| 摘要 |
PURPOSE:To obtain a high preciseness encoder apparatus, by opposing a ferromagnetic material having a detection coil wound therearound to a rotary member having permanent magnets arranged to the periphery thereof at equal intervals. CONSTITUTION:By winding detection coils 51-55 around ferromagnetic materials 31-35 rapidly changing in magnetizing intensity by the increase and decrease in an external magnetic field, high induced electromotive force is obtained in the detection coils at the time of the increase and decrease in a magnetic field. When a rotary member 8 having permanent magnets 9 arranged to the periphery thereof is rotated, large impulse like induced voltage can be obtained in the detection coils wound around the ferromagnetic materials without supplying power and the discrimination of a rotary direction and the counting of a rotary pulse are performed on the basis of the outputs of a plurality of the detection coils by an electronic circuit electronically energized by a battery to make it possible to detect the position of a rotary member even at the time of power failure.
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