Patent Publication Number: US-2007109916-A1

Title: Annual calendar mechanism for watch movement

Description:
This application claims priority from European Patent Application No. 05024628.9 filed Nov. 11, 2005, the entire disclosure of which is incorporated herein by reference.  
      The present invention concerns an annual calendar mechanism for a watch movement associated with a month indicator mechanism. This type of calendar mechanism display the exact day of the month, performing a single correction per year of one or two days to change the date to the first of March at the end of the month of February.  
      An annual calendar mechanism for a watch movement is disclosed in EP Patent No. 0 987 609 in the name of Frédéric Piguet. According to this Patent, the mechanism comprises a date disc provided with thirty one inner teeth located at a first level and to which thirty one figures are affixed, each corresponding to an indication of the day of the month, these figures appearing in succession through an aperture arranged in a dial. A drive wheel set for the date disc comprises a drive wheel that is connected via an intermediate wheel set to the hour wheel of the watch movement. This drive wheel set, fitted with a drive finger, completes one revolution in twenty-four hours and is able to drive the date disc through one step once per day via its inner toothing to control the date display.  
      The Piguet mechanism further comprises a device for correcting the date indication at the end of each of the months of less than thirty-one days. The date disc therefore comprises a second toothing secured to the date disc and located at a second level. This additional toothing is provided with two juxtaposed teeth spaced from each other by a thirty first of a revolution and drives once a month a wheel which carries a month cam via two intermediate wheels. The month cam is arranged to be actuated at the end of each month by the additional tooth and to make one revolution per year. It carries fine teeth corresponding to the months of less than thirty one days, each of these teeth being arranged to be at the end of the months of less than thirty one days, on the path of the beak of a lever. This lever carries a correction wheel set fitted with a correction finger able to cooperate with the second toothing at the end of the months of less than thirty one days to drive the date disc through an additional step at the end of these months of less than thirty one days when the lever pivots following the passage of its beak over a tooth of the month cam. The correction wheel set is arranged, like the date drive wheel set, to complete one revolution in twenty-four hours.  
      The mechanism as described has several drawbacks. First of all, the month cam, which includes indications identifying the months of the year and appearing in succession through an aperture pierced in the watch dial, is driven, as has just been seen, by a toothing secured to the date disc. Consequently, it is impossible to correct the month indication without having simultaneously to act on the date mechanism. This can be inconvenient when the watch has, for example, stopped on the 10 th  day of a given month and when one wishes to reset it to the correct date on the 15 th  day of the following month. In such case, one would have to scroll down in succession all of the numbers corresponding to the date indications from the “11 th ” to the “31 st ” then from the “1 st ” to the “15 th ”.  
      Moreover, as has also been seen, the device for correcting the date indication at the end of each of the months of less than thirty one days requires a second toothing to be provided on the date disc, provided with two juxtaposed teeth separated from each other by a thirty first of a revolution. The month cam is arranged to be actuated in succession by each of these two teeth by moving forward by one twenty fourth of a revolution each time. If a quick correction device were used, one would not be able to determine which of the two teeth of the second toothing of the date disc was about to actuate the month cam, such that a phase shift would be liable to occur between the date display and the month indication. This quick correction mechanism therefore cannot be employed in the annular calendar mechanism disclosed in the Piguet Patent.  
      Finally, the Piguet mechanism cannot be used with an instantaneous calendar device. Thus, referring to the Figures of the Piguet Patent, it can be seen that at midnight on the 30 th  of a month of thirty days, the date ring indicates the 31 st . Consequently, during a time period that extends from 21h00 on the “30 th ” of a month of 30 days and 02h30 on the “ 1   st ” day of the month following the month of thirty days, the date indication provided by the watch is incorrect.  
      It is an object of the present invention to overcome the aforementioned drawbacks in addition to others by providing an annual date mechanism for a watch movement which, in particular, can be corrected simply and quickly.  
      The invention therefore concerns an annual calendar mechanism for a timepiece comprising a date disc to which thirty one figures are affixed, each corresponding to an indication of a day of the month and fitted with a first inner toothing comprising thirty one teeth, a date drive wheel set, this wheel set including a finger driving the date disc through one step once per day via one of the teeth of the first inner toothing to control the date display, said date disc comprising a second toothing, an additional correction drive wheel set able to cooperate with the second toothing to drive the date disc through one additional step at the end of the months of less than thirty one days and a month cam arranged to be actuated at the end of each month and to complete one revolution per year, characterized in that it includes a month drive wheel set provided for driving the month cam at the end of each month, said drive wheel set being connected, via a gear train, to the date drive wheel set and to the correction drive wheel set, said wheel set occupying a first position in which it has no effect on the month cam such that the kinematic chain between the date disc and the month cam is broken, and a second position that it only occupies at the moment when a change of month occurs and in which it actuates the month cam so as to move it forward one step.  
      Owing to these features, the present invention provides an annual date mechanism in which the date disc is not kinematically connected to the month cam, except during the time interval necessary for the mechanism to pass from the end of one month to the start of the next month. Correction of the month can thus be made independently of the date correction. It can thus be achieved much more quickly than in the case where the date disc is permanently connected to the month cam and where the date has to be rotated through thirty one days in order to correct the month indication.  
      According to a complementary feature of the invention, the date drive wheel set, the correction drive wheel set and the month drive wheel set are driven by an instantaneous release mechanism.  
      Owing to this other feature, the present invention provides an annual calendar mechanism in which the date and month indications are corrected quasi instantaneously. The user can thus barely see the display correction steps. Moreover, the watch fitted with the date mechanism according to the invention permanently provides an exact indication of the date and month. This is particularly well appreciated at a change from a month of less than thirty-one days to the first day of the next month. Indeed, as described above, in the case of annual calendar watches of the prior art, correction of the display occurs gradually, in a manner known as sliding in the horological field, and takes several tens of minutes, or even several hours to complete. During this time period, the watch provides incorrect data and month indications. Conversely, according to the invention, these indications are corrected instantaneously, such that the watch always provides the user with correct indications. 
    
    
      Other features and advantages of the present invention will appear more clearly upon reading the following detailed description of an embodiment of the annual calendar mechanism according to the invention, this example being given purely by way of non limiting illustration, with reference to the annexed drawing, in which:  
       FIG. 1  is a plan view of a watch fitted with an annual calendar mechanism according to the invention;  
       FIG. 2  is a plan view of the annual date mechanism according to the invention in a position preceding the passage of the date disc from the “30 th ” to the “31 st ” at the end of month of less than thirty-one days;  
       FIG. 3  is a similar view to that of  FIG. 2 , with the annual calendar mechanism according to the invention passing from the “30 th ” to the “31 st ” at the end of a month of less than thirty-one days;  
       FIG. 4  is a similar view to that of  FIG. 3 , with the date mechanism according to the invention preparing to pass from the “31 st ” to the first day of a month of thirty-one days;  
       FIG. 5  is a similar view to that of  FIG. 4 , with the annual calendar mechanism according to the invention at the first day of a month of thirty-one days;  
       FIG. 6  is a perspective view of the date disc;  
       FIG. 7  is a bottom plan view of the instantaneous release system;  
       FIG. 8  is a top plan view of the drive wheel of the instantaneous release system;  
       FIG. 9  is a perspective view of the month star wheel;  
       FIG. 10  is a perspective view of the lever cooperating with the month star wheel shown in  FIG. 9 ;  
       FIG. 11  is a plan view of the dial side of the quick correction system in the neutral position;  
       FIG. 12  is a plan view of the back cover side of the quick correction system of  FIG. 11  again in the neutral position;  
       FIG. 13  is a similar view of that of  FIG. 12  but in which certain pieces have been omitted in order to show the pieces located at lower levels;  
       FIG. 14  is a plan view showing the corrector pinion of the quick correction system meshed with the toothing of the date disc;  
       FIG. 15  is a plan view showing the corrector pinion of  FIG. 14  meshed with the toothing of the month star wheel;  
       FIG. 16  is a plan view of the quick correction system in the watch time-setting position, and  
       FIG. 17  is a perspective view of the month indicator disc. 
    
    
      The present invention proceeds from the general inventive idea that consists in providing an annual calendar mechanism in which the kinematic chain between the date disc and the month star wheel is constantly interrupted except during the period of time necessary for the mechanism to pass from the last day of a month to the first day of the following month, which allows the date indication and the month indication to be corrected more quickly and in an independent manner for example at the end of the month of February or after the watch has been stopped for an extended period. Moreover, the annual calendar mechanism according to the invention includes an instantaneous release system which allows the date and month indication to pass from the end of one month to the beginning of the next month abruptly without dragging such that, for the user, the passage from one month to the next month occurs almost imperceptibly and the watch always provides correct indications.  
       FIG. 1  is a plan view of a watch fitted with an annual calendar mechanism according to the invention. Designated as a whole by the general reference numeral  1 , this watch is fitted in particular with an hour hand  2 , a minute hand  4  and second hand  6 . It also includes a date indicator in the form of a date  8  appearing through an aperture  10  pierced in a dial  12 . Time setting can be performed via a crown  14 .  
      If the dial is now removed from this watch and one keeps only those elements useful for the implementation of the invention, one is left with the plan views of FIGS.  2  to  5 , which show the annual calendar mechanism according to the invention at three different instants during the passage from a month of less than thirty one days to the following month, in the example illustrated from the 30 th  April to the 1 st  May.  
      An examination of  FIG. 2  and of the perspective view of  FIG. 6  will explain the operation of the annual calendar mechanism according to the invention. This mechanism comprises a date disc  16  formed of a bottom annular disc  18  carrying a first inner toothing  20  and a top annular disc  22  carrying a second inner toothing  24 . The first toothing  20  comprises thirty-one teeth  20   a  whereas the second toothing  24  comprises a single tooth  24   a . The top face of annular disc  22  carries thirty-one numbers each corresponding to an indication of a day of the month. These numbers appear in succession through aperture  10  shown in  FIG. 1 . Annular disc  22  also carries on its bottom face a control member  26  of the post type which can be affixed to said annular disc  22  by any appropriate means or which can be integral with said disc  22 . The role of this post  26  will be explained in detail hereinafter. Teeth  20   a  and tooth  24   a  consequently extend in two different planes, teeth  20   a  extending below tooth  24   a . As can be seen upon examining  FIG. 6 , the two bottom  18  and top  20  annular discs extend parallel to and at a distance from each other.  
      In FIGS.  2  to  5 , it can also be seen that a jumper  28  returned by a spring  30  is applied against toothing  20  of disc  18  in order to position date disc  16  angularly when the latter is not being actuated, allowing perfect indexing of the date disc  16  opposite aperture  10 .  
      A date drive wheel set, generally designated by the reference numeral  32  is fitted with a finger  34  capable of driving date disc  16  through one step once a day via its inner toothing  20 . In the particular case of  FIG. 2  in which the date mechanism according to the invention is shown in a state immediately preceding the jump from the “30 th ” to the “31 st ”, it can be seen that finger  34  is not yet meshed with inner toothing  20  of bottom annular disc  18 . As can be seen upon examining FIGS.  2  to  5  and also in  FIGS. 7 and 8 , the date drive wheel set  32  includes a wheel  36  which carries finger  34  and which is driven in rotation by a first drive wheel  38  completing one revolution per day. This drive wheel  38  is itself driven by the hour wheel  39  of a conventional watch movement, which may be mechanical or electromechanical, via a wheel set  41  whose wheel  43  is driven by hour wheel  39  and whose pinion  45  meshes with drive wheel  38 . The date drive wheel set  32  thereby formed pivots on a post  37  secured in movement at A. It could also pivot in a bearing (jewel).  
      With the exception of the structure of the date disc  16 , the foregoing description is well known in the state of the art. It is in fact a conventional date disc drive able to be reset to the date by means of a quick correction device meshed with toothing  20  using a crown when the latter is in a determined position. According to this conventional system, it is necessary to reset the date at the end of months having less than thirty-one days, namely the months of February, April, June, September and November.  
      We will now describe what has been added to this mechanism to transform it into an annual calendar mechanism in which, apart from for the end of the month of February, the date jumps automatically from the “30 th ” to the “1 st ” of the following month at the end of the months of less than thirty-one days.  
      As was already mentioned above, the date disc  16  according to the invention differs from a conventional date disc in that it comprises the additional tooth  24   a  provided on the top annular disc  22 . It is to be driven once per month, typically at the end of the months of less than thirty-one days, by a correction drive wheel set  42 . This wheel set  42  is comprised of a finger  44  secured to a second drive wheel  46 , which is carried by a sliding pinion  48  pivoting at B. The second drive wheel  46  is driven by the first drive wheel  38  via an intermediate wheel  50 , which meshes with wheel  36 .  
      A sliding lever  40  also carries a month drive wheel set  52  for driving a month star wheel  54  at the end of each month. For this purpose, the month drive wheel set  52  comprises a third drive wheel  56 , which carries a finger  58  and which is driven by the first drive wheel  38  via wheel  36 . As described in detail hereinafter, a coupling lever  59  pivoting at F controls the pivoting of sliding lever  40 . This lever  59  is returned by a spring  61  and cooperates with sliding lever  40  via a manoeuvring arm  63  whose head  65  slides into a shaped aperture  67  arranged in said lever  40 .  
      As is particularly clear in  FIG. 9 , the month star wheel  54  comprises a wheel with twelve teeth  60 , which is positioned by a jumper  62  returned by a spring  62  in order to position said month star wheel  54  angularly when it is not being actuated. This month star wheel  54  also includes a bottom cam  66  and a top cam  68 . The top cam  68  includes five protruding portions  68   a - 68   e  distributed at its periphery, these five protruding portions  68   a - 68   e  respectively corresponding to the five months of the year that have less than thirty one days. Bottom cam  66  avoids the use of a return spring for a lever  70 , which, via its beak  74 , follows the profile of the bottom cam  66  whereas it follows the profile of top cam  68  via its nose  72 . This lever  70  pivots at C and is mounted to pivot freely on sliding lever  48 .  
      As the various constituent elements of the invention have been defined above, there remains the explanation of the operation of the annual calendar mechanism. Two cases can arise depending upon whether it is a month of less than thirty-one days or a month of thirty-one days. Passage from the “30 th ” to the first day of the next month in the case of a month of less than thirty-one days is illustrated in FIGS.  2  to  5 .  
      In  FIG. 2 , the annual calendar mechanism according to the invention is shown in the position that it occupies immediately before passage from the “30 th ” to the “31 st ”. In this position, fingers  34  and  44  are released from the first and second bottom toothings  20  and  24  of the bottom and top annular discs  18  and  22 . Likewise, finger  58  is released from the toothing of the wheel with twelve teeth  60  of month star wheel  54 . Quick correction of the date disc  16  or month star wheel  54  is thus possible at any time because of the use of an instantaneous release system  76  and not a dragging correction system whose peculiarity lies in the fact that the correction fingers gradually penetrate the toothings of the date ring and the month star wheel.  
      Instantaneous release system  76  is shown in  FIGS. 7 and 8 . It comprises in particular the first drive wheel  38  and wheel  36  carrying finger  34 . It also comprises a release lever  78  returned by a spring  80  and which abuts via its beak  82  against a cam  84 . Wheel  36  is secured to cam  84  via a pin  86  or by rivets. This pin  86  is free to move in a shaped aperture  88  made in drive wheel  38 .  
      The instantaneous release system  76  operates as follows. By rotating, drive wheel  38  drives, via pin  86 , wheel  36  and cam  84 . The release lever  78  follows the profile of cam  84  via its beak  82  until a point where, constrained by spring  80 , it starts to slide abruptly along said cam  84 , driving the latter and wheel  36  in rotation at an angle determined by the shape of cam  84 . Then, cam  84  and wheel  36  remain still until drive wheel  38  starts to drive them again via pin  86  which is at the bottom of shaped aperture  88 .  
      After instantaneous release system  76  has been released, the date mechanism passes in succession through the positions illustrated in  FIGS. 3, 4  and  5 . It will be understood that the sequence of movement of the various members forming the date mechanism according to the invention has been broken down in order to facilitate comprehension, but that, in reality, the mechanism passes from the position illustrated in  FIG. 2  to that illustrated in  FIG. 5  in a fraction of a second.  
      In  FIG. 3 , finger  44 , carried by the second drive wheel  46 , which is itself driven by cam  84  and wheel  36  via intermediate wheel  50 , has pushed tooth  24   a  through one step and has driven date disc  16  to make the display pass from the “30 th ” to the “31 st ”. Wheel  36 , driven by instantaneous drive system  76  to which the first drive wheel  38  belongs, continues to rotate, such that finger  34 , carried by said wheel  36 , is behind a tooth  20   a  of bottom annular disc  18  and the second operating phase of the mechanism illustrated in  FIG. 4  can begin.  
      In fact, in  FIG. 4 , finger  34  pushes forward the tooth of teeth  20   a  which it was behind, thereby driving top annular disc  22 . Via its post  26 , the latter then pushes coupling lever  59 , which starts to pivot about its pivoting centre F. In turn, via its manoeuvring arm  63 , coupling lever  59  pushes sliding lever  40  which carries the third drive wheel  56  and its associated finger  58 . Via the effect of this thrust, sliding lever  40  pivots about its pivoting centre A and finger  58  penetrates the toothing of the wheel  60  with twelve teeth of month star wheel  54 . Finger  44  continues to rotate but without any effect on tooth  24   a  which moves away. As can be seen upon examining  FIG. 4 , jumper  28  is passing from one hollow between two successive teeth  20   a  to the hollow between the next two teeth  20   a  and momentarily passes over one of these teeth  20   a . At this operating stage of the mechanism, the display is in an intermediate position between the “31 st ” and the “1 st ” of the following month.  
      We will now examine the change of month step with reference to  FIG. 5 . In this position, finger  34  has finished pushing one step forward the tooth  20   a , which it was behind, and has driven date disc  16  through an additional step to make the display pass from the “31 st ” to the “1 st ” of the following month. It is thus the first day of month following a month with less than thirty-one days. It is thus a month of thirty-one days at the end of which there is no need to correct the display of the date disc  16 . finger  44  is thus released from the second inner toothing  24  as will now be described in detail. Driven by wheel  56  which has itself been driven by wheel  36 , finger  58  has moved month star wheel  54  one step forward, namely one twelfth of a revolution. During this last phase, the pivoting of month star wheel  54  is accompanied by the pivoting of bottom cam  66  and top cam  68 . Beak  74  of lever  70  has followed the profile of bottom cam  66 , whereas nose  72  is between two protruding portions of top cam  68 . Lever  70 , pivoting about its pivoting centre C, simultaneously drives sliding lever  48  while pivoting about its pivoting centre B, which causes the removal of finger  44  from the radius of toothing  24 , such that at the end of the month of thirty one days, this finger  44  is released from said toothing  24  and cannot move date disc  16  through an additional step.  
      In  FIG. 5 , it is thus the first day of a month of thirty-one days following a month of less than thirty-one days. Finger  44  is in its final position in which it is released fro the second inner toothing  24  of the top annular disc  22 . It remains in this position for the whole of the month. At the end of the month of thirty one days, finger  34  passes date disc  16  from the “30 th ” to the “31 st ”, then from the “31 st ” to the “1 st ” of the following month like a conventional calendar. Each time, finger  44  is actuated by instantaneous release system  76 , but this has no effect on the date indication since finger  44  is released from the second inner toothing  24  of the top annular disc  22 . During this second day, post  26  pushes sliding lever  40  via coupling lever  59 . Via the effect of this thrust, lever  40  pivots about A and finger  58 , penetrating the toothing of the twelve-toothed wheel  60  of month star wheel  54 , moves said month star wheel  54  one step forward, namely one twelfth of a revolution. If one is passing from a month of thirty-one days to another months of thirty-one days (July/August and December/January), cams  66  and  68  will hold levers  70  and  48  in their position. If, on the other hand, one is passing to a month of less than thirty one days, nose  72  of lever  70  will climb onto protruding portion  68   b  and cause lever  48  to pivot such that finger  44  is in the radius of toothing  24  of disc  22 , ready to move tooth  24   a  forward one step at the end of the month of less than thirty one days. This position is maintained during the entire month. On the “30 th ” of the month, tooth  24   a  will be in the position illustrated in  FIG. 3  and the cycle described will start again. It will be noted that during passage from the “1 st ” to the “2 nd ”, post  26  completely overtakes coupling lever  59 . The latter is then returned to its rest position via the effect of the thrust of spring  61  and is on the path of said post  26 , ready to be actuated again by the latter when the current last day of the month passes to the first day of the next month.  
      It is clear from the foregoing that, during the months of less than thirty-one days, finger  44  is permanently on the path of tooth  24   a  of top annular disc  22 . However, finger  44  only acts once per month since top annular disc  22  only has this single tooth  24   a . however, during the months of thirty-one days, finger  44  is moved away from toothing  24 , such that it has no effect on top annular disc  22 . Further, the two cams  66  and  68  of month star wheel  54  materialise the succession of months of less than thirty-one days and months of thirty-one days. During a month of thirty-one days, beak  74  of lever  70  abuts on the tip of a protruding portion of bottom cam  66 . Lever  70  pivots and brings finger  44  into an inactive position via sliding lever  48 . During a month of less than thirty-one days, nose  72  of lever  70  abuts on the profile of top cam  68  and brings finger  44  into the active position. A perspective view of lever  70  is shown in  FIG. 10 .  
      The annual calendar mechanism according to the invention also comprises a quick correction device illustrated in  FIG. 11  and the following Figures. Designated as a whole by the general reference numeral  90 , this quick correction device includes a corrector pinion  92  with three fingers friction driven by an intermediate wheel  94 , which is itself driven by winding stem  96  via a sliding pinion  98  and a second intermediate wheel  100 . A sliding lever  102  pivoting at D at the centre of the second intermediate wheel  100  carries the corrector pinion  92 .  
      Quick correction device  90  is usually held in the neutral position in order not to disturb the proper operation of the annual calendar mechanism according to the invention. The control lever  104  of the time-setting mechanism of the movement can occupy three distinct positions as a function of the respective positions of winding stem  96  and a pull-out piece  106 . In  FIGS. 12 and 13 , the control lever  104  is shown in the neutral position, with winding stem  96  pushed in. It carries the time-setting train  108 , one pin  110  of which penetrates, on the dial side of the watch (not shown), a shaped slot  112  arranged in a lever  114 . Lever  114  pivoting at E carries a post  116  which holds sliding lever  102  in place by lodging in a V-shaped cut out portion  118  of sliding lever  102 .  
      When winding stem  96  is pulled out into the intermediate position, control lever  104  pivots and its pin  110  moves lever  114  and its post away from sliding lever  102 . Sliding pinion  98  then drives intermediate wheels  94  and  100  and corrector pinion  92 . Depending upon the direction of rotation of winding stem  96 , sliding lever  102  pivots at D and corrector pinion  92  drives either date disc  16  by its first inner toothing  20 , or month star wheel  54  by its twelve-toothed wheel  60 . When winding stem  96  is in the time-setting position, control lever  104  pivots in the opposite direction and its pin  100  again holds lever  114  and its post  116  which lodges in V-shaped cut out portion  118 .  
      The annual calendar mechanism according to the invention includes finally a month indicator shown in  FIG. 17 . Designated as a whole by the general reference numeral  120 , this month indicator includes a disc  122  bearing the indication of the twelve months of the year. This indicator disc  122  is riveted onto a hub  124  provided with two holes  126  via which hub  124  is engaged on two corresponding posts  128  carried by month star wheel  54 . The month indicator  120  thereby formed is held up by a key carried by a tube of the holding plate (not shown).  
      It goes without saying that the present invention is not limited to the embodiment that has just been described and that various simple alterations and variant can be envisaged by those skilled in the art without departing from the scope of the invention as defined by the annexed claims.