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Siliconguy

macrumors 6502
Jan 1, 2022
424
619
First link in the Google search;

"In short, to use PWM dimming and avoid its drawbacks, you should set the PWM dimming frequency higher than 2kHz. To achieve high-frequency dimming, most LED drivers have a PWM dimming input. "


You can't see a 2 KHz flicker. What you might be able to see is a heterodyne between the LED on the screen and the frequency in the lights in the room. If they are almost but not quite the same frequency you might see the difference as a flicker as they move in and out of phase with each other.
 

rui no onna

Contributor
Oct 25, 2013
14,915
13,259
PWM sensitive people, however, also seem to have no interest in getting into the nitty gritty of specifics and assume all PWM is the same. To take its existence on a product as confirmation that they’ll be sensitive to it is just nonsense. There’s a huge range of frequencies that it can operate at and that seems to have an impact on whether it actually hurts their eyes. The higher ranges seem to alleviate the effect that *some* people have.

I can read for a long period on the Mini-LED iPad Pro 12.9 which I believe also has PWM but at higher frequencies.

Alas, no go on iPhone 12 mini nor the iPhone 15 Pro. A quick search on Yelp or checking iMessage/Messenger/WhatsApp/Viber is OK but not longer use.
 

TracerAnalog

macrumors 6502a
Nov 7, 2012
796
1,462
I feel sorry for OP, but the vast majority of people is very happy with OLED in their TV’s, phones and tablets. Apple cannot possibly manufacture bespoke electronics for every subset of people… 🤷🏻‍♂️
 

Analog Kid

macrumors G3
Mar 4, 2003
9,360
12,603
It’s semantics but since the PWM signal never switches polarity in my experience it’s still referred to as DC, albeit a noisy DC.

There can be some ambiguity between "DC" and "rectified AC", but it gets confusing to call a blinking light "DC". The concept of "high frequency DC" doesn't really compute. It's clearer to understand that rectified AC is really a superposition of DC and AC. In cases like this a "DC dimmer" is one that achieves its function by adjusting the magnitude of the 0Hz component at the input to the diode, and minimizes non-zero frequency, AC, components that the diode sees.

A PWM is typically that superposition of a zero mean square wave and a DC signal at a fraction of the peak magnitude. You can see that in the spectrum, there is a DC component at 0Hz and a sequence of AC components at various frequencies. If you were to view this on a scope and enable AC coupling, you aren’t converting it to AC, you are isolating the AC for viewing. Peak-to-peak will remain the same, but average will fall to zero.

All of which to say, a PWM has significant AC components, a DC dimmer would not. However you want to define the terms, this is what's meant in the discussion.

A similar smoothing effect should be achievable by adding a capacitor or inductor to the pulsed circuit. That’s effectively how switched mode regulators work after all. I would imagine that’s already the case though.

Yes, it could.

Also, since the phosphor is responsible for the color, not the LED itself, color shifts in the underlying LED are probably less of an issue so they may not hit it with such a harsh PWM waveform.
Series inductor comes to mind.

(It's the inductor that strives to keep current constant.)
 
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ThailandToo

macrumors 6502a
Apr 18, 2022
692
1,357
This is a small subset of people self-diagnosing themselves. The last thread here on the topic was pages and pages of people asking for studies that demonstrate that PWM is the culprit, and there were none forthcoming. I'm not saying the sufferers are making it up, but I am far from convinced that they know what's actually happening.
This is probably the smartest thing anyone has ever written in these forums.
 

AlixSPQR

macrumors 65816
Nov 16, 2020
1,077
5,466
Sweden
I can read for a long period on the Mini-LED iPad Pro 12.9 which I believe also has PWM but at higher frequencies.

Alas, no go on iPhone 12 mini nor the iPhone 15 Pro. A quick search on Yelp or checking iMessage/Messenger/WhatsApp/Viber is OK but not longer use.
Which is virtually no one.
So, rui no onna, above, and others like him/her/they*, are no one? Just to understand you correctly.

*Edit: Including jimmy_uk below.
 
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jimmy_uk

macrumors 68020
Oct 19, 2015
2,478
3,305
UK
This is a small subset of people self-diagnosing themselves. The last thread here on the topic was pages and pages of people asking for studies that demonstrate that PWM is the culprit, and there were none forthcoming. I'm not saying the sufferers are making it up, but I am far from convinced that they know what's actually happening.
And this might be the truth because there isn't enough data or studies to know what is the real cause, but you cannot ignore that the common thread is that sensitive folk will describe eye strain/headaches/fatigue when using and viewing: mobile phones, laptops, computer monitors, TVs, lighting (street, building, vehicles), etc = anything human-made that is emitting artificial light that is flashing/moving/dithering rapidly.

This isn't a cult or a group of people who simply want something to complain about. I've always had a strong interest in new technology, having grown up surrounded by it and using it daily for work. However, my ability to fully enjoy it or even use it at all is hindered by the fact that it can trigger negative physical reactions in me, and I have no idea why this happens. Sadly, as a day one iPhone user, this started for me with the first OLED iPhone and has remained the same with every OLED phone after it. I would love to have the 13" iPP but already know there would be no point in even trialing it. 😵‍💫
 
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spamabyss

macrumors member
Dec 4, 2021
53
149
I have a friend who states to get intense headaches from looking at any of the oled iphones. I'm luckily fine with iphone and macbook screens but find the LG C2 OLED at my moms place surprisingly rather uncomfortable to look at, regardless of the settings. Alas. Always something.
 

NT1440

macrumors Pentium
May 18, 2008
15,092
22,158
And this might be the truth because there isn't enough data or studies to know what is the real cause, but you cannot ignore that the common thread is that sensitive folk will describe eye strain/headaches/fatigue when using and viewing: mobile phones, laptops, computer monitors, TVs, lighting (street, building, vehicles), etc = anything human-made that is emitting artificial light that is flashing/moving/dithering rapidly.

This isn't a cult or a group of people who simply want something to complain about. I've always had a strong interest in new technology, having grown up surrounded by it and using it daily for work. However, my ability to fully enjoy it or even use it at all is hindered by the fact that it can trigger negative physical reactions in me, and I have no idea why this happens. Sadly, as a day one iPhone user, this started for me with the first OLED iPhone and has remained the same with every OLED phone after it. I would love to have the 13" iPP but already know there would be no point in even trialing it. 😵‍💫
Have you managed to determine what PWM frequencies affect you? It can’t be all of them.
 
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Timpetus

macrumors 6502
Jun 13, 2014
400
923
Orange County, CA
Besides the issues with proving the exact cause of this phenomenon, what would you have Apple do about this? Going back to LCD would be the biggest PR (and subsequently, sales) disaster in the history of Apple. Producing a second line of iPad Pro (minus?) with LCD would be very expensive and would set a different kind of sales record. Change the frequency? To what? Everyone seems to be sensitive to a different frequency range, so there's no single frequency that'll be perfect for everyone. I don't see any option for Apple besides what they're already doing: not worrying about it and continuing to adopt the newest tech whenever they consider it "ready."
 

Maven1975

macrumors 65816
Original poster
Aug 24, 2008
1,014
275
I feel sorry for OP, but the vast majority of people is very happy with OLED in their TV’s, phones and tablets. Apple cannot possibly manufacture bespoke electronics for every subset of people… 🤷🏻‍♂️
Thank you very much for the sympathy. It is truly maddening that I suffer from sensitivity.

Flicker-Free displays exist on the market and are even touted when available. (Lenovo/Razer).

OLED consumer TVs don’t exhibit PWM as they are not power regulated in the quest to save battery life.

It is achievable on OLEDs, but phones and manufacturers want to show insane battery life.

I get it, that is the goal on a mobile device right? So, why not offer a flicker free mode with notification that brightness and power will be reduced?

Grrr
 

jimmy_uk

macrumors 68020
Oct 19, 2015
2,478
3,305
UK
Have you managed to determine what PWM frequencies affect you? It can’t be all of them.
Sadly no and I also have an issue with some of Apple's newer iPads that are reported as not having PWM, so it might be dithering? Or it might be all down to the software as some users are complaining their iPhone XR and/or 11, which were perfectly comfortable before, are now experiencing strain after the iOS 17 update. I've stuck to 16.7.2 on my iP11, just in case.
 
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jimmy_uk

macrumors 68020
Oct 19, 2015
2,478
3,305
UK
Besides the issues with proving the exact cause of this phenomenon, what would you have Apple do about this? Going back to LCD would be the biggest PR (and subsequently, sales) disaster in the history of Apple. Producing a second line of iPad Pro (minus?) with LCD would be very expensive and would set a different kind of sales record. Change the frequency? To what? Everyone seems to be sensitive to a different frequency range, so there's no single frequency that'll be perfect for everyone. I don't see any option for Apple besides what they're already doing: not worrying about it and continuing to adopt the newest tech whenever they consider it "ready."
Apple could easily give us many more accessibility options, a DC dimming/flicker-reduction option that ensures the phone's display is on 99.51% of the time during the duty cycle like Motorola offers, for example. It might not fix things for everyone, but options are always good.

I dream that we could order a bespoke device and choose OLED or LCD. It would cost more as it would need a dedicated production line, but I would gladly pay as it's been many years since I've been able to own a flagship product.
 
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Timpetus

macrumors 6502
Jun 13, 2014
400
923
Orange County, CA
Apple could easily give us many more accessibility options, a DC dimming/flicker-reduction option that ensures the phone's display is on 99.51% of the time during the duty cycle like Motorola offers, for example. It might not fix things for everyone, but options are always good.

I dream that we could order a bespoke device and choose OLED or LCD. It would cost more as it would need a dedicated production line, but I would gladly pay as it's been many years since I've been able to own a flagship product.
I hope I didn't come off as unsympathetic, because this really does sound like a nightmare. I guess the best solution that might be realistically possible would be a mode you can turn on that keeps the display at full brightness to minimize flicker. My understanding of the tech involved is that full brightness would minimize the amount of flickering, but it would mean reduced battery life. Someone correct me if I'm wrong about how PWM works...
 

rui no onna

Contributor
Oct 25, 2013
14,915
13,259
I hope I didn't come off as unsympathetic, because this really does sound like a nightmare. I guess the best solution that might be realistically possible would be a mode you can turn on that keeps the display at full brightness to minimize flicker. My understanding of the tech involved is that full brightness would minimize the amount of flickering, but it would mean reduced battery life. Someone correct me if I'm wrong about how PWM works...

If you disable auto-brightness, you can keep the screen at full brightness all the time.

That said, too bright screens give me headaches as well and even setting Reduce White Point to 100% is still way too bright.
 

TheRealAlex

macrumors 68030
Sep 2, 2015
2,982
2,248
The display backlight flickers at 6401 Hz that’s the 2022 M2 Pro. I glad I don’t perceive this issue.

I do detect the text Smear, or trails of text when scrolling if Tandem OLED solves that it’s a huge W.
 

chronos1919

macrumors member
Oct 26, 2016
43
65
Have you managed to determine what PWM frequencies affect you? It can’t be all of them.
Seems to impact everyone differently, with some being far more sensitive than others.

This is a very real issue with unfortunately not enough research for us impacted to understand exactly what is happening. For me, PWM causes dry eyes and sensitivity. Higher frequency PWM takes longer to impact me but still does with extended use. Low frequency PWM screens bother me within minutes of use. Dry, gritty eyes that get painful and red and take days of light screen use to recover from. As a tech enthusiast it's incredibly frustrating.

The worst offender for me was the Steam Deck OLED. Love the idea behind the handheld but it was brutal on my eyes. Multiple attempts at using it confirm this while I could use screens without PWM all day without issue. Notebook check lists the frequency of the Steam Deck OLED at 360, which is incredibly low. They have iPhone 15 Pro Max listed at 240 and that's about as bad as the Steam Deck OLED for me. Using it to check messages and light, quick tasks are fine. Trying to watch videos on it kills me. Notebookcheck has the M1 MacBook Pro listed at 14880 and I don't have issues with it unless I use it all day. The 12.9 Mini LED iPad Pro was the first iPad to impact my eyes negatively. My previous pro, with IPS screen didn't bother me in the slightest. With the M2 iPad Pro I can only use it for a few hours before my eyes get dry and gritty.

I've been experiencing this for the last 7-8 years and have done plenty of testing that proves, for me, it's specific screens. The actual use-case, hydration, blinking, etc. don't better. Just the amount of time that I use the screen without breaks and how aggressive the PWM is.

We spend a lot more time looking at screens than ever in human history and the technology behind screens is changing rapidly and often doesn't have ample testing done for safety. I'm not surprised that there's a growing subset of people that are now experiencing issues. Hopefully more screen manufacturers start to look into eye comfort rather than just bigger and brighter.
 
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rui no onna

Contributor
Oct 25, 2013
14,915
13,259
Seems to impact everyone differently, with some being far more sensitive than others.

This is a very real issue with unfortunately not enough research for us impacted to understand exactly what is happening. For me, PWM causes dry eyes and sensitivity. Higher frequency PWM takes longer to impact me but still does with extended use. Low frequency PWM screens bother me within minutes of use. Dry, gritty eyes that get painful and red and take days of light screen use to recover from. As a tech enthusiast it's incredibly frustrating.

The worst offender for me was the Steam Deck OLED. Love the idea behind the handheld but it was brutal on my eyes. Multiple attempts at using it confirm this while I could use screens without PWM all day without issue. Notebook check lists the frequency of the Steam Deck OLED at 360, which is incredibly low. They have iPhone 15 Pro Max listed at 240 and that's about as bad as the Steam Deck OLED for me. Using it to check messages and light, quick tasks are fine. Trying to watch videos on it kills me. Notebookcheck has the M1 MacBook Pro listed at 14880 and I don't have issues with it unless I use it all day. The 12.9 Mini LED iPad Pro was the first iPad to impact my eyes negatively. My previous pro, with IPS screen didn't bother me in the slightest. With the M2 iPad Pro I can only use it for a few hours before my eyes get dry and gritty.

I've been experiencing this for the last 7-8 years and have done plenty of testing that proves, for me, it's specific screens. The actual use-case, hydration, blinking, etc. don't better. Just the amount of time that I use the screen without breaks and how aggressive the PWM is.

We spend a lot more time looking at screens than ever in human history and the technology behind screens is changing rapidly and often doesn't have ample testing done for safety. I'm not surprised that there's a growing subset of people that are now experiencing issues. Hopefully more screen manufacturers start to look into eye comfort rather than just bigger and brighter.

Thankfully, there are 13" and 1TB options for the Air now. I'm hoping the Air sticks with LCD longer. I might need to go that route by the time I need to upgrade my M1 iPad Pro.

I do wish FaceID would trickle down to the Air though. That's the only Pro-only feature that's on my wish list. 16GB RAM is nice to have but 8GB ain't bad particularly when the 512GB -> 1TB upgrade costs $200 on the Air.
 

leifp

macrumors 6502a
Feb 8, 2008
522
501
Canada
Thank you very much for the sympathy. It is truly maddening that I suffer from sensitivity.

Flicker-Free displays exist on the market and are even touted when available. (Lenovo/Razer).

OLED consumer TVs don’t exhibit PWM as they are not power regulated in the quest to save battery life.

It is achievable on OLEDs, but phones and manufacturers want to show insane battery life.

I get it, that is the goal on a mobile device right? So, why not offer a flicker free mode with notification that brightness and power will be reduced?

Grrr
The Tech Chap has a review of the new iPad Pros where he actually compares PWM rates. He mentions that the OLED iPads have much quicker rates than prior iPads. Have a watch and see whether that will matter to you.
 
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chronos1919

macrumors member
Oct 26, 2016
43
65
Thankfully, there are 13" and 1TB options for the Air now. I'm hoping the Air sticks with LCD longer. I might need to go that route by the time I need to upgrade my M1 iPad Pro.

I do wish FaceID would trickle down to the Air though. That's the only Pro-only feature that's on my wish list. 16GB RAM is nice to have but 8GB ain't bad particularly when the 512GB -> 1TB upgrade costs $200 on the Air.
Indeed. I’m swapping out my 14” M1 Pro for a 15” M3 Air. Going to try the new iPad Pro but I’m expecting it will bother my eyes. If so, I’ll be buying an iPad Air. Waiting to see if the M2 iPad Air is PWM free. A shame if I can’t tolerate the new iPad Pro because I really want the new folio keyboard.
 
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Shirasaki

macrumors P6
May 16, 2015
16,263
11,763
If you disable auto-brightness, you can keep the screen at full brightness all the time.

That said, too bright screens give me headaches as well and even setting Reduce White Point to 100% is still way too bright.
Or maybe something of the effect of raising PWM frequency like others mentioned above at the cost of battery life, to help reducing the eye strain.
 
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Shirasaki

macrumors P6
May 16, 2015
16,263
11,763
My previous pro, with IPS screen didn't bother me in the slightest. With the M2 iPad Pro I can only use it for a few hours before my eyes get dry and gritty.
Which really makes me wonder why OLED can’t incorporate what IPS did to help reduce eye strain, just offer it as an option for those folks not asking for high level real life color accuracy, which is darn near all of them.
Hopefully more screen manufacturers start to look into eye comfort rather than just bigger and brighter.
Unfortunately providing eye comfort doesn’t seem to drive sales as good as brighter and bigger screen would. I know Chinese phone manufacturers Pretend to care more but they don’t really do enough either. It might as well be similar to natural selection, that is, people with sensitivity get selected out eventually and who’s left are those that don’t have such issues.
 
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