained by an adjustment apparatus in advance are stored in a storage section. The stored correction data are outputted to a correction waveform outputting section through a control circuit when necessary. The correction waveform outputting section produces correction waveforms based on the correction data inputted thereto and outputs the correction waveforms to a clock signal generation circuit. The clock signal generation circuit generates clocks, and the video data of red, green and blue stored in the memory are read out in response to the clock signals.

Abstract: A method for producing a plurality of successive output data values defining an output curve that approximates an input curve defined by a plurality of input sample values, the output data values having a higher sampling frequency than the input sample values, the method comprising the steps of: pre-emphasizing the plurality of input sample values; defining successive and overlapping intervals including at least three of the pre-emphasized input sample values; interpolating a plurality of the output data values in an interpolation interval by calculating a moving average of a linear interpolation curve based on the at least three pre-emphasized input sample values, each of the output data values being influenced by the at least three pre-emphasized input sample values; and, emphasizing differently the influence of the at least three pre-emphasized input sample values for determining different ones of the output data values in the interpolation interval, whereby the pre-emphasizing step brings the output curve

Abstract: A method for adjusting convergence in a projection television receiver, in which a marker contained in a projected image is adjusted by a manipulated variable to illuminate a photosensor arranged adjacent to the projection screen. The method employs two markers which are moved towards the sensor from opposite directions with a varying step size. The sensor supplies an output voltage indicating lighting by the two markers in conjunction with two mutually spaced manipulated variables. A mean value of the two manipulated variables is used as the manipulated variable for the marker.

Abstract: A method for generating a convergence correction curve from a plurality of successive output data values determined from a plurality of input sample values smaller in number than the plurality of output data values, the method comprising the steps of: defining successive and overlapping intervals including exactly three of the input sample values; interpolating a plurality of the output data values in an interpolation interval by calculating a moving average of a linear interpolation curve based on the three input sample values, each of the output data values being influenced by the three input sample values; emphasizing differently the influence of the three input sample values for determining different ones of the output data values in the interpolation interval; and, adjusting the input sample values to control convergence correction, whereby each incremental slope of the correction curve between adjacent output data values varies smoothly.

Abstract: The present invention relates generally to an electron gun for a color cathode ray tube, and more particularly to an electron gun for achieving an excellent focus characteristic on the whole screen by forming a dynamic quadruple lens in the electron gun used for a transpose scan type cathode ray tube.

Abstract: The present invention relates generally to an electron gun for a color cathode ray tube, and more particularly to an electron gun for achieving an excellent focus characteristic on the whole screen by forming a dynamic quadruple lens in the electron gun used for a transpose scan type cathode ray tube.

Abstract: The invention relates to a color display device comprising an in-line electron gun (5) for generating three electron beams (6, 7, 8), and a convergence unit (14′) to dynamically influence the convergence of the electron beams and deflecting means (51) for deflecting the electron beams (6, 7, 8). The convergence unit (14′) comprises a ring-shaped element (21′), said ring-shaped element comprising two parts, a first part (60) being positioned closer to the in-line gun (5) than a second part (68), and the first and/or the second part having four coils (22′) for generating a magnetic quadrupole field.

Abstract: A convergence control method and apparatus for a projection television are provided. The convergence control apparatus includes an image signal decoder, a convergence control unit, and a main microcomputer. The image signal decoder processes an input image signal and generates a data signal and horizontal and vertical synchronization signals, and a start signal indicating the start of either the horizontal and vertical synchronization signals. The convergence control unit performs convergence adjustment according to a convergence control command it receives, and generates a completion signal when convergence adjustment is complete. The main microcomputer inputs the convergence control command to the convergence control unit when the start signal is input from the image signal decoder, and performs a control operation to display the image signal when the completion signal is input from the convergence control unit.

Abstract: In an inline three-beam system color cathode-ray tube, there is provided an inline three-beam system color cathode-ray tube electron gun in which beam spot shapes of three electron beams on the left and right end portions of a fluorescent screen may be uniformed as much as possible and focusing voltages may be adjusted with ease and also deteriorations of beam spot shapes of three electron beams on the left and right end portions of the fluorescent screen may be alleviated and a satisfactory convergence characteristic may be obtained on the whole region of the screen. A color cathode-ray tube electron gun includes trisected focusing electrodes.

Abstract: A device for correcting residual mis-convergence errors in a color cathode ray tube, the tube including a narrow-necked section, located at the rear thereof, in which electron guns mounted therein generate forwardly-directed red, blue and green electronic beams, an outwardly-opening center skirt section, extending forward from the narrow-necked section, and terminating in a wide perimeter surrounding a relatively flat, pixel-coated, viewing screen section that is arranged generally orthogonal to the axis of the narrow-necked section and upon which the electronic beams are directed to strike the pixels to produce color and images for viewing from the front of the tube, and further having at least one pair of electromagnetic coils mounted outside the tube, for initial focusing of the electron beams during their travel from the guns to the screen, the device including a separator made of a plastic, including a high density of magnetizable particles therein, the separator arranged for placement about the outside

Abstract: A color display device having an electron gun, a display screen, a color selection electrode and a deflection unit. The distance between the electron beams in the x-direction is dynamically varied, whereby the distance in the deflection space decreases as the beams are deflected in at least one direction. The reduction of the distance enables the distance between the color selection electrode and the display screen to be increased in that direction. As a result, the curvature of the color selection electrode is increased, which has a positive effect on the strength and the doming and microphonic properties of the color selection electrode.

Abstract: A deflection yoke for use in a cathode ray tube includes a switching circuit, which is coupled to each vertical coil. The deflection yoke employs two pairs of vertical coils. The vertical coil pairs can be two pairs of saddle type coils, one pair of saddle type coils and one pair of toroidal type coils, or a divided pair of saddle type coils to make two pairs of saddle type coils. The deflection in the first quarter region from the top and the last quarter region at the bottom of the CRT screen is provided by one coil when energized by the vertical deflection current switched through it. The deflection in the two middle quarter regions of the CRT screen is provided by a second coil when energized by the vertical deflection current switched through it. One vertical coil pair is optimized to correct convergence error in the top and bottom quarter portions of the CRT screen. The other vertical coil pair is optimized to correct convergence error in the middle portion of the CRT screen.

Abstract: A problem to be solved by the invention is to prevent a digital convergence correction device from lowering in precision of correction performed when a relation between screen raster and effective area of picture varies. A vertical display area detection signal that corresponds to a position in vertical direction of a picture display area on a screen is generated in accordance with a vertical deflecting current. An address counter for generating an address for reading out correction data is controlled in accordance with the signal.

Abstract: A CRT display apparatus capable of displaying images in high contrast and high brightness without causing noises and halftone-reproduction degradation within dark areas is disclosed. The apparatus includes a circuit for generating an R-control signal, a G-control signal and a B-control signal by removing, from each of the R-, G- and B-video signals, portions which are below a predetermined level in amplitude, an amplification circuit for inverting and amplifying the R-, G- and B-control signals, and a selection circuit for selecting, for each of the three G1 electrodes, either a corresponding one of the R-, G- and B-control signals inverted and amplified by the amplification circuit or a potential of a predetermined value in accordance with an instruction from an outside, and applying each of the three G1 electrodes with a selected one of the corresponding one of the R-, G- and B-control signals and the potential.

Abstract: A method for measuring a convergence of color CRT uses a combination pattern among Red(R), Green(G) and Blue(B) colors on a white pattern when measuring convergence by using a color camera so that convergence is measured with a high degree of precision. The method sequentially generates two test patterns after mixing two colors chosen from among red(R), green(G), and blue(B) colors, e.g., mixtures of red(R)/blue(B) and green(G)/blue(B). Images are independently obtained of the two test patterns formed on the color CRT screen, and a signal conversion is performed based on each independently obtained pattern image to produce image information. The image information is stored and a convergence of the stored image information for each test pattern is calculated.

Abstract: A group of an upper coma correction coil and an upper four-pole coil is positioned in opposition to a group of a lower coma correction coil and a lower four-pole coil, with respect to an electron beam. A first circuit is composed of a circuit in which the lower four-pole coil and a first diode are connected in series is connected in parallel to the upper coma correction coil. A second circuit is composed of a circuit in which the upper four-pole coil and a second diode are connected in series is connected in parallel to the lower coma correction coil. The first circuit and the second circuit connected in series compose a YH correction circuit. The first diode and the second diode are positioned so as to have opposite polarities. Vertical deflection current is diverted to the YH correction circuit.

Abstract: A convergence control method and apparatus for a projection television are provided. The convergence control apparatus includes an image signal decoder, a convergence control unit, and a main microcomputer. The image signal decoder processes an input image signal and generates a data signal and horizontal and vertical synchronization signals, and a start signal indicating the start of either the horizontal and vertical synchronization signals. The convergence control unit performs convergence adjustment according to a convergence control command it receives, and generates a completion signal when convergence adjustment is complete. The main microcomputer inputs the convergence control command to the convergence control unit when the start signal is input from the image signal decoder, and performs a control operation to display the image signal when the completion signal is input from the convergence control unit.

Abstract: In color display tubes (1) with a dotted shadow mask (13) structure and an in-line electron gun (10), the geometry of the screen (6) and the deflection field produced by the deflection unit (11) cause triad rotation, which is a rotation of the three phosphor dots (red, green and blue) corresponding to one aperture of the shadow mask (13) with respect to the horizontal scan lines (35). This problem can be solved by giving the horizontal lines (35) a curved shape. However, in the prior art situation a parabolic shape is used, leading to severe moiré problems, because the vertical pitch asv (38) is influenced too strongly at the vertical screen edges. This problem can be overcome by using fourth order or even sixth order terms in the shape of the horizontal lines (35). A pure fourth order function reduces the vertical pitch asv 38 variation by 50% with respect to the parabolic prior-art situation, and a pure sixth order function even leads to a reduction by 67%.

Abstract: A CRT display apparatus capable of displaying images in high contrast and high brightness without causing noises and halftone-reproduction degradation within dark areas is disclosed. The apparatus includes a circuit for generating an R-control signal, a G-control signal and a B-control signal by removing, from each of the R-, G- and B-video signals, portions which are below a predetermined level in amplitude, an amplification circuit for inverting and amplifying the R-, G- and B-control signals, and a selection circuit for selecting, for each of the three G1 electrodes, either a corresponding one of the R-, G- and B-control signals inverted and amplified by the amplification circuit or a potential of a predetermined value in accordance with an instruction from an outside, and applying each of the three G1 electrodes with a selected one of the corresponding one of the R-, G- and B-control signals and the potential.

Abstract: The present invention relates to a deflection yoke, and in particular, to an apparatus for correcting a mis-convergence and geometric distortion in a deflection yoke using a variable resistance, proving a more convenient way to adjust VCR by adjusting the current flowing in a comma-free coil using a variable resistance, instead of attaching a magnetic member as in the conventional method for the products associated with VCR (Vertial Green) properties.

Abstract: A color TV tube apparatus having a horizontal deflection coil for generating a pincushion-shaped horizontal deflection field, which uses a self-convergence method. In such a color TV tube, the horizontal deflection coil is adjusted so that the vertical focus points of the electron beams lie 50 mm or less on the inside and 30 mm or less on the outside of each edge of the effective display screen area along the horizontal axis. The horizontal deflection coil is adjusted with the focusing of an electron beam by a lensing action of an electron gun non-operational.

Abstract: The invention is intended to enable the easy measurement of the amount of color purity at each of many measured points. An adjusting coil (9) is provided at a neck portion of a color cathode ray tube (1). Also, a color image pickup means (4) for photographing the screen of the color cathode ray tube (1) is provided. A monochrome signal of any one of red, green, and blue colors is input to this color cathode ray tube (1). Thereafter, while varying the electric current made to flow through the adjusting coil (9), the image pickup signal obtained by the color pickup means (4) is decomposed into red, green, and blue color signal components; and the intensity of each of them is measured.

Abstract: A color display device comprises an electron gun, a display screen and a color selection electrode as well as a deflection means. The distance between the electron beams is dynamically varied, i.e. the distance between the electron beams in the deflection plane decreases as the beams are deflected in at least one direction. The decrease of the distance enables the distance between the color selection electrode and the display screen to be increased in that direction. As a result, the curvature of the color selection electrode is increased, which has a position effect on the strength, doming and microphonics of the color selection electrode. The distance is dynamically varied by first and second means, the first means being arranged in or near the pre-focusing parts of the electron gun. Said first means comprise magnetic means outside the neck of the CRT for generating dynamically varying magnetic fields, and magnetic field conducting means to conduct the fields to a position near the electron beams.

Abstract: An apparatus and method are provided for measuring convergence of the Red-Green-Blue (R.G.B.) signals of a color cathode ray tube (CRT) using a color charge coupled device (CCD) camera. A uniform R.G.B. brightness value is picked up by the color CCD camera at all positions of the CRT screen when the color CCD camera images the screen, thus enabling convergence to be more accurately measured and adjusted. Test patterns having a constant R.G.B. brightness value are displayed on the screen of the CRT by a pattern generator. The displayed test patterns are picked up by the color CCD camera, and when the R.G.B. brightness values differ from a corresponding reference brightness value, a controller adjusts the intensity of each of the R.G.B. signals of each test pattern by suitably controlling the pattern generator. A uniform R.G.B. brightness value is thus provided for all test patterns displayed on the CRT screen. Only after the R.G.B.

Abstract: An apparatus and method for ring spline convergence correction for accurately affecting convergence at the outermost portion of a screen using ring spline interpolation are provided. Convergence correction data between seed data is output through an operation using a spline interpolation polynomial in the form of a ring which is continuous with an adjacent line, thereby accurately calculating convergence correction data at the outermost point of a screen to minimize the error in convergence.

Abstract: An image display correcting apparatus of the invention comprises, broadly, a correction data forming apparatus and an image display apparatus. Correction data for correcting a display state of an image is formed by the correction data forming apparatus on the basis of an image as a reference displayed on the screen of a CRT. Further, on the basis of the correction data, an operation of correcting image data is executed so that an image is accurately displayed on the image display apparatus. The corrected image data is outputted to the CRT. Thus, a defective display state such as image distortion, misconvergence, or the like can be corrected at low cost and a high quality image can be displayed.

Abstract: A landing correction coil is provided at the rear of a horizontal deflection coil of a deflection yoke or at a position where it is closely coupled with the horizontal deflection coil. The landing correction coil is fixed so as to generate a magnetic field perpendicular to the axis of a CRT. Moreover, the landing correction coil is connected so that a current flowing in a horizontal deflection coil may flow in the landing correction coil. Furthermore, the landing correction coil is connected to an adjustment coil for adjusting the current flowing therein. A varying means is provided in the adjustment coil and the polarity and amplitude of the current flowing in the landing correction coil is adjusted by the varying means. This causes the magnetic field distribution for scanning an electron beam of a CRT to be changed and enables a landing characteristic to be adjusted electrically.

Abstract: A method and system for providing two-dimensional convergence correction for a color cathode ray tube (CRT) is disclosed. The CRT displays an input video signal comprising a stream of video scan lines which include red, green and blue color signals that are to be displayed on corresponding scan lines and subpixel locations of a display screen. The method and system include storing a plurality of scan lines from the video signal into a buffer. For a particular red, green and blue color signal, horizontal and vertical distortion of the red and blue subpixels in relation to a position of the green subpixel on the display screen are measured. Then, at least one math function is generated that mathematically represents the distortions. Finally, the math functions are applied to control circuitry to control timing of red and blue subpixels read from the frame buffer so that output of the red and blue subpixels are coincident with output of the green subpixel on the display screen.

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 convergence correction circuit including a coordinate unit which sets a predetermined range with first level values according to a screen length; an interval unit which divides the screen length; an interval decoder which calculates the value of the branch point of each interval determined by the interval unit; an interval gain unit which stores the gain of each interval; a subtracter which subtracts the output of the coordinate unit from the output of the interval decoder; a multiplier which multiplies the output of the subtracter by the output of the interval gain unit; a level shifter which sets an initial and last value of each interval upon horizontal scanning; an adder which adds the output of the multiplier and the output of the level shifter; a digital-analog converter which converts the output of the adder; and a correction coil which corrects the convergence according to the converted output.

Abstract: The invention relates to a color display device comprising an in-line electron gun (5) for generating three electron beams (6,7,8), a deflection unit (51) for deflecting the electron beams (6,7,8) and a convergence unit (14′) for dynamically influencing the convergence of the electron beams. A variable transformer (40) is connected between the convergence unit (14′) and the deflection unit (51) for compensating undesired voltages induced by the deflection unit (51). The variable transformer (40) comprises three coils (47,48,49) wound around a hollow coil holder (43) and an adjustable core (42), which moves within the coil holder.

Abstract: In a color cathode ray tube having a flat panel exterior surface, the screen distortion and the convergence give rise to problems. To overcome these problems, by arranging bar magnets in such a manner that they are disposed parallel to a screen and are shifted from upper and lower ends of a horizontal deflection coil of a deflection yoke by not less than 10 mm in the direction perpendicular to a tube axis, the distortion of the screen and the characteristics of the convergence can be simultaneously improved.

Abstract: In a deflection yoke for use in a color cathode ray tube receiver, two sets of sextuple pole coils formed of bifilar windings are disposed around the orbits of three electron beams emitted from an electron gun of a cathode ray tube. Horizontal-period parabolic currents produced in a bridge circuit consisting of saturable reactors are caused to flow in such sextuple pole coils. Further the parabolic currents are modulated at the vertical period by the saturable reactor. Then sextuple-pole magnetic fields are generated by the modulated parabolic currents to thereby exert vertical force on the three electron beams, hence realizing proper correction of &Dgr;VCR to consequently optimize the balance between the corners and the center of a screen. Such optimization is conventionally difficult due to some restrictions existing in the winding distribution of a vertical deflection coil and a horizontal deflection coil in relation to convergence and focus of side beams.

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 television system performs beam convergence in video displays. The system is implemented through one or more convergence sensors, which are exposed to two distinct convergence test patterns. The output signals from the sensors when exposed to the two convergence test patterns are used in beam convergence calculations. The convergence test patterns are selected to reduce the dynamic range requirement for an A/D converter in the television system supplied with the sensor output signals.

Abstract: A switchable digital filter interpolates distortion correction values. The distortion correction values together with interpolated distortion correction values are supplied as an output. Proper operation of the digital filter is disturbed by transient signals occurring during horizontal retrace. The digital output is converted to an analog convergence correction signal. The digital to analog converter has an operating frequency and generates a transient signal during horizontal retrace as the operating frequency increases due to an increased horizontal scanning rate. A low pass filter receives the analog convergence correction signal and generates an analog deflection signal. An auxiliary deflection coil is driven by the analog deflection signal. The digital filter is switched off during the horizontal retrace. The digital filter is thus protected from disturbance by the transient signal and the digital to analog converter is protected from exceeding a maximum operating frequency.

Abstract: A convergence correcting apparatus and method of a television for automatically correcting convergence in consideration of terrestrial magnetism of a television location set by a user. Convergence is adaptively corrected in consideration of the terrestrial magnetism of a territory at which a television is installed, thereby preventing picture quality from deteriorating due to differences in the terrestrial magnetism of different territories.

Abstract: A problem to be solved by the invention is to provide a digital convergence correction device capable of coping with variation in scanning frequency at a reasonable price. The digital convergence correction device comprises a gate circuit for storing a variation in each convergence correction amount in a memory as correction data, and reading out the correction data synchronously with screen scanning at the time of integrating the correction data and causing the output time to be constant for each of the correction data read out.

Abstract: System for correcting an electron beam from a single cathode in an electron gun for a color CRT, in which the single electron beam emitted from the single cathode is controlled by a magnetic field generating device synchronous to an electron beam deflecting signal and a video signal applied to the cathode for realizing an optimal image, the system including a time division distributor for receiving a video signal and generating one of electron beam signals corresponding to a red, a green, or a blue fluorescent material, an electron gun with a single cathode for receiving any one of red, green, blue signals from the time division distributor and emitting a single electron beam, a deflection yoke for receiving a deflection signal and deflecting the electron beam emitted from the cathode to an entire region of a screen, a digital controller for receiving a signal from the time division distributor and the deflection signal, and a magnetic field generating device for receiving a signal from the digital controller