| 摘要 |
PURPOSE:To reduce the weight of a lens barrel and to improve the durability and mass-productivity of the products by strengthening the structure of a female helicoid for the lens barrel. CONSTITUTION:The female helicoid 2 is constituted mainly of a cylindrical barrel part 2a and a fixing screw thread and a working helicoid screw thread are respectively formed on the outer periphery and inner periphery of the barrel part 2a. A flange part 2b to be a projection part to be fitted to a front body is formed on the outer periphery of the front end of the barrel part 2a. In addition, a ring-like rib 2c is formed integrally with the inner periphery of the rear end of the barrel part 2a. Thereby, the barrel part 2a is reinforced by the rib 2c in addition to the flange part 2b and its rigidity is strengthened. Therefore, the whole female helicoid 2 can be formed as a mold consisting of a synthetic resin material. Since the size D of the inner diameter of the rib 2c can be optionally set up, the rib 2c can be as an opening diaphragm of a lens. |
