| 摘要 |
PURPOSE:To prevent the bite of a motor and to guarantee sure driving by setting a position moved from the reset position of a focusing lens to the side of an optical axis direction or the back side of an optical axis by specified amount as an initial position. CONSTITUTION:The 3rd group holder 4 of the focusing lens group L3 is moved in the optical axis direction through a nut 3 by rotating a lead screw 2 formed integrally with the output shaft of a stepping motor 21. The holder 4 is advanced or retreated according to the rotating direction of the screw 2. In the case of detecting the reset position of the focusing lens group L3, the detected position is surely moved from the reset position in a decided direction by the specified amount even in the case of detecting the reset position based on movement in any direction, and the obtained position is set as the initial position. Whatever place the holder 4 exists in, accurate initial aligning is executed without mechanical abutting action, then a bite phenomenon caused by the mechanical abutting action is evaded. |
