| 摘要 |
A lens barrel of a camera has a stationary cylinder and a rotary cylinder which is advanced and retracted relative to the stationary cylinder while it is rotated. A plurality of helical gears as well as a helicoid are formed, along the helicoid, on an outer periphery of the rotary cylinder which is helicoid-coupled to the stationary cylinder and advanced and retracted along the optical axis while it is rotated. A plurality of drive gears which are gear-coupled to the helical gears are formed on the stationary cylinder. At least one of the plurality of drive gears is gear-coupled to the helical gears in a rotation range of the rotary cylinder.
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