Method of measuring period of surface defect.

摘要

In a method of measuring a period on which a surface defect appears in a surface of a web-like material moving in a lengthwise direction, surface defects distributed in the surface are detected in a lengthwise direction of the web-like material. Positional data and distance data of the detected surface defects relative to one another are collected for a predetermined length of the web-like material. The web-like material is decided to have a periodic surface defect appearing on a period between predetermined maximum and minimum periods when the distance data includes a distance equivalent to an elemental period that is integer multiples of a fundamental period.