| 摘要 |
PURPOSE:To make it possible to adjust power supplied to a load without fluctuating a frequency, and lighten a discharge lamp, as a load, stably in a deep dimming state. CONSTITUTION:A set of serially connected switching elements S1 and S2 or S3 and S4 is connected to a DC power supply. An inductor L1, a capacitor C2, and a load (Z) are connected between each middle point of the switching elements S1 and S2 or S3 and S4. The switching elements S3 and S4 have an on-off timing range that is changed from the same phase to a 180-degree shifted phase with respect to a range of the switching elements S1 and S4. The concurrent on-state time of the switching elements S1 and S4 or S2 and S3 provided diagonally is changed so that the amount of power supplied to the load (Z) can be adjusted without shifting a switching frequency. Moreover, at least a switching frequency of the switching element S2 is made different than the other switching elements S1, S3, and S4 so as to supply a DC factor to the load (Z) while power with imbalance between the positive and negative is fed to a resonance circuit. Consequently, a discharge lamp, for example as a load, is prevented from going out and a flickering state with shifting strips is reduced. |
