To provide a rotation angle detection device having a linear magnetic flux change to the rotation angle.
This rotation angle detection device is equipped with: a ring magnet connected to a rotating shaft and forming a magnetic field; a ring yoke having a pair of gaps arranged in the magnetic field on the circumferential side of the magnet, forming a magnetic circuit between itself and the magnet, and arranged so that, when a relative angle to the magnet is changed by rotation of the rotating shaft, the magnetic flux density is changed; and a magnetic detector arranged on one of the pair of gaps, for detecting the magnetic flux density. A magnetic flux distribution curve spreading over the whole circumference on the yoke inner circumferential surface has at least one section of flat angle sections FX, FY having the approximately constant magnetic flux quantity, and has a characteristic wherein the section length of an N-pole side angle section X which is an N-pole side part of the magnetic flux distribution curve is different from the section length of an S-pole side angle section Y which is an S-pole side part of the magnetic flux distribution curve.
FUKAYA SHIGETOSHI
TAKEDA KENJI
KAMIZONO TSUTOMU
DENSO CORP
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