Saturday, December 30, 2006

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.

12 comments:

Anonymous said...

Great write up. I have also posted Pictures of my banding on my 52"sharp aquos on the AVS forums. I really like my set and don't plan on sending it back. I hope that this problem gets identified for all future LCD panels, regardless of who makes them.

Anonymous said...

I have a sharp aquos 52" lcd that I purchased in late dec 2006 and it has NO signs of banding...I love the TV it is the best that I found on the market today

Anonymous said...

I believe the "Coating" he mentioned is the new 3M Vikuiti coating that is touted on Shap's Aquos page. It is supposedly an anti glare coating that they started using, I believe on this model. I too had thought this may be the cause, be it from inconsistant coating, or even interferance with the polarized light (anyone who has looked at a car windshield in the sun with good polarized sunglasses will know what I mean.

Homer Simpson said...

How funny, I just posted about the Sony "cloud" issue on my blog. I too read the AVS forum, but I bought a Sony anyways - at Costco. So far I'm happy.

Anonymous said...

I have a Sharp 46" Aquos 1080p. Purchased it way back in October of 2006. Noticed the horizontal banding right away. Tried to live with it since it is not always noticeable. But, once you recognize the banding, it is very difficult not to be distracted by it.
It is a manufacturing defect since Sharp is swapping out my screen... finally. Thanks for the post.

Eric said...

Hi,

Got a Sharp AQUOS LC-52RX1W since March 2007. I noticed the banding after some weeks and tried different sources (TV/DVD...) same results. the Sharp after sales engineer is coming tonight for checking the issue. Let you know the result later and wil post pictures as well.
I was not able to find relevant explanation on this problem that seems to affect mainly Sharp sets. Mine was made in Kameyama Fact, supposedly the highest standart in the industry. Let's see.

Thanks for this instructive blog,

RicoRox

Anonymous said...

I heard that people having banding issues with the 62U, but not with the 64U. I purchased a Sharp Aquos 52" 64U. Recently I have seen many people in forums say the 64U also had banding issues. I was a little afraid to check to see if my tv had them, if I found banding issues I would always see them and it would drive me crazy. So I purchased DVE Basics Blu-Ray, I have absolutely no banding. I have calibrated my TV using DVE Basic Blu-Ray and verified that I no not have banding using the test patterns provided on the disc.

snadge said...

I have had 2 LCD TV's and both have had banding to some degree -

the first was a BUSH 32LCD 720p set and at first i didnt notice - not for 9 months then it seemed to 'appear' then get worse - i got rid of it and bought a new LG 32LG5700 1080p set and this one has very minimal banding - it doesnt even cover whole screen its just visible in top half on left and right sides...

At first I though this was caused by the backlight perhaps heating the LCD screen too much and causing the pixels in affected area to fault.... hence it got worse as time went on...

then I heard it was a defect that happens during the manufacturing process - and the companys let MANY of them out the factory doors otherwise it would be too costly an issue for them too repair every one that has it - this isnt our fault and the end user shoudlnt be mae to pay for it....

Anonymous said...

Looks like I'm the first to post that the Sharp Aquos 65" has a banding problem as well. About 6" right across the middle of the screen, horizontally. I'm still under warranty so hopefully, it'll be fixed or replaced.

eric said...

Anonymous,

You said:

Looks like I'm the first to post that the Sharp Aquos 65" has a banding problem as well. About 6" right across the middle of the screen, horizontally. I'm still under warranty so hopefully, it'll be fixed or replaced.

It's been a while since I posted the above about my bedroom TV. Since then I've obtained a Samsung LCD for my living room. It doesn't have "banding," but it does have the "clouds" that are referred to by the Japanese synonym mura.

I have also gotten an iMac computer whose screen has very noticeable banding. The bands are vertical ones, and they are distributed across the whole screen. There are times when the screen almost looks "corrugated."

Your problem is a single horizontal band running right-to-left (or left-to-right) across the middle of the screen, right?

Is your Sharp Aquos model the LC-6577UM? It uses an Advanced Super View Superlucent Panel, I hear ... though I don't know what that means. I'd like to know whether that technology is prone to banding ... let me know how you make out!

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