Maybe an odd question for XDA, but a question I need answered before I pull the trigger on this phone. Earlier this year while buying a new television set, I learned that I am amongst a small minority of people who are sensitive to LED-lit electronic displays that use pulse width modulation to control brightness. Apparently, I can look at a PWM CCFL-backlit (i.e. my 5-year-old computer monitor or my Nexus 5) screen or a DCM LED-backlit screen (my television set) for hours with no issue whatsoever but I can only focus on a PWM LED-lit screen briefly before I start experiencing symptoms of eyestrain and motion sickness. It's like looking at a CRT that flickers because the refresh rate is set too low. Now I know an AMOLED lacks a backlight layer, but it still has to adjust for brightness, so if it uses PWM to do so, then I have to presume it will cause the subtle flicker leading to the same problems that I've experienced with LED-LCD displays. Is there anyone here who could possibly shed some light (no pun intended) on this issue?
Yes, it uses PWM. My suggestion is to buy the phone, and if it bothers you, utilize the return window where you will receive a full refund.
Related
Just wondering because I've seen a few posts already about screen burn-in, but I've had my Nexus since launch and have no problems at all. Is it because the people that are having the issue are using the GSM version and have had it longer? Is it because those people have their screens on all day?
I'm just trying to get a baseline to understand where the problem might be coming from. Don't get me wrong, I'm not in highschool so I have no need to keep the phone screen on 4+ hours a day (I average somewhere around 1:30 a day, but most of that is reading and answering texts/emails)...but just curious.
For anyone with burn-in problems just post which version you have (and when you got it, if you could) and the average screen on-time per day that you have. Maybe this could lead to a "best practice" document to keep it from happening to others!
I am afraid that this might be a redundant post you just made.
There is no physical difference between GSM and CDMA variation's SAMOLED screens. There should be more difference between which factory and/or country it was made than between GSM and CDMA.
I know you have already, but please refer to the posts made on:
http://forum.xda-developers.com/showthread.php?t=1509123&page=2
And I'll re-post the post I made over there on here as well for your information.
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This will probably happen to all of us to some degree sooner or later.
The image retention that lasts 1-3 seconds we might see within a month or two usage is actually one of the characteristics of AMOLED "Ghosting effect"
which is not the same as AMOLED "reverse led fatigue" (or although technically incorrect but more widely understood term "Burn-ins") which maybe seen as permanent image retention shown as yellowish outlines of icons / keyboard outlines, etc.
Sadly, there's really nothing you can do about this problem after the fact, except to change the screen itself if it is really bothersome. Or you may try to change/delete/make transparent of the permanently placed icons/other objects/pictures to try to reverse these effects.
The only preventive measures would be changing screen rotation from vertical to horizontal, and make sure you don't have the screen on at a stay still image (preferably set auto screen off to 30seconds or so.)
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charlescom said:
I am afraid that this might be a redundant post you just made.
There is no physical difference between GSM and CDMA variation's SAMOLED screens. There should be more difference between which factory and/or country it was made than between GSM and CDMA.
I know you have already, but please refer to the posts made on:
http://forum.xda-developers.com/showthread.php?t=1509123&page=2
And I'll re-post the post I made over there on here as well for your information.
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This will probably happen to all of us to some degree sooner or later.
The image retention that lasts 1-3 seconds we might see within a month or two usage is actually one of the characteristics of AMOLED "Ghosting effect"
which is not the same as AMOLED "reverse led fatigue" (or although technically incorrect but more widely understood term "Burn-ins") which maybe seen as permanent image retention shown as yellowish outlines of icons / keyboard outlines, etc.
Sadly, there's really nothing you can do about this problem after the fact, except to change the screen itself if it is really bothersome. Or you may try to change/delete/make transparent of the permanently placed icons/other objects/pictures to try to reverse these effects.
The only preventive measures would be changing screen rotation from vertical to horizontal, and make sure you don't have the screen on at a stay still image (preferably set auto screen off to 30seconds or so.)
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I'm sorry, you misunderstood my point of the post. I realize the hardware is identical (as far as the screen is concerned), I'm more interested in kind of how much screen on-time has a strong chance of creating permanent burn-in. I have a max of around 1:30 of screen on-time per day and I haven't seen a hint of burn-in...so I'm wondering if there's some magic number of on-time that will cause the problem to a much higher degree.
What I'm really hoping for is that, for instance, if we find people with 2:30 of screen on-time seem to really have the issue but people with 2 hours or less don't...then it might be a helpful practice to kind of keep screen time to a minimum above that. I realize it's not really helpful for most people (because nobody wants to curve their usage), but it's a limitation of the hardware.
Or maybe if a majority of the people with the problem seem to keep on the screen for 15-20 minutes at a time...that would help, as well.
Its going to happen. All amoled screens get it. The 2 verizom demo units at the store here have it really bad cause the screen is on all day. If you use transparent top and bottom bar, full screen in browser, and rotate your screen periodically, you can avoid the issue.
RogerPodacter said:
Its going to happen. All amoled screens get it. The 2 verizom demo units at the store here have it really bad cause the screen is on all day. If you use transparent top and bottom bar, full screen in browser, and rotate your screen periodically, you can avoid the issue.
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Oddly enough none of my previous amoled based devices (captivate, SGSII, Galaxy Note) shows any signs of burn in but GNex shows slight ghosting/slight burn in of the notification bar. It's feintly visible when i open the xda app
It would be great if somebody can test it, thanks in advance.
How to test:
put a camera in front of the screen and play around with the shutter speed and the brightiness of the screen. When lines appears on the screen, its not good => pwm, without lines => good :good:
edit: i had links for pwm explanation, but not enough posts, sorry..
The question is about pulse width modulation, which I'm reading occurs when both of the following are true:
- you are using an LED light source with variable brightness
- you are using a camera with a rolling shutter
http://provideocoalition.com/aadams/story/pulse_width_modulation_is_not_your_friend/
The camera on the note 8 does not have an LED flash, so I think the poster either now knows that it won't be an issue, or is curious as to whether display brightness on the screen is controlled by pulse width modulation or a different technique.
In the latter case, I don't know, and since this is stuff that can't be seen by the eye nor in the viewfinder, but mostly in photo editing suites per the article I link to, I'm not sure why it's an issue here.
Hi roustabout
I think we dont speak about the same topic.
What I mean is the flickering of the display. A good example is found on youtube: Nexus 7: no PWM on LCD
A lot of LCD use this technology to dim, but its not proper dimming, just switch on / switch off the the lcd very quickly.
Some people have problem with this flickering but dont know that theres a problem, so for example dry eyes, getting tired very fast when working on the computer..
I think more the 95% of the usual monitors use this technique.
I hope this helps.
no, we're talking about the same thing:
'curious as to whether display brightness on the screen is controlled by pulse width modulation or a different technique.'
The article I found thinks it's not visible; what you've read or experienced suggests it's problematic.
What I can say is the first-gen ipad was very hard on my eyes; the note 8 is not like that, but not as good as e-ink. Much more fun than e-ink, though!
Hi, my english won't be very good because it's not my native langage.
I'm very sensitive to the flicker caused by PWM (Pulse Width modulation) wich is a technique used in the backlighting of a lot of LCD display to dim the brightness of the screen. I'm a "migraineur with aura" wich is a neurological disease, so like epileptic people my eyes and my brain are very sensitive to all sort of visual stress even the most subliminal one like PWM used at a high frequency. And I wanted to know if the note 10.1 (2014) use PWM to dim the screen at all level of brightness? I m' sure that it use it a least until 50 %, and that it is not PWMed at 100% brightness. Cause at 50% i'm sick litteraly within second, and at 100% i'm ok. But I have not tested all the level between 50 to 100 cause if it's flicker I can have quite a serious seazure, which would leave me ill for days, so it's quite hasardeous for my health. So what i'm doing is that i leave the system brightness to 100% wich of course is too bright, but I dim it with a soft (screen adjuster) that can dim the display without touching the backlight. But it's not a perfect solution cause the display is still using a lot of energy that way and there's a lot amount of blue wavelenght coming from it and i'm sensitive to blue wavelenght too. Basically as you can see, LED backligh is not a very good technology for epileptic people, eye-sensitive or migraineur. (I personally think it's not a healthy tec for anybody)
So, I just wanted to know if someone know if there's an "official" level where the note doesn't use PWM anymore to control the brightness of the screen, I mean below 100? Thanks in advance, and i'm sorry if my post can sound a bit confuse, it's not easy to try to ask and explain something in a langage that's note your native langage. Thanks in advance.
Hi all!
Does anybody know if HTC 10 uses PWM (Pulse-width modulation) for brightness control?
PWM is a cheap and easy technology to manage screen brightness. To adjust brightness PWM-controller rapidly (usually with speed of 230-240 Hz) turns backlight on and off, which in turn could cause headaches and eye fatigue after using the device.
More about PWM: https://en.wikipedia.org/wiki/Pulse-width_modulation
Absence of PWM is one of the key parameters for me. Unfortunately only a few reviewers test flickering and this information is very hard to find. So far, I have not found a single review with PWM test.
Thank you!
21.05.2016 update: Notebookcheck confirmed that HTC 10 is flicker free!
Surely the only way to dim LEDs is with PWM?
Nope, PWM is just the cheapest an the easiest way. Plus controller won't overheat.
But there are other ways to dim LEDs. One of the oldest ways - variable resistor.
Considering humans see appx 60-90 hz I'd say this is a non-concern.
Unless you're a mutant who can see 100hz+ in which case you must go crazy anywhere you go from the constant exposure to higher frequencies.
Sent from my HTC One using Tapatalk
Considering that I had 5 laser eye surgeries this concerns me a lot.
Using a screen with PWM for more that 15 minutes causes eye strain for me. And this is the main reason why I haven't already bought Galaxy S7.
You are lucky that PWM doesn't affect your eye, and probably should google further more: https://www.google.ru/?#safe=off&q=pwm+eye+strain
datafoo said:
Considering humans see appx 60-90 hz I'd say this is a non-concern.
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Where did you get that info? Especially flickering can be seen at even higher frequencies. I personally see flickering on the XPS 15 and it uses PWM at around 362 Hz.
http://www.notebookcheck.net/Dell-XPS-15-2016-9550-InfinityEdge-Notebook-Review.156354.0.html
It's not disturbing but it is noticeable.
http://www.100fps.com/how_many_frames_can_humans_see.htm
Also the difference between 60 Hz and 144 Hz in a monitor is obvious just by dragging windows around.
If you can't see it, fine. But don't go around telling untrue stuff please.
Dr. lele said:
Where did you get that info? Especially flickering can be seen at even higher frequencies. I personally see flickering on the XPS 15 and it uses PWM at around 362 Hz.
http://www.notebookcheck.net/Dell-XPS-15-2016-9550-InfinityEdge-Notebook-Review.156354.0.html
It's not disturbing but it is noticeable.
http://www.100fps.com/how_many_frames_can_humans_see.htm
Also the difference between 60 Hz and 144 Hz in a monitor is obvious just by dragging windows around.
If you can't see it, fine. But don't go around telling untrue stuff please.
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Untrue stuff LOLOLOLOLOL - I believe you're suffering a nocebo effect.
Pardon my incredulity but as I mentioned if you see anything over 100hz you're a mutant (I said 60-90hz) and that appears to be corroborated by your 100fps link. I'm not completely disagreeing with you, I'm however pointing out that you're such a small subset of the population it's rare and hard to validate.
Although FPS and HZ are different we'll bypass the semantics for the fact we're discussing cycles per second in a general fashion.
It must drive you crazy being ANYWHERE with lighting and electricity. At least here in the US electricity runs at appx 60hz so lights (most computer monitors etc) must bother you quite a bit.
Either way, good luck to you. I hope you find what you're looking for.
There is of course a difference between the way LCDs refresh their content and the way CRTs did. Strobing of light can definitely be seen at much higher rates than you said.
Also I never said that it's infuriating or drives me crazy I just said it's noticeable. I have no idea where you get this from.
Tests with Air force pilots have shown, that they could identify the plane on a flashed picture that was flashed only for 1/220th of a second.
That is identifying. So it's pretty safe to say, that recognizing, that SOME light was there is possible with 1/300th of a second.
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That was the part I wanted to show you.
Now the blur on LCDs is a different story, since the lights are on constantly and only the pixels change color at the given rate. But still you cann see the motion blur / dragging of the cursor even on a 144 Hz screen. Albeit much less noticeable than on a 60 Hz one.
If given a 60 Hz display side by side with a 144 Hz panel most people will be able to tell you which one feels more natural.
BTT: I don' think it will be a real poblem even if HTC does use a PWM module. Even though it might be somehow noticeable it won't disturb most people. Also: how often do you use your phone at the lowet brightness.
Yay! HTC 10 is PWM (flicker) free! Confirmed by Notebookcheck: http://www.notebookcheck.com/Test-HTC-10-Smartphone.164311.0.html (in German).
Oscillogram: http://www.notebookcheck.com/fileadmin/Notebooks/HTC/10/response_pwm.jpg
Just want to add that being able to notice it and it affecting you are two different things. Normally you can't notice neon lights flicker but they do and it will strain your eyes and make you tired. That's why bars have started to charge them out to leds.
Sent from my HTC 10
Glad I'm not effected by this crap. I'd hate having to pass on phones I really like just because they use PWM.
Sent from my SM-G935T using Tapatalk
Hi, is this issue still a problem? After some time during gaming you are not able to get the backlight over 50% like on this video:
Dimming
Or it have been solved by the latest updates and you are able to set maximum brightness even after half of an hour of gaming?
I think the dimming issue has been significantly reduced and fixed with the latest firmware.
It still dims but not by much, you might not even notice it at all depending on how much you're into the game or how sensitive your eyes are to light change.
Dimming is fine for me. I think its really feature not an issue for thermal purposes.
I'm more worried in touch delay issue. They marketed this device with high touch response and how come it would have an issue in the hands of customers.
Two words: Android 11.