CH720479A1 - Vertical clutch device, chronograph mechanism, watch movement and timepiece - Google Patents

Abstract

The invention relates to a vertical clutch device comprising: – a driving mobile (10) comprising a clutch plate (16), – a driven mobile (32) comprising a clutch disc (36) movable between an engaged position, in which it is positioned against the clutch plate (16), and a disengaged position, in which it is located at a distance from the clutch plate (16), – a disengaging member, movable between a rest position, in which it allows the clutch disc (36) to occupy its engaged position, and an active position, in which it acts on the clutch disc (36) to maintain it in its disengaged position, the device further comprising a brake (52), integral with the disengaging member, and carrying a bearing surface (56), arranged to be moved in contact with a plate (40) of the driven mobile (32) when the disengaging member is moved to its active position. The invention also relates to a chronograph mechanism comprising such a device, a watch movement comprising such a device or such a chronograph mechanism, and a timepiece comprising such a movement.

Description

Technical field

[0001] The present invention relates to a vertical clutch device for a watch movement, comprising: – a driving wheel set intended to have a permanent kinematic connection with a drive wheel set of the watch movement and comprising a clutch plate, – a driven wheel set, coaxial with the driving wheel set, comprising a driven shaft and a clutch disc arranged on the driven shaft and being capable of moving along the length of the latter between an engaged position, in which it is rotationally integral with the driven shaft while being positioned in abutment against the clutch plate, such that it is also rotationally integral with the clutch plate, and a disengaged position, in which it is located at a distance from the clutch plate, – a disengaging member, movable between a rest position, in which it allows the clutch disc to occupy its engaged position, and an active position, in which it acts on the clutch disc to maintain it in its disengaged position.

[0002] The present invention also relates to a chronograph mechanism and a watch movement comprising such a vertical clutch device, as well as a timepiece comprising such a watch movement.

State of the art

[0003] Clutch devices are found in connection with various types of mechanisms in watch movements, most commonly with chronograph mechanisms.

[0004] Examples of common chronograph mechanism architectures are presented in the work entitled "Théorie d'horlogerie" by C.-A. Reymondin et al., published by the Fédération des Ecoles Techniques (Switzerland), ISBN 2-940025-10-X, in particular on pages 232 to 244.

[0005] These chronograph mechanisms have a large number of moving components interacting with each other and their development is very complex.

[0006] In particular, these mechanisms generally comprise: – a clutch device for ensuring the establishment of a kinematic connection between the finishing gear of the corresponding watch movement and a chronograph counter, – a blocker or brake for ensuring the locking of the chronograph counter when it is not 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 a column wheel for controlling the state of the various devices which have just been listed.

[0007] It is often provided that these different devices interact to ensure perfect synchronization of their respective actions on the chronograph counter.

[0008] Thus, for example, it is apparent from pages 237 and 242 of the aforementioned work that, in the context of the implementation of the mechanisms presented, with horizontal clutch devices, the stop function involves a movement of the blocker which is placed in contact with the chronograph counter to stop its rotation, while the clutch device assumes its disengaged state. The reset function involves the cooperation of a reset hammer with a heart secured to the chronograph counter, the movement of the hammer causing the neutralization of the blocker which is raised.

[0009] Indeed, it proves necessary to prevent rotation of the chronograph counter in all operating phases in which it is not voluntarily driven by the finishing gear, via the clutch device, or by the zero-reset device.

[0010] The operating mode of horizontal type clutch devices involves a risk of the chronograph seconds hand jumping, particularly during the clutch operation. Thus, other types of clutch devices have already been developed to address this problem, particularly vertical clutch devices.

[0011] Thus, for example, patent EP2015145B1 describes a chronograph mechanism comprising such a vertical clutch device. The latter comprises a driven wheel movable in translation along a clutch axis, between an engaged position and a disengaged position. This driven wheel is in permanent engagement with a chronograph wheel set, whatever its axial position, while it is brought into contact with a seconds wheel in its engaged position, and is separated from it in its disengaged position. A pair of clamps controlled by a column wheel is arranged to act, in the closed configuration, on the axial position of the driven wheel and push it back towards its disengaged position against the action of a spring intended to keep it pressed against the seconds wheel. In the disengaged position, a shoulder of the clutch shaft is positioned in abutment against a bearing of this same shaft, giving rise to friction which prevents the driven wheel, and therefore the chronograph wheel set, from rotating. Thus, this document specifies that, thanks to such a construction, it is not necessary to provide for the implementation of a specific brake or blocker to ensure the immobilization of the chronograph wheel set when it is not driven by the seconds wheel set.

[0012] However, in this case, it is found that the friction between the clutch shaft and its bearing risks leading to premature wear of the clutch shaft, or even of its bearing. Furthermore, the surfaces in contact to produce the friction are of small dimensions, and the materials generally used for the bearings are intended precisely to reduce the friction with the shaft, which here leads to a situation which is ultimately unsatisfactory.

[0013] Thus, it still seems desirable to find an alternative approach for the realization of a vertical clutch device of simplified construction, and which would present a robust and reliable operation.

Disclosure of the invention

[0014] A main object of the present invention is to propose a vertical clutch device, in particular for a chronograph mechanism, of alternative construction to the known constructions of the prior art, having in particular a relative simplicity of construction and assembly, while offering a high level of operational reliability.

[0015] For this purpose, the present invention relates more particularly to a vertical clutch device of the type mentioned above, characterized in that it further comprises a brake, movable between an inactive position, in which it is located at a distance from the driven mobile, and a locking position, in which it acts on a board of the driven mobile to limit the rotation of the latter by friction. In addition, according to the present invention, this brake comprises an arm, integral with the disengaging member, having an elastically deformable portion carrying a bearing surface, arranged to be moved in contact with the board of the driven mobile and define the locking position of the brake when the disengaging member is moved to its active position.

[0016] Thanks to these characteristics, it is possible to produce a vertical clutch device having reliable and robust operation, in particular by ensuring good retention of the driven mobile when it is disengaged from the driving mobile thanks to the implementation of a brake, without making its manufacture and assembly particularly complex. Indeed, if the construction described in patent EP2015145B1 makes it possible to do without a brake, its development remains delicate due to the nature of the contacts involved to give rise to friction to ensure the locking of the driven wheel. In addition, this friction is the result of contact between two surfaces of reduced diameters. In the case of the present invention, the installation of a brake directly on the disengaging member greatly simplifies its adjustment aimed at ensuring its perfect synchronization with the disengaging member, compared to devices in which the brake is controlled by an additional control member. Furthermore, the implementation of the brake according to the present invention offers greater flexibility in the choice of materials of the components giving rise to friction, as well as in the choice of the surface condition of the contact surfaces involved, the latter also being of larger diameter than in the case of the aforementioned patent, guaranteeing improved efficiency when locking the driven mobile.

[0017] More precisely and preferably, it can be provided that the disengaging member comprises two clamps arranged to cooperate with the clutch disc in substantially diametrically opposite regions of the latter to move it in the direction of the driven shaft, the brake being carried by one of the two clamps.

[0018] Furthermore, it is advantageous to provide that one of the two clamps has an actuating surface intended to cooperate with a control member of the watch movement capable of having two different states so as to be able to move it by changing state, a first state being associated with the rest position of the disengaging member and a second state being associated with the active position of the disengaging member, and that the two clamps have a kinematic connection between them arranged to synchronize their movements.

[0019] In this case, it is also possible to provide that the device further comprises an elastic return member arranged to cooperate with one of the two clamps and tend to move it in a direction corresponding to the active position of the disengagement member.

[0020] Generally, the present invention also relates to a chronograph mechanism comprising a vertical clutch device according to the above characteristics.

[0021] According to an advantageous embodiment, it can be provided that the driven mobile also comprises a seconds board, arranged to ensure the driving of a minute counter of a measured time, as well as a zero-reset cam, intended to be actuated by a zero-reset hammer to position the driven mobile according to a predefined orientation corresponding to a zero measured time.

[0022] When the clutch device comprises a pair of clamps associated with a control member capable of occupying two different states to define the rest and active positions of the disengagement member, it may also be provided that the latter and the reset hammer are arranged to cooperate with each other, in such a way that a movement of the reset hammer in the direction of the cam, aimed at carrying out a reset, causes a movement of the disengagement member from its active position to its rest position.

[0023] The present invention also relates to a watch movement comprising a clutch device meeting the characteristics mentioned above, whether it is integrated into a chronograph mechanism meeting the characteristics which have just been set out or into another watch mechanism, as well as a timepiece comprising such a watch movement.

Brief description of the drawings

[0024] Other features and advantages of the present invention will become more apparent upon reading the detailed description of a preferred embodiment which follows, made with reference to the appended drawings given by way of non-limiting example and in which: – Figure 1 shows a simplified cross-sectional view of a portion of a chronograph mechanism incorporating a vertical clutch device according to a preferred embodiment of the present invention, illustrated in its engaged state; – Figures 2a and 2b show simplified perspective and cross-sectional views of the same components as those illustrated in Figure 1, respectively in the engaged state and in the disengaged state of the vertical clutch device, and – Figures 3 and 4 show simplified perspective views, respectively on the bridge side and on the dial side, of a larger portion of the chronograph mechanism of Figure 1.

Method(s) of carrying out the invention

[0025] Figure 1 shows a simplified cross-sectional view of a part of a chronograph mechanism 1 incorporating a vertical clutch device 2 according to a preferred embodiment of the present invention.

[0026] More precisely, FIG. 1 represents a view of the clutch device 2 while it is directly associated with a chronograph counter, that is to say a seconds counter of a measured time, itself intended to cooperate with a transmission wheel set 4 arranged in mesh with a minutes counter of a measured time (numerical reference 6 in FIGS. 3 and 4).

[0027] The clutch device 2 comprises a driving mobile 10 comprising here a central body 12, to which a drive wheel 14 is made integral. The drive wheel 14 is intended to be arranged in permanent connection with a drive mobile of the corresponding watch movement, typically a seconds wheel (not shown), to perform a rotation on itself in one minute. Of course, the person skilled in the art will not encounter any particular difficulty in implementing a suitable gear ratio if the drive mobile is different from a seconds wheel, or if the clutch device 2 is associated with a mobile other than a chronograph counter.

[0028] The driving mobile 10 also comprises a clutch plate 16, here made in one piece with the central body 12 but which could just as well be made as an added part.

[0029] Finally, the driving mobile 10 also comprises an assembly tube 18 on which the central body 12 is mounted, these two elements preferably being integral with each other.

[0030] In the case of the chronograph mechanism 1 as illustrated, the driving wheel set 10 is mounted to rotate freely on a shaft 20 of the chronograph counter, so as to be permanently rotated by the driving wheel set of the corresponding watch movement.

[0031] The shaft 20 is preferably intended to be rotatably mounted between two bearings 22, 24 on a frame element of the corresponding watch movement. The shaft 20 comprises two portions 26 of diameter greater than its average diameter, complementary to the internal diameter of the tube 18, to ensure good rotational guidance of the latter while limiting the contact surface, therefore the friction, between them.

[0032] Furthermore, the shaft 20 has a ring 28, advantageously but not necessarily made in one piece, adjacent to one of the portions 26, to define an axial stop both for a possible relative movement between the tube 18 and the shaft 20, and for a possible axial movement between the shaft 20 and the bearing 22, i.e. with reference to the frame of the watch movement.

[0033] According to the illustrated embodiment, optionally, the end 30 of the shaft 20 located on the dial side is shaped to allow the driving in of a display hand (not shown).

[0034] The clutch device 2 also comprises a driven mobile 32, coaxial with the driving mobile 10 since it is integral with the shaft 20, the latter thus playing the role of driven shaft.

[0035] The driven mobile 32 comprises a central body 34, extending substantially from the tube 18 to the vicinity of the bearing 24 located on the bridge side, and having a plurality of shoulders defining positioning stops for various members which will be described below.

[0036] The driven mobile 32 carries a clutch disc 36 adjacent to the clutch plate 16 of the driving mobile 10. The clutch disc 36 is mounted freely in translation on the central body 34, while being integral with the latter in rotation.

[0037] As a preferred but non-limiting example of embodiment, the central body 34 also carries a spring washer 38, the washer portion of which is rotationally integral with the central body 34 and the spring portion of which is rotationally integral with the clutch disc 36, while exerting a force on the latter tending to push it back towards the clutch plate 16 of the driving mobile 10, in an engaged position, as illustrated in FIG. 1 corresponding to the engaged state of the clutch device 2. In the configuration of FIG. 1, the clutch disc 36 is arranged to bear against the clutch plate 16 of the driving mobile 10 and, consequently, the clutch disc 36 and the driven mobile 32 are rotated by the driving mobile 10.

[0038] The central body 34 also carries a locking board 40 adjacent to the spring washer 38 then a chronograph seconds board 42 and a heart-shaped cam 44 for resetting the chronograph counter, all integral in rotation with the central body 34 and driven in rotation from the movements of the driving mobile 10 in the configuration of FIG. 1.

[0039] The clutch device 2 further comprises a disengaging member intended to cooperate with the clutch disc 36 to move it away from the clutch plate 16 of the driving mobile 10, and place the clutch device 2 in its disengaged state. In this disengaged state, the connection between the driving mobile 10 and the driven mobile 32 is interrupted and the latter is therefore no longer rotated at the rate of the drive mobile of the watch movement.

[0040] The clutch release member comprises a pair of clamps 46, 48 arranged to act in a synchronized manner on substantially diametrically opposed regions of the clutch disc 36 and move it away from the clutch plate 16, opposing the action of the spring washer 38. Thus, the clamps 46, 48 are movable in a substantially radial direction with reference to the shaft 20, in any case substantially perpendicular, between a rest position of the clutch release member and an active position, and have inclined attack surfaces 50 facing the periphery of the clutch disc, itself being chamfered to cooperate with the attack surfaces 50 smoothly.

[0041] The mode of cooperation of the clamps 46, 48 with the clutch disc 36 emerges more clearly from the cross-sectional and perspective views of FIGS. 2a and 2b, which show the same components as those illustrated in FIG. 1, respectively in the engaged state and in the disengaged state of the vertical clutch device 2.

[0042] It is indeed noted during a comparative examination of FIGS. 2a and 2b that, when the attack surfaces 50 continue to move in the direction of the shaft 20, after having contacted the chamfered part of the clutch disc 36, the clamps 46, 48 exert a force on the latter tending to push it axially towards the bridge side of the corresponding watch movement, and consequently tending to move it away from the clutch plate 16 to interrupt the connection between the driving 10 and driven 32 mobiles.

[0043] The clutch device 2 is then in its disengaged state, as illustrated in FIG. 2b, where the clutch disc 36 is held in a disengaged position, located near the spring washer 38, by the clamps 46, 48.

[0044] It is also more clearly seen from the views of FIGS. 2a and 2b that one of the clamps, 48, also carries a brake 52 arranged to cooperate with the board 40 for locking the driven mobile 32. Due to its location, this brake 52 is capable of exhibiting movements similar to those of the clamp 48, i.e. in a substantially radial direction with reference to the shaft 20, in any case substantially perpendicular, between an inactive position and a locking position.

[0045] The brake 52 here comprises an arm 54 having an elastically deformable portion and carrying a support surface 56 arranged opposite the board 40 for locking the driven mobile 32.

[0046] In the locking position, illustrated in FIG. 2b, i.e. in the disengaged state of the clutch device 2 and in the locking position of the brake 52, it appears that the support surface 56 is positioned in contact with the locking board 40 of the driven mobile 32, preventing the latter from rotating on itself by friction.

[0047] As mentioned above, this structure of the surfaces involved in giving rise to friction, and therefore to locking the driven mobile 32, in addition to their large diameters, makes it possible to choose optimized materials and surface conditions. As a non-limiting example, the brake 52 may be made of a material taken from the group comprising: steels, nickel alloys, copper alloys (brass, copper-beryllium, etc.) or light alloys (aluminum, titanium, etc.). Similarly, the locking board 40 may advantageously be made of a material taken from the group comprising: steels, copper alloys (brass, copper-beryllium, etc.), light alloys (aluminum, titanium, etc.), ceramics, metal-ceramic composites or composites with a thermoplastic or thermosetting organic matrix and fiber or particle type reinforcement.

[0048] Figures 3 and 4 show simplified perspective views, respectively on the bridge side and on the dial side, of a larger part of the chronograph mechanism 1 of Figure 1, according to a preferred embodiment of the present invention.

[0049] It is apparent from Figures 3 and 4 that, as a non-limiting preference, the brake 52 can be made integral with the clamp 48 by means of a screw 60 and two pins 62. Alternatively, it would also be possible to provide for the use of an eccentric and a single pin to allow adjustment of the relative angle between the brake 52 and the clamp 48.

[0050] It may advantageously be provided that one of the clamps 46, 48, here the clamp 46, comprises a beak 64, defining an actuation surface, arranged to cooperate with a control member 66, here having the shape of a column wheel by way of non-limiting illustration. The clamps 46, 48 may have a kinematic connection, for example a gear 68, to ensure their synchronized operation. An elastic return member (not illustrated) is then arranged to exert a force on one of the clamps 46, 48 such that the beak 64 is held by default in abutment against the column wheel. When the beak 64 is located between two columns of the column wheel, the clamps 46, 48 move away from each other, as illustrated in FIGS. 3 and 4, the clutch device 2 being in its engaged state. When the beak 64 is located opposite a column of the column wheel, it is raised, which causes a relative approach of the clamps 46, 48, which then act on the clutch disc 36 to place the clutch device 2 in its disengaged state.

[0051] The chronograph mechanism 1 comprises a START/STOP control lever 70, arranged to pivot on a frame element in response to a suitable action by a user giving rise to pressure exerted on an actuating pin 72 that it carries. Each actuation of the control lever 70 causes a rotation of one step of the column wheel, due to the action of a pawl 74 carried by the control lever 70 on its teeth. A return spring 76 is here directly integrated into the control lever 70 to ensure its return to the rest position.

[0052] It is also apparent from FIGS. 3 and 4 that the chronograph seconds board 42 comprises an elastic finger 78 arranged to advance the transmission wheel set 4 by one step for each complete revolution of the driven wheel set 32, to advance the minute counter of a measured time 6 by one step. The latter also comprises a shaft 80 extending on the dial side to receive a chronograph minute display hand, as well as a heart-shaped cam 82 for resetting to zero.

[0053] The chronograph mechanism 1 also includes a zero-reset hammer 84, rotatably mounted on a frame element, and carrying two blades intended to cooperate respectively with the chronograph counter and with the chronograph minute counter.

[0054] As a non-limiting illustration, the chronograph mechanism 1 is of the “flyback” type, that is to say that the resetting of its counters can be carried out without their prior stopping, the release of the reset control simultaneously causing the release of the counters to start a new measurement. Thus, a return spring (not illustrated) is typically provided to hold the hammer 84 in the high position (that is to say at a distance from the heart-shaped cams 44, 82).

[0055] A reset lever 86 rotatably arranged on a frame element carries a pin 88 arranged to drop the hammer 84 (so that its blades act on the heart-shaped cams 44, 82), in response to an adapted action by the user. More precisely, the reset lever 86 has an actuating surface 90 intended to receive pressure following the action of the user to tend to pivot the reset lever 86 in the counterclockwise rotation direction in the view of FIG. 3. The reset lever 86 comprises an elastic notch 92 intended to cooperate with a pin (not visible) fixed with reference to the frame, such that the reset lever 86 is actuated only from a predefined threshold of pressure applied to its actuating surface 90, and that it then pivots suddenly to actuate the hammer 84.

[0056] Furthermore, it is more particularly apparent from FIG. 4 that the reset lever 86 carries an additional pin 94 arranged to act on the clamp 46, when the reset lever 86 is actuated, and to move the disengaging member from its rest position to its active position. Thus, when a reset is carried out during the measurement of a time, i.e. in the engaged state of the clutch device 2, the reset lever 86 acts on the latter to move it from its engaged state to its disengaged state immediately before the action of the hammer 84 on the heart-shaped cams 44, 82, in order to prevent the rotation of the chronograph counter from being transmitted to the driving wheel set 10 during this operation.

[0057] When the reset lever 86 is released, it returns to its default rest position, either under the effect of the action of a specific return spring, or under the effect of the action of the return spring of the hammer 84, the latter then acting on the pin 88. The clamp 46 is released at the same time, which allows the disengagement member to return to its engaged position and to start a new time measurement.

[0058] Of course, the person skilled in the art will not encounter any particular difficulty in integrating the vertical clutch device 2 which has just been described into a chronograph mechanism of different construction, for example which would not have a flyback function and which would possibly be of the single-pushbutton type (in particular with a three-stroke column wheel), without however departing from the scope of the invention as defined by the appended claims.

[0059] From the above description, it is understood how it is possible to produce a vertical clutch device of simple construction and having great operational reliability. It also emerges how such a clutch device can advantageously be integrated into a chronograph mechanism, possibly of the flyback type, for a watch movement having a simplified construction, in particular thanks to the implementation of a brake whose actuation is greatly simplified compared to previous solutions.

[0060] The foregoing description seeks to describe a particular embodiment by way of non-limiting illustration and the invention is not limited to the implementation of certain particular features which have just been described, such as for example the architecture of the START/STOP and RESET (reset to zero) controls, the fact that certain elastic members are made in one piece with particular components of the mechanism, or the fact that a single brake has been described and illustrated, since it is possible to provide as an alternative that each clamp carries a brake. Similarly, the vertical clutch device which has just been described could be integrated into a watch mechanism other than a chronograph mechanism without departing from the scope of the invention as defined by the set of claims.

Claims (10)

1. Vertical clutch device (2), for a watch movement, comprising: – a driving mobile (10) intended to have a permanent kinematic connection with a drive mobile of the watch movement and comprising a clutch plate (16), – a driven mobile (32), coaxial with said driving mobile (10), comprising a driven shaft (20) and a clutch disc (36) arranged on said driven shaft (20) and being capable of moving along the length of the latter between an engaged position, in which it is rotationally integral with said driven shaft (20) while being positioned in abutment against said clutch plate (16), such that it is also rotationally integral with said clutch plate (16), and a disengaged position, in which it is located at a distance from said clutch plate (16), – a disengaging member, movable between a rest position, in which it allows said clutch disc (36) to occupy its engaged position, and an active position, in which it acts on said clutch disc (36) to maintain it in its disengaged position, the device being characterized in that it further comprises a brake (52), movable between an inactive position, in which it is located at a distance from said driven mobile (32), and a locking position, in which it acts on a plate (40) of said driven mobile (32) to limit the rotation of the latter by friction, and in that said brake (52) comprises an arm (54), integral with said disengaging member, having an elastically deformable portion carrying a bearing surface (56), arranged to be moved in contact with said plate (40) of said driven mobile (32) and to define the locking position of said brake (52) when said disengaging member is moved to its active position. 2. Device (2) according to claim 1, characterized in that said disengaging member comprises two clamps (46, 48) arranged to cooperate with said clutch disc (36) in substantially diametrically opposite regions of the latter to move it in the direction of said driven shaft (20), said brake (52) being carried by one of said two clamps (46, 48). 3. Device (2) according to claim 2, characterized in that one of said two clamps (46, 48) has an actuating surface intended to cooperate with a control member (66) of the watch movement capable of having two different states so as to be able to move it by changing state, a first state being associated with the rest position of said disengaging member and a second state being associated with the active position of said disengaging member, and in that said two clamps (46, 48) have a kinematic connection between them arranged to synchronize their movements. 4. Device (2) according to claim 3, characterized in that it further comprises an elastic return member arranged to cooperate with one of said two clamps (46, 48) and tend to move it in a direction corresponding to the active position of said disengaging member. 5. Chronograph mechanism (1) for a watch movement comprising a vertical clutch device (2) according to one of claims 1 to 4, in which said driven mobile (32) is associated with a seconds counter of a measured time. 6. Mechanism (1) according to claim 5, characterized in that said driven mobile (32) also comprises a seconds board (42), arranged to ensure the driving of a minute counter of a measured time (6), as well as a zero-reset cam (44), intended to be actuated by a zero-reset hammer (84) to position said driven mobile (32) in a predefined orientation corresponding to a zero measured time. 7. Mechanism (1) according to claim 6, comprising a vertical clutch device (2) according to claim 4 as well as a control member (66) capable of having at least two different states so as to be able to move one of said two clamps (46, 48) with which it cooperates, by changing state, a first state being associated with the rest position of said disengaging member and a second state being associated with the active position of said disengaging member, characterized in that said disengaging member and said reset hammer (84) are arranged to cooperate with each other, in such a way that a movement of said reset hammer (84) in the direction of said cam (44), aimed at performing a reset, causes a movement of said disengaging member from its active position to its rest position. 8. Clock movement comprising a vertical clutch device (2) according to one of claims 1 to 4. 9. Watch movement comprising a chronograph mechanism (1) according to one of claims 5 to 7. 10. Timepiece comprising a watch movement according to claim 8 or 9.