Abstract: The present invention discloses a method and apparatus for generating a synchronizing signal during a frequency switch-over of an input signal from a first frequency to a second frequency in a video monitor system. The method comprises the steps of: (1) detecting the frequency switch-over; (2) maintaining the synchronizing signal at the first frequency; (3) generating the synchronizing signal at a third frequency; (4) determining if the second frequency is valid; and (5) if the second frequency is valid, generating the synchronizing signal at the second frequency.

Abstract: A high-voltage generating circuit for use in a CRT display apparatus has a horizontal drive circuit which is supplied with a horizontal frequency signal synchronous with a horizontal synchronizing signal in an input signal, a high-voltage converter output circuit which can be turned on and off by an output signal from the horizontal drive circuit, and a flyback transformer connected to an output terminal of the high-voltage converter output circuit. A frequency multiplier connected between the horizontal drive circuit and a terminal supplying the horizontal frequency signal to the horizontal drive circuit multiples the frequency of the horizontal signal at the terminal by a multiplication factor variable depending on the frequency of the horizontal frequency signal.

Abstract: A display apparatus for displaying a video image operates with plural horizontal scanning frequencies. The apparatus includes a horizontal scanning frequency oscillator for generating a signal in synchronism with a horizontal synchronous signal of an input video signal; and a control unit for controlling a frequency of an output of the horizontal scanning frequency oscillator corresponding to the horizontal synchronous signal of the input video signal. A multi-scan video monitor may be provided for displaying the image relative to any of the plural horizontal scanning frequencies without any turbulence.

Abstract: A CRT correcting circuit comprises a correcting deflection coil excited by an alternating signal of a vertical period, a capacitor connected in parallel to the correcting deflection coil to form a resonance circuit, a first field effect transistor of a first conduction type, and a second field effect transistor of a second conduction type. The first and second field effect transistors are turned on and off simultaneously by a pulse signal of a horizontal period. The CRT correcting circuit is capable of operating at a low power consumption and has a simple circuit construction.

Abstract: In correction waveform data generating apparatus for digital convergence or digital focusing in a color television receiver, the adjustment data for all adjustment points including the region of blanking intervals is controlled from the adjustment data for a relatively small number of representative adjustment points on the image screen. Data for the representative points is automatically interpolated to generate uniform correction waveform data for the entire image screen. Basic correction waveform data is stored for each representative adjustment point and is repeatedly added to and/or subtracted from on the basis of adjustment instructions at the respective adjustment points, so that data adjustment and waveform correction are achieved.