On the other hand,
would the white interior of a white opto-coupler not provide additional
reflection to the light generated by the diode,
and thus enhance the sensitivity?
(for circuits that are built into a black enclosure? )
Rgds
Rene Charton
"Chileshe, Chris"
<ChrisChileshe@Ea
ton.com> To
Sent by: <[email protected]>
[email protected] cc
Subject
06/01/2006 04:22 RE: Why are some optocouplers white
PM and some black?
Doug,
This is only a part response (addition) to your query.
>> It would seem that a white body would be more translucent and you
>> risk falsely triggering the transistor.
Osram produce a white (SFH421) and black (SFH4271) infrared emitter
specifically addressing this issue of translucency. I have worked with
both devices and can confirm that the side emissions through the white
plastic is not insignificant. There is next to no side emission through
the black plastic. I would hazard a guess that the actual optical
barrier
used in optocouplers is designed for purpose and selection of wavelength
gives some additional immunity.
Rgds
- Chris
From: [email protected] [mailto:[email protected]]On Behalf Of Powell,
Doug
Sent: 31 May 2006 18:03
To: [email protected]
Subject: Why are some optocouplers white and some black?
This is obviously a trivia question but I think is related to product
safety.
My recollection is that early on, some manufacturers designated white
body optocouplers as the only type that had certain attributes, like
agency approvals.
It would seem that a white body would be more translucent and you risk
falsely triggering the transistor.
-Doug
Doug Powell
Advanced Energy Industries Inc.
Fort Collins, Colorado USA
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