Flicker, eyestrain or headache when using a monitor with LED backlighting?

Discussion in 'Digital Darkroom' started by frans_waterlander, Sep 16, 2013.

  1. It is reported that some people see flicker or experience eye strain or headaches when working with LED backlit monitors. This would be caused by pulse width modulation where the backlighting is switched on and off rapidly at varying on and off times to change the brightness. If this frequency of on and off switching, the pulse width modulation frequency, is below 500Hz or even 1kHz, these problems are reported by some people and not by others. Although the brightness of most CCFL backlit monitors is also changed using pulse width modulation, this is less of an issue because the CCFL tubes don't turn off completely during the off cycle, because they have some after glow, reducing the on/off contrast.

    Here's my question: have you experienced any of these issues - flicker, eye strain or headaches - when using an LED backlit monitor and if so, which monitor did you use and do you know by any chance the pulse width modulation frequency?
     
  2. Nope, none at all. I have a Dell U2410 and it's much easier on my eyes than any of my old CRT monitors. Years ago I had a very expensive CRT monitor with a very reflective screen and it gave my terrible eyestrain.
     
  3. My inexpensive ViewSonic LED backlit monitor has been very easy on the eyes. Even the older Dell backlit TV/monitor (pre-LED) is easier on the eyes than my aperture grille CRTs. Surprised me because I stuck by my aperture grille CRTs for years, convinced they were better. Silly me.
     
  4. The only difference I saw between switching from my CCFL backlit 22" Dell 2209WA to my current 27" LED LG 27ea63vp is that the bigger screen's wider line of sight reduces the adaptive effect caused by the differences of the darker surround which was more prominent with the Dell due to its smaller screen area.
    Bigger screen is a must for preventing adaptation induced fatigue from perception changes to contrast and brightness between the bright screen and dark surround.
    No scientific data to back this up. It's just I notice a big difference in how I feel when I go back to working on my Dell's smaller 22" screen. Also the Dell had uniformity issues with warm on the right and cool on the left which caused me to focus harder and move the image around to avoid seeing the temp changes to the images I was editing.
    The LG is quite uniform causing very little fatigue.
     
  5. Reported by whom?
     
  6. Tim, I don't think I ever experienced what you call adaptation induced fatigue, even when I used a 20" monitor. I make sure that the area around my monitor is lit to reduce the contrast between the monitor and its surrounding.
    Ellis, It's reported by, among many others, tftcentral. Read their review of the NEC P232W and the separate article linked to in the review's text. And when you google it, you get an earful.
     
  7. I've used a 23" LG IPS backlit monitor for about three years, and have had no problems whatsoever with eyestrain, fatigue or flicker.
    As Lex suggests, it's very easy on the eye - and I've got an eyesight problem which makes me very susceptible to eyestrain and headaches.
     
  8. LED backlit, Frans.
     
  9. Frans, if you suspect severe flicker with your LED display just take a photo of it using a 60 sec. shutter speed and see if you get color bars. I don't with my LED LG 27in. and I even tried it at 30 sec. shutter speed.
    Have you tried contacting NEC about this issue?
     
  10. Tim,
    I'm interested in this issue because I plan to buy an LED backlit monitor, not because I have one already. I've asked NEC why one monitor has a pulse width modulation frequency of 180Hz (anything below 500Hz or even 1kHz may cause issues for some people) and the other two have 8kHz and 20kHz. As en electrical engineer I believe it would be easy to increase the frequency of the 180Hz one to something well above 1kHz. I hate to think that NEC would use 180Hz for the lower cost, 23" monitor on purpose, so they could sell up if people have issues with it, but you never know. I'm waiting for NEC to respond; their chat and next higher level support people didn't even understand the term pulse width modulation frequency, as far as I could tell, and my questions have been bumped up to engineering in Chicago and/or Japan.
     
  11. There are several monitors that reportedly don't use PWM at all for backlight dimming. This article lists a few. Would that resolve the issue?
     
  12. Lex,
    I'm aware that there are LED monitors that don't use PWM and those may be the solution for people that have issues with PWM monitors, as are LED monitors that use a high-enough PWM frequency to not bother anybody. I'm trying to learn as much as possible about this issue and I don't know (yet) if I'm susceptible myself. I strongly prefer NEC SpectraView monitors with LED backlighting and the one I would like to buy has 180Hz, which may or may not be a problem for me, costs about $750; the next one up has 8kHz but costs about $1000. And since I'm on a limited budget...
     
  13. I'm not a vision/disply expert, but 180Hz seems awfully slow; I'd expect--or at least not be surprised-- to get a flicker effect in my peripheral vision when moving my eyes between one side of the screen and the other at that frequency. If you buy one, be sure there's a good return policy.
     
  14. Today, NEC confirmed that they are aware of the potential problems of flicker, eye strain, headaches, etc. caused by the low pulse width modulation frequency (just 180Hz) of the W-LED backlighting of their 23" P232W LCD monitor. They also said there are no plans to increase this frequency, which in my opinion would be very easy to do; similar W-LED backlighting of the 24" P242W runs at over 8,000Hz and is as such problem-free. They advice to buy the P242W, which is US$200 more expensive, if you have issues with flicker, eye strain, headaches, etc. If you consider the P232W, better evaluate before you buy or buy with a solid money-back warranty, which is what I am going to do.
     
  15. Looks like things are going your way, Frans.
    BTW the Solux dude you said you emailed in your PN message to me several weeks ago where you mentioned to him my Solux/Eiko task lamp failure after 40 hours of use and wanting a replacement hasn't contacted me. What gives?
     
  16. Tim, If things were really going my way, NEC would up the LED backlighting PWM frequency of the P232W to well over 1kHz, something very simple to do in my opinion as an electrical engineer. But they won't and if you don't like the product, you can always pay US$200 more for the next model up, something I and many ohters may have to do if the P232W doesn't work out. Nice going, NEC!
    As for SoLux, why don't you give Kevin McGuire a call (the number is on the SoLux website) or email him. I know for a fact that he is busy addressing an issue with one of their products.
     
  17. I went round and round with SoLux management and ownership about replacing the cr@ppy che@p@ss prone-to-failure
    voltage transformers they sold with their task lights . I had about a dozen spare bulbs (silly me, I thought bulb failure was
    the reason they weren't working) that I gave to friend who has his SoLux bulbs in a track system he built with real
    transformers and the task lights and transformers went to the electronics recycler.

    I will never buy or recommend their products again. Great bulb, terrible customer support.
     
  18. Tim, If things were really going my way, NEC would up the LED backlighting PWM frequency of the P232W to well over 1kHz, something very simple to do in my opinion as an electrical engineer. But they won't and if you don't like the product, you can always pay US$200 more for the next model up, something I and many ohters may have to do if the P232W doesn't work out. Nice going, NEC!​
    Well here we go, another Frans conspiracy theory, this time that NEC can't or isn't willing to up the frequency of a display, that this is some attempt to get you to spend more money on a higher end unit when few if anyone has issues with the current display system. And further, anyone that does suffer these rare conditions should know they have sensitivity to such issues and at least purchase the unit from someone that would take it back if indeed you found your head exploded after using it. So, a non issue.
    BTW Frans, whom exactly did you speak to at NEC? You get his/her name? Because I find what you are stating needs to be verified!
     
  19. Let's look at the facts, Andrew, before we fly off the handle: NEC will not increase the P232W LED pulse width modulation frequency and advises that people with issues consider the more expensive P242W or PA242W.
    And now you second-guess me? Fine! Here goes:
    Monitor Level 2
    Sep 25 (1 day ago) [​IMG] [​IMG] [​IMG]
    to me [​IMG]
    Good morning Frans,
    I got a note back from my corporate office. Currently, there are no plans to increase the PWM frequency on the P232W. They did confirm for me, as you discovered, that flickering may occur when the brightness on the display is lowered. The suggestion for customers for whom this is an issue is to use the P242W, or the PA242W which are displays that don't experience this flickering, as you've also discovered.
    That's not the answer I'd hoped to provide, but I do appreciate you bringing that to my attention as it was something I hadn't been familiar with to this point.
    Thanks much,
    Andrew NEC Display Service & Support Telephone:
     
  20. Spearhead

    Spearhead Moderator

    Please do not post email addresses or phone numbers in forum posts, especially if they belong to other people. Harvesters pick up the email for spam and phone numbers for telemarketing, even 800 numbers. You can point people to the appropriate web link. I have removed all email and telephone numbers from this thread.
     
  21. Let's look at the facts...​
    I'm waiting for a single fact based answer: whom at NEC did you speak to. You seem unable to supply that. I'm not asking for an address or phone or e-mail (which you could provide privately), just a full name.
    there are no plans to increase the PWM frequency on the P232W.​
    Probably no reason to do so.
    That's not the answer I'd hoped to provide...​
    The facts are, the answers you receive are rarely if ever what you hoped are provided. Look at the facts just in this thread. You asked what seemed like a simple question: have you experienced any of these issues - flicker, eye strain or headaches?
    In post #2, #3, #4, and #5 and #8 the answers were the same: no.
    You do not own, nor have you viewed or examined the NEC you later decided to name specifically. I know this because you admitted this on the LuLa post you made in addition to the one here. So what's the issue? It may or may not affect you. If so, take it back. You haven't admitted that you are even sensitive to this potential issue that is quite rare anyway.
    In the last couple months, you've started three threads both here and simultaneously on LuLa, two have been shut down by your own doing. I have to wonder if you have an genuine questions to raise based on your responses to the answers you receive.
    So tell us what answers you want in the first place and I'll oblige by telling you what you want to hear and we can move forward. Again, two simple questions before Jeff has to close this tread down:
    1. Whom did you contact at NEC. I simply need an first and last name.
    2. If this low frequency of any display system, NEC or otherwise might affect you, what's the problem in either getting a demo to see if it affects you (then reporting your findings here) OR simply purchasing the unit from any number of sources and returning it IF you suffer some issue?(then reporting your findings here).
     
  22. Andrew, you won't get any response unless you start to observe common courtesy. Pronouncements like "Because I find what you are stating needs to be verified!" go just a little too far.
     
  23. Andrew, you won't get any response unless you start to observe common courtesy.​
    Translation: I (Frans) can't supply the information you require because it would provide the information necessary to disprove (again) my observations.
    How's this: Frans, Please supply the full name of the person at NEC who said what you are suggesting he said. And Frans, please tell the audience here why, if you are so sensitive to low frequency display systems, you are unable to test one out and if not to your liking, simply return it? Thank you for addressing these questions which would better allow us to understand why you started this post. Pretty please. With sugar on top.
    Because I find what you are stating needs to be verified!​
    Trust but verify. It's the part of peer review you seem to have missed in all three of your posts here and on LuLa.
     
  24. There you go again, Andrew: "Translation: I (Frans) can't supply the information you require because it would provide the information necessary to disprove (again) my observations." That's exactly the kind of lack of common courtesy I'm talking about. And your loaded questions are more of the same. As soon as you apply real common courtesy, I'll answer those questions, but it will require you to convince me that you are willing to mend your ways.
     
  25. You two boys need to go find yourselves a motel room. Either that or a cage for your shovel fight.
     
  26. But they won't and if you don't like the product, you can always pay US$200 more for the next model up...​
    Which provides a slightly wider gamut and higher displayable colors, slightly larger display of pixels (1920 x 1080 vs. 1920 x 1200), higher cd/m2, yes, higher refresh and costs (list price) a mere $180 more. The P232W is an entry level offering in the P series! Big deal. IF you don't like the spec's, move up or buy another product.
    One can purchase an Audi A4 or a VW Passat which are very similar but have different prices and options but are from the same company. Again so what? You asked a very general question about LED backlit displays and got half a dozen answers (including mine: no issues), you don't like the possible but unknown affects of one NEC unit. Don't buy one.
    Either that or a cage for your shovel fight.​
    Someone needs to knock some sense into this guy, good suggestion Ellis.
     
  27. B&H has been my prefered store for many years and I haven't had a single issue with them. So I was a little disappointed when they told me that if the low 180Hz frequency backlighting pulse width modulation (PWM) of the NEC P232W-BK-SV would cause issues for me, they would not pay for return shipment. Their rationale is that the monitor is supposed to work at that frequency and as such is not defective and I can't disagree with that. They are right, but not as flexible as I would have liked. B&H has definitely become more rigid in their attitude; a couple of years ago they would replace at their expense any monitor that I would find personally unacceptable for backlight bleeding, something that is not even specified. Oh well, the times they are achanging. So I decided to not even bother and bought the next higher up model, the P242W-BK-SV (with 8,000Hz PWM) from B&H. Great monitor. Calibration is easy and at 4900K and 105 nits I get a great match with my prints illuminated by the 4900K SoLux bulbs.
     
  28. A lot of the feedback on this blog is awesome. I'm helping develop this site http://flicker.boards.net/ and I was wondering if any of you wanted to help with info on certain tv's or computers that made eye strain worse or better. E-mail me at HypersonicHunter@gmail.com if you want to help out.
     

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