| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the adverse effects of the hysteresis of an MI element. SOLUTION: An A.C. magnetic field including a D.C. component is impressed on an MI element 30 by a A.C. magnetic field biasing means 40. While this state is maintained, an A.C. current is passed through the MI element 30 by a drive circuit 32 for detecting the impedance of the MI element 30 by an element impedance detecting means 42. Since an A.C. magnetic field is impressed on the MI element 30 by the A.C. magnetic field biasing means 40, the impedance of the MI element 30 changes periodically. Although the periodical change of the impedance has hysteresis, since its peak value has no hysteresis, the peak value changes according to the intensity of the detected magnetic field. Then by obtaining the change of the impedance based on the detection magnetic field on the basis of the peak value, it is possible to perform magnetic field detection with the effects of hysteresis eliminated.
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