Timepiece comprising a device for amplifying vibrations

Abstract

The present invention relates to a timepiece (1) comprising a case (2) containing a movement, at least one vibration-generating device intended to produce at least one sound, at least one vibration-amplifying device (16) for amplifying the vibrations generated by the vibration-generating device, the vibration-amplifying device (16) comprising a lever (20) connected to a support (22) by a hinge about a single axis of rotation and arranged to be actuated by a transmission member (28) cooperating with the vibration-generating device in order to transmit the vibrations to the lever (20). The vibration-amplifying device (16) comprises at least one plate (18) arranged to cooperate with the lever in order to be moved according to a vibration movement, the plate (18) being housed in the case (2) in such a way as to form a free space around the periphery of the plate (18) over at least 70%, and preferably at least 80%, of the perimeter of the plate (18).

Description

[0001] The present invention relates to a timepiece comprising a case containing a movement, at least one vibration generating device intended to produce at least one sound, at least one device for amplifying the vibrations generated by said vibration generating device, said vibration amplification device comprising a lever linked to a support by an articulation along a single axis of rotation, said lever being arranged to be actuated by a transmission member cooperating with the vibration generating device to transmit the vibrations to said lever in order to pivot it relative to its support according to a vibration movement around its axis of rotation.

[0002] Such a timepiece is, for example, a striking watch (such as a minute repeater, grande sonnerie, petite sonnerie, alarm clock) for which the vibration-generating device is, for example, a gong arranged to be struck by a hammer when the striking mechanism is engaged to generate vibrations in order to produce a sound. The gong is typically in the form of a wire wound around the movement. The gong is mounted integral with the frame (assembly of the plate and bridges) of the watch by means of a heel or gong holder, in order to transmit the vibrations of the gong to the entire watch (frame, movement, exterior components). Thus, the vibrations of the gong are transmitted to the wearer of the watch with maximum intensity.

[0003] Since sound transmission is achieved by vibrating the entire watch, it has been proposed to stiffen the various elements of the watch in order to promote the vibration of these elements and thus improve said sound transmission.

[0004] This solution yielded satisfactory results in terms of sound transmission quality but generated other problems, such as the appearance of unwanted sounds. Indeed, the greater the sound intensity, the more the movement vibrates, and the more noise the various components of the movement generate as they vibrate. This set of vibrations generates unwanted noise.

[0005] One solution to amplify the sound is to increase the force of the hammer striking its timbre. This resulted in a sound gain, but the sound quality was degraded by background noise.

[0006] The striking watch described in application EP 3 644 133 proposes to solve this problem by using the waterproof sound transmission membrane implemented to seal the case in order to protect the movement and the striking device from moisture and dirt. The membrane can for example be held by an O-ring seal. Said waterproof sound transmission membrane is brought into contact with a sound transmission bridge secured to a movable part with a single degree of freedom in rotation, said movable part being associated with a heel carrying a gong. Thus, the sound transmission bridge transmits vibrations of the heel, generated by those of the gong, when struck by its hammer, directly to the waterproof membrane in an optimal vibration direction to vibrate said waterproof membrane, which increases the volume of the sound perceptible outside the watch.

[0007] However, since the waterproof membrane is by definition fixed around its perimeter to an element of the box to ensure sealing, said membrane, when it receives the vibrations of the sound transmission bridge, deforms by bulging in one direction then in the other in its first vibration mode. These deformations generate significant damping, which worsens the sound quality. In addition, the contact between the lever and the membrane can be achieved by pre-stressing the lever on the membrane, which amplifies the damping. In the case of a fixed contact, the membrane would deform in a non-symmetrical way, which would add stresses.

[0008] The present invention aims to remedy these drawbacks by proposing a timepiece comprising a device for generating vibrations intended to produce at least one sound and a device for amplifying these vibrations making it possible to amplify said generated sound significantly, while preserving the quality of the sound.

[0009] To this end, the present invention relates to a timepiece comprising a case containing a movement, at least one vibration generating device intended to produce at least one sound, at least one device for amplifying the vibrations generated by said vibration generating device, said vibration amplification device comprising a lever linked to a support by an articulation along a single axis of rotation, said lever being arranged to be actuated by a transmission member cooperating with the vibration generating device to transmit the vibrations to said lever in order to pivot it relative to its support according to a vibration movement around its axis of rotation.

[0010] According to the invention, the vibration amplification device comprises at least one plate arranged to cooperate with the lever in order to be moved in a vibration movement, said plate being housed in the box so as to form on the periphery of said plate a free space over at least 70%, preferably at least 80%, or even 100% of its perimeter.

[0011] Thus, when the plate receives the vibrations transmitted by the lever and enters into its vibration movement, said plate, being substantially free to move, undergoes practically no deformation and acts like a piston on the air. Consequently, the sound produced by the timbre is amplified significantly while maintaining high quality.

[0012] According to a first embodiment, the plate is integral with the lever and moves with the lever in a rotational movement around the axis of rotation of said lever.

[0013] According to a first variant, the plate is fixed to the lever by its main surface, so that 100% of the perimeter of the plate is free.

[0014] According to another variant, the plate is fixed to the lever by its peripheral edge, so that the amplification device will not be visible to a user.

[0015] According to a second embodiment, the plate is arranged to cooperate with the lever so as to be driven by a linear translation movement along an axis perpendicular to the plate.

[0016] Advantageously, the plate cooperates with means for guiding in linear translation along said axis perpendicular to the plate in order to guarantee linear movement.

[0017] According to a first variant, said guide means comprise at least three flexible fasteners distributed regularly around the periphery of the plate and connecting said plate to a connecting support.

[0018] Thus, the first vibration mode of the plate is a linear displacement of the entire plate by bending of said attachments.

[0019] According to another variant, the guide means consist of a bracket comprising a central plate secured to the plate and at least three elastic arms connecting the central plate to the box.

[0020] Such a jib advantageously makes it possible to generate a linear movement of the entire plate, 100% of the perimeter of the plate being free to move.

[0021] Other characteristics and advantages of the present invention will appear on reading the following detailed description of different embodiments of the invention, given as non-limiting examples, and made with reference to the appended drawings in which: there figure 1 is a view of the bottom of a timepiece according to a first variant of a first embodiment of the invention; the figure 2 is a perspective view of a timepiece according to the invention; figure 3 is a schematic sectional view of the first variant of the first embodiment of the invention; figure 4 is a perspective view of a lever used in the invention; figure 5 is a schematic view from the bottom side of another variant of the first embodiment of the invention; figure 6 is a schematic view from the bottom side of another variant of the first embodiment of the invention; figure 7 is a schematic sectional view of another variant of the first embodiment of the invention; figure 8 is a view of a plate according to a first variant of a second embodiment of the invention; the figure 9 is a schematic sectional view of the plate of the figure 8 in its first vibrational mode; figure 10 is a perspective and sectional view, from the bottom side, of a second variant of the second embodiment of the invention; figure 11 is a perspective view from inside the box of the figure 10 ; there figure 12 is a sectional view of the stem plate and the lever according to the second variant of the second embodiment of the invention; figure 13 is a perspective view of another embodiment of cooperation of the transmission member and the lever with the vibration generating device; and the figure 14 is a sectional view of the lever of the figure 4 .

[0022] The present invention relates to a timepiece comprising a case containing a movement, at least one vibration generating device intended to produce at least one sound, at least one device for amplifying the vibrations generated by said vibration generating device, said vibration amplification device comprising a lever connected to a support by an articulation according to a single degree of freedom in rotation, that is to say according to a single axis of rotation, said lever being arranged to be furthermore actuated by a transmission member not directly connected to said support and cooperating with the vibration generating device to transmit the vibrations to said lever in order to pivot it relative to its support according to a vibration movement around its axis of rotation,the vibration amplification device comprising at least one plate arranged to cooperate with the lever and receive the vibrations amplified by the lever in order to be moved in a vibration movement to exert pressure on the air in order to generate a sound from the inside to the outside of the timepiece, said plate being housed in the case so as to form on the periphery of said plate a free space over at least 70%, preferably at least 80%, more preferably at least 90%, or even 100% depending on the variants, of the perimeter of said plate, free space through which a certain air flow can pass.,

[0023] The vibration movement of the plate is amplified because the actuation point of the lever, the pivot point of the lever on the support and the connection point of the lever with the plate are positioned so that a displacement of the transmission member generated by the vibration of said transmission member in connection with the vibration generating device is transmitted to the plate via the lever, actuated by said transmission member, in a manner amplified by the lever arm effect of said lever. Thus, the amplified vibrational displacement of the plate generates an amplified sound.

[0024] In addition, the plate is fixed to the lever by a defined area, as small as possible, the rest of the plate being in the void, and having no contact with any other element of the timepiece.

[0025] The plate is as large as possible to move, during its vibratory movement, as much air as possible, while leaving a free space around said plate through which air can pass in order to reduce the forces on the plate and to dampen the vibrations as little as possible, so as not to worsen the quality of the amplified sound. Thus the plate is free to move, without deformation, in order to vibrate with the least damping possible, to have a powerful and clean sound.

[0026] The aim is to make the plate resonate with the vibration generating device, so that the propagated sound lasts as long as possible.

[0027] The plate can be circular or polygonal, depending on the shape of the box.

[0028] The plate, in the rest state, may be substantially flat or be domed in the shape of a shell, with a radius of curvature greater than the diameter of the watch, preferably greater than 30 mm, more preferably greater than 50 mm, and preferably between 50 mm and 500 mm. The concave side of the domed plate is advantageously directed towards the outside of the case, on the sound outlet side, the lever being linked to the convex side of the plate. The reverse configuration is however possible.

[0029] In this description, the term "plate" generally designates a flat or curved plate.

[0030] The plate is preferably made of a very light and rigid material in order to have a high dynamic response and not to deform, in its center but also on its free periphery, during its movement, as defined above.

[0031] Advantageously, the plate has a stiffness such that said plate has over a frequency interval of at least two octaves, and for example between 1 kHz and 4 kHz, a piston behavior such that the average displacement of the points of the main surface of the plate is greater than 50%, preferably greater than 75%, of the maximum displacement, i.e. the displacement of the point of the main surface of the plate which moves the most, so that the plate used in the present invention has substantially no deformation over its entire surface, in particular at low frequency.

[0032] For comparison, a waterproof membrane traditionally used in a bell, the edges of which are fixed to the case, deforms in a parabolic motion so that the average displacement of the points on the surface of the membrane is less than 50% of the maximum displacement.

[0033] The plate is preferably made of a transparent material. For example, it can be sapphire, mineral glass, plexiglass, diamond, composite materials, cellulose, or composite glass such as safety glass, etc.

[0034] Preferably, the plate is made of mineral glass, sapphire or diamond.

[0035] When the plate is used as a dial, as will be described hereinafter, the plate is preferably made of a non-transparent material, such as silicon, titanium, carbon or aluminum.

[0036] The plate must be as rigid and light as possible. For this, its thickness is less than 1 mm, preferably less than or equal to 0.5 mm, preferably less than or equal to 0.15 mm, and more preferably less than or equal to 0.1 mm.

[0037] The vibration generating device may be a striking gong arranged to be struck by a striking hammer, said striking gong being integral with the transmission member, and said transmission member being integral with the lever.

[0038] In another variant, the vibration generating device may be a rotating disc comprising an engraved groove arranged to generate a sound, the transmission member being a needle secured to the lever and arranged to follow the groove on the disc.

[0039] In another variant, the vibration generating device may be a music box comprising vibrating blades fixed by studs, the transmission member being integral with said studs and the lever.

[0040] In the following description, the vibration generating device is a striking gong struck by a striking hammer so that the timepiece comprises a striking mechanism for indicating the time (minute repeater, grand sonnerie, petite sonnerie) or for striking at a predefined time (alarm). The timepiece is preferably a watch, and more preferably a wristwatch intended to be worn by a user on his wrist.

[0041] Unless specifically indicated, the remainder of the description of the invention, in particular of the vibration amplification device, will apply in the same way to a watch comprising a music box or a rotating disc read by a hand, one end of which is secured to the lever and the other end is arranged to read the groove engraved on the rotating disc. The hand is mounted on the lever, for example by embedding or brazing, for example by being inserted into an orifice provided for this purpose on the lever.

[0042] In reference to the figures 1 And 2, the watch 1 comprises a case 2 having a caseband 3, a back 4, a bezel 5, and a first glass 6. The back 4 is annular and its central opening is closed by a second glass 7. The bezel and the caseband may be two different pieces, or form a single single piece. Similarly, the back and the caseband may be two different pieces or form a single single piece.

[0043] In the following description, the vibration amplification device and the plate are arranged to generate sounds through the back of the watch. It is obvious that the vibration amplification device and the plate can be arranged in a similar manner but in reverse to generate sounds on the dial side of the watch.

[0044] With more specific reference to the figure 1 , the watch 1 also comprises a movement and a striking mechanism 9 constituting the device generating vibrations intended to produce at least one sound. The movement and the striking mechanism 9 are housed in the middle 3 of the case 2, mounted on a frame 10 (plate and bridges). The striking mechanism 9 comprises, in a known manner, hammers 12 arranged to strike the striking gong 14, here in the form of a wire gong or spring blade wound around the movement.

[0045] In order to amplify the sounds produced by the gong 14, a device 16 is provided for amplifying the vibrations generated by the gong 14, comprising a lever 20 linked to a support 22 by an articulation along a single axis of rotation 21, so that said lever is mounted tilting or pivoting on said support 22 around said axis of rotation 21, as well as a plate 18 (cf. figures 3 and following) arranged to receive said amplified vibrations and generate an amplified sound from the inside to the outside of the watch. When the sound is transmitted on the back side, the plate 18 is mounted on the back 4 side, being positioned parallel to said back 4 at least when it is in a rest position, not subject to vibrations, between the movement and the second crystal 7. It will be mounted inside the bezel 5, being positioned parallel to said bezel 5 at least when it is in its rest position, between the movement and the first crystal 6 when the sound will be transmitted on the dial side.

[0046] In a particularly preferred manner, the lever 20 and the plate 18 are arranged relative to each other such that the axis of rotation 21 of the lever 20 is parallel to the plane of the main surfaces of the plate 18 at least when said plate 18 is in its rest position. The other degrees of freedom of the lever 20 are considered negligible compared to its degree of freedom in rotation about its axis of rotation 21.

[0047] In reference to the figures 3 , 7 , 10 et 11 , the lever 20 is arranged to be actuated by a transmission member 28 cooperating with the gong 14 to transmit the vibrations to the lever 20. The transmission member 28 is positioned on the same side as the lever 20 relative to the articulation 21 of said lever 20 with the support 22 so that the transmission member 28 is not directly connected to the support 22 on which the lever 20 is mounted articulated. The transmission member 28 is preferably integral with the lever 20. The transmission member 28 may consist for example of a heel or gong holder integral with the lever 20 and in which the gong 14 is mounted, for example by embedding, locking by a screw or brazing. For this purpose, the transmission member 28 comprises for example an orifice 30 into which the gong 14 is introduced. Thus, the gong 14 is integral with the lever 20 and is not fixed, via a heel, to the frame of the watch.The transmission member 28 can be attached or made of a single piece with the lever 20, as shown in the . figures 3 , 7 , 10 et 11 . When the transmission member 28 is in one piece with the lever 20, the stamp is assembled directly to the lever, by welding for example.

[0048] According to another variant not shown, the transmission member 28 can be in one piece with the lever 20, being arranged to form a clamp in which the gong 14 is held. This arrangement makes it possible to limit the loss of vibration as much as possible.

[0049] According to another variant shown on the figure 13 , the transmission member 28, which is advantageously made of a single piece with the lever 20, does not carry the gong 14 and does not constitute the heel of the gong 14, but is arranged to cooperate with the gong 14 by contact in order to be able to capture the vibrations of the gong 14 and actuate the lever 20 accordingly to transmit the captured vibrations to the plate 18. The transmission member 28 can cooperate with the gong 14 by simple contact or have the form of a clamp. The gong 14 is then fixed on a heel 64 preferably fixed on an element of the case, such as the caseband or the back, or possibly on an element of the movement. Preferably, the capture point of the transmission member 28 on the gong 14 is relatively close to the embedding zone at the heel.In this configuration, the point of vibration capture by the lever 20 is advantageously positioned on the stamp 14 and not on its heel, in order to have low damping of the vibrations, the amplitude of the signal being greater.

[0050] Advantageously, the material of the lever 20, the gong 14 and the transmission member 28 is chosen to produce these three elements in a single piece. This material is chosen as transporting the vibrations, for example steel or magnesium.

[0051] Advantageously, the vibration amplification device, and more particularly the support 22 of the lever 20, is isolated from the movement, from the striking mechanism 9 and from the frame 10. For this purpose, the support 22 of the lever 20 can be mounted on an element of the casing and more particularly on the bezel 5 if the sound is transmitted on the dial side, on the back 4, if the sound is transmitted via the back. When the striking gong 14 is embedded in the transmission member 28 secured to the lever 20, said gong 14 is not fixed to the frame via a heel, as is traditional, but appears to float around the movement.

[0052] The support 22 of the lever 20 can also be mounted on the movement, or even on the caseband 3, but advantageously by means of an insulating element, such as a polymer, in order to guarantee the isolation of the support 22 from the movement, the caseband and the frame.

[0053] When the support 22 of the lever 20 is mounted on the bezel 5, respectively on the back 4, said bezel 5, respectively said back 4 can be assembled directly on the caseband 3 in a conventional manner. However, in order to ensure that no parasitic vibration will reach the caseband 3 and therefore the movement, said bezel 5, respectively said back 4 is advantageously assembled on the caseband 3 by means of an insulating element, such as a polymer.

[0054] The plate 18 also being isolated from the movement and the striking mechanism 9, the vibration amplification device and the plate are isolated from the movement and the frame so that all the vibrations of the gong recovered by the lever 20 are directed and transmitted to the plate 18, without transmission to the movement, the frame or the case.

[0055] The lever 20 is preferably made of a very light and very rigid material. For example, the lever 20 can be made of steel, titanium, aluminum, magnesium, composite material, carbon, glass, sapphire and ceramic.

[0056] Advantageously, the lever 20 can be mounted articulated or pivoted on the support 22 by means of a single central flexible ball joint 24 as shown in the figure 1 . The flexible ball joint (more precisely the flexible pivot since it is an articulation along the single axis of rotation 21) allows, if necessary, to modify the direction of the vibrations. In particular, in the case of the striking gong, the latter tends to vibrate radially, in the direction of the hammer strike. Preferably, the position of the flexible ball joint 24 (i.e. the flexible pivot) of the lever 20 allows the direction of the radial vibrations of the gong to be modified by 90° to transform them into a movement of vibrations perpendicular to the plane defined by the bottom for example, i.e. the plane defined by the plate 18 when it is in the rest position, by means of the pivoting of said lever 20. Preferably, the flexible ball joint 24 (i.e. the flexible pivot) is positioned on the center of mass of the gong / lever / plate assembly.

[0057] As shown in the figure 4 , the lever 20 can be mounted articulated or pivoting on the support 20 by means of two flexible ball joints or pivots 24, arranged on the outside as far apart as possible from each other, in order to ensure better guidance of the plate 18 by reducing unwanted movements, in particular lateral movements.

[0058] Advantageously, the thickness e of the wall of the flexible ball joint 24 (i.e. of the flexible pivot) as shown in the figures 4 And 14can be modified in order to vary the vibration frequency of the lever 20 and the plate 18, and consequently the length of the sound generated. Preferably, the thickness e is chosen so that the vibration frequency of the lever 20 / plate 18 assembly is a multiple of the natural frequency of the gong 14 so that the lever / plate system enters into resonance with the gong, which will reduce the damping of the sound and therefore increase the length of the sound. When several gongs are used, an average value of the frequencies can be chosen as the frequency.

[0059] The thickness of the lever 20 can be chosen to be greater on the side of the axis of rotation 21 and to decrease in the direction of the plate 18, in order to maintain as much rigidity as possible and to reduce the inertia of the system.

[0060] It is also possible to mount the articulated or pivoting lever 20 on the support 22 by means of a pin mounted transversely on the support 22 and constituting the axis of rotation 21 of the lever 20. The support 22 is then constrained by a spring.

[0061] More specifically, the lever 20 comprises a first end 20a mounted articulated or pivoting on the support 22 and integral with the transmission member 28 and a second end 20b arranged to cooperate with the plate 18. The length of the lever 20, that is to say the distance between its first end 20a and its second end 20b, varies according to the variants of the invention.

[0062] According to a first embodiment of the invention, the plate 18 is integral with the lever 20, being fixed to said lever 20 by a defined zone, and moves with said lever 20 according to a vibratory rotational movement around the axis of rotation 21 of said lever 20, that is to say according to the same degree of freedom in rotation as the lever 20.

[0063] The plate 18 comprises two main surfaces 18a, 18b parallel to the dial and to the back when said plate 18 is in its rest position, that is to say a face 18a on the back side and a face 18b on the dial side, said main surfaces 18a, 18b being joined by a lateral edge 18c.

[0064] According to a first variant of this first embodiment shown in the figure 3 , the plate 18 is fixed to the lever 20 by one of its main surfaces, here by its face 18b on the dial side, so that 100% of the perimeter of the plate 18 is free. The fixing of the lever 20 to the plate 18 can be done for example by means of a screw 32 screwed into a hole provided on the plate 18 and into a hole 34 (cf. figure 4 ) provided at the second end 20b of the lever 20, or by gluing, welding, etc.

[0065] The volume of air displaced will be greater on the area of ​​the plate 18 furthest from the axis of rotation 21, represented by the arrows of the figure 3 .

[0066] Furthermore, since the plate 18 moves parallel to the lever 20, it is possible to have extremely little or no play between the plate and the lever, which makes it possible to reduce the size.

[0067] According to another variant shown on the figure 5 , the plate 18 can be cut to include a radial opening 36 in which the lever 20 is housed, without contact with the plate 18 on either side of the radial opening 36. This makes it possible to integrate the lever 20 into said radial opening 36, by passing it into said radial opening 36, which makes it possible to reduce the size.

[0068] It is also possible to provide for opening certain areas of the plate 18 in order to integrate said plate 18 into the movement. This makes it possible to reduce the size. Preferably, said openwork areas are positioned where the efficiency is lowest.

[0069] According to another variant shown on the figure 6 , the timepiece comprises at least two vibration generating devices distributed inside the case 2, for example two different gongs 14', 14", at least two levers 20', 20" articulated respectively on their support 22', 22", and respectively carrying the gongs 14', 14", and at least a first plate 18' associated with one of the levers 14' and a second plate 14" associated with the other lever 14". Said first and second plates 18', 18" may have complementary shapes chosen to occupy the interior space of the case 2, leaving a completely free space between said plates 18', 18" and the peripheral edge of the element of the case 2 as close as possible to said plates, in accordance with the invention.A free space 23 is also formed between said plates 18', 18" to allow said plates 18', 18" to move freely independently of each other, according to their own vibration movement, depending on the vibrational movements of their respective levers 20', 20". It is thus possible to amplify the sources in different ways. For example, it is possible to adjust a high-pitched timbre and a bass timbre differently. In the case of a minute repeater, it is for example possible to adjust the hour timbre and the minute timbre independently.

[0070] The 14', 14" stamps can be positioned around the 18', 18" plates opposite each other or in any other location. It is obviously possible to provide more than two stamps.

[0071] According to another variant of the first embodiment of the invention shown in the figure 7 , the plate 18 is fixed to the lever 20 by its peripheral edge, for example by embedding. For this purpose, the lever 20 has a groove 38 forming an embedding clamp in which the plate 18 is held, by the periphery of these main faces 18a, 18b, compressed by the lever 20. In another variant not shown, an additional plate is provided which makes it possible to fix the plate 18, by the periphery of these main faces 18a, 18b, on the upper face of the lever 20. The plate 18 can be compressed, by the periphery of the main faces 18a, 18b between the plate and the upper face of the lever 20, or the periphery of the main face 18a of the plate is glued under the plate which is itself screwed onto the upper face of the lever 20, the periphery of the main face 18b being in contact with said upper face of the lever 20.The length of the lever 20 is reduced accordingly to correspond substantially only to the length of the embedding clamp or to the surface area necessary to hold the periphery of the main faces 18a, 18b of the plate 18. Thus, there is no element which passes over the movement or over the dial. The amplification device will then not be visible to a user, which is particularly advantageous when the plate 18 is on the dial side.

[0072] In order to combine rigidity and lightness of the plate 18, said plate may advantageously have a thickness which increases from the peripheral edge to which the lever 20 is fixed to the opposite free peripheral edge. The rigidity is greater close to the point of fixing to the lever 20 and the lightness is greater in the area of ​​the plate furthest away.

[0073] Advantageously, the plate 18, when it is on the dial side, can be arranged to constitute a dial itself, by being pierced in the center for the passage of the hands. Preferably, the dial is transferred, without applique or other added element so as not to increase the weight of the plate.

[0074] In these variants, the lever 20 advantageously comprises the two flexible ball joints or pivots 24 described above with reference to the figure 4 , in order to ensure the guidance of the plate 18.

[0075] In another variant not shown, the plate 18 can be made in a single piece with the lever 20 and the support 22 so that the lever 20 and the support 22 are advantageously constituted by a rim of the plate 18, directly embedded in an element of the box 2, the rest of the plate being in the void, in order to be able to vibrate freely. The gong heel is fixed directly on the plate, close to its point of embedding in the element of the box 2. The gong heel and the plate can be made in a single piece.

[0076] According to a second embodiment of the invention, the plate 18 is arranged to cooperate with the lever 20 in such a way that the entire plate 18 is driven by a linear translational movement along an axis perpendicular to said plate 18, the rotation axis 21 of the lever 20 and the plate 18 remaining parallel in vibration mode. This means that all the points of the plate move according to the same linear translational movement.

[0077] Preferably, the connection point of the lever 20 with the plate 18 is located at a distance from the center of said plate 18 of less than 40%, preferably less than 20%, of the width of said plate 18. In a particularly preferred manner, the connection point of the lever 20 with the plate 18 is located at the center of said plate 18, in order to have a maximum lever arm effect.

[0078] Advantageously, the plate 18 cooperates with means for guiding in linear translation along said axis perpendicular to the plate in order to guarantee that the movement remains linear.

[0079] According to a first variant of the second embodiment shown in the figures 8 et 9 , said guide means comprise at least three flexible fasteners 40 distributed regularly around the periphery of the plate 18 and connecting said plate 18 to a connecting support 42, secured for example to an element of the box 2.

[0080] Thus, the first vibration mode of the plate is a linear displacement of the entire plate 18 by flexing of said fasteners 40 which guide the vibration displacement of the plate 18 and the lever 20, as shown in the figure 9 .

[0081] In this variant, said connecting support 42 constitutes the element of the box 2 closest to the plate 18, delimiting with the plate 18 the free space 44 around the plate 18, between the connecting support 42 and said plate 18.

[0082] When the plate 18 is circular, the fasteners 40 may be three in number, spaced apart from each other by an angle of 120°, or more than three. This principle makes it possible to reinforce the low frequencies by resonance of the elastic plate-fastener system. The shape of the fasteners and their number may vary in order to determine the resonance frequencies of the plate-fastener system. For example, according to a variant not shown, the fasteners may extend concentrically to the plate, and may be three or more in number.

[0083] The dimensions, and in particular the length, of the fasteners 40 are chosen to manage the flexibility (compliance) of said fasteners. Thus, a greater length makes it possible to increase the flexibility of the fasteners 40.

[0084] Advantageously, the flexible or supple fasteners 40 and the connecting support 42 have been formed by cutting into the plate 18, for example by laser. Laser cutting has the advantage of forming the fasteners 40 very precisely in order to make the plate 18 resonate with respect to the gong 14. This also makes it possible to precisely dimension the width of the space 44 between the plate 18 and the connecting support 42, in order to manage the air flow passing from said space 44, as will be described below. Advantageously, the width of the fasteners 40 is such that at least 70%, preferably at least 90% of the periphery of the plate is free to move.

[0085] According to another variant of the second embodiment of the invention, shown in the figures 10 à 12 , the guide means may consist of a bracket 46 comprising a central plate 48 secured to the plate 18 and at least three elastic arms 50 connecting the central plate 48 to an element of the case 2, such as the middle 3.

[0086] Preferably, the arms 50 are distributed regularly around the central plate 48 and have a great length giving them a certain elasticity or flexibility to guarantee linear guidance. They can be attached to the element of the case 2, for example the middle 3, held by a joint 52. They can also be formed in a single piece with the element of the case 2.

[0087] The plate 18 is secured to the central plate 48, for example by screwing, gluing, welding or any other suitable fixing means. The plate 18 is fixed to the central plate 48 by its center so that 100% of the perimeter of the plate 18 is free to move.

[0088] In order to have a perfectly linear vibratory movement of the plate 18, without deformation of the plate, said plate 18 is preferably coupled to the lever by a spherical connection.

[0089] Such a spherical connection can be ensured by an additional flexible ball joint provided at the second end 20b of the lever 20 between said lever and the central plate 48.

[0090] In an advantageous manner, and with particular reference to the figure 12 , such a spherical connection can also be ensured by providing on the central plate 48 of the bracket 46 a contact zone 54 with the second free end 20b of the lever 20, said contact zone 54 and said second free end 20b of the lever 20 being rounded. In addition, the central plate 48 and the second free end 20b of the lever 20 respectively comprise a central channel 56, 58, perpendicular to the main plane of the plate 18, communicating with each other. A prestressed elastic wire 60, such as a nylon wire, passes through said channels 56, 58, one end of the elastic wire 60 being secured to the central plate 48 and the other end of the elastic wire 60 being secured to the second free end 20b of the lever 20. The ends of the wire 60 can be fixed to the plate 48 and to the lever 20 respectively by gluing for example.This arrangement makes it possible to couple the lever 20 and the plate 18 by a flexible fixing and to guarantee contact between the lever 20 and the plate 18 without constraint.

[0091] Regardless of the embodiments, and advantageously, the free space formed around the plate 18 has, between said plate 18 and the peripheral edge of the element of the box 2 closest to the plate, a width of between 10 µm and 500 µm, preferably between 10 µm and 400 µm, preferentially between 10 µm and 300 µm, and more preferentially between 30 µm and 60 µm. A width of less than 10 µm may be considered depending on the technologies available. The same applies to the free space left between the plates, when several plates are used as shown in the figure 6 .

[0092] The free space formed around the plate 18 is necessary to work in piston mode and thus reduce internal friction in said plate 18, but it generates a leak, which must then be sized to be as small as possible in order to reduce the loss of acoustic power.

[0093] The free space is also sized in relation to the openings 62 (cf. figure 2 ) provided for example laterally on the box 2 and through which the amplified sound exits. The leak and the openings 62 can be characterized by their acoustic resistance. The openings 62 have an acoustic resistance much lower than that of the leak so that the majority of the compressed air exits through said openings 62 to propagate the amplified sound. Preferably, the ratio of the acoustic resistances in the useful frequency range between the leak and the openings 62 is at least 2 and preferably 5.

[0094] The openings 62 can advantageously be closed by adjustable closing means arranged to be able to adjust the volume of the sound generated by the plate 18 or arranged to close the openings 62 once the sound has been generated, for example outside the ringing time. These closing means are arranged to be able to be moved between a closed position in which the opening 62 is entirely closed and an open position in which the opening 62 is at its maximum, the intermediate positions making it possible to block the opening 62 more or less to adjust the sound volume. For example, the closing means can comprise a rotating element such as a ring, mounted in rotation on the bottom 4, and arranged to rotate between a closed position in which the opening 62 is entirely blocked and an open position in which the opening 62 is at its maximum.

[0095] Advantageously, when seeking to have a waterproof timepiece, each opening 62 can be protected by an air-permeable and waterproof filter, in order to prevent impurities or water from entering the case. Such filters are known to those skilled in the art.

[0096] The timepiece according to the invention allows a significant amplification of the sound by means of an articulated lever which directs the vibrations of the sound source in the correct axis, while preserving the quality of the sound, which undergoes practically no damping due to the use of a free plate around which air can pass, so that the plate no longer undergoes deformation stress. Unlike a device using a sealed membrane for which the damping of vibrations is very important, the propagated sounds being very strong but very short, the present invention makes it possible to obtain a resonance, with strong propagated sounds, of good quality and lasting as long as possible.

[0097] For most of the examples described above, only one stamp is represented. Obviously, several stamps can be used in the same way.

Claims

1. A timepiece (1) comprising a case (2) containing a movement, at least one device for generating vibrations intended to produce at least one sound, at least one device (16) for amplifying the vibrations generated by said vibration-generating device, said device (16) for amplifying the vibrations comprising a lever (20) linked to a support (22) by an articulation about a single axis of rotation (21), said lever being arranged to be actuated by a transmission member (28) cooperating with the vibration-generating device to transmit the vibrations to said lever (20) in order to make said lever (20) pivot with respect to its support (22) according to a vibration movement around its axis of rotation (21), the device (16) for amplifying the vibrations comprising at least one plate (18) arranged to cooperate with the lever in order to be displaced according to a vibration movement, the timepiece being characterized in that said plate (18) is housed in the case (2) so as to form a free space on the periphery of said plate (18) over at least 70%, preferably at least 80%, of the perimeter of said plate (18).

2. The timepiece according to Claim 1, characterized in that said plate (18) has a stiffness such that said plate (18) acts like a piston over a frequency interval of at least two octaves such that the average displacement of the points on the surface of the plate is greater than 50%, preferably greater than 75%, of the maximum displacement.

3. The timepiece according to any one of Claims 1 and 2, characterized in that the plate (18) is integral with the lever (20) and is displaced with the lever (20) in a rotational movement around the axis of rotation (21) of said lever (20).

4. The timepiece according to Claim 3, characterized in that plate (18) comprises two main surfaces (18a, 18b) joined by a lateral edge (18c), said plate (18) being fixed to the lever (20) by one of its main surfaces.

5. The timepiece according to Claim 4, characterized in that the plate (18) comprises an opening (36) in which the lever (20) is housed without contacting the plate (18) on either side of said opening (36).

6. The timepiece according to Claim 3, characterized in that the plate (18) is fixed to the lever (20) by its peripheral edge.

7. The timepiece according to any one of Claims 1 to 6, characterized in that the lever (20) is mounted in an articulated manner on the support (22) by means of two flexible ball joints (24) disposed so as to be spaced apart from one another as much as possible.

8. The timepiece according to any one of Claims 3 to 7, characterized in that it comprises at least two vibration-generating devices, at least two levers (20', 20"), and at least one first plate (18') associated with one of the levers (20') and a second plate (18") associated with the other lever (20"), said first and second plates (18', 18") being free to be displaced independently of one another according to their own vibration movement.

9. The timepiece according to any one of Claims 1 and 2, characterized in that the plate (18) is arranged to cooperate with the lever (20) so as to be driven by a linear translational movement along an axis perpendicular to the plate (18).

10. The timepiece according to Claim 9, characterized in that the plate (18) cooperates with guide means in linear translation along said axis perpendicular to the plate (18).

11. The timepiece according to Claim 10, characterized in that said guide means comprise at least three flexible attachments (40) distributed regularly over the periphery of the plate (18) and connecting said plate (18) to a linking support (42).

12. The timepiece according to Claim 11, characterized in that said attachments (40) and the linking support (42) have been shaped by cutting into the plate (18).

13. The timepiece according to Claim 10, characterized in that said guide means consist of a bracket (46) comprising a central plate (48) integral with the plate (18) and at least three elastic arms (50) connecting the central plate (48) to the case (2).

14. The timepiece according to any one of Claims 9 to 13, characterized in that the plate (18) is coupled to the lever (20) by a spherical linkage.

15. The timepiece according to Claims 13 and 14, characterized in that the central plate (48) of the bracket (46) comprises a contact area (54) with the free end (20b) of the lever (20), said contact area (54) and said free end (20b) being rounded, in that the central plate (48) and the free end (20b) of the lever (20) respectively comprise a central channel (56, 58) perpendicular to the plate (18), communicating with one another, and in that a prestressed elastic wire (60) passes through said channels (56, 58), one end of the elastic wire (60) being integral with the central plate (48) and the other end of the elastic wire (60) being integral with the free end (20b) of the lever (20).

16. The timepiece according to any one of the preceding claims, characterized in that the free space formed around the plate (18) has, between said plate (18) and the peripheral edge of the case (2) closest to the plate (18), a width of between 10 µm and 500 µm and, preferably, between 30 µm and 60 µm.

17. The timepiece according to any one of the preceding claims, characterized in that the vibration-generating device is a strike-gong (14) arranged to be struck by a strike-hammer (12), said strike-gong (14) being integral with the transmission member (28), said transmission member (28) being integral with the lever (20).

18. The timepiece according to any one of Claims 1 to 16, characterized in that the vibration-generating device is a rotating disk and includes an engraved groove arranged to generate a sound, the transmission member (28) being a hand integral with the lever (20) and arranged to follow the groove on the disk.

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