Screen Printing Automatic Defect Detection System Design Based On Multi-template Matching

Product surface quality screen printing machine vision inspection can improve production efficiency and product quality, but due to the presence of an object detected rotational deviation and horizontal angle to the vertical position deviation,resulting in high false consciousness, slow detection speed. Priori conditions by detecting objects based on the limited angle of rotation, a plurality of pre-test to establish a certain angle of rotation template for the basic template matching detection of defective object, template matching with rotation detection. And wherein a match can still be detected correctly judged as qualified products, all the smallest error then select the template matching error to indicate the location of the defect. No real-time detection of image rotation processing, matching and just simple logic, or operation, greatly improving the speed and reduce the error rate.The project is designed for the electrical connector surface quality silk screen machine vision inspection systems, designed on the basis of comparative experiment hardware system when a low angle diffuse light source, the detection algorithm in the traditional pattern matching method is improved, we designed a multi-template matching rapid detection methods, ensuring low missing rate of defective products,while reducing the false positive rate, improve the detection speed. Research to this article as follows:(1) Electrical connector is designed for surface printing quality inspection machine vision inspection systems, particularly the selection of the light source compared experiments designed better source program.(2) Improved detection algorithm based on image matching template for smaller rotational position deviation of the actual specific applications designed multi-template matching method, that is, before the establishment of a plurality of detecting a certain angle of rotation of the rotary templates, detection no longer do the image rotation process, but simultaneously or sequentially with a plurality of templates for the improved detection rate and reduce the false alarm rate.(3) Designed to establish a multi-template method: Based on the 3-5 has been determined eligible artificial samples for image pre-processing, accurate image matching and image morphological processing, establish expansion templates and skeleton templates two basic template, and further respectively rotate around a small fixed angle of rotation to create multiple templates.(4) Designed based on the peak position of the image line integral method for determining the offset method to judge, quick assessment to detect objects smaller positional deviation and improve image matching, matching speed.Contents of this paper can also be used to apply the practice of other quality testing machine visual appearance.