TAG HEUER PENDULUM CONCEPT: A RADICAL “OUT OF THE BOX” RETHINK OF MECHANICAL TIME REGULATION DESIGN AND PERFORMANCE
Since the creation of the Galileo-inspired hairspring by Christiaan Huygens in 1675, the regulating organ of all mechanical watches has been based on a balance wheel and spiral-shaped torsion hairspring system. A coiled strip of fine metal alloy, the hairspring provides the torque necessary for the balance wheel to oscillate and regulate its frequency. Over the centuries, it has been significantly modified and improved. Charles-Edouard Guillaume (1861-1938), the son of a Swiss watchmaker, discovered new alloys (Invar and Elinvar) that significantly reduced the metal spring’s thermal sensitivity. Guillaume won the Nobel Prize for Physics for this invention in 1920.
With the challenge of temperature diminished by Guillaume’s alloys, the spiral hairspring regulation system came to dominate mechanical movement design. However, the mechanical hairspring has three serious design limitations: a mass that makes it sensitive to gravity and deforms its geometry; a material that makes it sensitive to thermal expansion; and a divergence between its geometric centre and its centre of mass. These may cause isochronal issues that can be technically and physically improved but never completely eliminated.
Overcoming the design limitations inherent in the traditional regulation system by eliminating the need for a spiral hairspring was the first challenge TAG Heuer set for itself. The second was keeping the movement 100% mechanical: conventional watchmaking wisdom has always held that a mechanical watch without spiral hairspring would necessarily require another energy source for its regulation.
In the TAG Heuer Pendulum Concept, the traditional hairspring is replaced by an “invisible” or virtual spring derived from magnets. The complete device forms a harmonic oscillator. The magnetic field, generated by means of 4 high-performance magnets and controlled in 3D through complex geometric calculations, provides the linear restoring torque necessary for the alternative oscillations of the balance wheel. The oscillating period of the TAG Heuer Pendulum Concept is resistant to changes from perturbing forces, which is what makes it an exceptionally good timekeeping device. The movement built with this revolutionary oscillator is fully mechanical and does not contain any electronics or driven actuators. The magnets generate a constant field over decades.
TAG Heuer Pendulum Concept, the world’s first oscillator in a mechanical movement without hairspring, beats at 43,200/hour (6 Hertz) — making it a superlative representative of TAG Heuer’s unique mastery of high frequencies and ultimate precision. It requires no additional components and is based on physical magnetic properties. It gets its name from an earlier Huygens creation — the pendulum clock of 1657.