| 摘要 |
PURPOSE:To lower a pressure per unit area, to prevent a zoom ring from being damaged by a polygonal spring, and to improve the durability of a clutch mechanism by increasing a contact area, when the polygonal spring is welded by pressure to the zoom ring. CONSTITUTION:A clutch mechanism of a zoom lens is constituted by coupling directly a motor gear 2 to a motor 1, engaging a zoom gear 3 of a zoom gear mechanism 3a to this gear 2, and placing a polygonal spring 4 between this zoom gear mechanism 3a and a polygonal spring receiving part 5a of a zoom ring 5. A V-groove 5b is formed on the periphery of the polygonal spring receiving part 5a of this zoom ring 5. Also, a sectional shape of the polygonal spring 4 is made circular, and its polygonal spring 4 is welded by pressure to the zoom ring 5 by contacts 5c, 5d in the V-groove 5b. Moreover, the V-groove 5b is formed to a trapezoidal groove, and the polygonal spring 4 is made to abut on two parts of the inclined surface and one part of the bottom face of the trapezoidal groove. In such a way, the zoom ring 5 is prevented from being damaged by the polygonal spring 4, and the durability of the clutch mechanism is improved.
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