Have you ever checked out your telephone and gotten a headache? Sometimes, it simply means you’ve got been on it too lengthy and want to take a break. For some people, nonetheless, it may imply you’ve got developed PWM flicker sensitivity due to the way in which your telephone’s display works.
PWM, or pulse width modulation, is a technique of flickering a display to idiot the human eye into seeing a brighter or dimmer display. It’s a tactic utilized by lots of the finest telephones — together with the Apple iPhone, Google Pixel, Samsung Galaxy, and many others — for a lot of causes and has solely develop into extra and extra widespread as telephones proceed to swap to OLED shows.
The consequence is a telephone which may make you are feeling nauseous, make your eyes damage, provide you with a headache, and even make you need to curl up in a ball for hours. So what is PWM, why is it dangerous to some individuals, and what are you able to do about it? Other than getting a brand new PWM-friendly telephone, we have got a number of options that can assist make your present telephone slightly extra eye-friendly.
What is PWM dimming?
PWM dimming works by flashing the display screen on and off in a short time. Think of 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 pictures 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 display is on or off per second.
PWM dimming works by flashing the display screen on and off in a short time, which methods your eyes into seeing a “brighter” or “dimmer” display screen.
The cause this is totally different from a film is that film frames are evenly lit in development from one to the following. PWM flashing, nonetheless, 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 display 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 proportion distinction between the brightest and dimmest values.
Imagine a vibrant gentle flashing always at you in a darkish room and you will shortly perceive why this is problematic.
In layman’s phrases, that merely means how vibrant the display will get for a break up second earlier than turning off momentarily, then repeating the cycle over and over once more a number of hundred instances per second.
As you decrease the brightness slider, the display screen is not really getting dimmer. Instead, what’s taking place is that the display screen stays off for longer durations of time as it continues to flash on and off tons of of instances per second. Imagine a vibrant gentle flashing at you always in a darkish room, and you will shortly perceive why this 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. While it does not have an effect on some individuals as negatively as others, it’s nonetheless exposing you to a strobing gentle all all through the day. We know from analysis that this sort of publicity is dangerous on your well being.
Why do telephones use PWM dimming?
Smartphone shows typically use two principal strategies to management brightness. The most typical methodology used to be what’s known 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. Reduce that energy, and the LED will get dimmer.
But, as smartphones have begun to swap to OLED shows extra and extra usually, producers are utilizing PWM to handle brightness as an alternative of DC dimming. This sounds ridiculous — and, in lots of instances, it actually is — however there is a sound cause for all of it.
First, let’s shortly look at the distinction between LCD panels and OLED shows. An LCD panel incorporates a totally 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 are utterly separate items of the display puzzle.
This backlight may be dimmed individually from the coloured pixels by lowering energy to the white LED backlight, thus, dimming that white gentle like a light-weight bulb.
OLED shows use individually-lit pixels, usually made up of pink, inexperienced, and blue sub-pixels. Each of those sub-pixels offers off its personal gentle, 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. However, when the brightness dropped beneath 30% or so, greys would develop into inexperienced, and different colours simply would not look proper.
For this cause, producers like Samsung use PWM dimming. When a display makes use of PWM dimming, it’s giving 100% energy to every pixel, making certain that colour accuracy and depth keep the identical regardless of the brightness stage.
It’s an excellent answer to a technological downside, however it forgets to take two main issues under consideration: human eyes and brains.
Some producers, like Motorola, Xiaomi, and Nothing, have begun to provide hybrid options which might be 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 light-weight at customers all day lengthy is not wholesome and at the moment are utilizing DC Dimming above 50% brightness.
At larger brightness ranges on telephones just like the Motorola Edge Plus (2023), Nothing Phone (2), and Xiaomi 13, DC dimming controls the voltage stage of every particular person pixel. Each of those telephones makes use of DC dimming 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 gentle flashing of a PWM display all day lengthy. Instead, this solely happens in decrease gentle if the person desires to decrease the brightness stage.
Waveforms and the mind
Dialing down additional into the causes of PWM/flicker-sensitivity, just a few components appear to have an effect on most individuals on this class. When utilizing a software to measure flicker parameters, the tip consequence comes out wanting like a waveform on an oscilloscope. If I’ve already misplaced you, maintain tight. I promise I’ll preserve this straightforward.
The most snug sample is the sine wave, which is represented by a easy curve that evenly strikes up and down at a gentle charge. Incandescent lightbulbs sport this sort of wave as a result of the filament inside by no means turns utterly off throughout the typical oscillating energy cycle that comes from energy traces. Displays 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.
Displays that come throughout utilizing different waveform patterns above have a tendency to flicker at various or harsher charges. I’ve discovered this to be extraordinarily uncomfortable most often. If you scroll again up to the Fold 5 instance above, you will see it’s 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 will see that it’s a reasonably flat waveform with very shallow dips at evenly-spaced intervals.
Lastly, I’ll have a look at the PWM charge, which implies how quick the display can flicker per second. Most Samsung Galaxy and Google Pixel telephones flicker at a really low charge of 240Hz, or 240 instances per second.
Apple makes use of a frequency of 480Hz even supposing it makes use of comparable forms of OLED shows as Galaxy and Pixel telephones. Higher numbers can lead to better consolation, even when utilizing PWM to “dim” a display, so iPhones are theoretically extra snug to have a look at than Galaxy or Pixel telephones.
Higher (quicker) PWM charges can lead to better consolation when utilizing a display that “dims” through the use of pulse width modulation.
But the telephones we suggest right here usually go effectively past that in the event that they use PWM in any respect. The Honor 90, for instance, makes use of an extraordinarily excessive PWM charge of three,840Hz. That’s 8x quicker than the iPhone and 16x quicker than most Galaxy or Pixel telephones. At this charge, even PWM flickering is possible usable for most individuals.
Other telephones on this checklist, just like the Nothing Phone (2) and the Xiaomi 13, use a PWM charge of 1,920Hz when brightness will get decrease. Otherwise, at 50% brightness or above, these telephones make the most of DC dimming, an influence regulation methodology that reduces the voltage to particular person LEDs within the display, making them primarily flicker-free.
How to deal with PWM sensitivity
Being delicate to flickering lights or shows is merely no enjoyable. Flickering gentle sources could cause eye straight, complications, dizziness, a way of vertigo, nausea, and loads of uncomfortable or painful sensations. Thankfully, there are methods of managing these signs and issues you are able to do to assist forestall them within the first place.
No matter which telephone you utilize, being PWM or flicker-sensitive means you must take some precautions to make sure you’re not exposing your self to an excessive amount of flicker. Here are some suggestions and methods to assist make your telephone simpler on the eyes.
See an optometrist
First and foremost, in case you’re experiencing any of the signs described above whereas your telephone, go see an optometrist. I personally dealt with 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 gentle and flickering smartphone shows even have astigmatism, and correcting for this downside may very effectively remedy your sensitivity situation.
In my case, I’m in a position to use flickering telephones as long as I put on my glasses, however even this 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 not use them when I’m not sporting my glasses.
For me, which means I can not use my telephone to navigate whereas driving since my glasses are for studying solely, and it implies that it’s extremely inconvenient (or unattainable) to have a look at flickering telephones for any size of time whereas doing bodily actions away from house.
Don’t use computerized brightness
Automatic brightness is a fantastic idea when a telephone makes use of DC dimming. For telephones that use PWM to dim, computerized brightness is a fast means to get a headache. Instead, handle the brightness your self and preserve it at a stage that you just really feel is manageable and does not provide you with eye pressure.
That’s as a result of PWM-dimmed telephones flicker extra harshly at decrease brightness ranges, growing the potential for PWM illness.
I like to recommend utilizing this apply in conjunction with the following tip.
Try a screen-dimming app
Don’t use your telephone’s brightness slider to regulate brightness. Instead, I might suggest conserving the system brightness slider at 100% to preserve display screen modulation as little as doable. Then, use a screen-dimming app to management brightness since it works otherwise.
First off, I might by no means suggest dimming most smartphone shows below 50% in case you’re delicate to gentle flicker. Even many of the most eye-friendly smartphone shows begin to do humorous issues beneath 50% so as to keep excessive picture high quality at low brightness values.
I’ve tried lots of screen-dimming apps, however this display screen and notification-dimming app is my all-time favourite. Not solely does it characteristic a useful management panel that stays in your notification shade always and has a fast toggle button, however it really 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 recurrently have to disable them simply to do regular issues in your telephone.
The app I really helpful has none of those issues and works as you’d count on it to.
Don’t use your telephone in a darkish room
Using your telephone in a darkish room is one of many quickest methods to develop these terrible emotions of PWM illness. It does not matter what brightness stage your system is at — particularly in case you’re utilizing a telephone that makes use of PWM to dim the display. Sitting in a darkish room a vibrant telephone simply is not good on your eyes.
Instead, attempt to preserve the ambient lighting within the room at about the identical brightness stage as your telephone. Automatic brightness would do that already, however for us PWM-sensitive people, computerized brightness is not often an possibility since telephones have a tendency to flicker extra at darker brightness ranges.
Additionally, I might suggest utilizing a flicker meter to check the lightbulbs in your house to guarantee they do not flicker. If you do not have a specialised gentle meter, this flicker meter app is free and may also help you detect gentle bulb flicker.
I would not use its measurements as an actual science, although. Rather, 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 house and love them.
Don’t use darkish theme on some telephones
It may sound bizarre, however OLED shows utilizing PWM modulate extra when displaying darker colours. That’s as a result of colour and gentle depth are linked collectively in a single LED diode, as I defined within the part means above. Phones utilizing OLED shows that use DC Dimming are simply advantageous to use darkish mode of any shade, as evidenced by the pictures beneath.
Most darkish theme apps do not use a black background, which might really flip particular person OLED pixels utterly off. Instead, many builders and smartphone corporations use a darkish gray background which is extra dangerous to your eyes than a very black or utterly white background.
Image 1 of 2
Don’t imagine me? Check out the pictures above, taken at a really sluggish shutter pace and excessive ISO to seize the PWM charge on every colour. The black bars you see working from the highest to the underside of the display are how the digicam sees the PWM charge. The thicker the bar, the extra modulation happens to create a colour.
Notice that all the gentle colours have a thinner black bar, and all of the darker colours have a a lot thicker bar? Those pixels have to flicker much more to present that darkish colour as a result of, when utilizing PWM, the brightness of a pixel is managed by the size of time the display is off throughout the pulsing cycle.
Notice 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 will see that each one colours are equally represented and have zero flicker distinction seen between them. That consists of darker greyscale pictures.
Image 1 of 2
On telephones that use PWM-dimmed OLED shows, use a light-weight theme in your telephone’s UI and then cherry-pick apps which have settings for “lights out” mode. On apps like Twitter X, Lights Out mode makes the whole background black and solely illuminates the display when different colours or textual content are current. That ensures that much less of your display is awake to modulate on telephones that use PWM dimming.
Lock the refresh charge
It may sound bizarre, however locking a telephone’s display refresh charge is typically simpler on the eyes than a dynamic refresh charge on telephones that use PWM dimming. There are a variety of theories as to why this is the case, however I personally suppose it’s the variability of the refresh charge on LTPO OLED shows that is enjoying the most important half.
Since the refresh charge modifications always on these shows relying on what app you are utilizing or what you are utilizing the telephone for — however the PWM charge possible stays fixed — your eyes are always bombarded with various ranges of unnatural display refresh patterns.
Go into your telephone’s display settings and discover the refresh charge possibility. Sometimes this is known as “Smooth display” or one thing comparable. Either flip it off or choose a single refresh charge to check. Some telephones permit you to choose from a number of totally different charges to lock the display at. My private eye-friendly favourite telephone, the Motorola Edge Plus (2023), permits you to choose from 60Hz, 120Hz, or 165Hz.
Depending on the display sort, selecting the bottom doable refresh charge of 60Hz may really be essentially the most snug. Give it a shot and see how you are feeling!
Get a greater telephone
The actuality is that our definition of “the most effective telephones” usually revolves round processor speeds, digicam high quality, or different components however usually neglects how dangerous these telephones’ shows are for our eyes.
Thankfully, the most effective telephones for PWM-sensitive individuals all provide nice experiences, processing speeds, high quality cameras, and, most significantly, shows that do not damage to have a look at.
Motorola Edge Plus (2023)
Motorola is again, child. Sporting a stunning design, an eye-friendly OLED display, a blazing-fast processor, and 2-day battery life, the Motorola Edge Plus (2023) is the most effective telephone Motorola has made in years.