Precision position control for pcb screen printer using image processing technique

Abstract

In this paper, a precision position control system of PCB (Printing Circuit Board) screen printer incorporating image processing technique is introduced. Two fiducial marks on the PCB are used as the sensing points for the image processing to recognize the position errors in directions of coordinates. The precise alignment device is composed of tables. These tables are controlled by three stepping motors which are driven by 80C196KC microprocessor based controller. Two CCD cameras with ultraviolet ray type of light source are used to capture the image of two fiducial marks. The centers of the fiducial marks are obtained by a least square error method. The effectiveness of this precision position control system is proved through applying for a practical PCB screen printer. It realizes the precision about 2.5m in position control of tables, and the high speed processing time about 1 second.