What would a mechanical watch look like if it was reimagined and redeveloped from the bottom up? Master watchmaker Benoît Mintiens asked himself this question. He came up with a unique mechanism in the world of mechanical timepieces, a wristwatch that ‘sleeps’ when you take it off and wakes up when you put it back on, setting the correct time automatically. This fascinating animation is powered by the smallest series motor from Faulhaber.
Innovative functionality and revolutionary product design
The basis of his success is a series of unique features that can be found only in watches from Ressence. It is not the hands that move on the dial but instead the dial itself. To be precise, there are multiple dials – a different one for each hand. The smaller hands are integrated in the large hand, circling one another like a planetary gearhead, and are constantly seen in new constellations. In spite of the unusual picture that forms as a result, one intuitively recognises the big and small ‘hands’ as the markers for minutes and hours.
Also missing is the crown, the small dial on the side which, on other mechanical watches, is pulled out and used to set the time. Its function is performed by a hinged lever on the bottom of the watch. The initial winding is also performed with the mechanical movement for the setting of the time. From then on, an automatic movement ensures spring tension and accuracy.
Time signal plus motor drive
With the help of an accelerometer, the Type 2 also recognises whether it is currently being worn or if it has been set down. In the latter case, the spring energy is conserved and the movement paused − the dials stop moving. In addition to the mechanical movement, this model also has onboard electronics called the e-Crown. When first set, it saves the time and continues to measure the time during the rest phases. The sensor registers when the watch is again put on, and the electronics release the spring. The movement is started by double-tapping the bezel, and the correct time is then automatically set – even if the watch has not been worn for months.
“With the e-Crown, we expand the concept of the mechanical watch with a new dimension,” says Mintiens. “The correct time is always available, and a person can also select a second time zone that the watch then likewise automatically sets. For the selection of the zone, the electronics communicate via Bluetooth with an app developed specifically for this purpose. Nevertheless, the watch remains an independent unit thanks to its automatic movement; the electronics do not interfere with its actual function. The electronics are used only for the adjustment steps that are otherwise performed with the crown.”
The e-Crown consists of 87 components; its flexible PCB with four layers is just a quarter of a millimetre thick. All parts are of the smallest dimensions and optimised for minimum energy consumption. As a result, the watch gets by on just 1,8 joules of energy per day. The electronics check the position of the dials at least once per day and make a correction if necessary. When putting the watch on again, or when switching between the time zones, an automatic adjustment process is triggered.
Micro-powerhouse
During this process, the large and small dials are turned to the appropriate positions. The power for the mechanical work of the e-Crown comes from the smallest series motor from Faulhaber, the 0308…B brushless DC-servomotor, in combination with the 03A micro planetary gearhead. With a diameter of just three millimetres, the drive unit fits into the extremely small installation space present in the watch. The available electric power is also quite limited there. It flows from six micro lithium-ion batteries, which are charged by very small solar cells. They supply just 1,2 V. “This is actually not enough to overcome the intrinsic inertia and friction of the system,” explains sales engineer Hein Vos from Faulhaber Benelux. “We therefore made a number of changes to the gearhead. These include a modified shaft, an adapted gear ratio, and a special lubricant.”
There may have been other products small enough for his watch, but for Mintiens the choice was clear. “One expects that a mechanical watch will function flawlessly for decades. The technology from Faulhaber guarantees the high quality and reliability of the drive that I need,” he concludes.
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