Research On Infrared Light Transmission Plastic Film Thickness Gauge

Nowadays, plastic film has a wide application in everyday life and factory production. With the increasing demand of this material, the criteria of film production have also been stricter in recent years. Hence, it is necessary to have an efficient, accurate and real-time method to measure the thickness of the plastic film, in order to meet the quality requirement. However, the traditional manual measurement method is low in efficiency. Besides, this traditional method is discontinuous and cannot get the real-time data, which means there is delay in the measurement process. What’s more, the manual measurement has the risk of breaking the film and has poor repeatability. For the purpose of changing this situation, this paper focus on the research of the thickness measurement of the plastic film, based on infrared rays.In the first part of this paper, I introduced the background of the thickness measurement by infrared rays and the production process of the plastic film. I also mentioned the theory of this measurement method and described the overall design of the thickness measuring instrument. In the second part, I elaborated on the hardware design of this instrument, including the infrared rays driver circuit and the signal processing circuit. The infrared rays driver circuit is used to transmit the signal and amplify the signal to have a constant current output. And I introduced all the details about the components of the infrared rays driver circuit. And for the signal processing circuit, this part is arranged in the order parallel to the flow of the signal. I first introduced the selection of photosensitive components and the design of photosensitive circuits. Then I present the selection of analog filter components and the related circuits design. In addition, I described the principle and process of the design of signal amplifying and strengthening circuits, A/D sampling circuits and the design of TMS320F2812 controlling circuits. In the next part, I introduced the design of the controller in the film measurement system, from the algorithm of infrared ray driver board, the initializing program of the DSP signal processing board, to the main program, the data processing program and the touch screen program. Finally, I analyzed the experience data of the system and the influence that caused by the measurement errors.This paper presents the design and debugging of the plastic film thickness measurement instrument, which is based on the DSP embedded system and the infrared rays technology. This instrument gathers the advantages of real-time measurement, friendly interactive interface and satisfying stability. According to the practical comparison tests with traditional measurement methods, the measurement system I designed can make non-contact measurement and reduce the artificial errors. What’s more, this new measurement method can improve the accuracy, efficiency and the quality of film thickness measurement.