FIRING UNIT

PROBLEM TO BE SOLVED: To lessen loss of transistors or other parts during an interval when spark discharge is not generated at the time of starting or ending oscillation by providing a loss suppressing circuit for suppressing oscillation output on the secondary of a transformer not exceeding a voltage for enabling generation of spark discharge. SOLUTION: A loss suppressing circuit 11 comprises a circuit 12 for dividing a DC voltage VDC converted from a commercial power supply VAC through a diode D1, a resistor R3 and a transistor Q3 inserted into the ground line of a switching current control section 1, and a resistor R4 inserted into the base circuit of the transistor Q3. The loss suppressing circuit 11 controls switching of a main transistor Q1. Since a high voltage lower than the sparking voltage is not generated in the secondary winding L2 of a transformer T, generation of loss can be suppressed in the main transistor Q1 or other circuit parts and energy efficiency is enhanced.