| 主权项 |
1. A one-piece balance spring comprising a single strip wound on itself between an inner coil and an outer coil, the strip comprising, at rest, between the end of the inner coil and the second coil, a first area wherein the pitch continuously decreases and the section continuously increases, a second area, in the extension of the first area, wherein the pitch between each coil continuously increases and the section of the strip starts at a smaller value than the section at the end of the first area, then continuously increases such that, when the angle of contraction of the balance spring has a value of 360 degrees, there is a constant distance between each coil from the second coil to the penultimate coil. |
