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Cleaning (Fixing?) stain on LCD

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May 29, 2004 1:45:37 AM

Archived from groups: comp.sys.laptops (More info?)

Toshiba Satellite 2435.

Recently noticed a very slight "stain" on the LCD screen. Its extremely
slight and only barely noticeable if an entire window is opened with a white
(or slightly grey) background. I have no idea how long it's been there, but
now that I know it's there it -- it's annoying. (I'm sure I'd have to
point it out to 8 out of 10 people, but once you know something is on a
screen, it likes to stare you in the face, sticking it's nose out you.)

Its not a digital problem. Its definetly some type of residue. Pattern is
irregular (about 1x2 inches) with "upward" smudge marks, as if it was wiped
at one time but some residue remained (and dried).

Tried rubbing it good with iso alcohol, (which did seem to take a bit of it
out -- further showing it's not a digital problem), but most of it still
remains.

Hesitant about trying other chemicals though. What chemicals, stronger than
iso alcohol, would be safe?

Also, (while looking at entire screen for any other "stains"), came across a
very small dark "fleck" near one of the corners. Hardly noticable before,
but now it too is bugging me. The little "fleck" is under the screen. Its
not a dead pixel though. At first, I thought it was a dead pixel, but after
looking real close at it, can see it is also irregular in shape and has the
mass of about 1.5 pixels. Tried massaging the screen and it moved a little
to the right. Definetly some type of debris -- which bring me to asking
this question about LCD screens:

Is the outer most part of the LCD screen actually part of the LCD screen?
On my Toshiba, it doesn't seem attached to the LCD itself. Pressing on the
screen, you can feel a very slight "gap" between this and the LCD. Is this
just a protective plastic window of some sort, protecting the LCD? Its
definetly plastic. Is it possible to take the top half of the laptop apart,
so you can clean both sides of this "plastic protector" and perhaps clean
off the LCD itself, (I would probably just spray the LCD screen itself with
compressed air, to avoid any residue left on it.) Seems like doing this
would solve both of the above issues.

Thanks...
May 29, 2004 6:16:09 PM

Archived from groups: comp.sys.laptops (More info?)

>Is this just a protective plastic window of some sort, protecting the LCD?

There is a thin, plastic membrane that coats the LCD. The smudge could
be on the inside; however, I've not read of anyway disassembling the LCD
to the degree that you are inquiring about.

Regards ... John
Anonymous
a b D Laptop
May 29, 2004 7:55:52 PM

Archived from groups: comp.sys.laptops (More info?)

An LCD panel has an "optical stack" that consists of 6 to 15 layers of
various materials. Some of these are simple, e.g. simple plastics or
films. Some of them are MUCH more exotic, although they may look like
simply sheets of clear plastic (things like polarizing filters). Some
of them, while still looking like just a sheet of clear plastic, are
HIGHLY exotic (there are "brightness enhancing films" that cost nearly
$100 for a single large sheet (from which the sheets in several LCD
panels can be cut).

On most LCD screen, the very front film really is nothing more than
relatively plain cleay mylar to simply protect the screen. So in
principle, you could take it apart and replace this. But in fact, you
can't. First, the risk of destroying the LCD screen if you try to take
it apart is very high, far greater than 50%, could be over 90% for some
models of LCD panels (they vary greatly in this regard, some really
can't be taken apart). Second, you will get dust in the panel -- and
you will have LOTS of "flecks" instead of just one. When panels are
being worked with in LCD assembly plants, it's done in a clean room or
on a laminar-flow workstation. The degree of cleanliness required is
almost as high as for opening a hard drive. It's not something that you
can do safely at a kitchen table.

So you really can't safely do anything about your "fleck". It's a piece
of dust inside the optical stack, but the risk of trying to remove it is
too high to justify the necessary disassembly.

As to the residue, I'm taking a big, deep breath here. When nothing
else works, I've found that lighter fluid (cigarette lighter fluid) will
remove almost anything. But this stuff is a solvent, and can damage
many plastics. I would consider it to be a very last resort, but you
could try some of it on a VERY SOFT lint-free cloth. My guess is that
it would remove the {whatever} without causing immediate damage to the
material, but there is some risk that it might cause subsequent
yellowing or crazing. Windex, which has ammonia, is something that I
think I'd try first. Windex, which is actually pretty strong and which
can also cause screen yellowing, should not be used OFTEN on LCD
screens, but for occasional use in relatively extreme situations (no
more than 2-3 times per year), it seems, in my experience, to be acceptable.

For normal cleaning, the eyeglass cleaner sold in spray bottles at
optical shops (also the optical departments of Sears and Sam's Club) is
probably the best stuff to use. For LCDs, spray it on a cloth, not on
the screen itself.


Jason wrote:

> Toshiba Satellite 2435.
>
> Recently noticed a very slight "stain" on the LCD screen. Its extremely
> slight and only barely noticeable if an entire window is opened with a white
> (or slightly grey) background. I have no idea how long it's been there, but
> now that I know it's there it -- it's annoying. (I'm sure I'd have to
> point it out to 8 out of 10 people, but once you know something is on a
> screen, it likes to stare you in the face, sticking it's nose out you.)
>
> Its not a digital problem. Its definetly some type of residue. Pattern is
> irregular (about 1x2 inches) with "upward" smudge marks, as if it was wiped
> at one time but some residue remained (and dried).
>
> Tried rubbing it good with iso alcohol, (which did seem to take a bit of it
> out -- further showing it's not a digital problem), but most of it still
> remains.
>
> Hesitant about trying other chemicals though. What chemicals, stronger than
> iso alcohol, would be safe?
>
> Also, (while looking at entire screen for any other "stains"), came across a
> very small dark "fleck" near one of the corners. Hardly noticable before,
> but now it too is bugging me. The little "fleck" is under the screen. Its
> not a dead pixel though. At first, I thought it was a dead pixel, but after
> looking real close at it, can see it is also irregular in shape and has the
> mass of about 1.5 pixels. Tried massaging the screen and it moved a little
> to the right. Definetly some type of debris -- which bring me to asking
> this question about LCD screens:
>
> Is the outer most part of the LCD screen actually part of the LCD screen?
> On my Toshiba, it doesn't seem attached to the LCD itself. Pressing on the
> screen, you can feel a very slight "gap" between this and the LCD. Is this
> just a protective plastic window of some sort, protecting the LCD? Its
> definetly plastic. Is it possible to take the top half of the laptop apart,
> so you can clean both sides of this "plastic protector" and perhaps clean
> off the LCD itself, (I would probably just spray the LCD screen itself with
> compressed air, to avoid any residue left on it.) Seems like doing this
> would solve both of the above issues.
>
> Thanks...
>
>
Related resources
May 29, 2004 11:34:10 PM

Archived from groups: comp.sys.laptops (More info?)

Hi,

Thank you for your reply -- especially for bringing me back to my senses
about thinking going into a laptop LCD.

I've replaced a touchscreen for a PDA before, which lays just on top the LCD
screen, and as you said that was a major pain to prevent dust being trapped
between the two layers. Took as much precaution as possible, doing it on
well luminated workbench, took ESD precautions (mat and wrist wrap), even
had an ionized fan blowing -- but it was still a pain. Eventually got it,
after a half a dozen tries. I definetly shouldn't been even thinking about
doing it for a laptop LCD. Besides, the little speck was there, I'm sure,
as long as I had this laptop. (Just didn't notice it before.)

Strange how these little things "stare you in the face" once you noticed
them the first time. LOL. I suppose I should just be thankful that there
isn't a single dead pixel on the LCD.

After writing last post, I used iso alcohol again and put a bit of elbow
grease into it. Even more of the residue came off, its now about 1/2 the
size and even fainter. So, if anything else, I'm happy to know that its on
the outside and not inside.

Zippo lighter fluid actually did cross my mind, but I was paranoid about
even giving it a try. Is there an anti-reflective coating on the protective
plastic? I'm worried about eating that off. I may try a very small amount
of zippo on a Q-tip in one of the corners and see if it is too harmful.

Oh well, guess I can live with this very small spot of residue now anyway.
In time it may fade away. The world isn't a perfect place anyway.

Thanks again,
Jason
May 31, 2004 4:10:18 AM

Archived from groups: comp.sys.laptops (More info?)

To follow up my own post, I went ahead and gave lighter fluid a try. Using
just a Q-tip, I did a test spot in one of the corners first. The test spot
wasn't damaged by the fluid, so I decided to give it a try with removing the
large "stain".

Using a lint-free cloth, I wiped the stain area with lighter fluid and then
quickly wiped it with another lint-free cloth saturated in a water + iso
alcohol solution.

The second cloth picked up a bit of "something" and I was quite worried that
I had taken off what may have been an anti-glare coating. From looking at
the screen, nothing appeared to have been damaged though. I then powered
up.

The stain was completetly removed and the area cleaned was indistinguisable
from the rest of the screen. It worked!

I definetly wouldn't recommend anyone to use lighter fluid to clean their
LCD, but I can report that lighter fluid did remove a stuborn stain on my
Toshiba LCD. I wouldn't even think about attempting it unless you have a
very stubborn stain -- and even then be careful. Do a test spot first. Get
the fluid off the screen as quickly as you can afterwards.

I also think I know where the faint stain originated from. While at work, I
was involved with something that required spray painting. I got some of the
black spray paint on thumb and forefinger. Afterwards, I closed my laptop
and bagged it -- getting some of the paint on the outside of the laptop
(which I cleaned right away). I probably got some paint on the LCD and
didn't know it at the time, which was about six months ago.

I think I'm going to look at new laptops again anyway. When I got this one,
I balanced between cost and performance. Since I'm doing a bit of video
work now, I think I'll look for a higher-end laptop. Starting research
again on laptops, this time leaning towards IBM's.
!