| 摘要 |
PURPOSE:To prevent a horizontal AFC circuit from operating abnormally by comparing output voltages of plural power circuits by a comparator and controlling the operation of the AFC circuit according to the comparison output. CONSTITUTION:When the output voltage of the 2nd power circuit 8 of a synchronous separating circuit 11 is low, the horizontal AFC circuit 2 is inhibited from operating and when a specific value is reached, the inhibition is reset. The 1st power circuit 1 supplies electric power to the circuit 2 and the circuit 8 smooths and supplies horizontal fly-back pulses to the circuit 11. When the output voltage of the circuit 8 rises, a reference voltage Vref2 exceeds a 1st reference voltage Vref1 and a switch 24 is closed. When the output voltage of the circuit 8 rises, the charging of a capacitor 14 ends and only a normal horizontal synchronizing signal is generated and applied to a phase comparator 21. In this state, the comparator 21 is released from being inhibited from operating, so the circuit 2 is prevented from operating abnormally when powered ON. |
