Migraine headaches from LED backlighting in x200t

+ Reply to Thread
Page 1 of 3 123 LastLast
Results 1 to 10 of 29
  1. #1
    Pen Pal - Newbie
    Join Date
    Oct 2006
    Posts
    7
    Rep Power
    0

    Default Migraine headaches from LED backlighting in x200t

    Hey everyone,
    I was just wondering if anyone has experienced any problems with their x200t tablet with regards to the backlighting. I have found that I am sensitive to LED backlighting in computers and would like to know if anyone else has experienced the same thing. The x200t seems like a very nice tablet PC but if it gives others the same problems as me then thats just a deal breaker for me.

  2. #2
    Think tank & Designer
    Join Date
    Jan 2008
    Posts
    758
    Rep Power
    10

    Default Re: Migraine headaches from LED backlighting in x200t

    Why is it not a deal breaker if it gives YOU the problem vs everyone else?

    I'd think that LED backlighting would be better for you since its an even spread of light...odd. Have you tried viewing the machine with lower light intensity settings? Are you sure its the backlight and not just the monitor itself? Ie do you have glasses/need glasses/have something like epilepsy?

    It could be the digitizer on the tablet pc...it can sometimes make the screen look grainy or like a grid which could agitate things like epilepsy if you happen to have it.

    Not trying to scare you or anything or say that its all you , but those are just some suggestions.
    Fujitsu Lifebook T5010| Intel C2D T9400 2.53 Ghz | 4GB Ram | 320 GB 7200 HDD | Atheros XSPAN ABGN | Modular Bay Battery | Microsoft Wireless Laser Mouse 8000 (bluetooth)

    A day spent without learning something is a day wasted.

  3. #3
    Pen Pro - Senior Member
    Join Date
    Oct 2007
    Location
    Augusta, GA
    Posts
    1,369
    Rep Power
    13

    Default Re: Migraine headaches from LED backlighting in x200t

    I would have thought one would be more sensative to a CCFL backlight vs an LED one due to the flicker of the flourescent bulb vs the constant light from an LED... but really it is what triggers YOUR migraines. All that you would get in a forum like this is anecdotal evidence, and does that matter really if YOU are uncomfortable? I would never purchase a computer that hurt me, but to each his/her own I suppose.

    Last edited by TabbedOut; 12-03-2008 at 08:32 AM.

  4. #4
    Since 2006? wow...
    Join Date
    Aug 2006
    Posts
    74
    Rep Power
    8

    Default Re: Migraine headaches from LED backlighting in x200t

    Trouble with LED back lighting is how they dim the screens - They use something like PWM, basically flickering the LED back lights on and off - increasing the time it's off to make it appear dimmer. It's simpler and more efficient to vary the light output this way than to do it like a typical light dimmer.

    The down side is in fact yes, the back light can cause headaches because while you may not be able to see it, it is flickering. A quick way to check - go into a dark room and turn up the screen brightness to 100%. Wave your hand infront of the screen; then repeat with the screen turned down all the way. You'll see a similar effect as waving your hand infront of a strobe light or your old style tube-TV.

    What can you do about it? Not a whole lot - it's how it works, but there are two tips:
    1. Keep the brightness at 100% always to minimize flicker.
    2. If it the screen is too bright at 100%, wear sunglasses (I know, it's dorky)

  5. #5
    Since 2006? wow...
    Join Date
    Aug 2006
    Posts
    74
    Rep Power
    8

    Default Re: Migraine headaches from LED backlighting in x200t

    Ooh as an addendum - why isn't this a problem or as big as a problem on standard CCFL back lit screens? CCFLs employ higher switching frequencies. Microsemi, a manufacturer of inverters for CCFL back lights runs at 68+Khz. Typically you can't even perceive any difference after 60-120hz.

  6. #6
    Pen Pro - Senior Member
    Join Date
    May 2007
    Posts
    193
    Rep Power
    8

    Default Re: Migraine headaches from LED backlighting in x200t

    Quote Originally Posted by Cirrus View Post
    I have found that I am sensitive to LED backlighting in computers

    How did you come to this conclusion?
    I have a few LED Lights in my room and they are more comfortable to me than any other Light i have (CFLs and FLs).

  7. #7
    Pen Pro - Senior Member
    Join Date
    Sep 2007
    Location
    Stuttgart, Germany
    Posts
    3,848
    Rep Power
    27

    Default Re: Migraine headaches from LED backlighting in x200t

    @makito:
    Your description is not possible. The PWM frequency shouldn't cause flicker or headaches at all. But I admit, that I don't know the exact frequency.

    Second: The frequency is constant, regardless if bright or dim, that's why it is called Pulse-width modulation, it only varies the width of the pulse.
    So the frequency stays the the same.


    The headaches can come from the smaller font on the 12" display, bad ergonomic position of the display, maybe you always have to look down, I don't know your setup, glossy display and the reflections, too bright, too dark.
    But it's not the LED backlight.

  8. #8
    Since 2006? wow...
    Join Date
    Aug 2006
    Posts
    74
    Rep Power
    8

    Default Re: Migraine headaches from LED backlighting in x200t

    Hehe I stand corrected on my terminology - yes PWM uses a fixed frequency but it's the pulse width that essentially gives he same effectas lowered effective frequency.Well what I really mean is, regardless there is a off time and an on time for the led back lights that he maybe sensitive to.

    Either way would certainly say - don't purchase a computer that doens't agree with your body. you can replace a computer but you can't replace your mind or eyes! Best of luck.

    Quote Originally Posted by Frank View Post
    @makito:
    Your description is not possible. The PWM frequency shouldn't cause flicker or headaches at all. But I admit, that I don't know the exact frequency.

    Second: The frequency is constant, regardless if bright or dim, that's why it is called Pulse-width modulation, it only varies the width of the pulse.
    So the frequency stays the the same.


    The headaches can come from the smaller font on the 12" display, bad ergonomic position of the display, maybe you always have to look down, I don't know your setup, glossy display and the reflections, too bright, too dark.
    But it's not the LED backlight.

  9. #9
    Pen Pro - Senior Member
    Join Date
    Nov 2008
    Posts
    169
    Rep Power
    6

    Default Re: Migraine headaches from LED backlighting in x200t

    Cirrus,

    If you are hesitant of getting an LED display, why don't you just order a X200 with CCFL backlighting????? I don't see the "deal-breaker" dilemma here.

  10. #10
    Pen Pro - Senior Member
    Join Date
    Sep 2007
    Location
    Stuttgart, Germany
    Posts
    3,848
    Rep Power
    27

    Default Re: Migraine headaches from LED backlighting in x200t

    just for completion:
    Thank you makito, who brought me to the idea to measure the PWM signal of my tablet PC with the help of an oscilloscope and a photo resistor.
    I used a photo transistor instead, had no photo resistor

    I measured the frequency of both my Fujitsu T2010 display as well as the display of a Sony VAIO TX2 notebook, both LED backlit.

    The periodic time is T=2ms and so the frequency f=500 Hz.

    The only funny thing was that the T2010 display always used a PWM signal to control the brightness whereas the TX2 disabled the PWM at full brightness.

    Cirrus asked about the Lenovo x200t. I don't have one , but I don't think that it will use a different frequency, because both the Sony and the Fujitsu use the same frequency, whereas both computers are totally different. I think 500Hz is a common used frequency. I don't know it, but I just can't believe that Lenovo uses a much lower frequency for their PWM.

 

 

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
All times are GMT -5. The time now is 05:10 PM.
Powered by vBulletin® Version 4.2.2
Copyright © 2014 vBulletin Solutions, Inc. All rights reserved.
Search Engine Friendly URLs by vBSEO 3.6.1