| 摘要 |
PURPOSE:To measure precisely irrespective of the size of local magnetic field, by forming magnetic field detection points of plural positions with a plurality of magnetic field detectors, determining the position and size of the magnetic dipole equivalent to the local magnetic field generating body due to the difference in the output signals, and erasing the local magnetic field components. CONSTITUTION:Magnetic field detectors a'', a' are provided at positions 18, 19 at the spacing of + or -1/2DELTAZ respectively from position 3 of a magnetic field detecting point (a), for instance, with respect to X-axis. These magnetic field detectors a'', a' are intended to obtain an output propotional to the X-direction component of the magnetic field vector at each position. Thus disposing the detectors, from the sum of the output signals of both detectors, the magnetic field vector at point (a) is obtained, and also from the differential signal and size of DELTAZ, the differential coefficient in the Z-axis direction of the magnetic field at point (a) is determined. From this differential coefficient, the size of the X-direction magnetic field due to equivalent magnetic pole is determined, and the uniform magnetic field component is obtained by subtracting the local magnetic field component. The Y-direction component and Z-direction component of the magnetic field may be obtained in the same manner. |
