Method for forming a date indicator actuated by a clock movement and mechanism for implementing this method

A date mechanism for the implementation of a method for forming a date indicator actuated by a clock movement to show, in succession and automatically, all the days from 01.03 of one year to 28.02 of the next year, wherein the units and tens numerals are placed onto respective indicator runners comprising ten numerals or a multiple of ten, and four numerals or a multiple of four numerals, respectively, two drivelines are formed, one being a daily driveline between said clock movement and said indicator runners, for moving the unites indicator runner selectively step by step by one step every 24 hours, and for moving the tens indictor runner by one step for every ten steps of the units indicator runner, in order to move on from one multiple of ten to the next, and for moving said tens indicator alone by one step to move on from “31” to “01” on a 31-day basic cycle, and an annual driveline between said clock movement and said tens indictor runner, which driveline is programmed to move the tens indicator runner by one step at the same time as the units indicator runner is moved by the daily driveline, to move on from “30” to “01” at the end of the months which comprise less than 31 days,

• in which said units indicator runner is secured to a unit indicator runner equipped with ten teeth or a multiple of ten teeth and said tens indicator runner is secured to a tens runner equipped with four teeth or with a multiple of four teeth, a transmission connecting the units and tens runners to move the latter runner by one step for every ten steps of the units runner and a drive runner for driving the units runner, connected to the indicator geartrain of the timepiece, wherein a tooth of the units runner for moving on from “1” to “2” is a tooth of an auxiliary runner the rotation spindle of which is secured to the units runner and is able to engage alternately with the teeth of the tens runner and with a cam coaxial with and secured to this tens runner, this cam comprising, on the one hand, a part for angularly immobilizing said auxiliary runner and, on the other hand, a cut-out the position of which is chosen to allow said auxiliary runner to drive said tens runner by one step between “31” and “01”, and wherein said tens runner is shaped to engage selective with an annular runner itself selectively in engagement with said drive runner for driving the units runner, and said annual runner and said tens runner being in engagement, when the indicator runner moves the tens on from “2” to “3” and from “3” to “0”, said drive runner for driving the units runner being shaped to engage with said annular runner only when the date moves on directly from “30” to “01”.