In order to explain the characteristics of white LED, first look at the lighting source used in the situation. Incandescent lamp and halogen tungsten light, its optical efficiency is 12~24 lumens/watts, fluorescent lamps and HID lamps are 50~120 lumens/watts. Dialogue Light led: In 1998, White LED light efficiency of only 5 lumens/Watts, to 1999 has reached 15 lumens/watts, this indicator is similar to the general household incandescent lamp, and in 2000, white light LED light efficiency has reached 25 lumens/watts, this indicator is similar to halogen tungsten lamp. Companies predict that by 2005, LED light efficiency can reach 50 lumens/watts, by 2015, LED light efficiency is expected to reach $number lumens/watts. At that time the white light led working current can reach the ampere level. This shows that the development of white LED writers with lighting light source, will become a possible reality.
Incandescent and halogen lamps for general lighting, though inexpensive, but light efficiency is low (the heat effect of the lamp consumes electricity), life is short, maintenance work is big, but if use white light led for illumination, not only high light efficiency, and long life (10,000 hours of continuous working time), almost need not maintain.