This story broke last week on CNET after owners on AVSforum noticed black levels on NEO PDP plasma’s were slowly rising with age. Panasonic’s acknowledged the the issue today by responding to TV editor David Katzmaier inquiry into the matter:
Panasonic Viera plasma HDTVs deliver exceptional picture performance throughout the lifetime of these products. Various elements and material characteristics of all electronic displays change with use over time. In order to achieve the optimal picture performance throughout the life of the set, Panasonic Viera plasma HDTVs incorporate an automatic control which adjusts an internal driving voltage at predetermined intervals of operational hours.
As a result of this automatic voltage adjustment, background brightness will increase from its initial value. After several years of typical use, the internal material characteristics will stabilize and no additional automatic voltage adjustments are required. The Black Level at this stabilized point will yield excellent picture performance.
The newest Viera plasma HDTVs incorporate an improved automatic control which applies the voltage adjustments in smaller increments. This results in a more gradual change in the Black Level over time.
What does this mean? It means the black level rise is by design to help compensate for the aging of the panel. Does this mean you should hold off on buying a Panasonic plasma? In our opinion no. Even with elevated blacks (if you notice it) the NEO plasma’s are still competitive with sets from Samsung and just about anything else out there with liquid crystal technology so don’t sweat it. Don’t quote us on this, but just about all plasma displays do something similar to compensate for phosphor wear so it’s really nothing new, however it’s usually done in a way thats imperceptible to the owner. Extreme videophiles may be disappointed with the news, but perhaps the companies upcoming flagship VT25 display will make us all forget.
UPDATE: CNET editor David Katzmaier had a long talk with Panasonic about the issue. Basically the company states there will be no fix for the black level rise as “there’s nothing to fix.”. These are his words below:
“Since the TVs work as designed, there’s nothing to fix.”
That answer comes from Bob Perry, Senior VP of Panasonic Consumer Electronics Company, in reply to a follow-up question CNET asked in response to the company’s February 3 statement addressing reports about the company’s plasma TVs losing their deep black levels over time.
That statement maintained that the plasmas’ black levels are designed to brighten over time (“background brightness will increase from its initial value”) to compensate for the normal aging process, but suggested that picture quality was still “excellent” after the compensation period was complete and the “internal material characteristics…stabilize.”
In a February 5 phone call with CNET (also attended by CNET editors and Bill Schindler, an independent engineering consultant for Panasonic), Perry confirmed that the company has no plans to fix anything related to the black level-related complaints with its current plasmas. He echoed the explanation in the original statement and elaborated somewhat on the black level increase. He likened it to rotating the tires on a car–an example of standard maintenance–and said that some users noticed the change “because they have trained eyes,” although he also said that the change is subtle “even among trained experts.”
He did not go into specifics on many points, however, claiming that some answers might give away trade secrets and that lack of standards for black level measurement make it “very difficult to make meaningful comparisons.”
He reiterated that owner satisfaction was very high and that the vast majority of owners don’t notice any change at all. See the end of this article for the full text of an e-mail sent by Perry the morning of February 9, with Perry’s complete responses to CNET’s follow-up questions.
Perry’s answer that there’s nothing to fix seems to contradict statements made by respected calibrator D-Nice, citing sources within Panasonic. In an e-mail to CNET, D-Nice wrote: “It seems as if Panasonic Engineering goofed on a portion of their software that modifies the pixel voltage levels periodically. All plasmas have a voltage control system that adjusts pixel voltage at predefined hours of use to ensure pixels do not misfire. However, Panasonic’s software seems to be going overboard in this area. The end result is an elevated idle black that worsens as more hours are clocked on the display.” He made similar statements first on the AVS forum thread that originally surfaced those user complaints.
Some user comments to the previous two CNET articles, as well as postings to the AVS thread such as themeasurements painstakingly collected here, seem to support the “goof” theory with eyewitness accounts that the black level increase is abrupt, easily noticeable, and detrimental to picture quality. Meanwhile, Panasonic’s statement that new 2010 plasmas feature “more gradual change in the black level over time” seems to confirm that the behavior of the 2009 models is less than ideal, although Panasonic characterizes it as “a natural part of our product development efforts and how our products evolve.”
On the other hand, other posts and comments note no change at all.
Ironclad confirmation of the extent of the black level rise–the crucial question as far as I’m concerned as a TV reviewer–is still elusive. I haven’t seen the black level change myself. Perry did offer to set up a demo featuring new vs. aged panels so I could judge for myself, but considering Panasonic’s vested interests, I wouldn’t consider any result from such a demo meaningful.
Instead, I am currently long-term testing a pair of Panasonic plasmas and have noted no increase in black levels over the last week, but that doesn’t mean much since by the company’s own estimation, the adjustment process takes years. Of course, those tests will continue indefinitely. Given my tests and the fact that numerous CNET editors use Panasonic plasmas every day at home, I’m confident that meaningful results will manifest eventually.
The fact remains that it’s now the end of the 2009 TV buying cycle and the company’s current plasmas are going for rock-bottom prices to make way for the new 2010 models. Those ’09 Panasonic sets are pretty tempting and, at least initially, should deliver excellent picture quality.
But if I were buying a plasma TV right now, I would avoid the 2009 line of Panasonic plasmas. The user reports cited above, and Panasonic’s statement that the 2010 models feature a more gradual change, are currently enough to make me doubt the long-term picture quality of the company’s 2009 plasmas. See our Best products lists for more details on alternative models; the Samsung PNB650 and PNB850/860 models are my (new) current favorites among 2009 plasmas.
That said, I won’t be modifying my reviews or ratings of 2009 Panasonic plasmas beyond including a prominent Editors’ Note referring to this issue, and removing the Editors’ Choice award from the V10 series (hey, I just said it wouldn’t be my choice). My hands-on reviews must reflect my actual experience, and for now that experience is of mostly excellent black level performance. The same restriction will apply to any 2010 Panasonic plasma TV reviews, and to all of my reviews in general. If my tests or other experience eventually reveals anything different, you’ll hear about it here first.
Bob Perry e-mail
What follows is the full text of the email replies Perry sent in reply to CNET’s follow-up questions.
Q: Is a fix planned for current TVs to address owner complaints? If so, when? If not, why not?
A: Of course, electronic display characteristics change over time. Our sophisticated Viera displays are designed to automatically adjust over time, too, to optimize their performance and reliability. Since the TVs work as designed, there’s nothing to fix.
Q: At what “predetermined intervals” do the voltages increase? Hour counts? If so, what are they and how much do the increases affect black levels each time?
A: As you can understand, exactly how this works is proprietary information that we regard as a trade secret. We can’t give away trade secrets.
Q: When do the materials stabilize? The statement mentioned “years,” anything more specific?
A: It varies based on the assumptions you make, but it would be safe to assume that around three years, more or less, is a reasonable approximation.
Q: What is the quantitative difference between the initial black level and the “stabilized point” referred to in the statement?
A: There is no agreed-upon standard way of measuring this, making it very difficult to make meaningful comparisons. Even at the stabilized value, our models’ black level performance is excellent. You can see that by comparing sets that have reached the stabilized value with new Panasonic sets and or other makers’ sets. And my offer to demo that for you still stands.
Q: Which are the “newest Viera plasma HDTVs” referred to in the statement? Please provide model numbers and, if current (2009) models are affected, how can a shopper determine between old and new ones, e.g. those with and without the more-gradual increases?
A: 2010 model year Viera TVs, which are being produced now, feature a more gradual automatic adjustment process.
Q: If the voltage increases are normal and current TVs have “excellent” performance, why do the newest TVs have a more gradual change?
A: We continuously make improvements in our products every year, that’s a natural part of our product development efforts and how our products evolve. As a result of design improvements in the 2010 PDP panels, the adjustment that takes place is now more gradual.
Q: Have all plasmas always lightened in terms of black level over time? Has Panasonic ever publicly addressed the long-term black level performance of its plasma TVs?
A: All displays, CRT, Projection, DLP, LCD and Plasma, have specific performance characteristics that change over time. Customer satisfaction with our Viera Plasma’s has been excellent. We are confident that the long-term black level performance will continue to provide customers with an excellent picture over years of use. As for your specific question, companies in the consumer electronics business, including Panasonic, only specify the initial values of their displays and do not project those values into the future.
Q: What should owners do who are unsatisfied with the picture quality of their TVs?
A: There is no reason for dissatisfaction with a product that works as it was intended to and provides industry-leading excellent black level performance. However, customers do have access to the Panasonic Plasma Concierge Program, which can provide advice and assistance on all customer satisfaction issues.