Notebookcheck

iPhone 12 Pro: Pulse Width Modulation for the OLED Display

iPhone 12 Pro OLED flicker
iPhone 12 Pro OLED flicker
Straight from our test lab: just like all OLED displays the iPhone 12 Pro’s will also be utilizing Pulse Width Modulation for brightness regulation. We took a closer look at it and would like to present you with our findings.
Daniel Schmidt, 👁 Daniel Schmidt (translated by Finn D. Boerne), 🇩🇪 🇫🇷 ...

The basis for Apple’s Super Retina XDR displays are OLED panels made by Samsung, most likely based on their current generation Dynamic AMOLED technology. At least that’s what the technical specifications suggest.

At 6.1-inches the iPhone 12 Pro’s display is slightly larger than the iPhone 11 Pro's. In order to maintain the same high pixel density, the resolution was increased to 2532 x 1170 pixels. In addition to displaying HDR content the display also supports Dolby Vision.

Just like all OLED panels this one, too, suffers from OLED flickering that is often equated with Pulse Width Modulation flickering but not quite the same. Both, however, have the same result: they may lead to headaches.

When reviewed the iPhone 12 Pro showed differing amplitude response levels depending on display brightness. At minimum brightness, we measured a frequency of between 117.9 and 245.1 Hz. Between minimum brightness and 21 % the frequency remained fairly consistent at 223 to 250 Hz. Between 22 % and 50 % display brightness we were able to attest a frequency of 60 Hz, and above that it started to fluctuate wildly between 80 and 277.8 Hz.

The fairly consistent amplitude response between 21 % should in theory make for less strain on the eye of the user. Combined with True Tone, which shifts colors towards the warm end of the color spectrum, the eyes should be confronted with less strain. Above 22 % the iPhone goes into 60 Hz mode, a method also commonly used for DC dimming. This maximum brightness achieved in this mode is around 150 nits, which means it will be most commonly used indoors. Brightness then increases significantly, and amplitude response becomes somewhat irregular. Given that the amount of ambient light will be fairly high in these cases the strain on the eyes of the user should be fairly low as well if the ambient light sensor is used to regulate display brightness.

Apple does not refer to this as DC dimming but rather uses a very complex finely tuned display controller to reduce the effects of PWM as much as possible. However, some strain may still occur, and we cannot ultimately say that it will be completely and 100 % perfect.

Minimum panel brightness flicker (117.9 - 245.1 Hz)
Minimum panel brightness flicker (117.9 - 245.1 Hz)
21 % panel brightness flicker (223 - 250 Hz)
21 % panel brightness flicker (223 - 250 Hz)
More than 21 % panel brightness flicker (60 Hz)
More than 21 % panel brightness flicker (60 Hz)
More than 50 % panel brightness flicker (80 - 277.8 Hz)
More than 50 % panel brightness flicker (80 - 277.8 Hz)
Read all 5 comments / answer
static version load dynamic
Loading Comments
Comment on this article
Please share our article, every link counts!
> Notebook / Laptop Reviews and News > Reviews > iPhone 12 Pro: Pulse Width Modulation for the OLED Display
Daniel Schmidt, 2020-11-18 (Update: 2020-11-18)
Daniel Schmidt
Editor of the original article: Daniel Schmidt - Managing Editor Mobile - @Tellheim
Already as a little dwarf I was fascinated by my Commodore 16 and ignited my enthusiasm for computers. With my first modem I surfed the Btx and later also the World Wide Web. The latest technology trends have always fascinated me and this is especially true for mobile devices like smartphones and tablets. For Notebookcheck, I have been on the ball since 2013 and I am looking forward to the innovations that are still to come and that we will put to the acid test for you.