How the LCD works

March 17, 2017

    Simply put, the basic principle of screen display is to fill liquid crystal material between two parallel plates. The arrangement of molecules in the liquid crystal material is changed by voltage to display different shadows and uniform images, so as to achieve the purpose of shadow and translucency. In addition, a color image can be displayed by adding a tri-color filter layer between the two plates.


     Only understand its structure, principle and technology, craft characteristic, ability has clear target of choose and buy, ability makes use and maintain more scientific and reasonable. Liquid crystals are organic compounds made up of long rod-shaped molecules. In nature, the long axes of these rod-like molecules are roughly parallel. The first feature of an LCD is that, in order to work properly, liquid crystals must be injected between two planes with thin grooves. The gaps in the two planes are perpendicular to each other (90 degrees intersecting), that is, if the molecules in one plane line up north-south and the molecules in the other plane line up east-west, the molecules in between the two planes are forced into a 90-degree distortion. When light travels in the direction of the molecular alignment, it also reverses by 90 degrees as it passes through the liquid crystal. But when a voltage is applied to the liquid crystal, the molecules rearrange themselves vertically so that light can be directed away without distorting.
A second feature of LCDS is that they rely on polarized filters and light itself, which scatters natural light randomly in all directions. A polarization filter is actually a series of parallel lines that get thinner and thinner. These lines form a network to block all light rays that do not line the lines.


     The line of the polarized filter is just perpendicular to the first line, so polarized light can be completely blocked. Light can only penetrate if the lines of the two filters are perfectly parallel, or if the light itself is distorted to match the second polarizing filter. On the one hand, an LCD consists of two polarizing filters that are perpendicular to each other, so under normal circumstances all light trying to pass through should be blocked.

      However, due to the distortion of the liquid crystal between the two filters, when light passes through the first filter and finally through the second filter, the liquid crystal molecules will be distorted by 90 degrees. On the other hand, if a voltage is applied to the liquid crystal, the molecules rearrange themselves and become perfectly parallel, so that the light is no longer distorted and is therefore blocked by a second filter. In short, light will be blocked by the addition of electricity, light will be emitted without the addition of electricity. Of course, it can also change the alignment of the liquid crystals in the LCD so that they glow when the power is on, but not blocked when it is on. But because the LCD screen is almost always on, only the "power will block out the light" scheme achieves the most energy savings.