| 摘要 |
PROBLEM TO BE SOLVED: To miniaturize and simplify a helicoid mechanism to be used for the focusing and zooming of a CCTV camera provided with a small-pitch multiple thread. SOLUTION: The Figure is a cross section obtained at the time of developing a supporting lens barrel part (helicoid female member) 14 and a zoom lens barrel part (halicoid male member) 13 where a helicoid is provided to a plane and cutting the plane in a plane perpendicular to the hericoid line. A projected line part 41 having width three times of the width of another projected line part 31 is formed without engraving one of recessed line parts 30 engraved at the same pitch on the lens barrel part 13. One of the projected lines formed at the same pitch of the lens barrel part 14 is shave to form a recessed part 40 screwed with the projected line part 41. A bore 13b subjected to tapping work is provided on the projected line part 41, and an aperture 14b is provided along the hericoid of the recessed line part 40. A machine screw is screwed in the bore 13b and engaged with the aperture 14b, thereby constituting a cam mechanism.
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