To improve the luminous efficiency and the power of LED used for lighting is one of the key problems of the industrial development at present. At the same time, the and shell heat dissipation problems are particularly important. Generally we use the led thermal resistance , shell temperature and junction temperature to represent.
At present, the International Electrotechnical Commission (IEC) conducts radiation safety tests(Electrical Safety) and verification on LED products which is equal to the requirements of the semiconductor laser. For LED is luminescent device of narrow beam, high brightness shine and considering the radiation may be harm to the human eye retina, LED for different occasions of application, international standard lies down rules for the efficient radiation limits requirements and testing method. Now in the European Union and the United States, the radiation safety of LED products for lighting is considered as a mandatory safety requirements.
Reliability index is measured by the normal working ability of LED in various conditions. It is particularly important in the liquid crystal backlight and big screen display. Led life is the evaluation quality index of available period of LED products. It is usually represented by effective life or end life. In lighting applications, the effective life means the duration of the time when LED is in rated power conditions, the led life attenuates to the provisions of the percentage of the initial value.
LED (LED test) has the characteristics of small luminous surface, narrow beam and high brightness which determines the specific characteristics of led light measurement. In order to deal with the particularity of the problem, CIE respectively established two technical committees“TC2-45 LED light measurement” and “TC2-46 CIE/ISO LED testing standard”. CIE TC2-34 group held a meeting in Vienna headquarters in October of 1997 and developed and recommended the CIE 127 1997 LED light measurement standards, it involves LED radiate emittance, the luminosity and color measurement(colorimeter). But in recent years because of the rapid development of LED lighting technology, especially the white LED products used for lighting, many problems have not been considered in the past. Therefore, in Japan in 1999, at the annual CIE meeting of the Tokyo, the representatives of the developed countries suggests that CIE TC2-34 formulates the standards white LED lighting appliance, Japanese delegation also submitted two draft standards for the white LED used for the general illumination (luminance meter)