Slight screen flicker?

sdelcegno · Dec 6, 2010

I have a nook color, I was wondering if anyone notices a very slight screen flicker like a low refresh rate? Most people would not notice. It doesn't bother me much but I wanted to see if its normal. I notice it most on a dark grey background at 50 percent or lower brightness.

Sent from my HTC Vision using Tapatalk

ericejs · Dec 6, 2010

Yes! finally someone that notices it! I have been posting this on other forums. I notice it too on dark backgrounds with about 20-40% brightness, Not sure if it can ever be fixed with an update, but it is sometimes annoying, although not highly noticeable.

sdelcegno · Dec 6, 2010

I have worked with computer enough that I can tell the refresh rate of a crt just by looking at it. If its normal I am not to worried I justed wanted to know if it was defective because ill switch it out before I root it.

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boret · Dec 7, 2010

I get the same thing, very noticeable when you are changing the brightness setting. I use the lowest brightness to read an eBook, and I can really notice the flicker when I lower the brightness, but I can notice it when I get back to the reading screen.

rckymtnrfc · Dec 7, 2010

I see it on darker images...its so subtle I ignore it.

Sent from my NOOKcolor using Tapatalk

jta · Dec 7, 2010

I still have mine stock... but I see it as well.

Anyone that has loaded any other apps notice it in those apps? i.e. does it flicker noticably in Angry Birds? or other apps?

thanks.

J

sdelcegno · Dec 7, 2010

I wonder if it being an IPS screen has anything to do with it. It doesnt bother me to much but causes more eye strain than reading from my htc g2. You would think they would make sure an ebook reader doesnt flicker. oh well i can deal with it.

plympton · Dec 7, 2010

sdelcegno said:
I wonder if it being an IPS screen has anything to do with it. It doesnt bother me to much but causes more eye strain than reading from my htc g2. You would think they would make sure an ebook reader doesnt flicker. oh well i can deal with it.

It's not the screen, per se, but the LED's that are lighting it up. From what I've read, LED's can't vary output with respect to voltage (they're not dimmable), so you have to pulse them very fast to change the output. I assume that the lower the "level" the more the LED is off vs. on, hence the flicker.

Dang I can't post links yet...

Go to Wikipedia, and look for :
/wiki/Backlight#Flicker_due_to_backlight_dimming

I'm pretty sensitive to this, but haven't noticed it on my iPad, but apparently it does it as well. I was wondering why the stock lowest brightness levels were so friggin' bright - probably at the threshold of flicker. You can dim more in a browser or ebook app, which is where I see reports of flicker.

Go to Discussions dot apple dot com
/thread.jspa?threadID=2398784

Another reason why I like my old CCFL IPS 12" ThinkPad X32!

-Dan

nemoscat · Dec 8, 2010

While you can dim an LED by limiting the current (either via inline resistors or with constant current drivers), you can only do so to a degree. Below a certain current, they will simply not light even though the current goes through the LED. On high performance LED's this is still at a pretty bright level. So instead you use PWM (Pulse Width Modulation) and vary the duty cycle to brighten and dim the LED. As the PWM is at a fixed frequency, with more or less of the cycle being lit or unlit, once the unlit portion becomes substantially longer than the Lit part, you can detect the "Flicker" if you are sensitive to it. This is usually particularly noticeable in the "corner of the eye" if you pan you vision across the area and the device gets paned across you field of vision.

This is done on all the new LED tail lights on cars as well and I hate seeing them at night, when they are almost making me nauseous from the flicker.

sdelcegno · Dec 8, 2010

Good info thanks. Makes sense but wonder why I don't notice on my led backlit netbook. Guess every screen is different.

ericejs · Dec 8, 2010

yea I really wish there was an update to fix this, but i guess it's just the screen, funny how I have never noticed this on any LCD screen I have ever had from computer to TV

glacon · Dec 8, 2010

three nook colors - my experience with flicker

My first nookColor had screen flicker, also a mind of its own with phantom taps. Nook #2. Did not have noticeable screen flicker but did have a handful of stuck pixels. Took it back and picked up #3. No stuck pixels, but I've got screen flicker on dark colors. Find it strange that nook #2 didn't have te problem with the flicker. I don't like the flicker at all but think it may be timento live with it.

glacon · Dec 8, 2010

flicker

Has any one returned a flikering nook color and gotten a better one in return?

jpl605615 · Dec 9, 2010

Hello, I am having a similar problem with angry birds. My screen sometimes will flash different colors and today the screen stayed completely red for 2 or 3 seconds while playing the game. But other than that I love the rooted nook color. Maybe the graphics chip is not powerful enough for this game.

glacon · Dec 10, 2010

Firmware update

What you described with angry birds is not the problem I am having. Mine is screen flicker. My eye can basically detect the refresh rate with low brightness or in darker colors.

Tried to change it out. Would say that Best Buy is much easier to exchange things at than Barnes & Noble. Eventually they switched mine out and the new one had a dead pixel. They then let me open two more in store in the store all had dead pixels, so did their display model. All presented in the lower right hand corner of the screen. Would be covered up by the black menu bar normally, but visible when the black menu bar goes away.

Anyway I kept my flickering nook, and talked to someone at Barnes and Noble tech support on the phone. He told me the dead pixels were new to him, but they knew about screen flicker issues. He said they would be releasing a firmware update to address this and other problems very soon.

Just wanted to note that none of these nook colors were rooted.

webvan · Dec 10, 2010

Yes, same here, I have that on my Witstech A81 (resistive screen) too, more noticeable when the battery level drops. Never noticed this problem on my iPhones or iPad though...can't be Android related can it?

greenmky · Dec 15, 2010

glacon said:
What you described with angry birds is not the problem I am having. Mine is screen flicker. My eye can basically detect the refresh rate with low brightness or in darker colors.

Tried to change it out. Would say that Best Buy is much easier to exchange things at than Barnes & Noble. Eventually they switched mine out and the new one had a dead pixel. They then let me open two more in store in the store all had dead pixels, so did their display model. All presented in the lower right hand corner of the screen. Would be covered up by the black menu bar normally, but visible when the black menu bar goes away.

Anyway I kept my flickering nook, and talked to someone at Barnes and Noble tech support on the phone. He told me the dead pixels were new to him, but they knew about screen flicker issues. He said they would be releasing a firmware update to address this and other problems very soon.

Just wanted to note that none of these nook colors were rooted.

Thanks. I can see the flicker too on gray screens. I have no other issues though (minus a tiny, tiny bit of give on the bottom bezel). I'll wait and hope it gets fixed in an update. I don't have a lot of time to keep exchanging a good unit.

blackjoker4215 · Dec 15, 2010

If it is a known issue and a firmware fix is planed, then I am content with my rooted nook. Thanks for this thread.

greenmky · Dec 15, 2010

I took mine back to B&N today to see if replacing it would fix it. Both store displays didn't have any flicker.

They opened two different nooks and they did the same flickering thing.

So I called Nook technical support. He put me on hold for about 5 minutes. He said he checked about 5 nooks and they all flickered. But he hadn't noticed it before.

So, he will put a ticket into the development team to have it looked at.

So, another confirmation that Nook tech support is aware and looking into it.

starlabs · Dec 16, 2010

My first Nook did not display this behavior. I returned it due to creaking issues, and the replacement did display screen flicker.

I'm hoping it's a firmware issue and not a hardware one!

Currently not a big deal though...

Slight screen flicker?

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