Light-quantity control device

摘要

An optical apparatus having a light-quantity control device includes: a) a rotating member having a plurality of magnetic poles; b) a stator having a plurality of magnetic pole sections opposed to the rotating member; c) a coil for exciting the stator; d) an input device for inputting driving speed information as the driving speed of the rotating member; e) an output device for outputting to the coil a driving signal for rotatably driving the rotating member less than one full rotation thereof on the basis of the driving speed information; f) a detecting device for directly detecting a movement state of the rotating member and outputting a detection signal which varies approximately linearly with the position of the rotating member representing movement state information; g) a forming device for forming rotating speed information of the rotating member from the detection signal; h) a correcting device for correcting the driving speed information by the use of the rotating speed information, the correcting device providing a corrected driving speed information; and i) a light-quantity adjusting member adapted to be displaced by the rotation of the rotating member.