Machine Vision Research On Technology Of LED Die Sorting

The Sorting of LED is one of the most components of the LED production. In the past, sorting equipment has been monopolized by foreign companies; therefore, it's extremely urgent and necessary to develop LED sorting equipment with independent intellectual property rights. In sorting equipment, machine vision technology is of paramount important, whose design have a significant impact on the whole sorting system. This paper mainly focused on the application of machine vision technology into LED sorting equipment.The machine vision hardware platform is established to gather and process image base on high-speed CCD camera, lens, image acquisition card and industrial control computer in this paper. In the LED sorting equipment, the dies location information is essential and works for the entire basic parameter information. The template matching algorithm based on gray value of region was developed to determine the LED dies' level and location parameters. This study further analyzed the function and pretreatment process of the template matching algorithm. Before the corresponding matching, the image was regionally segmented. The main objective of segmentation was to divide the image into small components, change the way of image presentation and to re-organize image pixels to form a more advanced unit, which was also useful to facilitate in-depth analysis. Regional segmentation was only a partitioning process; and it only put similar pixels into different regions; As a result, there were still much redundant information after segmentation. Therefore, we would like to describe the image with regions of interest (ROI). ROI refers to the image region which can arouse the interest of the most users' and is able to well present main image content; it can exactly show the profile and shape of the objects; it can eliminate redundant image information in a certain extent and highlight the core content of the image. Because optical distortion that caused by lens affect the identification and positioning of dies when CCD is working. To solve this problem, the measure of pre-process was applied before the image correction. After identification, it will generate LED location parameter table, which provides for the motion control the movement of data. Base on VC + +6.0 as a software development platform, Sapera Processing image processing software was applied to develop the software control system of machine vision for LED sorting equipment. Machine vision processing algorithms was developed to achieve the image recognition and location. The test results show that the hardware platform and visual processing algorithms in this study are reasonable, and the processing accuracy can meet the requirements of production. The system has good practicability and utility.