LED FLICKER
Where does this come from?
People react to light – we’ve known that for a long time! The day-night rhythm, hormonal fluctuations and even psychological effects are well-known and proven. So if natural light has such a significant impact on us and our bodies, what happens with artificial light, especially with ‘poor’ artificial lighting?
Does this sound familiar? Headaches, mild nausea or dizziness? There are many reasons for this, one of which could be the wrong LED lighting! And not just on PC monitors, mobile phones or televisions, but also on cheap and poor-quality LED light sources. They flicker – and this LED flicker has long-term effects on us. This phenomenon can even go as far as the visible strobe effect we’re familiar with from discos. In most cases, however, we don’t even notice the flickering – and that’s the problem!
BUT WHERE DOES THE LED FLICKER COME FROM?
In principle, it’s quite simple to explain: the electricity from the mains is alternating current, which means that at very, very short intervals, the voltage changes polarity from POSITIVE to NEGATIVE and vice versa. To be precise, 50 times per second – that’s a frequency of 50 Hz. It is precisely this alternating voltage that the LED light sources visually reproduce. And it always does so at double the frequency, meaning the LED switches on and off 100 times per second. It switches on during the positive and negative half-cycles and off around the zero point. In fact, LED light sources would ideally require direct current to function perfectly and shine without flickering.
THE SOLUTION
A ballast circuit within the LED light source (hidden in the base) converts the alternating current from the mains supply into direct current, or modulates the frequency so that it is no longer perceptible.
A high-quality circuit can reduce the flicker of dimmable LED light sources to virtually zero. However, this involves significant material costs. We can therefore assume that most low-cost products contain no ballast electronics, or only insufficient ones.
Many NON-dimmable LED light sources do not suffer from the problem of flickering, as they are based on a different, simpler technology that generates a constant voltage. Nevertheless, there is also significant flickering in the non-dimmable sector, e.g. in many G9 and R7s in glass housings and in LED light sources using driverless AC-Direct technology.
HOW DO I FIND OUT IF MY LED LIGHT SOURCE FLICKERS?
There is a very simple test that anyone can carry out at home without much equipment: the so-called camera test. In our part of the world, with a mains frequency of 50Hz and a standard camera or mobile phone (24fps), you can use this method to detect the most common 100Hz flicker.
HERE’S HOW:
Switch on the LED light sources and the camera (launch the camera app on your mobile phone). Hold the camera or mobile phone very close to the LED light sources. DO NOT take a photo or video, just watch! If the light source flickers, dark bars will run across the screen. The darker these bars, the worse the flickering!
HOW TO DEAL WITH LED FLICKER
In recent years, the flicker problem has become more prevalent and has increasingly come to the attention of LED users due to the widespread switch to LED and the phasing out of old incandescent bulbs. This is because, in particular, the driverless AC-direct technology mentioned above, as well as G9 and R7s LEDs in glass housings, are very cheap to manufacture and are flooding the market. There are a number of, mostly relatively complex, measurement procedures and methods for measuring the ‘flicker level’ of LED light sources. None of them take all factors into account and none are 100% conclusive. And they are virtually impossible for the average consumer to understand!
The incandescent bulbs serve as a reference and starting point for retrofit LED light sources. Because, as hardly anyone knows, these too flicker, albeit to a very small extent. From experience and habit, we know that flickering in this range is imperceptible and, above all, harmless.
On the left is the measurement graph of an incandescent bulb – on the right are the clear fluctuations of a heavily flickering LED light source!
Image source: “Der Lichtpeter”
Anyone wishing to find out about the exact measurement methods, get an overview of measurement results and, above all, learn about a new and highly sophisticated approach can find detailed information here at “Der Lichtpeter”.
SOLUTIONS FOR LED FLICKER
Unfortunately, there is still no valid law requiring manufacturers or suppliers to specify the flicker level of their products. Only the manufacturer knows what components they use! As customers, we therefore find it very difficult to determine whether the LED light sources we buy fall within the tolerance range or not.
At the end of 2019, a new EU regulation, ‘EU2019/2020’, was published, which came into force in September 2021. This stipulates that the limit values for flicker, measured as PstLM ≤1.0, and the stroboscopic effect (100Hz flicker), measured as SVM ≤0.4, must be met.
SEGULA LED – WHAT WE DO
SEGULA’s promise to our customers: We use only the highest-quality and most advanced ballast electronics for our dimmable LED light sources. For our measurements, we use the values prescribed by the EU. Incidentally, since the publication of the directive, several other manufacturers have also been doing this. Upon request, we naturally have all the relevant values regarding flicker ready and available!
The measurement chart for an 8W SEGULA LED light source, showing outstanding results. Flicker is completely negligible.
Image source: “Der Lichtpeter”