Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!nrl-cmf!mailrus!ukma!rutgers!rochester!kodak!ornitz
From: ornitz@kodak.UUCP (barry ornitz)
Newsgroups: sci.electronics
Subject: Re: visible infrared? (Mouse Systems Mouse)
Summary: Visible and IR LED's
Keywords: LED,IR,visible,mouse,Mouse Systems
Message-ID: <1574@kodak.UUCP>
Date: 3 Jan 89 02:16:13 GMT
References: <743@optilink.UUCP> <501@igor.Rational.COM>
Reply-To: ornitz@kodak.UUCP (barry ornitz)
Followup-To: sci.electronics
Organization: Eastman Kodak Co, Rochester, NY
Lines: 30

In article <501@igor.Rational.COM> dsb@Rational.COM (David S. Bakin) writes:
>From article <743@optilink.UUCP>, by brad@optilink.UUCP (Brad Yearwood):
> 
>> Which brings me to a question.  There is a second LED, presumably infrared
>> emitting, in the Mouse System mouse, to the left of the red LED.  If you
>> look carefully (particularly if you cover the red LED), the infrared LED
>> appears to have a pale bluish-gray glow.
>
>The Mouse System mouse is an optical mouse.  Light goes out, some light goes 
>back in.  The second "LED" isn't a led, its a photosensor.  I would guess.
>
>-- Dave
Guess again, Dave.
I thought this sounded funny, but I just opened up my PC Mouse to be sure.
There are two LED's, visible red and IR.  Next to the LED's are two spherical
lenses mounted in holes in the printed circuit board.  These lenses focus the
reflected light via a reflector on the top cover of the mouse to two associated
photodetectors mounted on the circuit board.  A second giveaway is the fact 
that the mouse pad is printed in two colors giving a different contrast to
the red and IR beams.
                                                    Barry
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|  ___  ________  |
| |  / /        | |  Dr. Barry L. Ornitz  UUCP:..rutgers!rochester!kodak!ornitz
| | / /         | |  Eastman Kodak Company
| |< < K O D A K| |  Eastman Chemicals Division Research Laboratories
| | \ \         | |  P. O. Box 1972
| |__\ \________| |  Kingsport, TN  37662       615/229-4904
|                 |
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