The commonly used light sources in backlight module are el, CCFL, led, etc. EL light source is a kind of surface emitting body with uniform brightness and low power consumption, but it has short life, low brightness and poor emission spectrum. At present, El back source is only suitable for small LCD products such as mobile phones, monochrome PDAs and so on, which are less than 4 inches. CCFL light source is a kind of linear light source, which has the advantages of high luminous efficiency, high brightness, long service life, simple structure, easy bending and low price. Although the technology of CCFL has been very mature, the high starting voltage of CCFL light source and the presence of heavy metal mercury in the filler restrict its further application. With the advent of the era of energy saving and environmental protection, LED light source has emerged to replace CCFL. LED backlight has the following advantages:

(1) Good color rendering. Compared with CCFL backlight, LED backlight has better color gamut, color saturation can reach 105% ~ 120%, which is much larger than 65% ~ 75% of CCFL backlight. It has stronger color expression and can make up for the defect of less color quantity in liquid crystal technology.

(2) Long life. The service life of LED can be as long as 100000 hours, which is 2-5 times of CCFL. According to the working time of 10 hours per day, LED can work continuously for 27 years, which can increase the service life of products to a certain extent.

(3) Energy saving and environmental protection. LED energy consumption is small, and does not contain harmful components such as heavy metals, so it is more environmentally friendly. Therefore, with the improvement of people's awareness of energy conservation and environmental protection and the requirements of image display quality, LED has a broader application prospect than CCFL.