Reduced dimension balance spring of constant double section
AssigneeETA SA Manufacture Horlogere Suisse
InventorsJean-Luc Helfer, Yves-Alain Cosandier
Life of this patent
Estimating the term…
Abstract
A one-piece balance spring including a single strip wound on itself between an inner coil and an outer coil, the strip having a geometry such that when the angle of contraction of the balance spring has a value of 360 degrees, there is a substantially constant distance between each coil from the inner coil to the penultimate coil.
Claims7
A one-piece balance spring comprising a single strip wound on itself between an inner coil and an outer coil, the strip at rest having:
- between the end of the inner coil and the penultimate coil, a first area, wherein the pitch between each coil continuously increases such that, when the angle of contraction of the balance spring has a value of 360 degrees, there is a substantially constant distance between each coil from the inner coil to the penultimate coil;
- a second area, in the extension of the first area and comprised between the start of the penultimate coil and the end of the outer coil, wherein the pitch continuously increases such that, when the angle of expansion of the balance spring has a value of 360 degrees, there is a minimum distance between the penultimate coil and the outer coil to prevent any contact therebetween, the second area including a first portion, whose section is substantially identical to that of the first area, and a second portion, in the extension of the first portion, whose section is increased.
A resonator comprising a balance cooperating with a one-piece balance spring comprising a single strip wound on itself between an inner coil and an outer coil, the strip at rest having:
- between the end of the inner coil and the penultimate coil, a first area, wherein the pitch between each coil continuously increases such that, when the angle of contraction of the balance spring has a value of 360 degrees, there is a substantially constant distance between each coil from the inner coil to the penultimate coil;
- a second area, in the extension of the first area and comprised between the start of the penultimate coil and the end of the outer coil, wherein the pitch continuously increases such that, when the angle of expansion of the balance spring has a value of 360 degrees, there is a minimum distance between the penultimate coil and the outer coil to prevent any contact therebetween, the second area including a first portion, whose section is substantially identical to that of the first area, and a second portion, in the extension of the first portion, whose section is increased.
Dependencies are inferred from the claim text.