Perpetual calendar date mechanism for watch, has ratchet cooperating with surface of correction cam to retard input of ratchet for permitting ratchet to displace date wheel when displacement amplitude is higher than present amplitude

摘要

The mechanism has a driving unit (19) with ratchets (24, 25) integrated to respectively cooperate with a calendar date wheel (27) and a correction cam (29). The ratchet (25) cooperates with a surface of the cam (29) to retard an input of the ratchet (24) in gear teeth of the wheel. The input retarding permits the ratchet (24) to displace the wheel from a step during passing from a day to the next day within a month when a displacement amplitude defined by month and leap year cams (12, 39) is higher than a present amplitude corresponding to an end of months having thirty days.