What are the working principles of LCD screens

- Jun 01, 2018-


 LCD screens are familiar to everyone, and everyday use is also more, but you may not understand the working principle of LCD screens. How to understand them in depth? First of all, you need to know It works, see below for understanding it:

LCD screen


In simple terms, the basic principle of the screen to achieve display is to fill the liquid crystal material between the two parallel plates, and then to change the arrangement of the molecules inside the liquid crystal material by voltage to achieve the purpose of shading and light transmission. Different shades of image are displayed, and as long as a three-color filter layer is added between the two plates, a color image can be displayed.

LCD screen:

The structure of the LCD liquid crystal screen is to place liquid crystal material in two parallel glasses. There are many vertical and horizontal fine wires in the middle of the two glass sheets, and the rod-like crystal molecules are controlled by being energized or not, thus changing. The direction, the light produced by refracting the resulting picture. It is much better than CRT, but its price is more expensive.

Liquid crystal is an organic compound composed of long rod-like molecules. Under natural conditions, the major axes of these rod-shaped molecules are roughly parallel.

The first feature of the LCD is that the liquid crystal must be poured between two flats with fine grooves to work properly. The grooves in the two planes are perpendicular to each other (90-degree intersection). That is, if the molecules in one plane are aligned in a north-south direction, the molecules in the other plane are arranged in the east-west direction and are located in two planes. The molecules between them will be forced into a 90-degree twist. Since light travels in the direction of the arrangement of the molecules, the light is also twisted by 90 degrees when passing through the liquid crystal. However, when a voltage is applied to the liquid crystal, the molecules will be re-arranged vertically so that the light can be emitted directly without any twisting.

The second feature of the LCD is that it relies on polarization filters and the light itself. Natural light is randomly emitted in all directions. Polarization filters are actually a series of increasingly fine parallel lines. These lines form a net that blocks all light that is not parallel to these lines. The lines of the polarizing filter are also exactly perpendicular to the first, so they can completely block those rays that have been polarized.

       Only when the lines of the two filters are completely parallel, or the light itself has been twisted to match the second polarizing filter, light can penetrate. The LCD is composed of such two orthogonal polarizing filters, so under normal circumstances, all the light that tries to penetrate should be blocked. However, because the two filters are filled with twisted liquid crystals, when the light passes through the first filter, the liquid crystal molecules are twisted by 90 degrees, and finally they pass through the second filter. . On the other hand, if a voltage is applied to the liquid crystals, the molecules will rearrange and be completely parallel, so that the light will not be twisted again, so it is just blocked by the second filter. In short, light can be blocked when powered, and light can be emitted without power. Of course, it is also possible to change the arrangement of the liquid crystals in the LCD screen so that light is emitted when it is powered on, and it is blocked when it is not powered.