As a kind of the third generation of light source, LED performance indexes including the light and electrical parameters of electric light source. Electrical parameters of voltage, current, power, namely due to the LED is a dc drive, and the voltage and current are dc, thus performance index is, but the LED relationship is not linear relationship between the current and voltage.
parameters include light with the light energy, spectrum energy release, the chromaticity coordinates and display index ( The white light) And spatial distribution of light intensity, etc. The definition of these parameters as light source. Monochrome leds is narrow band spectrum, and its spectrum bandwidth for 20 - commonly 35 nm, and white LED varies according to the mechanism of the output spectrum. LED light output and encapsulation structure is directly related to the spatial distribution, display with LED general output Angle is small, light and LED lighting generally output light Angle is bigger.
LED light output is highly affected by the temperature, thus the temperature curve of output flux is very important. LED as light source, life is weight indicator, the theory of life for more than 100000 h, but the actual LED because of reasons of chips and the packaging, it is difficult to achieve the theoretical value.