| 摘要 |
PURPOSE:To prevent the damage of a lens barrel driving mechanism even if an external force is applied to a photographic lens moving cylinder in the feed- out state, by constituting the mechanism of a coupling member which moves the photographic lens moving cylinder forward and backward, a detaining member which can be engaged with and disengaged from this coupling member, and a driving pin engaged with this detaining member. CONSTITUTION:When a focal length varying gear 14 is rotated counterclockwise, a pin 20 depresses a side edge 30A of a control lever 30 to rotate it clockwise and a photographic lens moving barrel 12 is fed out from a fixed cylinder 10. If an external force is applied to the moving cylinder 12 in this state by drop of a camera or the like, a pin 40 presses a detaining part 38 by counter clockwise turning of a connection lever 22, and a detaining lever 34 is rotated clockwise and is disengaged from the pin 40 to release the connection between the moving cylinder 12 and the pin 20. Thus, even if the external force is applied with the moving cylinder 12 fed out, a gear transmission means is not damaged because the connection is released.
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