The Research Of AOI System For Pin-Checking Based On Image Measurement

When manufacturing PCB, the drill pin's quality is an important factor to ensure the PCB's eligibility. To improve the drill's measurement way in China, this paper study the technology of developing the drill's AOI system which is based on image measurement technology.After analyzing the request of drill's detection, this paper design the system's whole structure, and explain the system's structure detailedly according to the info stream. And then this paper designs the system's hardware systems. Firstly this paper puts forward that a ringed lamp-house should be fixed higher than the lens in order to avoid noise-light getting the lens. Secondly this paper design acentric objective for the pin's imaging. And lastly this paper chooses the suitable CCD sensor and video card for the detection request.Then this paper discusses the development technology of the instrument system's software part. After analyzing the software's request, this paper designs the whole software structure. And then design a special data structure for the transfer of the image's data. When processing the pin's image, this paper studies some image processing algorithm. When detecting the edge, an auto-choose threshold algorithm is given to reduce the salt-and-pepper or pulse wrong edges. After analyzing the special noise factor in pin's image, this paper improves the edge detection elements. That's putting forward a way which is named"the method of de-noise based on linear weighted operator template"to reduce the zonal or cluster noise. And test show that the algorithms detect image's edge rightly. Because pin's geometrical figure is complex, a method which is called"edge searching with line fitting"is puts forward to searching the pin's edge. To find the right special points for calculating parameters, this paper puts forward an algorithm which firstly detects the edge to get the general points and then uses interpolation to get the exact points. At last this paper studies how to use points'coordinate num for parameters'calculating. A drill-pin's image is processed by using the algorithms, and the result show that these algorithms are effective.The algorithm which is named"de-noise based on linear weighted operator template"and the edge searching method which is called"edge searching with line fitting"are based on the factor of pin's image. But the algorithms can be used to process general images.