METHOD FOR SENSING MAGNETISM AND DEVICE THEREOF

摘要

A method for sensing magnetism, in which a low-pass filter (107) extracts low frequency signal components in the output signal (106) of a magnetic sensor (104) which senses the leakage magnetic flux caused by the magnetically abnormal part of a body (101) to be inspected that moves in a magnetic field. The extracted low frequency signal components are amplified and applied to a compensating coil (111). By the magnetic flux induced by the applied components in the compensating coil, a stray magnetic flux crossing the magnetic sensor (104) is canceled. A device for sensing magnetism comprises the low-pass filter (107) for extracting low frequency signal components in the output signal (106) of the magnetic sensor (104) which senses the leakage magnetic flux caused by the magnetically abnormal part of the body (101) to be inspected that moves in the magnetic field, an amplifier (110) for amplifying the low frequency signal component extracted by the low-pass filter (107), and the compensating coil (111) which is excited by the output signal of the amplifier (110) and induces a magnetic flux for canceling the stray magnetic flux produced by the body (101) and crossing the magnetic sensor (104).