DISCHARGE LAMP FLASHING CONTROL SYSTEM

摘要

PURPOSE:To reduce power consumption while preventing early deterioration of filaments by minimizing filament power loss in a discharge lamp flashing control system suitable for facsimile equipment. CONSTITUTION:Filaments of a discharge lamp FL are pre-heated for standby by pre-heating coils N3 and N5 of an output transformer T in an inverter, while a lighting coil N4 is connected to both ends of the lamp FL through a two-way three- terminal thyristor THR1 acting as a first switching element in such a manner that a flashing control circuit 4 allows a thyristor THR1 to control the flashing of the lamp FL. In a system of this type, the inverter is provided with a pre-heating current limiting circuit 1. With the on-or-off action of a transistor Q3, the circuit 1 allows a resistor R3 in a feed back circuit of the inverter to be short-circuited or opened so that current for pre-heating the filaments of the lamp FL can be limited when the lamp FL is pre-heated in standby and the circuit 4 can be actuated at a delayed time by a delay circuit 2 to turn the thyristor THR1 on when the lamp FL comes on.