| 摘要 |
PURPOSE:To prevent the discharge current at starting time from being subjected to an under shoot thereby enabling the stable discharge starting characteristics by parallel-connecting a Zener diode to an output current detecting resistor. CONSTITUTION:A Zener diode 7 parallel-connected to an output current detecting resistor 8 to clamp down the voltage between the both ends of the resistor 8 to a voltage not exceeding a specified value. The Zener voltage of diode 7 is set at a value higher than the voltage generated at the both ends of the resistor 8 by a set output current so that the discharge current may have no undershoot during the time from the discharge start in a gas laser tube 15 to the normal discharge. Furthermore, the time in transient state is made shorter than the lag time in a comparison circuit 11 by a resistor 12 and a capacitor 13 so that the discharge current may become a stable normal discharge state without being subjected to the undershoot. Through these procedures, the stable discharge characteristics can be constantly obtained without being subjected to the under-shoot. |
