Film thickness measuring device with signal averaging to compensate for roller eccentricity

摘要

A film thickness measuring device for measuring the thickness of a film formed on a sheet member conveyed with the rotation of a rotary shaft. The thickness measurement is accomplished based on averaged values for a period of time which is determined according to the rotation speed of the rotary shaft. Consequently, errors due to the eccentricity or uneven surface of the rotary shaft are removed from the measurement values resulting in improving an accuracy of the thickness measurement of the film.