100Hz flicker in lighting is a problem?

[ocset]

Hello,
Please can we   de-nonsense   the  “100Hz flicker problem” in lighting?

The web is full of conflicting stories  about  whether or not  100Hz flicker is  actually harmful to humans.

I believe that 100Hz flicker in lighting is no problem whatsoever…..i lived under the old magnetic ballast fluorescent lighting for decades…and had no problem with its 100Hz flicker. Also, driving down motorways with sodium vapour lamp streetlighting which flickers at 100Hz,  caused me no problem whatsoever…..and no problem to other drivers either.

Headaches  in today’s world are more likely to be caused by Hangovers, too much caffeine, too much sugar, too little exercise, too little sleep due to watching Netflix all night, etc etc…..

The 100Hz flicker problem in lighting is simply a nonsense story pervaded by large  electronics corporations so that they can sell their integrated circuits and lamps  which get rid of this 100Hz flicker.
Also, most of the large electronics corporations have decided to volume manufacture LED power supplies with large-ish  electrolytic capacitor banks, (eg after the PFC stage) which makes them cheaper and easier to design……..and means the 100Hz flicker is easily avoided…….having committed their resources to this in vast quantity, they then are looking to create nonsense stories about smaller manufacturers who make lamps which do flicker at 100Hz….in  other words, yet again, all we are  seeing, is the large globalist corporations lobbying Governments so as to increase their profits and destroy their smaller rivals.

Surely you agree?

I mean, they are looking to make greedy mega bucks by replacing all  the old 100Hz flickering sodium streetlamps with their flicker free  LED offerings....but first, they have to pervade their nonsense  health hazard stories about 100Hz flicker.

There is not one single piece of conclusive evidence to state that 100Hz lighting flicker is actually a problem……..nonsense?

http://luxreview.com/article/2018/04/street-light-flicker-is-new-hazard-says-watchdog

3:43 to 4:43 of this video shows how the global corporastions lobby governments to favour their own profit making rackets, eg in the case of 100Hz flicker stories....

[Siwastaja]

Depends on the amplitude and shape (duty cycle) of the 100Hz! That's one of the reasons for so many conflicting views - there are so many levels of "flicker".

Also, people are really different. We do have physiological differences. Sensitivity to flicker is a classic discussion. Similarly, motion picture film projectors existed in two varieties, 48Hz and 72Hz flicker, and people had strong opinions on them.

For example, the traditional incandescent lamp flickers at 100Hz but the amplitude is only about 10-30% peak-to-peak of the full power. Fluorescent is more flickery, but the fluorescent material they use still has some "delay" in it. The amplitude of the flicker is not even near to 100%. Fluorescent lamps tend to also flicker in different colors; the spectrum varies as a function of time.

With LEDs, it depends a lot of the driver. For example, if you drive "raw" from full bridge rectified mains, with capacitive or resistive dropper, so that the Vf of the LEDs is fairly high, it means they conduct only a small portion of the cycle, giving a very strong flicker - amplitude is 100% and duty cycle may be as low as 30%. These kind of bulbs do exist and some people are fine with them, but some are not. Personally, I don't like them at all, I'd call them disastrous. When you move your hands quickly, you get the strobe effect.

People actually getting migraines or epilepsy is AFAIK not very common, but still a valid concern.

If at all possible, please design your LEDs to be fairly flicker-free. No need for perfectionism here, but I think solutions which only use a small portion of mains cycle without storing any energy are out of question.

I don't think there's a conspiracy out there. I have seen so many shitty, flickery lamps existing!

It's well possible that marketing exaggerates the flicker problem to sell products and lobby. That's how marketing works. But even if the problems of flicker were exaggerated by some, it's still a very good idea to limit it to sane levels.

[Twoflower]

One I was in a Hotel that had all lights converted to (cheap) LEDs. All light in the room flickered synchronous to each other and it was not very bright light. The result was moving in the room made feel me dizzy. While stay still was no problem. Except in the peripheral view. It took a few hours to get used to that. Nothing I would recommend to live in. I never experienced this with fluorescent light. Not even close to that, except with fast running stroboscope lights. In fact my desk lamp is still using a fluorescent tube with a old balun and I never had an issue with that having this as only light in my room (similar brightness like the said hotel room). Obviously LEDs can be driven in modes that this stroboscopic effect is very intense.

Please note that I seem to recognize reasonable high flicker frequencies but has no direct issues with such conditions.

Also working with machines can be dangerous under such conditions. As the stroboscopic effect might trick your assumption of the rotation speed. That's the reasons that in some countries are rules for fluorescent lights in machine halls need to be supplied from different phases or other measures to prevent the stroboscopic effect (e.g. Duoschaltung; sorry no english entry).

Edit: Added link to Duoschaltung

[mikerj]

Hello,
Please can we   de-nonsense   the  “100Hz flicker problem” in lighting?

The web is full of conflicting stories  about  whether or not  100Hz flicker is  actually harmful to humans.

I believe that 100Hz flicker in lighting is no problem whatsoever…..i lived under the old magnetic ballast fluorescent lighting for decades…and had no problem with its 100Hz flicker. Also, driving down motorways with sodium vapour lamp streetlighting which flickers at 100Hz,  caused me no problem whatsoever…..and no problem to other drivers either.

How do you know that no other drivers were affected by flicker?  Has every single driver been questioned?  Do you believe every single person has the same sensitivity to flicker?

[ocset]

Ive never met  anyone who was sensitive to flicker...i have never seen any of the effects of flicker that are described here...i am in my 40's.
How do you know that the "flickering" led lights were not suffering some feedback stability loop thing?

I can honestly say that lighting in a room, dim or not, has never ever made me dizzy...and i never met anyone who said this.

Ive been to loads of nightclubs where the lighting was deliberately flickering very fast ( i used to work in one like this)...and if you moved your hand across your face, it was kind of weird seeing it jagger across....but i did not mind at all...and none of the other 1000's in the packed nightclub left the club because of it.....you did not get lots of people leaving saying...wow...i just couldnt handle those flickering lights...had to go home early.

Also working with machines can be dangerous under such conditions. As the stroboscopic effect might trick your assumption of the rotation speed

Now this anyone would say is a good point...so for those particular places, yes....even then, people shouldnt be going anywhere near ungaurded electical machines that are rotating whatever the lighting

[Siwastaja]

Ive never met  anyone who was sensitive to flicker...

I knew one guy who was somewhat sensitive to mains frequency fluorescents (@ 100Hz)! And he was serious about it.

Now, the important takeaway is that a "flickerily" designed LED source can be an order of magnitude worse than a fluorescent. Haven't talked to him since LED lamps got more widespread, however...

i have never seen any of the effects of flicker that are described here...i am in my 40's.

The reason might be that you simply haven't seen the "worst offenders", or you just don't know anyone who's suffered from them.

The fact this doesn't seem to be a problem might be just because the designers know flicker is a problem and hence, design the products to be non-flickery!

How do you know that the "flickering" led lights were not suffering some feedback stability loop thing?

Well, that's a possibility, too. The reason of the flicker is irrelevant, but you need to limit the amount of flickering to manageable levels.

I can honestly say that lighting in a room, dim or not, has never ever made me dizzy...and i never met anyone who said this.

I agree it isn't common enough. Although, I have never known or heard of anyone being allergic to nuts directly... Yet it's a true fact that some people are deadly allergic to nuts - and it even isn't very uncommon!

It's just that your personal ring of people you discuss lighting details with is most likely very small.

Also, most people who get a headache from poor lighting would just leave the place and be done with it, and forget the incidence. It's an unfair expectation that they would know you are interested about this and come to you with this information!

Ive been to loads of nightclubs where the lighting was deliberately flickering very fast ( i used to work in one like this)...and if you moved your hand across your face, it was kind of weird seeing it jagger across....but i did not mind at all...and none of the other 1000's in the packed nightclub left the club because of it.....you did not get lots of people leaving saying...wow...i just couldnt handle those flickering lights...had to go home early.

Well, I think people do get a headache at nightclubs, and I think people do need to leave these places. I guess these places even employ staff to look at people not feeling well. They even tend to implement "closing hours" to limit the exposure times.

I guess countless people actually die due to visiting these places. People go there to deliberately poison themselves, anyway, and purposefully cause physical damage to themselves.

The flickering lights are supposed to make you feel dizzy, just like the alcohol they serve!

That's the whole idea.

Now, I'm very sure there are a lot of folks who don't go to nightclubs - for example, me. I would get a headache quite soon, probably as a combination of loud noises, and possibly flickering lights - even without any alcohol.

Note that the number of people who enjoy nightclubs and visit them without getting a headache is a very small minority. Most of the people just don't visit nightclubs too many times during their life, and most of those who do visit them are having a serious headache the next day. And I guess many don't want to try to classify the exact reasons for the headache. We all know what the number 1 is, but how about all the other contributing factors?

But I guess most people wouldn't like to have a nightclub at their home, 24/7. That could cause some serious headache.

[maukka]

Slow LED flicker is the worst. I don't get any symptoms like headache from it but in some situations it is very visible and annoying. Most people don't see or care about the usual 100/120Hz flicker, but playing with frequency, duty cycle and modulation depth everyone will see it with suitable parameters. With low duty cycle and true on/off PWM it can be seen up to several kHz if you know how to look for it with rapid eye movements.

Here's a good introduction and a single unit to evaluate flicker visibility: https://www.derlichtpeter.de/en/light-flicker/cfd/

Also in the flashlight world there's a huge variety of drivers for LEDs and some work has been done to estimate the visibility of flicker: http://budgetlightforum.com/node/57087

Just like with everything, YMMV. But just because it doesn't bother you, doesn't mean that others can't see it. Although I don't claim it has any effects on general health.

[ocset]

But just because it doesn't bother you, doesn't mean that others can't see it.

Thanks, there's never been a significant study done with unbiased groups of people being placed into rooms with/without flicker, and then seeing if they get headaches with /without the flicker being there.
This says it all........this is nonsense pervaded for reasons of financial gain, as described in the top post.

[Twoflower]

I think the LEDs actually had no driver real that could run havoc. One part of the lighting was a chandelier with several cheap filament replacements. They flicker synchronous to each other and with some single LEDs mounted in a wall. As all light sources are independent from each other I'm sure they're running synchronous at 100Hz. The interesting part is that I had the feeling that the 'see the world around me' wasn't the problem. The problem was the sense moving around didn't match to the visual.

Just one thing that just came back to my mind. Few moths ago I came to a customer office. And they replaced the T8 tubes in the ceiling with LED replacements. I noticed that flicker too, even with some additional daylight from windows. If I would work there I would actually do something to change that (e.g. LED with decent driver) as sitting under that light 8h+ a day would have an impact to my concentration. I have no problems working under fluorescent light and never noticed such things there. And fortunately so far for me that's only an annoyance.

One study for example (I just read the abstract) also note the list of references at the end. there are many studies listed with this specific topic:
https://www.ece.neu.edu/groups/power/lehman/Publications/Pub2010/2010_9_Wilkins.pdf
And you can find some more using your preferred search engine.

Note that I'm also 40+. This is a completely new effect to me to see this in lamps. I've noticed that in old computer screens 20something years back and I'm happy that this problem is gone with LCDs. Still under certain conditions I can see the OLED screen of my Samsung flicker too. But it seems that this now come back with cheap LED lamps. And potentially the microLED screens in future...

[maukka]

Some LCD monitors and especially televisions are notorious for having a PWM driven backlight, which flickers very clearly. At least TFT Central tests for this

[Siwastaja]

But just because it doesn't bother you, doesn't mean that others can't see it.

Thanks, there's never been a significant study done with unbiased groups of people being placed into rooms with/without flicker, and then seeing if they get headaches with /without the flicker being there.
This says it all........this is nonsense pervaded for reasons of financial gain, as described in the top post.

It seems you have already made your mind of rationalizing your shitty design - simply for your company's financial gains to save cost!

So why are you asking here when you already have your own "truth"?

Or were you just expecting confirmation to your rationalization, and now it backfired when people start telling their personal experience?

BTW, if you google for "lighting flicker study", you'll find a lot of scientific research about the matter. But it takes quite some time to go through enough material. Clearly, the flicker has been officially considered a health risk, hence standards exists. But you can, of course, decide that it's a further proof of a conspiracy, and a further confirmation for your rationalization - to allow you save money further in your shitty design and still feel good.

[bd139]

Treez: that youtube video is basically a load of bollocks run by a bunch of crackpot fucknuggets who's entire empire is run from being contrarian to rationality. Please stop watching stuff like this and getting angry. Develop some critical thinking skills.

This isn't about 100Hz flicker as such. It's about visual noise. If you have a 100Hz flickering LED light and 101Hz flickering TFT backlight for example then you get the thing beating at 1Hz resulting in some wierd visual artifacts. These are terribly difficult for the brain to process as it reacts quicker to contrast, which results in fatigue and at higher frequencies, actual fits. I know this having spent a good few years on anticonvulsants.

[rstofer]

In the early days of fluorescent lighting, the stroboscopic effect of flicker could make rotating saw blades appear to be switched off.  The ballast designers went to some effort to put a phase shift between the lamps to prevent this effect.

Ignoring all other physical issues, in terms of lighting only, I would be concerned that flicker might cause that stroboscopic effect to return.

https://www.electrotechnik.net/2015/11/stroboscopic-effect-in-fluorescent-lamps.html

[edavid]

If you have a 100Hz flickering LED light and 101Hz flickering TFT backlight for example then you get the thing beating at 1Hz resulting in some wierd visual artifacts.

No you don't, because there's no nonlinear element (mixer).  Two frequencies adding together in a linear element don't make a beat frequency.

[NiHaoMike]

Some LCD monitors and especially televisions are notorious for having a PWM driven backlight, which flickers very clearly.

That's often done intentionally to reduce motion blur, by transitioning the pixels while the backlight is off. LightBoost is one of the marketing names used.
https://www.blurbusters.com/zero-motion-blur/lightboost/
At 120Hz, the flicker is not noticeable.

[maukka]

Even though PWM is used in blur reduction technologies such as Lightboost or black frame insertion many normal non-gaming monitors suffer from it as well. And 120Hz PWM is very visible to some people even if it doesn't bother you.

[NiHaoMike]

Those who are bothered by 120Hz flicker must have had a really bad time back in the days of 60Hz TVs. There are also 240Hz monitors and TVs out there, but they're mostly for 3D glasses so that the effective framerate would be 120Hz after the glasses demultiplex it.

[maukka]

60Hz television would have been a luxury in a country with the 50Hz PAL system. But with practically no persistence, LEDs are much worse than a CRT screen at similar frequencies. 100Hz televisions/monitors seemed perfectly stable to me back then, but I haven't checked one out for quite a some time.

[ocset]

Also, all British motorways were, and often still are , lit with 10's of thousands of orange sodium lamp streetlights, which flicker at 100hz...and they go to zero current (zero light) every 10ms.........there has never been one single complaint from a driver about these streetlights....i think this says it all.

[bd139]

If you have a 100Hz flickering LED light and 101Hz flickering TFT backlight for example then you get the thing beating at 1Hz resulting in some wierd visual artifacts.

No you don't, because there's no nonlinear element (mixer).  Two frequencies adding together in a linear element don't make a beat frequency.

There are three very non linear elements in your head.

Watch this. I connected two cheap red LEDs to my FG and set them at 6Hz and 5Hz respectively 50% duty cycle. Note at approx 1Hz there is an intensity gradient.

I had to slow this down to 5/6Hz to maintain video quality as the camera is good for about 30fps only unlike the brain.  Average eyes and  brain and eyes can see this up to about 60Hz. 60-120Hz depends on the person.

https://youtu.be/TM6Y0cYLVU0

Edit: updated number of non linear elements to three because the brain has its own abstraction over what is going on.

[floobydust]

You have to consider the physiology of vision, the biomechanics.
It's very difficult to put in electrodes (in animals) to get the time constants out of a region of the brain that does the auto-focus and positioning for us.

As you read this, your eye is micro-focusing and moving from letter to letter.
An entire servo system, that does not like flicker lest it cause eye-fatigue from its muscles going back and forth. Or it simply fails to focus/position in time to avoid an accident due to a strobing streetlight.

Or perhaps there is a heterodyning issue, between two independent light sources.

[Marco]

Those who are bothered by 120Hz flicker must have had a really bad time back in the days of 60Hz TVs.

You don't have parallax planes moving independently while being lit by a stroboscopic light on a TV. Nor does the TV have a mix of continuous and stroboscopic lit movement from background light combining with the stroboscopic light.

60Hz television would have been a luxury in a country with the 50Hz PAL system. But with practically no persistence, LEDs are much worse than a CRT screen at similar frequencies.

Once you're above the flicker limit for displays, low persistence is far better for motion until you hit very high framerates (actual fully rendered framerates, not just screen updates). So if you can only generate say 100 fps, you want a low persistence display.

LED lit and OLED displays are almost always capture and hold, high persistence. Nice to display a photograph, not so much for moving images.

[james_s]

Harmful? Probably not directly, but it certainly is annoying.

Here HID, magnetic ballasted fluorescent and some LED lights flicker at 120Hz and that's bothersome to me, 100Hz is significantly worse. I suppose you get used to it but when I visited the UK the flicker was quite pronounced. I also noticed that motors and transformers sounded strange to me. You get used to a certain frequency of "electrical hum" and when it's suddenly different it really becomes noticeable. A friend of mine who lives over there has said the same thing when he's visiting the US, the refrigerators and air conditioners and such all sound weird to him.

[tooki]

Hello,
Please can we   de-nonsense   the  “100Hz flicker problem” in lighting?

The web is full of conflicting stories  about  whether or not  100Hz flicker is  actually harmful to humans.

I believe that 100Hz flicker in lighting is no problem whatsoever…..i lived under the old magnetic ballast fluorescent lighting for decades…and had no problem with its 100Hz flicker. Also, driving down motorways with sodium vapour lamp streetlighting which flickers at 100Hz,  caused me no problem whatsoever…..and no problem to other drivers either.

Headaches  in today’s world are more likely to be caused by Hangovers, too much caffeine, too much sugar, too little exercise, too little sleep due to watching Netflix all night, etc etc…..

The 100Hz flicker problem in lighting is simply a nonsense story pervaded by large  electronics corporations so that they can sell their integrated circuits and lamps  which get rid of this 100Hz flicker.
Also, most of the large electronics corporations have decided to volume manufacture LED power supplies with large-ish  electrolytic capacitor banks, (eg after the PFC stage) which makes them cheaper and easier to design……..and means the 100Hz flicker is easily avoided…….having committed their resources to this in vast quantity, they then are looking to create nonsense stories about smaller manufacturers who make lamps which do flicker at 100Hz….in  other words, yet again, all we are  seeing, is the large globalist corporations lobbying Governments so as to increase their profits and destroy their smaller rivals.

Surely you agree?

I mean, they are looking to make greedy mega bucks by replacing all  the old 100Hz flickering sodium streetlamps with their flicker free  LED offerings....but first, they have to pervade their nonsense  health hazard stories about 100Hz flicker.

There is not one single piece of conclusive evidence to state that 100Hz lighting flicker is actually a problem……..nonsense?

Wooooow… duuude. This is taking your ignorance to a whole 'nother level. How the f**k are you working as an engineer at a lighting manufacturer when you demonstrably know nothing about electronics or lighting?!? And even worse, seem hell-bent on not learning. You come here and basically ask for people to confirm your latest crackpot theory or design…

Is flicker harmful as in causing illness or injury? Not directly. But it does cause headaches in some people, and it is annoying to many more, and the strain of trying to ignore the flicker can be exhausting. And finally, flicker can be distracting (especially in peripheral vision), which can be dangerous.

Learn about the "flicker fusion threshold". Please. (Executive summary: to eliminate the chance of flicker in ALL situations, you need a PWM frequency of up to 30KHz.)


As for the conspiracy theory about manufacturers inventing a problem: oy gevalt… No. They don't need to invent reasons to avoid flicker, because enough people perceive flicker as annoying and distracting to complain about it.

[tooki]

Those who are bothered by 120Hz flicker must have had a really bad time back in the days of 60Hz TVs. There are also 240Hz monitors and TVs out there, but they're mostly for 3D glasses so that the effective framerate would be 120Hz after the glasses demultiplex it.

60Hz CRT TVs were OK for two reasons: phosphor persistence, and the fact that you look at a CRT straight-on. In peripheral vision, you might catch slight flicker.

120Hz LED is a totally different beast. It has zero persistence, so especially in peripheral vision, it's easily noticed, especially when your eyes, head, or the light source are in motion. You also should google the "flicker fusion threshold".