Weird LCD "backlight" problem

Anyone else seen this?

Last night I spotted a small black streak on my 32inch Panasonic LCD screen.
"Dead pixels" I thought, although the pattern really looked like a diagonal
scratch.

I checked the screen and it wasn't scratched so hooked up a laptop and ran
on of those "pixel exerciser" programs (UDPixel). This produces a white
block which you move over the dead pixels and it flashes them until they
either submit and start working, or you loose interest.

But having set this going, I had to move sideways slightly and realised I
could see the entire white block now. Looking closer I realised that the
pixels were all working but that the "scratch" seemed to be BEHIND the
pixels.

My guess is that the backlight lights a "big white panel" behind the pixels
and somehow some of the white on this panel has flaked off. So no matter
what the pixels are doing, there is no light being reflected though.

Does this sound reasonable and if so, anyone else seen this?

And before anyone says "warrantee" - yes, it will be going back soon (whilst
we're on holiday so we won't miss it!).

Paul DS

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Paul D.Smith"
saying something like:

My guess is that the backlight lights a "big white panel" behind the pixels
and somehow some of the white on this panel has flaked off. So no matter
what the pixels are doing, there is no light being reflected though.

Does this sound reasonable and if so, anyone else seen this?

I've butchered a couple of LCD monitors recently and yes, there's a 5mm
thick sheet of plexiglass end-on to the backlight fluorescent strips.
Each of the sheets is covered in a diagonal pattern of etched squares,
about 2mm wide, to distribute the light evenly. Behind this plexi sheet
there's an ultra-white sheet of plastic.

On 16 June, 17:41, Grimly Curmudgeon
wrote:
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Paul D.Smith"
saying something like:

My guess is that the backlight lights a "big white panel" behind the pixels
and somehow some of the white on this panel has flaked off. *So no matter
what the pixels are doing, there is no light being reflected though.

Does this sound reasonable and if so, anyone else seen this?

I've butchered a couple of LCD monitors recently and yes, there's a 5mm
thick sheet of plexiglass end-on to the backlight fluorescent strips.
Each of the sheets is covered in a diagonal pattern of etched squares,
about 2mm wide, to distribute the light evenly. Behind this plexi sheet
there's an ultra-white sheet of plastic.

I've repaired a couple of Laptops recently and can concur with this.
No experience with TVs on this level but the technology is very
similar.
When I think of this backlit process it's no wonder LCDs can't compete
with Plasmas on the Contrast Ratio front.