OLED TVs: Technology Advancements Thread - Page 369 - AVS Forum
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post #11041 of 11050 Old Yesterday, 02:15 PM
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Darin (good to hear from you) and TGM, good points from both of you. I basically agree across the board.

Fundamentally, my sense is that the white serves a pretty limited function. And I think TGM, you agree here, too. Getting back some lost output more than trying to "save the pixels from themselves".

I doubt very much the long-run plan is to keep using the white for this reason. The design gets a lot simpler over time without it and given that you can lose the corresponding transistors, you probably don't need much improvement in overall light output to justify dropping it (if you're overall goal is a power budget).

Of course, to the extent that driving the material harder has some effect on lifespan, that's also a concern. But it seems probable that, too, will be mitigated over time.

One other random thought. LG uses a color-filter design that is not a million miles removed from their LCD technology because they're exceptionally good at patterning and producing that layer. The OLED makes light really differently from LCDs, however. It might make sense over time to rethink the color-filter layer and/or add a special film in between the light and the CF. Some sort of purpose-built OLED BEF (brightness enhancer) that takes advantage of the way OLED works. It looks like a lot of potential light is lost to the rigid lines of the color filter and/or the electrodes. That seems like an area where long-term improvement is more than a hypothetical.

There is no difference in HDMI cables. If you can see the picture without visible dropouts or sparklies, the cable is working at 100%. No other cable will display a better version of that picture. You're simply wrong if you think there is a better digital cable than one that is already working. (Oh, and plasma didn't die because of logistics problems, nor does OLED ship in big boxes because it comes from Korea.)
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post #11042 of 11050 Old Yesterday, 03:10 PM
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Quote:
Originally Posted by rogo View Post
Darin (good to hear from you) and TGM, good points from both of you. I basically agree across the board.

Fundamentally, my sense is that the white serves a pretty limited function. And I think TGM, you agree here, too. Getting back some lost output more than trying to "save the pixels from themselves".
Hhmm... I guess I'm going to be the odd man out. Increasing light output for colors with a common grey component, but not for colors without a common grey component, does not seem like you could get much benefit without hurting PQ. I would think you would want to normalize all your colors with how bright you could make your primaries. I don't have the experience with displays and color you folks do, I'm just going by inuition, but adding the white pixel to make some colors brighter does not seem likely. I agree if that is why it is there, it probably won't be around long.

On the other hand, if you look at the diagrams TGM made in is last post, there is much less total wear when the grey component is illuminated with the white pixel compared to doing it with the primaries thanks to the clear filter. I have no idea how hard the white would need to be driven to equal the light output of the combined 3 primaries, but using TGM's conceptual diagrams as an example, you can see there is 1/3 the total wear compared to using the primaries. This seems like a good reason to add the white pixel.

As for the terms "common mode" and "grey component", sounds like TGM has much working experience with colors and displays, so if he is used to "grey component" that is what I will use. I liked fafrd's use of common mode because it is a EE term and so I understood immediately what he was saying.

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post #11043 of 11050 Old Yesterday, 03:47 PM
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Quote:
Originally Posted by rogo View Post
Darin (good to hear from you) and TGM, good points from both of you. I basically agree across the board.

Fundamentally, my sense is that the white serves a pretty limited function. And I think TGM, you agree here, too. Getting back some lost output more than trying to "save the pixels from themselves".

I doubt very much the long-run plan is to keep using the white for this reason. The design gets a lot simpler over time without it and given that you can lose the corresponding transistors, you probably don't need much improvement in overall light output to justify dropping it (if you're overall goal is a power budget).

Of course, to the extent that driving the material harder has some effect on lifespan, that's also a concern. But it seems probable that, too, will be mitigated over time.

One other random thought. LG uses a color-filter design that is not a million miles removed from their LCD technology because they're exceptionally good at patterning and producing that layer. The OLED makes light really differently from LCDs, however. It might make sense over time to rethink the color-filter layer and/or add a special film in between the light and the CF. Some sort of purpose-built OLED BEF (brightness enhancer) that takes advantage of the way OLED works. It looks like a lot of potential light is lost to the rigid lines of the color filter and/or the electrodes. That seems like an area where long-term improvement is more than a hypothetical.

I'm just not understanding why you are saying this (in bold above) - do you have some other specific information or are you just commenting on the same examples that have been posted.

Extracting the 'grey component' (or 'common mode' if you are EE like sooke and I) is a pretty important function and leads to significantly less use of the primaries (especially blue).

And since the examples shown never show all three primaries lit up, it's pretty strong evidence that this is exactly how the white sub is used (as pointed out by TGM).

When there is no grey component, the white sub must be off by definition (including the case of any two of the primaries being used all the way up to 100%).

But let's consider the color composed of 100% R + 100% G + 100% B (ie: a white).

Let's assume the color filters are 50% efficient and further that the light output fro the WOLED layer is evenly divided 33% into each primary (as far as the color filters are concerned).

So each of the colored subs is only going to be ~17% efficient and driving the R & G & B primaries at 100% is only going to result in light output which is ~17% of that produced or ~50% of the light output of a single sub.

That means if the white sub pixel is going to be used to drive that same white light output, it only needs to be driven to the 50% level (because none of the primaries are filtered out and there is no color filter to further degrade efficiency.

Both for reduced power consumption as well as increased lifetime, I would think LG would want to make use of the white sub whenever possible and as strongly as possible (meaning to the limit offered by the grey component).

We can debate this ad nauseum, but the easiest thing would be to convince an owner to run color ramps or a color palette and check with a magnifying glass for any examples where all 4 subs are used. My guess is that there are none (with the possible exception of the brightest possible white which would be ~150% of what the white sub could put out all by itself driven to max).

By way of comparison, if LG sacrifices the white sub and increased the size of the other primary subs (to 133% of the current size), max white output would increase from ~50% of the current white sub to ~67%.

To me, a white subpixel makes a heck of a lot more sense than a yellow subpixel (as in Sharp) and I won't be at all surprised to see it hanging around for a long while.

All of this analysis glosses over the impact of the inter-subpixel spacing which would make the 'eliminate the white sub' scenario a bit more favorable (but not enough to change the overall message).
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post #11044 of 11050 Old Yesterday, 05:56 PM
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Well one thing's for sure, I really wish I knew what the LG engineers know. I bet there's quite a bit of "learning the hard way" type information about all of this that would be cool to know.

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post #11045 of 11050 Old Yesterday, 06:12 PM
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Quote:
Originally Posted by Wizziwig View Post
You will see there is never a case where they only use the white sub-pixel, even on gray ramps. Only pure red and blue seem to use a single sub-pixel.
The white subpixel alone is used for dull greens/browns. In my brief time with a 55EA9700 I did some testing. See pics below.
https://dl.dropboxusercontent.com/u/...8/P1010045.JPG
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post #11046 of 11050 Old Yesterday, 07:35 PM
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"Both for reduced power consumption as well as increased lifetime, I would think LG would want to make use of the white sub whenever possible and as strongly as possible (meaning to the limit offered by the grey component)."

This makes no sense to me. If you overdrive and utilize the white subpixel, you just torch that one instead. It's the same exact chemistry as any other subpixel -- they all have the exact same OLED "stuff" in there. If you keep using it "as strongly as possible" you will just kill it off.

You have to always remember the "blue subpixel" isn't blue. It has nothing to do with blue lifetime. It's white. Ditto the red. Ditto the green. You have to balance your use of the white one, or else it just lives fast and dies hard, and again you have an uneven wear problem and you're no longer going to get the expected colors out of the display when you use it.

There is no difference in HDMI cables. If you can see the picture without visible dropouts or sparklies, the cable is working at 100%. No other cable will display a better version of that picture. You're simply wrong if you think there is a better digital cable than one that is already working. (Oh, and plasma didn't die because of logistics problems, nor does OLED ship in big boxes because it comes from Korea.)
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post #11047 of 11050 Old Yesterday, 08:58 PM
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LG slashes 55-inch OLED TV price (In Korea)
http://www.koreatimes.co.kr/www/news...33_165343.html


That's roughly $3784. Still much cheaper here in the U.S.
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post #11048 of 11050 Old Yesterday, 09:34 PM
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Quote:
Originally Posted by fafrd View Post
We can debate this ad nauseum, but the easiest thing would be to convince an owner to run color ramps or a color palette and check with a magnifying glass for any examples where all 4 subs are used. My guess is that there are none (with the possible exception of the brightest possible white which would be ~150% of what the white sub could put out all by itself driven to max).

If there really are no cases where all 4 sub-pixels are lit, doesn't that mean that 1/4 of the panel is off on average?


Looks like we finally have some proof that LG is starting to change the pixel structure a little.

http://www.lesnumeriques.com/tv-tele...re-n36031.html


Quote:
This year, LG reviews the architecture of its Oled tiles. While the 55EA970V and 55EA980V proposed the sub-pixels of equivalent sizes, the 55EC930V has white and blue two times larger than the Green and red.

Also of note, green, blue, and Red sub-pixels now consist of two under cells, but according to what we have seen, the top and bottom are not controlled separately.
First 2 pics are from 2013 (55EA970V and 55EA980V). Third pic is from 2014 (55EC930V).


In the oldest 2013 pic, you actually do see several pixels with all 4 subs enabled.
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post #11049 of 11050 Old Yesterday, 10:04 PM
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Quote:
Originally Posted by Wizziwig View Post
If there really are no cases where all 4 sub-pixels are lit, doesn't that mean that 1/4 of the panel is off on average?
1/4 of the sub-pixels would be off at minimum, so the average would be even more off than that.

However, the first picture you attached has an example of all 4 sub-pixels lit a little above the center of the picture.

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post #11050 of 11050 Old Yesterday, 10:34 PM
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It's very clear there are times when all sub-pixels are very much alive. But those test images show they are rare.

What they don't necessarily show is a lot of very representative content.

There is no difference in HDMI cables. If you can see the picture without visible dropouts or sparklies, the cable is working at 100%. No other cable will display a better version of that picture. You're simply wrong if you think there is a better digital cable than one that is already working. (Oh, and plasma didn't die because of logistics problems, nor does OLED ship in big boxes because it comes from Korea.)
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