Do allow me to clarify on a few things with the above.
As based on the replies, it really does suggest that at least 1/3 of what I have attempt to bring up might not have been read. Hence there were even more speculation and confusion caused as a result.
Thus I will reiterate again. with a few technical terms used in this attempt.
One can only say a panels
uses PWM as a dimming
method provided that
Duty Cycle (independent variable) has been directly manipulated . As directly manipulating the Duty Cycle results in the intensity of the
Pulses (dependent variable).
Hence the name :
Pulse. Width. Modulation. (aka method)
Any change in duty cycle
that is not a result of directly manipulation is not called PWM as a dimming method anymore. The change in modulation is caused by hybrid PWM/DC dimming.
This is where instead of duty cycle been directly manipulated, DC Dimming is been used as a subsitute. This is called Hybrid dimming. This is what Apple is using with their recent iphones when brightness is between 100% to 25%. Thus modulation is also changed since DC dimming did not replace the modulation depth caused from the PWM's.
To reitierate again, because hybrid dimming is now been used, we cannot say it uses PWM as dimming method anymore.
However, saying that a panel
has PWM is a completely different thing. It means PWM exist but duty cycle is not been manipulated. For instance, a panel can have a low flicker frequency of 200 hertz, duty cycle of 50% with a modulation of 100%. This is when between brightness level is between 99% to 0%. This is actually pretty brutal to any individual that is sensitive.
As duty cycle remains locked at duty cycle 50%, we say that it
has PWM, and uses DC dimming to regulate the brightness level.
This is also a good example of
Hybrid dimming. and is also called
PWM 0, PWM free ~ since duty cycle remained unchanged even till brightness 0, and
no change duty cycle percent has been directly manipulated.
As for the 100% brightness, it does not really matter whenever if 100% meant 100%. That is not the point I am attempting to bring. 100% could be 1500nits which is the value accessible to us, while 2000nits might be the actual max brightness value. That is not the point I am attempting to bring.
What I am attempting to bring is that when the screen is at its default brightness level — when PWM has not even began its transition, should flickering exist despite the lack of any direct duty cycle manipulation, it is called
temporal light modulation. Not PWM. One can also say hybrid dimming causes direct changes in the modulation depth, since PWM is part of this mixed hybrid (PWM/ Dc dimming) dimming after all.
Over at the PWM sub reddit, we continue to use PWM in our analysis because it is what most familiar to us in the community. Furthermore, a number of us probably knew that hybrid dimming still contains a small percentage of PWM afterall.
As to the PWM free which results in a flat ampulitude, which I attempted to bring up in this post, last image carousel:
I am referring to PWM not showing up in an amplitude graph, and not to say of any hint that PWM is even being used, such as hybrid dimming.
For instance, in a post I have wrote some time ago.
My only go to iPhone 7 plus with a replaced in-cell LCD panel was using
ultra high frequency hybrid dimming, with a flicker hertz of well over 200,000 hertz, and a modulation depth of 25% while brightness level below 25%. As "Ultra high frequency hybrid dimming" still contains a percentage of PWM afterall.
Had I used a Radex Lupin to do the measurement on my only go iPhone 7 plus with replaced in-cell LCD, I would have immediately discriminated it on the basis that it has such ridiculously high modulation depth.
That said, I have another iphone 8 plus which also has a replaced in-cell LCD but from another supplier. While that panel is also using ultra high frequency hybrid dimming , it has incredibly
heavy ripples, which has given me mild tension headaches.
Next on the future of OLED in panels, I predict that the same implementation of using
high frequency hybrid dimming is a fantastic workaround to address the limited of LED panels. However, I do not foresee LEDs using
ultra high frequency hybrid dimming like my iphone 7 plus's replaced LCD panel, since that is essentially a carbon copy of a true dc dimming panel, which is flicker free. Perhaps through continued technology advancement, high frequency hybrid dimming can be used with low modulation, to which resulting in the same flicker-free experience.
Moving on to how Apple's respond to PWM in this regard, allow me give an analogy to further show why their attempted remedy is still ineffective, hence we are unable to appreciate the effort made by them.
Imagine this analogy. We complained of heavy weightload that Apple's iPhone has made us carry on our right dominant hand (assuming that we are all right handers, and whether are we really right or left handers is not the point of this discussion). This right dominat hand of us is PWM. So Apple responded by marginally removing of some the weightload, and moved the heavy weightload from the right dominat hand to our non dominat left hand.
This non dominat left hand would be Temporal Light Modulation. Now the stress is no longer on the right dominat hand(PWM), but the weaker non-dominat hand(TLM).
Additionally, as a result of this implementation, when brightness level hit below 20%, the heavy weightload returns back to the right dominat hand(PWM), with the weightload being even heavier than before (because of this implementation).
To which Apple might have responded with : "There! All fixed now. That ought to do the trick ~ The heavy weightload is no longer on your right hand, like you wanted."
To address this, Temporal Light Modulation's modulation depth % must be significantly lower, before any of the hybrid dimming methods is applied.
I hope the above clarifies.
This will be my last post here btw as my objective here is to act as a "bridge" between the end users(that is also me that was affected) and the engineers who have worked on this (based on my field which is studying and analysing them). As based on reading the past posts accumulated here over till now, it seems very likely that the end users is perceiving PWM as one thing, while the engineers are completely perceiving as PWM another. There seem to be a complete mismatch in how things are percieved.
To get manufacturers to understand our problems, we have to speak their language jargon and by their definition, and not based only on our definition within our community we have been well accustomed to.
However, considering that my earlier attempt was somewhat met with resistance, I will quietly take my leave from here forth.
I really do appreciate the meaningful discussion, and the attentive given to me thus far.
🙂
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