| 摘要 |
PROBLEM TO BE SOLVED: To provide a lens driving device which can detect the position of a lens accurately irrelevantly to whether or not the movement distance of the lens is long or short even after repetitive long-period use. SOLUTION: A photographic lens 2 as this lens driving device is equipped with a cam cylinder 8 which rotates and moves on a straight line passing nearly the center of an opening as a center of rotation, a rear group restriction ring 10 which is inside the cam cylinder 8 and moves straight in the same direction by the same distance together with the cam cylinder 8, a control circuit which controls the movement of the cam cylinder 8, and a rear lens group 4 which is positioned inside the rear group restriction ring 10 so that the optical axis is aligned with the center of rotation and is driven along the optical axis according to the angle of rotation of the cam cylinder 8. In this case, the rear group restriction ring 10 is provided with an optical detecting element 17 which has a light emitting element and a light receiving element and the cam cylinder 8 is provided with reflecting plates 15 and 16; and the reflecting plates 15 and 16 pass position opposite the optical detecting element 17 when the cam cylinder 8 rotate s and the control circuit detects light which is emitted by the optical detecting element 17 and reflected by the reflecting plates by the element 17 to detect the rotational position of the cam cylinder 8. |
