HK1174980B - Program wheel of a calendar mechanism - Google Patents

Description

Program wheel of calendar mechanism

Technical Field

The present invention relates to a program wheel of a calendar mechanism, and more particularly to a program wheel of a perpetual calendar mechanism.

Background

Almanac and perpetual almanac mechanisms have long been known, which enable the display of the dates of the months to be automatically incremented, taking into account the months of less than 31 days, and not requiring any manual intervention to correct these months; the perpetual calendar mechanism additionally takes into account leap years in order to increase the date on the last day of february.

The perpetual calendar mechanism uses a cam of type 12 or 48, the latter performing one revolution per year or every four years, respectively, and having notches for different depths for months of less than 31 days. In the case of a cam of type 12, the february notch additionally comprises a year indexed/transposed (index) by Maltese crosses, which defines a smaller depth for the leap year. The beak of the lever, which is restored by a spring, acts on the cams for these date display mechanisms to determine the advance of the date indicator at the end of the month according to the depth of engagement. This results in a relatively complex structure with a number of important parts, which is not very reliable in operation, for example in the event of shocks. Moreover, such a cam system only allows the date wheel and the basic movement to be synchronized in a given direction, so that the date value can only be increased and not decreased during the hour adjustment operation.

To overcome these drawbacks, the solution disclosed in patent document CH 680630 proposes, for example, a perpetual calendar mechanism comprising a program wheel driven by a projecting tooth of a 24-hour wheel and provided with a gear train so that it always moves along a number of steps corresponding to the difference between the days of the month and 31. This mechanism has no lever, balance or spring at all, except for the jumper spring for the indexed date wheel. However, the transmission system is very complex, with a large number of planetary gears equipped with long teeth for indexing readjustment, said long teeth being arranged eccentrically on the program wheel. This therefore leads not only to great height requirements on the base plate, but also to very high production costs, in particular because the shaft requires a high-precision positioning to ensure reliable engagement with the 24-hour wheel.

Document EP1351104 proposes an alternative to the above solution, with the aim of reducing the number of components on the program wheel. Thus, the disclosed calendar mechanism provides a program wheel having a moving element with retractable teeth that slide between an operative position and an inoperative position. Such an arrangement enables the overall thickness of the program wheel to be effectively reduced. However, the sliding moving element has a very specific shape and must be positioned precisely between the abutment and the shoulder with a complex geometry. Furthermore, the control device still comprises a large number of planet gears with teeth of unequal length, which act on cam surfaces on the sliding element. Therefore, not only is the reliability of the engagement questionable, but also the wear of the different parts of the control device is aggravated, due to the large number of guide surfaces for the sliding elements.

There is therefore a need for a calendar mechanism, in particular a perpetual calendar mechanism, which overcomes the above-mentioned limitations of the prior art.

Disclosure of Invention

It is an object of the present invention to provide an alternative to conventional calendar mechanisms which has a simplified structure and in which the adjustment of hours and dates can be synchronized in both directions.

It is a further object of the present invention to provide such a solution that minimizes energy losses during different indexing operations, in particular during indexing readjustments at the end of months of less than 31 days.

These objects are achieved, inter alia, by a calendar mechanism comprising a program wheel arrangement 100 for a calendar mechanism, wherein the program wheel 100 comprises: a date program wheel 13 and a coaxially mounted month program gear 43, said date program wheel 13 being driven by a timepiece movement and actuating the gear trains 16-24 for the display of the dates in the months and performing one complete revolution per month, said month program gear 43 performing one complete revolution per year.

One advantage of the proposed solution is that the number of elements required for the program wheel is minimized and that the arrangement of the different gears that are active during the different day indexing readjustments is simplified. Furthermore, since many of the gears forming the program wheel are coaxial, assembly of the program wheel is facilitated.

Another advantage of the proposed solution is that it ensures better meshing reliability and better durability, since the wear of the wheels used during each indexing operation is limited.

An additional advantage of the proposed solution is that only planetary gears with simple geometry are used, wherein all teeth are identical. Therefore, it is possible to dispense with a planetary gear having long teeth, and the machining thereof is very complicated.

Another advantage of the proposed solution is that each readjustment train member mounted on the program gear for automatically indexing the dates in months of less than 31 days can be easily replaced in a modular manner with meshing levels instead of meshing levels.

Drawings

Exemplary embodiments of the invention are described below and illustrated in the accompanying drawings, wherein:

FIG. 1A is a partial cross-sectional view of a calendar mechanism according to a preferred variation of the present invention;

fig. 1B is a partial plan view of a calendar mechanism according to the preferred variant of the invention shown in fig. 1A, in particular with a program wheel and a planetary gear;

fig. 1C is a plan view of a display device of a calendar mechanism according to the preferred modification of the present invention shown in fig. 1A and 1B;

fig. 2A is another sectional view of the calendar mechanism according to a preferred variant of the invention, which shows in particular the control mechanism of the display of the program wheel and of the months and leap years;

FIG. 2B is a partial plan view of a calendar mechanism according to a preferred variation of the invention shown in FIG. 2A;

figures 3A and 3B show a section and a plan view, respectively, of a control mechanism for the display of 24 hours and days of the week, associated with a calendar mechanism according to a preferred variant of the invention;

FIGS. 4A and 4B show the cross-sectional view of FIG. 3A and a plan view at another meshing level of the control mechanism and day of the week display, respectively;

FIGS. 5A and 5B show a cross-sectional view and a perspective view, respectively, of a preferred embodiment of a program wheel and an indexing gear in accordance with the present invention;

FIG. 6 is a perspective view of a calendar mechanism according to a preferred variant of the invention, using the preferred embodiment of the different modules shown in the previous figures;

fig. 7A and 7B show the different indexing sequence operation of the two first and third planet gears and the date indexing gear, respectively, on their respective meshing levels for the perpetual calendar mechanism according to a preferred embodiment shown in fig. 5 on day 28 of february in non-leap years.

Detailed Description

The calendar mechanism according to the invention is preferably a perpetual calendar mechanism with display of the week, 24 hours, month and leap years. However, it will be appreciated by those skilled in the art that for other types of calendar mechanisms, the various modules forming the calendar mechanism described above may also be used independently of one another; and, by adjusting the number of planetary gears and the number of meshing levels, the program wheel can be adapted equally to simpler mechanisms, such as an annual calendar mechanism or a calendar mechanism for the months of 30 days.

Fig. 1A and 1B show a sectional view and a plan view, respectively, of a drive wheel train for displaying the date in the month, forward from the movement, while fig. 1C shows a typical date of the month display device. Fig. 1B particularly shows the position of the wheel train relative to the housing 0 and particularly shows the operation of the adjustment mechanism of the date value effected by the manual date correction actuator 26.

In the following, reference will be made alternately to fig. 1A and 1B, which may be referred to in combination for a better understanding of the drive train of the calendar mechanism according to the preferred embodiment shown. Hour wheel 1 of the movement meshes with 24 hour wheel 2 containing twice the number of teeth. In this case, the 24-hour wheel 2 is provided with a date meshing segment 11, which date meshing segment 11 is composed of 7 teeth spaced apart by 15 degrees, so that the change from one tooth to the other takes place every hour. The date meshing section 11 of the 24-hour wheel meshes with a calendar indexing gear 12 on the first level a visible in fig. 3A, the calendar indexing gear 12 consisting of 8 teeth on this meshing level. Thus, each day, the 24-hour wheel causes the calendar indexing gear 12 to perform one full revolution when engaged with 7 teeth of the engagement section 11, i.e. within an interval of 8 hours. When the day indexing gear 12 is not engaged with the toothed meshing sector 11, it still rests on the non-toothed sector of the 24-hour wheel (which is indicated by the reference 11' in fig. 1A) and is thus held in position. The meshing section 11 of the 24-hour wheel and the calendar indexing gear 12 are therefore preferably arranged so that said calendar indexing gear 12 performs one complete revolution per day between 18.00 hours and 2.00 hours of the morning and the indexing effected by the date program wheel 13 takes place between 20.00 hours and the midnight.

As can be seen from fig. 1A, the calendar indexing gear 12 has a plurality of meshing segments 28, 29, 30, 31 which are distributed over different meshing levels B, C, D, E. These segments will be more clearly seen in particular in fig. 5B, which shows them in perspective view. Moreover, according to the preferred embodiment described, these engagement segments are continuous and therefore can engage with the day program wheel 13 every hour. Fig. 1B shows the engagement level B of the engagement segment 29 engaging with the program wheel 100, i.e. the second engagement level downwards in fig. 1A. The planet gear 129 rotates about its axis of rotation 120' and additionally meshes with an indexing tooth 451 for the month of february, said indexing tooth 451 being the only tooth of the program gear 45 for the month of february, said program gear 45 being integral with the program gear 43 visible in fig. 2B. The engagement segment 29 is preferably arranged to engage the planet gear 129 between 21.00 hours and 22.00 hours for readjustment from day 29 to day 30 in the month of february, as will be described in detail in fig. 7A and 7B.

The date program wheel 13 comprises a uniform date indexing tooth system 13 'with 31 teeth (i.e. in which the height of each tooth and the spacing between each tooth is the same), and said system 13' is indexed by pitch by one tooth per day by the above-mentioned train starting from the date meshing sector 11 of the hour wheel 1, i.e. the 24 hour wheel 2, the 24 hour wheel, and the date indexing gear 12. In fact, according to the preferred embodiment shown, the toothed segment 31, fixed against relative rotation with the day indexing gear 12, meshes with a corresponding tooth 131 of the day indexing tooth system 13' of the day wheel 13, preferably between 23.00 hours and midnight each day. Unlike the toothed segment 31 of the calendar indexing gear 12, said tooth 131 is different every day and corresponds each time to another tooth of the external date indexing tooth system 13', since it is defined only with respect to the tooth 31 of the calendar indexing gear 12. The elastic indexing element 14 of the program wheel, which is located between two consecutive teeth after each jump, enables indexing with pitch by a single tooth. According to the preferred embodiment shown, the day indexing tooth system 13' is located on the outer periphery of the day program wheel 13. However, an alternative embodiment can be envisaged in which the tooth system is located on the inside surface of the date ring.

In combination with the corresponding planetary gears 128, 130 provided on the program wheel 100, more precisely on the day program wheel 13, the other meshing segments 28 and 30 of the calendar indexing gear 12 (which are visible only in fig. 1A for the sake of clarity) are used to perform an additional readjustment for months of less than 31 days. As is evident in succession, in particular on the basis of fig. 5, 6 and 7, the planet gear 129 meshes on the meshing level B, while the other planet gears 128 and 130 (whose respective axes of rotation 128 'and 130' are integral with the date wheel 13) mesh on levels E and D, respectively, for indexing from 28 to 29 in february months of non-leap years, and for indexing from 30 to 31 in months of less than 31 days. These indexing readjustments preferably take place between 20.00 hours and 21.00 hours and between 22.00 hours and 23.00 hours, respectively.

At the bottom of fig. 1A, a meshing level G can be seen, which corresponds to the meshing of the intermediate month control wheel 42 with the month program gear 43, which month program gear 43 is indexed, i.e. changes the value of the month, by 1/12 revolutions at the end of each month. The intermediate month control wheel 42 is the last link of the control train for such monthly indexing operation of the external date indexing tooth system 13' starting from the date program wheel 13 and will be further described below on the basis of fig. 2A and 2B. A fixed wheel 47 ' is also visible, which allows the maltese cross 46 ' (which can also be seen more clearly in fig. 2A and 2B) to perform 1/4 revolutions per year, during which the month program gear 43, integral with said fixed wheel 47 ', performs one complete revolution. The maltese cross 46' meshes on a meshing level F situated above the meshing level G and is integral with a leap year indexing gear 46, said leap year indexing gear 46 comprising three teeth on the meshing level E (which can be clearly seen in fig. 5B).

In fig. 1A and 1B it can be seen that, at the meshing level C, the day indexing tooth system 13' meshes with the day wheel 16 via an intermediate day wheel 15 arranged coaxially but freely rotatable with respect to the intermediate month control wheel 42, said day wheel 16 also having 31 teeth as the day program wheel 13. Said intermediate day wheel 15 constitutes only one circuit for all indexing movements on the day program wheel 13 to be integrally responsive on the day wheel 16 and, conversely, all rotational movements of the day wheel 16 to be integrally responsive on the day wheel 13 during adjustment using the manual actuator 26, described further below. Thus, there is no need for an elastic indexing element to index the date wheel 16. In case the height in the housing 0 is sufficient, the date program wheels 13 and 16 can be arranged coaxially and superposed, or even merged. According to the preferred embodiment described, the separation of the program wheel 13 and the date program wheel 16 allows the functional separation of the unit formed by the date program wheel 13 dedicated to meshing with the movement in order to automatically correct the dates of the months of less than 31 days, from the unit formed by the date wheel 16, the units wheel 17 and the tens wheel 18, said date wheel 16, units wheel 17 and tens wheel 18 being coaxial with each other, rotationally fixed to each other and dedicated to meshing with a date display gear, which is shown in fig. 1C and will be described below.

The unit wheel 17 is divided into 31 equal angular sectors, i.e. a sector with 30 teeth thereon and a sector without teeth. The unit wheel 17 drives a gear for actuating the unit display disc 19 on each day of the month other than No. 1. The ones display disc 20, integral with said gear for actuating the ones display disc 19, is thus indexed by one unit per day, except for the transition from the 31 st day of the month to the 1 st day of the following month, during which only the tens display disc 23 is added. Said gear for actuating the unit display disc 19 comprises 10 teeth and is indexed by pitch by 1/10 revolutions, by means of the elastic indexing element 24 coming to the unit disc between two consecutive teeth.

The ten-position display plate 23 is integrated with an actuating gear, i.e., a gear for actuating the ten-position display plate 22, the ten-position display plate 22 having a cross shape with 4 arms and indexed by 1/4 revolutions during the transition from the 9 th to the 10 th days, from the 19 th to the 20 th days, from the 29 th to the 30 th days, and from the 31 st to the 1 st days. The jump of 1/4 revolutions is ensured by the elastic indexing element 24 coming to the tens display disc between two adjacent arms of the cross; and indexing on these date values is ensured by the long teeth provided on the tens wheel 18, said tens wheel 18 also being divided into 31 sectors, but comprising only 4 long teeth, of which 3 are provided at 9 sector intervals, the 4 th long tooth being after the 3 rd long tooth for the transition from day 31 to day 1 of the next month.

In each of fig. 1A, 1B and 1C, there can be seen, in part, a train for the display of the date in the month, made up of the elements with reference numbers 16 to 24 from the date wheel 16 to the units display 20 and the tens display 23: fig. 1A shows the entire train, but without the elastic indexing elements 21 and 24 of each actuation gear 19 and 22 associated respectively with the units display disc 20 and the tens display disc 23, and fig. 1B shows the meshing levels beneath these units display disc 20 and tens display disc 23, said units display disc 20 and tens display disc 23 thus being visible only in fig. 1C.

The adjustment of the day of the month is carried out by means of a manual actuator 26 provided on the housing 0. According to the preferred embodiment described in fig. 1A and 1B, the manual actuator 26 for date adjustment is a push button which is pressed at most 30 times in succession to reach the desired date. Adjustment mechanism 25 is not shown in fig. 1B for clarity, adjustment mechanism 25 enabling the transmission of the pulse from the push button to date gear 16; however, such mechanisms are known to those skilled in the art. Instead of a push button, a shaft could be used as manual actuator 26, in which case the rotation of the shaft could drive the date gear 16 in rotation in both directions together with a suitable mechanism 26 for adjusting the day of the week. However, according to the preferred embodiment shown, and with the alternative proposed, such an adjustment of the date cannot be made when one of the meshing segments 28, 29, 30 or 31 of the indexing gear 12 is engaged with the date program wheel 13, either directly or via the planetary gears 128, 129, 130, that is to say between 20.00 and 24.00. In fact, the direct engagement of the day indexing gear 12 and the day meshing sector 11 of the 24-hour wheel tends to transfer these indexing operations to the hour wheel 1, which is unlikely without impairing the normal functioning of the movement.

Fig. 2A and 2B show a section and a plan view, respectively, of a calendar mechanism according to a preferred variant of the invention, in which the control wheel train for positioning the month program gear 43 in order to properly position the pivoting retractable teeth, and the wheel train for displaying the months and leap years are described. Two further manual actuators are shown at the position of the casing 0, the first one, referenced 48 and at 8 o 'clock on the casing, for adjusting the month, the second one at 4 o' clock on the casing 0, in the form of a crown 50, usually provided, for example, on a tie rod, one of the axial positions of which enables the movement to be rewound, the other axial position allowing the hour and minute hands to be adjusted bidirectionally.

In the central part of fig. 2A, a gear wheel can be seen, on which the monthly indexing teeth 32 visible in fig. 2B are provided. Said monthly indexing tooth 32 meshes with a monthly indexing gear 33 having 8 teeth, said monthly indexing gear 33 being fixed together non-rotatably with a month control wheel 41 having 32 teeth, said month control wheel 41 meshing, on a meshing level G, with an intermediate month control wheel 42, said intermediate month control wheel 42 being coaxial with the intermediate date wheel 15 but not fixed non-rotatably with respect to the intermediate date wheel 15, said intermediate month control wheel 42 in turn meshing with a month program gear 43 having 48 teeth. The monthly indexing gear 33 performs exactly 1/8 revolutions per month due to the elastic indexing element 34 coming between two consecutive teeth of the monthly indexing gear 33. The transmission ratio between the monthly indexing gear 33 and the number of month program gears 43 allows the month program gears 43 to be indexed by exactly 1/12 revolutions per month.

The monthly indexing gear 33 additionally meshes with an intermediate monthly indexing gear having 23 teeth, which in turn meshes with an actuating gear 36 for the month display having 12 teeth. The gear ratio 8/12 between the monthly indexing gear 33 and the actuating gear 36 for the month display ensures that the actuating gear for the month display performs exactly 1/12 revolutions at the end of each month. Said actuating gear 36 for the month display is non-rotatably fixed with respect to a year indexing tooth 37, said year indexing tooth 37 being positioned on one wheel performing one complete revolution per year. The year indexing tooth 37 meshes with a leap year actuating gear 38 having 8 teeth, which leap year actuating gear 38 is shifted by two teeth, i.e. 90 degrees, during each meshing with the year indexing tooth 37. The leap year actuating gear 38 is fixed in a non-rotatable manner relative to an intermediate leap year wheel 39 with 39 teeth, the intermediate leap year wheel 39 meshes with a leap year display wheel 40 which likewise comprises 39 teeth, the leap year display wheel 40 is mounted coaxially with the actuating gear 36 for the month display, so that the indicators of the months and leap years, in particular the hands pointing to concentric rings arranged on the dial, can be set in rotation about the same hand-motion mechanism in order to improve the legibility for the user. It will be understood by those skilled in the art that, for the elements forming the wheel train described in fig. 2A and 2B, i.e. (elements 33-36) for the month display, (elements 37-40) for the leap year display and (elements 33, 41, 42, 43) for the positioning control of the month program gear 43, the number of teeth cited is given as an example, within the framework shown with sufficient meshing efficiency to achieve the preferred variant of the invention, but should in no way be considered limiting.

Fig. 2B clearly shows the leap year index gear 46 mounted on the month program gear 43. The leap year indexing gear 46 is integral with a maltese cross 46 ', which maltese cross 46 ' meshes at level F with a leap year indexing finger 47 ' provided on a fixed wheel 47. On the 3 arms of the maltese cross are superimposed 3 teeth 461, 462 and 463, which engage on engagement level E to move the date from 28 to 29 days when the year is not a leap year.

The month program gear 43 must be synchronized with the displayed and indexed month values in order for the planetary gear to engage to perform the readjustment required at the end of the month. This is the reason why the control train, which according to the shown preferred embodiment is formed by the elements 15, 16, 32, 33, 41 and 42, enables a reverse action (retroaction) from the external day indexing tooth system 13' to the month program gear 43. The day indexing tooth system 13' of the day program wheel 13 performs at least 1/31 revolutions per day (i.e. an additional readjustment of one or more 1/31 revolutions required for months and february of 30 days is performed for a regular day of 1/31 and for the last day of months with less than 31 days) in order to index the month program gear 43 by 1/12 revolutions after the end of each month. According to the preferred variant shown, the indexing of the month program gear 43 takes place at the same time as the indexing of the gear 36 for actuating the month display, also by 1/12 revolutions, since the indexing of these two gears is effected by meshing with the same elements, namely the monthly indexing teeth 32.

According to a preferred embodiment of the described calendar mechanism, the control train of the month program wheel, made up of the elements referenced 15, 16, 32, 33, 41, 42, is formed by a first kinematic chain starting from the date indexing tooth system 13' of the date program wheel 13 via the intermediate date wheel 15 to the date gear 16, said date gear 16 forming the first element of the date display train (16-24), while a second kinematic chain, starting from the date gear 16 and the monthly indexing tooth 32, returns to the month program wheel via the monthly indexing gear 33 and the month control wheel 41 (both rotationally fixed to each other) and the month intermediate control wheel 42, which is arranged coaxially with the date program wheel 13 but rotationally independent of the date program wheel 13. The intermediate gears 15 and 42, i.e. the intermediate date wheel 15 and the intermediate month control wheel 42, are provided as a single intermediate wheel comprising two coaxial and rotationally independent wheels, in order to save the maximum amount of space on the board, for example for other movement modules. Said intermediate month control wheel 42 meshes with the month program wheel 43 at level G, while the intermediate date wheel 15 meshes with the date indexing tooth system 13' of the date program wheel 13 at level C. According to the preferred embodiment shown, said intermediate wheels (intermediate date wheel 15 and intermediate month control wheel 42) rotate in opposite directions of rotation to each other, since intermediate date wheel 15 directly meshes with date wheel 16 and therefore rotates in opposite direction to date wheel 16, whereas month intermediate control wheel 42 is driven by a transmission formed by monthly indexing finger 32 integral with date wheel 16 via gears 33 and 41 and therefore rotates in the same direction as date wheel 16.

The adjustment of the months is carried out by means of a manual actuator 48 provided on the housing 0. According to the preferred embodiment depicted in fig. 2A and 2B, the manual actuator 48 for adjusting the day of the week is a button that is continuously pressed at most 11 times to reach the desired month of the year. According to the described preferred embodiment, the manual actuator 48 is used not only for determining the month, but also for determining the year in a leap year cycle of 4 years, since there is no dedicated actuator for the adjustment of the year. In this case the maximum number of pulses would be 47 instead of 11. To overcome this drawback, in an alternative embodiment another manual actuator can be provided on the central part to act directly on the tooth system of the gear 38 for actuating the leap year display. In this case, however, it will be necessary to ensure that the tooth system of the actuating gear does not engage with the year indexing teeth 37 during the adjustment, i.e. preferably does not engage with the year indexing teeth 37 during the months 12 or 1, which imposes an additional limit on the moment at which the adjustment must be performed.

For the sake of clarity, the adjustment mechanism 49 is not shown in fig. 2B, said adjustment mechanism 49 allowing the pulses of the push-button to be transmitted to the month program gear 43. However, such mechanisms are known to those skilled in the art. Instead of a push button, a shaft may be used as the manual actuator 48, in which case the rotation of the shaft may drive the month program gear 43 to rotate in both directions together with a suitable mechanism for adjusting the months. However, according to the preferred embodiment shown, and with the proposed alternative, such month adjustments cannot be made when the monthly indexing tooth meshes with the monthly indexing gear 33, i.e. during the night from the last day of the current month to the first day of the next month. In fact, the engagement of the indexing tooth 32 will cause the rotation of the date gear 16, which will cause the same movement of the date program wheel 13, the engagement between the teeth 28, 29, 30, 31 of the date program wheel 13 and the indexing gear 12 at 20.00 and 24.00 will cause the rotation of the date meshing section 11 of the 24-hour wheel. This tends to transmit these indexing operations to hour wheel 1, which, as described previously, is not possible without impairing the normal functioning of the movement if the adjustment of the date takes place between 20.00 hours and 24.00 hours.

Fig. 3A and 3B show a sectional view and a plan view of a display mechanism for 24 hours and days of the week of a calendar mechanism according to a preferred modification of the present invention, respectively. Fig. 3A and 3B are enclosed by a housing 0 to indicate the position of the wheel train inside the watch. A button 10 for correcting the day of the week is provided at 9 o' clock on the watch case 0. In fig. 3A, an hour hand mechanism can be seen, on which an hour wheel 1, preferably comprising 35 teeth, is provided. The hour wheel 1 meshes with a 24-hour wheel 2 comprising twice the number of teeth. Said 24-hour wheel 2, which performs one complete revolution per day, is mounted so as to be rotationally fixed with a transmission wheel 3, said transmission wheel 3 being in mesh with a 24-hour display gear 4 comprising the same number of teeth (for example 46 teeth according to the preferred embodiment shown here). The 24-hour display gear wheel 4 is mounted coaxially with a day star wheel 7 having 7 arms, the star wheel 7 being driven at a rate of once a day on the meshing level shown later in fig. 4B by a pawl 6, the pawl 6 being coaxial with the 24-hour wheel 2. The coaxial arrangement of the 24-hour display gear 4 with respect to the day star wheel 7 makes these display parameters more legible, for example by means of concentric rings.

Fig. 4A is identical to fig. 3A, except for the additional component denoted 8, which shows the elastic indexing element of the day star wheel 7. Fig. 4B is a plan view of the index wheel train of the day star 7 at a meshing level lower than that of the transmission wheel 3 at the 24-hour display gear 4. The pin 5 integral with the 24-hour wheel drives a pawl 6, said pawl 6 engaging with the day star wheel 7 to rotate the day star wheel 7 and perform 1/7 revolutions per day. Meshing occurs over a segment between about 10 o 'clock and 11 o' clock on the 24 hour wheel 2 in fig. 4B, which means that in this configuration the daily indexing of the day occurs between about 2 o 'clock and 4 o' clock in the morning. The indexing of the day star wheel 7 by 1/7 revolutions is ensured precisely by the elastic indexing element 8 which positions itself between two teeth of the day star wheel 7, so that each indexing step corresponds to 1/7 revolutions.

The pawl 6 of the 24-hour wheel is preferably provided as a coaxial element with the 24-hour wheel 2, but is not completely fixed in rotation with respect to said 24-hour wheel 2, so that the adjustment of the day of the week can be made independently of the calendar mechanism and of the hour of the day. In fact, the arrangement of said pawl 6 on the meshing gear provides a degree of freedom in rotation between the first abutment 6 'and the second abutment 6 ", in which the pin 5 of the 24-hour wheel will rest against said first abutment 6' when the 24-hour wheel 2 is turned in the anticlockwise direction (i.e. when the hour wheel 1 is turned in the clockwise direction during normal functioning operation of the watch); whereas if the 24-hour wheel were turned in the opposite direction, the pin 5 of the 24-hour wheel would rest against said second abutment 6 ". The amplitude of this degree of freedom preferably corresponds to an angular sector of 20-30 degrees and is determined so that, for the embodiment shown in fig. 4B, it is possible to make the day star wheel 7 turn, for example, in the clockwise direction, without interfering with the normal operation of the hour wheel 1, even if the pawls 6 of the 24-hour wheel are in the engaged position with the teeth of the day star wheel 7, i.e. for the preferred embodiment described, in the sector of between about 10 o 'clock and 11 o' clock of the 24-hour wheel in fig. 4B, as described above. In the case where the pawl 6 of the 24-hour wheel is located between two consecutive teeth of the day star 7 at the moment of adjustment, it will simply be turned in the anticlockwise direction, without causing any resistance to the day star 7 before reaching the second abutment 6 ", and without affecting the operation of the 24-hour wheel 2. Thus, the normal operation of hour wheel 1 is fully protected during the adjustment operation, regardless of the hour at which this adjustment operation is performed. If this operation is carried out with the pawl 6 of the 24-hour wheel between two teeth of the day star wheel 7, the usual daily meshing will no longer occur, since the pawl 6 of the 24-hour wheel will then be located outside the usual meshing section between 10 o ' clock and 11 o ' clock, outside which said first abutment 6 ' will later be readjusted only by the pin 5.

The adjustment of the day of the week is performed by means of a manual actuator 10 provided on the housing 0. According to the preferred embodiment depicted in fig. 4A and 4B, the manual actuator 10 for adjusting the day of the week is a button that is pressed at most 6 times in succession to reach the desired date. For the sake of clarity, the adjustment mechanism 9 enabling the transmission of the pulses from the push-button to the day star-wheel 7 is not shown in fig. 4B; however, such mechanisms are known to those skilled in the art. According to the preferred embodiment shown, the day of the week can therefore only be adjusted in a single direction.

The fact that the adjustment of the day of the week never affects the movement of the 24-hour wheel 2 ensures independence not only of such adjustment with respect to the display of hours and minutes, but also with respect to the value of the month and the date in the month determined by the calendar mechanism according to the invention. In fact, the calendar mechanism is driven by the movement of the integral meshing section of the 24-hour wheel 2-as explained further below with reference to the drawings-which is never affected by the adjustment of the day of the week. The correction of the days of the week is therefore independent of the values of the date and month displayed according to the preferred embodiment of the calendar mechanism described in the present invention.

Fig. 5A and 5B show a cross-sectional view and a perspective view, respectively, of a preferred embodiment of the program wheel 100 and the date indexing gear 12 according to the present invention. The day indexing gear 12 is driven by a movement meshing on level a, while the different meshing levels 28, 29, 30 on meshing level B, D, E allow indexing readjustment to take place while the meshing level 31 on meshing level C performs a normal daily indexing operation, preferably between 23.00 hours and midnight. The meshing segments 28, 29, 30 and 31 respectively comprise a single tapered tooth according to the variant shown, and are superimposed on the teeth 28 ", 29", 30 "and 31" of the day indexing gear 12 on level a. The meshing levels F and G relate only to the program wheel 100 and enable the indexing of the leap year indexing gear 46 by means of the maltese cross 46' meshing on the pawl of the fixed wheel 47 and the indexing of each month of the program wheel 43 by means of 1/12 revolutions, respectively. According to the described embodiment, the engagement segment 29 is located on level B, the engagement segment 30 is located on level D and the engagement segment 28 is located on level E. This configuration of the meshing levels is advantageous so that the planet gears 128, 129, 130 can be positioned set back from the successive teeth of the external day indexing tooth system 13' of the day program wheel 13, as shown in fig. 5B.

The month program gear 43 is mounted coaxially and rotationally fixed with the program gear 45 for the months of february on meshing level B and the program gear 44 for the months of less than 31 days on meshing level D, so that no dedicated wheel train is required for each of these two indexed readjustments. Program gear 45 for the month of february comprises a single tooth 451, and program gear 44 for the months of less than 31 days comprises 5 teeth 441, 442, 443, 444 and 445, each tooth corresponding to february, april, june, september and 11 months, respectively. These teeth are located in the second, fourth, sixth, ninth and eleventh segments of the 12 corner segments corresponding to each month. The program gear 44 for months less than 31 days is thus set to a gear having 12 teeth over the segment corresponding to the months less than 31 days, of which 7 teeth will be omitted. Moreover, the teeth 441 of the month of february 441 and the teeth 451 of the month of february program wheel, corresponding to the program gears for months less than 31 days, are superposed and identical, so as to facilitate the assembly of the different program gears by simply checking the required centering, as well as to limit the machining costs due to the similarity of the shapes of the teeth for each indexed readjustment.

In fig. 5B three planet gears 128, 129, 130 can be seen, each planet gear having 8 teeth and having a rotation axis integral with the date program wheel 13. These planet gears 128, 129, 130 are all identical, their axes of rotation 128 ', 129 ', 130 ' being located between successive teeth of the day indexing tooth system 13 ' of the day program wheel 13, so that the tooth system of the meshing segments 28, 29, 30 is able to effectively drive the tooth system of the planet gears 128, 129, 130 in both directions and along an angular distance corresponding to 1/31 revolutions of the day program wheel 13, and said axes of rotation 128 ', 129 ', 130 ' also being located at equal distances from the centre of rotation of the day program wheel 13. The depth of the tips of the teeth relative to the indexing tooth system 13' is determined such that good engagement with the tooth system of each engagement segment 28, 29, 30 is achieved. This configuration of the axes of rotation 128 ', 129 ', 130 ' on the same circular arc is possible because the tooth systems of the program gear 44 for months of less than 31 days, the program gear 45 for the months of february and the leap year program wheel 46 are identical and overlap during the months of february of non-leap years. The planet gears 128, 129, 130 mesh with the tooth system of these gears which is rotationally fixed with respect to the month program gear 43, in order to perform an indexed readjustment at the end of the month. According to the described preferred embodiment, each of the planet gears 128, 129, 130 comprises 8 teeth to improve the meshing efficiency, such arrangement of the wheels between successive teeth of the planet gears for the months being possible only if the wheels 128 and 130 are located on either side of the date meshing level C (on which the meshing segment 31 of the date indexing gear 12 meshes directly with the external date indexing tooth system 13' each day), so that the tooth system of each planet gear 128, 129 and 130 can span the rotation axis of the adjacent gear. For example, in fig. 5B it can be seen that the tooth system of the planet gears 129 spans the rotational axes 128 'and 130' of the planet gears 128 and 130.

The program wheel 100 shown in fig. 5A and 5B is therefore intended for a perpetual calendar mechanism with a first indexing readjustment on meshing level B for indexing from day 29 to day 30 during the month of february by means of a toothed segment 29, said toothed segment 29 cooperating with a planetary gear 129 and with the indexing teeth 451 of the month of february to advance the date program wheel 13 by one tooth; the perpetual calendar mechanism also has a second indexing readjustment, by meshing at a second meshing level D, for indexing from day 30 to day 31 in months of less than 31 days by means of a toothed segment 30, said toothed segment 30 cooperating with a second planetary gear 130. The third indexing readjustment is not a year indexing operation, as it only occurs for the month of february, which contains only 28 days. This indexing operation occurs at the third meshing level E by means of the toothed segment 28, said toothed segment 28 cooperating with the third planetary gears 128. The date indexing tooth system 13' of the date program wheel 13 itself meshes on the fourth meshing level C.

The leap year program gear 46 of the shown program wheel, which contains three teeth 461, 462, 463, is integrated with a maltese cross 46 ', which maltese cross 46' is mounted to pivot on the month program wheel 43 and meshes with a pawl 47 for leap years on the meshing level F each year. To facilitate the assembly of the program wheel 100 and the machining of the meshing section of the corresponding day indexing gear 12, the leap year program gear teeth 461, 462, 463 are identical and overlap during the february months of the non-leap years above the teeth corresponding to the teeth 441 of the february months of the program gear for months of less than 31 days and the teeth 451 of the february program gear.

Thus, the illustrated program wheel 100 extends over a total of 6 meshing levels from B to G. However, it will be appreciated by those skilled in the art that the invention is equally applicable to almanac mechanisms by omitting meshing levels E and F for leap years.

Figure 6 shows a perspective view of a calendar mechanism according to a preferred embodiment of the invention shown by different previous views. Starting from the hour wheel 1 in the center of the figure, it is possible to see a train leading to the day program wheel 13 through the 24 hour wheel 2 and the day meshing sector 11 with 7 teeth meshing with the indexing gear 12, of which only the upper meshing level B is shown, said meshing level B having a planetary gear 129 movable about its rotation axis 129 ' and an indexing tooth 451 for the month of february, said rotation axis 129 ' being located slightly below the maltese cross and between the successive teeth 29 ' and 30 ' of the day indexing tooth system 13 '.

On the left side of the figure, the transmission wheel 3 of the 24-hour wheel (which is rotationally fixed with the 24-hour wheel 2) meshes with a 24-hour display gear 4, said 24-hour display gear 4 rotating around the same motion work as the days of the week star wheel 7 arranged on the lower level. However, the pawl 6 of the 24-hour gear wheel causing the day star 7 to rotate and the elastic indexing element 8 of the day star are also hidden in this figure.

During each engagement with one of the meshing sectors 28, 29, 30, 31 of the indexing gear 12 of the calendar mechanism (the teeth 28 ", 29", 30 "and 31" superimposed to said meshing sector on level a have also been given a reference numeral), the date program wheel 13 performs 1/31 revolutions. The date gear 16 is made to rotate by the same angle by the intermediate date wheel 15. The unit wheel 17 and the tens wheel 18 are visible above the date wheel 16, and it is clearly visible that the 4 long teeth of the tens wheel 18 are arranged at the position of the 9 th, 19 th, 29 th and 31 th teeth of said tens wheel 18, the 31 th tooth of the unit wheel 17 being hollowed out. The date display mechanism is not shown for clarity.

The whole of the train of wheels for the display of the date in the month is also not shown in fig. 6, since the various display disks and indexing elements (the reference numbers 20-24 can be seen in fig. 1C) and the monthly indexing tooth 32, coaxial with the date wheel and rotationally fixed, are hidden under the date wheel 16. However, it is possible to see a monthly indexing gear 33 which enables a month control wheel 41 (said monthly indexing gear 33 being rotationally fixed with said month control wheel 41) to drive in rotation a month program gear 43 through an intermediate month control wheel 42, and also meshing with the wheel train for the month display, the tooth system of said month program gear 43 being hardly visible below the tooth system of the date indexing portion 13' of the date wheel.

At the top of fig. 6, an intermediate monthly indexing wheel 35 can be seen, which meshes with an actuating gear 36 for the month display, hidden under the monthly indexing teeth 37, said actuating gear 36 being coaxial with the monthly indexing teeth 37 and rotationally fixed. The monthly indexing teeth 37 perform one full revolution a year and mesh with an actuation gear 38 for the leap year display, which actuation gear 38 is coaxial and rotationally fixed with an intermediate leap annual wheel 39, which intermediate leap annual wheel 39 meshes with a wheel 40 for the leap year display having the same number of teeth. The wheel 40 for the leap year display is arranged coaxially with the actuation gear for the display of the month, so as to provide better legibility for the user of the watch.

Fig. 7A shows two first indexed sequential operations of the perpetual calendar mechanism according to the preferred embodiment shown in the figures, on day 28 of the month of february in non-leap years. For such dates, the calendar mechanism must be readjusted by 3 date values, which is achieved by the engagement at each level E, B and D; the figure shows a first readjustment at level E at 20.00 and a second readjustment at level B at 21.00.

The upper part of the figure shows the position of the day index segment 11 and the different teeth 28 ", 29", 30 "and 31" on meshing level a that overlap with the meshing segments 28, 29, 30 and 31 on their respective meshing level E, B, D, C at 20.00 on day 28 of the month of february. At this time, the meshing segment 28 of the indexing gear 12, located below the teeth 28 "of the indexing gear meshing on level a, meshes, on level E, with a planetary gear 128, the planetary gear 128 being mounted so as to pivot about a rotation axis 128' integral with the day program wheel 13. According to the preferred embodiment shown, the axis of rotation 128 'of the pivoting retractable tooth 128 is located slightly below the blank between the successive teeth 28' and 29 'of the day indexing tooth system 13'. The planet gear 128 additionally meshes with the second tooth 462 of the leap year indexing gear 46, which leap year indexing gear 46 is integral with the maltese cross 46 ', which maltese cross 46 ' is indexed once a year by the fixed leap year indexing finger 47, which leap year indexing finger 47 is itself integral with the fixed wheel 47 '. According to the preferred embodiment shown, the fixed wheel 47' is coaxial with the month program wheel 43 and with the date program wheel 13.

As a result of the above arrangement and the cooperation of the tooth system of the planet gear 128 with the tooth 462 of the leap year indexing gear 46 and the tooth system of the meshing section 28, which preferably may comprise one or two teeth, the date program wheel 13 is driven for 1/31 revolutions, for example according to the view of fig. 7A, in the same direction of rotation S1 as the direction of rotation of the 24-hour wheel 2, here clockwise of the hands of the watch. The elastic indexing element 14 of the day program wheel enables the day indexing tooth system 13 'to be indexed by pitch by a precise 1/31 revolutions in the direction S1, said day indexing tooth system 13' then meshing on the day display train (see reference numerals 15-24 shown in the other figures).

A second illustration will be seen from the top of fig. 7A, following downwards the arrow S, which indicates the direction in which the last indexing sequence operation of the month of february is performed, which shows a section of the day program wheel 13 and the month program wheel 43 on the meshing level B on which the meshing segment 29 of the day indexing gear 12, superimposed on the tooth 29 "of the day indexing gear on the meshing level a, meshes with the pivoting retractable tooth 129 of the day program wheel 13, said pivoting retractable tooth 129 being mounted so as to pivot about the rotation axis 129' integral with the day program wheel 13. According to the preferred embodiment shown, the rotation axis 129 'of the planet gear 129 is located slightly below the blank between the consecutive teeth 29' and 30 'of the day indexing tooth system 13'. This sequential operation occurs at 21.00 when the 24-hour wheel 2 has advanced the date meshing section 11 of the 24-hour wheel by one tooth and caused the date indexing gear 12 to rotate 1/8 revolutions to mesh on the tooth 29 "after the tooth 28". Obviously, the indexing tooth 451 for the month of february on level B is identical to and superposed on the leap year indexing tooth 462 on the meshing level E previously shown at the top of fig. 7A, this arrangement enabling the day indexing gear 13' to rotate 1/31 turns in the same direction S1, as a result of the cooperation of the tooth system of the planet gear 129 with the tooth 451 for the indexed month of february and with the tooth system of the meshing segment 29, which preferably may comprise one or two teeth, and preferably has the same number of teeth as the meshing segment 28. The elastic indexing element 14 of the day program wheel enables the day indexing gear 13' to be indexed to rotate once again through exactly 1/31 revolutions in the direction S1. The direction of rotation S2, opposite to the direction of rotation S1 itself, corresponds to the direction of rotation of the month program gear 43, with respect to which month program gear 43 the program gear 45 for the months of february is rotationally fixed. However, according to the described preferred embodiment, the indexing of the month program gear 43 only takes place when going from the 31 st day of the current month to the 1 st day of the following month.

The third and final indexing readjustment which takes place on the meshing level D is shown in fig. 7B, which shows a cross-section of the date program wheel 13 and of the month program wheel 43 along the meshing level D, on which the meshing segment 30 of the date indexing gear 12, superimposed on the tooth 30 "on the meshing level a, meshes with the planetary gear 130 of the date program wheel 13, said planetary gear 130 being mounted so as to pivot about a rotation axis 130' integral with the date program wheel 13. According to the preferred embodiment shown, the rotation axis 130 'is located slightly below the blank between the consecutive teeth 30' and 31 'of the day indexing tooth system 13' and is on the same arc as the rotation axes 128 'and 130' with respect to the rotation centre of the day program wheel 13. This sequential operation occurs at 22.00 when the 24-hour wheel 2 has again advanced the date meshing section 11 of the 24-hour wheel by one tooth and caused the date indexing gear 12 to rotate 1/8 revolutions to mesh on the tooth 30 "following the tooth 29" on the date indexing gear 12. Similar to the previous illustration in fig. 7A on meshing levels B and E, on level D the indexing teeth 441 are identical to and overlap the teeth 462 and 451 respectively on levels E and B, this arrangement on level D enabling the day indexing gear 13' to be driven in the same direction S1 for one 1/31 revolutions, as a result of the cooperation of the tooth system of the planetary gear 130 with the indexing teeth 441 of the gear 44 for months less than 31 days (here for the month of february) and with the tooth system of the meshing segment 30, which may preferably comprise one or two teeth, and preferably with the same number of teeth as the other meshing segments 28 and 29. The other four teeth 442, 443, 444 and 445, identical to tooth 441, correspond respectively to indexing teeth for readjustments from day 30 to day 31 in april, june, september and undemony, all of which occur similarly from 22.00 to 23.00 of the last date of these months.

The elastic indexing element 14 of the day program wheel enables the day indexing gear 13' to be indexed again with pitch for this last indexing readjustment by a precise 1/31 revolutions in the direction of rotation S1. The direction of rotation S2, opposite to the direction of rotation S1 itself, corresponds to the direction of rotation of the month program gear 43, the program gear for the months less than 31 days being rotationally fixed with said month program gear 43, as with the wheel 45 for the months of february. However, according to the described preferred embodiment, the indexing of the month program gear 43 only takes place when going from the 31 st day of the current month to the 1 st day of the following month.

As can be seen in particular from the different illustrations of fig. 7A, all the planet gears 128, 129, 130 preferably have the same geometry, which on the one hand greatly simplifies the manufacture of the date program wheel 13, while also simplifying the manufacture of spare parts, which do not require any machining of special elements for the adjustment of the date in the month. The simple and uniform geometry of each planetary gear 128, 129, 130 together enables the use of indexing gears (wheel 45 for the months of february and wheel 44 for the months of less than 31 days) with the same uniform tooth system at each level (B, D, E) for indexing readjustment as described above. Thus, the complexity of the entire proposed calendar mechanism is greatly reduced compared to conventional mechanisms. The planet gears 128, 129, 130 preferably comprise 8 teeth and mesh with the meshing segments 28, 29, 30 at their respective meshing levels E, B, D. According to one illustrated preferred embodiment, the meshing segments 28, 29 and 30 each comprise only a single tooth, sufficiently tapered to mesh with the tooth system of each planet gear 128, 129, 130, and also superposed on the teeth 28 ", 29", 30 "of the day indexing gear 12. This solution enables to simplify the machining of the engagement segments 28, 29, 30. In order to increase the engagement reliability, in an alternative embodiment, a second tooth may be provided in each engagement section. In this case, the two teeth of the meshing sectors will be located on either side of, rather than exactly below, the corresponding teeth 28 ", 29", 30 "of the day indexing gear 12, even if the whole of said meshing sectors is located in a sufficiently superposed position with respect to the teeth 28", 29 "and 30" of the day indexing gear 12.

In fig. 7A and 7B, of the 31 teeth of the date program wheel 13, only the 1 st and 28 th to 30 th teeth of the date indexing tooth system 13 '(which are respectively given the reference numbers 1, 28', 29 ', 30') and the tooth 131 are marked, said tooth 131 cooperating in the example described with the meshing segment 31 superimposed on the tooth 31 ″ of the date indexing gear 12 in order to index from the 31 st day to the 1 st month of the next month when going from the 28 th day of the february of non-leap years to the 3 rd 1 st day. In the preferred embodiment shown, the toothed segment 31 differs from the other meshing segments dedicated to readjustment (reference numbers 28, 29, 30) in that said toothed segment 31 has exactly the same shape as the teeth 31 "of the day indexing gear 12 (said toothed segment 31 being superimposed on the teeth 31"), while the other meshing segments each have tapered teeth so as to mesh with planetary gears having a finer tooth structure.

The diagram at the bottom of fig. 7B shows the last indexed sequential operation of a month, which follows the three previous indexed readjustments for day 28 of february in non-leap years, but which also occurs at 23.00 hours to midnight on all other days in the year. It can be seen that the same arrow S for the last indexing of the month as in the preceding fig. 7A points downwards to indicate the direction in which the indexing sequence operation is performed.

This figure shows the day program wheel 13 at an engagement level C, which in the preferred embodiment shown, in particular in fig. 1A/B and 2A/B, is located just above level D, at which the engagement segment 31 of the day indexing gear 12 engages with the teeth 131 of the day indexing tooth system 13' of the day program wheel 13. This sequential operation occurs at 23.00 when the 24-hour wheel 2 has caused the date meshing section 11 of the 24-hour wheel to advance one tooth again with respect to the top illustration of fig. 7B and has caused the date indexing gear 12 to rotate 1/8 revolutions to mesh on the tooth 31 "following the tooth 30" on level a of the date indexing gear 12.

Once the day of the month has been indexed to 3 months 1 day at midnight, the meshing segment teeth 31 are no longer meshed with the day indexing gear 13' when the day indexing gear 12 has performed an additional 1/8 revolutions. The date indexing gear 12, which preferably comprises 8 teeth on level a meshing with the date meshing section 11, of which the teeth 28 ", 29", 30 "and 31" are superposed on the meshing sectors 29, 30 and 31 on the respective level E, B, D, C meshing with the date program gear 13, will continue to mesh with the remaining teeth of the meshing section 11 and this has no effect on the movement of the date program wheel 13. The day indexing tooth system 13' will therefore not be driven in rotation after this moment. However, the control train described above, and in particular based on fig. 2B (reference numerals 15, 16, 32, 33, 41, 42), will still index the month gear 43 by 1/12 revolutions in the direction S2 opposite to the direction S1 each time the 1 st day passes from day 31 to the next month. To ensure that the energy used for the movement during each month change is not too great, in an alternative embodiment the type of monthly indexing teeth associated with the month display and with the reverse action on the month program gear 43 may be separated. According to the proposed embodiment, these monthly indexing teeth are convergent, since the monthly indexing tooth, referenced 32, simultaneously causes the indexing of the actuation gear 36 for the month display and of the month program gear. In an alternative embodiment, it is possible to envisage that the second indexing tooth meshes, at level G, with the month control wheel 41 (which is not rotationally fixed with the monthly indexing gear 33), so that said tooth can be angularly moved forward by a value of a few days between the 10 th and 20 th days of the month, for example, so that the indexing of the month program gear does not take place simultaneously with the indexing of the display of the current month, so that no very large moment for the simultaneous indexing operation is required at the end of the month, while ensuring the proper positioning of the date program gear 43 when the retractable tooth must be brought into the operative position, i.e. for a sufficiently long time before the last few days of the month. Moreover, the day indexing gear 12, which has performed a complete revolution after meshing with the 7 teeth of the toothed meshing sector 11, will be held in position by the surface of the sector 11' without teeth (which prevents the day indexing gear 12 from rotating) visible in all the illustrations of fig. 7A and 7B, until the next meshing with said same toothed sector.

The reliability of the meshing proposed by the calendar mechanism according to the invention is improved compared to mechanisms that make use of complex cam surfaces and/or movements that have several translation members for retractable teeth. Moreover, the construction is simplified by using a planetary gear that is identical for each readjustment of the day of the month and by using several coaxial and rotationally fixed program gears having a similar tooth structure at the respective meshing level.

Furthermore, it is clear that neither the date indexing gear 12 nor the date program wheel 13 have long teeth, which simplifies the machining thereof. The toothed segments, which are preferably identical for readjustment, can be mounted and positioned modularly on the respective meshing level. Their depth and the number of teeth (doubling the number of teeth on each meshing segment 28, 29, 30 with respect to the corresponding superposed teeth 28 ", 29", 30 "on the meshing level a of the day indexing gear 12) enable good meshing reliability, while the angular interval between each meshing segment itself ensures a unit increment of the day program wheel 13.

It can be seen from the views of fig. 7A and 7B that readjustment of the missing dates at the end of the months of less than 31 days is carried out by the calendar mechanism according to the invention in turn hourly over a period of at most 4 hours (i.e. from 20.00 hours to 24.00 hours), first at each of the 3 readjustment meshing levels E, B, D and then at the regular day indexing level C, while the day indexing gear 12 is driven by the meshing section 11 of the 24-hour wheel. All the planet gears are driven by the same clockwork train, more precisely by the same component (i.e. the day indexing gear 12), so that no dedicated train for each correction is required, which simplifies the construction of the proposed calendar mechanism compared to conventional mechanisms. The number of teeth of the date indexing gear 12, which is fixed to 8 according to the selected preferred embodiment, has been determined to perform rotation around a sufficient angle to index the date program wheel 13 (on which the planetary gears 128, 129, 130 are mounted) by 1/31 revolutions, while having a suitable depth of mesh. Moreover, the fact that the day indexing gear 12 performs exactly one complete revolution per day enables a similar movement to be repeated by a day cycle starting from the same position. The fact that the meshing level B, D, E is separated from the meshing level C of the day indexing operation for all readjustment operations at the end of the month enables modular substitution, preferably by meshing level, for each component of the program wheel 100 and the day indexing gear 12. This possibility provided by the calendar mechanism according to the invention is very advantageous because meshing levels C will be used for example daily, while levels B will be used once a year, levels D5 times a year, levels E once a year in three of four years, not leap years.

The calendar mechanism achieves that the date display is always synchronised with respect to the movement, and in both directions, so that the hours' minutes (which are normally achieved by rotating a crown provided on the case 0) will be transmitted to the hour wheel 1 and subsequently to the calendar mechanism. This is advantageous during travel to a destination whose time zone lags the original location (e.g., the west coast of the united states lags europe by 9 hours). A user of a watch equipped with a calendar mechanism according to the invention only needs to adjust the hours of his/her watch to less than 9 hours, so that the date will be automatically adjusted backwards, for example from 3 months 1 to 28 or 29 days of february, without any special operation for the adjustment of the date in the month. The use of such a watch is simpler than a watch with a conventional date mechanism, for which no synchronism with the movement is provided during adjustment in the opposite operating direction.

Claims (10)

1. A program wheel apparatus (100) for a calendar mechanism, wherein the program wheel (100) comprises:

-a date programme wheel (13), said date programme wheel (13) being driven by a timepiece movement and actuating a train of wheels (16-24) for the display of the dates in the month, wherein said date programme wheel (13) is adapted to perform one complete revolution per month, and

-a month program gear (43) adapted to perform one complete revolution per year,

characterized in that said date program wheel (13) and month program wheel (43) are coaxially mounted;

said day program wheel (13) comprising a uniform day indexing tooth system (13 ') having 31 teeth, said day indexing tooth system (13 ') being indexed by one tooth by pitch per day by a drive train (1, 2, 11, 12) actuated by said timepiece movement, wherein said day indexing tooth system (13 ') additionally operates a control train (15, 16, 32, 33, 41, 42) to index said month program gear (43) by 1/12 revolutions per month; and the number of the first and second groups,

the program wheel comprises a plurality of planet gears (129, 130), wherein the rotation axes (129 ', 130') of the planet gears are integral with the date program wheel (13), and the planet gears (129, 130) mesh at the end of the month with the gear fixed in rotation with respect to the month program gear (43) for indexing readjustment.

2. Program wheel device for calendar mechanisms according to claim 1, characterized in that said month program gear (43) is mounted coaxially and rotationally fixed with respect to the program gear (45) for the months of february and with respect to the program gear (44) for the months of less than 31 days.

3. The program wheel device for calendar mechanisms according to claim 2, characterized in that the program gear (45) for the month of february comprises a single tooth (451), the program gear (44) for months less than 31 days comprising 5 teeth (441, 442, 443, 444, 445) corresponding to february, april, june, september and november, wherein the tooth (441) of the program gear for months less than 31 days corresponding to february is superposed and identical to the tooth (451) of the program gear for the month of february.

4. A program wheel device for a calendar mechanism according to claim 1, characterized in that the date display mechanism comprises a date wheel (16), the date wheel (16) overlapping or meeting the date program wheel (13).

5. A program wheel device for calendar mechanisms, according to claim 1, characterized in that the calendar mechanism is a perpetual calendar mechanism, a first planetary gear (129), a second planetary gear (130) and a third planetary gear (128) are mounted on the date program wheel (13), the first planetary gear (129) is meshed on a first meshing level (B) for indexing from 29 th to 30 th in the months of february, the second planetary gear (130) is meshed on a second meshing level (D) for indexing from 30 th to 31 th in months of less than 31 days, the third planetary gear (128) is meshed on a third meshing level (E) for indexing from 28 th to 29 th in the months of the year, wherein the day indexing tooth system (13') is meshed on a fourth meshing level (C).

6. Program wheel device for calendar mechanisms according to claim 5, characterized in that the month program gear (43) is mounted coaxially to a fixed wheel (47 ') equipped with a leap year pawl (47) and comprises a leap year program gear (46) with three teeth (461, 462, 463) integral with a maltese cross (46'), said maltese cross (46 ') being mounted so as to pivot on the month program gear (43), wherein the leap year program gear (46) acts on the third meshing level (E) of the date program wheel (13), the maltese cross (46') meshing with the leap year pawl (47) on a fifth meshing level (F) every year, wherein each of the teeth (461, 462, 463) of the leap year program gear in the months of non-leap years is superposed on the tooth (441) corresponding to february of the program gear for months less than 31 days and on the tooth (441) for february Over said teeth (451) of the program gear.

7. A program wheel device for calendar mechanisms according to claim 5, characterized in that the month program gear (43) meshes with an intermediate month control wheel (42) on a sixth meshing level (G) per month, the intermediate month control wheel (42) forming part of a control train (15, 16, 32, 33, 41, 42) driven by the day indexing tooth system (13').

8. A program wheel device for calendar mechanisms according to claim 5, characterized in that the rotation axes (128 ', 129 ', 130 ') of the planetary gears are located between two consecutive teeth of the date program wheel (13) and on the same circular arc with equal distance from the rotation centre of the date program wheel (13).

9. A program wheel arrangement for a calendar mechanism according to claim 5, characterized in that the first (129), second (130) and third planetary gear (128) are identical.

10. A calendar mechanism comprising a program wheel device according to any one of claims 5 to 9, wherein the calendar mechanism is a perpetual calendar mechanism, characterized in that the timepiece movement comprises a 24-hour wheel (2) fitted with a date meshing section (11), the date meshing section (11) having a plurality of teeth meshing with a date indexing gear (12) at a seventh meshing level (a), wherein the date indexing gear (12) performs at most one full revolution in 24 hours, the date indexing gear (12) additionally comprising a first meshing segment (29), a second meshing segment (30), a third meshing segment (28) and a fourth indexing segment (31), the first meshing segment (29) meshing with the first planetary gear (129) at a first meshing level (B) for indexing from day 29 to day 30 in the second month, the second meshing segment (30) meshes with the second planetary gear (130) on a second meshing level (D) for indexing from day 30 to day 31 in months of less than 31 days, the third meshing segment (28) meshes with the third planetary gear (128) on a third meshing level (E) for indexing from day 28 to day 29 in the february in leap years, the fourth indexing segment (31) meshes with the teeth (131) of the day indexing tooth system (13') on a fourth meshing level (C), wherein the first meshing level (B) and the second and third meshing levels (D, E) are located on either side of the fourth meshing level (C).