| 摘要 |
PROBLEM TO BE SOLVED: To provide a small and inexpensive discharge lamp lighting device commonly using a filament pre-heating timer circuit pre-heating filaments of discharge lamps when turning on a power source for a certain period and a part of a protection circuit stopping the discharge lamp lighting device at the life end thereof, capable of detecting the life end of any lamp with the same detection condition as in the case all discharge lamps are mounted, even if any of a plurality of the discharge lamps is taken off. SOLUTION: The discharge lamp lighting device comprises an inverter circuit composed of a half-bridge circuit having two switching elements 2, 3 each converting a direct current supplied from a direct current power source 1 into a high-frequency current; discharge lamp load circuits L1, L2 lighting discharge lamps 6, 10 by the high-frequency current from the inverter circuit; inter-peak voltage detection circuits P1, P2 detecting voltages generated at secondary windings 5b, 9b arranged at choke coils 5, 9 of the discharge lamp load circuits l1, l2 between peaks; a pre-heating timer circuit 10 controlling currents flowing through filaments of the discharge lamps 6, 10 with the inter-peak detection voltages detected by the inter-peak voltage detection circuits P1, P2 as control voltages; and a protection circuit H1 stopping the oscillation of the switching elements 2, 3 of the inverter circuit when the inter-peak detection voltages detected by the inter-peak voltage detection circuits P1, P2 exceeds a value set in advance. COPYRIGHT: (C)2005,JPO&NCIPI |
