DISCHARGE LAMP LIGHTING DEVICE

摘要

PROBLEM TO BE SOLVED: To avoid an excessive spike voltage or resonance voltage due to transient in operation until the filter capacitor voltage reaches the preset voltage. SOLUTION: This discharge lamp lighting device has a control circuit 10 in which DC voltage obtained by rectifying AC power source Vin with a rectifier 1 is fed to the connection point of a first and a second switching element Q1 and Q2 connected in series in the same direction and each with a first and a second diode connected in parallel inversely via inductance 2 and the third diode 3. Also, a filter capacitor 4 is connected in parallel to the end of the first switching element Q1 and a discharge lamp 8 is connected via a resonance circuit from the connection point of the first and the second switching elements Q1 and Q2 to a capacitor 5, a coil 6 and another capacitor 7. The first and the second switching elements Q1 and Q2 are alternately turned on and off, and the second switching element Q2 is turned off when voltage across a resistor 9 connected in series to the second switching element Q2 for overcurrent detection reaches the preset voltage. And the first switching element Q1 is turned on. The discharge lamp 8 is released until the voltage of the filter capacitor 4 reaches the preset voltage after turning on the AC power source Vin.