PROBLEM TO BE SOLVED: To prevent the uneven magnetization of a transformer without using a center tap capacitor to miniaturize a device, in a lighting device of a lamp having an inverter of a full bridge structure.;SOLUTION: A fifth switching element Z5 is mounted between a rectifying circuit 3 and a smoothing circuit 4 on the secondary side of a transformer Tr, and the switching element Z5 is turned off during a dead time period for turning off all switching elements Z1, Z4, Z2 and Z3. Thereby, the secondary side of the transformer Tr is opened and a voltage is generated across primary-side terminals of the transformer Tr in a direction for negating remaining magnetic flux. Thereby, even when the ON-time of one-side switching element is extended, the transformer Tr is prevented from being unevenly magnetized. By mounting a diode D5 on the input side of the secondary-side rectifying circuit 3, a current from a coil L1 of the secondary-side smoothing circuit 4 is supplied to a lamp 5 through the diode D5 while the switching element Z5 is at the OFF state.;COPYRIGHT: (C)2006,JPO&NCIPI
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