Magnetic position detecting device

摘要

To provide a magnetic position detecting device which is capable of extremely accurately detecting a reference position. In a magnetic position detecting device for detecting a position of a moving body 2 to a fixed body 1 on the basis of a change of a magnetic flux density that a Hall element 4 senses when the moving body 2 provided with a magnet 6 and the fixed body 1 provided with the Hall element 4 move relatively to each other. An S-pole and an N-pole of the magnet 6 are juxtaposed along a direction in which the magnet 6 and the Hall element 4 move relatively to each other. When the Hall element 4 passes a boundary position between the S-pole and the N-pole of the magnet 6, a magnetic flux density that the Hall element 4 senses is zero. The polarities of the magnetic field are completely inverted. Therefore, a variation of the position where the magnetic flux density sensed by the Hall element 4 is zero is completely eliminated. Only during a fixed period that the magnet 6 and the Hall element 4 mutually approach, a detect signal which depends on a magnetic flux density sensed by the Hall element 4 is compared with a reference signal. By detecting a position where both the signals are equal in level, a reference position is considerably accurately detected.