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Hardware

Flaws in LCD Displays? 23

Posted by Cliff from the those-darned-always-on-pixels dept.
jaredreimer asks: "Having just spent a sizeable amount of money on a top-of-the-line Sony VAIO notebook PC, I am extremely dismayed to find a single red pixel stuck on in the middle of the screen. While this is virtually unnoticable when running regular Windows applications [white backgrounds hide it well], it is unbelievably irritating when trying to watch DVD movies [which tend to have dark backgrounds]. The question is this: How good is good enough? Many vendors won't touch a screen unless it has six or ten bad pixels; is this fair, given that we spend thousands of dollars on their product? Barring a remedy from the manufacturer, has anyone heard of a software fix for this problem? (Preventing the pixel from ever lighting would be far preferable to having a red one stuck on.)"
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Flaws in LCD Displays? More

Flaws in LCD Displays?

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  • Perhaps you can drop a slight hint that you are actually evaluating the laptop before a major company purchase for all of your travelling sales staff (even if you don't have any).

    I did this recently with a Toshiba 4260dvd who's display thought it was actually a strobe light several times during the day.

    I had a new unit on my desk via airborne the next day before even sending the defective one back.

  • I have a Nanao CRT with a total of three "dead spots" - very small points (smaller than pixels on any LCD I've seen) that stay stubbornly black. I've thought about asking Nanao to replace it, but it doesn't really bother me that much.

  • Because, then you would have even uglier seams in the screen. This works fine for JumboTron stadium screens, where the seams can be an inch or so apart. However, the seam would have to less than a few micrometers in width in order for the display to look uniform. A display like this would be a living nightmare to backlight as well. You'd have odd areas in the display where you would have a bright sqauare and a slightly darker one. This will become more visiable as the screen ages. Each square would have to be individually backlit, because the frames of the square would get in the way of a single backlight. Furthermore, this type of layout would add alot of weight to the laptop.

    I also believe that failure rates would be just as high, since you would actually have to run the traces that drive the individual display components around in an odd fashon (i.e. how would you get the wires up to the center block of pixels?). It's these fragle traces that go bad and cause stuck pixels and stuck lines, not the actual element on the display itself.
  • If they threw away all the displays with a few bad pixels, the yields would be much worse and the cost of the display would be unaffordable for many people.

    My current laptop had its display replaced twice due to gross defects when it was new. The third display worked fine until recently, when a complete vertical line of pixels stopped working. Now it is no longer under warranty and it would be too expensive to replace the display.

  • Check with your manufacturer. Some have different acceptable thresholds for stuck "On" vs. stuck "Off" pixels, since the "On" pixels are usually more annoying than the "Off" ones.
  • I've been told by someone who claimed what he knew was fact that the manufactures only keep one in five made. That means your paying for four you don't use. If that is true I'm can sympathize why they manufacturers don't wanna replace them but it don't make me sympathize with them any.


    Citrix

  • man my post sucked! sorry I need sleep.

    I meant to say:

    If that is true I'm can see why the manufacturers don't wanna replace them but it doesn't make me sympathize with them any.

    Hopefully this one doens't .. as much :-)
    Citrix

  • I bought an Advent laptop from PCWorld as well!

    As far as I know - most displays upto 1024*768 seem to be defect free.

    When the resolution is increased beyond this - the defects become more common (I hate to think how many components these things have!)
  • I bought an Advent laptop from PC World last month and found it had a single always-on pixel.

    They didn't bat an eyelid when I took it back the next day and replaced it without charge.

    You can't say fairer than that, can you?

    (PS. I don't work for them :)

  • Unfortunately trying to get them to replace your display based on 1 or 2 bad pixels will get you nothing, my dell has the same sort of policy, 6 bad pixels is considered acceptable. The chance of Sony replacing it for you is basically zero which leaves you with the rather questionable task of fucking up the display yourself so that they have to replace it. this involvs opening up your display and monkeying around with stuff but being careful to make it look like things weren't monkey with'd so that your display is sufficently fucked for them to replace it.
  • Do Sony use more than one 'block' for some of the Viao laptops? Just asking as my Vaio (F250) has an annoying horz. divide accross the srcreen with slightly different contrasts above and below it. I do not know why. Is this a fault (ie can I get it replaced) or is it normal (for this model)?
  • One thing to try: take a slightly damp soft cloth, same as you'd use to clean the display and gently massage the pixel. You'll get the weird afterimage like when you touch the screen, but that's OK. Sometimes ON pixels fix themselves with a bit of manual stimulation.
  • Heh, when you said "naugty pixel", my mind flashed to Robert Heinlein's story that had a cat named Pixel involved somehow...damn it's been a long time since I read that.

    Weird, sorry for the off-topic post.

  • So, might as well call whomever you bought it from and tell them there are bad pixels on the display, and that you need a replacement unit. If they tell you that you need X number of bad pixels, just start being an asshole about it, and they'll probably see it your way ;)
    Trouble is, any manufacturer with any sense won't tell you what the spec is for a defective TFT, simply because they can't afford to give away that many free ones. If you really work on them, they might ask you to tell them what your screen has on it, and then tell you yes or no as to whether they will replace it for you, but unless they're fools, that's as far as they'll go. Sorry, but if they replaced every TFT with one defective pixel they'd be out of business ..
  • Check with your manufacturer. Some have different acceptable thresholds for stuck "On" vs. stuck "Off" pixels, since the "On" pixels are usually more annoying than the "Off" ones.
    Makes sense, particularly if you watch DVD's on your laptop -- although if a pixel has one fail-dark color in it, you'll still see a noticeable color spot on a white field like a text window. I would also suspect that since there's a transistor in the equation and they tend to fail shorted, that affects the distribution of stuck-on vs. stuck off somewhat ..
  • Someone needs to make a piece of software to short out pixels so that we can get to the 6 pixel limmit and get our displays fixed! :P
  • Same situation for me (er, at work), bought it from CDW. My rep checked, and apparently their policy (Sony's policy?) was to fill the request for a replacement unit. The unit I originally received had two bad pixels--the new one had only one, and it was in the lower right of the display, and hardly noticeable.

    So, might as well call whomever you bought it from and tell them there are bad pixels on the display, and that you need a replacement unit. If they tell you that you need X number of bad pixels, just start being an asshole about it, and they'll probably see it your way ;)

    BTW, I had them ship me a new unit before I sent the old one back. My thought was to just swap the HDDs so I didn't have to re-setup the new machine. BIG mistake. Find some other method of backing up the drive (Ghost it to a fileserver?) before attempting to swap the HDDs. The unit I had (505?) had the HDD nestled deep, deep within the unit.
  • Some of them seem to be caused by bad contacts. I have an el-cheapo laptop w a 1024x768 screen and one or two "naugty" pixels (prone to go bad, but if you give 'em a tap they shape up).

    Actually, it's better to give the screen a tap about 2 inches away from the bad pixel, horizontally or vertically. That has yet to fail to turn the pixel on.

    Anyway, after that experience, from now on, I'm buying all my laptops at stores, so I can check out the screen before I take them home.

    I will not spend $2K for anything that is defective, regardless of what they conscider acceptable.
  • Is it a passive matrix (STN) screen? What you describe sounds like a dual scan passive display. In fact that's why they're called "dual scan" - they're really two displays, one above the other, simultaneously refreshed to reduce the flicker.

    If it's an active matrix (TFT) display then there's something wrong with it, like a bad trace or damaged display cable.
  • I've used several Toshiba and Dell notebooks which started out with a flawless display, but a pixel suddenly went bad (usually showed up as blue or red all the time) after either several power-cycles, or after the first month of use.

    You can't necessarily tell a display will be perfect for you based on firing it up once in the store to test it. That's for sure.
  • Go with the flow, eh? Somebody give this man a promotion!

    Perhaps they could ship the laptops with duct tape over parts of the case, to give it that kewl X-Files kind of look...

    =P

  • ...Grungy screens?

    All the best films, such as BladeRunner and Aliens, have really dirty displays; with flickering, distortion and "we're losing your signal!" type-effects.

    Perhaps manufacturers could follow this lead. Perhaps that's why all the computers in the future do have dodgy displays.

    How about a window manager to handle this?

    That way the inherent defects in the screen will simply add to the overall effect.

    (I think I ate too much for lunch)

  • I seem to remember reading in the manual for my Libretto that Toshiba considered up to 6 (IIRC) flawed pixels acceptable. The problem is that from the users point of view, even a single flawed pixel can be unacceptable. A friend has an HP OmniBook with a single permanently blue pixel at the moment, and it is very noticable. You basically have two options: live with your manufacturer's ideas about the acceptable level of imperfection, or challenge it. In the UK, you may well be able to claim that the goods are not fit for purpose. Other countries probably have similar legislation. I suspect it'll need a test case in the courts before the manufacturers back down, though.

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