Balance spring, regulated balance wheel assembly and methods of manufacture thereof

摘要

A balance spring comprising a flat spiral coil and a non-elastic inner attachment part formed by laser beam cutting. The spring has an outer attachment plate in the plane of the coil formed with a channel which receives and protects the outer winding of the coil. The outer attachment plate has a curved attachment edge which allows the location of the oscillator dead point to be varied without affecting spring frequency.