| 摘要 |
PURPOSE: To relieve the fluctuation in DC voltage of the chopper output end by arranging a variable impedance element in a base control circuit, and changing an operational characteristic of transistors so as to increase and reduce both outputs fo a chopper circuit and an inverter circuit. CONSTITUTION: In a base control circuit 50, an input coil 511 of an oversaturation type current feedback transformer 51 is connected to a discharge lamp lighting circuit 30 corresponding to an AC load of an inverter circuit 20, and a base electric current is supplied to transistors(Tr) 14 and 21. A variable impedance element 551 composed of a variable resistance of the circuit 50 changes an operational characteristic of the (Tr) 14 and 21 so as to increase and reduce both outputs of a chopper circuit 10 and the circuit 20. When a resistance 551 is large, voltages of output coils 521 and 522 increase, and the magnetic flux of the transformer 51 suddenly increases, and early reaches a saturation level, and an ON period of the (Tr) 14 and 21 becomes short. Therefore, both outputs of the circuits 10 and 20 reduce, and voltage fluctuation is relieved. |
