| 摘要 |
PROBLEM TO BE SOLVED: To provide an encoder which can perform angle detection within one revolution of a motor by a detecting part detecting a magnetic field. SOLUTION: The encoder includes a magnet part (6) which has a magnetic pattern formed and revolves around the axis (R) of revolution and which forms the radial magnetic field between inner and outer circumference sides and is so provided as to make the direction of the magnetic field change at least once through one round in the direction of revolution, and the detecting part (4) which detects the magnetic field formed by the magnet part, wherein the magnet part has a reduced width part (6s) formed by relatively reducing a radial width (Ws) in the boundary (6d) where the direction of the magnetic field changes. COPYRIGHT: (C)2011,JPO&INPIT
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