| 摘要 |
PURPOSE:To get a stable detection signal without amplitude fluctuation, by providing an auxiliary magnet for correction of detection signal in the vicinity of a magnetic detector, and detecting mainly the change of the magnetic field being the target of detection. CONSTITUTION:For the detector 30 of a motor 3, an auxiliary magnet 31 for correction of a detection signal, where N and S poles are made in parallel with the rotating shaft 6, is interposed between the FG magnet 11 provided at the periphery of a rotating yoke 8 and the magnetic resistor 13 arranged in opposition to the magnetization face 11A. The magnetic field of the auxiliary magnet 31 saturates the magnetic field around the magnetic resistor 13, whereby even if the magnetic field changes due to the rotation of a rotor 10, the magnetic resistor 13 is made not to detect this. This way, it can mainly detect only the change of the magnetic field by a magnetized pattern 11, and reduce the amplitude fluctuation of the detection signal. Furthermore, the accuracy in mounting the magnetic resistor 13 can be lightened, and also, by omitting the inspection for the amplitude change of the detection signal, the manufacturing process can be simplified. |
