In message
<64D32EE8B9CBDD44963ACB076A5F6ABB0267F68D@Mailbox-Tech.lecotech.local>,
dated Mon, 13 Jan 2014, "Kunde, Brian" <[email protected]> writes:
They want the LED itself to be bright so it shines through the Light
Pipe with good intensity.
There is a question of whether the light pipe is well designed and
whether the LED is coupled to it correctly. While the principle of the
light pipe is well known, it does need to be designed correctly in order
to be efficient.
LED brightness is a relative thing. If your product is used in a
relatively dark ambient room the indicators appear too bright (get out
the black tape). But it if is installed in a very bright room, then you
get complaints that the customer cannot read the indicators. You cannot
win.
Bring back the CdS cell used in LED bedside radios to control the
display brightness oh, no, we can't because the 1 mg of cadmium kills
at 100 m range. (;-) But there are silicon-based substitutes now.
The LED in question is only rated 150mcd (millicandelas) which
doesn’t seem very high to me. Is there a “Light Intensity” level
in which you have to be concern about being too bright? I would like to
just give Engineering a value and tell them to keep their LEDs below
that level and you will have no problem.
At one time, LEDs were classified as 'sort-of' lasers and there were
very stringent requirements imposed. These were relaxed later.
There is relevant information in IEC/EN 60950-1 4.3.13.5.2 (specifically
in EN 60950-1:2006+A12:2011).
You probably need to look at these:
IEC 62471 Edition 1.0 (2006-07-26) Photobiological safety of lamps and
lamp systems
IEC/TR 62471-2 Edition 1.0 (2009-08-06) Photobiological safety of lamps
and lamp systems - Part 2: Guidance on manufacturing requirements
relating to non-laser optical radiation safety
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
Nondum ex silvis sumus
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
-
----------------------------------------------------------------
This message is from the IEEE Product Safety Engineering Society emc-pstc discussion
list. To post a message to the list, send your e-mail to <[email protected]>
All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html
Attachments are not permitted but the IEEE PSES Online Communities site at
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used
formats), large files, etc.
Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas <[email protected]>
Mike Cantwell <[email protected]>
For policy questions, send mail to:
Jim Bacher: <[email protected]>
David Heald: <[email protected]>
