Patent ID: 6550986
Filing Date: 2003-04-22
Classification: G03B,H04N

Abstract:
A light amount control apparatus comprising:a base plate having an optical axis aperture; at least one blade member facing said optical axis aperture to open and close the same; a rotating magnet rotor interconnected with said at least one blade member to open and close the aperture, and having magnetic poles and a neutral point between the magnetic poles; at least one of a coil and a soft magnetic member situated adjacent to the magnet rotor to apply equal rotational torques to said magnet rotor in different rotational directions; and regulating means formed adjacent to the magnet rotor to regulate a rotational movement of said magnet rotor within a prescribed angle, said regulating means being located to provide the magnetic rotor with an opening region and a closing region different from each other with respect to the neutral point so that the rotational torques acting on said magnet rotor differ by said regulating means to regulate the rotational movement of the at least one blade member in the opening and closing regions.