CRT television alter brainwaves - AVS Forum
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post #1 of 16 Old 04-30-2012, 04:23 AM - Thread Starter
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Just read something interesting. Most likely bogus. Can someone decipher this.

CRT screen flicker causes switch to low alpha state. Flicker occurs in a CRT because the phosphor dims while waiting for the next pass of the electron gun.

LCD screens don't have that flicker because the lighting is done at the pixel level by turning the grids' transistors on and off simultaneously. Videogames are another matter as the framerate of most games is 30 hz. A crt is 60hz while a lcd computer monitor is 30 to 80 khz

LCD tv's go up to 120 hz. The high frequency flicker of lcd's may be worse then the low frequency flicker of CRT's. Increased resolution is supposed to worsen flicker. LCD's have a higher resolution. Dim room lighting makes it worse.

Plasma Tv

Every single pixel in a plasma screen television is it's own little fluorescent light bulb. Each of those 'bulbs' flickers at around 120 Hz 100 Hz is well within the range which can be considered a "Strobe Light" capable of inducing a hypnotic Alpha state in the brain
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post #2 of 16 Old 04-30-2012, 11:48 AM
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Post the article.

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post #3 of 16 Old 04-30-2012, 12:18 PM
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Originally Posted by Floydage View Post

Post the article.

Probably from here.

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post #4 of 16 Old 04-30-2012, 12:45 PM - Thread Starter
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That is correct. I first read about it here, then did a google search and came up with that resuklt.
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post #5 of 16 Old 05-01-2012, 09:37 AM
 
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Quote:
Originally Posted by sefmiller View Post

That is correct. I first read about it here, then did a google search and came up with that resuklt.

The "strobe" effect of displays has been kn own to possibly cause everything from eye fatigue to seizures in some people depending on sensitivity. Imagine what it was like in Europe with 50HZ TVs!

As you have pointed out what also imposes this issue is "sync rate" or refresh of the video source signal. So just because a display has a higher capacity for a screen refresh does not mean it will or will not cause or alter alpha brain issues. That said, cartoons, video games, and other rapidly flashing patterns can and do wreak havoc with eye/brain activity. One wonders of the higher incidence of autism and ADHD.

There are other more subtle things that can help even when watching more common video material. A bias light behind the TV that provides soft, diffused light in the room at night is a great aid to reduce eye strain. Some insist on special "neutral" colors and an "all or nothing" stance on the use of such lights. But most people find that use of a small 15 watt CCFL Bright White spiral type bulb in a small fixture behind the TV increases both perceived black level, reduces eye strain, and keeps direct light from striking the TV screen or your eyes. In many movies the fast action or rapid change of full bight to darker images are responsible for some visual fatigue and possible other brain/eye functions. Trying a CCFL light source of 2700K to 6500K may help. It will depend on the wall color and preference to some degree, but almost any light will help.
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post #6 of 16 Old 05-01-2012, 11:44 AM
 
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Videogames are another matter as the framerate of most games is 30 hz. A crt is 60hz while a lcd computer monitor is 30 to 80 khz

A crt can be refreshed at any rate. NTSC operates at 30 frames per second...like video games.
So do computer monitors. The first part of the paragraph talks about vertical refresh rates, and then they compare that to the horizontal refresh of a computer monitor.
Since the author gets this basic concept wrong, what else is wrong in the article?
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post #7 of 16 Old 05-02-2012, 03:11 AM - Thread Starter
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Quote:
Originally Posted by Phase700B View Post

The "strobe" effect of displays has been kn own to possibly cause everything from eye fatigue to seizures in some people depending on sensitivity. Imagine what it was like in Europe with 50HZ TVs!

As you have pointed out what also imposes this issue is "sync rate" or refresh of the video source signal. So just because a display has a higher capacity for a screen refresh does not mean it will or will not cause or alter alpha brain issues. That said, cartoons, video games, and other rapidly flashing patterns can and do wreak havoc with eye/brain activity. One wonders of the higher incidence of autism and ADHD.

There are other more subtle things that can help even when watching more common video material. A bias light behind the TV that provides soft, diffused light in the room at night is a great aid to reduce eye strain. Some insist on special "neutral" colors and an "all or nothing" stance on the use of such lights. But most people find that use of a small 15 watt CCFL Bright White spiral type bulb in a small fixture behind the TV increases both perceived black level, reduces eye strain, and keeps direct light from striking the TV screen or your eyes. In many movies the fast action or rapid change of full bight to darker images are responsible for some visual fatigue and possible other brain/eye functions. Trying a CCFL light source of 2700K to 6500K may help. It will depend on the wall color and preference to some degree, but almost any light will help.

In fairness, I don't think videogames do flash that often. Most of them are a fixed screen and you use the controller to pan the camera sideways.

The CRT is said to induce changes in brain waves via radiant light and screen flicker. Is this still a problem with HDTVs?

The article I originally quoted is confusing. It say's "LCD screens don't have that flicker because the lighting is done at the pixel level by turning the grids' transistors on and off simultaneously". This makes you think LCD's are okay. Until, "The high frequency flicker of lcd's may be worse then the low frequency flicker of CRT's. Increased resolution is supposed to worsen flicker"

The plasma bit is concerning also, "every single pixel in a plasma screen television is it's own little fluorescent light bulb. Each of those 'bulbs' flickers at around 120 Hz 100 Hz is well within the range which can be considered a "Strobe Light" capable of inducing a hypnotic Alpha state in the brain"

There is no mention of LED TV. Could someone verify some of these statements?
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post #8 of 16 Old 05-02-2012, 05:20 AM
 
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"LCD screens don't have that flicker because the lighting is done at the pixel level by turning the grids' transistors on and off simultaneously". This makes you think LCD's

This makes me think the author doesn't know anything about display devices.
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post #9 of 16 Old 05-02-2012, 02:34 PM
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This is completely unrelated to the frequency of operation of the TV..... the first article did NOT state a certain frequency of operation. It said the light itself was the cause. If the hertz would be the cause you would alter your brainwaves from looking at a light bulb... (yes it flickers all the time at 60hz too!)

The fact is that watching tv as in watching just for watching... is truly a state where you arent thinking and almost relaxing. If that is good or bad is for yourself to choose, but no way the hz or tech has anything to do with how your brain reacts when u watch tv.
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post #10 of 16 Old 05-02-2012, 05:34 PM
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Quote:
Originally Posted by sefmiller View Post

There is no mention of LED TV.

An LED is an LCD with LED backlighting, sort of a misnomer.
-----
I do remember an article stating that greater than 60 Hz would be unnatural for humans. This was back when TVs were first coming out at higher freq's.

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post #11 of 16 Old 05-03-2012, 10:31 AM - Thread Starter
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So frequency is not the issue, but the radiant light emitted from Cathode Ray Tubes has not been discounted.

Some of the websites that mention this talk about mind control & brainwashing, so this may be a wacky conspiracy theory.
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post #12 of 16 Old 05-03-2012, 10:41 AM
 
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Another area of concern with CRT TVs is the issue of xrays. Throughout the years with kids having there faces so close to small CRT screens health care folks wondered about the amount of xrays children and adults received with daily watching. As years went by, coatings, shields, and internal grids in the CRT itself were designed to try and limit the amount of xray emissions.

Well, that's what happens when you apply 25,000 volts or more to a huge 25" to 36" vacuum tube. Of course, it's nothing in the amount of radiation like you get in commercial xray tube when applying 140,000 volts.
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post #13 of 16 Old 05-03-2012, 11:47 AM
 
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Quote:


but the radiant light emitted from Cathode Ray Tubes has not been discounted.

This light is no different than the light produced by fluorescent tubes, white leds, plasma tv's ...the sun. etc.

Quote:


As years went by, coatings, shields, and internal grids in the CRT itself were designed to try and limit the amount of xray emissions.

No, the glass has Lead oxide in it, this effectively absorbs th x-rays. It's been like this since they were invented.
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post #14 of 16 Old 05-03-2012, 11:55 AM - Thread Starter
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So, I can conclude that CRT does not cause low alpha brainwaves. It seems that all explanation have been refuted.
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post #15 of 16 Old 05-03-2012, 03:07 PM
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TV programming causes low alpha brainwaves, not flicker. With the boring shows, bugs, pips, and commercials that are broadcasted, anyone could be put into a trance (or just fall asleep).
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post #16 of 16 Old 05-03-2012, 03:28 PM
 
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Quote:
Originally Posted by SAM64 View Post

No, the glass has Lead oxide in it, this effectively absorbs th x-rays. It's been like this since they were invented.


Yes, that was the initial attempt to limit xrays and it worked to a good extent, especially when CRTs operated at 15KV or less. Later, however, it was deemed not enough especially as anode voltages increased with the size of the CRT itself, plus HV regulation issues arose. And moms and health officials got active, voiced concerns, and the other means I mentioned were also put into use to further limit xrays.

Here is just one link of many others about some of the concern:

http://www.repairfaq.org/samnew/tvfaq/tvaihxray.htm
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