Multirotation type encoder

摘要

There is provided a multirotation type encoder which is small-sized, having nomechanical contact portion other than a bearing, having high reliability and long life and dispensing with interchange of a battery. A multirotation type encoder of the invention includes a first encoder 20 attached to a rotating shaft 11 of a rotating machine 10 for detecting an absolute value rotational angle within one rotation, and a second encoder for counting a multirotation amount of the rotating shaft 11 by using a speed reducing mechanism 30 by magnetic coupling and the second encoder 40 is constituted by a first magnetic gear 31 directly connected to the rotating shaft and magnetized in multiple poles and at least one second magnetic gear 32 arranged to be opposed thereto in noncontact and magnetized in multiple poles by a number of magnetic poles larger than that of the first magnetic gear 31 and is constituted to count a multirotation amount by detecting a rotational angle of the second magnetic gear by the second encoder.