To everyone that is crying about iPad screen bleed

[Alx9876]

http://www.pchardwarehelp.com/guides/backlight-bleeding.php


Backlight Bleeding: An LCD Problem

The entire surface of an LCD is backlit from behind by a light source (CCFL light) and the LCD blocks out the light that is not needed. Backlight bleeding occurs when this light is not 100% blocked allowing some light to "bleed" through the LCD causing spots of lighter areas on a dark or black background.

Unfortunately, almost all LCDs suffer at least a small amount of backlight bleed because the opacity of LCD panels is not enough to block all light, though it only causes problems if it can be easily detected by the human eye. The graphic below shows an example of what an LCD display with excessive backlight bleeding looks like with a dark, static background. As you can see, the top left and bottom right corner are lighter in color than the center of the display.



Fixing Backlight Bleed

In general, there is no definite fix for backlight bleeding, although some users in this thread have had success improving the bleeding on the model 2005FPW Dell LCD using the method listed. The best way to fix backlight bleed is to have the monitor replaced or avoid LCD's which are known to have bleeding problems all together.

Read reviews on the model of LCD you plan on purchasing, buy from a retailer that will allow you to exchange the display if there are any major problems and if possible try to view a display model or two before you buy. Even this does not guarantee you will receive an LCD completely free from bleeding.

Now that you read this, Please shut up about the iPad 2 screen. It's getting old and redundant.

Until Apple puts Retina display or something better we all have to just deal with it.

 

[NYY FaN]

yea.. I don't think you understand the severity of the bleeding thats going on with most of these ipads..

it has nothing to do with putting a "Retina display" in.. the ipad 1 had the same screen and there wasn't such a big problem last year.

 

[dread]

The iPad 1 was just as bad. People just let it go after a while. The bleeds are worse than any other LCD that I own. Why are you telling people to forget about it? That is what forums are for.

 

[Piggie]

Agreed, you are totally missing the point.

Yes, we all know (well not everyone knows, but most techy people know) that due to the way LCD screens work you cannot get a black screen.

Local dimming would fix this to a lot of extent, but monitors don't appear to have white LED arrays with local dimming yet.

So we have a bright white backlight along say the bottom of the screen and diffusers to spread this bright single light source over the entire back of the panel.

Then using filters and LCD crystals we attempt to block the light to make it look black. And it does a pretty good job, all things considered.

Due to manufacturing variations and mass production assembly you tend to get very slight variations/deviations in the panel which leads to slightly more pale areas, normally along the sides of perhaps in a corner.

This is what most screens have to a little degree, a slight fading/lightening that can be seen by the human eye, which is very sensitive to these things.

This is not the iPad2's problem.

What seems to be the case with LCD panels is that if you pinch them, you get a bright patch. You can try this with your desktop monitor, and may of ma not show up depending on it's construction.
In a dark room try pinching the bezel and the back of your screen, and, depending on it's construction, you may be able to place a tiny amount of pressure onto the LCD panel itself and show a bright patch whilst you are applying the pressure, which will go away when you let go.

This appears to be the iPad2's issue.

Due to a general design flaw, tolerance variations and assembly methods the LCD panel inside the iPad2 is having pressure applied to it when the unit is complete.

Now, seeing the iPad2 stripdown, it appears to by lying over the battery and logic board and screwed down at each of the four corners.

Of course, you would not want the panel to be bent as it's being screwed down, so let's assume that the logic board/battery are not quite touching the rear of the screen. Or they are offering a nice flat surface for the LCD panel to rest against. when it's screwed down.

We're talking about a tolerance less than a mm here, if the batter was not seated down perfect and was sticking up say 1mm, then the panel would be being bent as it's was being screwed down.

But again, let's assume that's not the case, as they would be an assemble error.

What more people seem to be thinking is the issue if the screen being glued down into place. Apple don't, I guess, want a gap between the glass touch screen and the LCD panel. Firstly a gap is wasted space, Secondly it you allow flexing of the glass as you pressed down. So we can assume it's been designed to just about rest evenly onto the LCD panel.

Now along comes the new idea of no clips/brackets, but lets glue this glass into position. So, however the assembly method works, the glass is them pressed down onto the iPad, possibly heated to soften the glue? and fixed firmly into place, applying pressure onto the whole assembly to make a "Tight Sandwich" if you wish to the whole device.

This, we are thinking is where the problem starts. Due to this, which as I said, if a fundamental design issue, various uneven pressure points are being created between this strongly glued down multitouch front glass sheet and the LCD panel inside, and these individual pressure, pinched areas, then show up as bright spots, as that was a LCD panel does when it's pinched.

Unless you release the pressure, settling in, these bright spots are not going to change, small heat variations will cause things to change a fraction as materials expand/contract, so if you wrapped your iPad is a airtight bag in the fridge and looked for them, or left it out in the sun and looked for them you may see some differences.

I don't believe, unless you remove the glass, the pressure points are just going to disappear one morning.

So again, as said in the beginning, it's not the general slight fading issue that's people are complaining about, as all screens will have this to a minor degree, and is something we are happy accepting, we do not expect perfection, as this tech does not allow perfection. It's the bright "Pinched/Pressure" bright patches that are the issue here, and without a design change, I cannot see what can be done, and it's almost total pot luck as to how your glass is pressing down the panel on your iPad2 which will determine how bad your model is.

They are not going to be able to change design now the manufacturing cogs are running. With mass production you sometimes see a bit of tape added of a foam pad is added, if something were loose for example, but you cannot change a fundamental design now. It's to late.

They could I suppose change glue specs, or pressure/heat of assembly, that kind of thing. but nothing structural.

The best we can hope is, firstly, being lucky and getting a good one.

Secondly, we need as many people as possible to return iPad's to Apple in enough numbers that major feedback works it's way beck from Apple stores to Apple HQ, and it's enough of a logistical and financial issue that they do all they can to design this problem out for the next model.

 

[bossxii]

yea.. I don't think you understand the severity of the bleeding thats going on with most of these ipads..

it has nothing to do with putting a "Retina display" in.. the ipad 1 had the same screen and there wasn't such a big problem last year.

Any proof at all or just the typical unfounded hyperbole found on tech blogs?

 

[tigres]

The iPad 1 was just as bad. People just let it go after a while. The bleeds are worse than any other LCD that I own. Why are you telling people to forget about it? That is what forums are for.

I tell you with no uncertainty, both my wife's, my friend, and my neighbor's iPad 1 exhibit zero backlight issues. I know, because I have personally checked them when I set them up.

The screens are the closest to perfection that I can see with the human eye, which is good enough for them/me.

OP. Very nice summary btw.

 

[Buck987]

piggie,

you are spot on...great summary.

this is not the same issue as the original iPad

 

[NYY FaN]

Any proof at all or just the typical unfounded hyperbole found on tech blogs?

well, let me give you a first hand experience.. I've gone through 4 ipads myself, so far, all with the issue, and the employees I talked to have dealt with returns for this all week. obviously that doesn't account for EVERY ipad... but its become a hassle

 

[Piggie]

In addition to my -long- post above where I try to explain what I feel are the issues.

Here is a basic/general explanation video about the general construction, "how they work" for LCD panels.

I'm sure different manufacturers have their own tweaks, perhaps where they arrange the rear light source and their diffuser panels. This is still interesting for those who have never seen it before:

http://www.youtube.com/watch?v=jiejNAUwcQ8

If you watch this video. I think what's happening with the iPad2's design is that the "LCD Sandwich" is being squeezed due to pressure points from the front glass being glued down, hence allowing the light to pass through the glass panel from the rear light source to your eyes.

 

[Charlie Sheen]

I have the ipad 1 and i can't tell any bleeding in normal use

 

[rkahl]

People who are returning their iPads 5-6 times for light bleed issues and hope the next will be better are insane... just get a refund and re-purchase in 3-4 months.

 

[kazaam93]

People who are returning their iPads 5-6 times for light bleed issues and hope the next will be better are insane... just get a refund and re-purchase in 3-4 months.

Why not keep the iPad and get a replacement after 3-4 months>

I phoned up Applecare as my iPad has backlight bleeding as well. I asked if Apple were aware of them problem and was told that they are.The Applecare man asked me if he should make an appointment for me in my local Apple Store but I said that I have read of people having replaced their iPad 2's multiple times just to have the same problem, and that this is too much hassle. I then asked how long I should wait to go into my Apple store for a replacement, and was told 4 months! (I'm like woah, by then the iPad 3 will almost be out) but I plan to wait a month or two and phone up to see if the problem is sorted as the problem shouldn't take so long to fix. C'mon APPLE!! (I know they don't read this, lol)


I am sure there are some people with no issues, but many people like me won't notice it or think its normal. I wouldn't have really noticed it if I hadn't read it on these forums. But there must be some people with perfect iPads!

Hope this helps!!

 

[Jottle]

How is having a retina display going to eliminate backlight bleeding? Are they manufactured any idfferently? If not, there will be bleeding on ipad 3 as well. It's an issue with lcd technology in general, just as the OP posted.

 

[Vanessa17]

Screen bleed may be an inherent issue of LCDs etc however that does not take away from the fact that when spending hundreds of dollars on a piece of technology, a luxury item for most, that we then expect a fault-free device.

Sure, they will always be production faults but this seems to be an issue for both models of iPad...

 

[Mac.World]

How is having a retina display going to eliminate backlight bleeding? Are they manufactured any idfferently? If not, there will be bleeding on ipad 3 as well. It's an issue with lcd technology in general, just as the OP posted.

Yep, light bleed is an issue with lcd's in general. I have had TV's with light bleed, iMac's, iPads, macbook Pro's, Dell monitors and so on. Sometime's it is barely noticable, but it is there.