kurtk@tekcae.TEK.COM (Kurt Krueger) (04/27/88)
>>> 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 > >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,... What you have probably experienced is the fact that your peripheral vision is mainly rods (black & white) which are more responsive to flicker than your center (cones) vision. Also, your eye is less sensitive to flicker if the intensity is lower (I don't know why). So one trick to help a screen that flickers too much is to turn down the brightness. You usually have to adjust the room lighting so you can still see the display. Note that this effect is independant of most everything except absoute brightness of the display, not perceived brightness, contrast, etc. I put a cardboard hood on my display so I could turn it down, otherwise I could NOT work with a white background.
doug-merritt@cup.portal.com (04/29/88)
Getting down to brass tacks, flourescent light flicker can be annoying;
if the flicker rate were higher it wouldn't be. Other than possibly
the spectrum.
So: are there any commercially available gizmo's that you can stick
on flourescent lights that drive them at a higher frequency? Seems
simple in concept but I've never seen one.
Douglarry@kitty.UUCP (Larry Lippman) (04/30/88)
In article <4902@cup.portal.com>, doug-merritt@cup.portal.com writes: > Getting down to brass tacks, flourescent light flicker can be annoying; > if the flicker rate were higher it wouldn't be. Other than possibly > the spectrum. > > So: are there any commercially available gizmo's that you can stick > on flourescent lights that drive them at a higher frequency? Seems > simple in concept but I've never seen one. There are commercially available fluorescent lighting systems which use high frequency excitation. The primary motivation for such use is more efficient energy utilization, and not flicker reduction, however. Using an appropriately designed ballast and exciting a fluorescent fixture at say, 3 kHz, will result in energy savings of 50% or more over an equivalent 60 Hz fixture. Since the excess energy goes to heat, not only is there electrical power reduction, but also reduced load on HVAC systems to remove room heat. General Electric makes high frequency fluorescent lamp systems which operate from 277 volts (i.e., 480/277 3-phase), and which excite at 3 kHz. These are strictly intended for large installations in commercial buildings; I don't know of any single-fixture systems for 120 volts. Interestingly enough, while the energy savings from the use of high frequency fluorescent lamp excitation are significant, the actual number of installations are still few and far between. I suspect that the reason is high installation cost. <> 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?"
pavelz@tekigm2.TEK.COM (Pavel R. Zivny) (05/03/88)
In article <2499@kitty.UUCP> larry@kitty.UUCP (Larry Lippman) writes: > There are commercially available fluorescent lighting systems >which use high frequency excitation. The primary motivation for such >use is more efficient energy utilization, and not flicker reduction, >however. > Using an appropriately designed ballast and exciting a fluorescent >fixture at say, 3 kHz, will result in energy savings of 50% or more >over an equivalent 60 Hz fixture. Since the excess energy goes to >heat, not only is there electrical power reduction, but also reduced >load on HVAC systems to remove room heat. I am sorry to stretch the subject so much, but could you please describe more in detail where do the energy savings really come from ? I thought that the usual ballast in the fluorescent light is an inductor, which actually has secondary task to help with starting the tube. Of course, the inductor itself doesn't waste but little percentage of the wattage of the whole thing; consequently, even if the balast would be replaced with an ideal device, savings woudn't be all that great. The only warm thing inside the fluorescent light fixture is the tube - does the higher frequency change the distribution of energy between heat and light ? thanks -Pavel
larry@kitty.UUCP (Larry Lippman) (05/04/88)
In article <2890@tekigm2.TEK.COM>, pavelz@tekigm2.TEK.COM (Pavel R. Zivny) writes: > > There are commercially available fluorescent lighting systems > >which use high frequency excitation. The primary motivation for such > >use is more efficient energy utilization, and not flicker reduction, > >however. > > I am sorry to stretch the subject so much, but could you please > describe more in detail where do the energy savings really come from? Two reasons: 1. High frequency (3 kHz to 20 kHz) excitation will directly ionize the mercury vapor in the fluorescent lamp more efficiently than at 60 Hz, resulting in more lumens/watt of illumination. 2. With ballasts being consequently smaller, there is less loss of energy to heat. > The only > warm thing inside the fluorescent light fixture is the tube Not true; consider the ballast! > does the higher > frequency change the distribution of energy between heat and light ? Yes - 1. above. <> 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?"