Conf.42 applications of digital image processing XIV moiré image overlapping method for PCB inspection designator

The computer pattern recognition has been expanding its application in wide various fields, take its application in Print Circuit Board (PCB) inspection for example, will accordingly reduce requirement of manpower as well as the error rate, if equipped with adequeat accessories, then real time processing can be implemented with defect locating feature. The design philosophy of this system is focused on how to establishing a complete PCB inspection methodology with error indication for a more effective amending process. Algorithm of this system is as follow: first use the CCD camera to scanning the PCB under inspection, then compare it with the correct one which already been stored in the computer memory and examine the result of comparision. If any error exist, then a mark " + " will be marked on the defect spot from computer and overlapping will be excuted via a computer controlled zooming LCD (Liquid Crystal Display) overhead projector, the " + " mark can actually specify the defect spot clearly. The size and the position of the overlapping image with the tested PCB will be equally and exactly one to one corresponding, the optical distortion error are corrected by computer program with morie and optical analysis method. A robot arm can take an advantage of it for automatic amending work which will definitely improving error indication and defect amending. (Patent Apending).