| 摘要 |
A rotation angle detecting device includes a magnet ( 4 ), a magnetic substance unit ( 5 ), and a non-contact magnetic detection element ( 7 ). The magnet ( 4 ) rotates with an object to be measured and includes two ends magnetized so as to have opposite polarities. The magnetic substance unit ( 5 ) forms a predetermined air gap with the two ends of the magnet ( 4 ) and is divided into magnetic members ( 6 ) so as to provide plane symmetry with respect to a vertical plane perpendicularly crossing a rotational center axis of the magnet ( 4 ) to form a magnetic detection gap ( 9 ) by the division. The non-contact magnetic detection element ( 7 ) is provided in the magnetic detection gap ( 9 ) between the magnetic members ( 6 ) so as to output a signal corresponding to a density of a magnetic flux passing through the magnetic detection gap ( 9 ). The rotation angle of the object to be measured is detected based on the output signal from the magnetic detection element ( 7 ). The magnetic members ( 6 ) include reverse warp parts ( 34 ) so that the air gap suddenly increases when the magnet ( 4 ) rotates at a predetermined rotation angle from a state where the air gap is minimum in a direction in which the air gap increases.
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