Latest EU Policy: Flicker-free Lighting is the Norm

July 14, 2022

LED lights are increasingly used in daily life, home, office, indoor and outdoor. As we transition over into an LED accustomed society, there is an issue that presents itself that not only has a negative effect on your health but as well your electronics. What exactly is flicker in LED lights and why are my LED lights flickering?

What is a flicker and what causes it?

There are occasions in life that strange phenomena are observed: when rapidly waving a pencil under a lamp, it is a series of static and individual images are created which is known as Stroboscopic effect. This effect captures the impression of rapid light flux fluctuations, which our vision perceives as flickering. 

This phenomenon, whether noticed or not, occurs due to the change of visible light intensity over time; a light flicker. LED lights exhibit rapid repetitive changes in brightness over time which can cause visual, physiological, and neurological effects on our bodies; eye strain, fatigue, headaches, and difficulty in concentration. Light flickering occurs all the time, even when we don’t notice it.

Visible flickers-Wave a Pencil

Visible VS. Invisible Flickers

Visible flickering is picked up by our eyes, and then registered in our brains. Invisible flickering, however, cannot be directly noticed but our optic system may still sense it. Although invisible to the naked eye, invisible flickering can have long-term harmful effects on humans.

Why does LED light flicker?

An LED light source consists of two parts, one is the LED emitter that emits the light by DC Current. The more powerful the DC current is, the brighter an LED illuminates. The other part is that the LED driver which converts the 120V/230V AC or other voltages into the DC voltage and current that conforms to the rated driving condition of the LED emitters in the lamp. An LED driver works in two steps: rectify and filter. An LED driver first rectifies 50Hz/60Hz  AC current into 100Hz/120Hz current which is closer to a DC (actually fluctuates in double time). Then, filtering the current as smooth as possible to be closer to a DC. So why is your light fixture flickering? Flicker occurs when bad filters happen with certain fluctuations in current.

Dangers of Flickering

Standard lighting and task lighting with minimal flicker should always be preferred. As described in The Institute of Electrical and Electronics Engineers (IEEE) Standards 1789-2015, flickers increase the risks of problems such as eye strain, headaches, and even seizures (photosensitive epilepsy), after prolonged exposure. Because of the harm that flickering lights have on human health and the safety risk it poses on industries where lighting is a necessary function, there is an increasing number of industrial organizations and legislators who agree that it should be mandatory to manufacture and use flicker-free lighting products.

Physical & Mental Health: Unlike natural sunlight and moonlight that doesn’t flicker, artificial flickering lights pose a threat for the well-being of an individual. We don’t see it, but our nerves and organs can sense it and may have a hard time identifying and adapting.

Photography & Videography: The shutter speed of a camera can be set very high, which can cause brightness defects on the images captured under a flickering light. Not having the proper flicker-free lighting can ruin your light quality in images, or you may notice fluctuations in lighting of different frames in video.

Industrial Lighting: Certain industries utilize equipment that are rapidly rotating or has moving parts. Not having exceptional flicker-free lighting can create a safety hazard for you or your business. 

The EU Mandates Flicker Free Lighting As The Norm

Because of the enormous harm that flickers in lighting have on human health and the safety risk to daily life and industrial safety, there is an increasing number of industrial organizations and legislators who agree that it should be mandatory to manufacture and use flicker-free lighting products.

The European Union’s release of their Commission Regulation (EU) 2019/2020 on eco-design products and lighting controllers, which it clearly defines flicker and stroboscopic effect, and the strict numerical requirements: Pst LM ≤ 1.0, SVM ≤ 0.4. Beginning on September 1st, 2021, all lighting products entering and manufactured in the European Union, should be regulated in terms of flicker. These restrictions on flicker come about amidst growing concerns over the harmful effects they leave on the body, which means that now more than ever flicker-free lighting is becoming an industry standard.

The USA’s Stance on Flicker Free Lighting?

At present, in many countries including the USA, flicker-free LED light bulbs, lamps, and tubes are increasingly selected by consumers. Products featuring words such as flicker-free, vision protection, high-quality lighting, and human-centric lighting are becoming more and more well-known and accepted. It is believed that in the coming years, the USA will also pay more and more attention to the harmful effects of flickering in lighting.

Is labeling flicker-free truly no flicker?

As LED lamps become popular and dominant in the lighting market, more consumers get to know the advantages of flicker-free lighting and boost the market as well. Meanwhile, more and more lighting brands show up by labeling flicker-free LED lamps to consumers. Do these flicker-free labeled lamps truly have no flicker? Maybe not all, some are no observable effect level (NOEL) flicker-free.

Unfortunately, some brands have misled the concept of flicker-free by claiming it is no observable effect level flicker-free. Because the max number of still images that the human eye can distinguish is 24 frames per second (fps) which is the least video frame rate of animations. This is the same case in lighting. When the light flickers regularly, and the flicker frequency exceeds 24 times/second, which is 24Hz, it is not easy for the human eye to distinguish that the light is flickering. When the flicker frequency exceeds 100Hz, most people can no longer distinguish the flicker in lighting. Therefore, the concept of “no observable effect level flicker-free” cannot mean that LED lights have no flicker fundamentally.

For those conventional LED lights without flicker control, their flicker frequency is normally 100Hz~120Hz (double times the alternative current). The flicker at this frequency is not observable by human eyes.

For those LED lights that have a flicker control unit, its stroboscopic effect is not so obvious, it is the kind of flicker that cannot be easily identified.

It is irresponsible to consumers when these two kinds of LED lights enter the market labeling “no observable effect level flicker-free”.

The real flicker-free LEDs by Yuji Lighting

Step 1: Identify the flicker metrics in LED lighting

There are three major flicker metrics regarding the severity of flickering in lighting:

Flicker frequency (Modulation frequency): The number of repetitive changes in brightness magnitude, or modulation, of the luminous flux of a light source per second, the unit is Hz. According to the assessment in IEEE Std 1789-2015, when the flicker frequency is greater than 1250Hz, flickering in lighting will have a little negative impact on human life and work, and can be classified as the low-risk exemption level. When the flicker frequency is greater than 3125 Hz, this high-frequency flickering light is classified as a high-frequency exemption level.

Low-Risk Level and no observable effect level

Flicker index: Flicker index is defined as a measure of the cyclic variation taking into account the shape of the waveform. It covers 0.0~1.0. The greater the flicker index, the more substantial the flicker and the less stable of light output.

Percent flicker: Percent flicker, also known as modulation depth, is a relative measure of the cyclic variation in the peak-to-peak amplitude of light. It covers 0%~100%. The greater the percent flicker, the more substantial the flicker.

Diagram for definition of flicker index and percent flicker

Step 2: Mitigate flicker risk by optimizing the design of LED drivers

  1. Use a more effective noise filter unit at the output end to stabilize the output current at a fixed value.
  2. Use a more reasonable driving topology of a two-stage (AC to DC + DC to DC) LED driving scheme to turn the unstable input current into a stable value.

By adoption of one or both methods mentioned above, the flicker index of an LED lamp will fall between 0.001 and 0.01, and the percent flicker down to 0%-5%. While the flicker index and percent flicker stay at low values, the flicker frequency will normally be read as 0.0Hz by a professional flicker meter. For those lights that require the flicker index and percent flicker above 0, designing a modulation frequency greater than 3125Hz will turn it into a high-frequency exemption level.

Step 3: How to verify the flicker-free LED

Without complicated and expensive measurement devices, your smartphone can be used to verify the flicker of an LED lamp. Unless needed, use a professional flicker meter. Turn your smartphone camera into slow motion mode, set both resolution and video frame rate at the maximum (like 4K at 240fps), and leave the camera as close to the LED lamp as possible. At this time, if the images on your smartphone remain stable in brightness without dark stripes scrolling, congratulations, your LED may be the real flicker-free.

If unfortunately, you have observed flickers in your LED lamps, then please email us or call us to name your preferred bulb type, or choose from our catalog by yourself, because they are truly flicker-free.

Contact us for more information. Contact us