The luminous principle of white LED is that after the PN junction emits blue light, part of the blue light irradiates the phosphor and emits yellow light, and the blue light penetrating the phosphor and the yellow light recover white light. Because the phosphor coating technology has not yet passed the standard, the LED emits blue light or yellow light, and similar light colors will be selected for factory inspection. In other words, LED is a two-color light source, not a three-color light source, which is very irritating to human eyes. It is a mistake to use it as an eye protection lamp. The correct eye protection lamp should use tricolor energy-saving lamps with a color temperature of about 4500, and then choose the power and illumination according to the purpose, that is, lumen finger.