Mechanism for measuring time for a timepiece movement, in particular a chronograph mechanism

Abstract

The invention relates to a chronograph mechanism (1; 201), for a timepiece movement, including a counter for a unit of time comprising: - a display wheel capable of being rotated from a zero position, - a return wheel, rotatable between an initial position, associated with the zero position of the display wheel, and a final position, the display wheel and the return wheel being arranged such that the return wheel pivots from its initial position to its final position when the display wheel makes one revolution, - a resilient return member (20) arranged to act on the return wheel and to tend to return it to its initial position, the display wheel including a toothing arranged in mesh with the return wheel and having a truncated portion intended to allow the display wheel and the return wheel to be uncoupled on each complete revolution of the display wheel.

Description

Description MECHANISM FOR MEASURING TIME FOR A CLOCKWORK MOVEMENT, ESPECIALLY A CHRONOGRAPH MECHANISM Technical field

[0001] The present invention relates to a mechanism for measuring time, for a watch movement, comprising a counter of a unit of time comprising: - a display wheel intended to ensure the driving of a time unit display member and capable of being put into kinematic connection with a watch movement drive wheel, on request, to be able to be driven in rotation in a predefined direction of rotation from a predefined position throughout the measurement of a time, - a return wheel, intended to be pivotally mounted on a frame element so as to be able to pivot between an initial position, associated with the predefined position of the display wheel, and a final position, the display wheel and the return wheel being arranged in such a way that the latter pivots from its initial position to its final position when the display wheel travels substantially one revolution from its predefined position, - an elastic return member arranged to act on the return mobile and tend to return it to its initial position.

[0002] According to a preferred embodiment, the mechanism according to the present invention is a chronograph mechanism, but this mechanism can also be a countdown mechanism, as an alternative, without departing from the scope of the invention as defined by the appended claims.

[0003] The present invention also relates to a watch movement comprising a chronograph mechanism of this type, as well as a timepiece comprising such a watch movement. State of the art

[0004] Different architectures of mechanisms for measuring time, in particular chronographs, are already known in the prior art.

[0005] Examples of common chronograph mechanism architectures are presented in the work entitled "Theory of Watchmaking", by C.-A. Reymondin et al., published by the Federation of Technical Schools (Switzerland), ISBN 2-940025-10-X, notably on pages 232 to 244.

[0006] These chronograph mechanisms have a large number of moving components interacting with each other and their development is very complex.

[0007] In particular, these mechanisms generally include: - a clutch device to ensure the establishment of a kinematic connection between the finishing gear of the corresponding watch movement and a chronograph counter, - a blocker or brake to ensure the chronograph counter is locked when it is not being driven, - a zero-reset device acting on demand on the chronograph counter to return it to its zero position when the reading of a measured time is finished, - a shuttle or column wheel to control the status of the various devices just listed.

[0008] It is often intended that these different devices interact to ensure perfect synchronization of their respective actions on the chronograph counter.

[0009] Most of the time, these chronograph mechanisms also include a minute counter, or even an hour counter, with the additional components that this implies to ensure their drive and reset.

[0010] A large number of construction variants have already been presented aimed at improving all or part of these mechanisms.

[0011] Thus, for example, patent application WO 2018 / 091696 A1 describes a chronograph mechanism comprising a seconds counter comprising a seconds display wheel capable of being driven on demand from the finishing gear of the corresponding watch movement. The seconds display wheel carries a snail cam arranged to cooperate with a feeler subjected to the action of a elastic return member, such that the feeler can act on the cam to return the seconds display wheel to zero as soon as it is not driven or subjected to the action of a suitable brake. Furthermore, the feeler acts on a winding lever arranged to increment a chronograph minute counter each time the feeler falls from the portion of the cam with the largest radius to the portion with the smallest radius. This construction therefore makes it possible to replace the conventional elements constituting the zero-reset device, in particular a heart-shaped cam and a hammer intended to act on it to position the display wheel to zero. This makes it possible to respond to a frequent constraint in chronograph mechanisms relating to the high force that it is generally necessary to apply to the zero-reset push-piece of the corresponding timepiece, often uncomfortable for the user.

[0012] This chronograph mechanism requires delicate fine-tuning and adjustment operations to ensure that the forces of the springs involved, the shapes of the cam and the feeler, as well as the positioning of the pivot center of the latter in reference to the cam, are well adapted to allow its proper functioning. In addition, while this construction lends itself particularly well to the implementation of coaxial displays of the different units of measured time, it has a relatively large footprint along the direction of its thickness.

[0013] Thus, it still seems desirable to find an alternative approach to the realization of a chronograph mechanism that is comfortable to use, yet exhibits robust and reliable operation, and in particular allows for easy conventional arrangement of the chronograph counters on the dial of the corresponding timepiece. Disclosure of the invention

[0014] A main aim of the present invention is to propose a chronograph mechanism of alternative construction to the known constructions of the prior art, presenting in particular better efficiency, great simplicity and good reliability in its operating kinematics, as well as comfortable handling for a user.

[0015] To this end, the present invention relates more particularly to a chronograph mechanism of the type mentioned above, characterized in that the display wheel set further comprises a toothing arranged in engagement with a toothing of the return wheel set, the toothing of the display wheel set having a truncated portion, intended to allow temporary uncoupling between the display wheel set and the return wheel set when the latter reaches its final position, causing a retrograde movement of the return wheel set to its initial position at each complete revolution of the display wheel set, under the effect of the action of the elastic return member.

[0016] Thanks to these characteristics, it is possible to create a chronograph mechanism of simplified and robust construction, ensuring comfortable handling, particularly for its reset.

[0017] It is clearly understood, on the basis of the above characteristics, that the drive of the display wheel is carried out in the predefined direction of rotation throughout the measurement of a time, including when its elastic return member returns from its final position to its initial position, which may possibly happen several times during the measurement of a time whose duration allows it. Thus, each time the return wheel returns from its final position to its initial position, therefore in a retrograde manner, the travel of the display wheel is unchanged and continues in the predefined direction of rotation.

[0018] Preferably, it can be provided that the chronograph mechanism according to the invention also comprises a jumper arranged to be able to cooperate with the display wheel set and prevent its rotation at least in the direction of rotation opposite to the predefined direction of rotation when the measurement of a time is inactive, as well as a device for neutralizing the jumper, actuable on demand, arranged to allow a return of the display wheel set to its predefined position under the effect of the action of the elastic return member on the return wheel set. Thus, the return of the display wheel set to its predefined position is always done in the same direction of rotation, that is to say in the direction of rotation opposite to the direction of rotation predefined for the drive during the measurement of a time.

[0019] According to a preferred embodiment, it may be provided that the display wheel set comprises a plate having a drive toothing by which the display wheel set is capable of being put into kinematic connection with the drive wheel set of the watch movement. In this case, it may be provided that the jumper comprises three teeth capable of cooperating with this drive toothing to prevent the rotation of the display wheel set in the direction of rotation opposite to the predefined direction of rotation, the three teeth having a pitch p2 strictly greater than the pitch p1 of the drive toothing and strictly less than (3*p1) / 2.

[0020] Furthermore, it is advantageous to provide that the time unit counter is a seconds counter arranged in such a way that the display wheel makes a complete revolution in sixty seconds, that the mechanism for measuring a time also includes a counter of the minutes of measured time comprising a minute display wheel intended to ensure the driving of a member for displaying the minutes of measured time, and that the return wheel has a kinematic connection with a minute ratchet arranged to cooperate with the minute display wheel and make it rotate, to increment or decrement the minute counter, at each complete revolution of the display wheel.

[0021] In this case, it is advantageous to provide that the elastic return member is arranged to act on the return wheel via a first transmission lever carrying the minute ratchet.

[0022] According to a preferred embodiment, it can be provided that the minute display wheel set further comprises a toothing arranged in engagement with a minute return wheel set intended to be pivotally mounted on a frame element, so as to be able to pivot between an initial position and a final position, both associated with a predefined position of the minute display wheel set, that the minute counter further comprises an elastic minute return member arranged to act on the minute return wheel set and tend to return it to its initial position, that the teeth of the minute display wheel and the minute return wheel are arranged in such a way that the latter pivots from its initial position to its final position when the minute display wheel completes a full revolution from its predefined position, and that the teeth of the minute display wheel have a truncated portion, intended to allow temporary decoupling between the minute display wheel and the minute return wheel when the latter reaches its final position, causing a retrograde movement of the minute return wheel to its initial position at each full revolution of the minute display wheel, under the effect of the action of the elastic minute return member.

[0023] As with the first display wheel, the travel of the minute display wheel continues in the normal driving direction when a time measurement is in progress, without any particular impact at the end of each revolution when the minute return wheel returns to its initial position, in a retrograde movement.

[0024] Furthermore, it may be provided that the minute counter is arranged in such a way that the minute display wheel makes a complete revolution in sixty minutes, more preferably in thirty minutes, to benefit from better readability, that the mechanism for measuring a time also comprises a counter of the hours of measured time comprising an hour display wheel intended to ensure the driving of a member for displaying the hours of measured time, and that the minute return wheel has a kinematic connection with an hour pawl arranged to cooperate with the hour display wheel and make it rotate, to increment or decrement the hour counter, at each complete revolution of the minute display wheel.

[0025] In this case, it can also be provided that the elastic minute return organ is arranged to act on the minute return wheel by through a second transmission lever carrying the hour ratchet.

[0026] Furthermore, it may advantageously be provided that the hour display wheel set further comprises a toothing arranged in engagement with an hour return wheel set intended to be pivotally mounted on a frame element, so as to be able to pivot between an initial position and a final position, both associated with a predefined position of the hour display wheel set, that the hour counter further comprises an elastic hour return member arranged to act on the hour return wheel set and tend to return it to its initial position, that the toothing of the hour display wheel set and the hour return wheel set are arranged in such a way that the latter pivots from its initial position to its final position when the hour display wheel set travels a complete revolution from its predefined position, and that the toothing of the hour display wheel set has a truncated portion,intended to allow temporary decoupling between the hour display wheel and the hour return wheel when the latter reaches its final position, causing a retrograde movement of the hour return wheel to its initial position at each complete revolution of the hour display wheel, under the effect of the action of the elastic hour return member.,

[0027] As with the other display wheels, the travel of the hour display wheel continues in the normal driving direction when a time measurement is in progress, without any particular impact at the end of each revolution when the hour reminder wheel returns to its initial position, in a retrograde movement.

[0028] It is then possible to further provide that the chronograph mechanism includes an hour jumper acting on the hour display wheel to allow its rotation only in the direction of its normal drive when the measurement of a time is in progress, as well as a device for neutralizing the hour jumper, actuable on demand, arranged to allow a return of the hour display wheel to its position predefined under the effect of the action of the elastic hour return organ on the hour return wheel.

[0029] Furthermore, it can be provided that the mechanism for measuring a time also includes a minute jumper acting on the minute display wheel to allow its rotation only in the direction of its normal drive when the measurement of a time is in progress, as well as a device for neutralizing the minute jumper, actuable on demand, arranged to allow a return of the minute display wheel to its predefined position under the effect of the action of the elastic minute return member on the minute return wheel.

[0030] When the seconds and minutes counters include jumpers, it may further be provided that the mechanism for measuring time includes a control wheel set capable of pivoting on demand between at least one STOP position and one RESET position, and that the device for neutralizing the seconds jumper and the device for neutralizing the minutes jumper are arranged on the control wheel set in such a way that they can act substantially simultaneously on their respective jumpers to neutralize them when the control wheel set is moved from its STOP position to its RESET position.

[0031] When the mechanism includes an hour jumper, it is also possible to provide for its neutralization device to be arranged on the control wheel, in such a way that all the neutralization devices can act substantially simultaneously on their respective jumpers to neutralize them when the control wheel is moved from its STOP position to its RESET position.

[0032] In this case, it is possible to provide, according to a first variant embodiment of the invention, that the control wheel also carries a clutch wheel capable of occupying an engaged position, associated with an additional position, START, of the control wheel, to establish a kinematic connection between the display wheel and the drive wheel of the watch movement, or a disengaged position, associated with the positions STOP and RESET of the control mobile, to interrupt the kinematic link.

[0033] In this case, it is also possible to provide that the chronograph mechanism comprises a control member capable of switching on demand between a first state, START, and a second state, STOP, to pivot an intermediate control lever between a first position, START, and a second position, STOP, the intermediate control lever being arranged to actuate the control wheel and pivot it between its START and STOP positions.

[0034] In this case, it can also be provided that the mechanism for measuring a time includes a zero-reset member arranged to be able to act on the intermediate control lever and make it pass from one of its first and second positions to a third position, RESET, in which it actuates the control wheel to make it pivot into its RESET position.

[0035] Furthermore, it is advantageous to provide that the mechanism for measuring a time comprises a spring arranged to tend to position the intermediate control lever in its first position.

[0036] Furthermore, it is possible to provide, according to a second variant embodiment of the invention, that the mechanism for measuring time comprises a clutch device comprising a clutch wheel and capable of switching on demand between an engaged state, in which the clutch wheel occupies an engaged position, to establish a kinematic connection between the display wheel set and the drive wheel set of the watch movement, and a disengaged state, in which the clutch wheel occupies a disengaged position, to interrupt the kinematic connection, the control wheel set then being arranged to act on the clutch device, by passing from its STOP position to its RESET position, to switch or maintain the clutch device in its disengaged state.

[0037] In this case, when the mechanism for measuring time includes a jumper associated with the first display wheel, it is advantageous to provide that it further comprises an actuator movable between an active position, in which it cooperates with the jumper so as to position at least one of its teeth within reach of the drive teeth of the plate of the display mobile, and an inactive position, in which it leaves the jumper free to place all of its teeth out of reach of the drive teeth, and that the clutch device is further arranged to cooperate with the actuator and make it take its active position in the disengaged state and its inactive position in the engaged state.

[0038] In this case, it is further possible to provide that the clutch device comprises an intermediate control rocker arranged to act on the clutch wheel and define its position, the intermediate control rocker then advantageously carrying the actuator to simplify the synchronization of the movements of the jumper and the clutch wheel.

[0039] The present invention also relates to a watch movement comprising a mechanism for measuring time, preferably a chronograph mechanism, meeting the characteristics which have just been explained, as well as a timepiece comprising such a watch movement as well as at least one external control member arranged to actuate it in response to a suitable action by a user, that is to say a control member accessible to a user from outside a case of the timepiece. Brief description of the drawings

[0040] Other characteristics and advantages of the present invention will appear more clearly on reading the detailed description of preferred embodiments which follows, given with reference to the appended drawings given by way of non-limiting example and in which: - Figure 1 represents a simplified partial front view, in partial transparency, of a chronograph mechanism according to a first preferred embodiment variant of the present invention; - Figures 2a to 2c represent simplified front views of construction details of the chronograph mechanism of Figure 1; - Figure 3 shows a front view similar to that of Figure 1, with some additional components of the chronograph mechanism according to the first preferred embodiment of the present invention being illustrated; - Figure 4 shows a simplified overall front view of the chronograph mechanism according to the first preferred embodiment of the present invention; - Figure 5 shows a simplified perspective view of a construction detail of the chronograph mechanism according to the first preferred embodiment of the present invention; - Figure 6 shows a simplified front view of a construction detail of the chronograph mechanism according to the first preferred embodiment of the present invention; - Figure 7 represents a simplified partial front view of a chronograph mechanism according to a second preferred embodiment variant of the present invention; - Figures 8a and 8b show front views similar to that of Figure 7, in respective first and second configurations, certain components visible in Figure 7 no longer being shown, while certain additional components of the mechanism according to the second preferred embodiment variant are illustrated; - Figure 9 represents a simplified partial front view similar to that of Figure 7; - figures 10a, 10b and 10c represent simplified front views of a construction detail of the chronograph mechanism according to the second preferred embodiment variant, in three different respective configurations; - figures 11a, 11b and 11c represent partial and simplified overall front views of the mechanism of chronograph according to the second preferred embodiment, in three different respective configurations; - figures 12a and 12b represent simplified front views of a construction detail of the chronograph mechanism according to the second preferred embodiment variant, in two different respective configurations; - figures 13a, 13b and 13c represent simplified front views of a construction detail of the chronograph mechanism according to the second preferred embodiment variant, in three different respective configurations; - Figure 14 represents a simplified perspective view of a construction detail of the chronograph mechanism according to the second preferred embodiment of the present invention, and - Figure 15 shows a simplified front view of a construction detail of the chronograph mechanism according to the second preferred embodiment of the present invention. Method(s) of carrying out the invention

[0041] Figure 1 represents a simplified partial front view, in partial transparency, of a mechanism 1 for measuring a time according to a first variant of a preferred embodiment of the present invention, when the mechanism 1 is implemented in the form of a chronograph mechanism. A person skilled in the art will not encounter any particular difficulty in adapting the present teaching and producing a countdown mechanism without departing from the scope of the invention as defined by the appended claims.

[0042] More specifically, Figure 1 shows a partial view of 2-second, 4-minute and 6-hour counters, along with the corresponding reset devices.

[0043] The seconds counter 2 comprises a seconds display wheel comprising a seconds wheel 8, intended to be driven on demand from a drive wheel (numerical reference 10 in figure 5) of the corresponding watch movement, as well as a pinion 12 (visible in transparency) secured to the seconds wheel 8. The pinion 12 has a truncated dentition, two of its teeth being cut directly at their base.

[0044] The teeth of the pinion 12 are arranged to cooperate with the teeth of a return wheel intended to be pivoted on a frame element of the watch movement, more precisely on a rack 14 which it comprises, the latter being associated with a counterweight 16. The teeth of the return wheel also have two truncated teeth, preferably and optionally, as well as a stop 18.

[0045] An elastic return member 20 is arranged to act on the return wheel set so as to pivot the latter in the counterclockwise direction of rotation in the view of FIG. 1, to tend to return it to a first, initial position, in which the stop 18 is positioned against the teeth of the pinion 12, as illustrated in FIG. 1. Thus, the stop 18 acts as a positioning jumper indexing the return wheel set in its initial position.

[0046] The teeth of the pinion 12 and the rack 14 are arranged in such a way that when the seconds wheel 8 travels a complete revolution from its zero position, in the counterclockwise direction of rotation in the view of FIG. 1, the pinion 12 cooperates with the rack 14 to pivot the return wheel set from its initial position to a final position, reached by the action of the last tooth of the pinion 12, located immediately before the truncated portion of the teeth following the direction of rotation, on the last tooth of the rack 14.When this last tooth of the pinion 12 releases the last tooth of the rack 14, after substantially one complete revolution of the seconds wheel 8, the truncated portion of the teeth of the pinion 12 faces the rack 14 and the latter can then freely undergo the action of the elastic return member 20 to return to its initial position, in a rapid retrograde movement, while the seconds wheel 8 can continue its rotation in the counterclockwise direction of rotation to begin a new revolution from its zero position. Thus, it is clear that the seconds wheel 8 has a conventional apparent operating mode, always rotating in the same predefined direction of rotation, while the measurement of a time is in progress.

[0047] Preferably, it is possible to provide that the last tooth of the rake 14 is slightly narrower and / or pointed than the other teeth, in order to avoid tip-to-tip blocking between it and the last tooth of the pinion 12 which drives it. Alternatively or in addition, it is also possible to provide that this last tooth of the rake 14 has a length slightly greater than that of the other teeth, to avoid any risk of contact of the other teeth with the teeth of the pinion 12 when the rake 14 falls towards its initial position, under the effect of the action of its elastic return member 20.

[0048] In a preferred non-limiting manner, it may be provided that the seconds wheel 8 makes a complete rotation on itself in sixty seconds and that it is intended to directly carry a display member for the seconds of a measured time, advantageously a display hand (not shown). In this case, the return wheel has a retrograde movement whose period is sixty seconds, which makes it possible to dimension the elastic return member 20 in such a way that the impact on the operation of the watch movement is relatively reduced.

[0049] The construction and operation of the 4 minute and 6 hour counters are similar to that of the seconds.

[0050] In fact, the minute counter 4 comprises a minute display wheel, intended to drive a minute display member, comprising a minute wheel 22 carrying a pinion 24 whose teeth are truncated and arranged in mesh with teeth provided on a rack 26 of a minute return wheel.

[0051] An additional elastic return member 28 is arranged so as to act on the minute return wheel and tend to pivot it in the counterclockwise direction of rotation in the view of FIG. 1, to an initial position defined by the contact between a stop 29 of the rack 26 and the teeth of the pinion 24.

[0052] The minute display wheel and the minute reminder wheel are preferably arranged such that, when the minute display wheel completes substantially one revolution from its zero position (illustrated in Figure 1), it rotates the minute return wheel from its initial position to a final position, in which the truncated portion of the teeth of the pinion 24 faces the rack 26. The action of the elastic return member 28 on the minute return wheel then causes a rapid retrograde movement of the latter to its initial position, without affecting the movement of the minute wheel 22 as long as the measurement of a time is in progress.

[0053] Similarly, the hour counter 6 comprises an hour display wheel, intended to drive an hour display member, comprising an hour wheel 30 carrying a pinion 32 whose teeth are truncated and arranged in mesh with teeth provided on a rack 34 of an hour return wheel.

[0054] An additional elastic return member 36 is arranged so as to act on the hour return wheel and tend to pivot it in the counterclockwise direction of rotation in the view of FIG. 1, to an initial position defined by the contact between a stop 37 of the rack 34 and the teeth of the pinion 32.

[0055] The hour display wheel set and the hour return wheel set are preferably arranged in such a way that, when the hour display wheel set makes substantially one revolution from its zero position (illustrated in FIG. 1), it rotates the hour return wheel set from its initial position to a final position, in which the truncated portion of the teeth of the pinion 32 faces the rack 34. The action of the elastic return member 36 on the hour return wheel set then causes a rapid retrograde movement of the latter to its initial position, without affecting the movement of the hour wheel 30 as long as the measurement of a time is in progress.

[0056] Figures 2a, 2b and 2c represent simplified front views of construction details of the various counters, respectively, for seconds, minutes and hours.

[0057] It is clear from Figure 2a that the seconds counter 2 advantageously comprises a jumper 40 arranged to cooperate with the seconds wheel 8 and ensure its angular locking in the STOP mode of the chronograph, while letting it rotate in a predefined direction of rotation in START mode, when the measurement of a time is in progress and it is driven by the watch movement.

[0058] More precisely, here the jumper 40 comprises a double beak 42 whose two points are spaced from each other in such a way that the points cooperate in turn with the teeth of the seconds wheel 8 every half step, in other words, the step of the jumps of the seconds wheel 8 corresponds to half the step of its teeth. Thanks to this characteristic, the recoil of the seconds wheel 8 is limited when starting the measurement of a time. Furthermore, the implementation of a brake is not necessary since the jumper 40 ensures the maintenance of the seconds wheel 8 in a given position when its drive from the watch movement is interrupted.

[0059] It is advantageous to provide that the action of the spring of the jumper 40 is adjustable, for example by means of an eccentric as shown here, to optimize its operation and define the best compromise between its locking action and the energy consumption that its action causes on the proper operation of the corresponding watch movement.

[0060] Similarly, as is apparent from figures 2b and 2c, a jumper 44 is associated with the minute wheel 22 and another jumper 46 is associated with the hour wheel 30 to ensure their angular locking when the measurement of a time is interrupted, while allowing these two wheels to rotate, in the direction of their incrementation, when the measurement of a time is in progress.

[0061] It is also noted in Figures 2b and 2c that the indexing between, on the one hand, the minute and hour wheels and, on the other hand, the corresponding pinions is typically carried out on a mounting provided with two positioning pins intended to receive the wheel, by means of two corresponding indexing holes in the latter, and cooperating with the teeth of the pinion. Thus, the indexing between each wheel and its pinion is precise.

[0062] Figure 3 shows a simplified front view similar to that of Figure 1, in which additional construction details are illustrated.

[0063] More specifically, Figure 3 illustrates how the 4 minute and 6 hour counters are driven when time measurement is in progress.

[0064] The chronograph mechanism 1 according to the preferred embodiment of the invention comprises a first transmission lever 50 intended to be pivoted on a frame element of the watch movement along an axis of rotation 52.

[0065] The first transmission lever 50 comprises a first arm 54 whose end is connected to the seconds return wheel set by a linear ball joint type articulation or link 56. The first transmission lever 50 comprises a second arm 58 carrying at its end a minute ratchet 60, arranged to retract initially to move from one tooth to the other of the minute wheel 22, when the transmission lever 50 rotates in a first predefined direction of rotation (counterclockwise in the view of FIG. 3), then to increment the minute counter when the transmission lever 50 rotates in the opposite direction, driving the minute wheel 22 with it.

[0066] Thus, the minute ratchet 60 is positioned behind the next tooth of the minute wheel 22 while the seconds return wheel moves from its initial position to its final position, while it rotates the minute wheel 22 by one step (in the counterclockwise direction of rotation in the view of figure 3) during the rapid retrograde movement of the seconds return wheel from its final position to its initial position, i.e. every sixty seconds.

[0067] Similarly, the chronograph mechanism 1 comprises a second transmission lever 62 intended to be pivoted on a frame element of the watch movement along an axis of rotation 64 (here merged with that of the hour reminder wheel set, for non-limiting illustration purposes).

[0068] The second transmission lever 62 comprises a first arm 66 whose end is connected to the minute return wheel set by a linear ball joint type articulation or connection 68. The second transmission lever 62 comprises a second arm 70 carrying at its end a ratchet of the hours 72, arranged to retract and pass from one tooth to the other of the hour wheel 30, when the transmission lever 62 rotates in a first predefined direction of rotation (clockwise in the view of figure 3), and to increment the hour counter when the transmission lever 62 rotates in the opposite direction, driving the hour wheel 30 with it.

[0069] Here, the hour ratchet 72 gradually rotates the hour wheel 30 by one step (in the counterclockwise direction of rotation in the view of Figure 3) while the minute return wheel moves from its initial position to its final position, while it quickly positions itself behind the next tooth of the hour wheel 30 during the rapid retrograde movement of the minute return wheel from its final position to its initial position. Thus, the minute counter 4 is advantageously arranged in such a way that the minute wheel 22 makes one revolution in sixty minutes, more preferably in thirty minutes. The hour counter 6 is here made in such a way that the hour wheel 30 makes one revolution in twenty-four hours, more preferably in twelve hours, by way of non-limiting illustration.

[0070] It will be noted that, advantageously, the jumper of each of the three counters, more particularly of the minute and hour counters, makes it possible to maintain the orientation of the corresponding wheel fixed during the return of the associated transmission lever to its initial position. Indeed, during this operation, which immediately follows an increment of the counter, its wheel no longer undergoes the force which is exerted by the transmission lever the rest of the time and which opposes the return to zero of the counter under the effect of the action of the corresponding return wheel set. Thus, during the return of the transmission levers to their initial position, only the jumpers oppose the action of the return wheel sets and prevent an unexpected return to zero of the counters.Consequently, when a time measurement is in progress, each of the jumpers only allows the rotation of the corresponding counter in one direction of rotation, that of its incrementation, rotation in the direction of resetting to zero, induced by the corresponding return wheel, being blocked.

[0071] The general operation of the chronograph mechanism 1 according to the preferred embodiment of the present invention will now be described in relation to Figures 4, 5 and 6, respectively representing a simplified overall front view of the chronograph mechanism 1, a simplified perspective view of a first construction detail of the chronograph mechanism 1, and a simplified front view of a second construction detail of the chronograph mechanism 1.

[0072] The components of the chronograph mechanism 1 are carried by one or more frame elements, generally identified by the reference numeral 80, the number and shape of which are of little importance for the implementation of the present invention. Thus, the frame elements may comprise a plate of a watch movement or an additional plate specific to the chronograph mechanism 1, and one or more bridges.

[0073] The operation of the chronograph mechanism 1 is here intended to be controlled by a user by means of two pushers (not visible) of the corresponding timepiece, one intended to act on a START / STOP command 82, and the other on a RESET command 84.

[0074] The START / STOP control 82 carries a pawl 86 arranged to cooperate with a control member here having the form of a column wheel 88, to make it turn by one step, in the counterclockwise direction of rotation in the view of figure 4, each time the user presses the corresponding push button.

[0075] A jumper 90 also cooperates with the column wheel 88 to define stable angular orientations, in a conventional manner, alternately associated with START and STOP states of the chronograph mechanism 1.

[0076] The column wheel 88 in turn cooperates with a beak provided at the free end of a first arm of an intermediate control lever 92, in the general shape of a V. The second arm of the intermediate control lever 92 comprises a spring 94 arranged to push the beak of the first arm in the direction of the column wheel 88.

[0077] Furthermore, the free end of the second arm carries a pin 96, which is engaged in a slot formed in an arm 98 of a control wheel set 100. The latter is free to rotate with reference to the frame of the watch movement, along an axis of rotation which here coincides with that of the chronograph seconds counter 2. The control wheel set 100 is assembled to the frame by three screws 102 engaged in curved slots of a central plate of the control wheel set 100. A person skilled in the art will not encounter any particular difficulty in setting up means making it possible to define the extreme angular positions of the control wheel set 100 (either by at least one screw, or even an eccentric, or by one or more members cooperating with it to make it pivot) without departing from the scope of the invention as defined by the appended claims.

[0078] When moving from one START or STOP state to the other, the column wheel 88 pivots the intermediate control lever 92 between a first START position and a second STOP position, which itself pivots the control wheel 100 between a first START position and a second STOP position.

[0079] The control mobile 100 comprises a second arm carrying a clutch wheel 104 capable of occupying two different positions, an engaged position and a disengaged position, depending on the position of the control mobile 100.

[0080] The clutch wheel 104 is part of a clutch device whose construction and operation are more clearly visible in the view of Figure 5.

[0081] The clutch device comprises a clutch wheel set 106 comprising two wheels integral with each other in rotation, one of which is permanently engaged with the drive wheel set 10 of the watch movement, and the other of which may or may not be engaged with the clutch wheel 104 depending on the position in which the control wheel set 100 is located.

[0082] The clutch device also comprises an additional wheel 108 coaxial with the clutch mobile 106 and identical to the second wheel of this last. The additional wheel 108 is arranged in permanent mesh with the seconds wheel 8 of the seconds counter 2.

[0083] Thus, when the control wheel 100 is in its START position, as illustrated in FIGS. 4 and 5, the clutch wheel 104 is simultaneously engaged with the clutch wheel 106 and with the additional wheel 108, so as to create a kinematic connection between the drive wheel 10 and the seconds wheel 8 to ensure the drive of the latter.

[0084] When the control wheel 100 passes into its STOP position (by pivoting in the counterclockwise direction of rotation in the view of FIG. 4), the clutch wheel 104 is no longer engaged with either the clutch wheel 106 or the additional wheel 108. The kinematic connection between the drive wheel 10 and the seconds wheel 8 is then interrupted and the latter is no longer driven.

[0085] Of course, those skilled in the art will be able to implement a clutch of more conventional construction than that which has just been described without departing from the scope of the present invention as defined by the appended claims.

[0086] The RESET command 84 is shown more visibly in Figure 6, with the intermediate control flip-flop 92.

[0087] The RESET control 84 comprises a reset member 110 and a reset lever 112, both assembled to the frame by a screw 114 so as to be able to pivot, as well as a rotary lock 116, acting on the reset lever 112 and actuated by the reset member 110, to give rise to operation of the “all or nothing” type.

[0088] More precisely, the reset member 110 carries a first pin 118 arranged to cooperate with the latch 116, to make it rotate, and a second pin 120 arranged to deform a spring 122 carried by the reset lever 112, when the reset member 110 is actuated while the latch 116 prevents rotation of the reset lever 112.

[0089] The lock 116 comprises a cutout 124 in which a beak 126 secured to the reset lever 112 is capable of engaging when the cutout 124 faces it.

[0090] Thus, the RESET control 84 returns to its rest state (illustrated in FIG. 6) without impact on the operation of the chronograph mechanism 1 when the user releases the corresponding pusher before reaching a certain threshold predefined by construction. When the reset member 110 pivots sufficiently for the cutout 124 to position itself opposite the beak 126, the latter can be inserted into the cutout 124 to allow the spring 122 to release the energy that it has stored during its deformation. In doing so, the reset lever 112 suddenly pivots and a finger 128 that it carries can act on the intermediate control lever 92 to pivot it in the clockwise rotation direction in the view of FIG. 6.

[0091] Returning to Figure 4, we see that, whatever the starting position of the intermediate control lever 92, its actuation by the RESET command 84 causes a rotation of the control wheel 100 into a third position, RESET, in which it is intended to reset the chronograph counters to zero.

[0092] For this purpose, the control wheel 100 comprises in particular devices for neutralizing the jumpers of the different chronograph counters, taking the form of two slots 132 and 134 formed in a first lug 130, and a slot 138 formed in a second lug 136.

[0093] The slot 132 cooperates with the seconds jumper 40 to pivot it clockwise in the view of Figure 4, when the control wheel 100 passes into its RESET position, to move its double beak 42 away from the seconds wheel 8 and thus allow the return of its return wheel to its initial position, causing the seconds counter 2 to return to its zero position as explained previously.

[0094] It will be noted that, preferably, the entrance of the slot 132 is shaped so as to define a stop for the seconds jumper 40 when the control wheel 100 is in its STOP position, to prevent it from rotate in the clockwise direction in the view of figure 4, and thus secure the position of the seconds wheel 8 when the measurement of a time is stopped.

[0095] The second slot 134 of the first lug 130 is arranged to cooperate with the minute counter 4. More precisely, the device for neutralizing the minute jumper also comprises a minute neutralizing lever 140, pivotally mounted on the frame and carrying a pin 142 housed in the second slot 134. The latter has two successive portions, a first associated with the START and STOP positions of the control wheel set 100 and with a first angular orientation of the minute neutralizing lever 140, and a second associated with the RESET position of the control wheel set 100 and with a second angular orientation of the minute neutralizing lever 140, occupied by the latter after a counterclockwise rotation in the view of FIG. 4.

[0096] The minutes neutralization lever 140 comprises a first branch 144 arranged to neutralize the minutes jumper 44 by pivoting it in the clockwise rotation direction in the view of Figure 4 when the control wheel set 100 is pivoted to its RESET position. Thus, with the minutes wheel 22 released, the minutes return wheel set can return to its initial position and return the minutes counter 4 to its zero position, as explained previously.

[0097] The 140 minute neutralization lever has a second branch 146 arranged to keep the 60 minute pawl away from the 22 minute wheel when it is reset to zero.

[0098] The slot 138 of the second lug 136 is arranged to cooperate with the hour counter 6. More precisely, the device for neutralizing the hour jumper also comprises an hour neutralizing lever 150 which is pivotally mounted on the frame and carries a pin 152 housed in the slot 138. The latter has two successive portions, a first associated with the START and STOP positions of the control wheel set 100 and with a first angular orientation of the hour neutralizing lever 150, and a second associated with the RESET position of the wheel set control lever 100 and a second angular orientation of the hour neutralization lever 150, occupied by the latter after a clockwise rotation in the view of figure 4.

[0099] The hour neutralization lever 150 comprises a first branch 154 arranged to neutralize the hour jumper 46 by pivoting it in the counterclockwise direction of rotation in the view of Figure 4 when the control wheel 100 is pivoted to its RESET position. Thus, with the hour wheel 30 released, the hour return wheel can return to its initial position and return the minute counter 6 to its zero position, as explained previously.

[0100] The 150 hour neutralization lever has a second branch 156 arranged to keep the 72 hour pawl away from the 30 hour wheel when it is reset to zero.

[0101] When the RESET command 84 is released, the chronograph mechanism 1 resumes its state prior to its activation, START or STOP, depending on the state of the column wheel 88, under the effect of the action of the spring 94 of the intermediate control lever 92. Thus, the chronograph mechanism 1 here has a flyback type operation since the measurement of a time can resume as soon as the reset push-piece is released if the active mode during a reset was the START mode.

[0102] From the above description, it is understood how it is possible to produce a flyback type chronograph mechanism for a watch movement having a simplified construction, in particular thanks to the implementation of a central control wheel allowing both to start or stop the measurement of a time, and to reset the chronograph counters to zero, all these functions being controlled from a single lever arranged to define the position of the control wheel from two separate controls (each associated with a push-piece). In addition, the conventional spatial distribution of the chronograph counters allows the implementation of large lever arms to ensure good transmission of forces between them. Furthermore, the operating principle and the construction of the device reset allow to significantly limit the force that a user must apply to the corresponding push-piece to actuate it, which improves its ergonomics. In addition, this construction also makes it possible to limit the travel and the actuating force of the control push-pieces associated with this chronograph mechanism, to actuate the various functions, which in particular makes it possible to improve the ergonomics and design of these push-pieces by improving their integration into the caseband. Concretely, this makes it possible to produce push-pieces with reduced actuating characteristics, for example going from a typical travel of the order of 0.8 to 1 mm to a reduced travel of the order of 0.3 mm, and / or from a typical actuating force to be applied of the order of 8 to 12 N to a reduced actuating force of the order of 1.5 to 2.5 N (it is thus possible to produce mechanical pushers similar to the electromechanical pushers used on mobile phones for example).

[0103] These advantages can be obtained in particular thanks to the structure of the zero-resetting device according to the invention, which makes it possible to carry out a reliable and precise zero-resetting of chronograph counters without using conventional hammers.

[0104] Furthermore, the construction according to the present invention makes it possible to keep the seconds counter under permanent tension, thus avoiding any jittering of the associated chronograph seconds hand when triggering time measurements.

[0105] Furthermore, the energy usually lost in friction resulting from the implementation of friction is here exploited by charging the return mobiles, this energy then being used either to reset the counters to zero, or to increment the chronograph minute and hour counters. Thus, the construction according to the invention offers better efficiency than conventional constructions.

[0106] It is understood that the different components of the chronograph mechanism according to the invention can also have very diverse shapes without this affecting their functionality, which provides great flexibility to a watch movement manufacturer to distribute the various components involved, including those of the associated clock mechanism.

[0107] A second alternative embodiment of a chronograph mechanism 201 according to a preferred embodiment of the invention will now be presented in relation to the illustrations of Figures 7 to 15. The presentation of this second alternative embodiment focuses mainly on the differences that it presents with reference to the first alternative embodiment which has already been described in detail above.

[0108] For the sake of simplification of understanding, certain components already described in relation to the first embodiment variant and which only have minor differences when moving to the second embodiment variant bear the same numerical references in both embodiment variants.

[0109] Figures 7, 8a-8b, 9 and 10a-10c represent different partial front views of counters for seconds 2, minutes 4 and hours 6 according to the second embodiment variant, the general operating principle of which remains identical to that of the first embodiment variant and will therefore not be described again in detail.

[0110] In particular, figures 7 and 9 illustrate the seconds counter 2, with its seconds wheel 8 and its pinion 12 with truncated teeth, as well as its return wheel with its rack 14 cooperating with the pinion 12.

[0111] Figures 8a and 8b illustrate in particular the minute counter 4, with its minute wheel 22 and its pinion 24 with truncated teeth, and its return wheel with its rack 26 cooperating with the pinion 24, as well as the hour counter 6, with its hour wheel 30 and its pinion 32 with truncated teeth, and its return wheel with its rack 34 cooperating with the pinion 32.

[0112] The kinematic connections between the different counters are also illustrated in Figures 7, 8a and 8b. Figure 7 illustrates how a first transmission rocker 50 provides the connection between the seconds 2 and minutes 4 counters, while Figures 8a, 8b illustrate how a second transmission rocker 62, articulated following an axis of rotation 162, ensures the connection between the minute counters 4 and hours 6.

[0113] If the shapes of the different components and the construction of the connections between the return wheels and the transmission levers have been slightly modified with reference to the first embodiment variant, we note above all a new layout of the elastic return members 20, for the seconds counter 2, and 28, for the minutes counter 4. Indeed, it is clear from Figure 7 that the elastic return member 20 acts on the return wheel of the seconds counter 2 via the first transmission lever 50, by acting on a pin 164 carried by the latter. Similarly, it is clear from Figures 8a and 8b that the elastic return member 28 acts on the return wheel of the minutes counter 4 via the second transmission lever 62, by acting on a pin 166 carried by the latter.

[0114] These characteristics make it possible to implement a lever arm by which the fluctuations in the torque exerted by each elastic return member on its counter, between its minimum load and maximum load states, are smoothed compared to the first embodiment variant. Thus, the impact of the load variations of these elastic return members on the operation of the corresponding watch movement is reduced, for example on the amplitude of the oscillations of a balance wheel.

[0115] More precisely, considering the situation of the elastic return member 20 of the seconds counter 2, it can for example be provided, in the case where the oscillator of the associated watch movement comprises a balance wheel, that the latter has a loss of amplitude (or consumption) of 30 degrees at most, that is to say when the elastic return member 20 has its maximum state of charge during the measurement of a time, such a level of loss of amplitude being standard in watch movements with conventional chronograph mechanisms. While in a standard design this consumption is the consequence of the friction of a friction spring which prevents the chronograph seconds hand from jittering, this consumption comes here from the pre-stressing of the elastic return member 20 on the return wheel, which applies a return torque to the seconds counter 2 equivalent to the friction torque of the frictions of standard chronograph mechanisms. The return wheel therefore allows the seconds counter 2 to be tensioned and thus prevents the associated chronograph seconds hand from wobbling.

[0116] In order to have the most constant consumption possible when the chronograph mechanism 201 is running (in START mode), the elastic return member 20 has preferably been placed further in the kinematic chain, on the first transmission lever 50, in order to apply the most constant torque possible to the seconds return wheel set. Indeed, when the pinion 12 of the seconds counter 2 pivots 360°, the return wheel set pivots about 30°, and the first transmission lever 50 about 5°. Thus the load variation of the elastic return member 20 is much lower than its initial prestress. This also makes it possible to have a greater force from the elastic return member 20, at equivalent torque applied to the seconds counter 2, than if it acted directly on the return wheel set.The corresponding spring section is therefore larger and makes it possible to desensitize the system to variations in manufacturing tolerances, while guaranteeing good repeatability in terms of consumption.

[0117] It will also be noted that the tooth profiles of the pinion 12 and the rack 14 are preferably drawn in such a way that the system is completely reversible. Thus, regardless of their movement from the initial position, the rack 14 is capable of returning the seconds counter 2 to its zero position (or predefined, in the case of a countdown mechanism) in a retrograde manner under the effect of the elastic return member 20.

[0118] As with the first preferred embodiment, the minute counter 4 is an instantaneous jump counter, and not a semi-instantaneous or trailing counter as in many known calibers. A basic principle of the present invention is to use the energy stored in the elastic return member 20 of the seconds, via the rack 14 of the seconds and the first transmission flip-flop 50, using their instantaneous return at each complete revolution of the seconds counter 2 to increment the minutes counter 4. Thus this system allows great precision of the jump moment, without adding additional consumption when passing the minute.

[0119] On the same principle as for the seconds counter system 2, the elastic return member 28 of the minutes return wheel is positioned further in the kinematic chain, on the second transmission lever 62, in order to limit the variation of its load, and to have the most constant and repeatable force possible.

[0120] It may also be noted that the jumper 44 of the minute counter 4 can advantageously be drawn with its tip off-center so that it can be easily incremented in one direction, but has a high holding torque in the other direction to prevent the minute counter 4 from returning to zero under the action of the minute return wheel.

[0121] As for the 6 hour counter, its mode of operation is again based on the same rake system as the 2 second and 4 minute counters. The movement of the 26 minute rake is used to progressively increment the 6 hour counter, which results in a "semi-trailing" display of the 6 hour counter.

[0122] In this case, we see that the elastic return member 36 of the hours acts directly on the hour return wheel set and not on a lever or a lever which would multiply the angular travel as is the case for the 2 seconds and 4 minutes counters. Consequently, the torque variation is greater here and the section of the corresponding spring is lower at equivalent torque on the hour wheel set than on the minute wheel set. However, the 6 hours counter is much less sensitive to this problem than the 2 seconds and 4 minutes counters, and it is not necessary to optimize it.

[0123] Generally speaking, the shapes of the 60 minute and 72 hour ratchets, as well as those of the 44 minute and 46 hour jumpers, are preferably optimized to limit the torque variations linked to their interactions with the corresponding counters during the measurement of a time.

[0124] According to an advantageous embodiment variant, it can be provided that the hour ratchet 72 is not in contact with the teeth of the hour wheel 30 during part of the travel of the minute counter 4, with reference to the duration of a complete revolution.

[0125] Such an implementation is presented in relation to Figures 8a and 8b, which illustrate the configuration of the hour counter 6 respectively when the minute counter 4 is at the beginning of a revolution, and when it is approaching the end of a revolution.

[0126] It can be seen in Figure 8a that the hour ratchet 72 is positioned slightly set back from the teeth of the hour wheel 30, at the start of the measurement of a time (from zero, then at the start of each revolution of the minute counter 4). When the minute counter 4 is driven, in one-minute steps, it pivots the second transmission lever 62 in such a way that the hour ratchet 72 pivots in the clockwise direction of rotation in the view of Figure 8a, around the axis of rotation 64. During the first few minutes, the hour wheel 30 is therefore not driven. The hour ratchet 72 comes into contact with a tooth of the hour wheel 30 after a few minutes and gradually rotates it, in time with the minutes of the measured time.The 46-hour jumper is gradually moved apart by a tooth of the 30-hour wheel, and it is advantageous to provide that the beak of the 46-hour jumper and this tooth are in a point-to-point configuration a few minutes before the end of a complete revolution of the 4-minute counter, for example around twenty-five minutes if the 4-minute counter makes a complete revolution in thirty minutes. When the tip of the tooth crosses the tip of the beak of the 46-hour jumper, the latter can act on the other flank of the tooth to turn the 30-hour wheel, in the direction of its normal drive, to its next discrete position (corresponding here to the next half-hour in the case where the 4-minute counter makes a revolution in thirty minutes). Thus, this step could therefore occur when the 4-minute counter passes from its twenty-five-minute position to its twenty-six-minute position, the. corresponding configuration, after indexing of the hour wheel 30 by the hour jumper 46, being that illustrated in figure 8b. It can then be seen that the hour ratchet 72 is again distant from the teeth of the hour wheel 30. During the following movements of the minute counter 4, to complete the thirty-minute revolution, the hour ratchet 72 continues its rotation to catch up with the tooth with which it cooperated until the hour jumper 46 takes over. Once the minute counter 4 reaches thirty minutes, its return wheel pivots in the opposite direction with reference to its normal drive, to return to its initial position, and also pivots the second transmission lever 62 in the opposite direction to return the hour ratchet 72 to its initial position, by rotation in the anti-clockwise direction on the view of figure 8b with retraction of the hour ratchet 72 upon passage of the next tooth.The same cycle can then be repeated during a new turn of the 4-minute counter.

[0127] It will be noted that it is possible to provide a device for adjusting the position of the hour pawl 72 to ensure precise positioning of the display member for the measured time hours (since this display member does not move quickly, its incorrect positioning would be easily detectable by an observer). For example, it is possible to provide the implementation of an eccentric between the two portions of the second transmission lever 62, to be able to adjust their relative angle at the level of the rotation axis 162.

[0128] It is understood from the preceding explanations that the energy stored in the elastic return organ 20 of the seconds is used to progressively increment the counters of minutes 4 and hours 6, with each complete revolution of the seconds counter 2. This energy must therefore be sufficient to increment the counter of minutes 4 and the counter of hours 6 in the configuration where they consume the most energy, that is when the racks of minutes 26 and hours 34 are armed, but the jumper of hours 46 has not yet crossed its point of equilibrium.

[0129] Figure 9 represents a simplified partial front view similar to that of Figure 7, illustrating the seconds counter 2 with its return wheel and the first transmission lever 50 carrying the minutes pawl 60, in the configuration corresponding to substantially thirty seconds, or approximately half a revolution of the seconds wheel 8.

[0130] Points P1 and P2 have been marked in Figure 9 to indicate the position of the respective centers of gravity of the seconds return wheel and the first transmission lever 50.

[0131] Generally speaking, it is advantageous to provide for balancing of the seconds and minutes return mobiles with the associated transmission levers. Indeed, it may for example be desirable to prevent any loss of information during shocks of up to 500 G, and it is therefore necessary, in such a case, to desensitize the system to the unbalances of the racks and levers. For this purpose, it is possible to carry out static balancing of the return mobiles with their transmission levers so that regardless of the direction of a shock, the torques generated by it on the return mobiles and their transmission levers cancel each other out.

[0132] A principle for achieving static balancing can be based on the following methodology, highlighted by the addition of direction lines and arrows in relation to the components of the second counter 2 in Figure 9: - the sets are positioned in their middle position to average the effects of balancing, - the directions from the center of rotation to the center of gravity of the assemblies are parallel. Thus, regardless of the direction of the shock, the radial and axial components resulting from the shock will be equivalent on the assemblies, - the directions from the center of rotation to the center of gravity of the assemblies allow the torques generated by shocks to be subtracted and not added together, and - the forces generated by the unbalanced masses of the assemblies must cancel at the point of contact between the sets taking into account the lever arms.

[0133] Furthermore, it should be noted that the speed of resetting the various counters is directly linked to the return torques to which they are subjected and to the inertias of their mobiles and their display hands (or other types of display organs). A priori, only the seconds counter 2 could really justify the implementation of specific measures to ensure a sufficient speed of return to zero, according to specific needs that the person skilled in the art might have, due to the inertias involved being greater than those of the minutes counter 4 and the hours counter 6, which can have a virtually instantaneous resetting. In this case, it is possible to possibly provide for a reduction in the inertia of the seconds mobile by manufacturing the seconds hand and the seconds wheel 8 in titanium, because it has a density almost half that of the copper materials usually used.Furthermore, as will be apparent from the following, the second embodiment incorporates the implementation of an obstacle braking system for the seconds counter 2 which provides high shock resistance. Thanks to this, it is no longer necessary to have a balanced seconds hand to withstand shocks in STOP mode of the chronograph mechanism 201. This makes it possible to reduce the inertia of the seconds hand by reducing the dimensions of its balancing sector, the function of which becomes essentially aesthetic.

[0134] Figures 10a, 10b and 10c will now show the construction of the seconds jumper 240 according to the second preferred embodiment, this playing the role of an obstacle braking system as mentioned above, with excellent ability to ensure that the orientation of the seconds wheel 8 is maintained in the event of an impact.

[0135] More precisely, the 240 seconds jumper advantageously has teeth, for example machinable by electroerosion, allowing the seconds wheel 8 to be locked by obstacle and not by friction.

[0136] This toothing is designed to limit as much as possible any jump of the seconds hand when the teeth of the 240 seconds jumper and of the seconds wheel 8 come into contact. For this, the seconds jumper 240 has three teeth, separated from each other by a different pitch than that of the teeth of the seconds wheel 8, these teeth being therefore distributed in such a way as to be able to index the seconds wheel 8 in three different angular orientations, illustrated in figures 10a, 10b and 10c. As the seconds wheel 8 here has 160 teeth, the pitch is 2.25 °, so the seconds jumper 240 allows the seconds wheel 8 to be blocked every 2.25 / 3 = 0.75 °, which corresponds to a potential jump of the seconds hand of + / - 0.375 °.

[0137] A comparative examination of the illustrations in figures 10a, 10b and 10c makes it possible to see how each of the three teeth of the seconds jumper 240 is likely to cooperate with a tooth of the seconds wheel 8, taken from a group of three adjacent teeth, depending on the angular orientation of the seconds wheel 8 at the moment when the teeth of the seconds jumper 240 come into range of the teeth of the seconds wheel 8.

[0138] It is also understood from such a comparative examination that, advantageously, to limit as much as possible the potential jump of the chronograph seconds hand, it is preferable to provide that the three teeth have a pitch p2 strictly greater than the pitch p1 of the drive teeth and strictly less than (3*p1) / 2.

[0139] Furthermore, the teeth of the 240 seconds jumper also have the particularity of being drawn with a pulling angle, like a non-return ratchet, in such a way that the 240 seconds jumper can lock automatically under the action of a restoring torque exerted on it by the seconds counter 2. From then on, this 240 seconds jumper can remain in position and prevent the seconds counter 2 from returning backwards, even in the absence of any pre-stressing.

[0140] More specifically here, as will emerge in more detail from the rest of the description, the seconds wheel 8 is intended to be driven in rotation by the watch movement in the counterclockwise direction of rotation in the view of figures 10a to 10c during the measurement of a time. Such a rotation induces an increasing load on the elastic return member 20 which will thus tend to rotate the seconds wheel 8 in the direction of rotation clockwise via rack 14 and pinion 12. As long as the seconds wheel 8 is driven, in START mode, it is kept under tension by a clutch wheel in the counterclockwise direction of rotation, and by the return wheel set in the clockwise direction of rotation. When the chronograph mechanism switches to STOP mode, the connection between the seconds wheel 8 and the clutch wheel is interrupted and the seconds wheel 8 could then be driven into rotation in the clockwise direction of rotation by the return wheel set, in the absence of any countermeasure. It is then that the seconds jumper 240 can perform a braking function by obstacle rather than by friction.As explained above, as soon as its teeth are positioned within range of the teeth of the seconds wheel 8, its pulling angle ensures the almost immediate locking of the seconds wheel 8 by the stop of their teeth, that is to say with a maximum displacement of the seconds hand of + / - 0.375°.

[0141] Figures 11a, 11b and 11c show partial and simplified overall front views of the chronograph mechanism 201 according to the second preferred embodiment variant, in three different respective configurations, in order to explain the general operating principle thereof. More specifically, the chronograph mechanism 201 is illustrated in STOP operating mode in Figure 11a, in START mode in Figure 11b and in RESET mode (actuated from the START mode here, either flyback or return-to-flight type) in Figure 11c.

[0142] Just as in the case of the first embodiment variant, the second preferred embodiment variant advantageously provides, but without limitation, the implementation of two commands, a START / STOP (numerical reference 82, visible in figures 12a and 12b) and a RESET (numerical reference 84 in figure 15).

[0143] Figures 12a and 12b illustrate the interaction between the START / STOP control and a control member also having the form of a column wheel 88. More precisely, Figure 12a illustrates the START / STOP control 82 and the column wheel 88 in the rest position, while Figure 12b illustrates this device when the START / STOP control 82 is at the end of its travel, after having caused a rotation of one step of the column wheel 88.

[0144] At rest, the START / STOP control 82 is positioned by its return spring which presses it against a stop (not visible), its pawl 86 then being located behind the column wheel 88, which is indexed by its jumper 90.

[0145] When a user exerts pressure on a push button adapted to actuate the START / STOP control 82, the latter begins to rotate in the clockwise direction of rotation, as seen in Figures 12a and 12b, until the pawl 86 comes into contact with the teeth of the column wheel 88. When the user's action continues, the column wheel 88 begins to rotate and its jumper 90 is raised until its tip reaches the top of a tooth of the column wheel 88. Once the top of the tooth in question crosses the tip of the jumper 90, the latter exerts a force on the top of the tooth to push it back and thus pivot the column wheel 88 in the counterclockwise direction of rotation as seen in Figures 12a and 12b.If a tooth of column wheel 88 contacts pawl 86 during the jump caused by jumper 90, pawl 86 pivots on START / STOP control 82 to allow column wheel 88 to pivot directly to its next equilibrium position rather than remaining stuck for a moment in an intermediate position.

[0146] An additional stroke on the pusher ensures that the function is activated by driving the START / STOP control 82 and its pawl 86 to their maximum position as in Figure 12b. When the user releases pressure on the pusher, the return spring of the START / STOP control 82 returns it to its initial position, as illustrated in Figure 12a, the pawl 86 retracting as it passes over the teeth of the column wheel 88 during this movement.

[0147] Thanks to this construction, it is for example possible to implement a pusher stroke of 0.3 mm and a force between 1.5 N and 2 N, with ideally a net force release of at least 1 N at the end of the stroke, to have a qualitative feeling and a satisfactory "click" effect for the user.

[0148] Returning to Figures 11a to 11c, it can be seen that the column wheel 88 cooperates with a clutch device, via an articulated intermediate control lever 202 which it comprises, the latter being arranged to be able to cooperate with a clutch lever 204, to move it between a disengaged position and an engaged position, according to a kinematics illustrated in Figures 13a, 13b and 13c, corresponding to the transition from STOP mode to START mode.

[0149] Figure 13a illustrates the configuration of the chronograph mechanism 201 when it is in STOP mode, the clutch device then being in a disengaged state.

[0150] The beak of the intermediate control lever 202 rests on a column of the column wheel 88. In this orientation, the intermediate control lever 202 acts on the clutch lever 204 to position it in a first extreme position following a clockwise rotation in the view of FIG. 13a, this position being its disengaged position. It is advantageous to provide one or more stops 206, integral with the frame 80 of the watch movement, arranged to define this extreme position of the clutch lever 204, or even its second extreme position, engaged, as is the case here. For this purpose, the stops 206 are engaged in slots 208 adapted to the clutch lever 204, at least one of which is closed at its two ends.

[0151] It can also be seen in Figures 13a to 13c that the intermediate control lever 202 carries an actuator 210, here preferably having the shape of a straight spring, made in one piece with the intermediate control lever 202 by way of non-limiting illustration. The actuator 210 is arranged so as to be able to cooperate with the seconds jumper 240 in a manner which will be described below.

[0152] A return spring 212 is also provided to tend to push the beak of the intermediate control lever 202 towards the column wheel 88, in a conventional manner.

[0153] In the STOP operating mode illustrated in Figure 13a, the clutch rocker 204 being in its disengaged position, its clutch wheel 214, which is in permanent engagement with the drive wheel 10 of the watch movement, is not engaged with the seconds wheel 8 which is therefore not driven. However, as explained above, in the absence of a drive, the seconds wheel 8 is potentially subject to a return torque exerted on it by the seconds rack 14 of its return wheel set, if it is not in its zero position, this torque tending to make it rotate in the clockwise direction in the view of figures 13a to 13c. Thus, to avoid such rotation of the seconds wheel 8 in the STOP mode, it is preferable to ensure that the teeth of the seconds jumper 240 are positioned in the passage of the teeth of the seconds wheel 8. This is why the actuator 210 is arranged in an active position, to slightly push the seconds jumper 240, in the counterclockwise rotation direction in the view of figures 13a to 13c, to bring it closer to the seconds wheel 8 and ensure the locking of the latter.

[0154] When the START / STOP push button (not visible) is actuated by a user, the START / STOP control 82 causes the column wheel 88 to rotate in the counterclockwise direction of rotation in the view of Figures 13a to 13c, which has the effect of positioning a gap between two columns opposite the beak of the intermediate control lever 202, as illustrated in Figures 13b and 13c.

[0155] The intermediate control lever 202 begins to fall between the columns of the column wheel 88 in the configuration of Figure 13b, in particular under the effect of the action of its return spring 212. At the same time, the clutch lever 204 begins to pivot in the counterclockwise direction of rotation in the view of Figure 13b, until finally reaching its engaged position illustrated in Figure 13c, in which the clutch wheel 214 is engaged with the seconds wheel 8 to drive it in counterclockwise rotation.

[0156] It is also noted that by pivoting counterclockwise, the intermediate control lever 202 has driven the actuator 210 in the same direction, into an inactive position, thus moving it away from the seconds jumper 240 which is therefore freed from it. If the cutting of the teeth of the seconds jumper 240 is such that the latter does not oppose the drive of the seconds wheel 8 by the clutch wheel 214, the fact that the seconds jumper 240 is released by the actuator 210 allows it to possibly completely disengage from the teeth of the seconds wheel 8 in the START mode, which is more favorable from the point of view of possible energy losses through friction than if the jumper remained permanently in contact with the seconds wheel 8.

[0157] The perspective view of Figure 14 illustrates the relative arrangement between the wheel of the drive wheel 10 of the watch movement, the clutch wheel 214 and the seconds wheel 8, to clarify how the clutch device according to the second preferred embodiment behaves when changing state, in relation to the illustrations of Figures 13a to 13c.

[0158] The axis of rotation of the drive wheel 10 is fixed, as is that of the chronograph seconds wheel 8. The clutch wheel 214 is carried by a shaft 216 with which it is integral, the latter being housed between two fixed bearings (not shown) carried by the frame 80 of the watch movement, so as to be able to move axially by sliding in the bearings (along a distance which may be for example of the order of 0.1 to 0.4 mm, preferably between 0.2 and 0.3 mm). The relative positioning of the wheel of the drive wheel set 10 and the seconds wheel 8, in particular along the direction of the thickness of the watch movement, and their respective thicknesses are such that the clutch wheel 214 can occupy a first axial position, disengaged, in which it is engaged only with the drive wheel set 10 and a second axial position, engaged, in which it is engaged both with the drive wheel set 10 and with the seconds wheel 8.

[0159] It can also be seen in Figure 14 that the clutch wheel 214 can advantageously have a beveled cut of its teeth, to avoid remaining in contact, tooth on tooth, on the seconds wheel 8 when it moves in its direction when passing from its disengaged position to its engaged position.

[0160] A comparative examination of Figures 13a to 13c highlights the fact that the clutch device comprises a clutch spring 218 arranged to act on the shaft 216 of the clutch wheel 214 and tend to push it axially in a predefined direction. Advantageously, the clutch spring 218 here acts on the clutch wheel 214 to push it towards its engaged position. Thus, the action of the clutch spring 218 on the shaft 216 generates more friction in STOP operating mode than in START mode, which generally makes it possible to move towards the direction of balancing the respective loads that the drive wheel 10 undergoes in the two operating modes, and therefore the disturbances that the oscillator of the associated watch movement undergoes. Indeed, when switching from STOP mode to START mode, the load due to the clutch spring 218 decreases significantly, but a new load linked to the driving of the chronograph gear train is applied at the same time to the drive wheel 10.Furthermore, the application of a load by the clutch spring 218 on the shaft 216, in STOP mode, allows the clutch wheel 214 not to wobble in this operating mode since it remains in tension with the wheel of the drive mobile 10.

[0161] Furthermore, the clutch lever 204 is arranged to act, on demand, on the shaft 216 of the clutch wheel 214 against the action of the clutch spring 218. Thus, in the STOP mode illustrated in FIG. 13a, the clutch lever 204 is in a position such that it has a suitable stop (not visible, having an inclined plane similar to the clamps of a conventional vertical clutch) opposite the shaft 216 of the clutch wheel 214 to push it towards the front of the figure, in such a way that it is in its disengaged position, that is to say that it is not engaged with the seconds wheel 8. It is advantageous to provide that the shaft 216 has a slight bevel at its end cooperating with the stop of the clutch lever 204.

[0162] When the column wheel 88 is actuated to release the beak of the intermediate control lever 202 and allow it to fall between two columns, the clutch lever 204 pivots in the counterclockwise direction of rotation, as illustrated in Figure 13b. Its stop then begins to disengage from the shaft 216 of the clutch wheel 214 which can begin to move in the direction of its axis of rotation, to move closer from the axial level of the seconds wheel 8, under the effect of the action it undergoes from the clutch spring 218. This movement is therefore made here in the direction of the rear of the illustration in figure 13b.

[0163] Once the clutch lever 204 has released the clutch wheel 214, as illustrated in FIG. 13c, the latter has reached an axial, engaged position, such that it is engaged with the seconds wheel 8 to drive it in rotation from the movements of the drive wheel 10.

[0164] It will be noted that, advantageously, the bearing of the clutch wheel 214 located on the side of the clutch spring 218 can be arranged in such a way that the clutch spring 218 can bear on it and is no longer in contact with the shaft 216 of the clutch wheel 214 when the latter occupies its engaged position. Thus, in this case, the clutch spring 218 no longer applies any load to the gear train in START operating mode and therefore no longer generates any friction.

[0165] Preferably, but optionally, it may be provided that the clutch lever 204 carries a locking pin 220 arranged so as to be positioned above the clutch wheel 214 when the latter moves into its engaged position, as illustrated in FIG. 13c. Indeed, the preload of the clutch spring 218 is not sufficient to retain the clutch wheel 214 in this position in the event of a significant shock, for example of 500 G, with a component following the direction of the thickness of the watch movement. The locking pin 220 thus makes it possible to prevent disengagement in the event of a shock, by limiting the axial displacement of the clutch wheel 214.

[0166] It follows that the clutch device according to the second preferred embodiment variant combines the advantages of conventional horizontal and vertical clutches, without having their disadvantages.

[0167] Furthermore, it will be noted that the fact of having linked two functions to the same component, namely the clutch device and the actuator 210 which controls the seconds jumper 240, the latter in particular fulfilling a function equivalent to that of the conventional brake, makes it possible to control perfectly the synchronization of the two functions concerned. More precisely, this characteristic makes it possible to guarantee perfect synchronization between the moment when the clutch wheel 214 begins to drive the seconds wheel 8 and the moment when the seconds jumper 240 releases it (it is especially important to avoid the seconds jumper 240 releasing the seconds wheel 8 too early, otherwise it could be driven backwards under the effect of the action of its return wheel) and, above all, it makes it possible to guarantee the locking of the seconds wheel 8 by its jumper 240 at the precise moment when its drive by the clutch wheel 214 ceases, when switching from START mode to STOP mode.Furthermore, this synchronization combined with the cutting of the teeth of the 240 seconds jumper prevents any possibility of the chronograph seconds hand jumping backwards when switching from STOP mode to START mode, as can happen with conventional chronograph mechanisms, particularly with horizontal clutch.

[0168] The transition from START mode to STOP mode is achieved by reversing the steps just presented. A further rotation of the column wheel 88 by one step causes a column to be positioned opposite the beak of the intermediate control lever 202, causing both a movement of the actuator 210 towards the seconds jumper 240 and a movement of the clutch lever 204 in the clockwise direction in the view of FIGS. 13a to 13c. During this movement, the stop of the clutch lever 204 returns to position itself opposite the shaft 216 of the clutch wheel 214 to push the latter out of reach of the seconds wheel 8 against the action of the clutch spring 218.

[0169] Returning to Figures 11a to 11c, the reset device according to the second preferred embodiment will be described below, also in relation to Figure 15 which illustrates a construction detail.

[0170] Just as in the case of the first preferred embodiment, the principle of resetting here, in the context of the second preferred embodiment, consists of simultaneously releasing all the chronograph counters 2, 4 and 6 from the constraints which lock them, so that they can be reset independently of each other under the action of their return mobiles. This simultaneous release is implemented by an all-or-nothing control system of robust construction and offering a feel similar to the START / STOP control.

[0171] This control system includes in particular a control mobile 250 intended to cooperate on demand, by moving from a START / STOP position to a RESET position, with all the jumpers and pawls capable of locking the different chronograph counters.

[0172] Figure 15 illustrates, in isolation, the control mobile 250 as well as its actuating mechanism, in order to simplify understanding. The operating principle of the actuating mechanism according to this second preferred embodiment variant is similar to that of the actuating mechanism according to the first preferred embodiment variant.

[0173] The actuating mechanism comprises a reset member 252, intended to receive an impulse in response to an action by a user on a suitable external control member (not shown), and assembled to the frame 80 of the watch movement so as to be able to pivot along an axis of rotation coinciding with the axis of its fixing screw 254. The reset member 252 is held in a rest position, by default, under the effect of the action of a return spring 256, made here in a single piece with the reset member 252, by way of non-limiting illustration. Receiving an impulse causes the reset member 252 to rotate in the clockwise direction of rotation in the view of FIG. 15, and aims to induce the control wheel set 250 to rotate in the counterclockwise direction of rotation, to make it move from its START / STOP position to its RESET position.

[0174] A lock 258 is rotatably mounted on the frame of the watch movement, being positioned by default opposite a beak 260 of the control wheel set 250 to prevent the latter from rotating. A return spring 262 made in one piece with the lock 258, and bearing on a fixed pin 264, ensures the default positioning of the lock 258.

[0175] The reset member 252 carries a trigger pin 266 arranged to pivot the latch 258 in the counterclockwise rotation direction in the view of Figure 15 when the reset member 252 pivots (clockwise). The reset member 252 also carries an actuating pin 268 arranged to cooperate with a reset spring 270 and charge it as long as the latch 258 maintains the locking of the control wheel 250.

[0176] Once the latch 258 pivots sufficiently to release the beak 260 of the control wheel 250, the reset spring 270 can suddenly release its energy, causing the control wheel 250 to rotate in the counterclockwise direction of rotation in the view of FIG. 15, towards its RESET position, the latter rotating with it its first 272, second 274, third 276, fourth 278, fifth 280 and sixth arms 282, these defining neutralization devices similar to those already described in relation to the first preferred embodiment variant.

[0177] When the reset member 252 is released, it quickly returns to its rest position under the effect of the action of its return spring 256, while the lock 258 remains blocked, initially, due to the presence of the beak 260 of the control wheel set 250 on its return path. The reset member 252 drives the control wheel set 250 with it, by the action of its actuating pin 268 on a rigid portion of the latter, and the lock 258 returns to its rest position once the beak 260 releases it.

[0178] It is understood from the above that the control wheel 250 has two different angular positions within the framework of this second preferred embodiment variant, a first STOP (or START) position common to the two START and STOP operating modes of the chronograph mechanism 201, and a second RESET position for the RESET operating mode.

[0179] Thus, the control mobile 250 is illustrated in its first position (STARTZ)STOP in figures 11a and 11b which partially illustrate the chronograph mechanism 201 respectively in its STOP operating mode and in its START operating mode.

[0180] Figure 11c illustrates the RESET operating mode and shows how the chronograph mechanism 201 behaves when the reset member 252 is actuated while the measurement of a time is in progress, i.e. in START mode, which corresponds to the function commonly referred to as "flyback".

[0181] It can be seen that the beak of the intermediate control lever 202 is still located between two columns of the column wheel 88 and therefore the clutch device should potentially be able to occupy its engaged state. However, it appears that the control wheel 250 acts on the clutch lever 204, via its first arm 272, to rotate it in the clockwise direction of rotation by passing from the configuration of Figure 11 b to that of Figure 11 c, and thus push it back into its disengaged position. This is also evident from the position of the beak of the intermediate control lever 202 which has moved away from the column wheel 88 by passing from the configuration of Figure 11 b to that of Figure 11 c.

[0182] At the same time, it emerges from a comparative examination of figures 11 b (or 11 a) and 11 c that the other arms of the control mobile 250 move to actuate the different jumpers and pawls by passing from the configuration of figure 11 b (or 11 a) to that of figure 11 c.

[0183] More precisely, the second arm 274 of the control wheel set 250 cooperates with the jumper 44 of the minute counter 4 to push it back and allow the counter to rotate freely, while the third arm 276 cooperates with the pawl 60 of the minute counter 4 to ensure that it is not located on the path of the teeth of the minute wheel 22 during the reset. Thus, the minute counter 4 is freed from any constraint and can be returned to its zero position (initial, different from 0 in the case of a countdown mechanism) under the effect of the action of its return wheel set.

[0184] The fourth arm 278 of the control wheel 250 cooperates with the seconds jumper 240 to at least define a stop and prevent the jumper from pivoting in the direction of the seconds wheel 8, to release the seconds counter. seconds 2 from any constraint and allow it to return to its zero position (or possibly initial in the case of a countdown mechanism) under the effect of the action of its return wheel. It may optionally be provided, in general, that the fourth arm 278 slightly pushes the seconds jumper 240 back during the reset, opposing the actuator 210. Such an action is in any case necessary if the reset is activated from the STOP mode, in which the seconds jumper 240 is positioned against the seconds wheel 8.

[0185] Finally, the fifth arm 280 of the control wheel set 250 cooperates with the jumper 46 of the hour counter 6 to push it back and allow the counter to rotate freely, while the sixth arm 282 cooperates with the pawl 72 of the hour counter 6 to ensure that it is not located on the path of the teeth of the hour wheel 30. Thus, the hour counter 6 is freed from any constraint and can be returned to its zero position (or initial in the case of a countdown mechanism) under the effect of the action of its return wheel set.

[0186] When the reset member 252 is released, the control wheel 250 can pivot clockwise in the view of FIG. 11c to return to its STOP (or START) position under the effect of its return spring 256 as described above. The jumpers and pawls are then also released by the various arms of the control wheel 250 and can return to the position they occupied before the reset was triggered. When the reset is actuated from the START mode, a new measurement of a time starts immediately after the release of the reset member 252.

[0187] It will be noted that the reset can also be carried out in a similar manner with a prior stop of the measurement of a time, that is to say when the chronograph mechanism 201 is in the STOP operating mode. In this case, the second to sixth arms of the control wheel set 250 cooperate in a similar manner to that just described with the various jumpers and pawls of the various counters, while the first arm 272 is positioned in the immediate vicinity of the lever clutch 204 without pushing it back, since it is then already in its disengaged position.

[0188] It will also be noted that the control wheel 250 according to the second preferred embodiment variant has only two different positions (whereas the control wheel 100 of the first embodiment variant had three different positions), a STOP position (for example, or START) associated with the START and STOP operating modes of the chronograph mechanism 201, and a RESET position associated with the RESET operating mode of the chronograph mechanism 201, the transition from the START operating mode to the STOP mode of the chronograph mechanism 201, and vice versa, being implemented independently of the control wheel 250.

[0189] The description of the second embodiment variant allows a better understanding of how it is possible to adapt the present teaching in the context of the production of a flyback type chronograph mechanism for a watch movement having a simplified, reliable and robust construction, while notably limiting the force that a user must apply to the corresponding pushers to actuate it, which improves its ergonomics. In addition, as already mentioned previously, this construction also makes it possible to limit the travel and the actuating force of the control pushers associated with this chronograph mechanism, to actuate the various functions thereof, which in particular makes it possible to improve the ergonomics and design of these pushers by improving their integration into the caseband.

[0190] The preceding description is intended to describe a particular embodiment by way of non-limiting illustration (chronograph mechanism, but a countdown mechanism can also benefit from the advantages of the present invention) and the invention is not limited to the implementation of certain particular characteristics which have just been described, such as for example the shape of the return mobiles or the levers allowing them to be connected to each other, the architecture of the START / STOP and RESET controls, or even the fact that certain elastic members are made in one piece with components particularities of the mechanism. Indeed, the various elastic members of the chronograph mechanism which has just been described could be constructed differently (in particular by reversing their direction of installation). It will be noted, for example, that the return mobiles illustrated in the appended figures have a preferred but optional characteristic: they are balanced from the point of view of mass distribution, each rack being associated with a counterweight, in order to limit the risks of damage to the mechanism in the event of impact, but the person skilled in the art may choose to balance these various components in a manner adapted to his specific needs without departing from the scope of the present invention as defined by the appended set of claims.

Claims

Claims 1. Mechanism (1; 201) for measuring time, for a clock movement, comprising a counter of a unit of time comprising: - a display wheel intended to ensure the driving of a display member of said unit of time and capable of being put into kinematic connection with a drive wheel (10) of the watch movement, on demand, to be able to be driven in rotation in a predefined direction of rotation from a predefined position throughout the measurement of a time, - a return wheel, intended to be pivotally mounted on a frame element (80) so as to be able to pivot between an initial position, associated with said predefined position of said display wheel, and a final position, said display wheel and said return wheel being arranged in such a way that the latter pivots from its initial position to its final position when said display wheel travels substantially one revolution from its predefined position, - an elastic return member (20) arranged to act on said return wheel set and tend to return it to its initial position, characterized in that said display wheel set further comprises a toothing arranged in engagement with a toothing of said return wheel set, said toothing of said display wheel set having a truncated portion, intended to allow temporary uncoupling between said display wheel set and said return wheel set when the latter reaches its final position, causing a retrograde movement of said return wheel set to its initial position at each complete revolution of said display wheel set, under the effect of the action of said elastic return member (20).

2. Mechanism (1; 201) according to claim 1, characterized in that it also comprises a jumper (40; 240) arranged to be able to cooperate with said display wheel set and prevent its rotation at least in the direction of rotation opposite to said predefined direction of rotation when the measurement of a time is inactive, as well as a neutralization device (132; 278) for said jumper (40; 240), actuable on demand, arranged to allow a return of said display wheel set in its predefined position under the effect of the action of said elastic return member (20) on said return wheel set. Mechanism (201) according to claim 2, characterized in that said display wheel set comprises a plate having a drive toothing by which said display wheel set is capable of being put into kinematic connection with the drive wheel set (10) of the watch movement, and in that said jumper (240) comprises three teeth capable of cooperating with said drive toothing to prevent rotation of said display wheel set in the direction of rotation opposite to said predefined direction of rotation, said three teeth having a pitch p2 strictly greater than the pitch p1 of said drive toothing and strictly less than (3*p1) / 2.Mechanism (1; 201) according to one of claims 1 to 3, characterized in that said time unit counter is a seconds counter (2) arranged in such a way that said display wheel set makes a complete revolution in sixty seconds, in that the mechanism for measuring a time (1; 201) also comprises a minute counter (4) of measured times comprising a minute display wheel set intended to ensure the driving of a member for displaying the minutes of measured times, and in that said return wheel set has a kinematic connection with a minute pawl (60) arranged to cooperate with said minute display wheel set and to rotate it, to increment or decrement said minute counter (4), at each complete revolution of said display wheel set.Mechanism (1; 201) according to claim 4, characterized in that said elastic return member (20) is arranged to act on said return wheel set via a first transmission lever (50) carrying said minute pawl (60). Mechanism (1; 201) according to claim 4 or 5, characterized in that said minute display wheel set further comprises a toothing arranged in engagement with a minute return wheel set intended to be. pivotally mounted on a frame element (80), so as to be able to pivot between an initial position and a final position, both associated with a predefined position of said minute display wheel set, in that the minute counter (4) further comprises an elastic minute return member (28) arranged to act on said minute return wheel set and tend to return it to its initial position, in that said toothing of said minute display wheel set and said minute return wheel set are arranged in such a way that the latter pivots from its initial position to its final position when said minute display wheel set travels a complete revolution from its predefined position, and in that said toothing of said minute display wheel set has a truncated portion,intended to allow temporary uncoupling between said minute display wheel set and said minute return wheel set when the latter reaches its final position, causing a retrograde movement of said minute return wheel set to its initial position at each complete revolution of said minute display wheel set, under the effect of the action of said elastic minute return member (28). Mechanism (1; 201) according to claim 6, characterized in that said minute counter (4) is arranged in such a way that said minute display wheel set makes a complete revolution in sixty minutes, more preferably in thirty minutes, in that the mechanism for measuring a time (1; 201) also comprises an hour counter (6) of measured times comprising an hour display wheel set intended to ensure the driving of a member for displaying the hours of measured times,and in that said minute return wheel has a kinematic connection with an hour ratchet (72) arranged to cooperate with said hour display wheel and rotate it, to increment or decrement said hour counter (6), at each complete revolution of said minute display wheel., 8. Mechanism (1; 201) according to claim 7, characterized in that said elastic minute return member (28) is arranged to act on said minute return wheel set via a second transmission lever (62) carrying said hour pawl (72).

9. Mechanism (1; 201) according to claim 7 or 8, characterized in that said hour display wheel set further comprises a toothing arranged in engagement with an hour return wheel set intended to be pivotally mounted on a frame element (80), so as to be able to pivot between an initial position and a final position, both associated with a predefined position of said hour display wheel set, in that the hour counter further comprises an elastic hour return member (36) arranged to act on said hour return wheel set and tend to return it to its initial position, in that said toothing of said hour display wheel set and said hour return wheel set are arranged in such a way that the latter pivots from its initial position to its final position when said hour display wheel set travels a complete revolution from its predefined position,and in that said toothing of said hour display wheel has a truncated portion, intended to allow temporary uncoupling between said hour display wheel and said hour return wheel when the latter reaches its final position, causing a retrograde movement of said hour return wheel to its initial position at each complete revolution of said hour display wheel, under the effect of the action of said elastic hour return member (36)., 10. Mechanism (1; 201) according to claim 9, characterized in that it also comprises an hour jumper (46) acting on said hour display wheel set to allow its rotation only in the direction of its normal drive when the measurement of a time is in progress, as well as a neutralization device (138; 280) of said hour jumper (46), actuable on demand, arranged to allow a return of said hour display wheel set to its predefined position under the effect of the action of said elastic hour return member (36) on said hour return wheel set.

11. Mechanism (1; 201) according to one of claims 6 to 10, characterized in that it also comprises a minute jumper (44) acting on said minute display wheel set to allow its rotation only in the direction of its normal drive when the measurement of a time is in progress, as well as a neutralization device (134; 274) of said minute jumper (44), actuable on demand, arranged to allow a return of said minute display wheel set to its predefined position under the effect of the action of said elastic minute return member (28) on said minute return wheel set.

12. Mechanism (1; 201) according to claim 2 or 3 and claim 11, characterized in that it comprises a control wheel set (100; 250) capable of pivoting on demand between at least one STOP position and one RESET position, and in that said neutralization device (132; 278) for said jumper (40; 240) and said neutralization device (134; 274) for said minute jumper (44) are arranged on said control wheel set (100; 250) in such a way that they can act substantially simultaneously on their respective jumpers (40, 44; 240) to neutralize them when said control wheel set (100; 250) is moved from its STOP position to its RESET position.

13. Mechanism (1; 201) according to claims 10 and 12, characterized in that said neutralization device (138; 280) of said hour jumper (46) is also arranged on said control wheel set (100; 250), in such a way that all said neutralization devices (132, 134, 138; 278, 274, 280) can act substantially simultaneously on their respective jumpers (40, 44, 46; 240) to neutralize them when said control wheel set (100; 250) is moved from its STOP position to its RESET position.

14. Mechanism (1) according to claim 12 or 13, said control wheel (100) further carrying a clutch wheel (104) capable of occupying an engaged position, associated with an additional position, START, of said control wheel (100), to establish a kinematic connection between said display wheel and the drive wheel (10) of the watch movement, or a disengaged position, associated with said STOP and RESET positions of said control wheel (100), to interrupt said kinematic connection. Mechanism (1) according to claim 14, characterized in that it comprises a control member (88) capable of switching on demand between a first state, START, and a second state, STOP, to pivot an intermediate control rocker (92) between a first position, START, and a second position, STOP, said intermediate control rocker (92) being arranged to actuate said control wheel (100), by passing from one position to the other, and to pivot it between its START and STOP positions.Mechanism (1) according to claim 15, characterized in that it comprises a reset member (110) arranged to be able to act on said intermediate control lever (92) and make it pass from one of its first and second positions to a third position, RESET, in which it actuates said control wheel (100) to make it pivot into its RESET position. Mechanism (1) according to claim 15 or 16, characterized in that it comprises a spring (94) arranged to tend to position said intermediate control lever (92) in its first position.Mechanism (201) according to claim 12 or 13, comprising a clutch device comprising a clutch wheel (214) and capable of switching on demand between an engaged state, in which said clutch wheel (214) occupies an engaged position, to establish a kinematic connection between said display wheel set and the drive wheel set (10) of the watch movement, and a disengaged state, in which said clutch wheel (214) occupies a disengaged position, to interrupt said kinematic connection, characterized in that said control wheel set (250) is arranged to act on said clutch device, by passing from its STOP position to its RESET position, to switch or maintain said clutch device in its disengaged state.

19. Mechanism (201) according to claims 3 and 18, characterized in that it comprises an actuator (210) movable between an active position, in which it cooperates with said jumper (240) so as to position at least one of its teeth within reach of the drive teeth of the plate of said display wheel, and an inactive position, in which it leaves the jumper (240) free to place all of its teeth out of reach of said drive teeth, and in that said clutch device is further arranged to cooperate with said actuator (210) and make it take its active position in the disengaged state and its inactive position in the engaged state.

20. Mechanism (201) according to claim 19, said clutch device comprising an intermediate control rocker (202) arranged to act on said clutch wheel (214) and define its position, the mechanism being characterized in that said intermediate control rocker (202) carries said actuator (210).

21. Clock movement comprising a mechanism for measuring time (1; 201) according to one of claims 1 to 20.

22. A watch movement according to claim 21, wherein said mechanism (1; 201) for measuring time is a chronograph mechanism.

23. Timepiece comprising a watch movement according to claim 21 or 22.

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