STN and TN

The display principle of STN type is similar to that of TN. The difference is that the liquid crystal molecule of TN torsional nematic field effect rotates the incident light by 90 degrees, while STN super-torsional nematic field effect rotates the incident light by 180~270 degrees.

It must be pointed out here that the pure TN liquid crystal display itself only has light and dark two situations (or black and white), and cannot achieve the color change. Due to the relationship between liquid crystal materials and the interference of light, the color of STN LCD is mainly light green and orange. However, if a color filter is added to the traditional monochrome STN LCD, and any pixel of the monochrome display matrix is divided into three sub-pixels, which will display the three primary colors of red, yellow and blue through the color filter respectively, and then the color ratio of the three primary colors is adjusted, the color mode can also be displayed.

In the small mesh circuit on the conductive glass of TFT liquid crystal display, the electrodes are matrix switches arranged by thin-film transistors, and each circuit intersects with a corresponding control box. Although the driving signal sweeps through the display points quickly, only the selected display points in the transistor matrix on the electrode can obtain a voltage sufficient to drive the liquid crystal molecules. This causes the molecules of the liquid crystal to pivot and form a "bright" contrast, whereas the unselected display points are naturally a "dark" contrast. This also avoids the dependence of display function on the electric field effect of liquid crystal.

TFT type liquid crystal display is more complex, mainly composed of: fluorescent tube, light guide plate, polarizing plate, filter plate, glass substrate, directional film, liquid crystal material, thin mode transistor and so on. First, LCDS must project light from a backlight, or fluorescent tube, which passes through a polarizing plate and then through the liquid  crystal. The molecules of the liquid crystals are arranged in such a way that they change the Angle of light passing through the liquid crystals, which then have to pass through a coloured filter and another polarizer in front of them. Therefore, we can control the intensity and color of the final light as long as we change the voltage value of the liquid crystal, so that we can change the color combination with different tones on the liquid crystal panel.

Each pixel of a TFT-LCD is controlled by a TFT integrated on itself, and they are active pixels. Therefore, not only the reaction time can be greatly accelerated, at least to about 80ms; Contrast and Brightness are also greatly improved; At the same time, the Resolution has been improved unprecedentedly. Because of its higher contrast and richer colors, the screen updates faster, so we call it true color.