Patent ID: 7994749

Claim:
A multiple-rotation absolute-value encoder of a geared motor wherein an output rotation of a motor shaft is reduced and taken off from a gear shaft and a load side device is driven in an operating range corresponding to multiple rotations of the gear shaft, the multiple-rotation absolute-value encoder characterized in comprising: a gear shaft absolute-value encoder having a first two-pole magnet attached to the gear shaft and a first magnetic sensor for detecting a change in a rotating magnetic field from the first two-pole magnet; a reduction mechanism for reducing the rotational speed of the gear shaft; and a load side absolute-value encoder having a second two-pole magnet attached to a reduced-rate output shaft of the reduction mechanism and a second magnetic sensor for detecting a change in a rotating magnetic field from the second two-pole magnet; wherein a reduction ratio of the reduction mechanism is set so that the second two-pole magnet rotates in a range of one rotation or less in the operating range of the load side device.