摘要 |
PROBLEM TO BE SOLVED: To stably operate a lighting device by providing a direct current power source, a power source voltage detecting means, a step-up chopper, at least two step-up voltage detecting means, a step-up voltage detecting means switching means, a step-up chopper output voltage control means, and a load circuit including at least an inductance element and for stably lighting a high- pressure discharge lamp. SOLUTION: A step-up chopper 3 for high-pressure discharge lamp DL lighting device includes an inductance element L1, a rectifying circuit 2, a capacitor element C1 and a switching element Q0, and raises the input voltage to the predetermined voltage with control of the switch, and outputs it. A power source voltage detecting means 21 detects voltage, and in the case where the power source voltage is less than the predetermined value, a transistor Q1 of a step-up voltage detecting means 31 is turned on, and a short-circuit is formed in a potential dividing resistor R23. In the case where the power source voltage is higher than the predetermined value, the transistor Q1 is turned off, and a control IC controls the operation of the switching element Q0, and raises the voltage to the predetermined voltage. |