Screen flickers at low brightness

There's nothing wrong with your iPads, almost [anything|http://www.youtube.com/watch?v=7Moniwv8ewU] with an LED backlight display will show it at low brightness.

LEDs don't actually dim like old CCFLs, they flicker at specific frequencies to appear as though they are dim. Some people are more sensitive to this than others. I see it on my LED backlit MBP and on my wife's iPad (each at low brightness). The only real workaround is to turn your brightness up a tad.

Here's the best description I've found...

+The average brightness of the LED would also be the same if measured electronically. The difference is in the brightness perceived. The human eye has a certain amount of persistence. If exposed to a bright light the eye will "remember" the light for a short period of time. This allows us to view a motion picture or TV screen as a steady image when in fact it is flickering at 24 to 30 times a second. When the LED is flashed on brightly for a short time and then turned off the eye "remembers" the light at the high brightness level. The result is that the perceived brightness of the back light is closer to the high pulsed brightness than to the lower average dc brightness.+

Source :: http://www.tstonramp.com/~pddwebacc/lcd_backlights.htm

Message was edited by: Oso Grande

I'm also experiencing this issue. And after doing some tests I have discovered how to reproduce this.

1. Auto-Brightness must be On
2. Brightness must be ajusted to low. Something about 20% to 30%
3. iPad must be on batteries. No power cord plugged.
4. You must be in a dark room.
5. You must be viewing a almost white screen (any bright screen). A white/light web page like this one should work.

It seams that the flicking happens in 2 situations:
1. Any part of the screen has been updated. An animeted gif, the tap of a keyboard letter, or even the loading bar of a loading web page.
2. The light on the room have changed a little bit. A TV, for exemple.

Notice that I cound not reproduce the problem all the times I tried. So there is probably another variable that I could not figure out. Maybe I wasn't watching an action movie. 🙂

What I have noticed is that if the room light stay exactly the same, iPad take a fraction of a second ajusting the auto brightiness, flicking during this small period of time and then stopped, as it was finaly found the rigth brigthness for the ambient.

I was reading a white web page in my bed, dark room, without a shirt and even the reflection of the screen in my chest seams to cause this auto-brightness/flicking problem.

Since this do not happens with the power cord plugged, I don't believe that this can be a phisical problem with auto-brigthness sensor.

I think that the auto-brightness piece of software are doing ambient light ajustment so fast that it start to do this flicker until it finaly foung the right brigtness, and if the ambient light keep changing (TV light) the software will keep trying to ajust the brigthness, causing the flicker. And in some way the change in the screen (animated gif) is also causing auto-brightness act and ajust.

So, probably, this issue could be fixed with a OS software update.

Hope this could help.

Fabio
An iPad fan from Brazil.

As someone stated above, it does have some relation to process load, so try to just turn it off by holding the lock button until the shut down message appears, and then turn it on again. This will kill any 'unwanted' process that may be loading your CPU, taxing it so producing the interference.

It worked for me, I was noticing flickering at the lowest bright setting with auto brightness on and, after 'reboot' it just went away.

My new iPad's screen flickered too - mostly at lowest brightness, but at times above that as well (~20%).

I read through this thread, and decided to get a replacement. Best Buy has inventory data on their site, I chose a day when they were in stock, and the exchange was easy.

No flickering screen yet on the new one.

My screen flickers too.

My take is that WiFi packet exchange is causing either interference with brightness circuitry or puts additional load on the battery which causes it to momentarily drop output voltage which results in flicker.

Depending on the WiFi output power it may be more noticeable or less noticeable. The thing is that LED brightness output is non-linear at low voltages and this causes the flicker to be more noticeable at low screen brightess.

So my advice would be to either turn off WiFi when reading a book in low brightness (which will save your battery even more) or move closer to your WiFi router to get a better signal and make iPad transceiver use less power output.

x0SiN0x wrote:
I'd ask then why not all ipads display this same behavior and how come after a reset things seem to be better (time will tell)

It has to do with the refresh rate of the LEDs, what frequency they are set to, and how much power drain there is. If you happen to be doing something CPU intensive, you are causing a large enough power draw that it might affect the timing of the LED flicker. Some people are more sensitive to it than others. Since it is software/firmware related it may not be fixed in the future but I doubt it...

I'll give you an example... When I got my 15" MBP, I noticed it had the backlight flicker/flutter on low brightness almost immediately. However, if I put it on High Performance (using the discrete 9600GT GPU), no flicker at any brightness level b/c of the lack of power management. Coincidentally, my logic board was replaced for an unrelated issue (headphone jack stuck on) and the replacement had no effect on the flickering/fluttering backlight.

I brought it to the Genius Bar, they noticed it, and said to turn the brightness up...it's nothing they haven't seen before and is very common. I contacted AppleCare about it, an inquiry was sent to their engineering department on behalf of their Product Specialist that I spoke to... the guy called me two days later and told me exactly what Apple Engineering had told him--exactly what the genius bar had told me--it's normal on low brightness, especially with the 9400M integrated chip (ie. battery saver mode)

The iPad is no different...it uses LED backlights just like the Macbooks and Macbook Pros. My wife's iPad, bought less than a week after release, will show a slight flicker/flutter in the backlight on low brightness if I'm pulling up web pages or doing something CPU intensive on a solid white page.

Windows users complain about the same thing on LED backlights... check out this post on another thread, there are links to it.

http://discussions.apple.com/message.jspa?messageID=11380062#11380062

My iPad has just started exhibiting this behaviour. Previously it has been frequently crashing out to the apple logo. I have restored it to factory firmware and all has been good for a couple days but today it has been crashing out again and the screen started to flicker.

Interestingly enough I have discovered that the cloth I use to clean the screen was causing a static buildup and making a crackling sound when I used it. I have since discontinued the use of the offending cloth and the screen has not flickered since, although its only been about 30 minutes so I'm still unsure if there will be a trip to the apple store in my immediate future.

FYI - I was also using the official apple case. Not sure if this has caused some problems with not allowing the static electricity to earth, but my girlfriend also has the same case on her iPad and has had no problems at all?

I too have this problem but have found a quick and effective solution it does require you to turn your auto brightness off for good I hope.... Anyway you must turn your brightness to 35% up to 45% and while typing this iv noticed that after you shut off auto brightness and move the brightness bar via double tap you can dim the screen even more now, there is no flicker for me that is. I felt like returning this but if you look up LCD problems via flickering you get many other laptops and LCD backlit items doing the same thing. Tvs, computers, ereaders and more. Hope this helps, this also got rid of the blurred text I got when I surfed the Internet. <--- if this is a new problem then here is a answer I guess.

After bringing mine back into Best Buy I was sent to their "genius" who indicated this was perfectly normal. After I checked a few of the store display models and not seeing the issue I presented these new findings to them. They then proceeded to perform a reset which seems to have at least stopped it from flickering but not counting on this fix lasting long.

In the end bestbuy wouldn't even return the unit and requested I come back if any further issues.

I had mine replaced today, and so far it does not show the same flickering issue my last one had.

Hi there, thanks for detail answer. It exactly describes the situation and also the solution-for me-turn off auto brightness and the flickering disaopears...I also had one week without problem but now it came back whe the auto was on.

I noticed the same exact issue today on my 32GB wifi model. at about half power (brightness) things seem to be ok. But anything lower then this and I get a flickr and gets worse the lower I go.

Compared mine to an associates here at work and his dont have the issue at all (64GB model but dont think anythings different between the two?).

not happy with this

AstroMacMan wrote:
If this is indeed a common or inherent feature with the iPad, we may have to reconsider our plans. Hope some others chime in that can report they DON'T have the problem!

It's defiantly not on all, i would make sure to play with yours prior to leaving the store.