OLED provides far better contrast than LCD—but unless Apple improves its OLED dimming technology, this will not be a beneficial change for those very sensitive to OLED flicker.
OLEDs can be dimmed with analog dimming (aka constant current reduction), in which the OLED's simply emit less light. But analog dimming's downsides include color shifts as the screen is dimmed, larger circuitry, and higher power consumption. Thus OLED screens are instead usually dimmed
digitally by keeping the OLED's brightness constant (when they're on), and rapidly switching them on and off. This is called pulse width modulation (PWM). The idea is that if you want, say, 50% brightness, you rapidly switch the OLEDs on and off so that they illuminate the screen only 50% of the time.
The problem with PWM is that the frequency at which OLEDs can do this is not that high (often just a few hundred Hz, though it can go higher), and some can perceive this flickering and get headaches from it. The flicker becomes especially noticeable when the display is significantly dimmed. E.g., at 10% brightness, the display would have a duty cycle of 10% on and 90% off. That's why people using OLED devices at night are more likely to get eyestrain.
It would be nice if Apple gave consideration to this in making its MacBook Pro OLED screens, and either implemented an improved analog dimmer, or chose an OLED technology with an extremely high PWM frequency. For instance, according to
https://www.notebookcheck.net/PWM-R...del=1&screen_resolution=1&screen_panel_type=1 , OLED variants are available with PWM frequencies > 800 Hz (833 Hz for the AMOLED Lenovo Legion Phone Duel). According to
https://www.xda-developers.com/apple-iphone-14-pro-max-display-review/ , Apple's implementation of PWM in Apple's iPhone 14 is complicated, with two different PWM frequencies (240 Hz and 480 Hz)*. [Unfortunately, the article doesn't fully explain how that works.] 480 Hz is towards the upper end of the range, but higher would be better.
The LED's used to backlight LCD screens also use PWM dimming. The difference is that their PWM frequency is much higher, which makes flicker far less noticeable (and typically imperceptible, even for sensitive viewers). For instance, according to the above link, the PWM frequency for the 14" & 16" M1 MacBook Pro LCD screens is 14,880 Hz.
See also:
All screens flicker to some degree, but what causes it on smartphones in particular, and how does DXOMARK test for it?
www.dxomark.com
Some iPhone and iPad users are sensitive to PWM flickering on the latest devices OLED displays. PWM, which stands for Pulse Width Modulation, can cause some users to have eye strain, feel nauseous …
osxdaily.com
*Correction: I had previously quoted a 60 Hz PWM frequency for the iPhone 14 from the notebookcheck table but, based on the more detailed analysis from xda-developers, that appears to be incorrect.
