ghot@s.ms.uky.edu (Allan Adler) (02/14/91)
I am concerned about the effects of electromagnetic radiation from terminals. I own an old vt52 terminal, an old black and white tv and an old EICO oscilloscope. I don't own a computer and instead use the vt52 to log in to mainframes via a modem. I would like to know about the cost of liquid crystal display terminals that I could use to replace my vt52, liquid crystal televisions to replace my old black and white tv set and liquid crystal oscilloscopes to replace my old EICO oscilloscope which isn't much good anyway. This is essentiall a hypothetical question since I probably won't be able to afford whatever is available. But I would still like to know. Allan Adler ghot@ms.uky.edu
mcovingt@athena.cs.uga.edu (Michael A. Covington) (02/14/91)
(1) Keep the old Eico oscilloscope. It has neither a deflection yoke nor a flyback transformer and therefore doesn't have the main sources of ELF emissions. I'd be surprised if it put out any detectable emissions at all. (2) I'm wary of LCD screens because of the loss of readability. I *know* that eyestrain is bad for me. I *don't* know if the oscillating magnetic field from a conventional terminal will do me any harm. (3) How close do you sit to your TV when you watch it? (4) Why are you only concerned about oscilloscopes and TVs and computer terminals? What about the 60 Hz magnetic field from all the wiring in your house? In sum: Exactly what kind of emission are you trying to get away from, and why do you think they are harmful, and what is the total amount of energy involved, and what do you consider to be an acceptably low level?
mcovingt@athena.cs.uga.edu (Michael A. Covington) (02/14/91)
One other thing: Are you clear on the distinction between a magnetic field and electromagnetic radiation? Not the same thing at all, although TVs emit some of both.
adamd@rhi.hi.is (Adam David) (02/15/91)
In <1991Feb13.203003.18739@athena.cs.uga.edu> mcovingt@athena.cs.uga.edu (Michael A. Covington) writes: >(2) I'm wary of LCD screens because of the loss of readability. >I *know* that eyestrain is bad for me. I *don't* know if the oscillating >magnetic field from a conventional terminal will do me any harm. You mean that CRT screens are easy to read without eyestrain? Now that is hard to believe. A non-backlit LCD may lack contrast but at least the surface of the darkened pixels is sharply defined and relaxing to focus on (partially due to reduced flicker). All CRT displays that I have seen suffer from four main problems which make them visually tiring to use: 1) flickering. 2) ion emission. 3) poorly delineated pixel dots (fuzzy edges and depth of surface. It is easier to focus on an opaque surface than on a luminating phosphor). 4) CRT focussing circuitry can at best only approximate a true focus over the whole of the screen area. Some of the new paper-white low-emission hi-rez CRTs that are becoming available are a minor improvement to frying one's brains on older types, but active-matrix LCD screens of reasonable size and response time should be getting cheaper. It won't be so long until people will be saying "CRT, what's that?" -- Adam David. adamd@rhi.hi.is