YHK - yet another hacker news clone

Seriously cannot believe the PWM frequency is 240Hz. I was shocked out of my mind when I first saw that. It needs to be on the order of kHz to avoid eyestrain for a very significant proportion of the population. Did Apple just forget about accessibility, or did they underestimate it?

I'd be fascinated to see how common this really is. Is it something that affects .0001% of users, more, less? At Apple scale an issue like that could hit millions of people. Given the newness and expense of the product one would assume not that many OLED Macbook Pros have shipped. So it's surprising that this issue didn't come up in testing if we're talking about more than a handful of people.

I'd love for more research to be made into PWM sensitivity, if only to find out roughly how many people experience problems with it.

I've never had issues with it other than when trying to film certain old displays, but then again, I've never had issues with PAL TV sets running at 50 hz interlaced, nor even old PC CRTs running at 60, which definitely was not 'flicker-free', so I'm probably on the far end of the spectrum compared to the PWM sensitive.

It's an easy thing to forget, as with many accessibility features. And it's going to suck to have the nominally best display be one you just can't use if want to not feel like gouging your eyes out.

> But some people are particularly sensitive to this kind of modulation and can experience eye strain, headaches and other forms of discomfort when looking at displays that use it.

So that tiny fraction of users would be well served with some other display and can either return their MacBook or use an external monitor if and when they find out that they're in that cohort.

I am shocked that Apple would release a screen with such a low PWM frequency. Here is a paper showing humans can perceive flicker at frequencies more than double their display’s rate: https://www.nature.com/articles/srep07861

In my experience, Apple hardware always gets better over time. So, you should never buy the first hardware "innovation" changes that they do.

If it’s as low as 240hz, anyone will see a stop motion effect by waving an open hand in front of the screen at 50% brightness.

I’m curious if this is a harmonic mode for a high speed PWM where pulses are either not even widths or the driver loses some power at the 240hz cycle. May perceive similarly.

I have a couple windows laptop workstations with high dpi OLEDs (one with 240hz refresh rate) that I love and don’t perceive this so I’ll have to check.

I am not particularly sensitive, but switching the ipad pro for the oled model, I just don’t like the screen that much, and it is hard to put the finger on why. Side by side, the screen has better blacks and peak brightness and I am sure it beats the LCD empirically on many metrics. But I don’t like the colors as much, and perhaps subconsciously, the flicker is turning me off.

240hz is insanely low.

If you want to use PWM in an application like this you need to start at like 600hz. This is how fast the subfield drive on a plasma TV is.

I have to use incandescent lightbulbs for certain fixtures because I sometimes need a break from engineers who think they are smarter than me.

You're looking at it wrong.

I was expecting to read this and learn that the display was reasonably engineered and that there is some small subset of people who have extreme PWM sensitivity who have problems. But no, Apple modulates at 240Hz, according to plenty of articles.

We’re no longer in the dark ages of flicker. There’s actual industry guidance: IEEE 1789. And 240Hz, at any respectable depth of modulation, does not meet the low-risk limit, let alone the no-observable-effect limit.

I am wondering whether this is actually just an amazing firmware goof: the reports seem to suggest that operating at full brightness mitigates the problem, which makes little sense for an OLED display. An OLED showing 50% (post-gamma) gray ought to drive the pixels the same way as an OLED at 50% brightness showing white. And this display supports HDR, so even 100% brightness white isn’t really 100%.

I’m wondering if a little engineering mistake snuck in: some (most?) LCD displays dim by PWM-dimming the backlight, and plenty of backlights have current-to-light transfer functions that inherently low-pass filter the light. If someone naively ported the same logic to an OLED (which doesn’t have a backlight), they might have implemented brightness controls by applying a 240Hz envelope to the pixel excitation waveform. This makes no sense at all as an actual implementation, but I can totally see an AI doing it and writing tests to validate it :)

Even if there is a genuine engineering factor that requires low frequency PWM, I bet Apple could mostly mitigate the problem by deliberately mismatching the phases. For decades, pre-LED stadium lights had rather extreme flicker at 120Hz, but it was tolerable because the overall system was engineered to roughly evenly split the lights between three electrical phases, giving an effective modulation depth near zero.

I haven’t seen one of these displays myself. I find 120Hz flicker to be extremely obvious and very very unpleasant, and if these displays really do modulate in a nasty way at 240Hz, I expect I’ll be able to see it, albeit rather less obviously than at 120Hz. Also, pretty much any modern phone can see this in slo-mo video mode :)

This is one of the worst articles in terms of information per word density! Too many words and so much beating around the bush before it even discusses what the heck it's talking about.

When I actually went to the source for the 240hz claim, I didn’t reach the same conclusion as the testers?

Maybe they just let their rigol scope spit out 240hz, but 480hz worst case and I would actually say 960hz. I think what’s happening with the tandem oled is they both pwm at 480hz and 180 degrees out of phase giving effective 960hz when both are in use. Which appears to be most of the usable brightness.

Edit: I’m so confused.

“The PWM behavior is interesting, because we can see DC-dimming for all brightness levels. Usually, OLED panels use DC-Dimming only at higher brightness levels. The frequency is very low at 240 Hz, however, and this might be an issue for sensitive users, despite the DC-dimming. ” https://www.notebookcheck.net/Amazing-OLED-panel-Apple-MacBo...

As someone who’s had a concussion, this is really interesting. For me this is how any screen was to me, not just bright OLED ones. Even more interestingly it’s essentially only screens— backlist posters at the mall (paper with a backlight) still affect it but less so. To me perhaps it’s focusing on something on a screen that does this, but it’s really interesting to see this affect the general population.

It’s also odd to think about lack of ability to concentrate, and I wonder if screens cause this optically somehow but to a less noticeable degree even when less intense than this new one? (Independent distracting contents)

I noticed that adding a severe red filter to all my screens helped me significantly with the concussion and am also curious about that, would that impact the intensity of a refresh perhaps? Is blue light specifically the problem? I’m unsure but have a plethora of subjective experience.

I’m glad for this to enter public consciousness a bit and would love to see more research on the screen itself impacting our brain.

This is bad.

I had to return the Steam Deck OLED and LCD because their displays PWM was burning my eyes out. Sore eyes for days, having problems to focus properly. I hope this is a learning process and it will get better from the manufacturer side. But I hoped that after my personal Steam Deck fiasco as well.