Flicker

[Hi Ho]

I know some people see the flickering in different displays (CRT, plasma) and some don't.

I am one that does. It drives me absolutely nuts! I cannot look at a CRT PC monitor set lower than 85hz without getting a serious headache. The same goes for plasma TV's.

However, I can watch my 27in CRT TV for hours and not experience a single flicker or headache. CRT TV's run at 60hz. If I looked at a PC monitor running at 60hz I would be in agony from the horrible flicker. Why is this?

I don't have any problems with DLP rainbow effect. It would seem that this would somehow be related. Are there any explainations for my problem? Does anyone else experience this with CRT and plasma TV's?

 

[Hi Ho]

No one has any explainations for this phenomenon?

 

[sjdgpt]

I cannot look at a CRT PC monitor set lower than 85hz without getting a serious headache. The same goes for plasma TV's.

However, I can watch my 27in CRT TV for hours and not experience a single flicker or headache. CRT TV's run at 60hz. If I looked at a PC monitor running at 60hz I would be in agony from the horrible flicker. Why is this?

I not a physician, but I can propose several answers, and suggest some advice.




Think spatial relationship relative to the refresh rate.

You are physically closer to the PC monitor. You are able to distinguish details on that screen which you would not be able to distinguish on your CRT TV. The low refresh rate on the monitor is actually visible (consciously or subconsciously) to your eye/brain.

(in a way, the plasma monitor has the same problem ... great details)

Technically your eye is tracking the refresh line as it passes across the screen. This tracking movement could be causing eye fatigue and your headaches.

Why you are sitting that close to the PC monitor could be an issue for your eye doctor. You may need an update prescription, or your first pair of eye glasses.


Then there are serious problems.

Way back in high school I dated a girl way that could not sit close to a TV or the screen at the movie theatre. The flicker would cause a specific type of seizure.

There are different types of seizures. Some types of migraine headaches are considered a seizure, or a precursor to a seizure. And light, noise and other stimuli can trigger these seizures.

It is possible that when you are close to a monitor or display, or have a monitor-display that has a relatively low refresh rate (relative to your distance) you are trigger the neurological response that is generating the headaches.

Since these headaches could be a sign of a serious problem, I would not ignore the problem if it continues.



But first, visit the eye doc. Most likely a new pair of glasses will solve your problem.

 

[Hi Ho]

I don't sit any closer to a PC monitor than any other person. I don't see the flicker on a CRT TV even when I get close to it, closer than I do to a monitor.

 

[sjdgpt]

I am assuming you have tried different monitors etc, and the problem is common to all monitors. If so, the problem really must be with you.

As I said before, You are physically closer to the PC monitor. You are able to distinguish details on that screen which you would not be able to distinguish on your CRT TV.


An example, you can read this 12 point text on the PC monitor. If this same text was transmitted to the TV the text would be difficult to see. Yes the text would be blown up (proportionally), but the pixels that form the text on the screen would be displaced further apart with blank pixels between the text pixels most likely making the text inadaquate for clear comprehension.

Bottom line, you can SEE stuff on the PC monitor that you could not see (meaning comprehend) on the TV.

And the refresh rate as an artifact that is seen as a rolling line of white light. When details are great (such as on the PC monitor) or when the refresh rate is low, your eye/brain is picking up this artifact.

In essence, your eyes are moving up and down to catch the artifact as it rolls across the screen. (if your screen was rotated 90degrees and the refresh artifact was now moving right to left or left to right, your eyes would be following that movement)


And eye strain can produce headaches, and is common with people that need new glasses.

So visit the eye doc.

Most likely an eye exam is going to rule out or find a visual problem (just make sure you tell the doc that you are getting headaches from PC monitor and can visualize the refresh artifact).


If the eye doc does not find a source of the problem, I strongly suggest that you visit your family doc for a referral to a neurologist.

 

[Hi Ho]

I wasn't looking for medical advice here. I have been to an eye doctor recently for a check-up and have 20/10 vision. My theory is that I'm simply more sensitive to flicker. I can see the flickering in a dimmed lightbulb, for example, that other people don't notice. I was just curious whether or not other people notice this.

 

[larry7995]

60 HZ on a PC monitor bothers me too. I better get to a doctor right away.
I will have to check the plasma effect, having not been able to afford one just yet.

 

[dm_4u]

Way back in high school I dated a girl way that could not sit close to a TV or the screen at the movie theatre.

Way back in high school...I dated a girl too...those were the days