The principle of LCD screen

LCD screen, the full name is Liquid Crystal Display. It is a display that utilizes the optoelectronic properties of liquid crystal materials. Its principle is mainly to control the arrangement of liquid crystal molecules by changing the electric field, thereby affecting the transmission of light to achieve the display effect.

First, let us first understand the characteristics of liquid crystal. Liquid crystal is a substance between solid and liquid. Its molecules have a special characteristic – they can rotate but not flow. When an external electric field acts on the liquid crystal, the arrangement of the liquid crystal molecules will change, which will affect the degree of scattering and transmission of light by the liquid crystal, forming the image we see.

LCD screens are mainly composed of the following parts: light source part, light guide plate, LCD panel, and drive circuit part. Among them, the liquid crystal panel is the core part of the LCD.

The working process of LCD screen can be divided into two stages: charging stage and discharging stage. During the charging stage, the backlight emits light and uniformly illuminates the LCD panel through the light guide plate. At this time, the driving circuit applies voltage to the pixel electrodes on the liquid crystal panel, causing the liquid crystal molecules to be arranged in a certain direction, allowing light to pass smoothly and achieving the display effect. During the discharge stage, the drive circuit stops applying voltage to the pixel electrode. At this time, the liquid crystal molecules return to their original state due to the absence of an electric field, blocking the light emitted by the backlight, causing the pixels to appear black.

By continuously and quickly switching between the charging stage and the discharging stage, and controlling the brightness of each pixel (that is, controlling the voltage applied to the pixel electrode), dynamic image display can be achieved. This is the basic working principle of LCD screen.

In addition, in order to improve the display effect and save energy, modern LCD screens also use some advanced technologies. For example, in order to solve the problem that LCD display colors are not as bright as CRT displays, color filter technology is used; in order to improve response speed and prevent the occurrence of smear, frequency doubling technology and vertical scanning technology are used; in order to save energy and extend use lifespan, using LED backlight technology, etc.

In general, the principle of LCD screen is to use the photoelectric properties and electronic control technology of liquid crystal to control the transmission of light by changing the arrangement of liquid crystal molecules, thereby achieving image display. Although the color expression and response speed of LCD screens are slightly inferior to those of CRT monitors, they have become the mainstream personal computers and TV display devices due to their low power consumption, small size, and light weight. In the future, with the development and advancement of technology, the performance of LCD screens will be even higher.

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