Acoustic device for a striking timepiece

Abstract

The invention relates to an acoustic device (10) for a ringing member, comprising: an acoustic membrane (20); at least one piezoelectric element (30, 30a, 30b, 30c, 32) arranged to cooperate with the acoustic membrane (20); and at least one electrical circuit (40a, 40b) integrated with a piezoelectric element. The acoustic device (10) further comprises at least one spring strip (12, 14) that can be struck by a hammer. Comprising a piezoelectric element (30, 30a, 30b, 30) and a circuit (40a, 40b) is configured to adjust the resonant frequency of the acoustic membrane (20) in accordance with the resonant frequency of the at least one spring strip (12, 14). The invention also relates to a sounding member, in particular a timepiece, comprising said acoustic device (10).

Description

(19) State Intellectual Property Office (12) Invention Patent Application (10) Application Publication Number (43) Application Publication Date (21) Application Number 202480045610.5 (22) Application Date 2024.06.18 (30) Priority Data 23183868.1 2023.07.06 EP (85) PCT International Application Entering National Phase Date 2026.01.05 (86) PCT International Application Application Data PCT / IB2024 / 055926 2024.06.18 (87) PCT International Application Publication Data WO2025 / 008699 FR 2025.01.09 (71) Applicant Audemars Piguet Watches Manufacturing Ltd. Address Leblanc, Switzerland (72) Inventor N. Robusch A. Toue A. Pinat (74) Patent Agency China Patent Agency (Hong Kong) Ltd. 72001 Patent Attorney Liu Shuhang Lu Jiang (51) Int.Cl. G04C 21 / 04 (2006.01) G04C 21 / 12 (2006.01) G04C 21 / 20 (2006.01) G04C 21 / 28 (2006.01) G10K 9 / 122 (2006.01) G04C 21 / 30 (2006.01) G04C 21 / 36 (2006.01) (54) Title of Invention Acoustic Device for Sounding Components (57) Abstract This invention relates to an acoustic device (10) for sounding components, comprising: an acoustic diaphragm (20); at least one piezoelectric element (30; 30a, 30b; 30c;) arranged to cooperate with the acoustic diaphragm (20). 32); and at least one circuit (40a, 40b) integrating a piezoelectric element. The acoustic device (10) also includes at least one spring (12, 14) capable of being struck by a hammer. The assembly including the piezoelectric element (30; 30a, 30b; 30) and the circuit (40a, 40b) is configured to adjust the resonant frequency of the acoustic diaphragm (20) according to the resonant frequency of the at least one spring (12, 14). The invention also relates to a sounding component including the acoustic device (10), particularly a timepiece.Claims 2 pages, Description 6 pages, Drawings 5 ​​pages, CN 121444023 A 2026.01.30 CN 1 21 44 40 23 A 1. An acoustic device (10) for a humming component, comprising: an acoustic diaphragm (20); at least one piezoelectric element (30; 30a, 30b; 30c; 32) arranged to cooperate with said acoustic diaphragm (20); and at least one circuit (40a, 40b) integrating the piezoelectric element, characterized in that the acoustic device (10) further comprises at least one spring (12, 14) capable of being struck by a hammer, and the assembly including the piezoelectric element (30; 30a, 30b; 32) and the circuit (40a, 40b) is configured to adjust the resonant frequency of said diaphragm (20) according to the resonant frequency of said at least one spring (12, 14). 2. The acoustic device (10) of claim 1, wherein each piezoelectric element (30; 30a, 30b) is deployed in direct contact with the acoustic diaphragm (20) and preferably has a shape that at least partially complements the shape of the acoustic diaphragm (20). 3. The acoustic device (10) of claim 2, wherein the acoustic diaphragm (20) is circular, and the at least one piezoelectric element (30a, 30b, 30c) is circular or partially circular. 4. The acoustic device (10) of claim 3, wherein the at least one piezoelectric element (30c) has a shape that is at least partially annular and is arranged at least partially along the outer periphery of the acoustic diaphragm (20) to modulate the resonant frequency of the diaphragm (20) when the diaphragm (20) is subjected to radial stress due to the at least one piezoelectric element (30c). 5. The acoustic device (10) as claimed in any one of claims 1 to 3, wherein at least one side of the acoustic diaphragm (20) is covered by at least one piezoelectric element to occupy at least 70% of its surface, preferably at least 80% of its surface, or even at least 90% of its surface. 6. The acoustic device (10) as claimed in any one of the preceding claims, comprising: at least one piezoelectric element (30; 30a, 30b; 30c; 32) configured to be powered by a power supply (60) integrated into the circuitry (40a, 40b) for operation in an active mode. 7. The acoustic device (10) as claimed in the preceding claim, wherein the power supply (60) is one or more other piezoelectric elements of the device (10). 8. The acoustic device (10) as claimed in claim 1 or 2 further includes a peripheral element (50) in contact with the acoustic diaphragm (20) through its periphery, wherein a piezoelectric element (32) is integrated into the peripheral element (50) such that any expansion or contraction of the piezoelectric element (32) applies a tension change to the acoustic diaphragm (20) to modulate its resonant frequency.9. The acoustic device (10) of any one of the preceding claims, comprising a plurality of springs (12, 14), wherein each spring is assigned a circuit, and the circuit has a suitable characteristic that allows adjustment of the resonant frequency of the diaphragm (20) according to the resonant frequency of the spring to which the circuit is assigned. 10. The acoustic device (10) of any one of the preceding claims, comprising a plurality of springs (12, 14), wherein each spring is assigned a piezoelectric element (30a, 30b), and the piezoelectric element (30a, 30b) has a suitable characteristic that allows adjustment of the resonant frequency of the diaphragm (20) according to the resonant frequency of the spring to which the piezoelectric element (30a, 30b) is assigned. 11. The acoustic device (10) of any one of the preceding claims, wherein the at least one circuit (40a, 40b) comprises: a switch (70) that allows opening or closing the circuit to respectively disconnect or activate the at least one piezoelectric element integrated therein. 12. An acoustic device (10) as claimed in any one of the preceding claims, wherein the piezoelectric element and circuitry are configured to further space the resonant frequency of the diaphragm and the resonant frequency of the spring strip. 13. A whistling timepiece comprising an acoustic device (10) as claimed in any one of claims 1 to 8 and hammers arranged to strike the spring strips (12, 14) of the acoustic device (10). 14. A whistling timepiece comprising: an acoustic device (10) as claimed in claim 9 or 10 and as claimed in claim 11; and a plurality of hammers arranged to strike corresponding spring strips, wherein a switch (70) is driven by the movement of the hammers or a whistling actuation element. 15. A whistling timepiece as claimed in claim 13 or 14, wherein at least one piezoelectric element (30; 30a, 30b; 30c; 32) is arranged on the surface of the acoustic diaphragm (20) facing the spring strips (12, 14). Claims 2 / 2 Page 3 CN 121444023 A Acoustic Device for a Sounding Component Technical Field

[0001] The present invention relates to an acoustic device for a sounding component, comprising a diaphragm whose resonant frequency is adjustable by the piezoelectric effect. The present invention also relates to a sounding component comprising such an acoustic device, particularly a timepiece. Background Art

[0002] Sounding components of the grande sonnerie or minute repeater type, and particularly sounding timepiece components, are known. For example, CH714635 and EP2942675 disclose a sounding timepiece component comprising: a watch case housing an acoustic diaphragm; and a timepiece movement equipped with a sounding mechanism. The mechanism comprises at least one spring and a hammer for striking the spring.The sound generated by the hammer striking the spring bar causes the spring bar and diaphragm to vibrate, which contributes to the sound transmission between the inside and outside of the watch case.

[0003] A disadvantage of the above-described timepiece components is that the acoustic diaphragm operates under forced conditions and does not resonate. Therefore, the diaphragm is not utilized to its full potential.

[0004] Watches also exist that include an acoustic diaphragm associated with a piezoelectric element to adjust the resonant frequency of the acoustic diaphragm. For example, FR2466903 discloses a mechanical watch equipped with an assembly consisting of an acoustic diaphragm and a piezoelectric element. According to one operating mode, the piezoelectric element is controlled by electronic circuitry to cause the acoustic diaphragm to vibrate to produce an audible sound. The watch also includes a mechanism for adjusting the resonant frequency of the acoustic diaphragm. This mechanism is mounted on the bottom of the case and includes a rotating arm that contacts the diaphragm and is movable to adjust its resonant frequency. This allows modification of the frequency of the diaphragm-piezoelectric element assembly to amplify the sound.

[0005] A disadvantage of the above-described mechanical watches is that the quality of the emitted sound depends in part on the characteristics of the acoustic diaphragm.

[0006] The object of the present invention is therefore to provide an acoustic device for a phonograph component so that the phonograph component can produce a better quality sound.

[0007] Another object of the present invention is to provide an acoustic device for a phonograph component that allows the phonograph component to attenuate the sound amplitude to obtain a soft mode. Summary of the Invention

[0008] At least some of these objects are achieved, in particular, by an acoustic device for a phonograph component comprising: an acoustic diaphragm; at least one piezoelectric element arranged to cooperate with the acoustic diaphragm; and at least one circuit, particularly by means of electrodes typically formed by its largest surface, on which the piezoelectric element is integrated. The acoustic device also includes at least one spring bar capable of being struck by a hammer. The assembly including the piezoelectric element and the circuit is configured to adjust the resonant frequency of the diaphragm according to the resonant frequency of the at least one spring bar.

[0009] According to an embodiment, each piezoelectric element is deployed to be in direct contact with the acoustic diaphragm and preferably has a shape that at least partially complements the shape of the acoustic diaphragm.

[0010] According to an embodiment, the acoustic diaphragm is circular in shape. The piezoelectric element is circular or partially circular in shape.

[0011] According to an embodiment, at least one piezoelectric element has at least a partially annular shape. The piezoelectric element is arranged along at least a portion of the outer periphery of the acoustic diaphragm. This allows the resonant frequency of the diaphragm to be modulated when the diaphragm is stressed radially due to the piezoelectric element.

[0012] According to an embodiment, at least one surface of the acoustic diaphragm is covered by at least one piezoelectric element to occupy at least 70% of its surface, preferably at least 80% of its surface, or even at least 90% of its surface.

[0013] According to an embodiment, the acoustic device includes: at least one piezoelectric element configured to be powered by a power source integrated into the circuit for operation in an active mode.

[0014] According to an embodiment, the power supply is constituted by one or more other piezoelectric elements of the acoustic device.

[0015] According to an embodiment, the acoustic device further includes a peripheral element that contacts the acoustic diaphragm through its periphery. The piezoelectric element is integrated into the peripheral element such that any expansion or contraction of the piezoelectric element applies a tension change to the acoustic diaphragm to modulate its resonant frequency.

[0016] According to an embodiment, the acoustic device includes a plurality of springs. A circuit is assigned to each spring, and the circuit has suitable characteristics that allow adjustment of the resonant frequency of the diaphragm according to the resonant frequency of the spring to which the circuit is assigned.

[0017] According to an embodiment, the acoustic device includes a plurality of springs. A piezoelectric element is assigned to each spring, and the piezoelectric element has suitable characteristics that allow adjustment of the resonant frequency of the diaphragm according to the resonant frequency of the spring to which the piezoelectric element is assigned.

[0018] According to an embodiment, at least one circuit includes: a switch that allows the circuit to be opened or closed to disconnect or activate the at least one piezoelectric element integrated therein, respectively.

[0019] According to an embodiment, the assembly including the piezoelectric element and the circuit is configured to further space the resonant frequency of the diaphragm and the resonant frequency of the spring strip.

[0020] Another aspect of the invention relates to a striking timepiece component, comprising: the acoustic device; and a hammer arranged to strike a spring strip of the acoustic device.

[0021] Another aspect of the invention relates to a striking timepiece component, comprising: the acoustic device equipped with a plurality of spring strips; and a plurality of hammers arranged to strike corresponding spring strips. A switch is driven by the movement of the hammers or a striking actuation element.

[0022] According to an embodiment, the at least one piezoelectric element is arranged on the surface of the diaphragm facing the spring strip.

[0023] Embodiments of the invention are indicated in the accompanying figures in the description, in which: - FIG1 illustrates, in association with a spring bar, a perspective view of an acoustic device intended for mounting in a striking timepiece according to an embodiment; - FIG2 illustrates an equivalent circuit including a piezoelectric element and a control circuit including a switch; - FIG3 schematically illustrates a watch case including an acoustic device of the embodiment illustrated in FIG1 or any of the embodiments described below; - FIG4a and FIG4b illustrate two circuits integrating piezoelectric elements according to two embodiments; - FIG5 illustrates a plan view of FIG1 with a circuit diagram including an energy source according to an embodiment containing a variation; - FIG6 illustrates a plan view of an acoustic device for a timepiece according to another embodiment containing a variation; - FIG7 illustrates a cross-sectional view of the acoustic device of FIG6; - FIG8 illustrates, together with the spring bar, a plan view of an acoustic device for a timepiece according to another embodiment; - FIG9 is a cross-sectional view of FIG8; - Figure 10 illustrates a schematic diagram of an acoustic device for a timepiece according to another embodiment, and Figure 11 is a graph showing the resonant frequencies of the springs and acoustic diaphragms of the timepiece when the sound amplitude generated by the spring-diaphragm-circuit assembly is in attenuation, non-optimal, and optimal modes. Detailed Description

[0024] According to an embodiment, and referring to Figures 1 and 3, the acoustic device 10 is intended to be mounted in a whistling component. The whistling component is intended to encompass any whistling or musical component, such as a whistling timepiece component, a music box, an automaton, or other mechanical or semi-mechanical component configured to generate whistling and / or music. The embodiments used as examples in this description refer to the whistling timepiece component in a non-limiting manner.

[0025] The timepiece component may be, in particular, of the full self-ringing or minute repeater type, comprising one or more springs 12, 14. Typically, the device 10 functions primarily as a partition, dividing the internal chamber 6 of the timepiece components to form a sealed chamber 16 and an acoustic cavity 8. Chamber 16 encloses the timepiece movement equipped with a striking mechanism. The acoustic cavity 8 includes a through-hole 9 for diffusing sound generated by the striking mechanism from the interior of the watch case 100 to the exterior.

[0026] In this example, the acoustic device 10 generally has a bowl-shaped form with edges forming a fixing flange 11. The central portion of the partition constitutes an acoustic diaphragm 20, on which, for example, a first piezoelectric element 30a and a second piezoelectric element 30b are deployed, as illustrated in FIG. 1. The acoustic diaphragm 20 can be made, for example, of titanium—a material with the advantage of having a relatively low modulus of elasticity and ideal for transmitting acoustic waves.According to a variant, for aesthetic reasons, a sapphire crystal film may be used so that the user of the timepiece can at least partially see the timepiece movement, especially during the operation of the striking mechanism, on the bottom side of the watch case.

[0027] In the example illustrated in FIG1, the acoustic device 10 may also include a bushing 15 connected to a fixed flange 11 and thereon fixed a first spring 12 and a second spring 14 intended to be struck by a first hammer and a second hammer (not shown) of the striking mechanism of the timepiece, respectively. In this way, such a device is typically able to produce two sounds of different tones, such as a low sound and a high sound. The acoustic device 10 can therefore be adapted, in particular, for minute repeater timepieces so as to indicate the hour by a low sound, the quarter-hour by a high-low sequence, and the minute by a high sound when needed.

[0028] The bushing 15 or the assembly consisting of the springs 12, 14 and the bushing 15 is not necessarily part of the acoustic device 10. Preferably, the acoustic device comprises only: an acoustic diaphragm; at least one piezoelectric element arranged to cooperate with the diaphragm; at least one circuit integrating the piezoelectric element; and a frame for securing the acoustic device close to the striking mechanism of the timepiece component equipped with at least one spring within the watch case. The frame is adapted to support the various elements of the acoustic device described above.

[0029] According to an implementation variant not shown, the timepiece component including the acoustic device 10 may comprise only a single spring. According to another implementation variant not shown, the timepiece component including the acoustic device 10 may comprise more than two springs, such as three, four, or even five springs. This type of timepiece component is called a carillon and may, for example, comprise three, four, or five beats of three, four, and five notes played at different frequencies. In the most melodic models, the device therefore requires a larger number of springs and hammers, i.e., three, four, or even five springs and hammers.

[0030] According to the embodiment of FIG. 1, the acoustic device 10 further includes a first circuit and a second circuit, respectively integrating a first piezoelectric element 30a and a second piezoelectric element 30b. The device 10 is thus adapted for a timepiece having two spring bars 12, 14.

[0031] In order to maximize the magnitude of the mechanical stress applied to the acoustic diaphragm 20 by the two piezoelectric elements 30a, 30b, at least one side of the acoustic diaphragm is covered by the two piezoelectric elements to occupy at least 70%, preferably at least 80%, or even at least 90% of its surface. According to a variant of implementation not shown, a single piezoelectric element is deployed on one side of the acoustic diaphragm and covers it according to the above proportions.

[0032] The piezoelectric elements or each piezoelectric element 30a, 30b preferably have a shape that at least partially complements the shape of the acoustic diaphragm.The acoustic diaphragm 20 may have a circular shape, while the piezoelectric elements or each piezoelectric element 30a, 30b may have a circular or partially circular shape. For example, both piezoelectric elements 30a, 30b may each have a semi-circular shape including straight edges facing each other, as illustrated in FIG1. ​​

[0033] According to an embodiment, the characteristics of the first circuit 40a, preferably at least related to its impedance z, are selected according to at least one resonant frequency of the first spring 12. The selection of the impedance of the first circuit thus allows the resonant frequency of the diaphragm 20 to be adjusted by exciting the first piezoelectric element 30a according to the resonant frequency of the first spring 12. As with the first circuit, the characteristics of the second circuit 40b, preferably at least related to its impedance, are selected according to at least one resonant frequency of the second spring 14. The selection of the impedance of the second circuit, which is different from the impedance of the first circuit, thus allows the resonant frequency of the diaphragm 20 to be adjusted by exciting the second piezoelectric element 30b according to the resonant frequency of the second spring 14.

[0034] According to FIG. 5, each of the first circuit 40a and the second circuit 40b includes a mechanically connected switch 70a, 70b such that when one is open, the other is closed, thus forming a switcher. The first circuit 40a and the second circuit 40b are thus able to alternately excite, arouse, or activate the first piezoelectric element 30a and the second piezoelectric element 30b to adjust the resonant frequency of the acoustic diaphragm 20 according to the resonant frequency of the spring strip that will be struck by a hammer corresponding to the striking mechanism of the timekeeping component of the integrated acoustic device 10.

[0035] When the first circuit 40a and the second circuit 40b are open and closed, respectively, the arousal or activation of the first piezoelectric element 30a will modify the stiffness of the acoustic diaphragm 20 according to the resonant frequency of the first spring strip 12 and thus modulate its resonant frequency, while the second piezoelectric element is inactive. Conversely, when the first circuit 40a and the second circuit 40b are closed and open respectively, the excitation or activation of the second piezoelectric element 30b modulates the stiffness of the acoustic diaphragm 20 according to the resonant frequency of the second spring 12 and thus modulates its resonant frequency, while the first piezoelectric element 30a is inactive.

[0036] This results in a significant gain in the acoustic intensity of the sound generated by the vibration caused by the first and second springs being struck by a hammer associated with the spring of the striking mechanism of the timekeeping component. The switches 70a, 70b of each circuit 40a, 40b can be switched directly or indirectly, for example, by the corresponding movement of the first and second hammers of the timekeeping component, so as to modify the stiffness of the acoustic diaphragm according to the spring that will be struck by the associated hammer. A gain in clarity can also be obtained by modulating at least one of the resonant frequencies of the acoustic diaphragm to the fundamental frequency of the two springs.

[0037] Referring to FIG11, the sound amplitude of the spring-diaphragm system is optimal when the resonant frequency of the diaphragm corresponds to the resonant frequency of the spring.Although it is difficult to modify the stiffness of the acoustic diaphragm so that its resonant frequency corresponds precisely to the resonant frequency of the spring strip, making them close still allows for a significant gain in acoustic intensity.

[0038] According to a variant of implementation, the first circuit 40a and the second circuit 40b are identical in nature, while the corresponding properties of the first piezoelectric element 30a and the second piezoelectric element 30b are different, so that their excitation by the first circuit 40a, and correspondingly by the second circuit 40b, allows the resonant frequency of the acoustic diaphragm 20 to be adjusted according to the corresponding resonant frequencies of the first spring strip 12 and the second spring strip 14. The properties of each piezoelectric element 30a, 30b can be selected from, in particular, one or a combination of the following properties: the capacitance of the piezoelectric element, its contact surface with the acoustic diaphragm, its thickness, and its mass.

[0039] According to another implementation variant, the properties of the first circuit 40a and the second circuit 40b, as well as the properties of the first piezoelectric element 30a and the second piezoelectric element 30b, are also selected so that the excitation of the piezoelectric element by the circuit for itself can modulate the resonant frequency of the acoustic diaphragm so that these frequencies are as close as possible to the resonant frequency of the spring to which the piezoelectric element is associated.

[0040] In a general manner, for acoustic devices intended to be integrated into timepieces whose sounding mechanism comprises only one spring or (for the most melodic glockenspiel timepieces) three, four, or even five springs, the selection of the properties of each circuit and the selection of the properties of the piezoelectric element associated with the circuit of the acoustic device as described above are transposable. In this case, the acoustic device may include three, four, or five circuits associated with a common piezoelectric element or respectively associated with one of three, four, or five different piezoelectric elements.

[0041] More particularly, for timepieces whose sounding mechanism comprises only one spring, the nature of the circuit, especially its impedance z and / or the nature of the piezoelectric element (e.g., the capacitance of the piezoelectric element, its contact surface with the acoustic diaphragm, its thickness and / or its mass) is determined based on at least one resonant frequency of the spring. For timepieces whose sounding mechanism comprises three, four, or even five springs, the nature of the three, four, or five circuits and / or the nature of each piezoelectric element or common piezoelectric element associated with each spring is selected in a similar manner based on the corresponding resonant frequencies of the third, fourth, and fifth springs.

[0042] Figures 4a and 4b illustrate two different circuits, both of which integrate piezoelectric elements. For example, a variation in the capacitance value of the circuit in Figure 4a allows modification of the diaphragm's stiffness. Conversely, the circuit in Figure 4b is adapted to attenuate the vibration 20 of the acoustic diaphragm by dissipating electrical energy generated in the circuit's resistance. This allows the acoustic device 10 to be configured in a low-noise mode.In this case, the user can activate the piezoelectric element or each piezoelectric element by means of a switch, for example, implemented using a button, to eliminate or at least attenuate the sound emitted by the acoustic device. According to this operating mode, the stiffness of the acoustic diaphragm is modified so that its resonant frequency is as far away as possible from the resonant frequency of the spring, as schematically illustrated in Figure 11.

[0043] In cases where piezoelectric elements or each piezoelectric element are used to amplify the vibration of the diaphragm to obtain a gain in acoustic intensity, and where the user wishes to disable the piezoelectric effect on the diaphragm to obtain a weaker sound, the circuitry of the acoustic device 10 may also include a switch. In the disabled mode, the sound transmission mode corresponds to the sound transmission mode of a conventional striking timepiece component. Conversely, if the user desires greater gain, the circuitry of the acoustic device may include an energy source 60, which allows the piezoelectric element or each piezoelectric element to operate in an active mode to apply greater stress to the diaphragm.

[0044] The energy source 60, mounted in the watch case of the timepiece component, can typically take the form of a battery, a micro-generator, a capacitor, or any combination of these elements. For example, a micro-generator can be installed to partially convert the mechanical energy generated from the user's action on a pin designed to wind the spring of the mainspring barrel of the striking mechanism.

[0045] According to another embodiment and referring to Figures 6 and 7, the acoustic device 10 includes: an acoustic diaphragm 20; a piezoelectric element 30 having at least a partially annular shape and arranged along at least a portion of the outer periphery of the diaphragm 20; and a frame connected to the diaphragm and provided with or constituted by a fixing flange 11 for assembling the acoustic device in a watch case.

[0046] This particular arrangement allows modulation, and in particular reduction, of the resonant frequency of the diaphragm 20 when it is subjected to radial stress due to the deformation of the piezoelectric element 30. Preferably, the piezoelectric element 30 is in the form of a ring mounted against the circular edge of the acoustic diaphragm 20 in its plane. Vibration of the diaphragm 20 polarizes the piezoelectric ring 30, which exerts radial stress on the diaphragm through its deformation. Preferably, the piezoelectric ring is powered by an energy source 60 to enable operation in an active mode.

[0047] According to another embodiment illustrated in Figures 8 and 9, the acoustic device 10 includes: an acoustic diaphragm 20; and a piezoelectric element 30c, which also has at least a partially annular shape and is arranged along at least a portion of the outer periphery of the diaphragm 20. Preferably, the annular piezoelectric element is arranged in the same or similar manner as in the embodiments described above. The piezoelectric ring 30c may be intended to operate in either a passive or active mode.

[0048] For this purpose, the acoustic device 10 also includes at least one or more piezoelectric elements 30a, 30b, which, as particularly in the embodiment illustrated in Figure 1, are deployed on one surface of the acoustic diaphragm 20 to cover at least 70% of its surface, preferably at least 80% of its surface, or even at least 90% of its surface.In active mode, the piezoelectric element or each piezoelectric element 30a, 30b is electrically connected to the piezoelectric ring 30c.

[0049] Thus, when the striking mechanism of the timing component is actuated, the acoustic diaphragm 20 vibrates under the action of the vibration generated when the hammer strikes the spring bar, which allows the piezoelectric element or each piezoelectric element 30a, 30b to generate electricity to power the piezoelectric ring 30c. The active mode allows greater stress to be applied to the acoustic diaphragm 20 from the outer periphery of the acoustic diaphragm 20. Thus, the stiffness of the acoustic diaphragm 20 can vary over a wider range. Therefore, the reduction in the resonant frequency of the acoustic diaphragm 20 can be greater compared to the embodiment operating in passive mode.

[0050] According to any of the above embodiments, the piezoelectric element or each piezoelectric element 30a, 30b can be in the form of a thin layer, for example, on the order of tens or hundreds of micrometers, typically on the order of 0.2 mm or even greater. These layers are fixed to at least one surface of the acoustic diaphragm 20, preferably to the surface on the spring side. The piezoelectric layers 30a, 30b can be fixed, for example, by adhesive bonding. Alternatively, the piezoelectric layers 30a, 30b can be deposited using CVD or PVD processes. The piezoelectric layers 30a, 30b can be made of different materials, particularly quartz, ferroelectric oxides, or III-V semiconductors.

[0051] The piezoelectric element or each piezoelectric element 30a, 30b can typically include two electrodes of opposite polarity. For example, when the piezoelectric element is in the form of a thin layer, these electrodes can be in the form of plates deployed on two opposite surfaces of the piezoelectric element.

[0052] According to another embodiment illustrated in FIG. 10, the acoustic device 10 includes: an acoustic diaphragm 20; and a peripheral element 50 connected to the acoustic diaphragm 20 via its periphery. The peripheral element can, for example, be in the form of an annulus 50 surrounding the acoustic diaphragm 20 and connected to the acoustic diaphragm 20 via a fixing member 34. The acoustic device 10 also includes a piezoelectric element 32, which is integrated in the annulus such that any expansion of the piezoelectric element 32 applies an increase in tension on the acoustic diaphragm 20, resulting in an increase in its resonant frequency. Conversely, contraction of the piezoelectric element will compress the diaphragm and result in a decrease in its resonant frequency. In a general sense, it can be said that any expansion or contraction of the piezoelectric element applies a change in tension on the acoustic diaphragm, allowing modulation of its resonant frequency.

[0053] The piezoelectric element 32 may be intended to operate in a passive or active mode. It may be powered, for example, by an energy source 60 (such as the energy source already mentioned) or at least one other piezoelectric element of the acoustic device 10.

[0054] Although the outline of the diaphragm is circular according to the illustrated embodiment, it may have other shapes. In this case, the shape and deployment of at least one piezoelectric element on the diaphragm will therefore be adapted to maximize the contact area between the piezoelectric element and the diaphragm.

[0055] Various modifications can be made to the above-described implementation without departing from the scope of the invention as defined by the appended claims. For example, the partition that functions as a frame intended to be fixed in the watch case can take different forms. Furthermore, as mentioned above, the springs or each spring can be connected to a striking mechanism in the watch case of the chronograph component instead of being connected to an acoustic device as illustrated in the figures. (Figures 1-5 are listed below.)

Claims

1. An acoustic device (10) for a sounding member, comprising: an acoustic a membrane (20); at least one piezoelectric element (30; 30a, 30b; 30c; 32) arranged to cooperate with said acoustic membrane (20; 2. The acoustic device (10) of claim 1, wherein each piezoelectric element (30; 30a, 30b) is deployed in direct contact with said acoustic membrane (20) and preferably has a shape at least partly complementing the shape of said acoustic membrane (20).

3. The acoustic device (10) of claim 2, wherein said acoustic membrane (20) is circular in shape and said at least one piezoelectric element (30a, 30b, 30c) is circular in shape or partly circular in shape.

4. The acoustic device (10) of claim 3, wherein said at least one piezoelectric element (30c) has an at least partly annular shape and is arranged along at least part of the periphery of said acoustic membrane (20) to modulate the resonance frequency of said membrane (20) when it is stressed in the radial direction by said at least one piezoelectric element (30c).

5. The acoustic device (10) of one of claims 1 to 3, wherein at least one face of said acoustic membrane (20) is covered by at least one piezoelectric element to occupy at least 70% of its surface, preferably at least 80% of its surface, even at least 90% of its surface.

6. An acoustic device (10) as claimed in one of the preceding claims, comprising: at least one piezoelectric element (30; 30a, 30b; 30c; 32) configured to be powered by a power supply (60) integrated to the circuit (40a, 40b) so as to operate in an active mode.

7. The acoustic device (10) of the preceding claim, wherein the power supply (60) is one or more other piezoelectric elements of said device (10).

8. The acoustic device (10) of claim 1 or 2, further comprising a peripheral element (50) in contact with said acoustic membrane (20) by its periphery, a piezoelectric element (32) being integrated to the peripheral element (50) so that any expansion or contraction of the piezoelectric element (32) exerts a change in tension on said acoustic membrane (20) to modulate its resonance frequency.

9. The acoustic device (10) of one of the preceding claims, comprising a plurality of reeds (12, 14), wherein each reed is assigned a circuit and the circuit has appropriate properties allowing to modulate the resonance frequency of said membrane (20) according to the resonance frequency of the reed to which the circuit is assigned.

10. Acoustic device (10) according to one of the preceding claims, comprising a plurality of reeds (12, 14), wherein a piezoelectric element (30a, 30b) is assigned to each reed, and the piezoelectric elements (30a, 30b) have suitable properties allowing to adjust the resonance frequency of the membrane (20) in dependence of the resonance frequency of the reed to which the piezoelectric element (30a, 30b) is assigned.

11. The acoustic device (10) according to one of the preceding claims, wherein the at least one circuit (40a, 40b) comprises: - a switch (70) allowing to open or close the electric circuit to disconnect or activate the at least one piezoelectric element integrated therein, respectively.

12. Acoustic device (10) according to one of the preceding claims, wherein the assembly comprising the piezoelectric element and the electric circuit is configured to space the resonance frequency of the membrane and the resonance frequency of the reed more apart.

13. A striking timepiece member comprising an acoustic device (10) according to one of claims 1 to 8 and a hammer arranged to strike the reed (12, 14) of the acoustic device (10).

14. A chiming timepiece component comprising: - an acoustic device (10) according to claim 9 or 10 and according to claim 11 ; and a plurality of hammers arranged to strike the respective reeds, and wherein the switch (70) is driven by the movement of the hammers or a striking activation element.

15. Striking timepiece member according to claim 13 or 14, wherein the at least one piezoelectric element (30; 30a, 30b; 30c; 32) is arranged on the face of the acoustic membrane (20) facing the reed (12, 14).

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