| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens barrel which is suitable for use in a projection lens optical system for a projector, and permits automatic focusing. SOLUTION: This zoom lens barrel comprises a cam cylinder 130 performing a cam action in the direction of the optical axis, 1st to 3rd lens transfer frames 140, 150, 160 for performing zooming operation by being relatively transferred by the cam cylinder in the direction of the optical axis, a transfer frame for focusing 170 for performing focusing operation by helicoidal coupling to the 1st lens transfer frame 140, a fixed cylinder 120 for supporting the cam cylinder to be freely turnable and also guiding the lens transfer frames in the direction of the optical axis, and a 1st motor 180 for applying rotary driving force to the cam cylinder. Then, for the transfer frame for focusing 170 and a fixed cylinder 120, a interlock mechanism consisting of a ring gear 190 and ring lever 200 which transfer the transfer frame for focusing 170 in the direction of the optical axis interlocking with the torque at a predetermined position in the optical axis direction, and a 2nd motor 210 for driving the interlock mechanism are used. Thus, zooming and focusing can be carried out automatically. COPYRIGHT: (C)2004,JPO&NCIPI
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