A watch with a vibration amplifier

Abstract

The invention relates to a timepiece 1 comprising a case 2 housing a movement, at least one vibration generator intended to generate at least one sound, and at least one device 16 for amplifying the vibrations generated by said vibration generator, said device 16 for amplifying the vibrations comprising a lever 20 connected to a support 22 by an articulation about a single axis of rotation and arranged to be actuated by a transmission member 28 which cooperates with the vibration generator to transmit vibrations to said lever 20. The device 16 for amplifying the vibrations comprises at least one plate 18 arranged to cooperate with the lever for displacement in response to a vibratory movement, said plate 18 being housed in the case 2 so as to leave free space on the periphery of said plate 18 over at least 70%, preferably at least 80%, of its circumference.

Description

[Technical Field]

[0001] The invention relates to a timepiece comprising a case containing a movement, at least one vibration generating device intended to generate at least one sound, and at least one device for amplifying the vibrations generated by said vibration generating device, said device for amplifying the vibrations comprising a lever connected by an articulation to a support about a single axis of rotation, said lever being arranged to be actuated by a transmission member which cooperates with the vibration generating device and transmits vibrations to said lever in order to pivot the lever relative to its support in response to an oscillatory movement about its axis of rotation. [Background technology]

[0002] Such a timepiece may be, for example, a chiming watch (minute repeater, grand sonnerie, petite sonnerie, or alarm clock), where the vibration generator is, for example, a gong arranged to be struck by a hammer when the striking mechanism is engaged to generate vibrations to produce sound. The gong is typically in the form of a wire wound around the movement. The gong is attached integrally to the watch frame (plate and bridge assembly) by a heel or gong holder to transmit the gong vibrations to the watch assembly (frame, movement, and external parts). The gong vibrations are thus transmitted with maximum intensity to the wearer of the watch.

[0003] Since the transmission of sound is obtained by vibrating the entire watch, it has been proposed to make the various elements of the watch more rigid in order to encourage them to vibrate and improve said transmission of sound.

[0004] Although this solution gave satisfactory results in terms of sound transmission quality, it created other problems, such as the generation of parasitic noise. In fact, the greater the acoustic intensity, the more the movement vibrates, and the more noise the different parts of the movement generate during vibration. This series of vibrations creates parasitic noise.

[0005] One solution to amplifying the sound is to increase the force with which the hammer strikes the gong, which does achieve an increase in sound, but the quality of the sound is adversely affected by parasitic noise.

[0006] The chiming watch described in patent application EP3644133 proposes to solve this problem by using a waterproof sound-transmitting membrane mounted to seal the case to protect the movement and striking mechanism from moisture and impurities. The membrane can be held in place by, for example, an O-ring seal. The waterproof sound-transmitting membrane contacts a sound-transmitting bridge integrated with a moving part with only one degree of freedom in rotation, which is connected to a heel bearing a gong. The sound-transmitting bridge thus transmits vibrations from the heel, generated by the vibration of the gong when struck by its hammer, directly to the waterproof membrane in the direction optimal for vibrating the membrane, thereby increasing the volume of the sound perceptible outside the watch.

[0007] However, in reality, the waterproof membrane, which is by definition fixed around its periphery to the case elements to ensure its waterproofness, deforms when subjected to vibrations from the sound-transmitting bridge by expanding in one direction and then in the other in a first vibration mode. These deformations cause significant damping that negatively affects the sound quality. Furthermore, the contact between the lever and the membrane can be achieved by the lever prestressing the membrane, thereby amplifying the damping. In the case of a fixed contact, the membrane deforms asymmetrically and is therefore stressed. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent application EP3644133 Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is 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 greatly amplify the generated sound while maintaining the quality of the sound. [Means for solving the problem]

[0010] To this end, the invention relates to a timepiece comprising a case housing a movement, at least one vibration generating device intended to produce at least one sound, and at least one device for amplifying the vibrations generated by said vibration generating device, said device for amplifying the vibrations comprising a lever connected by an articulation to a support about a single axis of rotation, said lever being arranged to be actuated by a transmission member which cooperates with the generator and transmits vibrations to said lever, in order to pivot the lever relative to its support in response to an oscillatory movement about its axis of rotation.

[0011] According to the invention, the device for amplifying vibrations comprises at least one plate arranged to cooperate with a lever for displacement in response to a vibration movement, said plate being housed in a case so as to leave free space on the periphery of said plate over at least 70%, preferably at least 80% or even 100% of its circumference.

[0012] Thus, when the plate begins its oscillatory movement in response to the vibrations transmitted by the lever, said plate, which is essentially free to displace, does not actually deform but acts like a piston against the air, so that the sound produced by the gong is greatly amplified while maintaining its high quality.

[0013] According to a first embodiment, the plate is integral with the lever and is displaced together with the lever in a rotational movement of said lever about its rotation axis.

[0014] According to a first variant, the plate is fixed to the lever by its main surfaces, so that 100% of the periphery of the plate is not fixed.

[0015] According to another variant, the plate is fixed to the lever by its circumferential edge so that the amplification device is not visible to the user.

[0016] According to a second embodiment, the plate is arranged to cooperate with a lever to be driven by a linear translational movement along an axis perpendicular to the plate.

[0017] The plate advantageously cooperates with guide means which translate linearly along said axis perpendicular to the plate to ensure linear movement.

[0018] According to a first variant, said guide means comprise at least three flexible fasteners regularly distributed over the periphery of the plate and connecting said plate to the connecting support.

[0019] Therefore, the first vibration mode of the plate is the linear displacement of the entire plate due to bending of the fastener.

[0020] According to another variant, the guide means consist of a bracket with a central plate integral with the plate and at least three resilient arms connecting the central plate to the case.

[0021] Such a bracket can advantageously produce a linear movement of the entire plate, with 100% of the periphery of the plate being free to displace.

[0022] Other characteristics and advantages of the invention will become apparent on reading the following detailed description of different embodiments of the invention, given by way of non-limiting example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a view of the back of a timepiece according to a first variant of the first embodiment of the present invention. [Figure 2] 1 is a perspective view of a timepiece according to the present invention; [Figure 3] FIG. 1 is a schematic cross-sectional view of a first modified example of the first embodiment of the present invention. [Figure 4] FIG. 2 is a perspective view of a lever used in the present invention. [Figure 5] FIG. 10 is a schematic diagram of the rear of another modified example of the first embodiment of the present invention. [Figure 6] FIG. 10 is a schematic diagram of the rear of another modified example of the first embodiment of the present invention. [Figure 7] FIG. 10 is a schematic cross-sectional view of another modified example of the first embodiment of the present invention. [Figure 8] FIG. 10 is a view of a plate according to a first variant of the second embodiment of the present invention. [Figure 9] 9 is a schematic cross-sectional view of the plate of FIG. 8 in a first vibration mode. [Figure 10] FIG. 10 is a perspective cross-sectional view from the rear of a second modified example of the second embodiment of the present invention. [Figure 11] FIG. 11 is a perspective view of the inside of the case of FIG. 10. [Figure 12] FIG. 10 is a cross-sectional view of a plate and a lever of a bracket according to a second modified example of the second embodiment of the present invention. [Figure 13] FIG. 10 is a perspective view of another embodiment in which a transmission member and a lever cooperate with a vibration generator. [Figure 14] FIG. 5 is a cross-sectional view of the lever of FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0024] The invention relates to a timepiece comprising a case containing a movement, at least one vibration generator intended to generate at least one sound, and at least one device for amplifying the vibrations generated by said vibration generator, said device for amplifying the vibrations comprising a lever connected to a support by an articulation with only one degree of freedom in rotation, i.e. around a single axis of rotation, said lever being arranged to be actuated by a transmission member not directly connected to the support but which cooperates with the vibration generator to transmit vibrations to said lever, in order to pivot the lever relative to its support in response to a vibratory movement around its axis of rotation, said device for amplifying the vibrations comprising at least one plate arranged to cooperate with the lever and to receive the vibrations amplified by the lever, in order to be displaced in response to the vibratory movement in order to apply pressure to the air in order to generate sound from the inside of the timepiece to the outside, said plate being accommodated in the case in such a way as to leave a free space on the periphery of said plate over at least 70%, preferably at least 80%, more preferably at least 90% or even 100% of its circumference, depending on the variant, through which a constant air flow passes.

[0025] The actuation point of the lever, the lever pivot point on the support, and the coupling point of the lever with the plate are positioned so that the displacement of the transmission member generated by the vibration of the transmission member connected to the vibration generator is transmitted to the plate by the lever acted on by the transmission member in a manner amplified by the lever effect, and therefore the vibration movement of the plate is amplified by the amplified vibration displacement of the plate, thereby generating amplified sound.

[0026] Furthermore, the plate is fixed to the lever by a defined area that is as small as possible, the rest of the plate being in a vacuum and not in contact with any other element of the watch.

[0027] The plate is as large as possible to displace as much air as possible during its vibratory motion, while leaving free space around the plate for air to pass through in order to reduce the forces on the plate and damp the vibrations as little as possible without adversely affecting the quality of the amplified sound. Thus, the plate is free to displace without deformation in order to vibrate with as little damping as possible, resulting in a powerful and clean sound.

[0028] The desired objective is to resonate the plate relative to the vibration generator so that the transmitted sound lasts as long as possible.

[0029] The plate may be circular or polygonal, depending on the shape of the case.

[0030] In its rest state, the plate may be substantially flat or may be convex in the shape of a shell, with a radius of curvature greater than the diameter of the watch, i.e. preferably greater than 30 mm, more preferably greater than 50 mm, and preferably between 50 mm and 500 mm. The concave side of the convex plate is advantageously oriented towards the outside of the case at the sound outlet side, and the lever is connected to the convex side of the plate. However, the reverse configuration is also possible.

[0031] As used herein, the term "plate" generally refers to a plate that is flat or bulging.

[0032] The plate is preferably made of a very light and stiff material in order to obtain a large dynamic response as defined above and to avoid deformation not only at its centre but also at its free periphery during its displacement.

[0033] The plate has a stiffness such that said plate acts like a piston over a frequency interval of at least two octaves, for example between 1 kHz and 4 kHz, so that the average displacement of a point on the main surface of the plate is greater than 50%, preferably greater than 75%, of the maximum displacement, i.e. of the displacement of the point on the main surface of the plate that is displaced the most, so that the plates used in the invention do not show substantially any deformation over their entire surface, especially at low frequencies.

[0034] By way of comparison, waterproof membranes conventionally used in striking mechanisms whose edges are fixed to the case deform in response to a parabolic motion so that the average displacement of a point on the surface of the membrane is less than 50% of the maximum displacement.

[0035] The plate is preferably made of a transparent material, for example it may be made of sapphire, mineral glass, plexiglass, diamond, composite material, cellulose or composite glass of the safety glass type.

[0036] The plate is preferably made of mineral glass, sapphire, or diamond.

[0037] When the plate is used as a dial, as described below, the plate is preferably made of a non-transparent material such as silicon, titanium, carbon, or aluminum.

[0038] The plate must be as stiff and light as possible, so its thickness is less than 1 mm, preferably 0.5 mm or less, preferably 0.15 mm or less, more preferably 0.1 mm or less.

[0039] The vibration generator may be a striking gong arranged to be struck by a striking hammer, said striking gong being integrated with a transmission member, said transmission member being integrated with a lever.

[0040] In another variation, the vibration generator may be a rotating disk, including engraved grooves arranged to generate sound, and the transmission member is a needle integrated with a lever, arranged to follow the grooves on the disk.

[0041] In another variant, the vibration generator may be a music box with vibrating wings fixed by a stud, the transmission member being integral with said stud and lever.

[0042] In the following description, the vibration generator is a striking gong that is struck by a striking hammer, so that the timepiece is equipped with a striking mechanism for indicating the time (minute repeater, grand sonnerie, petite sonnerie) or for striking at predetermined times (alarm).The timepiece is preferably a watch, more preferably a wristwatch intended to be worn on the wrist of a user.

[0043] Unless otherwise indicated, the remainder of the description of the invention, and in particular the remainder of the device for amplifying vibrations, applies equally to a music box or a watch with a rotating disk read by a hand, one end of which is integral with the lever and the other end of which is arranged to read an engraved groove on the rotating disk, the hand being attached to the lever, for example by embedding or soldering, for example by being introduced into an orifice provided on the lever for this purpose.

[0044] 1 and 2, watch 1 comprises a case 2 having a middle part 3, a back 4, a bezel 5, and a first crystal 6. Back 4 is annular, with its central opening closed by a second crystal 7. The bezel and middle part may be two distinct parts or may form a single, integral part. Similarly, the back and middle part may be two distinct parts or may form a single, integral part.

[0045] In the following description, the device for amplifying vibrations and the plate are arranged to produce sound from the back of the watch, although it will be apparent that the device for amplifying vibrations and the plate may be arranged in a similar manner, but also in the opposite manner, to produce sound on the dial side of the watch.

[0046] 1, the watch 1 also comprises a movement and a striking mechanism 9 constituting a vibration generator intended to produce at least one sound. The movement and striking mechanism 9 are housed in the middle part 3 of the case 2 and are attached to a frame 10 (plates and bridges). The striking mechanism 9 comprises, in known manner, a hammer 12 arranged to strike a striking gong 14, here in the form of a wire gong or strip spring wound around the movement.

[0047] To amplify the sound produced by the gong 14, a device 16 for amplifying the vibrations produced by the gong 14 is provided, comprising a lever 20 articulated to a support 22 about a single axis of rotation 21, so that the lever is tilted or pivotally mounted on the support 22 about said axis of rotation 21, as is a plate 18 (see Figures 3 et seq.) arranged to receive the amplified vibrations and generate an amplified sound from the inside to the outside of the watch. When the sound is transmitted to the back side, the plate 18 is attached to the back 4 side by being positioned parallel to the back 4 when it is in a vibration-free rest position, at least between the movement and the second crystal 7. When the sound is transmitted to the dial side, the plate 18 is attached inside the bezel 5 by being positioned parallel to the bezel 5 when it is in a rest position, at least between the movement and the first crystal 6.

[0048] It is particularly preferred that the lever 20 and the plate 18 are arranged relative to one another such that the axis of rotation 21 of the lever 20 is parallel to the plane of the main surface 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 to be negligible relative to the degree of freedom of rotation about the axis of rotation 21.

[0049] Referring to Figures 3, 7, 10, and 11, the lever 20 is arranged to be actuated by a transmission member 28 that cooperates with the gong 14 to transmit vibrations to the lever 20. The transmission member 28 is positioned on the same side of the lever 20 with respect to the articulation 21 of the lever 20 with the support 22, so that the transmission member 28 is not directly connected to the support 22 to which the lever 20 is articulated. The transmission member 28 is preferably integral with the lever 20. The transmission member 28 may, for example, consist of a heel or gong holder that is integral with the lever 20, into which the gong 14 is attached, for example, by recessing, screwing, or soldering. For this purpose, the transmission member 28 includes, for example, an orifice 30 through which the gong 14 is introduced. The gong 14 is therefore integral with the lever 20 and is not fixed to the watch frame via the heel. The transmission member 28 can be added to or integrated with the lever 20, as shown in Figures 3, 7, 10, and 11. When the transmission member 28 is integral with the lever 20, the gong is directly assembled to the lever, for example by welding.

[0050] According to another variant not shown, the transmission member 28 can be integrated into the lever 20 by being arranged to form a clamp in which the gong 14 is held. This arrangement minimizes vibration losses.

[0051] According to another variant shown in FIG. 13, the transmission member 28, advantageously formed integrally 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, making it possible to capture the vibrations of the gong 14 and to transmit the captured vibrations to the plate 18 by actuating the lever 20. The transmission member 28 can cooperate with the gong 14 by simple contact or can have the form of a clamp. The gong 14 is then fixed on a heel 64, which is preferably fixed on an element of the case, such as the middle part or the back, or, if appropriate, on an element of the movement. The capture point of the transmission member 28 on the gong 14 is preferably relatively close to the recessed area on the heel. In this configuration, the point at which vibrations are captured by the lever 20 is advantageously located on the gong 14, not on its heel, to achieve low vibration damping and a greater signal amplitude.

[0052] The materials of the lever 20, the gong 14 and the transmission member 28 are advantageously chosen to unite these three elements, said materials being vibration transmitting, for example steel or magnesium.

[0053] The device for amplifying the vibrations, and more particularly the support 22 for the lever 20, is advantageously isolated from the movement, the striking mechanism 9 and the frame 10. For this purpose, the support 22 for the lever 20 can be mounted on an element of the casing, more particularly on the bezel 5 if the sound is transmitted to the dial, or on the back 4 if the sound is transmitted through the back. When the striking gong 14 is embedded in a transmission member 28 integral with the lever 20, said gong 14 appears to float around the movement, rather than being fixed to the frame via a heel, as is conventional.

[0054] The support 22 of the lever 20 can also be mounted on the movement or even on the intermediate part 3, but advantageously via an insulating element such as a polymer to ensure isolation of the support 22 from the movement, the intermediate part and the frame.

[0055] When the support 22 of the lever 20 is attached to the bezel 5, the back 4, respectively, said bezel 5, said back 4, respectively, can be assembled directly to the intermediate part 3 in a conventional manner. However, to ensure that no parasitic vibrations occur on the intermediate part 3, and therefore on the movement, said bezel 5 or said back 4, respectively, is advantageously assembled on the intermediate part 3 by means of an insulating element, such as a polymer.

[0056] The plate 18 is also isolated from the movement and the striking mechanism 9, so that the device for amplifying the vibrations and the plate are isolated from the movement and the frame, with the result that all of the vibrations of the gong captured by the lever 20 are directed towards and transmitted to the plate 18, and not to the movement, the frame or the intermediate part.

[0057] Lever 20 is preferably made from a very light and very rigid material, for example, lever 20 may be made from steel, titanium, aluminum, magnesium, composites, carbon, glass, sapphire, and ceramic.

[0058] The lever 20 can be advantageously articulated or pivotally mounted on the support 22 by a single central flexible ball joint 24, as shown in FIG. 1 . The flexible ball joint (more precisely, the flexible pivot, when considered as an articulation about a single axis of rotation 21) allows the direction of vibration to be changed, if necessary. In particular, in the case of a striking gong, the striking gong tends to vibrate radially in the direction of the hammer strike. The position of the flexible ball joint 24 (i.e., the flexible pivot) of the lever 20 preferably allows the direction of the radial vibration of the gong to be changed by 90°, for example, to convert the radial vibration of the gong, via the pivoting of the lever 20, into a vibratory motion perpendicular to the plane defined by the back surface, i.e., the plane defined by the plate 18 when the plate 18 is in its rest position. The flexible ball joint 24 (i.e., the flexible pivot) is preferably located at the center of mass of the gong / lever / plate assembly.

[0059] As shown in FIG. 4, the lever 20 can be articulated or pivotally mounted on the support 20 by means of two flexible ball joints or pivots 24 arranged on the outside as far away from each other as possible to ensure good guidance of the plate 18 by reducing parasitic movements, especially lateral movements.

[0060] 4 and 14, the wall thickness e of the flexible ball joint 24 (i.e., flexible pivot) can be advantageously varied to vary the vibration frequency of the lever 20 and plate 18 and, therefore, the duration of the sound produced. The thickness e is preferably selected 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 begins to resonate with the gong, thereby reducing sound attenuation and, therefore, lengthening the sound duration. If several gongs are used, the average of their frequencies can be selected as the frequency.

[0061] The thickness of the lever 20 can be chosen to be thicker on the side of the rotation axis 21 and thinner in the direction of the plate 18 in order to reduce the inertia of the system while maintaining the highest possible stiffness.

[0062] It is also possible to articulate or pivotally mount the lever 20 on the support 22 by means of a pin which is attached laterally to the support 22 and which constitutes the axis of rotation 21 of the lever 20. The support 22 is spring-loaded.

[0063] More specifically, the lever 20 comprises a first end 20a articulated or pivotally mounted 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, i.e. the distance between its first end 20a and its second end 20b, varies according to the variants of the invention.

[0064] According to the first embodiment of the present invention, the plate 18 is fixed to the lever 20 by a defined area, thereby being integral with the lever 20 and displacing together with the lever 20 in response to the oscillatory rotational movement of the lever 20 about its axis of rotation 21, i.e. with the same rotational degrees of freedom as the lever 20.

[0065] When the plate 18 is in its rest position, it has two main surfaces 18a, 18b parallel to the dial and back, namely the back surface 18a and the dial surface 18b, which are joined by a lateral edge 18c.

[0066] According to a first variant of this first embodiment, shown in Figure 3, the plate 18 is fixed to the lever 20 by one of its main surfaces, here its surface 18b facing the dial, so that 100% of the periphery of the plate 18 is free. The lever 20 can be fixed to the plate 18, for example, by means of a screw 32 threaded into a hole provided on the plate 18 and into a hole 34 (see Figure 4) provided on the second end 20b of the lever 20, or by gluing, welding, etc.

[0067] The volume of displaced air is greater over the area of ​​plate 18 furthest from axis of rotation 21, indicated by the arrow in FIG.

[0068] Furthermore, since the plate 18 is displaced parallel to the lever 20, the play between the plate and the lever can be extremely small or even zero, thereby reducing the bulk.

[0069] According to another variant shown in Figure 5, the plate 18 can be cut to have radial openings 36 in which the levers 20 are accommodated without contacting the plate 18 on either side of the radial openings 36. This allows the levers 20 to pass through said radial openings 36, thereby integrating the levers 20 within said radial openings 36 and reducing their bulk.

[0070] It is also possible to cut off certain areas of the plate 18 in order to integrate it into the movement, thereby reducing its bulk, and these cut-off areas are preferably located in areas of lowest efficiency.

[0071] According to another variant, shown in FIG. 6, the timepiece comprises at least two vibration-generating devices distributed within the case 2, for example two different gongs 14′, 14″, at least two levers 20′, 20″ articulated on supports 22′, 22″ respectively and carrying a gong 14′, 14″, and at least one first plate 18′ associated with one of the levers 14′ and a second plate 14″ associated with the other lever 14″. According to the invention, said first and second plates 18′, 18″ may have complementary shapes chosen to occupy the interior space of the case 2, leaving a generally free space between said plates 18′, 18″ and the circumferential edge of the element of the case 2 closest to said plates. A free space 23 is also formed between the plates 18', 18" which allows the plates 18', 18" to be freely displaced independently of one another according to their own vibrational movement in response to the vibrational movement of the respective levers 20', 20". It is therefore possible to amplify sources in different ways, for example to adjust a high-pitched gong and a low-pitched gong separately. In the case of a minute repeater, for example, it is possible to adjust the hour gong and the minute gong separately.

[0072] The gongs 14', 14" may be arranged around opposing plates 18', 18" or in any other position. It will be apparent that more than two gongs may be provided.

[0073] According to another variant of the first embodiment of the invention, shown in FIG. 7, the plate 18 is fixed to the lever 20 by its circumferential edge, for example by embedding. For this purpose, the lever 20 has a groove 38 forming a embedding clamp, in which the plate 18 is held by the circumferential edges of its main surfaces 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 to the upper surface of the lever 20 by the circumferential edges of its main surfaces 18a, 18b. The plate 18 can be compressed by the circumferential edges of its main surfaces 18a, 18b between the additional plate and the upper surface of the lever 20, or the circumferential edge of the main surface 18a of the plate is glued under an additional plate which is itself screwed onto the upper surface of the lever 20, with the circumferential edge of the main surface 18b contacting said upper surface of the lever 20. The length of the lever 20 is accordingly reduced to correspond substantially only to the length of the recessed clamp or to the surface required to hold the periphery of the main surfaces 18a, 18b of the plate 18. Thus, no elements pass over the movement or over the dial. The amplification device is invisible to the user, which is particularly advantageous when the plate 18 is on the dial side.

[0074] To combine stiffness and lightness of plate 18, said plate advantageously increases in thickness from the circumferential edge to which lever 20 is fixed to the opposite free circumferential edge, the stiffness being more pronounced near the point of fixation to lever 20 and the lightness being lowest on the region of the plate furthest away.

[0075] Advantageously, plate 18 may be arranged so that when it is on the dial side it constitutes the dial itself by being perforated in the center for the passage of the hands. The dial is preferably printed by transfer, without appliqués or other additional elements, so as not to increase the weight of the plate.

[0076] In these variants, the lever 20 advantageously comprises two flexible ball joints or pivots 24 as described above with reference to FIG. 4, to ensure the guidance of the plate 18 .

[0077] In another variant not shown, the plate 18 may be made integral with the lever 20 and the support 22, such that the latter are constituted by a rim of the plate 18 that is advantageously embedded directly in an element of the case 2, the remainder of the plate remaining isolated so that it can vibrate freely. The heel of the gong is fixed directly onto the plate, near the point where the plate is embedded in the element of the case 2. The heel of the gong and the plate may be made in one piece.

[0078] According to a second embodiment of the invention, the plate 18 is arranged to cooperate with the lever 20 so that the entire plate 18 is driven by a linear translational movement along an axis perpendicular to said plate 18, the axis of rotation 21 of the lever 20 and the plate 18 remaining parallel in vibration mode, i.e. all points of the plate are displaced according to the same linear translational movement.

[0079] The connection point between the lever 20 and the plate 18 is preferably located at a distance from the center of the plate 18 that is less than 40%, preferably less than 20%, of the width of the plate 18. The connection point between the lever 20 and the plate 18 is preferably located at the center of the plate 18 in order to have maximum leverage.

[0080] The plate 18 advantageously cooperates with guide means for linear translation along said axis perpendicular to the plate, to ensure that the movement is linear.

[0081] According to a first variant of the second embodiment shown in FIG. 8, the guiding means comprise at least three flexible fasteners 40 regularly distributed over the periphery of the plate 18 and connecting said plate 18 to a connecting support 42 rigidly connected to an element of the case 2, for example.

[0082] The first vibration mode of the plate is therefore the linear displacement of the entire plate 18 by bending the fastener 40 which guides the oscillatory displacement of the plate 18 and lever 20 as shown in FIG.

[0083] The connecting support 42 constitutes in this variant the element of the case 2 closest to the plate 18, which delimits a free space 44 between the connecting support 42 and the plate 18, around the latter.

[0084] When the plate 18 is circular, the number of fasteners 40 may be three, spaced 120° apart from one another, or may be greater than three. This principle allows for low-frequency enhancement due to the resonance of the plate / elastic fastener system. The shape and number of fasteners may be varied to determine the resonant frequency of the plate / fastener system. For example, in a variation not shown, the fasteners may extend concentrically around the plate and may be greater than three.

[0085] The dimensions of the fastener 40, particularly its length, are selected to accommodate the flexibility (moldability) of said fastener. Thus, a longer length can increase the flexibility of the fastener 40.

[0086] The flexible or pliable fasteners 40 and connecting supports 42 are advantageously shaped by cutting into the plate 18, for example by means of a laser. Laser cutting has the advantage of shaping the fasteners 40 very precisely so that the plate 18 begins to resonate with the gong 14. This also makes it possible to accurately dimension the width of the space 44 between the plate 18 and the connecting supports 42 in order to manage the flow of air displaced from said space 44, as will be explained below. The width of the fasteners 40 is advantageously such that at least 70%, preferably at least 90%, of the periphery of the plate is free to displace.

[0087] According to another variant of the second embodiment of the invention shown in Figures 10 to 12, the guide means may be made of a bracket 46 with a central plate 48 integral with the plate 18 and at least three elastic arms 50 connecting the central plate 48 to elements of the case 2, such as the intermediate part 3.

[0088] The arms 50 are preferably distributed regularly around the central plate 48 and are so long that they are endowed with a certain elasticity or flexibility to ensure linear guidance. They can be added to an element of the case 2, such as the middle part 3, held by the seal 52. They can also be formed integrally with the element of the case 2.

[0089] Plate 18 is integral with central plate 48, for example by screwing, gluing, welding, or any other suitable fastening means. Plate 18 is fixed to central plate 48 by its center so that 100% of the periphery of plate 18 is free to displace.

[0090] To achieve a completely linear oscillatory movement of the plate 18 without deformation of the plate, said plate 18 is preferably connected to a lever by means of a spherical connection.

[0091] Such a spherical connection can be provided by an additional flexible ball joint provided at the second end 20 b of the lever 20 between said lever and the central plate 48 .

[0092] Advantageously, and referring more particularly to FIG. 12, such a spherical connection can also be ensured by providing a contact area 54 for the second free end 20b of the lever 20 on the central plate 48 of the bracket 46, the contact area 54 and the second free end 20b of the lever 20 being rounded. Furthermore, the central plate 48 and the second free end 20b of the lever 20 each have central channels 56, 58 that communicate with each other and are perpendicular to the main plane of the plate 18. A prestressed elastic wire 60, such as a nylon thread, passes through the 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 second free end 20b of the lever 20. The ends of the wire 60 can be fixed to the plate 48 and the lever 20, respectively, for example by gluing. This arrangement allows the lever 20 and the plate 18 to be connected by flexible fastening, ensuring stress-free contact between the lever 20 and the plate 18.

[0093] Regardless of the embodiment, advantageously, the free space formed around the plate 18 has a width between said plate 18 and the circumferential edge of the element of the case 2 closest to said plate of between 10 μm and 500 μm, preferably between 10 μm and 400 μm, preferably between 10 μm and 300 μm, more preferably between 30 μm and 60 μm. Depending on the available technology, widths of less than 10 μm are conceivable. The same applies to the free space left between the plates when several plates are used, as shown in FIG. 6.

[0094] The free space around the plate 18 is necessary to operate in piston mode and therefore reduce internal friction within the plate 18, but it creates a leak that must be dimensioned to be as small as possible to reduce losses in acoustic power.

[0095] The free space is also dimensioned, for example, with respect to an opening 62 (see FIG. 2) provided laterally on the case 2, through which the amplified sound exits. The leak and opening 62 can be characterized by their acoustic resistance. The opening 62 has an acoustic resistance that is much lower than that of the leak, so that a large portion of the compressed air exits through said opening 62, propagating the amplified sound. Preferably, the ratio of the acoustic resistances in the useful frequency range between the leak and opening 62 is at least 2, preferably 5.

[0096] The openings 62 can advantageously be blocked by adjustable blocking means arranged to adjust the volume of the sound generated by the plate 18 or, for example, to block the openings 62 when sound is generated outside of the striking time. These blocking means are arranged to be displaceable between a closed position in which the openings 62 are completely blocked and an open position in which the openings 62 are at their maximum, the intermediate positions blocking the openings 62 and allowing some adjustment of the volume. For example, the blocking means may comprise a rotating element, such as a ring, which is rotatably mounted on the back surface 4 and arranged to rotate between a closed position in which the openings 62 are completely blocked and an open position in which the openings 62 are at their maximum.

[0097] Advantageously, if a waterproof watch is desired, each opening 62 can be protected by a breathable and impermeable filter to prevent impurities or water from entering the case. Such filters are known to those skilled in the art.

[0098] The timepiece according to the invention allows the sound to be greatly amplified by means of an articulated lever which directs the vibrations of the sound source along the correct axis, while at the same time maintaining a virtually undampened sound quality by using a free plate around which air can pass, so that the plate is no longer subjected to deformation stresses. Unlike devices using waterproof membranes, where the damping of vibrations is very important, the transmitted sound is very strong but very short, and the invention allows for a good resonance with a strong transmitted sound that lasts as long as possible.

[0099] For most of the examples above, a single gong is shown, although it will be apparent that several gongs could be used as well.

Claims

1. It comprises a case (2) containing a movement, at least one vibration generator intended to generate at least one sound, and at least one device (16) for amplifying the vibrations generated by said vibration generator, said device (16) for amplifying the vibrations comprising a lever (20) connected by a joint about a single axis of rotation (21) to a support (22), said lever cooperating with said vibration generator to pivot said lever (20) relative to its support (22) in response to a vibratory movement about its axis of rotation (21). a timepiece (1) arranged to be actuated by a transmission member (28) which transmits the vibrations to the lever (20) through a vibration amplifier, characterized in that the device (16) for amplifying the vibrations comprises at least one plate (18) arranged to cooperate with the lever to be displaced in response to the vibration movement, the plate (18) being accommodated in the case (2) so as to leave free space on the periphery of the plate (18) over at least 70% or at least 80% of the periphery of the plate (18).

2. 2. A timepiece according to claim 1, characterized in that the plate (18) has a rigidity such that it acts like a piston over a frequency interval of at least two octaves, so that the average displacement of points on the surface of the plate is greater than 50% or greater than 75% of the maximum displacement.

3. 3. A timepiece according to claim 1 or 2, characterized in that the plate (18) is integral with the lever (20) and displaces together with the lever (20) in the rotational movement of the lever (20) about the rotation axis (21).

4. 4. Timepiece according to claim 3, characterized in that said plate (18) is fixed by its main surface to said lever (20).

5. 5. Timepiece according to claim 4, characterized in that said plate (18) comprises an opening (36) in which said lever (20) is accommodated.

6. 4. Timepiece according to claim 3, characterized in that said plate (18) is fixed to said lever (20) by its circumferential edge.

7. 7. A timepiece according to any one of claims 1 to 6, characterized in that the lever (20) is articulated on the support (22) by means of two flexible ball joints (24) arranged as far apart as possible from each other.

8. 8. A timepiece according to any one of claims 3 to 7, characterized in that it comprises at least two vibration generators, at least two levers (20', 20"), 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 displace independently of one another according to their own oscillatory movements.

9. 3. Timepiece according to claim 1 or 2, characterized in that the plate (18) is arranged to cooperate with the lever (20) to be driven by a linear translational movement along an axis perpendicular to the plate (18).

10. 10. Timepiece according to claim 9, characterized in that said plate (18) cooperates with guide means translating linearly along said axis perpendicular to said plate (18).

11. 11. Timepiece according to claim 10, characterized in that said guiding means comprise at least three flexible fasteners (40) regularly distributed over the periphery of said plate (18) and connecting said plate (18) to a connecting support (42).

12. 12. Timepiece according to claim 11, characterized in that the fasteners (40) and the connecting supports (42) are formed by cutting into the plate (18).

13. 11. Timepiece according to claim 10, characterized in that the guide means consist of a bracket (46) with 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. Timepiece according to any one of claims 9 to 13, characterized in that said plate (18) is connected to said lever (20) by means of a spherical connection.

15. 15. A timepiece according to claim 13 or claim 14 dependent on claim 13, characterized in that the central plate (48) of the bracket (46) has a contact area (54) with the free end (20b) of the lever (20), the contact area (54) and the free end (20b) being rounded, the central plate (48) and the free end (20b) of the lever (20) each having a central channel (56, 58) perpendicular to the plate (18) and communicating with each other, a prestressed elastic wire (60) passing through the 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. A timepiece according to claim 6, claim 7 depending on claim 6 or claim 8 depending on claim 6, characterized in that the free space formed around the plate (18) has a width between the plate (18) and the circumferential edge of the case (2) closest to the plate (18) of between 10 μm and 500 μm, or between 30 μm and 60 μm.

17. 17. A timepiece according to any one of claims 1 to 16, characterized in that the vibration generating device is a striking gong (14) arranged to be struck by a striking hammer (12), the striking gong (14) being integral with the transmission member (28), the transmission member (28) being integral with the lever (20).

18. 17. A timepiece according to any one of claims 1 to 16, characterized in that the vibration generator is a rotating disk with engraved grooves arranged to produce sound, and the transmission member (28) is a hand integral with the lever (20) and arranged to follow the grooves on the disk.

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