03-17-2009 11:20 AM
I received my X200 Tablet with the Superbright LED screen a few months ago, and I have been suffering from severe eye strain and headaches ever since. I knew my woes had something to do with the display itself but I couldn't quite figure out the exact cause until recently. Using my cell phone camera, I discovered that the screen was flickering. Because the refresh rate of the cell phone camera is relatively low, it interferes with the flickering on my LCD screen. Through the cell phone camera, the screen appears to have moving dark vertical or horizontal banding (depending on the cell phone orientation).
Through some internet searches and participation at other forums, I discovered that LED displays uses pulse width modulation (PWM) to dim the display. PWM in effect, flickers the screen on and off at variable rates to create the illusion of a dimmer display. In the case of X200 Tablets equipped with LED backlit displays, the screen flickers 100% of the time when on battery even at the highest brightness level. I'm assuming this is to conserve battery but it wreaks havoc on my eyes and sanity. The only time my laptop stops flickering is when it is plugged in and set to the highest brightness. I now find myself constantly seeking an electrical outlet whenever I want to use my laptop even if my battery is fully charged. This really takes away from the convenince of my laptop. Furthermore, it is usually too bright at the highest brightness level unless I am outside or by a sunlit window. My eyes don't ever seem to get a break with this laptop.
Is anyone else experiencing the same issues. Can others confirm the flicker on their LED backlit display using a cell phone camera? I used the camera on a Samsung cell phone and an iPhone and get the same results. Is there anything that can be done to stop the flicker?
03-29-2009 04:31 AM
Same here with this x200 LED touch panel. Thought this issue would not affect me, but after using the machine at half-brightness I start to get some sort of headache which goes away instantly when I turn up the screen brightness to max and set the gamma to very low (software brightness).
My previous machine has a higher dpi (smaller dots) and I do not have this issue. It has a CCFL backlit screen. This x200 screen flickers at 90Hz which a percentage of the population do react to. Why doesn't Lenovo QA these sort of 'human issues' as we are paying quite a high price for these machines? And no, here in the UK we are fixed to one single non-configurable x200 tablet. There are NO hardware options, so we cannot order a CCFL non-touch screen.
It would be very nice if Lenovo could replace my panel with a non-touch CCFL version to allow me to use the machine at lower than full brightness without getting headaches.
03-29-2009 04:35 AM
Here's a link to this issue on the 'other' X-series tablet forum:
05-18-2009 12:10 AM
I have something new to report for how to get rid of the flickering whenever the tablet is unplugged. Go into the Intel Graphics Properties (for the onboard graphics). Go to Display Settings->Power Settings->Modify Settings->and turn off "Intel(R) Display Power Saving Technology"
This will eliminate the flicker while unplugged (and at maximum brightness). Happy computing!
PS The 90Hz PWM frequency you guys built into this thing is way too low. Don't make your customers sick!
07-31-2009 10:52 AM - edited 07-31-2009 11:49 AM
11-13-2009 09:00 AM
All computer screens flicker, usually too fast for the naked eye to notice. If you use a camera (like on your mobile/cellphone) you're able to pick this up but that's the case on any computer or TV screen. However, mine screen wobbles occasionally like jelly, no headaches, just irritating.
11-13-2009 11:43 AM
Well, in this case, that's not true. If you put the X200 on maximum brightness and make the adjustment to intel power management above, it will not flicker at all, and you can verify this with your digital camera. If you use a lower brightness you will see the PWM on your digitial viewfinder. It makes a huge eyestrain difference.