EP3032349A1 - Drive mechanism of a skipping member - Google Patents

Abstract

The invention relates to a drive mechanism for a jumping member comprising a drive wheel (1), an indicator of a unit of time, a jumping member (6) integral with said indicator and coaxial with said drive wheel. the drive (1) to which said jumping member (6) is coupled by a spring (8), a cam (12) arranged to tilt an anchor (20) in an oscillating movement so as to release the jumping member (6). ) once per unit of time. According to the invention the cam (12) and the jumping member (6) have distinct pivot axes, the drive mechanism further comprising an intermediate gear kinematically linking the drive wheel (1) to the cam (12). ), and the anchor (20) has four distinct arms (20a, 20b, 20c, 20d), two (20a, 20b) of the four arms constituting feelers arranged to cooperate with the cam (12) and the other two arms ( 20c, 20d) constituting exhaust arms arranged to successively block and release once per unit time the jumping member (6) alternately.

Description

Field of the invention

The invention relates to the field of mechanical watchmaking. It relates, more particularly, to a drive mechanism of a member jumping in a timepiece comprising a drive wheel arranged to rotate at a constant speed, an indicator of a unit of time, a jumping member integral with said indicator and coaxial with said drive wheel to which said jumping member is coupled by a spring, a cam arranged to control an anchor, said cam having a profile arranged to tilt the anchor in an oscillating movement so as to release the organ jumping once per unit of time. The present invention also relates to a timepiece comprising such a mechanism for driving a jumping member.

Background of the invention

When the drive wheel is one revolution per minute, the unit of time may be the second. The drive mechanism can then be a dead second mechanism, arranged to release the jumping member once per second. A dead second mechanism includes a dead second indicator, usually a large hand in the center of the dial, which is 1 jump per second. These mechanisms are extremely complicated realization. However, they sometimes lack accuracy, the jumps taking place in some cases to 5/6 of a second. They are also very energy consumers.

Some of these mechanisms are powered by a second source of energy, specific to the second dead mechanism, in addition to the main source of energy required for movement.

Other mechanisms are powered by the energy source of the movement, of the type described in the preamble. Such mechanisms are known to those skilled in the art and described for example in the patent CH 311865 . In these mechanisms, the dead second cam includes a large number of teeth (30), involving small angular steps, which makes the jumps very sensitive to the imperfections of the dead second cam. In addition, the same pallet of the dead second anchor is used both to cooperate with the dead second cam and the second wheel. The dead second anchor blocks the jumping member due to the force of the coupling spring and friction. This friction absorbs a relatively large power, so that the power consumption by the second dead mechanism is high.

Summary of the invention

The invention particularly aims to overcome the various disadvantages of the known mechanisms.

More specifically, an object of the invention is to provide a mechanism for driving a jumping member, and in particular a dead second mechanism, reliable, allowing to have precise jumps at each unit of time, and in particular at each second.

The invention also aims to provide a mechanism for driving a jumping member, and in particular a second dead mechanism for having regular jumps throughout its life.

The invention also aims to provide a mechanism for driving a jumping member, and in particular a mechanism for second dead, allowing a reduced energy consumption, allowing the use of the same source of energy as that of the movement.

For this purpose, the present invention relates to a drive mechanism of a jumping member comprising a drive wheel arranged to rotate at a constant speed, an indicator of a unit of time, a jumping member integral with said indicator and coaxial with said driving wheel to which said jumping member is coupled by a spring, a cam arranged to control an anchor, said cam having a profile arranged to tilt the anchor in an oscillating motion so as to release the jumping member once by unit of time.

According to the invention, the cam and the jumping member have distinct pivoting axes, said drive mechanism further comprising an intermediate gear cinematically linking the drive wheel to the cam, and the anchor has four distinct arms, two of the four arms constituting feelers arranged to cooperate with the cam and the other two arms constituting exhaust arms arranged to successively block and release once per unit of time alternating jumping member.

Advantageously, the intermediate wheel may comprise an intermediate mobile formed of an intermediate gear arranged to cooperate with the drive wheel and an intermediate wheel arranged to cooperate with a camming wheel integral with the cam.

Preferably, the intermediate gear can be sized so that the cam comprises less than thirty teeth, each tooth having a front ramp, and performs more than one revolution per minute.

Advantageously, according to an alternative embodiment, the unit of time is the second, the drive wheel being arranged to turn in 60 seconds, and the indicator being a second dead indicator, the cam can include ten teeth and be arranged to perform three revolutions per minute, each tooth having a front ramp decomposing in six steps.

Preferably, the forward ramp of each tooth of the cam has, on the last three steps of the tooth, a slope greater than the slope of the front ramp on the first three steps of the tooth.

Advantageously, the four arms of the anchor can be arranged to form substantially an X, the probe arm positioned to cooperate with the cam being disposed opposite to the pivot point of the anchor to the arm exhaust positioned to release the jumping member.

Advantageously, said drive mechanism also comprises a mechanism for securing the relative position of the drive wheel and the jumping member.

Preferably, the mechanism for securing the relative position of the drive wheel and the jumping member may comprise first support means provided on the drive wheel and a first stop provided on the jumping member, said first support means being arranged to bear on the first stop and limit the stroke of the jumping member, when the drive wheel and the jumping member rotate in opposite directions.

Preferably, the mechanism for securing the relative position of the drive wheel and the jumping member may comprise second support means provided on the drive wheel and a second stop provided on the jumping member, said second support means being arranged to rest on the second stop and limit the travel of the drive wheel when the jumping member is stopped.

Advantageously, said first and second support means may comprise a pin. In another variant, the first and second support means may comprise an eccentric.

Advantageously, the jumping member may be a wheel having at least two recessed areas separated by at least one arm, and the first and second support means are arranged on either side of the arm, said arm constituting at least one of the first and second stops on which the first and second support means are able to rely respectively.

The drive mechanism of a jumping member according to the invention allows to have precise jumps at each unit of time while allowing a reduced power consumption. In addition, jumps will be regular throughout the life of the mechanism.

The present invention also relates to a timepiece comprising a watch movement provided with a finishing gear powered by a power source, and a drive mechanism of a jumping member as defined above.

Advantageously, the drive wheel of the second dead mechanism can be powered by the energy source of the movement.

Preferably, the drive wheel may be the second wheel of the work train.

Brief description of the drawings

• les figures 1 à 4 représentent une vue de dessus d'un mécanisme de seconde morte conforme à l'invention, l'ancre de seconde morte occupant différentes positions en fonction des pas d'une dent de la came de seconde morte,
• la figure 5 représente une vue du profil d'une dent de la came de seconde morte,
• la figure 6 est une vue en perspective d'une variante de réalisation du mécanisme de sécurisation de la position relative de la roue d'entrainement et de l'organe sautant, et
• la figure 7 est une vue en perspective de la fixation du ressort-spiral sur l'organe sautant.

Other features and advantages of the invention will appear more clearly on reading the following description of a particular embodiment of the invention, given by way of a simple illustrative and nonlimiting example, and the appended figures, among which: :

• the Figures 1 to 4 represent a view from above of a dead second mechanism according to the invention, the dead second anchor occupying different positions according to the steps of a tooth of the dead second cam,
• the figure 5 represents a profile view of a tooth of the dead second cam,
• the figure 6 is a perspective view of an alternative embodiment of the mechanism for securing the relative position of the drive wheel and the jumping member, and
• the figure 7 is a perspective view of the attachment of the spiral spring to the jumping member.

Detailed description of a preferred embodiment

The following description relates to an embodiment of the invention for which the unit of time is the second. The training mechanism then constitutes "a second dead mechanism", and will be designated thereafter under this expression.

With reference to the figure 1 , the second dead mechanism according to the invention is integrated in a mechanical timepiece, comprising a watch movement provided with a finishing gear powered by a power source, such as a barrel. The finishing gear train traditionally comprises a second wheel 1 comprising 60 teeth and arranged to turn in 60 seconds. The movement also traditionally includes an escape pinion 2 and an escape wheel 3 as well as an escapement anchor and a pendulum. These elements are known to those skilled in the art and do not require a detailed description. Note however that the frequency of the balance is advantageously chosen at 3 Hz, as will be understood below.

The second dead mechanism comprises a drive wheel constituted more specifically here by the second wheel of the finishing gear.

The dead second mechanism also comprises a jumping member 6, such as a wheel, secured to a dead second indicator, such as a needle (not shown). The jumping member 6 is mounted loosely on the axis of the second wheel 1, so that the jumping member 6 is coaxial with the second wheel 1 and not integral with the latter. Jumping organ 6 is elastically connected to the second wheel 1 by means of a spiral spring 8, which is on the one hand driven on the second wheel 1 and secondly fixed on the jumping member 6. According to a first variant, the spring -spiral 8 comprises at its end intended to be fixed on the jumping member 6, a fixing notch 9 in which is inserted a holding pin 11 provided on the jumping member. According to a second variant represented on the figure 7 , the spiral spring 8 comprises at its end intended to be fixed on the jumper member 6, a double fixing notch 32 having two housings or notches. The jumping member 6 is provided with two holding lugs 34, each holding lug 34 being intended to be inserted into one of the housings of the double fixing notch 32. The holding lugs 34 are arranged to limit the axial clearance. . More particularly, each holding pin 34 has a groove around which is positioned each notch. Thus, the double fastening notch ensures that the flatness of the spiral spring 8 is retained during operation of the mechanism. The jumping member 6 is a wheel comprising 30 teeth and making a turn in 60 seconds.

The dead second mechanism also comprises a dead second cam mobile formed of a cam drive wheel 10 and a second dead cam 12, integral with said cam drive wheel 10. The cam drive wheel 10 is arranged to cooperate with the escape pinion 2. More particularly, the cam drive wheel 10 is in direct contact with the escape pinion 2.

According to the invention, the second wheel 1 and the cam drive wheel 10 are pivotally mounted on the frame of the movement so as to have separate pivot axes, so that the dead second cam 12 and the jumping member 6 (or the second wheel 1) are not coaxial.

In addition, the second wheel 1 and the cam drive wheel 10 are kinematically connected by an intermediate wheel, and more particularly an intermediate mobile comprising an intermediate gear 14 meshing with the second wheel 1 and an intermediate wheel 16, integral with said intermediate gear 14, and meshing with the driving cam wheel 10. Thus, the main kinematic chain of the movement goes from the wheel from second 1 to the escape gear 2 passing successively by the intermediate gear and the cam drive wheel 10, without a direct connection between the drive pinion and the second wheel. According to a preferred embodiment, the dimensions and the number of teeth of the intermediate mobile are provided so that the cam drive wheel 10 and the dead second cam 12 perform one revolution per 20 seconds, ie 3 revolutions per minute, the cam driving wheel 10 comprising 66 teeth and the dead second cam 12 comprising 10 teeth 18. It is obvious that the speed of the cam driving wheel and the dead second cam, as well as the number of teeth can be modified without departing from the scope of the present invention. We can choose for example a period of 16 seconds, with a second dead cam with 8 teeth.

The dead second mechanism also includes a second dead anchor 20 pivotally mounted at a pivot point A on the movement frame, and controlled by the second dead cam 12 to release and blow the jumping member 6 once per second. . The jumping member 6 thus constitutes a dead second escape wheel.

According to the invention, the dead second anchor 20 comprises four separate arms 20a, 20b, 20c and 20d. The end of each arm acts as a pallet. In the following description, the term "pallet" is used to designate the end of an arm 20a, 20b, 20c and 20d, the pallet thus forming a single piece with the corresponding arm. Advantageously, the second dead anchor 20 is monobloc and made by LIGA. The upper arm 20a and the lower arm 20b constitute upper and lower probes arranged to cooperate with the cam of second dead 12. The upper arm 20c and the lower arm 20d are upper and lower exhaust arms arranged to successively block and release, once a second, the jumping member 6 alternately. The four arms 20a, 20b, 20c and 20d are positioned relative to the pivot point A so as to form substantially an X, the end of each arm being bent to cooperate with either the dead second cam 12 or with the Jumping member 6. The arms 20a, 20b, 20c and 20d work in opposition to the pivot point A. For example, as shown in FIG. figure 1 the upper feeler arm 20a is positioned to be controlled by the tooth profile 18 of the dead second cam 12 while the exhaust arm opposite from the pivot point A, namely the lower exhaust arm 20d. , is positioned to release the jumping member 6.

Each tooth 18 of the dead second cam 12 has a profile defined by a front ramp 18a, the functional portion of the tooth on which the end or the pallet of the feeler arms 20a, 20b rubs, and a reverse 18b. Advantageously, the frequency of the balance is chosen at 3 Hz (or 6 alternations per second) so that each front ramp 18a can be decomposed into six steps, each step corresponding to a rotation angle of 3 ° of the cam second dead. It is obvious that another frequency can be chosen. A displacement along the front ramp 18a of a tooth 18 corresponding to a rotation angle of 18 ° of the second dead cam. In order to have a precise jump, the front ramp 18a of each tooth 18 has a slope which is higher on the last three steps corresponding to a rotation angle of the second dead cam between 9 ° and 18 °, ie at moment close to the jump, that on the first three steps corresponding to an angle of rotation of the dead second cam between 0 ° and 9 °. As shown more specifically figure 5 , by determining that at the origin of the tooth, for an angle of 0 ° the height is equal to 0, and that the total height of the tooth h corresponds to an angle of rotation of 18 ° of the dead second cam , the height is of the tooth corresponding to the third step, ie a rotation angle of 9 ° of the dead second cam, is between 10% and 15% of the height h, and the height b of the tooth corresponding to the fifth pitch, an angle of rotation 15 ° of the dead second cam, is between 55% and 60% of the height h.

The profile of the reverse 18b avoids the premature jump of the second dead anchor. This profile is the result of the profile of the front ramp 18a, so that when the pallet of one of the feeler arms is in contact with the front ramp 18a of a tooth 18 of the dead second cam 12, a constant clearance is maintained between the dead second cam 12 and the passive pallet of the other probe arm (that is to say the pallet of the probe arm which is not in contact with the ramp before a tooth).

In addition, there is provided a mechanism for securing the relative position of the second wheel 1 and the jumping member 6 to ensure permanent indexing of the second wheel 1 and the jumping member 6, including when the driving mechanism of the jumping member has stopped following the cessation of movement. With reference to the figure 4 , said mechanism for securing the relative position of the second wheel 1 and the jumper member 6 comprises a first pin 30 and a second pin 36 driven on the second wheel 1. Said pins 30 and 36 are shown only on the figure 4 to simplify the drawings. In addition, the jumping member 6 is a toothed wheel having four recessed areas whose edges form four separation arms 6a, 6b, 6c, 6d. The pins 30 and 36 are positioned on the second wheel 1 on either side of one of the separation arms 6a. More particularly, the first pin 30 is positioned so as to be in front of the separation arm 6a of the jumping member 6 when the second wheel 1 and the jumping member 6 rotate in the same direction, especially during operation. normal mechanism. When the second wheel 1 rotates in a direction opposite to that of the jumping member 6, especially when the setting of the time of the movement, the first pin 30, secured to the second wheel 1, is supported on the separation arm 6a of the jumping member 6, the separation arm 6a then constituting a stop for the first pin 30. The first pin 30, continuing its movement with the second wheel 1, drives the separation arm 6a and thus the jumping member 6 in its displacement, so that the second wheel 1 and the jumping member 6 recoil together and remain indexed, especially when setting the time.

The second pin 36 is positioned so as to be at the rear of the separation arm 6a of the jumping member 6 when the second wheel 1 and the jumping member 6 rotate in the same direction, in particular during the normal operation of the mechanism . A margin of at least one step, and preferably equal to one step, is provided. When the jumping member 6 is stopped, for example during the switching, the second pin 36, integral with the second wheel 1, moving in the normal direction, is supported on the separation arm 6a of the jumping member 6, the separating arm 6a then constituting a stop for the second pin 36. The second pin 36 abuts against the jumping member 6 stopped, so that the second wheel 1 stops and consequently the rest of the mechanism. Thus, the second wheel 1 and the jumping member 6 are both stopped and remain indexed, especially when switching.

Thus, the relative position of the second wheel 1 and the jumping member 6 is secured, so that there is no loss of arming on the spiral spring 8.

With reference to the figure 6 another variant of the securing mechanism is shown. According to this variant, the first and second support means comprise an eccentric 38, 40 in place of the first pin 30 and the second pin 36 respectively, their operation being similar. The advantage of the eccentrics 38 and 40 with respect to the pins 30, 36 is that the watchmaker can move them and position to adjust the clearance between the two eccentric 38, 40 and the separation arm 6a of the jumping member 6. This allows less depend on manufacturing tolerances.

According to another variant embodiment not shown, the first support means are positioned so as to be in front of one of the separation arms of the jumping member 6 when the second wheel 1 and the jumping member 6 rotate in the same direction, and the second support means are positioned to be at the rear of another separation arm of the jumping member 6 when the second wheel 1 and the jumping member 6 rotate in the same way. Thus, one of the separation arms of the jumping member 6 constitutes the first stop on which the first support means are able to rest and the other separation arm of the jumping member 6 constitutes the second stop on which the second support means are able to rely.

In another variant embodiment not shown, the first and second stops are not constituted by the separating arms of the jumping member but are parts driven on the jumping member 6 and arranged so as to be able to come into contact with their respective bearing means, in particular pins or eccentrics, provided on the drive wheel.

The operation of the second dead mechanism is as follows: Figures 1 to 5 , the second wheel 1 drives the intermediate gear 14 and thus the intermediate wheel 16, which in turn drives the cam drive wheel 10 and thus the dead second cam 12. Said dead second cam 12, turning, allows the front ramp 18a of a tooth 18 to act on the pallet of the upper probe arm 20a of the dead second anchor 20, so that said anchor 20 tilts around its pivot point A to exit, to the opposite, the pallet of the lower exhaust arm 20d of the second dead anchor 20 of the toothing of the jumping member 6.

More precisely, between step 0, represented on the figure 1 , and the fifth step of the ramp before 18a of the tooth concerned (ie for an angle of rotation of the dead second cam 12 of 15 °, cf. figure 5 ), the pallet of the lower exhaust arm 20d does not come out of the toothing of the jumping member 6, regardless of the clearance clearance. The asymmetric profile of each tooth 18 of the second dead cam 12 is such that the raising of the anchor is done progressively with the pallet of the upper probe arm 20a while the pallet of the lower probe arm 20b descends without touching the dead second cam 12.

When the pallet of the upper arm 20a reaches the fifth step of the ramp before 18a, as shown in FIG. figure 2 , the jumping member 6 has not yet jumped, and is still blocked by the pallet of the lower exhaust arm 20d. Once the pallet of the upper probe arm 20a has arrived at the fifth step of the ramp before 18a, if the dead second anchor 20 undergoes a catch of play following a shock for example, the pallet of the lower probe arm 20b is positioned at the contact 18b of the corresponding tooth 18 of the dead second cam 12, as shown in FIG. figure 3 . Even in this configuration, the jumping organ 6 has not jumped, but remains at the limit of jumping. The jumping member 6 jumps when the pallet of the upper feeler arm 20a moves between the fifth and sixth steps. When the pallet of the upper probe arm 20a arrives at the sixth step of the ramp before 18a, as shown in FIG. figure 4 the jumping organ 6 has jumped. With the dead second anchor tilted, the lower exhaust arm pad 20d disengaged from the jumping member 6 and released it. The jumping member 6, recalled by the spiral spring 8 attached to the second wheel 1, rotates 6 °, either a progress or a jump of one second of the second dead indicator. The jumping member is then again locked this time the pallet of the upper exhaust arm 20c, on which it is held in support by the spiral spring 8, as shown in FIG. figure 4 . This is the pallet of the lower probe arm 20b, opposite to the pivot point A, which will come into contact with the ramp before 18a of a tooth of the dead second cam 12, to tilt the second dead anchor 20 in the other direction and again release the jumping member. Thus, the movement of the dead second anchor is a reciprocating movement that releases, tooth by tooth, the jumping member 6, once with the pallet of the upper exhaust arm 20c, then with the pallet of the arm lower exhaust 20d, successively and alternately. As a result, the dead second indicator advances in increments of 1 second.

The second dead mechanism of the invention allows for precise jumps every second with less energy consumption. Indeed, the mechanism of the invention is powered by the same source of energy as the finishing gear. A second source of energy is not necessary. Furthermore, the arrangement on separate axes of the jumper member and the dead second cam provides optimized shapes for the vanes of the exhaust arms on the one hand and for the pallets of the feeler arms on the other hand , in connection with optimized shapes of the teeth of the dead second cam. The energy consumption due to the spiral spring between the second wheel and the jumping member is almost zero. In particular, the higher the slope of the front ramp of the teeth of the second dead cam will be high on the last three steps of the tooth, the more the jump will be marked and therefore accurate. A lower slope on the first three steps of the tooth makes the angular pitch of the second dead anchor relatively low over this period. The torque consumption is therefore low. The slope on the last three steps is on the contrary more important but must however remain measured in order to avoid over-consumption of torque on the mobile cam second dead. As a result, the angular pitch of the dead second anchor is higher on the last three steps, which allows the jump to be performed over a larger measurement range, and consequently increases the jump accuracy. In addition, the use of a dead second cam with only 10 teeth makes it possible to obtain larger angular steps, and therefore less sensitive jumps to the imperfections of the dead second cam.

All parts of the second dead mechanism directly related to the dead second indicator are hollowed out, in order to lighten them to the maximum and reduce inertia as well as torque consumption. Moreover, these recesses make it possible to balance the parts, in order to obtain an imbalance close to zero.

Furthermore, the radius forming the flank of the toothing of the jumping member is chosen to be concentric and equal to that of the second dead anchor with which it is in contact. As a result, when the dead second anchor tilts, the jumping member does not move, which ensures the stability of the second dead indicator.

Finally, the arrangement on separate axes of the jumping member and the second dead cam makes it possible not to add a large number of parts on the same axis and therefore to limit the accumulation of tolerances and the misalignment of the mobiles, unlike to the coaxial mechanisms of the prior art. The precision on the axis of the jumping member is therefore greater while simplifying the assembly of parts.

It is obvious that the second dead mechanism described above can be adapted to another unit of time than the second. Thus, the drive mechanism of a jumping member according to the invention can be adapted to the display of any unit of time: second, minute, ten seconds, ten minutes, etc. To do this, the skilled person knows how to adapt accordingly the number of teeth on the cam and the jumping member, as well as the gear ratios in the gear train.

Claims (15)

Mechanism for driving a jumping member in a timepiece comprising a driving wheel (1), an indicator of a time unit, a jumping member (6) integral with said indicator and coaxial with said wheel of drive (1) to which said jumping member (6) is coupled by a spring (8), a cam (12) arranged to control an anchor (20), said cam (12) having a profile arranged to tilt the anchor (20) according to an oscillating movement so as to release the jumping member (6) once per unit of time, characterized in that the cam (12) and the jumping member (6) have distinct pivot axes, said driving mechanism further comprising an intermediate gear kinematically connecting the drive wheel (1) to the cam (12), and in that the anchor (20) has four arms (20a, 20b, 20c, 20d) separate , two (20a, 20b) of the four arms constituting probes arranged to cooperate with the cam (12) and the two aut res bras (20c, 20d) constituting exhaust arms arranged to successively block and release once per unit time the jumping member (6) alternately. Mechanism according to claim 1, characterized in that the intermediate gear comprises an intermediate mobile formed of an intermediate gear (14) arranged to cooperate with the drive wheel (1) and an intermediate wheel (16) arranged to cooperate with a cam drive wheel (10) integral with the cam (12). Mechanism according to any one of the preceding claims, characterized in that the intermediate gear is sized so that the cam (12) comprises less than thirty teeth (18), each tooth (18) having a front ramp (18a), and performs more than one turn per minute. Mechanism according to any one of the preceding claims, characterized in that , the unit of time being the second, the drive wheel (1) being arranged to turn in 60 seconds, and the indicator being an indicator of second dead, the cam (12) comprises ten teeth (18) and is arranged to perform three revolutions per minute, each tooth (18) having a front ramp (18a) decomposing in six steps. Mechanism according to claim 3 or 4, characterized in that the front ramp (18a) of each tooth (18) of the cam (12) has, on the last three steps of the tooth (18), a slope greater than the slope the front ramp (18a) on the first three steps of the tooth (18). Mechanism according to any one of the preceding claims, characterized in that the four arms (20a, 20b, 20c, 20d) of the anchor (20) are arranged to form substantially an X, the probe arm (20a, 20b ) positioned to cooperate with the cam (12) being oppositely disposed with respect to the pivot point of the anchor (20) to the exhaust arm (20c, 20d) positioned to release the jumping member (6). Mechanism according to any one of the preceding claims, characterized in that it comprises a mechanism for securing the relative position of the drive wheel (1) and the jumping member (6) Mechanism according to claim 7, characterized in that the mechanism for securing the relative position of the drive wheel (1) and the jumping member (6) comprises first support means provided on the drive wheel. (1) and a first stop provided on the jumping member (6), said first support means being arranged to bear on the first stop when the drive wheel (1) and the jumping member (6) turn in opposite directions. Mechanism according to one of claims 7 and 8, characterized in that the mechanism for securing the relative position of the drive wheel (1) and the jumping member (6) comprises second support means provided on the drive wheel (1) and a second stop provided on the jumping member (6), said second support means being arranged to rest on the second stop when the jumping member (6) is stopped. Mechanism according to one of claims 7 to 9, characterized in that the first and second bearing means comprise a pin (30, 36). Mechanism according to one of claims 7 to 10, characterized in that the first and second support means comprise an eccentric (38, 40). Mechanism according to one of claims 7 to 11, characterized in that the jumping member (6) is a wheel having at least two recessed areas separated by at least one separation arm (6a), and in that the first and second support means are arranged on either side of said at least one separation arm (6a), said separation arm (6a) constituting at least one of the first and second stops on which the first and second means of support are likely to be based respectively. Timepiece comprising a watch movement provided with a finishing gear powered by an energy source, characterized in that it comprises a mechanism for driving a jumping member according to any one of Claims 1 to 12 . Timepiece according to claim 13, characterized in that the drive wheel (1) is powered by the energy source of the movement. Timepiece according to claim 13 or 14, characterized in that the drive wheel (1) is the second wheel of the work train.

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