Magnetic material amount detecting apparatus

摘要

A magnetic material amount detecting apparatus includes primary winding and secondary winding which are wound on a core having a reading section to which a to-be-detected medium is set close. A current is supplied to the primary winding and an output signal from the primary winding is adjusted by an A.C. current detecting section. Then, a difference between the output signal output from the primary winding and adjusted by the A.C. current detecting section and an output signal from the secondary winding is output as a signal indicating the amount of magnetic material which is present near the reading section.