The backlight unit (BLU) is a key component for the light source on the back of the LCD display. The LCD liquid crystal panel itself does not have light-emitting characteristics. Therefore, a light-emitting source must be added to the LCD liquid crystal panel to display. Generally speaking, the liquid crystal backlight module is composed of backlight, optical film, adhesive products, insulation products, plastic frame and other components. Among them, the optical film is one of the key components of the backlight module. According to its role, it can be divided into a diffusion sheet, a reflection sheet, a light guide plate, a prism sheet, and a lamp tube reflection cover. From the perspective of technological development, LCD development trends include large screens, high definition, using LED backlights instead of CCFL backlights, ultra-thin, wide color gamut, support for 3D display, and intelligentization, but these development trends will not Change the basic backlight display principle and structure of LCD. Therefore, LCD uses its advantages of small size, light weight, no radiation, no dazzling, anti-interference, anti-shock, large display angle, etc., becoming the current mainstream display technology.