EP3299908B1 - Self-winding watch - Google Patents

Description

Field of the invention

The present invention relates to the technical field of automatic winding devices. More specifically, the invention relates to a device for raising a mainspring, for example a timepiece, by means of the ambient light energy by means of a photovoltaic cell.

Background of the invention

Watch movements require motor means to provide energy to a set of mechanisms for providing at least one time indication.

For mechanical watches, it is a mainspring or barrel spring that arrests under the action of a winder operated manually or through the movements of the carrier that are transmitted to the mainspring via a connected oscillating mass to a gear reduction gear. The invention relates to self-winding watch movements using an oscillating mass.

The oscillating mass may, depending on the mechanism with which it is associated, either arm the spring using energy that the mass produces only in one direction of rotation, or in both directions of rotation.

Generally, the oscillating mass is rotatably mounted on an axis with an unbalance. When this oscillating mass moves in a first direction of rotation, said arming direction, it drives a gear train that arms a barrel spring. When the displacement of the mass is in the other direction said free direction, this oscillating mass no longer acts on the transmission train of the spring, it is free in rotation. In the absence of movement of the wearer, the mass returns to its equilibrium point thanks to the unbalance after several oscillations which allowed him to arm the spring each time it moved in the direction of the arming.

The movement of the arm of the watch wearer can cause rotation in one or the other direction of rotation of the mass so as to recover the energy.

There are also known automatic winding devices comprising a motor for moving the oscillating mass and for raising the mainspring. Such a device is described in the document EP 0 320 754 . However the torque required for the winding of the spring is quite high which implies a powerful motor, so more bulky, or a large gear ratio also bulky.

Summary of the invention

The invention particularly aims to overcome the various disadvantages of these known techniques.

More specifically, an object of the invention is to provide an automatic winding device that reduces the torque required to raise the mainspring.

Another object of the invention is to wind the watch when it is not worn and thus keep it in operation, as well as to maintain the function of the oscillating mass when it is worn.

Yet another object of the invention is to provide a "plug-and-play" device, the invention making it possible to replace the oscillating mass of an existing movement without major changes.

• une masse oscillante pivotant autour d'un axe;
• un rouage démultiplicatif coopérant avec la masse oscillante pour transmettre le couple au barillet ;
• une unité de stockage d'énergie électrique;
• une cellule photovoltaïque agencée pour recevoir la lumière ambiante et charger l'unité de stockage d'énergie électrique;
• un circuit de commande connecté aux bornes de ladite unité de stockage d'énergie électrique; et
• des moyens d'entrainement connectés au circuit et couplé à la masse oscillante pour la déplacer.

These objectives, as well as others which will appear more clearly later, are achieved according to the invention with the aid of a self-winding watch comprising a movement associated with a device for winding a mainspring comprising:

• an oscillating mass pivoting about an axis;
• a gear train cooperating with the oscillating mass to transmit torque to the barrel;
• an electrical energy storage unit;
• a photovoltaic cell arranged to receive ambient light and charge the electrical energy storage unit;
• a control circuit connected across said power storage unit; and
• driving means connected to the circuit and coupled to the oscillating mass to move it.

According to the invention, the electrical energy storage unit, the control circuit and the drive means are preferably integrated in the oscillating mass.

• les moyens d'entrainement comprennent au moins un micromoteur agencé pour coopérer avec la montre de manière à déplacer la masse oscillante autour de l'axe ;
• les moyens d'entrainement comprennent un anneau denté, solidaire de la montre, et coopérant avec les moyens d'entrainement ;
• les moyens d'entrainement comprennent un axe de transmission supportant un pignon engrenant avec ledit anneau denté ;
• l'anneau denté a un diamètre identique ou légèrement supérieur au diamètre du mouvement ;
• les moyens d'entrainement comprennent une roue multipolaire agencée pour coopérer avec la montre de manière à déplacer la masse oscillante autour de l'axe ;
• les moyens d'entrainement comprennent un anneau denté en matériau ferromagnétique, solidaire de la montre, et coopérant avec ladite roue multipolaire ;
• l'unité de stockage de l'énergie comprend un supercondensateur, un condensateur, une inductance ou une batterie ;
• la cellule photovoltaïque est montée préférentiellement sur la face visible de la masse oscillante, mais peut aussi être montée sur l'autre face pour un mouvement squelette, par exemple ;
• la cellule solaire est assemblée sur la montre.

According to other advantageous variants of the invention:

• the drive means comprise at least one micromotor arranged to cooperate with the watch so as to move the oscillating mass about the axis;
• the drive means comprise a toothed ring, integral with the watch, and cooperating with the drive means;
• the drive means comprise a transmission shaft supporting a pinion meshing with said toothed ring;
• the toothed ring has a diameter identical to or slightly greater than the diameter of the movement;
• the drive means comprise a multipolar wheel arranged to cooperate with the watch so as to move the oscillating mass about the axis;
• the drive means comprise a toothed ring of ferromagnetic material, integral with the watch, and cooperating with said multipolar wheel;
• the energy storage unit comprises a supercapacitor, a capacitor, an inductor or a battery;
• the photovoltaic cell is mounted preferentially on the visible face of the oscillating mass, but can also be mounted on the other face for a skeleton movement, for example;
• the solar cell is assembled on the watch.

The invention also relates and in particular all timepieces according to the invention.

Brief description of the drawings

• la figure 1 est une vue schématique d'un dispositif de remontage équipant une montre conforme à l'invention selon un premier mode de réalisation ;
• la figure 2 est une vue schématique d'un dispositif de remontage équipant une montre conforme à l'invention selon un deuxième mode de réalisation.

Other features and advantages of the invention will appear more clearly on reading the following description of a particular embodiment of the invention, given as a simple illustrative and nonlimiting example, and the appended figures, among which: :

• the figure 1 is a schematic view of a winding device equipping a watch according to the invention according to a first embodiment;
• the figure 2 is a schematic view of a winding device equipping a watch according to the invention according to a second embodiment.

Detailed Description of the Preferred Embodiments

An exemplary embodiment of a watch according to the invention will be described in the context of a particularly advantageous application shown in FIG. figure 1 . The winding device 1 is associated with a conventional mechanical watch movement, the assembly forming an automatic watch in which the winding energy, instead of or in addition to being produced by the movements of the wearer's arm, is provided by the ambient light. The watch will be reassembled, when worn or not, as long as it receives light energy.

The winding device 1 uses, for transforming the energy of the natural or artificial ambient light into electrical energy, a photovoltaic cell 3, the cell being able to be placed on the oscillating mass 2 of the watch so as to receive light when the watch is not worn or dial side when worn, the skilled person could also consider a combination of both. The photovoltaic cell 3 may comprise a plurality of elementary cells, for example of the heterojunction type, connected in series and / or in parallel to supply current. This current is likely to vary in large proportions, depending on whether the watch is in dim light or in direct sunlight.

An electrical energy storage unit 4 is connected to the photovoltaic cell 3 in order to store the energy produced by this cell. The electrical energy storage unit 4 may be in the form of a rechargeable battery, a supercapacitor, or in the form of a simple ceramic capacitor or an inductor. The photovoltaic cell 3 and the electrical energy storage unit 4 are then connected to the control circuit 5, which supplies drive pulses to drive means 6 at its output.

According to a first embodiment, the drive means 6 comprise a brushless micromotor, or a Lavet stepper motor well known in the watch industry, or an axial flow motor for example, or an engine. of piezoelectric type, the micromotor comprising a transmission shaft at the end of which is mounted a pinion 61 arranged to cooperate with a toothed ring 60, or a toothed sector, formed in the watch or assembled on the latter. In this way, when the micromotor is active, it moves the oscillating mass 2 about the axis A, which has the effect of raising the mainspring by means of a gear train 7 commonly used in mechanical watches with automatic winding. Such a solution has the advantage of requiring a much smaller torque than the known devices thanks to the gear ratio offered by the gear 7.

According to a second embodiment presented in figure 2 , the drive means 6 comprise a magnetic coupling between a wheel 62, composed of magnets or a monobloc magnet, driven by the micromotor and a ferromagnetic wheel 63 secured to the watch, the magnets of the wheel 62 being attracted by the notches of the toothed wheel 63 which causes the oscillating mass 2 without contact.

The force of the magnetic coupling is chosen so as to drive the oscillating mass 2 to a certain torque lower than the maximum torque of the mainspring. This avoids stressing the spring, and let the oscillating mass 2 do its work of reassembly to the worn. In addition, the absence of contact avoids significant stress on the gear teeth in case of shock due to the high inertia of the oscillating mass 2.

Assuming the illuminated photovoltaic cell 3 and the electrical energy storage unit 4 initially discharged, the current supplied by the photovoltaic cell 3 has the effect of charging the electrical storage unit 4 and increasing its voltage or current. After a certain time, the voltage or the current at the terminals of the storage unit 4 reaching the value corresponding to a reference value, the circuit 5 behaves like a switch, connecting the terminals of the storage unit 4 at the terminals of the drive means 6 during a predetermined time interval. The storage unit 4 then provides a well defined drive pulse to the drive means 6 to advance one or more steps.

Advantageously, the transmission can be controlled according to the position of the watch. In the case where the watch is in a horizontal or flat position, the effect of the gravity is negligible and the oscillating weight 2 is rotated continuously. And in the case where the watch is in the vertical position or on the edge, the oscillating mass 2 is raised by a certain angle, for example at 90 °, before being released so that the mass 2 oscillates under the effect of gravity until it returns to equilibrium. Once the equilibrium position is reached, the cycle starts again. For example, under normal lighting conditions, the micromotor can perform about twenty-five steps per second. Generally, five turns of the barrel are enough to raise the spring, which corresponds to five hundred turns of the oscillating mass, that is to say two hundred and fifty miles from the micromotor, or else 500 steps per revolution of the oscillating mass. It would take approximately three hours to raise the mainspring.

According to another particular embodiment of the invention, the watch has deliberately shaded areas so as to deprive the photovoltaic cell 3 of light periodically, and thus generate pulses necessary for feeding the training means 6. Such variant would for example make it possible to overcome the electronic circuit 5.

According to a variant of the invention, the electronic circuit 5 comprises means for measuring the quantity of energy supplied and / or the current profile necessary to supply the motor and / or the number of steps taken, in order to detect the moment or the barrel is completely reassembled. This moment detected, the electronic circuit 5 stops sending pulses to the micromotor so as not to wear the mainspring.

The watch movement which is associated with the winding device 1 comprises, for its part, a mainspring, a gear driven by the spring, an oscillator oscillated by the gear train to stabilize the rotation of the different moving parts, and a display of the time controlled by this wheel. The barrel spring is finally coupled to the gear train 7 to be armed at each step performed by the drive means 6. The movement and the winding device thus constitute the heart of an autonomous automatic watch not requiring for operate only a sufficient ambient light, typically about 150/200 Lux.

According to another variant of the invention, the oscillating mass 2 comprises coils for forming itself the rotor of an engine. The stator is formed by a ring comprising several magnets, which allows the oscillating mass 2 to move itself without a motor, the electronic circuit 5 feeding the coils to create a magnetic field.

Thanks to these different aspects of the invention, there is an automatic watch energy-autonomous, indicating the time permanently, and which does not require a particular action for the winding of the mainspring, even when the watch is not worn.

Of course, the present invention is not limited to the illustrated example and is susceptible of various variations and modifications that will occur to those skilled in the art.

Claims (10)

1. Self-winding watch comprising a movement connected to a winding device (1) of a barrel spring comprising:

   • an oscillating weight (2) pivoting around an axis A;

   • a reduction wheel train (7) cooperating with the oscillating weight (2) to transmit the torque to the barrel;

   • at least one storage unit for electrical energy (4);

   • at least one photovoltaic cell (3) arranged to receive the ambient light and charge the electrical energy storage unit (4);

   • a control circuit (5) connected to the terminals of the storage unit (4); and

   • drive means (6) connected to the control circuit (5) and coupled to the oscillating weight (2) to displace it,

   characterised in that the energy storage unit (4), the control circuit (5) and the drive means (6) are integrated in the oscillating weight (2).
2. Watch according to claim 1, in which the drive means (6) comprise at least one micromotor arranged to cooperate with the watch in order to displace the oscillating weight (2) around the axis A.
3. Watch according to claim 1 or 2, in which the drive means (6) comprise a toothed ring (60) integral to the watch that cooperates with said at least one micromotor.
4. Watch according to claim 2 or 3, in which said at least one micromotor comprises a transmission shaft that supports a pinion (61) meshing with said toothed ring (60).
5. Watch according to claim 3 or 4, in which said toothed ring (60) has a diameter that is identical to or slightly larger than the diameter of the movement.
6. Watch according to claim 1, in which the drive means (6) comprise a multipolar wheel (62) arranged to cooperate with the watch in order to displace the oscillating weight (2) around the axis A.
7. Watch according to claim 6, in which the drive means (6) comprise a toothed ring (63) made from ferromagnetic material that is integral to the watch and cooperates with said multipolar wheel (62).
8. Watch according to any one of claims 1 to 7, in which the energy storage unit (4) comprises a supercapacitor, a capacitor, an inductor or a battery.
9. Watch according to any one of claims 1 to 8, in which the photovoltaic cell (3) is mounted on the oscillating weight (2).
10. Watch according to any one of claims 1 to 8, in which the solar cell (3) is assembled on the watch.

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