[sci.electronics] New Canon lenses with built-in motor

jpexg@mit-hermes.UUCP (02/23/87)

I was skimming through the Photography section of Sunday's New York Times,
the subject of which was a new series of lenses produced by Canon for their
35mm cameras. It seems that unlike Minolta's Maxxum system, which puts a
motor for focusing the lens in the camera body, Canon has put the motor in
the lens itself, with "no discernible increase in size or weight". The
motor is claimed to use "ultrasound, instead of conventional electromagnets";
can anyone guess how it works?

hatcher@INGRES.BERKELEY.EDU.UUCP (02/24/87)

[ 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