EP3944027A1 - Portable object, in particular a wristwatch, comprising a power supply device provided with an electromechanical converter - Google Patents

Abstract

Portable object (42) comprising an electronic unit and an electrical power supply unit formed by an electromechanical converter (6A) which comprises a rotor (44) carrying first magnets (10A), a mechanical resonator (12A) provided with a inertia (46) capable of oscillating at a relatively high resonant frequency and carrying second magnets (20), and coils arranged so that, when the mechanical resonator is oscillating, an induced voltage is generated in these coils. The electromechanical converter is arranged so that the first magnets and the second magnets can, when the rotor is driven in rotation, interact magnetically so as to apply to the inertia mass, momentarily or at times, a torque of magnetic force making it possible to excite the mechanical resonator, in order to generate at least one oscillation of this mechanical resonator at its resonant frequency to generate a relatively high induced voltage making it possible to recharge an accumulator.

Description

Technical area

The invention relates to portable objects, in particular portable objects on the wrist such as watches, which incorporate an electronic unit and an electrical power supply unit for supplying power to at least this electronic unit. More particularly, the invention relates to so-called autonomous portable electronic devices, which are provided with an electric power supply unit which draws energy from an internal mechanical device, in particular from a generator associated with a source of internal mechanical energy (for example a barrel whose spring is wound automatically by a rotor or manually), or from at least one sensor receiving energy from the environment of the portable electronic device or from a user wearing this electronic device. We thus speak of energy harvesters incorporated in autonomous electronic devices.

Technology background

The movement of the wrist constitutes a source of mechanical energy which can be exploited to power a wristwatch. This has been exploited for a very long time in automatic mechanical watches. More recently, those skilled in the art have thought of using the mechanical energy of a rotor to supply electricity to at least one electronic unit of a wristwatch of the electromechanical or electronic type. To this end, various types of electromechanical converters have been proposed. In particular, the use of electromagnetic induction has proven successful. Mention may be made of two known types of autonomous watches having an electronic unit. The first type is described in particular in the patent application EP 822 470 , in the name of Asulab. It is an electromechanical watch comprising an electromechanical generator incorporated in a gear train of the watch movement and having two functions, namely a function for regulating its rotation frequency and an electromechanical converter function to be able to supply the electronic circuit of regulation. The second type is described in particular in the patent application EP 1 239 349 and WO 9204662 , on behalf of KINETRON. A particular embodiment is described in the patent application EP 1 085 383 , on behalf of ETA SA Manufacture Horlogère Suisse. In this second type, the rotor serves only to drive an electromechanical generator which supplies electricity to an accumulator incorporated in the watch of the electronic type. In the case of an electromechanical watch movement, the hands are driven by an electric motor, in particular step-by-step, which is powered by the accumulator.

The aforementioned embodiments have a factor limiting their performance, in particular because of energy losses due to friction in the gear trains. In addition, to obtain a sufficiently high tension, at least one intermediate multiplier mobile and/or a complex device allowing a barrel to restore the accumulated mechanical energy by pulses are necessary.

Another approach to harvest kinetic energy in a watch is to implement a rotor equipped with magnets in its peripheral part, with fixed coils integrated on a PCB above which the rotor magnets pass. When the rotor is driven, a voltage is then induced in the coils due to the variation of the magnetic flux. A disadvantage of this approach is that the rotor rotates relatively slowly (typically with an average rotational speed between 1 and 5 rpm), which limits the energy conversion efficiency due to the low induced voltages that are generated.

Summary of the invention

The object of the invention is to provide a portable device provided with an electronic unit and a power supply unit comprising an electromechanical converter having good efficiency, in particular by supplying a relatively high voltage before any possible voltage booster.

• un rotor susceptible d'être entrainé en rotation par des mouvements que peut subir l'objet portable, ce rotor portant au moins un premier aimant permanent ;
• un résonateur mécanique monté sur un support et muni d'une masse d'inertie susceptible d'osciller, autour d'un axe d'oscillation, à une fréquence de résonance propre à ce résonateur mécanique ; et
• un système électromagnétique formé par au moins un deuxième aimant permanent et au moins une bobine qui sont respectivement portés par la masse d'inertie, formant ainsi partiellement cette masse d'inertie, et par ledit support ou un élément solidaire de ce support et qui sont agencés de manière que, lorsque le résonateur mécanique est au repos, au moins une partie du flux magnétique généré par le deuxième aimant permanent traverse la bobine de sorte que, lorsque le résonateur mécanique est oscillant, une tension induite (U_Ind) est générée dans cette bobine.

Thus, the invention relates to a portable object comprising an electronic unit and an electrical power supply unit formed by an electromechanical converter comprising:

• a rotor capable of being driven in rotation by movements which the portable object may undergo, this rotor carrying at least one first permanent magnet;
• a mechanical resonator mounted on a support and provided with an inertial mass capable of oscillating, around an axis of oscillation, at a resonance frequency specific to this mechanical resonator; and
• an electromagnetic system formed by at least one second permanent magnet and at least one coil which are respectively carried by the inertial mass, thus partially forming this inertial mass, and by said support or an element integral with this support and which are arranged so that when the mechanical resonator is at rest, at least part of the magnetic flux generated by the second permanent magnet passes through the coil so that when the mechanical resonator is oscillating, an induced voltage (U _Ind ) is generated in this coil.

The electromechanical converter is arranged in such a way that said at least one first permanent magnet and said at least one second permanent magnet can, when the rotor is driven in rotation, interact magnetically so as to apply to the inertial mass, momentarily or at times, a couple of magnetic force making it possible to excite the mechanical resonator, in order to generate at least one oscillation of this mechanical resonator substantially at its resonant frequency.

In an advantageous variant, the resonant frequency is substantially equal to or greater than ten Hertz (F _Res >= 10 Hz), preferably between fifteen Hertz and thirty Hertz (15 Hz <= F _Res <= 30 Hz).

In a main embodiment, said at least one first permanent magnet and said at least one second permanent magnet are located in the same general plane, perpendicular to the axis of oscillation of the mechanical resonator, and arranged so that their magnetic interaction is in repulsion.

In a preferred variant, when the mechanical resonator is at rest, the center of said second permanent magnet and the center of said coil have between them an angular offset, relative to the axis of oscillation of the mechanical resonator, which is non-zero and which preferably corresponds to an angular positioning of the center of the second permanent magnet substantially at a point of inflection of the curve of the magnetic flux, generated by said at least one second permanent magnet and passing through the coil, as a function of the relative angular position between the second permanent magnet and the coil.

Brief description of figures

• Les Figures 1A à 1C montrent une première variante d'un premier mode de réalisation d'un objet portable selon l'invention, la Figure 1A étant sans le rotor et la Figure 1B étant coupée seulement partiellement;
• Les Figure 2A et 2B montrent une deuxième variante du premier mode de réalisation, la Figure 2B montrant seulement le système magnétique global prévu;
• Les Figures 3A à 3C montrent un deuxième mode de réalisation d'un objet portable selon l'invention, la Figure 3C ne présentant le résonateur mécanique que partiellement;
• Les Figures 4A à 4F montrent le fonctionnement du convertisseur électromécanique du deuxième mode de réalisation par une succession de positions instantanées du rotor tournant et du résonateur mécanique activé par ce rotor tournant;
• Les Figures 5A à 5C montrent un troisième mode de réalisation d'un objet portable selon l'invention;
• La Figure 6 est un éclaté en perspective du résonateur mécanique, du rotor et du système électromagnétique du troisième mode de réalisation ; alors que la Figure 7 représente ces parties assemblées;
• Les Figures 8A à 8H montrent le fonctionnement du convertisseur électromécanique du troisième mode de réalisation par une succession de positions instantanées du rotor tournant et du résonateur mécanique activé par ce rotor tournant;
• La Figure 9 est un schéma électrique d'une variante de réalisation d'un circuit électronique reliant les bobines du système électromagnétique, formant l'objet portable selon l'invention, à un accumulateur d'énergie électrique incorporé dans cet objet portable.

The invention will be described below in more detail with the aid of the accompanying drawings, given by way of non-limiting examples, in which:

• The Figures 1A to 1C show a first variant of a first embodiment of a portable object according to the invention, the Figure 1A being without the rotor and the Figure 1B being cut only partially;
• The Figure 2A and 2B show a second variant of the first embodiment, the Figure 2B showing only the predicted global magnetic system;
• The Figures 3A to 3C show a second embodiment of a portable object according to the invention, the Figure 3C presenting the mechanical resonator only partially;
• The Figures 4A to 4F show the operation of the electromechanical converter of the second embodiment by a succession of instantaneous positions of the rotating rotor and of the mechanical resonator activated by this rotating rotor;
• The Figures 5A to 5C show a third embodiment of a portable object according to the invention;
• The Figure 6 is an exploded perspective view of the mechanical resonator, rotor and electromagnetic system of the third embodiment; while Picture 7 represents these assembled parts;
• The Figures 8A to 8H show the operation of the electromechanical converter of the third embodiment by a succession of instantaneous positions of the rotating rotor and of the mechanical resonator activated by this rotating rotor;
• The Figure 9 is an electrical diagram of an alternative embodiment of an electronic circuit connecting the coils of the electromagnetic system, forming the portable object according to the invention, to an electrical energy accumulator incorporated in this portable object.

Detailed description of the invention

With reference to Figures 1A to 1C , 2A and 2B , two variants of a first embodiment of a portable object according to the invention will be described below. This portable object is a wristwatch 2 comprising an electronic unit (incorporated in the watch movement 4) and an electrical power supply unit. It should be noted that the casing circle, which connects the watch movement to the case of the watch, and the back of the case have not been represented in the drawings. The power supply unit is formed by an electromechanical converter 6 which transforms energy mechanism of a rotor 8 into electrical energy which is stored in an electric accumulator, which supplies the electronic unit. The rotor is capable of being driven in rotation by movements that the watch may undergo, in particular when it is worn on the wrist of a user.

• un rotor 8 portant au moins un premier aimant permanent, en particulier deux aimants 10 diamétralement opposés par rapport à l'axe de rotation 14 du rotor (cas de la première variante représentée) ;
• un résonateur mécanique 12 monté sur un support (le mouvement horloger 4) et muni d'une masse d'inertie 16, en forme d'anneau, qui est susceptible d'osciller, autour d'un axe d'oscillation 14 confondu avec l'axe de rotation du rotor 8, à une fréquence de résonance F_Res propre à ce résonateur mécanique,
• un système électromagnétique formé par au moins un deuxième aimant permanent 20 porté par la masse d'inertie 16 et formant partiellement cette dernière, en particulier par six aimants 20 (cas des deux variantes représentées), et au moins une bobine 24 portée par un PCB 22 solidaire du mouvement horloger 4, le nombre de bobines étant égal au nombre d'aimants 20 portés par la masse d'inertie dans le cas des deux variantes représentées.

The electromechanical converter 6 comprises:

• a rotor 8 carrying at least a first permanent magnet, in particular two magnets 10 diametrically opposed with respect to the axis of rotation 14 of the rotor (case of the first variant shown);
• a mechanical resonator 12 mounted on a support (the watch movement 4) and provided with a mass of inertia 16, in the shape of a ring, which is capable of oscillating, around an axis of oscillation 14 coinciding with the axis of rotation of the rotor 8, at a resonance frequency F _Res specific to this mechanical resonator,
• an electromagnetic system formed by at least one second permanent magnet 20 carried by the inertial mass 16 and partially forming the latter, in particular by six magnets 20 (case of the two variants shown), and at least one coil 24 carried by a PCB 22 integral with the watch movement 4, the number of coils being equal to the number of magnets 20 carried by the inertial mass in the case of the two variants shown.

In general, said at least one second permanent magnet 20 and said at least one coil 24 are arranged so that, when the mechanical resonator 12 is at rest, at least part of the magnetic flux generated by said second permanent magnet passes through the coil. so that when the mechanical resonator is oscillating, an induced voltage (U _Ind ) is generated in this coil.

The electromechanical converter 6 is arranged in such a way that said at least one first permanent magnet and said at least one second permanent magnet can, when the rotor is driven in rotation, interact magnetically so as to apply to the inertial mass, momentarily or at times, a couple of magnetic force making it possible to excite the mechanical resonator, in order to generate at least one oscillation of this mechanical resonator substantially at its resonant frequency.

It should be noted that, in this text, all the magnets used are permanent magnets so that the latter will also be called each 'magnet'. By 'an oscillation' is meant an oscillatory movement for at least one period of oscillation and therefore having at least two alternations. We call 'alternation' each movement of the mechanical resonator between two extreme angular values which define its amplitude of oscillation. In a preferred variant, provision is made for at least one pair of first magnets 10 and at least one pair of second magnets 20 which interact magnetically to apply to the mass of inertia the torque of magnetic force which serves to activate/excite the mechanical resonator, as will be described in detail later with reference to the Fig. 4A-4F .

In a first variant, the magnets 20 and the coils 24 are arranged so that, when the mechanical resonator 12 is at rest, these magnets and these coils are respectively aligned radially, in axial projection in a general plane of the mechanical resonator, relative to the axis of oscillation 14. Preferably, in the rest position of the mechanical resonator, each magnet 20 and the corresponding coil 24 are aligned axially. In a second preferred variant, when the mechanical resonator is at rest, the center of each second magnet 20 and the center of the respective coil 24 have between them a non-zero angular offset relative to the axis of oscillation of the mechanical resonator. In particular, the angular offset provided corresponds to an angular positioning of the center of each second magnet approximately at a point of inflection of the curve of the magnetic flux, generated by this second magnet and crossing the respective coil, as a function of the relative angular position between this second magnet and this coil relative to the axis of oscillation of the mechanical resonator. This preferred variant makes it possible to increase significantly the induced voltage produced in each of the coils, in particular when the amplitude of oscillation of the mechanical resonator after each excitation of the latter is relatively small, for example of the order of the half-angle at the center of the magnets 20. A using series of measurements or simulations, those skilled in the art will be able to determine, on the one hand, the characteristics and dimensions of the coils and of the second magnets 20 and, on the other hand, an optimal angular offset between these second magnets and the respective coils to optimize the variation of the magnetic flux in each coil so that this variation is maximum when the mass of inertia has a maximum speed, that is to say when the mechanical resonator passes through its neutral position (position rest), in order to obtain the greatest induced voltage U _Ind .

The mechanical resonator 12 is a resonator with flexible blades 26, these flexible blades carrying the mass of inertia 16 and connecting the ring forming this mass of inertia to a central element 28 which is fixed to the support of the mechanical resonator, that is i.e. which is integral to the watch movement. Schematically, in the variant shown, the central element is held fixed by a central screw between a projecting part of a fixed central part of the rotor 8 and a nut screwed onto the central screw. This variant is given by way of simplified example. Those skilled in the art will know how to design various means for fixing the mechanical resonator to the watch movement, so as to ensure in particular good stability of the central element 28. It will be noted that this central element can be connected to the watch movement 4, or to a another support integral with this one, independently of the central part of the rotor 8.

It will be noted that the rotor 8 is similar to a winding mass of an automatic mechanical movement. The rotating part of the rotor is mounted on a fixed central part by means of a ball bearing. Thus, this first embodiment has the advantage of allowing synergy in the case where the watch movement is of the mechanical type, the rotor 8 can then be used to activate the mechanical resonator, as will be explained later, and also to simultaneously wind a barrel of the mechanical movement. In the latter case, the electronic unit which is powered by the power supply unit according to the invention has a function other than that of displaying the current time. For example, it is a communication unit using light or electromagnetic waves, a sensor and its electronic signal processing unit picked up, an electronic regulation unit for the average frequency of a balance-spring incorporated into the mechanical movement, an additional digital display, etc. It will also be noted that the rotor and the mechanical resonator are arranged with their respective central axis located at the center of the watch movement. However, in a variant, these mechanisms are arranged off-center relative to the central axis of the watch movement.

The electromechanical converter 6 is arranged at the rear of the watch movement 4, on the side of the bottom of the watch case 32 and therefore on the side opposite the dial 34 relative to the movement 4 which is here an electromechanical movement with an analog display of the time. Thus, this movement comprises a motor, in particular a stepper motor.

The first embodiment is characterized in particular by the fact that the rotor 8 is mounted free to rotate on a central part which is fixed, according to various variants, either to the fixed central element 28, or directly to the watch movement 4 or possibly to an internal device which is integral with this central element or with this watch movement and which is located on the other side of the mass of inertia 16 relative to the rotor, namely on the side of the analog display in the case of the watch 2. The rotor is configured in such a way as to present an imbalance to favor its rotation during the movements which the watch may undergo. In the first variant, the rotor has a peripheral part which extends over an angle of approximately 200° and carries the two magnets 10 in two internal cavities which open laterally inwards, these two magnets emerging from the peripheral part of the rotor towards the mass of inertia 16 of the mechanical resonator.

In the first embodiment, just as in the other embodiments which will be described subsequently, the first magnets 10 and the second magnets 20 are located in the same general plane which is perpendicular to the central axis 14 defining the axis of oscillation of the mechanical resonator 12 and the axis of rotation of the rotor 8, which coincide. The purpose of this characteristic is to avoid the appearance of an axial force on the inertial mass of the mechanical resonator and consequently also on the rotor. Then, the first magnets 10 and the second magnets 20 are arranged so that their magnetic interaction is in repulsion. In an advantageous variant, they all have axes of magnetization substantially parallel to the central axis 14. It should be noted that a variant with radial axes of magnetization is possible. Finally, it will be noted that there is provided an even number of first magnets 10 and also an even number of second magnets 20, each pair of first magnets and each pair of second magnets being arranged in a diametrically opposite manner relative to the central axis 14 The purpose of this characteristic is to avoid the appearance of an overall radial force on the mass of inertia of the mechanical resonator and consequently also on the rotor. Thanks to these various characteristics, one avoids, on the one hand, the appearance of axial magnetic forces on the mass of inertia 16 of the mechanical resonator 12 which would axially stress the flexible blades 26 and, on the other hand, the appearance of a global radial magnetic force which would constrain these flexible blades radially. Otherwise, the mass of inertia could either be moved axially or radially or even undergo a rotation around an axis perpendicular to the central axis 14, which would be detrimental to the proper functioning of the electromechanical converter 6 according to the present invention. The intended magnetic interaction between the first magnets 10 and the second magnets 20 must essentially allow to generate a couple of magnetic force on the mass of inertia 16 of the mechanical resonator 12.

In a variant not shown, provision is made to double the inertia mass by arranging on both sides of the coils 24 a first inertia mass 16 and a second inertia mass which is similar to it. Thus, each second magnet 20 is replaced here by a pair of second magnets having the same polarity and aligned axially with a coil 24 located between these two magnets, preferably at the same distance from each of them. Since the two magnets of each pair of magnets attract each other magnetically, it is advantageous, even necessary, for the two magnets of each of the pairs of second magnets to be rigidly assembled. In this variant, the first magnets 10 are advantageously located in a general plane in which the coils 24 are located. In another variant not shown, the first magnets 10 carried by the rotor are doubled so as to have pairs of first magnets of same polarity replacing each first magnet 10 of the two variants shown. It will be noted that this last variant allows an axial arrangement of the pairs of first magnets with the second magnets, that is to say that the first magnets and the second magnets have substantially the same radius at the central axis, defining the axis of oscillation of the mechanical resonator and the axis of rotation of the rotor, without an axial magnetic force being exerted on the mass of inertia. In a variant combining the two variants not shown described here, there are pairs of first magnets and pairs of second magnets. In a first case, all these pairs of magnets are located in two general planes located respectively on both sides of the general plane of the coils 24. In a second case, an axial arrangement of the pairs of first magnets with the pairs of second magnets is provided. .

In an advantageous variant, the resonance frequency F _Res is substantially equal to or greater than ten Hertz (F _Res >= 10 Hz). In a preferred variant, the resonance frequency F _Res is between fifteen Hertz and thirty Hertz (15 Hz <= F _Res <= 30 Hz). While the rotor generally rotates at a frequency of the order of magnitude of 1 Hz (i.e. 1 to 5 revolutions per second), the mechanical resonator oscillates at relatively high frequency and transforms the kinetic energy of the rotor into mechanical energy of oscillation, preferably via a magnet-magnet coupling in magnetic repulsion. As each coil is associated with a magnet of the mechanical resonator, the number of sinusoidal pulses generated in each coil is equal to twice the resonant frequency F _Res as long as the mechanical resonator oscillates freely. By arranging the electromechanical converter so that the mechanical resonator remains activated approximately continuously when the rotor rotates substantially at constant speed in a range of usual speeds, it is possible to obtain a large number of sinusoidal pulses of induced voltage at each revolution of the rotor. and thus effectively converting a certain part of the kinetic energy of the rotor into electrical energy which is supplied to an electrical supply accumulator.

To Figure 2A and 2B is shown a second alternative embodiment of a wristwatch 2A according to the first embodiment. The mechanical resonator is identical to that of the first variant. This second variant differs from the first variant in that the rotor 8A carries six magnets 10, that is to say the same number as that of the magnets 20 which are carried by the inertial mass 16. Like the six magnets 10 are regularly distributed along the peripheral part 38 of the rotor, this peripheral part extends over a complete turn (360°). The peripheral part thus forms an annular part which laterally surrounds the mass of inertia 16 of the mechanical resonator. In order to keep the rotor unbalanced, three openings 36 are machined in the rotor plate. Given that the six magnets of the mass of inertia are distributed regularly, each magnet 10 has an identical magnetic coupling with the magnets 20 so that the torques of force generated between each of the magnets 10 and the magnets 20 are added. The Figure 2B shows the predicted global magnetic system according to the invention, namely the magnets 10 carried by the rotor and serving to activate the mechanical resonator, the magnets 20 carried by the oscillating mass of inertia 16 of the mechanical resonator, and the coils 24 mounted on a PCB 22 of so as to be opposite the magnets 20 when the mechanical resonator passes through its rest position.

In a specific variant, the flexible blades 26 of the mechanical resonator are made of a piezoelectric material and each coated with two electrodes through which an electric current is generated when the mechanical resonator is activated, this electric current also being supplied to an accumulator as includes watch power supply unit 2 or 2A.

A second embodiment of a watch 42 comprising an electromechanical converter 6A according to the invention is shown in Figures 3A to 3C . This second embodiment differs from the first embodiment substantially by the arrangement of the rotor 44 and by the arrangement of the mechanical resonator 12A. The mechanical resonator comprises an inertia mass 46 and a resonant structure 48 mounted on a projecting part 4A of the watch movement 4. The inertia mass defines a wheel which is formed by an outer ring, similar to that provided in the first embodiment and carrying four magnets 20 distributed regularly, a central part and radial arms which connect the outer ring to this central part. The central part is firmly connected to an oscillating part of the resonant structure 48 with flexible blades which is located in a general plane lower than that of the mass of inertia. The resonant structure is of a type which is described in the patent application EP 3 206 089 . According to two particular variants, the radial arms of the mass of inertia are respectively rigid and semi-rigid. The semi-rigid variant makes it possible to absorb sudden accelerations of the inertia mass resulting in particular from shocks that the watch may suffer. Four coils 24 are arranged on a PCB 22 so as to have an angular offset with the four corresponding magnets 20 when the mechanical resonator 6A is in its angular position of rest, according to an advantageous variant which has been explained in the context of the first embodiment.

The rotor 44 is mounted free in rotation on a fixed structure of the portable object, advantageously on the middle part of the case 32 of the watch as in the variant shown or preferably on a casing circle of the watch movement 4, by means of a ball bearing 50. To release the central zone of the rotor under which the resonant structure 48 is located, an inner ring 51 of the ball bearing 50 is advantageously formed by the rotor or secured to this rotor, while an outer ring 52 of this bearing is formed by said fixed structure or secured to this fixed structure. In the variant shown, the raceway of the inner ring 51 is formed by an outer side surface of the rotor 44. Preferably, as in the variant shown, the ball bearing 50 is located at the periphery of the rotor 44.

In the specific variant shown, the rotor 44 is formed by an annular part carrying four magnets 10A and it is arranged in the same general plane as the inertia mass 46 of the mechanical resonator and the ball bearing 50. Thus, the rotor and the mechanical resonator are advantageously coplanar to limit the increase in thickness of the case 32 of the watch 42 generated by the arrangement of the electromechanical converter according to the invention in this watch. In addition, this assembly is also provided here coplanar with the ball bearing. In a variant, the ball bearing is arranged under the annular part of the rotor, on the side of the watch movement 4. The magnets 10A of the rotor are the same number as that of the magnets 20 of the mass of inertia 46 of the mechanical resonator 12A. The magnets 10A and 20 are advantageously arranged in the same general plane. In the variant shown, these magnets are inserted into respective openings of the annular part of the rotor and of the inertial mass, so that they are arranged in the general plane in which this annular part and this mass of inertia. As in the first embodiment described above, the magnets 10A and 20 have axial axes of magnetization and a magnetic interaction in repulsion. The magnets 10A, respectively 20 are arranged in diametrically opposed pairs. Thus, the mass of inertia is only subjected to a torque of magnetic force in the general plane in which the magnets 10A and 20 are arranged (in other words, the vector of this magnetic torque is axial, coinciding with the axis of oscillation 14 of the mechanical resonator 12A). It will also be noted that the annular part of the rotor 44 has two openings making it possible to generate an unbalance.

With reference to Figures 4A to 4F , the operation of the electromechanical converter of the second embodiment will be described more precisely and more particularly the activation of the mechanical resonator 12A by the rotor 44. In these figures, the rotor is represented only by the magnets 10A. In the particular example treated here, provision is made for the rotor to rotate counterclockwise at a substantially continuous speed of one revolution per second (1Hz). It will be noted that the electromechanical converter of the first embodiment operates similarly to the electromechanical converter of the second embodiment.

To the Figure 4A , the rotor is substantially stationary and the mechanical resonator 12A is stationary in its rest position. From this initial position of the electromechanical converter, the rotor with its magnets 10A rotate counterclockwise at a substantially constant speed, after an initial acceleration resulting for example from a sudden movement of the arm of a user of the watch 42. At the Figure 4B , the four magnets 10A of the rotor have approached the four magnets 20 of the mechanical resonator. A magnetic interaction occurs between each magnet 10A and a corresponding magnet 20. A magnetic repulsion force F _RM is then exerted on each of the magnets 20 and a first strong magnetic coupling occurs. Note that the radial components of the four forces F _RM cancel each other out by pair of diametrically opposed magnets, while the tangential components of these forces F _RM add up and generate a torque of magnetic force applied to the mass of inertia 46 of the mechanical resonator, this torque of magnetic force rotating the mass of inertia 46 so that the magnets 20 carried by this mass of inertia undergo an angular displacement by deviating from the rest position of the mechanical resonator, as this is made visible by the circles in broken lines indicating, at the Figures 4B to 4F , the angular position of rest of the magnets 20 and also the angular position of each of the four coils 24 of the electromechanical converter 6A. The magnetic repulsion force F _RM increases further in intensity when the magnets 10A come even closer to the respective magnets 20, but it is mainly the radial component which increases so that the magnetic force torque exerted on the mass of inertia passes through a maximum for a relative angular position of the magnets 10A and the magnets 20 which is shown in Figure 4C .

Once the elastic restoring torque of the mechanical resonator is equal to the magnetic force torque and insofar as the latter increases more strongly than the magnetic force torque in the event that the latter continues to increase, an oscillation of the mechanical resonator begins thanks to to the elastic restoring torque of the mechanical resonator which drives the mass of inertia in the opposite direction to that of the rotor, as shown in Figure 4D . What is remarkable in the magnetic coupling between the rotor and the mass of inertia of the mechanical resonator comes from the fact that not only does it exert an initial torque of magnetic force in the direction of rotation of the rotor, generating an initial movement of the mass d inertia allowing it to be moved away from its rest position to then allow oscillation at the resonance frequency, but this magnetic coupling then exerts, as soon as the magnets 10A angularly exceed the corresponding magnets 20 to which they are substantially coupled during said initial movement , a couple of magnetic force of opposite direction which gives energy to the mass of inertia in the first alternation of its oscillation following the aforementioned angular overshoot and which makes it possible to amplify the oscillation of the inertia mass at the resonance frequency F _Res . To Figures 4E and 4F two instantaneous positions of the electromechanical converter are represented during two alternations following the first alternation represented in Figure 4D . Thus, given the _{relatively high resonance frequency F Res} , i.e. for example 20 Hz in the example treated, several alternations can occur substantially at this resonance frequency before the magnets 10A of the rotor are again strongly coupled with the magnets 20 of the inertia mass, each magnet 10A then being substantially magnetically coupled with a next magnet 20 (in the direction of rotation of the rotor) of the inertia mass during this new strong magnetic coupling.

The new strong magnetic coupling can generate various variants of magnetic interaction and thus act according to various scenarios on the mechanical resonator. These various scenarios depend in particular on the fact that the mechanical resonator rotates in the same direction of rotation as the rotor at the start of a new strong magnetic coupling or, on the contrary, that the respective rotations of the rotor and of the mechanical resonator are then of direction opposites. In the first case, the new strong magnetic coupling will serve for the most part to maintain the first oscillation generated during the first strong magnetic torque. In the second case, firstly, the new strong magnetic coupling slows down the inertial mass and therefore substantially dampens the first oscillation, then secondly generates a second oscillation, mainly by the magnetic force couple in the opposite direction to that of the rotor which intervenes after the magnets of the rotor have angularly exceeded those of the mass of inertia. It will be noted that because the resonance frequency is relatively high, the second case is predominant. Moreover, even if the first case can be predominant in certain situations, the mass of inertia often passes through a short time of stopping or of quasi immobility (not necessarily at the position of rest, because also possible in other angular positions and in particular close to an extreme angular position of the oscillating mechanical resonator) generating a time phase shift in the oscillatory movement of the mechanical resonator. Thus, the distinction between sustained oscillation and succession of oscillations is not clear. When the mechanical resonator stops for a certain interval of time in its rest position, we can speak of two successive oscillations, and in the opposite case we can then speak of the maintenance of an oscillation in progress, often with the introduction of a temporal phase shift. Be that as it may, a plurality of successive momentary oscillations can be observed between the successive strong magnetic couplings substantially at the resonance frequency F _Res .

In a main variant, the electromechanical converter is arranged so that the magnetic force torque applied to the inertial mass by the rotor makes it possible to generate, during rotational driving of the rotor over an angular distance greater than l central angle between two adjacent magnets 20 of the mechanical resonator, a plurality of successive momentary oscillations, at the resonance frequency F _Res and with an amplitude substantially equal to or greater than a minimum amplitude for which the voltage induced in each coil of the system magnetic, associated with the mechanical resonator, is substantially equal to a predetermined threshold voltage, this plurality of successive momentary oscillations occurring following a plurality of respective momentary rotation drives of the inertial mass of the mechanical resonator by the rotor allowing respectively generating the plurality of successive momentary oscillations.

By way of example, each coil 24 has a diameter of 4 mm, a height of 0.4 mm, 2300 turns and a resistance of 2.6 KΩ. Each coil is fixedly arranged at an axial distance of 0.1 to 0.2 mm under the respective magnets 20 of the mechanical resonator, which are chosen with strong remanent magnetization and have an approximately identical diameter. to that of the coils. By selecting a mechanical resonator having a resonance frequency F _Res approximately equal to 20 Hz and having an average amplitude between 7° and 10° when it is activated by the rotor rotating with a usual angular frequency, the magnetic system described here, associated to the mechanical resonator, can generate an average power of the order of 2 µW per coil on an impedance matched load and an average induced voltage of the order of 100 mV per coil. Note that higher performance is possible.

The Figure 9 is an electrical diagram of an alternative embodiment of an electronic circuit of the electromechanical converter connecting the coils, referenced 24*, of the electromagnetic system to an electrical energy accumulator 98 incorporated in the portable object according to the invention. The set of coils, generally of an even number and connected in parallel or in series, are connected to a rectifier 94 to which this set supplies an induced voltage U _Ind . The induced voltage signal is then supplied to a smoothing filter 95 and to a voltage booster 96 (which are optional) to generate a recharge voltage U _Rec of the accumulator 98. The accumulator supplies a supply voltage U _Al to a load 100 incorporated in the portable object considered. Other specific electronic units may be provided, in particular to guarantee a value of the supply voltage U _Al within a useful range and to ensure a certain stability of this voltage. A switch Sw is provided to be able to activate or not the power supply to the load, depending on the demand and/or other electrical parameters, in particular the voltage level of the accumulator 98.

With reference to Figures 5A to 8H , a third embodiment of a wristwatch 62 provided with an electromechanical converter 6B according to the invention will be described. Several similar or similar elements to those already described above will not be described again here in detail. It will be noted that the mechanical resonator 12B is essentially identical to the mechanical resonator 12A already described. His operation is similar. Only the external profile of the mass of inertia 16B is different, in connection with the specific character of this third embodiment which differs from the previous mode essentially by the arrangement of the rotor 66 allowing greater efficiency to activate the mechanical resonator 12B, and by fixing the rotor directly to the housing 32A given the presence of the resonant structure 48 located in the center of the mechanical resonator. This fixing of the rotor to the bottom of the case constitutes an alternative to the system proposed within the framework of the second embodiment, a system which can also be provided here as a variant.

The watch movement 4 bears on its rear projecting part 4A, inserted in an opening of the PCB 22 carrying four coils 24, the resonant structure 48 whose part 48A is fixed to this rear projecting part. The resonant structure further comprises an oscillating part 48B which is connected to the fixed part 48A by a system of flexible blades located in the same general plane and defining an axis of oscillation for this oscillating part and for the mass of inertia 16B which is fixed to the latter via a stud which is inserted into a corresponding hole arranged in a central element 18 of this mass of inertia. The inertia mass 16B carries in its peripheral part four circular magnets 20 which are inserted into holes of four respective projecting parts between which are provided four free angular zones 78 opening laterally onto the space outside the inertia mass and s extending radially to a radius corresponding to that of a geometric circle in which the mass of inertia 16B is inscribed. The rotor 64 is formed of three parts, a fixed central part 71, a half-disc 70 having a more massive peripheral part, and an annular structure 72 which is rigidly fixed to this peripheral part. The half-disc 70 is mounted freely in rotation on the central part 71 by means of a ball bearing.

In the variant represented for the third embodiment, provision is made for the central part 71 to be fixed to the bottom 66 of the casing 32A by a screw 68. Other fastening means can be envisaged, in particular welding or gluing. Thus, the rotor 64 is mounted on the inside of the bottom 66 before assembly of this assembly with the middle part of the case. According to a main characteristic of this third embodiment, the annular structure 72 carries four magnets 10B so as to allow them to undergo a radial elastic movement in order to be able to retract when these magnets arrive in angular zones respectively occupied by the magnets 20 of the mass of inertia, these occupied angular zones separating the free angular zones 78. Indeed, for a reason which will be explained later in more detail using the Figures 8A to 8H , the magnets 10B are arranged so that, in a neutral position in which they are not subjected to any radial elastic force, they penetrate at least partially into the free angular zones 78. However, provision is made for the magnets 10B to have a radius of the central axis which is greater than the radius at this central axis of the magnets 20 of the mechanical resonator, in order to allow the operation provided for this third embodiment described below.

In the advantageous variant shown, the cylindrical magnets 10B are inserted into rings fixed to the free ends of respective flexible blades 74. Each flexible blade 74 has a longitudinal axis in the form of an arc of a circle centered on the axis of rotation of the rotor 64 which coincides with the axis of oscillation of the mass of inertia. Thus, each flexible strip has great flexibility in the radial direction but relatively great rigidity in the angular/tangential direction. The flexible blades advantageously have a height greater than their width, so as to have sufficient axial rigidity to remain in the general plane of the magnets 20 of the mechanical resonator also during the interactions between the magnets 10B and 20 which can generate a certain axial magnetic force. due to manufacturing tolerances. Cavities 76 are provided in the annular structure to allow each first assembly, formed by a magnet 10B and the ring for fixing to the flexible blade 74, to undergo a radial movement over a sufficient distance to circumvent each second assembly, formed of a magnet 20 and the projecting part of the inertia mass serving to fix this magnet, when the rotor undergoes rotation.

In general, each magnet of the inertia mass is arranged so as to protrude from this inertia mass, so that the inertia mass has first and second free angular zones, respectively on both sides of this magnet, in which each magnet of the rotor can move. Then, each magnet of the rotor is arranged so as to be able to undergo a radial elastic movement relative to the axis of oscillation of the mechanical resonator, under the action of a radial magnetic force which is generated by the interaction in magnetic repulsion with a magnet of the inertia mass, when this magnet of the rotor is located close to the magnet concerned of the inertia mass. Preferably, the position of minimum mechanical energy of each first magnet of the rotor, considered at its center relative to the axis of rotation of the rotor, corresponds to a radial position of this first magnet situated in a range of radial positions, relative to the axis of rotation of the rotor which coincides with the axis of oscillation of the inertia mass, corresponding to the free angular zones located between the second magnets of the inertia mass. The radial elastic movement of each first magnet of the rotor is provided so that this first magnet can retract sufficiently, when it passes through the angular position of a second magnet of the mechanical resonator, to be able to pass from the first free angular zone to the second free angular zone relating to this second magnet. In an advantageous variant, each first magnet of the rotor is fixed to the end of a corresponding elastic blade which is arranged so as to have a mainly tangential longitudinal axis and a capacity for elastic deformation essentially in a radial direction, relative to the axis of oscillation of the mechanical resonator.

In a preferred variant, the radial elastic movement of each of the first magnets of the rotor, under the action of the radial magnetic force, is provided with a sufficient amplitude to avoid a shock between the rotor and the inertial mass of the mechanical resonator during of the passage of a first magnet by the angular position of a second magnet. In addition, the free angular zones 78, separating the angular zones occupied by the second magnets from the inertia mass, are provided so that the first magnets of the rotor do not abut against the inertia mass following a passage of these first magnets by the respective angular positions of the second magnets, so as not to disturb the oscillatory movement of the inertia mass at the resonance frequency F _Res following this passage.

With reference to Figures 8A to 8H which show a section of the rotor, at the level of the general plane in which the magnets 10B and 20 are arranged, and only the four magnets 20 (one of which has a variable angular position β) for the mechanical resonator 12B, a succession will be described instantaneous states of the electromechanical converter 6B during its operation. We consider a particular case where the rotor 64 rotates substantially at constant speed in the clockwise direction. To the Figure 8A , the magnets 10B of the rotor (one of which has an angular position a), carried by the respective flexible blades 74, have come sufficiently close to the magnets 20 of the mechanical resonator (variable angular distance θ between the magnets of the rotor and the corresponding magnets of the mechanical resonator) so that the magnetic repulsion force F _RM between them is significant and sufficient to drive the inertial mass 16B in rotation (represented here only by the four magnets 20). Already at the Figure 8A the benefit of the particular arrangement of the rotor and of the mechanical resonator in the third embodiment of the invention is understood. The force F _RM is essentially tangential, which has the consequence that substantially the whole of this force F _RM participates in the torque of magnetic force applied to the inertial mass. Continuing its rotation, the rotor drives the inertial mass with a force F _RM whose intensity increases given the reduction in the distances between the first magnets 10B and the corresponding second magnets 20. Thanks to the presence of the free angular zones 78 described above and the neutral radial position provided for each magnet 10B of the rotor , while the intensity of the force F _RM increases sharply, the force F _RM remains substantially tangential in the relative position of the snapshot shown in Figure 8B . Thus, a magnetic torque of relatively high intensity is applied to the inertial mass of the mechanical resonator.

The rotor continuing to turn clockwise, the radial component of the force has a value which becomes relatively large, this radial component acting on each magnet 10B so that each magnet 10B begins to undergo an elastic radial movement towards the outside thanks to to the flexible blade that carries it. The magnets 10B deviate from their circular trajectory so as to retract when these magnets pass by the respective angular positions of the magnets 20 of the inertia mass, as shown in the snapshot of the Figure 8C . While the magnets 10B of the rotor bypass the magnets 20 of the mechanical resonator under the action of the radial component of the magnetic repulsion force (also called 'radial magnetic force'), the inertial mass reaches a position of equilibrium of the tangential forces (tangential magnetic force and elastic restoring force of the mechanical resonator) and is thus at an extreme angular position (with zero angular velocity) corresponding to the snapshot of the Figure 8C . Thus, the mechanical resonator is excited/activated by the rotating rotor and it begins to oscillate substantially at its resonant frequency F _Res from this extreme angular position which determines an initial amplitude for this oscillation.

To the Figure 8D , while the magnets 10B and 20 are substantially radially aligned, the mass of inertia has begun a first alternation in the direction of rotation opposite to that of the rotor. Then each magnet 10B having passed the magnet 20 with which it is momentarily associated during this activation / excitation of the mechanical resonator, the magnetic repulsion force between them momentarily drives the mass of inertia counterclockwise from its first alternation, which again provides a supplement of energy to this mass of inertia and participates in the activation / excitation of the mechanical resonator. The Figure 8E shows the moment of the end of the first alternation. As the resonance frequency F _Res is provided relatively high, during the following alternation, the magnets 20 of the inertia mass rotate clockwise and again approach the magnets 10B of the rotor, as observed at the Figure 8F which shows the inertia mass again in an extreme angular position, although these magnets 10B of the rotor continue to rotate clockwise but at a speed less than the average speed of the magnets 20 of the inertia mass. It is noted that the magnetic repulsion force slows down the mechanical resonator and thus decreases its amplitude for this second alternation. However, as the magnetic force is a conservative force, most of the braking energy is given back to the mechanical resonator during the following alternation. The Figure 8G substantially shows the instant of the end of this following alternation. Then, in the specific case considered, the mechanical resonator still oscillates freely for two to three periods of oscillation before finding itself again in a situation similar to that of the Figure 8B where a strong magnetic coupling intervenes again between the rotor and the mass of inertia of the mechanical resonator, so as to maintain the oscillating movement of the latter or generate a new oscillation of the mechanical resonator. The Figure 8H still shows a snapshot at the end of the alternation following the snapshot of the Figure 8G , these two figures indicating the angular zone of free oscillation of the mechanical resonator. As already explained, when the magnets 20 of the inertia mass approach the magnet 10B of the rotor, the inertia mass generally undergoes magnetic braking which can momentarily stop the oscillation in progress, during the passage of the magnets of the rotor by the positions respective angular angles of the magnets of the mechanical resonator. Thus, it is observed that successive oscillations of the mechanical resonator are substantially generated by the rotating rotor via the magnetic force when it acts in the opposite direction to the direction of rotation of the rotor, i.e. after the magnets 10B of the rotor have passed, in s retracting, the magnets 20 of the mass of inertia, that is to say in time intervals according to the instantaneous state given to the Figure 8D .

Although the radial elastic constant of each elastic structure, formed by a magnet 10B and the flexible blade 74 which carries it, is selected so that it is sufficiently small so that the radial magnetic forces can move the magnets 10B out of the circular zone swept by the mass of inertia, in particular by the magnets 20 and their respective strappings during the passage of these magnets 10B by the angular positions of the magnets 20, it is provided that this radial elastic constant is however sufficiently large so that the radial oscillation frequency of each aforementioned elastic structure is higher than the resonance frequency F _Res of the mechanical resonator. For example, if the resonance frequency F _Res is equal to 20 Hz, it is advantageous for the radial oscillation frequency of each elastic structure of the rotor to be at least equal to twice F _Res , but preferably four to five times more large, in particular equal to approximately 100 Hz. This guarantees that the mechanical response of each elastic structure of the rotor is faster than the mechanical response of the mechanical resonator. Thus, the magnets 10B of the rotor are moved sufficiently quickly during the passage of these magnets through the angular positions of the magnets 20 so as to avoid collisions which would disturb the operation of the system provided.

Claims (20)

Portable object (2; 2A; 42; 62) comprising an electronic unit and an electrical power supply unit formed by an electromechanical converter (6; 6A; 6B), characterized in that the electromechanical converter comprises: - a rotor (8; 8A; 44; 64) capable of being driven in rotation by movements which the portable object may undergo, this rotor carrying at least one first permanent magnet (10; 10A; 10B); - a mechanical resonator (12; 12A; 12B) mounted on a support (4) and provided with an inertial mass (16; 46; 16B) capable of oscillating around an axis of oscillation (14) , at a resonance frequency (F _Res ) specific to this mechanical resonator; and - an electromagnetic system formed by at least one second permanent magnet (20) and at least one coil (24) which are respectively carried by the inertia mass and by said support or an element integral with this support and which are arranged in such a way that, when the mechanical resonator is at rest, at least part of the magnetic flux generated by the second permanent magnet passes through the coil so that, when the mechanical resonator is oscillating, an induced voltage (U _Ind ) is generated in this coil; the electromechanical converter being arranged in such a way that said at least one first permanent magnet and said at least one second permanent magnet can, during rotational driving of the rotor, interact magnetically so as to apply to the mass of inertia, momentarily or at times, a couple of magnetic force making it possible to excite the mechanical resonator, in order to generate at least one oscillation of this mechanical resonator substantially at its resonant frequency. Portable object according to claim 1, characterized in that the electromechanical converter (6; 6A; 6B) is arranged so that said torque of magnetic force applied to the mass of inertia (16; 46; 16B) makes it possible to generate, during said driving in rotation of the rotor, a plurality of successive momentary oscillations, at said resonance frequency and with an amplitude substantially equal to or greater than a minimum amplitude for which said induced voltage is substantially equal to a predetermined threshold voltage, this plurality of successive momentary oscillations occurring respectively following a plurality of successive excitations of the mechanical resonator by the rotating rotor. Portable object according to claim 1 or 2, characterized in that , when the mechanical resonator is at rest, the center of said second permanent magnet (20) and the center of said coil (24) have between them a non-zero angular offset relative to said axis of oscillation (14), preferably an angular offset which corresponds to an angular positioning of the center of the second permanent magnet substantially at a point of inflection of the curve of the magnetic flux, generated by said at least one second permanent magnet and passing through said coil, as a function of the relative angular position between said second permanent magnet and this coil relative to said axis of oscillation. Portable object according to any one of Claims 1 to 3, characterized in that the said mechanical resonator (12; 12A; 12B) is a resonator with flexible blades (26; 48). Portable object according to Claim 4, characterized in that the flexible blades are made of a piezoelectric material and each coated with two electrodes through which an electric current is generated when the mechanical resonator is activated, this electric current being supplied to an accumulator included in the power supply unit. Portable object according to any one of the preceding claims, characterized in that the said at least one first magnet permanent magnet (10; 10A; 10B) and said at least one second permanent magnet (20) are arranged such that their magnetic interaction is in repulsion. Portable object according to Claim 6, characterized in that the said at least one first permanent magnet (10; 10A; 10B) and the said at least one second permanent magnet (20) are located in the same general plane perpendicular to the said axis of oscillation of the mechanical resonator. Portable object according to Claim 7, characterized in that the said at least one first permanent magnet (10; 10A; 10B) and the said at least one second permanent magnet (20) have axes of magnetization substantially parallel to the said axis of oscillation (14 ). Portable object according to any one of the preceding claims, characterized in that the said resonant frequency is substantially equal to or greater than ten Hertz (F _Res >= 10 Hz), preferably between fifteen Hertz and thirty Hertz (15 Hz <= F _Res <= 30Hz). Portable object according to any one of the preceding claims, characterized in that the said mass of inertia (16) of the mechanical resonator (12) is formed by a ring supporting the said at least one second permanent magnet (20). Portable object (2; 2A) according to Claim 10 dependent on Claim 3, characterized in that the flexible blades (26) connect the said ring to a central element (28) which is fixed to the said support (4) of the mechanical resonator; and in that said rotor (8) is mounted free in rotation on a central part which is fixed to said central element, to said support or to an internal device which is fixed to this central element or to this support and located on the other side of the mass of inertia (16) relative to the rotor. Portable object (42) according to any one of Claims 1 to 10, characterized in that the said rotor is mounted free in rotation on a fixed structure (32) of the portable object (42) by means of a ball bearing or rollers (50), an inner ring (51) of said bearing being formed by the rotor (44) or secured to this rotor, while an outer ring (52) of this bearing is formed by said fixed structure or secured to this fixed structure (32). Portable object according to Claim 12, characterized in that a raceway of the said internal ring (51) is formed by an external lateral surface of the rotor (44), the said bearing (50) being arranged at the periphery of the rotor. Portable object (62) according to any one of Claims 1 to 10, characterized in that the rotor (64) is mounted free in rotation on a bottom (66) of a casing (32A) in which the electromechanical converter (6B) is housed. ). Portable object (62) according to Claim 6 or 7 or according to any one of Claims 8 to 14 dependent on Claim 5 or 6, characterized in that the said at least one second permanent magnet (20) is arranged so as to project from the mass of inertia (16B), so that this mass of inertia has first and second free angular zones (78), respectively on both sides of the second magnet, in which said at least one first permanent magnet ( 10B) of the rotor (64); and in that said first permanent magnet is arranged so as to be able to undergo a radial elastic movement, relative to said axis of oscillation, under the action of a radial magnetic force which is generated by the magnetic interaction with said second permanent magnet when the first permanent magnet is located close to the second permanent magnet, the position of minimum mechanical energy of the first permanent magnet, relative to said rotor, corresponding to a radial position of this first magnet located in a range of radial positions, relative to said axis of oscillation, corresponding to said first and second free angular zones, said radial elastic movement being provided so that the first permanent magnet can retract sufficiently, when the first permanent magnet passes through the angular position of the second permanent magnet, to be able to pass from the first free angular zone to the second free angular zone. Portable object according to Claim 15, characterized in that the said at least one first permanent magnet (10B) is fixed respectively to the end of at least one corresponding elastic blade (74) which is arranged in such a way as to present a longitudinal axis mainly tangential and thus a capacity for elastic deformation essentially in a radial direction, relative to said axis of oscillation. Portable object according to claim 15 or 16, characterized in that said radial elastic movement under the action of said radial magnetic force is provided with an amplitude sufficient to avoid a shock between the rotor (64) and the inertial mass (16B ) of the mechanical resonator (12B) during the passage of the first permanent magnet (10B) by the angular position of the second permanent magnet (20). Portable object according to any one of the preceding claims, characterized in that the rotor has an annular part which laterally surrounds the mass of inertia of the mechanical resonator. Portable object according to any one of the preceding claims, characterized in that the rotor is configured in such a way as to present an imbalance to favor its rotation during the said movements which the portable object may undergo. Portable object according to any one of the preceding claims, characterized in that this portable object is portable on the wrist of a user, in particular a wristwatch.

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