Nice analysis.
The C1 doesnt use an evo panel
The C1 doesnt use an evo panel
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(Lack of) Burn-in on Evo WOLEDs
The last burn-in test Rtings performed was in 2017 and LG has made major strides in bottom-emission pixel aspect ratio (PAR) since then.
I took the subpixel images Rtings provided of 55C7 and 55C1 and overlayed the 55C1 subpixels on top of the 55C7 subpixels at equal pixel size (yellow rectangle) to show how much LGD has increased the red subpixel size since 2017:
![Colorfulness Rectangle Font Pattern Tints and shades]()
The small light blue rectangle was layed-out to be ~1/4 of the 55C7 red subpixel size and when overlayed on the 55C1 red subpixel, it's pretty clear that the 55C1 has a red subpixel which is at least ~175% the size of the 55C7 red subpixel (~7 rectangles versus ~4).
For equal lumens of red output, 175% the area translates to current density which is only 57% that of the red subpixel in the C7.
OLED aging rate is proportional to current density to the power of 1.55, or conversely, OLED lifetime or time-to-burn-in in inversely proportional to the same factor.
So 55C1 red lifetime should be roughly equivalent to 55C7 red lifetime / 0.57^1.55 = 1/ 0.42 = 2.38 at equal output levels.
The 2017 Rtings burn-in test showed first signs of burn-in from CNN after 20 weeks or ~3000 hours of CNN at max output levels of 380 cd/m2 (OLED Light 100) or after 28 weeks or ~4000 hours of CNN at 200 cd/m2.
So without accounting for any of the other burn-in protections that LG has added and improved since 2017 (such as static logo dimming), the intrinsic burn-in immunity of the 2021 Evo panel from an extended torture test like continuous CNN watching should now be extended to at least 6500 hours @ 380 cd/m2 or 9500 hours at 200 cd/m2...
The subpixel comparison also indicates other changes since 2017 such as a white subpixel which appears at least 50% larger on the 55C1 versus the 55C7 and that should ultimately translate to higher peak white output levels, but the primary aspect I wanted to focus on in this thread is the improved burn-in immunity (and especially the improved red burn-in immunity) from the 2021 subpixel layout...
I took the subpixel images Rtings provided of 55C7 and 55C1 and overlayed the 55C1 subpixels on top of the 55C7 subpixels at equal pixel size (yellow rectangle) to show how much LGD has increased the red subpixel size since 2017:
The small light blue rectangle was layed-out to be ~1/4 of the 55C7 red subpixel size and when overlayed on the 55C1 red subpixel, it's pretty clear that the 55C1 has a red subpixel which is at least ~175% the size of the 55C7 red subpixel (~7 rectangles versus ~4).
For equal lumens of red output, 175% the area translates to current density which is only 57% that of the red subpixel in the C7.
OLED aging rate is proportional to current density to the power of 1.55, or conversely, OLED lifetime or time-to-burn-in in inversely proportional to the same factor.
So 55C1 red lifetime should be roughly equivalent to 55C7 red lifetime / 0.57^1.55 = 1/ 0.42 = 2.38 at equal output levels.
The 2017 Rtings burn-in test showed first signs of burn-in from CNN after 20 weeks or ~3000 hours of CNN at max output levels of 380 cd/m2 (OLED Light 100) or after 28 weeks or ~4000 hours of CNN at 200 cd/m2.
So without accounting for any of the other burn-in protections that LG has added and improved since 2017 (such as static logo dimming), the intrinsic burn-in immunity of the 2021 Evo panel from an extended torture test like continuous CNN watching should now be extended to at least 6500 hours @ 380 cd/m2 or 9500 hours at 200 cd/m2...
The subpixel comparison also indicates other changes since 2017 such as a white subpixel which appears at least 50% larger on the 55C1 versus the 55C7 and that should ultimately translate to higher peak white output levels, but the primary aspect I wanted to focus on in this thread is the improved burn-in immunity (and especially the improved red burn-in immunity) from the 2021 subpixel layout...
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LGD started planning the transition to the new 3S4C / WBE WOLED stack before 2019 and the 2019 subpixel design was designed to support both 3S3C / WBC and 3S4C / WBE stacks (compatibility mode).
First 3S4C / WBE panels were quietly introduced in 2020 (without any Evo hoopla) and LGD has stuck with the same subpixel design for three generations now (and I expect them to stick with it until WBC panels cease production).
I was expecting conversion of Paju to WBE to be completed this year so that LGD would have the freedom to introduce WBE-optimized subpixels for all panel sizes in 2022, but they have now announced that Paju conversion from WBC to WBE won’t be completed until ‘early next year’ so it’s possible we’ll be stuck with these same compatibility-mode subpixels until 2023…
The new WBE stack has actually had very little impact on color gamut (despite LGD’s claims). The only way to know for certain which panel type is in a C1-Series WOLED is to characterize the spectral power distribution (SPD) of the panel. HDTVTEST does a good job describing that if you are interested so I will. It repeat it here. You can check the C1/G1 Owner’s Thread to find many examples of C1 owners who have measured their SPDs to confirm that they have the new 3S4C / WBE / Evo-capable panels in their C1s (even if those G1-like Evo-capable panels have been locked to C1-mode / non-Evo capability.
We don’t know for certain whether the 55C1 Rtings reviewed was a WBC or a WBE panel (since they provided no SPD) and it’s actually immaterial to the points being made in this thread: the increased burni-in protection since 2017 is driven by the increased red subpixel size (regardless of which stack is in the panel).
Look more closely: C1 was a review of a 55C1 while G1 was a review of a 65G1.
So yes, different panel sizes = different pixels = different subpixels.
Here is a picture of subpixels from an 83” panel (only manufactured in 3S4C / WBE so no need for comparability mode also supporting 3S3C / WBC:
Notice how small the blue subpixel is and compare to any Rtings picture you can find. The WBE / Evo-capable stack reinforces blue strength by ~20% which means the blue subpixel can be reduced in size by as much as 20% for the same level of burn-in-immunity.
Subpixels supporting either WBC or WBE need a large-enough blue subpixel to support the panel with the weaker blue (WBC) while subpixels optimized to support only 3S4C / WBE / Evo-capable WOLED can take some of that larger-than-necessary blue subpixel and shift if to red and/or white.
The 83” subpixel design is the only size which appears to have been optimized for the new 3S4C / WBE / Evo-capable WOLED stack…
Correct, any non-random correlated content (such as faces tending to be centered on the screen) will accelerate burn-in.
Such correlation is most extreme for logos or tickers, but also pretty extreme for news stations in general, where reporters and newscasters tend to be centered on the screen far, far more frequently than when watching movies.
You can see the central CNN ‘ghost’ is pretty much fully-formed (burned-in) after 14,280 hours at 380 cd/m2 (CNN Max):
(and 2-3 gang members have even started burning in to the sides behind him
).That image is after 102 weeks or 14,280 hours of CNN_Max @ OLED Light = 100.
This is the corresponding image after 14,280 hours of CNN @ 200 cd/m2:
And in terms of first evidence of the CNN ghost starting to appear @ 200 cd/m2, here is how it looks after 4760 hours (still pretty clean):
So if we want to say the C7 delivered 5000 hours of torture-test non-random centralized newscaster / reporter viewing before first signs of burn-in, the same 2.38 minimum improvement factor due to C1 red suboixel which is 75% larger should translate to at least 12,000 hours of CNN @ 200 cd/m2 before the ghost starts to appear…
Whocan say how to ctrapolate from a torture test like continuous CNN to random movies, but I would guesa that a minimum of a factor of 5X if not 10X sounds very reasonable / realistic.
60,000 to 120,000 hours before I need to worry about green blobs appearing in the center of my WOLED when viewing faces? I think I’m good…
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