AVS Forum banner
1 - 14 of 14 Posts

·
Registered
Joined
·
1,446 Posts
Discussion Starter · #1 ·
I just got a 52 EX 700 set and I can see rows of flashlighting on the bottom of the set. It's not awful, but right along the bottom edge you can see little bright spots where I am guessing there is an LED row there.


Is this normal? I know on my LCD sets there are no rows and the flashligting is more conisitant.
 

·
Registered
Joined
·
412 Posts
This panel has backlight LED's on all four sides so I am surprised that you only see this on the bottom. A slight amount of light leakage is always going to be present on today's LCD panels that are edge lit. Especially if you are looking for it.
 

·
Registered
Joined
·
866 Posts

Quote:
Originally Posted by display veteran /forum/post/18326014


This panel has backlight LED's on all four sides so I am surprised that you only see this on the bottom. A slight amount of light leakage is always going to be present on today's LCD panels that are edge lit. Especially if you are looking for it.

Then why are you surprised?
 

·
Registered
Joined
·
3,396 Posts
flashlights and clouding are a product of VA LCD panels not the backlighting used in the TV


any slight amount of pressure or uneven uniformity of the LCD panel can and will result in excess light leakage because the liquid crystals cannot fully close anymore.


edge lit IPS LCD's never suffer from these problems because the alignment of the LC's is exactly opposite of VA's
 

·
Registered
Joined
·
412 Posts

Quote:
Originally Posted by woodyjoe /forum/post/18326042


Then why are you surprised?

I was surprised that you only see it on the bottom edge.
 

·
Registered
Joined
·
866 Posts

Quote:
Originally Posted by display veteran /forum/post/18332223


I was surprised that you only see it on the bottom edge.

I see what you are saying after re-reading your post. Sorry, it was late and my eyes were tired.
 

·
Registered
Joined
·
412 Posts

Quote:
Originally Posted by frito /forum/post/18326047


flashlights and clouding are a product of VA LCD panels not the backlighting used in the TV


any slight amount of pressure or uneven uniformity of the LCD panel can and will result in excess light leakage because the liquid crystals cannot fully close anymore.


edge lit IPS LCD's never suffer from these problems because the alignment of the LC's is exactly opposite of VA's

All LCD panels have backlight leakage to some degree or another. It depends on what part of the master sheet your panel came from.
 

·
Registered
Joined
·
3,396 Posts

Quote:
Originally Posted by display veteran /forum/post/18338903


All LCD panels have backlight leakage to some degree or another. It depends on what part of the master sheet your panel came from.

i've yet to see an IPS LCD with an uneven backlight, the vast majority of flashlighting and clouding problems with LCD's is only on *VA type panels


MVA, PVA, ASV are all VA panels


find me someone who complained about an uneven blacklight on a Panasonic or LG LCD TV because they almost always use IPS panels and IPS panel's do not exhibit light leakage when you press on the screen like VA's do


this is why






in the off state the LC's are aligned perpendicular to the screen and pressing on the screen by even small amounts makes the LC's turn and partially open


IPS LC's are in the exact opposite direction when in the off state so pressing on the screen only results in pushing the LC's closer together


the effect of this is if you press on a VA screen when it has a black image displayed you get a large halo of light leakage or also known as a cloud of light around where your applying pressure, if you do this on an IPS screen you just get localized distortion and leakage from where you press directly but the area around where you press is 100% unchanged.


this is one of the reasons why IPS panels are used in resistive touchscreen displays because they react very well to being pressed upon where as if you press on a VA screen not only does the area around where you press distort but there is another thing that happens and that is moving images leave ghosts when you tap on a VA panel, try it some time its pretty neat to play around with on a TV actually but would be annoying to have on a touchscreen display hehe


there is some more interactive guides that explain how and why this works a bit better here http://ipslcd.com/en/
 

·
Registered
Joined
·
1,446 Posts
Discussion Starter · #9 ·
It's amazing the difference I'm seeing with these sets. I exchanged my set three times and the third one is the best by far. Only one area of leakage and no discernable flash lighting.
 

·
Registered
Joined
·
3,396 Posts

Quote:
Originally Posted by Ericthemidget /forum/post/18339509


It's amazing the difference I'm seeing with these sets. I exchanged my set three times and the third one is the best by far. Only one area of leakage and no discernable flash lighting.

yeah thats the name of the game with many VA TV's


some people have bought 5 samsungs in a row and not one of them had zero backlight uniformity problems.
 

·
Registered
Joined
·
12,690 Posts
I have an A-MVA panel (AA01) Samsung 32" B650 that has no flashlighting or clouding, regardless of auto dimming on/off or the backlight setting. Of course, the blacks get lighter off-angle and a blue tinge creeps into blacks/near blacks off-angle.

AMVA
 

·
Registered
Joined
·
3,396 Posts

Quote:
Originally Posted by PlasmaPZ80U /forum/post/18348388


I have an A-MVA panel (AA01) Samsung 32" B650 that has no flashlighting or clouding, regardless of auto dimming on/off or the backlight setting. Of course, the blacks get lighter off-angle and a blue tinge creeps into blacks/near blacks off-angle.

AMVA

the AUO and CMO panels often have no uniformity problems its usually the S-LCD S-PVA's that have the problems even though their picture quality is better than the other two
 

·
Registered
Joined
·
12,690 Posts

Quote:
Originally Posted by frito /forum/post/18348420


the AUO and CMO panels often have no uniformity problems its usually the S-LCD S-PVA's that have the problems even though their picture quality is better than the other two

So then it's primarily the S-PVA's that have those issues and not all VA's, right?
 

·
Registered
Joined
·
3,396 Posts

Quote:
Originally Posted by PlasmaPZ80U /forum/post/18348440


So then it's primarily the S-PVA's that have those issues and not all VA's, right?

i've seen other VA's have the problem but S-PVA's have them much more often than most others


the Toshiba 40xv645u i owned for a few weeks had major flashlighting problems and i checked to see what panel it had in it and it was a Samsung made Panel made in china, not sure what type exactly but it was not a S-LCD S-PVA panel that much was for sure.


my point though was the VA LCD's in general are the only ones susceptible to the problem due their LC alignment the fact that the AUO and CMO panels rarely have flashlighting and clouding just means they are either doing something different in the process that makes it more difficult for it to occur normally or they are just producing more well made panels uniformity wise in the LCD's thickness


VA type LCD's can also have a sagging problem due to their alignment which means that over time (years of use) the LC's begin to sag to the bottom of the display causing all kinds of bad picture problems, this is pretty rare with today's VA panels thus far but i have seen a few people come on these forums describing this sort of problem with 2006/7 model Samsung LCD's
 
1 - 14 of 14 Posts
Top