CHARGING CIRCUIT, AND ELECTRONIC BALLAST FOR FLUORESCENT LAMP

摘要

PURPOSE: To provide a charging circuit for reducing the wasteful consumption of a power and a ballast for momentarily lighting a fluorescent lamp by performing a switching control so as to stop the supply of applied voltage to a charger after the charger reaches a prescribed voltage. CONSTITUTION: An electronic ballast has a charging circuit 40. The voltage outputted from a rectifying circuit 20 is supplied to the charging circuit 40 through a rush current preventing circuit 30. The circuit 40 performs the charging until the voltage of a capacitor C6 as the charger of a power-factor converting circuit 50 reaches a prescribed voltage. When the capacitor C6 is charged and reaches the prescribed voltage, a switching control part 42 in the circuit 40 operates a switching part 41 to stop the supply of applied voltage to C6. Thus, the charger can be thus charged to a stable prescribed voltage at high speed, and the wasteful consumption of power can be reduced. A ballast using this charging circuit can drive the power-factor converting circuit at high speed to stably and quickly light a fluorescent lamp.