Apache-Talk @lexa.ru 

Inet-Admins @info.east.ru 

Filmscanners @halftone.co.uk 

Security-alerts @yandex-team.ru 

nginx-ru @sysoev.ru 




      :: Filmscanners
Filmscanners mailing list archive (filmscanners@halftone.co.uk)

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: filmscanners: LED Illumination for Film Scanners

On Fri, 22 Jun 2001, Julian Robinson wrote:

> Hey let's keep this clean and vaguely accurate even if it is OT...

Austin went just a bit over the edge with that 1000 
hour MTBF figure.

Having designed many circuits and systems around HP 
LED displays, optocouplers, fiberoptic transceivers, 
etc., I was troubled by that number.

HP is now Agilent.  Check out 


and do a quick search using the search phrase 

"LED reliability"

The first PDF I found cites a particular type 
of LED, used in highway warning signs, with 
a MTBF of 1.5 million hours (before catastrophic
failure). For simple aging, the paper cites 
100,000 hours of operation before a 25% 
reduction in light output.

A second paper gives mildly contradictory 
data.  This one (discussing LEDs for 
instrument cluster lighting) gives 10 million 
hours MTFB (catastrophic failure) and 50,000 
hours of operation before a 75% reduction in 

Either way, I think most of us won't have 
to worry much about LEDs failing in our 
Nikon scanners.  The scanners will be long 
obsolete before the LEDs die.

2000 hours is roughly a year's worth of work-
days (weekdays) at 8 hours per day.

I suppose if you figure in hard mechanical 
shock (like in Austin's Land Rover) the 
numbers might go down a bit.  Time to fix 
the potholes in your driveway, Austin, 
or get new shock absorbers for that beast.

rafe b.


Copyright © Lexa Software, 1996-2009.