The backlight layer is actually the structure of the backlight source and the light guide plate, which is actually the lamp tube or light-emitting diode that can emit white light. The backlight source is mostly an LED light source now. Because liquid crystal molecules don't emit light on their own, LCD screens need special light sources to produce images, which are then deflected by the molecules to produce different colors. And what backlighting does is provide light energy. After the light is emitted by the lamp tube, the light is distributed by the light guide plate, and the direction of all the light is concentrated towards the liquid crystal molecules through the reflective plate on the back. Finally, the light is distributed evenly through the diffusion plate (or light guide plate) to avoid the central brightness being too high and the surrounding brightness being too low.
In the backlight structure, it mainly plays the role of correcting the diffusion angle, which will increase the optical radiation area but reduce the light intensity per unit area, that is, the brightness. After the light source is diffused by the diffusion material, the area can become larger, and the uniformity is better.
The prism film is placed between the diffusion plate of the backlight source and the LCD panel. It can converge the light from the diffusion plate uniformly diverging to all angles to the axial angle, that is, the front angle, so as to improve the axial brightness without increasing the total luminous flux. If the diffuser or prism film is locally damaged, the derived light will have problems, resulting in white spots on the screen.
The function of the polarizer is to let light pass through in a single direction. The polarizer layer is made of PVA film after dyeing and stretching, which is the main part of the polarizer, also known as the original polarizer film. It determines the polarizing performance and transmittance of the polarizing plate and also affects the tone and optical durability of the polarizing plate.
The glass substrate is not only two pieces of glass; it has a groove structure on the inside, and the orientation film is attached, which can make the liquid crystal molecules neatly arranged along the groove. TFT thin-film transistors and color filters are attached to the upper and lower layers of glass. Between the two layers of glass is the liquid crystal layer.
We often say TFT-LCD, which actually refers to this thin film transistor. Its function is like a switch; TFT can control the signal voltage on the IC control circuit and transfer it to the liquid crystal molecules to determine the size of the liquid crystal molecules deflection angle, so it is a very important component.
The liquid crystal molecular layer is the most important element to change the polarization state of light, and its arrangement and polarization state are determined by electric and elastic forces.
Light deflected by liquid crystal molecules can only show different shades of gray but cannot provide the three primary colors of red, green, and blue (RGB). Color filters, however, consist of three RGB filters, which are mixed to adjust each color and brightness. Each pixel in the LCD panel is composed of three dots: red, green, and blue, and each dot has a different gray level. Filters are made of plastic or glass with special dyes; red filters only let red light through, and so on. The transmittance of a glass sheet was originally similar to that of air, and all colored light could pass through it, so it was transparent. However, after dyeing dye, the molecular structure changed, the refractive index also changed, and the passage of some colored light changed. For example, when a white light passes through a blue filter, it emits a blue light, while very little green or red light is absorbed by the filter.
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