Eric Vittoz - IEEE

TECHNICAL LITERATURE
Statek described his quartz resonator [26]. By creating
an electrostatic version of a tuning fork, Staudte was
able to shrink dimensions dramatically (Fig. 8). Additionally
Staudte introduced photolithographic batchprocessing
techniques to quartz resonator manufacture,
including laser trimming, allowing the same
economies of scale enjoyed by the IC business. Statek
even offered a transparent glass package option that
allowed laser trimming on packaged resonators.
Thanks to Staudte’s brilliance, a compact, inexpensive,
but accurate resonator could oscillate at
32.768kHz. This frequency has since become the standard
frequency for clocks, including those found
inside desktop and laptop computers.
The compounding effect of all of these advances
was a boon to consumers, for now anyone could
afford a watch whose accuracy was undreamt of only
a few years earlier. By the time of Intel’s sale of Microma,
LED watches were selling for under $10, and LCD
watches would soon follow suit.
“What’s Next?”
Even the most inexpensive wristwatches available
today are so precise that the need for even better
stability no longer drives their evolution. Other factors,
such as esthetics, generally matter more to
consumers now. The electronics revolution has
continued unabated over the four decades since
the Beta21 was introduced, so the ability to integrate
ever more functions per unit volume explains
why many watches are becoming multipurpose
information appliances. Wristwatches that are also
PDAs, infrared remote controls, pagers, radios,
TVs, walkie-talkies and MP3 players have all
appeared on the market at one time or another.
The primary constraint on adding even more features
is the power consumed by all of these functions.
The low-power tradition that Eric Vittoz
established will only strengthen as engineers struggle
with the constrained power budgets of a wristwatch
form factor.
And for those consumers who are obsessed
with accurate time, the ability to communicate
with GPS satellites can endow a watch today with
traceability to an atomic standard. One can only
hope that it would maintain a better accuracy than
that lobby clock Max Forrer’s wristwatch bested in
1968.
Acknowledgements
The author is grateful to Byron Blanchard for calling
attention to Airy’s analysis of the escapement; to Jim
Williams of Linear Technology for relating his experiences
with the Accutron; and to our polymath editor,
Mary Lanzerotti, for her literary and technical
inspirations.
References
[1] Christian Piguet, “The First Quartz Electronic Watch” in
Integrated Circuit Design, Power and Timing Modeling,
Optimization and Simulation, Proceedings of the 12th
International PATMOS Workshop, Seville, Spain, September
11–13, 2002, Springer Berlin/Heidelberg 2002, pp. 275-
288.
[2] James Jesperson and Jane Fitz-Randolph, From Sundials to
Atomic Clocks – Understanding Time and Frequency, U.S.
Dept. of Commerce, Technology Administration, National
Institute for Standards and Technology, Monograph 155,
March 1999.
[3] Joseph Needham, Wang Ling, and Derek de Solla Price,
Heavenly Clockwork: The Great Astronomical Clocks of
Medieval China," 2nd Edition, Cambridge University Press,
1986. Also see Joseph Needham, Science & Civilisation in
China, vol. IV, chapter 2: Mechanical Engineering, Cambridge
University Press, 2000.
[4] David S. Landes, Revolution in Time: Clocks and the Making
of the Modern World, Revised and Enlarged Edition (Paperback),
Belknap Press, April 21, 2000.
[5] Richard of Wallingford, Tractatus Horologii Astronomici, c.
1330.
[6] Giovanni di Dondi, Il Tractatus Astrarii, c.1370.
[7] Interview with historian William Andrews, http://www.abc.
net.au/rn/science/ss/stories/s199675.htm, retrieved 14 May
2008.
[8] Galileo Galilei, letter dated 1602 [8, Vol. X p. 97] in Le Opere
di Galileo Galilei, ed. A. Favaro, Nuovo ristampa della edizione
nazionale, G. Barbèra, Firenze, 1968.
[9] Christiaan Huygens, Horologium Oscillatorium, Apud F.
Muguet, Paris, 1673. Scans of an original manuscript may be
found at
http://historical.library.cornell.edu/kmoddl/toc_huygens1.ht
ml. Those whose Latin is a little rusty may find helpful the
English translation at http://www.17centurymaths.com/contents/huygenscontents.html.
Also, to hear native Dutch
speakers pronounce “Huygens” (and, as a bonus, “van
Leeuwenhoek”), see
http://frank.harvard.edu/~paulh/misc/pics/huygens_96.mp3.
We are grateful to Prof. Paul Horowitz of Harvard University
for providing this valuable service.
[10] Mark V. Headrick, “The Origin and Evolution of the Anchor
Clock Escapement,” IEEE Control Systems Magazine, vol. 22,
no. 2, Apr. 2002, pp. 41-52. Also see http://www. geocities.com/mvhw/
anchor.html.
[11] George Biddell Airy, “On the Disturbances of Pendulums and
Balances, and on the Theory of Escapements,” Transactions
of the Cambridge Philosophical Society, Vol. III, Part I (1830):
pp. 105-128, Plate 2. The connection of his analysis to that
of modern oscillators is evident in the oscillator phase noise
analysis in [28], which describes the benefits of properlytimed
impulsive energy restoration. The Colpitts oscillator
and pendulum-escapements share this property of impulsive
restoration.
[12] Alexander V. Roup et al., “Limit Cycle Analysis of the Verge
and Foliot Clock Escapement Using Impulsive Differential
Equations and Poincaré Maps,” Proceedings of the American
Control Conference, June 2001, pp.3245-3250.
[13] Dava Sobel, Longitude: The True Story of a Lone Genius Who
Solved the Greatest Scientific Problem of His Time, Penguin,
New York, 1995. Also see the PBS dramatization based on
Sobel’s book, Lost at Sea: The Search for Longitude.
[14] Jacques Curie and Pierre Curie, “Développement, par
pression, de l’électricité polaire dans les cristaux hémièdres
à faces inclinées” [Development, by pressure, of electrostatic
polarization in hemihedral crystals with inclined
48 IEEE SSCS NEWS Summer 2008