Xref: utzoo comp.robotics:870 sci.electronics:20212
Newsgroups: comp.robotics,sci.electronics
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: Sensing a known location to reference off of
Message-ID: <1991May15.214221.26760@zoo.toronto.edu>
Date: Wed, 15 May 1991 21:42:21 GMT
References: <1991May15.005403.28812@src.honeywell.com> <1991May15.203301.18003@mcs.anl.gov>
Organization: U of Toronto Zoology

In article <1991May15.203301.18003@mcs.anl.gov> winans@sirius.mcs.anl.gov (John Winans) writes:
>My old 8" cpm drives used leaf switches & to detect when the head was over 
>track 0 (the head was moved via worm gear on a stepper motor) and they NEVER
>failed over the 8 or so times I moved to and from college in the early 80's.

Note that the Canon laser printers -- aimed at a very cost-sensitive market
by people who consistently produce high-quality equipment -- use optical
interrupters for all such sensing jobs.  For example, passage of paper is
sensed by a little arm that moves a vane into or out of an interrupter.
-- 
And the bean-counter replied,           | Henry Spencer @ U of Toronto Zoology
"beans are more important".             |  henry@zoo.toronto.edu  utzoo!henry