Annual data mechanism for a timepiece movement
This mechanism comprises a date runner, a months satellite with five teeth on a pitch for twelve, secured to the date runner, a fixed planetary toothset and a drive member for driving the date runner comprising two drive fingers, the first intersecting the path of the toothset of the date runner, the second intersecting the path of the toothset of the months satellite. The latter is connected to the planetary toothset by a second satellite secured to it and the number of teeth of which is equal to a multiple of twelve, the number of teeth of the planetary toothset being chosen so that one of the five teeth of the months satellite is aligned with the axes of the satellites, of the drive member and of the date runner on the 30th of each month comprising less than 31 days.
1. An annual date mechanism for a timepiece movement comprising a 31-toothed date runner, a jumper in mesh with its toothset, a months satellite, the rotation pin of which is secured to this date runner and which comprises five driving teeth of a toothset on a pitch designed for twelve for the months comprising less than 31 days, a fixed planetary toothset coaxial with the date runner and in a direct-drive relationship with the months satellite and a drive member for driving the date runner in a driving relationship with the hours wheel of the timepiece movement and comprising two drive fingers, the first intersecting the path of the toothset of the date runner, the second intersecting the path of the toothset of the months satellite when its axis of revolution is aligned with those of the planetary toothset, of the drive member and of the date runner, wherein the months satellite is connected to the planetary toothset by a second satellite which is secured to it and coaxial and the number of teeth of which is equal to a multiple of twelve, and the toothset of each of said satellites works on a pitch circle tangential to the pitch circle of the toothset with which it is in mesh, the number of teeth z i of the planetary toothset being chosen from numbers or multiples of numbers obtained according to the formula:
z i+1 =z i +3+(−1) i , with i =1, 2, 3, . . . , and z 1 =5
so that each revolution of the date runner corresponds to a non-integer number of revolutions of the satellites such that one of the five teeth of the months satellite is more or less aligned with the axes of the satellites, of the planetary toothset and of the drive member driving the date runner on the 30th of each month comprising less than 31 days so as to allow said second finger to drive the date runner by an additional step via said satellites.
2. The date mechanism as claimed in claim 1 , in which the axis of revolution of the drive member driving the date runner, when aligned with the respective axes of revolution of the satellites and of the planetary toothset, lies between their axes of revolution.
3. The date mechanism as claimed in claim 1 , in which the second satellite has a diameter appreciably larger than that of the months satellite so that the direction of rotation of satellites when they are being driven by the second drive finger is the same as that of the drive member bearing said second finger.
4. The date mechanism as claimed in claim 1 , in which the date runner is an annulus with an internal toothset.
5. The date mechanism as claimed in claim 1 , in which said drive member is connected to the hours wheel of the timepiece movement by an instantaneous-drive device.