Influence of the injection current on the degradation of white high-brightness light emitting diodes

Bouchard, Sébastien; Lemieux, Hugo; Côté, Marie‐Pier; Thibault, Simon

doi:10.1117/12.838612

Cited by 3 publications

(2 citation statements)

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“…Even if there are many researchers studying these phenomena, they are not well understood, especially luminosity degradation. Though it seems that this degradation rises with current and temperature, its relation with these parameters is not clear and seems to change for different manufacturers [5]. This degradation and our lack of understanding cause three problems with LEDs: too much luminosity at the beginning, difference in luminosity between lamps and uncertainty about when the lamp's luminosity falls below minimum requirements.…”

Section: Introductionmentioning

confidence: 90%

“…Furthermore, with their small size, fast response time [4] and directionality, it is possible to combine them together and with secondary optics to achieve a superior level of design to increase their efficiency and reduce certain problems, such as light pollution. Unfortunately, beside their high initial cost, LEDs have a serious drawback, which is luminosity degradation over time [5][6]. They also have a color shift, but it is a less important problem for street lighting.…”

Section: Introductionmentioning

confidence: 99%

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LED luminaire longevity strategy models comparison

Lemieux

Thibault

Martel³

2010

SPIE Proceedings

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As energy efficiency becomes more and more important, light-emitting diodes (LEDs) are a promising alternative to traditional lighting. Indeed, the energy efficiency of LEDs is still improving as their luminosity is modulated by current. Moreover, for applications such as exterior lamp posts, their small size, directionality, colors and high frequency response allow to combine them and provide design possibilities which are impossible with any other light source. However, as any lamp, LEDs have a lumen depreciation which is a function of both current and temperature. Thus, to take advantage of the full characteristics of LEDs, LED luminaire longevity strategies must be carefully studied and planned, especially since the IES and CIE guidelines state clearly that the luminaire must maintain the rated recommended light level until the end of the system's operating life. The recommended approach for LED luminaire specification is therefore to use the end-of-life light level when evaluating the luminaire. Different power supply strategies have been simulated to determine which one maximizes energy saving and lifetime. With these results, it appears that active control can save at least 25% in energy, but the best strategy cannot be determined because of uncertainties in luminosity degradation models.

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Section: Introductionmentioning

confidence: 90%