Abstract:
A calendar corrector is disclosed for arrangement in a movement of a watchmaking part provided with a calendar display and, for example, a thirty-one wheel which goes round in thirty-one days. In one implementation, the corrector comprises a manual control, enabling information relating to the fact that the current month comprises less than thirty-one days to be introduced, and programming means coupled to the thirty-one wheel, responding to the information introduced by the control, such that the display can be corrected automatically at the end of the current month.

Description:
This application is a national stage filing under 35 U.S.C. 371 of International Application No. PCT/CH2004/000490, filed on Aug. 5, 2004, which claims priority to European Application No. 03405589.7, filed on Aug. 12, 2003. 
     TECHNICAL FIELD 
     The present invention relates to timepieces that display the calendar. It relates more specifically, based on the same principle, to a manual calendar corrector mechanism for a simple calendar and to an automatic calendar corrector mechanism for a perpetual calendar. 
     BACKGROUND 
     In a watch, the calendar mechanism allows the date of the month to be indicated by means of a hand moving over the dial or by means of a disk rotating under the dial and showing its information through a window. This kind of system is well known to those skilled in the art and is described in detail, for example, in the work entitled “Théorie de l&#39;horlogerie” by Reymondin et al., Fédération des Ecoles Techniques, 1798, ISBN 2-940025-10-X, pages 189 et seq. 
     It will be recalled that the calendar indicator, whether a disk or a hand, is actuated off the hours wheel, via the calendar gear-train the last element of which is a thirty-one wheel performing one revolution in thirty-one days by advancing by one step of 360/31° every twenty-four hours, at around midnight. In the case of a display using a hand, the hand is mounted so that it rotates as one with the shaft of this wheel. In the case of a display using a disk, this disk is driven by a finger integral with the thirty-one wheel. 
     For months comprising fewer than thirty-one days it is necessary, in the case of simple calendars, to make a manual correction. This operation can be performed either by rotating the winding stem in its quick date-setting position or by actuating a push-button fitted freely into the watch case middle. Of course, the operation has to be performed on the last day of a month comprising fewer than thirty-one days or on the first day of the next month. 
     In order to avoid the user having to perform such updates, various mechanisms, known as perpetual calendars, have been developed. They automatically adapt to the length of the months, sometimes even predicting leap years. A toothed wheel, known as a cam, has hollows the depths of which are correlated to the length of the months. Schematically speaking, the cam comprises forty-eight or twelve sectors, depending on whether or not the mechanism takes account of leap years. A complex assembly of several other cams and levers, one of which is equipped with a nose collaborating with the first cam, transmits to the thirty-one wheel the order to jump by one, two or three days at the end of a thirty-day, a twenty-nine-day or a twenty-eight-day month, respectively. 
     SUMMARY OF THE INVENTION 
     The initial object of the present invention is to propose a simple calendar corrector allowing the correction in the display of the date to be programmed simply on any day of a month comprising fewer than thirty-one days so that the correction is actioned on the last day. 
     More specifically, it relates to a simple calendar corrector intended to fit in a movement of a timepiece equipped with calendar-display means and with a thirty-one wheel that makes one revolution in thirty-one days. This corrector comprises:
         manual control means allowing information relating to the fact that the month in progress comprises fewer than thirty-one days to be input, and   programming means comprising a clutch runner equipped with two coaxial toothed disks, namely a first disk that can be rotationally driven in a first direction by the thirty-one wheel and a second disk that can be rotationally driven in a second direction, the opposite to the first, by the control means, so that, at the end of the month in progress, the display means are automatically corrected.       

     The second object of the invention is to provide a perpetual calendar mechanism devoid of the customary cams and levers. 
     In order to achieve this second object, the perpetual calendar corrector according to the invention comprises:
         automatic control means which, during each month comprising fewer than thirty-one days, produce information relating to the correction that will have to be made at the end of said month, and   programming means comprising a clutch runner equipped with two coaxial toothed disks, namely a first disk that can be rotationally driven in a first direction by the thirty-one wheel and a second disk that can be rotationally driven in a second direction, the opposite to the first, by the control means, so that, at the end of the month in progress, the display means are automatically corrected.       

     In both instances, whether in the case of a simple calendar or of a perpetual calendar, the disks are coupled together by a spring and by a system of pawls which are arranged in such a way that:
         the first disk rotates in the first direction independently of the second,   the second disk drives the first when it rotates in the first direction, and   the second disk does not drive the first when it rotates in the second direction, at that time merely loading said spring.       

     Furthermore, the programming means comprise:
         a finger fixed to the thirty-one wheel,   a first lever pivotably mounted on the second disk and that can be actuated by said finger on the last day of the month, and   a second lever mounted independent of the clutch runner, that can be actuated by the first lever when the latter is moved by the finger, immobilizing the second disk and releasing it when actuated in such a way that, subjected to the action of said spring, the first disk progresses rapidly in order to correct the calendar display.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other characteristics of the invention will become more clearly apparent from reading the description which follows, with reference to the attached drawing in which: 
         FIGS. 1 and 3  are views from above of the simple corrector according to the invention, at the end of thirty-one-day and twenty-eight-day months respectively, 
         FIG. 2  is a view in cross section of the mechanism of  FIG. 1 , and 
         FIG. 4  is a view from above of the perpetual calendar mechanism at the end of a thirty-day month. 
     
    
    
     DETAILED DESCRIPTION 
     The mechanism according to the invention is intended to fit in the movement of a mechanical or electro-mechanical watch with calendar display. As the realization of this function is perfectly well known to those skilled in the art and does not specifically form part of the invention, it will not be described in detail. 
       FIGS. 1 to 3  depict a thirty-one wheel  10  rotating in the clockwise direction (hereinafter CWD) at a rate of one revolution in thirty-one days. It bears, fixed to its shaft  11 :
         a hand  12  indicating the date on a series of numerals ranging from  1  to  31 , written on a dial  13 , and   a finger  14  the length of which exceeds the radius of the wheel  10 .       
     The essential component in the mechanism is a clutch runner with pawls  15 , comprising two coaxial toothed disks, a lower one  16  and an upper one  17 . The lower disk  16  meshes with the thirty-one wheel  10  and therefore rotates in the counterclockwise direction (hereinafter CCWD). The upper disk  17  is driven in the CWD by a push-piece  18  protruding from the watch case middle to form a button  19  accessible to the wearer of the watch. Pressing the button  19  causes the disk  17  to move on by one step, that is to say by 360/31°, then a spring  20  returns the push-piece  18  to its initial position. 
     The runner  15  is provided, according to a construction well known to those skilled in the art, with pawls and with a spring which are positioned between the two disks  16  and  17  but which are not visible in the drawing. The lower disk  16  thus rotates in the CCWD independently of the upper disk  17  which drives the disk  16  only when it rotates in the CCWD but not when it rotates in the CWD, in such circumstances merely loading the spring. 
     A first lever  22 , known as the small lever, is pivotably mounted about a spindle  23  on the upper face of the upper disk  17 . It consists of two arms  22   a  and  22   b  typically making an angle of about 120° between them and facing, the first ( 22   a ) toward the inside and the second ( 22   b ) toward the outside of the disk. The outer arm  22   b  is normally held pressed against a stop  24  positioned at the periphery of the disk  17  by a spring (not depicted), while its end lies flush with the edge of the disk. It will be noted, as shown by  FIG. 2 , that the small lever  22  is at the same level as the finger  14  of the thirty-one wheel  10 . 
     The mechanism comprises a second lever  25 , known as the big lever, which pivots about a spindle  26  riveted to the plate. This lever is roughly L-shaped. Its short arm  25   a  is positioned at the upper disk  17  and ends in a lug  27  that a jumper  30  presses against the toothset of the disk so as to prevent it from rotating in the CCWD. The long arm  25   b  of the big lever  25  is arranged on the upper disk  17  and provided with a shoulder  28  designed in such a way as to take the thrust of the short arm  22   a  of the small lever  22 . The long arm  25   b  ends in a boss  29  intended to experience the action of a safety block  31  riveted to the upper face of the disk  17  when the latter pivots in the CWD. 
     Advantageously, the series of numerals  28 ,  29 ,  30 ,  31  is written onto a portion of the periphery of an indicator disk  32  fixed to the shaft of the upper disk  17 , above the latter. A window  33  made in the dial  13  reveals one of the numerals in the series, depending on the position of the disk  17 . The usefulness of this indicator system will become more clearly apparent on reading the remainder of the description which explains how the mechanism according to the invention works. 
     In the course of a thirty-one-day month, there is no need to correct the calendar display. The thirty-one wheel  10  rotates the lower disk  16  of the clutch runner  15  in the CCWD, without that having any effect because the upper disk  17  is held immobile by the lug  27  and by the pressure of the jumper  30  on the short arm  25   a  of the big lever  25 . The indicator disk  32  is then positioned in such a way that the numeral  31  of the series on the disk  32  appears through the window  33 . 
     As the wheel  10  turns, the date display hand  12  performs its function in the normal way and the finger  14  moves over the upper disk  17  without its travel meeting the small lever  22 . 
     During a twenty-eight-day month of February it is necessary to make a correction of three steps so that, on the twenty-eighth day of the month, at around midnight, the hand  12  skips the days  29 ,  30  and  31  and directly indicates the first day of the month of March. 
     In order to do this, on the day of his choosing during the month of February, the user presses three times in succession on the button  19  part of the push-piece  18 , and this has the effect of rotating the upper disk  17  in the CWD by an angle of 3 times 360/31°. The lower disk  16  does not rotate but the spring of the runner  15  becomes loaded. The big lever  25  prevents the disk  17  from returning in the CCWD under the effect of the spring of the runner  15 . Of course, as  FIG. 3  shows, the small lever  22  and the safety block  31  are brought closer to the point of meshing of the thirty-one wheel  10  and the clutch runner  15 . It is important to note that the long arm  22   b  of the small lever  22  is now in the path of the finger  14 . More specifically, it is positioned in such a way as to meet it at the moment when the date indicator hand  12  moves on from the twenty-eighth to the twenty-ninth day. The numeral  28  in the series  28 ,  29 ,  30 ,  31  on the disk  32  then appears through the window  33 . 
     When, on the twenty-eighth day of the month, at around midnight, the thirty-one wheel  10  moves on by one step, the finger  14  comes into contact with the long arm  22   b  of the small lever  22  and causes it to pivot about its spindle  23 . The short arm  22   a  then presses against the shoulder  28  of the big lever  25 , applying pressure greater than that exerted by the jumper  30 . The big lever  25  pivots and the lug  27  breaks contact with the toothset of the upper disk  17 . 
     Thus released, the upper disk  17  skips three steps in the CCWD, moved by the spring which suddenly unloads. At the same time it drives the lower disk  16  which meshes with the thirty-one wheel  10 . The latter and the date indicator hand  12  therefore also skip three steps in the CWD. 
     The hand  12  then indicates the first day of the month of the series inscribed on the dial  13 . The numeral  31  in the series on the indicator disk  32  shows again through the window  33 . 
     For twenty-nine-day or thirty-day months, the mechanism works in the way that has just been described but the user presses twice or once on the button part  19  of the push-piece  18  in order thus to cause the upper disk  17  to move on by two steps or by one step, respectively. 
     There is no situation in which it is necessary to modify the calendar display by four days. Thus, were the wearer to press the push-piece  18  four times, the display will be one or more days out when moving on to the first day of the month. In addition, it could be inappropriate to apply excessive stress to the spring of the runner  15 . 
     In order to circumvent these problems, when three corrections have been made, as in the example set out hereinabove, the safety block  31  lies at the base of the boss  29  of the long arm  25   b  of the big lever  25 . Further pressure on the push-piece  18  causes the upper disk  17  to rotate by an additional step in the CWD and the block  31  pushes the boss  29  by applying a pressure greater than that exerted by the jumper  30 . The big lever  25  in its turn pivots and the lug  27  breaks contact with the toothset of the upper disk  17 , allowing the spring of the runner  15  to return to its rest position. 
     Thus, a calendar corrector mechanism is proposed that allows the correction that needs to be made to be programmed on any day of a month comprising fewer than thirty-one days, the correction being actioned on the last day of the month, at around midnight. 
     In order to avoid the user having to make the corrections himself, the present invention finds a second application in a perpetual calendar mechanism, illustrated in  FIG. 4 , which automatically takes account of the number of days in the various months. 
     This mechanism again includes:
         the thirty-one wheel  10 ,   the clutch runner with pawls  15 ,   the small lever  22  and its stop  24 ,   the big lever  25  and its jumper  30 , and   the indicator disk  32 .       

     These various elements are arranged in the way described previously but, this time, the upper disk  17  is no longer driven by a push-piece. 
     The mechanism in  FIG. 4  is set out in a simplified version that does not account for leap years. It comprises a months wheel  40  divided into twelve sectors  41  each corresponding to one month of the year. Each of these sectors  41  is either devoid of teeth, if identified with a thirty-one-day month or equipped with one tooth  42  in the case of thirty-day months, or equipped with three teeth  42  in the case of the month of February. These teeth  42  are positioned in a way that will be explained later on. 
     The teeth  42  are in mesh with an intermediate runner  43 , itself meshing with the upper disk  17  of the clutch runner  15 . The toothsets of these various runners have identical pitches, which means that an advance of the wheel  40  by one step causes the same advance of the disk  17 . 
     A months star  44  with twelve branches  45  is mounted coaxial to and rotating as one with the months wheel  40 . Each branch  45  corresponds to one month of the year. The star  44  is positioned by a jumper  46  with two inclined planes, so that, for example, when the tooth  42   a  of the sector  41   a  of the month of April of the wheel  40  is in mesh with the runner  43 , the branch  45   a  of the month of April is in the path of a finger  47  mounted on the shaft of a second thirty-one wheel  48 . The latter is identical to the first thirty-one wheel  10  and meshes with it. The length of the finger  47  exceeds the radius of the wheel  48 . 
     In operation, the first thirty-one wheel  10  rotates in the CWD and drives, in the CCWD, on the one hand, the second thirty-one wheel  48  and, on the other hand, the lower disk  16  of the clutch runner  15  without having any other impact. 
     For a thirty-one-day month, the finger  47  is positioned in such a way as to lie flush with the branch  45   b  of the months star  44  corresponding to this month, preferably the first day of the month. Then, when, on this first day, at around midnight, the thirty-one wheel  10  and therefore the wheel  48  and the finger  47  move on by one step, this finger pushes the branch  45   b  and drives the star  44  and the months wheel  40  by one step in the CWD. Henceforth, they are in position ready for the next month. 
     The wheel  40  and the star  44  rotate in two phases. First of all, rotation is slow when the branch  45   c  pressed against the jumper  46  raises it by sliding along its first inclined plane. Rotation is then quicker, when this branch arrives on the second inclined plane. The pressure then exerted by the jumper  46  accelerates the movement of the star. 
     The sector  41   b  of the months wheel  40  corresponding to a thirty-one-day month has no teeth and therefore does not drive the intermediate runner  43 , even though it faces it as the wheel rotates. The upper disk  17  of the clutch runner  15  therefore does not move either and no movement is transmitted to the thirty-one wheel  10 . 
     As in the case of the manual corrector set out hereinabove, the indicator disk  32  shows, through the window  33 , the numeral  31  corresponding to the number of days that the month comprises. 
     For a thirty-day month, the finger  47  lies flush with the branch  45   a  of the months star  44  corresponding to this month, also the first day of the month. Then, when, at around midnight, the thirty-one wheel  10  and therefore the wheel  48  and the finger  47  move on by one step, this finger pushes the branch  45   a  and drives the star  44  and the months wheel  40  in the CWD. 
     The teeth  42  of the months wheel  40  and, more specifically, the tooth  42   a  of the sector  41   a  corresponding to this thirty-day month are positioned in such a way as to drive the runner  43  in the CCWD during the rapid phase of the rotation of the star  44 . The latter, in its turn, causes the upper disk  17  of the clutch runner  15  to rotate by one step in the CWD, loading its spring but without driving the lower disk  16 . The small lever  22  is now positioned in such a way that its long arm  22   b  comes into contact with the finger  14  on the thirtieth day of the month at around midnight. The numeral  30  featuring on the indicator disk  32  appears through the window  33 . 
     In the manner of that which occurs in the case of the manual corrector set out hereinabove, the big lever  25  prevents any rotation of the upper disk  17  in the CWD. On the thirtieth day of the month at around midnight when the finger  14  moves on by one step, it comes into contact with the long arm  22   b  of the small lever  22  which pivots and pushes the long arm  25   b  of the big lever  25 . This lever rotates in its turn and releases the upper disk  17 . It then jumps by one step in the CCWD, moved by the spring of the clutch runner  15  which suddenly unloads and at the same time drives the lower disk  16 . The thirty-one wheel  10  and the date indicator hand  12  therefore also skip a step in the CWD. The hand  12  therefore indicates the 1st day of the month on the series inscribed on the dial  13  and the numeral  31  of the series on the disk  32  once again appears through the window  33 . 
     For twenty-eight-day or twenty-nine-day months of February, the mechanism works in the way just described, but the months wheel  40  causes the intermediate runner  43  to turn and therefore advances the upper disk  17  by three or by two steps. 
     In order for the abovedescribed mechanism to take account of leap years, the person skilled in the art will have no difficulty in adding a system, known as a Maltese cross system, to the months wheel  40 . Thus, the sector corresponding to the month of February exhibits, once every four years, two teeth causing the date indicator hand  12  to skip two steps at the end of the twenty-nine-day month. 
     Obviously, the months wheel is able to display the current month by means, for example, of an indicator hand mounted on its shaft and pivoting on a small dial. 
     The above description has been given merely by way of example and does not restrict the scope of the invention. It may easily be adapted to a calendar display mechanism employing disks, these being driven by a transmission gear train from the thirty-one wheel  10 . 
     Likewise, various solutions can be used to display the number of days programmed for the month. For example, a green region inscribed on the upper disk and occupying an angle of 360°/31 may travel under the dial. It can be seen through holes corresponding to the positions occupied by this green region when the corrections have been made in respect of the months comprising  28 ,  29 ,  30  or  31  days. The portions adjacent to the green region are advantageously red in color to signal clearly that the numerals in the series  28 ,  29 ,  30 ,  31  to which the red corresponds do not indicate the number of days in the current month. 
     In another, even simpler, solution, a hand mounted to rotate as one with the shaft of the upper disk  17  indicates, on a portion of the dial, the number of days that the month in progress should contain, according to the actual status of the corrector.