Minebea Mitsumi Inc.

Kaoru Nishiguchi

Yasuo Osada

Takahiro Ohara

To reduce the influence of an unintended magnetic flux of a permanent magnet on detection accuracy. An absolute encoder () includes a magnet provided at a tip end side of any one of a first worm gear portion () and a second worm gear portion (), and an angle sensor configured to detect a rotation angle of the magnet in response to a change in magnetic flux generated from the magnet. In the magnet, a first magnetic pole portion of a first polarity and a second magnetic pole portion of a second polarity different from the first polarity are formed adjacent to each other as viewed from an axial end surface of the magnet. The first magnetic pole portion and the second magnetic pole portion are formed adjacent to each other in a radial direction with a radial center of the magnet as a boundary, and the first magnetic pole portion and the second magnetic pole portion are formed adjacent to each other in an axial direction with an axial center as a boundary. The absolute encoder () is provided with a magnetic interference reduction member formed of a magnetic material on a radially outer peripheral surface of the magnet.

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Nagano, Japan

Kaoru Nishiguchi