Bit of a con, really ... ?

[Arfa Daily]

Just had one of those weekly e-ads from a local department store that we use
sometimes, trumpeting the latest "Ultraslim LED TV" from Samsung.

Ha! I thought. I haven't heard anything about this. Is it OLED ? At sizes up
to over 50", that didn't seem likely, so I followed the links to see what it
was all about.

Seems that these sets still actually have an LCD display panel, but the
*backlighting* is LED ...

OK, so I can see that there are advantages size-wise - these things are
only 32mm thick - and also power consumption savings, as we all know that
flourescent tube backlighting is very inefficient, but is it right to
actually call these "LED TVs" ? Seems like a bit of a deliberately
misleading use of the terminology to me - or is it maybe just me being a
picky grumpy old sod ? d:~)

Arfa

 

[Tim S]

Arfa Daily coughed up some electrons that declared:

Just had one of those weekly e-ads from a local department store that we
use sometimes, trumpeting the latest "Ultraslim LED TV" from Samsung.

Ha! I thought. I haven't heard anything about this. Is it OLED ? At sizes
up to over 50", that didn't seem likely, so I followed the links to see
what it was all about.

Seems that these sets still actually have an LCD display panel, but the
*backlighting* is LED ...

OK, so I can see that there are advantages size-wise - these things are
only 32mm thick - and also power consumption savings, as we all know that
flourescent tube backlighting is very inefficient, but is it right to
actually call these "LED TVs" ? Seems like a bit of a deliberately
misleading use of the terminology to me - or is it maybe just me being a
picky grumpy old sod ? d:~)

Arfa

This by any chance?

http://www.ebuyer.com/product/162377

Drop a line to Trading Standards for mis-description.

I agree - "LED TV means the primary display is LED, not LED backlit LCD".
There's a world of difference and calling an LCD and LED is clearly
designed to misrepresent the product as something it's not.

I'll have an LED TV when they become cheap/big enough

Cheers

Tim

 

[Tim S]

Arfa Daily coughed up some electrons that declared:

Just had one of those weekly e-ads from a local department store that we
use sometimes, trumpeting the latest "Ultraslim LED TV" from Samsung.

Ha! I thought. I haven't heard anything about this. Is it OLED ? At sizes
up to over 50", that didn't seem likely, so I followed the links to see
what it was all about.

Seems that these sets still actually have an LCD display panel, but the
*backlighting* is LED ...

OK, so I can see that there are advantages size-wise - these things are
only 32mm thick - and also power consumption savings, as we all know that
flourescent tube backlighting is very inefficient, but is it right to
actually call these "LED TVs" ? Seems like a bit of a deliberately
misleading use of the terminology to me - or is it maybe just me being a
picky grumpy old sod ? d:~)

Arfa

This is more descriptive, though the tile seems misleading:

http://www.comet.co.uk/shopcomet/advice/640/Samsung-7series

The bit about turning backlights on and off selectively to enhance blacks is
fair enough - a genuine advancement. But it's still not an LED TV, it's and
LED enhanced (or "intelligent LED backlight") LCD TV.

Here's what Samsung say:

http://www.samsung.com/uk/consumer/detail/detail.do?group=television&type=television&subtype=ledtv&model_cd=UE40B7020WWXXU&pid=uk_home_c1r2contents_series7

They seem to be rather overplaying the LED card, mentioning "single seamless
crystal" (I thought LCD meant Liquid Crystal)

And here's what TheRegister says:

http://www.reghardware.co.uk/2009/01/26/review_lcd_tv_samsung_le40a786/

That seems to get to the point. The LED arrays are not pixel resolution.

All rather fuzzy...

They should just be honest and say "Smart LED lit ultra thin LCD" - I'd
still be impressed.

 

[Dave Plowman (News)]

In article <eKTNl.27690$Ku5.2664@newsfe10.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:

Just had one of those weekly e-ads from a local department store that we
use sometimes, trumpeting the latest "Ultraslim LED TV" from Samsung.

Ha! I thought. I haven't heard anything about this. Is it OLED ? At
sizes up to over 50", that didn't seem likely, so I followed the links
to see what it was all about.

Seems that these sets still actually have an LCD display panel, but the
*backlighting* is LED ...

Yup. There are what can be accurately described as LED TVs on the horizon
- OLED. But are some way off in normal sizes at an affordable cost.

OK, so I can see that there are advantages size-wise - these things
are only 32mm thick - and also power consumption savings, as we all know
that flourescent tube backlighting is very inefficient, but is it right
to actually call these "LED TVs"

Who says fluorescent is inefficient? LED could be better if you could turn
off those in the dark parts of the picture - but no claims for that. Other
problem with LEDs is producing a continuous spectrum smooth white light -
needed to give all the colours from LCD.

? Seems like a bit of a deliberately misleading use of the terminology
to me - or is it maybe just me being a picky grumpy old sod ? d:~)

Might as well claim any TV is LED - if it has an LED warning light. ;-)

--
*Who is this General Failure chap anyway - and why is he reading my HD? *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[JW]

On Mon, 11 May 2009 13:28:06 +0100 "Dave Plowman (News)"
<dave@davenoise.co.uk> wrote in Message id:
<5059c38133dave@davenoise.co.uk>:

Yup. There are what can be accurately described as LED TVs on the horizon
- OLED. But are some way off in normal sizes at an affordable cost.

I took a look at Sony's offering. IIRC it's about 11" diagonally and about
$2500! I downloaded an operators manual, and noticed there were warnings
about screen burn when a steady single image is displayed. Think I'll
stick with my $800 42" LCD.

 

[William Sommerwerck]

I've seen this set at Fry's. It has problems.

The demo apparently was set in "store" mode, with a rather over-bright,
harsh-looking picture.

This set also has frame interpolation (to reduce smear in fast-moving
images), but the unintended result (which I've seen on other sets with
interpolation) is to make films look like video. I don't like it.

This is a fairly expensive set (for its size). I would not recommend it.

 

[Arfa Daily]

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:5059c38133dave@davenoise.co.uk...

In article <eKTNl.27690$Ku5.2664@newsfe10.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:
Just had one of those weekly e-ads from a local department store that we
use sometimes, trumpeting the latest "Ultraslim LED TV" from Samsung.

Ha! I thought. I haven't heard anything about this. Is it OLED ? At
sizes up to over 50", that didn't seem likely, so I followed the links
to see what it was all about.

Seems that these sets still actually have an LCD display panel, but the
*backlighting* is LED ...

Yup. There are what can be accurately described as LED TVs on the horizon
- OLED. But are some way off in normal sizes at an affordable cost.

OK, so I can see that there are advantages size-wise - these things
are only 32mm thick - and also power consumption savings, as we all know
that flourescent tube backlighting is very inefficient, but is it right
to actually call these "LED TVs"

Who says fluorescent is inefficient? LED could be better if you could turn
off those in the dark parts of the picture - but no claims for that. Other
problem with LEDs is producing a continuous spectrum smooth white light -
needed to give all the colours from LCD.

? Seems like a bit of a deliberately misleading use of the terminology
to me - or is it maybe just me being a picky grumpy old sod ? d:~)

Might as well claim any TV is LED - if it has an LED warning light. ;-)

--
*Who is this General Failure chap anyway - and why is he reading my HD? *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

I'm not disputing - not that anyone is suggesting that I am of course -
that this is very possibly a distinct improvement over the existing
backlight technology. I haven't actually seen one 'in the flesh' yet, but I
will look out for one next time I am in JL or Waitrose. I am expecting, as
it is from Sammy, that it will probably be very good. But following up on
Tim's link to "what Samsung say ..." I am very surprised that as a reputable
company, they have made such a deliberate attempt to 'fuzz the edges' on
this, and go out of their way to suggest that it is something other than an
LCD screen.

And as to who says that flourescent backlighting is inefficient - well I do,
actually. I have this morning been mending a bunch of LCD TV power supplies
that I do regularly for a company. They come from a manufacturer that
supplies them to many TV manufacturers for use in their LCD TV sets. The
main - as in biggest, chunkiest and most heatsunk - rail, is without doubt
the 24v one that feeds mostly the backlights. A small amount of power is
also drawn from this rail by the audio output stages, but by far the lion's
share goes to the backlight inverter.

This rail is designed to supply up to 5 amps, and an average sized LCD TV -
say a 28 or 32" - pulls around 4 amps off it to run the backlights. That's
100 watts. An awful lot of power to produce the amount of light that the
tubes do. A considerable amount of that input power goes to losses in the
inverter board, which runs pretty hot, and also to losses in the tubes,
which can get hot enough to be uncomfortable to touch. The LCD TV that I
have on my kitchen wall produces enough heat from the backlights, that you
can feel it on your face, rolling off the front of the screen as you walk
past.

If the LED backlighting that Sammy are using, is as bright or brighter than
the flourescent equivalent, I would be very surprised if it was consuming
more than 20 watts, even with the whole array on.

Arfa

 

[William Sommerwerck]

Who says fluorescent is inefficient? LED could be better if you could
turn off those in the dark parts of the picture -- but no claims for that.

Quite the contrary. Many LED sets use local dimming to improve image
contrast.

Other problem with LEDs is producing a continuous spectrum smooth
white light -- needed to give all the colours from LCD.

The last thing you want is a continuous spectrum.

 

[Man at B&Q]

On May 11, 1:52 pm, JW <n...@dev.null> wrote:

On Mon, 11 May 2009 13:28:06 +0100 "Dave Plowman (News)"
d...@davenoise.co.uk> wrote in Message id:
5059c38133d...@davenoise.co.uk>:

Yup. There are what can be accurately described as LED TVs on the horizon
- OLED. But are some way off in normal sizes at an affordable cost.

I took a look at Sony's offering. IIRC it's about 11" diagonally and about
$2500! I downloaded an operators manual, and noticed there were warnings
about screen burn when a steady single image is displayed. Think I'll
stick with my $800 42" LCD.

It was crap in all respects and ended up being sold off in bargain
basement stores.

MBQ

 

[Jeff Liebermann]

On Mon, 11 May 2009 12:12:08 +0100, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

...but is it right to
actually call these "LED TVs" ? Seems like a bit of a deliberately
misleading use of the terminology to me - or is it maybe just me being a
picky grumpy old sod ? d:~)

Sure. You've just been LED astray.
(Sorry, I couldn't resist).

I notice that Samsung's web pile conveniently does NOT mention
anything about the technology used in their Luxia line of TV's.
They've even dropped the Luxia name, preferring to use "LED TV"
instead. My suspicious mind suggests that this seems intentional.
<http://www.samsung.com/us/productsubtype/led/>

Perhaps it would be helpful to refer to Samsung TV's by their
backlighting. The ordinary LCD panel TV can be known as "CCFL TV".

As for improved efficiency, I'm wondering if that's true. CCFL lamps
belch about 80-100 lumens/watt. Typical white LED's do 10-20
lumens/watt.
<http://en.wikipedia.org/wiki/Light-emitting_diode#Efficiency_and_operational_parameters>
<http://en.wikipedia.org/wiki/Fluorescent_lamp#Luminous_efficacy>
To get the same light output, LED's need to about 4-5 times as much
power. If Samsung used the new and recently demonstrated high
efficiency white LED's, at 100 lumens/watt efficiency, they would at
best be equal to the efficiency of CCFL. Unless my arithmetic is
faulty, an common white LED backlit TV would belch MORE heat than a
CCFL backlit TV for the same brightness. In addition, the smaller
physical size (thickness) of the LED backlit TV leaves less area for
ventilation and conductive cooling. Looking back at the
"specifications" pages, on the Samsung web pile, I don't seem to find
a power consumption figure. Oh-oh....





--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[William Sommerwerck]

As for improved efficiency, I'm wondering if that's true. CCFL lamps
belch about 80-100 lumens/watt. Typical white LED's do 10-20
lumens/watt.

I believe Sony uses RGB LEDs. The R and G should be more efficient.

 

[Dave Plowman (News)]

In article <XAVNl.50634$861.724@newsfe12.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:

And as to who says that flourescent backlighting is inefficient - well I
do, actually. I have this morning been mending a bunch of LCD TV power
supplies that I do regularly for a company. They come from a
manufacturer that supplies them to many TV manufacturers for use in
their LCD TV sets. The main - as in biggest, chunkiest and most
heatsunk - rail, is without doubt the 24v one that feeds mostly the
backlights. A small amount of power is also drawn from this rail by the
audio output stages, but by far the lion's share goes to the backlight
inverter.

And the same will apply to LED backlights. It's a big con that LED are
more efficient - they only are where supplying narrow bandwidth light. As
soon as you try and make them produce continuous spectrum light - ie white
- the efficiency goes way down. Of course they may improve - but then
again so may fluorescent.

--
*Women like silent men; they think they're listening.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[Dave Plowman (News)]

In article <gu99ns$129$1@news.motzarella.org>,
William Sommerwerck <grizzledgeezer@comcast.net> wrote:

Who says fluorescent is inefficient? LED could be better if you could
turn off those in the dark parts of the picture -- but no claims for
that.

Quite the contrary. Many LED sets use local dimming to improve image
contrast.

No claims for that I could see. If it does can only be a good thing as it
could give truer blacks as well - a problem with any backlit device.

Other problem with LEDs is producing a continuous spectrum smooth
white light -- needed to give all the colours from LCD.

The last thing you want is a continuous spectrum.

Eh?

--
*How do they get the deer to cross at that yellow road sign?

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[William Sommerwerck]

And the same will apply to LED backlights. It's a big con that
LEDs are more efficient -- they only are where supplying narrow-
bandwidth light. As soon as you try and make them produce
continuous-spectrum light -- ie white -- the efficiency goes way
down. Of course, they may improve -- but then again, so may
fluorescent.

White LEDs are not continuous-spectrum. They contain a phosphor that
produces yellow light when stimulated by blue light.

 

[Dave Plowman (News)]

In article <gu9njq$opc$1@news.motzarella.org>,
William Sommerwerck <grizzledgeezer@comcast.net> wrote:

And the same will apply to LED backlights. It's a big con that
LEDs are more efficient -- they only are where supplying narrow-
bandwidth light. As soon as you try and make them produce
continuous-spectrum light -- ie white -- the efficiency goes way
down. Of course, they may improve -- but then again, so may
fluorescent.

White LEDs are not continuous-spectrum. They contain a phosphor that
produces yellow light when stimulated by blue light.

Indeed. So not suitable for where you need a decent quality light. As for
an LCD backlight.

--
*Save a tree, eat a beaver*

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[Dave Platt]

In article <5059c38133dave@davenoise.co.uk>,
Dave Plowman (News) <dave@davenoise.co.uk> wrote:

Who says fluorescent is inefficient? LED could be better if you could turn
off those in the dark parts of the picture - but no claims for that.

A video engineer I know, recently told me that some of the new
LED-backed-LCD displays do just that.

If I understand him correctly: these displays use a large matrix of
addressable R/G/B LEDs, with each LED illuminating the back size of a
set of LCD pixels. The actual visual brightness seen by the viewer,
for each individual pixel, depends both on the level of LED
back-illumination for that pixel, and the transparency of the LCD
pixel... both of which can be controlled by the display electronics.

By turning down (or off) the LED which back-illuminates a set of
pixels, the display can generate a *very* "deep black" in that area
when called for... these displays have a much higher maximum contrast
ratio than a traditional CFL-backlit LCD display.

This approach can save power, too, during times of low average screen
brightness.

These aren't OLED displays (which are still expensive for their
size)... the LEDs are of fairly standard inorganic construction.

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[Dave Platt]

In article <5059def3b4dave@davenoise.co.uk>,
Dave Plowman (News) <dave@davenoise.co.uk> wrote:

And the same will apply to LED backlights. It's a big con that LED are
more efficient - they only are where supplying narrow bandwidth light. As
soon as you try and make them produce continuous spectrum light - ie white
- the efficiency goes way down. Of course they may improve - but then
again so may fluorescent.

You're assuming that the designers use LEDs to create
continuous-spectrum light, and then pixel-filter this down to the
R/G/B pixels.

My understanding is that this is *not* what they're doing. Rather,
I'm told that they use a matrix of individual narrow-emission R/G/B
LEDs, which backlight the R/G/B-filtered LCD pixel "shutters".

With proper selection of the R/G/B LED wavelengths (e.g. pick them
with peak output wavelengths close to the peak-optical-sensitivity
wavelengths of the photopigments in the human retina) you ought to be
able to get very good efficiency.

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[Leonard Caillouet]

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:gu99ns$129$1@news.motzarella.org...

Who says fluorescent is inefficient? LED could be better if you could
turn off those in the dark parts of the picture -- but no claims for
that.

Quite the contrary. Many LED sets use local dimming to improve image
contrast.


Other problem with LEDs is producing a continuous spectrum smooth
white light -- needed to give all the colours from LCD.

The last thing you want is a continuous spectrum.

Local is a relative term and the effectiveness of these systems varies
considerably with real video. On/off contrast ratios can be impressive, but
the real test is how it performs with live video.

As for "continuous" spectra, again, it depends. Ideally, for a standard
video matrix decoding typical video, you would want spectra for R, G, & B
that match the CIE standard observer functions. These are what cameras are
designed to output, and what CRTs were more likely to approximate. You have
to account for narrow spectrum in the outputs of displays in the matrix for
the color decoder. Some sets have done a better job of this than others.

Like most technologies, there are caveats and implementation variance that
make some work very well and others less so. The best sets from Samsung and
the Sony look great, but still not as good in terms of blacks on real video
as the best PDPs. The color on the Sony seems more natural than that of the
Samsung to me, but neither are up to the best CRTs nor PDPs, yet. Darned
close, and better than many of the lesser from either technology. Any of
them properly calibrated will likely outperform any of the others out of the
box.

Leonard

 

[Andrew Gabriel]

In article <5059e164f9dave@davenoise.co.uk>,
"Dave Plowman (News)" <dave@davenoise.co.uk> writes:

In article <gu9njq$opc$1@news.motzarella.org>,
William Sommerwerck <grizzledgeezer@comcast.net> wrote:
And the same will apply to LED backlights. It's a big con that
LEDs are more efficient -- they only are where supplying narrow-
bandwidth light. As soon as you try and make them produce
continuous-spectrum light -- ie white -- the efficiency goes way
down. Of course, they may improve -- but then again, so may
fluorescent.

White LEDs are not continuous-spectrum. They contain a phosphor that
produces yellow light when stimulated by blue light.

Indeed. So not suitable for where you need a decent quality light. As for
an LCD backlight.

I don't see why an LCD backlight needs to be anything other than
red green and blue, and having just checked one, that's exactly
what it is -- actually very much narrower bands than a regular
fluorescent, and without any of the other fill-in colours you
get from a fluorescent lamp. After all, anything else from the
backlight would be wasted (or worse, might bleed through into
some colour cells and contaminate the primary additive colours).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

 

[Leonard Caillouet]

"Andrew Gabriel" <andrew@a20> wrote in message
news:4a08778b$0$516$5a6aecb4@news.aaisp.net.uk...

In article <5059e164f9dave@davenoise.co.uk>,
"Dave Plowman (News)" <dave@davenoise.co.uk> writes:
In article <gu9njq$opc$1@news.motzarella.org>,
William Sommerwerck <grizzledgeezer@comcast.net> wrote:
And the same will apply to LED backlights. It's a big con that
LEDs are more efficient -- they only are where supplying narrow-
bandwidth light. As soon as you try and make them produce
continuous-spectrum light -- ie white -- the efficiency goes way
down. Of course, they may improve -- but then again, so may
fluorescent.

White LEDs are not continuous-spectrum. They contain a phosphor that
produces yellow light when stimulated by blue light.

Indeed. So not suitable for where you need a decent quality light. As for
an LCD backlight.

I don't see why an LCD backlight needs to be anything other than
red green and blue, and having just checked one, that's exactly
what it is -- actually very much narrower bands than a regular
fluorescent, and without any of the other fill-in colours you
get from a fluorescent lamp. After all, anything else from the
backlight would be wasted (or worse, might bleed through into
some colour cells and contaminate the primary additive colours).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
Y

That depends on the assumptions you make in the production of the source and
the decoding to those narrow spectrum RGB displays. You may or may not end
up with the same distribution of secondary and intermediate colors. The
human eye perceives color over a spectrum approximated by the CIE standard
observer curves. Concentrating all of the energy at narrow bands can have
some very significant effects, not only in overall brightness, but in color
reproduction. While it is true that any color (within a given gamut) can be
made up of a combination of narrow band RGB display sources, getting the
right spectral power at a given color requires mapping from what the pickup
and encoding assume to what the display can produce. Unfortunately, there
are not many good options for measuring response at colors other than
primaries and secondaries and no good standards for evaluating performance
objectively at this time for intermediate colors, much less for those colors
over a range of luminance values.

Leonard