The thickness of LCD is generally less than 10 inch. If the desktop system adopts LCD technology, it will save more space. Although LCD display has its attractive originality, it is undeniable that LCD still has some shortcomings in high-quality color display compared with its main competitor CRT display. In addition, the price gap makes LCD still a luxury enjoyed by only a few people. As early as 1888, it was found that liquid crystal, like a metal in a magnetic field, will produce an accurate and orderly arrangement of its molecules when it is influenced by an external electric field. If the arrangement of molecules is properly controlled, liquid crystal molecules will let light pass through. Whether it is a notebook computer or a desktop system, the LCD screen used is a layered structure composed of different parts. The last layer is a backlight layer composed of fluorescent substances, which can emit light. The light emitted by the backlight layer enters the liquid crystal layer containing thousands of crystal droplets after passing through the first polarizing filter layer. The crystal droplets in the liquid crystal layer are all contained in a fine cell structure, and one or more cells constitute a pixel on the screen. When the electrodes in the liquid crystal display generate an electric field, the liquid crystal molecules will be distorted, so that the light passing through them will be refracted regularly, and then displayed on the screen after being filtered by the second filter layer. For a simple monochrome LCD display, such as the display screen used in PDA, the above structure is enough. However, for the more complex color display used in notebook computers, it is also necessary to have a special color filter layer for color display. Generally, in a color LCD panel, each pixel consists of three liquid crystal cells, and each liquid crystal cell has a red, green or blue filter in front of it. In this way, different colors can be displayed on the screen by light from different cells.