DISCHARGE LAMP LIGHTING DEVICE AND ON-VEHICLE HEADLIGHT LIGHTING DEVICE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To keep a positive lighting state in the case that a supplied voltage to a discharge lamp lighting device is suddenly decreased. SOLUTION: In the case of a normal lighting state in which a discharge lamp DL is not turned off, the ON duty of a switching element Q0 is made variable by a calculation unit 53 in such a way that outputs of lamp state detecting units 51, 52 may be received and appropriate electrical power may be fed to the discharge lamp DL. There is provided an input voltage detecting unit 57 for use in detecting an input voltage Vin of a DC/DC converter 2. In the case that a decreased amount of the input voltage Vin of the DC/DC converter 2 is higher than a predetermined value during the lighting of the discharge lamp DL, the ON duty of the switching element Q0 is forcedly corrected in its expanding direction for a predetermined time T1 without performing any calculation processing at a calculating unit 53 before the discharge lamp DL is turned off. Alternatively, polarity reversals at a square wave inverter 3 are stopped and a DC lighting is kept for a predetermined time T1. COPYRIGHT: (C)2011,JPO&INPIT