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  • tfouto Level 1 Level 1

    I am an electronics&computers engineering.


    unfortunately i dont understand much of LCD technology.


    What we need to solve eye strain was a trio of LCD expert, ophthalmologist and neurologist who dedicated enough time to solve those puzzles...

  • mvanier Level 1 Level 1



    Just to be totally accurate, the Dell U2410 is CCFL-backlit, not LED-backlit.  I'm using one now as I write this, and I'm very happy with it.  However, I have reason to believe that the (LED backlit) U2413, though perhaps not as good as the U2410, would still be much better than most LED-backlit monitors for three reasons.  First, it uses current-controlled dimming down to 20%, after which it uses PWM.  Second, when it does use PWM it runs it at about 8 KHz instead of the 200Hz most monitors use.  Third, the LEDs are a new kind: GB-r LEDs which have a much better color spectrum than conventional white LEDs.  They are a combined green/blue LED with a phosphor to generate red components (hence the name), as opposed to a blue LED with a phosphor to generate mostly yellow.  That doesn't mean that it would be as good as CCFL but I'd be surprised if it wasn't much better than conventional white LEDs.  If anyone has tried this monitor, please let us know what you think!

  • rpmiller4 Level 1 Level 1

    I had my iPhone 4S stolen a few days ago (no problems with this or earlier iPhones). So I went to the apple store to buy an iPhone5S, and had the same problem I have with the last three years of any new LED devices. I'm about to go return the 5S, due to nausea, headaches and pain in my lower legs. It also affects my ability to concentrate.


    I wish Apple didn't make the 16GB version of the 4S unavailable. In an effort to get everyone to get the latest phone, now I'm forced to downgrade to 8GB of disk space.


    This is so frustrating that I want to grab a hammer and hit the 5S as hard as I can on one of those wooden tables when I return it.


    I've already tried the 5, all recent versions of the MBP, the iPad3. I tried a MS Surface Pro, an acer Aspire S7. A Nokia Lumia 920, a Samsung Galaxy S4.


    All of those devices give me headaches. Even the Kindle Fire, and surprisingly, the Kindle Paperwhite if I read it at night with the LED backlight on.


    Has anybody found a modern smartphone or laptop that doesn't cause headaches? The only devices I can use at work are old LCD monitors, and at home I lucked out with a set of ASUS ProArt monitors (these are fluorescent displays). I also bought a Panasonic Plasma TV, and I only get headaches from it if I turn on 3D features.


    Any help would be appreciated. I already had my eyesight checked. The only working theory I have right now is that maybe I have some form of photosensitivity that is causing small seizures when I'm exposed to LED displays.

  • tfouto Level 1 Level 1



    If you have headaches with plasma 3D (polarization), it seems to enforce the theory of polarization i wrote several posts back.


    Can you check with your Panasonic glasses on if your iphone 5s and other models that make you nausea, have colors effects?


    There are other causes related with LED's namely blue light spectrum, which might cause eye strain along symptoms.  

  • ElleAle Level 1 Level 1

    Thank you, kvoth,


    I will stay away from u2413 - you confirmed my suspicion after I read that it has been updated with LED technology compared to the u2410



    About the prism, I have slight nearsightedness but do not wear glasses, because every glasses or contact lenses I've tried gave me nausia and eye strain. I don't have a lazy eye and have no problems focusing my eyes, but when looking at the mirror, one eye is slightly off center compared to the other. One day in a chance encounter an eye doctor suggested I might need a prism. She let me try a frame with prism lenses and I immideately experienced immense relief. She said fitting a right prism is a costly and lengthy process of grinding the prism into the glass by trial and error. When I went to an eye doctor and asked for a prism, he said I do not need one.


    So now you are bringing up prism and that makes me Very curious. More than 10 years had past since my prism "un-experience", may be technology has changed, was the process of getting a prism easy for you?

  • OQ3 Level 1 Level 1

    Just think about how changing a driver or an OS, which often causes the issue with eye strain to appear, could have anything to do with polarization or LED backlight or blue light. I think it doesn't. Software can not make it more polarized, more LED and it doesn't really change the lamp's spectrum. Things you should be talking and thinking about is that software changes the way content on the screen is displayed. A separate issue is PWM, which I am not talking about now, because Apple doesn't seem to use it, but almost every external display will have it, though.

  • tfouto Level 1 Level 1



    I dont think that the problem is with drivers at least in my case. It can be one of the causes. But to me it's not.

    I have a HTC one. I sent it to warranty. They change the display. Other things remain the same. One hurts like bad(it's eye severe pain, not strain), the other dont. The screens are from different manufacters.


    So if drivers could be a cause of the problem, they are not the all story. There are people here who complains on regular LED lightning. Is it drivers? Of course not. And why does people with Iphone 4s with the same IOS7 dont have problems, or have little, and with iphone 5 and the same IOS7 are having severe problems?


    You have to understand that there are several causes to eye strain. The eye is complex mechanism. You cant reduce it to a simple thing.

  • OQ3 Level 1 Level 1

    HTC = PWM suspect. Regular LED lighting flickers more often than not = same effect as PWM. Are you sure the IOS7's are identical? If hardware is slightly different, then drivers should be slightly different. Drivers = software.

  • tfouto Level 1 Level 1

    HTC=PWM? Why? I have a photodiode and didn't measure any Pwm on the HTC.

  • OQ3 Level 1 Level 1

    Sorry. Was only a suspicion, nothing more.

  • rpmiller4 Level 1 Level 1

    I already returned the iPhone 5S. I don't know that it has anything to do with polarization, at least not the way you describe it. When I look at my iPhone 4S at an angle I see a holographic color effect. But it does NOT give me headaches. Same if I use my active 3D glasses to look at it.


    Does anybody know what the spec difference is between the iPhone 4S and the iPhone 5 as far as the display goes? This would be the easiest way to find out why the iPhone 5 makes me feel sick and the iPhone 4 doesn't.


    I can't even update IOS from 7.0.3 to 7.0.4 due to lack of disk space. It would be nice to be able to get a new phone or at least solve this headache problem.

  • tfouto Level 1 Level 1

    I would bet the IPhone 5s would have a much stronger color effect.


    Only an apple technician can answer to difference between iphone 4 and iphone 5 display, but i doubt they answer.


    What i can tell is that the iphone 5s is for sure brighter at 100%, has more contrast, more color saturation. Is this the reason? Probably not.

  • tfouto Level 1 Level 1

    Maybe you could try the Sony xperia z1. It was helpfull to a user, but not so much to other. So maybe you could try and see...

  • rpmiller4 Level 1 Level 1

    The Sony Xperia z1 appears to use a quantum dot display with a blue instead of white LED backlight. I haven't had a chance to test it. Thanks for the suggestion.

  • tfouto Level 1 Level 1



    How did you measure the max. frequency your phototransistor was able to handle?