[rescue] Sun Postscript Mouse Pad

[Robert Darlington]

Those hour ratings for LEDs generally mean after 50,000 hours of use at them
maximum rated current, they dim to 70% brightness.  This is the level at
which the average person will notice that the light is dimmer.  This is 70%
as measured on a photometer, not the eye (our Mk I eyeballs are on a log
scale).   Some of the new ones are rated for 95% brightness after 100,000
hours!  If you run below the max current rating, these numbers go way up.
Running an ordinary LED at half current can make them last for decades of
continuous use.



On Thu, Sep 4, 2008 at 1:23 AM, Jochen Kunz <jkunz at unixag-kl.fh-kl.de>wrote:

> On Wed, 3 Sep 2008 16:37:34 -0700 (PDT)
> Ron Wickersham <rjw at alembic.com> wrote:
>
> > yes they worked WAAY better, but over time the output of the LEDs
> > reduced and made them work poorer and poorer as time wen on (most
> > workstations those days were on 24/7).
> Even high power LEDs (The 1 W to 3 W Lumileds) have a livetime of 50,000
> hours. That are 5.7 years. Normal LEDs can exceed this by a factor of
> maybe 5 times...
>
> > one thing that hasn't been mentioned is that the original mats had the
> > stripes in colors that were opaque to red light in one direction and
> > opaque to infrared light in the other direction.  so that makes a
> > carbon laser jet pad even less optimum even when you back it with a
> > reflector.
> I have seen such pads: Green and red stripes. But that was on SGIs. All
> Sun "razor mirrors", that I have seen, use a plain black grid. Open an
> old type 4 mouse: There are two LEDs, two lenses and two photosensors,
> all identical, mounted in a 90 degree angle...
> --
>
>
> tsch|_,
>       Jochen
>
> Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/<http://www.unixag-kl.fh-kl.de/%7Ejkunz/>
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