Motion detector

A detector for detecting motion of a moving body by use of a power generation sensor, wherein:

• the power generation sensor includes:
• a magnetic wire in which a large Barkhausen effect occurs;
• and
• a coil wound around the magnetic wire;
• the moving body includes:
• a soft magnetic body portion;
• and
• a plurality of magnetic-field generation sources mounted on the soft magnetic body portion at even intervals;
• the plurality of magnetic-field generation sources each have a pair of an N-pole and an S-pole;
• magnetic poles of two adjacent magnetic-field generation sources on a mounting-direction outer side of the magnetic-field generation sources, are heteropolar;
• the power generation sensor is disposed so as not to interfere with the moving body;
• a direction of motion of each of the magnetic-field generation sources when the magnetic-field generation source approaches the power generation sensor, is perpendicular to an axial direction of the magnetic wire;
• a magnetization direction of the magnetic-field generation source when the magnetic-field generation source approaches the power generation sensor, is parallel to the axial direction of the magnetic wire or parallel to a direction facing the magnetic wire;
• and
• at least one part of a place from an axial-direction central portion to an axial-direction first end portion of the magnetic wire faces the magnetic-field generation source, and at least a part of a place from the at least one part to an axial-direction second end portion of the magnetic wire faces the soft magnetic body portion, when the magnetic-field generation source approaches the power generation sensor,
• wherein the moving body rotationally moves, and the magnetic wire is on a straight line orthogonal to a rotational axis of the rotation motion,
• wherein the axial-direction central portion of the magnetic wire is offset from the rotational axis, and
• wherein the magnetic wire is disposed so as to intersect with the rotational axis of the rotation motion.