HK1170315B - Calendar display device and calendar watch - Google Patents

Description

Calendar display device and calendar watch

Technical Field

The invention relates to a calendar display device, in particular for a mechanical watch piece comprising a watch movement, comprising: a first disc (day disc) carrying a plurality of series of inscriptions representing seven days of the week; a second disc (date disc) bearing inscriptions representing the date of the month; a third disc (disk of months) carrying 12 inscriptions representing the months of the year; one of the day and day disks acts as a dial by being fixed, and the other as a rotary disk by being concentrically and rotatably arranged with respect to said dial, said dial comprising an aperture enabling the inscription of the current month on the disk of months rotatably mounted and driven by the watch movement of said watch piece, while the hands are concentrically and rotatably arranged with respect to said dial to indicate the days of the day and of the week simultaneously. The invention also relates to a watch piece comprising such a calendar display device.

Background

The watch piece comprising such a calendar display belongs to the category of watch pieces known as "complex timepieces" and allows the user to view the information relating to the number of days, dates and months, in particular the entire current month, with a glance at the dial of the watch piece. The documents DE25267 and US340,855 are typical examples of such devices. These devices offer the following significant advantages: it is very convenient to provide information which day of the week corresponds to which day of the whole month. However, these devices suffer from the following significant drawbacks due to the fact that the length of the month is generally not a multiple of the length 7 of the week: they require the user to manually intervene at the beginning of the month to readjust the inscription on the days scale with the inscription on the dates scale, otherwise the calendar display will no longer be correct.

In the field of date display and in general of displaying calendar data, mechanisms known to the person skilled in the art as "perpetual calendars" are also known. Such mechanisms are usually preprogrammed by using cams representing the length of the months and enable the display of days, dates, months and possibly years, for long periods, sometimes more than 100 years. In most cases, perpetual calendar mechanisms are used to display the aforementioned data by means of a plurality of individual apertures arranged in the dial of the watch piece. This is also the case of the first embodiment of the table described in document EP 1351104. Such a display shows only calendar data for a single day and thus the aforementioned advantages of providing an overall view of the entire month are not available. For this reason, the second embodiment of the watch described in document EP1351104 proposes a calendar display device of the type mentioned in the opening paragraph by combining it with a perpetual calendar mechanism, thereby increasing the advantage of the overall view of the calendar data over a whole month. Furthermore, the device described in this document offers the following advantages because it is equipped with a perpetual calendar mechanism: the inscription on the day scale is automatically readjusted at the end of each month using the inscription on the date scale.

However, through a detailed study of this document, the reader notes that these two advantages are obtained only by two technical features which are difficult to implement and technically complicated to design. In fact, the operation of the perpetual calendar according to EP1351104 is based on a programming wheel carrying retractable teeth, the movement of which is controlled by means of very complex kinematics arranged on the programming wheel. Furthermore, the kinematic chain of movements according to EP1351104 requires two drive trains which control, in a coordinated and separated manner, the rotation of the disk of months and of the date from the driving wheel with respect to a fixed dial indicating the days of the week.

Document EP1351105, which is the same as document EP1351104, describes the same device from another point of view and is particularly concerned with the following problems: calendar display devices of the type mentioned in the opening paragraph, although having the advantage of providing an overall view of calendar data on a given month, are not able to view the calendar of the next month until the evening of the last day of the current month. It is even stated in the introduction of this document that the design of such devices based on the type of mechanical watch movement would be difficult.

Document EP1351105 therefore differs from the design of the calendar display device of the type mentioned at the outset and proposes to separate the date disc into two distinct discs, each carrying about half the date inscription from 1 to 31. This document also proposes to rotate the two disks relative to each other by means of very complex kinematics as already mentioned above, according to the date to be displayed, so as to enable the user to view the calendar data over a period corresponding to approximately one month, whether it be the beginning or the end of the month. For example, in order to display the date at the beginning of the month, a first date disc bearing the dates from 1 to 15 is aligned with a second date disc bearing the dates from 16 to 31, so that the numbers from 1 to 31 are arranged in ascending order, and in order to display the dates close to the end of the month, the position of the first date disc bearing the dates from 1 to 15 is changed with respect to the second date disc bearing the dates from 16 to 31, so that the numbers from 1 to 15 follow the numbers from 16 to 31, in either case the whole assembly is suitable for a dial indicating the days of the week.

This brief explanation illustrates that the solutions of documents EP1351104 and EP1351105 are complex in their design, difficult to implement, expensive to manufacture and even partly remove the main benefits and aesthetic appeal of such devices due to the fact that two separate date disks are used, in order on the one hand to achieve automatic adjustment of the scales of days of the week and of the dates at the beginning of each month, and on the other hand to avoid that calendar display devices of the type mentioned at the beginning of the introduction do not allow extended viewing of the calendar data close to the end of the month.

Apart from the device according to the above-mentioned document, which however has the main drawbacks as explained above, the prior art does not appear to include a mechanism which makes it possible to provide, by means of a relatively simple device, the two aforementioned advantages in a calendar display device of the type mentioned in the opening paragraph, namely, on the one hand, the automatic marking of the scale of days and dates at the beginning of each month, and on the other hand, the possibility of viewing the calendar data at any time and even in a spread manner towards the end of the month. In view of the prior art known at present, there is thus a need to create a device that enables the use of equipment that is simpler in design, easier to produce and cheaper to manufacture to provide these advantages.

Disclosure of Invention

It is therefore an object of the present invention to overcome the drawbacks of the known calendar display devices and to achieve the aforementioned advantages, in particular to enable the production of a calendar display device that allows the automatic indexing of the days and dates at the beginning of each month and also the extended viewing of the calendar data at any time, including the end of the month, without excessively increasing the complexity, bulk and production costs of the device, while maintaining the main benefits and aesthetic appearance of the mechanism.

To this end, the invention proposes a calendar display device of the aforementioned type, in particular for a mechanical watch piece comprising a watch movement, characterized by a calendar display device for a watch piece comprising a watch movement, or a corresponding watch piece. In particular, the device according to the invention comprises a direct kinematic link between the disk of months and said rotary disk to enable automatic indexing between inscriptions on said rotary disk and inscriptions on the dial, based on the month displayed.

It is particularly advantageous to arrange the direct kinematic link between the disk of months and the rotary disk so that it has two separate components controlling said automatic indexing, in short, one for the february months of leap years and the other for all the other months and years.

It is thus possible to control the rotary disk, whether it be a disk of days or a disk of days, with a single gear train and directly by the disk of months, and thus to achieve automatic indexing by means of a device that is simpler in design and easy to implement and even manufacture.

The device preferably comprises a correction mechanism comprising means for advancing and retracting the disk of months to allow the months displayed on the dial to be modified.

The correction mechanism cooperates at least with a gear train driving the disk of months by the watch movement of said watch piece, and said device for advancing and retracting the disk of months advantageously comprises, on the one hand, a correction star fixed to a correction wheel meshing with said gear train, and, on the other hand, a first and a second correction lever operable by the pusher of the watch piece. Each actuation of these pushers thus causes 1/12 revolutions of the disk of months forward or backward, making it possible to vary the months displayed on the dial in a bidirectional manner and simultaneously cause, due to the above mentioned features, automatic indexing between the scales for the days and the dates of the months newly displayed on the dial.

As a result of these measures, a watch piece is provided which allows the user to have an overall view of the calendar data over the entire current month, the user being free to select the displayed month at any moment and to review the calendar data of another month in the manner of a diary by pressing the corresponding push member to advance or retract the displayed month. The device according to the invention makes it possible to implement these advantages by means of a simple and compact manner and to maintain the appearance of such a mechanism, in comparison with the mechanisms of the prior art.

In a particularly interesting variant of the mechanism, the second disc (date disc) forms a fixed dial, the first disc (day disc) being arranged as a ring rotatable around the dial. In a variant, a reverse arrangement is also possible. The third disc (disk of months) is generally arranged as a ring, which is concentrically and rotatably arranged below the dial. Thus, the device can be provided in a plurality of embodiments and is thus diversified in technical and aesthetic aspects.

Other features and corresponding advantages will become apparent from the description given below, which describes the invention in more detail.

Drawings

The figures show embodiments of the invention in a schematic and exemplary manner.

Fig. 1 is a schematic plan view of all displays on a dial plate of a calendar display device according to the present invention;

fig. 2a and 2b are perspective views of the device shown in fig. 1 from two different perspectives, with the dial formed by the date disc removed to show the underlying parts;

FIG. 3 is an enlarged perspective view of a portion of the device shown in FIG. 2, showing the gear train of the disk of months in greater detail;

FIG. 4 is an enlarged perspective view of a portion of the device shown in FIG. 2, showing in greater detail a first portion of a direct kinematic link between the disk of months and said rotating disk;

FIG. 5 is an enlarged plan view of a portion of the device shown in FIG. 2, showing in greater detail a second portion of the direct kinematic link between the disk of months and said rotating disk;

fig. 6a and 6b are schematic plan views illustrating the operation of the second part of the direct kinematic link during a normal year;

figures 7a and 7b are schematic plan views illustrating the operation of the second part of the direct kinematic link during leap years;

8a, 8b and 8c are schematic plan views illustrating in more detail the operation of the second part of the direct kinematic link with respect to its cooperation with the pins of the disk of months and the respective four-tooth stars of the corresponding jumper of the kinematic link, some parts of which are shown transparent to facilitate understanding;

FIG. 9 is an enlarged schematic plan view of a portion of the correction mechanism showing the first and second correction rods in greater detail;

10a, 10b, 10c and 10d are schematic plan views illustrating in greater detail the different stages of operation of the correction mechanism during operation of advancing by one month;

fig. 11a, 11b, 11c and 11d are schematic top views showing in greater detail the different stages of operation of the correction mechanism during operation of the backward one month.

Detailed Description

The invention will now be described in detail with reference to the accompanying drawings, which show by way of example one embodiment of a calendar display device according to the invention.

As schematically shown in fig. 1, the calendar display device according to the invention will be integrated into a mechanical watch piece comprising a traditional watch movement and belonging to the category of mechanisms allowing the user to view calendar data over a given month. In particular, such a device enables the date of the month to be matched to the number of days of the week.

To this end, the device according to the invention comprises the traditional components of such a device, namely a first disk 1 (day disk), which first disk 1 carries a plurality of series of inscriptions representing seven days of the week; and a second disc 2 (date disc), the second disc 2 bearing inscriptions representing the dates of the months. One 1, 2 of the day 1 and date 2 discs acts as a dial and is rigidly mounted, while the other 2, 1 of the two discs acts as a rotary disc by being concentrically and rotatably arranged with respect to said dial.

Fig. 1 shows an example of a device according to the invention, in which the second disc 2 (date disc) forms a fixed dial. The first disc 1 (day disc) is arranged as a ring that can be turned around a date disc as a dial. Variations of this arrangement may be discussed in detail after the detailed description of this embodiment of the device. Additionally, the term "disc" is used generically herein, knowing that the corresponding components can be effectively arranged as discs but can also be annular. Also, it will be apparent to those skilled in the art that the inscription on the disc may take a number of different forms without altering the scope of the invention. For example, the date may effectively be represented by the numbers 1 to 31, or as shown in the figure, by a series of numbers from 1 to 31 with an odd number replaced by a symbol to save space, or alternatively by other symbols representing the date. The same applies to the day disc, whose symbols may comprise, for example, the initials of a series of days of the week, wherein the sunday can be marked in a particular way, as shown in fig. 1, or may comprise another series of symbols representing the days of the week.

Furthermore, the device according to the invention comprises a third disk 3 (disk of months), this third disk 3 preferably carrying 12 inscriptions representing the months of the year, the arrangement of these inscriptions being able to be modified in a substantially identical manner, similarly to the explanations made above. The disk of months is rotatably mounted underneath the dial and is normally driven by the watch movement of the watch piece at a rate of 1/12 revolutions per month. The dial comprises an aperture 2.1 through which aperture 2.1 the inscription corresponding to the displayed month on the disk of months 3 can be seen by the user. Likewise, and similarly to the explanations of the subject above, the disk of months 3 is preferably arranged as a ring, which is arranged concentrically and rotatably below said dial.

In the preferred embodiment of the device shown in the figures, the day ring or disc 1 carries on its periphery, over 35 equidistant angular sectors, a series of inscriptions five times representing seven days of the week, and thus 35 inscriptions. The date disc 2, i.e. in this embodiment the dial, also carries on its periphery inscriptions from 1 to 31, representing the dates of the month, on 31 equidistant angular sectors of the same angular size as the sectors on the first disc 1, as can be seen in particular in fig. 1. The aperture 2.1, through which the user can see the inscription of the current month on the third disc 3, is arranged on the periphery of the dial 2 between the first and last inscription for the date and occupies an angular dimension corresponding to four other equidistant angular sectors of the same angular dimension as the sectors on the day disc 1. This arrangement of the dial 2 is particularly advantageous for the user in terms of aesthetic appearance and in terms of clarity of presentation of information relating to calendar data. However, further variants are possible and will be briefly mentioned after the detailed description of a preferred embodiment of the calendar display device.

In order to indicate both the date and the number of days of the current week, the device according to the invention also comprises a hand 4 arranged concentrically and rotatably with respect to said dial. This hand 4 is typically advanced one day except between the last day of the month and the first day of the next month and indicates the current day and date. Mechanisms for driving the hands 4 and correcting the position of the hands 4 are known to the state of the art, they will not be described here and are also not shown in the figures.

The embodiment of the device shown in fig. 1 also comprises a display 5 of the current year type, indicating whether the currently displayed year is a leap year or a normal year. Alternatively or additionally, the device can also include a display of the number of current year copies, for example by having corresponding apertures. In addition, other information such as information about the current time, information about the phases of the moon by means of hour, minute and second hands can of course be integrated into the corresponding watch pieces, but is not shown in the figures so as not to complicate them. Their integration is conventional in nature and does not relate to the present invention.

Fig. 2 is a perspective view of the device shown in fig. 1, with the dial formed by the date disc 2 removed to show the parts arranged underneath. In this figure, the ring forming the day disc 1 and rotating around the dial 2, not shown, is clearly visible, as is the ring forming the disk of months 3 arranged below said dial. It can be seen that the disk of months 3 has two internal toothing 3.1, 3.2 on its inner periphery, the two internal toothings 3.1, 3.2 being arranged at two levels of different thickness. The first internal toothing 3.1 of the disk of months 3 cooperates with a gear train 6, which gear train 6 enables driving of this disk 3, and the structure and operation of which will be described in more detail below with reference to fig. 3.

In practice, the disk of months 3 is driven by the watch movement of said watch piece at the desired speed by means of the gear train 6. Since the other moving parts of the watch movement can be entirely conventional, fig. 3 shows only said gear train 6 from a drive finger 6.1, which drive finger 6.1 is driven by said watch movement to perform one full turn per month in the embodiment shown. The drive finger 6.1 thus once a month drives a first intermediate transmission wheel 6.2 which meshes with a cam 6.3 carrying a month cam 6.4, the function of which month cam 6.4 will become clearer later. The cam 6.3 drives a second intermediate transmission wheel 6.5 fixed to a third intermediate transmission wheel 6.6. The third intermediate transmission wheel 6.6 meshes with a transmission pinion 6.7 carrying a transmission wheel 6.8, which transmission wheel 6.8 meshes with the first internal toothing 3.1 of the disk of months 3, so that said disk of months rotates 1/12 revolutions per month. The ratios of the teeth of the different wheels to pinions can be chosen, for example, so that the first intermediate transmission wheel 6.2 is provided with a toothing of 12 teeth, the cam 6.3 with 48 teeth, the second intermediate transmission wheel 6.5 and the third intermediate transmission wheel 6.6 with 10 and 30 teeth, respectively, and the transmission pinion 6.7 and the transmission wheel 6.8 with 10 and 40 teeth, respectively, which achieves the aforementioned result compared to 144 teeth on said first internal toothing 3.1 of the disk of months 3.

In addition, it should be noted that the gear train 6 and its respective components described above are preferred embodiments, but they can have any structure that enables a suitable drive of the disk of months 3 to be obtained, the invention not actually being in this component of the device. The aforementioned ratio can of course be chosen differently, in particular for example the disk of months 3 will have 24 inscriptions instead of 12, and should therefore be driven at a rate of 1/24 revolutions per month.

With reference to fig. 2, it is noted that, in contrast to the mechanisms of the prior art, the device according to the invention comprises, in the case of the disk of days 1 shown, a direct kinematic link 7, 8 between the disk of months 3 and the rotating disk 1, 2. This direct kinematic link 7, 8 enables automatic calibration between the inscriptions on said rotary disk 1, 2 and the inscriptions on the dial 2, 1, and thus between the days and the dates of the week, to be obtained on the basis of the displayed month. As can be seen in fig. 2, a part of said direct kinematic link 7, 8 cooperates with said second internal toothing 3.2 of the disk of months 3.

For a more detailed description of the structure and operation of this direct kinematic link 7, 8 between the disk of months 3 and said rotary disk 1, 2, reference is first made to fig. 2, which should be noted first of all to include two separate portions 7, 8 having separate functions which will become clearer after reading the following explanations.

The first portion 7 of said direct kinematic link, shown in greater detail by the enlarged perspective view in fig. 4, comprises a first connecting pinion 7.1 able to mesh with said second internal toothing 3.2 of the disk of months 3. Said first connecting pinion 7.1 is connected to a first intermediate connecting wheel 7.2 driving a second intermediate connecting wheel 7.3, which second intermediate connecting wheel 7.3 carries a second connecting pinion 7.4, which second connecting pinion 7.4 in turn meshes with the internal toothing 1.1 of the rotary disk 1, 2 and thus with the day disk 1 in the case shown in the figure. Thus in the example of the disk of days 1 shown, the rotation of the disk of months 3 will automatically cause the rotation of the rotary disk 1, 2 with respect to the dial 2, 1, except for the month of february, which will become clearer from the following description.

As can be seen in fig. 2, said second internal tooth 3.2 of the disk of months 3 comprises for this purpose 12 equidistant angular sectors, each sector comprising, in addition to the sector corresponding to the month of february, a succession of notches 3.2.1 and teeth 3.2.2 which allow the rotary disk 1, 2 to be advanced by the drive of the disk of months 3, so that the indexing between the inscriptions on said rotary disk 1, 2 and the inscriptions on said dial 2, 1 is performed automatically on the basis of the month displayed.

The operation of this first part 7 of the direct kinematic link and its cooperation with the disk of months 3, respectively with its second internal toothing 3.2, will be easily understood if recall that the mechanism performs automatic indexing to adjust the information on the rotary disk 1, 2 with respect to the information on the dial 2, 1, knowing that the length of the months is generally not a multiple of the length 7 of the week. As a result, it is thus necessary to adjust the rotary discs 1, 2 by rotating the rotary discs 1, 2 relative to the fixed dial 2, 1 when the month display changes, so that the number of days correctly matches the date of the new month to be displayed. As can be seen from fig. 1, it is thus possible for the preferred embodiment shown in the figures to rotate the day disc 1 by an angle corresponding to the 4 equidistant angular sectors of the first disc 1, more particularly in the clockwise direction, once a month of 31 days has lapsed. Alternatively, it is also possible to rotate the day disc 1 in a counter-clockwise direction, in which case it is rotated by an angle corresponding to 3 equidistant angular sectors. Once a month of 30, 29 or 28 days has lapsed, the disc must therefore perform a rotation in the clockwise direction corresponding to 3, 2 or 1 equidistant angular sectors, respectively, or a rotation in the anticlockwise direction corresponding to 2, 1 or 0 sectors, respectively, i.e. no rotation in the latter case, to allow correct adjustment between the information of the rotating disc 1, 2 and the information of the dial 2, 1.

Given that the rotation in the counter-clockwise direction requires a shorter path to be performed by the rotating disc 1 compared to the rotation in the clockwise direction and thus has a more advantageous performance in terms of energy consumption, the first solution of regulation by rotation in the counter-clockwise direction is preferred and shown in the figures. However, it is also possible for a person skilled in the art, in view of the technical teaching of the present description, to implement a second solution of adjustment by rotation in a clockwise direction. In order to implement a first solution of anticlockwise rotation of the rotary disk 1, 2 during the readjustment, the 12 equidistant angular sectors of said second inner toothing 3.2 of the disk of months 3 are arranged to cause a rotation of 3, 2, 1 or 0 steps of the rotary disk 1, 2 at the end of the month with 31, 30, 29 or 28 days, respectively, by means of the moving part of the first portion 7 of the direct kinematic link described above, one step corresponding to the angular distance of one of said equidistant angular sectors of the first disk 1. Given that only in the months of february in leap years have 29 days and that no adjustment is required for the months of february in normal years having 28 days, the 12 equidistant angular sectors of said second inner toothing 3.2 of the disk of months 3, except for the sector corresponding to the months of february, have successive notches 3.2.1 and teeth 3.2.2 which are able to allow the rotary disk 1, 2 to follow the driving of the disk of months 3 through the gear train 6 and by means of the first part 7 of the above-mentioned direct kinematic link, by a corresponding number of steps. The sector of said second inner toothing 3.2 of the month disc 3 corresponding to the months of 31 days thus comprises three notches 3.2.1 and two teeth 3.2.2, the sector of said second inner toothing 3.2 of the month disc 3 corresponding to the months of 30 days thus comprises two notches 3.2.1 and one tooth 3.2.2, whereas the sector of said second inner toothing 3.2 of the month disc 3 corresponding to the months of february has no notches or teeth. It should also be noted that, according to the arrangement of the first part 7 of the direct kinematic link on the inner periphery of the disk of months 3, the 12 equidistant angular sectors of said second inner toothing 3.2 of the disk of months 3 do not necessarily have to be aligned with the corresponding inscriptions on the upper surface of the disk of months 3, as is the case in fig. 2.

In order to ensure the desired driving of the rotary discs 1, 2 corresponding to the above described arrangement of the second toothing 3.2 of the disk of months 3, the first connecting pinion 7.1 and the second connecting pinion 7.4 of the first part 7 of the direct kinematic link may for example have 6 and 9 teeth, respectively, whereas said first intermediate connecting wheel 7.2 and said second intermediate connecting wheel 7.3 have a toothing of 20 and 10 teeth, respectively, the internal toothing 1.1 of the rotary disc having 105 teeth, which 105 teeth correspond to 3 teeth located on each of the 35 equidistant angular sectors shown in fig. 2. It is clear to the person skilled in the art that these teeth and the corresponding reduction ratios can be modified as long as the rotary discs 1, 2 are driven as described above.

The above explanation explains that in the example of the disk of days 1 shown, the rotation of the disk of months 3 caused by the watch movement of the watch piece at the end of each month automatically causes, in addition to the months of february, the rotation of the rotary disk 1, 2 with respect to the dial 2, 1, so that the inscriptions on the rotary disk 1, 2 are again correctly adjusted with respect to the inscriptions on the dial 2, 1.

With regard to said first part 7 of the direct kinematic link, it is further noted that it further comprises a disconnecting device 7.5, preferably a latch release mechanism. These disconnecting devices 7.5 are, for example, arranged between the first connecting pinion 7.1 and the first intermediate connecting wheel 7.2, as can be seen in fig. 4, and enable the rotating discs 1, 2 to be driven independently of said first portion 7 of the direct kinematic link. In particular, they allow the rotation of the rotary disks 1, 2 independently of the rotation of the first connecting pinion 7.1, the teeth of this first connecting pinion 7.1 locking their rotation when they slide on the second toothing 3.2 of the disk of months 3 over an equidistant angular sector corresponding to the month of february, assuming this sector is smooth. The function of these disconnection devices 7.5 will become clearer in the following description.

With reference to fig. 5, the description will now focus on the second part 8 of the direct kinematic link, which is also shown in fig. 2. Said second portion 8 of said direct kinematic link comprises a four-tooth star 8.1 able to cooperate with a pin 3.3 fixed on the disk of months 3. The star 8.1 is fixed to a first intermediate wheel 8.2 which meshes with a second intermediate wheel 8.3, which second intermediate wheel 8.3 is fixed to an actuating finger 8.4. The actuating fingers can mesh with the inner toothing 1.1 of the rotary disk 1, 2, so that the rotary disk 1, 2 advances one step after each four actuation of the star 8.1 by the disk of months 3. As can be seen from the enlarged plan view in fig. 5, the first and second intermediate wheels 8.2, 8.3 may each have 12 teeth for this purpose. Other options are of course available to the person skilled in the art, but the number of teeth on these pinions 8.2, 8.3 and on the star 8.1 must be a multiple of 4, so that the four-tooth star 8.1 and the actuation finger 8.4 perform a quarter of a turn after each actuation.

The operation of said second part 8 of the direct kinematic link is easily understood by means of figures 6a and 6b and respectively 7a and 7b, which show in schematic plan views the operating steps of the second part of the device during a normal year and during a leap year, respectively. In fact, the above description has explained that the automatic indexing between the rotary disc 1, 2 and the dial 2, 1 is performed by the first portion 7 of the direct kinematic link for months having 31 or 30 days, and that this automatic indexing is not necessary for the months of february in the normal year, which are 7 in length, i.e. a multiple of the days of the week, at least as far as the preferred solution is adjusted by rotation in the anticlockwise direction. During normal operation of the device or of a watch equipped with the device, the second part 8 of the direct kinematic link only effectively acts at the end of the month february in leap years, with the 29-day months and the only case that the rotary disc 1, 2 needs to be adjusted one step as described above.

The pins 3.3 fixed on the disk of months 3 advance each month by an angular distance corresponding to one of the 12 equidistant angular sectors on the disk of months 3 when the disk of months 3 is driven by the gear train 6. During normal years and as shown schematically in fig. 6a and 6b, this pin 3.3 approaches the second portion 8 of the direct kinematic link at the end of the month of february. At this moment, when the disk of months 3 is driven to move the display from the month of february to the month of march, the pin 3.3 advances along the path indicated by the arrow in fig. 6a and cooperates with the teeth of the four-tooth star 8.1, causing this four-tooth star 8.1 to rotate a quarter of a turn in the direction of the arrow indicated in fig. 6 a. By means of the first and second intermediate wheels 8.2, 8.3, this results in a quarter turn of the actuation finger 8.4 in the direction of the arrow indicated in fig. 6a after each actuation of the four-tooth star 8.1, i.e. once a year during normal operation of the watch piece equipped with the respective device. Fig. 6b shows the position of the components after a quarter turn during the first year of operation. As is clearly visible in fig. 6a and 6b, the actuation finger 8.4 rotates freely during the first, second and third years of operation, thereby causing no alteration of the position of the rotary disk 1, 2, known for the years for which the month has 28 days, thereby requiring no adjustment.

After having been rotated three quarters of a turn during operation for the first three normal years, the parts are in the position as shown in fig. 7 a. When the disk of months 3 is driven during the fourth year (hence the leap year) through the gear train 6 to move the display from february to march, the pin 3.3 cooperates again with the teeth of the four-tooth star 8.1 and causes this four-tooth star 8.1 to rotate a quarter of a turn, so that the drive finger 8.4 rotates a quarter of a turn again and completes its rotation for one full turn in four years. This time without free rotation, the drive finger 8.4 meshes with the tooth 1.1 of the rotary disk 1 and drives said rotary disk through three teeth in the example of a tooth described above, i.e. through an angular distance corresponding to one step or in particular to one of the 35 equidistant angular sectors of the rotary disks 1, 2. This adjustment can be independent of the first part 7 of the direct kinematic link due to the above mentioned disconnecting device 7.5. In particular, these devices make it possible to decouple the rotation of the rotary disk 1, 2 from the pinion 7.1 at the end of the month of february in leap years, this pinion 7.1 remaining stationary in this case, since it is locked by its teeth sliding on the smooth sectors of the disk of months 3.

The inscriptions on the rotary disks 1, 2 and on the dials 2, 1 are thus also automatically calibrated for the month of february in leap years. It is hereby noted that the device described above (respectively the watch piece equipped with the device according to the invention) makes it possible to provide the user with a fully automatic calibration between the inscriptions on said rotary disk 1, 2 and the inscriptions on the dial 2, 1, based on the displayed month. Due to the two parts 7, 8 of the direct kinematic link, which is the case for normal years and for leap years, the device thus effectively forms a perpetual calendar mechanism. Moreover, these advantages are achieved by means of a mechanical device which is relatively easy in design and easy to produce, in particular using only a single drive train between the movement of the watch piece and the disk of months 3, the rotary disk 1, 2 then being controlled only by the disk of months.

It is further noted that, as far as the second part 8 of the direct kinematic link is concerned, at least one of said intermediate wheels 8.2, 8.3 comprises a toothed portion 8.2.1 able to cooperate with a jumper 8.5. The jumper keeps the four-tooth star 8.1 in its rest position, which is important during the above-mentioned operation to avoid unintentional rotation of the rotary discs 1, 2. Furthermore, said at least one of said intermediate wheels 8.2, 8.3 is arranged so that, after actuation of star 8.1 by said pin 3.3 fixed on the disk of months 3, jumper 8.5 repositions said intermediate wheel 8.2, 8.3 with which it cooperates in a position such that the tooth 8.1.1, 8.1.2 of the four-tooth star 8.1 oriented towards the disk of months 3 is always located in the path of said pin 3.3, irrespective of the direction of rotation of the disk of months.

This is achieved due to the fact that: the position of the teeth of the at least one intermediate wheel 8.2, 8.3 and of the jumper 8.5 is arranged such that after actuation of the four-tooth star 8.1 by the pin 3.3, i.e. after a quarter turn of the star 8.1, the jumper 8.5 does not jump to the position of the last tooth of the corresponding intermediate wheel, but repositions the intermediate wheel (respectively the four-tooth star 8.1) backwards by a small angular distance. The jumper 8.5 thus resets the four-tooth star 8.1 into the rest position, in which the pin 3.3 in any case will actuate one of the teeth of the star 8.1, irrespective of whether the pin 3.3 (respectively the disk of months 3) rotates in the clockwise direction or in the anticlockwise direction. The different stages of this cooperation between the toothing 8.2.1 of the corresponding intermediate wheel 8.2, 8.3 and the jumper 8.5 are schematically shown in fig. 8a to 8 c. In fig. 8a, the pin 3.3 has driven the four-tooth star 8.1 a quarter turn, but has not yet disengaged from the last tooth of the star 8.1 on its path, knowing that the disk of months 3 has not moved a full step. In fig. 8b, the pin 3.3 is disengaged from said last tooth and the disk of months 3 continues its rotation. The circled part of fig. 8b shows that the position of the jumper 8.5 has not moved to the other side of the tooth with which the jumper 8.5 is engaged during this stage of motion. Finally, in fig. 8c, a rest position can be seen into which the jumper 8.5, in cooperation with the tooth it is resting on in fig. 8b, resets the four-tooth star 8.1, the direction of movement of fig. 8a to 8c being indicated by the arrow. This rest position corresponds to the position visible in fig. 8 a. In this position, the teeth 8.1.1, 8.1.2 of the four-tooth star 8.1 oriented towards the disk of months 3 are always arranged in the path of said pin 3.3 irrespective of the direction of rotation of the disk of months. The purpose of this feature will become more apparent from the description below.

In fact, the calendar display device according to the invention preferably also comprises a correction mechanism 9, 10, the structure and operation of which will be described hereinafter with reference to fig. 9, 10a to 10d and 11a to 11 d.

In its preferred embodiment, this correction mechanism 9, 10 cooperates with said gear train 6 driving the disk of months 3 starting from the watch movement of said watch piece. In particular, said mechanism 9, 10 comprises means for advancing and retracting the disk of months 3, so as to vary the months displayed on the dial 2, 1 in a bidirectional manner. Preferably, and as schematically shown in fig. 9, said means for advancing and retracting the disk of months 3 comprise, on the one hand, a correction star 9.1 fixed to a correction wheel 9.2, this correction wheel 9.2 being in mesh with said gear train 6 driving the disk of months 3. For example, the correction star 9.1 can have 12 teeth and the correction wheel 9.2 can have a 36-tooth toothing, which meshes with the drive pinion 6.7 mentioned in the description of the gear train 6. Of course, a person skilled in the art is able to choose another arrangement of these moving parts and/or another reduction ratio based on the arrangement of the wheels involved. On the other hand, these devices for advancing and retracting the disk of months 3 comprise a first correction lever 10.1 and a second correction lever 10.2 which can be actuated by pressure and which, when actuated, cause the correction star 9.1 to rotate in a clockwise direction and in a counterclockwise direction respectively, thus driving the disk of months 3 forward or backward 1/12 turns respectively after each actuation of one of said levers 10.1, 10.2. In particular, the actuation of the first correction lever 10.1 and of the second correction lever 10.2 causes, by means of the intermediate control 10.3, the lifting of the main control 10.4 cooperating with said month cam 6.4, said month cam 6.4 being arranged on the cam 6.4 in the gear train 6 driving the month disc 3. Thereby releasing the wheel train of said gear train 6 during the correction of the displayed month, while when neither lever 10.1, 10.2 is actuated, the gear train 6 and the disk of months 3 are secured by a corresponding jumper not shown in the figures. By actuating one of said levers 10.1, 10.2, the user is thus able to modify the months displayed on the dial 2.1 in a bidirectional manner, in order to consult in a diary manner the calendar data of the month that he desires to display.

The sequence of fig. 10a, 10b, 10c and 10d shows schematic plan views illustrating in more detail the different phases of operation of the correction mechanism 9, 10 during operation of the advancing month. Fig. 10a shows the rest position or start position of the components forming part of the correction mechanism 9, 10. Fig. 10b is a schematic view showing the position of the components when the user starts to press the correction lever 10.1 so that it pivots about its axis 10.1.1 and moves its free end 10.1.2. The free end pushes the intermediate control part 10.3, for example by means of a first pin 10.3.2 fixed to the intermediate control part 10.3, to pivot the latter about its axis 10.3.1. This pivoting results in a lifting of said main control 10.4, for example by means of a further pin 10.4.3 fixed to the main control 10.4, said main control 10.4 pivoting about its axis 10.4.1 and normally being biased against the month cam 6.4. In practice, this control 10.4 forms part of a perpetual calendar mechanism, which also comprises an end of month cam, a pawl, said main control 10.4 and a month cam 6.4, which mechanism is known not to be the subject of the present invention and to be known to a person skilled in the art, and which mechanism is not described in detail here. The main control 10.4 cooperates with a month cam 6.4 arranged in a cam 6.3, which cam 6.3 is located in the gear train 6 driving the month disc 3, so as to control the length of the months in a manner known in the art on the basis of the depth of the cut in the month cam 6.4. Said lifting of said main control 10.4 causes the release of the month cam 6.4, the finger 10.4.2 of the main control 10.4 coming out of one of the notches in the month cam 6.4, as can be seen in fig. 10 b. Fig. 10c then shows that once the gear train 6 is released and the user continues to press the first correction lever 10.1, the free end 10.1.2 of the first lever 10.1 continues to advance until it engages with the toothing of the correction star 9.1 to turn 1/12 turns the latter in the anticlockwise direction at the end of its stroke, as symbolically shown by the arrow in fig. 10 c. This actuation of the correction star 9.1 causes, by means of the correction wheel 9.2 and the gear train 6 visible in fig. 9, an advancement 1/12 turns through the disk of months 3 and thus a change in the display of the months, and an automatic adjustment between the inscriptions on the rotary disk 1, 2 and those on the dial 2, 1, and thus between the number of days and the date displayed, so that they correspond to the month currently displayed, by means of the direct kinematic link 7, 8. Finally, fig. 10d shows the position of the different components once the user no longer presses the first correction lever 10.1, the correction mechanism having established its starting position shown in fig. 10 a.

Similarly, the sequence of fig. 11a, 11b, 11c and 11d shows schematic plan views illustrating in more detail the different phases of operation of the correction mechanism 9, 10 during operation of the backward one month. Again, fig. 11a shows the rest or starting position of the components forming part of the correction mechanism 9, 10. Figure 11b is a schematic view showing the position of the components as the user begins to urge the second corrector lever 10.2 causing it to pivot about its axis 10.2.1 and causing its free end 10.2.2 to move. The free end pushes the intermediate control 10.3, for example by means of a second pin 10.3.3 fixed to the intermediate control 10.3, to pivot the intermediate control about its axis 10.3.1. Again, this pivoting causes the main control 10.4 to lift by causing the main control 10.4 to pivot about its axis 10.4.1, by means of a pin 10.4.3 fixed to the main control 10.4. As in the case of the advance by one month, the lifting of said control 10.4 causes the release of the month cam 6.4 due to the fact that the finger 10.4.2 of the main control 10.4 leaves one of the notches located in the month cam 6.4. Fig. 11c then shows that once the gear train 6 is released and the user continues to force the second correction lever 10.2, the free end 10.2.2 of the lever 10.2 continues to advance until it engages with the toothing of the correction star 9.1, so that at the end of its stroke the correction star 9.1 now turns 1/12 turns in the clockwise direction. Again, the direction of movement is symbolically indicated by the arrow in fig. 11 c. This actuation of the correction star 9.1 causes, by means of the correction wheel 9.2 and the gear train 6 visible in fig. 9, a backward 1/12-turn through the disk of months 3 and thus a change in the display of the months, and causes, by means of the direct kinematic link 7, 8, an automatic adjustment between the inscriptions on the rotary disk 1, 2 and those on the dial 2, 1, and thus between the days and dates displayed, so that they correspond to the months currently displayed. Finally, fig. 11d shows the position of the different components once the user no longer presses the second correction lever 10.2, the correction mechanism having established its starting position shown in fig. 11 a.

It is still to be added that the different components, such as the levers 10.1, 10.2 and the controls 10.3, 10.4, are of course biased towards their rest positions, for example by means of respective springs, which biasing devices are not shown in the figures for the sake of clarity. Likewise, it should be noted that the main control 10.4 is of course also lifted by means of the month cam 6.4, not shown, during normal operation of the device, i.e. when the month disc 3 is advanced one step by the movement of the watch piece, instead of being corrected manually by the user by means of the correction lever.

Finally, it should be noted that in the context of the correction mechanisms 9, 10, the above-described solution relates to the following case: wherein the watch piece comprises only a single gear train 6 for controlling the disk of months 3 and the rotary disk 1, 2 by means of the watch movement of said watch piece, i.e. said device comprises a direct kinematic link 7, 8 between the disk of months 3 and said rotary disk 1, 2. Without this variant needing to be described in detail, it is clear to the person skilled in the art having the technical teaching of the present invention that, in order to control the disk of months 3 and the rotary disk 1, 2 by means of the watch movement of said watch piece, said gear train 6 can also be arranged to drive the rotary disk first, said direct kinematic link 7, 8 then driving the disk of months 3 by means of said rotary disk. This thus represents the reverse arrangement of the preferred embodiment discussed in detail above. In this case, the gear train 6 and the correction mechanisms 9, 10 described above must be adapted according to the explanations given above, which is within the scope of the person skilled in the art having the technical teaching. In particular, the correction mechanisms 9, 10 can act indirectly on the disk of months 3, for example only by means of the kinematic links 7, 8 in this case, instead of driving it directly by means of the gear train 6 as in the case described in detail above.

Likewise, it is also theoretically conceivable to replace the combination of the single gear train 6 of the disk of months 3 and of the rotary disk 1, 2 with the direct kinematic link 7, 8 by two separate gear trains controlling the disk of months 3 and the rotary disk 1, 2 separately starting from the watch movement of the watch piece. In this case, the correction mechanisms 9, 10 described above must be adapted similarly to the explanations given and will be arranged to cooperate simultaneously with said gear train 6 driving the disk of months 3 and with the second gear train driving the rotary disk 1, 2 by the watch movement of the watch piece. In this way, the device for advancing and retracting said mechanism 9, 10 simultaneously controls the disk of months 3 and the rotary disk 1, 2 by means of the gear train 6 driving the disk of months 3 and the second gear train driving the rotary disk 1, 2, to achieve automatic indexing between the inscriptions on said rotary disk 1, 2 and the inscriptions on the dial 2, 1, on the basis of the month displayed, similar to the preferred solution described in detail above. For example, the second drive train driving the rotary discs 1, 2 can be arranged as known in the art, while the cooperation between said second drive train and the means for advancing and retracting said mechanisms 9, 10 can be supplemented similarly by means corresponding to the gear train 6 for driving the disk of months 3. Without needing to describe in detail the variants of such correction mechanisms, the person skilled in the art with the present technical teaching will thus know how to adapt the mechanisms described in detail above within the scope of the preferred solution to the situation of an alternative solution that requires the connection of the correction rods 10.1, 10.2 to the two separate gear trains described above, respectively. For this reason, the alternative solution using two separate gear trains is clearly less advantageous, but remains a viable option.

It should of course also be noted that other equivalent embodiments of the calendar display device according to the invention, not shown in the figures, can be envisaged. For example, the position or arrangement of the rotary discs 1, 2 can be changed without the result in terms of overall operation or display needing to be significantly different from what has been disclosed above. All of these embodiments are actually within the scope of those skilled in the art having the technical teaching according to the present specification, and all of them cannot be described in detail herein.

For the sake of clarity to enumerate some examples in this example, it is also possible to arrange a fixed dial, still indicating the date, as a ring, while a rotating disc, indicating the number of days, will be arranged as the actual disc, which in this case rotates inside said ring. This arrangement represents in a way the reverse of the arrangement according to the preferred embodiment described in detail above. Another variant of modifying the preferred arrangement shown in fig. 1 consists in reversing the rotary disc from the dial, on the other hand, i.e. using the day disc 1 as a fixed dial and the date disc 2 as rotary disc. This arrangement can in principle be provided in two different variants, similar to the two cases mentioned above. On the one hand, the first disc 1 (day disc) may form a fixed dial, while the second disc 2 (day disc) is arranged as a ring that can rotate around the dial, and the third disc 3 (month disc) is arranged as a ring that is arranged concentrically and rotatably under the dial. On the other hand, the day disc 1 may also be arranged as a ring while forming a fixed dial, the day disc 2 forming a rotating disc being turned inside in this case. In the latter two cases, the aperture 2.1 is integrated into the day disc 1. The date disc 2 still requires 31 sectors, whereby it is preferable to have the day disc 1 equipped with a series of inscriptions four times seven days representative of the week on 28 equidistant angular sectors, while the apertures occupy three equidistant angular sectors of the same size. In this way, by correspondingly modifying the gear train and the toothing of the different parts meshed together, it is possible to obtain equivalent results with respect to the display, compared to the preferred embodiment. Other variations having, for example, six times the seven day legends representing the week on 42 equidistant angular sectors or modifying other features for that matter are also contemplated and within the scope of those skilled in the art having the present teachings.

Another variant, which also applies to the four arrangements mentioned above, consists in arranging the third disc 3 (disk of months) in a non-concentric manner underneath the dial. In fact, although it is preferred to arrange the disk of months 3 concentrically with respect to the disk of days 1 and the disk of days 2, this is not essential. Likewise, it is not necessary to arrange the disk of months 3 as a ring-it can also be formed as a solid disk. Moreover, in both cases, the gear train 6 can cooperate with the disk of months 3 by means of external toothing or disk axis instead of internal toothing.

It should also be noted that the invention also relates to a watch piece comprising a calendar display device according to the invention and, as mentioned above, driven by the basic movement of the watch piece. In particular, said first 10.1 and second 10.2 correction levers of the device can be actuated, in general, by means of corresponding first and second pushers arranged on the case of the watch piece.

In view of the above description, it is clear that the calendar display device according to the present invention, which includes the above-described features, provides the following significant advantages: in addition to the overall view of calendar data for the entire month, automatic calibration between information about the days and dates of the week as the month display changes is provided. This automatic calibration applies to normal years and also to leap years, making the device always valid. Moreover, this automatic calibration can be performed by various devices, in particular by a direct kinematic link between the disk of months and the rotary disk, and is therefore performed in a particularly elegant manner in technical terms. Furthermore, such a device also preferably enables the displayed months to be changed manually in a diary manner, thereby providing the user with the opportunity to review the calendar data of the month he wishes at any time. In addition, such devices are highly versatile due to the fact that they can be provided in a plurality of variants based on technical or aesthetic requirements. These advantages are obtained without excessively increasing the complexity, volume or production cost of the device. Finally, the device according to the invention is ideally suited to the visual display on the dial of a watch, thus significantly contributing to the aesthetic appeal of such a watch.

Claims (20)

1. A calendar display device for a watch piece including a watch movement, the calendar display device comprising: a first disk (1), namely a day disk, said day disk (1) carrying a plurality of series of inscriptions representing seven days of the week; a second disc (2), namely a date disc, said date disc (2) bearing inscriptions representing the dates of the months; a third disk (3), namely a month disk, said month disk (3) carrying 12 inscriptions representing the months of the year, one (1, 2) of said day disk (1) and said date disk (2) acting as a dial by being fixed, while the other (2, 1) acts as a rotating disk by being concentrically and rotatably arranged with respect to said dial, said dial comprising an aperture (2.1), said aperture (2.1) enabling the inscription of the current month on said month disk (3) to be seen, said month disk (3) being rotatably mounted and driven directly or indirectly by said watch movement of said watch piece; and a hand (4) arranged concentrically and rotatably with respect to the dial to indicate simultaneously the day of the day and the day of the week, characterized in that the calendar display device comprises a direct kinematic link (7, 8) between the disk of months (3) and the rotary disk (1, 2) to enable automatic calibration between inscriptions on the rotary disk (1, 2) and inscriptions on the dial (2, 1) based on the month displayed.

2. Device according to claim 1, characterized in that the direct kinematic link (7, 8) between the disk of months (3) and the rotary disk (1, 2) comprises two separate parts.

3. Device according to claim 2, characterized in that the first part (7) of the direct kinematic link comprises a first connecting pinion (7.1), said first connecting pinion (7.1) being capable of meshing with the second internal toothing (3.2) of the disk of months (3), said first connecting pinion (7.1) being connected to a first intermediate connecting wheel (7.2) driving a second intermediate connecting wheel (7.3), said second intermediate connecting wheel (7.3) carrying a second connecting pinion (7.4), said second connecting pinion (7.4) in turn meshing with the internal toothing (1.1) of the rotary disk (1, 2).

4. A device according to claim 3, characterized in that said second inner tooth portion (3.2) of said disk of months (3) comprises 12 equidistant angular sectors, each sector, except for the sector corresponding to the month of february, comprising successive notches (3.2.1) and teeth (3.2.2), said notches (3.2.1) and teeth (3.2.2) allowing the rotary disk (1, 2) to be advanced by the drive of said disk of months (3) so that the indexing between the inscriptions on said rotary disk (1, 2) and the inscriptions on said dial (2, 1) is carried out automatically on the basis of the month displayed.

5. An arrangement according to any one of claims 2-4, characterised in that the first part (7) of the direct kinematic link comprises a disconnecting device (7.5) so that the rotating disc (1, 2) can be driven independently of the first part (7) of the direct kinematic link.

6. An arrangement according to claim 5, characterised in that the disconnecting device (7.5) of the first part (7) of the direct kinematic link is a latch release mechanism.

7. The arrangement according to any of the preceding claims 2-4, characterized in that the second part (8) of the direct kinematic link comprises a four-tooth star (8.1), said four-tooth star (8.1) being able to cooperate with a pin (3.3) fixed on said disk of months (3), the star (8.1) being fixed to a first intermediate wheel (8.2) meshing with a second intermediate wheel (8.3), the second intermediate wheel (8.3) is fixed to an actuating finger (8.4) that can be brought into engagement with the internal toothing (1.1) of the rotary disk (1, 2), such that after every four actuations of said star (8.1) by said disk of months (3), said rotating disk (1, 2) advances one step, to automatically calibrate the inscriptions on the rotary disk (1, 2) and the inscriptions on the dial (2, 1) for the month of february in leap years.

8. Device according to claim 7, characterized in that at least one of said intermediate wheels (8.2, 8.3) comprises a toothing (8.2.1) able to cooperate with a jumper (8.5), said jumper (8.5) holding said four-tooth star (8.1) in its rest position and being arranged to cause said jumper (8.5) to reposition said intermediate wheel (8.2, 8.3) with which it cooperates, after actuation of said star (8.1) by means of said pin (3.3) fixed on said disk of months (3), so that said teeth (8.1.1, 8.1.2) of said four-tooth star (8.1) oriented towards said disk of months (3) are located in the path of said pin (3.3) irrespective of the rotation direction of said disk of months.

9. A device according to any one of claims 1 to 4, characterised in that the disk of months (3) is driven by the watch movement of the watch piece through a gear train (6), said gear train (6) comprising a drive finger (6.1) driven by said watch movement to perform one revolution per month, and drives a first intermediate transmission wheel (6.2), said first intermediate transmission wheel (6.2) being in engagement with a cam (6.3) carrying a month cam (6.4), the cam (6.3) drives a second intermediate transmission wheel (6.5) fixed to a third intermediate transmission wheel (6.6), the third intermediate transmission wheel (6.6) is engaged with a transmission pinion (6.7) carrying a transmission wheel (6.8), the transmission wheel (6.8) meshes with a first internal toothing (3.1) of the disk of months (3) in order to rotate the disk of months 1/12 revolutions per month.

10. Device according to any one of the preceding claims 1 to 4, characterized in that said rotary disk (2, 1) is driven by the watch movement of the watch piece through a gear train (6), said disk of months (3) being driven indirectly by said direct kinematic link (7, 8) arranged between said rotary disk (1, 2) and said disk of months (3).

11. The device according to any one of claims 1 to 4, characterized in that said second disc (2), i.e. said date disc, forms said fixed dial; the first disc (1), the days disc, is arranged as a ring that can rotate around the dial; and the third disk (3), the disk of months, is arranged as a ring, said ring being arranged concentrically and rotatably under the dial.

12. The device according to claim 11, characterized in that the first disc (1), the days disc, carries on 35 equidistant angular sectors a series of inscriptions five times representing seven days of the week; the second disc (2), the date disc, carries inscriptions representing the dates of the month from 1 to 31 on 31 equidistant angular sectors of the same angular size as the sectors on the first disc (1), the aperture (2.1) located on the second disc (2) being arranged between the first and the last inscription and occupying angular sizes corresponding to four other equidistant angular sectors of the same angular size as the sectors on the first disc (1).

13. The device according to any of the preceding claims 1 to 4, characterized in that said first disc (1), the days disc, forms said fixed dial; the second disc (2), i.e. the date disc, is arranged as a ring that can rotate around the dial; and the third disk (3), the disk of months, is arranged as a ring, said ring being arranged concentrically and rotatably under the dial.

14. Device according to any one of claims 1 to 4, characterized in that it comprises a correction mechanism (9, 10), said correction mechanism (9, 10) cooperating at least with said gear train (6) driving said disk of months (3) directly or indirectly starting from said watch movement of said watch piece, said mechanism (9, 10) comprising means for advancing and retracting said disk of months (3), so as to allow the months displayed on said dial (1, 2) to be modified in a bidirectional manner.

15. The device according to claim 14, characterized in that said means for advancing and retracting the disk of months (3) comprise, on the one hand, a correction star (9.1) fixed to a correction wheel (9.2) meshing with the gear train (6) driving the disk of months (3) directly or indirectly, and on the other hand a first (10.1) and a second (10.2) correction rod which can be actuated by pressure, the first correction lever (10.1) and the second correction lever (10.2) cause the correction star (9.1) to rotate in the counterclockwise direction and in the clockwise direction, respectively, when actuated, whereby upon each actuation of one of said levers (10.1, 10.2) said disk of months (3) is driven respectively forward or backward 1/12 turns, so as to enable the months displayed on said dial (1, 2) to be changed in a bidirectional manner.

16. Device according to claim 15, characterized in that said first correction lever (10.1) and said second correction lever (10.2), when actuated, cause the lifting of a main control (10.4) by means of an intermediate control (10.3), said main control (10.4) cooperating with a month cam (6.4) arranged on a cam (6.4) located in said gear train (6) driving said month disc (3) to cause the release of the gear train of said gear train (6) during the correction of the displayed months, while said gear train (6) and said month disc (3) are fastened in their current position by means of said main control (10.4) when neither of said levers (10.1, 10.2) is actuated.

17. Device according to any of claims 1-4, characterized in that it comprises a display of the number of copies of the current year and/or a display (5) of the current year type indicating leap and normal years.

18. A watch piece, characterized in that it comprises a calendar display device according to any one of claims 1-17, said device being driven by the basic movement of said watch piece.

19. Watch piece as in claim 18, characterized in that said first (10.1) and second (10.2) correction levers of the device are actuated by corresponding first and second pushers of the watch piece.

20. A watch piece as claimed in claim 18 or 19, characterized in that it is a mechanical watch.