WatchTime - August 2012

PROFILE
TAG Heuer’s Guy Sémon
ter launching two new high-frequency
chronographs within two months, including
the first to achieve 1/1,000-second
accuracy. Not Guy Sémon. His latest
super-chronograph is called the
Mikrogirder, and its design is a revolution
in chronometry.
To achieve something faster than
1/1,000-second, Sémon had to abandon
classic escapement design because,
he says, traditional balance wheels and
spiral hairsprings are not capable of oscillating
reliably at frequencies above
500 Hz. In a traditional escapement,
the balance wheel oscillates back and
forth somewhere between 270 and 320
degrees in a horizontal position. While
higher speeds and smaller amplitudes
are possible (with smaller balance
wheels and stiffer hairsprings), traditional
escapements were never intended
to operate at extremely high frequencies.
Their physical limitations
70 WatchTime August 2012
The Mikrotimer
Flying 1000
achieves millisecond
accuracy.
meant a new design was needed. It was
time to get out the proverbial clean
sheet of paper.
Sémon’s new design is inspired by
the work of an 18th century French scientist,
who, like Sémon, was a physicist
and mathematician, not a watchmaker.
During the 1740s, Jean le Rond
d’Alembert published influential papers
on the vibration of strings and
wave equations, and his work still
plays important roles in physics today.
During his days as a university physics
instructor, Sémon taught a class that
included d’Alembert’s work.
Sémon’s new d’Alembert-inspired
regulator consists of three very small
metal blades (TAG Heuer also calls
them “girders” or “beams”) that can
be induced to vibrate at high frequencies,
and it represents a complete departure
from the centuries-old balance
wheel and spiral spring system.
THE MIKROGIRDER’S
FREQUENCY IS 1,000
HZ, OR 7.2 MILLION
VPH. TAG HEUER SAYS
IT IS THE FASTEST
MECHANICAL
REGULATOR EVER
CREATED AND
TESTED.
The Mikrogirder has an escape wheel
that turns and makes contact with two
teeth on an anchor, but that’s where any
visual similarity to traditional escapements
ends. The anchor excites the first
of the three blades, called the excitating
blade, which in turn excites the coupling
blade, which excites the linear oscillator
(also shaped like a blade). These three
blades are mere millimeters long and
small fractions of millimeters in diameter.
The linear oscillator performs the
same function as the hairspring in a traditional
escapement, controlling the
speed of the oscillation or vibration. In
the prototypes we saw, the excitating
blade is titanium, while the coupling
blade and linear oscillator are steel.
As Sémon explains his new system,
the energy of the escape wheel’s rotation
is converted into potential energy in the
anchor and excitating blade. This sets up
a vibration in the blades and linear oscillator.
The escape wheel is like a finger
plucking a guitar string (except the
Mikrogirder does not generate an audible
note). The Mikrogirder’s frequency is
1,000 Hz, or 7.2 million vph. TAG
Heuer says it is the fastest mechanical
regulator ever created and tested. Explaining
why he opted for 1,000 Hz, Sémon
said, “I can cut 1,000 into two
parts, and I can see for the first time the
scale of 1/10,000s of a second. I can
touch this scale for the first time in a mechanical
system.”