High-pressure discharge lamp ballast with rapid lamp restart circuit

Abstract

An electronic ballast is provided for quickly restarting a high-pressure discharge lamp after shutdown. The ballast includes a power supply circuit for supplying power to the lamp from a commercial power source, a start voltage generation circuit for supplying a starting high voltage to the lamp and a control circuit for controlling the power supply circuit and the start voltage generation circuit. A lighting transition module detects a startup or shutdown of the lamp. A lighting time count module measures a lighting time of the lamp when startup is detected. A comparison module compares the lighting time and a first reference time when shutdown is detected. A delay time setting module sets a predetermined delay time of the start voltage generation circuit based on the comparison result. Operation of the ballast is halted from a startup trigger until lapse of the delay time, and then the high starting voltage is supplied to the lamp.