Parameters of white LEDs respecting operational conditions

Abstract

IntroductionUsing of white LEDs (Light Emitting Diodes) for general lighting is on rise. It is caused by several factorscontinuously decreasing prices of LEDs, variable construction designs of luminaires, LED luminaires are suitable for implementation to advanced lighting systems due to their good controllability and others. But this rise brings new challenges for both researchers and manufacturers in the area of understanding the behaviour of LED parameters under real operating conditions. Current state of light parameters stability research is mostly focused on decrease of luminous flux during lifetime and influence of junction temperature on luminous flux. However using white LEDs especially for general lighting is conditioned by fulfilling of other parameter limits -operating voltage, luminous efficacy, colour rendering index, chromaticity temperature. Therefore the data based on spectral distribution changes of white LEDs respecting possible operational conditions are much more convenient for evaluation of possible influences on LED light sources.