Patent Publication Number: US-2021191330-A1

Title: Timepiece mechanism intended to be driven through a variable number of steps

Description:
TECHNICAL FIELD 
     The present invention relates to a timepiece mechanism for a timepiece movement, having
         a mobile comprising a toothset having at least one tooth of a first type and at least one tooth of a second type,   a jumper designed to cooperate with the toothset so as to define discrete positions of the mobile,   a pawl intended to be actuated by a drive mobile of the timepiece movement in order to act on the toothset and move the mobile by at least one step on each actuation.       

     According to a preferred embodiment, the timepiece mechanism may take the form of an annual, or perpetual, date display mechanism. 
     PRIOR ART 
     Such timepiece mechanisms have been known for a long time in the prior art in relation to different types of application, in particular in display mechanisms. 
     Thus, for example, the patent EP 3026504 B1 illustrates and describes an annual or perpetual date mechanism that complies with the above features. More specifically, that mechanism has a date wheel, bearing a hand for indicating the date, having thirty teeth of a first type and one tooth of a second type. The date wheel is driven by a first beak of an actuating pawl, once per day, in order to increment the display of the date. The actuating pawl comprises a second beak shaped, relative to the toothset of the date wheel, so as only to be able to cooperate with the tooth of the second type at the ends of months with fewer than 31 days. The actuating pawl is associated with a month wheel, driven so as to execute one turn in four years in order to take account of leap years, this month wheel having 48 notches, each of which corresponds to a given month, and the depth of which depends on the length of the corresponding month. The actuating pawl comprises a feeler intended to cooperate with the notches of the month wheel in order to define the starting position of the actuating pawl depending on the length of the current month. The notches are arranged such that the shorter a month, the deeper the corresponding notch and the sooner the second beak of the actuating pawl is able to cooperate with the tooth of the second type in the month, while turning the date wheel by a greater number of steps. The second beak is also shaped such that it does not drive the date wheel at the ends of months with 31 days. 
     Thus, it is apparent from the above explanation that the actuating pawl has a single total path that it will pass through in its entirety only during months of February with 28 days, that is to say when the feeler engages in the deepest notches of the month wheel, in order to define the longest travel of the actuating pawl, making it possible to advance the date wheel by four steps. The travel is reduced during months of February with 29 days in such a way that the date wheel is driven only by three steps, whereas it is reduced even more during months with 30, and then 31 days, the path of the actuating pawl during months with more than 28 days only corresponding to a portion of the total path passed through during months of February with 28 days. 
     Such a design makes it necessary to provide a relatively large diameter for the month wheel, in order to take into account the maximum possible travel for the actuating pawl, this not always being desirable depending on the space available in the corresponding timepiece movement. Moreover, great precision is necessary, both for manufacturing components of this mechanism and for the assembly thereof, in order to ensure that this mechanism for driving the date wheel operates properly. 
     SUMMARY OF THE INVENTION 
     A main aim of the present invention is to propose a timepiece mechanism having an alternative design that is more compact compared with mechanisms of this type that are already known. 
     To this end, the present invention relates more particularly to a timepiece mechanism of the type indicated above, wherein the pawl may exhibit a travel such that it is able to act on the toothset in order to move the mobile by two steps on each actuation, wherein the timepiece mechanism may have a correction mobile having at least one first state and at least one second state, different from the first state, the correction mobile being designed so as to be able to cooperate with the pawl, during the actuation of the latter, to define at least two different paths of the pawl that are associated with the first state and with the second state, respectively, and by the fact that the pawl and the correction mobile are designed such that, on each actuation of the pawl:
         the pawl acts on the toothset to move the mobile by one step, and   the pawl acts on the toothset to move the mobile by an additional step only when the correction mobile is in a second state and the tooth of the second type is situated along the travel of the pawl.       

     By virtue of these features, the correction mobile intervenes to modify the path of the pawl during the actuation thereof, and can hence be arranged in the vicinity of the mobile that the pawl drives, in any rate closer than in the case of the month wheel, in the abovementioned date display mechanism, in as much as the month wheel needs to be able to position the pawl before the actuation thereof. Thus, the timepiece mechanism according to the present invention can be realized in a much more compact manner than the equivalent mechanisms of the prior art. Moreover, the positioning of the correction mobile makes it possible to substantially simplify the adjustments that are necessary during the assembly of the mechanism compared with the mechanisms of the prior art. 
     Preferably, the mobile, the pawl and the correction mobile may be designed such that the travel of the pawl has two successive phases: an optional driving phase in which the toothset is able to be driven by only one step when the correction mobile is in a second state and the tooth of the second type is situated along the travel of the pawl, and a systematic driving phase in which the toothset is able to be driven by one step, regardless of the type of tooth situated along its travel and regardless of the state of the correction mobile. 
     In this case, provision may also be made for the mobile to be designed to pivot and to have an internal toothset, and for the mobile, the pawl and the correction mobile to be designed such that the optional driving phase occurs before the systematic driving phase. 
     Provision may also be made for each of the teeth of the first type to have an active flank, intended to cooperate with the pawl, that is different from the active flank of the tooth of the second type, such that the cooperation between the pawl and the toothset in the optional driving phase, when the correction mobile is in a second state, only gives rise to a force driving the mobile that is sufficient to overcome the action of the jumper when a tooth of the second type is situated along the travel of the pawl. 
     In this case, provision may also be made for the active flank of the tooth of the first type to comprise, from the bottom of the toothset, a first portion having a first mean inclination, with respect to the radial direction, and then a second portion having a second mean inclination, with respect to the radial direction, greater than the first mean inclination, and for the active flank of the tooth of the second type to have a third mean inclination, with respect to the radial direction, smaller than the second mean inclination. 
     Provision may thus advantageously be made for the second mean inclination to be substantially between 30 and 85 degrees with respect to the radial direction, preferably between 35 and 55 degrees. 
     Alternatively or in addition, provision may be made for the first mean inclination to be substantially between 0 and 25 degrees with respect to the radial direction, preferably between 5 and 15 degrees. 
     Alternatively or in addition, provision may be made for the third mean inclination to be substantially between 0 and 25 degrees with respect to the radial direction, preferably between 5 and 15 degrees. 
     Generally, provision may be made for the correction mobile to have a cam against the periphery of which the pawl is kept in abutment during the optional driving phase, in order for it to be able to modify the path of the pawl, the periphery of the cam having at least first and second radii that are different and associated with the first and second states, respectively, of the correction mobile. 
     In this case, provision may advantageously be made for the correction mobile to have a toothset intended to cooperate with at least one tooth of the mobile that exhibits a length greater than that of the other teeth of the mobile, in order to modify the angular orientation of the cam. 
     According to a preferred embodiment variant, the present invention may relate to a timepiece mechanism that complies with all or some of the features that have just been set out, and in which the mobile is intended to be secured to a date display mobile or to drive the latter,
         the toothset having thirty teeth of the first type and one tooth of the second type,   the pawl being intended to be actuated once per day in order to move the mobile by one or two steps, and   the correction mobile being a month mobile designed such that its angular orientation, associated at each moment with a given month, passes from one month to the next at each month end.       

     The present invention also relates to a timepiece movement and a timepiece having a timepiece mechanism that complies with the above features. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the present invention will become more clearly apparent from reading the following detailed description of a preferred embodiment, given with reference to the appended drawings, which are given by way of non-limiting example and in which: 
         FIG. 1  shows a bottom view of a part of a timepiece mechanism according to a preferred embodiment of the present invention, the correction mobile being in a first state, 
         FIG. 2  shows a view similar to the one in  FIG. 1 , the correction mobile being in a second state, 
         FIG. 3  shows a perspective view of the correction mobile, 
         FIG. 4  shows a top view of the timepiece mechanism in  FIGS. 1 and 2 , illustrated from the opposite face to the one in  FIGS. 1 and 2 , the correction mobile being in a second state, 
         FIGS. 5 a  to 5 e    show views similar to the one in  FIG. 4 , illustrating successive phases in the operation of the timepiece mechanism during the change of the day of the month from the thirtieth of a short month to the first of the following month, and 
         FIGS. 6 a  to 6 c    shows view similar to the one in  FIG. 4 , illustrating successive phases in the operation of the timepiece mechanism during the change of the day of the month from the thirtieth to the thirty-first of a long month. 
     
    
    
     EMBODIMENT(S) OF THE INVENTION 
     The following detailed description aims to describe a timepiece mechanism according to a preferred embodiment of the present invention by way of non-limiting illustrative example. More specifically, according to the embodiment illustrated and described, the timepiece mechanism has the form of annual date display mechanism  1  but, of course, a person skilled in the art could implement other types of timepiece mechanisms that employ the features set forth in the claims without departing from the scope of the present invention. 
       FIGS. 1 and 2  show one and the same bottom view of a part of the annual date display mechanism  1  according to a preferred embodiment of the invention, illustrated with its lower face visible, that is to say its face that is intended to be situated on the bottom side of the case of the corresponding timepiece, respectively in two different configurations. More particularly,  FIG. 1  illustrates the configuration of the mechanism  1  on 30 October before the change of the date, while  FIG. 2  illustrates the configuration thereof on 30 November, likewise before the change of the date. 
     The mechanism  1  has a mobile  2 , in this case in the form of a date disc, having an internal toothset comprising thirty teeth of a first type  4  and one tooth of a second type  6 . 
     A jumper  8  is designed to cooperate with the toothset of the mobile  2  and to define a plurality of discrete positions of the latter, in this case thirty-one. 
     The mechanism  1  also has a pawl  10  intended to be actuated by a drive mobile of the timepiece movement (not shown, typically a 24-hour wheel for example in the case of a date display mechanism) in order to act on the toothset of the mobile  2  and move the latter by at least one step on each actuation. 
     The pawl  10  in this case has, by way of non-limiting illustration, a rigid base  12  intended to be pivoted with respect to the corresponding timepiece movement about an axis of rotation  14 . The base  12  is kept in a rest position illustrated in  FIGS. 1 and 2  under the effect of the action of a return member (not shown) that tends to push it into abutment against a fixed pin  16 . An actuating tooth  18  is secured to the base  12  by way of an elastic connection  20 , the actuating tooth  18  typically being intended to cooperate with the drive mobile of the associated timepiece movement in order to ensure that the pawl  10  moves, by rotation of the base  12  in the anticlockwise direction of rotation in  FIGS. 1 and 2 . 
     An arm  22  is furthermore mounted on the base  12  so as to pivot about an axis of rotation  24 . The arm  22  bears a beak  26 , at a first end, that is intended to cooperate with the toothset of the date mobile  2  so as to turn the latter in the anticlockwise direction of rotation in  FIGS. 1 and 2  (in the clockwise direction in  FIGS. 4 to 6   c ) when the pawl  10  moves under the effect of the action of the drive mobile. Furthermore, the arm  22  bears a tail  28 , the edge of which that is directed towards the centre of the timepiece movement has a convex shape, the function of which will be explained below. 
     A spring  30 , formed in this case in one piece with the base  12 , is designed to act on the arm  22  and tends to turn it in the clockwise direction of rotation in the view in  FIGS. 1 and 2 . 
     The mechanism  1  furthermore has a correction mobile  32 , shown in detail in  FIG. 3 , which is realized in this case in the form of two superposed wheels  34 ,  36 , which rotate as one and one of which has a 24-tooth toothset, every other tooth of which is slightly truncated, and the other one of which has seven teeth corresponding to the long months having 31 days. 
     The first, 24-tooth wheel  34  is intended to allow the correction mobile  32  to be driven in rotation, by cooperation thereof with a prominent tooth  400  that has a greater height than the others for this purpose. In the embodiment presented, the prominent tooth  400  is a tooth of the first type  4 , but other arrangements are possible for driving the correction mobile. 
     The second wheel  36  acts as a cam for the pawl  10 , cooperating with the tail  28  thereof, the periphery of the wheel  36  in this case comprising portions having at least two different radii. Specifically, by virtue of the shape of the second wheel  36  and the seven teeth that it comprises, the correction mobile  32  can exhibit two different states with respect to the pawl  10 , a first state, illustrated in  FIG. 1 , in which one tooth of the second wheel  36  defines a stop for the tail  28 , and a second state, illustrated in  FIG. 2 , in which the second wheel  36  has an empty space between two teeth facing the tail  28 , the pawl then bearing against a portion of the second wheel  36  with a smaller radius than in the first state. 
     It is apparent from a comparison on  FIGS. 1 and 2  that, in at least some positions of the base  12 , under the effect of the action of the spring  30 , the tail  28  is kept in abutment against the correction mobile  32  and the beak  26  is situated further away from the toothset of the date mobile  2  when the correction mobile  32  is in a first state ( FIG. 1 ) than when the latter is in a second state ( FIG. 2 ). 
     Thus, in the first case, on 30 October, when the pawl  10  is actuated by the drive mobile, with its base  12  pivoting in the anticlockwise direction of rotation, its beak  26  has a path such that it cannot come into contact with the tooth of the second type  6  on account of the interaction of its tail  28  with the correction mobile  32 . When the movement of the pawl  10  continues, the beak  26  continues its travel along a path such that it comes into contact with the tooth of the first type  4  situated immediately after the tooth of the second type  6 , in order to advance the date mobile  2  by one step in the anticlockwise direction of rotation. 
     The display of the day of the month then passes from 30 to 31 (October) and the pawl  10  returns to its rest position as illustrated in  FIG. 1  after the drive mobile stops acting. The next day, during the actuation of the pawl  10  by the drive mobile, the beak  26  will again exhibit the same travel extending through two steps of the date mobile  2 , with the same path passing, during a first phase, at a distance from a first tooth (in this case the tooth of the first type  4  situated immediately after the tooth of the second type  6 ) and then intercepting, in a second phase, the tooth of the second type  6  so as to advance the date mobile by one step, causing the display of the date to pass from 31 (October) to 1 (November). 
     It will be seen that the base  12  of the pawl  10  has the same rest position in both states of the correction mobile, this not being the case for corresponding mechanisms of the prior art, as mentioned above. Thus, regardless of the state of the correction mobile  32 , the pawl  10  follows the same travel; in other words, it is moved such that it is capable of advancing the mobile  2  by two steps on each actuation by the drive mobile. 
     It is apparent from  FIG. 2  that the pawl  10  has a different path when it is actuated during a short month with fewer than 31 days from the one that it has when it is actuated during a long month with 31 days. Specifically, with the beak  26  being situated in the vicinity of the toothset of the mobile  2 , the path of the pawl  10  will directly intercept the first tooth situated along the travel of the pawl  10 , in this case the tooth of the second type  6 , as early as the first phase of the travel, in order to drive the date mobile by a first step during this phase. The pawl  10  then continues to move in a second phase, driving the tooth of the second type  6  by an additional step, as will become more clearly apparent from the following explanations in relation to  FIGS. 5 a  to 5 e   . Thus, the display of the date passes directly from 30 (November) to 1 (December) in a single actuation of the pawl  10 . 
     Generally, it is apparent from the above explanations that the pawl  10  systematically has a travel that allows it to advance the mobile  2  by two steps, this travel being able to be broken down into two successive phases, an optional driving phase and a systematic driving phase corresponding to the above-described first and second phases, respectively. 
     Furthermore, it will be noted that, while each tooth of the mobile  2  has an active flank intended to cooperate with the pawl  10 , the active flank of the teeth of the first type  4  is different from the active flank of the tooth of the second type  6 . Generally, provision may be made for the teeth of the first type  4  and the tooth of the second type  6  to be differentiated such that the cooperation between the pawl  10  and the toothset of the mobile  2  in the optional driving phase, when the correction mobile  32  is in a second state, only gives rise to a force driving the mobile  2  that is sufficient to overcome the action of the jumper  8  when the tooth of the second type  6  is situated along the travel of the pawl  10 . Thus, in the case of the design illustrated, the teeth of the first type  4  are intended to cooperate with the pawl  10  from the first day of the month until the penultimate day of the month, while the tooth of the second type  6  is intended to cooperate with the pawl  10  on the last day of the month, whether the current month has 30 or 31 days. When the correction mobile  32  is in a first state, the pawl  10  can only act on the tooth of the second type  6  on the 31st day of the month ( FIG. 1 , month of October), while it can act thereon as early as the 30th day of the month when the correction mobile  32  is in a second state ( FIG. 2 , month of November). 
     It is thus clear that the correction mobile  32  cooperates with the pawl  10  in order to define two different paths thereof, one of which is associated with the first state and the other of which is associated with the second state, the travel of the pawl  10  for its part remaining unchanged in both cases, and corresponding to a movement of the pawl  10  that is liable to advance the mobile  2  by two steps in all cases. 
     More specifically here, the differentiation between the types of teeth according to the preferred embodiment of the invention, by way of non-limiting illustration, resides in the respective geometries thereof. Specifically, the active flank of a tooth of the first type  4  comprises, from the bottom of the toothset, a first portion having a first mean inclination, with respect to the radial direction, and then a second portion having a second mean inclination, with respect to the radial direction, greater than the first mean inclination. In a different way, the active flank of the tooth of the second type  6  has a third mean inclination, with respect to the radial direction, smaller than the second mean inclination. It is thus possible to define inclinations of the different portions of the teeth and a shape for the beak  26  such that, when these teeth lie along the travel of the pawl corresponding to the optional driving phase, the pawl can slide over the second portion of the active flank of a tooth  4  of the first type, as illustrated in the configuration in  FIG. 4 , while it would act on the active flank of the tooth of the second type  6  in order to drive the mobile  2 , as shown in  FIGS. 5 a    and  5   b.    
     By way of non-limiting illustrative example, provision could be made for the first and third mean inclinations both to be substantially between 0 and 25 degrees with respect to the radial direction, preferably between 5 and 15 degrees (without necessarily having the same value). The second mean inclination could be substantially between 30 and 85 degrees with respect to the radial direction, preferably between 35 and 55 degrees. 
     By virtue of such angles, when a tooth of the first type  4  is situated on the path of the pawl  10  during the optional driving phase, the beak  26  comes into contact with the second portion of the corresponding active flank, said second portion being inclined too much for the pawl  10  to be able to drive the mobile  2  in this case. 
     Such a situation occurs for example from the 1st to the 29th of a short month, the correction mobile  32  being in a second state, as illustrated in  FIG. 4 . Thus, from the 1st to the 29th of a short month, the pawl  10  cannot drive the mobile  2  during the optional driving phase. On continuing along its path after the optional driving phase, the pawl  10  comes into contact with the first portion of a tooth of the first type  4  in the systematic driving phase and then turns the mobile  2  by one step in the clockwise direction of rotation in the view in  FIG. 4 . 
     On 30 November, the mechanism is in the situation illustrated in  FIG. 2 , the tooth of the second type  6  being positioned on the path of the pawl  10  as early as the optional driving phase. The shape of the active flank of the tooth  6  then makes it possible for the pawl  10  to drive the mobile  2  by one step as early as the optional driving phase, and then to drive it by an additional step in the systematic driving phase. 
       FIGS. 5 a  to 5 e    illustrate the chronology of the driving of the mobile  2  by the pawl  10  when the day of the month passes from the 30th of a short month to the 1st of the next month, each of the optional driving phase and the systematic driving phase being broken down into a plurality of steps. A part of the timepiece mechanism  1  is shown in these figures in a top view from the dial side of the corresponding timepiece. 
       FIG. 5 a    illustrates the configuration of the timepiece mechanism  1  before the pawl  10  is actuated by the drive mobile of the timepiece movement. A drive finger (not shown) can thus be provided in order to move the pawl  10  once per day, by rotation of its base  12  in the clockwise direction of rotation. 
     As is apparent from  FIG. 5 a   , the correction mobile  32  is in a second state corresponding to a short month having fewer than 31 days, the tail  28  of the pawl  10  being arranged between two teeth of the second wheel  36  of the correction mobile  32 , and thus bearing against a portion of small radius of the second wheel  36 . 
     Thus, during the optional driving phase, the path of the pawl  10  intercepts the toothset of the mobile  2 . On the 30th of the month, the tooth of the second type  6  is situated along the travel corresponding to the optional driving phase of the pawl  10 . As a result, the latter cooperates therewith so as to drive the mobile  2  and advance it by a first step. 
     The start of this first step is illustrated in  FIG. 5 b   , by the fact that the mobile  2  has started to turn in the clockwise direction of rotation in the view in  FIG. 5 b   , counter to the force to which it is subjected by the jumper  8 . Specifically, the latter is no longer arranged in simultaneous abutment against two adjacent teeth of the mobile  2 , as is normally the case in the rest position, since it is only in abutment against the inactive flank of a tooth  4 . 
     Inscriptions  40  of the date have been shown on the mobile  2 . These inscriptions  40  can be carried directly by the mobile  2  or, alternatively, by an additional disc secured to the mobile  2 , by way of non-limiting illustration. An aperture  42  is also shown in order to schematically indicate the position at which the date is read according to the embodiment illustrated, in a non-limiting manner. 
     When the jumper  8  passes over the top of the tooth  4  against which it is in abutment, it exerts a pressure force on the active flank of this same tooth  4 , this having the effect of turning the mobile  2  into its next discrete position, as shown in  FIG. 5 c   , in which the jumper  8  is arranged simultaneously in abutment against two adjacent teeth  4 . The inscription  40  of “31” is then situated facing the aperture  42 . 
     With the drive mobile continuing to turn the base  12  of the pawl  10  in the clockwise direction of rotation, the latter catches up with the tooth of the second type  6  which was moved forward under the effect of the action of the jumper  8 . 
     At the same time, the tail  28  of the pawl  10  is moved away from the correction mobile  32  and the angular orientation of the arm  22  is then defined by the action of the spring  30  and by the interaction of the beak  26  with the toothset of the mobile  2 , and no longer by the tail  28  bearing against the second wheel  36  of the correction mobile  32 , in a non-limiting illustrative manner. 
     On continuing to move, under the effect of the action of the drive mobile, the pawl  10  begins the systematic driving phase by starting to drive the mobile  2  counter to the force of the jumper  8  again, putting the mechanism into the configuration illustrated in  FIG. 5   d.    
     Provision may be made for the correction mobile  32  to bear inscriptions  44  indicating the current month that are designed to cooperate with a suitable aperture  46 . Thus, the inscription  44  relating to the month of February appears in the aperture  46  in the configurations illustrated in  FIGS. 4 to 5   d.    
     As mentioned above, the prominent tooth  400  has a height greater than that of the other teeth. It is apparent from  FIGS. 5 d  and 5 e    that, when the date mobile  2  passes from the position associated with the 31st of a given month to that associated with the 1st of the next month, the prominent tooth  400  meshes with the toothset of the first wheel  34  of the correction mobile so as to turn the first wheel  34  by two steps in the clockwise direction of rotation in the view in  FIGS. 5 d  and 5 e   . By virtue of this operation, the correction mobile  32  turns from an angular orientation associated with a given month to another angular position associated with the next month. 
     Once the top of the tooth  4  has been passed over, the jumper  8  acts on the active flank of this same tooth  4  in order to complete the movement of the mobile  2 , as illustrated in  FIG. 5 e   . The inscription  40  of “1” is then correctly positioned facing the aperture  42 , and in the same way the inscription  44  relating to the next month is positioned properly facing the aperture  46  after the correction mobile  32  has been driven by two steps in the clockwise direction of rotation. 
     At the end of the cycle, the pawl  10  returns to its rest position, meaning the position in which it is in abutment against the fixed pin  16 . 
     By turning through two steps, the correction mobile  32  is in this case passed from a second state corresponding to a short month to a first state corresponding to a long month. Thus, by returning into its rest position, the pawl  10  no longer cooperates with a portion of reduced radius of the second wheel  36  but with one of the teeth thereof, in the position shown in  FIG. 6   a.    
     Of course, the forces respectively applied by the return member to the base  12 , for the one part, and by the spring  30  to arm  22  of the pawl  10 , for the other part, are adjusted relative to one another such that, when the drive finger releases the pawl  10  and the base  12  is driven in rotation in the anticlockwise direction in  FIG. 5 e   , under the effect of the action of the return member, the arm  22  can pivot in the clockwise direction, bearing on the tooth of the second wheel  36 . Thus, the action of the return member takes precedence over that of the spring  30 . 
       FIGS. 6 a  to 6 c    show the passage from the 30th to the 31st of a long month. On the 30th of the month, the tooth of the second type  6  is situated along the travel of the pawl  10  during the optional driving phase. The correction mobile  32  is in its second state and diverts the pawl  10 , the beak  26  of which passes over the tooth of the second type  6  without driving it during the actuation of the base  12 . The beak  26  then dips behind the tooth of the second type  6  in order to drive the tooth of the first type  4  that directly follows it, during the systematic driving phase ( FIGS. 6 b  and 6 c   ). 
     By virtue of the features that have just been presented, a timepiece mechanism is obtained that has a mobile that is able to be driven by a variable number of steps by virtue of the intended interaction between the actuating pawl of the mobile in question and a suitable correction mobile, which is able to take up at least one first state and one second state, different from the first state, in order to define two different paths of the actuating pawl. 
     The implementation of the present invention is not limited to the display of the date. Specifically, a person skilled in the art will have no particular difficulty in adapting the present teaching to the implementation of another type of timepiece mechanism, in particular a mechanism for displaying a variable other than the date. 
     The above description aims to describe a particular embodiment by way of non-limiting illustration and the invention is not limited to the implementation of certain particular features that have just been described, for example the shape of the correction mobile  32  or the nature of its interaction with the pawl  10 , as described and illustrated. Specifically, it is sufficient, in order to implement the invention, for the correction mobile to have two different states in which it interacts in two different respective manners with the actuating pawl in order to define two different paths of the latter. Thus, it may be conceivable to provide for the correction mobile to comprise simply a shuttle that moves back and forth and bears a cam having two portions with different radii. The existence of optional and systematic driving phases, as described, is not indispensable to the implementation of the invention, either, and nor is the order in which they follow one another. It will thus be noted, for example, that in the case of a mobile having an external toothset, it will be simpler to provide for the systematic driving phase to occur before the optional driving phase. 
     Furthermore, an approach other than a geometric approach could be provided to ensure the differentiation of the interactions that occur between the pawl and the teeth of the first type, for the one part, and the tooth of the second type, for the other part. Thus, the active flanks of these teeth could for example be differentiated by using different roughnesses or by implementing different magnetic interactions. 
     Generally, while the pawl  10  described and illustrated in the present application is made in two parts (the base  12  and the arm  26 ), it is likewise possible to make it using more components or, conversely, to make it in one piece, for example on the basis of the teaching in the patent application CH 713288 A1. 
     Also generally, when the path of the pawl can be broken down into an optional driving phase and a systematic driving phase, provision may be made for the correction mobile to interact with the pawl throughout the optional driving phase or only during a part of this phase without departing from the scope of the invention. Furthermore, interaction between the correction mobile and the pawl outside the optional driving phase is likewise conceivable without departing from the scope of the invention. 
     The above disclosure allows persons skilled in the art to produce a wide variety of timepiece mechanisms having a mobile that is able to be driven by a variable number of steps by a pawl that always has the same travel, making it possible to advance the mobile by the maximum number of steps possible, the pawl cooperating with a correction mobile in order to define several paths of the pawl within this travel, depending on the state of the correction mobile, and thus to define the number of steps by which the mobile is advanced for a given state, depending on their specific needs, and without departing from the scope of the present invention.