| 摘要 |
PROBLEM TO BE SOLVED: To smoothly and highly accurately perform zoom operation with small operating power by providing a cam component with a non-linear rotation transmission groove and a lens group moving cam groove and decreasing the cam pressure angle of the lens group moving can groove rather than the case of making the rotation transmission groove linear. SOLUTION: A first lens group frame groove 41A to engage a first lens group frame provided on a first lens group moving frame and a third magnification cam cylinder groove to engage a second magnification cam output frame are provided. Then, the cam pressure angle at a wide side terminal part, namely, the angle formed with an optical axis direction 0 and a first lens group frame groove center line 41BC such as so-called cam pressure angle is reduced so that the cam pressure angle can be reduced smaller than a fixed value over all the first lens group frame groove at least. Namely, offset amountsα,β...between the center line 41BC of a first lens group frame groove 41B and a center line 41AC of the smoothly operable first lens group frame groove 41A are operated at each rotation angle position of the third magnification cylinder.
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