Patent Publication Number: US-8982673-B2

Title: Calendar mechanism including a quick month corrector

Description:
This application claims priority from European Patent Application No. 11159240.8 filed Mar. 22, 2011, the entire disclosure of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention concerns a calendar mechanism for a timepiece and more specifically a mechanism of this type including a date display, a month display and a quick month corrector. 
     PRIOR ART 
     Calendar mechanisms for timepieces are common. CH Patent No 697,662, in particular, discloses a calendar mechanism for a timepiece. This mechanism is more specifically a perpetual date mechanism. It comprises in particular a date display and a month display. The mechanism disclosed in this prior art document also comprises a date corrector and a month corrector for manually correcting the indication of the date and the month respectively. These correctors are arranged to be actuated by two respective push-buttons for incrementing by one step the date indication and the month indication respectively. According to the aforementioned prior art document, one of the advantages of the mechanism disclosed is that it can move the month indication forward using the corrector provided for this purpose, without affecting the date indication. In most cases, this arrangement makes setting the date of the calendar more intuitive. However, this is not always the case. For example, if the month corrector is actuated while the calendar indicates 30th January, the calendar changes to the 30th February. 
     Moreover, as explained in EP Patent No 0 509 959, when the same timepiece combines an equation of time mechanism and a calendar mechanism, it is advantageous to drive the equation of time cam from the 31 wheel set. Indeed, owing to this arrangement, it is theoretically possible to automatically return the equation of time cam to its exact position after an indefinite period where the movement is stopped, simply by resetting the calendar to the date. However, it will be clear that calendar mechanisms which include a corrector for modifying the month indication without affecting the angular position of the 31 wheel set do not have this advantage. Indeed, in this case, the month correction does not affect the angular position of the equation of time cam either. 
     EP Patent No. 1 004 947 discloses a quick date correction mechanism comprising an operating member which is accessible from the exterior of the watch and arranged for driving the date star wheel in rotation via a gear train. In certain embodiments, the multiplication ratio of the gear train is sufficient for one movement of the operating member to drive the date star wheel by a value of more than one month. However, under these conditions, the high multiplication ratio makes the correction device more imprecise. It thus becomes very difficult for the user to release the operating member in proximity to the desired date without risking going past said date. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the present invention to overcome the aforementioned drawbacks. This object is achieved by providing a calendar mechanism in accordance with the annexed claim  1 . 
     According to the present invention, the stop mechanism can either occupy an inactive position, in which it does not intercept the trajectory of the rotating stop member, or an active position in which it locks the 31 wheel set in an angular position corresponding to the indication of the first day of the month. Owing to this feature, the quick corrector device according to the invention does not interfere with the normal operation of the date drive means. It will also be clear that, when the 31 wheel set moves forward to the first day of the next month in one stroke, it actuates, in passing, the monthly drive means, which causes the 12 wheel set and the month indicator to move forward one step. In other words, according to the present invention, quick correction of the month indication is accompanied by a quick advance of the date to the next month. The connection between the date and the month is thus preserved during correction. This feature is particularly advantageous where the calendar mechanism is provided for cooperating with an equation of time mechanism, the 31 wheel set then being arranged to drive the equation of time cam. Indeed, in this case, the month corrector device according to the invention simultaneously corrects the angular position of the equation of time cam. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the invention will appear upon reading the following description, given solely by way of non-limiting example, with reference to the annexed drawings, in which: 
         FIG. 1  is a partial top view (from the bridge side) of a first embodiment of the calendar mechanism of the invention, more specifically showing the quick corrector. 
         FIG. 2  is a partial perspective view of the calendar mechanism and particularly the quick corrector of  FIG. 1 . 
         FIG. 3  is a partial bottom view (from the dial side) of the calendar mechanism of  FIGS. 1 and 2 , more specifically showing the monthly drive means. 
         FIG. 4  is a partial bottom view of the calendar mechanism of  FIGS. 1 ,  2  and  3 , more specifically showing the date corrector. 
         FIG. 5  is a side view of part of a quick corrector device forming part of a second embodiment of the calendar mechanism of the invention; 
         FIG. 6  is a top view of the part of a quick corrector shown in  FIG. 5 . 
         FIG. 7  is a perspective view of the part of a quick corrector shown in  FIGS. 5 and 6 . 
     
    
    
     DETAILED DESCRIPTION OF TWO EMBODIMENTS 
     The watch and the timepiece movement that it contains will not be described hereinafter in their entirety, but only the calendar mechanism. As regards the timepiece movement, it is sufficient to specify that it is arranged to drive, via date drive means forming part of the calendar mechanism, a 31 wheel set at a rate of one revolution per month. The 31 wheel set in turn actuates a date indicator hand. 
     Referring first of all to  FIG. 1 , it is seen that the quick month corrector includes a rack  3  with a toothed sector  5  at one end thereof and a first control pin  7  at the other end. The rack is pivotally mounted about an axis  9  arranged close to the end carrying pin  7 . The toothed sector meshes with the pinion of a first wheel set  11 , and the wheel of said first wheel set meshes with a single direction gear train  13 . As can be seen in the perspective view of  FIG. 2 , the single direction gear train includes an input wheel  15  and an output wheel  17 , which are coaxial and can pivot in relation to each other. The output wheel  17  carries a coaxial ratchet (not shown) which is sandwiched between the input wheel and the output wheel. A click  19  is pivoted on the plate of the input wheel  15 . This click is returned against the periphery of the ratchet by a spring  21 . Those skilled in the art will understand that the click is arranged to cooperate with a ratchet tooth when the input wheel rotates in the clockwise direction and to slide against the ratchet when the input wheel rotates in the anti-clockwise direction. Referring again to  FIG. 1 , it can be seen that the output wheel of the single direction gear train  13  meshes with a pinion  23  which forms part of the thirty-one wheel set (which is generally referenced  31 ). 
     The operation of the elements of the month corrector which have just been listed will now be described. The quick month corrector of the present example is to be actuated manually via a multi-function coaxial corrector device (not shown) which may advantageously be of the same type as that disclosed in EP Patent No 1 939 699 in the name of the Applicant. EP Patent No. 1 939 699 is incorporated herein by reference. It will be clear however that numerous other manual control devices known to those skilled in the art may also be suitable for actuating the quick month corrector of the present invention. In any event, this description does not provide details concerning the manual control device. Indeed, the features thereof do not have any direct bearing on the implementation of the invention. 
     When the person wearing the watch manually actuates the coaxial multi-function corrector button (not shown), the internal bearing surface of the control mechanism pushes the first control pin  7  in the direction of the arrow (a) ( FIG. 1 ), which causes rack  3  to pivot about axis  9 . The length of travel of the inner bearing surface of the control mechanism is considerably shorter than the length of toothed sector  5 . However, since the pivot axis  9  is close to control pin  7 , the lever effect allows the whole of the sector  5  toothing to cooperate with the pinion of wheel set  11 . Wheel set  11  is thus driven anti-clockwise. Control pin  7  is returned by a spring (not shown) in the opposite direction to the arrow (a) of  FIG. 1 . Thus, when the person wearing the watch releases the pressure on the control mechanism button, and the inner bearing surface thereof returns to the rest position, rack  3  returns to its initial position, this time driving wheel set  11  clockwise. 
     When wheel set  11  is rotating anti-clockwise, it drives input wheel  15  of the single direction gear train  13  clockwise. Under these conditions, output wheel  17  rotates integrally with the input wheel and also rotates clockwise. When wheel set  11  moves backwards again clockwise, it drives the input wheel anti-clockwise. Under these conditions, the single direction gear train is uncoupled and the output wheel is not driven. Finally, as already stated, the output wheel meshes with the pinion  23  of the 31 wheel set. It is thus clear that the effect of the user actuating the multi-function coaxial corrector button is to drive the 31 wheel set anti-clockwise. The gear ratios are selected as a function of the length of travel of the control mechanism, so that a single application of pressure on the button is sufficient to advance the 31 wheel set through one complete revolution. 
       FIG. 1  also shows that pinion  23  of the 31 wheel set also meshes with a pierced wheel  25  which has five radial arms carrying a toothed felloe. It will be noted that, in this example, the toothing of the felloe of wheel  25  has the same number of teeth as pinion  23 . Moreover,  FIG. 1  also shows a lever  29  which is pivotally mounted about an axis  33  and which carries, at one end, a bifid hook  35 , and at the other end, a beak  37 . The shape of lever  29  is adapted to allow it to cooperate with a bolt  39  which is pivotally mounted on an axis  41 . Lever  29  and bolt  39  are respectively returned in the direction of arrows (b) and (c) by two springs (not shown). As will be seen hereinafter, lever  29  and bolt  39  are both moveable between an inactive position and an active position.  FIG. 1  further shows that the hub of wheel  25  carries a pin (or a stud)  27  in an off-centre position. Pin  27  is arranged to cooperate with hook  35  only when the hook is in an active position. 
     The function of the elements of the quick month corrector which have just been described is to stop the quick advance of the date wheel set as soon as the latter reaches the angular position corresponding to the indication of the first day of the month. The operation is as follows. While the quick month corrector is not being activated, rack  3  is in its rest position shown in  FIG. 1 . As can be seen, beak  37  of lever  29  is then in abutment against the rack. The rack resists the pivoting of the lever in the direction of the arrow (b) and keeps it in the inactive position. In this position, hook  35  is outside the circular trajectory of the pin  27 . The hook therefore does not interfere with the rotation of the 31 wheel set. It will also be noted that bolt  39  is also in abutment against the rack. The rack thus also holds the bolt in the inactive position. When the quick month corrector is activated, the rack pivots, releasing lever  29  and bolt  39  which are then free to pivot respectively in the direction of the arrows (b) and (c) to change into the active position. 
     When lever  29  is in the active position, hook  35  acts as a stop arranged to intercept the trajectory of pin  27 . When the stop mechanism is in the active position and the pin is driven in rotation by the quick month corrector, the latter abuts against the hook  35  which stops the travel thereof. Pin  27  thus plays the part of a rotating stop member which is arranged to cooperate with stop mechanism  25 . It will also be clear that, owing to the is presence of bolt  39 , it is impossible for the rotating stop member  27  to push stop mechanism  29  back into the inactive position. The collision of the rotating stop member with the stop mechanism thus has the effect of stopping the progress of the 31 wheel set. Lever  29  is also positioned relative to the pin so as to immobilise the 31 wheel set in the angular position corresponding to the indication of the first day of the month. Once the 31 wheel set has moved to the angular position corresponding to the indication of the first day of the month, rack  3  returns to its initial position pushing back lever  29  and bolt  39  which return to the inactive position. Those skilled in the art will understand from the preceding description that according to a variant of this embodiment, it would be possible to omit wheel  25 . Pin  27  could in fact be mounted directly on the 31 wheel set. It is considerations of space which make it preferable to use an additional wheel (wheel  25 ). 
     In a known manner, the calendar mechanism of the invention includes a monthly drive means activated by the 31 wheel set for incrementing the month indication by one step at the end of every month. Referring now to  FIG. 3 , it can be seen that the monthly drive means includes an eccentric  43  which is secured to and concentric with the 31 wheel set, an instantaneous lever  45  pivotally mounted about an axis  46 , a beak  47  integral with the instantaneous lever, an instantaneous lever spring  49  arranged to return the beak of the lever against the periphery of the eccentric, and an instantaneous click  51  pivoted on an axis  53  arranged in a bend in the lever, the click  51  being returned against the asymmetrical saw teeth of a ratchet toothing carried by the twelve wheel set by a spring  55  (the twelve wheel set is generally referenced  12 ). Finally, the monthly drive means also includes a jumper spring  59  arranged to cooperate with the ratchet toothing of the 12 wheel set. 
     The operation of the monthly drive means will now be explained. In this example, the shape of eccentric  43  is such that the start and the peak of the curve of the eccentric are superposed. Moreover, the eccentric is arranged such that the angular position of the 31 wheel set at the moment when beak  47  of the instantaneous lever  45  can fall without transition from the peak to the start of the curve of the eccentric approximately corresponds to the transition between the 31st day of a month and the first day of the next month. On the first day of a month, the beak is at the start of the curve. Next, the beak climbs the curve day after day, gradually lifting the instantaneous lever. The pivoting of the instantaneous lever has the effect of sliding click  51  against the ratchet toothing of the 12 wheel set. At the end of the month, beak  47  reaches the peak of the curve and, pushed by spring  49 , suddenly drops to return to the start of the curve. In falling, the beak abruptly pushes the instantaneous lever and click  51  backwards. During its backward movement, click  51  hooks one of the saw teeth of the ratchet toothing and thus advances the 12 wheel set by one step, which has the effect of incrementing the date indication by one month. It will be noted that the monthly drive means that has just been described is arranged to increment the 12 wheel set each time that the 31 wheel set passes from the last day of one month to the first day of the next month. The monthly drive means is activated both when the 31 wheel set passes from one month to another driven by the movement, and when it is driven by the quick month corrector. Moreover, the drive means that has just been described is of the “instantaneous” type. Those skilled in the art will understand however that the monthly drive means of the calendar mechanism according to the invention could also be of the “continuous” or of the “semi-instantaneous” type. 
     The date corrector device of the calendar mechanism of this example will now be described with reference to  FIG. 4 . The date corrector device can be actuated manually and is for driving the 31 wheel set in one day increments. The date corrector includes a date corrector lever  61  pivoted on an axis  65 , a date control pin  63  mounted on one end of lever  61 , a beak  67  returned against the ratchet toothing of the 31 wheel set by a spring  71  and finally a jumper spring  69  arranged to cooperate with the ratchet toothing of the 31 wheel set. 
     The operation of the elements of the date corrector device which have just been listed will now be explained. The date corrector of this example is to be actuated manually by the same multi-function coaxial corrector device (not shown) that actuates the quick month corrector. It will be clear however that numerous other manual control devices known to those skilled in the art may also be suitable for actuating the date corrector of the present invention. In particular, according to a variant of the present example, the date corrector and the quick month corrector could be actuated respectively by two distinct manual control devices. 
     When the person wearing the watch selects the “date corrector” function of the multi-function coaxial corrector (not shown) and manually activates the corrector button, the inner bearing surface of the control mechanism pushes the date control pin  63  in the direction of the arrow (a) ( FIG. 4 ), which causes the lever  61  to pivot about axis  65 . When lever  61  pivots in this manner, beak  67 , which is fixed at one end thereof, moves along a substantially tangential trajectory to the ratchet toothing of the 31 wheel set. During its movement, beak  67  hooks one of the saw teeth of the ratchet toothing and thus advances the 31 wheel set one step lifting jumper spring  69 . The forward step by the 31 wheel set has the effect of incrementing the date indication by one day. It will be noted that rack  3  of the quick month corrector remains in the rest position during the use of the date corrector. Thus, lever  29  remains in the inactive position and the date corrector is still operating, even when the 31 wheel set has reached the angular position corresponding to the indication of the first day of the next month. 
       FIGS. 5 ,  6  and  7  are respectively side, top and perspective views of one part of a quick corrector device according to a second embodiment of the invention. These three views show in particular a wheel  125  the cylindrical arbour  126  of which carries a lug  127  and a projecting portion  145 . The Figures also show a fork  135  pivotally mounted about an axis  133  and one prong  147  of which plays the part of the cam follower lever, and the other prong  143  plays the part of stop lever. The function of the elements of the quick corrector which have just been listed is to stop the quick advance of the date wheel set as soon as said wheel set reaches the angular position corresponding to the indication of the first day of the month. 
     The other components of the quick corrector can be the same as in the first embodiment of the invention can be the same as those that have been described in relation to the first embodiment of the invention. 
     The operation is as follows. Wheel  125  is kinematically linked to the 31 wheel set (not shown in  FIGS. 5 ,  6  and  7 ) so that that the two elements rotate at the same speed. In this example, wheel  125  is arranged to rotate clockwise (as indicated by arrow d) when the 31 wheel set is incremented. It can also be seen that, in this particular example, the lug  127  and the projecting portion  145  are shifted by around 180°. Moreover, a careful examination of the Figures also reveals that the lug and the projecting portion are not only angularly shifted about arbour  126 , but they are also shifted in height. Indeed, lug  127  is placed quite low down, in immediate proximity to wheel  125 , whereas the projecting portion  145  is placed higher up, close to the top end of the cylindrical arbour. 
     As shown in  FIG. 7 , the distal ends of the two prongs of fork  135  are also shifted in height. The height of the end of prong  147  corresponds to that of projecting portion  145  and the height of the end of prong  143  corresponds to that of lug  127 . The end of prong  147  plays the part of a feeler spindle  149  and it is arranged to be raised by the projecting portion  145  upon each new revolution of wheel  125 . As it is raised, prong  147  causes fork  135  to pivot about the axis  133  thereof. This pivoting has the effect of bringing the other prong  143  of the fork into an active position. In this position, the end  151  of prong  143  intercepts the trajectory of lug  127  so that these two elements can cooperate, the lug playing the part of rotating stop member and the end of prong  143  playing that of a stop member  151 . 
     According to the invention, the angular position of the 31 wheel set at the moment when lug  127  encounters the end of stop lever  143  corresponds to the indication of the first day of the month. Moreover, in the example illustrated, the position at the moment when projecting portion  145  pivots fork  135  corresponds to the indication of the 27th day of the month. The Figures show the 31 wheel set one day later, in the angular position corresponding to the indication of the 28th day of the month. It can be seen that in rotating the projecting portion  145  has now gone past the feeler spindle  149 . Lug  127  has not yet reached the level of stop  151 . Moreover, a small spring (not shown) is arranged to return fork  135  in the direction of the arrow (d,  FIG. 6 ). The function of the small spring is to hold the feeler spindle  149  against the surface of the cylindrical arbour  126 . It can be seen in  FIGS. 6 and 7  that after the passage of the projecting portion, the cam follower lever  147  and its feeler spindle are again lowered by the effect of the small spring. This movement is accompanied by a pivoting of fortes  135  about the axis  133  thereof, so that the stop lever  143  returns to the inactive position, out of the circular trajectory of lug  127 . 
     The process that has just been described is what happens when the 31 wheel set advances step-by-step, driven by the calendar mechanism. When the 31 wheel set advances in one stroke by the action of the quick corrector device, things happen a little differently. Indeed, the rapidity of the advance of the 31 wheel set is such that the passage of projecting portion  145  causes the cam follower lever  147  to jump. Lever  147  then does not have time to fall again before lug  127  abuts against stop lever  151 . It will thus be clear that the small spring arranged to return the cam follower lever against the cylindrical arbour  126  must not be too strong. One advantage of this second embodiment of the invention is that it omits the bolt (referenced  39  in  FIG. 1 ). 
     It will also be clear that various alterations and/or improvements evident to those skilled in the art may be made to the embodiment described herein without departing from the scope of the present invention defined by the annexed claims. In particular, in the first embodiment, the hook  35  forming the end of the pivoting lever  26  could be replaced by a slide that can move axially between the active position and the inactive position.