Device for resetting a component indicating a time-related magnitude to a predetermined position

Abstract

The device (100) has an energy accumulator (9) and a return element (1) for returning an indicator member i.e. seconds hand (13) indicative of the parameter connected with time to a predetermined position. The return element is powered by energy from the accumulator, where the energy is supplied to the energy accumulator by a user via a push button (4) for resetting the seconds hand to the predetermined position, and the push button is manipulatable by a user. The seconds hand is kinematically linked to a drive wheel (15) by friction or by a clutch. An independent claim is also included for a timepiece.

Description

[0001] The invention relates to a device for returning an indicator of a time-related quantity, or temporal quantity, to a predetermined position, in particular a flyback device. The invention also relates to a watch movement or a timepiece equipped with such a device.

[0002] There are a number of wristwatches on the market whose seconds hand can be reset to zero and then restart instantly. This function is commonly called "flyback" and should be distinguished from split-seconds mechanisms, which are sometimes also referred to as "flyback."

[0003] Such a function is commonly performed by a synchronous reset device controlled by a actuator whose actuation resets the seconds hand to zero, and whose release causes it to restart. This should be distinguished from a non-synchronous reset device in which the action of a control actuator induces, on the one hand, the resetting of the seconds hand, and on the other hand, its restart. As shown in the figure 1 The operation of the synchronous mechanism is thus synchronized with the wearer's actions on the wristwatch; pressing a pusher resets the chronograph, and releasing it restarts the seconds hand. Consequently, the speed of the timing function depends on the user's dexterity. The functionality of such a device is therefore limited compared to that of a non-synchronous reset mechanism. Furthermore, this synchronous device is generally used in chronograph movements. In this case, the flyback mechanism relies on the chronograph's clutch system and the large number of components required for its operation. Another solution is to mount the seconds hand using friction within the main movement. This design has the advantage of using fewer parts and does not require a clutch.However, friction is subject to wear, and prolonged operation of the control mechanism risks disrupting the movement's timekeeping, or even causing the watch to stop. This is because friction consumes energy, which is drawn from the energy required for the movement's proper chronometric function.

[0004] Document CH183262 describes a modification to a horizontal clutch chronograph mechanism. Hammers are adapted to allow the counter chain to disengage during an unintentional reset without first stopping the chronograph. Releasing a push-button disconnects the hammers from the reset hearts and causes the counter chain to re-engage. This mechanism is dependent on the entire basic chronograph mechanism. Furthermore, the proper functioning of such a system requires a significant number of adjustments and precludes the implementation of a non-synchronous reset device.

[0005] Document CH 214664 concerns a horizontal clutch device without a triggering system (toggles, trigger levers, or column wheel). A control element is directly linked to a flyback mechanism. Pressing a push button causes a hammer to move, which in turn acts on a reset point and disengages the counting chain located on a rocker arm of the movement's kinematic chain.

[0006] Releasing the push-button restarts the seconds hand. Despite having fewer components than a typical chronograph mechanism, synchronizing the reset and disengagement controls is particularly challenging. Furthermore, this system does not allow for the implementation of a non-synchronous reset mechanism.

[0007] Document EP1136894A1 describes a chronograph mechanism with a vertical clutch that includes a hammer designed to actuate additional disengagement means in case of in-flight reset. The mechanism is disengaged, and the seconds hand is reset to zero, as long as the user presses a push-button. The proper functioning of this mechanism depends on the development of the vertical clutch and, moreover, requires an additional control to actuate it. Furthermore, such a system does not allow for the implementation of a non-synchronous reset device.

[0008] Document FR1104103 describes a clutchless mechanism. A seconds hand is friction-mounted on a seconds pinion. Pressing a push-button activates a hammer that strikes a reset mechanism for the seconds hand. The friction between the seconds pinion and the seconds hand continues until the user releases the push-button. This synchronous mechanism thus presents the risk of disrupting the movement's timing, or even causing the watch to stop. The hammer is returned to its position by a wire spring when the push-button is released. The seconds hand then rotates again. Consequently, this system does not allow for the implementation of a non-synchronous reset mechanism.

[0009] Document CH698827 describes a synchronous reset device. This device uses a control element designed to cooperate with a return spring, allowing the hammers to return to their rest position once the control element is no longer actuated. Therefore, such a system does not allow for the implementation of a non-synchronous reset device.

[0010] Document CH702157 describes a simplified chronograph device in which actuation of the single control mechanism resets the seconds and minute hands to zero, and releasing it restarts them. The system is reduced to the chronograph's horizontal clutch mechanism and the zeroing device, which are adapted to allow the counting chain to disengage when the hammers strike the hearts. Such a system allows for the implementation of a synchronous reset mechanism using a suitable zeroing device, but does not allow for the adaptation of the control mechanism, the horizontal clutch, and the hammers to define a non-synchronous reset mechanism.

[0011] Document CH678910 describes an adaptation of at least two hammers to allow adjustment of their positioning relative to their respective cores. This document does not disclose any information on how to modify these hammers for possible integration into a system intended to equip a non-synchronous reset device.

[0012] Document EP1936448 describes a time display device activated by a push button. The system comprises a cam, a cam contact attached to a rake, and a pinion that meshes with the rake. The rake is returned to its original position by a return spring as soon as the push button is released. This device thus has a control mechanism that is perfectly synchronized with the display mechanism.

[0013] DE1312184U discloses a timepiece in which hammer 27 has a unidirectional movement when actuated.

[0014] CH253514A unveils a central seconds hand watch featuring a mechanism activated during the winding stem's time-setting stroke 10 to return the central seconds hand to zero.

[0015] Based on these documents, these solutions allow for the implementation of synchronous reset devices in which return elements, namely hammers or rakes, are actuated directly by a control element, possibly by a control element combined with a return spring, independently of any third-party device. In fact, these solutions do not allow for the implementation of a non-synchronous reset device in which the action of a control element induces, firstly, the resetting of a time-related indicator to its predetermined position, and secondly, its restart.

[0016] Document CH192624 describes an embodiment of a flyback device characterized by its asynchronous operation: the seconds hand is reset to zero by pressing a push-button, and then restarted. The push-button's action is transmitted to a reset hammer via a cam and a control lever. The cam is rotatable and interacts with a return spring. The cam has an inclined surface designed to engage with the control lever during the reset. The hammer's action on the heart is interrupted once the control lever reaches the end of the inclined plane. The spring that interacts with the cam allows it to retract, thus interrupting the control lever's action on the hammer, which returns to its initial position under the action of a second return spring, regardless of whether the push-button is still pressed.This mechanism, however, does not eliminate the risk of the seconds hand lagging behind, nor does it prevent the seconds hand from stopping for an extended period, thus disrupting the movement's operation. Furthermore, no feature is provided to generate a clear tactile feedback that the user can feel immediately upon pressing the pusher. Finally, partial depressing of the pusher can cause the seconds hand to partially return to its zero position due to the incomplete action of the hammer on the heart. Such a possibility is undesirable.

[0017] In view of these documents, and more particularly in view of the last document mentioned above, none of the solutions makes it possible to implement a reliable non-synchronous reset device which allows, in a single operation, the instantaneous reset and the instantaneous restart of a time-related indication, for example the second, and this independently of the user's manipulations.

[0018] The object of the invention is to provide a device for resetting a predetermined position of an indicator, preferably asynchronous, remedying the drawbacks mentioned above and improving upon known prior art devices for resetting a predetermined position. In particular, the invention proposes a reliable device for resetting a predetermined position that allows, in a single action by the user, for example, pressing a push-button, a predetermined position of an indicator of a time-related quantity, for example, a seconds hand.

[0019] According to a first aspect of the invention, the device for returning to a predetermined position is defined by claim 1.

[0020] Different embodiments of the device are defined by claims 2 to 7.

[0021] A watch movement according to the invention is defined by claim 8.

[0022] Different embodiments of the movement are defined by claims 9 and 10.

[0023] A timepiece according to the invention is defined by claim 11.

[0024] A method according to the invention is defined by claim 12.

[0025] Different embodiments of the process are defined by claims 13 and 14.

[0026] The attached drawings represent, by way of example, two embodiments of a device for resetting a time-related indication to a predetermined position. There figure 1 is a diagram of a timepiece comprising a synchronous reset device. figure 2 is a diagram of a timepiece comprising a non-synchronous reset device for returning to a predetermined position. figures 3 à 8 These are views of a first embodiment of a device for returning to a predetermined position according to the invention, shown in different configurations. figure 9 is a cross-sectional view of the first embodiment of a device for returning to a predetermined position, the cross-sectional plane of which IX-IX is indicated in the figure 3 . There figure 10 This is a detailed view of a sample hammer-core assembly used to perform the action of returning to a predetermined position. figures 11 à 19 These are views of the hammer-core assembly in successive configurations during a specific repositioning phase. figures 20 et 21 are views of a second embodiment of a device for returning to a predetermined position according to the invention.

[0027] A first embodiment of a device 100 for returning an indicator 13 of a time-related quantity to a predetermined position is described below with reference to figures 2 à 9 This device is intended for use in a watch movement, particularly a wristwatch movement. For example, this device is a flyback mechanism that returns a seconds hand, or any other timekeeping hand, to a predetermined position. Specifically, the predetermined position can be an initial position, a zero position, or any other origin. Preferably, the device is activated by a single action from the user, in particular pressing a push-button. This action, as illustrated in the diagram, allows the user to... figure 2 The device triggers the indicator to return to its predetermined position and then resumes its operation within a tenth of a second. This resumption of operation is therefore considered instantaneous and does not depend on the user releasing the push button, but solely on the time required for the device to complete the function initiated by the user's action. Holding the push button down has no effect on the indicator's operation. Similarly, releasing the push button has no effect on the indicator's operation. The resumption of operation is thus independent of the control element's position.

[0028] The indicating element 13 is kinematically linked by friction to a drive element 15. This drive element is itself driven by a motion transmission chain, including a wheel 19 in a known manner, from a driving element such as a barrel. Thus, in the absence of actuation of the reset device, the indicating element of a time-related quantity is constantly in motion because it is kinematically linked by friction to the driving element.

[0029] The device for returning to the predetermined position mainly comprises an energy accumulator 9 and a return element 1 for the time-related indicator in the predetermined position. The return element is actuated or activated by energy from the accumulator. The device further comprises a motion transmission element from the energy accumulator to the return element and an energy transmission element to the energy accumulator that triggers the actuating or activating of the return element. Energy transmission to the accumulator can be achieved via a push button 4. The actuating or activating of the return element can be controlled by pressing the push button.This push button is user-operable and capable of acting on the energy transmission element to the energy accumulator and triggering the actuation or activation of the return element.

[0030] The return element comprises a hammer 92 adapted to act on a cam 2, in particular a core cam or a core, kinematically rotationally linked to the indicator member 13 and rotatably mounted about an axis 1'. The core 2 is preferably fixed to the indicator member 13. When the return element is actuated or activated, the hammer performs, as described below, a rotational movement about the axis 1', in particular a rotation of one full turn or a rotation of half a turn. The hammer includes a peen 92a designed to cooperate with the core and act on a portion of its profile to cause its rotation until the indicator member reaches the predetermined position. Furthermore, the hammer includes a locking element 92b designed to cooperate with a portion of the core's profile to immobilize the core and thus immobilize the indicator member in the predetermined position.The hammer is generally disc-shaped with a notch forming the peen 92a and a clearance 92c allowing the heart to rotate freely around axis 2' when the hammer is in its rest position. Unlike hammers mounted to pivot around known axes in the prior art, this hammer moves in only one direction of rotation. It completes, for example, a full turn or a fraction of a turn. It does not return to its initial position by reversing the direction of its movement or rotation. The hammer moves unidirectionally during its actuation, that is, from its rest position to its rest position via a position of contact with the heart with which it cooperates.

[0031] The motion transmission element from the energy accumulator 9 to the return element 1 includes a first cam 7 kinematically linked to the return element, in particular kinematically linked to the hammer. Specifically, the first cam 7 can be fixed to the hammer. The first cam 7 is therefore rotatable about the axis 1'. The motion transmission element also includes a roller 8a returned to contact against the first cam 7 by the energy accumulator, in particular by an elastic element, such as a leaf spring 91 of the energy accumulator. This roller is mounted to rotate freely and is intended to roll on the profile of the first cam 7. For example, the roller 8a is mounted to rotate freely on a lever 8 pivotally mounted about an axis 8'. In this case, the spring 91 acts on the lever to return the roller 8a against the first cam 7.Alternatively, the lever 8 and the spring 91 can be combined into a single piece, and the end of the lever 8 can cooperate with the cam profile 7, independently of the roller 8a.

[0032] The energy transmission and activation triggering element for the return element comprises a rocker 3 and a second cam 6. The second cam 6 is kinematically rotationally linked to the return element 1. For example, the second cam 6 is fixed to the first cam 7. This attachment can be achieved, as shown, by a notch on the second cam cooperating with a pin on the first cam 7. The rocker 3 is capable of acting on the second cam 6 to cause its rotation. To this end, the second cam 6 includes a notch 6a designed to cooperate with the rocker 3 and, more precisely, with a finger 5 pivotally mounted about an axis 5' and returned to a rest position against a stop 12 by an elastic element 11. The finger 5 is therefore retractable. Thus, the rocker 3 acts on the second cam 6 via the finger 5. The rocker is pivotally mounted about an axis 3'.The rocker's pivoting motion is caused by the translation of the pusher 4 when it is activated by the user. This actuation of the rocker is achieved against the action of a return spring 10. This spring returns the rocker to its rest position when the pusher is no longer pressed. Thus, its functionality is equivalent to that of springs designed to cooperate with the return elements and / or control mechanisms of known state-of-the-art reset devices.

[0033] The push button can of course be replaced by any type of control device.

[0034] The indicator organ 13 and the heart 2 can be driven onto an axis 14 as shown in the figure 9 The wheel 15 of the indicator 13 is friction-mounted on this assembly via a spring 16 to disengage the indicator from the transmission chain when the indicator returns to its predetermined position. The friction spring 16 is sized to keep the indicator 13 and its wheel 15 connected in the event of an accidental impact, but it is also designed to allow, in all circumstances, the indicator to return to its predetermined position using the energy stored by the spring 91. Optionally, a counterweight 17, attached to the shaft 14, advantageously counterbalances the imbalance due to the indicator and thus minimizes its sensitivity to impacts.

[0035] As depicted in the figure 2 , a device for returning an indicator organ to a predetermined position as described above can be fitted to a watch movement or a watch part.

[0036] The operation of the predetermined positioning device is described below with reference to figures 4A à 8 (which detail the operation of the energy transmission element to the energy accumulator and the triggering of the actuation of the return element) and 11 to 18 (which detail the operation of the return element and its interaction with the indicator organ).

[0037] There figure 4A illustrates the energy transmission element at rest, when the user is not pressing button 4. Pressing this button causes, as shown in figures 4B , 5 , And 7AThe pivoting of the rocker arm 3 around the axis 3' against the action of the spring 10. This pivoting causes the finger 5 to act on the second cam 6 at the notch 6a. This action causes the second cam 6 to rotate around the axis 1'. The rotation of the second cam 6 around the axis 1' causes the first cam 7 to rotate around the same axis. It follows as shown in figures 5 And 7Athat the roller 8a leaves its rest position defined by a first portion 7a of the first cam and arrives at a second portion 7b of the second cam. The rest position defined by the first portion 7a allows, by the action of the spring 91, the first cam 7 to be immobilized in rotation, and therefore to prevent the hammer from rotating when the control member 4 is not actuated. As it travels along the second portion 7b, the roller 8a moves away from the axis 1' of rotation of the first cam. This results in a pivoting of the lever 8 and consequently a deformation of the spring 91, which stores energy supplied by the user during the manipulation of the control member 4. This energy is accumulated via the second profile 7b of the first cam 7, which rotates over an angular range Φ of the rest position illustrated by the figure 11 up to a position represented on the figure 12 where the roller 8a reaches a junction 7d between the second profile 7b and a third profile 7c. Up to this position, the second cam 6 is still driven in rotation by the action of the rocker 3 via the finger 5. This third profile 7c is of the spiral or helical type. Thus, as soon as the roller 8a reaches this profile, as shown in figures 7B , 13 , 14 , 15 , 16 , 17 And 18The return action against the first cam 7 causes a mechanical action of the roller 8a on the first cam 7, creating a mechanical torque around the axis of rotation 1' of the first cam 7. Consequently, the first cam 7 is then driven in rotation by the energy of the spring 91. No further action is required on the control member 4 and the rocker 3. In particular, the control member 4 can be released. The rotation of the hammer 92 takes place in a time on the order of a tenth of a second when the spring 91 releases the accumulated energy by imparting a rotational movement to the first cam 7 via the lever 8 and its roller 8a, which cooperates with the third profile 7c. In the case where the control member is not released, the rotation of the hammer 92 does not interfere with the rocker because, as shown in the figure 8 The rotation of the second cam 6 is intended to unclip the finger 5. To do this, the finger 5, pivoted in 5' on the rocker 3, cooperates with the spring 11 and a stop 12, mounted on the frame, which hold it in position when the control member is not actuated.

[0038] In other words, as long as the hammer 92 does not interfere with the heart 2, the indicator organ 13 is driven in rotation by the transmission chain via the friction linkage, as shown in figures 3 , 4A And 11 for example. When the user actuates the control element 4 and triggers the energy transmission element formed by the rocker 3 and the finger 5 ( figure 4B ), a rotation of the cam 6, and therefore of the hammer 92, is initiated. The roller 8a travels along the second profile 7b of the cam 7 and arrives at the junction 7d of the second and third profiles of the cam 7 as illustrated in figures 5 And 12This cam has then traveled an angle Φ from its initial position, which is shown in the... figure 11 Once this energy accumulation phase is complete, the roller moves along the third profile 7c of the cam 7 until the first contact between the surfaces 92a of the hammer 92 and 2a of the core 2. This movement corresponds to a rotation of an angle α of the first cam 7 as shown in the figure 13 The hammer 92a then acts on a surface 2a of the heart 2 to return the indicator organ 13 to the predetermined position as shown in the figure 14 There is then slippage at the friction joint, the drive unit 15 still being driven. After a rotation through an angle β, a hammer safety profile 92b comes into contact with a core profile 2c as shown in figures 15 And 16The indicator organ has been returned to a predetermined position and is immobilized in this position while the hammer travels an angular arc δ as shown in the figure 17 Once this angular path has been completed, the hammer no longer interferes with the heart, and the indicator organ is again driven in rotation via the friction linkage from the predetermined position as shown in the diagram. figure 18 The hammer and the first and second cams then continue their rotation along an angular arc γ until the roller 8a returns to the level of the first profile 7a of the first cam as shown in the figure 19 .

[0039] The amplitudes of the angular ranges are of course a function of the relative position of core 2 with respect to hammer 92.

[0040] The device for returning the indicator to its predetermined position is designed to compensate for the dynamic effects generated by the energy release of the spring 91. To do this, the kinematics and geometry of the hammer 92 are studied to, on the one hand, perform the positioning, and, on the other hand, lock the angular position of the core 2 after positioning.

[0041] The cooperation between hammer 92 and core 2 can be likened to a Maltese cross system during the securing phase. In particular, profiles 92b and 2c can be complementary and formed at least partially from a circular arc with a comparable, or even identical, radius of curvature.

[0042] Thanks to the device according to the invention, an energy accumulator provides the interface between the control element and the return element in its predetermined position. Energy produced by the actuation of the control element is transmitted to the energy accumulator and then delivered, notably in a fraction of a second, to the return element in its predetermined position. In other words, the return element is actuated by energy from an accumulator, the energy being previously supplied to the accumulator by the control element. In this way, the user cannot, under any circumstances, directly act on the return element in its predetermined position. Such a design therefore makes the return-to-flight function more reliable and avoids any timing degradation due to the friction clutch mechanism.

[0043] When the return element acts on the indicator of the time-related quantity, the energy for this action comes entirely from the accumulator. This energy was previously stored in the accumulator by a user action, specifically an action by the user on the accumulator via the control element.

[0044] The energy storage system is a well-understood system. It is therefore easy to design and implement.

[0045] The energy stored by the device is that supplied by the user. The sensation at the pusher is therefore crisp and dependent on the energy accumulator. A timepiece equipped with such a reset device does not require an additional mechanism to create an opposing force at the pusher, as is the case with state-of-the-art chronographs.

[0046] The energy transmitted to the hammer enables it to overcome, within all tolerance ranges, the friction torque generated by the friction linkage, which must be sized to keep the indicating organ and the wheel of this moving part together in case of accidental shock.

[0047] The hammer's kinematics are particularly simple. Activating the function causes the hammer to pivot through 360° (Φ+α+β+δ+γ=360°), always in the same direction of rotation. The number of parts required to drive the hammer is therefore reduced to a minimum.

[0048] The kinematics and geometry of the hammer are designed to, firstly, return it to its predetermined position, and secondly, lock the angular position of the indicator once it has been returned to its predetermined position. This device thus eliminates, at minimal cost, the dynamic effects caused by the sudden release of energy, without the need for an additional braking mechanism.

[0049] The user has no control over the hammer's rotation. Therefore, the risks of delayed and partial resets are eliminated.

[0050] The hammer activates the heart in a fraction of a second, i.e., instantaneously. Therefore, there is no risk of degrading chronometric performance due to prolonged friction.

[0051] The device allows for instantaneous resetting and restarting of the seconds hand in a single operation, regardless of any other actions on the watch. Therefore, the accuracy of the timekeeping is not dependent on the user's dexterity.

[0052] This system is independent of any chronograph mechanism. It does not require a rocker clutch and overcomes the drawbacks inherent in known state-of-the-art friction mechanisms.

[0053] A second embodiment of a device 200 for returning an indicator of a time-related quantity to a predetermined position is described below with reference to figures 19 And 20In this second embodiment, elements that are identical, similar, or have the same function as the elements of the first embodiment are identified by reference numerals to which 20 units have been added compared to the reference numerals used for the first embodiment. Thus, for example, the lever referenced as 8 in the figures representing the first embodiment is referenced as 28 in the figures representing the second embodiment. Similarly, for example, the cam is referenced as 2 in the figures representing the first embodiment and as 22 in the figures representing the second embodiment. In this embodiment, the angular range of rotation of the hammer has been reduced for dimensioning reasons. The cam 27 and the hammer 292 are designed to rotate 180° in a single direction of rotation when the function is triggered.The functional surfaces of the cam 27 and the hammer 292 are therefore duplicated. The duplicated surfaces have been referenced using a '. The operation of the second embodiment is entirely similar to that of the first embodiment, in particular the fact that the cam and the hammer move in a single direction of rotation, without reversing the direction of movement during the predetermined return function. One can also imagine a hammer with a rotation angle of 120° or 90°, or more generally 360° / m, with m=1, 2, 3, or 4. This solution would, for example, allow several cores to be driven—n cores in this case—whose centers are distributed on a circle concentric to the axis of the hammer so as to return n indicating elements to n predetermined positions, with n=1, 2, 3, or 4. If n=m, each of the hammer's points can act on one core with each actuation of the hammer.

[0054] Thus, in both embodiments described above, the device comprises the actuating or motion transmission element to the return element via energy from the accumulator. Energy is supplied to the energy accumulator by the user via the control member 4, which returns the device to the user-operated predetermined position, and via the energy transmission element to the energy accumulator, which also triggers the actuating of the return element.

[0055] In the embodiments described above, the indicating element is mechanically linked by friction to the drive unit. However, a clutch system could be used instead of friction. In this case, disengagement would be triggered during the action phase of the return element, that is, during the reset step by the action of the hammer on the core, and then during the locking step.

[0056] It is certainly possible to integrate this device into a chronograph mechanism. Each indication in the chronograph's counting chain—for example, the seconds, minutes, and hours—corresponds to a heart that can be activated by the hammer. Depending on the design, these hearts can be arranged concentrically or distributed so that their centers are located on a circle concentric to the hammer's axis, allowing them to be activated sequentially by the reset hammer over a period of approximately one-tenth of a second, or, in particular, by a single strike of the reset hammer over a period of approximately one-tenth of a second.

Claims

1. Device (100; 200) for resetting to a predetermined position an indicator member (2, 13; 22) indicative of a parameter connected with time, the device comprising a return element (1; 21) for returning the indicator member indicative of the parameter connected with time to the predetermined position, the return element comprising a hammer (92; 292): - collaborating with a cam (2; 22) kinematically linked in terms of rotation to the indicator member, and - mounted to rotate about an axis (1'), the hammer performing a one-way rotational movement as it is actuated, notably a one-way rotational movement of 1 / m of a revolution as it is actuated, with m=1 or 2 or 3 or 4, the resetting device comprising: - an energy accumulator (9), the device being characterized in that: - a transmission element (8, 8a, 7; 28, 27) for transmitting movement from the energy accumulator to the return element, the movement transmission element comprising: - a first cam (7; 27) kinematically linked to the return element, and - a lever (8; 28) collaborating with the first cam (7; 27).

2. Device according to the preceding claim, characterized in that the return element is actuated using energy from the energy accumulator (9).

3. Device according to one of the preceding claims, characterized in that the hammer comprises at least one pane (92a; 292a, 292a') intended to collaborate with the cam (2) and to act on a portion of the profile of said cam so as to cause it to rotate until the indicator member reaches the predetermined position.

4. Device according to one of the preceding claims, characterized in that the hammer comprises at least one securing element (92b; 292b, 292b') intended to collaborate with a portion (2c) of the profile of the cam (2) so as to immobilize this cam and therefore immobilize the indicator member in the predetermined position.

5. Device according to the preceding claim, characterized in that the securing element (92b) and the portion (2c) of the profile of the cam (2) may complement one another and be formed at least partially of arcs of a circle of comparable, or even identical, radius of curvature.

6. Device according to one of the preceding claims, characterized in that overall, the hammer is in the form of a disc having a notch forming a pane (92a) and a cutout (92c) allowing the cam (2) to rotate freely about an axis (2') when the hammer is in a rest position.

7. Device according to one of the preceding claims, characterized in that the cam (2) is a heart-cam.

8. Timepiece movement comprising a device (100; 200) according to one of the preceding claims.

9. Movement according to the preceding claim additionally comprising a second indicator member indicating the same parameter as the first indicator member and permanently connected to a drive mobile.

10. Movement according to Claim 8 or 9, characterized in that the device is a "flyback" device in which resumed drive to the indicator member from the drive mobile (15; 35) following the action of the return element is independent of the position of the control member.

11. Timepiece comprising a timepiece movement according to one of Claims 8 to 10 or a device according to one of Claims 1 to 7.

12. Method for operating a timepiece according to Claim 11 or a timepiece movement according to one of Claims 8 to 10 or a device according to one of Claims 1 and 7, the method involving one-way rotational movement of the hammer, notably a one-way rotational movement of the hammer by 1 / m of a revolution, with m=1 or 2 or 3 or 4.

13. Operating method according to the preceding claim, characterized in that the one-way rotation comprises: - movement of the hammer through a first angle until one pane (92a) of the hammer (92) and the cam (2) make first contact, then - action of the pane (92a) of the hammer (92) on the cam (2) in order to return the indicator member (13), then - immobilization or locking or securing of the angular position of the cam (2), then - end of interference with the cam (2) and continued rotation of the hammer.

14. Operating method according to Claim 12 or 13, characterized in that the one-way rotation is a movement of the hammer from a hammer position of rest to a hammer position of rest via a position in which the hammer is in contact with the cam (2).

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