Coating weight measuring and control apparatus

摘要

A sensor (88) and a method for determining the basis weight of a coating material (24) containing CaCO3 on a substrate (12) is described. The sensor comprising: an infrared radiation source (50), and a radiation receiver consisting of two infrared detectors (32A,32B) sensitive to measurement and reference separate wavelength regions respectively. The determined basis weight is insensitive to changes in the amount of substrate material underlying the coating. Signals from the sensor may be used in the control of a coating mechanism to provide a coating having a uniform basis weight.