Patent ID: 8566063

Claim:
A rotation angle detector detecting a rotation angle of a detection subject, comprising: a magnetic-flux-transmitting means which is shaped like a symmetrical frame made of magnetic material, the symmetrical frame being symmetrical with respect to a symmetrical plane which represents an arbitrary plane including a rotational axis of the detection subject, the rotational axis extending inside of the symmetrical frame, the symmetrical frame including a first wall and a second wall which are arranged opposite with respect to a reference plane including the rotational axis and being orthogonal to the symmetrical plane, the symmetrical frame including a third wall which connects the first wall and the second wall, the symmetrical frame including a fourth wall which connects the first wall and the second wall, the third wall and the fourth wall arranged opposite with respect to the symmetrical plane; a magnetic-field-generating means disposed on an inner surface of the magnetic-flux-transmitting means symmetrically with respect to the symmetrical plane; and a magnetism-detection means disposed between the first wall and the second wall in such a manner as to relatively rotate with respect to the magnetic-field-generating means and the magnetic-flux-transmitting means according to a rotation of the detection subject, the magnetism-detection means having a detection surface which detects a magnetic flux, wherein the magnetic-field-generating means is disposed on only the inner surface of the first wall, and the magnetic-field-generating means is magnetized in a direction orthogonal to the first wall.