Patent Publication Number: US-7724611-B2

Title: Day of the month display mechanism for watch movement

Description:
REFERENCE DATA 
   This application is a continuation of International Patent Application 2004WO-EP05037 (WO04088435) filed on Mar. 26, 2004, claiming priority of Swiss patent application 2003CH-0571 of Apr. 2, 2003, the contents whereof are hereby incorporated. 
   FIELD OF THE INVENTION 
   The present invention concerns a day of the month display mechanism for watch movement, in particular a large-size day of the month display mechanism. 
   DESCRIPTION OF RELATED ART 
   Watch movements with hands for displaying the day of the month more often than not use an annular date disc with 31 positions, the days of the month from 1 to 31 being printed on these positions. The date disc is indexed each day by one position, so as to show each day another date through an aperture in the dial. Each indexation position thus occupies an angular portion of 360°/31, on which a date with one or two digits must be indicated; the maximal size of the displayed numbers is thus limited. 
   Different systems are known that allow dates of a larger size to be displayed. The known systems often use two distinct mobiles, one for the date&#39;s tens and one for the date&#39;s units; a mechanical or electromechanical control system makes it possible to display each day the correct ten and unit combination through the aperture or apertures. 
   International application WO9913383 (Jaquet SA) describes a mechanism for displaying a large size calendar date in which the units are displayed by an annular disc and the tens by a cross of which one of the branches covers a portion of the units&#39; annular disc. The units disc bears three times the sequence of digits 0 to 9 plus an intermediary  1 , corresponding to the sequence of the units for the numbers from 0 to 31. The cross&#39;s branches bear the numbers 0 to 3 respectively. An aperture on the dial is provided to display both the portion of the cross covering the annular disc and the next units number on the right of the cross. 
   This disposition has the disadvantage of requiring considerable modifications of the mechanism if one wishes to display the date at another place, for example at three o&#39;clock or at six o&#39;clock rather than at 12 o&#39;clock. In this case, the axis of the tens&#39; cross must be moved and the entire driving system must be adapted accordingly. 
   Furthermore, the units&#39; cross occupies a considerably space at the watch&#39;s center; this space is thus not available for other displays, for example for the axis of hands for auxiliary functions such as chronometer, power reserve, day of the week display etc. In any case, the size of the tens&#39; cross, and thus the maximal size of the displayed date digits, is limited by the distance between the units&#39; disc and the seconds&#39; axis. 
   In this solution, the tens&#39; and units&#39; digits are in any case displayed by mobiles moving in two different planes; there is thus, for all the dates, a difference in depth between the tens&#39; digit and the units&#39; digit, which is visible through the date aperture. 
   Furthermore, in this solution, the tens&#39; star wheel is driven by the units&#39; annular disc through a star wheel engaging with the internal units&#39; disc and held by a jumper. When the date changes, in particular during a manual correction of the date, the star wheel sometimes risks being driven with an energy sufficient for the jumper to pass directly from one tooth, or branch, to a non-neighboring tooth of the star. In this case, the correspondence between the tens and the units is irrevocably destroyed; the watch could for example display the dates  32 ,  33  etc. To limit this risk, though without suppressing it completely, it would thus be necessary to use a jumper holding the star that is actuated by a sufficiently strong spring; this solution however has the disadvantage of considerably increasing the power and the energy required for changing the date. Motors must thus be oversized only to act on the jumper and the electric consumption is increased accordingly. 
   One aim of the present invention is to propose a day of the month display mechanism that avoids these disadvantages. 
   BRIEF SUMMARY OF THE INVENTION 
   According to the invention, these problems are solved by means of a watch having the characteristics of the independent claims, preferred characteristics being further indicated in the dependent claims. 
   In particular, these problems are solved thanks to a day of the month display mechanism for watch movement, comprising a first mobile bearing a first sequence of digits and a second mobile bearing a second sequence of digits. The two mobiles are arranged and disposed in such a manner that, at least for certain dates, the day of the month displayed to the user corresponds to the combination of indications borne by the first mobile and of indications borne by the second mobile, whilst for at least another date, the displayed day of the month corresponds to the combination of two digits or of a digit and of a space borne by the same mobile. 
   The inventive display mechanism is thus a combination between a large date display mechanism, with two digits borne by two distinct mobiles, and a conventional day of the month display mechanism for other dates, for which the date&#39;s single digit or two digits are borne by the same mobile. One can thus avoid, at least for certain dates, the disadvantages of a display through two distinct mobiles without having to forgo the displaying of large size dates. 
   This solution further allows the number of indications borne by the two mobiles to be balanced by reporting certain units&#39; indications on the tens&#39; disc and/or certain tens&#39; indications on the units&#39; disc, so as to be able to display dates of the largest possible size. 
   The two mobiles are preferably constituted by two concentric and preferably superimposed annular discs. One thus avoids occupying portions of the upper surface of the movement that could be used by other displays. Furthermore, the date can be displayed at any angular position on the dial merely by replacing the annular discs, without modifying nor moving the driving mechanism. 
   These aims are also achieved by means of a day of the month display mechanism for watch movement, comprising a first mobile bearing a first sequence of digits and a second mobile bearing a second sequence of digits. The two mobiles are arranged and disposed in such a manner that, at least for certain dates, the day of the month displayed to the user corresponds to the combination of indications borne by the first mobile and of indications borne by the second mobile. The second mobile, for example the mobile bearing at least certain tens, is driven by the other mobile, for example the mobile bearing at least certain units, through a star wheel held by a jumper. A banking element is arranged so as to prevent the jumper from passing directly from one tooth of the star to a non-adjacent tooth when the date changes. 
   This solution has the advantage of reducing or eliminating the risk that the second disc is indexed erroneously by two positions instead of a single one when the date changes, in particular during manual correction of the date. It is thus possible to reduce without risk the spring&#39;s force acting on the jumper holding the star, which allows the energy and power necessary for changing the date&#39;s tens to be reduced. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood by reading the description illustrated by the attached figures that show: 
       FIG. 1   a  a top view of the driving mechanism according to a first embodiment of the invention. 
       FIG. 1   b  a top view of the tens&#39; ring in the first embodiment of the invention. 
       FIG. 2  a top view of the driving mechanism according to a second embodiment of the invention. 
       FIG. 3  a top view of the driving mechanism according to a third embodiment of the invention. 
       FIG. 4  a top view of the driving mechanism according to a fourth embodiment of the invention. 
       FIG. 5  a partial cross section along the axis V-V of the driving mechanism according the invention. 
       FIG. 6  a partial cross section along the axis VI-VI of the driving mechanism according the invention. 
   

   DETAILED DESCRIPTION OF POSSIBLE EMBODIMENTS OF THE INVENTION 
     FIG. 1  shows a top view of the date driving mechanism according to a first embodiment of the invention; only the parts that are useful for understanding the mechanism have been represented in full lines to make the figure easier to understand. 
   The mechanism comprises two mobiles constituted in this example by two concentric and superimposed annular discs  1  and  2 . The first mobile  1 , or units&#39; ring, bears a sequence of digits  10  {1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9}. The digits are regularly spaced with the exception of a greater interval between the last 9 and the first 1 which is sufficient for displaying a two-digit date, as will be seen further below. In the illustrated embodiment, the days of the month are designed to be displayed at twelve o&#39;clock on the dial; the units&#39; digits are thus placed nearly radially, so as to appear vertically when they are seen through a vertical aperture just right of the twelve o&#39;clock position. 
   The second mobile, or tens&#39; ring, is constituted by a second ring  2  turning in concentric fashion above the units&#39; ring  1 , as can be seen particularly in  FIGS. 5 and 6 . It must be observed that on these figures, the dial  6  of the watch is located on the bottom. As can be seen in particular in  FIG. 1   b , the second ring  2  bears in this embodiment the sequence {0,1,2,30,31,0,1,2,30,31}. A vertical window  21  is stamped through the tens&#39; ring  2  on the right of the digits 0, 1 and 2, allowing the digits  10  borne by the units&#39; ring  1  to be seen. 
   In a variant embodiment of the invention, not represented, the second mobile  2  could be constituted by a non-annular element, for example by a cross or a star turning above the first mobile  1 , and provided with non-rectangular blanks  21 , for example in the manner suggested in the mentioned document WO9913383. Furthermore, the tens&#39; mobile could bear a single sequence {0,1,2,30,31} or more than twice this sequence. A single sequence however has the disadvantage of requiring considerable angular steps at each indexation of the mobile, whilst the display of a greater number of sequences by necessity requires the use of smaller digits. 
   In another variant embodiment of the invention, not represented, the two mobiles could be concentric but of different diameter, and thus not superimposed or partially superimposed. In this case, at least one of the two annular discs could bear blanks in the form of internal or external radial flaps to cover the digits or indications borne by the other mobile at certain dates. 
   Furthermore, the one skilled in the art will understand that the blanks provided in the different embodiments of the invention could also be constituted by transparent portions of one of the two mobiles. 
   The arrangement of the digits  10 ,  20  and the inclination of the windows  21  depend on the position chosen for displaying the date on the dial; for example, to display the date at three o&#39;clock, it is necessary to pivot both the digits  10 ,  20  and the windows  21  by 90°. In this arrangement, the digits and the windows occupy a greater angular segment so that one will possibly adopt a number of sequences different from 2 on the tens&#39; ring  2 . The rotation angle depends of course on the angular position of the aperture. 
   In this embodiment of the invention, the date  3  displayed through the aperture  60  in the dial  6  is generally formed of a digit  20  from the tens&#39; ring  2  and of a second digit  10  from the units&#39; ring  1 , visible through a window  21 . However, the 30 th  and 31 st  of the month, the date  3  displayed to the watch&#39;s user comprises two digits borne both by the tens&#39; ring  2 . One thus avoids, for these particular dates, the problem of the difference in depth between the tens&#39; digit and the units&#39; digit. 
   The maximal size of the dates displayed in a conventional large size date display corresponds to the maximal size of the digits one can place both on the tens&#39; and the units&#39; mobile. By choosing to display certain dates with the aid of two digits from the same mobile, one gains the possibility of moving certain indications from one mobile to another, which allows at least for certain configurations the size of the digits that can be displayed to be increased. 
   In the variant embodiment of  FIG. 2 , the units&#39; ring  1  bears the sequence of digits  10  {1,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9, 0,1,2,3,4,5,6,7,8,9} whilst the tens&#39; ring bears the sequence of digits  20  {0,1,2,30,3,0,1,2,30,3}, the ‘0’ being replaceable by spaces. This configuration allows all the days of the month to be displayed with the aid of indications borne by the two mobiles  1 ,  2  with the exception of the date  30  which is indicated by means of two digits borne by the tens&#39; ring  2 . 
   In the variant embodiment of  FIG. 3 , the units&#39; ring  1  bears the sequence of digits  10  {1,2,3,4,5,6,7,8,9} repeated three times whilst the tens&#39; ring bears the sequence of digits  20  {0,10,1,20,2,30,31}. This configuration allows all the days of the month to be displayed with the aid of indications borne by the two mobiles  1 , 2  with the exception of the dates  10 ,  20 ,  30  and  31  which are indicated by means of two digits borne by the tens&#39; ring  2 . 
   The one skilled in the art will understand that other variant embodiments are conceivable within the frame of this invention. For example, in  FIG. 4 , the units&#39; ring  1  bears the sequence of digits  10  {1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0}, whilst the tens&#39; ring bears the sequence of digits  20  {0,1,2,3,31,0,1,2,3,31}. This configuration allows all the days of the month to be displayed with the aid of indications borne by the two mobiles  1 ,  2  with the exception of the date  31  which is indicated by means of two digits borne by the tens&#39; ring  2 . In another variant embodiment, not represented, the days of the month corresponding to the dates  1  to  9  are displayed with the aid of a single mobile; this allows for example this day of the month to be displayed with the aid of a single digit which can also be centered in the aperture  60 . 
   It would also be possible to display certain days of the month with the aid of two digits borne by the units&#39; ring  1 , by displaying certain tens&#39; indications on the units&#39; disc. For example, one could conceive that the units&#39; disc bears the date  30  or the date  31  in full. This variant embodiment however has the disadvantage of requiring windows  21  of large size through the tens&#39; ring  2 , which risks weakening this ring and moreover occupies more space. Furthermore, one could also imagine that certain days of the month are displayed with the aid of two digits borne by the units&#39; ring, others with the aid of two digits from the tens&#39; ring and yet others with the aid of two digits borne by the two rings. Finally, one could in particular for larger size watches use a units&#39; disc turning over the tens&#39; disc and provided with windows for seeing the tens&#39; indications on the second disc. 
   Movements are also known in which the date is displayed with the aid of literal indications, for example with an indication of the month for perpetual calendars and/or with an indication of the day of the week. One will thus understand that the invention also applies to this type of movements for which the different indications constituting the date are borne by a variable number of mobiles according to the date. For example, it would be possible within the frame of the invention to display the day of the week and/or the month in the same aperture  60  or in one or two additional apertures, the day of the week and/or the month being indicated by one or several mobiles according to the date. 
   Furthermore, the indication of the tens and the indication of the units can be displayed in two distinct apertures juxtaposed or placed at different places of the dial, for example at ten o&#39;clock and at two o&#39;clock. 
   We will now describe with the aid of  FIGS. 1 ,  5  and  6  the driving mechanism of the two mobiles  1 ,  2 . In this embodiment, the two mobiles are driven by the same electromechanical or mechanical motor (not represented) and set by the same winding button; it would however also be possible to drive and/or set the two mobiles with two independent motors or by a single motor but through two distinct cinematic chains. 
   A pinion  44  actuated by a motor (not represented) drives a wheel  46  on the axis of which a ratchet device  460  is mounted and arranged so as to cause the rotation, each day, at midnight or at another moment, of the internal gear teeth  11  of the units&#39; ring  1 . In this embodiment, the ring  1  is thus indexed each day by 360/31 degrees in order to complete one turn for each month of 31 days. 
   One could also within the frame of this invention conceive mechanisms in which the change of date does not occur at midnight, as well as mechanisms in which the disc  1  performs one turn during a period different from 31 days. 
   The units&#39; ring  1  comprises driving bankings  12  constituted by portions folded by stamping of the ring  1 . As can be seen in particular on the cross section of  FIG. 6 , these bankings allow a gear element  50  to be indexed, in this example a six-tooth or six-branch star wheel indexed by 60° at each contact with the bankings  12 . The bankings  12  are placed radially on the ring  1  so that one banking actuates the star each time a rotation of the tens&#39; ring  2  is desired. In the embodiment of  FIG. 1 , the tens&#39; ring is actuated 5 times a month:
         on the 10 th  of the month, when passing from the ten  0  to the ten  1 ;   on the 20 th , when passing from the ten  1  to the ten  2 ;   on the 30 th , when passing from the ten  2  to  30 ;   on the 31 st , when passing from the 30 th  to the 31′; and   on the 1 st , when passing from the 31 st  to the ten  0 .       

   The number and the instant of the rotations of the tens&#39; ring depend on the sequences on the two mobiles  1  and  2 , as can be seen by comparing the position of the bankings  12  on the variant embodiments of  FIGS. 1 to 4 . 
   The star wheel  50  drives at each rotation a wheel  52  mounted on the same axis, which itself actuates a wheel  53 . The wheel  53  is mounted on the axis of a wheel  54  engaging with the internal gear teeth  22  of the tens&#39; ring  2 . The engaging ratio between the wheels  50  and  53  is chosen so that the indexing angle of the ring  2  caused by a displacement of the star  50  corresponds to the angular distance between two tens&#39; digits. 
   The star wheel  50  is held by a jumper  51  pressing against the interstice  502  between two teeth  501  of the star  50  by a spring  510 . The jumper makes it possible to prevent the star  50  from turning freely, in particular when it is driven by a catch banking  12 . In order to force the jumper  51  to move close to the bottom of the interstice  502  between two teeth  501 , it is provided by a banking element  511 , constituted here by a pin perpendicular to the watch&#39;s plane, moving in a slide way  500  machined in the wheel  52 . The shape of the slide way  500  prevents the pin  511  from jumping directly from one interstice  502  to a non-adjacent interstice between two teeth of the star  50 ; it thus surrounds the star wheel  50  by approximately marrying its contours. 
   As can be seen in particular in  FIG. 5 , the first mobile  1  slides directly on the upper bridge  9  of the watch movement, and is held by a first plate  8  mounted over this bridge. The second mobile  2  slides on a ring path over this first plate  8  and is held by a second plate  7 . The dial  6  is fastened over the second plate and provided with an aperture  60  to display the days of the month borne by the first and/or second mobile.