Liquid crystal display is an optoelectronic display device based on liquid crystal technology. It is a display technology widely used in modern consumer electronics products, including TVs, computer monitors, smart phones, tablet computers, etc. The working principle of LCD can be divided into two stages: electric field control and optical change.

 

Electric field control stage:

 

A liquid crystal display consists of a liquid crystal layer and a backlight. Liquid crystals are composed of molecules, and the molecules present an arrangement structure, presenting an orderly state, and the arrangement rule that it presents has a specific direction. When an electric current is passed through the liquid crystal molecules, they change their alignment and shape. At this time, an electric field is applied to the liquid crystal molecules, and the arrangement of the liquid crystal molecules will change under the action of the electric field, so that the light will be deflected when passing through the liquid crystal layer to achieve the display effect. Liquid crystal molecules have two states: twisted and parallel. The basic unit of a liquid crystal display is a "pixel". Each pixel is composed of a liquid crystal molecule. When different colors are displayed, there will be three polarization filters inside the pixel, which are red, green, and blue. Because liquid crystal molecules have different molecular arrangements under the action of different electric fields, light transmission effects are also different under different liquid crystal molecular arrangements inside the pixel through the action of an electric field, thereby forming a color change.

 

Optical change stage:

 

Under the illumination of the backlight source of the liquid crystal display, the light passing through the liquid crystal layer will be deflected, and the pixels of different colors will display different colors through the polarizing filter. Inside each pixel, the strength of the charge in the activation electric field can adjust the orientation of the liquid crystal molecules, thereby controlling the degree of light transmission and forming an image. Under the action of an electric field, liquid crystal molecules can cause light to undergo refraction, reflection, absorption and other behaviors when passing through, and complete the display of the liquid crystal display.

Generally speaking, the working principle of liquid crystal display is to use the synergistic effect of special liquid crystal molecules, polarization filters and backlight to respond to changes in electric field and reflect different optical changes to form different changes in chromaticity and brightness. Thus, the display function of the display screen is realized. The disadvantage of liquid crystal display technology is that it needs a backlight, and the display effect may not be as good as that of OLED displays. However, due to its low manufacturing cost and good stability, it is still one of the mainstream display technologies widely used in consumer electronics products.