A New Bedroom HDTV for Me, Part VIII

I reported in A New Bedroom HDTV for Me, Part VII and previous posts that my new Sony KDL-40XBR2 1080p LCD TV has a problem with faint vertical bands that show up in some program content and are easiest to spot in gray test patterns. I have now discovered the same sort of thing complained of by owners of recent Sharp AQUOS 1080p LCDs.

In the Official Sharp Aquos 42D62U /46D62U /52D62U Owner's Thread at the AVS Forum I found post #192 to have this photo as its third attachment. It is of a Sharp AQUOS LC-52D62U 52" 1080p LCD panel.

In my judgment, the kind of vertical banding here is the same as my Sony exhibits. There may be less of it on view, but that may have to do with TV and camera settings, not with any intrinsic difference in the problem itself.

The first post in the AVS Forum thread contains a FAQ about the banding issue, adorablerocket's UNOFFICIAL SHARP D62U "BANDING" FAQ (ADDED 11/30/06). It says in part:

1. What is “banding”?

Banding is [a] name for a defect that occurs on *some* of Sharp’s d62u LCD TVs.

In the AVS forum this defect has been reported on 42”, 46” and 52” size TVs.

Banding is best described as stripes or “bands” of reduced brightness a few inches wide running across the display. These bands can run horizontally or vertically.

The bands range from very severe in some sets to quite subtle and may not be visible under most viewing circumstances. In general bands will be most notable when viewing a solid grey image.

Obviously a flat grey box is not something most people watch on their TVs. However the more an image resembles a flat grey field, the more it will display this defect if present. Slowly moving images of low contrast and saturation, such as may be found when playing some video games (for example turning around slowly in a room made of concrete) or watching some movies (for example in Master and Commander when the camera is focused on the subtle outline of a ship appearing through grey fog) will display the bands. Depending on the severity of the banding present on any given TV, more common images (for example a blank wall behind an actor) may also display the banding.

Generally if the banding is visible during normal use, viewers have found the banding to be an unacceptable defect of the TV. On the other hand viewers with sets that do display banding under the ‘grey screen test’ described above, or on occasional scenes, have said that the banding is livable, though many expect a repair or replacement from Sharp. Of course many other viewers have reported no banding or defects at all on their TVs.

You can search the thread for photos posted by people for whom the banding is clearly visible on a test screen ...

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12. What causes banding?

Nobody knows.

There has been speculation that the banding is part of the backlight process. There has also been speculation that it might be a defect in the LCD because it’s similar to a defect found in some LCD projectors.

If I had to [guess], I’d vote for micro misalignment on the horizontal and vertical backlight diffusers ...

There seem to be two different banding issues with the Sharps, one vertical like mine and the other horizontal. "To visualize [the horizontal bands]," one poster writes, "if you drew two horizontal lines across the screen to split it into almost-equal thirds (the middle third being just a touch larger), the bands are right on those lines." I have the feeling (as do many other posters) that some of the horizontal bands are caused by a form of interference, perhaps power-line interference. But, maybe not (see photo below).

There also seem to be posters who simply cannot see the faint vertical banding in the "problem" pictures posted in the thread by other participants. I am put in mind of the Sony-authorized service technician who swapped in a replacement LCD panel for my set. He couldn't see the bands either. Yet my HDTV installer who came back to do extra work for me said he could see them. This seems to be an issue for some eyeballs and not for others.

At right is another photo which shows vertical banding, from post #687. To my eyes, the lack of luminance uniformity is obvious. I also see what I would call horizontal banding as well.

Skipping ahead, in post #5699 an AVS Special Member named "mark_1080p" reproduces my own photo shown above of vertical banding revealed in window glare. (It's nice to be famous.) The poster says, "This would be simple to test for the Sharps, if you see banding in the glare or shine a very bright flashlight on it and see banding, then we know it is not the backlight but rather the coating. If you do not see it, I guess the cause is indeterminate." I'm not sure what he means by "the coating," however. I would imagine it to mean something on the very surface of the front of the LCD panel. To my eye, however, there seems to be a striated irregularity in the front surface that results from a physical unevenness — almost a pleated, corrugated effect — further down in the LCD "sandwich." That is, the problem doesn't seem to be confined to just the outer surface at all.

I get the feeling that the banding issue mushroomed in the Sharp thread over time. The thread was supposed to be about everything on these Sharp TVs, but a quick survey shows that something like one post in ten mentions banding, with the ratio getting higher the further along you go in the 190+ page thread. It's as if people became increasingly sensitized to this very faint source of imperfection by reading about it and seeing pictures of it.

In fact, I'd have to say the "banding issue" has become for Sharp AQUOS 1080p's what the "cloudy backlight issue" has for Sony BRAVIA XBRs like mine: something of a widespread scandal. It's odd that I have a Sony with a "Sharp issue," while I've yet to find a Sharp owner complaining about "clouds" in their backlight.