Patent ID: 7433271
Filing Date: 2008-10-07
Classification: G04B

Abstract:
1. A calendar mechanism for displaying a date and a day of a week in a timepiece, comprising: a date indicator formed by a crown with an inner toothing; means for driving said date indicator including a first drive wheel having an external toothing so as to be able to be driven about an axis of rotation by a wheel set secured to an hour wheel of said timepiece, said external toothing comprising a prominent tooth and other teeth, said prominent tooth longer than said other teeth and disposed to abut against a tooth of the inner toothing of the date indicator to move it forward one day in a time interval located around a determined time of the day; a day of the week indicator; means for driving said day of the week indicator to move it forward one day during said time interval; means for positioning said indicators wherein said means for driving the day of the week indicator comprises a second drive wheel fitted with an external toothing, superposed and coaxial to the first drive wheel, wherein said first and second drive wheels have respective diameters that are equal and respective even numbers of teeth which are equal, said first and second drive wheels both engaging said wheel set secured to said hour wheel so as to be driven by said wheel set, wherein said wheel set is formed by a pinion secured to a pipe of said hour wheel and including a number of teeth equal to half of that of said first and second drive wheels, wherein said day of the week indicator is a disc coaxial to said date indicator, wherein said means for driving said disc include a day star-wheel secured to said disc and driven by said second drive wheel, wherein said second drive wheel pivots on a fixed arbour and includes a hub via which it is mounted on said arbour and which is connected to a crown carrying said teeth and an elastic arm substantially in the shape of an arc of a circle, attached at least indirectly to said hub and partially surrounding said hub, and wherein said elastic arm has at its free end a first drive finger substantially perpendicular to the plane of said second wheel which is engaged between the teeth of said day star-wheel to move said day of the week indicator disc forward one day of the week when said calendar mechanism is operating normally.