Patent ID: 6179918
Filing Date: 2001-01-30
Classification: G01B,G01G

Abstract:
A coating system, comprising:a sheet coating apparatus for applying a coating material that contains silicone to the surface of a moving uncoated sheet that comprises a base sheet, the coating apparatus including a metering element for regulating the amount of the coating material which remains on a coated sheet after a moving uncoated sheet passes by the metering element;a first coating sensor disposed adjacent to the coated sheet and including a first radiation source disposed to direct a first beam of radiation into the coated sheet, and a first radiation receiver positioned to detect at least a portion of the first beam emerging from the coated sheet, the first receiver being configured to detect the amount of radiation in first and second separate wavelength regions of the infrared electromagnetic spectrum and to produce first and second signals therefrom, respectively indicative of the amount of detected radiation in the first and second regions, and wherein the first region is selected for radiation which is sensitive to the basis weight of the base sheet and the second region is selected for radiation which is approximately equally as sensitive as the radiation in the first region to the basis weight of the base sheet, but which is also sensitive to the silicone of the coating material, the sensitivity of the radiation in the first region to the silicone being different than the sensitivity of the radiation in the second region to the silicone and wherein the first region ranges from about 3.60 to 3.80 .mu.m and the second region ranges from about 3.36 to 3.38 .mu.m;a computer operatively coupled to the first receiver for computing the amount of coating material on the sheet from the first and second signals, the computer producing a third signal indicative of the computed amount of silicone in the coating material; andat least one actuator, operatively coupled to the computer and to the metering element, for adjusting the metering element in response to the third signal to regulate the amount of the coating material on the base sheet.