| 摘要 |
PURPOSE:To obtain a low power consumption driving circuit by a method wherein a constant current circuit or a source voltage control circuit which detects the duty of a driving pulse and controls a source voltage supplied to a driving transformer is provided between the electric source of the driving circuit and the driving transformer. CONSTITUTION:The collector current of a transistor(Tr) 24, i.e., the output of a constant current circuit 21, is constant. Therefore, the ON period of a Tr 7 is extended and, even if the collector current of the Tr 7 tends to be increased, the voltage drop induced by a Tr 24 is increased by the constant current circuit 21 so as to keep a current supplied to a driving transformer 8 constant and a source voltage supplied to the driving transformer 8 is reduced. Therefore, excitation energy stored in the driving transformer 8 is also reduced and a Tr 1 is never over-driven and a switching loss can be kept minimum. |
