Sophist888@aol.com
Fri, 2 Apr 1999 09:49:46 EST
From: Sophist888@aol.com Date: Fri, 2 Apr 1999 09:49:46 EST Subject: Re: IFETS-DISCUSS Digest - 31 Mar 1999 to 1 Apr 1999
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Arun writes
<<Dear Howard,
Could you tell me, which screen "Computer screen" or "TV screen"
emits the discrete or Continuous rays?>>
Arun,
Both types of screen emit both discrete and continuous rays. A CRT is an
analog device. The X-Ray is a result of the electron beam passing through the
glass after it has illuminated the tube surface. In either device, the beam
is driven in a very short amount of time (around 1/15000 of a second in TV,
even less in computer monitors) from the left to the right edge of the
screen, then turned off for an even shorter length of time (around 1/100,000
of a second in TV, around the same in a computer monitor) to be sent back to
the left side. So in the sense that the beam is on, it's continuous for that
15,000th of a second. But it's discrete in the sense of being turned on and
off.
I hope this is some sort of answer to your question. The subject of CRT
operation may be fascinating to me, but I think that it is pretty far removed
from the subject of education. The point I tried to make was that CRTs don't
pose a danger in terms of exposure to radiation. We can safely set people in
front of computer screens for long periods of time with little fear of
physical danger. Carpal tunnel syndrome and other repetitive stress injuries
are far more likely to occur. We have much more to worry about in the content
delivered by either medium than we do about the package it's delivered in.
Don't shoot the messenger!
- Howard Solomon
technical instructor
Panasonic Services Co.
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