| 摘要 |
PURPOSE:To improve lighting probability by interrupting the charge loop from a power source to a capacitor for a determined time after a thyristor for forming the discharge loop receives no gate pulse. CONSTITUTION:The gate pulse from a gate pulse generating circuit PG is generated, and a thyristor 10 is on to start discharge. Simultaneously, an interruption signal generating circuit SG also generates an interruption signal, and a transistor TR is off to interrupt a discharge loop. After a determined time after the discharge is ended and the gate pulse is built up, the interruption signal of the circuit SG is built up, and the TR is on. Thus, the current carried from a battery B to the thyristor 10 through a current limiting resistance R is interrupted, the current of the thyristor 10 is reduced to less than a holding current, and the thyristor 10 is certainly off. Thus, a high frequency voltage is certainly generated on the secondary side coil of a trigger transformer T, and the lighting probability of a metal halide lamp K is improved. The constitution as interrupting the discharge loop may be used. |
