| 摘要 |
PURPOSE:To prevent the generation of an upper curvature on a longitudinal line caused by a phase lag in a vertical parabolic wave in the raster distortion correcting circuit utilized in a variable scanning type display device. CONSTITUTION:A DC/DC converter 2 changes a DC power source voltage age Vcc into a voltage VccA corresponding to a horizontal deflection frequency. The voltage VccA is converted to a voltage VccB modulated by the vertical parabolic wave by means of an integrating circuit 4, a DC driving circuit 5, a driving circuit 6 of a DC with superposed parabolic wave, an output circuit 7 of a DC with superposed parabolic wave and a parabolic wave modulating circuit 8 and the voltage VccB is supplied to a horizontal deflection output circuit 9. A horizontal deflection oscillating circuit 11 and a horizontal deflection driving circuit 10 supply a horizontal output pulse to the horizontal deflection output circuit 9. Since a controller 15 makes the integration circuit 4 open after a prescribed time from the turning on of an AC power supply voltage, no phase lag in the vertical parabolic wave is present even if the vertical parabolic wave is fedback and a lateral pincushion distorsion is precisely corrected. |
