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Led backlight lcd monitor

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July 1, 2011 8:19:35 PM

Hello, what is the difference between LCD screen and an led back-light LCD ?
July 1, 2011 8:23:11 PM

Usually better and more consistent lighting. With a regular blacklight there's a centralized bulb and the corners usually get less light and are darker. The LED backlight monitor should be consistently bright regardless of the place on the screen you look.
a b à CPUs
July 2, 2011 1:55:30 AM

CHeck out this article
can explain it better
http://www.tomshardware.com/reviews/ccfl-led-backlight,...

to quote
"LEDs definitely look more dramatic. The blacks are deeper, the whites brighter, and the colors more vibrant. At the same time, we found LEDs more prone to skewing toward a given color and needing more calibration in order to remedy this. CCFL displays often look semi-lifeless when sitting next to an LED, but their colors appear more photo-realistic. CCFL definitely renders more detail in shadows because the blacks haven’t been pushed down as strongly. Yes, sometimes the measurement data contradicts this, but we’re going by side-by-side visual comparisons, and it’s important to weigh both.

Ultimately, we’d pick LED for media consumption, but we’d pick CCFL for editing work where detail and accuracy are paramount. LED is more fun to watch; CCFL is more reliable"

that is from experts in the field
Related resources
a c 471 à CPUs
July 2, 2011 5:21:58 AM

browsingtheworld said:
Usually better and more consistent lighting. With a regular blacklight there's a centralized bulb and the corners usually get less light and are darker. The LED backlight monitor should be consistently bright regardless of the place on the screen you look.


Consumer level LCD monitors using LED (a.k.a. WLED) backlight are all edge lit. LCD monitors using CCFL (florescent) backlight are all full arrays. That means the florescent lamp spans from on side of the monitor to the other. Cheap LCD monitors with CCFL uses as few as two florescent lamps. Large, expensive LCD monitors with CCFL can use as many as 6 lamps to the best of my knowledge.

LED backlight does not provide more consistent lighting because of the fact they are all edge lit. The light is emitted sideways in the monitor to a reflective material which reflects the light to the viewer(s). There is a greater can of light bleeding around the edge of the monitor because that's where the light is emitted.

Monitors with CCLF backlight can have better backlight consistence simply because of the fact it is a full array.

Additionally, WLED does not actually produce a white backlight. It uses blue LEDs with a yellow phosphorous coating to imitate white. Sometimes it produces slightly bluish colors. Some people may notice it, other don't.

Below is the a backlight uniformity luminance measurement of the BenQ XL2410T which is a 120Hz monitor with LED backlight. It is not bad, but it is no where near perfect either:



The review of that monitor can be found below:

http://www.tftcentral.co.uk/reviews/benq_xl2410t.htm
a c 471 à CPUs
July 2, 2011 5:34:04 AM

As a comparison here is the backlight uniformity luminance measurement of the popular Dell U2410 which uses CCFL backlight.



Again, it is not perfect, but better than the BenQ XL2410T.

Review:
http://www.tftcentral.co.uk/reviews/dell_u2410.htm


The NEC PA271W probably has the best backlight uniformity luminance measurement that I have ever seen. However, it is priced out of most people's budget since it is geared towards graphics professionals. It also uses CCFL backlight.



Review:
http://www.tftcentral.co.uk/reviews/nec_pa271w.htm


a b à CPUs
July 2, 2011 5:52:48 AM

^+10 Jag
Nice work :) 
July 2, 2011 10:12:07 AM

jaguarskx said:
Consumer level LCD monitors using LED (a.k.a. WLED) backlight are all edge lit. LCD monitors using CCFL (florescent) backlight are all full arrays. That means the florescent lamp spans from on side of the monitor to the other. Cheap LCD monitors with CCFL uses as few as two florescent lamps. Large, expensive LCD monitors with CCFL can use as many as 6 lamps to the best of my knowledge.

LED backlight does not provide more consistent lighting because of the fact they are all edge lit. The light is emitted sideways in the monitor to a reflective material which reflects the light to the viewer(s). There is a greater can of light bleeding around the edge of the monitor because that's where the light is emitted.

Monitors with CCLF backlight can have better backlight consistence simply because of the fact it is a full array.

Additionally, WLED does not actually produce a white backlight. It uses blue LEDs with a yellow phosphorous coating to imitate white. Sometimes it produces slightly bluish colors. Some people may notice it, other don't.

Below is the a backlight uniformity luminance measurement of the BenQ XL2410T which is a 120Hz monitor with LED backlight. It is not bad, but it is no where near perfect either:

http://www.tftcentral.co.uk/images/benq_xl2410t/panel_uniformity.jpg

The review of that monitor can be found below:

http://www.tftcentral.co.uk/reviews/benq_xl2410t.htm


jaguarskx said:
As a comparison here is the backlight uniformity luminance measurement of the popular Dell U2410 which uses CCFL backlight.

http://www.tftcentral.co.uk/images/dell_u2410/panel_uniformity.jpg

Again, it is not perfect, but better than the BenQ XL2410T.

Review:
http://www.tftcentral.co.uk/reviews/dell_u2410.htm


The NEC PA271W probably has the best backlight uniformity luminance measurement that I have ever seen. However, it is priced out of most people's budget since it is geared towards graphics professionals. It also uses CCFL backlight.

http://www.tftcentral.co.uk/images/nec_pa271w/uniformity_2.jpg

Review:
http://www.tftcentral.co.uk/reviews/nec_pa271w.htm


Why are you comparing an IPS monitor that costs GBP150 more with a 120hz gaming monitor where some of the manufacturing cost was obviously spent on the refresh rate? Why are you bringing up a $1300 IPS monitor as a third example?

The article on the same website you are linking your reviews from has this to say:
Quote:
Uniformity - Most desktop monitors use edge-lit W-LED backlighting with a line of LEDs along the edge of the panel. The whole screen is lit by means of a special diffuser, and so it is this which really determines the brightness uniformity you experience. The uniformity of brightness depends only on the design of the diffuser and you can often see various defects like bright spots or a brighter zone at the edge of the screen where the lamp or the line of LEDs resides. Having an LED backlight does not guarantee you better uniformity. In fact, good uniformity is harder to achieve in the long term as the LEDs age, with each LED possibly aging at a different rate. With RGB LED units, the use of three separate light sources for red, green, and blue means that the white point / colour temperature of the display can move as the LEDs age at different rates as well.

http://www.tftcentral.co.uk/articles/led_backlighting.h...

Like I said, LED monitors usually has better and more consistent lighting.
a c 471 à CPUs
July 2, 2011 3:10:24 PM

browsingtheworld said:
Why are you comparing an IPS monitor that costs GBP150 more with a 120hz gaming monitor where some of the manufacturing cost was obviously spent on the refresh rate? Why are you bringing up a $1300 IPS monitor as a third example?



This is a discussion about backlighting which is separate from LCD panel technologies.

LED (WLED) does not offer better backlight compared to traditional CCFL. The Dell U2410 is popular and relatively affordable H-IPS panel monitor with CCFL backlight which offers better backlight uniformity than the BenQ XL2410T which uses LED backlight.

As stated in my post, the NEC PA271W is typically be the budget of what most people are willing to spend on a monitor, but when it comes to backlight uniformity, the PA271W's uniformity is pretty difficult to match or even exceed.

The following is the quote you took from the TFTCentral with emphasis on the part you seemed to have missed.

Quote:
Uniformity - Most desktop monitors use edge-lit W-LED backlighting with a line of LEDs along the edge of the panel. The whole screen is lit by means of a special diffuser, and so it is this which really determines the brightness uniformity you experience. The uniformity of brightness depends only on the design of the diffuser and you can often see various defects like bright spots or a brighter zone at the edge of the screen where the lamp or the line of LEDs resides. Having an LED backlight does not guarantee you better uniformity. In fact, good uniformity is harder to achieve in the long term as the LEDs age, with each LED possibly aging at a different rate. With RGB LED units, the use of three separate light sources for red, green, and blue means that the white point / colour temperature of the display can move as the LEDs age at different rates as well.



Here's another quote, and an illustration regarding the backlight. It can have a direct affect on backlight uniformity.

Quote:
An edge backlight with white LEDs (W-LEDs) - The LEDs are placed in a line along the edge of the matrix, and the uniform brightness of the screen is ensured by a special design of the diffuser. This backlight does not offer the option of zonal control over brightness like the direct lit method does (see below). It can not offer an extended color gamut either. Instead, it is economical and compact, which makes it popular among notebook makers and with manufacturers producing ultra-thin displays and keen to keep costs to a minimum. This is the variation commonly being used in desktop displays at the moment.

Modern displays and LCD TV's have progressed from having 4 sides lit by LED backlights to only 1 side. This helps reduce cost and improve efficiency.




It would be logical suggest as monitors with LED backlight moves away from 4 sides with emissions to just 1 side with emissions that backlight uniformity can suffer from such design change. But on the bright side, cost is reduced and less power is consumed.
July 2, 2011 4:03:56 PM

jaguarskx said:
This is a discussion about backlighting which is separate from LCD panel technologies.

Actually all I did was explain why some LCDs have dark corners. I didn't try to explain how LED backlights work. All I said was they usually had more consistent lighting. I should have said better contrast.

You are right about the Uniformity, I should have linked the contrast ratio section.

I still think you should still only do comparisons between products of the same price bracket. Usually people have a budget and want to get the best for their money and these comparisons.

When taking cost into consideration, the LEDs usually look better. They have better whites/blacks and more vibrant colors. Sorry I was not more articulate in my initial post.

http://www.tomshardware.com/reviews/ccfl-led-backlight,...
Quote:
Looking across all nine of these monitors, we can generalize and say that LEDs definitely look more dramatic. The blacks are deeper, the whites brighter, and the colors more vibrant. At the same time, we found LEDs more prone to skewing toward a given color and needing more calibration in order to remedy this. CCFL displays often look semi-lifeless when sitting next to an LED, but their colors appear more photo-realistic. CCFL definitely renders more detail in shadows because the blacks haven’t been pushed down as strongly. Yes, sometimes the measurement data contradicts this, but we’re going by side-by-side visual comparisons, and it’s important to weigh both.
a c 471 à CPUs
July 2, 2011 4:27:37 PM

browsingtheworld said:
Actually all I did was explain why some LCDs have dark corners. I didn't try to explain how LED backlights work. All I said was they usually had more consistent lighting. I should have said better contrast.



Actually, the following is your first post.

Quote:
Usually better and more consistent lighting.With a regular blacklight there's a centralized bulb and the corners usually get less light and are darker. The LED backlight monitor should be consistently bright regardless of the place on the screen you look.


That is usually the misconception that most people have regarding LED backlight and the reason why I have taken the time to correct you. And to also make other people aware that LED backlight is not the magic bullet that many people seems to make it as a "be all, end all" reason to buy a particular LCD monitor.
July 2, 2011 4:49:35 PM

jaguarskx said:
Actually, the following is your first post.

Quote:
Usually better and more consistent lighting.With a regular blacklight there's a centralized bulb and the corners usually get less light and are darker. The LED backlight monitor should be consistently bright regardless of the place on the screen you look.


That is usually the misconception that most people have regarding LED backlight and the reason why I have taken the time to correct you. And to also make other people aware that LED backlight is not the magic bullet that many people seems to make it as a "be all, end all" reason to buy a particular LCD monitor.

I know what my first post said hence:
browsingtheworld said:
I should have said better contrast.


For lower priced CCFL LCDs you're probably going to get a crappy/mediocre light which will give you dark corners. It's much easier to light up the corners with a cheap LED than a cheap CCFL monitor. Most people don't buy high quality monitors nowadays since you can get a low quality one for so cheap (and it's much harder to distinguish between the quality of LCDs based on brand as you should know).

I'll be much more specific now. For a similar quality (brand) monitors under $200 the LED will most likely look better because of the contrast (sorry) and you don't have to worry about dark corners, even for some very cheap LEDs.
a c 471 à CPUs
July 2, 2011 11:43:08 PM

There's no evidence that points to LED backlight being better than CCFL backlight for "dark corners". I have owned 4 LCD monitors and none had issues with "dark corners".

Generally speaking, LED backlight pro and cons are as follows:

Pros:
1. Low power consumption
2. Thinner and lighter monitor due to edge lighting
3. More vibrant colors

Cons:
1. Colors can be slighly bluish due to blue LEDS with yellow phosphorous coating to imitate white.
2. Lower color accuracy, but this is not a major concern for the average user
3. Less uniform backlight due to edge lighting instead of a full backlight array for CCFL backlight.
a c 141 à CPUs
July 6, 2011 12:34:09 AM

Iactually never seen an lcd panel that had anything other than 1 or 2 ccfl's and they have anyways been on the edge witha diffuser behind the actual lcd. What model uses a ccfl array? I want to look up and find a disassembled shot to see what that looks like. Thanks.
a b à CPUs
July 6, 2011 1:02:46 AM

A monitor is someting you should buy in a store where you can see for yourself
same with speakers/sound systems
what sounds or looks good to me would look bad to somebody else
but neither one of us is wrong
It is not something you can benchmark
It is too subjective
Same as mice and keyboards
they are too personal an item

Buying mice,keyboards,monitors and speakers is something
best done in person
(unless there is a KILLER deal on Newegg :)  )
a c 471 à CPUs
July 6, 2011 3:14:09 AM

popatim said:
Iactually never seen an lcd panel that had anything other than 1 or 2 ccfl's and they have anyways been on the edge witha diffuser behind the actual lcd. What model uses a ccfl array? I want to look up and find a disassembled shot to see what that looks like. Thanks.


Here's a generic repair kit for a 24" Dell monitor which state that some models use 6 U-shaped CCFLs, while other models may use 7 of these U-shaped lamps. While others may use the more traditional straight CCFL lamps.

http://www.ccflwarehouse.com/morekitforde.html
a c 471 à CPUs
July 6, 2011 3:24:25 AM

king smp said:
A monitor is someting you should buy in a store where you can see for yourself


Unfortunately, that is easier said than done. None of the 4 LCD monitor I have purchased were ever available in a retail store.

Stores like BestBuy only sells a small portion of all LCD monitors available for sale. Additionally, they are all TN panel monitors which is something I generally avoid. The exception would be the Apple's monitors, a few of them are IPS panels.
a b à CPUs
July 6, 2011 3:42:44 AM

I didnt realize that Jag
I have always bought my LCDs off of Craigslist LOL
I got my Viewsonic 2260WM 21.5 1080p 1920x1080 16:9 2ms for
$90 USD with DVI cable included
Had it running over a year 24/7 with no dead pixels
TYL
I actually hate buying new electronics from stores unless I have to
I worked for RadioShack for almost ten years between 1998-2007
and I know what the markups are for electronics like TVs,Stereos
and monitors
I remember when a basic DVD player cost over $200
now it is $20 on sale at Kmart
!