| 摘要 |
PURPOSE:To prevent increase in a high voltage, to enhance the reliability and to improve the focus performance by extracting a charge of an output capacity of a high voltage stable circuit momentarily. CONSTITUTION:A change in a beam current is detected by a beam current detection circuit 9 from a low voltage terminal at a secondary side of a flyback transformer of a high voltage circuit and a switching pulse generating circuit 10 generates a signal pulse for switching. Moreover, a high voltage fluctuation detection section 12 detects a voltage fluctuation from a high voltage terminal at the secondary side of the flyback transformer and a control section 13 controls a power voltage to make the high output voltage stable. A switching circuit 11 rapidly extracts the charge in the output capacitor 45 of a high voltage stabilizing circuit 14 by using a pulse from the circuit 10 to decrease the power voltage momentarily. |
