Originally Posted by stama
A few notes on VRR.
Some expressed their wishes for LG to bring VRR capability to 2018 series sets. That is not possible, according to an interview
the guys at Les Numeriques had with the LG Electronics VP of Marketing and Communications and the Director of the TV division last year. The reason was not that LG Electronics is not able to, after all they are making FreeSync monitor displays. The problem lies in the Tcon (Timing Controller) of the OLED panel that LG Display manufactures, and which is not able to drive the panel with a variable refresh rate. (LG Electronics - the TV manufacturer, is not the same entity as LG Display - the panel manufacturer)
The Tcon chips (there can be more than one on the Tcon board) are responsible for driving the components that turn on and off the individual pixels on the panel. When you buy a panel, you get the panel and its custom Tcon board attached to it.
That's why no TV manufacturer that used LG OLED panels was able to offer VRR as a feature on their 2018 sets, the panel electronics simply did not allow to be driven that way. And that's why VRR can not be enabled on 2018 sets by a software upgrade, as it's a hardware limitation.
Which means, that now we know LG Display did bring at least one change to their panels this year, the Tcon and the panel drivers must have been changed to be able to drive the pixels with variable refresh rates. And maybe that required some changes to the sandwich structure of the OLED panel itself.
And this also means that VRR will likely be present not only on LG OLED TVs this year, but also on the sets of some other TV manufacturers using the LG OLED panel.
I believe that LG has had split-column refresh since they first introduced 120Hz 4K panels, but they have always been 'hard-coded' at the panel level to do full-frame refresh.
From their first forray into dlivering BFI last year (and all the limitation that suffered from), it finally occurred to LG that by seperatong control of the two half-columns so that new puxel data could be written into a row of one half while pixel data could be reset to black within a row of the other half, they would have an easy and effective way to deliver an effective refresh rate of 240Hz which would allow much better implementation of BFI.
That change, allowing seperate write and reset operations into both halves of the array in parallel, would require a change to the TCON controllers (as you've said).
So the underlying pixel design (and array design) of the WOLED panels may very well be dentical to 2018 (we'll need to await close-up pics of subpixels to determine whether they have further refined relative subpixel sizes or not), the WOLED stack itself has probably not changed (this is what LGD usually refers to when they talk about changes to the panel), but the control signals have almost certainly changed (meaning you could not retrofit a 2019 panel into a 2018 WOLED TV).
It would make total sense that those new TCONs needd to support the split-column 240Hz effective refresh rate are also where the support for VRR would be located.
In terms of LGDs lingo, the 2019 panel and 2018 panels are identical except for the modified antireflective coating. That means that, except for the impact of that new coating, peak brightness, aging/burn-in rate, color gamut, etc... should all be the same.
2020, when LG will hopefully have moved to top-emission, is when we should next expect major changes to the WOLED panel itself. At a minimum, we're going to see significant increases in lifetime (and time to burn-in), we'll hopefully also see increases in peak brightness, it's a good opportunity for LG to deploy changes LG has teed-up to the WOLED stack itself (TADF?) and since top-emission dictates changes to the IGZO backplane, I'm now predicting we'll see a doubling of backplane speed in 2020,
On 8K panels, doubling of the IGZO backplane will mean that the existing split-column architecture will support 120Hz refresh (identical to the 2019 4K WOLEDS). On 4K panels, it is more likely to mean going back from a split-column refresh to a single-column refresh (which will cut the number of TCONs for 4K TVs in half and reduce cost).