Nikon Corporation

Kiyonobu Takabayashi

Yoshiro Kodaka

A helicoid threaded tube formed by molding a synthetic resin in a split mold, comprises: a hollow cylindrical member of synthetic resin; primary threads integrally formed with the cylindrical member and helically extending on the inner or outer surface thereof and having a cross section which is substantially trapezoidal at all portions thereof except split line segments thereof where the matching surfaces of the split mold intersect with the cylindrical member; and relief thread portions centered at the split line segments and continuously extending from the primary threads with the width gradually narrowing, the relief thread portions having a height substantially equal to that of the primary threads. In such threaded tube, at those portions of its threads (relief portions) within which molding burrs will tend to occur during molding, the threads have a gradually narrowing width and a constant height. This configuration of the threads ensures that engaged male and female helicoid threaded tubes formed in accordance with the invention can achieve a smooth relative sliding movement while substantially maintaining mechanical strength. A lens barrel may incorporate such threaded tubes.

Growing community of inventors

Kawasaki, Japan

Kiyonobu Takabayashi