Mechanical timepiece movement
By designing the control handle and fixing mechanism, the problem of the flexible guided resonator being difficult to start is solved, automatic starting and restarting is achieved, which is suitable for various initial angular positions and enhances the reliability and convenience of starting.
Patent Information
- Application Number
- CN202510453709.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-04-15
- Filing Date
- 2025-04-11
- Publication Date
- 2025-10-21
AI Technical Summary
In existing mechanical watches, the flexible guided resonator is difficult to start, especially when the balance wheel is far from the stem or the movement is heavy. It requires violent shaking of the watch to start, and there is a lack of an effective fixing mechanism.
A watch movement including a control stem, a flexible guided mechanical resonator and a fixing mechanism is designed. Through the cooperation of a rod and an auxiliary rod, the balance wheel can be fixed and started without applying external torque, achieving self-starting.
It enables automatic start-up and restart of the flexible guided resonator, avoiding the need for violent shaking of the meter, and is applicable to various initial angle positions, enhancing the reliability and convenience of start-up.
Smart Images
Figure CN120821176A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a timepiece movement comprising a mechanical resonator and equipped with a mechanism that makes it possible to stop the resonator, in particular when setting the time of the movement, and then restart it. In particular, the invention relates to a mechanical movement incorporating a mechanical oscillator comprising a flexibly guided mechanical resonator and an escapement. The invention also relates to a timepiece, such as a watch, equipped with such a movement. Background Art
[0002] Many mechanical watches are equipped with a stop lever, which is used to stop the watch resonator when setting the time. Conventional stop levers typically consist of a rod that interacts with the balance wheel and is connected to the winding mechanism stem, either directly or via an intermediate component (pullout, lever, or other). While this system works correctly in a large number of movements, its application is less obvious in cases where the balance wheel is quite far from the stem and / or the movement is too heavy to allow direct access.
[0003] Furthermore, in mechanical watches, flexibly guided resonators make it possible to overcome the timing problems associated with the use of a balance spring with a pivot. However, due to their great rigidity, these resonators are difficult to activate, since the torque on the escapement is not always sufficient to overcome the restoring force of the flexible guide when stationary. One drawback associated with this type of resonator is that, unless specific means are provided to arm the resonator to at least a lower limit angle from which it can be maintained by the escapement once released during activation, it is usually necessary to shake the watch vigorously to activate the resonator. Summary of the Invention
[0004] The present invention aims to provide a timepiece movement equipped with a flexibly guided resonator that does not suffer from the aforementioned drawbacks. In particular, it is designed to provide an immobilization mechanism that, on the one hand, makes it possible to stop the flexibly guided mechanical resonator (i.e., to immobilize its balance wheel) and, on the other hand, to wind up the stationary resonator to at least a lower limit angle from which the resonator can be activated without being subjected to accelerations (in particular, by imparting an accelerating movement to the timepiece incorporating the timepiece movement).
[0005] For this purpose, the watch movement comprises:
[0006] a control stem movable along its axis between a winding position, also called the “pushed-in” position, and a time-setting position, also called the “pull-out” position,
[0007] a flexibly guided mechanical resonator comprising a balance wheel capable of oscillating about an oscillation axis between two extreme angular positions, the balance wheel being capable of reaching extreme angular positions on either side of the equilibrium position of the mechanical resonator,
[0008] - a mechanism for securing the mechanical resonator, the mechanism being arranged so as to interrupt the oscillations of the balance wheel when the stem is pulled into the time-setting position, and to hold the balance wheel in a rest position as long as the stem remains in the time-setting position,
[0009] The fixing mechanism comprises: a rod kinematically connected to the stem so that the rod pivots in a first direction about a pivot axis when the stem is pulled from the winding position to the time setting position, and pivots in a second direction when the stem is pushed from the time setting position to the winding position; and an auxiliary rod connected to the rod so that pivoting the rod in the first direction or the second direction causes the auxiliary rod to rotate in a given direction or in the opposite direction respectively about a rotation axis separated from the pivot axis, the auxiliary rod rotation thus being reversibly achieved between a rest position and an active position according to the axial displacement of the stem between the pushed-in position and the pulled-out position, the flexible guided mechanical resonator being arranged so that it can be started from an extreme angular position on either side of the equilibrium position without applying external torque. According to the invention, the balance comprises a part forming a stop for the auxiliary lever, the auxiliary lever being configured such that and its angular path between said rest position and said active position being designed such that, when the lever follows this angular path, it enters an annular zone centered on the axis of oscillation at the level of the stop and radially delimited by this stop, the lever then moves through an extreme position of contact with said stop corresponding to an extreme angular position of the balance on one side of the equilibrium position of this balance, and the lever then remains in this annular zone until it reaches its active position, in which the balance, once in contact with the lever via the stop, is in a rest position situated on the other side of the equilibrium position and beyond the extreme angular position on this other side.
[0010] According to an advantageous embodiment, the control stem and the fixing mechanism are arranged so that, when the user presses the control stem axially with sufficient force to allow it to move from the pulled-out position to the pushed-in position, the portion of the stem situated in said annular area moves in this annular area faster than the stop on the balance wheel, so that the balance wheel is not blocked by the stem when starting from the rest position.
[0011] According to a first specific embodiment, the balance comprises at least two annular segments forming an inertial mass, the lateral surface of one of these two annular segments forming a stop on the balance. According to a second specific embodiment, the balance comprises an annular rim forming a complete circle, or at least two annular segments, this annular rim or one of said annular segments being provided with a portion axially or radially rising from this annular rim or this annular segment and forming the stop. According to a third embodiment, the balance comprises an annular rim forming a complete circle, or an annular segment carried by arms, one of these arms being provided with a protruding portion axially rising and forming the stop.
[0012] The present invention makes it possible to stop the balance wheel and fix it in an angular rest position, called the "rest position," which ensures the automatic starting / restarting of the flexibly guided mechanical resonator. It also makes it possible to start the oscillations of the mechanical oscillator by actuating the control stem (the winding mechanism stem) alone, when this oscillator is initially stopped in its equilibrium / zero position. The present invention provides an effective and reliable solution to the problem of a mechanical oscillator failing to start, a typical problem of watch movements equipped with a flexibly guided resonator. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The invention will be described in more detail hereinafter with reference to the accompanying drawings, given by way of non-limiting examples, in which:
[0014] - Figure 1 and Figure 2 are front and back views of a portion of a timepiece movement according to an embodiment of the present invention, the timepiece movement operating in time indicating mode (winding mechanism stem pushed in, in winding position). Figure 2 In the figure, some components have been deleted in order to show components related to the present invention.
[0015] - Figure 3 and Figure 4 Shown when the winding stem is partially pulled out Figure 1 and Figure 2 Front and back views of the movement shown in.
[0016] - Figure 5 and Figure 6 Shown when the winding mechanism stem is fully pulled out and in the time setting position, with the mechanical resonator stopped Figure 1 and Figure 2 Front and back views of the movement shown in. DETAILED DESCRIPTION
[0017] The present invention will be described by referring to specific embodiments shown in the accompanying drawings without limiting the scope of the invention. Figure 1 and Figure 2 Partial front and back views of a mechanical watch movement 1 according to a preferred embodiment of the present invention Figure 2 Certain components of timepiece movement 1 can be identified by a person skilled in the art, in particular: bridge 2 , winding mechanism / control stem 3 , flexible guided mechanical resonator 4 .
[0018] The mechanical resonator 4 comprises a balance wheel 10 supported by a set of flexible blades 11 arranged so as to allow the balance wheel to oscillate about an oscillation axis 5. The structure of the balance wheel 10 is typical for a flexible guided resonator, comprising two diametrically opposed arms 8 with two annular segments 9 forming an inertial mass, the annular segments 9 being respectively carried at the outer ends of the two arms 8. The oscillation of the balance wheel 10 is maintained by an escapement mechanism comprising an escape wheel 12 and a pallet fork 13 rotatably arranged between two stop pins 14. The escape wheel 13 is usually connected to the barrel (not shown) of the movement by a gear system (not shown). The interaction between the resonator 4 and the pallet fork 13 and between the pallet fork 13 and the escape wheel 12 will also usually release the energy of the barrel in a controlled manner so that the movement 1 can indicate the time by rotating a hand relative to the dial. As Figure 1 The position of the balance 10 shown in corresponds to the equilibrium position of the balance, relative to which the oscillations occur on one side and on the other. Figure 2 It can be seen in FIG that at this time, the escapement fork 13 is centered between the two limit pins 14.
[0019] When the watch is set by pulling winding stem 3 and then rotating it manually, this controlled energy release is interrupted.
[0020] Figure 3 and Figure 4 The movement 1 is shown when the control stem 3 is partially pulled. This stem 3 is connected to a connecting element, called a puller 20. Pulling the stem 3 causes the puller 20 to exert a lever action relative to the bridge 2 about a pivot axis 21. A pin 22 attached to the puller 20 interacts with a lever 23 so that pulling the stem 3 causes this lever 23 to pivot relative to the bridge 2 about a pivot axis 24. More generally, lever 23 is in a kinematic relationship with the stem 3 such that the lever pivots about the pivot axis in a first direction when the stem is pulled from its wound position (also called the "pushed-in position") to the time-setting position (also called the "pull-out position"), and pivots in a second direction when the stem is pushed from the time-setting position to the wound position.
[0021] Lever 23 comprises two blades 23a and 23b, which are generally opposed relative to each other with respect to a pivot axis 24. The first blade 23a includes a rectangular opening 25 in which the pin 22 is disposed; the opposing blade 23b has a toothed section 26 (also known as a rack) at its end. An auxiliary lever 30 is rotatably arranged on bridge 2. This lever 30 is capable of rotating about an axis of rotation 31 separate from the pivot axis 24 of lever 23. Lever 30 is integral with a pinion 32, which, together with the toothed section 26 of lever 23, forms a gear transmission. In other words, the auxiliary lever 30 is kinematically connected to lever 23 such that pivoting the lever in the first or second direction causes the auxiliary lever to rotate in a given direction and in the opposite direction, respectively, about the axis of rotation 31 separate from the pivot axis 24. This rotation of the auxiliary lever 30 is thus reversibly achieved between a rest position and an active position, depending on the axial displacement of the stem 3 between the winding position (pushed in) and the time-setting position (extracted).
[0022] Reference back Figure 1 and Figure 2 , it can be seen that when stem 3 is in the pushed-in position, auxiliary lever 30 is folded back onto lever 23, which corresponds to the normal operating mode of the movement, i.e. the independent time indication mode achieved by the continuous oscillation of balance wheel 10. This folded position of lever 30 is its rest position. It should be noted that Figure 1 and Figure 2 Balance 10 is shown in its equilibrium position, which by definition corresponds to an angle of zero / 0°.
[0023] When stem 3 is pulled, auxiliary lever 30 is deployed in the direction of balance wheel 10 . Figure 3 and Figure 4The moment of contact of lever 30 with one of the annular segments 9 of balance wheel 10, or more generally with the portion of the balance wheel that forms a stop according to the angular orientation of this balance wheel, is shown. In a first particular embodiment (variations of which are shown in the figures), balance wheel 10 comprises at least two annular segments forming an inertial mass, the lateral surface of one of the annular segments forming a stop 36 for the lever on the balance wheel. The position of balance wheel 10 at the moment of contact with the lever depends on its position when the user initiates the actuation of the lever by pulling stem 3, and also on the speed of this actuation. The oscillation of the balance wheel, in particular its maximum amplitude and the configuration of the balance wheel, on the one hand, and the gearing between lever 23 and pinion 32, as well as the configuration and angular path of lever 30, on the other hand, are designed so that the contact between stop 36 and lever 30 occurs in any case during the expansion of lever 30, regardless of the angular position of balance 10 when the lever enters an annular zone radially delimited by stop 36 and centered on the oscillation axis 5 at the level of the stop, i.e., an annular zone with an outer and inner radius determined by the two radial ends of the stop. This annular zone is the circular contact area between the lever and the stop on the balance wheel, i.e., a continuous 360° geometric area delimited by stop 36 at its level, along the oscillation axis, within which contact between stop 36 and lever 10 may occur. Conventionally, the oscillation amplitude of a flexible-guided mechanical resonator in a watch movement is much smaller than that of a conventional balance spring, with the maximum oscillation amplitude of a flexible-vane mechanical resonator typically being less than 60°. In the variant shown in the figures, the maximum oscillation amplitude is approximately 30°. In the context of the invention, the maximum oscillation amplitude of the mechanical resonator is advantageously less than or equal to 45°.When balance 10 comes into contact with rod 30 , the oscillation of the balance is interrupted, meaning that rod 30 stops the oscillation of balance 10 .
[0024] Figure 3 and Figure 4 The balance wheel 10 is shown at -θ M The extreme angular position corresponding to the maximum θ that the balance can have on the negative angle side (clockwise from the zero position of the balance) M It can be seen that in this extreme angular position of the balance, rod 30 has entered the annular area radially delimited by stop 36, exceeding this stop, which means that the maximum θ corresponding to the balance on the negative angular side is greater than the absolute value of the stop. M Thus, if the lever contacts the balance in an extreme angular position on the negative side (e.g. Figure 3 and Figure 4), the rod is pressed against the stop 36. The rod 30 is then arranged in the timepiece movement and configured so that this rod portion remains in said annular area defined by the stop 36 until it has reached its final position (previously called the active position of the rod). In this final / active position of the rod ( Figure 5 and Figure 6 ), when the stop on the balance is pressed against the rod, the balance 10 is in an angular rest position θ on the positive side relative to the zero (0°) position of the balance. R Thus, lever 30 is arranged so as to be able to move the balance wheel angularly in the positive direction (the variant shown), thereby continuing its angular path about its axis of rotation 31 towards its final / active position, and then to maintain the balance wheel in the angular rest position corresponding to the final / active position as long as the control stem is in the time-setting position.
[0025] If from Figure 3 and Figure 4 Starting from the situation shown in FIG, traction is maintained on stem 3, then lever 30 completes its angular path until it reaches its final / active position, as shown in FIG. Figure 5 and Figure 6 As it continues the angular path, the rod pushes the balance 10 in front of it and, in its final position (also called "active position"), it fixes the balance in an angular rest position θ R , the absolute value of the angular rest position is greater than the lower limit angle θ L (also called "limit angular position"), from which the balance wheel 10 can be maintained by the escapement mechanism once it is released at start-up or restart; that is, the limit angular position θ from which the flexible vane mechanical oscillator starts to automatically start L , after having come to rest in its rest position, or, in another case, in its 0° equilibrium position, and then being brought into rest by the lever by actuating the control stem, there is no restoring force other than that of the flexible blade. In other words, lever 30 is configured and its angular path is planned so that, as it follows the angular path between its initial / rest position and its final / active position, it enters the annular zone radially delimited by the balance stop, passes through an angular position in contact with the stop corresponding to an extreme position of the balance on one side of its equilibrium position, and remains within the annular zone until it reaches its final / active position, in which the balance is in a rest position on the other side of the equilibrium position, beyond the extreme angular position on this other side. In this way, as it follows its angular path, the lever moves within the annular zone at an angle relative to the oscillation axis that is greater than the maximum amplitude of the oscillating balance and, therefore, greater than the sum of the values of this maximum amplitude and the angular extremes.
[0026] In summary, when the rod follows the angular path described (in the forward direction), this balance comes into contact with the stop 36 on the balance if it is in an angular position corresponding to the angular position of the rod, regardless of whether this angular position is an extreme angular position of the balance on one side of its zero position / equilibrium position (in the variant shown, this is the extreme angular position on the negative angular side -θ M ) and is located on the other side of the zero position / equilibrium position and exceeds the limit angular position relative to the zero position / equilibrium position (ie, in the shown variant, exceeds the lower limit angle θ L ) of the balance wheel at rest θ R ) (the absolute value of this angular rest position is greater than said limit angular position / said lower limit angle on said other side of the zero position / equilibrium position). In any case, whatever the angular position of the balance wheel along said angular path of the lever, this lever ultimately fixes the balance wheel 10 in said tightened state in said angular rest position, i.e., in a state in which, as soon as the lever 30 is withdrawn from its active position and said annular zone, the balance wheel is enabled to start or restart the oscillation maintained by the escapement, without any external intervention other than actuating the stem 3 by pushing this stem towards its wound position. The only specific measure for the automatic start or restart of the balance wheel (also called "self-start") is to withdraw the lever from the annular zone (the annular contact area between the lever and the stop on the balance wheel) faster than the stop 36 is when the balance wheel 10 is withdrawn from its angular rest position θ R The speed during free movement is high, and the balance 10 starts from its angular rest position (the state when the balance is stopped) with zero initial speed. It should be noted that the terms "automatic" and "self-starting" should be understood as starting or restarting, collectively referred to as "starting", which occurs after the winding mechanism / control stem has been actuated from its time-setting position (pulled-out position) to its winding position (pushed-in position) by the sole force exerted by the flexible vane on the balance; that is, starting from the rest position of the balance provided by the present invention, solely by means of the torque exerted on the balance by the flexible vane.
[0027] To achieve this self-starting function, relative to its swing equilibrium position ( Figure 1 The angular position of the stationary balance wheel, as defined by the position shown in FIG. , must typically exceed half the lift angle of the balance wheel. This lift angle is a typical resonator parameter, and the concept of lift angle is well known to those skilled in the art. In the specific resonator shown in the drawings, the lift angle is approximately 14° (7° on either side of the equilibrium position), and the absolute value of the lower limit angle corresponds to half of this lift angle, or approximately 7°. The rest position of the balance wheel is approximately 10° relative to the equilibrium position (zero position / 0°), which ensures the desired automatic start-up.
[0028] As already mentioned, the rod 30 can stop the balance wheel 10 at any point along its oscillating path. In most cases, after the rod 30 first contacts the stop on the balance wheel, the rod pushes the balance wheel toward its rest position. Preferably, the shape, material, flexibility, etc. of the rod 30 are designed so that during this period after the initial contact, the rod remains in contact with the balance wheel; in other words, the impact between the rod and the balance wheel does not cause the balance wheel to rebound on the rod, but is instead accompanied by the rod 30 toward its rest position. However, embodiments in which, after the initial impact, the impact causes the stop on the rod to rebound, or even rebound several times, are not excluded from the scope of the present invention, provided that, after the initial impact, the balance wheel eventually stops in a given angular rest position and is then held in this rest position by the rod.
[0029] Although the lever 30 holds the balance 10 in the Figure 5 and Figure 6 , but the user can set the time on their watch by turning the control stem 3 in a manner known per se. Then, when the stem 3 is pushed in, the lever 30 withdraws from its active position and returns to its rest position, allowing the balance wheel 10 to oscillate again. As already mentioned, to prevent the lever 30 from disrupting the self-starting, it must be withdrawn sufficiently quickly. The speed at which the lever 30 retracts depends on the pivoting speed of the lever 23 and the gearing between the toothed end 26 of the lever 23 and the pinion 32 integral with the lever. This system is preferably designed so that the rotation speed of the pinion 32, and therefore of the lever 30, far exceeds the pivoting speed of the lever 23, and the lever retracts / retracts faster than the balance wheel during the starting phase. This means that the lever always retracts / retracts sufficiently quickly, even if the user pushes the stem 3 to its wound position (pushed-in position) at a slower speed than usual, and even if this action is unintentional. According to some embodiments, the rotation speed of the lever 30 is at least twice, and preferably at least three times, the pivoting speed of the lever.
[0030] Since the rotation speed of lever 30 significantly exceeds the pivoting speed of lever 23, the angular path of lever 30 is much greater than the corresponding angular path of lever 23, which also enables the lever to interact with balance 10 over a sufficiently long path so that the balance can be stopped from any angular position in an angular position of rest greater than the lower limit for achieving self-starting, as explained above.
[0031] The present invention is designed for use with movements equipped with flexible, guided resonators, as it offers particular advantages for configurations including such resonators. This advantage is particularly due to the aforementioned self-starting feature. In effect, there is no longer any need to shake the watch to start or restart the mechanical oscillator including a flexible blade mechanical resonator. The present invention can also be used with a balance wheel having a full-circular annular rim. In this case, a stopper (e.g., a pin) is provided on the balance wheel, extending radially or axially from the rim; alternatively, it extends axially from one of the balance wheel arms and can, as described above, contact the auxiliary lever 30 when deployed. In a second specific embodiment, the balance wheel comprises a full-circular annular rim provided with a projection rising axially or radially from this annular rim and forming the stopper. In a third specific embodiment, the stopper is formed by a projection rising axially from one of the arms carrying the annular segments, or alternatively, from the annular rim.
[0032] One of the general benefits of the invention is that the fixing mechanism and its two-part system make it easier to reach the balance wheel if it is too far from the stem or if the movement is too heavy to allow direct access. Moreover, it allows functional contact with the balance wheel regardless of its initial angular position. In fact, it is important to be able to actuate the control stem at any time and for the interaction between the fixing mechanism (more generally, the stop and the self-starting mechanism) and the balance wheel to be always effective.
Claims
1. A watch movement, comprising: a control stem (3) movable along its axis between a winding position, also called the “pushed-in” position, and a time-setting position, also called the “pull-out” position, - a flexibly guided mechanical resonator (4) comprising a balance wheel (10) capable of oscillating about an oscillation axis (5) between two extreme angular positions, the balance wheel being able to reach said extreme angular positions on either side of an equilibrium position (0°) of the mechanical resonator, - a mechanism for fixing the mechanical resonator, the mechanism being arranged so as to interrupt the oscillation of the balance wheel when the stem (3) is pulled into the time-setting position and to hold the balance wheel in a rest position as long as the stem remains in the time-setting position, The fixing mechanism comprises: a rod (23) which is kinematically connected to the stem (3) so that the rod pivots in a first direction about a pivot axis (24) when the stem is pulled from its winding position to the time setting position, and pivots in a second direction when the stem is pushed from the time setting position to the winding position; and an auxiliary rod (30) which is connected to the rod (23) so that pivoting the rod in the first direction or the second direction causes the auxiliary rod to rotate in a given direction and in an opposite direction respectively about a rotation axis (31) separated from the pivot axis (24), the auxiliary rod (30) rotating so as to rotate between a rest position and an active position according to the axial displacement of the stem (3) between the pushed-in position and the pulled-out position. The invention also provides a method of reversibly achieving a rotation of the balance wheel between two active positions, the flexible guided mechanical resonator being arranged to be able to be activated from extreme angular positions on either side of the equilibrium position without applying an external torque; the invention also provides a method of reversibly achieving a rotation of the balance wheel between two active positions, the flexible guided mechanical resonator being arranged to be able to be activated from extreme angular positions on either side of the equilibrium position without applying an external torque; the invention also provides a method of reversibly achieving a rotation of the balance wheel between two active positions, the flexible guided mechanical resonator being arranged to be able to be activated from extreme angular positions on either side of the equilibrium position (0°) of the balance wheel ... M ), and the rod then remains in this annular area until it reaches its active position, in which the balance wheel, once in contact with the rod via the stop, takes up the rest position (θ R ), the rest position is located on the other side of the equilibrium position and exceeds the limit angular position (θ L ).
2. The watch movement (1) according to claim 1, characterized in that The auxiliary lever (30) is connected to the lever (23) such that the auxiliary lever can rotate at a speed at least twice as fast as the lever can pivot.
3. The watch movement (1) according to claim 1 or 2, characterized in that: The auxiliary lever (30) is connected to the lever (23) via a gear transmission.
4. Timepiece movement (1) according to any one of the preceding claims, characterized in that The control stem and the fixing mechanism are arranged so that, when a user presses the control stem axially with sufficient force to allow it to move from the pulled-out position to the pushed-in position, the portion of the stem situated in the annular area moves in this annular area faster than the stop on the balance wheel, so that the balance wheel is not blocked by the stem when starting from the rest position.
5. Timepiece movement (1) according to any one of the preceding claims, characterized in that The auxiliary rod (30) is connected to the rod (23) so that the angular path described by the rod (30) between its rest position and its active position is greater than the corresponding angular path described by the rod (23).
6. The watch movement (1) according to claim 5, characterized in that The angular path of the rod is at least twice the angular path of the rod.
7. Timepiece movement according to any one of the preceding claims, characterized in that The balance (10) comprises at least two annular segments (9) forming an inertial mass, the lateral surface of one of the two annular segments forming a stop on the balance.
8. The timepiece movement according to any one of claims 1 to 6, characterized in that The balance wheel comprises an annular rim forming a complete circle, or at least two annular segments, one of the annular rim or the annular segments being provided with a portion rising axially or radially from this annular rim or this annular segment and forming the stop.
9. The timepiece movement according to any one of claims 1 to 6, characterized in that The balance wheel comprises an annular rim forming a complete circle, or an annular segment carried by arms, one of these arms being provided with a projection axially raised and forming the stop.
10. A watch, characterized in that It comprises a timepiece movement according to any one of the preceding claims.