LED Backlighting Causing Eye Strain/Headaches?

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ThomasJL

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So now LED backlighting causes eye strain?

What about the dozens of complaints about why CCFL causes eye strain and how LED fixes it?. Which is it?

This just shows how bankrupt these arguments are.
 
Does anyone with other brands of LED-backlit LCDs (Samsung) have these issues?
 
ighardcore said:
Staring at bright lights for long periods of time can cause eye strain :D
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Actually, according to some people who posted in the first thread listed in the original post, the eye strain and headaches occur when they dim the LED backlight. The same people claim that the eye strain and headaches lessen or go away when the LED backlight is at full brightness.
 
ThomasJL said:
Actually, according to some people who posted in the first thread listed in the original post, the eye strain and headaches occur when they dim the LED backlight. The same people claim that the eye strain and headaches lessen or go away when the LED backlight is at full brightness.
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Yeah, and as of April or so, a few people are reporting they have no eyestrain issues on their new Macs. It appears Apple has fixed the issue. The people that are still reporting it have probably gotten old stock.

There's talk that it had something to due with the flicker frequency. I didn't know LEDs flickered at all. I thought they were a constant light source. I know CCFLs flicker but it's at such a high frequency it's pretty much unnoticeable (it certainly is for me).
 
eddieck said:
There's talk that it had something to due with the flicker frequency. I didn't know LEDs flickered at all. I thought they were a constant light source. I know CCFLs flicker but it's at such a high frequency it's pretty much unnoticeable (it certainly is for me).
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LEDs themselves don't, however the way that they are usually dimmed is by turning them on and off very quickly and then varying the duty cycle (ratio of on time to off time). This is much easier and more power efficient than other ways of controlling their brightness, as far as the electronics are concerned, and any time you see an LED dimming or 'breathing', this is what's happening. It's referred to as PWM or pulse-width modulation, and the technique is used for all kinds of different things beside LEDs (you may recognize PWM CPU fans - same idea).

As the backlight gets brighter, the LED is on for more of the time, and the off time gets shorter and shorter. I imagine this would make the PWM effect less noticeable/bothersome to those that might be affected by it.

I'm really not sure whether this could cause eyestrain or not, as the frequencies are typically quite high (in the KHz, similar to typical CCFL frequencies), but it's certainly feasible, and I have noticed that some car taillights have very poor PWM that's visible under certain conditions (sorta like how DLP colour separate works), so perhaps it's just a poor design that operates at too low a frequency.

tl;dr Seems reasonable, but should be solvable with proper design.
 
ThomasJL said:
Actually, according to some people who posted in the first thread listed in the original post, the eye strain and headaches occur when they dim the LED backlight. The same people claim that the eye strain and headaches lessen or go away when the LED backlight is at full brightness.
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Well that explains a lot, my eyes have been terribly stressed lately, and I keep trying to lower the brightness of my monitors to compensate. Ah :(
 
This is completely off topic, but this is one of the many (many, many) reasons why I don't like LCD televisions unless it's a small one relegated to bedroom use. If you are sensitive to such issues, get a plasma.
 
I'm using my Samsung XL2370 with 33 brightness, 67 contrast, and there isn't any more eyestrain than with my previous Samsung 2494HS, rather I found that it is easier on the eyes.
 
eddieck said:
Yeah, and as of April or so, a few people are reporting they have no eyestrain issues on their new Macs. It appears Apple has fixed the issue. The people that are still reporting it have probably gotten old stock.
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No, it appears the issue has not been fixed. On the last page of that Apple thread, people have posted complaints in May and June 2010 about the newest Macs still having the issue: http://discussions.apple.com/thread.jspa?threadID=1677617&start=60&tstart=0
 
For the most part, this kind of shit is psychosomatic. Some people just get it in their head that a given thing causes them problems and then because they think it does, it does.

I've seen this with fluorescents a whole lot. Back in the day, they did bother some people. Their ballasts were magnetic and operated at a 120Hz flicker. That is perceptible by some and caused problems. Still happens from time to time because magnetic ballasts are still around in some places. However most ballasts are electronic now. They cycle at 20,000-40,000Hz. This is not only imperceptible, but also well under the time it takes for the florescence to die down and thus there really isn't any change, perceptible or not.

None the less, people think it causes them problems. Happened at the last place I worked. Guy's wife would whine when she came in, saying the lighting gave her headaches because of the flicker. I checked them with a frequency counter, sure enough they were 40k. Didn't matter, she still said she could see it.

While I'm not saying that it is impossible there are problems, in general I think it is just the same as it ever was, people blaming new technology on things.
 
People may not understand the exact mechanism behind why they're bothered by things, but I don't think it's at all a stretch that they can legitimately identify what it is that causes it. Fluorescent lighting tends to be very harsh in temperature, and often very bright in offices, and it can certainly cause headaches regardless of flicker. I'm fairly sensitive to this myself, I much prefer to work in a dimly lit space than the typical office farm with 4x40W tubes at full power over every 2nd square meter of office space.

I'm also willing to bet that nobody went in with any preconceived notion that LED displays would be worse than what they were using before with respect to eyestrain. Where does the psychosomatic bias come from when I think it's reasonable to say that most people probably expected an overall better experience? Not so quick to make that snap judgment myself this time.

If I had one of these overpriced computers at hand I'd pull out a photodiode and measure it and see if I could perceive anything myself, but alas I'm a mere mortal and can't afford anything so nice (not that I'd buy it if I could).
 
keenan said:
Where does the psychosomatic bias come from when I think it's reasonable to say that most people probably expected an overall better experience?
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What often happens is people blame things on what changed. So they get a new screen, and they feel strain. This is unrelated, it is just a coincidence. However they now blame it on the new thing, and thus feel the strain when using said new thing. This gets fed in to when they search and see others complaining.

I just need more substantive evidence than people complaining online. People complain about -everything- much of it without good reason. Show me the study that backs this up with some validity, otherwise I suspect BS.

As I said, you see this all the time. Another example would be where I currently work. So to start you must understand I work for an electrical engineering department. We have people with PhDs in all various aspects of this stuff.

We have wireless all over the building. I'm talking like 200 APs for 5 floors. They cover EVERYTHING. You never lose a signal, no matter where you go. As such they aren't all hidden away as normal, they are in offices and such. They are just flat objects on the ceiling. Well one professor decided this was bad because of the "radiation" from it and put a shield around his. However, all the APs are centrally controlled and monitored. This had no net effect on the signal level at his chair (I checked) because other APs simply altered their broadcast strength to compensate.

Now this is a guy with a fucking PhD, and one in the correct area. He has all the requisite knowledge and skills to research and understand that WiFi does nothing to humans. However he is being superstitious about it and blaming it for problems. As such he has his little shield on his AP and that makes him feel better, never mind there's on in the hall outside his office, one a couple offices over, etc, etc.

People are not logical about this kind of stuff all too often.
 
eddieck said:
Does anyone with other brands of LED-backlit LCDs (Samsung) have these issues?
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Ive been using a PX2370 for long periods for the last couple months and haven't had any eye strain issues, I have the monitors light sensor enabled and set to Medium sensitivity (Samsung calls the feature MagicLux),

If its dark in my room the monitor's brightness is reduced and if its bright / daytime the brightness is increased to compensate.

"The MagicLux feature measures ambient light and has four settings which automatically adjust the screen to optimum brightness. An intelligent intensity sensor detects the brightness around the monitor and adjusts levels automatically, helping to reduce eyestrain." - quoted from here.
 
Hi Guys. I have had similar problems (eye strain and headache) with LED backlight. Do you know of any 13 inch laptops which do NOT have a LED backlight? many thanks.
 
LED are usually brighter and LED are often paired with glossy displays. Not exactly surprising that people are getting problems with "LED"...
 
I have problems with the color, the blueish white my eyes can't handle, it feels like they are getting burned when I look at led displays, I like them but I just can't handle looking at them.
 
I think it's simply a matter of everyone's eyes being different.

I can look at my LED based Apple displays all day and it's quite comfortable. But 10 minutes with a CCFL backlit matte display and my eyes are a mess.

Honestly I don't know if it's the antiglare coating or the CCFL component that bothers me.
 
brentsg said:
I think it's simply a matter of everyone's eyes being different.

I can look at my LED based Apple displays all day and it's quite comfortable. But 10 minutes with a CCFL backlit matte display and my eyes are a mess.

Honestly I don't know if it's the antiglare coating or the CCFL component that bothers me.
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The apple ones don't bother me much because they aren't as blue, its the samsung tv's that I can't stand for more than 10 seconds those suckers are a real blue white.
 
man this stinks.. I've been using CRT's for years.. had to crank up refresh so my eye's would not bug out.. LCD's came along and I could look at a laptop one fine.. but when I got my first one at home... I got a Dell 531 with a dell LCD.. I could look and code and do whatever for hours on it fine..then I got another new home PC..bad news..I bought a new HP with an ok display.. after about an hour I was on the verge of throwing up.. could not take looking at it.. tried brightness, glare, all the changes I could make.. nada... so figured maybe it was crappy monitor.. so I would take the LCD off the dell and that would fix it.. nope... same monitor on different PC (the new HP) still was bugging my eyes out.. so then I figured maybe its the graphics card... so I swapped cards.. same eye strain..

so then I got a new ACER monitor for HP... I could handle it a tad longer but same eye strain.. put that ACER monitor on my old Dell 531 and I can look at that one fine..

nothing I hook to my laptop can I look at for more than 15 min before I want
to pull my eyes out..

so its all hit or miss and I was hoping the maybe it was the backlighting and depending
on the drivers and cheapness of monitor it would make it better or worse.. and I had high hopes the LED backlighing would maybe cure my issue.. but sounds like it doesnt..

so for now for work all day I use my old CRT monitor .. when that dies.. I'm in deep doo doo... so for people that get the eye strain from LCD's have any of you found any magic
cures ?

I'm just at a loss as to why my Dell works fine at driving one monitor fine with no strain.. but that same monitor bugs me out on a different PC.. so it must be in the way the drivers
send the data to it right ?
 
Sycraft said:
For the most part, this kind of shit is psychosomatic. Some people just get it in their head that a given thing causes them problems and then because they think it does, it does.

I've seen this with fluorescents a whole lot. Back in the day, they did bother some people. Their ballasts were magnetic and operated at a 120Hz flicker. That is perceptible by some and caused problems. Still happens from time to time because magnetic ballasts are still around in some places. However most ballasts are electronic now. They cycle at 20,000-40,000Hz. This is not only imperceptible, but also well under the time it takes for the florescence to die down and thus there really isn't any change, perceptible or not.

None the less, people think it causes them problems. Happened at the last place I worked. Guy's wife would whine when she came in, saying the lighting gave her headaches because of the flicker. I checked them with a frequency counter, sure enough they were 40k. Didn't matter, she still said she could see it.

While I'm not saying that it is impossible there are problems, in general I think it is just the same as it ever was, people blaming new technology on things.
Click to expand...


interesting information, i have noticed at work that with some Dell LCD's and under flourescent lights i see a flicker, but on the monitor and only with about 3 monitors in the office, i assumed it is the lights as i had this problem as a kid and getting headaches in school and offices, being able to notice the flicker of these lights.
 
As has been said, there's many causes of sore eyes.. the main one probably being that our eyes aren't exactly suited to staring at a light all day - whether its an LED or CCFL source :)

However, the most common cause of perceived "flickering" on LCD's hasn't actually been mentioned on this thread, so I thought I might as well mention Inversion.. Most of you should see flickering in at least one of the Lagom Inversion test patterns if you full screen it and cycle through the patterns.. ( http://www.lagom.nl/lcd-test/inversion.php )

So flickering/eye strain etc is not only dependent on things like screen brightness, the surrounding lighting, and the backlight itself, it also depends on what shades your screen is showing and how well it handles them..
 
keenan said:
LEDs themselves don't, however the way that they are usually dimmed is by turning them on and off very quickly and then varying the duty cycle (ratio of on time to off time). This is much easier and more power efficient than other ways of controlling their brightness, as far as the electronics are concerned, and any time you see an LED dimming or 'breathing', this is what's happening. It's referred to as PWM or pulse-width modulation, and the technique is used for all kinds of different things beside LEDs (you may recognize PWM CPU fans - same idea).

As the backlight gets brighter, the LED is on for more of the time, and the off time gets shorter and shorter. I imagine this would make the PWM effect less noticeable/bothersome to those that might be affected by it.

I'm really not sure whether this could cause eyestrain or not, as the frequencies are typically quite high (in the KHz, similar to typical CCFL frequencies), but it's certainly feasible, and I have noticed that some car taillights have very poor PWM that's visible under certain conditions (sorta like how DLP colour separate works), so perhaps it's just a poor design that operates at too low a frequency.

tl;dr Seems reasonable, but should be solvable with proper design.
Click to expand...

All they need to do is add a filter between the PWM and the LEDs so the LEDs are driven with a steady DC voltage. The level of that voltage is still controlled by the PWM. This is how the main power supply in your computer works. It's a lot better than using the visual system of your brain to filter out the flicker.

I use an old CRT for my primary internet computer. It normally runs at 85Hz. The other day I made a change that caused it to drop back to the default 60Hz. AAAARRRGGGG... instant vertigo!

People used CRTs at 60Hz for decades. They just put up with it. But we don't want to go back to that nonsense with LED back lights. Hopefully manufacturers will get a clue.
 
I guess I'm lucky that I'm sensitive to flicker but haven't noticed this.

Valnar said:
This is completely off topic, but this is one of the many (many, many) reasons why I don't like LCD televisions unless it's a small one relegated to bedroom use. If you are sensitive to such issues, get a plasma.
Click to expand...

Unfortunately plasma also has an issue for a select number of folks, google "plasma rainbow effect". I honestly thought I was seeing things (very similar to the DLP rainbow effect) until I googled it and found out I wasn't the only one. It's much more subtle than the DLP effect, but certainly noticeable (at least to my eyes)

munkle said:
I have problems with the color, the blueish white my eyes can't handle, it feels like they are getting burned when I look at led displays, I like them but I just can't handle looking at them.
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Sounds like the displays you looked at needed to be calibrated.
 
Maybe someone will find the info I posted in this thread useful: http://hardforum.com/showthread.php?t=1592611

The electronic ballasts in CCFL backlights may run at 40,000Hz or so, but the PWM used for dimming only runs at about 175Hz and is visible to some people. I've tested several displays using a photoresistor and all cycle between 175 and 220Hz.

LED backlights can be dimmed by adjusting their current, but this is usually not done for bright backlight LEDs because this can cause color shifts and other problems. This leaves PWM as the only real means of dimming the display, and appears to work at the same frequency as CCFLs (though I have not measured it directly). Effects from a small duty cycle can be worse with LEDs because they do not continue to glow for several milliseconds like CCFLs when switched off.
 
I recently got a 19" asus 1440x900 LED backlit screen for portrait mode next to my main monitor. It did bother my eyes at first , but that was because the brightness was ridiculous. I also moved my whole monitor array backwards a bit, so my eyes had to get used to focusing a little further away.
..
... I turned the brightness down in the osd quite a bit, then I turned it down more in my gpu drivers. After further editing the brightness, contrast, gamma, etc It looks great to me now and doesn't bother me at all that I've noticed so far. The headaches I've been getting lately are all sinus headaches from the time of year .. mucky to freezing outside, and dry heat inside.
...
 
I read mr pixel's thread. I understand that issue. The effect he is talking about reminds me of the rainbow effect on DLP's. I can notice that rainbow effect on DLP tv's, but mostly when I am looking out of the corner of my eye or when I turn my gaze from away -> back to a screen to refocus on it quickly. I know lights have different frequencies but I was always under the impression that fluorescent would be more "strobe" than an led due to the gas + ballast tech vs a diode. Its very interesting to learn that dimming is done by strobing either type of backlight with pulses. That sounds strange.
....
.... On a related note - until very recently I had been running a graphics professional fw900 24" widescreen crt at 1920x1200@85hz next to a 27.5" TN at 60hz. When I would switch my gaze between monitors, there would be an adjustment period where my focus would change slightly. I got used to it after a few months (and for 3 years) but the clarity, contrast, and perhaps refresh rate on the crt would take a few seconds to "dial in" on my eyes.
..
....The point I am getting to is that some issues become apparent only when switching your gaze back to a screen type.. like moving your hand from a hot pipe to a cold one, or going from a dim room to a bright one.

...Maybe people will adjust to their new display types, and perhaps certain frequencies at different dimming levels may be more annoying to particular people? How many hz is a typical led strobing at 40%, 50%, 75% brightness? As for reading text, contrast levels can affect ease of text reading drastically. White text on back background and even this forum's default color scheme would exacerbate that kind of "pain". Some monitors have different preset modes for text, movie/media, pc/gaming for just that reason - and the text reading mode is a much paler contrast of course.

Most people I have asked can see the effect on newer monitors when fully dimmed, but not above 50% or so. I seem to be more sensitive than average and can see it at brightness levels as high as 70% on some displays. The main effect, other than annoyance at strange after-images, is that reading text is much more difficult and takes longer. White text on black appears to be the worst case, but black on white is significantly affected as well.
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..
.. Even though lower brightness is supposed to cause the pulse effect, I still think some people may be getting headaches from using them with the brightness (and brightness as pushed by contrast levels) much too high. For me the 19" is great so far after tweaking it. The 19" is a smaller display area so I don't have to move my eyes around much on it though. It is also 250cd/m2 brightness, but I have it dialed way down. The OSD brightness is at 38, and my nvidia panel brightness is ticked way down to 10%, contrast zero.
..
.. I have a 27" 2560x1440 led backlit cinema display due to arrive friday so I'll try to respond here about that after I spend some time tweaking it and using it. It is 375 cd/m2 and I'll be turning that down a lot as well.
...
... Maybe you could buy or make a privacy-screen type thing for your monitor like a neutral density filter for a camera. I used to use on on the projector for my old rear-projector LCD tv but it was a small square of film. I'm not sure what quality materials are available for full screen brightness reduction. It would be like giving your monitor sunglasses lol. Or just crank up the brightness and wear sunglasses. :cool:

This place might be able to provide some info on brightness reduction films..

http://www.gdoptilabs.com/products/film_laminations.htm
 
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when i changed my old monitors with my led display, i had many infiammation of my eyes and photofobia :mad:
specially in the night.

LED is optimal for games, films and pictures, but for text and internet is not the maximus of the life.
 
LED out of the box is like vivid / dynamic setting on a tv at 300% brightness. The light text on dark background of [H] was glowing, and the reply to thread white background was blasting light like a flashlight. I had to turn my 19" LED's brightness and contrast to 38/63 in the OSD, and then in my gpu drivers I turned them down much further to 10% brightness and zero contrast. Only then was the picture "normal". Photos still look good on it, and I have no problems with text. The 27" LED backlit ips will look incredibly better though after I tweak it similarly.. :D

... I will eventually turn the OSD brightness and contrast down further and turn the gpu driver versions up a bit until the 19" display is at the same levels it is at now - so that I'll have more wiggle room for tweaking via the gpu drivers instead of resorting to the OSD which can be a pain in portrait mode.
 
elvn said:
How many hz is a typical led strobing at 40%, 50%, 75% brightness?
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The cycling speed does not vary with brightness, only the amount of time the light is on during each cycle (AFAIK). At least in theory a speed of several megahertz is possible, but most displays seem to use 175-200Hz as standard for CCFL and a similar range for LED.

elvn said:
I have a 27" 2560x1440 led backlit cinema display due to arrive friday so I'll try to respond here about that after I spend some time tweaking it and using it.
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I'd be interested in your thoughts on it, though I'm not a fan of glossy (but that's for another discussion;)).
 
You need to be looking at the panel type also. 8 bit panels do not dither. 6-bit panels (mostly TN) use FRC (frame rate control) to create the perception of in between colors.

"More colors can be imitated with tricks like temporal dithering (also often referred as FRC, it basically means quickly altering the pixel color back and forth between the two nearest colors that the pixel can really display; causes some flickering)"

It is possible that the LED lighting is just more harsh or bright, and the dithering is more noticeable to more people.

The CCFL has the gas which glows, vs an LED which is on and off. So perhaps the CCFL is buffering out some of the blinking....the LED is totally binary.

Either way, I personally notice the flickering of TN panels, like the Dell 1908FP, and its enough to not want to keep them.

So IPS LED and TN LED are going to have different effects because of dithering and non-dithering.

If these 8 bit panels with FRC which they are calling 10-bit......flicker....I will be waiting out another generation of LCDs.
 
@ELVN

Your 19" is led but have little dimensionsand is most light for the eyes.
 
IPS is less strenous than TN when using LED bakclight ?
In the Text reading and internet activity ?
 
I read full height pages on my 19" LED backlit TN without a problem, once I tweaked my settings. The brightness had to go down.. wayyyyyyyy down. Like 37 in OSD and AT 10% in gpu drivers.. not down 10%.. 10% level out of 100. lol. Contrast was like 67 in OSD and I set it to off (zero) in the gpu drivers.

Now I set it lower in OSD so I can keep it a bit higher in the gpu drivers for wiggle room. I just upgraded my gpu last night though so I have some tweaking to do all over again.

The 19" is in portrait mode so is a 1440 height web page, at only 900 wide. It still gives plenty of room for reading documents.

I really have to turn the contrast and brightness down a lot for the screen to not affect my eyes harshly. Otherwise its like looking at a panel with a 100,000 candlelight spotlight behind it.

This setup is still fairly new so to be fair - I will have to give it some more time to see if I notice any problems with the strobing/afterimages effect.
 
I really don't think there is much of a quality control over in China I suspect if the product looks nice in the box and out of the box. Long term use or everyday though is a joke I never heard of photophbia before and inflamation of the eyes but I get that everyday from work =)
I used to ice my eyes down after work it was so bad.
I really want to try a led lcd monitor out next pay period but I'm not hoping for a miracle because I looked at them in the store and my vision blanks out when I look at something else.

I tired oled out and that gives me the same effect...
 
How bright were the the monitors that you viewed? I wonder how many of the issues reported are due to the extreme default brightness of most monitors. When I calibrated my monitors I was shocked at how dim it appeared initially, but once I got used to it the screen was much more pleasant to view.
 
I just bought a led lcd monitor off newegg the 21.1 with 140 reviews I'm hoping maybe the display models in the store might of been too bright? Well if I can't use this at least I'll have the whole led lcd monitor thing out of my system.

I'll post results on here good or bad I have two different computers any motherboard to try out too.
 
I'm still trying to get enough reading time on my 27" LED backlit cinema display to see if I am being required to refocus my eyes too often. I'm just getting the setup going so I really can't tell yet.

I did find this setting that amd drivers use (by default now I think), so I wanted to post it since it can affect text readability. I've read that it can blur text. Maybe it will help some people if they disable it. Its called Morphological Filtering.

http://sites.amd.com/us/game/technology/Pages/morphological-aa.aspx

I'm going to try disabling that for the hell of it when I get home later, and maybe tweak my cleartype settings afterward.
 
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