EM emissions of CRT's

G

GVX

Gawd
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Aug 19, 2004
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I am looking at getting rid of my cheap Compaq FP 5315 and getting a better monitor for gaming. I don't have the money for a high-end LCD w/ a 12ms response time so I'm thinking about stepping back over to Cathode Ray Tube-based monitors.

My main concern about these monitors is the extremely dangerous electro-magnetic field generated by the hot electron gun at the back of the vacuum tube.

Basically, I would like to get your opinions on just how dangerous these monitors are (I could always purchase a faraday sheild like this one here, but the cost of the damn thing would make it cheaper for me just to buy a high-end LCD).

thanks, in advance.
 
Have you ever watched TV? Those big scary cathode ray tubes have been used forever. The people that wrote all of the software you are using probably sat in front of a CRT for 1000's of hours a year. How many software developers die of cancer when they're 30?

Do they emmit radiation? Yes. Will it hasten your death? Probably not by a noticable amount.
 
GVX said:
My main concern about these monitors is the extremely dangerous electro-magnetic field generated by the hot electron gun at the back of the vacuum tube.
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If you were to open a CRT, you'd find that the entire "vacuum tube' is shielded by a metal cover.

If a CRT were to emit strong EM fields and/or X-rays, it couldn't even be sold thanks to numerous regulations.

In fact, it's far more unhealthy to expose yourself to sunlight and/or use a cellphone than sit in front of a CRT 24/7.
 
needmorecarnitine said:
I am writing a paper on how everyone who uses crts will end up dying
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...as opposed to those who use LCDs and will never die? CRTs have been around for as long as computers have had keyboards and there's been no correlation between their usage and an increase in cancer rates, impotency, or 3-eyed fish. After making that post did you go and sit in front of your CRT television? Computer monitors are many times safer than TVs due to the proximity at which they're viewed yet nobody bitches about CRT TVs.
 
In fact, it's far more unhealthy to expose yourself to sunlight and/or use a cellphone than sit in front of a CRT 24/7.
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Cellphones operate somewhere in the range of 900 to 2000Mhz which is in the radio bandwidth of the EM spectrum. EM energy of this level is not capable of damaging genetic material. Come on, 2000Mhz? Visible light is much higher energy than radio waves, and its not damaging to your DNA.

Do they emmit radiation? Yes. Will it hasten your death? Probably not by a noticable amount.
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CRTs use an electron beam aimed at a phosphor-coated screen to excite the phosphors and create visible light. If by radiation you mean visible light, then you are correct. But if by radiation you mean something with high enough energy to be harmful (UV radiation, X-rays, or Gamma Rays), then no, CRT's do not emit "bad" radiation.
 
zan780 said:
Cellphones operate somewhere in the range of 900 to 2000Mhz which is in the radio bandwidth of the EM spectrum. EM energy of this level is not capable of damaging genetic material. Come on, 2000Mhz? Visible light is much higher energy than radio waves, and its not damaging to your DNA.
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The signals emitted by cellphones do appear to be capable of heating up the fluid inside cells, indirectly damaging the cell's DNA. The research done so far on this subject is not conclusive yet, but it seems quite reasonable to assume that having a small radio-transmitter next to (or against) your head is not healthy, and will possibly cause long term damage.
 
"One topic that is often discussed when comparing CRT and LCD displays is that of safety. Although it is not directly connected to image quality, I’ll dwell upon it, too. And I’ll be talking about how dangerous CRT monitors are rather than about the safety of the LCD technology.

First of all, the monitor can be dangerous through radiation. I heard complaints that CRT monitors emit various types of radiation, from alpha particles to gamma radiation. Let’s browse through them one by one.

1) Alpha radiation is a stream of helium-4 nuclei. The cathode-ray tube has no helium to start with, so this radiation can only be the result of some nuclear reactions, which is absurd.

2) Next goes beta radiation, which is a stream of electrons. The cathode-ray tube does have a stream of electrons accelerated to energies of about 25,000 electron-volts (since the operational voltage of the kinescope is about 25 kilovolts), but there is one centimeter of glass between the electron stream and the user – no electron can break through it.

3) Hitting the phosphor, and being stopped by it, the electrons give only part of their energy to it (the phosphor shines due to this energy, by the way), while the remaining energy goes to the so-called bremsstrahlung (deceleration radiation), the radiation emitted by electrons slowed down in matter. The spectrum of the deceleration radiation stretches from zero to the maximum energy of the decelerating particles, i.e. its maximum energy may be 25 keV, which corresponds to very soft X rays (the term soft radiation is applied to a radiation with quantum energy up to a hundred thousand of electron-volts due to its relatively low penetrating property; for comparison, modern X-ray photography works with energies up to 150 keV).

4) Next to the X-ray radiation goes gamma radiation with quantum energies of tens of megaelectron-volts. It is created during nuclear fission reactions or as deceleration radiation when particles of energies of tens of MeV are being slowed down. Evidently, there are no nuclear reactions going on inside the monitor case, and there are no million-volt voltages in it, so it cannot emit gamma radiation.

So, the only type of radiation that may worry you is 3) soft X-ray radiation with an energy of about 25,000 electron-volts. To oppose it, the front glass of each cathode-ray tube (deceleration radiation is always directed forward, in the direction of movement of the particles it is created by) has lead and other metals (with lead alone, the glass eventually becomes blurry), which effectively stop this type of radiation. Thus, the X-ray radiation of the monitor originally has a very soft spectrum and after it has passed through the lead-doped glass of the tube it doesn’t exceed the natural background radiation."



Taken from the Xibit labs article in the sticky
 
Okay, thanks guys. I guess all those negative assumptions made about CRTs are just fallacies.
 
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