PURPOSE: To stabilize electric power supply to a heater and eliminate a choke coll by specifying a degree of coupling between an input winding and an auxiliary power supply, between an anode winding and a heater winding, between the input winding and the anode winding and between the input winding and the heater winding, respectively in a transformer.
CONSTITUTION: A degree of coupling is taken at 0.9 or more between the input winding of a transformer 5 and the winding of an auxiliary power supply for a control circuit 2 and the like to drive a switching element 3, and between an anode winding and a heater winding, respectively. Also, a degree of coupling is taken at 0.7 or below between the input winding and the anode winding, and between the input winding and the heater winding, respectively. More concretely, a two-leg core is used as the magnetic core of the transformer 5. And the input winding and the auxiliary power supply winding are applied to one of the two legs, and the anode winding and the heater winding are applied to the other leg. Or an E-E core is used and the intermediate leg of one E-core is applied with the input winding and the auxiliary power supply winding, while the anode winding and the heater winding are applied to the intermediate leg of the other E-core. In this case, leak inductance due to rough coupling is used as a substitute for a choke coll, thereby enabling the elimination of the choke coil.
ISHIYAMA KUNIO
NOGUCHI SHOICHI
HITACHI DEVICE ENG
HITACHI NISSHIN ELECTRON KK
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