Patent ID: 7053514

Claim:
An imaging apparatus having a lens barrel, in which an imaging optical system is disposed, a movement mechanism having movable members, which constitutes an iris or a shutter and opens and closes an optical path of said imaging optical system, and a drive motor serving as a drive source for said movement mechanism, wherein said drive motor comprises: a shaft serving as a center of rotation; a magnet, two-pole magnetized and rotated around said shaft; a turning arm engaged with said movable members and turned integrally with said magnet, for moving said movable members in a direction associated with a turning direction; a stator coil wound in a direction perpendicular to a direction of rotation of said magnet and disposed in such a way to enclose said magnet from outside; a coil bobbin on which said stator coil is wound; a stator yoke disposed outside said coil bobbin and having a cylindrical circumferential surface part penetrated in an axial direction of said shaft; and position detection means for detecting a rotational position of said magnet; wherein a closed magnetic path, which is closed in a direction of rotation of said magnet, is constituted by said circumferential surface part of said stator yoke, and a magnetic balance holding section, which holds a magnetically balanced condition between said magnet and said stator yoke during non-energization of said stator coil, is formed integrally with said stator yoke, and wherein a projecting part protruded from said circumferential surface part of said stator yoke is provided therewith as a magnetic balance holding section of said stator yoke.