Sony XBR Mura

The clouding phenomenon affecting some large screen LCD panels is increasingly recognized as ‘mura’, a Japanese term for ‘unevenness’ used to describe a low-contrast and irregular pattern or region causing uneven screen uniformity under certain conditions. In United States, the problem first cropped up with the latest Sony Bravia XBR sets, but intriguingly, this has also been spotted on some UK Bravia W and X series units with the possibility that other manufacturers may suffer from similar issues.

There are many manifestations of this mura condition and the causes are probably quite diverse as well. Although Sony has not issued an official technical explanation for the mura appearance on some of its units, several reasons have been mentioned (not all by conspiracy theorists : )

  • Impurities or foreign particles in the crystal matrix
  • Uneven distribution of LCD matrix during manufacturing
  • Backlight variance
  • Thermal induced stress
  • Panel assembly induced stress

How to Detect It

You can actively search for the problem by (do all three):

  • Setting the LCD backlight to factory or normal levels.

  • Watching in low ambient light conditions.

  • Choose a dark scene with many black elements.

Generally, you can limit the appearance of mura or clouding by reversing the above conditions. So, watching your LCD in brighter conditions with lower backlight and normal programmes will not expose this problem. In the US, the fix for Sony XBR mura defect revolves around lowering the backlight.

Mura has probably been around since LCD technology was introduced to the public. Heck, my colleagues’ 19 inch LCD monitor and flatmate’s Toshiba 32 inch HDTV have clouding to some extent. So why now? Well, LCD screens are getting bigger and we are enjoying more content now in low light conditions. Put this together with high consumer expectations (hint: price driven) it’s not hard to imagine a public backlash, and a costly PR disaster, if you get it wrong.

Technical papers on the net seem to imply a quality control issue with mura afflicted panels, given the need for automatic inspection algorithms. So are these panels defective or just low in quality? You decide. My point is: always check your screen.

If you don’t know what I’m talking about, the following pics should give you some idea.

 

 

 

 

Here’s to a cloud nine experience!

Resource

For user experience and support on clouding please visit the following sites:

http://www.avsforum.com/avs-vb/showthread.php?t=748779&page=1&pp=30

http://www.avforums.com/forums/showthread.php?t=432171

Acknowledgements

http://www.behardware.com/articles/589-1/panels-a-carte-mura-components-dead-pixels.html

http://www.magictouch.com/Mura.pdf

http://ailab.snu.ac.kr/publication/down/IEICE2004.pdf

9 comments

  1. Inorder to check our sets prior to purchases just does mean that LCD procurements should be from a “brick-and-mortar” shop and not from online shops so that we can check the “Mura effect” and then decide on the specific piece to take home!

  2. Andrew Fawcett

    Yes but you still have to purchase the set from the store before you can open the box to check? They won’t let you go through their stock opening them until you find a good one. Once you have bought one then only if the store agrees it’s an issue will they let you have another. If Sony doesn’t see it as an issue the store may not, and are not forced to exchange it. Your based bet is online, as at least you have the money back support of the unseen goods act.

  3. I am not making recommendations on how you should go about purchasing a LCD HDTV. It’s more about checking your screen when it arrives so you don’t get caught out 1 day after the grace period ends. Clouds are NOT the only thing that you should be looking out for.

    I am in favour of open QC standards regarding mura defect as personally, I believe it should be priced correspondingly with the amount of `defect’.

  4. Andrew Fawcett

    Well I’m now in that boat, after plumping for a Sony and taking the risk of clouds, I’m sad to say it didn’t pay off. I have to say not quite as bad as some pictures I’ve seen, but still very noticable, for example when I boot a game on my PS3, for a few seconds I get to stare at clouds. :-(

    So if the EmpireDirect where I bought it from won’t consider a replacement, I’m left considering my rights as regards DSR. Having read through your article on it I was left with some hope. But then I checked EmpireDirects own returns policy, it does mention the 7 days as covered in the DSR, but also adds that goods must be as NEW, clearly I’ve had to open the set and switch it on to determine it has the issue in the first place. Where do I stand in your opinion?

  5. If your 7 days isn’t up, then you have recourse to DSR if you DO NOT claim a fault with the TV. You can say you didn’t like it blah…blah…blah. You may incur a charge for `returning’ the TV.

    If you claim a fault, then the companies will assume you want it and offer a repair or replacement.

    Companies have variable attitudes towards returns policy, so you can meet resistance at all points.

    You can talk to Sony Customer Services about the clouding. I believe they may ask you to change some settings, send an engineer etc. Be firm with your correspondence to them and follow their suggestions, they may sell you a story about `normal’ manufacturing tolerances but don’t accept it if the clouding is bad on your TV. It is their job to come to a satisfactory conclusion with their customers.

  6. I have now had several sets from Currys. I have to say their customer service has been spot on.

    I had 2 LE40N73s 1 had an RGB issue through scart, the other set turned the same channel green! Then I had the Sharp LC42XD1E – that back-light got quite noisey and I wasn’t too impressed hearing it during quiet scenes (the Samsungs didn’t have this issue at all).

    Then I got the LE40F1, this time I have clouding – I’ve explained to them as ‘gray spots on screen’ and they are happy to exchange for the LE40M86BD (each time has been within their 1 month refund/replace period).

    I pick up the set Friday/Saturday so am hopeful of FINALLY getting a set I am happy with.

  7. all 40 inch lcdtv’s and above have clouding ,if you not see it that does not mean that its not there. all tv-technologies(PLASMA,LCD etc..) have serious problems. the XBR4 /5 in the USA(KDL X3500 in europe) is the most incredible tv that i’ve ever seen,take your time before you send a XBR back.