| 摘要 |
An ultrasonic motor built-in lens barrel includes a focusing optical system, a fixed barrel, and an ultrasonic motor having a stator so fitted to the fixed barrel as to be rotatable about an optical axis and capable of generating ultrasonic vibrations therein, and a rotor coming into a frictional contact with the stator and rotating about the optical axis with the ultrasonic vibrations to thereby enable the focusing optical system to move. The lens barrel also includes a motor drive controller for controlling a drive of the ultrasonic motor, a manual operating portion capable of moving the focusing optical system by an external operation, and a mode selecting portion capable of selecting an autofocusing mode for moving the focusing optical system by the ultrasonic motor, and a manual focusing mode for moving the focusing optical system. The lens barrel further includes an angle-of-rotation reduction mechanism for reducing an angle of rotation of the manual operating portion down to an angle of rotation of the stator of the ultrasonic motor. The same mechanism has a plurality of rotatable members rolling on a side surface of the fixed drum, and a biasing member for pushing the manual operating portion against a side surface of the fixed barrel through these rotatable members and thus causing frictional contacts therebetween.
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