LED lighting quality standards
From the current structure and the industrial development perspective, LED lighting products need to mainly consider the parameters of optical properties, electrical properties, thermal properties, radiation safety, lifetime and other aspects.
Optical Performance: This mainly relates to the performance requirements of spectrum, luminosity and colorimetric, etc. According to the newly established industry standard," semiconductor light-emitting diode test methods" includes the emission peak wavelength , spectral radiation bandwidth axial luminous intensity , beam angle of half intensity , luminous flux, radiant flux , luminous efficiency , chromaticity coordinates, correlated color temperature, color purity and dominant wavelength , color rendering index and other parameters. LED, as for display, is the direct effect of vision. So the correlated color temperature and color rendering index is not required. However, these two parameters are particularly important to the lighting of the white LED, they are the significant quotas of lighting atmosphere and effect, but the color purity and dominant wavelength generally not required.
Electrical properties: The electrical characteristics of the PN junction differ LED from traditional light sources in the electrical properties, namely unidirectional nonlinear conduction characteristics, low voltage drive and sensitive to static electricity and so on. At present the main measurement parameters includes forward drive current, forward voltage drop, reverse leakage current, reverse breakdown voltage and electrostatic sensitivity and so on.
Thermal Performance: It is one of the key issues for currently LED industrial development to improve luminous efficiency and power. At the same time, LED PN junction temperature and the shell heat problem is particularly important, usually expressed with thermal resistance, case temperature, junction temperature and other parameters.
Radiation Safety: Currently, the International Electro technical Commission (IEC) equates to the LED lighting with the semiconductor laser in safety testing and demonstration of radiation. Because LED is a narrow beam, high- brightness light-emitting device, its radiation may harm the retina of the human eye. Therefore , for different occasions of the LED application, International Standard specifies its effective radiation limits and testing methods . At present in the EU and the U.S., the radiation safety of LED lighting products, is implemented as a mandatory safety requirements.
Reliability and life: Reliability index measures the ability to work of LED lighting in various environments. It’s very important in liquid crystal display backlight and the large screen display. Lifetime is the quality indicator to evaluate the cycle availability of LED products available indicators, usually represented by the useful life or the end of life. In lighting applications, the useful life means the duration that, at rated power conditions, the flux decays to the specified percentage of the initial value.