Hairspring and its index-assembly

摘要

The hairspring (10) has an end fixed to a balance-spring stud (14), and an interior end fixed to a collet (12), where the hairspring is made of monocrystalline silicon/diamond and obtained by a deep etching process. The silicon is covered with an oxide/diamond layer. An exterior coil of the hairspring is terminated at an end fixed to the stud. The coil has a portion divided into two strips (16) that define an oblong opening (18). A radius of curvature of the strips is equal to that of the coil. The opening receives an adjustment unit (20) whose position is movable with respect to the opening.