iPhone X pulse width modulation?

Discussion in 'iPhone' started by tcellguy, Oct 23, 2017.

  1. tcellguy macrumors member

    Sep 20, 2017
    Does anyone know if the iPhone X is using low frequency pulse width modulation like Samsung OLED phones? Do all OLED displays require pulse width modulation?

    I am one of the few people who are bothered by screens using low-frequency pulse which modulation (PWM). I can see the flicker of the screen refresh from a few of the Samsung OLED displays when moving my eyes across a display, which is associated with headaches and eye strain.

    My understanding is that Apple devices have used either very high kHz PWM, or DC dimming techniques for several years now and I have no problems with any Apple display for extended use > 10 hours.

    From what I've read, it seems that the OLED technology requires steps, including PWM, to avoid burning out the OLED emissive elements. This site suggests that the majority of OLED screens use PWM at 200 Hz:


    The Apple Watch OLED refresh rate seems high enough that it doesn’t bother me, but I can see the refresh rate when using the iPhone slow motion camera. However, I only look at the watch for brief periods of time. Similarly, the MacBook Pro OLED touch bar also seems to be flickering at < 1000 Hz, but I don't look at it that long.

    I haven't seen any gross flickering of the display on any of the videos showing the iPhone X display, but it's hard to tell as I can't slow down the video speed.
  2. Jodiuh macrumors 6502

    Sep 15, 2009
  3. tcellguy, Nov 6, 2017
    Last edited: Nov 6, 2017

    tcellguy thread starter macrumors member

    Sep 20, 2017
    Thanks. That’s what I was afraid of. That graph shows very deep pulse width modulation and they mention the flicker can be seen with the naked eye. I’m not an electrical engineer. Why can’t the frequency be in the kHz range?
  4. Jodiuh macrumors 6502

    Sep 15, 2009
    “there is no visible flicker”

    Not sure about kHz as I’m not an expert either.

    I’ve been using it for a few short minutes right now and I can definitely tell there’s some discomfort in my eyes and even a mild headache.

    I had a 6S Plus before and didn’t think twice about the 8 Plus because I had my sites set on the X because of the “same size screen in smaller body” claim...which I find to be completely untrue. The side to side width is FAR narrower when reading in portrait and I consistently make mistakes while typing or have to enter passwords slower after failing time after time.

    It’s also thicker and about as heavy.

    Going back to the screen again, I find it jarring to look at because of the height vs width ratio. It’s just to damn tall in portrait mode and too damn collapsed height wise and long in landscape mode.

    Also, I’m not sure if it’s the leather case, but I’m getting a very numb pinky holding it in portrait mode. I think it’s becais it fatter and the weight isn’t spread out.

    Overall, I gotta say the biggest draw for me was the screen being as large as Plus and it fails miserably at that. Burn in is a real issue too!

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3 October 23, 2017