As a high luminous efficiency, energy saving, long life and easy maintenance light source, has been a lot of night lighting application. But precisely because of their small size, LED, high brightness, PN junction electrical characteristics, etc.

Therefore, the evaluation of the quality of the current LED have many new problems. Evaluation of a quality LED merits, can not be generalized. Because in different situations, on the LED? Goods is not the same performance requirements. For example to display the LED, stress is placed on its brightness, another?,? Color and other parameters. Used for general lighting of the LED, the luminous flux value,? Color, color characteristics and other parameters.

In addition, we have to judge the merits of quality but also from the LED optical, electrical, and thermal radiation safety and life and other aspects of the parameters of a comprehensive evaluation. LED for power type of PN junction temperature from the heat dissipation considerations in order to obtain higher power and LED luminous efficiency, power type LED lighting solution of PN junction temperature and shell heat dissipation is particularly important.

Evaluation of the thermal performance of LED general use of thermal resistance, case temperature, junction temperature and other parameters indicated. Applications for the different LED optical performance from consideration because, as shown with the LED, the visual focus is the visual effects, so the color temperature and color rendering index did not even relevant? Special requirements. In contrast is the white LED lighting is very focused correlated color temperature and color rendering index, because it is the atmosphere and lighting effects to create an important indicator, but the color purity and dominant wavelength generally do not have special requirements.

Currently countries are developing a new LED? Industry standard? And testing methods, LED also available from the flux, the axial luminous intensity, beam angle of half intensity, spectral radiation bandwidth, radiation flux, luminous efficiency, emission peak wavelength, correlated color temperature, color purity and dominant wavelength, color rendering index and other parameters to judge.

Semiconductor light emitting diodes for electrical characteristics of electrical properties from the LED to consider LED’s electrical characteristics of PN junction is one-way non-linear electrical properties, low voltage drive and the characteristics of static sensitive. Unlike traditional sources of electrical characteristics, so the main measurement parameters including forward drive current, forward voltage, reverse leakage current, reverse breakdown voltage and electrostatic sensitivity, etc.. LED light source for the body of biological or radiation safety considerations because LED is a narrow beam, high-brightness light emitting devices, the radiation may be human retinal?

Health hazards, therefore, the International Electrotechnical Commission IEC LED applications for different occasions, provided limits the effective radiation requirements and test methods, which is judged good or bad quality LED an important factor. Among them, the EU and the United States to do LED radiation safety testing mandatory implementation. LED work reliability and length of life, especially as the LCD backlight and LED big screen in these two indicators becomes more important. Our evaluation does not mean the length of LED life to the damage from the use of the available? Period, but rather LED at rated power conditions, the flux attenuation to the provisions of the initial value of the percentage of the duration of the time. The longer the duration, LED lifetime are longer.

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