MAGNETIC FIELD DETECTING DEVICE

摘要

PROBLEM TO BE SOLVED: To obtain a highly sensitive magnetic field detecting device of which the sensitivity is easily controlled. SOLUTION: The magnetic field detecting device uses magnetic impedance effects in which impedance varies with magnetic impedance characteristics in which impedance reduces as the size of an external magnetic field, which is a component in the direction of a detection axis, increases. A pulse current is supplied for a magnetic sensing element 10 of which the impedance varies according to an external magnetic field via an oscillating circuit 13 and a differentiating circuit 14. A voltage proportional to the impedance between the terminals of the magnetic sensing circuit is detected by a switch 15 which is turned on in synchronism with the pulse current and a signal processing circuit 16 for holding a peak. The output of the signal processing circuit 16 is compared with a predetermined level by a comparator 171.