| 摘要 |
PURPOSE:To improve the deflection distortion on an upper part of a screen due to high voltage fluctuation when a bright video image is displayed to the upper part of the screen in the high voltage generating circuit. CONSTITUTION:A high voltage driving circuit 2 converts a voltage into a current and a high voltage output circuit outputs a collector pulse. A flyback transformer 4 boosts a collector pulse and outputs a high voltage EHT. A high voltage detection circuit 5 detects the high voltage EHT and a voltage control circuit 6 controls a high voltage power supply voltage HV.Vcc in response to an output of the high voltage detection circuit 5 and gives the voltage to a primary winding 4a of the flyback transformer 4 to make the high voltage EHT constant. The deflection distortion at the upper part of the screen due to the fluctuation of the high voltage EHT is improved by keeping the input voltage Vc of the primary winding 4a to be a prescribed voltage between an input voltage Vc for a fully black level and an input voltage Vc for a fully white level only for the vertical blanking period. |
