EP2497095A1

EP2497095A1 - Setting member for a wristwatch, and timepiece comprising such a setting member

Info

Publication number: EP2497095A1
Application number: EP10773314A
Authority: EP
Inventors: Bertrand Pichon
Original assignee: LVMH Swiss Manufactures SA
Current assignee: LVMH Swiss Manufactures SA
Priority date: 2009-11-02
Filing date: 2010-11-02
Publication date: 2012-09-12
Also published as: CH702188B1; CH702188A1; WO2011051498A1

Abstract

Magnetic setting member for a wristwatch movement, comprising: a balance (1); permanent magnets (2, 10) for bringing said balance into at least one rest position; and an escapement (5, 6) for transmitting pulses to the balance in order to move the balance (1) away from the rest position; at least one of said permanent magnets being formed from a non-sintered crystalline material, for example based on platinum and cobalt.

Description

A regulating organ for a wristwatch, and a timepiece comprising such a regulating organ.

The present invention relates to a regulating organ for a wristwatch, and a timepiece for a wristwatch provided with such a movement.

The usual mechanical watches comprise an energy accumulator constituted by a barrel, a kinematic chain, or a train, driving needles, a regulating organ determining the running of the watch, and an escapement for transmitting the oscillations of the regulating organ. at the wheel. The present invention relates in particular to the regulating organ.

The regulating organs of conventional mechanical watches comprise most often a rocker mounted on a rotating axis and a return member exerting a torque on the beam to bring it back to a rest position. The escapement maintains oscillations of the balance around the rest position. The return member generally comprises a spring, the spiral, which transmits a restoring torque to the balance beam through the ferrule.

The oscillator formed by the sprung-balance pair offers remarkable properties for the measurement of time. However, it has the disadvantage of being sensitive to gravity, which tends to deform the spiral differently depending on the inclination of the watch. Moreover, the manufacture of spiral is delicate, and these organs are traditionally difficult to obtain. Electric watches are also known whose running is regulated by an electromechanical oscillator comprising coils and magnets. For example, US4266291 discloses an oscillating mechanism for horological application based on permanent magnets and requiring a power source to energize a stator with a pulsed current. GB1 175550 discloses a resonator comprising an H part provided with of oscillating magnets in a magnetic field created by coils or electrostatic elements. The oscillation frequency is determined by the geometry of the resonator.

With respect to these documents, an object of the present invention is in particular to propose a regulating organ which can also

operate in a timepiece entirely mechanical and without battery or other source of power.

On the other hand, CH615314 describes a regulating member with a balance and a conventional spiral spring; the regularity of the oscillations is improved by means of a magnet mounted on a vibrating tongue and vibrating in the magnetic field of a fixed magnet. Similarly, US2003 / 0137901 discloses a mechanical watch comprising magnets for detecting or correcting the position of the balance; the frequency of oscillations of the pendulum is, however, determined by an ordinary spiral. EP1 122619 describes different embodiments of a mechanical watch whose balance is provided with magnets generating a magnetic field in fixed induction coils linked to the movement. The intensity of the current in the coils makes it possible to control the amplitude of oscillation and therefore the running of the watch. It is also suggested to correct this step in case of irregular oscillations. The movements of the balance are however stabilized by a spiral, and not by magnets.

Various documents also describe a magnetic escapement associated with a conventional regulating organ. For example, US3183426 discloses a magnetic escapement for watch movement. This device uses magnets arranged on the pendulum. However, it is not suggested to remove or replace the hairspring.

In the same way, CH274901 describes different variants of mechanical escapements associated with a conventional spiral spring regulating member. These different solutions therefore require an additional magnetic system in addition to the spiral spring. They therefore have all the disadvantages of spiral springs, adding further complexity. An object of the present invention with respect to these various solutions is therefore to remove the spiral spring.

US387721 5 describes a member which comprises a tuning fork whose vibrations are transmitted to the balance by magnetic coupling.

GB1 142676 discloses another mechanical and magnetic oscillator with a tuning fork. CH235718 discloses a regulating organ for a watch comprising an oscillating flexible rod whose end is provided with a magnet vibrating in the magnetic field of a fixed magnetic pole.

These solutions make it possible to suppress the spiral spring, but replace it with a tuning fork whose elastic deformations determine the running of the watch. The manufacture of a precise tuning fork poses similar or even more complex problems than the manufacture of a high precision hairspring.

US 3621424 discloses a pendulum oscillating in a magnetic field caused by a single magnet connected to the exhaust. The magnet serves both the exhaust and bring the pendulum back to its equilibrium position. The pendulum, however, must be subjected to the gravitational force and can only operate in a vertical position, that is to say in a clock.

US4308605 discloses a regulating member for a timepiece provided with a vertical axis balance. Magnets make it possible to compensate for the gravitational force to compensate for the pressure differences on the two bearings and to limit the bending of the balance wheel shaft due to its own weight. The oscillations are controlled by a conventional spiral.

US5638340 relates to a table clock with a pendulum oscillating in levitation in a magnetic field, and which in a variant determines the running of the watch. The oscillating member is thus totally decoupled from the drive train of the needles. This device however requires a source of electrical energy to produce the levitation magnetic field and for the sensors

Optoelectronic position control of the pendulum. The mechanism is not suitable for a wristwatch.

GB615139 evokes a vertical gravitational pendulum clock. The end of the pendulum oscillates in a circular path controlled by magnets, and thus causes the movement of the watch.

With respect to these last four documents, an object of the present invention is in particular to propose a regulating organ adapted to a wristwatch, and whose operation and running are practically independent of the gravity and the orientation of the organ. adjusting relative to the vertical.

GB644948 discloses a galvanometer with a mass of inertia which is provided with two movable magnets. A permanent fixed magnet generates a magnetic field for bringing the balance back into its equilibrium position. The oscillations are maintained by a conventional anchor escapement. This solution is only sketched schematically; magnets of relatively large size are however necessary. These magnets generate a magnetic field around the regulating organ, which is likely to disrupt the operation of the device and attract parts or organs nearby.

Patent application WO2006 / 045824 in the name of the

Applicant, whose content is incorporated herein by reference, proposes to replace the spiral spring of the prior art with at least one permanent magnet which pushes the balance to its rest position against the pulses of the exhaust. The magnetic force of the magnet is independent of its orientation in space, and thus avoids the isochrononism disturbances that characterize the spiral springs when they deform under the action of gravity. The solution described in the patent application WO2006 / 045824 employs stationary magnets relatively remote from the movable magnets on the balance, in order to push these mobile magnets to the rest position at a distance. It is therefore necessary to use strong and therefore bulky magnets to generate a sufficient repulsion force. It has however been observed during tests and simulations in the context of the invention that a large part of the magnetic flux created by these magnets does not contribute to the progress of the balance, and escapes to other components of the invention. movement which it disrupts the operation. Most of the above documents use permanent magnets in conventional materials chosen for their

significant remanence, eg neodymium etc. Conventional magnets, however, are generally formed of sintered materials that are difficult to machine accurately. It is therefore difficult to produce magnets of dimension and volume perfectly reproducible, and difficult to mount and position precisely in a device.

An object of the present invention is therefore to provide a regulating member whose isochronism is improved over the regulating members of the prior art. In particular, another object of the present invention is to provide a dimensioned magnetic regulating member which can, if necessary, also be integrated in a small mechanical wristwatch movement, or even in an additional module superimposed over a movement of existing base. Another aim is to propose a regulating organ that is less sensitive to shocks and accelerations than the regulating members of the prior art, in particular a regulating organ whose period is less disturbed by external shocks than known regulating devices.

Another aim is to propose a regulating organ which is not very sensitive to temperature variations. Another object of the present invention is also to propose a mechanical timepiece based on a magnetic regulating member and without a spiral spring.

It is important for most watch brands to regularly offer technical innovations; this is a real challenge given the amount of published material concerning mechanical watches. An object of the present invention is therefore also to propose a regulating member for a wristwatch which is new and different from the regulating members of the prior art. According to the invention, these objects are achieved by means of a regulating member having the features of the main claim, preferred variants being indicated in the claims.

dependent.

These goals are achieved in particular by means of a regulating member for a wristwatch, comprising:

a pendulum;

permanent magnets for bringing said balance to at least one rest position;

an escapement for transmitting impulses to the balance to move the balance from the rest position;

at least one said permanent magnet being formed of a non-sintered crystalline material.

In an advantageous embodiment, the permanent magnets are made of an alloy of platinum and cobalt. The ferromagnetic properties of these alloys are certainly known. However, their use has become largely obsolete, because the alloy is expensive and the coercive field Hc is lower than that which can be obtained with more economical materials.

However, platinum-cobalt alloys have the advantage of being available in crystalline and ductile form, which allows them to machining with very precise tolerances using conventional machining tools, such as milling, electro-erosion, etc. The dimensional accuracies that can be obtained are excellent, which makes it possible to ensure reproducibility of the volumes of magnetic material and therefore of the magnetic fields produced. Precise air gap and magnetic path distances can also be guaranteed by using these easy-to-machine materials.

The dimensional accuracy obtained is furthermore sufficient to avoid the use of glues for fixing the magnets, which can be maintained by mechanical means, for example by driving them into a housing provided for this purpose. This avoids disturbances of magnetic fields caused by the glue.

Platinum-cobalt alloys are also slightly oxidizable and insensitive to temperature variations. In a preferred embodiment, at least one permanent magnet is made of a material consisting of 75 to 78% platinum (for example 76.85%) and less than 24% cobalt.

Other unsintered magnetic materials may be employed for permanent magnets, including micropowder-based magnets, plastic magnets, or other ductile magnetic alloys (Fe-Cr-Co, Remalloy, Cunife, Cunico, Vicalloy etc. ). The weak coercive field of these other materials, however, makes their use less suitable for horological applications; it is necessary to use large volumes to generate the necessary magnetic fields. On the other hand, the magnetic field produced depends very much on temperature variations.

In an advantageous embodiment, the permanent magnets comprise several layers arranged so that the magnetic field variations compensate at least partially. In an advantageous embodiment, the stationary magnets are connected to the plate or to a bridge, and polarized so as to attract the mobile magnets of the balance to the equilibrium position. The distance between the opposite poles of the fixed and mobile magnets is therefore minimal at the rest position, so that the attraction torque to this rest position is important.

This important torque makes it possible to oscillate the balance at a high frequency, and thus to obtain an improved resolution in the measurement of time. If a very high frequency is not essential, it is also possible to reduce this torque by using permanent magnets of small volume, which allows to miniaturize the movement.

In an advantageous embodiment, the restoring torque C of the pendulum varies proportionally or substantially

proportional to the angular position Θ of the pendulum: C≡ k Θ

K being a constant and Θ indicating the deflection angle of the balance relative to the rest position. This relationship is

preferably true for at least a portion of the angular segment traversed by the balance during its normal oscillations, preferably for most of this segment. With this linear relationship, the regulating member operates almost isochronously, that is to say that the oscillation period is almost independent of its amplitude.

The invention will be better understood on reading the description of various embodiments illustrated by the figures which show: FIG. 1 is a plan view of a regulating member according to a first embodiment.

Figure 2 is a perspective view of a regulating member according to a second embodiment. Figure 3 is a perspective view of a regulating member according to a third embodiment.

Figure 4 a sectional view of a regulating member according to the third embodiment. Figure 5 is a sectional view of a multilayer magnet.

Figure 1 shows a top view of a regulating member for wristwatch movement, according to a first embodiment of the invention. The regulating organ mainly comprises an oscillator with a rocker 1 of which only the parts in the plane of the magnets are represented; the complete pendulum preferably includes a not shown serge mounted on the same axis 1 1 but in another plane.

The oscillator also includes fixed permanent magnets 2 and an escapement of which only the escape wheel 6 and a portion of the anchor 5 are shown. The exhaust 5, 6 is in this example entirely conventional, and may be constituted by a known anchor escapement. Other types of exhaust, including for example magnetic exhausts, can however also be used in this variant as well as in the other embodiments described in the application. The pendulum 1 of the oscillator rotates about an axis 1 1 linked to a bridge and the plate by means of unrepresented bearings, for example incabloc bearings or magnetic bearings. In the embodiment shown, an annular portion 10 at the periphery of the balance 1 is magnetized permanently and without discontinuities all around the balance. This annular portion 10 constitutes a dipole with two opposite poles spaced in this example by 180 ° and represented symbolically with the symbols + and -.

In the variant of Figure 1, the permanent magnets 10 of the beam 1 are constituted by a ring magnetized continuously. This provision is advantageous because it is easier to obtain a return torque that varies linearly and continuously with the angular deviation Θ of the balance relative to the rest position. However, it is also possible to provide the balance 1 of several discrete magnets glued or reported, or to use a zone or a magnetization intensity which varies depending on the angular position around the balance. In another variant, the ring 10 is discontinuous, and for example provided with one or more air gaps, or magnetized with jumps / discontinuities of

magnetization. The magnetization of the periphery 10 of the beam 1 can for example be obtained by magnetizing it by means of a head

recording.

The regulating member of this example comprises two fixed permanent magnets 2 arranged at 180 ° from each other on either side of the balance. One of the poles of each magnet is towards the inside of the regulating organ and the opposite pole towards the outside. In addition, the polarities of the two fixed permanent magnets 2 are opposite to each other, as illustrated with symbols + and -. Reference 7 corresponds to the air gap

(gap) between the fixed permanent magnets 2 of the stator and the movable magnets 10 of the rotor. In the figure, the balance 1 is shown in the rest position, and the two poles of the balance 1 are each facing the middle of the fixed magnet 2 of opposite polarity. When the rocker 1 moves away from this rest position, for example under the effect of the escapement or shock, one of the two fixed permanent magnets 2 attracts it again, while the other magnet opposite the pushes back towards this position of rest.

The fixed permanent magnets 10 advantageously have in this example a shape comprising a central portion 21 and peripheral portions 20 on either side of the central portion 21. The section of the two peripheral portions 20 in a radial plane perpendicular to the page increases gradually away from the central portion 21. This results in a magnetic field, and therefore a mechanical return torque, which grow linearly throughout the section 20 when the rocker 1 moves away from the rest position.

The central portion 21 of the fixed permanent magnets 2 however forms a protuberance and thus has a large radial section. These two protuberances 21 have several important effects:

on the one hand, they make it possible to control the direction of the magnetic field lines and to make sure that these lines are as straight as possible along the axis of symmetry of the stator, avoiding the

deformations that would inevitably occur at both ends if the magnetic field was too weak in this portion 21.

on the other hand, these protuberances make it possible to create a very strong localized magnetic attraction zone close to the desired resting zone, and thus to prevent the pendulum from stopping or being attracted towards one on several others. possible equilibrium zones (for example towards the discontinuities formed by the junction between the magnets 2 and the cylinder head 3).

These protuberances have the disadvantage of introducing a discontinuity in the relationship between the angular deflection and the mechanical return torque; the torque increases instead of decreasing when the magnetic poles of the balance 1 are in the immediate vicinity of these protuberances 21 and that the balance approaches the rest position. This disturbance is however very local and however

detrimental to isochronism, because it occurs only when the balance 1 receives the pulse of the exhaust; this pulse introduces a disturbance substantially greater than that produced by the protuberances 21, whose effect on isochronism can be neglected.

Other means than protrusions can be imagined to very locally strengthen the magnetic field near the rest positions; for example, it would be possible to magnetize more magnets at this location, or increase their thickness. A yoke 3 made of soft magnetic material holds and connects the two stationary magnets 2 to each other. This yoke also makes it possible to guide the magnetic flux between these magnets and to limit the portion of the flux

magnetic escaping to other components of the watch. On the other hand, the magnetic field re-emitted by this yoke 3 also contributes to the generation of the pendulum return torque, and is used to control the direction and amplitude of this field in space. Note the substantially non-circular elliptical shape of the gap 7 between the yoke 3 and the rocker 1. This shape determined by calculation and numerical simulation is optimized in order to guarantee the linearity between deflection angle and torque and in particular to ensure a high restoring force when the rocker 1 moves away from the rest position and exceeds the angular segment of about 60 ° defined by the two permanent magnets 20. "Substantially elliptical" means here that the ellipse is deformed at both longitudinal ends by the protuberances 21; a not strictly elliptical oval shape could also be

considered.

Mechanical or magnetic stops may be provided to limit the maximum amplitude of oscillations of the balance 1. A magnetic stop, for example a zone of strong magnetization integral with the cylinder head 3, makes it possible to push the rocker arm towards its rest position without presenting the disadvantages of the mechanical stops causing shocks likely to disturb the isochronic movement of the rocker arm.

Figure 2 illustrates another variant of magnetic regulating member according to the invention. The rocker 1 is made in the same manner as in the example of Figure 1, and has a magnetic annular peripheral section 10. The fixed permanent magnets 2, however, have a simpler shape and comprise a single magnetic circular ring around the balance. A cylinder head 3 here in two parts surrounds this ring 2 and thus constitutes a magnetic shielding preventing the field

magnetic to go out. In this arrangement, the return torque is only very approximately proportional to the angular deflection Θ of the balance. Nevertheless, in order to guarantee isochronism, the balance 1 is forced here to perform oscillations of small amplitude over a sufficiently small angular segment so that the non-linearity can be practically neglected.

For this purpose, the regulating member comprises a reduction gear with a wheel 20 on the axis 1 1 of the beam and a pinion 21 actuated by the fork of the anchor 5. With this gearing, the pulses given by the exhaust 5 , 6 cause a rotation of limited amplitude of the balance, so that the restoring torque is almost linear in this limited area.

A similar reduction can also be used with a regulating member similar to that of Figure 1, or Figure 3 for example. Furthermore, it is also possible to introduce a gear upstream of the escape wheel 6, rather than downstream as in the example; this variant reduces the friction in the regulating member, but has the disadvantage of not being able to be integrated into an existing movement without a complete redesign. The reduction 20, 21, however, has the disadvantage of introducing additional losses by friction.

Figures 3 and 4 illustrate another embodiment in which two permanent magnets 2 are arranged in two planes above, respectively below the plane of the balance 1. In the example, the positive pole of the upper permanent magnet 2 is directed towards the balance, while the negative pole of the lower permanent magnet is directed towards the balance. A yoke 3 connects and holds the two permanent magnets 2 and thus strengthens the magnetic field in the gap 7 between the two magnets and the balance. The balance 1 is provided with a single magnet 10, here a non-permanent magnet (punctual magnet) made of a ferromagnetic material. This magnet forms one of the spokes connecting the periphery of the balance to its axis 1 January. The outer extremity of this ray widens in the shape of a half-moon. The magnetization of this magnet is therefore determined by the field

The half-moon shape of the magnetic zone 10 ensures a return torque that varies linearly with the deflection angle with respect to the rest position (not shown). Other variants can be imagined in the context of the invention. For example, it is possible to provide the balance 1 of one or more permanent magnets and a movable breech ferromagnetic material (or not) to direct the magnetic field between these magnets. The fixed yoke - or the bolt - can be provided with an air gap to avoid the risk of saturation of the ferromagnetic material. It is also possible to use yokes formed of ferromagnetic sheets or grains of ferromagnetic materials, in order to control the induced currents that can circulate there. In a preferred variant,

however, will use a cylinder head in a 50-50 alloy of Iron and Nickel, with little magnetic hysteresis.

The variation of the magnetic field and the magnetic torque as a function of the angular deflection can also be controlled by modifying the thickness, the section in a radial plane, and / or the magnetization of the fixed or moving magnets as a function of the angular position. In all the above variants, the accuracy of the isochronism depends in a significant way on the shape of the permanent magnets. Initial manufacturing tests with standard neodymium-type magnets, or with other common permanent magnets, have, however, proved inconclusive, since it is difficult or expensive to machine the sintered materials that make up these magnets with the required dimensional accuracy. usual permanent. According to an independent characteristic of the invention, the regulating member implements permanent magnets in materials which are certainly a little less powerful than the neodymiums and other modern materials usually used, but which have the advantage of being unsintered and available. in crystalline form; they can therefore be machined more easily with the required accuracy. In an advantageous embodiment, the magnets are based on unsintered platinum cobalt, which is one of the materials whose magnetic remanence is insensitive to temperature variations. This material also has the advantage of being slightly oxidizable, and therefore does not need to be nickel plated to protect it. Convincing tests were obtained with magnets consisting of 75 to 78% platinum (for example 76.85%) and less than 24% cobalt.

A heat treatment is preferably applied to the magnets after machining, to make it magnetizable.

Permanent magnets made of these materials can be machined with such precision that they are preferably simply driven out or mechanically held in motion; this avoids the use of glues, which disturb the direction of the magnetic field lines.

The march of the watch is determined at least in part by the magnetic field developed by the different permanent magnets, and by the magnetic attraction force exerted on the balance. This field and this force, however, vary with each individual magnet, and it is difficult to ensure perfect reproducibility during mass production. In order to compensate for this variability, the regulating member advantageously comprises means for adjusting the position of at least one individual magnet, making it possible to adjust it to the mounting in order to adjust the running of the watch. In an advantageous embodiment, these means are for example constituted by at least one micrometer screw, or another threaded element, allowing to bring closer or to separate at least one corresponding permanent fixed magnet from the balance, in order to influence the magnetic field. exerted by this magnet on the magnetized portions of the balance. It is also possible to adjust the angular distance between two permanent magnets.

Other means of adjustment can be provided, for example playing on the size of an air gap in the cylinder head, or by adding or moving compensating masses on the balance. On the other hand, temperature compensation means can also be implemented, for example by employing a conventional bimetallic balance which is deformed under the action of temperature. Alternatively, components with a high coefficient of expansion, or bimetallic components, are used to move the fixed or moving permanent magnets as a function of temperature, so that

in particular to compensate for variations in the efficiency of the magnets when the temperature varies.

FIG. 5 illustrates a sectional view of a multilayer magnet generating a magnetic field almost independent of the temperature in the useful temperature ranges. In this example, the magnet comprises a layer 25 and another 27 polarized in the same direction and both made of a material whose magnetic remanence varies little with temperature. The intermediate layer 26 is made of another material (for example neodymium, etc.) polarized in the opposite direction and which generates a magnetic field smaller than the sum of the fields generated by the two layers 25 and 27. The magnetic remanence of the layer 26 however varies greatly with temperature. Stacking resulting from layers 25 to 27 is equivalent to a polarized magnet in the same direction as the layers 25 and 27, the amplitude of the resulting field being reduced by the layer 26. By judiciously choosing the materials and the thicknesses of the layers 25 to 27, it is possible to thus producing a magnet whose variations of remanence in the layers 25 and 27 are almost completely canceled by the variations in the layer or layers 26 polarized in opposite direction.

The number of layers and / or materials used to make temperature-insensitive magnets may be different from the illustrative example shown in Fig. 4. In one embodiment, the magnets are formed from a variety of materials including variations in remanence. offset each other but without arranging the materials in layers. Multilayer or multi-material magnets can be used for permanent magnets as well as for mobile permanent magnets.

In one embodiment, the currents induced by the rotating magnetic field created by the rotation of the magnetic balance are used to adjust the operation of the watch. These currents can for example be measured by means of a coil connected to the movement, and their frequency or their phase used by an electronic circuit (which can itself be supplied by these currents) to determine the running of the watch, and possibly correct it.

The bridges, plates, wheels and other mobile elements close to the regulating member are preferably made of a material

non-magnetic in order to limit the disturbances caused by the flows

magnetic parasites that escape the organ despite the breech. Magnetic shields may be provided for magnetically separating the regulating member from sensitive elements in at least some directions. Advantageously, a grounding (that is to say platinum) of the adjacent elements in which currents can be induced is advantageously provided in order to protect these elements. The regulating organ described proves particularly effective for generating high return torques, and therefore frequencies oscillation. One possible application relates for example to a regulating organ for a chronograph organ; the high oscillation frequency significantly improves the resolution and

mechanically time durations with a resolution of one tenth, one hundredth or even one thousandth of a second. For example, it is possible in the context of the invention to produce regulating members with more than 72Ό00 alternations per hour, for example 360Ό00 alternations, 720Ό00 alternations, or more. Even if the energy dissipated by the exhaust and gear at such frequencies is important, it is not detrimental for use in a stopwatch which is intended for use for limited periods. Furthermore, it is possible to drive this high frequency regulating member with an additional barrel, for example an independent of the main barrel used for displaying the time.

High frequencies, however, require powerful magnets or very thick, which affects the desire for miniaturization.

Such a regulating member may for example be added to the main regulating member used in a wristwatch movement to give the time. The watch comprises in this case a very high resolution and very high precision regulating member dedicated to the measurement of timed durations.

This magnetic regulating member may also be mounted in the same movement as the main regulating member, or in an auxiliary module superimposed over the basic movement, for example in an additional chronograph module. The claimed solution also has the advantage of being devoid of a spiral spring. In addition to the advantages mentioned above (supply, disturbances due to gravity etc), the removal of this organ allows to see through the regulating member, between the spokes of the beam, without the hairspring shields the components backwards. plan. The regulating organ of the invention will therefore advantageously be disposed behind an opening of the dial or in the bottom of the watch. so as to clearly show the pendulum oscillating rapidly and the components behind this pendulum.

The regulating member of the invention is preferably mounted in a movement and in a watch case revealing at least part of the balance, which allows the user to control his

travel at all times.

Claims

claims

1. Magnetic regulating member for wristwatch movement, comprising:

a balance (1);

permanent magnets (2, 10) for bringing said balance to at least one rest position;

an escapement (5, 6) for transmitting impulses to the balance to move the balance (1) away from the rest position;

characterized in that at least one said permanent magnet is formed of a non-sintered crystalline material.

2. The regulating member of claim 1, wherein said at least one permanent magnet (2, 10) is made of a platinum-cobalt alloy.

3. The regulating member of one of claims 1 to 2, wherein said at least one permanent magnet (2, 10) is fixed without glue.

4. The regulating member of one of claims 1 to 3, wherein said at least one permanent magnet (2, 10) comprises a plurality of materials (25, 26, 27) arranged so that the variations of magnetic remanence depending on the temperature at least partially compensate.

5. The regulating member of claim 4, wherein said at least one permanent magnet (2, 10) comprises several layers of materials (25, 26, 27) whose variations of magnetic remanence as a function of the temperature compensate for the less partially.

6. The regulating member of one of claims 1 to 5, wherein said at least one permanent magnet (2, 10) is formed of a heat-treated material after machining.

7. The regulating member of one of claims 1 to 6,

comprising means for adjusting the position of at least one fixed permanent magnet (2) in order to bring it closer to or away from the balance (1) and thus to adjust the running of the watch.

8. The regulating member of one of claims 1 to 7, wherein at least one of the magnets (2, 10) has a shape not

parallelepipedal, non-annular and non-cylindrical, adapted to ensure the proportionality between the mechanical return torque and the angular deflection of the balance (1) relative to the rest position.

9. The regulating member of one of claims 1 to 8,

having a magnetic escapement.

10. The regulating member of one of claims 1 to 9, the rocker being held by a magnetic bearing.

1 1. Mechanical watch movement comprising a

chronograph whose running is determined by a regulating member according to one of claims 1 to 10.

The movement of claim 11, comprising:

a first regulating organ for determining the running of the watch; and

said magnetic regulating member for determining the chronograph operation, the frequency of the magnetic regulating member used to determine the running of the watch being greater than the frequency of the first regulating member.