Flicker Explained : guide to IEC for the lighting industry

Flicker, or more precisely temporal light modulation (TLM), has re-emerged as a problem with the introduction of LED-based lighting technology. TLM, meaning variations in light intensity over time, may have negative effects on human health, causing annoyance, headaches, eyestrain and migraine. In addition to the unnecessary suffering TLM causes in individuals, the negative consequences of TLM create an obstacle to broad and rapid adaptation of the new LED-technology and consequently also an obstacle to potential energy savings.This guide gives an introduction to TLM, what it is and how it is measured. The effect of TLM on health is concluded, and also the state of knowledge in its research area. An extended part of this guide discusses the flicker measure short-term flicker indicator, Pst, and the technical report describing it, TR IEC 61547-1:2020 (henceforth referred to as IEC 61547, unless otherwise stated). This report describes the equipment, method and measures required to assess flicker. It is, however, technically complicated and could be very hard to interpret by non-technical readers. For a more detailed investigation and recommended amendments of the IEC 61547, see “Flicker explained – Interpretation of the Technical Report IEC 61547“ which is another product of the project Flicker Explained. For a general guide on TLM measurements, please consult the technical note published by International Commission on Illumination, CIE TN 012:2012

Flicker – a technological overview

Flicker can be annoying, but above all it can have a negative effect on human health; causing irritation, headaches, eye strain and migraines. With the introduction of LED lamps, flicker has once again become a problem. In addition to the unnecessary suffering caused to individuals, the negative consequences create an obstacle to the wide and rapid adoption of new LED technology and thus also an obstacle to potential energy savings.The EU’s new eco-design regulations entered into force in September 2021. These include, for the first time (in Europe) regulatory limits for flicker, creating an urgent need to disseminate knowledge about flicker and how to measure it