Light quantity adjustment apparatus, lens unit and optical apparatus provided with the same

A light quantity adjustment apparatus comprising:

• a board having an exposure aperture;
• blade members that adjust a quantity of light passing through the exposure aperture;
• and
• a driving device for driving the blade members,
• wherein the driving device is provided with an electromagnetic coil,
• a magnet rotor that rotates by applying a current to the electromagnetic coil,
• a rotating shaft that is the center of rotation of the magnet rotor,
• a coil frame which has bearings for supporting opposite ends of the rotating shaft rotatably and around which the electromagnetic coil is wound,
• a reference surface for positioning formed in the coil frame, and
• a shield yoke that is supported with respect to the reference surface and that magnetically shields the magnet rotor, and
• the board is comprised of a support plane that supports the blade members to enable the members to travel,
• a concave portion in the support plane to store the driving device from the plane side for supporting the blade members,
• a support portion in the concave portion to support one end of the shield yoke, and
• holding means for storing and supporting the driving device in the concave portion so that one end of the shield yoke is supported in the support portion and that the other end of the shield yoke can be positioned in the reference surface of the coil frame.