Panasonic plasmas have been reported to be increasing in brightness after a certain period of use causing some overseas users to complain, but the company says this is normal and will not be fixed.
In a statement to CNET US, which had received a "barrage" of reader complaints, Panasonic said that its plasma TVs' "background brightness will increase", but described the change as "automatic" over the TV's lifespan and part of normal operation in order to "achieve the optimal picture performance throughout the life of the set".
Bob Perry, senior VP of Panasonic Consumer Electronics Company (US), said that "since the TVs work as designed, there's nothing to fix".
While CNET Australia has received several enquiries from readers it has yet to hear of any compaints from local Panasonic owners.
Professional TV calibrator Aaron Rigg from Avical says that plasmas tend to dull over time, but has "never noticed" any specific issues with Panasonic plasmas he had worked on.
Rigg said plasmas normally tend to drop in brightness — by as much as 5 per cent in two years — but reckons it is still a very stable technology in comparison to the majority of LCDs.
"LCD brightness drops off very rapidly in the first 1000 hours, as much as 20 per cent in my opinion", Rigg said.
"I won't disagree with that", said Evan Manolis AV manager at Samsung Australia, "That's why LED was invented. It's more like plasma and is better at keeping its brightness and picture quality."
Manolis, who previously worked at Panasonic, also said he had never heard of the issue, and added that it wasn't the case with Samsung plasmas.
Avical's Aaron Rigg said that it is possible to "drive" plasmas harder which would make them brighter, and that the Panasonic plasmas could be doing this slightly after the panel has been run-in. He said that the effect was probably imperceptible, and that even a change as large as 20 per cent was difficult to tell in isolation.
Meanwhile, another 'calibrator' who goes under the screen name D-Nice told CNET US the problem appears more sudden and says he believes it is an engineering problem. "It seems as if Panasonic Engineering goofed on a portion of their software that modifies the pixel voltage levels periodically... The end result is an elevated idle black that worsens as more hours are clocked on the display."
The local effect of this issue is unknown, as representatives from Panasonic Australia failed to return CNET Australia's attempts to contact them by the time of publication.