MECHANISM FOR DISPLAYING THE MOON PHASES FOR A CLOCKWORK

Description

technical field

[0001] The present invention relates to a display mechanism for a watch movement, comprising a representation of the Moon in the form of a disc, a mask capable of masking the representation of the Moon, a mask drive device arranged to be able to move it along a predefined trajectory extending from an initial position to a final position, in such a way that the representation of the Moon and the mask can present, depending on the trajectory, a full Moon configuration in which the representation of the Moon is completely visible, and a new Moon configuration in which the representation of the Moon is completely masked.

[0002] The present invention also relates to a watch movement comprising such a display mechanism and to a timepiece comprising such a watch movement. State of the art

[0003] Such display devices have already been disclosed in prior art.

[0004] As an example, utility model CN202548538U presents a moon phase display mechanism meeting the above characteristics. In particular, the display mechanism disclosed in this document includes a representation of the fixed moon, carried by the dial of the corresponding timepiece, in front of which a mask carried by a driven arm moves in such a way as to exhibit periodic retrograde motion.More precisely, the mask is driven to exhibit the following movements during each period, the duration of which is equal to that of a lunar cycle: starting from an initial full moon configuration, the mask is driven in a counterclockwise rotation from an initial position, gradually covering the representation of the Moon, until it reaches a new moon configuration. This driving continues until a final position in which the representation of the Moon is once again completely uncovered, in a new full moon configuration. The mask is then driven rapidly in a clockwise rotation (a retrograde movement in relation to the slow counterclockwise driving phase) to return to its initial position, still in a full moon configuration, before beginning a new cycle.

[0005] Patent EP1692574B1 describes another mechanism for displaying the phases of the Moon that meets the characteristics mentioned above. More specifically, this mechanism comprises a representation of the Moon carried by a first arm and a mask carried by a second arm. The arms are driven to exhibit an initial slow movement in opposite directions to transition from a first full moon configuration to a second full moon configuration, progressively passing through waning moon phases, a new moon configuration, and then waxing moon phases. Once the second full moon configuration is reached, the moon representation and the mask are rapidly moved, in a retrograde fashion, to return to the first full moon configuration after a period equal to one lunar cycle, before beginning a new cycle.Thus, compared to the one described previously, this mechanism reduces the size of the display of the phases of the Moon since the angular sector covered by the mask is reduced thanks to the fact that the representation of the Moon is also driven in the opposite direction to that of the mask.

[0006] These display mechanisms are primarily aimed at reducing the clutter of displaying the phases of the Moon on a watch dial, while offering a relatively realistic display of the phases of the Moon as they appear to an observer in reality, without however taking into account the movement of the Moon in the sky throughout a given lunar cycle.

[0007] Patent CH710450B1 describes an alternative mechanism for displaying the phases of the moon, designed to enhance realism by offering an orbital display of the moon to symbolize the relative rotation between the Earth's surface and the moon. To this end, the display mechanism comprises a disc, forming the dial of the corresponding timepiece, with an aperture through which a representation of the moon is visible. This disc is driven to rotate on its axis every 24 hours. The mechanism also includes a mask driven to complete a full rotation of the dial every 24 hours with virtually no change in its orientation. This mask is simultaneously driven to move relative to the aperture to display the phases of the moon over periods equal to the length of the lunar cycle.While this mechanism is more realistic than its predecessors, due to the moon's movement along a complete circular path, its legibility is equivalent to that of previous mechanisms because of the moon's smaller size. Furthermore, the increased realism results in a significantly larger display mechanism, as the entire dial rotates to display the starry sky, thus precluding the addition of further complications.

[0008] Therefore, there is still a need to offer an alternative moon phase display mechanism that is realistic, legible, dynamic, and compact enough to allow for the addition of further complications. Disclosure of the invention

[0009] A main objective of the present invention is to propose a display mechanism of alternative construction to known display devices, to produce a timepiece with an appearance that is original, realistic, and highly legible.

[0010] To this end, the present invention relates more particularly to a display mechanism of the type mentioned above, characterized by the fact that it comprises a Moon display element bearing the representation of the Moon, as well as a drive device for the Moon display element arranged to be able to move the latter along the predefined trajectory, between the initial and final positions, and by the fact that it is arranged in such a way that the mask and the representation of the Moon move, during each lunar cycle, according to the following sequence: a) the representation of the Moon and the mask being both located in the initial position, in the new Moon configuration, the representation of the Moon is driven along the predefined trajectory, to gradually move away from the mask, until it is positioned in the final position in the middle of a given lunar cycle, in the full Moon configuration, b) the mask is driven along the predefined trajectory, to gradually cover the representation of the Moon,until positioned in the final position at the end of the given lunar cycle, in new moon configuration, and c) the representation of the Moon and the mask are trained so that they both quickly return to the initial position, in new moon configuration, to begin a new sequence.

[0011] Thanks to these characteristics, the display mechanism according to the present invention has a different operating sequence from that of previous display mechanisms, while maintaining an optimized level of bulk, since the extent of the trajectory traveled by the representation of the Moon and the mask can be contained in a sector joining their centers when they are positioned as adjacent in front view.

[0012] In a preferred embodiment, the moon display is a rotating dial, the mask being carried by a frame capable of also bearing a display surface for information other than the phases of the moon, arranged so as to mask a portion of the rotating dial other than the moon representation. It is then advantageous to provide that the moon representation has a diameter representing at least 50%, preferably at least 60%, of the radius of the rotating dial.

[0013] In general, it is preferable to plan for the representation of the Moon and the mask to be driven retrogradely during step c), with reference to their direction of movement during steps a) and b).

[0014] Preferably, we can expect the representation of the Moon and the mask to be trained in a substantially simultaneous manner during step c).

[0015] Advantageously, one can foresee that the Moon display organ drive device includes a feeler held against a cam guide surface, to define the angular orientation of the feeler at each instant, under the effect of the action of an elastic return element, and that the feeler is integral with a toothing arranged in contact with a Moon drive unit whose angular orientation determines that of the Moon display organ.

[0016] In this case, it can also be predicted that the guiding surface has a first portion of increasing radius, followed by a second portion of substantially constant radius and a third portion, empty or radial, connecting the first and second portions.

[0017] We can then also predict that the mask drive device includes an additional feeler held against a guide surface of an additional cam, to define the angular orientation of the additional feeler at each instant, under the effect of the action of an elastic return member, and that the additional feeler is attached to a toothed gear arranged in contact with a mask drive mechanism whose angular orientation determines that of the mask.

[0018] In this case, it can also be predicted that the additional cam guide surface has a first portion of substantially constant radius, followed by a second portion of increasing radius and a third portion, empty or radial, connecting the first and second portions.

[0019] It can then be particularly advantageous to provide that the display mechanism includes a kinematic link between the cam and the additional cam, and that the first and second portions of the cam guide surface and the first and second portions of the additional cam guide surface all have substantially equal angular extents.

[0020] Furthermore, in this case, it is best to plan that the mechanism includes a support surface attached to one of the probe and the additional probe and capable of bearing against a stop surface attached to the other probe, and that the probe and additional probe are arranged in such a way that the passage of the probe associated with the support surface of the second portion to the first portion of the corresponding guide surface is conditioned by the passage of the probe associated with the stop surface of the second portion to the first portion of the corresponding guide surface, in order to synchronize the movements of the representation of the Moon and the mask during step c).

[0021] According to a preferred embodiment, the display mechanism may be provided to include a latitude adjustment device arranged to modify the angular orientations of the Moon display element and the mask, in a coordinated manner, in response to a predefined action of a user on a latitude adjustment element.

[0022] In this case, it is advantageous to provide that the display mechanism also includes a display element for the latitude set at each instant, the latitude adjustment device also being arranged to control the position of the display element for the set latitude.

[0023] In general, it is preferable to predict that the predefined trajectory followed by the representation of the Moon and by the mask is circular.

[0024] The present invention also relates to a watch movement comprising a display mechanism meeting the characteristics stated above, as well as a timepiece comprising such a watch movement. Brief description of the drawings

[0025] Other features and advantages of the present invention will become more apparent upon reading the detailed description of a preferred embodiment that follows, made with reference to the accompanying drawings given by way of non-limiting example and in which: there figure 1 represents a schematic diagram illustrating the general operating principle of a display mechanism according to a preferred embodiment of the present invention; the figure 2 represents a simplified general front view of a portion of the display mechanism according to the preferred embodiment of the invention; the figure 3 represents a simplified exploded perspective view of an initial construction detail of the display mechanism of the figure 2 ; there figure 4 represents a simplified exploded perspective view of a second construction detail of the display mechanism of the figure 2 , and the figure 5 represents an exploded and simplified perspective view of a third construction detail of the display mechanism of the figure 2 . Method(s) of embodiment of the invention

[0026] There figure 1 represents a schematic diagram illustrating the general operating principle of a display mechanism according to a preferred embodiment of the present invention. Of course, the figure 1 and its detailed description which follows are provided by way of illustrative example and a person skilled in the art may make adaptations justified by their own needs without necessarily going out of the scope of the invention as defined by the claims.

[0027] The diagram of the figure 1 consists of three lines arranged one above the other.

[0028] The top line represents the appearance of the Moon as it appears in the sky when it is at its zenith (its orientation constantly changing noticeably due to the Earth's rotation on its axis), at a latitude of about 45 degrees, on the first day of a new lunar cycle starting with a new moon, then on day 4, day 7, day 11, day 15 (full moon), day 19, day 22, day 25, and then on day 29 (the following new moon).

[0029] The following line (in the middle) represents schematic representations of the phases of the Moon at the same times throughout the lunar cycle, always when it is located at its zenith.

[0030] The lower line schematically and in a simplified manner illustrates the implementation of a lunar phase display mechanism 1, according to a preferred embodiment of the invention, allowing the lunar phases to be displayed reliably and realistically with reference to what can be observed in the sky when the Moon is at its zenith. For the sake of simplicity and readability, the configuration of the display mechanism has not been shown for all the days of the lunar cycle illustrated in the first two lines, but only for the first day, day 7, day 15, day 22, and day 29.

[0031] The display mechanism 1 includes a Moon display element 2 bearing a representation of the Moon 4, here taking the form of a rotating dial, by way of non-limiting illustration.

[0032] A mask 6 is positioned above the rotating dial (from the perspective of an observer of the corresponding timepiece), so as to be able to at least partially cover the representation of the Moon 4 in certain configurations. Mask 6 is here supported by a chassis (numerical reference 8 on the figure 4 ) rotated appropriately to allow the moon phases to be displayed at any given moment. Thus, by way of non-limiting example, the mask 6 here has the shape of a disc whose diameter is equal to, or even slightly larger than, that of the moon representation 4. Two additional discs 10 and 12, also mounted on the chassis, have been illustrated by way of non-limiting example. Discs 10 and 12 can, in particular, define counters in which additional information can be advantageously displayed, whatever its nature, whether temporal or not (the current time, the date or other calendar information, a power reserve, etc.). A person skilled in the art can, for example, implement a display method, in relation to discs 10 and 12, such that the orientation of the display in question remains constant in all positions of the disc on the dial.Constructions enabling such an effect are known in the prior art. The aforementioned patent CH710450B1 describes an example related to the display of the phases of the Moon, and those skilled in the art will encounter no particular difficulty in adapting its teaching and implementing the display of information other than the phases of the Moon.

[0033] According to the present invention, the display mechanism 1 is arranged in such a way that the mask 6 and the representation of the Moon 4 move, during each lunar cycle, according to the following sequence: a) the representation of the Moon 4 and the mask 6 being both located in an initial position, in new Moon configuration, the representation of the Moon 4 is drawn along a predefined trajectory, to gradually move away from the mask 6, until it is positioned in a final position in the middle of a given lunar cycle, in full Moon configuration, b) the mask 6 is drawn along the same predefined trajectory, to gradually cover the representation of the Moon 4, until it is positioned in the same final position at the end of the given lunar cycle, in new Moon configuration.

[0034] At the end of the sequence, the representation of Moon 4 and the mask 6 are trained so that they both quickly return to the initial position, in new moon configuration, thus moving from the configuration of day 29 to that of the first day, to begin a new sequence.

[0035] Here we observe that the Moon 4 representation has a significant diameter compared to the earlier mechanisms mentioned above, offering excellent legibility. More precisely, it is advantageous to stipulate that the diameter of the Moon representation should be at least 50%, and preferably at least 60%, of the radius of the rotating dial on which it is displayed.

[0036] The display mechanism 1 according to the present invention thus makes it possible to implement a spectacular display of the phases of the Moon, without forgoing the display of other information. Indeed, the large dimensions of the representation of the Moon 4 and the mask 6 have an impact on the extent of the trajectory they both describe, which is significant (it extends over slightly less than half of the dial in the example illustrated on the figure 1 ), but the implemented drive kinematics allow for optimization of the corresponding footprint. Furthermore, the available surface area can be used, as mentioned above, to display additional information, particularly through the use of disks 10 and 12. It should be noted that the mask 6 itself can also be used to display information as described previously in relation to disks 10 and 12.

[0037] This results in a particularly advantageous combination of features, allowing both the use of a significant portion of the dial surface for displaying various information and the implementation of an extremely legible display of the phases of the Moon, while remaining faithful to the appearance of the Moon as seen in the sky when it is at its zenith. Even more advantageously, additional features will be described later, by which the rotating dial bearing the representation of the Moon 4 and the frame 8 bearing the mask 6 can be manually rotated simultaneously to adjust the orientation of the display of the phases of the Moon according to the latitude of the wearer of a timepiece incorporating a display mechanism 1 according to this preferred embodiment of the invention.

[0038] There figure 2 represents a simplified general front view of a part of the display mechanism 1 according to the preferred embodiment of the invention.

[0039] The display mechanism 1 can be directly integrated into a watch movement or it can be assembled to a basic watch movement as an add-on module without departing from the scope of the invention. A display mechanism 1 in the form of an add-on display module will be described below for the sake of simplicity. The construction details of the basic watch movement will not be discussed here, for the sake of brevity and simplicity, since the implementation of the present invention does not directly depend on them.

[0040] A twenty-four-hour mobile 20 is driven by a mobile (not visible) of the clockwork movement to complete one rotation in twenty-four hours. The twenty-four-hour mobile 20 carries a finger 22 designed to cooperate with a lunar star 24 to rotate it one step per day when the twenty-four-hour mobile rotates counterclockwise on the view of the figure 2 . Finger 22 has a special construction allowing it to retract when it meets the Moon star 24 while the twenty-four hour mobile 20 rotates clockwise (in case of correction of the current time in particular).

[0041] The Moon star 24 in turn cooperates with a reducing mobile 26 arranged in contact with a Moon cam mobile 28 comprising a groove defining a Moon cam 30.

[0042] There figure 3 represents an exploded and simplified perspective view of part of the display mechanism 1 allowing a better understanding of the function of the Moon cam 30, in particular how it ensures the drive of the Moon display organ 2.

[0043] The display mechanism 1 comprises a moon rocker 32 arranged on a frame element (not shown) so as to be able to pivot about an axis of rotation 34. The moon rocker 32 carries a finger 33 which acts as a feeler by engaging with the moon cam 30 and being held against at least one of its walls, the latter defining a guiding surface for the moon rocker 32. The latter also carries a toothed sector 36 arranged to mesh with a pinion 38 of a drive unit 40 of the moon display element 2, with which its wheel 42 meshes via a gearbox 44 (the meshing being more clearly visible on the figure 2 ).

[0044] Furthermore, an elastic return member 46 has a kinematic link with the display member of Moon 2 to apply on the latter an elastic return force tending to keep the probe against the guide surface of the Moon cam 30.

[0045] It also appears from the figure 3 that the Moon cam 30 has a spiral shape with a first portion extending approximately over half of its total length and having an increasing radius, followed by a second portion also extending approximately over half of its total length and having a constant radius, then a third portion, empty or radial, allowing the finger 33 to fall back from the second portion onto the first portion at the end of the lunar cycle.

[0046] Thus, when the Moon cam mobile 28 is driven from the twenty-four-hour mobile 20, in the direction of clockwise rotation on the view of the figure 3 The Moon cam 30 presents an increasing radius to the probe from the beginning of the first portion, causing the Moon rocker 32 to rotate counterclockwise and the Moon display member 2 to rotate clockwise. During this phase, the elastic return member 46 accumulates mechanical energy.

[0047] When the probe reaches the second portion of the Moon cam 30, the latter continues its rotation without further rotating the Moon rocker 32. The Moon 2 display element, and therefore the representation of the Moon 4, then remain immobile.

[0048] When the feeler reaches the third portion of the Moon cam 30, the elastic return member 46 can release the accumulated mechanical energy by causing the feeler to fall back to the level of the first portion of the Moon cam 30, rapidly rotating the Moon rocker 32 clockwise in the view of the figure 3 , via the Moon 2 display unit and its drive unit 40.

[0049] Returning to the figure 2 , we observe that the Moon cam mobile 28 is arranged in contact with a mask cam mobile 50 comprising a groove defining an additional mask cam 52.

[0050] There figure 4 represents an exploded and simplified perspective view of part of the display mechanism 1 allowing a better understanding of the function of the additional mask cam 52, in particular how it ensures the drive of the chassis 8 carrying the mask 6.

[0051] The display mechanism 1 includes a mask rocker 54 arranged on a frame element (not shown) so as to be able to pivot about an axis of rotation 56. The mask rocker 54 carries a finger (not visible) fulfilling the function of an additional probe by being engaged in the additional mask cam 52 and being held against at least one of its walls, the latter defining a guiding surface for the mask rocker 54. The latter also carries a toothed sector 58 arranged in mesh with a pinion 60 of a drive unit 62 of the frame 8, to which its wheel 64 is kinematically connected by means of a gearbox 66 and a ring gear 68 intended to be directly attached to the frame 8.

[0052] Furthermore, an elastic return element 70 has a kinematic link with the ring 68 to apply on the chassis 8 an elastic return force tending to hold the additional probe against the guide surface of the additional mask cam 52.

[0053] It also appears from the figure 4 that the additional mask cam 52 has a spiral shape having a first portion extending substantially over half of its total length (at the central shaft) and having a constant radius, followed by a second portion also extending substantially over half of its total length and having an increasing radius, then a third portion, empty or radial, allowing the additional probe to fall back from the second portion onto the first portion at the end of the lunar cycle.

[0054] Thus, when the mask cam mobile 50 is driven from the twenty-four hour mobile 20, via the Moon cam mobile 28, in the counter-clockwise direction of rotation on the view of the figure 4 , the additional mask cam 52 presents a constant radius to the additional feeler from the beginning of the first portion, resulting in a lack of rotation of the mask rocker 54 and therefore of the mask 6 for half of a given lunar cycle.

[0055] When the probe reaches the second portion of the additional mask cam 52, the latter presents an increasing radius to the additional probe, which causes the mask rocker 54 to rotate counterclockwise in the view of the figure 4 This causes the chassis 8, and therefore the mask 6, to rotate clockwise. During this phase, the elastic return element 70 accumulates mechanical energy.

[0056] When the probe reaches the third portion of the additional mask cam 52, the elastic return member 70 can release the accumulated mechanical energy by causing the additional probe to fall back to the level of the first portion of the additional mask cam 52, rapidly rotating the mask rocker 54 in the counterclockwise direction in the view of the figure 4 , through the crown 68 and the reference 66.

[0057] As mentioned above, mask 6, as well as discs 10 and 12, can be used to implement additional displays of any type of information, whether time-related or not. Various holes and recesses in these three discs are shown for illustrative purposes only (notably to allow the mounting of moving parts, springs, and to allow the passage of switches).

[0058] Returning once again to the figure 2 It appears that the mask flipper 54 includes a beak defining a stop surface 74 arranged to cooperate with a bearing surface 76 of the moon flipper 32, defined here by a pin. The cooperation between these stop and bearing surfaces ensures good synchronization during the retrograde return of the two flippers 32 and 54. Indeed, it can be seen that, in the configuration of the display mechanism 1 illustrated on the figure 2 , while the probes are close to the end of the second portion of the corresponding cam, if the Moon rocker 32 were to be released before the mask rocker 54, for example in case of shock, it could not descend into the third portion of the corresponding cam due to the contact between its bearing surface 76 and the stop surface 74 of the mask rocker 54.

[0059] The display mechanism 1 advantageously includes a correction element for the display of the phases of the Moon, comprising here a correction rocker 80 carrying a retractable ratchet 82, arranged to act directly on the Moon star 24. The correction rocker 80 has an actuation surface 84 intended to receive pulses, in response to appropriate actions by a user, following which the correction rocker 80 pivots to advance the Moon star 24 by at least one step per actuation.

[0060] Advantageously, the display mechanism 1 according to the present preferred embodiment of the invention further comprises a latitude adjustment device arranged to modify the angular orientations of the Moon display element 2 and the mask 6, in a coordinated manner, in response to a predefined action of a user on a latitude adjustment element.

[0061] This adjustment mechanism is more clearly visible on the figure 5 which represents its main components in an exploded and simplified perspective view.

[0062] The latitude adjustment device includes a correction rocker 90 having an actuation surface 92 intended to receive impulses from a user via a corrector (not visible) for example, to pivot on a frame element.

[0063] The correction lever 90 carries an actuating beak 94 arranged to act on the main teeth 96 of a latitude correction wheel 98 and advance the latter by at least one step per user impulse. A conventional jumper 100 ensures that the latitude correction wheel 98 is held in a given position, also cooperating with its main teeth 96.

[0064] Half of the teeth of the main gear 96 have an extension along a direction substantially parallel to the direction of the axis of rotation of the latitude correction wheel 98, while the latter includes an internal secondary gear 102.

[0065] The two gears 96 and 102 are arranged to cooperate with a drive unit 104 of a latitude indicator (not shown), via a toothed ring 106 to which the latter is attached. The latitude indicator may bear an indication intended to cooperate with a fixed latitude scale, or it may bear a latitude scale intended to cooperate with a fixed indication to display the set latitude value.

[0066] The training of the training wheel 104 is carried out via a lower star (hidden on the figure 5 ), while the drive unit comprises a main star 108 arranged in contact with the wheel 64 of the drive unit 62 of the chassis 8, as can be seen from the figure 2 .

[0067] The drive unit 104 further includes a pinion 110 by which it provides the drive for the toothed ring 106.

[0068] The toothed ring 106 in turn drives a lunar drive 112 via a pinion 114 of the latter. The lunar drive 112 also includes a star 116 arranged to mesh with the wheel 42 of the drive 40 of the lunar display 2. Each of the drive 40, 62 advantageously includes friction between its wheel and its pinion, to allow rotation of the wheel only during latitude adjustment.

[0069] Thus, when the user applies pulses to the correction rocker 90, he simultaneously rotates the Moon 2 display organ and the chassis 8 carrying the mask 6, in the same direction of rotation, without changing the positions of the representation of the Moon 4 and the mask 6 along their trajectory.

[0070] After a certain number of pulses, the teeth of the latitude correction wheel 98, which mesh with the lower star wheel of the drive unit 104, change, resulting in a change in the direction of rotation of the latter. With proper indexing of the mechanism, this design allows the latitude to be corrected across its entire range of values ​​without altering the operation of the corresponding control element, in this case, a corrector. Thus, starting, for example, with an initial latitude setting of 45 degrees, the first pulses will increase the value until it reaches 90 degrees. The next pulse will then decrease the latitude value, allowing the user to lower it to -90 degrees before raising it again by continuing to apply pressure to the corrector.

[0071] A double jumper 118 is arranged to cooperate with the drive units 104 and 112 to ensure their orientation in the set position. Of course, it is possible to provide two independent jumpers as an alternative.

[0072] Thanks to the characteristics just presented, it is possible to create a moon phase display mechanism with an original appearance that is faithful to a real observation of the moon in the sky, while offering excellent readability without preventing the addition of further complications on the dial of the corresponding timepiece.

[0073] The preceding description focuses on describing a particular embodiment by way of non-limiting illustration, and the invention is not limited to the implementation of certain specific features described above, such as the implementation of additional discs mounted on the chassis, or even their number, if any, or their shape (which is not limited to a single disc). Furthermore, the display mechanism described above can be implemented without the latitude adjustment mechanism, without departing from the scope of the present invention as defined by the claims. In this case, the mechanism could, for example, be customized for each buyer, with a latitude adjustment corresponding to their place of residence.When a latitude adjustment mechanism is implemented, it can also be provided that it is operated by rotating an external control ring, in one direction or the other, as an alternative to what has been described above.

Claims

1. Moon phase display mechanism (1), for a watch movement, comprising a disc-shaped representation of the Moon (4), a mask (6) suitable for masking said representation of the Moon (4), a drive device for said mask (6) arranged to be able to move it along a predefined trajectory extending from an initial position to a final position, so that said representation of the Moon (4) and said mask (6) can present, along said trajectory, a full Moon configuration in which said representation of the Moon (4) is completely visible, and a new Moon configuration in which said representation of the Moon (4) is completely masked, characterized in that it comprises a Moon display member (2) carrying said representation of the Moon (4), as well as a drive device for said Moon display member (2) arranged to be able to move the latter along said predefined trajectory, between said initial and final positions, and in that it is arranged in such a way that said mask (6) and said representation of the Moon (4) move, during each lunar cycle, according to the following sequence: a) with said representation of the Moon (4) and said mask (6) being both located in said initial position, in a new Moon configuration, said representation of the Moon (4) is driven along said trajectory, to progressively disengage from said mask (6), until being positioned in said final position in the middle of a given lunar cycle, in a full Moon configuration, b) said mask (6) is driven along said trajectory, to progressively cover said representation of the Moon (4), until it is positioned in said final position at the end of the given lunar cycle, in a new Moon configuration, and c) said representation of the Moon (4) and said mask (6) are driven so as to both rapidly return to said initial position, in a new Moon configuration, to begin a new sequence.

2. Mechanism (1) according to claim 1, characterized in that said representation of the Moon (4) and said mask (6) are driven in a retrograde manner in step c), with reference to their direction of movement in steps a) and b).

3. Mechanism (1) according to claim 1 or 2, characterized in that said representation of the Moon (4) and said mask (6) are driven substantially simultaneously in step c).

4. Mechanism (1) according to one of the preceding claims, characterized in that said device for driving said Moon display member (2) comprises a feeler held in abutment against a guide surface of a cam (30), to define the angular orientation of said feeler at each instant, under the effect of the action of an elastic return member (46), and in that said feeler is integral with a toothing (36) arranged in engagement with a Moon drive wheel (40) whose angular orientation determines that of said Moon display member (2).

5. Mechanism (1) according to claim 4, characterized in that said guide surface has a first portion of increasing radius, followed by a second portion of substantially constant radius and a third portion, empty or radial, connecting the first and second portions.

6. Mechanism (1) according to claim 4, characterized in that said device for driving said mask (6) comprises an additional feeler held in abutment against a guide surface of an additional cam (52), to define the angular orientation of said additional feeler at each instant, under the effect of the action of an elastic return member (70), and in that said additional feeler is integral with a toothing (58) arranged in engagement with a driving mobile (62) of said mask (6), the angular orientation of which determines that of said mask (6).

7. Mechanism (1) according to claim 6, characterized in that said guide surface of said additional cam (52) has a first portion of substantially constant radius, followed by a second portion of increasing radius and a third portion, empty or radial, connecting the first and second portions.

8. Mechanism (1) according to claims 5 and 7, characterized in that it comprises a kinematic connection between said cam (30) and said additional cam (52), and in that the first and second portions of the guide surface of said cam (30) and the first and second portions of the guide surface of said additional cam (52) all have substantially equal angular extents.

9. Mechanism (1) according to claim 8, characterized in that it comprises a bearing surface (76) integral with one of said feeler and said additional feeler and capable of bearing against a stop surface (74) integral with the other feeler, and in that said feeler and said additional feeler are arranged in such a way that the passage of the feeler associated with said bearing surface (76) from the second portion to the first portion of said corresponding guide surface is conditioned by the passage of said feeler associated with said abutment surface (74) from the second portion to the first portion of said corresponding guide surface, in order to synchronize the movements of said Moon display member (2) and said mask (6) in step c).

10. Mechanism (1) according to claim 8 or 9, characterized in that it comprises a latitude adjustment device arranged to modify the angular orientations of said Moon display member (2) and said mask (6), in a coordinated manner, in response to a predefined action of a user on a latitude adjustment member.

11. Mechanism (1) according to claim 10, characterized in that it further comprises a latitude display member to display the set latitude at each instant, said latitude adjustment device also being arranged to control the position of said latitude display member.

12. Mechanism (1) according to one of the preceding claims, characterized in that said Moon display member (2) is a rotary dial, and in that said mask (6) is carried by a frame (8) further carrying a surface for displaying information other than Moon phases and arranged so as to mask a portion of said rotary dial other than said representation of the Moon (4).

13. Mechanism (1) according to claim 12, characterized in that said representation of the Moon (4) has a diameter representing at least 50%, preferably at least 60%, of the radius of said rotary dial.

14. Watch movement comprising a display mechanism (1) according to one of claims 1 to 13.

15. Timepiece (1) comprising a watch movement according to claim 14.