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View Full Version : Anyone else have this problem (LCD Displays)



Naryn
December 2nd, 2003, 10:26 PM
I just recently got myself a new LCD since I was wanting something space-saving to go in my dorm room.

However, while browsing over the past two days, I've noticed that it seems to cause me to have a slight eye strain and eventually can build up to a headache when I read on it for extended periods. Playing games I dont' have any issues.

Anyone else have this problem? Not sure if its just my eyes adjusting or what. The screen is quite bright.

HolyKnight
December 2nd, 2003, 10:46 PM
Turn down the brightness, change the resolution/text size... reading glasses?

Naryn
December 2nd, 2003, 10:55 PM
Got contacts that are the correct prescip, and I'm reading it from far away that glasses couldnt' help.


Just been afraid to mess with brightness: messes with my Counter-stike'ing :D

DocBobo
December 3rd, 2003, 01:42 AM
(Just in case it wasn't obvious)
TFT monitors only support one resolution. If your desktop or game resolution isn't the same, it is recalculated/resized by the monitor to make it fit. In the case of text that means letters can become a little sketchy. It is highly recommended that your desktop size is exactly that of the TFT. Not so much in games, as the constant movement hides a lot of blockiness caused by resizing.

In the properties of the desktop you can change the way fonts are displayed (I'm running a german windows, so I have to guess the names a little). Richt click on the desktop, the select Properties -> effects -> font display
You will find a combobox displaying none / somethingorother / cleartype
Play a little with these settings to see which fits your needs the best.

I hope that helps a bit.

Naryn
December 3rd, 2003, 01:55 AM
Done that too :) Thanks for offering the info though :)



I'm starting to suspect that its just the sheer brightness of the whites of the GU site and several other that I browse.

Like staring at a very bright lightbulb for an hour or more. Not too pleasant. Going to tinker with the brightness and see how that helps.

Lenardo
December 3rd, 2003, 12:18 PM
also check your refresh rate and max it for your monitor

you could have a low rate

Serresrelic
December 3rd, 2003, 03:28 PM
flat panel monitors only support one resolution? o_O

I have a 19-inch flat panel monitor at home that I can adjust the resolution from 640x480 up to 1280x1024 (my current resolution).

Am I missing something?

Kordesh
December 3rd, 2003, 03:59 PM
your refresh rate wouldn't happen to be set to 60htz would it?

Dolby
December 3rd, 2003, 04:28 PM
flat panel monitors only support one resolution? o_O

I have a 19-inch flat panel monitor at home that I can adjust the resolution from 640x480 up to 1280x1024 (my current resolution).

Am I missing something?

Yes your LCD monitor can display other resolutions but it only does 1 of them well.
Read everything that DocBobo said not just the first sentance ;)


If your desktop or game resolution isn't the same, it is recalculated/resized by the monitor to make it fit. In the case of text that means letters can become a little sketchy. It is highly recommended that your desktop size is exactly that of the TFT. Not so much in games, as the constant movement hides a lot of blockiness caused by resizing.

Trastero
December 3rd, 2003, 05:06 PM
Yep, try turning the brighness down. I had the exact same problem. As soon as I got my settings to a comfy point (brightness, etc) I was good to go. Also, make sure your screen is pointed right at you in the vertical plane as well as horizontal. Mine was driving me nuts, and I couldn't adjust the fuzz out. I did a mini-tilt down and it cleared right up.

Serresrelic
December 3rd, 2003, 06:23 PM
Bah, I did read everything Doc said. The problem was I misunderstood what he wrote. There's a difference, but thanks for trying.

DocBobo
December 4th, 2003, 02:53 AM
(to clarify a little more how a TFT monitor works)
a TFT panel actually consists of a matrix of pixels. Each pixel is controlled individually by the monitor's electronics. A pixel isn't just a lamp that glows in diffferent colors, it consists of three subpixels which can glow in the colors of red, green and blue. The intensity (of the glow) of each subpixel determines which color the pixel shows.

These constraints lead to the following technical problems:
A panel has a fix resolution (a pixel horizontal, b pixels vertical), for example 1280x1024. If you want to show a different resolution it has either to be downsized or upsized or shown "in a window" (centered, with a black frame) to make it fit into the TFT's pixel matrix. Older notebooks do this a lot when they boot up in DOS mode, for example.
When a subpixel dies it cannot be replaced. You end up with a pixel that lacks the ability to show all the colors. Those are the little annoying dots on your panel you only see in special cases (white on black, black on white, anything which has high contrast). Most displays are sold with a certain percentage of broken pixels per default, for example "not more than 3 dead pixels per display" which is a percentage of 2.3e-4% (at the given example of 1280x1024 pixels). Very little actually.

Nosferatu
December 4th, 2003, 04:19 AM
Doc, your genius scares me sometimes. *wink*

Woody
December 4th, 2003, 04:36 AM
I think Kordesh has the right of it though.

I had to turn down the refresh rate on my monitor because it gave me skull wracking headaches at the default refresh rate for the resolution I work at.

Nothing else was changed.

Naryn
December 4th, 2003, 04:49 PM
Yep my monitor recommended that I put my refresh rate @ 60megahertz.

That is as low as it will go the way it is set up right now. Does that specific refresh rate have something associated with it? I know higher resolutions can give me headaches like Woody is talking about. Played Counter-Strike on my crt monitor with max resolution for abit since it was supposedly going to help accurracy and it gave me one of the worst headaches I've ever had.

Should I increase the refresh rate?

Woody
December 4th, 2003, 05:07 PM
I had to turn down the refresh rate on my monitor because it gave me skull wracking headaches at the default refresh rate for the resolution I work at

Uhhh? When did I say it was a problem with my resolution?

Satarus
December 4th, 2003, 07:45 PM
60Hz can be hard on the eyes for many people. My friend recomends 70 Hz to avoid headaches.

Naryn
December 5th, 2003, 12:23 AM
What I meant by saying that was that I was having "skull wracking headaches" and I was thinking along the lines that the default refresh rate for the higher resolution was causing the problem, much like what you said Woody.

I'll try to be more specific in the future.


Going to try kicking it up to 70 Satarus and see how it goes then.

Edit: Reworded some of the text. It was quite late.

DocBobo
December 5th, 2003, 03:03 AM
Here we go again...
the refresh rate of a TFT doesn't exactly work like that of a normal monitor. A monitor works much like a TV set, an electron beam is projected on a phosphoric layer and makes certain areas of the phosphor glow in specific colours. It takes the electron beam some time to paint a complete picture (in the case of TVs half-picture, meaning every second line) on the screen. In the case of NTSC 60 half-pictures are drawn line for line per second, in the case of PAL it's 50. This results NTSC in supplying 30 frames/sec and PAL with 25 frames/sec.

Back to monitors, which draw full pictures, at the rate the graphic card supplies them. The problem of the phosphoric layer, it cannot keep the glow up longer than a certain amount of time (which I don't know). Which means, by the time the electron beam is done finishing a screen, it vanishes already at the beginning. By the time the beam starts a new screen the screen actually goes black for a brief time before the circle starts new. That's what causes TVs and monitors to "flicker", the eye still can see the monitor darken inbetween frames.

There's a very simple trick to see if a frequency is okay for your eyes or not. Don't watch the screen directly, focus something behind and besides the monitor. This way you see the screen out of the corner of your eye. If you see the screen flicker then, the frequency is too low for you. I for myself have determined that I can see a screen flicker when the frequency is below 85Hz. Your mileage may differ greatly. Some people can't see the flicker at 60Hz, some still claim to see it at 100Hz.

Back to TFTs.
Here you can see the beauty of a pixel matrix at work. All pixels change their state at the same time, because they are controlled individually by the electronics. The pixels hold their state untill they are told otherwise (or till they lose their energy and go dark, I really don't know). This, however has a downside: it takes some time till the order to switch states has reached a pixel (the bigger a panel, the longer it takes). For a screen to work at 60Hz, the electronics must be able to switch stats 60 times a sec (Hz), which means a switch doesn't take more time than 1sec/60 ~ 16ms. Big displays (at the current technology, 21" upwards) already can't switch that fast. Current standard is around 25ms. This results in "smearing". That is an effect where certain areas aren't refreshed properly, keep their old state to a degree, and thus "smear". Fast movement, for example in games produce this effect. Increasing the frequency to 70Hz would result to force the electronics to switch at a speed of 14ms.

As far as I know, TFTs don't go black inbetween switches, so the eye shouldn't be able to see any flicker effects. This means a frequency change shouldn't make any difference to your eyes. The trick with watching the screen out of the corner of the eye applies here too. If you can see it flicker, try to increase the frequency. Maybe the electronics can switch that fast or it doesn't. In the worst of cases the screen will go dark and windows will return to the old frequency after 15 seconds. However, I have never seen a TFT that works at a frequency >70Hz.

Just to make it clear, I think TFTs don't flicker. For me a TFT at 60Hz works perfectly fine. If someone of you can prove that TFTs indeed do flicker (go black between frames), be my guest to provide a link so I can read up on the technology behind it. :)

Ciarin
December 5th, 2003, 03:20 AM
Doc, tell me all you know about monitors.

DocBobo
December 5th, 2003, 03:56 AM
Already done ;)

Kat
December 5th, 2003, 08:03 AM
I'm having the same problem reading Doc's posts. They give me a skullcracking headache!

I'm just too used to standing there handing him things. While he operates.

( For the New GUers - In addition to my duties as Right Hand Wench in the NPO - I'm also DocBobo's Nurse Assistant. )

PS - Actually Doc I understood that the way you explained it. The fact of which gives me a skullcracking headache!

Grey_Bishop
December 6th, 2003, 09:53 PM
Remember Flat Screens work a bit differently on refresh than CRTs (at least mine does).

Instead of refresh rate it has something else (it may be delay instead of refresh, I can't remember at the moment). That rate can't actually be changed.

The delay is measured in milli or micro-seconds, and you want the lowest value there possible. They can go down to .12

I believe it's refresh rate that's messing you up more than anything else.

Serresrelic
December 6th, 2003, 10:13 PM
I have never seen a TFT that works at a frequency >70Hz.


Actually my TFT monitor is currently set to 75Hz and appears to be working fine. I don't see any blurring or any of the other side effects you mentioned.
I guess I got lucky and picked a good one, woohoo!

As a side note, I switched between 60Hz and 75Hz and there is no visual difference that I can see. No flicker, no nothing. Looks identical.

Edit: For reference in case you're interested Doc, This (http://www.neovo-usa.com/products/S-19.htm) is my monitor.

Naryn
December 6th, 2003, 10:34 PM
I ended up just taking the bloody thing back.

I tried everything you guys suggested and it still wasn't getting better over long periods of time so I figured I'd just get my cash back and lug my 50ish pound CRT with me to campus next semester.

Grey_Bishop
December 7th, 2003, 01:47 AM
On the bright side, CRT monitors are much harder to steal than LCD monitors, which could be an actuall plus if living on campus.

Naryn
December 7th, 2003, 11:13 PM
Heheh, didn't think about it that way :)

Considering the suicide stairwells in my dorm-to-be, I'd love to see someone try to make off with my crt in a hurry :D

DocBobo
December 8th, 2003, 07:01 AM
Actually my TFT monitor is currently set to 75Hz and appears to be working fine. I don't see any blurring or any of the other side effects you mentioned.
I guess I got lucky and picked a good one, woohoo!
As I explained (in length) earlier, at a response time of 10ms the TFT panel could work at 100Hz. Well, in theory. And as you already stated, the difference between 60HZ and 75Hz is already not visible.

Judging from the technical data supplied in the link I'd say that's a very nice TFT indeed. Oh well, maybe I can get one myself when my 21" monitor breaks down. I'd really like to have a little more space on my desk.