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Historical Background
As mentioned in other sections, the first battery driven, marketed wrist watch was the electro-mechanical system introduced to the public by Hamilton in 1957.
The idea of creating an electric wrist watch already was present in 1937 with the Elgin Watch Co. in the USA, but the actual research on the system began in 1946 about the same time as Frédéric Lip in France would start the same research, completely independently of Elgin. Lip had already some experience concerning the electric system for watches, having built electric time pieces before the advent of WWII. A few months after Lip and Elgin, also Hamilton Watch Co. in the USA would start the research on such electrical wrist watches and would be the first company to market the system in 1957 (1, 2).
In Switzerland Ebauches SA was the first looking into the development of electro-mechanical calibers and with the lead of André Beyner, they will market a short lived but widely used system, the L4750/51 movements. The downside of latter calibers is the need for physical, electrical contacts which would spark from time to time. The solution was to use a transistor, which is an electric switch, rendering the electric contacts obsolete and thus making the caliber more reliable. Again Ebauches SA looked into this, starting from 1961 developing the ‘Dynotron 9150’ movement, which was marketed, also highly successfully starting from 1967. The ‘Dynotron’ caliber received several updates and it was used until the mid 1970s.
From Omega’s side there is a Swiss patent filed the 26.4.1955 (granted 1961) for an experimental electro-mechanical set up with fixed coil and magnet on the balance, resembling the ‘Dynotron’ system by ESA. Omega did work with a variant of this concept around 1964 and made a few prototypes named cal.: 6550, but with coils on the balance like the Hamilton system of 1957. The concept was pushed so far, that the model name was already decided upon: Dynatron (not to confuse with ESA’s Dynotron). The Omega system featured two transistors, while ESA’s Dynotron system had only one. Despite several experimental attempts, Omega did not produce electro-mechanical watches at all.
Although the patent for this system is attributed to Omega, it seems that engineers from the Battelle institute in Geneva are responsible for the invention. Omega’s research collaboration with the Battelle Institute in Geneva will finally abandon the electromechanical systems and enter the development of quartz regulated watches.
Technological Features
The electro-mechanical system for wrist watches has the advantage of theoretically only needing a partial redesign of the calibers. Finally ‘only’ the energy provided by the main spring must be replaced by the energy coming from a battery. The problematic parts being the construction of a battery small enough to be mounted inside a wrist watch and the transduction of electric energy from the battery into mechanical energy for entertaining the balance wheel oscillations.
The solution was to electrically stimulate a magnetic element with an electro-magnetic coil, the magnetic charge of the coil being provided by an electric circuitry. During the 1950s more than two dozen different systems were patented either mounting the electro-magnetic coil or the magnetic element on the balance wheel. These systems were developed all over the world, in the USA, in Germany and France, but also in Japan. The first to have successfully applied the system were LIP in France in collaboration with Elgin USA and Hamilton (USA).
Even if the use of electricity though the integration of a battery, the electro-mechanic system still relies on the oscillations of a balance wheel. The oscillation frequency of a balance wheel being limited to a few Herz, even with the use of a battery the precision of the system cannot be bettered. This fact was one of the main arguments of Max Hetzel in his meta-analysis to criticise the system as being obsolete and promote his electro-magnetic system allowing oscillation frequencies of 300 – 720Hz (3).
In the sub-sections you can follow the chronological evolution of the system and also appreciate the different technological approaches of some manufacturers.
Ref.:
- Coustans M.-P.; Lip, des heures à conter; Editions Glénat, 2022
- Trueb L. F., Ramm G., Wenzig P.; Die Elektrifizierung der Armbanduhr; Ebner Verlag, 2011
- Hetzel M., La Montre Electrique; Conference de Synthese, Societé Suisse de Chronométrie, June 1964
Electric Watch Prototypes 