ELECTROMAGNETIC ACTUATOR, LIGHT QUANTITY ADJUSTMENT DEVICE, AND OPTICAL APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a small-type electromagnetic actuator capable of positioning a yoke against a rotor with high precision while suppressing magnetic loss of the yoke.

SOLUTION: An electromagnetic actuator includes a rotor and a yoke having two magnetic poles and magnetic path formation parts to which a coil is mounted. The magnetic path formation parts have a protrusion for attaching the yoke to a base. The yoke is formed by a powder metallurgy molding method. A cross section perpendicular to a first direction in which a magnetic path extends in the magnetic path formation part is referred to as a magnetic path cross section. A width in a second direction intersecting at right angles with the first direction seen from the direction in which the rotation center axis of the rotor extends is referred to as a magnetic path width. The protrusion is formed such that the area of the magnetic path cross section in a first part including the protrusion in the magnetic path formation part does not become smaller than the area of the magnetic path cross section in a second part adjoining the first part in the first direction and the magnetic path width of the first part does not become larger than the magnetic path width of the second part.

COPYRIGHT: (C)2013,JPO&INPIT