Panasonic has been sued in New Jersey for not maintaining the same image quality in regards to the black levels as the company has promised.
Panasonic has declined to comment on this particular situation but made this comment in general;
"The black level changes were acknowledged, although the change is said to be "automatic" over the life of the TV. The increase in background brightness was claimed to be necessary to "achieve the optimal picture performance throughout the life of the set."
The "automatic voltage adjustment" supposedly increases the black levels after several years until of use to maintain an acceptable image through time.