Liquid Crystal Display Aoi System Study And Application

LCD (Liquid Crystal Display) has been widely used in our lives. People's requirement is more and higher about vision enjoyment. The best goodness is reducing cost and improves quality for that LCD company rises market share. The key is improve inspect function of defects. At present, manual inspection is major method, the method waste more cost and missing. So AOI system can solve this problem, reduce company press, and raise enterprise competitive power.At first, for study LCD defects, it focuses on introduction common LCD defects. And detail introduces base structures, display principle, defects reason. As usually, the defects can be divided into three types: function defects, back light defects, cell defects. Different display comes from different defect. AOI system must distinguish all kinds of defects.At second, the key LCD parameters have been introduced. The LCD parameters mainly include: brightness, contrast, color saturation, response time. Because this parameters need to be measured, it introduced measure method about key parameters. One is measure about luminous intensity, another is measure about brightness. Base on this parameter, test pattern have been set up. This parameter is base of image collection.At third, base on above contents, the AOI system has been setup, the base of image collection is CCD. The data base of CCD became to image that has been analysis through A/D transfer and remove noise. Afterwards, the image has been handling for noise, and been regulated, been subdivided. In image segmentation, a background modeling method based on polynomial surface fitting using least square method is presented. Defect objective has been distinguished; the auto inspection function has been realized.At last, set up AOI hardware. In production process, AOI system collects parameter of LCD through CCD. The parameter message has been passing to control computer for analysis. The image has been collected which compares with standard image, so as to achieve analysis result, and judge OK or NG. When it can't be judged, the AOI system is fail. So the system accuracy is key. From collection, the system accuracy is above 90%, so this system is successful. It can be used LCD production process.From above study, AOI system can improve LCD company enterprise competitive power. It provides good software and hardware foundation for speed inspection.