Patent Publication Number: US-10775744-B2

Title: Timepiece comprising a day/night display that takes account of seasonal variations

Description:
This application claims priority from European Patent Applications No. 16206863.9 filed on Dec. 23, 2016 and Ser. No. 17/195,835.8 filed on Oct. 11, 2017, the entire disclosure of which is hereby incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention concerns a timepiece comprising a timepiece movement and sunrise and sunset indicating means that take account of seasonal variations, said means comprising a sphere that replicates the terrestrial globe, a support, and a ring mounted on the support and arranged concentrically to the sphere, the ring being arranged to indicate the position of the earth&#39;s terminator, and the ring and the sphere being arranged to be able to rotate with respect to each other, at a rate of one revolution in 24 hours, about a first axis corresponding to the polar axis of the terrestrial globe, and to be able to pivot with respect to each other about a second axis intersecting the first axis perpendicularly at the centre of the sphere, the ring being mounted to pivot on the support about the second axis, the sunrise and sunset indicating means further comprising an annual cam that has a profile representative of the tilt of the sun with respect to the equatorial plane, and is arranged to be driven in rotation at a rate of one revolution per year, a cam follower arranged to cooperate with the cam, and a kinematic chain arranged to connect the cam follower to the ring, such that the plane subtended by the ring forms with the first axis an angle equal to the relative angle of tilt of the sun with respect to the equatorial plane. 
     PRIOR ART 
     The duration of the day is the time comprised, each day, from the moment when the upper limb of the sun appears above the horizon in the east, at sunrise, until it disappears below the horizon in the west, at sunset. Whatever the time, there is always one half of the earth&#39;s surface which is illuminated by the sun, and another half which is in darkness. The earth&#39;s terminator is the line of demarcation between the portion of the earth which is illuminated and that which is in darkness. Geometrically speaking, the earth&#39;s terminator is a large circle which encircles the earth. This large circle extends in a plane perpendicular to the plane of the earth&#39;s orbit around the sun (called the ecliptic plane). It is also noted that the centre of the earth is on the line of intersection between these two planes. 
     Generally, the length of day varies throughout the year and also depends on latitude. This variation is caused by the tilt of the axis of rotation of the earth on itself with respect to the ecliptic plane. This tilt by definition corresponds to the latitude of the tropics which is ±23° 27′. As is well known, the length of day is shortest at the December Solstice in the Northern Hemisphere, and at the June Solstice in the Southern Hemisphere. At the equinoxes, the length of day and night are equal everywhere on earth. 
     There are already known timepieces arranged to indicate the current position of the boundary between day and night and which meet the definition given in the above preamble. Descriptions are found, in particular, in European Patent documents EP2911013, EP2977832 and EP3007012 in the name of the Applicant. However, the use and the design of these timepieces present a certain number of difficulties. 
     In particular, the ring and the terrestrial globe are arranged to be driven by the movement in order to rotate with respect to one another, at a rate of one revolution in 24 hours, so as to provide an indication of the current position of the earth&#39;s terminator on the surface of the globe. In this regard, it will be understood that, since the hour wheel of a timepiece normally completes one revolution in 12 hours, it may advantageously serve as the driving element for this rotation. This simply requires combining the hour wheel with, for example, a reduction gear having a ratio equal to 1:2. However, one problem with such a configuration is that, when the hands of the timepiece are acted on to change from summer time to winter time, for example, the indication of the current position of the earth&#39;s terminator on the globe is moved, although this does not reflect an actual movement of the sun in the sky. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the present invention to overcome the aforementioned drawbacks of the prior art. The invention achieves this object by providing a timepiece movement. 
     According to the invention, the timepiece movement comprises a manually actuatable time change mechanism arranged to pivot the hour wheel set, step-by-step, independently of the motion work. Those skilled in the art will understand that one advantage of such a correction mechanism is that it makes it possible to change time zones or switch between summer time and winter time, without affecting the indication of the minutes and the indication of the seconds by the timepiece. 
     According to the invention, the timepiece movement also comprises, on the one hand, a second kinematic chain which connects the hour wheel set to the ring or to the sphere, so as to drive the ring or the sphere such that one rotates with respect to the other at a rate of one revolution in 24 hours, and comprises, on the other hand, a disengagement mechanism arranged to disengage the second kinematic chain when the time change mechanism is implemented to pivot the hour wheel set to change from summer time to winter time, or vice versa. One advantage of such an arrangement is that the rotation of the ring or of the sphere, with respect to one another, at a rate of one revolution in 24 hours, is not affected by any summer time/winter time correction. 
     Also according to the invention, the timepiece comprises a calendar mechanism comprising means for displaying the date, arranged to be driven via the hour wheel set, and a month display arranged to be driven by the means for displaying the date. Further, the annual cam is arranged to be driven via the means for displaying the date. One advantage of this design is that, after an indeterminate period of stoppage of the timepiece, the annual cam can automatically be returned to the correct position without any possible error, simply by resetting the date of the calendar mechanism. 
     According to the invention, the date display means are driven by the hour wheel set. In these conditions, when the wearer of the timepiece pivots the hour wheel set, step-by-step, forwards or backwards, with the aid of the time change mechanism, the hour correction automatically results in correction of the calendar mechanism. 
     According to an advantageous variant of the invention, the timepiece movement comprises a first hour wheel meshing with the motion work and referred to as the ‘motion-work hour wheel’, and a second hour wheel, referred to as the ‘hour-wheel’, which forms part of the hour wheel set. Further, the time change mechanism comprises a coupling and indexing device which is disengageable and which is arranged to alternatively disengage and make integral in rotation the first and second hour wheels. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the invention will appear upon reading the following description, given purely by way of non-limiting example, with reference to the annexed drawings, in which: 
         FIG. 1  is a block diagram briefly illustrating the kinematic connections between different mechanisms of a timepiece according to a first particular embodiment of the invention; 
         FIG. 2  is a block diagram briefly illustrating the kinematic connections between different mechanisms of a timepiece according to a second particular embodiment of the invention; 
         FIGS. 3A and 3B  are respectively a cross-sectional view and a view of an example mechanism, known as such, which comprises a first and a second hour wheel and a disengageable coupling device arranged to make integral in rotation and index, or alternatively to disengage, the two hour wheels. 
         FIGS. 4 a  and 4 b    are views of structural elements of the timepiece. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       FIG. 1  annexed is a block diagram illustrating the kinematic connections associating different mechanisms of a timepiece according to a first exemplary embodiment of the invention. This extremely basic block diagram represents the means for transmitting the driving force provided by the movement to the various mechanisms with the aid of double-thickness arrows, and represents the kinematic connections which are arranged to transmit the commands manually inputted by a user with the aid of thinner arrows. 
     In the block diagram of  FIG. 1 , the arrows symbolise kinematic connections which, between them, connect symbols that represent different mechanisms of the timepiece. The mechanisms represented by the symbols are a drive mechanism  103  that combines a drive member, a regulating member and an escapement, a minute wheel set (referenced  105 ) which is integral with a minute display member and which is arranged to be driven at a rate of one revolution per hour by the drive mechanism, an hour wheel set  107  integral in rotation with an hour display member, a motion work  106  connecting the minute wheel set to the hour wheel set, such that the latter is driven at the rate of one revolution every 12 hours, and a time change mechanism (referenced  101 ) inserted between motion work  106  and hour wheel set  107 . In the illustrated example, the hour wheel set is arranged to make one complete revolution every 12 hours. It will be understood, however, that according to the invention, the hour wheel set could alternatively be arranged to rotate at a rate of one revolution every 24 hours. 
     Still referring to  FIG. 1 , it can be seen that the illustrated timepiece further comprises a calendar mechanism  121  which comprises, in particular, means for displaying the date  123 , arranged to be driven via hour wheel set  107 , and a month display  125  arranged to be driven by the date display means via monthly drive means (referenced  127  in  FIG. 1 ). According to the first embodiment forming the subject of the present description, the date display means  123  comprise a date wheel (not shown), and monthly drive means  127  are arranged to increment month display  125  each time that the date wheel passes from the position corresponding to the last day of the month to that corresponding to the first day of the following month. Calendar mechanism  121  of the present description is preferably a perpetual calendar or an annual calendar mechanism. It should be recalled that, as is well known to those skilled in the art, a perpetual calendar mechanism is a mechanism that automatically takes account of the different lengths of the months and leap years, and that, unlike the perpetual calendar, the annual calendar does not take account of February, which is considered to be a month of 30 days, or leap years. The annual calendar mechanism therefore has to be manually corrected once a year, at the end of February. Since perpetual calendar and annual calendar mechanisms are well known to those skilled in the art, the operation of calendar mechanism  121  will not be described in detail. It is further specified that the invention is not limited to timepieces comprising a perpetual or annual calendar mechanism. The calendar mechanism could also be of a different type. 
     According to the invention, the illustrated timepiece also comprises means for indicating the sunrise and sunset that take account of seasonal variations. These means comprise a sphere replicating the terrestrial globe, a support, and a ring mounted on the support concentrically to the sphere and arranged to indicate the position of the earth&#39;s terminator. The ring and the sphere are arranged to be driven in order to rotate with respect to one another, at a rate of one revolution in 24 hours, about a first axis corresponding to the polar axis of the terrestrial globe. Further, the ring is mounted on the support in order also to be able to pivot relative to the sphere about a second axis intersecting the first axis perpendicularly at the centre of the sphere. The sunrise and sunset indicating means further comprise an annual cam having a profile representative of the relative tilt of the Sun with respect to the equatorial plane and arranged to be driven in rotation at the rate of one revolution per year, a cam follower arranged to cooperate with the cam, and a first kinematic chain arranged to connect the cam follower to the ring, such that the plane subtended by the ring forms, with the first axis, an angle equal to the tilt angle of the Sun with respect to the equatorial plane. Referring to  FIG. 1 , it can be seen that, in the embodiment represented, the timepiece comprises a sunrise and/or sunset indicating mechanism which comprises a sphere  117  representing the terrestrial globe and a half-spherical shell  113 , which is arranged concentrically to sphere  117  so as to darken or conceal one half of the terrestrial globe. Shell  113  has a substantially circular rim  113   a , and it will be understood that this rim forms said ring of the sunrise and sunset indicating means according to the invention. Still referring to  FIG. 1 , it can also be seen that the annual cam is referenced  111  and that it forms part of a tilt control mechanism (generally referenced  109 ). It will be understood that the cam follower (not represented) also forms part of the tilt control mechanism. 
     According to the invention, the date display means  123  are arranged to drive annual cam  111  via a third kinematic chain  118 . As already mentioned, date display means  123  of the present example comprise a date wheel (not represented), and third kinematic chain  118  takes the form of a reduction gear train arranged downstream of the date wheel and having a gear ratio of 1:12. In the present example, the reduction gear train comprises a 16-tooth pinion integral with the date wheel, a 48-tooth wheel meshing with the 16-tooth pinion and integral with a 14-tooth intermediate pinion, which in turn meshes with a 56-tooth wheel integral with annual cam  111  (the wheels and pinions are not illustrated in the diagram of  FIG. 1 ). The annual cam is thus arranged to make one revolution while the date wheel makes twelve revolutions. It will thus be understood that annual cam  111  and calendar mechanism  121  are arranged to advance synchronously. 
     According to the embodiment of the invention illustrated in  FIG. 1 , the movement of half-spherical shell  113  relative to sphere  117  is the result of the combination of distinct rotations about two perpendicular axes that intersect at the centre of the sphere. The first of these two rotations is made by sphere  117 , which is arranged to rotate at the rate of one revolution in 24 hours about the first of these two axes, and the other rotation corresponds to the pivoting of the half-spherical shell representing the dark  113  (dark half sphere) about the second axis and manifests as a variation in the angle of tilt of the half-sphere with respect to the first axis. Since the movements of dark half-sphere  113  and of sphere  117  with respect to one another are two functionally independent movements, sunrise and/or sunset indicating mechanism  115  is represented twice in  FIG. 1 . Referring to the Figure, it will be understood that mechanism  115  is represented once to depict the rotation of sphere  117  at the rate of one revolution in 24 hours about the first axis, and a second time to depict the pivoting of dark half-sphere  113  about the second axis. 
     According to the invention, the pivoting motion about the second axis is controlled using annual cam  111 , whose profile is representative of the tilt of the sun above or below the equatorial plane. The cam follower (not represented) is arranged to transmit the variations in the cam profile to half-spherical shell  113  through a first kinematic chain  112 . According to the first embodiment of the invention, dark half-sphere  113  is mounted to pivot on a fixed support and the arrangement of indicator mechanism  115 , like that of first kinematic chain  112 , may conform, for example, to the description given in European Patent document EP 2911013. This document is incorporated by reference in the present description. 
     According to the present embodiment of the invention, hour wheel set  107  is connected to sphere  117  by a kinematic chain  120  (hereinafter ‘second kinematic chain  120 ’). The second kinematic chain is arranged to drive the sphere in rotation so that it rotates about a first axis corresponding to the polar axis of the terrestrial globe, at the speed of one revolution in 24 hours.  FIG. 1  also shows a disengagement mechanism  133  arranged to disengage on demand second kinematic chain  120 . See also  FIGS. 4A and 4B . 
     Referring again to  FIG. 1 , it can be seen that the timepiece whose operation is represented also comprises a certain number of corrector mechanisms which are arranged to be manually actuated by the wearer of the timepiece. First of all, as already mentioned, a time change mechanism (referenced  101 ) is inserted between motion work  106  and hour wheel set  107 . As will now be explained, mechanism  101  can be controlled in two different ways depending upon whether the time change relates to an actual change of longitude, following a journey for example, or relates to the change from winter time to summer time, or vice versa. In the illustrated example, when the wearer of the timepiece changes time zone during a trip, he can correct the time indication by means of control stem  131  of the timepiece. In order to do this, he must pull stem  131  out into position T 2  before rotating the crown to move the hour hand forwards or backwards in a series of one-hour jumps. As was seen above, hour wheel set  107  drives calendar mechanism  121  and annual cam  111 . Further, hour wheel set  107  also drives sphere  117  in its rotation about the first axis. It will thus be understood that annual cam  111 , calendar mechanism  121  and sunrise and/or sunset indicating mechanism  115 , are arranged to advance synchronously, not only when they are driven by means of drive mechanism  103 , but also when they are manually driven forwards or backwards by means of control stem  131  in position T 2 . 
     In the illustrated example, at the change from winter time to summer time or from summer time to winter time, the wearer of the timepiece can move the time indication exactly one hour forward or back by pressing on pusher P 2 . Pressing on pusher P 2  not only actuates time change mechanism  101 , but also simultaneously actuates disengagement mechanism  133 , so as to disengage second kinematic chain  120 , as shown in  FIG. 4B . It will be understood that disengaging the second kinematic chain at the change from summer time to winter time, or vice versa, prevents the movement of the hour hand affecting the relative angular position of dark half-sphere  113  with respect to sphere  117 . 
     In addition to time change mechanism  101 , the timepiece of the present example comprises a conventional type of time-setting mechanism. This time-setting mechanism allows the wearer of the timepiece to set the time by using control stem  131 . In order to do this, he must move stem  131  into position T 3  before rotating the crown. As in most current timepieces, the time-setting mechanism is arranged to drive motion work  106 , which in turn drives minute wheel set  105  and hour wheel set  107 . As was the case previously with the correction of the time zone, hour wheel set  107  drives calendar mechanism  121  and annual cam  111  via third kinematic chain  118 . Further, hour wheel set  107  also drives sphere  117  in its rotation about the first axis. It will thus be understood that annual cam  111 , calendar mechanism  121  and sunrise and/or sunset indicating mechanism  115 , are arranged to advance synchronously, also when they are driven manually forwards or backwards by means of control stem  131  in position T 3 . 
     Finally, the calendar mechanism of the timepiece of the present embodiment also comprises a mechanism for correcting month display  125  of calendar mechanism  121 . When the wearer of the timepiece wishes to correct the month indication, for example following an indeterminate period of stoppage of the timepiece, he can advance the month indication step-by-step by actuating pusher P 1 . According to the present example, actuation of pusher P 1  by the timepiece wearer has the effect of driving date wheel  123  in rotation at high speed. The correction mechanism is arranged such that a single press on the pusher is sufficient to advance the date wheel one complete revolution if required. However, a movable stop, also comprised in the correction mechanism, has the function of stopping the date wheel as soon as the latter reaches the angular position corresponding to the indication of the first day of the month, after passing the 31st day of the month. On passing from the last day of the month to the first day of the following month, the date wheel actuates monthly drive means  127 , which has the effect of incrementing month display  125 . It will thus be understood that this month display correction mechanism has the advantage of allowing the link between the date and the month to be retained during the correction. The correction mechanism that has just been explained is known as such. It is described in European Patent publication EP2503410 entitled “Calendar mechanism comprising a quick month corrector”. This document is incorporated by reference in the present patent application. 
     As already explained, the date display means  123  are arranged to drive annual cam  111  via a third kinematic chain  118 . Further, according to the first embodiment, third kinematic chain  118  takes the form of a reduction gear train arranged downstream of the date wheel and having a gear ratio of 1:12. In these conditions, it will be understood that, since the month correction is combined with a quick advance of the date, the month display correction mechanism simultaneously corrects the angular position of annual cam  111 . 
       FIG. 2  annexed is a very similar block diagram to that of  FIG. 1 , but illustrating the kinematic connections associating different mechanism of a timepiece according to a second exemplary embodiment of the invention. As will be seen, the second embodiment is very similar to the first and, in particular, both the calendar mechanism and the correction mechanisms arranged to be actuated by the wearer of the timepiece are identical to those which were described in relation to the first embodiment.  FIG. 2  represents a drive mechanism  203  that combines a drive member, a regulating member and an escapement, a minute wheel set (referenced  205 ) which is integral with a minute display member and which is arranged to be driven at the rate of one revolution per hour by the drive mechanism, an hour wheel set  207  integral in rotation with an hour display member, a motion work  206  connecting the minute wheel set to the hour wheel set, such that the latter is driven at the rate of one revolution every 12 hours, and a time change mechanism (referenced  201 ) inserted between motion work  206  and hour wheel set  207 , a tilt control mechanism (referenced  209 ) which comprises an annual cam  211  and a cam follower (not represented), and finally a sunrise and/or sunset indicating mechanism (referenced  215 ) comprising a sphere  217  that replicates the terrestrial globe and a half-spherical shell  213 , which is arranged concentrically to the sphere. 
       FIG. 2  also shows a calendar mechanism  221  which comprises, in particular, means for displaying the date  223 , arranged to be driven via hour wheel set  207 , and a month display  225  arranged to be driven by the date display means via monthly drive means (referenced  227 ). According to the second embodiment forming the subject of the present description, the date display means  223  comprise a date wheel (not shown), and monthly drive means  227  are arranged to increment month display  225  each time that the date wheel passes from the position corresponding to the last day of the month to that corresponding to the first day of the following month. As was the previously the case with regard to the first embodiment, calendar mechanism  221  of the timepiece according to the second embodiment is preferably a perpetual calendar or annual calendar mechanism. Further, according to the invention, date display mechanism  223  is arranged to drive annual cam  211  via a third kinematic chain  218 . In the illustrated example, the third kinematic chain could be identical to kinematic chain  118  described above in relation to the first exemplary embodiment. 
     In the second embodiment, as in the first, the relative movement of half-sphere  213  and sphere  217  is the result of the combination of distinct rotations about two perpendicular axes that intersect at the centre of the sphere. However, according to the second embodiment, it is dark half-sphere  213  which simultaneously makes the two rotations, since sphere  217  is not driven. This operating mode is made possible by the fact that the support (not represented), on which dark half-sphere  213  is mounted, is a rotating support. Still referring to  FIG. 2 , it will be understood that in the illustrated embodiment, hour wheel set  207  is connected to the rotating support (not represented) by a kinematic chain  220  (hereinafter ‘second kinematic chain  220 ’). The arrangement of indicator mechanism  215  and that of second kinematic chain  220  could, for example, conform to the description in one or other of European Patent documents EP2977832 and EP3007012. These two documents are incorporated by reference in the present description. 
     Referring again to  FIG. 2 , it can be seen that a reference mechanism  216  is inserted between tilt control mechanism  209  and indicator mechanism  215 . It can be seen that mechanism  216  comprises an output connected to indicator mechanism  215 , and two inputs. A kinematic connection  221  (referred to as the ‘fourth kinematic chain’  221 ) connects hour wheel set  207  to the first of the two inputs. Mechanism  216  is thus driven by the hour wheel set through its first input, called the ‘driving input’. It can also be seen that the cam follower (not represented) is connected to the second input by a kinematic chain  212  (referred to as the ‘first kinematic chain’  212 ) arranged to transmit the variations in the cam profile. Mechanism  216  is thus controlled by the profile of cam  211  through its second input, called the ‘control input’. Just like second kinematic chain  220 , the output of mechanism  216  is arranged to drive indicator mechanism at a speed of one revolution in 24 hours. However, mechanism  216  drives the indicator mechanism with an offset with respect to second kinematic chain  220 . Mechanism  216  can be realized in many ways without departing from the scope of the present invention. It may, for example, be a differential mechanism, especially a differential mechanism as described in European Patent No EP 2977832. It may also be a disengagement mechanism, especially a disengagement mechanism as described in European Patent No EP3007012. 
     Referring now to  FIGS. 3A and 3B , the time change mechanism, which is generally designated by the reference  101 , will now be described in more detail. It will be recalled that mechanism  101  was already represented in  FIG. 1 , inserted between motion work  106  and hour wheel set  107 . Moreover, mechanism  201  represented in  FIG. 2  could be identical to mechanism  101 . Mechanism  101  comprises a first pipe  2 , called the inner pipe, intended to be mounted in rotation in a conventional manner, about an axis of rotation X, on a cannon-pinion C driven by drive mechanism  103  (shown in  FIG. 1 ). Inner pipe  2  bears an indicator hand  4  forming the hour hand, which is externally pressed onto a free end of pipe  2  projecting from mechanism  101 . 
     Inner pipe  2  thus forms an hour pipe, and it carries a first externally toothed wheel  6 , called the lower wheel, comprising a plate  7 . It will be specified here that, advantageously, this lower wheel  6  forms an hour wheel, and it meshes with a wheel  8  (partially represented) of motion work  106  ( FIG. 1 ). In normal operation, this hour wheel  6  receives time information delivered by wheel  8  of the motion work, which information it transmits, as will be seen below, indirectly to inner hour pipe  2  and to indicator hand  4 . Indeed, lower hour wheel  6  is mounted for free rotation on hour pipe  2 . For this purpose, the end of hour pipe  2 , opposite to the free end thereof carrying hand  4 , comprises a collar  10  forming a shoulder freely supporting a star-wheel  12  on which wheel  6  is fixedly held. Star-wheel  12  comprises a plate  13 , an external toothing  14  and a circular flange  16  arranged edgewise adjacent to toothing  14 , behind and coaxially with the latter, underneath plate  13 . 
     Hour wheel  6  is fixedly held on the side of star-wheel  12  against its toothing  14 . Indeed, hour wheel  6  is force fitted externally onto flange  16 , pressed and/or riveted thereon, via the central part of its plate  7  which has a bore opening. Star-wheel  12  and hour wheel  6  are thus directly integral in rotation and, in this example, as a result of their assembly, form a single piece placed on hour pipe  2 . Star-wheel  12  and hour wheel  6  can thus be moved together concomitantly via wheel  8  of the motion work. 
     The time change mechanism also comprises two drive rollers  20  which are stepped and which each have a cylindrical base  22  from which a stud  24  extends in a perpendicular manner. The rollers are both engaged at rest, via their base  22 , in toothing  14  of star-wheel  12  and they rest freely and sideways via this base against the side (unreferenced) of plate  7  of hour wheel  6 . This rest position is also represented in a top view in  FIG. 2B . Rollers  20  are also resiliently held in this rest position in toothing  14 , by elastic return means  26 , which are formed here by a closed annular spring, mounted coaxially to star-wheel  12  and acting radially on the outer periphery of bases  22  of rollers  20 . It will be noted here that spring  26  is freely mounted against drive rollers  20 , without any fixed attachment to mechanism  1 . Spring  26  also rests freely against, and more particularly on, plate  7  of hour wheel  6 . Spring  26  is thus self-supported and self-centering. 
     The time change mechanism further comprises a second pipe  30 , called the outer pipe, which comprises a guide bore  31  and which is mounted externally via this bore  31  onto first pipe  2 . This second pipe  30  carries a second externally toothed wheel  32  arranged above lower hour wheel  6  and called the ‘upper wheel’. It will be specified here that the upper and lower positions of wheels  6  and  32  refer to the drawing of  FIG. 3A , which represents the correction mechanism with the hour hands oriented upwards. Upper wheel  32  comprises a plate  33  and it meshes via its outer toothing with a wheel  34 , driven in turn by a corrector member, which is manually actuatable from outside the timepiece. 
     Upper wheel  34  thus forms a time change wheel which, as will become clear, can directly correct the position of hour pipe  2  and of indicator hand  4 , without acting on the motion work, and therefore without disrupting the other time information, such as the minutes and seconds, which are normally kinematically connected to hour pipe  2  via said motion work. Advantageously, outer pipe  30  is force fitted externally onto inner hour pipe  2  and it is thus secured thereto. These two pipes are therefore integral in rotation and they can be moved together. It will be understood that hour pipe  2 , outer pipe  30  and upper wheel  34  together form hour wheel set  107 . Upper correction wheel  34  can thus act on inner hour pipe  2  via outer pipe  30 . 
     It will be specified that hour pipe  2  is also driven in normal operation by motion work  106 , and in particular by wheel  8  of the motion work. This is why there are radial grooves  36  arranged in plate  33  of correction wheel  32 , in which are freely engaged studs  24 , which can translate radially in said grooves. Rollers  20  can thus drive in rotation correction wheel  32 , and the two pipes  2  and  30 , when star-wheel  12  is itself driven by hour wheel  6 . 
     In order to change to another time zone, the user of the timepiece must rotate correction wheel  34 ; rollers  20  are then angularly displaced and jump (while star-wheel  12  and hour wheel  6  remain stationary) in toothing  14  of star-wheel  12 , making spring  26  oval. Rollers  20  then return to the rest position in toothing  14  of star-wheel  12 , but are offset with respect to the position of  FIG. 3B . Hand  4  then indicates another time zone. It will be specified that, although the toothing of star-wheel  12  has 12 teeth in the Figures (to indicate the 12 hours), this toothing could have 24 teeth for application to a 24-hour timepiece. 
     It will also be clear that various alterations and/or improvements evident to those skilled in the art may be made to the embodiment forming the subject of the present description without departing from the scope of the present invention defined by the annexed claims.