Questions about A-TW Polarizer

[delerious]

Just got the LCD2490WUXi.

I read about the A-TW polarizer causing a magenta and green effect in the corners, but I thought that was only when looking at the monitor from an angle.

Well I created a 100% black image and made it full screen, and I see that the lower left looks purplish and the lower right looks greenish, while looking at the monitor straight on. That is with my head approximately 18 inches from the monitor. If I move back to about 5 feet, then I don't see any purple or green (although there does seem to be some backlight bleed, especially in the lower left corner). But then I won't be using the monitor 5 feet away, I'll be using it 18 inches away. I thought H-IPS was supposed to eliminate the purple hue at an angle that S-IPS monitors suffer from. But it looks like it has introduced magenta/green corners straight on.

So what is the A-TW polarizer supposed to cure exactly? The white glow when viewed from an angle? Certainly a white glow from an angle would be better than magenta/green corners from straight on, no? I have access to a widescreen TN panel and a 4:3 S-IPS panel - can I use either one to recreate the white glow so that I can see what it looks like?

 

[chrcoluk]

I have been told the glow which appears off angle on blacks that people get on dell's e-IPS screens is because the polarizer isnt fitted so I assume thats what it is supposed to take care off.

 

[nomu]

Just got the LCD2490WUXi.

I read about the A-TW polarizer causing a magenta and green effect in the corners, but I thought that was only when looking at the monitor from an angle.

Well I created a 100% black image and made it full screen, and I see that the lower left looks purplish and the lower right looks greenish, while looking at the monitor straight on.

Yes, working as intended.

That is with my head approximately 18 inches from the monitor. If I move back to about 5 feet, then I don't see any purple or green (although there does seem to be some backlight bleed, especially in the lower left corner).

Yes, precisely. The lower left BLB is also a common issue with that monitor, and if it bugs you enough you have the option of exchanging it until you get a perfect one.

But then I won't be using the monitor 5 feet away, I'll be using it 18 inches away. I thought H-IPS was supposed to eliminate the purple hue at an angle that S-IPS monitors suffer from. But it looks like it has introduced magenta/green corners straight on.

So what is the A-TW polarizer supposed to cure exactly? The white glow when viewed from an angle? Certainly a white glow from an angle would be better than magenta/green corners from straight on, no?

No. Again: no. Again: Again: No.

Instead of looking at a completely black screen, try looking at an actual image. White glow ruins dark images, the much dimmer red/green glow is hardly noticeable, even on Hardforum. A comparably bright white glow would be better than a colored glow, but without the polarizer the glow is much brighter, and that's the whole point of the A-TW.

If what you really do want is a black screen, turn the monitor off.

I have access to a widescreen TN panel and a 4:3 S-IPS panel - can I use either one to recreate the white glow so that I can see what it looks like?

Yeah, make them show a black screen and move your face close enough that the corners glow. The glow on the TN will probably be more yellow, and the S-IPS may be purple depending on the model.

 

[Snowdog]

Just got the LCD2490WUXi.

I read about the A-TW polarizer causing a magenta and green effect in the corners, but I thought that was only when looking at the monitor from an angle.

Well I created a 100% black image and made it full screen, and I see that the lower left looks purplish and the lower right looks greenish, while looking at the monitor straight on. That is with my head approximately 18 inches from the monitor. If I move back to about 5 feet, then I don't see any purple or green

18 inches seems a bit close on a monitor this size. I tried it, you need quit a lot of eye movement to see the screen. You are 18" away from a screen that is actually wider than that(20"). So you are creating a viewing angle of less than 60 degrees (more than 30 degrees off axis). So you are viewing the corners at quite an angle.

I don't see this effect, but I will probably have to wait till night with a black screen. What other LCDs have you used. Using a TN or VA panel at that distance should cause all kinds of anomalies as well.

I would recommend:

a: Using the monitor at a little further out. I thought I was close and I use mine around 24" - 28".

b: Make sure your backlight is adjusted for your lighting conditions. If you are using your panel in darkness you need to turn down the backlight. Having your backlight higher than it needs to be, means any backlight/leakage/viewing angle leakages will be more obvious.

c: After the above, try some real world usage, instead of sitting up close staring at black screens looking for defects.

I have owned 5 panels including VA,TN and IPS without A-TW. It is no constest A-TW image stability and freedom from anomalies is the best, but it isn't a CRT. Wider screens also mean greater angles to the corner especially if you are sitting VERY close.

From my review showing the glow on my 17" TN: http://www.hardforum.com/showthread.php?t=1338622

 

[Surly73]

Just got the LCD2490WUXi.

I read about the A-TW polarizer causing a magenta and green effect in the corners, but I thought that was only when looking at the monitor from an angle.

Well I created a 100% black image and made it full screen, and I see that the lower left looks purplish and the lower right looks greenish, while looking at the monitor straight on. That is with my head approximately 18 inches from the monitor. If I move back to about 5 feet, then I don't see any purple or green (although there does seem to be some backlight bleed, especially in the lower left corner). But then I won't be using the monitor 5 feet away, I'll be using it 18 inches away. I thought H-IPS was supposed to eliminate the purple hue at an angle that S-IPS monitors suffer from. But it looks like it has introduced magenta/green corners straight on.

So what is the A-TW polarizer supposed to cure exactly? The white glow when viewed from an angle? Certainly a white glow from an angle would be better than magenta/green corners from straight on, no? I have access to a widescreen TN panel and a 4:3 S-IPS panel - can I use either one to recreate the white glow so that I can see what it looks like?

My 2490 seems to be more or less like yours. When close magenta on the left, green on the right (though subtle unless I bob my head around trying to make it do it). I have some lower left BLB too but it comes and goes. Sometimes it isn't there at all. I have no idea what makes it come and go, it doesn't seem to match temperature, operating time, or anything else. I wish it was never there, but I also appear to have no dead/stuck pixels in the panel. I think if I start swapping it out I won't be so lucky with the replacements. In actual use I almost never see any of these effects.

 

[delerious]

Thanks for the informative replies, guys.

Instead of looking at a completely black screen, try looking at an actual image. White glow ruins dark images, the much dimmer red/green glow is hardly noticeable, even on Hardforum. A comparably bright white glow would be better than a colored glow, but without the polarizer the glow is much brighter, and that's the whole point of the A-TW.

Yeah, make them show a black screen and move your face close enough that the corners glow. The glow on the TN will probably be more yellow, and the S-IPS may be purple depending on the model.

I just tried a Dell E248WFP 24" TN panel and a Dell 2007FP 20" non-widescreen S-IPS panel, and you are right, the glow is definitely brighter on those, although only when viewed from an angle. The TN panel does show a bit of a yellowish glow on the sides when I look at it straight on from 18" away, and the S-IPS doesn't show a glow straight on at all (although maybe that's because it isn't widescreen).

c: After the above, try some real world usage, instead of sitting up close staring at black screens looking for defects.

I have owned 5 panels including VA,TN and IPS without A-TW. It is no constest A-TW image stability and freedom from anomalies is the best, but it isn't a CRT. Wider screens also mean greater angles to the corner especially if you are sitting VERY close.

Yeah, this will probably be fine for real world usage. I realize that there is no such thing as a perfect LCD, but I guess for $1100, I was expecting this monitor to be closer to perfect than it actually is.

My 2490 seems to be more or less like yours. When close magenta on the left, green on the right (though subtle unless I bob my head around trying to make it do it). I have some lower left BLB too but it comes and goes. Sometimes it isn't there at all. I have no idea what makes it come and go, it doesn't seem to match temperature, operating time, or anything else. I wish it was never there, but I also appear to have no dead/stuck pixels in the panel. I think if I start swapping it out I won't be so lucky with the replacements. In actual use I almost never see any of these effects.

Yeah, I don't think I'll bother trying to exchange it. If I get lucky enough to find one with no BLB, it will probably end up having a dead pixel!

 

[Snowdog]

Yeah, this will probably be fine for real world usage. I realize that there is no such thing as a perfect LCD, but I guess for $1100, I was expecting this monitor to be closer to perfect than it actually is.

Yeah, I don't think I'll bother trying to exchange it. If I get lucky enough to find one with no BLB, it will probably end up having a dead pixel!

Yeah. I know about that feeling of buying something expensive and being dissapointed. My first LCD was a Dell 2405 which was nearly $1000 at the time. It was a hideous disappointment (got rid of it). A much cheaper TN came later and it was 1/4 the price and had less issues.

Later I bought the Dell 3007-HC. Again huge disappointment and over $1000. It really helped to buy something as poor quality as the 3007-hc because it makes the 2490uxi look awesome in comparison. It isn't perfect, but it is the best I have seen.