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Chapter 1
The Optical Mouse: Early Biomimetic
Embedded Vision
Richard F. Lyon
Abstract The 1980 Xerox optical mouse invention, and subsequent product, was a
successful deployment of embedded vision, as well as of the Mead-Conway VLSI
design methodology that we developed at Xerox PARC in the late 1970s. The design
incorporated an interpretation of visual lateral inhibition, essentially mimicking biol-
ogy to achieve a wide dynamic range, or light-level-independent operation. Con-
ceived in the context of a research group developing VLSI design methodologies,
the optical mouse chip represented an approach to self-timed semi-digital design,
with the analog image-sensing nodes connecting directly to otherwise digital logic
using a switch-network methodology. Using only a few hundred gates and pass tran-
sistors in 5
nMOS technology, the optical mouse chip tracked the motion of light
dots in its field of view, and reported motion with a pair of 2-bit Gray codes for x
and y relative position—just like the mechanical mice of the time. Besides the chip,
the only other electronic components in the mouse were the LED illuminators.
µ
1.1 Early Mice
At Xerox PARC, wheel mice and ball mice went through several generations in the
1970s, and when Xerox first delivered their commercial workstation product—the
Xerox “Star” 8010 Information System—in the early 1980s, it shipped with a ball
mouse. But the optical mouse that I first designed in 1980 made it to product a few
years later, and displaced the ball mouse in favor of this less expensive and more
reliable technology based on a single-chip VLSI sensor with logic (see the chip
photo, Fig. 1.1 ).
The early mechanical mice worked well when they were clean, but tended to
gum up over time. They did not have removable balls like the later Apple Macintosh
mice, so had to be disassembled and cleaned by a technician. Due to these difficul-
ties, several researchers at PARC had worked on developing no-moving-part optical
alternatives. I had the advantage of being able to review several different previous
( B )
Google Inc., Mountain View, CA, USA
e-mail: dicklyon@acm.org
R.F. Lyon
 
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