| 摘要 |
A capacitance gauge for measuring changes in the thickness of dielectric film, such as plastic film, is automatically calibrated by utilizing a direct-measurement sensor method or a contact-type sensor method alongside the capacitance sensor assembly. The direct-measurement sensor and the capacitance sensor measure the same point on the film sample, and the capacitive calibration reading is correlated to the direct-measurement sensor reading to automatically calibrate the capacitive sensor. 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 accurate positioning of the film in the sensors. Also, electronics which provide four modes of operation which include operating both the direct-measurement sensor and the capacitance sensor independently, or integrated for automatic calibration of the capacitance sensor, or simultaneously as a dual-sensor thickness measurement system.
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