ASSIST Publishes Recommendations for Detectability of Flicker in LED Sources

The Alliance for Solid-State Illumination Systems and Technologies (ASSIST) recently released a new publication that addresses the issue of LED light source flicker. The methods offered in the publication can be used by LED lighting manufacturers to develop systems that minimize the effects of flicker.

The publication, ASSIST recommends: Flicker parameters for reducing stroboscopic effects from solid-state lighting systems, provides calculation methods for estimating the detectability and acceptability of stroboscopic effects from flicker using the parameters of frequency and percent flicker. The calculation methods are based on Lighting Research Center (LRC) work published last year in Lighting Research & Technology journal.

Flicker and stroboscopic effects have been a concern with SSL sources, and industry and the ENERGY STAR program have debated the effects of frequency and other driving modes on the perception and acceptability of flicker. To provide further data and guidance in this area, ASSIST funded human factors studies of indirect flicker perception. The studies, led by LRC senior research scientist John Bullough, were designed to determine what light source parameters affect the detection of flicker and stroboscopic effects, and to assess subjective responses to flicker in terms of acceptance and comfort. Previous research had shown at what frequencies direct flicker is perceptible but did not identify thresholds and acceptance levels for indirect perception, nor a means of predicting these levels for SSL.

The results from these studies suggest that there is a tradeoff between the frequency and the modulation depth in the detection and acceptability of indirect flicker. Follow-up studies systematically evaluated this tradeoff and looked more closely at the relationship between frequency and percent flicker. The conclusions drawn from these studies led to the development of the calculation methods detailed in the ASSIST recommends publication, which provides estimations of the detection and acceptability of light source flicker for a given frequency and percent flicker.

Click here to download these recommendations.

Craig DiLouie

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