Been thru the same thing for the boost gauge in my car.
The problem was evident not only in direct sunlight,
but also in indirect sunlight.

I tried different LED's, different currents, and different
filter grades/colors, with little success.  Some of these
helped, especially overdrving the LED's a bit, but one of
the best solutions was using a non-glare red filter over
the LED's.  The color I used was 2444 P-50.  The "P-50"
indicated the low-glare property of the material, and
the 2444 was the darkness/color.

Cheers,
-Neil.




> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Chris Loiacono
> Sent: Monday, February 03, 2003 6:45 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: 7 segment LED's & luminosity ratings
>
>
> I have just tested a small instrumentation project (which Sid is familiar
> with) that uses individual 1" tall 7 seg LED's from Lumex. I did
> all I could
> to maximize the brightness - even cheating with the current to
> the point of
> knowingly having shortened the part's life span.
> Indoors, in any lighting condition I can reasonably produce, the
> brightness
> is fantastic.
> Outdoors, it's a real dog, only clearly readable in shade or indirect
> sunlight.
> I have tried tinted plastic of various densities and at varying distances
> from the display surface - all to no avail.
> The only thing I have left to try is to increase the mux freq a
> bit, but am
> now questioning how much difference this CAN make.
>
> I have seen LED displays in outdoor environments, and with the latest
> generation of ultrabrights available I would expect more...
> Am I missing something, or should I just ditch the LED idea and go to a
> different display technolgy???
>
> Chris
>
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