"LED TVs" - Demistifying the Myths and bringing out the Facts

[sanjay0864]

Due to the misleading marketing by certain companies and the incorrect use of the term "LED TV", most people now a days assume these so called "LED TVs" as the "be all and end all" of televisions. Thus, I think it might be quite useful to many here, to demistify the myths and present the facts about "LED" TVs. The following article from 'CNET', excerpts of which I am reproducing here, does a great job of this --> LED TVs compared: Local dimming, edge-lit, and full array

If you thought all LED TVs were created equal, you're underestimating the power of confusion as a marketing tool. In their continuing efforts to compete against the picture quality advantages of plasma-based flat-panel TVs, makers of LCDs TVs have introduced numerous new technologies. The most successful in our opinion is full-array LED backlighting with local dimming. When you see the words "LED TV" in an ad, it definitely refers to an LCD TV with an LED backlight, but what type of LED backlight and how it's configured make all the difference.

Below we've gathered reviews of six different "LED TVs" that provide examples of all four LED backlight configurations, but first we'll provide a bit of context. All LCD-based TVs rely on a backlight of some kind to illuminate the liquid-crystal panel itself. The most common use fluorescent backlights, known as CCFL, but a growing number feature LED backlights instead. LEDs use somewhat less power, can enable thinner flat-panel cabinets, and--crucially for TV makers--provide a great excuse to charge more money. But make no mistake: despite the misleading marketing, LED TVs are just LCD TVs with fancy backlights.

Unfortunately for TV shoppers, the confusion just increases from there. To help cut through the clutter we're going to lengthen our descriptions beyond the "LED TV" shorthand, and tell you how picture quality generally compares with standard LCD. More details are available in our LED TVs: 10 things you need to know companion piece as well as the individual reviews.

Full-array without local dimming: The rarest of the bunch but the most familiar in concept. These models are just like standard LCD-based TVs aside from the fact that the CCFL backlight is replaced by LEDs. The "full-array" means that the LEDs themselves are arranged behind the entire LCD panel, not just along the edge.
Picture quality impact: No difference compared with standard LCD.

Edge-lit without local dimming: The most common today. Chances are if you see an "LED TV" advertised, it's this variety, which was first widely introduced by Samsung in 2009, then imitated in 2010 by just about everyone else. It's characterized by thin cabinet designs--around just an inch or even less in depth--that lead to decreased weight in shipping and wall-mounting, along with increased bragging rights (although we fail to see much practical appeal versus a standard, 3-to-5-inch-deep flat-panel TV). Unlike full-array models, the LEDs on these sets are arranged only along the edge of the LCD panel, and can illuminate the center and other areas of the screen using so-called "light guides."
Picture quality impact: No major advantage over standard LCD, and can have even more uniformity problems, such as brighter edges compared with the middle.

Full-array with local dimming: The original and still the best. There are exceptions, but in general, TVs with this LED backlight configuration are the best-performing LCDs you can buy. They're similar to full-array models, but the individual zones of LEDs can be dimmed or brightened independently.
Picture quality impact: Can have significantly better black levels and uniformity than normal LCD, but will also exhibit "blooming," or stray illumination, to some extent.

Edge-lit with local dimming: A new innovation for 2010, currently available on select models from Samsung, LG and Sony. The idea is to allow some dimming of the screen in independent areas without having to place LEDs behind the LCD panel, just along the edge.
Picture quality impact: In our tests, the Samsung preformed relatively well and the LG did not, although neither matched the picture quality of full-array with local dimming and both exhibited more blooming.

Disclaimer: The highlighting, bold/italics/underlined, is mine.

Bottom line, don't just rush into buying a so called "LED TV", ie. without first finding out the details of what kind of "LED" array the TV has. Also, do not assume these so called "LED TVs" to be neccesarily better than Plasmas or for that matter, even the regular 'CFL' lit LCD TVs.

 

[bhupinder511]

Good info.....

 

[BLASTO]

Edge-lit with local dimming: A new innovation for 2010, currently available on select models from Samsung, LG and Sony. The idea is to allow some dimming of the screen in independent areas without having to place LEDs behind the LCD panel, just along the edge.

How is this possible?
Can the brightness of the light emerging from the edge be contolled in a different area?

 

[reignofchaos]

pls delete this post. was a duplicate

 

[reignofchaos]

The light guides used for illumination can be turned off by putting some sort of obstruction. This is slightly better than conventional edge lit.

One thing this article fails to mention is the fact that even led backlighting can be of two different types - RGB leds and white leds. The former will perform significantly better than the latter though almost all tv makers use white leds as RGB is significantly. more expensive. The only known RGB led backlighting tvs are the top end philips ones and the sony xbr8

 

[reignofchaos]

Also to add wide color gamut ccfl will perform better than edge lit led in most situations unless the screen is absolutely dark. Edge lit leds will also have significantly worse uniformity in illumination compared to wcg-ccfl.

 

[allajunaki]

You guys forgot to mention another important aspect of LED lit TV's.

Power Consumption. It is significantly lower.

Also, there is no "shift" in colors as exhibited by convention CFL backlit LCD's
(Shift is due to the fact that conventional cfl's normally shift the colour they produce over their lifespan, CFL, as they age, starts producing more and more yellowish white).
LED, as far as I know, don't shift colours.

 

[karmapilots]

So guys if someone is in the market for a 55inch HD TV, what will you guys suggest. LED(if so what back-lit array) or Plasma.

 

[adder]

Edgelits tvs have a significant power consumption difference vs CCFL and quite large difference vs plasma.
Todays 52" size edge led lcds consume less then 60 watt calibrated to around 105 watt at high backlight settings vs a much smaller 42" plasmas which consumes anywhere b/w 190watts average to a peak of 400+ watt.

So the power consumption difference is huge.

 

[longshanks]

The only known RGB led backlighting tvs are the top end philips ones and the sony xbr8

Yeah, looks like Philips are also coming up with LED back lighting from 8 series on for their 2010 line up.

Also the new ambilight looks even more groovy in the new model 9705.

 

[sanjay0864]

Personally I find 'power consumption' to be the least important of all the factors in deciding upon what TV to buy. Picture quality and other features are far more important factors. Quite simply, if it is primarily just cost that we are concerned with, then one should buy the cheapest TV and be done with it. If one wants quality then one must be willing to pay more for it. Somehow i have found that in our country more people are concerned with the running cost compared to the one time initial cost. If a TV consumes less power but costs Rs. 10,000 more initially, I assure you, you will not save Rs. 10,000 even over the life of the TV. By the way, this is not to say that 'power consumption' should not be a consideration, but it should definately not take precedence over other factors such as quality. Personally, I would consider 'power consumption', only as a tie breaker, if after all evaluations I am stuck between deciding two equally good TVs that are also priced similiarly.

Side Note:
I have never understood why so many people, whose driving distance per month is just average, pay a huge premium to buy a 'diesel' car. Most of these people are not even able to recover the 'premium' they paid, over the entire ownership period, specially when the higher cost of maintaining a diesel car is taken into account. Like I said, people in India generally are willing to pay more initially but not recurringly. The same trait can be seen where people will invest huge sums of money in great audio/video equipment, but they will not pay even a little extra for good quality software and instead opt to watch cheap pirated DVDs and listen to free downloaded compressed audio etc. I actually know several people who only watch absolutely crappy pirated DVDs in their Home Theaters worth over 15 - 20 lakhs (even more), simply because they think paying Rs. 100 for an original Blu-ray is way too high, after all they can buy the pirated DVDs for Rs. 30 -40.

 

[reignofchaos]

You guys forgot to mention another important aspect of LED lit TV's.

Power Consumption. It is significantly lower.

Also, there is no "shift" in colors as exhibited by convention CFL backlit LCD's
(Shift is due to the fact that conventional cfl's normally shift the colour they produce over their lifespan, CFL, as they age, starts producing more and more yellowish white).
LED, as far as I know, don't shift colours.

Both of them drift towards yellow with age and LEDs do so slower than ccfls. However neither will show appreciable drift when used for 4-5 years after which the TV will be obsolete anyway.

Power consumption is a valid point - LED backlit TVs have roughly half the power consumption of a CCFL based TV. However someone who worries about picture quality typically doesn't care a rat's rear about power consumption.

 

[allajunaki]

Haha, Right said Sanjay.

Agree with you on that front. However I believe what adder pointed out does have some merit in some circumstances, like when your house is running on inverter. In that case power consumption do play a big role.
But yeah, for normal day to day running, I don't think shelling out a bomb for LED's for the sake of power consumption is not gonna help you much.

 

[adder]

Well is the price premium of EDGE LED lcds justified personally i don't think so if one want to save power bills.
But if one wants to go green then yes.
Also my APC 1000UXI 800watts APC smart ups can't handle a 21" crt which consumes around 70 to 100watts but only during cold start.
Not sure if it can handle a plasma during cold start.
In bangalore with the power cuts during the last few days the UPS could barely get the batteries fully charged,a plasma seriously is a bad choice.if i had a plasma instead of a lcd i would have missed many F1 races or even football matches.

 

[BLASTO]

Well is the price premium of EDGE LED lcds justified personally i don't think so if one want to save power bills.
But if one wants to go green then yes.
Also my APC 1000UXI 800watts APC smart ups can't handle a 21" crt which consumes around 70 to 100watts but only during cold start.
Not sure if it can handle a plasma during cold start.
In bangalore with the power cuts during the last few days the UPS could barely get the batteries fully charged,a plasma seriously is a bad choice.if i had a plasma instead of a lcd i would have missed many F1 races or even football matches.

If you are worried about inverter going poof, Get an LCD. Personally, My plasma works fine with inverter for 1 hour which is the typical time for power cuts in hyderabad.. Not tested beyond this..

LED does not come into picture even in this case. LCD is good enough.

LED IMO is only for bragging.. Really good LEDs which does makes a difference are too costly negating the significance.

 

[adder]

If you are worried about inverter going poof, Get an LCD. Personally, My plasma works fine with inverter for 1 hour which is the typical time for power cuts in hyderabad.. Not tested beyond this..

LED does not come into picture even in this case. LCD is good enough.

LED IMO is only for bragging.. Really good LEDs which does makes a difference are too costly negating the significance.

Well LED are on average twice as efficient compared to CCFL like i said a todays LED are very efficient a 52" calibrated LED lcd can consume less then 60watt .

Again why are you using the term LED,only samsung and lg use the term LED.

OT:Btw does your inverter handle a cold start of your plasma tv i.e switching it on when its in room temperature or when it wasn't used for around hr before.Switching my crt from cold makes the UPS trip ,where as in the lcd no such issues.

 

[borg]

Well LED are on average twice as efficient compared to CCFL like i said a todays LED are very efficient a 52" calibrated LED lcd can consume less then 60watt .

Again why are you using the term LED,only samsung and lg use the term LED.

OT:Btw does your inverter handle a cold start of your plasma tv i.e switching it on when its in room temperature or when it wasn't used for around hr before.Switching my crt from cold makes the UPS trip ,where as in the lcd no such issues.

In CRT there is a degaussing coil which is a virtual short circuit at coldstart,the inrush current at start will be very high for the first few cycles
This makes the UPS trip
plasma or lcd dont have a degaussing coil so that is not an issue ,

 

[anuragn]

LCDs and plasmas have a "soft-start" vs a CRT which has a very high inrush of current during cold starts.
My PV8 plasma is able to cold start on my 800VA invertor.

 

[BLASTO]

OT:Btw does your inverter handle a cold start of your plasma tv i.e switching it on when its in room temperature or when it wasn't used for around hr before.Switching my crt from cold makes the UPS trip ,where as in the lcd no such issues.

No issues cold starting my plasma.. It is connected to a good v-guard stabilzer.. Dont know if it plays any part..

Runs fine for an hour of power cut could run more..

Mine is 42", 50" might run for much lesser time, owners can comment.

 

[sanjay0864]

No issues cold starting my plasma.. It is connected to a good v-guard stabilzer.. Dont know if it plays any part..

Runs fine for an hour of power cut could run more..

Mine is 42", 50" might run for much lesser time, owners can comment.

I have 24hr power backup where I live, so I guess my experience wouldn't count for most people. But in any case, I have absolutely no issues 'cold starting' or running my Samsung 50" plasma. Two people I know closely, have a Panasonic 42" plasma and they have no issues with 'cold starting' their plasma on a APC Back-UPS 1100.