US 4,427,300 AGranted

Timepiece with a perpetual calendar mechanism

AssigneeCompagnie des Montres Longines

InventorMichel Groothuis

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Abstract

The mechanism comprises a date-disc (8) actuated at midnight by a lever (1) supporting a rotary part (3) with catches (3a) gearing with the wheel (4) of 24 h. The mechanism is so designed that each transition from a date to the next is effected in less than one hour so that the calendar remains still in synchronism with the hours hand, even in the case of the changing of the indication of time-zones. The disc comprises pins (14) controlling at the end of each month through a star-wheel (13) the rotation of a first (17) and a second (20) cam. The cams bear finger-pieces (17a,17b,21) the ones (17a,17b) of the first cam having variable widths according to the different lengths of the months forming bankings for a catch (9) of the lever (1) for hindering the return motion of this lever thus prolonging the duration of the gearing of the rotary part (3) with the disc (8). At the end of February of the normal years a finger-piece (17b) of the first cam (17) juxtaposes itself with a finger-piece (21) of the second cam (20) for causing the transition between the 28th of February and the 1st of March. This finger-piece (21) is missing in the leap years. The mechanism operates in the two directions of rotation of the wheel of 24 h.

Claims8

Dependent claims

An improved timepiece with a perpetual calendar mechanism of the type having a rotationally displaceable date-disc for indication of the date of the month, said date-disc being moveable in discrete angular displacement steps, drive means for rotating said date-disc and determining means for determining the number of displacement steps of said date-disc, said determining means being driven at the end of each calendar month by said date-disc and cooperating with said drive means so that said date-disc indicates the transition from the end of the month to the beginning of the next month, wherein the improvement comprises said determining means having:

(a) a months cam rotatable one full turn per year, said months cam having an outer periphery and month finger-pieces radially projecting from said periphery for sweeping a rotational path and for interaction with said drive means, each of said month finger-pieces having different angular widths for determining different durations of interaction with said drive means;
and
(b) a years cam rotatable one full turn in four years having an outer periphery and year finger-pieces radially projecting from said periphery for sweeping a rotational path cooperating with said month finger-pieces and said drive means for determining the number of date-disc rotation steps necessary to indicate the last day of the month and activate the drive means in order to advance the date-disc to the first date of the month even during leap years.

Dependencies are inferred from the claim text.