Patent ID: 9709424
Date: 2017-07-18
CPC Classifications: G01D

Claim:
1. An inductive detection type rotary encoder comprising: a stator; a rotor provided opposite the stator so as to be rotatable around a rotation axis; a first transmission winding provided in the stator, the first transmission winding having a first radius centered on the rotation axis; a second transmission winding provided in the stator, the second transmission winding having a second radius centered on the rotation axis; a first reception winding provided in the stator, the first reception winding being formed within a first region, the first region having a ring shape centered on the rotation axis, the first reception winding having a first inside radius and a first outside radius centered on the rotation axis; a second reception winding provided in the stator, the second reception winding being formed within a second region, the second region having a ring shape centered on the rotation axis, the first and second reception windings being formed with a first insulating layer therebetween, the second reception winding having a second inside radius and a second outside radius centered on the rotation axis; a first magnetic flux coupling body provided in the rotor, the first magnetic flux coupling body being formed within a third region, the third region being a ring-shaped region centered on the rotation axis and overlapping the first region in an axial direction along the rotation axis, the first magnetic flux coupling body having a third inside radius and a third outside radius centered on the rotation axis; and a second magnetic flux coupling body provided in the rotor, the second magnetic flux coupling body being formed within a fourth region, the fourth region being a ring-shaped region centered on the rotation axis and overlapping the second region in the axial direction, the first and second magnetic flux coupling bodies being formed with a second insulating layer therebetween, the second magnetic flux coupling body having a fourth inside radius and a fourth outside radius centered on the rotation axis, wherein the second region, the first region, the third region, and the fourth region are disposed in this order in the axial direction, a shortest distance between the first transmission winding and the first magnetic flux coupling body is shorter than a shortest distance between the second transmission winding and the first magnetic flux coupling body, a shortest distance between the second transmission winding and the second magnetic flux coupling body is shorter than a shortest distance between the first transmission winding and the second magnetic flux coupling body, the shortest distance between the first transmission winding and the first magnetic flux coupling body is shorter than the shortest distance between the first transmission winding and the second magnetic flux coupling body, and the shortest distance between the second transmission winding and the second magnetic flux coupling body is shorter than the shortest distance between the second transmission winding and the first magnetic flux coupling body.