LCD technology involves filling liquid crystals between two planes with thin grooves. The grooves on these two planes are perpendicular to each other (intersecting at 90 degrees). That is to say, if molecules on one plane are arranged in a north-south direction, then molecules on the other plane are arranged in an east-west direction, and molecules located between the two planes are forced into a 90 degree twisting state. Due to the fact that light propagates in the direction of molecular arrangement, it is also twisted 90 degrees when passing through liquid crystals. When a voltage is applied to the liquid crystal, the liquid crystal molecules will rotate, changing the light transmittance and achieving multi grayscale display.
LCD usually consists of two polarizers that are perpendicular to each other. The function of a polarizer is like a fence, blocking the light wave components as required. For example, blocking the light wave components perpendicular to the polarizer fence and only allowing the light wave components parallel to the fence to pass through. Natural light diverges randomly in all directions. Two polarizers perpendicular to each other should, under normal circumstances, block all natural light attempting to penetrate. However, due to the twisted liquid crystal between the two polarizers, after the light passes through the first polarizer, it will be twisted 90 degrees by the liquid crystal molecules and finally exit from the second polarizer.
