LED judge the quality of the merits of the several factors
 
LED as a light-emitting efficiency, energy saving, long life, easy to maintain the light source, has been in a lot of night lighting application engineering. LED, however it is precisely because of its small size, high brightness, PN junction characteristics, such as electrical characteristics, the LED current in the evaluation of the quality of many new problems. Judge the merits of a quality LED, can not be generalized. Because in different applications, LED products on the different performance requirements. For example, to display the LED, its brightness value, the distribution perspective, color and other parameters. Used for general lighting of the LED, the luminous flux value, color, characteristic parameters such as color. In addition, we have to judge the quality of LED advantages and disadvantages but also from the optical, electrical, and thermal radiation safety and life in several areas such as evaluation parameters.

LED for power type of PN junction temperature from the cooling performance considerations

In order to obtain a higher LED luminous efficiency of the power and resolve the power-type LED lighting of the PN junction temperature and the cooling housing problem is particularly important. Evaluation of the thermal performance of LED thermal resistance tends to be used, the shell temperature, junction temperature and other parameters.

LED for the different applications considered from the optical properties

Due to be used as the LED, focused on the intuitive visual effects, so the color temperature and color index no special requirements. The opposite is the white LED lighting with a strong emphasis on the related 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 in general there are no special requirements. At present, countries are to develop new LED industry standards and testing methods, LED luminous flux can also be axial luminous intensity, the beam half-intensity angle, spectral bandwidth of radiation, radiation flux, luminous efficiency, light emitting peak wavelength, related to color temperature and color purity and dominant wavelength, color-rendering index and other parameters to judge.

Semiconductor light-emitting diode electrical characteristics of electrical properties from the LED to consider

LED electrical characteristics of the PN junction is a one-way non-linear electrical properties, low-voltage drive, as well as features such as static sensitive. Unlike traditional sources of electrical characteristics, so the main parameters, including positive drive current, forward voltage drop, reverse leakage current, reverse breakdown voltage and sensitivity, such as static.

LED light source for the body of biological or radiation safety considerations

Since the LED is a narrow beam, high-brightness light-emitting components, the radiation may harm the human eye retina, therefore, the International Electrotechnical Commission IEC applications on different occasions for the LED provides an effective radiation limits its requirements and testing methods, which is judged LED quality an important factor in the pros. Among them, the European Union and the United States radiation safety testing LED to do the implementation of a mandatory requirement.

LED reliability and length of life

In particular the LED as a backlight and the LCD screen on the two indicators is even more important. We evaluated the length of the life span of LED does not mean that the damage from the use of available cycles, but the power LED at rated conditions, the flux attenuation to the provisions of the initial value by the percentage duration. The longer the duration, LED longer life expectancy.