Constancy (in the sense of constant force) is a permanent quest for watchmakers. At Girard-Perregaux, this horological ‘holy grail’ has become a reality. Presented in 2008, the Constant Escapement – whose name is a nod to Constant Girard-Perregaux – revolutionised the very foundations of chronometry (timekeeping precision). Leveraging the extraordinary properties of silicon that enables the most innovative structures, the mechanism supplies the balance wheel with constant force that never dwindles, however much energy is available. Ten years after this major breakthrough that won the prestigious “Aiguille d’Or” award in the Grand Prix d’Horlogerie de Genève, Girard-Perregaux introduces a new Constant Escapement L.M. model featuring a design that is more technical and contemporary than ever.
Although very efficient, the oscillating organ of a traditional watch movement is beset by a recurrent weakness: its isochronism directly depends on the quantity of energy delivered by the barrel. The wide amplitude of the balance wheel when the watch is full wound gradually diminishes as the mainspring unwinds. A linear supply of energy is thus the very foundation of precision.
Protected by four invention patents, the new Constant Escapement L.M. reprises the mechanism that made such a strong impression: a butterfly-wing frame is placed between the lever and the balance spring. This intermediate device serves to support a buckled-blade measuring just 14 microns thick – six times finer than a human hair.
Impossible to make in any material than silicon, this strategic component appears to be floating in a vacuum, taking on a wave-like form. Thus flexed at the point of instability, it is capable of storing a certain amount of energy, before releasing it all at once and transmitting it back to the balance wheel when an impulse causes it to buckle from one state of equilibrium to another.
