As the name suggests, the liquid crystal display uses "liquid crystal" as the material of the display, so what is liquid crystal? In fact, liquid crystal is a substance between solid and liquid. When heated, a transparent liquid will appear, and when cooled, it will crystallize into a chaotic solid state. Liquid crystal is an organic compound with regular molecular arrangement. Liquid crystals can be divided into three types according to their molecular structure: clay-like smectic liquid crystals, nematic liquid crystals (similar to thin matchsticks), and cholesterol-like cholesteric liquid crystals. The physical properties of these three kinds of liquid crystals are not the same, because the second type of scintillation liquid crystal in the liquid crystal display screen has long rod-shaped molecules. In the natural state, the long axes of these long rod-shaped molecules are roughly parallel.
With the deepening of research, people have begun to grasp many other properties of liquid crystals: when the liquid crystal is energized, the liquid crystal molecules are arranged in an orderly manner, allowing light to pass through easily; with or without electricity, the liquid crystal can block or allow light to pass through like a door. In this way, the two states of light can be controlled, which is the premise of the LCD screen to form an image. Of course, it also needs to cooperate with a certain structure to realize the conversion of light to image. Let's take a look at the original monochrome LCD screen first.
Liquid crystal clear principle
LCD screens come in many different structures, but the principles are basically similar, so let's take an example.
TN (Twisted Column) is a monochrome LCD panel that contains two fairly sensitive sodium-free glass materials called columns with a layer of liquid crystal in the middle, structured like a "sandwich" We focus our attention on the middle layer, the liquid crystal layer , the liquid crystal not only flows into the middle layer, but flows into the two inner ridges of the middle layer, which are basically like this. The alignment of the liquid crystal molecules is precise, because without precise alignment, light cannot pass through the liquid crystal part smoothly. In order to achieve the effect of neat alignment, with these fine alignments, the liquid crystal molecules will line up along the grooves, and the grooves are very parallel, so the molecules are also completely parallel.
We usually call it the upper and lower layers, the upper and lower layers are neatly arranged, and the liquid crystal molecules are neatly arranged, but the arrangement direction is different. . In the production process, the upper and lower (90 degrees vertical) overlap, that is, the arrangement of the upper liquid crystal molecules is horizontal, and the arrangement of the lower liquid crystal molecules is vertical. The liquid crystal molecules are aligned vertically.
On the whole, the arrangement of liquid crystal molecules is like a helical evolution, and the key to the evolution is the interlayer between molecules. A key device called a polarizing filter is set in the interlayer, which arranges and transmits light at the same angle as the stripes in the upper and lower interlayers, assuming that under normal conditions, when the light goes from top to bottom, usually only Light that penetrates an angle, passes through the upper filter and enters the grooves of the upper interlayer, and then forms a passage from the lower filter by setting the twisted channels of the liquid crystal molecules. Completely penetrates light. Once these liquid crystal molecules are driven by the electrodes, due to the action of the external voltage, the liquid crystal molecules are no longer aligned in the normal way, but are aligned vertically, so the light cannot pass through; resulting in black on the screen. This creates white light transmission (ie when the power supply is not working), when can't speak (when the power supply is not working), the characters can be displayed on the screen, which is the simplest display principle. Seeing this, you may ask, why is the LCD screen opaque when it is powered on? Since the screen works under normal conditions, it is not transparent to light, and the energy reduction adjustment is effective.
LCD liquid crystal display light principle - liquid crystal interlayer
2022 07/05