Piezoelectric actuation device with improved robustness

Abstract

This presentation relates to a piezoelectric actuation device comprising: a housing defining a cavity; a support comprising a deformable wall in bending and a rigid rim surrounding the deformable wall, the housing being delimited by said rim and the deformable wall; a rigid push button positioned in the upper housing, and configured to move between a free position and a constrained position in which the deformable wall is deformed towards the lower cavity; a piezoelectric element integral with the housing, inside the internal cavity; and a printed circuit board housed in the lower cavity and electrically connected to the piezoelectric element. Figure for the abstract: Fig. 3

Description

Title of the invention: Piezoelectric actuation device with improved robustness Technical field

[0001] The present invention relates to a waterproof and robust piezoelectric actuation device. More specifically, the invention relates to an actuation device operating in an environment subject to meteorological and physical disturbances which may disrupt normal operation. STATE OF THE ART

[0002] Piezoelectric actuation devices are used in many applications, for example human-machine interfaces.

[0003] These actuating devices are based on the application of dynamic pressure to a piezoelectric element, the deformation of which results in the generation of an electrical voltage.

[0004] However, these actuating devices can be used on devices subject to significant shocks, acts of deliberate damage or bad weather such as rain, frost or high heat. Such events can cause malfunctions of these actuating devices, disturbances in the generation of electrical voltage or a fracture of an element constituting the actuating device.

[0005] Document FR 2 893 353 A1, in the name of the applicant, proposes a piezoelectric actuation device comprising a housing, an actuation wall and a piezoelectric element arranged in the housing.

[0006] However, such a device cannot withstand significant impacts without breaking or deteriorating, the actuating wall being deformable, as is the part of the housing in contact with the piezoelectric element.

[0007] Furthermore, there is a significant need for sealing piezoelectric actuation devices in order to prevent any infiltration of water which could have consequences on the electrical operation of the switch but also on its deformation, in the event of frost. GENERAL STATEMENT

[0008] One purpose of the disclosure is to solve at least one of the aforementioned problems.

[0009] To this end, according to one aspect of the present disclosure, there is provided a piezoelectric actuation device comprising: - a housing defining a cavity, - a support separating the cavity into an upper housing and a lower cavity, the support comprising a wall deformable in flexion and a rigid rim surrounding the deformable wall, the housing being delimited by said rim and the deformable wall; - a rigid push button positioned in the upper housing, and configured to move between a free position and a constrained position in which the deformable wall is deformed towards the lower cavity; - a piezoelectric element secured to the housing, inside the internal cavity; and - a printed circuit housed in the lower cavity and electrically connected to the piezoelectric element.

[0010] This piezoelectric actuating device makes it possible to protect the flexible upper wall of the housing from excessive pressure. Indeed, from a certain applied pressure, the rigidity of the actuating device and the shoulder provided in the housing prevent greater bending of the flexible part of the housing.

[0011] In addition, the actuating device has significant robustness while allowing deformation of the piezoelectric element in order to generate a signal.

[0012] Advantageously, but optionally, the method described comprises at least one of the following characteristics, taken alone or in any combination:

[0013] - the button is irremovably connected to the deformable wall of the support;

[0014] - the deformable wall comprises an upper face and the button comprises a face contact opposite the upper face, the upper face and the contact face being spaced from each other, when the button is in the free position, by at least a first pin extending from the upper face or from the contact face;

[0015] - the upper face of the deformable wall comprises a tubular pin and the button includes a complementary groove of the pin, such that the groove of the button engages in the pin of the deformable wall;

[0016] - the device comprises a light source arranged in the lower cavity;

[0017] - the support is translucent and comprises an extension extending longitudinally in the housing from the rim to an upper edge of the housing, the extension surrounding the button, such that the holder guides the light emitted by the light source to the upper edge of the housing;

[0018] - the device comprises a seal positioned between the button and the wall deformable;

[0019] - the piezoelectric element is fixed against the deformable wall by a pad double-sided adhesive;

[0020] - the electrical connection between the printed circuit and the piezoelectric element is provided respectively by a first and a second compression spring, cy- revolution lindrics and arranged in the internal cavity between the printed circuit and the piezoelectric element; the first and second springs having coincident axes of symmetry and the second spring being arranged inside the first spring;

[0021] - a part of the internal cavity is sealed by a layer of resin. DESCRIPTION OF FIGURES

[0022] Other characteristics, aims and advantages will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which:

[0023] [Fig.l] illustrates an exploded view of a piezoelectric actuator device according to an embodiment of the present disclosure;

[0024] [Fig.2] illustrates an axial section of a piezoelectric actuator device according to an embodiment of the present disclosure;

[0025] [Fig. 3] illustrates an axial section of a piezoelectric actuation device according to a particular embodiment of the present disclosure;

[0026] [Fig.4] illustrates an exploded view of a luminous piezoelectric actuator device according to an embodiment of the present disclosure;

[0027] [Fig.5] illustrates an axial section of a luminous piezoelectric actuation device according to an embodiment of the present disclosure.

[0028] Throughout the figures, identical elements bear identical references. DETAILED DESCRIPTION OF EMBODIMENTS

[0029] In the following description and unless otherwise specified, an axial direction corresponds to the direction of the longitudinal axis X, which is the direction of actuation of the device, and a radial direction is a direction perpendicular to the longitudinal axis X and intersecting the longitudinal axis X. Furthermore, an axial plane is a plane containing the longitudinal axis X and a radial plane is a plane perpendicular to the longitudinal axis X. A circumference is understood to be a circle belonging to a radial plane and whose center belongs to the longitudinal axis X. A tangential or circumferential direction is a direction tangent to a circumference: it is perpendicular to the longitudinal axis X but does not pass through the longitudinal axis X.We will call upper what is longitudinally on the side of a user with respect to the device and lower what is on the side opposite the user with respect to the device, in other words the side of the system to be controlled in which a device 1 is used. In the figures, the device is shown with its upper part at the top and its lower part at the bottom.

[0030] Furthermore, we will call deformable that which is capable of deforming elastically when pressure is exerted along the longitudinal axis X. More precisely, we will call deformable that which is capable of deforming in bending. And we will call rigid that which does not deform (or deforms by an amplitude less than a certain value less than that of the deformable element) under the application of the same force as that applied to the deformable element.

[0031] The piezoelectric actuation device 1 is for example a push button actuating a piezoelectric element. This device 1 is a modular device which can be used as such in a system to be controlled or else associated with other switches to form a switching device incorporated in a human-machine interface in a system to be controlled.

[0032] [Fig.l] illustrates the device 1 in exploded view along the longitudinal axis X. The device 1 comprises a housing 2 defining a cavity 23, and a push button 3, a push button support 4 (hereinafter simply called support), a piezoelectric element 5 and a printed circuit 6. The push button 3, the support 4, the piezoelectric element 5 and the printed circuit 6 are positioned in the cavity 23 of the housing.

[0033] The case

[0034] As illustrated by [Fig.2], the housing 2 houses the other components of the device 1. The housing 2 allows the other components of the device 1 to be fixed to the system to be controlled on which the device is implemented, such as, for example, a bicycle, a scooter, etc.

[0035] The housing 2 comprises a side wall 21 delimiting the cavity 23. The side wall 21 is preferably cylindrical and of circular section. It extends along the longitudinal axis X of a lower circular edge 213, forming a lower part of the device 1, and an upper edge 214, configured to be in contact with the outside. The upper edge extends in a plane orthogonal to the longitudinal axis X.

[0036] The side wall 21 comprises a concentric inner surface 211 and an outer surface 212. The side wall is rigid and non-deformable.

[0037] Preferably, the side wall 21 of the housing 2 comprises a rigid shoulder 24. The shoulder extends radially towards the inside of the cavity 23 of the housing from the internal surface 211 of the side wall 21 at least close to the upper edge 214.

[0038] According to a preferred embodiment, the shoulder 24 extends continuously around the longitudinal axis X. According to another embodiment, the shoulder extends discontinuously around the longitudinal axis X.

[0039] Advantageously, the shoulder of the housing allows the support to be positioned in the cavity 23.

[0040] The housing is preferably made of a metallic material.

[0041] Support

[0042] The support 4 is positioned in the housing 2, as illustrated in [Fig.2], in other words in the cavity 23. The support can advantageously rest on the shoulder of the housing, in other words on an upper part of the shoulder.

[0043] The support preferably forms an internal part of the side wall 21 of the housing 2 and extends all around the cavity 23 and over a longitudinal portion of the cavity 23.

[0044] The support comprises a cylinder 41 around the longitudinal axis forming a cavity, called the connection cavity 411. The connection cavity 411 of the support is configured to house the piezoelectric element 5 and the printed circuit 6.

[0045] The support further comprises an upper wall 42 called a deformable wall. The deformable wall 42 is positioned on the upper part of the cylinder 41 and closes the connection cavity 411.

[0046] The deformable wall 42 is a plate perpendicular to the longitudinal axis X and preferably in the shape of a disc whose center is located on the longitudinal axis X. The deformable wall comprises an external face 421 and an internal face 422.

[0047] Advantageously, the support comprises a rim 43 extending radially towards the housing from the cylinder, at the intersection between the cylinder and the deformable wall. The rim of the support advantageously rests on the shoulder 24 of the housing so as to position the support in the cavity. The rim 43 has a contact surface with the shoulder 24 of the housing.

[0048] According to a particular embodiment, illustrated for example by [Fig. 3], the contact surface between the rim 43 and the shoulder 24 of the housing can form a truncated conical surface, around the longitudinal axis X. Such a surface makes it easier to position and robust the device 1. Advantageously, the support can comprise hooks 45. The hooks are configured to retain the support 4 in the housing and prevent the support from coming out of the housing when it is subjected to extreme weather conditions.

[0049] The support thus defines in the cavity 23 of the housing an external cavity 231 forming a housing 231 for the push button 3, and an internal cavity 232. The housing 231 is defined in the part of the cavity located above the support and the internal cavity 232 is defined in the part of the cavity located below the support. In other words, the housing extends in the housing from the deformable wall to the upper edge of the housing and the internal cavity extends in the housing from the deformable wall to the lower edge of the housing. Thus it can be understood that the connection cavity 411 is part of the internal cavity 232.

[0050] According to one embodiment, the external face 421 of the deformable wall 22 comprises a pin 423 centered on the longitudinal axis X extending from the external face 221 advantageously into the housing 231. The pin may be of hollow cylindrical shape and is advantageously centered on the longitudinal axis X. The pin allows the push button 3 to be fixed to the support.

[0051] The support may advantageously be made of a thermoplastic material opaque, such as ABS, polyamide or polybutylene terephthalate (PBT).

[0052] Button

[0053] The push button 3 is housed in the cavity 23 of the housing 2. Preferably, the push button 3 is housed in the housing 231. The push button is preferably in the form of a rigid circular plate. The push button comprises an external face 30 and an internal face 31. The external face is configured to receive contact from a user's finger. The external face of the push button forms an interface for access to the device by a user and may be subject to regular degradation.

[0054] Advantageously, in a rest position of the push button, the external face extends in a plane tangent to the upper edge of the housing. The internal face 31 of the push button is arranged facing the external face 421 of the deformable wall.

[0055] The push button is movable by sliding in the housing along the longitudinal axis X. By pressure exerted by an operator on the external face 30, the push button can translate between the rest position, called the free position, in which the actuating device is inactive and a constrained position for actuating the device.

[0056] Advantageously, in a constrained position the push button comes to bear against the edge of the support and deforms the deformable wall towards the connection cavity 411. The longitudinal translation of the button is thus limited by the edge of the support.

[0057] According to one embodiment, the contact face 31 of the push button 3 comprises a pin 33 centered on the longitudinal axis X and extending from the contact face 31 into the housing 231.

[0058] According to another embodiment, the external face 421 of the deformable wall 42 comprises a pin 423 centered on the longitudinal axis X extending from the external face 421, in the housing 231.

[0059] According to another embodiment, the contact face 31 of the push button 3 comprises a pin 33 centered on the longitudinal axis X and extending from the contact face 31 into the housing 231 and the external face 421 of the deformable wall 42 comprises a groove complementary to the pin 31.

[0060] According to another embodiment, the external face 421 of the deformable wall 42 comprises a pin 423 centered on the longitudinal axis X and extending from the external face 221 into the housing 231 and the contact face 31 of the push button 3 comprises a groove 32 complementary to the pin 423.

[0061] According to a preferred embodiment, illustrated by [Fig. 2], the contact face 31 of the button comprises a groove 32 centered on the longitudinal axis X and the external face 421 of the deformable wall 42 comprises a pin 423 extending in the housing 231 towards the contact face 31. Preferably, the contact face of the push button 3 comprises, in addition to the groove 32 centered on the longitudinal axis X, a central pin 33 surrounded by the groove 32. The pin 423 of the deformable wall 42 is advantageously a hollow cylinder configured to engage in the groove 32 and to receive the pin 33 of the contact face. Advantageously, the distance between the bottom of the groove 32 and the end of the pin 33 of the contact face is smaller than the height of the pin 423 of the deformable wall 42. Thus, in the free position, a space is provided between the contact face and the external face 421 of the deformable wall 42 and, in the constrained position, the contact face can come to bear against the rim 43 and the pin 423 of the deformable wall 42 can bear against the contact face 31 and thereby cause the deformable wall 42 of the housing to bend.According to a possible embodiment, the distance between the bottom of the groove 32 and the end of the pin 33 of the contact face is greater than the height of the pin 423 of the deformable wall and it is the pin 33 of the contact face which causes the deformation of the deformable wall, in the constrained position.

[0062] Preferably, the pin 423 is a hollow cylindrical pin extending along the longitudinal axis X and the groove 32 is complementary to the pin 423, so that the pin fits into the groove. The pin and the groove, and possibly the pin 33 of the button, make it possible to connect the push button 3 to the deformable wall 42 of the housing 2.

[0063] Advantageously, the pin 423 and the groove 32 respectively comprise complementary irremovable fixing means such as lugs or a non-return clip. Thus, the push button 3 is integral with the housing 2 once mounted thereon. The push button 3 cannot be detached from the housing without damaging the push button and / or the housing.

[0064] Advantageously, the housing 2 further comprises a seal 7. The seal is positioned in the housing 231, advantageously against the internal surface 211 of the side wall 21 and between the push button and the deformable wall 42. The seal 7 is configured to protect the space between the contact face 31 of the push button 3 and the external face 421 of the deformable wall 42 from the intrusion of a foreign body such as water or dust. In addition, the seal makes it possible to avoid blocking the movement of the push button from the free position to the constrained position which would be due to the presence of a blocking element or in the event of frost which would transform infiltrated water into ice.

[0065] Piezoelectric element

[0066] As visible in [Fig.2], the piezoelectric element 4 is positioned on the internal face of the deformable wall 42 of the support. Thus the piezoelectric element is fixed to the deformable wall of the support so as to take its shape and undergo the deformations. Thus, the deformation of the deformable wall of the support generated by the pressure of the push button in the constrained position, generates a deformation of the piezoelectric element.

[0067] The piezoelectric element 4 is therefore fixed to the support. The piezoelectric element is housed in the connection cavity. Preferably, the piezoelectric element has the shape of a disc centered on the longitudinal axis X but it could have any other shape without departing from the scope of the invention.

[0068] Preferably, the piezoelectric element 5 is fixed to the internal face 422 of the deformable wall 42 of the support 4 by means of a double-sided adhesive pad 51.

[0069] The piezoelectric element 5 is adapted to generate an electrical voltage under the effect of a dynamic pressure exerted via the upper wall of the housing.

[0070] The piezoelectric element 5 may thus comprise electrodes made of brass, silver and / or another electrically conductive material, covered with a layer of piezoelectric ceramic. For purely indicative purposes, a piezoelectric element marketed by the company Murata under the reference 7BB-12-9 may be used. Such a piezoelectric element may comprise a brass plate with an external diameter of 12 mm and a thickness of 0.1 mm, forming the first electrode, covered with a layer of piezoelectric ceramic 9 mm in diameter. A second silver electrode 8 mm in diameter is arranged on the surface of the ceramic layer. The total thickness of this element is 0.22 mm.

[0071] The piezoelectric element 5 is configured to operate for a lifetime greater than about fifty million cycles, a cycle comprising the passage of the push button 3 from a free position to a constrained position and its return to the free position.

[0072] Thus, the device 1 makes it possible to convert mechanical energy given by a user who presses the push button 3 into electrical energy.

[0073] Printed circuit board

[0074] The printed circuit 6 is preferably positioned in the cavity 23 of the housing 2. Preferably, the printed circuit is housed in the connection cavity 23 of the support and is electrically connected to the piezoelectric element 5, as visible in [Fig.2]. The printed circuit positioned in the support thus defines with the deformable wall and the cylinder of the support the connection cavity.

[0075] The printed circuit is equipped with components adapted to convert the voltage generated by the piezoelectric element and consequently establish a closed contact between two connection elements 61 (for example two electric wires) between the piezoelectric element and the system to be controlled. The switching time depends on the force and speed of pressing the push button 3.

[0076] The electrical connection between the piezoelectric element 5 and the printed circuit 6 is provided by two compression springs 9a, 9b which are made of electrically conductive material. The springs are in contact, on the one hand, with respectively a first and a second electrode (not shown) present on the face of the piezoelectric element opposite the deformable wall 42 of the housing and, on the other hand, with tracks of the printed circuit connecting the two connection elements 61.

[0077] According to a preferred embodiment, the springs 9a, 9b are coaxial. The first spring 9a, called the external spring, has a diameter greater than that of the second spring 9b, called the internal spring. Particularly advantageously, the external spring 9a has a diameter slightly smaller than that of the cylinder of the support, so that the cylinder also guides the external spring 9a.

[0078] Furthermore, the device 1 preferably comprises a retaining element 10 for the internal spring and a guiding element 11 for the external spring. For example, the retaining element may consist of an axial pin with a diameter slightly smaller than that of the internal spring, around which the internal spring is arranged. The guiding element for the external spring may comprise a hollow cylinder in which the external spring can slide. The guiding element and the retaining element ensure that the springs are well positioned in contact with the electrodes of the piezoelectric element 5 during assembly of the device and that they remain so when the push button 3 is actuated. The assembly is particularly simple since it does not require any welding and can be automated.

[0079] Advantageously, the guide element 11 of the external spring can allow the printed circuit to be fixed in the connection cavity.

[0080] Preferably, the printed circuit 6 is electrically connected to a system in which the housing 2 is housed, for example in the system to be controlled. The printed circuit can be connected there by two conductors 61 sized according to the electrical requirements of the device 1.

[0081] Advantageously, the printed circuit 6 is configured to filter the voltage generated by the piezoelectric element so as not to generate a control signal by mistake, for example when the voltage generated is the result of an untimely shock on the system to be controlled on which the device is implemented.

[0082] Backlighting

[0083] Advantageously, the device 1 may comprise a backlighting system, as seen in [Fig.4]. The backlighting system comprises a light source 8.

[0084] The light source may comprise one or more light-emitting diodes (LEDs), for example LEDs of different colors.

[0085] The light source 8 is arranged in the cavity 23 of the housing 2, as visible in [Fig. 5]. More precisely, the light source 8 is housed in the internal cavity 232 of the housing.

[0086] The light source 8 comprises conductive wires 81 sized according to the electrical requirements of device 1 and suitable for connecting the device to the system to be controlled.

[0087] According to a preferred embodiment, the support 4 is translucent so as to be able to allow light to pass through it. In this case, the support 4 therefore also fulfills a light guide function from the light source to the upper face of the push button.

[0088] Preferably, the support 4 comprises an extension 44 in the housing 231 from the rim 43. The extension 44 forms a cylinder extending longitudinally from a plane tangent to the deformable wall 42 and to a plane tangent to the upper edge 214 of the housing. Advantageously, the extension 44 of the support in the housing forms an internal wall of the housing 231.

[0089] Thus, the support extends longitudinally from the internal cavity in which the light source 8 is housed and to the outside of the housing, i.e. to the upper edge 214 of the side wall 21 of the housing. In other words, the support forms an internal portion of the side wall of the housing from the internal cavity to the upper edge 214. The support is thus capable of allowing the light emitted by the light source in the cavity 23 to be visible from the outside at the push button 3, and more precisely, all around the push button, between the upper edge 214 of the side wall 21 of the housing 2 and the push button 3. A user can thus see the light emitted by the controlled light source turn on according to certain conditions.

[0090] In this embodiment, the support is advantageously molded from a translucent thermoplastic material, such as polycarbonate.

[0091] The device 1 is suitable for operating in an environment subject to temperatures ranging from -40°C to +75°C and for resisting intentional impacts. The device 1 has a robustness greater than IK06 according to the impact protection index (IK) according to standard EN 62-262.

[0092] The device 1 advantageously comprises a degree of sealing greater than IP69K according to the sealing protection index (IP).

[0093] The force required to move the push button 3 into the constrained position is between 1 and 10 N and preferably between 2 and 8 N. The movement of the push button 3 from the free position to the constrained position is between 0.10 mm and 0.50 mm and preferably 0.15 mm.

[0094] Assembly method

[0095] The assembly method comprises, for example, the successive placement in the cavity 23 of the housing 2 of the support in which the piezoelectric element 5, of the printed circuit 6 equipped with the connection elements have been positioned. Then, in the embodiment according to which the device comprises a backlighting system, the light source 8 is installed in the internal cavity. Advantageously, resin 12, for example epoxy resin, can be injected into the internal cavity 232 in order to seal the device 1, except in the connection cavity which remains free of it. In the case of a device 1 with a backlighting function, transparent resin 12, for example transparent silicone resin, can be injected into the internal cavity 232 between the support and the light source 8, in order to seal the device 1 while allowing the passage of light. Resin 12, for example epoxy resin, can be injected into the other part of the internal cavity 232.

[0096] Furthermore, the seal 7 and the push button 3 are placed in the housing 231 of the casing, by clipping onto the deformable wall 42 of the support. When the device is assembled, the springs 9a, 9b are in the free or slightly stressed state.

[0097] Thus, when the push button 3 is at rest, the springs do not apply significant stress but are only stressed so as to guarantee contact with the piezoelectric element 5, which prevents it from being damaged.

[0098] When dynamic pressure is exerted on the push button 3, the latter presses on the deformable wall, the springs can compress while ensuring the electrical connection between the electrodes of the piezoelectric element 5 and the printed circuit 6, and this without degradation of the piezoelectric element. The presence of the shoulder 43 makes it possible, among other things, in the case where abnormally high dynamic pressure is exerted on the push button 3 (for example in the event of an act of vandalism), to avoid damage to the piezoelectric element, by blocking the deformation of the deformable wall 42 by the push button pressing on the shoulder 43.

[0099] Thus, the device according to the invention is particularly suitable for use in environments which require increased protection against intentional damage.

Claims

Claims

1. Piezoelectric actuation device (1) comprising: - a housing (2) defining a cavity (23), - a support (4) separating the cavity (23) into an upper housing (231) and a lower cavity (232), the support (4) comprising a deformable wall (42) in flexion and a rigid rim (43) surrounding the deformable wall (42), the housing (231) being delimited by said rim (23) and the deformable wall (42); - a rigid push button (3) positioned in the upper housing (231), and configured to move between a free position and a constrained position in which the deformable wall (42) is deformed towards the lower cavity (232); - a piezoelectric element (5) secured to the housing (2), inside the internal cavity (232); and - a printed circuit (6) housed in the lower cavity (232) and electrically connected to the piezoelectric element (5).

2. Device (1) according to claim 1, wherein the button (3) is irremovably connected to the deformable wall (42) of the support (4).

3. Device (1) according to any one of claims 1 to 2, in which the deformable wall (42) comprises an upper face (421) and the button (3) comprises a contact face (31) opposite the upper face (421), the upper face (421) and the contact face (31) being spaced from each other, when the button (3) is in the free position, by at least one first pin (423, 33) extending from the upper face (421) or from the contact face (31).

4. Device (1) according to claim 3, in which the upper face (421) of the deformable wall (42) comprises a tubular pin (423) and the button (3) comprises a groove (32) complementary to the pin (423), such that the groove (32) of the button (3) engages in the pin (423) of the deformable wall (42).

5. Device (1) according to any one of claims 1 to 4, comprising a light source (8) arranged in the lower cavity (232).

6. Device (1) according to claim 5, wherein the support (4) is translucent and comprises an extension extending longitudinally in the housing (231) from the rim (43) to an upper edge (214) of the housing (2), the extension (44) surrounding the button (3), so that the support (4) guides the light emitted by the light source (8) towards the upper edge (214) of the housing (2).

7. Device (1) according to any one of claims 1 to 6, comprising a seal (7) positioned between the button (3) and the deformable wall (42).

8. Device (1) according to any one of claims 1 to 7, in which the piezoelectric element (5) is fixed against the deformable wall (42) by a double-sided adhesive pad (51).

9. Device (1) according to any one of claims 1 to 8, in which the electrical connection between the printed circuit (6) and the piezoelectric element (5) is ensured respectively by a first and a second compression spring (9a, 9b), cylindrical in revolution and arranged in the internal cavity (232) between the printed circuit (6) and the piezoelectric element (5); the first and the second spring (9a, 9b) having coincident axes of symmetry (XX) and the second spring (9b) being arranged inside the first spring (9a).

10. Device (1) according to any one of claims 1 to 9, wherein a portion of the internal cavity (232) is sealed by a resin layer (12).

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