Resonator with fine adjustment via an index-assembly
AssigneeETA SA Manufacture Horlogere Suisse
InventorsJean-Luc Helfer, Marc Stranczl, Laurent Jeanneret, Xavier Berdat
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Abstract
A resonator of the inertia/elasticity type includes a balance-spring coupled to an inertia flywheel and a system for adjusting the frequency of the resonator including an index-assembly arranged to cooperate with one coil of the balance-spring in order to selectively choose the active length of the balance-spring. The portion of the coil of the balance-spring cooperating with the index-assembly includes at least one area of larger cross-section than the other balance-spring coils for finer adjustment of the frequency of the resonator.
Claims11
A resonator of an inertia/elasticity type comprising:
- a balance-spring coupled to an inertia flywheel and a system for adjustment of a frequency of the resonator including an index-assembly comprising two stop members arranged to cooperate with a coil of the balance-spring in order to selectively choose an active length of the balance-spring,
- wherein a portion of the coil of the balance-spring cooperating with the index-assembly includes at least one area of greater cross-section than other coils of the balance-spring so that a correction of the index-assembly has less impact on the frequency of the resonator than on a non-thickened cross-section of a rest of the balance-spring, and
- wherein the index-assembly and the portion of the coil of the balance-spring cooperating with the index-assembly are arranged to offer the resonator an adjustment of one second per day for a shift of the index-assembly comprised between 10 and 50 micrometers along the portion of the coil of the balance-spring cooperating with the index-assembly.
Dependencies are inferred from the claim text.