Patent ID: 8821007

Claim:
An anti-trip balance spring for a timepiece comprising at least one strand wound between a first end and a second end and comprising at least two pairs of coils each formed of a first coil and a second coil immediately adjacent to each other, respectively comprising an stopping means and a complementary stopping means, wherein, in at least two of said pairs of coils, said respective stopping means and complementary stopping means are arranged so as to define different maximum angular travel values, in order to gradually limit the amplitude of pivoting between said first end and said second end of said balance spring during angular or radial accelerations of said balance spring which are greater than desired values, so as to cause said stopping means and said complementary stopping means of one of said pairs to cooperate in abutment before those of said other pair, and thus to gradually modify the resulting rigidity of said balance spring by successively deactivating or reactivating some of the coils thereof.