| Abstract [eng] |
In this work a brief of the main optical characteristics and parameters of the light sources used in research of LEDs is presented. It includes the following properties: luminous flux, colour temperature, chromaticity, lifetime. An estimation and correction methods and algorithms of variation of the optical characteristics of LEDs found in electrical devices, which require high light quality, is reviewed. The principal characteristics of the research of LEDs are distinguished. The properties of LEDs under investigation are luminous flux, colour coordinates (chromaticity) and current-voltage characteristic. Six types of LEDs, found in modern lighting systems, are chosen for observation. The set consists of amber, lime, cyan, blue and violet colour LEDs. The methodology of LEDs research is formed and experimental work environment, along with equipment, is prepared. The operating mode of LEDs working at 500 mA current in 60 degrees environment (programmable temperature chamber) is set. Under such conditions LEDs ageing is accelerated approximately by a factor of 2. The optical characteristics of LEDs are evaluated ten times at discrete time intervals of 336 hours (2 weeks) using “GL Spectis 1.0 Touch” spectrometer. Results are plotted and luminous flux, where electrical current is 200 mA and 500 mA, approximation and trend line are fitted according to the chosen models. Difference in chromaticity coordinates of LEDs during the investigation is evaluated using statistical means. An example of the effect of variation of LEDs optical characteristics to 1800 K, 2700 K and 6500 K CCT white colour light parameters is provided. |
