Home theater enthusiasts have long appreciated plasma sets for their cinematic qualities, including, among other things, their ability to display truly dark blacks. But following complaints from some customers, Panasonic--the largest manufacturer of plasma TV sets in the world--has acknowledged that over time, the blacks on its plasmas will get somewhat lighter.
A company official says that most people won’t even notice the change, which results from technology designed to optimize the set’s overall performance as it ages. Bob Perry, senior vice president of marketing, e-commerce, and supply-chain management, says that the change will likely not be apparent to most viewers--and that it doesn’t significantly degrade image quality.
“We still either outperform, or are at least as good as, our competitors in terms of picture performance,” Perry said in a phone interview. However, he added, Panasonic continues to refine the technology, and the phenomenon will be less apparent in 2010 TV models.
At issue is the attribute known as black level, which on a plasma set can get very low (meaning the set can become very dark). Plasma sets create images by lighting up gaseous cells; only the cells that need to be lit are lit, which allows for deeper blacks.
In contrast, dark blacks are more difficult to achieve on LCDs since traditionally the entire panel is backlit, and completely shutting off light to the pixels is hard (LED-backlit LCDs often have local dimming features, which turn off the backlight in dark areas of the picture). Images with deep blacks generally look more attractive than those in which the darkest hues are grey.
“Some people believe that deeper and deeper blacks give you a wider contrast range and more variation in terms of a color palette,” Perry says.
In order to keep overall image quality high as a set ages, however, Panasonic makes several adjustments (Perry declined to be more specific, citing trade-secret concerns). One adjustment increases overall luminance after roughly three or four years (or less, for sets in frequent use).
A viewer sitting in front of the set when the adjustment occurred “might see overall brightness go up slightly,” Perry says. And as a consequence, the black level would increase too, resulting in lighter black tones.
“In 2009 sets, the adjustment was fairly coarse, which might be why someone noticed it,” Perry says.
Questions about shifts in black levels for Panasonic sets arose after a poster to AVS Forum, a popular community site for audio and video enthusiasts, observed that the blacks had become noticeably lighter on his set.
Though he couldn’t say whether other plasma sets are prone to the phenomenon, Perry did note that most plasma manufacturers build control circuits designed to maintain overall image quality as a set’s components age. The luminance adjustments in Panasonic’s 2010 plasmas will be more subtle, and therefore less likely to be visible to the naked eye as they occur, he says.
This story, "Panasonic Pooh-Poohs Black-Level Brouhaha" was originally published by PCWorld.