What exactly is resonance and how does it work? The Watch Pages teamed up with the expert in the field, Claude Greisler, Chief Horologist and Co-founder of Armin Strom, to explain to us the phenomena of resonance in watchmaking. Claude Greisler is one of only a handful of watchmakers worldwide that has mastered resonance in wristwatches.
When did the concept of resonance start?
In horology, the phenomenon of synchronized motion has fascinated watchmakers since the time of Christiaan Huygens (1629-1695). Huygens, the inventor of the pendulum clock, was the first to discover the resonance of two separate pendulum clocks, which he logically surmised should keep slightly different time. When hung from a common beam, however, the pendulums of the adjacent clocks synchronized. Researchers thereafter confirmed that the common wooden beam coupled the vibrations and created resonance.
The two pendulums functioned as one in a synchronous manner, existing and occurring at the same time. An outside shock slowing down one of them increases the speed of the other one by the same amount; but both will strive to get back in resonance, averaging and minimizing the effects of the outside influence as they find their rhythm.
How does resonance work?
A body in motion causes vibrations in its surroundings. When another body with a similar natural resonant frequency to the first receives these vibrations, it absorbs energy from it and starts vibrating at the same frequency in a sympathetic manner. Think of a trained singer who can hold a note that causes a tuning fork tuned to the same frequency to vibrate – that is resonance.
For the oscillators of a watch movement to be able to synchronize with each other, they, therefore, have to be closely tuned. Imagine a small child trying to synchronize steps with an adult; the child is unlikely to synchronize for more than a few steps as the length of their steps are too dissimilar to resonate.
Or imagine yourself pushing a child on a swing: the child and the swing make a natural pendulum, which will have an inherent natural frequency (speed of swing back and forth). If you push at the wrong frequency (too fast or too slow) then you are likely to block the motion and slow the swing down; however, if you push at or near the natural frequency of the swing then you will increase the amplitude of the child and the swing.
The advantages of resonance in a watch
The advantages of resonance are twofold:
1 – It has a stabilizing effect on timekeeping, meaning better accuracy.
2 – It produces a reduction of the negative effects on timekeeping accuracy, such as from outside perturbation like a shock to the balance staff, which in turn keeps the rate more stable resulting in increased accuracy.
Resonance and watchmakers through the years
In the eighteenth century, Abraham-Louis Breguet demonstrated his mastery of the physics with his double pendulum resonance clock. What was true for Huygens’ and Breguet’s clocks is just as true for Armin Strom’s wristwatch. Confirmed and tested by the CSEM, “Swiss Center for Electronics and Microtechnology”, the patented solution from Armin Strom is a new milestone in the history of watchmaking.
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