| 摘要 |
PURPOSE:To transmit the motion of a rotor directly to a lens frame by coupling a lens barrel which is the rotor directly with the stator yoke of a motor rotatably through a bearing mechanism, and converting the rotary motion of the rotor into the straight movement of the lens frame by a rotation inhibiting member. CONSTITUTION:The annular lens barrel 22 is provided rotatably through the bearing mechanism 14 in contact with the stator yoke of the motor provided with a magnetic pole plate 8 and a coil 10, the cylindrical lens frame 30 engages the lens barrel threadably through helicoid screws 28 and 32, and an engagement projection 36 projects from the bearing housing 2 of the stator yoke and can engage a lock groove 34 formed in the lens frame. Then the engagement projection engages the lock groove to inhibit the rotary motion transmitted to the lens frame from the lens barrel through the helicoid screws and convert it into the linear motion. Consequently, a focusing lens group put in the lens frame is displaced linearly by optional distance in its optical-axis direction to move focusing lenses for focusing, thereby focusing the lens automatically. |
