| 摘要 |
PURPOSE:To detect an absolute position with a high reliability, by changing the length of a closed magnetic path to which a prescribed magnetomotive force has been applied, varying the quantity of a magnetic flux of this magnetic path, and detecting its magnetic flux or a leakage of the magnetic flux. CONSTITUTION:To a closed magnetic path 1 which has been constituted so as to have a parallel part by a magnetic material, a magnetomotive force is applied by a permanent magnet which has been installed to a main spindle 3 provided so as to be slidable in parallel to the longitudinal direction of this closed magnetic path 1. In this state, by the length of a magnetic path formed by the permanent magnet 4 and a detector 2, and a magnetic path formed by the permanent magnet 4 and a detector 2', and output V2 of the detector 2 and an output V'2 of the detector 2' are varied, and as the permanent magnet is separated from the center, a difference of the outputs of both of them becomes large. Accordingly, by detecting a relation as to whether the outputs of these two detectors 2, 2' are large or small and a difference of the outputs, in which position the permanent magnet exists can be known.
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