LCD display is a flat ultra-thin display device composed of a certain number of colored or black and white pixels, placed in front of the light source or reflective surface. LCD displays have low power consumption, making them highly favored by engineers and suitable for electronic devices that use batteries. Its main principle is to stimulate liquid crystal molecules with an electric current to generate points, lines, and surfaces, which are combined with the back light tube to form a picture. The working principle of liquid crystal display: Liquid crystal is a special substance between solid and liquid. It is an organic compound that appears as a liquid under normal conditions, but its molecular arrangement is very regular like that of solid crystals. Therefore, it is named liquid crystal. Another special property of liquid crystal is that if an electric field is applied to it, it will change its molecular arrangement. In this case, if it is matched with a polarizing plate, It has the function of preventing light from passing through (without applying an electric field, light can pass through smoothly). If combined with a color filter and changing the voltage applied to the liquid crystal, the amount of light transmission of a certain color can be changed. It can also be vividly said that changing the voltage at both ends of the liquid crystal can change its transparency (but in reality, this must be combined with a polarizing plate)