| 摘要 |
PROBLEM TO BE SOLVED: To provide a means for easily measuring the direction and strength of a magnetic field for each frequency of an AC external magnetic field only by one magnetic sensor and one frequency filter. SOLUTION: In an AC magnetic field detection display, a coil, a magnetic sensor, and a control circuit and mounted to a disc-like or spherical coil assembly, the coil assembly is supported so that it can be rotated at low torque in an arbitrary three-dimensional direction, a current corresponding to the output of the magnetic sensor is supplied from the control circuit to the coil, and the axis of the coil is directed toward the external magnetic field due to the interaction between the magnetic field being generated by the current and the external magnetic field. Additionally, in the control circuit, an amplifier for amplifying the output of the magnetic sensor, a filter for taking out a specific frequency component being outputted by the amplifier, and a drive circuit for supplying an AC current having the same frequency and phase as the output of the filter are arranged. Then, the direction of the specific frequency component selected by the filter in the AC external magnetic field is directed by the axis of the coil. COPYRIGHT: (C)2004,JPO
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