Application of camera calibration method based on active vision in solar cell chip screen printing machine

ZHANG Su zhi 1.2, QIN Yu jin2

(1.College Of Electrical And Power Engineering TAIYUAN Uiniversity Of Technology, Taiyuan 030024, China

2.THE Second Research Institute of China Electronics Technology Group Corporation， Taiyuan 030024, China)

Abstract: In order to achieve high calibration precision in vision alignment system of the solar cell printing machine, linear camera model was adopted; high precision calibration plate and high precision active vision platform was used in the calibration system. The active visual calibration method based on orthogonal movement was employed to achieve calibration. Camera linear model and calibration method was explained. The composition of the vision alignment system of the screen printing machine was introduced; the motion process of the alignment platform based on active vision was designed. The active vision plate was moved in accordance to a predesigned movement information table in the calibration process, the image of the target in the calibration plate was taken by the camera after every movement. According to the relationship between captured target information and active vision platform movement distance during each motion of the platform, OPENCV algorithm in MATLAB was applied to solve the inner and outer parameters of the camera linearly, part of the calibration program was showed, and the calibration error was analyzed. And The results indicate that the calibration method base on active vision of orthogonal movement only need several movements of the active vision platform to solve the camera model linearly, it is relatively easy to implement, and able to meet the needs of calibration accuracy.

Key words:  camera calibration; camera model; screen printing machine; calibration method