| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp lighting apparatus, capable of surely detecting a failure at the end of the life of a discharge lamp and securely protecting circuits, and capable of being miniaturized, at a low cost. SOLUTION: This discharge lamp lighting apparatus is comprised of a rectifying/smoothing circuit 1 for rectifying/smoothing a DC power supply, a self-exciting inverter circuit 2 including a load circuit consisting of a series circuit of two switching elements Q1 and Q2 connected between the output ends of the rectifying/smoothing circuit 1 and a current transformer CT connected to both ends of the switching element Q2, etc., a service life end detecting circuit 8 having a smoothing capacitor C5 discharged with a current generated in a secondary coil n22 of the current transformer CT and Zener diode Zd3 for monitoring the voltage at both ends of the smoothing capacitor C5, and a service life end holding circuit 7 for holding the output control condition of the inverter circuit 2, when an irregular condition is detected. |
