| 摘要 |
PROBLEM TO BE SOLVED: To normally detect a magnetic field from a transmitting magnet without glitch due to the effect of terrestrial magnetism even if the magnitude of the magnetic field transmitted from the transmitting magnet embedded in a rotor to an amorphous sensor becomes small. SOLUTION: The invention is for detecting the magnetic field from the transmitting magnetism embedded in the end surface of the rotor rotating in proportion to the flow rate of measuring fluid by using the amorphous sensor, and comprises a coil for an external magnetic field canceling which is put in the vicinity of the amorphous sensor, a magnetic sensor arranged in the vicinity of the amorphous sensor for detecting the external direct current magnetic field in the same direction as the amorphous sensor, and a controller for controlling the current sending to the coil for external magnetic field canceling for canceling the external direct current magnetic field detected with the magnetic sensor. The external direct current magnetic field affecting to the amorphous sensor is canceled by the magnetic field generated by the coil for external magnetic field canceling. COPYRIGHT: (C)2006,JPO&NCIPI
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