JPS57192879A - Magnetic sensor - Google Patents

Abstract

PURPOSE:To obtain a magnetic sensor which is capable of detecting accurately the direction of a signal magnetic field, by detecting the direction of the signal magnetic field based on a phase difference between a signal corresponding to an AC bias magnetic field imprssed on a magnetic resistance effect element, and an output signal. CONSTITUTION:When an AC bias magnetic field 18 is impressed on a magnetic resistance effect element 1 formed of a ferromagnetic alloy film by an AC bias magnetic field impressing means 17, output signals 20 and 22 which are free from such an offset as occurs at the time of impression of DC bias or the like and have no effect on the ununiformity of compensation resistance, and whose phases are changed in accordance with the direction of a signal magnetic field Hs being positive and negative in the direction x are generated and impressed on the pulsing circuit 14 of a phase comparator 13 via an AC amplifier 8 forming an integration circuit. Meanwhile, phase comparison between a reference pulse 19 formed by inverting the magnetic field 18 at an angle of 90 degrees in the reference pulse circuit 15 of the comparator 13 and pulses 21, 23, etc. from the circuit 14 is conducted by a phase comparator 16, and thus a magnetic sensor being capable of detecting accurately whether the signal magnetic field is in the positive or negative direction x.