SSL refers to a type of lighting that uses semiconductor light-emitting diodes (LEDs), organic or polymer light-emitting diodes (OLED / PLED) as sources of illumination rather than electrical filaments, plasma (used in arc lamps such as fluorescent lamps), or gas. SSL applications are now at the doorstep of massive market entry into our offices and homes. This penetration is mainly due to the promise of an increased reliability with an energy saving opportunity: a low cost reliable solution.
Per today, commercial claims for LED-based products in terms of lumen maintenance are fully based on LM80 data and TM-21 extrapolations. The lumen maintenance life is defined as the time when the maintained percentages of the initial light output fall below a failure threshold. There may be a risk in doing this as TM-21 only relies on the behavior of the average LED degradation, instead of taking into account the degradation of all individual LEDs. A more profound statistical analysis is required to make the step from TM-21 extrapolation to lumen maintenance on product level.
Willem van Driel (Philips Lighting) and CQM consultant Marc Schuld analyzed several LM80 data sets from a statistical point of view and reviewed the different approaches currently available to perform lumen maintenance extrapolations.
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