Why are the surfaces of some LCD screens soft?

[Mxsmanic]

I notice that the screens of two of my LCD displays are "soft"; that is,
they don't seem to be made of rigid glass, but of some sort of soft,
flexible plastic. If I press my fingertip lightly against the screen,
its influence on the image is obvious, implying that the screen is so
flexible that it indents beneath my finger.

What's the reason for this? Wouldn't it make more sense to put a rigid
class plate over the front of the screen to protect it?

The front of the screens is soft enough that I was able to eliminate a
hot pixel on one screen by "massaging" it gently with a fingertip (and
it never came back, fortunately).

 

[Bob Myers]

I notice that the screens of two of my LCD displays are "soft"; that is,
they don't seem to be made of rigid glass, but of some sort of soft,
flexible plastic. If I press my fingertip lightly against the screen,
its influence on the image is obvious, implying that the screen is so
flexible that it indents beneath my finger.

Many if not most panels will have an anti-glare film added
as the "top" or "front" surface of the panel. There's little sense
in putting a piece of polished glass over THAT, since it would
defeat the purpose. The entire "top" substrate, glass, film, and
all, of a typical LCD IS flexible to some degree, though, as the
glass is very thin. Typical LCD glass these days is 0.7 mm thick,
with some notebook panels getting down to about 0.4 mm and
practically no one using glass more than about 1.1 mm thick.
It WILL given under finger pressue. It's not recommended that
you apply such pressure to an LCD screen, as the same sort
of pressure which you noted can clear up some forms of
defects can also cause them. (These sorts of problems generally
result from a non-uniform distribution of spacers within the
actual LC layer, which results in non-uniformity in the LC
cell gap. That gap itself is generally on the order of a few microns.)

Bob M.

 

[Mxsmanic]

It's not recommended that you apply such pressure to an
LCD screen, as the same sort of pressure which you noted
can clear up some forms of defects can also cause them.

How does one clean an LCD screen? It was easy enough on CRTs, with
their indestructible glass surface, but what about LCDs? They don't
seem to have that magic attraction for dust that CRTs have, but they
still gather dust eventually. The manual for my new LCD seems to
indicate that I can clean it with a "soft cloth," but I am wary.

 

[SR2]

How does one clean an LCD screen? It was easy enough on CRTs, with

their indestructible glass surface, but what about LCDs? They don't
seem to have that magic attraction for dust that CRTs have, but they
still gather dust eventually. The manual for my new LCD seems to
indicate that I can clean it with a "soft cloth," but I am wary.

To remove dust you can use a good feather duster.

For more ostinate dirt buy a 3M Scotch Brite 2010 cloth.
It's expensive for a cloth, but you can remove fingermarks
using only some water.
Be careful to don't leave the fingermarks for long time
ore they would be irremediably fixed (!)
I this and other difficult cases the right solvent to try is
Isopropilic Alcohol.

Greetings

 

[SR2]

Many if not most panels will have an anti-glare film added

as the "top" or "front" surface of the panel.

[cut]

Hello Bob!
I can see you are always the number one... :-]

What do you think about new LCD with
hardware acceleration (overdrive)?
Like this:
http://www.eizo.com/products/lcd/l778/spec.asp

You think this is an effective solution to reduce
smearing or only a "lemon"? :-\

Thanks

(sorry for the intrusion)

 

[Mxsmanic]

Be careful to don't leave the fingermarks for long time
ore they would be irremediably fixed (!)

What do you mean??

I this and other difficult cases the right solvent to try is
Isopropilic Alcohol.

The instructions say never to use any type of alcohol.

 

[Bob Niland]

How does one clean an LCD screen?

Start with the manufacturer's recommendations. You
might have to hit their web site to find them.

It was easy enough on CRTs, with their indestructible
glass surface, ...

Whoa. Low-end CRTs may well be plain glass at the
surface, but most mid-range and hi-end units have
a fairly delicate anti-reflection coating, which is
all too easy to damage or even entirely remove.

The manual for my new LCD seems to indicate that
I can clean it with a "soft cloth," but I am wary.

Be wary, and don't rely on 3rd-party cleaning gear
either. Most of the junk for cleaning CDs and CD
players, for example, is just plain dangerous to
both data and drive.

 

[SR2]

What do you mean??

My english is a little bad.

"fingermark" is correct?
When you touch the monitor with the hands... (?)

I seen that if you leave this dirt for long time
(many months I think) it becomes very very
difficult to clean.

The instructions say never to use any type of alcohol.

Samsung recommends "Isopropilic Alcohol".
But it may be that I've made a bad generalization... :-\

I've used the 3M micro-fibre cloth for more than a
year and never have need any other...

 

[Bob Myers]

Getting caught up after being computer-free over the holidays -
sorry for the delay...

What do you think about new LCD with
hardware acceleration (overdrive)?
Like this:
http://www.eizo.com/products/lcd/l778/spec.asp

Overdrive is a legitimate ad very effective means of reducing
LCD response times. In general, it involves hitting the subpixels
in question "harder" (higher drive voltage) than would be expected
from the target gray level on the first frame of drive, in order to
get the LC molecules changing state more rapidly, and then
getting them in to the proper state (with the correct drive
voltage) on later frames. Done properly, it has basically no
bad side-effects.

Bob M.