| 摘要 |
PROBLEM TO BE SOLVED: To hold the coupling by a helicoid screw strong even if an unexpected external force is applied without decreasing the strength of the helicoid screw and a lens frame as to a lens barrel using the coupling by the helicoid screw. SOLUTION: A female helicoid screw 13 (15) and a male helicoid screw 14 (17) have flanks 13a (15a) and 14a (17a), facing a fixed frame 3 (rotary frame 4) in a direction wherein the rotary frame 4 (zoom frame 5) is sent out and extended, at a flank angleθ1. Flanks 13b (15b) and 14b (17b) facing the fixed frame 3 (rotary frame 4) in a direction wherein the rotary frame 4 (zoom frame 5) is stored, are formed at a flank angleθ2. Here the flank angleθ1 is smaller than the flank angleθ2.
|
