Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!husc6!think!ames!ucbcad!ucbvax!cbosgd!cwruecmp!neoucom!wtm From: wtm@neoucom.UUCP (Bill Mayhew) Newsgroups: comp.terminals,comp.sys.ibm.pc Subject: Re: screen cover to shield user from emissions Message-ID: <614@neoucom.UUCP> Date: Sat, 4-Jul-87 13:35:34 EDT Article-I.D.: neoucom.614 Posted: Sat Jul 4 13:35:34 1987 Date-Received: Sun, 5-Jul-87 07:38:03 EDT References: <3392@sdcsvax.UCSD.EDU> Organization: Northeastern Ohio Universities College of Medicine Lines: 50 Keywords: screen emissions radiation Summary: Probably not worth your money... LCD screen would be a better bet. Xref: mnetor comp.terminals:341 comp.sys.ibm.pc:5323 About a year ago we tested several different types of terminals and CRT screens for personal computers in our building for emission of ionizing radiation. I don't have quantitative figures at hand, but all screens gave off very little radiation. The safety officer concluded there ought to be little health risk unless you routinely sit within an inch or two of the screen, which isn't likely. Chances are pretty good that the so-called radiation filter screens would not significatly reduce the amount of radiation reaching the user. Remeber that they do very little to reduce the emission from the sides and bottom of the case. There is a very, very tiny amount of merit in the protective CRT screens in that they may tend to reduce, slightly, the static electricity build-up. This ought to slightly reduce the likelyhood of computer crashes due to static discharge. We've found that the most objectionable aspect of CRT screens is that some emit very intense ultrasonic acoustical energy. While I'm not a physician, I'd imagine that this has a greater physiolgical impact on computer users than RF energcy coming from CRTs. Some CRT terminals emit a very high pitched whine (probably ~15 KHz) that I can hear; I've found it very uncomfortable to work at those terminals for more than a short time. My suggestion would be to look into getting a computer that is equipped with an LCD or plasma display type screen, if you are concerned with RF emissions from CRTs. The voltages present in LCDs and plasma screens is quite low: ~200 volts or less. That should prevent any sighnificant high energy radiation from being generated. Note, however, that some plasma screens do emit a discernible audio whine at ~2 KHz. While not dangerous, such a whine might prove distracting if the computer is used in a very quiet area. The newer "turbo" models of the Zenith Z-181 can make quite acceptible desktop units, if you feel avoiding radiation is that important. The above does not reflect any policy or medical opinions of my employer or the State of Ohio. Opinions expressed are strictly personal. Bill Mayhew Division of Basic Medical Sciences Northeastern Ohio Universities' College of Medicine Rootstown, OH 44272-9989 USA phone: 216-325-23511