US Patent 7944202 Rotation angle detector

A rotation angle detector is arranged to detect a rotation angle of an object. The rotation angle detector includes a rotor that rotates about a rotation axis according to a rotation of the object, a detecting unit for detecting a rotation of the rotor, a controller for detecting a rotation angle of the rotor based on a detection signal output from the detecting unit, and a case for accommodating the rotor rotatably. The case has at least three elongate holes provided therein. The elongated holes have longitudinal directions extending radially from the rotation axis of the rotor.