Do OLED screens really have no PWM on maximum brightness?

Deepdeep

All the OLED phone and tablet screens that I have examined with a phone camera (set on manual with a shutter speed of 1/4000) look like they have PWM even at 100% brightness, whereas the non-OLED devices I have looked at that seem to use PWM don't look like they have PWM at 100%.

So, do OLED devices really have no PWM at 100% or do they still have PWM at 100% but just with short off periods and are therefore less problematic but not totally unproblematic? If any of you have oscilloscope pics of OLED waveforms at 100% brightness could you please share some?

NB I feel the pics on notebookcheck may not be quite revelatory of what's actually going on, but it maybe just that I'm not interpreting them right.

qb74

Deepdeep Because they do.

First off, OLED is the superior display tech, to clear that away. Infinite contrast ratios and very fast response times are the biggest benefits of OLED vs LCD

PWM (Pulse Width Modulation, or specifically, multi strobe PWM, the one that most have an issue with here from what I gather) is a technology used to dim the screen by flashes in appropriate duty cycles.

By design, at 100% brightness (duty cycle), PWM should never be a thing. There are LCD's which suffer from this too, it's not OLED specific. It's a panel specific thing.

From what I gather, low PWM frequency (different from refresh rate/vertical frequency of a display) is mostly used as a way to cut corners in a device by using a cheaper controller for adjusting the backlight of the panel, thus resulting in the low refresh rate flicker we have on modern OLED smartphones and older LCD displays.

Ever since VESA made the Freesync certification (monitors) a standard, most of the low end backlight contollers have been cleared (or use a very high pwm dimming frequency, imperceptible to humans)

Perhaps if some governing body like VESA jumps in the same way for phones might yield to much better OLED's for people suffering from PWM dimming related eyestrain

However, Freesync cert is still not a viable way to 100% be sure the display is without flicker across it's entire brightness range too! As I've mentioned, it's still panel specific

Yes, desktop OLED's/newer modern LCD's are able to dim themselves without PWM flicker across most of it's brightness range (with slight/unnoticable flicker on lower ranges for OLEDs, LCD's mostly have none), for example:
Aorus 48" OLED (CTRL+F for "PWM" and you'll see the graph)

Asus Zenbook Flip 14"

Asus Zenbook 14x

So, what's stopping phone manifacturers to pick up? I don't really know, I wish we'd get a proper reason other than the usual "OLED's cannot be PWM dimmed due to issues in form of black crush, color banding etc. on DC dimmed panels"

I pressume this is an issue if someone wants single digit nits of brightness on a OLED, surely not an issue if aiming for 20-60nits. But, modern phones don't seem to care about the lower end of the brightness spectrum, it's all about the upper range (how high it can go!!!)

The Lumia 650, Wiko WIM and S20 FE 5G (DC dimmed till 30%, so ~150nits I assume, which can be a obnoxious brightness setting at night, but only this particular model as the 4G one doesn't seem to incorporate the same panel)

The former two are irrelevant as they're way too old to be useful in any way possible.

So, to answer the question of your topic, yes, they do and almost all modern OLED smartphones (apart from the S20 FE 5G from my knowledge) have PWM dimming at 100% brightness.

It shouldn't be there at 100% brightness, but it sadly is due to (my theory) manifacturers cutting corners in display panel backlight controllers.

I wouldn't rely on those "DC Dimming / Anti-Flicker" modes most manifacturers provide, as it is a hardware issue not a software one (I've yet to read some proper explanation as to what each manifacturer does to "achieve DC dimming" with their software solutions)

So, keep an eye out for notebookcheck reviews for PWM dimming frequency measurements for smartphones, they seem to be the only reliable ones on the current market (RTings does desktop panels only)

Deepdeep

Some pics of 2 phones with OLED displays:

Galaxy Note 8 at max manual brightness.

Galaxy Note 8 at 75% manual brightness.

LG g8x at max manual brightness.

LG g8x at 75% manual brightness.

KM

What you see there on max. brightness (1st picture) is the refresh rate flicker. It won't go away. However, you can see that the black bars are not pitch black. They're just a little darker than the rest of the screen. It means during the flicker the brightness does not go all the way down to "lights off". This is a difference to the PWM you see in the rest of the pictures. The difference may be huge enough to provide noticable relief.

Deepdeep

KM ok, that kinda makes sense to me, but why is it not present on a non-OLED phone eg the LG G7 on which there seems to be no flicker at all at 100% brightness?

KM

It seems the AMOLED technology inherently has that small change in brightness whenever the screen refreshes. I think all AMOLED displays have it - though perhaps in varying intensity.

asus389

I wonder about this also. For example, the iPhones that support HDR say that they have a normal max brightness and a max brightness for watching HDR content. That leads me to believe that the "normal" max brightness isn't 100% bright for the display, thus would still have PWM. That being said, out of all of the iPhones with OLED screens, I seemed to be able to use a 12 Pro and 11 Pro Max at least briefly with less symptoms when set to 100% brightness. Symptoms got worse as I tried to dim the screen so there is probably something to this concept.

Deepdeep

asus389 Yes, and apart from increased max brightness for HDR mode, on a lot of (most?) phones the max brightness in auto brightness mode is greater than in manual mode, so unless there is no pwm at "max manual brightness" there will still be pwm when we set the slider at max. But it still helps to keep the brightness at max coz there the "off" part of the pwm cycle is much shorter than the "on" part which reduces the effect of the flicker on us even if it doesnt eliminate it totally. I think on iPhones you can reduce the white point to reduce the brightness without affecting the pwm after setting the brightness at max?

JTL

qb74 So, what's stopping phone manifacturers to pick up? I don't really know, I wish we'd get a proper reason other than the usual "OLED's cannot be PWM dimmed due to issues in form of black crush, color banding etc. on DC dimmed panels"

Given how Samsung essentially buries their heads in the sand when someone complains about eyestrain and cites the PWM with known tests as a concern and also were involved in an academic study that I believe was a poor excuse for continuing to justify using PWM I'm not hopeful.

KM

qb74 I believe the reason why most AMOLED devices employ PWM is because flaws in the panel would become more visible otherwise. If you ever used a brightness app to dim, by software, an AMOLED smartphone that's operating at 100% brightness (without PWM), chances are you will start to see uneven uniformity below a certain dim level. So instead of having "DC dimming", the companies employ PWM. The image we look at when there's PWM is composed of bright flashes. And each flash by itself, as it is bright enough, does not suffer from the "low brightness uniformity issue". So the final perceived image is both low in brightness and high in quality.

PacificHike

qb74

Interesting info. I have a Galaxy s22 with an amoled and it kills my eyes. So I just assumed all OLED monitors are bad and have pwm and are to be avoided if you have eye strain issues. Plus Notebookcheck always tests OLED laptops and they always test positive for bad PWM on the OLED panels of the laptops and say to avoid it if your sensitive.

But does that not apply to certain OLED monitors?

So is it actually worth trying a pwm free OLED monitor to see if that solves eye strain issues, since they have no backlight and no pwm?

Deepdeep

KM I think "DC dimming" is usually/mainly done via hardware by limiting the current to the display.

KM

It is - on AMOLED devices, the effects are similar because the pixels are composed of small lamps that will have their current lowered either way.

K-Moss

Android has "Extra Dim" now that allows one to keep the screen very bright on the hardware dial while dimming it using "Extra Dim" which has an intensity slider.

With Extra Dim, I believe OLED can be comfortable enough. I am comparing a Moto G and a Moto Edge.

Do people comparing phones tend to use the wireless feature? Because if I take out the SIM the phone has no connectivity unless I use wireless, which I suppose I'll do to test the phones side by side more meaningfully.

K-Moss

K-Moss I tend to think OLED itself is what is causing people to become more sensitive to ALL screens. OLED after a while even in non-sensitive individuals is bound to cause issues in the highly sophisticated eye-brain system. Just isn't right to be flicking off and on the pixels extremely rapidly, and this happens right up to 100% brightness with OLED.

Furthermore, I am told 100% brightness will prematurely damage the OLED screen. OLED screen always degrades and this degradation is increased through higher brightness and less aggressive PWM.

From a health standpoint OLED is inferior. From a picture standpoint, I don't miss OLED when I am using IPS.

EDIT: further on what I was saying in the first sentence:

" I used a VA monitor for 8 years. I never had any problems. I played up to 6 hours a day. I recently replaced it with an LG c4 42". The first few days I had a headache and eye pain. I used it for a few weeks. Then I changed it back to my old monitor. But the eye pain didn't go away. I feel like the OLED ruined my eyes. I was at an ophthalmologist, I use artificial tears, but my eyes still burn in front of the screen......"

Another: "man my msi destroyed my eyes i cant say how terrible it was. I first thought i get crazy but no, it was the monitor. My eyes was complete red every day. Its a crime to say one world about eye comfort and qd oled in a sentance. Just marketing bullshit"

However, here's a positive anecdote:

"I was coming from an IPS monitor and switched to QD-OLED. First week I definitely was getting eye strain and that feeling of when you take off your glasses and your eyes need to adjust. But like most of everything else in life, I just got used to it after a little while. No issues at all now. Might be helping that I'm using biased lighting and glasses with a blue light filter."

But we tend to read more anecdotes like this:

"i have one qled and one ips. i wound not recommend a qled to my worst enemy that thing will destroy your eyes. with my alienware ips i can game for hourss and I cant play for more than 1 hour with my qled."

And:

"This was the reason why I returned the AW3225QF - I just cannot do QD-OLED. I found it so fatiguing on my eyes with not even 5-10 minutes of use. Makes you wonder how much damage it is doing to peoples' eyes."