HK1218170B - Timepiece having an improved sound level - Google Patents

Description

Timepiece with increased sound level

Technical Field

The invention relates to a method for increasing the sound level of a musical or striking timepiece comprising at least one generator of vibrations in the range of 1kHz to 6 kHz.

The invention also relates to an external component of a musical or striking timepiece carrying at least one vibration generator.

The invention also relates to a timepiece, which is a striking watch and/or a music box watch.

The present invention relates to the field of timepieces, more particularly to timepieces comprising means for generating vibrations in the audible sound range, and more particularly to striking watches and music box watches.

Background

Among the complex timepieces, the striking watch is particularly popular. However, their small size often limits sound emission and the user has to pay special attention to correctly hear the sound message.

Specific holders are known for use as sound boxes, on which the user places his watch when he wishes to better hear the sound produced by the watch, which are not within the scope of the present invention.

Watchcases or watchcase middle parts comprising a resonance chamber, on which an organ, gong or diaphragm generating a musical sound is mounted, are known, as in french patent application No2777095a1 in the name of CHRISTOPHE CLARET SA, wherein, in some variants, the diaphragm is arranged in contact with the walls of such a resonance chamber, which occupies a large part of the available interior space within the watchcase or watchcase middle part.

European patent No 2034376B1 in the name of ROTH ET GENTA SA attempts to solve this space problem by proposing a thin middle part of the watch case as a resonator comprising lugs for fixing a gong or the like.

Swiss patent application No 645236G in the name of boille discloses a watch case comprising a peripheral lug for a mechanical fastener: due to this specific function, they have an increased mechanical rigidity. The geometry, fastening and orientation of such lugs are well defined and the acoustic efficiency is low, they cannot be used as external acoustic resonators.

Acoustic resonators are also known which emit sound through a diaphragm which vibrates a resilient strip and whose vibration is maintained by an electromagnetic transducer, as in swiss patent numbers 497760 and 497017 in the name of SPADINI, which acoustic resonators have large dimensions and require electrical circuitry.

In order to increase the sound level of the striking watch, it is necessary to optimize the elements that make up the external part of the watch so that they radiate the frequencies generated by the striking system, i.e. in general the natural frequencies of the band of the vibrating plate, or of the gong or minute repeater. In order to obtain a rich sound (in the case of a minute repeater device) or a sound with a uniform intensity regardless of the notes played (in the case of a musical box watch), the external part must be able to respond to a wide frequency range between 1kHz and 6kHz, which is the frequency that the human ear perceives best.

However, due to their size, shape and rigidity, the natural modes of the external parts of the watch are mainly at high frequencies. In this case, the external part filters rather than radiating the frequency of the timing sound or melody.

United states patent No. 4216650 in the name of HARA YOSHIAKI (SEIKO) discloses an alarm watch comprising a watch case with a back cover, the peripheral part of which is inclined, a watch band being fixed on both sides of the case, a movement in the front of the case, and a chamber in the back of the case between the movement and the back cover, a transducer facing the chamber and arranged to generate an alarm sound at a selected frequency. The case includes a plurality of sound holes in the inclined peripheral portion to communicate the chamber with the environment. These sound holes are only located internally at an angle of 45 degrees on each side of the longitudinal axis of the bracelet to prevent any holes from being blocked by the user's arm. The volume of the chamber and the number and size of the sound holes are selected so as to form a Helmholtz resonator, thereby increasing the sound pressure generated by the transducer in response to the frequency of the transducer and efficiently transferring the sound to the environment.

It is known to optimise external components so that they radiate at a single given frequency within the relevant frequency band (1kHz-6kHz), as in french patent application No. 1136675a in the name of gebruder JUNGHANS a.g., which discloses the use of a standard diaphragm for a time signal clock; alternatively, the external part is made to radiate multiple modes within the relevant frequency band (1kHz-6kHz), as in european patent application No. 2461219a1 in the name of montes burgent SA, which discloses the use of a spatially optimized homogeneous diaphragm, or also as in european patent No. 2367079B1 in the name of montes burgent SA, which discloses a solution in which the watch mirror constitutes the vibrating radiating part due to the specific arrangement for fixing it to the bezel.

European patent application No. 2367078a1 in the name of montes BREGUET SA discloses a striking watch with a case comprising a case middle part and a removable back cover fixed to the case middle part in a leaktight manner, a mirror closing the case in a leaktight manner, a movement held inside the case and provided with a striking mechanism able to actuate at a determined time to sound, and at least one acoustic membrane connected to the case to radiate the sound generated by the striking mechanism towards the outside of the case, wherein the acoustic membrane is made of amorphous metal.

European patent application No. 2461220a1 in the name of montes BREGUET SA discloses an acoustically radiating diaphragm for a music box or a watch. The membrane comprises a number of recesses or protrusions over a first thickness of the total thickness of the membrane, the shape and size of which are adapted to the type of material and to the note or notes to be radiated by the membrane, and has a uniform amplification in the audible frequency band.

In the prior art, however, it is not possible for a conventional watch design to achieve acoustic resonance of the external parts at frequencies less than 1500Hz, since the main function of the external parts is to ensure protection of the movement and, in general, sealing of the watch, which must therefore be sufficiently rigid and thick. For the same reason, it is not possible to increase the number of acoustic resonances of the external parts in the relevant audible frequency range (from 1kHz to 6kHz) substantially, which significantly limits the level and richness of the emitted sound and of the played melody.

Disclosure of Invention

The invention proposes to increase the sound level and richness of the sounds and melodies played by a timepiece, in particular a chronograph or musical watch, without compromising the quality of the sound transmitted through the mechanism or transmission circuit. The invention also makes it possible to selectively filter part of the noise generated by the mechanism of a timepiece, in particular a wristwatch.

In an innovative way, the invention integrates additional vibration-radiation elements in the conventional external part, these additional elements being dimensioned such that the frequency of their first natural mode (hereinafter referred to as the "frequency of the radiator") is tuned to the natural frequency of the vibration generator of the timepiece, in particular of a watch, in particular of the gong or the bar of the vibrating plate (hereinafter referred to as the "frequency of the generator") in order to increase the overall sound level of the timepiece, in particular of the watch. The geometry (surface, thickness, shape) of these additional elements allows the formation of acoustic radiation waves.

Thus, the conventional external parts can be dimensioned according to constraints imposed by the design of the timepiece, the model studies, the dimensions of the movement, and in order to respond to requirements such as waterproof and shock-resistant performances without being particularly related to the radiation power of the external parts, which is increased according to the invention by the addition of these vibrating elements (hereinafter referred to as "acoustic radiators"), the dimensions of which are optimized specifically for the acoustic radiation function.

To this end, the invention relates to a method for increasing the sound output level of a musical or striking timepiece, said timepiece comprising at least one vibration generator vibrating at a generator-specific natural frequency lying in the range 1kHz to 6kHz, characterized in that the external part and/or movement of said timepiece is modified by integrating or adding at least one acoustic radiator comprising at least one vibration-radiating element whose radiator natural frequency is tuned to one of the natural frequencies of said vibration generator, wherein the frequency difference is less than or equal to the ratio between the natural mode frequency of the radiating element and the inverse quality factor (inverse quality factor), or less than or equal to 100Hz, characterized in that, in order to determine the number of said acoustic radiators, the following steps are carried out:

-determining the number of vibration modes of the generating element formed by the vibration generator that needs to be radiated;

-providing said timepiece with said number of radiating elements, each radiating element being formed by one of said acoustic radiators comprising at least one vibration-radiating element, each of said acoustic radiators being fixed on the outside of the case of said timepiece.

The invention also relates to external parts for a musical or striking timepiece, said external parts being characterized in that they comprise at least one acoustic radiator comprising at least one element vibrating-radiating at a radiator natural frequency tuned to at least one of the natural frequencies of the timepiece generator.

The invention also concerns a timepiece, such as a striking watch and/or a musical box watch, characterized in that it comprises the above-mentioned external part, and/or a movement carrying at least one vibration generator vibrating at a generator-specific natural frequency, said movement comprising at least one acoustic radiator comprising at least one element vibrating-radiating at a radiator natural frequency tuned to at least one of the generator natural frequencies.

Drawings

Other features and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:

fig. 1A shows a schematic partial perspective view of a timepiece formed by a watch optimized according to the invention by integrating an acoustic radiator comprising a radiating plate, the acoustic radiator being integrated in a middle part of the case or in the bezel of the watch.

Figure 1B shows a schematic perspective view of a watch optimized according to the invention, with different sizes of acoustic radiators with different mounting conditions, extending outside the watch case.

Figure 2A shows a schematic perspective view of a particular variant embodiment of the invention with 4 generally radial acoustic radiators fixed to a watch case, with the main vibrating surface facing the user.

Fig. 2B shows a schematic cross-section of the watch of fig. 2A, in a plane passing through the main axis, said watch comprising an acoustic radiator and a sound generator according to the invention.

Figure 2C shows, in a similar way to figure 2B, another variant with acoustic radiators outside and inside the watch case.

Fig. 3 shows a graph of the frequency and the sound level measured on the major axis of the watch at 5cm from the watch for the same watch exterior part, the frequency in Hz lying on the abscissa and the sound level in dB lying on the ordinate, with a solid line for the conventional embodiment and with a dashed line for the first optimized embodiment in which the same exterior part is equipped with an acoustic radiator according to the invention; the figure is shown in an application where the first natural mode of the acoustic radiator is at 1350 Hz. The figure shows the effect of the resonance of the radiator at the desired frequency and the anti-resonance effect (filtering, sound attenuation) at the rest of the frequency band.

Fig. 4 shows, in a similar way to fig. 2A, the same external parts according to a second preferred embodiment, where each part is provided with an acoustic radiator having a first natural mode of 2210 Hz.

Fig. 5 shows a block diagram of a timepiece comprising an optimized external component according to the invention.

Detailed Description

The present invention relates to the field of timepieces, more particularly timepieces comprising an acoustic emission device, and more particularly to a musical box watch and a striking watch, which will be referred to hereinafter as "musical watch", and proposes to provide means for increasing the sound level and volume.

The present description more particularly relates to such musical watches. The skilled person will understand how to use the invention described for a timepiece or watch that is not musical or that does not have a striking mechanism, for example in order to make all or part of the sound emitted by the watch mechanism audible to the user, as the case may be, or conversely to filter and make inaudible the noise generated by this mechanism (by exploiting the phenomenon of antiresonance caused by the vibration coupling between the acoustic radiator according to the invention described below and other external parts of the watch).

The present invention relates to improvements relating to both the design of musical watches and the retrofitting of existing musical watches to optimize their sound levels.

The invention thus relates to a method for increasing the sound output level of a musical or striking timepiece 1 comprising at least one vibration generator 2 vibrating at a specific natural frequency (referred to herein as the "natural frequency of the generator"). The vibration generator 2 may comprise a gong, a diaphragm, a loudspeaker box or the like which vibrates with a specific natural frequency within the active band, i.e. with a frequency between 1kHz and 6 kHz. The frequency of vibration of the generator element will be referred to herein as the "frequency of the generator", while the frequency of vibration of the radiating element described below will be referred to herein as the "frequency of the radiator".

The external part 3 of timepiece 1 or movement 17 of timepiece 1 carries this vibration generator 2.

According to the invention, the specific natural frequency of the generator is determined: the specific natural frequency of the generator is calculated precisely (FEM simulation, etc.) and at least one radiating element is integrated or added to the design and to the external part 3 and/or the movement 17, and in particular but not exclusively to the outside of said external part 3 and/or of said movement 17, this radiating element being an acoustic radiator 4.

The acoustic radiator 4 comprises at least one vibration-radiating element which vibrates at a radiator natural frequency tuned to one of the generator natural frequencies of the vibration generator 2, wherein the frequency difference is less than or equal to the ratio between the natural mode frequency of the radiating element and the inverse of the quality factor, or the frequency difference is less than or equal to 100 Hz.

In a particular embodiment, the natural frequency of the radiator is tuned to one of the natural frequencies of the generator, wherein the frequency difference is smaller than or equal to the minimum of the ratio between the natural mode frequency of the radiating element and the inverse of the quality factor on the one hand and the value of 100Hz on the other hand.

"tuning" herein means adjusting a frequency to a substantially equal frequency, wherein the frequency difference is less than a calculated or predetermined value; the term "substantially equal" depends on the vibro-acoustic resonance width of the radiating element and therefore on its quality factor.

The radiator frequency of the fundamental natural mode of the radiating element, here the acoustic radiator 4, is tuned to the generator frequency of the natural vibration mode of the vibration generator 2. This tuning rule can be configured in a different way by specifying that the radiator frequency of the fundamental natural mode of the radiating element is substantially equal to the generator frequency of the natural vibration mode of the vibration generator 2, the difference between the two frequencies being smaller than the ratio between the radiator frequency and the quality factor of the radiating element evaluated at the radiator frequency.

It must be understood that the term "tuning" used in this description refers to the vibroacoustic resonance capability of the radiating element formed by the acoustic radiator 4 when stressed at the vibration frequency of the generating element formed by the vibration generator 2. Thus, the term does not take into account any musical characteristics.

Thus, if the quality factor of the radiating element is less than or equal to 10, the frequency of the generator can be tuned to the frequency of the radiator, wherein the frequency difference is less than or equal to 100Hz, which is generally feasible, as shown in fig. 3 and 4.

The quality factor Q is defined as the ratio between the mechanical energy (sum of elastic and kinetic energy) stored in the vibrating element on the one hand and the energy lost due to damping during one complete oscillation on the other hand.

In one oscillation, Q ═ 2. pi. (stored/lost energy)

The quality factor is also defined in the same way as the ratio between the frequency of the natural vibration mode and the resonance bandwidth of the vibrating element. When excitation is applied at a frequency in a frequency range around the frequency of the natural vibration mode, the vibrating element responds (thus it starts to vibrate strongly): this frequency range is the bandwidth (peak width in fig. 3 and 4). Mathematically: q ═ f/(f2-f1), f1 and f2 define the extremes of the frequency range.

The frequency difference with respect to the generator frequency that needs to be tuned to this frequency is thus less than or equal to the ratio between the natural mode frequency of the radiating element and the inverse of the figure of merit.

The default maximum value for this frequency difference may be taken to be 100 Hz.

This definition takes into account the fact that the quality factor Q of the generating element is always between 5 and 100 times the quality factor Q of the radiating element and is typically between 8 and 30 for the mechanism to which the invention relates.

Thus, the radiating element resonates when it is stressed by vibrations at a generator frequency fA, which is tuned according to the above definition, or substantially equal to its fundamental frequency in tabulated terms, as shown for example in fig. 3 and 4, where the frequency response range of the radiating element is about 100 Hz: the difference between the frequency of the radiating element and the frequency of the generating element may thus be 100 Hz.

The vibration frequencies (infinite harmonic numbers) of the radiating elements need not all be substantially equal to one of the vibration frequencies of the generating elements.

In contrast, according to the most advantageous variant of the invention, a plurality N of radiating elements is fixed to timepiece 1, in particular a wristwatch. N is the number of vibration modes of the generating element that need to be radiated, and each radiating element has a fundamental vibration mode with a frequency substantially equal to the frequency of one of the modes of the generating element.

For example, for a gong having 4 vibration modes in the frequency range between 1kHz and 6kHz, 4 acoustic radiators 4 formed by radiating plates are added to the exterior of the case of timepiece 1, in particular a watch, each of these 4 plates having a fundamental natural vibration mode whose frequency is substantially equal to one of the vibration frequencies of the gong between 1kHz and 6kHz according to the above definition.

In another example, for a vibrating plate having 10 strips, each having a vibration mode in the frequency range between 1kHz and 6kHz, 10 acoustic radiators 4 formed by radiating plates are added to the exterior of the case of timepiece 1, in particular a wristwatch, each of these 10 plates having a fundamental natural vibration mode with a frequency substantially equal to one of the vibration frequencies of the vibrating plate strips.

Thus, in order to improve the radiation of timepiece 1, in particular a wristwatch, the person skilled in the art implements a method for determining the number of acoustic radiators 4 comprising the following steps:

determining the number N of vibration modes of the generating element formed by the vibration generator 2 that needs to be radiated;

-providing timepiece 1 with a number N of radiating elements, each radiating element being formed by an acoustic radiator 4 comprising at least one vibration-radiating element, each acoustic radiator 4 being fixed on the exterior of the case of timepiece 1;

ensuring that the only function of each acoustic radiator 4 is radiation;

preferably orienting each acoustic radiator 4 in a particular listening direction in which timepiece 1 is designed; it is assumed that the user listens to the striking tone and/or music emitted by timepiece 1 in said specific listening direction;

optimizing each acoustic radiator 4 to ensure that the frequency of its fundamental natural mode is tuned to be substantially equal to the frequency of one of the natural vibration modes of the generating element;

ensuring that each acoustic radiator 4 is distinguished from the generating element (apart from the substantially equal frequencies that need to be radiated, their frequencies are different, their quality factors are different, there is no phase relationship between the vibration of the acoustic radiator 4 and the vibration of the generating element).

The acoustic radiators 4 according to the invention have a radiating function in the case where they are positioned on the outside of the case of a timepiece 1, in particular a wristwatch; if they are arranged internally, their function is instead to filter (denoise) at the relevant frequencies.

This acoustic radiator 4 and its mechanical connection to timepiece 1 are digitally dimensioned to have a natural vibration mode, the frequency of which is tuned to within 100Hz of at least one of the natural frequencies of the generator, and the spatial deformation of which allows the generation of acoustic radiation waves. The radiation conditions of the structures are proposed, for example, in the C Lesueur document "ray-absorbent devices," video-absorbent, interaction flow-structure "(1988).

Preferably, the outer part 3 and/or the movement 17 are adapted by integrating or adding a plurality of such acoustic radiators 4, each of which introduces a radiator natural frequency within 100Hz of one of the generator frequencies of the vibration generator.

In a particular embodiment of the invention, at least a part of the acoustic radiators 4 are selected to have radiator natural frequencies that differ from each other.

In a particular embodiment of the invention, at least a part of the acoustic radiators 4 are selected to have radiator natural frequencies equal to each other.

It will be appreciated that both embodiments of the invention can also be combined by selecting a plurality of sets of acoustic radiators 4, each set being formed by acoustic radiators 4 tuned to the same radiator natural frequency, and the radiator natural frequencies of the different sets being different from each other.

In an advantageous embodiment, at least one such acoustic radiator 4 having a radiator natural frequency tuned to one of the generator natural frequencies is selected for each generator natural frequency generated by at least one vibration generator 2 in a given frequency range within the audible range of the human ear.

Advantageously, at least one such acoustic radiator 4 is made with a main vibrating surface 6 oriented in a preferred direction, in particular the main axis of the watch, corresponding to the pivot axis of the hands, to enhance the diffusion of the sound towards the user, in particular via the external part 3.

The use of the acoustic radiator 4 must not complicate the handling of the timepiece components, in particular of the watch, during assembly or maintenance. Furthermore, preferably and in a non-limiting manner, at least one such acoustic radiator 4 is fixed to middle case part 5 comprised in external part 3, or to case 10 comprised in external part 3, or to bezel 11 carried by one such middle case part 5, or to bottom plate 14 comprised in timepiece 1. Advantageously, at least one such acoustic radiator 4 is arranged outside the middle part 5 of the watch case or inside the watch case 10 such that the acoustic radiator 4 is not in direct contact with the user.

In order to achieve good vibration of each acoustic radiator 4, at least one of said acoustic radiators 4 is connected to the middle part 5 of the watch case or to the watch case 10 by means of an attachment leg 7 (preferably only one is present) carrying at least one vibration strip 8 of the acoustic radiator 4. Figure 1B shows a vibrating strip 8 connected to the middle part 5 of the watch case by one or two attachment legs 7.

Fig. 2A shows an embodiment of the invention in which 4 acoustic radiators 4 are formed by 4 rectangular strips 8 fixed to a case 10 of timepiece 1, each rectangular strip 8 being connected by one such attachment leg 7, these strips 8 being substantially radiating and having main vibrating faces 6 that are substantially coplanar. The radiators 4 are free to vibrate in their first mode of vibration and generate an acoustic radiation wave that propagates in the direction of the axis of the timepiece, in particular of the wristwatch 1.

According to the invention, at least one such acoustic radiator 4 can also be formed by making a partial cut in the form of a vibration strip 8 in the case middle part 5 (or in the bezel 11 or other component of the case of a timepiece, in particular a wristwatch), the vibration strip 8 being connected to the case middle part 5 by a single end 9 of the vibration strip 8, as shown in fig. 1A.

In a particular embodiment, at least one such acoustic radiator 4 is formed by making a partial cut in the form of a vibrating strip 8 in the bezel 11, the vibrating strip 8 being connected to the bezel 11 by a single end 9 of the vibrating strip 8.

In a particular embodiment, at least one such acoustic radiator 4 is formed by making a partial cut in the form of a vibration strip 8 in the back cover 12, which vibration strip 8 is connected to the back cover 12 by a single end 9 of the vibration strip 8.

The invention also relates to an external part 3 for a timepiece 1 or for a musical or striking timepiece, in particular for a wristwatch and more particularly for a musical or striking watch. These outer parts 3 carry at least one vibration generator 2 which vibrates at a specific generator natural frequency.

According to the invention, the external part 3 comprises at least one acoustic radiator 4, which acoustic radiator 4 comprises at least one vibration-radiating element, in particular a vibration strip 8, which vibrates with a radiator natural frequency tuned to at least one of the generator natural frequencies.

The outer part 3 preferably comprises a watch case 10 surrounding at least one middle part 5, and at least one such acoustic radiator 4 is fixed to the middle part 5 or to the watch case 10.

In a particular variant, the external part 3 comprises at least one such acoustic radiator 4 outside the middle part 5 of the case or inside the case 10.

In the different variants that can be combined with one another and that are visible in fig. 1A, 1B, 2A, 2B and 2C:

at least one acoustic radiator 4 is arranged outside the middle part 5 of the case;

at least one acoustic radiator 4 is arranged outside a bezel 11 carried by the case middle part 5;

at least one acoustic radiator 4 is arranged outside a back cover 12 comprised in the watch case 10;

at least one acoustic radiator 4 is arranged on one or both corners 13 comprised in the watch case 10;

at least one acoustic radiator 4 is arranged on a bottom plate 14 comprised in a movement 17 of timepiece 1, acoustic radiator 4 comprising a connecting member 15 passing through case 10 of timepiece 1;

at least one acoustic radiator 4 is formed integrally with the element to which it is attached to timepiece 1.

In the embodiment of fig. 1B, at least one such acoustic radiator 4 is connected with the middle part 5 of the watch case or the watch case 10 by a single attachment leg 7, which attachment leg 7 carries at least one vibration strip 8 comprised in the acoustic radiator 4.

In the embodiment of fig. 1A, at least one such acoustic radiator 4 comprises at least one vibration strip 8 cut out of the middle part 5 of the watch case, which vibration strip 8 is connected to the middle part 5 of the watch case by a single end 9 of the vibration strip 8.

Preferably, the outer part 3 comprises a plurality of such acoustic radiators 4, wherein at least a part of the acoustic radiators 4 have radiator natural frequencies which differ from each other.

The invention also relates to a timepiece 1, this timepiece 1 being a striking watch and/or a musical box watch. The timepiece comprises an external part 3 and/or a movement 17 carrying at least one vibration generator 2 vibrating at a specific generator natural frequency, these external parts 3 and/or this movement 17 comprising at least one acoustic radiator 4, this acoustic radiator 4 comprising at least one element vibrating-radiating at a radiator natural frequency tuned to at least one of the generator natural frequencies.

Returning to the acoustic radiator 4, preferably a vibration strip 8, in particular an additional plate, here shown in a non-limiting rectangular shape, is screwed or welded or pressed in or fixed by any method allowing the transmission of acoustic vibrations to one or more members of the external part, such as the corners 13, the bar, the case middle part 5, the bezel 11, the back cover 12, the case 10 or even the bracelet links. These additional plates vibrate and radiate at their natural frequency when the striking mechanism is released, either for sound presentation or simply to permanently ensure amplification (resonance) or filtering (anti-resonance) of the noise emitted by the mechanism during operation in a selective manner. These vibrating elements serve as radiating plates forming the acoustic radiator 4.

According to a first variant, acoustic radiator 4 is fixed to movement 17 of timepiece 1, for example to bottom plate 14 of movement 17, instead of to external part 3. In this case, it is preferable that the connection part 7 is a member that passes through the outer part 3 through an opening sealed by a sealing gasket.

According to a second variant embodiment, the acoustic radiators 4 and their connecting elements 7 form an integral assembly. Advantageously, at least one acoustic radiator 4 is thus made with structural or external components in a pre-assembly operation, which facilitates the final assembly of timepiece 1.

The shape of the acoustic radiators 4, the attachment conditions and the materials used define the natural frequency of these elements, which is tuned to the natural frequency of the striking system (in particular the gong or diaphragm strip) or mechanism. Fig. 1A and 1B show these acoustic radiators 4, for example, fastened to a housing intermediate part 5. Fig. 1B shows in particular acoustic radiators 4 of different sizes, with different attachment conditions by means of one or more attachment legs 7, which naturally modify their natural radiator frequencies.

Fig. 2A shows a second embodiment of the present invention.

Figures 2B and 2C show two variants, the first having only the acoustic radiator 4 located outside the case and the second having the acoustic radiator located both outside and inside the case.

According to a third embodiment (not shown), at least one acoustic radiator 4 is formed by a plate 8, the shape of which plate 8 is close to that of a crown or spherical dome, and its connecting element 7 is fixed at the centre of the plate 8.

The acoustic radiator may be made of gold or other noble metals, such as platinum or platinum group metals or alloys of one or more of these noble metals. Alternatively, they may be made of steel. Alternatively, they may be made of titanium or titanium alloys. Alternatively, they may be made of silicon or silicon dioxide, or of polycrystalline diamond. Alternatively, they may be made of metallic glasses or alloys that are at least partially amorphous. Alternatively, they may be made of ceramics.

Advantageously, the acoustic radiator 4 is made in the form of a vibrating strip 8 comprising a plate 16 inscribed in a parallelepiped, the maximum dimension of which is greater than or equal to 4mm, the minimum dimension of which is comprised between 0.05mm and 2mm, and the third dimension of which is greater than or equal to 2 mm.

Advantageously, the acoustic radiator 4 comprises a vibrating strip 8, the vibrating strip 8 in turn comprising at least one plate with a radius of curvature greater than 0.5 mm.

The acoustic radiator 4 makes it possible not only to increase the acoustic intensity of the timepiece, in particular of the watch 1, but also to optimize the acoustic directivity. In fact, the vibration plane, or at least the main vibration plane 6, can be oriented so that the radiation is maximum in a particular desired direction. In embodiments comprising a plurality of acoustic radiators 4, it is also possible to define a specific directivity for each note produced, thus producing a stereo effect.

A vibro-acoustic model is developed within the scope of the present invention to appropriately size the acoustic radiators 4 and predict the acoustic gain provided by these vibrating elements.

In the exemplary embodiment of fig. 3, the acoustic radiators 4 are optimized such that their first natural mode has a frequency of 1350 Hz. A harmonic excitation scan frequency between 1000Hz and 3200Hz is applied to the external part 3.

Fig. 3 shows the sound level of the outer part 3, consisting of the middle part 5 of the watch case and the bezel 11 with the mirror, corresponding to the excitation frequency applied to it, without an acoustic radiator (solid line) and with an acoustic radiator 4 according to the invention (dashed line). In a configuration without a radiator, the sound level increases at frequencies above 3kHz, which corresponds to the frequency of one of the natural modes of the outer part 3.

When the outer part 3 is supplemented by an acoustic element 4, the sound level increases significantly at the frequency of the first natural mode of the radiator (at 1350 Hz). The gain is 10 to 15 dB. The coupling between the acoustic radiator 4 and the external part 3 occurs at 1900Hz, which also achieves an increase in the sound level. The coupling between the modes of vibration of the acoustic radiator 4 and the external part 3 also causes two anti-resonances at 1450Hz and 2150Hz, which also reduce the acoustic emissions at the remaining frequencies of the frequency band compared to the case without the radiator, and thus filter the noise generated by the mechanism.

In fig. 4, the sound level of the outer part 3 of the acoustic radiator 4 with the first natural mode at 2210Hz (dashed line) is compared with the sound level of the same outer part 3 without the radiator (solid line). Again, the acoustic radiators 4 provide a strong acoustic improvement at their first mode frequencies.

As a result of these results, acoustic radiator 4 can be sized for each frequency produced by a sound producing, time telling, alarm, music or other system. The sound produced by a timepiece, particularly a wristwatch, can be optimized across a wide frequency band. The specific dimensioning of the radiator also makes it possible to filter the noise coming from the mechanism.

In summary, the present invention is capable of improving acoustic efficiency not only with respect to the above-mentioned patent application filed by the same applicant, Montres Breguet SA, but also with respect to the above-mentioned french patent No. 1136675a filed by Junhans, which applications collectively represent the most effective mechanism prior to the present invention: the prior art embodiments have always encountered the problem of having the system (e.g. clock) radiate at multiple independent frequencies within the 1kHz to 6kHz frequency band rather than through a single resonant radiation. Thus, in FR1136675A, the diaphragm radiation frequency coincides with the single radiation frequency of the device and therefore of the external component.

The present invention introduces a non-diaphragm acoustic radiator solution that can, in contrast, add one or more additional radiation frequencies to the natural radiation frequencies of the external components of the system: as shown in fig. 3 and 4, the result is that the frequency of the acoustic radiator 4 is increased to that of the external part 3 without destroying or replacing it, whereas in the prior art only one resonance, i.e. that of the system with diaphragm, is visible.

The features of the invention constitute novelty over the prior art, which is intended only to improve the radiation of elements forming external parts, such as the bezel-mirror assembly, the middle part of the case or the back cover, or to make the actual sound-generating element radiate.

In the case of the present invention, the generating element does not necessarily radiate and even advantageously remains non-radiating and physically distinct from the radiating element, which ensures a low attenuation rate and purity of the vibration frequency (and therefore ultimately of the sound), while the radiating element is transferred to the external part but is not part of the member forming the external part, which in particular ensures the waterproof properties of timepiece 1 (in particular in the case of a wristwatch).

The invention is easy to implement, is of moderate cost and offers a number of advantages over the prior art:

-an increase in the sound level of the sound radiated by a timepiece, in particular a wristwatch, in a frequency band between 1kHz and 6 kHz;

the possibility to individually and specifically optimize the acoustic radiators 4 to increase the overall sound level, in particular the tuning according to melodies or gongs.

This system does not impose any constraints on the design of the external components:

the waterproofing properties are not affected, since all gaskets can be retained, which is necessary in any timepiece, in particular waterproof watches;

in certain embodiments, the impact resistance and interior space need not be changed;

the possibility of optimizing the directionality of the sound produced by the timepiece, in particular watch 1, and thus of obtaining a stereo effect, in a frequency selective manner;

the possibility of producing the acoustic radiator 4 very economically by electroforming;

the possibility of tuning the natural frequency of each acoustic radiator 4 to the frequency of the strip or gong of the diaphragm;

-maintaining the intelligibility of the sound emitted by the mechanism.

Claims (31)

1. A method for increasing the sound level of a musical or striking timepiece (1), said timepiece comprising at least one vibration generator (2) vibrating at a specific generator natural frequency in the range 1kHz to 6kHz, characterized in that the external part (3) and/or movement (17) of the timepiece is modified by integrating or adding at least one radiating element formed by an acoustic radiator (4), said acoustic radiator (4) comprising at least one element vibrating-radiating at a radiator natural frequency tuned to one of the generator natural frequencies, wherein the frequency difference is less than or equal to the ratio between the natural mode frequency of the radiating element and the inverse of the quality factor, or less than or equal to 100 Hz; and, in order to determine the number of acoustic radiators (4), performing the following steps:

-determining the number (N) of vibration modes of the generating element formed by the vibration generator (2) that needs to be radiated;

-providing said timepiece (1) with said number (N) of radiating elements, each radiating element being formed by one of said acoustic radiators (4) comprising at least one vibration-radiating element, each of said acoustic radiators (4) being fixed on the exterior of the case of said timepiece (1).

2. Method according to claim 1, characterized in that for each of the acoustic radiators (4) the radiator natural frequency is tuned to the generator natural frequency, wherein the frequency difference is smaller than or equal to the minimum of the ratio between the natural mode frequency of the radiating element formed by the acoustic radiator (4) concerned on the one hand and the inverse of the quality factor on the other hand, and the value of 100Hz on the other hand.

3. A method according to claim 1, characterized in that the only function of verifying each acoustic radiator (4) is to radiate.

4. A method according to claim 3, characterized in that each of said acoustic radiators (4) is oriented in a particular listening direction for which the timepiece (1) is designed.

5. A method according to claim 3, characterized by optimizing each acoustic radiator (4) to ensure that the frequency of the fundamental vibration mode of each acoustic radiator is tuned to be substantially equal to the frequency of one of the natural vibration modes of the vibration generator (2), wherein the frequency difference is smaller than or equal to the ratio between the natural mode frequency of the radiating element and the inverse of the figure of merit, or the frequency difference is smaller than or equal to 100 Hz.

6. A method according to claim 3, characterized by verifying that each acoustic radiator (4) is distinct from the vibration generator (2).

7. Method according to claim 1, characterized in that the external part (3) or the movement (17) is retrofitted by integrating or adding a plurality of the acoustic radiators (4).

8. A method according to claim 7, characterized in that at least a part of the acoustic radiators (4) are selected to have radiator natural frequencies that differ from each other.

9. Method according to claim 1, characterized in that at least one of said acoustic radiators (4) is made with a main vibrating surface (6) oriented in a preferred direction to enhance the dispersion of the sound towards the user.

10. A method according to claim 1, characterised in that at least one of the acoustic radiators (4) is fixed on a middle part (5) comprised in the external part (3), or on a watch case (10) comprised in the external part (3), or on a bezel (11) carried by the middle part (5), or on a bottom plate (14) comprised in the movement (17) of the timepiece (1).

11. Method according to claim 10, characterized in that at least one of the acoustic radiators (4) is arranged on the outside of the middle part (5).

12. Method according to claim 10, characterized in that at least one of the acoustic radiators (4) is arranged on the outside of a bezel (11) carried by the middle part (5).

13. Method according to claim 10, characterized in that at least one of said acoustic radiators (4) is arranged on the outside of a back cover (12) comprised in said watch case (10).

14. Method according to claim 10, characterized in that at least one of the acoustic radiators (4) is arranged on one or both corners (13) comprised in the watch case (10).

15. Method according to claim 10, characterized in that at least one of said acoustic radiators (4) is arranged on a bottom plate (14) comprised in said movement (17) of said timepiece (1), said acoustic radiator (4) comprising a connecting member (15) passing through said case (10) of said timepiece (1).

16. Method according to claim 1, characterized in that at least one acoustic radiator (4) is provided, which is integral with the element for attaching it to the timepiece (1).

17. Method according to claim 10, characterized in that at least one of the acoustic radiators (4) is connected to the middle part (5) or to the middle part (10) or to the movement (17) by means of a single attachment foot (7) included in the acoustic radiator (4) carrying at least one vibration strip (8).

18. Method according to claim 10, characterized in that at least one of the acoustic radiators (4) is formed by making a partial cut in the middle part (5) in the form of a vibration strip (8), the vibration strip (8) being connected to the middle part (5) by a single end (9) of the vibration strip (8).

19. A method according to claim 12, characterized in that at least one of said acoustic radiators (4) is formed by making a partial cut in the form of a vibrating strip (8) in said bezel (11), said vibrating strip (8) being connected to said bezel by a single end (9) of said vibrating strip (8).

20. A method according to claim 13, characterized in that at least one of the acoustic radiators (4) is formed by making a partial cut in the form of a vibration strip (8) in the back cover (12), the vibration strip (8) being connected to the back cover by a single end (9) of the vibration strip (8).

21. A method according to claim 1, characterized in that at least one of said acoustic radiators (4) is made in the form of a vibrating strip (8) comprising a plate (16) inscribed in a parallelepiped, the maximum dimension of which is greater than or equal to 4mm, the minimum dimension of which is comprised between 0.05mm and 2mm, and the third dimension of which is greater than or equal to 2 mm.

22. A method according to claim 1, characterized in that at least one of the acoustic radiators (4) comprises a vibration strip (8), the vibration strip (8) comprising a plate (16) with a radius of curvature greater than 0.5 mm.

23. A method according to claim 1, characterized in that at least one acoustic radiator (4) is made of gold or a noble metal or silicon or ceramic or metallic glass or steel or titanium.

24. An external part (3) for a musical or striking timepiece (1), said external part (3) carrying at least one vibration generator (2) vibrating at a specific generator natural frequency, wherein said external part (3) comprises at least one acoustic radiator (4) comprising at least one element vibrating-radiating at a radiator natural frequency tuned to at least one of the generator natural frequencies of the timepiece (1); wherein the outer part (3) comprises a watch case (10) surrounding at least one middle part (5), at least one of the acoustic radiators (4) being fixed to the middle part (5) or to the watch case (10); characterized in that at least one of the acoustic radiators (4) is connected to the middle part (5) or to the watch case (10) by means of a single attachment foot (7) included in the acoustic radiator (4) carrying at least one vibration strip (8).

25. External part (3) according to claim 24, characterized in that the external part (3) comprises at least one of the acoustic radiators (4) either outside the middle part (5) of the watch case or inside the watch case (10).

26. The outer part (3) according to claim 24, characterized in that the outer part (3) comprises a plurality of said acoustic radiators (4), wherein at least a part of the acoustic radiators (4) have different radiator natural frequencies from each other.

27. An external part (3) for a musical or striking timepiece (1), said external part (3) carrying at least one vibration generator (2) vibrating at a specific generator natural frequency, wherein said external part (3) comprises at least one acoustic radiator (4) comprising at least one element vibrating-radiating at a radiator natural frequency tuned to at least one of the generator natural frequencies of the timepiece (1); and wherein the outer part (3) comprises a watch case (10) surrounding at least one middle part (5), at least one of the acoustic radiators (4) being fixed to the middle part (5) or to the watch case (10); characterized in that at least one of the acoustic radiators (4) comprises at least one vibration strip (8) cut out from the middle part (5), the vibration strip (8) being connected to the middle part (5) by a single end (9) of the vibration strip (8).

28. External part (3) according to claim 27, characterized in that the external part (3) comprises at least one of the acoustic radiators (4) either outside the middle part (5) of the watch case or inside the watch case (10).

29. External part (3) according to claim 27, characterized in that at least one of the acoustic radiators (4) is connected to the middle part (5) or to the middle part (10) of the watch case by means of a single attachment foot (7) included in the acoustic radiator (4) carrying at least one vibration strip (8).

30. The outer part (3) according to claim 27, characterized in that the outer part (3) comprises a plurality of said acoustic radiators (4), wherein at least a part of the acoustic radiators (4) have different radiator natural frequencies from each other.

31. Timepiece (1) which is a striking watch and/or a musical box watch, characterized in that it comprises an external part (3) according to claim 24 or 27, and/or a movement (17) carrying at least one vibration generator (2) vibrating at a specific generator natural frequency, said movement (17) comprising at least one acoustic radiator (4) comprising at least one element vibrating-radiating at a radiator natural frequency tuned to at least one of said generator natural frequencies.