Re: Flicker in CFLs, linear fluorescent lamps and LEDs.
- From: Victor Roberts <xxx@xxxxxxxxxxxxxxxxxxxxx>
- Date: Tue, 28 Aug 2007 16:00:11 -0400
On Tue, 28 Aug 2007 15:19:19 GMT, "TKM" <nomail@xxxxxx>
wrote:
"RHRRC" <h.lewis@xxxxxxxxxxxxxxx> wrote in message
news:1188288965.951485.243660@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On 25 Aug, 17:43, Victor Roberts <x...@xxxxxxxxxxxxxxxxxxxxx> wrote:
It is generally known that fluorescent lamps operated on.........................<snip>..............
line frequency EM ballasts produce a substantial amount offlickerat twice
the power line frequency: 100 Hz or 120 Hz
depending upon country. Thisflickeris known to cause
create headaches in some people.
The conventional wisdom is that fluorescent lamps operated
on high frequency fluorescent ballasts will not create
headaches. The phosphor cannot respond to variations in UV
intensity at frequencies of 20 kHz and above, and the small
amount of light emitted directly by the mercury will be
modulated at frequencies far too high to be detected by the
eye/brain system.
--
Vic Robertshttp://www.RobertsResearchInc.com
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Some years ago in the UK some work was undertaken on this very topic
of which I have some recollection and which may be relevant if you can
find the source.
The luminairs were switch start (before the days of HF ballsts) in an
office environment and flicker was suspected as being a cause of some
discomfort in some people. Electromagnetism (of course) also raised
its head as a possible cause but it was eventually shown that sub
audio from the fittings was the main culprit.
Maybe someone out there can offer you the reference (my memory is a
fading bloom) to see if it is relevant - I would not want you to spend
ages seeking such only to find that it was 'quack' science!!
regards
Yes, I recall the reference and I should have posted it earlier since it has
been my basic reference on the subject.
It is: G.W. Brundrett, "Human sensitivity to flicker". Light. Res. Technol.
6 (1974), pp. 127?143.
I couldn't find the paper on line; but I've asked LR&T if it is still
available.
Terry McGowan
Thanks Terry. It would be very useful to have a copy.
--
Vic Roberts
http://www.RobertsResearchInc.com
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.
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