Image Sticking is one of critical issue in TFT-LCD, since it affects product quality and also shows technical and manufacturing capability of LCD factory. In this paper, we use 2D-CCD and automatic machine to measure image sticking phenomenon. The different Q-time panels are measured to compare the image sticking level. A simple model is also proposed to evaluate the panel quality in this thesis. we can get the image sticking quantity by this kind measurement and realized the effect of different Q-time.
IntroductionThe liquid crystal displays (LCDs) product has been widely used in human life, including TV, monitor and portable electric products. All companies are trying their best to improve the LCD performance, low power consumptions, viewing angle, response time, etc. However, image sticking phenomenon, the most critical one, has been discussed in plasma display panels (PDPs) and LCDs panel quality for a long time. As we all know, the main cause of the image sticking phenomenon is the generation of residual DC voltage. The distribution of electron charges, such as ion, may be included in LC phase as impurity material in cell process. The impurity quantity has affect the image sticking phenomenon level. In cell process, the array and color filter sheet would have take different Q-time before combination. It may cause the LCD cell have different panel quality.There are many studies focused on several kinds of ions and the behaviors of ions in LC cell [1][2][3]. Masanobu, etc. has study the generation of residual DC voltage [4]. The optical measurement method is easier to get the image sticking phenomenon [5,6]. The traditional method of evaluating the image sticking phenomenon is human eyes detecting. The human eyes is very sensitive to image sticking phenomenon but the results depends on human eyes of each people and hard to get the quantity of it.In this study, we use 2D-CCD to measure image sticking phenomenon [5] and compare the effect of Q-time in LC cell.
Method and ProcessThe measurement equipment in this experiment is MURATest of ELDIM Company. The pattern generator (VG-852) and power supply for drive is used in our experiment. The process of measurement is completely automatically controlled by computer program. It can set different time interval to measure the test panel. The measure environment is fully dark room state at 25℃.We prepare 19inch TN type of different Q-time panel, 10hr, 15hr, 34hr, and 50hr for our experiment. The Q-time is controlled between PI coating and assembling process. 7x7 chessboard (with white L255 and black L0 block pattern)was used as burn-in pattern and L127 pattern is taken as reference one. The test panel is burned for 24 hour, then switch to L127 pattern and measure image sticking decay phenomenon. As Figure 1, we normalize the measured data to get the image sticking phenomenon. In order to reduce the edge mura effect, we choose the 3x3 block in panel to analysis the image sticking quantity. Figure 2 show the area which we choose and calculate its decay level.We normalized...