Inventors:
Kevin D. Edmunds - Newport MN
Neil A. Sticha - Newport MN
International Classification:
G01N 2722
G01R 2726
Abstract:
A capacitance gauge for measuring changes in the thickness of dielectric film, such as plastic film, is automatically temperature and humidity compensated by utilizing a primary measurement sensor and a reference sensor which monitors changes in perceived capacitance caused by ambient temperature and humidity changes or other environmentally induced interferences. The reference sensor counterbalances in an equal an opposite fashion, and thereby automatically cancels, any imbalance in the primary sensor caused by temperature, humidity, or other, fluctuations. An improved film transport assembly for serially examining plastic film material which eliminates errors in thickness measurement location and eliminates variation in distance between individual sensor readings, while at the same time allowing the user of the invention to select from a full variable range of distances between individual sensor readings and also allows accurate positioning of the film in the sensor.