Patent ID: 9234771
Filing Date: 2016-01-12
CPC Classification: G01D

Claim Text:
1. A rotary encoder, comprising: a stator; a first rotor affixed to a rotation shaft and rotatable with the rotation shaft, the first rotor opposing the stator in an axial direction of the shaft; a second rotor positioned about an external circumference of the first rotor and rotatable relative to the first rotor, the second rotor opposing the stator in the axial direction; a rotation transmitter configured to rotate the rotation shaft; a gear configured to rotate the second rotor at a different speed than the first rotor; each of first and second angle detectors being coaxially positioned about the rotation shaft on a surface of the stator opposing the first rotor and on a surface of the first rotor opposing the stator, wherein the first angle detector is radially inside of the second angle detector; and each of third and fourth angle detectors coaxially positioned about the rotation shaft on a surface of the stator opposing the second rotor and on a surface of the second rotor opposing the stator, wherein the third angle detector is entirely radially inside of the fourth angle detector, wherein: each of the first, second, third, and fourth angle detectors comprises a flux coupling winding with a plurality of protrusions and recesses; the first angle detector detects, at a reference position, N the second angle detector detects, at a reference position, N the third angle detector detects, at a reference position, N the fourth angle detector detects, at a reference position, N N N