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Edge lit vs back lit LED driven LCDs': What's the big deal other than being thinner?

post #1 of 48
1/2/10 at 7:02am
Thread Starter 
Other than these edge lit LED driven LCD sets are thinner, is there any other advantages?
Do they both have the same power consumption?
Are they more or less prone to hot spotting/flashlight/uneven background levels?

I did look at that now closed thread regarding Samsung Edge lit LCD sets, but other than the thinner part, I didn't read any other differences.
I do know that 'local dimming' is not possible (debatable if that is any issue) and there is cost difference.
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post #2 of 48
1/2/10 at 9:35am
Not sure what yo are asking. The edge lit LEDs produce better blacks than regular LCDs. But the back-lit, local-dimming LEDs are even better (and more expensive). All LCDs/LEDs still suffer with off-angle viewing.
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post #3 of 48
1/2/10 at 2:05pm
+1
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post #4 of 48
1/2/10 at 4:59pm
One difference is that the light from the LEDs are near monochromatic, meaning the red, green and blue colors are very pure. Florescent lighting is broadband meaning the RGB filtering was accomplished purely with the filters on each LCD element. With LEDs there is only the light at the primary wavelengths which decreases the amount of crosstalk. What this leads to is a wider color gamut - deeper saturated colors. That's not really taken to full advantage if one limits the gamut to rec709 (which is recommended).

A second advantage is that LEDs are more power efficient.
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post #5 of 48
1/3/10 at 7:15am
Thread Starter 
Quote:
Not sure what yo are asking.

Quote:
What's the big deal other than they are thinner?

I don't know how much clearer I can ask this? Is that the only difference, the thickness of the panel?
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The edge lit LEDs produce better blacks than regular LCDs'.

Better than back lit (w/o local dimming)??
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One difference is that the light from the LEDs are near monochromatic, meaning the red, green and blue colors are very pure.

Understood, but back and edge lit sets use white LEDs' don't they? How could they use a tri-colored arrangement other than those monster stadium sized displays that use LEDs' for the actual pixel elements?
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Florescent lighting is broadband meaning the RGB filtering was accomplished purely with the filters on each LCD element.

Then the actual panel of a LED driven set is different than a panel for a CCFL diver display?
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A second advantage is that LEDs are more power efficient.

But, are edge lit sets more efficient than back lit?
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post #6 of 48
1/3/10 at 11:03am
All LCD panels are backlit and there are three principal ways to do this that I am aware of.
1. Use close coupled floursant lighting(CCFL) directly behind the LCD panel
2. Use LEDs mounted on the edges of the screen to uniformly provide backlighting to all of the LCD panel.
3. Use local dimmng LED lighting direcly behind the LCD panel and control the amount of backlighting in each local zone so as to maximize the zones contrast.

The best method for both maximizing contrast and reducing power consumption is with local dimming and the CCFL method uses the most power and provides the poorest contrast.
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post #7 of 48
1/4/10 at 5:10am
Thread Starter 
Quote:


maximizing contrast and reducing power consumption is with local dimming

If you don't mind halos around high contrast objects, namely text; as in credits, titles, CC, etc. Helps one problem (looks good on paper), but creates another.

After reading a few reviews of LCD sets, the drawback with edge lit sets is poorer viewing angle. Blacks become grayish, whites become grayish. Apparently, it's even worse than CCFL LCD sets over DLP RPTVs' and Plasmas'.
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post #8 of 48
1/4/10 at 10:49am
My xbr5 is three years old,i don't see a revolutionary better lcd on the market
right now.
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post #9 of 48
1/4/10 at 11:01am
Quote:
Originally Posted by walford View Post

The best method for both maximizing contrast and reducing power consumption is with local dimming and the CCFL method uses the most power and provides the poorest contrast.

CCFL is inferior to the current direct-LED approach, but it's superior to the current Edge-LED approach.

And direct-LED doesn't improve the CR over-CCFL unless something is applied between backlight and the LCD layer.
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post #10 of 48
1/4/10 at 11:18am
Quote:
Originally Posted by videobruce View Post

Other than these edge lit LED driven LCD sets are thinner, is there any other advantages?

They have several advantages:

1. Slimmer profile means manufactures can cut cost in production, transportation and storage.
2. CCFLs suffer from power-up and shutdown latency, which is negligible on LEDs. So backlight strobing can be implemented accurately to reduce hold-time thus improving motion resolution.
3. LED helps to eliminate CCFL trailing.
4. Direct-LED approach can be used to achieve below 0.01cmd2
5. Certain type of filtration can be applied to the LGP to improve the black level of direct-LED systems
6. LED emits less heat, which may improve the life of the unit

and so on...


Quote:
Originally Posted by videobruce View Post

Do they both have the same power consumption?

Yes

Quote:
Originally Posted by videobruce View Post

Are they more or less prone to hot spotting/flashlight/uneven background levels?

I would say about the same.

ATM, edge-LED systems suffer from uneven luminance. The new Philips LCD supposedly matches the KURO in terms of black level performance (when viewed directly). However, I doubt it has the same level of uniformity as the KURO.

http://www.flatpanelshd.com/review.p...&id=1236858201
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post #11 of 48
1/5/10 at 5:58am
Thread Starter 
Quote:
1. Slimmer profile means manufactures can cut cost in production, transportation and storage.

For cutting cost; maybe For transportation; probably since they are lighter. And for storage; maybe. When I saw the box a friends plasma came in, I thought it was a RPTV. The size of the box was only a few inches less in depth. I could almost get my RPTV in his box.
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2. CCFLs suffer from power-up and shutdown latency, which is negligible on LEDs. So backlight strobing can be implemented accurately to reduce hold-time thus improving motion resolution.
3. LED helps to eliminate CCFL trailing.
6. LED emits less heat, which may improve the life of the unit

None of that addressed the question of back vs edge lit LED, only CCFL vs LED which the thread is not about.
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5. Certain type of filtration can be applied to the LGP to improve the black level of direct-LED systems

LGP???
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ATM, edge-LED systems suffer from uneven luminance.

ATM??? Doing some on line banking?
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post #12 of 48
1/5/10 at 6:07am
Thread Starter 
How's this for a list;

Edge lit LED driven LCD displays;
Pros;
1. Thinner panel (AFAIC it's the only selling point. Just another 'con', they still stick out from a wall),
2. Less weight.

Cons;
1. More expensive,
2. Local dimming can't be used,
3. Uneven brightness (brighter towards the corners),
4. Even narrower viewing angle (if LCDs' already have enough of a issue here).
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post #13 of 48
1/5/10 at 6:15am
There is a thread in the LCD forum where LG has announced an edge-lit led with local dimming for 2010. Might be better to wait if you're still undecided.
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post #14 of 48
1/5/10 at 8:08am
Quote:
Originally Posted by videobruce View Post

How's this for a list;
Cons;
2. Local dimming can't be used,

Local dimming systems for edge-lit LED-LCD are under development.
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post #15 of 48
1/5/10 at 8:59am
Quote:
Originally Posted by videobruce View Post

None of that addressed the question of back vs edge lit LED, only CCFL vs LED which the thread is not about.

I've included all there and I don't see the problem of mentioning CCFL. After all, the LG L8000 series is powered by CCFL and has similar profile compared to its older brother.

http://www.avforums.com/forums/lcd-l...000-l9000.html


Quote:
Originally Posted by videobruce View Post

LGP???

Short for Light Guide Plate

Quote:
Originally Posted by videobruce View Post

ATM??? Doing some on line banking?

?
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post #16 of 48
1/5/10 at 9:01am
Quote:
Originally Posted by xrox View Post

Local dimming systems for edge-lit LED-LCD are under development.


Samsung should be unveiling their version in few weeks (CES 2010)
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post #17 of 48
1/5/10 at 9:04am
Quote:
Originally Posted by videobruce View Post

Cons;
1. More expensive,

For now yes. But in time, it will become cheap

Quote:
Originally Posted by videobruce View Post

2. Local dimming can't be used,

Not true


Quote:
Originally Posted by videobruce View Post

3. Uneven brightness (brighter towards the corners),

That's due to the current LGP tech. Future LGP technology may help to eliminate the issue.


Quote:
Originally Posted by videobruce View Post

4. Even narrower viewing angle (if LCDs' already have enough of a issue here).

We do not know if that is due to the higher operating frequency of the panel or because of the current LGP.

But what I can tell you is that the 46B750 also has narrow viewing angles.
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post #18 of 48
1/5/10 at 9:33am
Thread Starter 
Quote:


Local dimming systems for edge-lit LED-LCD are under development.

And so are OLED's. I was discussing what is here now, not 6 months from now (first on the block' technology; i.e.; unproven).
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I don't see the problem of mentioning CCFL

Because the thread is about LED lighting, not CCFL.
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But what I can tell you is that the 46B750 also has narrow viewing angles.

I'm going by the reviews of some of these Edge Lit LCD sets where the reviewer talks about a narrower viewing angle over the back lit models.
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post #19 of 48
1/5/10 at 9:48am
Why no love for the CCFL? It is our friend and we must never forget it.

When you are alone in a dark room (depressed and wondering when the world is coming to an end), who is there to light the LCD and provide hours of empty joy?
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post #20 of 48
1/5/10 at 9:59am
Thread Starter 
Quote:


Why no love for the CCFL?

Power hog. LED driven sets pretty much remove LCD sets from the power hog list (i.e.: Plasma).
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post #21 of 48
1/5/10 at 10:00am
Yes, it take a little more juice, but it has served as well for the past 30-40 years


PS: Plasma make its up providing superior image. By plasma, I means the Neo-PDP and KURO.
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post #22 of 48
1/5/10 at 7:17pm
Is it a safe statement to say that a mid range EDGE LIT LED LCD will provide a better picture than a high end CCFL set, or is it to general of a statement?


Also, based on the comments here I'm guessing Plasma TV's use a lot of energy?
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post #23 of 48
1/6/10 at 5:41am
Quote:
Originally Posted by Justin89t View Post

Is it a safe statement to say that a mid range EDGE LIT LED LCD will provide a better picture than a high end CCFL set, or is it to general of a statement?

No

CCFL still has the upper hand. But that may change this year.


Quote:
Originally Posted by Justin89t View Post

Also, based on the comments here I'm guessing Plasma TV's use a lot of energy?

If you compare using static white, yes.

But on average, it's not that high
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post #24 of 48
1/6/10 at 5:48am
Quote:
Originally Posted by Justin89t View Post

Also, based on the comments here I'm guessing Plasma TV's use a lot of energy?

They typically use more than an LCD. However it's not a lot, and any talk you hear using terms like "power hogs" and "space heaters" is overblown nonsense. The difference between an LCD and a plasma is about as much as a couple light bulbs. I do not believe there's much of a return on investment in electricity savings given the increased cost/area of an LCD.

jeff
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post #25 of 48
1/6/10 at 6:25am
Thread Starter 
Quote:
Is it a safe statement to say that a mid range EDGE LIT LED LCD will provide a better picture than a high end CCFL set

Read the previous negatives.
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terms like "power hogs" and "space heaters" is overblown nonsense

Those terms are NOT overblown and they sure aren't nonsense!
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The difference between an LCD and a plasma is about as much as a couple light bulbs.

Apparently you haven't compared LED driven LCDs' with Plasmas'.
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post #26 of 48
1/6/10 at 6:51am
Quote:
Originally Posted by Nielo TM View Post

CCFL is inferior to the current direct-LED approach, but it's superior to the current Edge-LED approach.

And direct-LED doesn't improve the CR over-CCFL unless something is applied between backlight and the LCD layer.

direct backlit local dimming LED is far superior to CCFL in contrast ratio, as the separate areas of the screen can be dimmed or turned completely off while another area can be extremely bright at the same time. CCFL is better than edgelit LED IMO, but far inferior to local dimming LED. With a GOOD local dimming set, the only blooming that will be noticed will be during credits or names on a black screen, and you can always turn down the backlight a bit if it bugs you. But you won't see much blooming (if any) during regular content.
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post #27 of 48
1/6/10 at 7:41am
Oh God, this has been gone over ad nauseum but I must. I don't know how I can refute powerful assertions made in bold ALL CAPS italics, but I will try, with some data and logic.

The smallest electric space heater you can buy uses 1,500 watts. A typical 50" plasma uses 250-325 watts per CNet and Crutchfield. So, despite the fact that these sets use 5 to 6 times less energy (and thus produce 5 to 6 times less heat) than an actual space heater, it's not nonsense to equate them? I'm all for good metaphors but they should at least make sense.

As for the difference with LCD, a typical CCFL 52" set uses in the 130-180 watt range. LEDs look to use 100-130 watts.

As I said, the plasmas generally use more power. No shock or argument there. The question is, how much more and what's the consequence? Looks to me like it's about 100-150 watts more than CCFL and 150-200 watts more than LED. 100 watts is a common, medium brightness light bulb size. ergo, my comment that the difference amounts to a couple of light bulb's worth.

But you're going to save a lot of money on electricity with that LED set right? Let's say you use it 8 hours a day and pay 10 cents per kW-hr. At 200 watts less than the plasma, you'll save $58 a year - less than $5 a month.

But, you have to pay a lot more upfront for those savings. Using the G10 and UN6000 for comparison's sake, it looks like the LED will run you an extra $750 for a 46" and $900 for a 55". Your ROI window is 13+ years!

jeff
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post #28 of 48
1/6/10 at 9:13am
Thread Starter 
Quote:


But you won't see much blooming (if any) during regular content.

Depending on how critical you are. Your statement is flawed without the word "may". No different than saying if one will see rainbows when viewing a DLP set. I use to when I was looking for them, but it's rare that I see them now.
Quote:


Your ROI window is 13+ years!

With a handle with the word "green" in it, I would expect something different than the "bottom line". There is far more than the dollar saving to the customer. You are missing the big picture.
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post #29 of 48
1/6/10 at 9:22am
Quote:
Originally Posted by greenjp View Post

Oh God, this has been gone over ad nauseum but I must. I don't know how I can refute powerful assertions made in bold ALL CAPS italics, but I will try, with some data and logic.

The smallest electric space heater you can buy uses 1,500 watts. A typical 50" plasma uses 250-325 watts per CNet and Crutchfield. So, despite the fact that these sets use 5 to 6 times less energy (and thus produce 5 to 6 times less heat) than an actual space heater, it's not nonsense to equate them? I'm all for good metaphors but they should at least make sense.

As for the difference with LCD, a typical CCFL 52" set uses in the 130-180 watt range. LEDs look to use 100-130 watts.

As I said, the plasmas generally use more power. No shock or argument there. The question is, how much more and what's the consequence? Looks to me like it's about 100-150 watts more than CCFL and 150-200 watts more than LED. 100 watts is a common, medium brightness light bulb size. ergo, my comment that the difference amounts to a couple of light bulb's worth.

But you're going to save a lot of money on electricity with that LED set right? Let's say you use it 8 hours a day and pay 10 cents per kW-hr. At 200 watts less than the plasma, you'll save $58 a year - less than $5 a month.

But, you have to pay a lot more upfront for those savings. Using the G10 and UN6000 for comparison's sake, it looks like the LED will run you an extra $750 for a 46" and $900 for a 55". Your ROI window is 13+ years!

jeff


I agree that the power difference is non-important when a person is paying over $1000 (or much much more) for a TV. If it's only going to be $100 or less a year, that's less than $10 a month. pretty small in comparison to the price of the TV/programming fees/movie rentals/purchases. If i liked TV-A over TV-B but it would cost me another $75 a year, i would still get TV-A.
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post #30 of 48
1/6/10 at 9:38am
Quote:
Originally Posted by videobruce View Post

With a handle with the word "green" in it, I would expect something different than the "bottom line". There is far more than the dollar saving to the customer. You are missing the big picture.

Alas, the green in my username has nothing to do with environmentalism.

Anyway, I agree with you, and if a particular consumer values the extra "greenness" of the lower power consuming LED, then by all means factor that into the decision.

However, I'd suggest that self-congratulations and waving the green banner because you chose LED over plasma when buying a new television set (that let's face it you don't really need) that was manufactured overseas (by lower-paid workers) and transported across the ocean to your house (on ships that burn heavy fuel oil) is meaningless window dressing.

I'm not trying to poo-poo energy saving or environment-concious actions or anything. I've got CFLs in my house, my wife and I just bought a 4 cylinder stick shift Accord instead of a V6 auto (I figure we'll use 1,000 gallons less gas over it's life), blah blah blah. Just pointing out that in the "big picture" what TV you choose has a miniscule impact on your enviro footprint.

jeff
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