Research On Scanning System For Measuring The Thickness Of Plastic Film Based On Capacitive Sensor

The thickness equality is an important parameter for evaluating the quality of the plastic film. Traditional off-line way of measurement could not meet the actual need. It is in dire need of developing a kind of on-line measuring the thickness of plastic film system. This paper individually designed a set of dynamical scanning system for measuring the thickness of plastic film based on capacitive sensor accompanied by the eddy sensor. To eliminate the errors in dynamical scanning measurement, single-eddy and double-eddy sensor compensation models were established in this paper. The temperature drift characteristic of system was explored.Innovation points are shown as follows. A double-eddy sensor synchronous scanning compensation solution was proposed. The temperature characteristic of thickness measurement system was researched in detail, and temperature drift compensation was discussed. The way of increasing the sensitivity and linearity was explored.The main work included in the dissertation is shown as follows.1. Analyzing the errors in dynamical scanning measurement in detail such as external vibration, linearity error of rail, temperature and humidity drift.2. Designing the before-compensation and synchronous compensation, establishing the single-eddy sensor and double-eddy sensor compensation models, and analyzing these models in theory.3. Designing the temperature and humidity measuring circuit based on SHT15 sensor, accomplishing the program for data acquiring and serial communication, and researching on temperature drift and compensation;4. Constructing a set of dynamical scanning equipment for measuring thickness, measuring the sensitivity of system using standard film, experimenting on some samples, and validating the reliability and stability of system.