A method of and apparatus for monitoring coating thickness.

摘要

A monitor for monitoring coating thickness in a vacuum metallizer comprises a Q meter. The meter has a number of heads H spaced across the width of the web W being metallized. Each head has a coil and an inductor which together form a tuned circuit. The heads are supplied with high frequency current from a source S and changes in Q caused by variation in coating thickness are detected by detector D. The outputs from the heads may be multiplexed so that only one source S and detector D are required. Variation in Q is an indication of coating thickness. The detector D may be calibrated directly in units of thickness if desired.