Glass Thickness Measurement System Of Double Beam Path Compensation Based On CPLD Technology

In our country, glass production capacity has already reached the level of developed countries, but the thickness of glass is still used artificial measurement method. Detection efficiency is not high enough, and test results are vulnerable to man-made factors. Therefore research on the thickness of glass-detection technology is particularly important. The measurement system with CCD has an advantage on geometrical measurement such as thickness for achieving high accuracy, on-line dynamic detection, non-contact measurement, especially adapts to measure little thickness alternation.Based on refraction and reflection principle,according to the production technology of float glass, glass will quiver in the transmission. As to this deficiency, the refraction and reflection principle is improved, and the method of double beam path compensation is advanced. The semiconductor laser is chosen as light source, and peripheral circuit of linear CCD is designed in theory and studied in experiment. Finally non-contact thickness measurement instrument is constructed, using CCD as photoelectric transformation element and computer as the controller. After theory analysis, measurement range of the system is between 1 mm to 20 mm, and the precision is 0.01 mm.The time order driving circuit of CCD is designed and debugged with CPLD (Complicated Progra mmable Logic Device), which enhance reliability and agility of circuit. The CPLD designing under MAX+PLUS II can complete all work. The video signal processing circuit realizes the primary catching, signal amplifying, CDS filtering and variable threshold binarization. The binary data is regional calibrated and thickness judged, and then the final data is input to computer.The experiment of CCD time order driving circuit shows the circuit can drive CCD perfectly; take advantage of the characteristic of CCD photoelectric transition and output steady and reliable electric signal. Experiments simulate condition of producing glass, carry on several measurements for glass with different thickness, get and analyze measured data.