SECULAR CHANGE CORRECTION METHOD AND CURRENT MEASURING METHOD OF MR SENSOR

摘要

PROBLEM TO BE SOLVED: To solve the problem of a drift of an MR sensor accompanying a secular change.;SOLUTION: Output of the MR sensor when magnetic field measurement is performed, is standardized based on sensor output in the MR sensor is under a specific state. In this embodiment, current is passed on an electric circuit line, magnetic field is generated, and its magnetic field is applied to the MR sensor 21. Voltage is applied to the MR sensor 21 from a constant voltage source 25 when the MR sensor 21 is reached a resistance value saturation state 24 of high resistance or low resistance. Even after changing this constant voltage source 25 to a constant current source 26, the flowing current is to be maintained so as to become the same current at the constant voltage source 25. The current value of the constant current source 26 is inverse proportion to the resistance value of the resistance value saturation state 24. Then, current of the electric circuit line 22 is turned off, and removing the magnetic field 23, the MR sensor 21 is put on detectable state only for the measuring object magnetic field. Constant current is supplied from the constant current source 26 into the MR sensor 21. The voltage of the MR sensor 21 becomes proportional to the resistance value of the MR sensor 21 standardized by a saturation resistance value.;COPYRIGHT: (C)2011,JPO&INPIT