Patent ID: 7706214

Claim:
A perpetual or annual calendar mechanism comprising: a date mobile ( 16 , 28 - 31 ); and means ( 2 , 3 , 4 , 14 , 40 ) for driving the date mobile, wherein the driving means are arranged so that, during the transition from one day to the next within a month, the date mobile is shifted in an instantaneous manner, and during the transition from the last day of a month of less than 31 days to the first day of the following month, the date mobile is shifted in a dragging manner until it reaches an angular position corresponding to the 31 st and then in an instantaneous manner to pass from the 31 st to the 1 st , said instantaneous shifts of the date mobile being effected by a first driving member of said driving means dropping under the action of a first return spring, said dragging shift of the date mobile being effected by a second driving member of said driving means progressively moving against the action of a second return spring.