US Patent No. 9,360,494

ROTATION DETECTOR AND METHOD OF PRODUCING A ROTOR IN THE ROTATION DETECTOR


Patent No. 9,360,494
Issue Date June 07, 2016
Title Rotation Detector And Method Of Producing A Rotor In The Rotation Detector
Inventorship Shunichi Odaka, Yamanashi (JP)
Assignee FANUC CORPORATION, Yamanashi (JP)

Claim of US Patent No. 9,360,494

1. A rotation detector including a rotor, a magnetic field generator fixed to face said rotor and generates a magnetic field,
and a detector unit arranged between said rotor and said magnetic field generator to detect signals that vary responsive to
changes in said magnetic field caused the rotation of said rotor; wherein
said rotor includes a first cylindrical portion having one or a plurality of steps, and a second cylindrical portion having
one or a plurality of steps and arranged concentrically with said first cylindrical portion and being deviated in the axial
direction; and

said second cylindrical portion includes a first partial circumferential surface having a width narrower than that of said
first cylindrical portion in the circumferential direction, and a second partial circumferential surface having a radius smaller
than a radius of said first partial circumferential surface;

said rotor, further, including:
a first to-be-detected portion having a plurality of teeth formed on each of the steps of said first cylindrical portion;
and

a second to-be-detected portion having at least one tooth in phase with, and in the same shape and size as, the tooth of said
first to-be-detected portion, said at least one tooth being formed on said first partial circumferential surface of said second
cylindrical portion;

wherein said at least one tooth of said second cylindrical portion and a tooth of said first cylindrical portion corresponding
to said at least one tooth are formed in one operation by machining; and

wherein said second partial circumferential surface of said second cylindrical portion is positioned on the inside of the
bottom of teeth of said first to-be-detected portion in the radial direction.