Production Process for Liquid Crystal Display Panels
For TN (twisted nematic) LCD panels, which primarily use liquid crystal material with positive magnetic susceptibility, electrodes are placed on either side of the liquid crystal substrate layer. When voltage is applied and the electric field is created, the liquid crystal molecules line up parallel to the electric field, producing the inclination to align vertically. For MVA LCDs, which primarily use liquid crystal material with negative magnetic susceptibility, electrodes are placed on either side of the liquid crystal layer. Once the voltage is applied and the electric field is created, the LC molecules orient themselves 90 degrees to the electric field, and the LC molecules become inverted. For IPS LCD panels, which mainly use liquid crystal material with positive magnetic susceptibility, paired electrodes are placed on one side. When an electric field is created the liquid crystal molecules orient themselves parallel to the electric field and rotate on the same plane.
With TN LCD panels, the image produced will vary from different viewing angles; variations in brightness and even grayscale inversion are all typical of TN LCD panels. Thanks to mutual compensation alignment, MVA LCD panels produce an image that does not vary with different viewing angles – and there’s no risk of grayscale inversion. With IPS, paired electrodes are placed on the side of the substrate making the current run parallel with the material. This technology aligns the liquid crystal parallel to the front screen, thereby increasing the viewing angle.
Three Major Steps in the TFT-LCD Production Process
Array
– The front-end Array process is similar to that for semiconductors, the only difference being that the thin-film transistors are placed on the glass substrate, not on the silicon wafer.
Cell
– The Cell process fits the Array substrate to a color-filter substrate; liquid crystal is then inserted between the two substrate layers.
Back-end Module Assembly
– Back-end Module Assembly involves taking the panel from the Cell process and bonding the LCD driver IC, and assembling backlights, metal frame, and other components to make the finished product.
