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

[allajunaki]

Now, Why do I get a feeling that adder is anti-plasma?

Funnily though, this thread is NOT about plasma. This is about "CCFLS vs LED". So I do not see much point in bringing plasma.
So lets stick to that, shall we ?


Thanks, reignofchaos. I did not know that LED's also suffer the same.
But, if that is the case, don't you think LED's will be worse off, In case of CCFLS, you normally have 2 CCFL lamps, if they deviate at different rates, then your top and bottom ends will show different coloration.

However, for LED's with local dimming, they will all age and differently, hence they will begin to deviate at different rates. So don't you think you notice the deviations? (shifting temperature of display is fine, but uneven shifting is something our eye will pickup quickly, right?)

Agreed this will not happen before 4-5 years, but Indian, AFAIK, use TV's for atleast 5 years, before thinking of replacement, right? So they will see this happen towards the end of TV's life.

 

[adder]

Now, Why do I get a feeling that adder is anti-plasma?

Funnily though, this thread is NOT about plasma. This is about "CCFLS vs LED". So I do not see much point in bringing plasma.
So lets stick to that, shall we ?


Thanks, reignofchaos. I did not know that LED's also suffer the same.
But, if that is the case, don't you think LED's will be worse off, In case of CCFLS, you normally have 2 CCFL lamps, if they deviate at different rates, then your top and bottom ends will show different coloration.

However, for LED's with local dimming, they will all age and differently, hence they will begin to deviate at different rates. So don't you think you notice the deviations? (shifting temperature of display is fine, but uneven shifting is something our eye will pickup quickly, right?)

Agreed this will not happen before 4-5 years, but Indian, AFAIK, use TV's for atleast 5 years, before thinking of replacement, right? So they will see this happen towards the end of TV's life.

Well i am not anti plasma nor am i anti lg be it in plasma or lcd i only state the facts.
Well 2 ccfl lamps in a lcd may be a really tine one.IN tvs size lcds there are many CCFL.

 

[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?

Anyone have the idea?
How can independednt areas dim the light source when the source itself is in the edges?

 

[adder]

Anyone have the idea?
How can independednt areas dim the light source when the source itself is in the edges?

well if the LEDs are located at either side of the edges the light it can dim certain zones.No idea about other companies such as LG .samsung also apprears to have some sort of dimming in their flagship C9000 which is said to be similar to sony HX800 version here is sony approach in their HX800 which is edge LED and local dimming and has the UV2A panel.

The blacks levels of HX800 matches the panasonic VT20 in ANSI checkboard pattern and gets even darker in other testing methods if the blacks area is higher.

 

[vramak]

Anyone have the idea?
How can independednt areas dim the light source when the source itself is in the edges?

If you understand the concept of edge-lit LEDs you can easily guess how local dimming works.

LED edge lit LCD will have an array of small, bright LED lights around the edges. The light from these LEDs will be spread across the surface of the screen using a light guide (basically, it's a sheet with a number of tiny prisms that will deflect the light at right angles, away from the screen.)

Here's a nice image explaining LCD back(or side)lighting.

Local dimming cannot be done for normal, CCFL LCDs.

Local dimming is done best in LED backlit LCDs where individual LEDs are dimmed according to the scene. The more the number of back LEDs, the more the local dimming zones and better the picture quality. The best and most expensive LED backlit TVs have about 512 local dimming zones. (Of course, full HD plasmas have technically 2 million local dimming zones but practically there's not a drastic difference in picture quality between expensive plasma's and expensive LEDs.)

Local dimming in edge lit LCDs will be done by dimming the light level of some of the edge LEDs. A simple ASCII explanation -

Fully lit screen. 1's are the glowing LEDs. -

1111111
1------1
1------1
1111111

Locally dimmed screen. 0's are the dimmed LEDs. -


1110011
1------1
0------0
1110011

Of course, this is a very approximate process and will be nowhere as good as backlit LED TVs' local dimming.

 

[allajunaki]

Do we have any HCFL Panels in India?
Looks quite interesting...

 

[adder]

Do we have any HCFL Panels in India?
Looks quite interesting...

It was available but only in grey market like the last years sony WE5.