well, you’re right.
but what about the competitors using oled? do they have this also? I think only lcd needs strobing in order to work for vr
As I just told you, all OLED displays employ PWM (slight simplification, but the black and white that don’t still scan so the strobing is there all the same). The big VR headset manufacturers chose OLED displays specifically because they could run fast, producing short (low persistence) and frequent (high frame rate) strobes. LCDs modulate a distinct light source, so low persistence LCDs simply need to synchronize short strong strobes to achieve low persistence (the Pimax 4K used a second layer of shutters instead, as the backlight wasn’t divided and they wanted separate strobes for the left and right eye). Several other technologies such as LCoS and DLP natively use low persistence strobes as well, but in addition use different colours at different times, leading to the infamous “rainbow” effect. Many light sources flicker as well, particularly non-HF fluorescents that may flash at 120Hz or as low as 50Hz, depending on construction and region.
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so that means that that vr will always show some sort of strobing/pwm and will result being more prone to eye fatigue than standard monitors with no pwm. right?
how do you know all that stuff?
As I understand, PWM doesn’t create eye fatigue. Now I could be wrong about this, but as I understand PWM does just the opposite. Take a look at the Pimax 4K VR system for example. Some members actually took their HMD apart and removed the shutters in their system in an attempt to make the 4K brighter. Some of those members have now reported that even though this process did in fact make the system MUCH brighter, it also created eye fatigue. Keep in mind, PWM is used to adjust brightness in LCD’s… If PWM was a mainstream issue effecting a large portion of the population, LCD TV’s and LCD computer monitors would have never been popular because they too use PWM.
Not necessarily always (again, see the extreme frame rate demos), but certainly the next few generations. But it’s a lot more complex than strobing=flickering=headache. It’s not generally your eyes reacting but your brain; in principle your brain receives distinct pulses from cells in your eye, saying that some point has exceeded a level of brightness, possibly compared to its neighbour. Interweaving blackness like low persistence displays do (including cinema projectors) increase the chances of such signals, as the eye keeps comparing to a lower overall level. The main source of fatigue regarding displays hasn’t been the strobes, but rather dust, because CRTs would charge electrically and incidentally drive some airborne dust at your face. There are other concerns such as how current VR systems use flat focus distance, regardless of vergence (also work in progress, see light field displays). Many of the things that do use PWM do so at much higher frequencies than the display rate, and that too reduces issues (the cinema example here is classically 24Hz frame rate but three times the strobe rate at 72Hz).
As for how I know, it’s mostly a matter of paying attention due to interest, and actually thinking about the things I read about. One rule of thumb is that alarmist articles trying to scare you are thin on information and try to control your thoughts; those are not good reasons to trust. Do listen to your own senses; you’ll find there are always little signs, and it is important to learn that most are transient and not actual threats. One thing I find fun to do is watch one of those scrolling LED signs and hum a bit; it goes all wavy from the beat frequency of your hum shifting your eyes and the sign’s strobing. Also glancing through your periphery makes it much easier to notice flickering, particularly if your central vision sees steady light.
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