The Study And Implementation Of Automatic Scanning Device Used For Measuring The Quality Of Band-pass Filter

With the rapid development of IT industry, filter is being used more and more extensively, and its quality is demanded more and more highly. In the actual mass production process, the defect of the manufacturing causes filter quality uneven. Thus, it has practical significance to measure the quality of filter comprehensively, accurately, rapidly and automatically.In this paper, a precise 2D movable platform is designed. The platform whose maximal displacement is 120 mm x 120 mm can carry up to one hundred pieces of filter with size of 10 mm x 10 mm, also can load many pieces of large size filter, and its specification is flexible according to user customization. Combined with high performance stepping motors and subdivision drivers, the platform can operate stably and continuously in order to meet the effective measurement need of market.The hardware circuit of this system is composed with control board whose core component is EZ-USB FX2 and stepping motor subdivision drivers. The firmware program is finished based on the Cypress framework. Through the USB2.0 agreement, EZ-USB FX2 can receive command from PC's application and send pulses to the stepping motor drivers in order to control the movement of the 2D platform. At the same time, EZ-USB FX2 uses the interrupts to detect displacement state of platform and gives feedback to PC's applications in time.Filter transmission measurement can't without modern miniature spectrometer. Based on understanding the basic principle of miniature spectrometer, in this paper, the noises of the miniature spectrometer are studied comprehensively, and the corresponding denoising algorithms which have been proven feasible by experiments are proposed. The accuracy of this measurement system gets guaranteed.In this paper, a practical band-pass filters quality criterion algorithm is putted forward. This algorithm is not only applicable to the normal filter transmission curve, but also more suitable for measuring the filter with quality problems which usually appears as their transmission curves are not smooth but with many'inflection points' or'pits'. The proposed quality criterion algorithm has the significant breakthrough in accuracy, reasonable, comprehensive, etc.According to large numbers of experiment by samples, the results have verified this system measurement precise, criterion comprehensive, and scanning fast. Moreover, for every plate of the filter array, the scanning system can realize the automatic measurement, without any human intervention. Compared with those equipment used for testing quality of filter nowadays, the comprehensiveness and efficiency of this system are the most outstanding, thus it has the important use value and broad market prospect.