| 摘要 |
A compact magnetic detection device with a high sensitivity. The device includes a single bias magnet producing a magnetic field to a gear having a magnetic substance, and a magnetoresistive effect element. The element is arranged so as to oppose the bias magnet and adjoin a pole face of the magnet on the gear's side. Further, the element is arranged in a plane substantially perpendicular to a moving direction of the gear, for producing resistance change caused by changes of magnetic field in response to the movement of the gear. Thus, the bias magnetic field existing in the moving direction of the gear is modulated to the direction facing the gear. Since a magnitude of modulation against the bias magnetic field amounts to a maximum in the vicinity of the pole face of the bias magnet on the gear's side, it is possible to realize the high sensitivity and furthermore, the magnetic detection device can be miniaturized by use of the single magnet.
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