CLOCK WITH UNIVERSAL HOUR DISPLAY AND DATE CORRECTION MECHANISM

Description

technical field

[0001] The present invention relates to a world time timepiece comprising a date correction mechanism. The correction mechanism allows the date to be corrected according to the selected time zone. State of the art

[0002] World time watches allow the wearer to simultaneously display the local time and the time in other time zones. By convention, the Earth is divided into twenty-four time zones. The first time zone is centered on the Greenwich Meridian and is usually referred to by the abbreviation UTC or UTC+0. The local time in London, called Greenwich Mean Time ( GMTGMT+1 is used as the reference for calculating time around the world. Time is one hour ahead or one hour behind when crossing from one time zone to another, depending on whether one is traveling east or west. For example, the time in Switzerland is one hour ahead of London, so Switzerland is on GMT+1. The twenty-four time zones extend along the circumference of the Earth between UTC+12 and UTC-11 (during winter time).

[0003] This type of timepiece features a disc on which the names of twenty-four cities, each corresponding to a different time zone, are inscribed within twenty-four 15° sectors. For example, London is inscribed within one 15° sector of the disc, and Geneva GMT+1 is inscribed within an adjacent sector. Generally, this disc includes a sector diametrically opposite the Greenwich sector, in which the city of Auckland (UTC +12) is indicated. An adjacent sector to the Auckland sector indicates Midway (UTC -11). The meridian separating these two time zones results in a change of date. When crossing this meridian from Midway to Auckland, the date must be advanced by one day, while crossing it in the opposite direction requires the date to be set back by one day.

[0004] However, there is a special case between 11 p.m. and midnight for the time zone corresponding to Auckland, where the date must remain unchanged when switching to the time zone corresponding to Midway. Indeed, the arrival of midnight advances the date by one day, while the transition from Auckland to Midway sets the date back by one day.

[0005] Generally, a timepiece with world time does not have a date display or displays the date only in relation to local time, since correcting the date to address the aforementioned problem is complex to achieve, especially the simultaneous and contradictory action on a date star in the particular case mentioned above.

[0006] EP2790069, however, offers a timepiece with twenty-four time zones and a date display mechanism capable of adjusting the date according to all possible time zone changes. This mechanism allows, in particular, for a day to be subtracted from the date when a time zone change between Auckland and Midway occurs before 11 p.m., and for the date to remain unchanged when a time zone change between Auckland and Midway occurs between 11 p.m. and midnight Auckland time.

[0007] To this end, the date display mechanism according to EP2790069 includes a synchronizing mechanism kinematically linked to the date mechanism and a time zone mechanism. This synchronizing mechanism comprises a differential gear configured so that an output wheel of the differential, depending on the combination of inputs, can perform one of the following operations: advance the date by one day, advance the date by one day, or leave the date unchanged. In particular, the simultaneous rotation of an input star wheel by one step and a satellite wheel by one step leaves an output wheel, carrying the date hand in this case, stationary for a time zone change between Auckland and Midway occurring between 11 p.m. and midnight Auckland time.

[0008] The gear train of the aforementioned differential, however, has the drawback of introducing play that necessitates the addition of an extra jumper, designed to operate simultaneously with the main jumper. The use of these jumpers significantly increases the timepiece's power consumption. Brief summary of the invention

[0009] One aim of the present invention is therefore to offer a universal timepiece equipped with a date mechanism whose consumption is significantly less than the aforementioned mechanism.

[0010] This purpose is achieved, in particular, by means of a world time clock comprising a city disc, a 24-hour disc, an hour indicator, a disc support that rotates fixedly to the city disc, a drive mechanism that rotates fixedly to the 24-hour disc and is arranged to rotate once every 24 hours, a time zone correction mechanism designed to rotate the city disc, the 24-hour disc, and the hour indicator at each time zone correction, and a date display. The date display includes a display stand bearing date indications, a date indicator, and a date correction mechanism comprising a triggering system. This mechanism is arranged to induce a first movement of the date indicator relative to the display stand in one direction each day.The date correction mechanism also includes an actuation element attached to the disc support to induce a second movement of the date indicator relative to the indication support in the opposite direction when a time zone correction causes the date to move backward.

[0011] In one embodiment, the date indicator or display holder is kinematically connected to a date star. The triggering system is configured to rotate the date star in a first direction to induce the first movement. The actuation element of the disc holder is arranged to indirectly rotate the date star in a second direction opposite to the first to induce the second movement.

[0012] In one embodiment, the display medium is in the form of a date disc. The date indicator or date disc is rotationally fixed to a date ring which is engaged with a date wheel fixed to the date star.

[0013] In one embodiment, the date correction mechanism further comprises a correction wheel meshing with the date wheel and a correction star fixed to the correction wheel for rotation. The actuating element is arranged to engage a tooth of the correction star to induce said second movement.

[0014] In one embodiment, the triggering system comprises a 24-hour wheel arranged to complete one revolution every 24 hours, a cam fixed to the 24-hour wheel, a rocker arranged to cooperate with the cam to perform one jump per day, and a finger to drive the date star in the first direction with each jump of the rocker. The finger is movably mounted on the rocker so that it is disengaged from the date star when the date star is rotated in the second direction by the actuating element.

[0015] In one embodiment, the triggering system further includes a drive element pivotally mounted on the rocker and comprising the finger.

[0016] In one embodiment, the drive element includes a follower arranged to move in a groove along a closed path. The groove has a first portion acting on the follower to pivot the drive element on the rocker so that the finger can engage a tooth of the date star at each jump of the rocker.

[0017] In one embodiment, the groove includes a second portion acting on the follower to pivot the drive member on the rocker so that the finger is clear of the date star from the end of the rocker jump until the next jump.

[0018] In one embodiment, the time zone correction mechanism comprises a first rocker arm arranged to actuate the drive mechanism of the 24-hour disc and the hour indicator, and a second rocker arm arranged to actuate the support of the city disc. The two rockers are arranged to cooperate with a control mechanism that moves in a first direction and then in the opposite direction to return to its initial position, such that one of the rockers can actuate one of the support and the drive mechanism when the control mechanism is actuated in the first direction, and the other rocker arm can actuate the other of the support and the drive mechanism when the control mechanism moves in the second direction.

[0019] In one embodiment, the two rockers are connected to each other by a linking element.

[0020] In one embodiment, the disc support for the cities is in the form of a first ring arranged to be rotated by one of two rocker arms. The driving element is in the form of a second ring arranged to be rotated by the other of the two rocker arms.

[0021] In one embodiment, the second crown is engaged with a driving wheel arranged to be driven in rotation by said other of the two rockers.

[0022] In one embodiment, the second crown is further kinematically linked to a wheel of a driving gear train. This wheel is integral with a five-toothed star wheel cooperating with a jumper so that the rotation of the driving wheel drives the twenty-four-hour crown by one twenty-fourth of a turn and the hour indicator by one twelfth of a turn. Brief description of the figures

[0023] Examples of implementation of the invention are given in the description illustrated by the accompanying figures, in which: there figure 1 illustrates a top view of part of the clockwork mechanism with a partial representation of the date disc, the city discs, and the twenty-four-hour disc; figures 2a to 2c illustrate top views of an operational sequence of the time zone correction mechanism during a one-way stroke of the control unit; the figures 3a to 3c illustrate top views of an operational sequence of the time zone correction mechanism during the opposite direction of the control organ's travel, and the figures 4a to 4f illustrate an operational sequence of the date triggering mechanism at the passage of midnight. Detailed description of the methods of execution of the invention

[0024] The timepiece according to the invention, illustrated in the figures, may be, in particular, a wristwatch or a table clock comprising a mechanism for displaying universal time and time zones known to those skilled in the art and described, for example, in CH693191. The timepiece also includes a date display and correction mechanism, which will be described later, and which allows the date to be triggered when a change of time zone results in a change of date at midnight.

[0025] With reference to the figure 1The world time timepiece 10 features a classic design: a first disc 12, called the city disc 12, inscribed with the names of twenty-four cities. Each city corresponds to one of the twenty-four time zones. For simplicity, only GMT indications such as GMT-4, GMT-5, and GMT-4 are shown, corresponding to different time zones specific to different cities. A second disc 14, called the twenty-four-hour disc 14, is positioned inside the city disc and is numbered from 1 to 24 (only the numbers 7 and 8 are shown), so that the numbers increment clockwise to allow the time to be read opposite each city.

[0026] The twenty-four-hour disc 14 is kinematically linked to the hour wheel carrying the hour hand of the time display mechanism of the timepiece, so as to rotate continuously counterclockwise at a rate of one revolution every twenty-four hours. To this end, the twenty-four-hour disc 14 is attached to a driving element 16 arranged to be driven in rotation by the movement at a rate of one revolution every twenty-four hours.

[0027] The time displayed by the hour and minute hands of a conventional world time clock corresponds to the current time in the city on the 12-hour disc located at 12 o'clock relative to the clock face. This time is referred to in this application as "local time." To read the time in another time zone, simply locate the inscription for the city corresponding to that other time zone and read the number on the 24-hour disc opposite that city.

[0028] The timepiece 10 also includes a date display mechanism. This mechanism comprises, in particular, an annular disc 45 and a date indicator in the form, for example, of an aperture 48. The disc 45 is arranged around the city disc 12 and includes the numbering from 1 to 31 of the days of the month. According to the embodiment illustrated, the date disc 45 is fixed, while the aperture 48 is attached to a crown 46 which engages with a date wheel 50, the latter being attached to a date star 52. It will be understood that the date disc can be attached to the crown while the aperture can be fixed, for example, in the form of an opening in the dial, according to a more conventional date display.

[0029] In another embodiment, the date star could have 31 teeth and carry a date hand. In this case, the dial could display the numbering from 1 to 31 of the days of the month, arranged, for example, along an annular area on the dial concentric with the axis of rotation of the date hand. The presence of a date disc is therefore not an essential feature of the date display mechanism.

[0030] Generally, the mechanism for displaying world time and time zones allows the user to change the time zone and display the corresponding time in that new time zone via a time zone correction mechanism. This mechanism includes a control element (not shown), for example, a pusher that the user can manually press a number of times necessary to align the city in the new time zone, displayed on the city disc, with the 12 o'clock position relative to the watch face. This new time zone typically corresponds to the user's local time.

[0031] Conventionally, the time zone correction mechanism is designed to rotate the city disc 12 and the 24-hour disc 14 counterclockwise with each time zone correction. The hour hand is typically kinematically linked to the 24-hour disc 14 so that it is driven to advance by one hour clockwise with each time zone correction.

[0032] For this purpose, the city disc 12 is attached to a disc support 18. This support is in the form of a first ring 18 with a series of twenty-four teeth 19 evenly distributed around its outer circumference. The twenty-four-hour disc 14 is attached to a second ring 16 arranged inside the first ring 18 coaxially with it. The second ring 16 has external teeth that mesh with a wheel 22 of a drive gear via two linkages 26, 28.

[0033] According to the lower part of the figure 1The time zone correction mechanism includes a first rocker 34 arranged to actuate in a counterclockwise rotation the crown 16 which is fixed in rotation to the twenty-four hour disc 14, and a second rocker 40 arranged to actuate in a counterclockwise rotation the crown 18 which is fixed to the city disc 12. More particularly, the first rocker 34 is mounted to pivot about the axis A and includes a part 38 which can be operated by the user by the control member such as a pusher via a lever (not shown).

[0034] This first rocker arm 36 has an arm whose end is configured to cooperate with a toothed wheel 32, under the action of a spring (not shown). This wheel is mounted coaxially and integrally with a driving wheel 30 that meshes with the ring gear 16. The second rocker arm 40 is mounted to pivot about axis B and has a finger 42 arranged to engage between two teeth 19 of the first ring gear 18 and to push against one of these teeth in order to rotate the disc of the cities 12 counterclockwise. The two rocker arms 34 and 40 are connected to each other by a linkage 44.

[0035] It will be understood, according to the description of the operational sequence of the time zone correction mechanism which will be given later with reference to figures 2a to 2c , And 3a to 3cThis mechanism allows the twenty-four-hour disc 14 and the city disc 12 to be operated counterclockwise sequentially. The operation of the twenty-four-hour disc 14 and the city disc 12 occurs respectively during the "back and forth" movement of the control element, for example a push button, when it is activated.

[0036] It should also be noted that the driving gear wheel 22 is integral with a five-toothed star wheel 24, which cooperates with a jumper 77. The gear ratio between the wheel 22, the two linkages 26 and 28, and the teeth of the crown 16 has been determined so that the rotation of the driving wheel 30 by the first rocker arm 34 can drive the 24-hour crown 16 by one twenty-fourth of a turn. In other words, the star wheel 24 ensures that the 24-hour disc 14 is indexed at each time zone change. It will also be understood that the second rocker arm 40 allows the crown 18 to be rotated by one twenty-fourth of a turn counterclockwise at all times to bring the city corresponding to the new time zone, inscribed on the city disc 12, to 12 o'clock relative to the dial of the timepiece.

[0037] In order that the date mechanism can display at all times the date proper to the selected time zone while overcoming the disadvantages of the prior art, the timepiece 10 includes a date correction mechanism comprising, on the one hand, a triggering system 60 kinematically linked to the crown 16 supporting the twenty-four hour disc 14 and arranged to change the date every day at midnight, and on the other hand, an actuating element 20 attached to the crown 18 supporting the city disc 12.

[0038] This actuation element can, for example, take the form of a finger 20 whose end is located beyond the end of the teeth 19 of the crown 18. According to the illustrated example, this finger 20 is intended to engage a correction star 58 attached to a correction wheel 56 in contact with the date wheel 50 each time the time zone correction causes a passage from Auckland to Midway causing the date to be pushed back by one day.

[0039] The triggering system 60 is configured to rotate the date star 52 and the date wheel 50 of the date display mechanism clockwise to increment the date by one during the "going" motion of the control member. Conversely, the date star 52 is rotated counterclockwise by the action of finger 20 on the correction star 58 of the correction wheel 56 during the "coming" motion of the control member when a time zone correction results in a date change. The sequential rotation of the date star 52, one step clockwise and one step counterclockwise during the back-and-forth movement of the control member, ensures that the date remains unchanged during a time zone change between Auckland and Midway occurring between 11 p.m. and midnight Auckland time.

[0040] With reference to the figure 4aThe triggering system 60 comprises, for this purpose, a twenty-four-hour wheel 62 arranged to complete one revolution every twenty-four hours and kinematically connected to the crown fixed to the twenty-four-hour disc, a snail-shaped cam 64 fixed to the twenty-four-hour wheel 62, a rocker 66 arranged to cooperate with the cam 64 via a feeler 68, and a rocker spring (not shown) acting on the rocker 66. The rocker is thus configured to perform one jump per day. A drive member 70 is pivotally mounted on the rocker and includes a finger 72 to drive the date star 52 clockwise with each jump of the rocker.

[0041] Since time zone correction can occur at any time, it is essential that the triggering system 60 activates the star 52 at midnight clockwise instantly while remaining clear the rest of the time to allow for reverse date correction when a change of time zone causes a date to fall back.

[0042] For this purpose, the drive element 70 is configured to be disengaged from the date star 52 when the date wheel 50 is rotated counterclockwise, via the correction wheel 56 driven by the action of the finger 20 on the star 58, as illustrated by the figure 1When a time zone correction results in a date adjustment, the drive member 70 includes a follower 74 arranged to move in a groove 76 along a closed path. The groove has a first portion 76a, acting on the follower 74 to pivot the drive member 70 on the rocker 66 so that the finger 72 can engage a tooth of the date star 52 with each jump of the rocker. The groove 76 has a second portion 76b, acting on the follower 74 of the pawl 70 to pivot the pawl on the rocker so that the finger 72 is disengaged from the date star 50 at all times when the rocker 66 cooperates with the cam 64 after the jump of the rocker until its next jump.

[0043] In order to avoid a malfunction of the date correction in the event that the change of time zone resulting in a change of date occurs when the triggering system 60 activates the star 52, the first and second rockers 32, 40 of the time zone correction mechanism are arranged to rotate in turn the crown 16 connected to the twenty-four hour disc 14 and the crown 18 connected to the city disc 14.

[0044] More specifically, according to the operational sequence illustrated by the figures 2a to 2c , And 3a to 3c, when changing time zones, the first rocker 34 of the time zone correction mechanism will first rotate the crown 16 counterclockwise, thus driving the twenty-four hour disc 14 via the wolf tooth wheel 32 and the driving wheel 30, then the second rocker 40 of the correction mechanism will rotate the crown 18 counterclockwise, thus driving the city disc 12.

[0045] With each time zone correction, the 24-hour disc 14 and the city disc 12 are activated sequentially. For example, the control element for the time zone correction mechanism can be a push button. When the user presses the push button, it moves the first rocker 34 in its initial direction, rotating the 24-hour disc 14 by one twenty-fourth of a turn counterclockwise. The push button then rotates the city disc 12 by one twenty-fourth of a turn counterclockwise as it moves in the opposite direction, returning to its rest position under the action of return mechanisms (not shown).

[0046] More specifically, by referring to the figure 2aThe user actuates part 38 of the first rocker 34 downwards by means of the control member, causing the rocker 34 to pivot around its axis A in order to engage the distal part of the arm 36 with the teeth of the wolf's tooth wheel 32. At this moment, the finger 42 of the second rocker 40 rests on a tooth 19 of the crown 18 supporting the disc of the cities 12. When the control member continues its travel along the figures 2b and 2c , the arm 36 of the rocker 34 rotates the wolf's tooth wheel 32 in order to drive the crown 16 via the driving wheel 30.

[0047] As explained previously, since the crown 16 is also engaged with the wheel 22, which is fixed to the five-toothed star 24, the crown 16 is indexed in increments of 15° or one twenty-fourth of a turn with each action on the control mechanism. This allows for an offset of one full hour, regardless of the position of the hour hand (which depends on the displayed minute).

[0048] The two rockers 36, 40 being connected to each other by the linking member 44, the movement of the first rocker 34 makes it possible to disengage the finger 42 of the second rocker 40 from one of the teeth 19 of the crown 18 supporting the disc of the cities 12 and to position this finger 42 so that it can engage an adjacent tooth 19 of the crown 18 supporting the disc of the cities 12.

[0049] By referring to figures 3a to 3cOnce it reaches the end of its travel, the control member moves in the opposite direction to reach its rest position. Since the control member is connected to the actuable part 38 of the first rocker 34, the rocker pivots around axis A counterclockwise in order to, on the one hand, disengage the arm 36 of this rocker from the toothed wheel 32 and, on the other hand, to pivot the second rocker 40 around its axis B clockwise via the connecting member 44 to engage the finger 42 against a tooth 19. During the movement of the control member to its rest position, the finger 42 pushes against the tooth 19 to rotate the crown 18 by one twenty-fourth of a turn counterclockwise and the city disc 12 in the same way to bring the city corresponding to the new time zone to 12 o'clock relative to the dial of the timepiece.

[0050] Thus, when the user activates the time zone correction mechanism between 11 p.m. and midnight to set the Midway time zone, the first movement of the rocker 34 causes the triggering system 60 to rotate the date wheel 50 clockwise by acting on the date star 52. Then, during the second movement of the rocker 34, the finger 20 of the crown 18 rotates the date wheel 50 counterclockwise by acting on the correction star 58. The date therefore remains unchanged when switching to the Midway time zone. Indeed, the arrival of midnight advances the date by one day, while the transition from Auckland to Midway sets the date back by one day.

[0051] The figures figures 4a to 4f illustrate an operational sequence of the date correction mechanism.

[0052] According to the figure 4aThe finger 72 of the pawl 70 is disengaged from the star 52 of the date wheel. The user can change the time zone, resulting in a date change, since the star can be driven counterclockwise at this moment. It should be noted that the state of the triggering system 60 corresponds to a local time close to midnight, since the feeler 68 of the rocker 66 is positioned at the top of the cam 64. At this moment, the follower 74 of the pawl 70 is upstream of the first straight segment 76a of the groove 76.

[0053] When the state of the triggering system 60 corresponds to midnight, local time, under the action of the rocker spring, the rocker 66 falls from the top of the cam until the feeler 68 comes into contact with the beginning of a transition portion of the cam as illustrated by the figures 4b and 4cThis movement sequence is performed instantaneously, i.e., in a few milliseconds. During this sequence, the follower 74 moves along the first portion 76a of the groove, which allows the drive member 70 to be oriented so that the finger 72 can engage a tooth of the date star 52.

[0054] This seven-toothed star wheel, cooperating with the jumper 54, causes each instantaneous jump of the rocker 66 to rotate the date star 52 and the date wheel 50 by one-seventh of a turn. The gear ratio between the date wheel 50 and the date crown 46 has been determined so that the date indicator 45 is driven by one-thirty-first of a turn with each jump of the date star 52.

[0055] Once the jump is made, cam 64 will gradually arm the triggering system 60 over twenty-four hours. As illustrated by the figures 4e, 4f And 4a, the follower 74 moves, during this time interval, along a portion 76b of the groove allowing the drive member 70 to be oriented so that the finger 72 is always clear of the date star 52 in order to allow at any time a correction of the time zone resulting in a date adjustment, or even a setting correction

[0056] Various modifications can be made to the timepiece without departing from the scope of the invention as defined by the attached claims. For example, according to an alternative embodiment, the date correction mechanism's triggering system may include a pawl having two predefined positions: an engaged position to actuate the date star and a disengaged position. This pawl may be controlled by engagement and disengagement stops, in addition to a jump spring or a bistable blade, holding the pawl in the engaged position when the rocker falls and in the disengaged position when the rocker rises.

[0057] According to another, unillustrated embodiment, the date-correcting mechanism's release system may include a finger arranged to wind for 24 hours and then instantly release to move directly to a resting position outside the teeth of the date star. An example of this type of mechanism is disclosed in CH707439B1. Reference list

[0058] Clockwork component 10 City disc 12 Twenty-four-hour disc 14 Driving element 16 (e.g., crown) Disc support 18 Teeth 19 Actuating element 20 Main gear 22 Star 24 First gear 26 Second gear 28 Driving wheel 30 Depth wheel 32 First rocker arm 34 Pivot axis A Arm 36 Actuating part 38 Second rocker arm 40 Pivot axis B Finger 42 Connecting element 44 Date display mechanism Indication support 45 Date crown 46 Date indicator (e.g., date window 48) Date wheel 50 Date star 52 Jumper 54 Correction wheel 56 Correction star 58 Triggering system 60 Twenty-four-hour wheel 62 Cam 64 Rocker arm 66 Feeler 68 Drive element 70 Finger 72 Follower 74 (e.g., pin) Groove 76 First portion 76a Second portion 76b Jumper 77

Claims

1. Timepiece (10) with universal time, comprising a city disc (12), a twenty-four-hour disc (14), a hour indicator, a disc support (18) secured to the city disc (12) so as to rotate therewith, a drive member (16) secured to the twenty-four-hour disc (14) so as to rotate therewith and arranged to be driven in rotation at a rate of one revolution in twenty-four hours, a time zone correction mechanism intended to drive in rotation the city disc (12), the twenty-four-hour disc (14) and the hour indicator at each time zone correction, and a date display, the date display comprising an indicator holder (45) bearing date indications, a date indicator (48), and a date correction mechanism comprising a release system (60) arranged to cause, each day, a first displacement of the date indicator (48) relative to the indicator holder (45) in one direction, the date correction mechanism further comprising an actuating element (20) secured to the disc support (18) to cause a second displacement of the date indicator (48) relative to the indicator holder (45) in the opposite direction when a time zone correction results in the date being set back.

2. Timepiece (10) according to claim 1, wherein the date indicator (48) or the indicator holder (45) is kinematically connected to a date star (52), the release system (60) being configured to rotate the date star (52) in a first direction in order to cause said first displacement, the actuating element (20) of the disc support (18) being arranged to rotate, indirectly, the date star (52) in a second direction opposite to the first direction to cause said second displacement.

3. Timepiece (10) according to the preceding claim, wherein the indicator holder is in the form of a date disc (45), the date indicator (48) or the date disc (45) being rotationally secured to a date crown (46) meshing with a date wheel (50) secured to the date star (52).

4. Timepiece according to the preceding claim, wherein the date correction mechanism further comprises a correction wheel (56) meshing with the date wheel (50), and a correction star (58) secured to the correction wheel (56) so as to rotate therewith, the actuating element (20) being arranged so as to be able to engage a tooth of the correction star (58) to cause said second displacement.

5. Timepiece (10) according to any one of claims 2 to 4, wherein the release system (60) comprises a twenty-four-hour wheel (62) arranged to complete one revolution in twenty-four hours, a cam (64) connected to the twenty-four-hour wheel (62), a lever (66) arranged to cooperate with the cam (64) in order to effect one jump per day, and a finger (72) for driving the date star (52) in the first direction at each jump of the lever, the finger (72) being mounted movably on the laver so as to be disengaged from the date star (52) when the date star (52) is rotated in the second direction by the actuating element (20).

6. Timepiece (10) according to the preceding claim, wherein the release system (60) further comprises a drive member (70) mounted so as to pivot on the lever (66) and comprising the finger (72).

7. A timepiece (10) according to the preceding claim, wherein the drive member (70) comprises a follower (74) arranged to move within a groove (76) along a closed path, the groove comprising a first portion (76a) acting on the follower (74) to pivot the drive member (70) on the lever (66) so that the finger (72) can engage a tooth of the date star (52) at each jump of the lever.

8. Timepiece (10) according to the preceding claim, wherein the groove comprises a second portion (76b) acting on the follower (74) to pivot the drive member (70) on the lever so that the finger (72) is disengaged from the date star (52) once the lever has completed its jump and until the next jump.

9. Timepiece (10) according to one of the preceding claims, wherein the time zone correction mechanism comprises a first lever (34) arranged to rotate the drive member (16) of the twenty-four-hour disc (14) and the hour indicator, and a second lever (40) arranged to rotate the disc support (18) of the city disc (12), the two levers (34, 40) being arranged to cooperate with a control member moving in a first direction and then in a second, opposite direction in order to return to its initial position, such that one of the levers (34, 40) can drive one of said support (18) and said drive member (16) when the control member is actuated in the first direction, and in that the other of the levers (34, 40) can actuate the other of said support (18) and said drive member (16) when the control member moves in the second direction.

10. A timepiece (10) according to the preceding claim, wherein the two levers (34, 40) are connected to one another by a connecting member (44).

11. A timepiece (10) according to claim 9 or 10, wherein the support of the city disc (12) takes the form of a first crown (18) arranged to be rotated by one of the two levers (34, 40), the drive member (16) being in the form of a second crown (16) arranged to be rotated by the other of the two levers (34, 40).

12. Timepiece (10) according to the preceding claim, wherein the second crown (16) meshes with a drive wheel (30) arranged to be rotated by the other of the two levers (34, 40).

13. Timepiece (10) according to the preceding claim, wherein the second crown (16) is further kinematically connected to a wheel (22) of a main gear train, said wheel (22) being connected to a five-toothed star gear cooperating with a lever (77) so that the rotational actuation of the drive wheel (30) causes the twenty-four-hour crown (16) to turn by one twenty-fourth of a turn and the hour indicator to turn by one twelfth of a turn.