| 摘要 |
PURPOSE:To eliminate a projection part on the outer circumference of a lens barrel and to obtain a small-sized, lightweight lens barrel by pressing an oscillation ring where electrostrictive elements are fixed to the rear end of a lens moving ring, and rotating the moving ring forward or backward by a travelling mode oscillatory wave by power feeding. CONSTITUTION:A friction plate 8a is stuck to the rear end of the moving ring 3 which holds a photographic lens 4 for focusing, and the oscillation ring 6a where electrostrictive elements are stuck in a specific shape is provided without rotating around an optical axis by being pressed against the friction plate by a coil spring 9. When electricity is fed to the electrostrictive elements, oscillations of the elements generate the traveling mode oscillatory wave at the ring 6a to rotate the moving ring 3 relatively through the friction plate 8a. Both forward and backward rotations are attained by varying the phase of the voltage to move the lens, and a zoom lens 19 has similar constitution. Consequently the projection part on the external circumference of the lens barrel for housing a motor, etc., is eliminated to obtain the small-sized, light weight constitution. |
