| 摘要 |
PURPOSE:To improve the sharpness of a picture, by controlling a modulation factor at peripheral parts on both sides larger than that at the center part of a picture plane, and enhancing a contour correction function by setting high beam scan speed at the peripheral part. CONSTITUTION:A video signal V is inputted, and a signal (a) in which the video signal is differentiated 2 for two times, is amplified 3. Meanwhile, a parabolic waveform voltage (b) in which a horizontal deflecting sawtooth waveform voltage is integrated, is inputted from a terminal 4, and a voltage VL is generated by overlapping the voltage on the lower limit voltage of an amplitude limitating voltage, and a VH is generated by overlapping an inverted parabolic waveform voltage on the lower limit voltage, then the amplitude of an inputted signal (a) is limited by the VL and the VH. A parabolic waveform differentiation signal is amplified 6, then it is supplied to a scan speed modulating coil 7, and the contour correction function is enhanced by setting a large coil current at a position where a steep change in a differentiation signal (c) is generated at the periphery of the picture plane, and the light spot shape of a beam is made approach to a real circle, thereby, the picture with a sharp contour can be formed.
|
