| 摘要 |
The invention relates to a balance spring comprising a strip wound around itself into several coils, the inner coil being integral with a collet comprising a band extending substantially in the form of a polygon. According to the invention, the outer contour on each bulging portion (2, 4, 8) of the vertices of the polygon comprises two axially extending walls (21-22, 41-42, 81-82) substantially parallel to each other relative to the segment formed between the centre (C) of the collet (5) and the end (S1, S2, S3) of said bulging portion (2, 4, 8). |
