Operating circuit for electric discharge lamp.

摘要

There is disclosed an operating circuit for an electric discharge lamp in which a first DC operating circuit (26) for starting an electric discharge lamp (32), a second DC operating circuit (28) for making the electric discharge lamp operative by a voltage near a rated lamp voltage and by a current near a rated lamp current, and a third DC operating circuit (30) for supplying a relatively large current to the electric discharge lamp immediately after the electric discharge lamp is started and for stabilizing the lamp luminous flux in a short time. are connected in parallel. A switching circuit (62) for cutting off the first DC operating circuit after the electric discharge lamp is started is provided atthe outputterminal of the first DC operating circuit. In addition, reverse current preventing circuits (66, 68) for preventing the currents from reversely flowing from the operating circuits at higher voltages are provided at the output terminals of the second and third DC operating circuits.