FPGA-Based Real-Time Data Processing For CCD Scanning Defects Inspection

Surface defects affect products quality which is one of the important factors for quality control. With the updated information technology and advanced electronic devices, it is possible to develop a new inspecting technology for sorting, checking and evaluating material quality, by which defects microscopic images can be real-time recorded, processed and displayed. In this dissertation, real-time defects data processing technology based on Field Programmable Gate Array(FPGA) was developed for this purpose. This instrument was used for polymeric film inspection for the first time.In this dissertation, real-time defects inspection was implemented using paralleled structure and high-speed operation of FPGA. The hardware circuit based on FPGA was established. According to signal characteristics of polymeric film defects, the scheme of preprocessing defects images based on FPGA was designed. First, the polymeric film defects signal from CCD was processed using dynamic threshold. The data above the threshold, which was regarded as image's background information, was abandoned. The data below the threshold, which included defects microscopic images information, was preserved. Then, the defects data was packed according to the defined format. Finally,the data processed was transferred to PC through USB2.0 real-time to reconstruct defects microscopic images. The transferred data quantity was decreased tremendously by this method. The inspecting speed was greatly improved.The standard plate and polymeric film material were tested. The experimental results demonstrated that defects within 70μm～1000μm were inspected effectively by the CCD scanning defects inspection instrument, and Good agreement was shown between defects images real-time reconstructed and optical microscopic images not only in shape but also in gray.