TN type liquid crystal display principle

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TN type liquid crystal display principle [Copy link]

TN-type liquid crystal display principle

TN-type liquid crystal display technology can be said to be the most basic among liquid crystal displays, and other types of liquid crystal displays can be said to be improved based on the TN type. Similarly, its operating principle is simpler than other technologies. Please refer to the picture below. The figure shows a simple structural diagram of a TN-type liquid crystal display, including vertical and horizontal polarizing plates, an alignment film with fine grooves, a liquid crystal material, and a conductive glass substrate. Without an electric field, the incident light passes through the liquid crystal layer after passing through the polarizing plate. The polarized light is rotated 90 degrees by the liquid crystal layer where the molecules are twisted and arranged. When leaving the liquid crystal layer, its polarization direction is exactly the same as the direction of the other polarizing plate, so the light can pass smoothly and the entire electrode surface is bright. When an electric field is added, the optical axis of each liquid crystal molecule turns to be consistent with the direction of the electric field, and the liquid crystal layer loses its ability to rotate light. As a result, the polarized light from the incident polarizer is perpendicular to the polarization direction of the other polarizer and cannot pass through, so the electrode surface appears dark. The imaging principle is to place the liquid crystal material between two transparent conductive glasses attached to the polarizers with perpendicular optical axes. The liquid crystal molecules will rotate and arrange in sequence according to the direction of the fine grooves of the alignment film. If the electric field is not formed, the light will smoothly enter from the polarizer, rotate according to the direction of the liquid crystal molecules, and then emit from the other side. If the two conductive glasses are energized, an electric field will be generated between the two glasses, which will affect the arrangement of the liquid crystal molecules between them, causing the molecular rods to twist, and the light will not be able to penetrate, thereby blocking the light source. The phenomenon of light-dark contrast obtained in this way is called twisted nematic field effect, abbreviated as TNFE (twisted nematic field effect). The liquid crystal displays used in electronic products are almost all made using the twisted nematic field effect principle.