Anyone know why some IRLEDs have a blue tinted encapsulation instead of
water clear?

TIA.

On Wed, 16 Jul 2008 17:56:02 +0100, "ian field"
wrote:

Anyone know why some IRLEDs have a blue tinted encapsulation instead of
water clear?


1) It's benign?

2) It's cheaper?

3) For ident/differentiation?

4) Mechanical filtering?

I've seen infra-red leds with almost-black encapsulation.

RL

"legg" wrote in message
...
On Wed, 16 Jul 2008 17:56:02 +0100, "ian field"
wrote:

Anyone know why some IRLEDs have a blue tinted encapsulation instead of
water clear?


1) It's benign?

2) It's cheaper?

3) For ident/differentiation?

4) Mechanical filtering?

I've seen infra-red leds with almost-black encapsulation.

RL

The almost black types are ubiquitous in consumer electronics as the
integrated IR receiver modules, I was wondering why sometimes blue when blue
is at the other end of the spectrum from IR?

"ian field" wrote in message
news


The almost black types are ubiquitous in consumer electronics as the
integrated IR receiver modules, I was wondering why sometimes blue when
blue is at the other end of the spectrum from IR?


As long as it's transparent to IR at (usually) 850-950nM is fine. The
PhotoDiodes used in remote receivers are 'black' to block out ambient light
shorter wavelength than about 850nM.

** Posted from http://www.teranews.com **

On Wed, 16 Jul 2008 21:03:31 +0100, "ian field"
wrote:


"legg" wrote in message
.. .
On Wed, 16 Jul 2008 17:56:02 +0100, "ian field"
wrote:

Anyone know why some IRLEDs have a blue tinted encapsulation instead of
water clear?


1) It's benign?

2) It's cheaper?

3) For ident/differentiation?

4) Mechanical filtering?

I've seen infra-red leds with almost-black encapsulation.

RL

The almost black types are ubiquitous in consumer electronics as the
integrated IR receiver modules, I was wondering why sometimes blue when blue
is at the other end of the spectrum from IR?

Apparently the visible coloration doesn't always relate to
near-visible or IR transmission. Googling.... a Peacock Blue filter is
a black absorber under IR light, while the Congo Blue is transparent,
though one looks a 'lighter' blue than the other.

It turns out that the 'water clear' and darker tinted polycarbonates,
are grades that tend to be more stable with temperature - it's a
reliability issue, if not actually one of flammability.
(polyetherimides and polyethersulphones are probably too pricey here)

RL