Absolute encoder
To suppress deterioration in the detection accuracy of a rotation angle of a magnet even when a member located in the vicinity of the magnet is made of a magnetic material. An absolute encoder includes a first sub-shaft gear configured to rotate based on rotation of a main shaft, a bearing part configured to rotatably support the first sub-shaft gear around an axial line A, a support shaft configured to support the bearing part, and a spacer provided between the first sub-shaft gear and the bearing part. At least a part of the spacer is formed of a magnetic material, and the spacer is formed extending in a direction intersecting the axial line A.
1 . An absolute encoder comprising:
a sub-shaft gear configured to rotate based on rotation of a main shaft;
a bearing part configured to rotatably support the sub-shaft gear around an axial line;
a shaft part configured to support the bearing part; and
a spacer provided between the sub-shaft gear and the bearing part, wherein
at least a part of the spacer is formed of a magnetic material, and
the spacer is formed extending in a direction intersecting the axial line.
2 . The absolute encoder according to claim 1 , wherein
the spacer includes a plate-shaped part and a ring part,
the plate-shaped part is a portion extending along a plane and has a pair of surfaces, and
the ring part is an annular portion and protrudes from one of the pair of surfaces of the plate-shaped part.
3 . The absolute encoder according to claim 2 , wherein
the ring part and the plate-shaped part are integrated with each other, and
the spacer is formed of the magnetic material.
4 . The absolute encoder according to claim 2 , wherein
the ring part and the plate-shaped part are separate from each other, and
the plate-shaped part is formed of the magnetic material.
5 . The absolute encoder according to claim 2 , wherein
the plate-shaped part is formed covering the bearing part in the axial direction.
6 . The absolute encoder according to claim 1 , wherein
the bearing part includes at least one bearing,
the bearing has an outer ring and an inner ring,
the outer ring of the bearing is fixed to the sub-shaft gear,
the inner ring of the bearing is fixed to the shaft part, and
the spacer is sandwiched between the sub-shaft gear and the outer ring of the bearing in the axial direction.
7 . The absolute encoder according to claim 1 , wherein
the sub-shaft gear includes an accommodating part forming a space capable of accommodating the spacer and the bearing part, and
the bearing part is configured to be fitted into the accommodating part.