| 摘要 |
PROBLEM TO BE SOLVED: To provide a power-supply unit, a discharge lamp-lighting device, and a lighting device each having less distortion in an input current from an AC power supply, and can cope with a high input voltage even if a switching element with a low breakdown voltage is used. SOLUTION: A partial smoothing circuit S is combined with a deformed half-bridge inverter circuit INV for connecting the partial smoothing circuit S for charging so that a switching element Q2 at a low side is tuned on, a load circuit LD is connected in parallel with a switching element Q1 at a high side. The partial smoothing circuit S is charged when the switching element Q2 at the low side is turned on, current flowing to the switching element Q2 at the low side is larger than the switching element Q1 at the high side, a voltage exceeding the power supply voltage is not applied to the switching element Q2 at the low side, a voltage that is vibrated by the load-side inductance and a second capacitor Q2 of the deformed half-bridge inverter circuit INV is applied to the switching element Q1 at the high side, and a voltage that is higher than the supply voltage is applied. More specifically, the switching elements with nearly the same size can be used in the switching element Q1 at the high side and the switching element Q2 at the low one. |
