The Truth About Flourescent Lights? 97
plato is desperate for answers to the following questions: "Help! I, for one, am driven insane (eg., headaches) by the flickering and buzzing of flourescent lights; I know others are plagued by the same problem and am looking for some answers. At what refresh rate do flourescent lights flicker? Why does flickering (eg., flourescent lights, computer monitors with bad refresh rates, strobe lights) cause headaches for some people? What are some better alternatives to flourescent lights for an office environment? How cost effective are they (in the short- and long-term) compared to natural light, (which isn't always an option)."
Try the EMF-L archives. (Score:1)
Get some FAQ on Fluo lighting (Score:1)
Get it right here:
Fluorescent Lamps, etc... Faq [misty.com]
Lots of other interesting info there too. Like Arc Lamps, etc... );-)
Flickering (Score:1)
I've noticed that some fluorescent lights seem to flicker less than others (ie. I never notice flicker at school, but the fluorescent lights in my basement drive me crazy). Do different types of lights flicker at different rates? (maybe some light bulbs have coatings that hold the light energy for longer than others?)
Inaccurate color (Score:1)
Because of this ugly green color cast, and the flicker, I don't use florescent lights in my house for esthetic reasons.
If you are senitive to florecent lighting (Score:1)
Double frequency (Score:1)
Maybe it's possible to buy fluorescent lights with phosphors that glow longer (do they use phosphor in a TL?).
It's also important to notice that some LCD's refresh at almost the same frequency as lighting, which causes _very_ annoying flickering (due to interferention between the light and the LCD refresh).
Although I'm an EE student, I'm not really an expert on this, so don't sue me on this info
Re:A much simpler solution... (Score:1)
I also hate direct light when I'm really deep into a project.
I stick 2 desk lamps in corners of the room, and aim them up.
Re:It's 120 hertz (Score:1)
Re:Holographic lighting? (Score:1)
Why Lights give us a headache (Score:1)
about this. It seems that they have done tests
and when they asked people to read with floresent
lights the eyes moved in a much more jerkey fashion. On the other hand when they switched to a
light that flashed at 20Khz they normal smooth motion returned.
I'm just thankfull that I have abig window and can
mostly leave the overhead lights off here.
Indirect fluorescent (Score:1)
That probably doesn't help, unless you happen to be designing the lighting for your building. But it's something to look for if you do have a choice in the matter.
Lava lamps (Score:1)
Re:headaches or migranes? (Score:1)
2) If you've been to the doctor and had a stress EEG to help diagnose migraine, did they make you close your eyes and put a strobelight over your face? Hmmm... see, I'm a migraine sufferer, my sister is a migraine sufferer, and I know several other migraine sufferers, and most of us believe that flickering lights or lights that are outputting more light in the green-violet spectrum are triggers for migraines. Also, a lot of us absolutely hate prolonged exposure to Blacklights, especially the fluorescent ones, so our theory is that ultraviolet is a trigger (goes with the other fluorescent lights too). Basically, we suggest to other people experiencing bad effects that they go to incandescent or halogen lamps, try to go with natural spectrum bulbs, try to work somewhere with windows (no not the MS kind) so you can have natural light (unless you're a vampire) and definately run the monitor/video card at a setting you can tolerate. Also remember that if you are diagnosed as having migraines and you can document such things as triggers, that according to various legislation (the Americans with Disabilities Act for one) that your employer must attempt to make a reasonable accomodation for you. So they should be able to pay $50 for a decent lamp and bulb, or $250 for that 3dfx Voodoo 3 3500 TV
Re:Holographic lighting? (Score:1)
Re:It's 120 hertz (Score:1)
It's probably fast enough, but ya never know, right?
Re:Holographic lighting? (Score:1)
Halogen Lamps (Score:1)
If you like halogen light, but are concerned about the power consumption or the heat, Sylvania (tm) makes a bulb that goes in a normal incandescent socket but is a halogen bulb. It looks mostly like an incandescent, but the glass is much thicker. I love this bulb for a few reasons:
No, I don't work for Sylvania. :) I just wanted to share the wealth gleened from my quest for acceptable lighting.
Zeitgeist
What!?! If you're drunk, maybe... (Score:1)
The difference between 12 and 24 is fps is QUITE obvious to the casual observer, 24 to 30 is very obvious to somebody watching on a big screen (I'm talking movies), and you have to go to 60 fps before pans (moving the camera sideways) look realistic.
Star Wars:TPM had lots of pans that left me naseated. On a TV screen, you can get away with it -- on a IMAX screen, you just don't do pans. Period. It leaves the audiance seasick as their visual cortex tries to reconcile the "jumping" images.
I'm not all that heavy into cinema, but I'm involved in a Japanese animation club, and I am heavily involved in Rocky Horror, which has occasionally lead me down the path of NTSC vs. PAL, differing aspect ratios, screen media (the actual sheet that is projected upon), and animation rates. I also live right near an IMAX theater that shows nifty space related films, so I've *seen* the difference between various frames per second.
--
Evan
Re:depression? (Score:1)
Problems Here Too... (Score:1)
Re:Refresh rate of lights (Score:1)
-Aaron
Re:A much simpler solution... (Score:1)
Cool White (Score:1)
There are better fluorescent phosphors, but most buildings and offices use cool white.
Re:flourescent or florescent (Score:1)
Re:Try the EMF-L archives. (Score:1)
http://www.wave-guide.org/archives/emf-l/
Re:Made worse by low refresh rate on monitor... (Score:1)
Now, my office has a window, and my offcemate and I each have new, large monitors driven at 72Hz+ refresh rates
Re:A much simpler solution... (Score:1)
Monty
Refresh rate of lights (Score:1)
Re:It's 120 hertz (Score:1)
So all this means that while the light does flicker, it is never completely dark. Sorry to split hairs, but us physicists, have to keep the engineers in check
Re:What about DC Floresents (Score:1)
Re:It's 120 hertz (Score:1)
Re:Indirect fluorescent (Score:1)
However, these types of fluoro's are very expensive and are often very hard to locate... Besides the OEM, I had to find a specialty lighting store to find anyone who knew of the lights I was looking for...
Some facts about flourescent lights (Score:1)
Flourescent lights are not supposed to buzz, hum or flicker. If you have a noisy or flickering light, the bulbs may be starting to wear out, and will need to be replaced. Other common causes are a bad starter (for a starter-type light), loose wiring, a bad connection between the bulb and lamp holder, or the balast is going bad. Also, a bad ground can cause any number of problems.
As another poster mentioned, older flourlescent lamps used a magnetic balast ( esscently a transformor) while newer ones use an electronic balast (usially a switching power supply with some extra circuitry). If the fixtures in your office are more than a few years old, it may be a good idea to replace them.
Re:Candle (Score:1)
Re:A much simpler solution... (Score:1)
Brain Waves (Score:1)
I used to program laser shows, and I know that we had to be VERY careful about not flickering at the same rate for too long. People have actually been driven into seizures from exposure to low frequency flashing lights.
Another thing to keep in mind is the 'beat frequency' of two unrelated sources. For example, a 60 Hz light fixture and a 59.7 hertz monitor (most monitors are slightly off frequency, while the power line is always dead on), produce a
Things don't get much better as you go up in rate. At 72 Hz, you get a 12 Hz beat, which is right in the middle of the range of brain wave activity.
That's what drove me,
Loopy
Web sites? (Score:1)
?How could it be 120Hz? (Re:Flickering) (Score:1)
For the biologists & chemists: Chemically - WHY? (Score:1)
flourescent or florescent (Score:1)
The Truth About Fluorescent Lights (Score:1)
Re:?How could it be 120Hz? (Re:Flickering) (Score:1)
What about DC Floresents (Score:1)
You're not crazy... (Score:1)
I find that 75Hz gives me a headache (on a 19 inch) but 85Hz is just fine.
I hadn't noticed any problems with 100Hz but after reading thoes reports I've stuck to 85Hz for all resolutions.
Back to topic: I also get headaches from flourescent lights, but I know very little about them. I wouldn't live some where that had them, but I have little choice at work.
Re:Made worse by low refresh rate on monitor... (Score:1)
This sounds like a quote right out of a guide to Feng Shui [mistral.co.uk].
Who would have suspected that Confucius knew about fluorescent lights?
--
Epilepsy...everyone "has" it to a degree (Score:1)
Anonymous Coward, get it?
Quality of monitor... (Score:1)
Anonymous Coward, get it?
Re:?How could it be 120Hz? (Re:Flickering) (Score:1)
The flicker, by my hypothesis, is due to incomplete rectification, which would allow some 60Hz component to sneak through. For example look at the spectrum of the slightly perturbed problem Abs[ d + Sin[60 Hz * t] ], where "d" is some small DC offset. The bigger the offset (i.e. the more shoddy the rectification) the bigger the 60Hz component.
This could explain why older and cheaper lights begin to flicker, since their rectifying components may be poorly made and deteriorating.
Re:One Reason to Be Happy About Flickering Fluros (Score:1)
Re:Holographic lighting? (Score:1)
The only times I have problems... (Score:1)
This doesn't seem to happen if I do not have flourescent lights on and am at the terminal, or if I am doing something else in a room with flourescent lights. 'Tis only the two in combination.
Cheers!
Re:depression? (Score:1)
can refresh rates be too high? (Score:1)
Add incandescant lighting!!! (Score:2)
The yellowish mercury free (iron-iodine) lights they are putting in everywhere have an extreme effect on me personally--I really wanted to scream when they took out the old bulbs and put in the new ones (I've been through this at two universities--they could save enough in two years to pay for hiring the electricians to do the switch, plus no hazardous waste mercury bulbs to dispose of from time to time). Others apparently find them less outrageously painful.
I have evolved two solutions:
1. A flourescent desklamp with a natural spectrum bulb. Bulbs from WallMart, about $5. There used to be "office rated" lights with no 60 cycle transformer hum, but now everything is from Taiwan and hums after it gets warm. About $65 versus $95+ for the Swedish ones that don't hum, if you can evern find them (I haven't seen one in years.) The desklamp plus a little natural light will work wonders.
2. A substantial desklamp using either an incandescant bulb (100W) or (best) a really good halogen lamp (50W,about $50, although sometimes on "clearance" for $30 or so). Get the one with the counterbalance, length adjustments on the arms, and 2 intensity levels if you can.
The economics are such that you will never see the really good flourescent illumination again. The mercury free Trimline (tm) bulbs with their reduced power coonsumption will be the choice of building managers for the indefinite future. You have different things going on inside the bulb, and different phosphors, and much lower intensity (the human eye is more sensitive to yellow light, so less light intensity appears bright nonetheless). The old office had 4 or 5 times the illumination level, and the higher powered bulbs seemed to give a more constant illumination--maybe they didn't cool off completely in the ionized core, or somehting. Anyway, those days are gone forever.
beat frequency. (Score:2)
Re:Holographic lighting? (Score:2)
Curiously, though, do you have any idea how much these Solatubes cost? I can't find anything resembling a price on their web site...
Re:Holographic lighting? (Score:2)
Re:Made worse by low refresh rate on monitor... (Score:2)
There might be other ways to reduce the annoyance of 60Hz flicker, such as angling the desk and reflective framed pictures on the wall, or even placing large plants around the desk. Arrangement of the office can have wonderful effects besides increasing window light. It can really liven up a person at work.
One Reason to Be Happy About Flickering Fluros (Score:2)
There's no thinking involved as such in this kind of test: either you see the light flickering or you don't. The bad news is that people of the highest IQ (measured by 6 different kinds of test - it took days!!) could detect flickering down to 16 milliseconds (IQ of 130-140) which is about 62Hz. Lowest IQs tested (90-100) were down around 30ms. The relationship was *roughly* linear.
Hence, next time you're in a room and you're the only one complaining about flickering lights or screens, you might just have to console yourself with the thought that you're the brightest person in the room!
Personally, I had the fastest flicker rate (16ms), I notice flickering lights and screens if I think about it, but don't seem to be adversely affected by fluro lights. Maybe I'm just used to it (my original PC ran at 1024x768 *interlaced* ugg!! I used to think it was horrible to stare at, but strangely, after a few weeks I didn't notice any flicker at all). I'm sure other factors are also involved. (similar to the story of the guy with the upside down glasses, but that's a major digression
By the way, I much, much prefer the new "daylight" fluro tubes you can get, which have a much more natural spectral distribution, making other fluros look yellow or brown by comparison.
So change the lights... (Score:2)
There are phosphors which glow longer, there are ones which produce a different spectrum (combination of colors).
Or, if it's your house, change the light fixture. Start by replacing the "starter" in case a bad one is interfering with the bulb's power. There are also different power circuits available for various bulbs. Or you can change from fluorescent to the various low-energy vapor bulbs. Or put in a track light or X-10 controllers so you can adjust the lighting in different ways to suit the situation...such as giving some chairs spotlights for reading, or turning lights off when watching a movie.
Re:What about DC Floresents (Score:2)
Plus, an inductor is good for regulating the current flow to the bulb.
Compact and other flourescent tubes that run on DC usually use a high frequency oscillator and a small transformer to get the high voltage. With high frequency, you can use a much smaller (physically) transformer and retain the same efficiency. }:)
My preferred lighting placement (Score:2)
In an office environment, you may have trouble getting this unless a doctor recommends it.
Ideally, you have your own office (I hate cubicles, but that's a given) that you can simply turn off the flourescent light in.
Oh yeah, flourescents give off *lots* of noise. You can demonstrate that with a microphone. That may be another "playing card" you can use with your employer.
Answers from a former lighting engineer (Score:2)
Good quality modern fluorescent lights that are operating properly don't have a perceivable flicker. Easy to prove: Hold a stick (pen, pencil ruler) up in front of you while looking at the light. Hold it by the end and shake it back and forth rapidly in an arc. You should see a smooth blur. Do the same thing in front of your monitor. You'll see a strobe effect, several apparently stationary images of the stick or whatever.
(Do this in front of a TV (in the US, NTSC type) and you'll see a curved image of the stick.)
The reason they don't flicker is the same reason you can still see the image at the top of a monitor when the electron beam is scanning the bottom of it - persistence. The phosphor that gives off the light continues to glow after the electrons stop hitting it.
Different phosphors have different persistence, which is a good thing. If you had a long-persistence phosphor on your TV screen you would get trailing images when objects moved rapidly.
Phosphors used in lighting today have fairly long persistence. You may be able to detect the variation using something like a strobe wheel (spinner with lines spaced at regular intervals, often used or found on record turntables), but you shouldn't be able to see it in normal circumstances.
The "flicker" rate is 2x the rate of your AC current - 60hz in the US, 50hz in some other countries. Because the current has a peak voltage in each "direction" once per cycle, you get two peaks and two "troughs" in one cycle, so the correct rate for the US would be 120hz.
Aircraft and some military installations, along with some unusual building installations, use 400hz AC power, which would yield 800 "flickers" per second.
Different phosphors also give off different colors. Depending on what you want to light, you can choose the color. Grocery meat counters are often cited as a place where a warmer, redder light makes the product look better. Graphic design studios would want a more even color for accurate perception of what they are working with.
The pinkish high-pressure sodium vapor lamps actually have a pretty neutral color, unlike the older mercury vapor designs, which are blue to green. Many people didn't like the new style at first because it seemed so pink next to the mercury.
LOW-pressure sodium lamps are monochromatic yellow. They were cheap, they didn't attract as many bugs at night, but you often could not tell the color of a car under them.
If you're getting headaches at work, it's not because you're under fluorescent light. It's most likely that the lighting isn't appropriate to the work you're doing (or there's some other factor like your monitor).
It COULD be because you're under BAD florescent light. Fixtures need to be cleaned, bulbs need to be replaced, and so do ballasts on a regular basis. A fluorescent lamp can loose fifty percent of it's light output before it finally quits. More than sixty percent of the possible output is often lost to dirt on the lamp and fixture.
Cheap fluorescent lamps might not have good phosphors in them, giving bad color and possible 120hz flicker.
Bad ballasts CAN induce a noticeable flicker. They're noisy, and noise causes fatigue, and they're dangerous - they can catch fire and even explode.
One reason STROBE lights or lights without phosphor can cause people problems is that there are natural brain wave patterns that will try to synchronize with the frequency of the strobe. One of these is slightly below 60hz, and early research on Attention Deficit Disorder (ADD) thought that fluorescent lights were speeding this up and causing the hyperactivity of the kids. (For the reasons above, this theory was discarded.)
So if you're getting headaches at work, don't bitch about it being from fluorescent lamps. If the lamps flicker, try to get them serviced. If the ballast gets noisy, it's going to go out soon and needs to be replaced. Report it. Look at other factors such as glare, too much or too little light, bad positioning of your monitor, poor monitor quality, and for those of us over 40, failing near vision. A good rule for the lighting level around your monitor is that objects you see around it should have about the same light level. A black screen with white or other bright colored text against a well-lit bright background will cause problems, as will a white screen with some dark text against a dark or window.
Gallium Nitride (Score:2)
"In principle all these fluorescent tubes, so long and ugly, you could replace with these tiny light emitting diodes in any shape you want. The actual LED is a fraction of a millimetre across."
The output of these devices is equal to that of a conventional tungsten filament bulb.
No matter what it looks like, there isn't a
Re:It's 120 hertz (Score:2)
Re:Full-Spectrum Fluorescent Lights (Score:2)
Holographic lighting? (Score:3)
Has anybody heard of any applications of this idea?
Made worse by low refresh rate on monitor... (Score:3)
Interestingly enough, the people who were screaming in pain were those with 56 or 60 hz refresh rates on the monitors. Replacing the monitors with newer models capable of 72 hz or higher refresh rates eased the problem to tolerable levels.
We solved the problem by using the secondary light system as much as possible (low wattage incandescent floodlights). Management didn't like the "mood lighting" though and would turn on the fuorescents whenever they wandered by.
Eventually we used the ADA (only applies if you are in the US, but I'm sure many countries have similar legislation) to force the fluorescents off (one member of the group had chronic migraines triggered by harsh lighting, especially flickering). It's amazing what you can get declared "reasonable measures" to meet the needs of a "disabled" worker! The ADA is your friend!
A much simpler solution... (Score:3)
-ElJefe
Full-Spectrum Fluorescent Lights (Score:3)
three fold problem (Score:5)
You may be able to replace the existing florescents with compact florescents (electronic ballast). They often use a higher flicker rate, and they use long persistance phosphers that glow longer and reduce flicker (remember the original IBM PC's green monitor - had long persistence phosphers also). Yes, you can get electronic ballasts for standard fixtures that take 48 inch tubes.
Indirect lighting is almost always better for computer users. I usually use a halogen up-light (six foot tall "torch" that points at the ceiling). Reduces glare, and reduces flicker (any light source based on a hot filament has minimal flicker since the filament tends to stay at a pretty constant temperature).
The best, of course, is north facing windows. Excellent light quality (perfect color temperature, zero flicker), and no glare. Damn few archictects know or care about this (Frank Lloyd Wright taught us this in the 1910s or so), sadly. Shame on the jerks that design "modern" office buildings!
Obviously, you should have the best monitor you can get, running at the highest refresh rate your video card can use with the resolution you need. I'm running 1280x1024x24 @85Hz on a 21 inch monitor.
A forth overlooked problem is that of seating position, but that's not the subject here...
Re:Indirect fluorescent (Score:5)
Ordinary, Low Frequency (LF) Fluorescent likes do have noticable flicker which can certainly upset some (many?) people.
There are many ways of reducing the problem
1) In large installations the lighting should be wired such that each area is lit by lights on all three phases. This reduces the perceived flicker.
2) Where three phase power is not available you can buy "lead/lag" fittings with two tubes wired such that the flicker in each tube is out of phase. These are only available in small sizes and are hard to get.
3) The unpleasant effects do seem to be reduced if the you can bounce the light(s) off another surface
4) But the best solution is to use "High Frequency" Ballasts and tubes. This converts the incoming supply to DC and then uses a high frequency inverter to run the tubes. They offer lower weight and better efficiency than LF Fluorescents. The persistence of the phosphors in the tubes means that there is virtually no flicker present at any frequency.
HF fluorescents have a higher capital cost than LF fittings - but the difference has become much smaller recently. Twin tube fittings are usually cheaper per tube than single tube fittings. You can also get HF control gear which can be dimmed (commonly by a 1-10V DC control voltage).
The phosphors used also have an effect. Older tubes tend to obtain white by mixing of purple with a green/yellow. This gives appaling colouring rendering. There's a measure of this quality called "Ra" which you should be able to check for different types of tubes. An Ra of 40%-50% is typical for older type tubes. Modern tubes are available which use phosphors very similar to those used in colour TV tubes. These have an Ra of about 80%. The offer higher efficiency too. Many people the better "Quality" of light they give reduces the problems they have. These modern phosphors ( often known as "Trisphosphors" ) have a slightly longer persistence - although the difference in flicker levels is small.
You can get tubes with an Ra of almost 100% - but they are rare, expensive and innefficient.
Colout temperature is also important. For domestic environments it is worth getting tubes with a colour temperature of 2700K which is similar to that of incandescent bulbs. This allows different types of light source to "blend" better. Offices tend to use a colour temperature of 3500K or even 4000k - which produces a very tiring "blue" light.
If you are using HF lights then you can get tubes which offer slightly more efficiency. Such tubes must NOT be used in LF lights. If they strike at all the resulting light would be very flickery. It's usually OK to use LF tubes in HF fittings.
When tubes get old the light output starts dropping very fast. This is the time to replace them. as the light output drops the flicker will also being increasing. Most tubes are worn out long before they fail to strike reliably. New tubes frequently swirl for the first few hours of use.
Modern HF fluorescent lights are very much more efficient than other forms of lighting in theory. But in practice though Tungsten Halogen can rival them in many applications because because Halogen lights give a small, point source of light which is easy to control usin reflectors and lenses.
Fluorescents - especially HF types are not a very good choice for things like hallways and stairs which only require to be lit intermittently. This is because they take several minutes to warm up. They light almost instantly - but will only deliver about 5% of their light output, gradually rising to the full level.