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Jim Yanik

"Arfa Daily" wrote in
:

"hr(bob) " wrote in message
.
.. On Oct 18, 6:11 pm, "
wrote:
On Oct 18, 4:44 pm, "Arfa Daily" wrote:

"Dave Platt" wrote in message

...

Anyone else ever seen this effect on an LCD display, or have any
thoughts
on
how it could occur ?

Might the screen have been an LCD, or a CRT, which "bounces" the
image onto a translucent display screen via a mirror or lens
arrangement of some sort? All sort of opportunity for linearity
and misalignment issues with that sort of arrangement.

--
Dave Platt AE6EO

No evidence of any kind of 'line structure' on the display Dave, so
I don't
think that it was any kind of CRT display, direct or indirect. It
was just a
typical flat panel display on a bulkhead wall, the other side of
which was a
toilet. As well as these main bulkhead displays (there were several
throughout the length of the aircraft) there were also 'repeater'
displays
suspended from the cabin ceiling at regular intervals over the left
and right aisles. These were definitely small LCDs and were
perfectly linear in
both axes, which rules out there being any intrinsic non linearity
in the
original picture before it was placed on whatever media was used
onboard the
aircraft. It's a strange one, for sure ...

Arfa

I have seen this, and stranger effects, in LCD sets. For instance,
I've seen the image "fold-over" on the right side of the screen as if
it's hitting the inside of the CRT, but much more subtly, confined to
about 1/4" of the picture. I always figured it was some sort of
phenomenon arising from the A-to-D of the analog input signal, but I
don't even know if that's possible. I'd also be interested in hearing
what others think of this.- Hide quoted text -

- Show quoted text -

Was only the one bulkhead display non-linear? Did you get a chance to
see the bulkhead display on the other side of the plane? I've
traveled a lot over the years and seen minor non-linearity, but all
the LCD displays were always equal and so it was the source. LCD's
should by their very nature be linear unless the digital electronics
are "counting" wrong.

My thoughts exactly, Bob, which is why I am having so much trouble
getting my head around this one. As to other displays being like it,
there was only one more bulkhead one in front of me, right at the
front of the cabin just before business class, and then there was
another in there with them, which I couldn't see - remember that this
was a crappy little 767 that Delta had put on in place of the
wide-bodied plane that we should have been on, and which would have
had individual seatback LCDs. The 767 has a 2 - 3 - 2 seat
configuration, so only large bulkhead displays up the middle. (In
defence of the aircraft though, I have to say that it was very quick -
7hrs 22m across the Atlantic - and the leather seats were very
comfortable). Anyways, the display right at the front wasn't close
enough to see in detail, but the repeater screens over the aisles
certainly were, and as I think I said elsewhere, these were perfectly
linear in both axes, which I feel eliminates the source signal as
being in error in any way.

Arfa

I think you're right about the analog signal processing being the source of
the problem.
Any digital problem would be severe and highly noticeable.

--
Jim Yanik
jyanik
at
localnet
dot com