In a story last week, CNET broke the news that Panasonic has admitted to problem with rising black levels on some Viera models of their plasma HDTVs. Apparently there have been many consumer complaints about the increase in black level over time on these sets. Black level is important because it is perhaps the key [...]
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HDTV Almanac - Panasonic Plasmas Not So Smart?
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alfredpoor
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dmspen
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Panasonic Plasmas Not So Smrt - but what about others?
My questions?
Why does Panasonic do this with the plasma TVs? Is there a technical reason for it?
Do other TV manufacturers do this also?
What about the panels that were sold to Pioneer for the KURO line? Are these affected?
Can the black level be adjusted or is it a permanent degradation?
Why does Panasonic do this with the plasma TVs? Is there a technical reason for it?
Do other TV manufacturers do this also?
What about the panels that were sold to Pioneer for the KURO line? Are these affected?
Can the black level be adjusted or is it a permanent degradation?
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alfredpoor
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Why do they do it?
Let me start by saying I don't know the technological details on this. What follows is pure conjecture, so take it with a grain of salt, and if someone has better information, please point me to it.
Having said that, I expect that some component ages during the initial use of a plasma set. I expect that uncorrected, the entire image would dim more rapidly. In order to maintain a long useful lifetime for the product, the makers jack up the power to the display over time to keep the light output levels up to par. This presumably would also raise the black level, and risks diminishing contrast performance.
I also expect that other plasma makers may do something similar. I expect that the correction occurs in the controller, and is probably not reversable so you may not be able to get the black levels back to their original levels. (Since so many people are complaining about this, it leads me to expect that the user controls are ineffective at fixing the problem.)
Alfred
Having said that, I expect that some component ages during the initial use of a plasma set. I expect that uncorrected, the entire image would dim more rapidly. In order to maintain a long useful lifetime for the product, the makers jack up the power to the display over time to keep the light output levels up to par. This presumably would also raise the black level, and risks diminishing contrast performance.
I also expect that other plasma makers may do something similar. I expect that the correction occurs in the controller, and is probably not reversable so you may not be able to get the black levels back to their original levels. (Since so many people are complaining about this, it leads me to expect that the user controls are ineffective at fixing the problem.)
Alfred
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Richard
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In the past, as the plasma panel would age, a sparkling artifact would start appearing typically called sparklies and they can be of different colors, white or red is common. There were some adjustments we could make to help that in some cases, in other cases it requires taking the product out of calibration, and in some cases nothing can be done except replace the plasma panel.
This is not something you would notice with plasma signage but in the home with a variety of images... absolutely!
About mid 2000s, 2005, this problem was rectified by providing an aging algorithm as part of the controller, the board that actually runs the panel. Some plasma models we see today for repair have the sparkly problem and we can install an updated controller CBA to resolve that. As far as I know, all plasma going forward from about that time included this algorithm.
I suspect all recent plasma products will develop this black level problem, and I also suspect only the videophiles will notice. That said, I have not heard a peep from ISF calibrators who own one. I'll check into that...
It appears the only way to correct it would be to replace the plasma panel and due to cost that won't be happening.
As a video race car driver, there is a lot to like about plasma and a lot to hate, and it's a damn shame SED withered on the vine and could not compete in the market as it was the best of plasma and CRT technology rolled into one.
This is not something you would notice with plasma signage but in the home with a variety of images... absolutely!
About mid 2000s, 2005, this problem was rectified by providing an aging algorithm as part of the controller, the board that actually runs the panel. Some plasma models we see today for repair have the sparkly problem and we can install an updated controller CBA to resolve that. As far as I know, all plasma going forward from about that time included this algorithm.
I suspect all recent plasma products will develop this black level problem, and I also suspect only the videophiles will notice. That said, I have not heard a peep from ISF calibrators who own one. I'll check into that...
It appears the only way to correct it would be to replace the plasma panel and due to cost that won't be happening.
As a video race car driver, there is a lot to like about plasma and a lot to hate, and it's a damn shame SED withered on the vine and could not compete in the market as it was the best of plasma and CRT technology rolled into one.
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akirby
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Richard
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Richard
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oh... Gotta come up with a new term for that... That statement in the home can easily lead to being asked what kind of car racing I like to watch...
Sine you mention it, I too am disappointed by how long GT5 is taking. I have not looked at it for 2 years but I still have my wheel ready to go (if they fully support it - ARGH)! I am also all absorbed in WOW, and recently Mass Effect on PC.
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wessokolosky
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While all plasma manufacturers adjust idle voltage over time, only Panasonic appears to adjust it so aggressively that MLL increases in all their 11th and 12th generation (2008 and 2009) panels...when measured properly. Panasonic has announced this same MLL increase will occur, but slower in their 2010 plasma panels. Measurements of other manufacturers panels have not shown a similar increase in MLL. I believe that Tom Huffman (a well regarded ISF calibrator) was the first to report this observation, in April 2009, in a panel he owns and measures regularly. (The master thread over on AVSforum is daunting, but the first post is updated regularly.) It appears that in some 2009 panels, the MLL increase is both sudden and dramatic, approaching a quadrupling of baseline (new, out of the box measurement).Richard wrote:...
About mid 2000s, 2005, this problem was rectified by providing an aging algorithm as part of the controller, the board that actually runs the panel. Some plasma models we see today for repair have the sparkly problem and we can install an updated controller CBA to resolve that. As far as I know, all plasma going forward from about that time included this algorithm.
I suspect all recent plasma products will develop this black level problem, and I also suspect only the videophiles will notice. That said, I have not heard a peep from ISF calibrators who own one. I'll check into that...
....
Wes Sokolosky