| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp circuit device which can detect an emitterless state that an emitter filled in an electrode of a discharge lamp has been worn with good precision. SOLUTION: A rectifier circuit Rx is connected to an ac power supply AC to form dc voltage VDC, and the voltage is supplied to switches Sa, Sb connected between terminals A, B. The switches Sa, Sb are alternately on-off controlled by signals from a control part Cnt to apply high-frequency voltage to a discharge lamp Lx. A reversing capacitor Cd is connected to the discharge lamp Lx in series. The wear of an emitter filled in an electrode is detected by an emitterless detecting circuit Y. A non-load state that the discharge lamp Lx has been troubled is detected by a non-load detecting circuit Xa. A delay capacitor Cf is connected to an input side of a non-load detecting diode Dc to delay lowering of voltage applied to the diode Dc, thereby normally operating the emitterless detecting circuit Y. |
