| 摘要 |
PURPOSE:To obtain the titled mechanism whose adjusting work can be executed easily and whose structure is simple, by providing an eccentric cam and a fixing means for fixing its cam, on a cam mechanism part for zooming, consisting of a second cam groove and a connecting pin which is engaged to said groove. CONSTITUTION:An eccentric cam 26 is formed in a circular shape centering around a position being eccentric by (e) from O in the center of a revolving shaft. Accordingly, when a fixing screw 27 is loosened and the eccentric cam 26 is rotated, the revolving shaft center O moves by (s) in the optical axis direction, first and second cylindrical bodies 8, 19 move therewith, and both the first and the second lens groups 7, 17 move by (s) in the optical axis direction. In such a way, a back-focal distance is adjusted, and in order to execute easily the adjusting work, the eccentric cam 26 and a roller 25 are connected by a pawl 28, and the roller 25 is rotated by engaging a tool to a slot 29 formed on the head part of the roller 25, by which the eccentric cam 26 is rotated through the pawl 28. In such a way, when the back-focal distance has been adjusted, the eccentric cam 26 is fixed to the first cylindrical body 8 with the fixing screw 27.
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