The Mikrotourbillon S presented this autumn by TAG Heuer is the culmination of a long study that goes back nearly ten years. Just to remind you, TAG Heuer purchased the rights to the V4 “concept-watch” from Jean-François Ruchonnet in 2003. The problem at that time, however, was that the development of this new type of watch, which used transmission belts in place of the traditional gear trains, required a level of technical knowledge and competence that was outside of the realm of watchmaking.
Quite determined to succeed, at any cost, in developing and commercialising this product that came before its time, TAG Heuer called in consultants from other sectors, such as automobile, aeronautics, and avant-garde techniques. It was within this framework that Guy Semon, physicist, mathematician, engineer, and university professor, who had previously worked at the French National Defence department, came to meet the teams at TAG Heuer in 2004.
In 2007, TAG Heuer asked Guy Semon to join the company in order to create a research and development department worthy of the name. Jean-Christophe Babin, CEO of TAG Heuer, was following a very innovative vision regarding research for his brand. Rather than follow the path of classical watchmaking, TAG Heuer had from the outset earned its reputation in the field of technical watchmaking, focused entirely on performance and precision. The whole idea was to distinguish the brand by introducing high technology into products that would nonetheless remain accessible.

Back to basics
Guy Semon became the man of the hour. Armed with his scientific experience—which, in the beginning, had nothing to do with watchmaking—this engineer had to start thinking about the basics of timekeeping. (Today, Semon muses that he is 50 per cent engineer and 50 per cent watchmaker.)
His first observation was that even though there was a standard defining a chronometer (the ISO 3159 standard, which is found in the COSC), there was no standard to define the criteria of what a chronograph should or should not be in terms of precision. But—and here is the rub—the activation using a clutch of an integrated (or additional, it does not matter) chronograph in a watch that is classified as a chronometer requires an additional energy supply that affects the watch’s timekeeping. Thus, when its chronograph is activated, the watch is no longer a chronometer.

Decoupling the two functions
Semon decided then to disconnect the two functions and assemble them in parallel. On one side would be the time function, which has its own source of energy (the barrel), its own transmission system (the gear trains), and its own regulation. On the other side would be the chronograph function, with its own energy source, its own transmission system and its own regulation. From then on, in the absence of a clutch linking the two functions, the operation of the chronograph would not interfere at all with the operation of the watch. This opened the possibility, for the first time, of certifying the chronograph function. Even more importantly, decoupling the two functions allows the precise calibration of the energy needed for each function and thus permits a rise in frequency to regulate the chronograph function at 5 Hz (which makes it possible to display 1/10th of a second), 50 Hz (making it possible to display 1/100th of a second), or even at 500 Hz (with the possibility of counting to 1/1000th of a second).

“To appreciate 1/100th of a second, you must know the 1,000th”
The first practical exercise—and commercial one, since the piece in question was launched in the market in the summer of 2011—was the Mikrograph. Twelve patents were filed for this first dual-chain watch, in which coexist two different barrels and two regulators, one at 4 Hz for the time function, and one at 50 Hz for the chronograph function at 1/100th of a second, readable on the largest scale, namely the one around the circumference of the dial.
But, as Guy Semon quickly adds, “to be able to appreciate the 1/100th of a second, you must be able to count the 1/1000th.” As on a metric ruler, to appreciate the centimetre, you must be able to count the millimetre. The second dual watch is thus the Mikrotimer, introduced soon after, that houses a 4-Hz hour, minute, and second regulator, and a 500-Hz chronograph function capable of measuring 1/1000th of a second.
Here, we can appreciate another phenomenon that logically leads to the next innovation. The higher the frequency, the more the need for a shorter and shorter balance spring that is also more and more rigid. And, at the same time, the diameter of the balance decreases. This diameter, in fact, decreases to the point of becoming totally useless, until it finally disappears altogether.
It is here that a small technical point becomes important. A balance is an energy reservoir that stocks energy coming from the pallet fork, whose function is to help the balance spring return, since a normal balance spring does not have any inertia. Already in the 50-Hz Mikrograph, the necessity to help the balance spring return to its position was well understood. The solution thus was to add a launch hub brake system to the column wheel that, acting a little like a whip, gives the balance an impulsion greater than its speed in order to rhythmically re-launch it. The 500-Hz Mikrotimer no longer has a balance at all. The pallet fork is in direct contact with an ultra-thin plate fixed to a column, whose end supports a balance spring. At the base of the column, the launch hub brake system acts directly on the hub.
But, as in the example above, to appreciate the 1/1000th of a second, you must then be able to count the 1/10,000th of a second, which means increasing the frequency to 5,000 Hz. But here we reach an insurmountable barrier, since physically a balance spring, as defined by Huygens in 1675, cannot go beyond 600 Hz. Higher than this, it is no longer isochronous, but rather “goes nuts and vibrates all over the place,” as Semon colourfully explains.

Going past the physical barrier
The physical barrier of 600 Hz pushed Guy Semon to think about developing a new type of mechanical regulator that could exceed the limits of the traditional balance spring. He remembered the vibratory theory of d’Alembert. Theorised in the 18th century by this famous encyclopaedist, this physical vibratory property has hitherto been applied essentially only to musical instruments. Everyone knows that when you strike a guitar string, it vibrates at a certain calculable pitch, which is called the note. Taking the example of the harp, Semon got the idea of making a metallic blade vibrate at a certain frequency, in this case 1,000Hz.
His principle of the regulator was, in fact, quite simple: driven by the escape wheel, the pallet fork excites a metallic blade (a “girder”). This blade is connected, via a second coupling blade, to a vibratory blade with a regulating screw at the end. The screw allows it to be stabilised to the desired vibration speed, with the blade serving as a regulator.
This innovation gave birth to the Mikrogirder, which was presented this year. Guy Semon’s dream is to adapt this new type of oscillator to the Mikrotimer, but this is still a long way off.

The Mikrotourbillon S
Back in the present, however, we find a new model based on the dual principle, but applied this time to a tourbillon, or rather to two tourbillons. A few years ago, Jean-Christophe Babin proclaimed, “TAG Heuer will never make tourbillons”. He was certainly not wrong to look for success in other aspects of mechanical timekeeping, as we have seen, but the introduction of the Mikrotourbillon S—while contradicting his statement—was done for the right reasons, namely pushing chronometry even further. A tourbillon is slow (generally it operates at 2.5 Hz or at 4 Hz), and is intended to measure the time of day rather than short intervals.
And yet, the Mikrotourbillon S that has just arrived on the market is endowed with a dual architecture. On the one hand, there is a traditional tourbillon adjusted to 4 Hz (in other words, one revolution per minute) that fulfils the criteria of the COSC and displays hours, minutes, and seconds, regulated for 48 hours of power reserve. Its barrel is wound automatically. On the other hand, there is a 50-Hz tourbillon—capable of indicating 1/100th of a second—that, along with its 12 revolutions per minute, regulates a chronograph that has a power reserve of ten minutes at this speed. This smaller tourbillon has no carriage, but is equipped with a launch system, similar to what we saw above for the Mikrograph and the Mikrotimer.
One of Semon’s proudest achievements is to have made these two tourbillons totally in-house (with the exception of the balance spring and the surface treatments), in the brand’s own R&D unit, which today employs 50 people.

Pulling the brand upmarket
“Strategically, my role with these very innovative products such as the Mikrotourbillon S, selling for between CHF 190,000 and 220,000 depending on the model, is to place them at the top of the TAG Heuer product pyramid in order to pull the entire brand towards the high-end,” he continues. “TAG Heuer’s average price is around €2,500, and today we are the biggest producer of mechanical chronographs. We must ensure our growth by developing our range. This is essential because, with our volumes, we must each year renew our clientele and find new markets.”
As part of the brand’s strategy, the certification of chronographs plays an essential role. The Observatory in Besançon has developed for TAG Heuer; an irreproachable protocol that lays down the ground rules for the certification of a chronograph. This is a standard for mechanical measurement in the form of an instrument capable of measuring to 10-6 second (or one microsecond), thus allowing the calibration of various traditional measurement instruments that would be obsolete at such levels of accuracy. In a similar vein, a very special camera, purchased in the United States, lets TAG Heuer capture up to 70,000 images per second. “This is a way to discover things that we don’t expect,” smiles Semon.
The chronograph certification is therefore on the way. It remains to be seen, however, if it will become a veritable shared standard. We must also note that the power reserve, which has its own physical limits, is intimately linked to the frequency. It is 100 minutes for 5 Hz displaying 1/10th of a second, 10 minutes for 50 Hz displaying 1/100th of a second and just one minute for 500 Hz displaying 1/1000th of a second. With an understanding of this reality, will the consumer—aside from real watch aficionados—care about this new certification? Only time will tell.

Source: Europa Star August - September 2012 Magazine Issue