Positions-Erkennungseinrichtung des magnetischen Erkennungstyps

摘要

Disclosed is a position detecting device of magnetic detection type capable of accurate position detection. The device comprises a magnet (1) consisting of an N-pole part (1a) and an S-pole part (1b), a back yoke (2) formed with upstanding projections (2a, 2b) extending up to the surface level of the N-pole part (1a) of the magnet (1), the S-pole part (1b) of the magnet (1) being bonded to the central area of the back yoke (2), and a Hall IC (4) located to make parallel movement relative to both the exposed upper surface of the N-pole part (1a) of the magnet (1) and the upper end surfaces of the projections (2a, 2b) of the back yoke (2) in slightly spaced apart relation. When the Hall IC (4) moves above narrow spaces (3a, 3b), which are defined between the magnet (1) and the projections (2a, 2b) of the back yoke (2) and in each of which the magnetic flux density is zero (the neutral zone between the N pole and the S pole), the threshold of the Hall IC (4) is crossed by the magnetic flux density curve in each of these narrow spaces (3a, 3b), so that the position can be detected without any substantial error.