Patent ID: 7535802

Claim:
An annual calendar mechanism for a timepiece, including: a date ring including a lug and 31 teeth, and a date wheel set arranged for rotating said date ring through one step per day, an intermediate wheel set cooperating with said lug such that said date wheel set drives the intermediate wheel set through a first step when the date passes from the 30 th to the 31 st of the month, via said date ring, an annual wheel set meshed with the intermediate wheel set and cooperating with the date wheel set, said date, intermediate and annual wheel sets being arranged such that said date wheel set drives said intermediate wheel set through a second step when the date passes from the 31 st to the 1 st of the month, for the months of 31 days, via said date ring, and such that said date wheel set drives said intermediate wheel set through a second step after the date has passed from the 30 th to the 31 st of the month, for the months of less than 31 days, via the annual wheel set, the intermediate wheel set then driving the date wheel ring, said mechanism being wherein it further includes a month indicator ring including an inner flank fitted with teeth cooperating with said intermediate wheel set, said intermediate wheel set being arranged for rotating the month ring at least to said second step.