| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply unit which can improve input current strain with a simple circuit structure, prevent generation of load current including low-frequency ripple and radiation noise, and prevent flickering of an electric-discharge lamp, especially when a load is the electric-discharge lamp. SOLUTION: A serial circuit consisting of a load circuit 1, a choke L1 and a coupling C3 is parallel-connected to both ends of an electric field effect transistor Q11, and an impedance element Z11 is connected between the contacts of the load circuit 1 and the choke L1 and the positive output terminal of a rectifier DB. A capacitor C4 is connected between the contacts of the load circuit 1 and the switching element Q11 and the positive output terminal of the rectifier DB. A diode D1 is parallel-connected to the capacitor C4, so that input current from the rectifier DB may run, without passing through the load circuit 1. |
