Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!ames!ucbcad!ucbvax!INGRES.BERKELEY.EDU!hatcher
From: hatcher@INGRES.BERKELEY.EDU.UUCP
Newsgroups: sci.electronics
Subject: Re: New Canon lenses with built-in motor
Message-ID: <8702240818.AA09404@ingres.Berkeley.EDU>
Date: Tue, 24-Feb-87 03:18:11 EST
Article-I.D.: ingres.8702240818.AA09404
Posted: Tue Feb 24 03:18:11 1987
Date-Received: Fri, 27-Feb-87 00:32:02 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: University of California at Berkeley
Lines: 13

[ re: a question about a piezoelectric motor Canon built into the lens
  of a new camera]
In a recent issue of EE Times (I think...) there was a product announcement
of a small lightweight stepper motor that used a piezoelectric mechanism.
There was a picture that showed an inner and outer ring; no explanation but
from the looks of it I guessed that they used something conceptually similar
to a ratchet mechanism, where on each pulse of the transducer the ring moves
(say) clockwise, and something prevents it from ever moving CCW. Thus, even
a very small forward motion per pulse could add up to reasonable rotation
rates at ultrasonic modulation frequencies. Anyway, these doohickeys are
available off-the-shelf now. Seems like there could be *scads* of applications
for them.
	Doug