Design And Development Of A AOI Device Control System For TFT-LCD Electrode Line Defect Detection

In recent years,with the rapid development of electronic information industry,TFT-LCD(Thin Film Transistor-Liquid Crystal Display)technology continues to progress and improve,making the size of LCD-defect down to sub micron level.In order to meet the requirements of high quality and high efficiency of TFT-LCD,AOI(Automatic Optic Inspection)technology has been used in the process of TFT-LCD defect detection.However,the domestic research on the AOI detection of the LCD mainly depends on foreign imports.Therefore,it is very broad application prospect to make up for the lack of TFT-LCD peripheral electrode line defect detection technology,and to realize the automatic detection of TFT-LCD LCD screen.This paper realized the accurate positioning of the magnitude of the micro focus and image acquisition system in motion control system according to industry demand.Then this paper has designed the detection of TFT-LCD peripheral electrode line defect of AOI equipment and research control technology development.The main contents are as follows:Firstly,according to the process flow of AOI for the defect detection of LCD screen,the structure and component of motion control system of AOI equipment are designed,and the motion analysis of four motion axes of the control system is carried out.Then,in order to reduce defects in the error rate,this paper puts forward a method of positioning rotation correction,including the analysis of hardware and algorithm,which could dropped the error rate to less than 0.1%.Then,a UI based on C++ is developed.Secondly,in order to solve the problem of the loss of focus in the image acquisition at the micron level,a high precision PID auto focus double closed loop system based on PLC is proposed.The design of the system structure and the optimization of the PID algorithm are studied.The validity of algorithm is proved by experimented,and detection speed is up to 20 seconds per piece.Thirdly,this paper combined with PSO(Particle Swarm Optimization)and NN(Neural Network)to develop a adaptive PSO algorithm of dynamic perception coefficient combined,in order to carry out parameter tuning of nonlinear PID control system.The experimental results show that the algorithm has good robustness,stable global convergence ability and fast convergence speed.