General > General Technical Chat
Why do backlight LEDs burn out and go blue?
james_s:
It's the contrast ratios and black levels that really sold me on OLED, they look absolutely stunning in a darkened room, and the color is also amazingly good. LCD looks washed out and bland in comparison. I think it's unfortunate that so many people don't care about picture quality and that has kept LCD going when it should have been largely obsolete by now.
I don't watch TV in a traditional sense, I use my TV for movies and streaming older shows and it is only on when I'm actively sitting there watching something so the potential for screen burn is not really an issue, and picture quality is very important to me. I have an LCD TV only because I got it for free, it's not nearly as nice as the OLED sets a couple of my friends have but it's good enough for the price.
Zero999:
--- Quote from: macboy on November 12, 2021, 04:45:40 pm ---
--- Quote from: bdunham7 on November 11, 2021, 06:08:37 pm ---
--- Quote from: wraper on November 11, 2021, 05:59:06 pm ---If he had manually ran compensation cycle, most likely those issues would be gone.
--- End quote ---
I've seen no success with screen-burn reduction apps in other devices--is there something special about the compensation cycle in an LG OLED? Does it know somehow which pixels are weak? Does it store calibration data?
--- End quote ---
Yes, it is special.
LG engineers determined that the forward voltage of the individual OLED pixels changes predictably with wear. So if you can measure the forward voltage, you know the state of that pixel and compensate. The modern OLED TV panels are engineered with a substantial headroom in maximum brightness output. As the each pixel ages, the TV applies compensation to boost the output to match original specifications. Eventually of course, it will run out of headroom and won't be able to boost some pixels any further, at which time light output will decrease and burn in will begin to show up. I've read they expect this will occur after approximately 100000 hours, or around 10 hours a day for 30 years. This technology has improved over the years (and didn't exist at first) so don't be surprised to hear of burn-in issues from people with old OLED panels. It's highly likely that modern OLED TVs (just like LCDs) will be replaced due to technological obsolescence or some non-panel fault far before the panel is worn out.
Even if my OLED TV only lasts 5 years, I will get another OLED to replace it. There is no other tech on the market that comes anywhere close to the picture quality. The picture uniformity is perfect; in fact, I now find it almost painful to watch any LCD TV due to the subtle non-uniformity (blotches, brighter edges, etc.) that most people don't even notice because it's so "normal"/common. The black levels and shadow detail of OLED are amazing. The best zone-lit LCDs have narrowed the gap but don't and can't match the performance.
--- End quote ---
Wouldn't it have been much easier to allocate an area of memory to store how long each pixel is illuminated for and at what brightness? Then the wear can be calculated and compensated for.
james_s:
--- Quote from: Zero999 on November 12, 2021, 09:50:11 pm ---Wouldn't it have been much easier to allocate an area of memory to store how long each pixel is illuminated for and at what brightness? Then the wear can be calculated and compensated for.
--- End quote ---
That would rely on the wear being absolutely predictable, which it may not be. If you can measure the actual condition of the pixel that is likely to produce much better results.
PlainName:
--- Quote ---I don't watch TV in a traditional sense, I use my TV for movies and streaming older shows and it is only on when I'm actively sitting there watching something
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That's got me puzzled. What is the 'traditional sense' for a TV? Are they used instead of, for instance, a radio (I note Freeview over here has a lot of 'FM' channels).
eti:
--- Quote from: dunkemhigh on November 12, 2021, 11:37:30 pm ---
--- Quote ---I don't watch TV in a traditional sense, I use my TV for movies and streaming older shows and it is only on when I'm actively sitting there watching something
--- End quote ---
That's got me puzzled. What is the 'traditional sense' for a TV? Are they used instead of, for instance, a radio (I note Freeview over here has a lot of 'FM' channels).
--- End quote ---
Streaming on demand, and/or YouTube as opposed to watching broadcast tv through the air, or via cable, I should think.
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