Patent ID: 8159215

Claim:
An induction detecting rotary encoder comprising: a stator; a first rotor engaged with a rotating shaft, rotated along with the rotating shaft, and provided axially opposite to the stator; a second rotor provided on an external periphery side of the first rotor, rotatable with respect to the first rotor, and axially opposite to the stator; a rotation transferer transferring rotation of the rotating shaft and rotating the second rotor at a speed different from the first rotor; a first transmitting winding, a second transmitting winding, and a third transmitting winding provided in order from inside concentrically to the rotating shaft, on a surface opposite to the first rotor and the second rotor of the stator; a first receiving winding, a second receiving winding, and a third receiving winding provided in order from inside concentrically to the rotating shaft, on the surface opposite to the first rotor and the second rotor of the stator, and associated with the first transmitting winding, the second transmitting winding, and the third transmitting winding; a first flux coupling body and a second flux coupling body provided in order from inside concentrically to the rotating shaft, on the surface opposite to the stator of the first rotor, the first flux coupling body flux-coupling with the first transmitting winding and the first receiving winding, the second flux coupling body flux-coupling with the second transmitting winding and the second receiving winding; and a third flux coupling body provided external to the first flux coupling body and the second flux coupling body concentrically to the rotating shaft, on the surface opposite to the stator of the second rotor, and flux-coupling with the third transmitting winding and the third receiving winding; wherein the first transmitting winding, the first receiving winding, and the first flux coupling body constitute a first angle detection track generating a cyclic change for N 1 times per single rotation of the first rotor; the second transmitting winding, the second receiving winding, and the second flux coupling body constitute a second angle detection track generating a cyclic change for N 2 times per single rotation of the first rotor; the third transmitting winding, the third receiving winding, and the third flux coupling body constitute a third angle detection track generating a cyclic change for N 3 times per single rotation of the second rotor; N 1 , N 2 , and N 3 are different from one another; and N 3 is less than N 1 and N 2 .