In the TN and STN LCD screens, a method of simply driving electrodes is used. They are all driven by the cross method of X and Y axes, as shown in the figure below, so if the LCD screen displays part If you want to get bigger and bigger, then the reaction time of the electrode in the center part is likely to be longer. In order to make the screen display consistent, the overall speed will be slower. To put it simply, it is as if the update frequency of the CRT LCD screen is not fast enough, then the user will feel the screen flickering and beating; or if it is said that when fast 3D animation is required, the display speed of the LCD screen is not If you cannot keep up, the displayed image may be delayed. Therefore, the early LCD screens have certain limitations in size, and they are not suitable for watching movies or playing 3D games.
In order to improve this situation, in the later liquid crystal display technology, an active matrix method was used to drive the liquid crystal screen. This is now an ideal device to achieve high data density liquid crystal display effects, and its resolution is extremely high. The method is to use the silicon transistor electrode made of its thin film technology, and use the scanning method to select any one of the display points (pixel) on and off. This actually uses the non-linear function of the thin film transistor to replace the non-linear function of the liquid crystal which is difficult to control. As shown in the figure above, in the TFT LCD screen, some small lines of conductive glass are grid-shaped, and the electrodes are matrix switches arranged by thin-film transistors. There will be a control box where each line intersects, although the drive The signal will quickly scan through each display point, but only the selected display point in the transistor matrix on the electrode can get enough voltage to drive its liquid crystal molecules, so that the liquid crystal molecular axis turns and becomes a "bright" contrast. The display points that are not selected are naturally "dark" contrasts, thus avoiding the dependence of the display function on the ability of the liquid crystal electric field effect.
