Arfa Daily wrote:
Yes Geoff, I'm aware of all that. I work with the technology all the time.
Did you read the original thread from last week ? We were not discussing the
differences between transport and encoding systems, rather the moral - if
not technical - validity of Sammy advertising this new offering of theirs as
a "LED TV", which it isn't. It's an LCD TV with an alternate form of
backlighting (LEDs rather than CCFL).

I have no idea of UK law, but in the US and here in Israel, if they use
LED's in the display, then they can call it an "LED TV". I expect the same
in the UK, I was watching a show from the first season of "The F Word" (things
take a long time to get here) and they were discussing exactly what could be
called a sasuage in the UK. Based on what I saw, I expect you would have
trouble fighting them calling a TV with a power on LED an LED TV. :-(



One of the main selling points that they claim, is that because they can
control the intensity of the backlighting in individual areas, they can
deepen the blacks, effectively improving the contrast ratio.

In theory, yes they can. Since LCD's have very limited control over brightness
then a variable brightness LED behind an LCD will allow them to modulate the
light level of that particular pixel.

I don't know the resolution of the LCD array used in a TV set, but at the
actual crystal level, it's clear (on edge) or colored/transparent (face out).
I guess if you modulated the polarizing signal you could get levels of color
out of them, but I thought that the crystals were not fast enough for that.


On the example
that I saw last night, I observed no such improvement that was obvious,
compared to the sets around it. The reason that I questioned what controls
for picture setup are available on this particular set, was that given that
the backlighting is formed by RGB LED arrays, not white LEDs, then the
overall colour temperature would in theory be adjustable - sort of a grey
scale adjustment for LCDs, if you like.

Is there really such a thing as a white LED? The ones I have seen have all
been red/green/blue LEDS on the same substrate to produce what appears to
the eye as a white beam, most of which are far too blue for my taste.

They are blue because blue LEDs have a much shorter life than red and green
so the color will change as they age, and they start out blue before the end up
a red green mix (yellow/orange).


If this was the case, it might be
accessible to the customer via the standard controls menu, as something like
"tint" or "hue", and the reason that this particular set (they only had the
one on display) did not seem to produce good flesh tones compared to the
sets around it, might be because some sales erk had been playing with the
controls to see if he could 'improve' it ...

That may be a different story because PAL TV sets never had them. NTSC
sets needed them because the phase of the color carrier wandered and
often shifted to the green, while PAL sets reset the phase each line and
therefore were always "correct".

Since the chroma signal of an MPEG encoded TV signal does not pass through
a phase encoder unless you connect a composite or RF monitor, it seems
unlikely any sets would have them. More likely, ones sold to people who
are used to PAL over the air signals don't and people used to NTSC ones
do.

Someone - maybe William - commented last week in the original thread, that
they had seen one in Fry's in the U.S., and that they weren't especially
impressed, either.

I have yet to be impressed by an LCD/PLASMA TV. Every single one of them
I have seen is oversaturated and too bright.


Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM