| 摘要 |
PURPOSE:To easily adjust a bias voltage by providing an exciting coil, detection coils, a compensating coil, variable resistances, etc. CONSTITUTION:The exciting coil 2 is wound around an exciting core 7 having high magnetic permeability to control the distribution of a magnetic field. Further, detection coils 3a and 3b are arranged in a couple at both ends of the coil 2 and the relative positions of a beltlike magnetic body and a magnetic sensor are known from the outputs of the coils 3a and 3b. Then, the compensating coil 4 for bias voltage control is wound around the exciting core 7 coaxially with the exciting coil 2. Further, the output of the coil 4 is voltage-divided by variable resistances 5a and 5b and the differences between the outputs of the coils 3a and 3b are detected by voltage detectors 6a and 6b. Thus, the variable resistances 5a and 5b are only adjusted to easily adjust a bias voltage.
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