Abstract: A bias circuit and a method for operating the same minimizes a picture distortion. The bias circuit includes a main capacitor and a plurality of sub capacitors for compensating picture distortion, a controller provides control signals having different duty cycles, and a plurality of switches receiving each of the switch control signals and changing each link (or path) between the main capacitor and the sub capacitors in accordance with the received switch control signals.

Abstract: The present disclosure describes a technique for reducing east-west geometry mismatch between the top and bottom of a raster display. This is accomplished by generating a horizontal correction signal that does not have any discontinuities. Since there are no discontinuities in the horizontal correction signal, the horizontal deflection current signal will not be distorted. As a result, there will be no east-west geometry mismatch between the top and bottom of the raster display.

Abstract: A parabola generator for providing dynamic correction includes a capacitor source of a parabolic input signal at a frequency related to a horizontal deflection frequency coupled to a first terminal of the capacitor. A diode switch is coupled to a voltage at a reference level and to a second terminal of the capacitor for periodically clamping a peak level of a signal developed at the second terminal. A transistor switch is responsive to a periodic switch control signal and coupled to the second terminal of the capacitor for periodically clamping a signal applied from the second terminal, during retrace, for removing a parasitic parabolic voltage portion to generate a dynamic correction signal. The dynamic correction signal is coupled to the cathode ray tube to vary a field in a beam path of an electron beam of the cathode ray tube for providing dynamic correction.

Abstract: A color image display device has an auxiliary means for compensating brightness simply and inexpensively by using an electron gun of a cathode ray tube. Brightness uniformity is improved in the image display device having a flat-type color cathode ray tube with a glass panel having a high wedge ratio and a low transmissibility. The color image display includes a panel housing a screen on an inner face thereof, a funnel engaged with the panel; an electron gun engaged with a neck portion of the funnel for emitting electron beams toward the screen, a deflection device for displaying an image by deflecting the electron beams emitted from the electron gun in horizontal and vertical directions with respect to the screen, and a cathode ray tube including a shadow mask aligned from the screen at a predetermined distance.

Abstract: An apparatus for generating a dynamic focus signal appropriate for a flat-type CDT, or flat-screen CRT has a first multiplier for receiving a horizontal sawtooth wave and outputting the square component of the wave; a second multiplier for receiving a vertical sawtooth wave and outputting the square component of the wave; a third multiplier for multiplying the outputs of the first and the second multipliers; and a mixer for mixing the outputs of the first through the third multipliers and outputting the result as a dynamic focus signal. The apparatus is able to perform optimal focus control appropriate for a flat-screen CRT.

Abstract: A horizontal dynamic focus regulation circuit, which induces a horizontal dynamic focus waveform voltage by a horizontal deflection circuit generating a different frequency according to a display mode of a display apparatus, comprising a microcomputer outputting a plurality of control signals; a plurality of switching parts corresponding to the plurality of control signals outputted from the microcomputer, respectively; a plurality of S-regulation capacitors connecting with the plurality of switching parts in series, respectively; an auxiliary capacitor provided on a line diverged from a line connecting each switching part with each S-regulation capacitor, and being respectively connected with the S-regulation capacitor in parallel and series according to switching on and off of the switching part. With this configuration, the dynamic focus regulation circuit supplies a uniform parabolic waveform voltage regardless of variation of a horizontal frequency in a display mode.

Abstract: An object of the present invention is to obtain excellent images which are free from distortion in a flat display apparatus including electron-emitter elements, phosphors, and spacers. A structure of the present invention is such that the display apparatus comprises a display panel including a first substrate having a plurality of electron-emitter elements, a second substrate having phosphors, and spacers; and driving means employing a line-sequential scanning method; wherein scan pulse output is performed by the driving means, and the driving means performs scanning in such a manner that a scan is performed in the direction of approaching a relevant one of the spacers from far. Thus, the present invention realizes the excellent display images which are free from distortion by largely reducing or eliminating influence of charging of the spacers to be exerted on the images.

Abstract: A dynamic focus voltage generator includes a source of a flyback input signal at a horizontal deflection frequency. A double integrator is responsive to the input signal for generating a parabolic periodic signal. An amplitude detector is responsive to the parabolic periodic signal for generating a control signal that is indicative of an amplitude of the parabolic periodic signal. A comparator is responsive to a signal at a reference level and to the control signal and coupled to the double integrator for regulating an amplitude of the parabolic periodic signal in a gain control negative feedback manner. A non-linear network is responsive to the parabolic periodic signal for producing a bathtub shaped output signal that is coupled to a focus electrode of a cathode ray tube.

Abstract: A raster center control circuit for a CRT-type display device that automatically determines a correct horizontal center position of a raster, regardless of a horizontal sync frequency input from a video card. The raster center control circuit includes a horizontal deflection circuit, electrically connected to a horizontal deflection yoke, to supply the horizontal deflection yoke with a parabolic wave signal used to determine a horizontal center position of the raster. A memory device stores predetermined values for raster control according to horizontal sync signal frequencies. A microprocessor determines a frequency of a horizontal sync signal and generates a raster control signal by converting one of the predetermined values stored in the memory device into a raster control signal according to the predetermined frequency.

Abstract: An electrode assembly includes at least first and second electrodes for forming one or more dynamic quadrupole lenses to emit electron beams and an electron gun using the same. A first parabolic waveform signal having voltages decreasing from the center to the periphery of a screen on which the electron beams land is applied to the first electrode, and a second parabolic waveform signal having voltages increasing from the center to the periphery of the screen is applied to the second electrode, in synchronization with horizontal and vertical deflection signals for horizontally and vertically deflecting electron beams emitted from the electrode assembly.

Abstract: A color-cathode-ray-tube electron gun of the present invention comprises a three-divided first focus electrode and a second focus electrode set so as to oppose the first focus electrode: wherein a parabolic-waveform voltage synchronizing with horizontal scanning is applied to the second focus electrode; of the three-divided focus electrodes, a built-in resistor electrically connecting the central electrode and the both outside electrodes is provided; a voltage on which a first voltage component having a waveform similar to serration and synchronizing with horizontal scanning, and a second voltage component having a parabolic waveform convex in the direction opposite to the parabolic waveform and synchronizing with horizontal scanning are superimposed is applied to the central electrode, and a voltage obtained by passing the voltage on which the first voltage component and second voltage component are superimposed through the built-in resistor is applied to the both outside electrodes.

Abstract: In a waveform generator, a repetitive non-linear waveform is generated by varying the number supplied to a pulse reduction circuit during the repetition period. Consequently, the pulse reduction circuit supplies a number of desired output pulses, which number varies in time corresponding to the varying number. For example, when a lower number is inputted to the pulse reduction circuit during a sub-period of the repetition period, a corresponding lower number of output pulses will be generated. Consequently, a lower number of increment values will be summed or integrated during this sub-period and the waveform changes less steeply.

Abstract: A simple and cheap dynamic S-correction circuit compensates the higher order errors like the so-called moustache effect and the inner linearity distortion. This is achieved in a known way by connecting an additional proper tuned S-capacitor in parallel with the original one during the start and end of the scan interval. Duty cycle modulation of the on/off times as a function of the frame compensates the inner-pin distortion (also called inner-linearity or modulated S-correction). The duty cycle or the switch on and off instants required to compensate the horizontal distortion or moustache effect is derived by comparing the AC parabolic waveform generated on the S-capacitors with a DC-voltage. Duty-cycle modulation required for compensation of the inner-pin distortion is, in this way, automatically obtained.

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: A method for generating display correction waveforms for a CRT display comprises the steps of selecting one of a plurality of trace portions for forming part of a correction waveform, the trace portions having different average values. Completing each of the correction waveform by combining each selected trace portion with a respective retrace portion such that all completed correction waveforms have a predetermined average value.

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 apparatus for compensating for corner focus and brightness in a CRT improves compensation efficiency for corner focus and brightness regardless of the dimensions of the CRT and minimizes the manufacturing cost and power consumption. The apparatus for compensating for corner focus and brightness in a CRT includes a CRT, a parabola signal generator for generating a parabola signal from input vertical and horizontal driving pulses, a fly back transformer for supplying high voltage of parabola waveform to an anode electrode of the CRT, an adder for adding the parabola signal of the parabola signal generator and a feedback voltage from the fly back transformer, an error amplifier for amplifying error components of an output voltage of the adder and a reference voltage, and a +B converter for converting the output of the error amplifier to a direct current voltage level required to operate the fly back transformer.

Abstract: A method for controlling the power consumption in a tilt correcting coil is disclosed. The power consumption is corrected Controlling power consumption in the tilt correcting coil for correcting to correct the tilt of the images of on the cathode ray tube. If When a microcomputer judges that the mode is the on-state mode, then the microcomputer outputs a tilt correcting PWM signal in accordance with the user's inputting input. Then the The output tilt correcting PWM signal is converted into a dc voltage, and the level is adjusted. Then the signal is supplied to the tilt correcting coil, so that the tilt of the image on the screen would be is corrected. In the cases of the standby mode, the suspend mode and/or the or power-off mode, the microcomputer outputs a signal which has a function of minimizing the to minimize power consumption of by the tilt correcting coil. Therefore, the tilt Tilt of the image of the screen is corrected in the normal manner.