Have you ever ever checked out your telephone and gotten a headache? Typically, it simply means you have been on it too lengthy and have to take a break. For some of us, nevertheless, it may imply you have developed PWM flicker sensitivity as a result of manner your telephone’s show works.
PWM, or pulse width modulation, is a technique of flickering a show to idiot the human eye into seeing a brighter or dimmer show. It is a tactic utilized by most of the finest telephones — together with the Apple iPhone, Google Pixel, Samsung Galaxy, and lots of others — for a variety of causes and has solely develop into increasingly more widespread as telephones proceed to change to OLED shows.
The result’s a telephone which may make you are feeling nauseous, make your eyes damage, offer you a headache, and even make you wish to curl up in a ball for hours. So what’s PWM, why is it dangerous to some folks, and what are you able to do about it? Aside from getting a brand new PWM-friendly telephone, we have a number of solutions that may assist make your present telephone a bit extra eye-friendly.
What’s PWM dimming?
PWM dimming works by flashing the display screen on and off in a short time. Consider it a bit like watching a film, which is comprised of images being proven back-to-back many instances per second.
Your mind interprets this fast development of photographs as motion in a film, however within the case of PWM-dimmed telephones, your eyes see a brighter or dimmer picture relying on how usually your telephone’s show is on or off per second.
PWM dimming works by flashing the display screen on and off in a short time, which tips your eyes into seeing a “brighter” or “dimmer” display screen.
The rationale that is totally different from a film is that film frames are evenly lit in development from one to the subsequent. PWM flashing, nevertheless, alternates between 100% brightness and 0% brightness, offering a harsh, stark distinction to your eyes and mind.
Graphs just like the one above — which present the Samsung Galaxy Z Fold 5‘s outer show at 100% brightness — present the sample of on/off cycles that your eyes do not see however your mind perceives. The distinction between the very best and lowest factors is the modulation, which is outlined as the share distinction between the brightest and dimmest values.
Think about a brilliant mild flashing consistently at you in a darkish room and you may shortly perceive why that is problematic.
In layman’s phrases, that merely means how brilliant the show will get for a break up second earlier than turning off momentarily, then repeating the cycle over and over a number of hundred instances per second.
As you decrease the brightness slider, the display screen is not truly getting dimmer. As an alternative, what’s occurring is that the display screen stays off for longer durations of time because it continues to flash on and off a whole lot of instances per second. Think about a brilliant mild flashing at you consistently in a darkish room, and you may shortly perceive why that is problematic.
That distinction between the display screen being on for a break up second adopted by staying off for a break up second is extremely jarring to the human mind. Whereas it does not have an effect on some folks as negatively as others, it is nonetheless exposing you to a strobing mild all all through the day. We all know from analysis that this type of publicity is unhealthy in your well being.
Why do telephones use PWM dimming?
Smartphone shows typically use two primary strategies to regulate brightness. The most typical technique was once what’s referred to as DC dimming, which controls the quantity of voltage despatched to an LED panel. The extra energy you provide, the brighter the LED will get. Scale back that energy, and the LED will get dimmer.
However, as smartphones have begun to change to OLED shows increasingly more usually, producers are utilizing PWM to handle brightness as a substitute of DC dimming. This sounds ridiculous — and, in lots of circumstances, it really is — however there’s a legitimate cause for all of it.
First, let’s shortly look at the distinction between LCD panels and OLED shows. An LCD panel incorporates a absolutely white backlight behind coloured pixels. These coloured pixels act like a filter for the sunshine however don’t have anything to do with the brightness or depth of the sunshine itself. They’re fully separate items of the show puzzle.
This backlight may be dimmed individually from the coloured pixels by decreasing energy to the white LED backlight, thus, dimming that white mild like a lightweight bulb.
OLED shows use individually-lit pixels, usually made up of pink, inexperienced, and blue sub-pixels. Every of those sub-pixels offers off its personal mild, so the depth of the brightness is immediately tied to the colour.
As OLED pixels are dimmed, the accuracy and depth of the colour additionally dim. A number of years in the past, OnePlus experimented with a totally DC-dimmed OLED panel on the OnePlus 6 and 6T. Nonetheless, when the brightness dropped beneath 30% or so, greys would develop into inexperienced, and different colours simply would not look proper.
Because of this, producers like Samsung use PWM dimming. When a show makes use of PWM dimming, it is giving 100% energy to every pixel, making certain that shade accuracy and depth keep the identical regardless of the brightness stage.
It is a sensible answer to a technological drawback, nevertheless it forgets to take two main issues into consideration: human eyes and brains.
Some producers, like Motorola, Xiaomi, and Nothing, have begun to supply hybrid options which are far simpler on human eyes and brains, all whereas retaining the visible high quality we count on from OLED shows.
Some producers are lastly realizing that strobing a lightweight at customers all day lengthy is not wholesome and at the moment are utilizing DC Dimming above 50% brightness.
At increased brightness ranges on telephones just like the Motorola Edge Plus (2023), Nothing Cellphone (2), and Xiaomi 13, DC dimming controls the voltage stage of every particular person pixel. Every of those telephones makes use of DC dimming right down to a sure brightness stage — usually round 50% brightness — then switches to PWM dimming beneath that stage.
This ensures that customers aren’t uncovered to the strobe mild flashing of a PWM show all day lengthy. As an alternative, this solely happens in decrease mild if the consumer needs to decrease the brightness stage.
Waveforms and the mind
Dialing down additional into the causes of PWM/flicker-sensitivity, a number of components appear to have an effect on most individuals on this class. When utilizing a software to measure flicker parameters, the top end result comes out trying like a waveform on an oscilloscope. If I’ve already misplaced you, maintain tight. I promise I will preserve this straightforward.
Probably the most snug sample is the sine wave, which is represented by a easy curve that evenly strikes up and down at a gentle fee. Incandescent lightbulbs sport this type of wave as a result of the filament inside by no means turns fully off throughout the ordinary oscillating energy cycle that comes from energy strains. Shows that make the most of PWM dimming may be snug in the event that they adhere to the sine wave sample, however this comes with caveats.
Shows that come throughout utilizing different waveform patterns above are likely to flicker at various or harsher charges. I’ve discovered this to be extraordinarily uncomfortable most often. In the event you scroll again as much as the Fold 5 instance above, you may see it is utilizing a sq. waveform which is a really harsh on/off sample.
Conversely, in case you have a look at the sample of the Motorola Edge Plus (2023) within the picture beneath, you may see that it is a pretty flat waveform with very shallow dips at evenly-spaced intervals.
Lastly, I will have a look at the PWM fee, which implies how briskly the show can flicker per second. Most Samsung Galaxy and Google Pixel telephones flicker at a really low fee of 240Hz, or 240 instances per second.
Apple makes use of a frequency of 480Hz even supposing it makes use of related kinds of OLED shows as Galaxy and Pixel telephones. Greater numbers can result in better consolation, even when utilizing PWM to “dim” a show, so iPhones are theoretically extra snug to take a look at than Galaxy or Pixel telephones.
Greater (quicker) PWM charges can result in better consolation when utilizing a show that “dims” by utilizing pulse width modulation.
However the telephones we suggest right here usually go nicely past that in the event that they use PWM in any respect. The Honor 90, for instance, makes use of an extraordinarily excessive PWM fee of three,840Hz. That is 8x quicker than the iPhone and 16x quicker than most Galaxy or Pixel telephones. At this fee, even PWM flickering is probably going usable for most individuals.
Different telephones on this record, just like the Nothing Cellphone (2) and the Xiaomi 13, use a PWM fee of 1,920Hz when brightness will get decrease. In any other case, at 50% brightness or above, these telephones make the most of DC dimming, an influence regulation technique that reduces the voltage to particular person LEDs within the show, making them basically flicker-free.
The right way to cope with PWM sensitivity
Being delicate to flickering lights or shows is just no enjoyable. Flickering mild sources could cause eye straight, complications, dizziness, a way of vertigo, nausea, and loads of uncomfortable or painful sensations. Fortunately, there are methods of managing these signs and issues you are able to do to assist forestall them within the first place.
Irrespective of which telephone you employ, being PWM or flicker-sensitive means it is best to take some precautions to make sure you’re not exposing your self to an excessive amount of flicker. Listed here are some suggestions and tips to assist make your telephone simpler on the eyes.
See an optometrist
Before everything, in case you’re experiencing any of the signs described above whereas your telephone, go see an optometrist. I personally handled elevated sensitivity and harsher signs over a interval of some months earlier than I went to an optometrist, and I could not have been happier with my expertise.
In my case, one eye had astigmatism, and my optometrist was in a position to give me a brand new studying glasses prescription to appropriate for that astigmatism. Many people who find themselves delicate to flickering mild and flickering smartphone shows even have astigmatism, and correcting for this drawback may very nicely clear up your sensitivity subject.
In my case, I can use flickering telephones as long as I put on my glasses, however even that is inside a restrict. I do not dare use any of those flickering telephones beneath 50% brightness or in a darkish room, and I typically can’t use them once I’m not sporting my glasses.
For me, meaning I am unable to use my telephone to navigate whereas driving since my glasses are for studying solely, and it implies that it is extremely inconvenient (or unattainable) to take a look at flickering telephones for any size of time whereas doing bodily actions away from residence.
Do not use automated brightness
Computerized brightness is a superb idea when a telephone makes use of DC dimming. For telephones that use PWM to dim, automated brightness is a fast option to get a headache. As an alternative, handle the brightness your self and preserve it at a stage that you simply really feel is manageable and does not offer you eye pressure.
That is as a result of PWM-dimmed telephones flicker extra harshly at decrease brightness ranges, rising the potential for PWM illness.
I like to recommend utilizing this follow along side the subsequent tip.
Strive a screen-dimming app
Do not use your telephone’s brightness slider to regulate brightness. As an alternative, I might suggest preserving the system brightness slider at 100% to maintain display screen modulation as little as potential. Then, use a screen-dimming app to regulate brightness since it really works in a different way.
First off, I might by no means suggest dimming most smartphone shows below 50% in case you’re delicate to mild flicker. Even many of the most eye-friendly smartphone shows begin to do humorous issues beneath 50% to be able to keep excessive picture high quality at low brightness values.
I’ve tried quite a bit of screen-dimming apps, however this display screen and notification-dimming app is my all-time favourite. Not solely does it function a helpful management panel that stays in your notification shade always and has a fast toggle button, nevertheless it truly dims notifications and system-level dialogs.
Many display screen dimming apps will solely dim apps by including a gray overlay on high of the display screen which is not allowed to be displayed over system-level UI components. Worse but, most of those apps do not allow you to click on “safe” buttons which implies you usually must disable them simply to do regular issues in your telephone.
The app I really useful has none of those issues and works as you’ll count on it to.
Do not use your telephone in a darkish room
Utilizing your telephone in a darkish room is without doubt one of the quickest methods to develop these terrible emotions of PWM illness. It does not matter what brightness stage your machine is at — particularly in case you’re utilizing a telephone that makes use of PWM to dim the show. Sitting in a darkish room a brilliant telephone simply is not good in your eyes.
As an alternative, attempt to preserve the ambient lighting within the room at about the identical brightness stage as your telephone. Computerized brightness would do that already, however for us PWM-sensitive of us, automated brightness is not normally an possibility since telephones are likely to flicker extra at darker brightness ranges.
Moreover, I might suggest utilizing a flicker meter to check the lightbulbs in your house to make sure they do not flicker. If you do not have a specialised mild meter, this flicker meter app is free and will help you detect mild bulb flicker.
I would not use its measurements as a precise science, although. Quite, simply use it to assist detect bulbs that may be changed with flicker-free variations like these Sylvania flicker-free LED bulbs. I take advantage of these in my residence and love them.
Do not use darkish theme on some telephones
It’d sound bizarre, however OLED shows utilizing PWM modulate extra when displaying darker colours. That is as a result of shade and light-weight depth are linked collectively in a single LED diode, as I defined within the part manner above. Telephones utilizing OLED shows that use DC Dimming are simply advantageous to make use of darkish mode of any shade, as evidenced by the photographs beneath.
Most darkish theme apps do not use a black background, which might truly flip particular person OLED pixels fully off. As an alternative, many builders and smartphone corporations use a darkish gray background which is extra dangerous to your eyes than a totally black or fully white background.
Picture 1 of 2
Do not imagine me? Try the photographs above, taken at a really sluggish shutter velocity and excessive ISO to seize the PWM fee on every shade. The black bars you see working from the highest to the underside of the show are how the digital camera sees the PWM fee. The thicker the bar, the extra modulation happens to create a shade.
Discover that the entire mild colours have a thinner black bar, and all of the darker colours have a a lot thicker bar? These pixels must flicker much more to point out that darkish shade as a result of, when utilizing PWM, the brightness of a pixel is managed by the size of time the show is off throughout the pulsing cycle.
Discover the greyscale picture, particularly, as these colours are the precise shades utilized in Android’s darkish theme throughout many producers and apps.
Now, if we have a look at a telephone that does correct DC dimming — the Motorola Edge Plus (2023) — you may see that every one colours are equally represented and have zero flicker distinction seen between them. That features darker greyscale photographs.
Picture 1 of 2
On telephones that use PWM-dimmed OLED shows, use a lightweight theme in your telephone’s UI after which cherry-pick apps which have settings for “lights out” mode. On apps like Twitter X, Lights Out mode makes all the background black and solely illuminates the show when different colours or textual content are current. That ensures that much less of your show is awake to modulate on telephones that use PWM dimming.
Lock the refresh fee
It’d sound bizarre, however locking a telephone’s show refresh fee is usually simpler on the eyes than a dynamic refresh fee on telephones that use PWM dimming. There are a whole lot of theories as to why that is the case, however I personally suppose it is the variability of the refresh fee on LTPO OLED shows that is taking part in the largest half.
Because the refresh fee adjustments consistently on these shows relying on what app you are utilizing or what you are utilizing the telephone for — however the PWM fee seemingly stays fixed — your eyes are consistently bombarded with various ranges of unnatural show refresh patterns.
Go into your telephone’s show settings and discover the refresh fee possibility. Typically that is referred to as “Easy show” or one thing related. Both flip it off or choose a single refresh fee to check. Some telephones will let you choose from a number of totally different charges to lock the show at. My private eye-friendly favourite telephone, the Motorola Edge Plus (2023), means that you can choose from 60Hz, 120Hz, or 165Hz.
Relying on the show sort, selecting the bottom potential refresh fee of 60Hz may truly be probably the most snug. Give it a shot and see how you are feeling!
Get a greater telephone
The truth is that our definition of “the very best telephones” usually revolves round processor speeds, digital camera high quality, or different components however usually neglects how unhealthy these telephones’ shows are for our eyes.
Fortunately, the finest telephones for PWM-sensitive folks all supply nice experiences, processing speeds, high quality cameras, and, most significantly, shows that do not damage to take a look at.
Motorola Edge Plus (2023)
Motorola is again, child. Sporting a beautiful design, an eye-friendly OLED show, a blazing-fast processor, and 2-day battery life, the Motorola Edge Plus (2023) is the very best telephone Motorola has made in years.