| 摘要 |
FIELD: individual supplies. ^ SUBSTANCE: invention concerns clock industry. Effect is achieved by forming the claimed balance spring by first and second units. First unit includes coils and external spiral and is made of first material, such as elinvar, showing some elastic torsion momentum and insensitive to elongation or change of temperature or magnetic field. Second unit is attached to the first one and includes internal spiral made of second material selected for mechanical properties facilitating internal spiral shaping along most appropriate shape to create concentric extension of balance spring. For instance, this shape can be Grossman curve. The second unit can also include crown. ^ EFFECT: improved isochrony of chronometre. ^ 7 cl, 3 dwg |
