Detailed explanation of the working principle of LCD display

To put it simply, the basic principle of screen display is to fill liquid crystal material between two parallel plates, and use voltage to change the arrangement of molecules inside the liquid crystal material to achieve the purpose of shading and transmitting light to display different depths and staggered colors. Color images can be displayed by adding a three-color filter layer between two flat plates.

Only by understanding its structure and principles, as well as its technical and process characteristics, can we make a targeted purchase and be more scientific and reasonable in application and maintenance. Liquid crystal is an organic compound composed of long rod-shaped molecules. In their natural state, the long axes of these rod-like molecules are roughly parallel.

The first characteristic of dot matrix LCD is that the liquid crystal must be filled between two planes with fine grooves to work properly. The grooves on these two planes are perpendicular to each other (intersecting at 90 degrees). That is to say, if the molecules on one plane are arranged north-south, the molecules on the other plane are arranged east-west, and the molecules located between the two planes are Forced into a 90-degree twist. Since light travels in the direction of the arrangement of molecules, the light is also twisted 90 degrees when passing through the liquid crystal. But when a voltage is applied to the liquid crystal, the molecules will rearrange themselves vertically, allowing light to shine directly without any twisting.

The second characteristic of LCD screen is that it relies on polarized light sheets and light itself. Natural light radiates randomly in all directions, and polarizing filters are actually a series of increasingly thinner parallel lines. These lines form a net that blocks all light rays that are not parallel to these lines. The lines of the polarizing filter are exactly perpendicular to the first one, so they completely block the light that has been polarized. Only if the lines of the two filters are completely parallel, or the light itself has been twisted to match the second polarizing filter, can the light pass through.

On the one hand, the custom LCD screen is composed of two mutually perpendicular polarized light-extinguishing sheets, so under normal circumstances it should block all light trying to penetrate. However, since the space between the two filters is filled with twisted liquid crystal, the light will be twisted 90 degrees by the liquid crystal molecules after passing through the first filter, and finally pass through the second filter. On the other hand, if a voltage is applied to the liquid crystal, the molecules will rearrange and become completely parallel, so that the light is no longer twisted, so it is blocked by the second filter.

In short, applying electricity will block the light, while not applying electricity will cause the light to emit. Of course, the arrangement of the liquid crystals in the LCD can also be changed so that light is emitted when powered and blocked when not powered. However, since the LCD screen is almost always on, only the solution of "powering up to block the light" can achieve the most power-saving purpose.