harrym@sco.COM (Harry Max) (04/22/88)
Hello world, I just started a new job and now must work under fluorescent lights. My brain seems to be adversely effected my the lights. I have been going home with a lot of eye- and brain-strain. A hardware tech told me that it is possible to phase the lights. He said that there is some way to put the starters or ballasts in phase so that my brain wont hurt. Is this true? If so, how can I do it? Harry Max ucbvax!ucscc!sco!harrym microsoft!sco!harrym
markz@ssc.UUCP (Mark Zenier) (04/26/88)
In article <530@scourge>, harrym@sco.COM (Harry Max) writes: > Hello world, > > I just started a new job and now must work under > fluorescent lights. My brain seems to be adversely > effected my the lights. I have been going home with > a lot of eye- and brain-strain. > > A hardware tech told me that it is possible to > phase the lights. He said that there is some way > to put the starters or ballasts in phase so that > my brain wont hurt. Is this true? If so, how > can I do it? 1) Try to get the building people to replace the ballast with a transisorized unit which will kick the flicker up to several thousand Hz. instead of the usual 120hz. 2) Get a decent chair. Some people will bend over their VDT like a contortionist chipmunk and then start to blame their aches and pains on the computer :-). 3) Adjust the screen so there is no glare from the lighting or windows. 4) Open a window, the air in new office buildings can kill you. Mark Zenier Holder of the Cliff Claven chair at the school of uunet!pilchuck!ssc!markz Unsubstantiated Opinion
lewisd@homxc.UUCP (David Lewis) (04/26/88)
In article <530@scourge#, harrym@sco.COM (Harry Max) writes:
# I just started a new job and now must work under
# fluorescent lights. My brain seems to be adversely
# effected my the lights. I have been going home with
# a lot of eye- and brain-strain.
# A hardware tech told me that it is possible to
# phase the lights. He said that there is some way
# to put the starters or ballasts in phase so that
# my brain wont hurt. Is this true? If so, how
# can I do it?
# Harry Max
I find that I have eye-strain, too, but I think it is more from close
work than from the lighting.
I don't know what the technician was talking about.
I do know, however, that I don't really like the fluorescent lighting
in my windowless office. I've been looking (not very hard) for
something called Vita-lite, which, I understand, is an alternate
fluorescent lighting which produces a much more natural, energizing light.
It may reduce the glare which could be contributing to your head-aches.
--
David B. Lewis {ihnp4,allegra,ulysses,rutgers!mtune}!homxc!lewisd
"More than ninety years ago, H.G. Wells foretold time travel, yet to this day
the time machine stands as an example of a vision unfulfilled."
-- lead sentence from an article on optical storage in Macworld, 4/88, p.155prager@Data-IO.COM (David Prager) (04/26/88)
In article <1182@ssc.UUCP> markz@ssc.UUCP (Mark Zenier) writes: In article <530@scourge>, harrym@sco.COM (Harry Max) writes: > Hello world, > > I just started a new job and now must work under > fluorescent lights. My brain seems to be adversely > effected my the lights. I have been going home with > a lot of eye- and brain-strain. > > A hardware tech told me that it is possible to > phase the lights. He said that there is some way > to put the starters or ballasts in phase so that > my brain wont hurt. Is this true? If so, how > can I do it? What you want to do is control the phase of the power going to the flouresants, not put them in phase. These lights strobe at 60 hz. and can indeed make your eyes silly. If one takes the time and wires the fixtures in staggered way at OPPOSITE phases of the AC line; strobing and it's effects are reduced. ------------------------------------------------------------------- David Prager (w)206-881-6444 (h)206-485-4397 FutureNet Corp 10524 Willows Rd. NE Redmond, WA. ...uw-beaver!entropy!dataio!prager 98073-9746 or whatever works.
moran-william@CS.YALE.EDU (William Moran) (04/26/88)
In article <1182@ssc.UUCP> markz@ssc.UUCP (Mark Zenier) writes: >In article <530@scourge>, harrym@sco.COM (Harry Max) writes: >> Hello world, >> >> I just started a new job and now must work under >> fluorescent lights. My brain seems to be adversely >> effected my the lights. I have been going home with >> a lot of eye- and brain-strain. >> ... stuff deleted >2) Get a decent chair. Some people will bend over their VDT like a >contortionist chipmunk and then start to blame their aches and pains on >the computer :-). This is interesting because the other evening, I was looking at my workstation (a sun 3/60 with a 1600x1280 BW display), and I was getting a headache. Then, I noticed that the edge of the screen looked like it was wavering, but I wasn't sure whether or not it was my imagination, so I asked someone else to take a look at the screen, and he agreed that it looked like it was wavering. Eventually, I discovered that it was the result of having an indirect light on (flourescent), and when I turned that light off everything was fine. Further, I found that no other workstation seemed to have that problem. So, you might try different combinations of lights, as other flourescent lights may not cause problems. William L. Moran Jr. moran@{yale.arpa, cs.yale.edu, yalecs.bitnet} ...{ihnp4!hsi,decvax}!yale!moran Jesus! Did I say that? Or just think it? Was I talking? Did they hear me? Hunter Thompson
carl@aoa.UUCP (Carl Witthoft) (04/26/88)
In article <530@scourge> harrym@sco.COM (Harry Max) writes: >I just started a new job and now must work under >fluorescent lights. My brain seems to be adversely >effected my the lights. I have been going home with >a lot of eye- and brain-strain. > >A hardware tech told me that it is possible to >phase the lights. He said that there is some way >to put the starters or ballasts in phase so that >my brain wont hurt. Is this true? If so, how >can I do it? I dont know much about that unless you are more sensitive than the "average" guy to 60Hz. In any case, have you done what you can to avoid direct glare, etc? Also, fluorescent lights are whiter (actually bluer) than incandescent and often uncomfortable anyway. -- Alix' Dad ( Carl Witthoft @ Adaptive Optics Associates) {ima,harvard}!bbn!aoa!carl 54 CambridgePark Drive, Cambridge,MA 02140 617-864-0201 " Axis-navigo, ergo sum."
jwg1@bunny.UUCP (James W. Gish) (04/27/88)
In article <530@scourge> harrym@sco.COM (Harry Max) writes: >Hello world, > >I just started a new job and now must work under >fluorescent lights. My brain seems to be adversely >effected my the lights. I have been going home with >a lot of eye- and brain-strain. > >A hardware tech told me that it is possible to >phase the lights. I don't know anything about "phasing" the lights, but my solution to the problem was to get my employer to provide full-spectrum fluorescent tubes. The color is as close to "natural" as you can get and the flicker rate is such that I don't get the headaches and eyestrain that I almost always get with regular fluorescents. In addition you will have people stopping by your office for months saying, "Where did you get those weird lights - it looks like you have a skylight in your office!" They're a great conversation piece and their use will spread throughout your workplace. Everyone I know that has gotten them thinks they're great. The brand that I bought is Vita-Lites and they sell for about $12 each. GE also makes a full-spectrum fluorescent. -- Jim Gish GTE Laboratories, Inc., Waltham, MA CSNET: jwg1@gte-labs UUCP: ..!harvard!bunny!jwg1
wtm@neoucom.UUCP (Bill Mayhew) (04/28/88)
We connected a photo cell up to the input of an oscilloscope just to be sure. It would appear that fluorescent lights flash 120 times per second. That is to say, one pulse of light is emitted for each 1/2 cycle excursion of the 60 Hz waveform. Phasing of the power leads to the lights would probably be pretty much irrelevent. (Even if lights in adjacent rows were phased oppositely.) What would help would be to obtain a solid state ballast unit as is used in recreational vehicles. The ballasts operate at high frequencies, thus the flashing is less objectionable. Unfortunaely, some people find the several KHz whine just as annoying as the 120 buzz emitted by conventional lighting. Ce est la vie. --Bill
wtm@neoucom.UUCP (Bill Mayhew) (04/28/88)
In my last article I said that I believed that phase was irrelevent with regards to fluorescent lighting. Perhpas true with single or split phase wiring. If the tubes were fed from 240 or 480 volt three phase circuit, with correct wiring, you could get 360 flashes a second, not true? Since the three phases are separated by T/3, there would be a totoal of 6 peaks (3+ and 3-) per T, separated by T/6. In this case, T=1/60th sec, the fundamental period of the power line frequency (in most, if not all of the USA, that is). As I mentioned, we tried hooking tubes up to a 120 volt single phase circuit, and it didn't seem to effect the signal that we picked up on a photo diode positioned below the tubes. We got the same shape 120 Hz waveform either way. Since it was an impromptu experiment, we did not have a solid state ballast handy for comparison. They don't trust us with the big toys, so we din't have the ability to try a three phase set-up. --Bill wtm@neoucom.UUCP
prv@philabs.Philips.Com (Paul Veldman) (04/29/88)
I will add my $0.02: 1) There seems to be a general misunderstanding about the flickering of fluorescent lamps. Although, for mains frequency operated fluorescent lamps, the major part of the light ripple consists of the second harmonics of the mains frequency, the light ripple that annoys people is generally the (small) ripple at the mains frequency itself. In ideal lamps that component is zero, but in practice it is not. This phenomena is stronger with brand new lamps (that still have to get rid of some impurities) and lamps running towards end of life, where the emitter substance on the electrodes starts to get exhausted. In both cases it is especially noticeable around the electrode area of the lamp. It is caused by a slightly asymmetrical behavior with respect to re-ignition of the lamp after zero-crossing of the current. 2) It was suggested that using a solid state ballast, which operates the lamp(s) in the kHz range (generally between 20 and 60 kHz) eliminates any light ripple. If operated from the mains, this statement is only true if a large energy-buffer (generally a large electrolytic capacitor) is used as an intermediate stage, between mains input and the high frequency converter. Not all solid state ballasts on the market are operated in this way, because there are regulations that have to be met with respect to the amount of distortion in the current you draw from the mains. Therefore part of the designs presently on the market show a high frequency operation of the lamp which is amplitude and/or frequency modulated with (twice) the mains frequency, resulting in a light-ripple of twice the mains frequency (and higher harmonics). As explained above, this generally does not bother people. You do however get rid of the light-ripple component that bothers people (at the mains frequency itself), because generally re-ignition of the lamp is prevented by keeping the lamp on during zero-crossing of the mains. Paul Veldman Standard disclaimers apply. If you plan to flame or e-mail: I won't be back on the net until May 9.
hollombe@ttidca.TTI.COM (The Polymath) (04/30/88)
In article <1143@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes: }We connected a photo cell up to the input of an oscilloscope just }to be sure. It would appear that fluorescent lights flash 120 }times per second. That is to say, one pulse of light is emitted }for each 1/2 cycle excursion of the 60 Hz waveform. ... }... What would help would be to obtain a solid state ballast unit as is }used in recreational vehicles. The ballasts operate at high }frequencies, thus the flashing is less objectionable. }Unfortunaely, some people find the several KHz whine just as }annoying as the 120 buzz emitted by conventional lighting. All of the above is overlooking a rather important physiological point. According to my psych. course in Sensation and Perception, under ideal circumstances the maximum flicker rate detectable by the typical human eye is about 60 hz. That's why projectors in movie theaters open and close their shutters 3 times per frame, yielding an undetectable flicker rate of 72 Hz (and why movies were called the "flicks" before they discovered that trick). Therefore, if fluorescent tubes strobe at 120 Hz, they can't be causing your headache problems. Your eyes are physiologically incapable of detecting the flicker. -- The Polymath (aka: Jerry Hollombe, hollombe@TTI.COM) Illegitimati Nil Citicorp(+)TTI Carborundum 3100 Ocean Park Blvd. (213) 452-9191, x2483 Santa Monica, CA 90405 {csun|philabs|psivax|trwrb}!ttidca!hollombe
madd@bu-cs.BU.EDU (Jim Frost) (05/02/88)
In article <2427@ttidca.TTI.COM> hollombe@ttidcb.tti.com (The Polymath) writes: |According to my psych. course in Sensation and Perception, under ideal |circumstances the maximum flicker rate detectable by the typical human eye |is about 60 hz. That's why projectors in movie theaters open and close |their shutters 3 times per frame, yielding an undetectable flicker rate of |72 Hz (and why movies were called the "flicks" before they discovered that |trick). | |Therefore, if fluorescent tubes strobe at 120 Hz, they can't be causing |your headache problems. Your eyes are physiologically incapable of |detecting the flicker. I think this is more of an average and may be affected by "point of view". For instance, I can quite definitely detect a flicker in florescent lights and also with color televisions. While this flicker is undetectable when I'm looking right at the source, it is periferally detectable. It's a tremendous annoyance when you're talking to someone over a glass-topped display case that's lit internally (such as at a jeweler's). One way to see if something is producing a slightly out-of-visibility flicker is to wave your hand quickly in front of it. If you see multiple images of you hand, it is. Under sunlight you will see a continuous motion. Try it in front of a color television in a dark room. Worse (I think) than flickering is CRT noise. No one seems to care that about 10% of the population (my estimate based on experience) can hear most CRTs the entire time they are on. This is terribly annoying! On the plus side, it enables me to find equipment that is left on at night by walking around and listening. jim frost madd@bu-it.bu.edu
straka@ihlpf.ATT.COM (Straka) (05/03/88)
In article <2427@ttidca.TTI.COM> hollombe@ttidcb.tti.com (The Polymath) writes: >In article <1143@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes: >}to be sure. It would appear that fluorescent lights flash 120 > >All of the above is overlooking a rather important physiological point. >According to my psych. course in Sensation and Perception, under ideal >circumstances the maximum flicker rate detectable by the typical human eye >is about 60 hz. That's why projectors in movie theaters open and close > >Therefore, if fluorescent tubes strobe at 120 Hz, they can't be causing >your headache problems. Your eyes are physiologically incapable of >detecting the flicker. Everyone seems to be missing this one! To my understanding (and as an EE, not as a human-factors type), this flicker is caused not by the 60 (or 120) Hz of the fluorescent lights themselves, or the terminal/computer itself, but the ALIASING of the two frequencies. It seems that the human eye keys on the most significant stimulation that it encounters (sort of like capture ratio, in FM radio terms). For example, take a MacIntosh (black on white screen, of course (~66Hz refresh)), and put it far away from you in an environment rich in fluorescent lighting. If you are more than ~10 feet from the Mac, the fluorescent lights seem to dominate your eyes, and you see some sort of odd flickering. However, if you get close to the Mac, say 2-3 feet, the flicker seems to disappear. I believe that the "capture ratio" phenomenon is what's at work here. Since the light on most computers is white on black, one's eyes don't seem to key on them. The flicker issues are much different for them. -- Rich Straka ihnp4!ihlpf!straka Advice for the day: "MSDOS - just say no."
jimc@iscuva.ISCS.COM (Jim Cathey) (05/04/88)
In article <4608@ihlpf.ATT.COM> straka@ihlpf.UUCP (55223-Straka,R.J.) writes: >It seems that the human eye keys on the most significant stimulation that it >encounters (sort of like capture ratio, in FM radio terms). For example, >take a MacIntosh (black on white screen, of course (~66Hz refresh)), and put >it far away from you in an environment rich in fluorescent lighting. If you >are more than ~10 feet from the Mac, the fluorescent lights seem to dominate >your eyes, and you see some sort of odd flickering. The 9" Macintosh screens are refreshed at 60.15 Hz.
larry@kitty.UUCP (Larry Lippman) (05/04/88)
In article <2443@ttidca.TTI.COM>, hollombe@ttidca.TTI.COM (The Polymath) writes: > > Question: Ignoring the physiology for a moment, why don't they use long > presistence phosphors in fluorescent tubes? That should smooth over any > possible flicker effects. Persistence is one characteristic used in the selection of phosphors for fluorescent lamps. However, from a practical standpoint, there is not much choice in this area since phosphors must also exhibit the following characteristics: 1. Be of inorganic material, stable, and be able to withstand high temperatures and other conditions during lamp manufacture and subsequent operation. 2. Have strong optical absorption at 185 and 253 nm with resultant fluorescence. 3. Have minimum absorption at visible light wavelengths. 4. Have minimum fluorescence in near-IR and near-UV regions. 5. Maximum fluorescence must occur between 40 and 50 deg C. 6. Must retain fluorescent characteristics over long period of time. 7. Must be capable of being prepared in fine powder form. 8. Must have minimum toxicity. Finding a "happy medium" for the above ain't easy. And you want persistence, too? :-) <> Larry Lippman @ Recognition Research Corp., Clarence, New York <> UUCP: {allegra|ames|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> VOICE: 716/688-1231 {hplabs|ihnp4|mtune|utzoo|uunet}!/ <> FAX: 716/741-9635 {G1,G2,G3 modes} "Have you hugged your cat today?"
jimh@ism780c.UUCP (Jim Hori) (05/04/88)
Regarding fluorescents: can anyone cite those studies analyzing behavioral differences and problems related to partial spectrum fluorescents? These studies show marked relief when full spectrum lights are installed - the one I remember clearly is the calming effect of full spectrum lights on school children who were hyperactive under partial spectrum lights. jimh@ism780c.UUCP awopbopaloobop alopbamboom ...............................................................
jmsulliv@phoenix.Princeton.EDU (John M. Sullivan) (05/08/88)
I am posting this for my brother, Charlie Sullivan, who doesn't have
access to e-mail. I will, however, make sure that he gets replies you
send to me at sullivan@fine.princeton.edu John Sullivan
---------------------------------------------------------------------
I work for a company, Lutron Electronics, that makes lighting controls,
including high-frequency fluorescent ballasts and other products that can help
people who are presently unhappy with fluorescent lighting, particularly
near VDTs.
My understanding of the issue of whether or not 120 Hz flicker is visible
is that pure 120 Hz is not visible, at least not to most people, but
that any small amount of a 60 Hz component in the fluctuation of light
level is very easily visible and annoying. This can be caused by any
assymetry between the two halves of the 60 Hz cycle. 60 Hz flicker
is often most visible in the ends of the lamp, as they switch
between being anodes and cathodes. Miswired fixtures, bad lamp socket
connections, bad lamps, and combination air conditioning vents/light
fixtures ("air handling fixtures") all contribute to increasing visible
60 Hz flicker. The filaments in the end of the lamp are normally heated to
make them emit electrons to act as cathodes. If one end is not heated, it will
not work as well when it is supposed to be a cathode, and the whole lamp
can act somewhat like an old vacuum tube diode, and be brighter in one
half cycle than in the other half cycle.
One product our company makes is a high-frequency fluorescent ballast
called Hi-lume. It operates above 20 kHz so that it is inaudible.
It is also more efficient than a normal 60 Hz ballast. (The lamp itself
produces more light and less heat than it would at 60 Hz, and a 60 Hz
ballast has considerable losses in the resistance of its windings, and in
the hysteresis of the magnetic material.) The >40 kHz pulsation of light
is much too fast to be visible. Hi-lume is also capable of controlling
the light level from 100% to 1/2%, which is good for setting a comfortable
light level for working at VDTs. It is available in 120 and 277 volt
versions, and for a variety of lamp types. Although there is never any
visible flicker, there is some 120 Hz variation in light level.
(The circuit was designed to do that to improve power factor.) An
older version, identified by model numbers beginning with PCU
instead of OSPCU, has no light level fluctuation below 20 kHz.
We also have other products for controlling light level of fluorescent
lamps which can be very helpful for reducing eye-strain for VDT users.
Although Hi-lume gives the best dimming performance, other products
include such things as systems that allow using normal 60 Hz ballasts to
to minimize rewiring and installation trouble and cost on retro-fit
instaltions.
For more information you can call our hot-line at 800-523-9466 or
800-222-4509 in PA.kevin@chromo.ucsc.edu (Kevin McLoughlin) (05/12/88)
In article <9890@ism780c.UUCP> jimh@ism780c.UUCP (Jim Hori) writes: >Regarding fluorescents: can anyone cite those studies >analyzing behavioral differences and problems related >to partial spectrum fluorescents? These studies show >marked relief when full spectrum lights are installed - >the one I remember clearly is the calming effect of I've done some science-journalistic work in this general area and could probably give you some references; I'm posting this only because I don't have much luck trying to get through to these UUCP addresses. Write me and I'll probably figure out how to reply. ----------- Susan Nordmark Internet: kevin@chromo.UCSC.edu UUCP: ...ucbvax!ucscc!chromo.kevin Santa Cruz, CA
erict@flatline.UUCP (eric townsend) (05/12/88)
In article <2427@ttidca.TTI.COM>, hollombe@ttidca.UUCP writes: [some discussion about flourescents and flickering and headaches delted] > All of the above is overlooking a rather important physiological point. > According to my psych. course in Sensation and Perception, under ideal > circumstances the maximum flicker rate detectable by the typical human eye > is about 60 hz. That's why projectors in movie theaters open and close > their shutters 3 times per frame, yielding an undetectable flicker rate of > 72 Hz (and why movies were called the "flicks" before they discovered that > trick). > Therefore, if fluorescent tubes strobe at 120 Hz, they can't be causing > your headache problems. Your eyes are physiologically incapable of > detecting the flicker. Are our eyes physiologically incapable of detecting the flicker, or are our tests incapable of detecting the response our eyes have to the flicker? Before I was old enough to understand the difference between flours and incans, flour lights caused me eyestrain and headaches. (This could have been caused by other effects, but I doubt it.) Even now, flour lights bother me... I just stay out of them as much as possible, and try and have incans in whatever office space I'm working. Just curious. -- Know Future Another journalist with too many spare MIPS. J. Eric Townsend ->uunet!nuchat!flatline!erict smail:511Parker#2,Hstn,Tx,77007