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Introduction
Backlighting, LCD matrix type, resolution, size, efficiency, gamut, response times, input lag, contrast ratios, viewing angles, grey scaling, white saturation, black point, luminance, uniformity, bleeding. All aspects people take, less often then not, when purchasing an LCD. All present their problems discerning exaggerated facts with real world performance. Nothing more so then with contrast and backlighting. The static vs dynamic contrast story has been told countless times and is well documented, but just in case: Static dynamic contrast is what matters.

Backlighting however is an iffy subject mixed with manufacturer specifications, yet no documentation on test methodology, or results on hand or at the very least third party scientific measurements to provide a solid base for comparison.
Contenders

CCFL and LED. The 'old' vs the new. The mature vs the immature.
Just what exactly are the differences, what are the advantages of either? Why were LED's debuted as superior technology in both performance and green?

My search came up with a few conclusions and public mis conceptions but that's later to come.. But first let's begin with LED/CCFL manufacturer specification scandals.
According to manufacturers/public:
LED's are brighter then "typical" backlighting, being CCFL (public opinion I've gathered from forums/customers/public)
LED's offer 25% energy efficiency (manufacturer/public misconception)
LED's have superior life expectancy (manufacturer)

So let's touch each of these subjects in real world performance.
Brightness
Without a doubt LED's can provide more brightness if high quality LED's/enough LED units/ and enough power is supplied. Then again the same can be said about CCFL, increase CCFL numbers and quality and you can get a very bright panel. In both real world/manufacturer specifications they remain the same in LCD's, but why is it that the public sees LED's as being brighter? There's only one word to describe this: LCD monitor quality. Some perform to specifications (luminance specified) while most don't.
They likely saw a bad quality CCFL and saw a better quality LED and made the error to take that comparison to be the final verdict on LED/CCFL

Verdict: LED and CCFL offer same luminance in LCD's depending on quality of LCD as whole.

Power Consumption

This is without a doubt the iffiest subject in LED vs CCFL scenarios. Manufacturers claim 25% energy efficiency over typical* backlighting. The vastly common type of backlighting for LCD's is CCFL.

First the public misconception. I hear people all the time say LED's are more efficient then CCFL, and say it as a fact. Yet when I ask them for documentation for it, they fall way short.
I think the reason why manufacturer's 25% energy efficiency claim go unquestioned in the publics eye is because they fail to realize what backlighting is used in LCD's to begin with, even if they knew the name they would know little to nothing about the technology, cold cathode fluorescent lamp.
So when manufacturers come around claiming energy efficiency, people think "maybe they're talking incandescent light bulbs." Incandescent light bulbs, as you probably know, are the bulbs most used in your house. They are inefficient and run incredibly hot. There are alternatives to incandescents but they're costly, and they come in the name of CFL or compact fluorescent bulb. They are highly effiecient providing similar or better luminance then incandescent by far. 8w CFL is comparable to a 40w incandescent. 25-45w CFL is comparable to a 150w incandescent.


So of course when the public thinks of lighting they think incandescent, the most common form of lighting in houses. So when they hear LED's are superior in power efficiency in LCD's compared to "typical backlighting", they go without questioning it because it makes sense for them.

Next is manufacturer claims.
This is were it gets iffy. I could find no scientific paper comparing CCFL/LED's in LCD study by manufacturers nor third parties. I did however find an article by Alfred Poor regarding LED/CCFL usage in laptops.
Found here.
Overall when I researched I found:
CCFL's offer greater efficiency to CFL nearly 50% more efficacy.
LED's offer great efficiency too however no numbers have been produce in LCD usage.
In comparison there are experts giving the edge to LEDs, others to CCFL. There is no clear cut line. Apparently quality is what matters in the end.
In the end the biggest issue found is with CCFL's electrical requirements, needing high voltage (5v-48v) and low amperage which requires inverters/complex power supplies to allow for dimming. LED's on the other hand do not require inverters since they can [email protected] 12 or 24 Vdct and do not require complex power supplies.


Verdict: So in the end power consumption efficiency is unknown.

Lastly, Life expectancy

This is still an iffy subject but finally some light was shed when I did more research. I found something incredible. LED's offer the same life expectancy then CCFL's for the most part in LCDs. Keep in mind these life expectancies are for different applications not just LCD's, although I did manage to get some numbers)
CCFL life expectancy: 8,000-100,000 (25,000-75,000 appear to be common life expectancy in LCD's, I found no reference to 100,000 hour CCFL's used in LCD's)
LED Life expectancy (Dependant on color): 25,000-100,000 (50,000 hours is the common life expectancy in most applications** I found no reference to 100,000 hour LED's used in LCD's just claims that LED's "can" have life expectancy of 100,000 hours)
Keep in mind however LED's are subject to failing from heat, while CCFL do not.

**However life expectancy ranges from white, red, blue, etc. Red has the worst life expectancy, just how much worse I could not find however most sources say it's substantially worse.

Verdict: This is a very complex verdict. While I was able to pull up numbers I also found a lot of sources' resentment to LED manufacturers with their documentation/claims. Most criticized them for not:
* Specifying when the LED was considered dead (efficiency loss)- This is a major factor in expectancy. A few manufacturers answered claiming at 50% luminance loss was the LED considered "dead". The results showed 50,000 20,000 hours *I misread*. It would appear life expectancy varies greatly from manufacturer to manufacturer, its apparent to sources that luminance loss percentage was going to vary.
* Specifying LED's used (White, red, etc)
* At least publishing documentation etc. So far no publication

Sources:

http://www.eetindia.co.in/ART_880048...T_20be8751.HTM
http://www.instrumentsystems.com/fil...ystems_web.pdf
http://ca.news.finance.yahoo.com/s/2...s-proving.html
http://www.dominion.net.au/files/doc...20Brochure.pdf
*Others remain, however are pay for publications*
 

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good info. This will hopefully clear some things up for people.

+rep for making it an easy read.
 

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Nice read. Learned something new
 

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Quote:

Originally Posted by AsAnAtheist View Post
They likely saw a bad quality CCFL and saw a better quality LED and made the error to take that comparison to be the final verdict on LED/CCFL.
If a bad quality CCFL costs the same as a better quality LED, wouldn't the LED be the better choice?
 

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Discussion Starter #6
Quote:

Originally Posted by Tempest001 View Post
If a bad quality CCFL costs the same as a better quality LED, wouldn't the LED be the better choice?
Not really. CCFL/LED costs are just about negligible. Perhaps back in 2008-2009 that may have been the case, but in those times LED TV or LED LCD's were hella more expensive due to tiny supply.
Edit: if anything at all LED's have always had a premium cost and never served up premium performance.

Quote:

Originally Posted by Trogdor View Post
Nice write-up.

Proof read one more time, see if you can find qualified sources and this is stickyable.
Thats my problem. Finding qualified sources is getting to be a nightmare. I been using my colleges' pay to use search engine I still can't even find anything on LED in LCD's..
I could list sources I have found which are mostly articles written by authors that list other specialists. I suppose I will put the sources list anyways, let me compile the data.
 

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There are still benefits to LED backlighting. First of all, the weight and size of LED backlit LCD's is nice, especially when mounting and managing multiple monitors.
Also, contrast ratios tend to be better with LED backlit monitors.
When talking about white LEDs vs. CCFL it really depends on the specific lamps being used.
 

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Discussion Starter #8
Quote:

Originally Posted by Mygaffer View Post
There are still benefits to LED backlighting. First of all, the weight and size of LED backlit LCD's is nice, especially when mounting and managing multiple monitors.
Also, contrast ratios tend to be better with LED backlit monitors.
When talking about white LEDs vs. CCFL it really depends on the specific lamps being used.
Thinness/weight are the only upsides to LED's but they come at a price (LED edge lit which is comparably worse then edge lit CCFL as LED's are directional in their light)

Contrast ratios are not better then CCFL. They're the typical 1000:1 with bloated dynamic contrast ratios, same as CCFL.

Just about specific case by case.
 

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A couple of points....

* You can look at power consumption of recent CCFL and LED displays. You will notice that LED use less power.
* There are different types of LED and arrangements... edge-lit, back-lit, RGB LEDs.
* No mention of color reproduction?
 

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Discussion Starter #12
Quote:


Originally Posted by DuckieHo
View Post

A couple of points....

* You can look at power consumption of recent CCFL and LED displays. You will notice that LED use less power.
* There are different types of LED and arrangements... edge-lit, back-lit, RGB LEDs.
* No mention of color reproduction?

* Oh I'v seen power consumption differences. 21.5", 23", 24" 20", etc I found the power consumptions to be incredibly the same. I found the energy efficiency differences can be attributed to higher and lower quality power supplies used in monitors. My 21.5" EIPS utilizes 23w measured by a kill-a-watt, I can't find a comparable LED LCD panel with near power consumption..
* Yes Edge-lit, full array, RGB LED
* My argument was more on the backlighting misconceptions not so much on differences found already by reviewers/others.
 
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