CN110501893B

CN110501893B - Display mechanism for displaying periodic events and timepiece comprising a display mechanism

Info

Publication number: CN110501893B
Application number: CN201910398415.1A
Authority: CN
Inventors: 盖伊·波夫; 雷娜·皮佐伦; 皮埃尔·格罗尔德
Original assignee: Chronometrie Ferdinand Berthoud Sa
Current assignee: Chronometrie Ferdinand Berthoud Sa
Priority date: 2018-05-17
Filing date: 2019-05-14
Publication date: 2022-03-04
Anticipated expiration: 2039-05-14
Also published as: EP3570119B1; EP3570119A1; CN110501893A

Abstract

The present invention relates to a display mechanism for displaying periodic events and a timepiece comprising a display mechanism. The display mechanism includes: the cam includes a cam track, the length of the cam track being determined in accordance with the periodic events displayed by the indicator elements on the markings of the disc. The disc face comprises a first portion supporting the flag and a second portion arranged to be rotationally movable about the first portion by means of a gear arrangement, the cam track being formed on the second portion of the disc face. The gear means comprise a toothed crown integral with the second portion of the dial face and suitable for effecting coupling of the gear means with the hour wheel of the watch movement. The cam follower is movably mounted relative to the first and second portions of the panel and kinematically linked with the indicator element to displace the indicator element relative to the flag during rotation of the second portion of the panel.

Description

Display mechanism for displaying periodic events and timepiece comprising a display mechanism

Technical Field

The present invention relates to the field of watchmaking. More particularly, the present invention relates to a display mechanism for displaying periodic events such as a lunar phase or a calendar display.

The invention also relates to a timepiece having such a display mechanism for displaying periodic events.

Background

Astronomical clocks and calendars have been well known since the 16 th and 17 th centuries, respectively, and many mechanisms designed to display periodic calendar events have been proposed in the prior art. The most common of wristwatches are simple calendars or perpetual calendars and phases of the moon. In a general and simplified manner, these different mechanisms comprise a calendar or synoptic moon gear (greenwork) with a star wheel, the number of teeth of which (7 for the number of days of the week, 12 for the number of months, 31 for the number of days, 59 for the months being equal) being arranged, on the one hand, in kinematic linkage with the hour wheel of the finishing gear train of the watch movement, with which a disc or star indicator of the calendar or moon phase rotates integrally. The gear means are designed to advance the star wheel one step per day to follow the normal calendar evolution and to display corresponding information on or in the watch face.

It is also known that some mechanisms of this type provide a reverse display, as described for example in patents CH 703546B 1 or CH 701836B 1. However, in order to operate the return jump of the hands, these mechanisms require the use of cams of complex shape associated with the rake linked to the hands kinematically, all in a reduced space occupation, so as not to affect the other functions of the watch movement, which generally makes its realization and implementation difficult in the case of fairly compact display information.

It is an object of the present invention to propose a display mechanism for reverse display of periodic events which is easier to implement, more reliable in operation and more accurate than the mechanisms known in the prior art.

Disclosure of Invention

More specifically, according to a first aspect, the present invention relates to a display mechanism for displaying periodic events, the display mechanism comprising:

-a panel provided with signs representing periodic events to be displayed, such as in particular a calendar or a moon phase;

-an indicator element arranged to be rotationally movable relative to the markings on the disc surface to display the periodic events;

-a gear device for displaying said periodic events, the gear device being adapted to be arranged in kinematic linkage with the hour wheel of a watch movement;

-a cam arranged kinematically linked with the display gear means and the indicator element and comprising a cam track, the length of which is determined according to the periodic event displayed by the indicator element on the sign of the disc;

it is characterized in that the preparation method is characterized in that,

-the disc face comprises a circular and concentric first portion supporting said sign and a second portion arranged to be rotationally movable about the first portion by means of the display gear arrangement, the cam track being formed on said second portion of the disc face;

the display gear means comprise a toothed crown integral with the second portion of the dial face and suitable for enabling the coupling of the display gear means with the hour wheel of the watch movement; and is

A cam follower is movably mounted relative to the first and second portions of the panel and kinematically linked with the indicator element to displace the indicator element in a counter-track relative to the sign during rotation of the second portion of the panel.

Such a display mechanism has the following advantages: the structure is very simple, not necessarily compact, and equally suitable for displaying calendars and phases of the moon, while providing the user with additional entertainment elements through the functional mobility of the second part of the disk surface with respect to the first part, and working with finer gearing relationships, thanks to the better precision in the display thanks to the toothed crown with a greater diameter compared to that of classic calendars.

Different special features of the display mechanism of the invention are the subject of claims 2 to 18.

In particular, in one embodiment, the first and second portions of the disc surface are coplanar, each of the first and second portions having an upper or display surface and a lower or gearing surface, the cam track and the indicia representing periodic events to be displayed being arranged on said display surfaces of the second and first portions respectively.

Preferably, said toothed crown is formed or fixed on the gearing surface of the second portion of the disc face.

According to one embodiment, the cam track comprises n identical and consecutive segments on the display surface of the second portion of the disk surface; preferably, n is equal to 12.

According to different embodiments, determined by aesthetic considerations of the display, the cam track is constituted by a different wall protruding from the display surface of the second portion of the panel surface or by a different slide dug out.

In these various embodiments of the cam track, the wall or ramp is formed by plastic deformation, molding, deposition, material removal, assembly, or machining of the second portion of the disk face.

According to one embodiment, the cam follower is a linear follower movable in translation along a radial direction with respect to the second portion of the panel, said follower having a rack meshing with a pinion integral with the indicator element.

According to another embodiment, the cam follower is a movable finger that rotates integrally with the indicator element about an axis of rotation perpendicular to the plane of the disc surface.

In either case, however, the cam follower is retained by a spring that is permanently supported on the cam track.

According to one embodiment, the first portion of the disk surface is circular and concentric with the second portion of the disk surface.

According to one embodiment, the periodic event is a lunar phase, said marks represent different lunar phases in a synodic month of 29.53 days, and the cam track is configured such that the indicator element continuously follows the representation of the successive lunar phases of the synodic month and returns to a so-called "crescent" position at the end of the synodic month.

According to one embodiment, said markers represent different phases of the moon in a half of a synodic month, the cam track being configured such that the indicator element travels past said markers in a rotational direction for the half of a synodic month from a so-called "crescent" position to a so-called full moon position and then in a reverse direction for the next half of the synodic month.

According to one embodiment of the display mechanism for displaying the lunar phases, the display mechanism comprises a second marker located on one of the first and second portions of the disc surface for indicating the progressive addition or depletion nature of the lunar phases and a cursor located on the other of the first and second portions of the disc surface, said markers being configured such that the cursor is positioned opposite to the appropriate marker indication during the entire progressive addition or depletion period of the moon of the synovia month.

As a variant, the periodic event may also be a calendar. In this case, the sign will comprise a sign for the day of the month, and the toothed crown may be, for example, a calendar crown.

The invention also concerns a timepiece comprising a mechanical or quartz watch movement and a display mechanism as previously defined, the display gear means of which is coupled to the hour wheel of the watch movement by said toothed crown.

Drawings

Further details of the invention will become apparent upon reading the following description with reference to the accompanying drawings, in which:

FIG. 1 illustrates an assembled view of a display mechanism for displaying a periodic event, in a preferred embodiment for displaying a lunar phase, in accordance with the present invention;

FIG. 2 illustrates a partial view of the display gear arrangement showing the display mechanism in greater detail without the first disk face portion of the display mechanism of FIG. 1;

3A-3C show partial views similar to FIG. 1 for displaying different positions of a lunar phase by means of the display mechanism of the present invention;

fig. 4A to 4C show partial views similar to fig. 1 for displaying different positions of the second symbol, illustrating the growth of the lunar phase for each of the positions shown in fig. 3A to 3C.

Detailed Description

An embodiment of a display mechanism according to the present invention for displaying periodic events, and more particularly in certain embodiments for displaying lunar phases, is shown in fig. 1 and 2. Such a display mechanism is particularly designed to be mounted in a timepiece, such as a wristwatch, kinematically linked to a watch movement, in particular a mechanical movement (not shown in the figures), of the timepiece.

As shown in fig. 1, this display mechanism first comprises, in top view, a display panel C of a timepiece, such as a watch, on which the visible elements of the display mechanism of the invention can be seen. These elements include, in particular in the example shown, a first disc face portion C1 having a generally circular shape and an annular second disc face portion C2 disposed concentrically with and coplanar with the first portion C1. Each section C1, C2 of disk surface C has an upper or display surface and a lower or gearing surface. The dial ring C2 is advantageously movable in rotation around the first portion C1 by means of the display gear R as shown in fig. 2, ensuring that the ring C2 (the inner toothed crown 1 on the gearing face with the ring C2 formed or fixed on the dial) is kinematically linked to the hour wheel 3 of the finishing gear train of the watch movement via a pinion 2 fitted on the rotation axis of the hour wheel 3.

A first portion C1 of the disc surface C includes on its display surface a main moon sign 14 representing a periodic event to be displayed, in this case a lunar phase during a complete synodic month. In the embodiment shown, said main moon mark 14 comprises a circular track 14a associated with a graduated scale 14b indicating the date of the progressive phase of the synovia from the "0" position or "crescent moon" to the full moon position indicated by the numeral 14, which graduated scale represents the evolution of the moon brightness during this progressive phase, said graduated scale 14b being constituted by sections of increasing and progressive length, with the section of maximum length being opposite the sector of the track 14a corresponding to the fourteenth day of the synovia. An indicator element formed by a so-called moon pointer 8 is associated with the main moon sign 14 so as to progressively indicate the current date of the synodic month in the manner of classical calendar indication. This moon pointer 8 is mounted rotatably movably relative to the fixed part of the disk surface C1 so that it can pivot about its axis above the disk surface C or, if applicable, under the disk surface C, in particular if the fixed part C1 of the disk surface C is transparent. Furthermore, said moon pointer 8 is arranged kinematically linked with the display gear R (fig. 2) by means of a pinion 9 on which the pointer is fastened (in this case screwed) and a cam follower 7 provided with a rack meshing with the pinion 9 and movable in translation in a radial slot 17 formed in a portion C1 of the disk surface C.

The cam follower 7 advantageously abuts, in the region of the contact end 71, a cam track 13 formed on the display surface of the movable ring C2 of the disc surface C. The cam track 13 is advantageously made up of n identical and consecutive segments 13s (twelve segments 13s in the present case), each portion being made up of two

successive cam segments

13a, 13b, so that the contact end 71 of the cam follower 7 slides along the whole one segment 13s in a complete synodic month, and therefore the

cam segments

13a, 13b run, via their toothed crown 1, for a duration equal to half a synodic month during the rotation of the ring C2 of the disc surface C under the action of the display gear R, as described below. Of course, the number of segments 13s of the cam track 13 is determined by the periodic events to be displayed by the display mechanism of the present invention. In this example, the 12 segments 13s can display 12 complete synopsis months of a civilian year of 12 months.

The cam track 13 is preferably constituted by a protruding wall or a hollowed-out slide from the display face of the second portion C2 of the disc face, in particular for example by plastic deformation, moulding, deposition, material removal, assembly or machining of the second portion C2 of the disc face C.

The moon pointer 8 is advantageously moved rotationally with respect to the main moon sign 14 by a counter-rotational movement, travelling in one direction through the entire track 14a of the main moon sign 14 during the first half of a synodic month, while the contact end 71 of the cam follower 7 slides on the

first cam section

13a, 13b and then makes a counter-stroke in the other direction during the following half of a synodic month, while the cam follower 7 slides on the

other cam sector

13b, 13a, respectively.

In order to provide a counter-movement of pointer 8 with respect to flag 14, cam track 13 is advantageously configured in the exemplary embodiment shown such that sliding of contact end 71 of cam follower 7 on one section 13b of cam track 13 produces a left-hand translational movement of cam follower 7 in slot 17 and sliding on section 13a produces a right-hand translational movement, respectively a clockwise and a counter-clockwise rotational movement of pointer 8 with respect to flag 14. Likewise, the

segments

13a, 13b are successively oriented with respect to each other to form the cam track 13 over the entire upper surface of the ring C2 along an obtuse angle α between 110 ° and 135 ° of the central opening towards the disc surface C, so that the cam track 13 is serrated.

In order to assist the left-hand translational movement of the cam follower 7 and the hands 8 in the anticlockwise direction, the leaf spring 10 is advantageously integral with a first end of the pinion 9 carrying the hands 8 and is fastened to a second end on the fixed portion C1 of the panel C, or, as a variant, on a pressure plate of a watch movement associated with the display device of the invention.

In addition to the main moon sign 14 of the date and the brightness of the synodic month, the display mechanism of the invention also comprises a secondary sign 15 for indicating the progressive or progressive nature of the moon. This sub-label 15 has only two

adjacent sectors

15a, 15b, carrying respectively the "+" and "-" signs and of equal length, arranged on the edge of the fixed portion C1 of the disc surface C, so that when the contact end 71 of the cam follower 7 is located at the angle α between the two

segments

13a, 13b of the cam track 13 as shown in fig. 1, the median point 15m of the two

sectors

15a, 15b is radially aligned with the moon cursor 18 on the movable ring C2 of the disc surface C, the hand 8 then facing the scale "14", i.e. the lunate and lunate months. In practice, ring C2 carries 12-month bright cursors 18 regularly distributed along the circumference.

Finally, the panel C of the display mechanism of the invention comprises, in the example shown but in a supplementary manner and not necessarily for the display mechanism of the invention, a secondary panel 16 for displaying the hours, located above the 12 o' clock position and the main panel C, this secondary panel 16 being associated with the hour and minute hands, which are fitted, respectively, in a known classical manner, onto a barrel integral with the hour wheel 3 (fig. 2) and onto a platform coaxial with the hour hand barrel.

Fig. 2 shows in detail the constitution of the display gear device R of the display mechanism of the invention, making it possible to achieve an kinematic link between the hour wheel 3 of the watch movement and the ring C2 of the display panel C of the display mechanism, so that the cam track 13 actuates the displacement of the hand 8 with respect to the sign 14 via the cam follower, and displaces the cursor 18 beside the secondary sign 15, to indicate the progressive nature of the moon in the half of a synoptic month indicated by the sign 14 and the hand 8.

Therefore, starting from hour wheel 3, this display gear R or moon gear comprises:

hour pinion 2, coaxial with hour wheel 3 and comprising a 24-tooth toothing z 1;

a first moon wheel 4 or friction wheel comprising a 62-tooth peripheral toothing z 2;

a first moon pinion 5, coaxial with the first moon friction wheel, said first moon pinion comprising a 16-tooth toothing z 3;

a first return wheel 6;

a second february wheel 12 comprising a 93-tooth peripheral tooth z 4;

a second crowned pinion 11 carried by the second crowned wheel 12 and comprising a 10-tooth toothing z5 and meshing with the moon ring;

a moon ring C2 forming the peripheral part of the disk face C as described above and comprising an internal toothed crown 1 comprising a tooth profile z6 of 236 teeth.

The moon display gearing R is therefore arranged so that on the one hand the first moon wheel 4 meshes with the tooth profile z1 of the hour pinion 2 via its tooth profile z2 and the first moon pinion 5 meshes with the first return wheel 6 via its tooth profile z3, the first return wheel itself meshing with the second moon wheel 12, which is arranged kinematically linked to the moon ring C2 via the toothed crown 1 by the moon pinion 11. The kinematic chain thus makes it possible to drive, starting from the hour wheel 3, the ring C2 in rotation in a counterclockwise direction with a suitable multiplication, this rotation effecting, through the cam track 13 supporting the cam follower 7, the displacement of the moon pointer 8, which is coupled by its pinion 9 to the rack of the cam follower 7, with respect to the main moon sign 14.

The display mechanism of the present invention thus provides in an advantageous manner an original display of the lunar phase by means of the hands with a reverse movement, without a schematic visual representation of the moon as proposed in most of the lunar phase displays of the prior art. Furthermore, the display mechanism of the present invention does not require any moon disk and it uses the movable part of the disk surface C2 as a cam for actuating the moon hands 8, which provides a simplification of the display mechanism and a double animation in the disk surface by the displacement of the ring C2 around the fixed central part C1, which causes the displacement of the moon hands 8 with respect to the main moon sign 14 and the displacement of the moon cursor 18 with respect to the sub-sign 15.

Another major advantage of the display mechanism of the invention compared to the known lunar phase display mechanism is that its accuracy is improved, in particular due to the large toothing z6 of the toothed crown 1 of the ring C2. In fact, the ratio of synodic months RL provided by the mechanism of the invention for the synodic months is calculated so that:

alternatively, the exact value is 29 days, 12 hours, 44 minutes, 15 seconds. Therefore, according to the rotation values of the earth and the sun agreed in 1961, an error of 1 day showing synodic months occurs only after 577 years. It can therefore be considered that it is almost unlikely that corrective adjustments will be required to the mechanism of the invention during the life of the timepiece incorporating the mechanism.

The function and mode of displaying and reading the lunar phases of the display mechanism according to the invention is illustrated in fig. 3A to 3C, and fig. 4A to 4C show enlarged views of the sub-symbol 15 in fig. 3A to 3C.

Figure 3A shows a display of the gradual moon at day 8 of the synoptic month. The contact end 71 of the cam follower 7 abuts against the ring C2 of the disc surface on the tapered section 13b of the cam track 13, the moon pointer pointing to the number 8 of the track 14a of the main moon sign 14. The progressive nature of the moon is then indicated by the radial alignment of cursor 18 on ring C2 with sector 15a carrying the indication "+" on secondary mark 15.

From day 8 to day 15 of the fade, ring C2 continues to rotate in the counterclockwise direction, causing cam follower 7 to slide over section 13B of the cam track until an equilibrium position (at angle a) between section 13B and successive sector 13a is reached, as shown in fig. 3B. The moon pointer 8 is then in a substantially horizontal position pointing towards the upper end of the trajectory 14a of the main moon sign 14, facing the scale 14 and the section with the greatest brightness. Thus, it is a full moon, and the mark of the middle point 15m of the sub-mark 15 is aligned with the cursor 18 on the ring C2, as shown in fig. 4B.

Fig. 3C finally shows the display of the progressive loss moon on day 22 of the synovia month. The moon pointer 8 then moves back in its reverse direction to "0" of the orbit 14a of the main moon sign 14. The contact end 71 of the cam follower 7 abuts against the ring C2 of the disc surface on the progressive section 13a of the cam track 13, the moon pointer pointing to the number 8 of the track 14a of the main moon sign 14. The progressive nature of the moon is then indicated by the radial alignment of cursor 18 on ring C2 with sector 15b carrying the indication "-" on secondary flag 15, as shown in fig. 4C.

The display mechanism of the present invention enables simplified animated representation of new types of periodic events, such as the phases of the moon described above, thanks to its construction or also through a similar mechanism for displaying a calendar. To this end, in particular, it will be sufficient to select a cam track 13, a cam section 13s and/or a

section

13a, 13b of a length and shape suitable to cooperate with one or more indicator elements suitable to represent the desired periodic events, while also adjusting the display gear arrangement as required.

In particular, in the example not shown in the figures, it is possible, for example, by means of a moon disk carried on a calendar carriage with 12 teeth and mounted in rotation on a fixed part of the disk surface C, a mechanism displaying simultaneously the phases of the moon, the year calendar, a tracking member movable in translation similar to the cam follower 7 of the moon pointer 8 being arranged between the cam track 13 and the calendar carriage and being returned by the spring between them, so that said carriage pivots one step each time the tracking member advances from one segment 13s of the cam track 13 to the successive segment 13 s. The calendar date can then be displayed, if appropriate, by means of a pointer actuated in substantially the same way as the moon pointer 8 or by means of a calendar disc according to a classic calendar mechanism of the prior art.

Of course, variations of the display mechanism of the present invention are contemplated by those skilled in the art, particularly with respect to the nature and shape of the indicator elements and associated indicia that provide the desired information of the periodic event.

Claims

1. A display mechanism for displaying periodic events, the display mechanism comprising:

-a disc surface (C) provided with marks (14) representing periodic events to be displayed;

-an indicator element (8) arranged to be rotationally movable relative to a marker (14) on the disc face (C) to display periodic events;

-a gear device (R) adapted to be arranged kinematically linked with an hour wheel (3) of a watch movement,

-a cam arranged kinematically linked with the gear wheel means (R) and the indicator element (8) and comprising a cam track (13) whose length is determined according to the periodic events displayed by the indicator element on the sign (14) of the panel;

it is characterized in that the preparation method is characterized in that,

-the disc face (C) comprises a first portion (C1) carrying the flag (14), which is arranged in an annular second portion (C2) which is rotatably movable about the first portion by means of the gear arrangement (R), the cam track (13) being formed on the second portion (C2) of the disc face;

-said gear device (R) comprises a toothed crown (1) integral with a second portion (C2) of said dial (C) and adapted to enable coupling of said gear device (R) with an hour wheel (3) of a watch movement, and

-a cam follower (7) is movably mounted with respect to a first portion (C1) and a second portion (C2) of the disc surface (C) and kinematically linked with the indicator element (8) to displace the indicator element with respect to the sign (14) in a counter trajectory during rotation of the second portion (C2) of the disc surface.

2. The display mechanism for displaying periodic events according to claim 1, wherein a first portion (C1) and a second portion (C2) of said disc surface are coplanar, each of said first and second portions having a display face and a gearing face, said cam track (13) and said sign (14) representing a periodic event to be displayed being arranged on said display faces of said second portion (C2) and said first portion (C1), respectively.

3. Display mechanism for displaying periodic events according to claim 2, characterized in that said toothed crown (1) is formed or fixed on the gearing face of the second portion (C2) of the disc face.

4. A display mechanism for displaying periodic events according to claim 2 or 3, characterized in that the cam track (13) comprises n successive segments on the display surface of the second portion (C2) of the disc surface.

5. A display mechanism for displaying periodic events according to claim 2 or 3, characterized in that the cam track (13) comprises n identical and consecutive segments on the display surface of the second portion (C2) of the disc surface.

6. A display mechanism for displaying periodic events according to claim 4, wherein n is equal to 12.

7. A display mechanism for displaying periodic events according to claim 5, wherein n is equal to 12.

8. A display mechanism for displaying periodic events according to claim 2 or 3, characterized in that the cam track (13) is constituted by a wall protruding from the display face of the second portion (C2) of the disc face or by a hollowed-out slide.

9. A display mechanism for displaying periodic events according to claim 8, wherein the wall or slide is formed by plastic deformation, molding, deposition, material removal, assembly or machining of a second portion of the panel face.

10. A display mechanism for displaying periodic events according to any one of claims 1 to 3, characterized in that said cam follower (7) is a linear follower translationally movable in a radial direction with respect to a second portion (C2) of the disc face, said linear follower having a rack meshing with a pinion (9) integral with said indicator element (8).

11. A display mechanism for displaying periodic events according to any one of claims 1 to 3, characterized in that the cam follower (7) is a movable finger rotating integrally with the indicator element about an axis of rotation perpendicular to the plane of the disc face (C).

12. A display mechanism for displaying periodic events according to any one of claims 1 to 3, characterized in that the cam follower (7) is held by a spring (10) permanently supported on the cam track (13).

13. The display mechanism for displaying periodic events of any of claims 1 to 3, wherein a first portion (C1) of the disk surface is circular and concentric with a second portion (C2) of the disk surface.

14. Display mechanism for displaying periodic events according to any one of claims 1 to 3, characterized in that the periodic event is a lunar phase, the main lunar signs represent different lunar phases, and the cam track (13) is configured so that the indicator element (8) follows the successive lunars of the synodic moon and returns to the so-called "crescent" position at the end of the synodic moon.

15. A display mechanism for displaying periodic events according to claim 14, wherein the main moon signs represent different phases of a half of a synodic month, the cam track being configured such that the indicator element travels past the main moon signs in the direction of rotation for the half of a synodic month from a so-called "crescent moon" position to a so-called full moon position and then in the opposite direction for the next half of a synodic month.

16. The display mechanism for displaying periodic events according to claim 14, wherein the main moon sign comprises a track (14a) representing different dates in a half synodic month and a scale (14b) representing the moon brightness for each day of the synodic month represented on the track (14a) of the main moon sign.

17. The display mechanism for displaying periodic events according to claim 12, characterized in that it comprises a second marker (15) located on one of a first portion (C1) and a second portion (C2) of the disc surface and intended to indicate the progressive addition or depletion nature of the phases of the moon, and a cursor (18) located on the other of the first portion (C1) and the second portion (C2) of the disc surface, the second marker (15) being configured so that the cursor (18) is positioned opposite to the indication of progressive addition or depletion during the whole respective period.

18. The display mechanism for displaying periodic events according to claim 16, wherein the mechanism comprises a second marker (15) located on one of a first portion (C1) and a second portion (C2) of the disc surface for indicating the progressive addition or depletion nature of the lunar phase, and a cursor (18) located on the other of the first portion (C1) and the second portion (C2) of the disc surface, the second marker (15) being configured such that the cursor (18) is positioned opposite the indication of progressive addition or depletion during the entire respective period.

19. A display mechanism for displaying periodic events according to any of claims 1 to 3, characterized in that the periodic event is a calendar.

20. A timepiece comprising a mechanical or quartz watch movement and a display mechanism according to any one of claims 1 to 19, the gear means of the display mechanism being coupled to the hour wheel of the watch movement by means of the toothed crown.