| 摘要 |
PURPOSE:To make the aspect ratio of a screen constant regardless of a change in the brightness by detecting a change in a high voltage current of a picture tube with a DC current flowing to a horizontal deflection circuit and feeding back the detected change to a discharge path of a capacitor of a vertical deflec tion circuit. CONSTITUTION:A loop is formed from a DC power supply E to a reference potential point via a primary winding of a flyback transformer T2, a transistor (TR) Q1 or a damper diode D1, a diode D2 and a resistor R4 and a DC load current IDC flows from the DC power supply E. A voltage drop is generated across the resistor R4 by the DC load current IDC. A voltage changing in a same direction as a change in a high voltage current is obtained from the resis tor R4 and given to a discharge path of an integration capacitor C1 to change the vertical deflection current reversely to a change in the high voltage current, thereby reducing the fluctuation of the horizontal amplitude due to the vertical amplitude. Thus, the vertical amplitude is made almost constant similarly to the horizontal amplitude to obtain a constant aspect ratio regardless of the brightness. |
