Eta Sa Fabriques D'ebauches

Eta Sa Manufacture Horlogere Suisse

Denis Burdet

Jean-Philippe Rebeaud

Florian Serex

Frédéric Leuba

Fr&eacute;d&eacute;ric Leuba

The present invention proposes improving the yield of a microgenerator () used for operating a timepiece. Such a microgenerator operates on the basis of the phenomenon of electromagnetic induction, it is thus desirable to limit as far as possible the presence of magnetic masses in proximity to said generator. Research undertaken has shown that the electrically conductive paths (), and even their single protective layer, arranged in proximity to the microgenerator brake it, when they are formed of a magnetic material, and in particular a ferromagnetic material. Thus, the selection of exclusively non-magnetic materials is proposed for manufacturing the conductive paths.

Use of non-magnetic paths for an electronic module intended for a timepiece

The timepiece includes a time base ( ), a generator ( ) formed in particular of a rotor ( ) with permanent magnets and at least one coil ( ), a barrel ( ) with a mainspring coupled to said generator in order to drive it, analogue time indicating means ( ) also driven by said barrel. These time indicating means operate substantially synchronously relative to said time base as long as the torque C provided by said barrel is greater than or equal to a minimum synchronisation torque C . The timepiece also includes means ( ) for braking said generator, magnetised means ( ) having with the rotor, when the generator is stopped, a static positioning torque C allowing said rotor to be kept in a substantially stationary position. The generator braking means are activated as soon as the time indicating means are no longer operating in a substantially synchronised manner with the time base, and the magnetised means are arranged such that the static positioning torque C is greater than or substantially equal to a reference torque C for which the torque C exerted by the barrel on the rotor is equal to said minimum synchronisation torque C .

Timepiece including a generator

The transmission device disclosed is inserted between a rotating oscillating weight and an electric micro-generator in order to drive the generator rotor from the oscillating weight by multiplying the rotational speed. Its intermediate wheel and pinion includes a barrel ( ) whose central shaft ( ) is coupled to the drum ( ) of the barrel by a spiral spring ( ). The inner end of the spring has a bent portion ( ) which engages via resilience in any one of a number of hollows ( ) in the shaft and can be released by sliding over a slanting side ( ) when the shaft exerts too great a torque in the given rotational direction. This arrangement prevents damage resulting from shocks, in particular in the case of a watch, without using a friction system.

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Neuchâtel, Switzerland

Denis Burdet