DISCHARGE LAMP LIGHTING DEVICE

摘要

PURPOSE:To provide a discharge lamp lighting device of preheat start type, which can work without impairing the starting performance of a voltage drive swithching element while the oscillation frequency at the time of lamp preheating is well secured. CONSTITUTION:A discharge lamp lighting device is equipped with an inverter circuit 1 of self-exciting half bridge type in which the load current is sensed by a sensing winding 5 of a saturable current transformer 4 and the output is controlled upon feeding a control signal to the control terminals of a pair of voltage drive switching elements 2, 3 on the high voltage and the low voltage sides by the output windings 12, 14 of the current transformer 4 in accordance with the sensed load current. An impedance element 20 to determine the oscillative frequency of the inverter circuit 1 when the preheat current is fed to a preheating capacitor 9 which is connected between the filaments of this discharge lamp 8 is connected with the drive circuit 10 for that of the switching elements 2 which is situated on the high voltage side. The other switching element 3 on the low voltage side which precedes at the time of starting, is trigger started certainly.