| 摘要 |
PURPOSE:To impress uniform high pressure pulses stably at the time of starting by turning on and off a switching element connected with a pulse generating winding through a capacitor with a constant phase angle. CONSTITUTION:A voltage to be impressed on a time constant circuit composed of a resistance 78 and a capacitor 79 is made constant by a series circuitry of constant voltage diodes 84, 85. Accordingly the voltage impressed on this CR circuit is always controlled constant even with changing voltage of the commercial AC mains. Thereby the on-timing of the second thyristor 80 is always controlled constant even though the supply voltage is varying, and the gate current to the first thyristor 59 passes by with turning-on of the second thyristor 80, and the first thyristor 59 is turned off with the second phase angle, Accordingly the on-period of the first thyristor 59 becomes constant regardless of change in the supply voltage, and uniform high voltage pulses can always be impressed on a discharge lamp 60 from a pulse generating winding 55, and the first thyristor 59 will not be turned off to eliminate inconvenience such that pulses are generated only in the half periods on a single side, which leads to avoidance of damage of the lamp electrode. |
