LED Flicker: A Drawback or an Opportunity?

Abstract

<p class="MsoNormal" style="text-align:justify;"> <span lang="EN-US">In this paper we examine the flicker of commercial LED lamps and with the help of volunteers we explore the parameter space (frequency and duty cycle) in order to find pulsing operating conditions under which the light fluctuations are not visually perceived. The results show that LEDs under mains voltage manifest the most extreme cases of flicker and we also confirm that under pulsing mode the overall impression is of higher brightness which is an opportunity for energy savings. The results also show that the background color and luminance contrast is of high importance. Finally we propose an easy method for consumers to detect flickering of light sources under mains voltage.</span> </p

Predicting the stroboscopic effects of measured and artificial flicker waveforms through simulation

“…Subsequently, luminance profile lines can be applied to generate parameters such as the stroboscopic index and stroboscopic percentage, which are similar to the flicker index and percent flicker for the purpose of quantifying the stroboscopic effect. Since the perception rate, acceptability, and visibility threshold have already been obtained in the literature, [11][12][13][14] the experimental conditions that produce acceptable and/or unacceptable stroboscopic effects can be defined. Such conditions can be employed for stroboscopic pattern simulations to calculate the acceptable stroboscopic index and stroboscopic percentage.…”

“…9,10 Flicker can, however, be perceived indirectly by the stroboscopic effect. Recent research [11][12][13][14] on flicker evaluation has therefore been mainly based on the perception rate and acceptability of stroboscopic effects. In previous experiments, observers sitting in a flickering-light environment were asked to rate the stroboscopic effects induced by different flicker waveforms.…”

Measurement Approach for Monitoring Time-Dependent Intensity Variations of Commercial Light Sources

“…The integrated light intensity of a light source over time is plotted in lumen over time. 2,12,27,28 For most applications, this kind of measurement is sufficient, but it does not yield any additional information concerning the shape of the emission spectrum and its possible impact on the perception of flicker. Since each color in the visible spectrum is perceived differently by the human eye, it can have different impacts on the perception of flicker.…”

“…26 However, depending on the driver, the whole LED may still suffer from a short off-time or a fluctuation in the intensity over time. 27 During an off-time of the LED chip or a phase with decreased current driving the LED chip, no or less photons are emitted since the applied LED phosphors have decay times much lower than 1 millisecond. Therefore, the photon flux decreases as soon as the LED chip intensity changes.…”

“…1 However, solid state light sources still have a drawback, namely the so-called intensity flicker. 2 According to the 9 th edition of the IESNA Lighting Handbook, flicker is defined as "the rapid variation in light source intensity". 3 The term flicker is used ambiguously within the scientific world.…”