ELECTROACOUSTIC CONVERTER

Description

[0001] The invention relates to an electroacoustic transducer for generating shock waves for the treatment of the human or animal body.

[0002] Electroacoustic transducers can operate according to various physical principles. The present invention relates to such electroacoustic transducers for generating shock waves for treating the human and animal body, which are constructed at least using piezoelectric elements. Such transducers, in various designs, are part of the prior art. There are focused, line-focused, planar transducers, and hybrid designs, all of which are part of the prior art.

[0003] From DE 33 198 71 A1, a piezoelectric transducer for the destruction of calculi inside the body is known, in which the piezoelectric elements are arranged on a substrate in the form of a hemispherical shell, electrically connected, and filled with casting resin as a potting compound. Due to the arrangement of the elements on a spherical shell, the transducer is self-focusing. The inside of the transducer is filled with liquid and can be coupled to the body to be treated via a membrane. The casting resin must protect the piezoelectric elements from the liquid, which presents a challenge.

[0004] A similarly constructed electroacoustic transducer is known from DE 195 43 741 C1, in which the plastic potting compound is protected by a metal foil as a moisture barrier. Both designs have in common that the piezoelectric elements generally have to be painstakingly attached to the carrier dome and electrically connected to each other by hand, after which the casting resin is poured in. This requires a special tool that forms the part of the mold facing the coupling side. A separate tool is required for each transducer shape and size, which is complex and expensive.

[0005] German patent DE 10 2010 055 836 B4 discloses a multi-layered, self-focusing electroacoustic transducer constructed with piezoelectric elements as prior art. In this design, the piezoelectric elements are arranged in carriers that have a multitude of through-holes, each holding and retaining a piezoelectric element. While this design can also incorporate a backing or support body to ensure the mechanical stability of the transducer, the bond is created using a potting compound, which is applied using a special tool positioned at the coupling side. The tool must remain in place until the potting compound has sufficiently cured. German patent DE 197 33 233 C1 discloses an electroacoustic transducer with a dome-shaped carrier. Piezoelectric elements are arranged on both the inner and outer surfaces of the carrier.The spaces between the piezoelectric elements are filled with a potting compound. DE 39 32 959 C1 discloses a piezoelectric transducer for generating focused ultrasonic shock waves. A plurality of piezoelectric transducer elements are arranged on a carrier of the transducer. A space formed between the carrier and a housing of the transducer, in which the piezoelectric elements are arranged, is filled with a highly insulating medium. CN 109 365 253 A1 discloses a piezoelectric transducer for de-icing. The transducer comprises a back wall and a seal, between which two piezoelectric elements are arranged. An electrode is arranged between the back wall and the adjacent piezoelectric element, between the two piezoelectric elements, and between the seal and the adjacent piezoelectric element. US 2007 / 007118 A1 discloses an ultrasonic transducer with a piezoelectric receiving resonator and a transmitting resonator.The two resonators are arranged in a common housing. A damping layer is positioned behind the resonators in the direction of sound transmission. An acoustic matching layer is located between the two resonators.

[0006] Against this background, the invention according to the application is based on the objective of designing an electroacoustic transducer for generating shock waves for treating the human or animal body of the aforementioned type, i.e., one constructed using piezoelectric elements, in such a way as to simplify its manufacture. Furthermore, a method for manufacturing such an electroacoustic transducer is to be provided.

[0007] The apparatus-related part of this problem is solved by an electroacoustic transducer with the features specified in claim 1. A method for manufacturing such a transducer is characterized by the features specified in claim 13. Advantageous embodiments are described in the dependent claims, the following description, and the drawings.

[0008] The electroacoustic transducer according to the invention for generating shock waves for treating the human or animal body is equipped with piezoelectric elements arranged in at least one carrier within a housing. The space formed between the piezoelectric elements and the housing is filled with a potting compound.

[0009] The basic idea of ​​the present invention is to replace the otherwise complex casting tool by using a housing that forms part of the subsequent electroacoustic transducer. The solution according to the invention thus makes it possible to produce electroacoustic transducers of the type mentioned above cost-effectively, both in small series and individually. These transducers can be manufactured practically without tooling, but the piezoelectric elements are tightly and firmly fixed and held by a hardening potting compound. The potting compound can also consist of a gel, a high-voltage oil, or a sand-like powder suspended in a liquid. This results in a bond between the piezoelectric elements, the support(s), and the housing, forming a stable whole.Such a housing, which can be manufactured using 3D printing, for example, allows the converter to be varied almost arbitrarily in its external shape and internal structure without requiring complex tool modifications. According to the invention, the housing thus replaces the casting mold and has the added advantage that it does not even need to be removed after the potting compound has hardened. It also offers the advantage that potting compounds that do not harden, such as liquids or pastes, can be used. If the housing, as in many designs, does not have a load-bearing function, it can be manufactured cost-effectively and, if necessary, even in single-unit production.

[0010] Preferably, according to a further development of the invention, the cavity is filled with a hardening plastic. Such a hardening plastic can, for example, be a thermoplastic that hardens within the housing after cooling, or a thermoset that hardens chemically, similar to the potting compounds known from the prior art. Such a plastic can advantageously be cross-linked with strength-enhancing fibers, e.g., glass fibers, carbon fibers, particles, or other macroscopic materials.

[0011] Advantageously, according to a further development of the invention, the housing is designed such that it has at least one opening for filling with the potting compound and at least one further opening for gas escape during filling. It is understood that, depending on the design, several filling and / or degassing openings may also be provided in the housing. The gas escape opening can assist the filling process by allowing evacuation in this area.In the case of a hardening plastic, these openings can remain open after the cavity has been filled with the potting compound and the material has hardened. However, if the potting compounds remain in a liquid, pasty, or mixed form, these openings can be designed to be closed, either by providing a suitable filling valve in the filling opening and a plug for the outlet opening, or by deliberately closing these openings at the end of production, be it by welding, gluing, or the like.

[0012] Advantageously, the housing is constructed in multiple parts and consists of at least two housing parts which, after being integrated into the support or supports containing the piezoelectric elements, are firmly connected to one another. This is preferably done by a material bond, be it by gluing, welding or the like.

[0013] According to the invention, the housing is designed as a closed housing and completely replaces the casting mold. The potting compound is reliably contained by the housing. According to an alternative embodiment, which is not part of the claimed invention, the housing can be designed to be partially open, i.e., not completely closed. In this case, the open side is located on the side opposite the coupling side, i.e., on the rear of the housing. Depending on the design of the transducer, a housing wall can be omitted here, for example, if a planar transducer is to be potted with a hardening plastic, since no casting mold is then required in this area.A partially open housing within the meaning of the present invention is therefore only to be understood as a housing which is open on one side where no tool is required when filling the free space with the potting compound, as may typically be the case on the back side in special designs.

[0014] It can be advantageous to manufacture both the housing and the support(s) from plastic. These can be produced using 3D printing or injection molding, especially for larger production runs. Parts of the housing, and also the support(s), can also be advantageously made of metal, although in this case, special precautions regarding electrical insulation are generally necessary. The coupling end is advantageously made of metal, particularly if a liquid-filled pre-line section connects there, to prevent moisture from diffusing through the housing into the potting compound. To increase the strength of the components, it can be beneficial to use composite materials, especially in the area of ​​the support(s), which form essential parts of the final assembly.Even in designs where the potting compound is non-hardening, the support forms the essential mechanical connection between the piezoelectric elements. The support(s) are then expediently fixed to the housing by means of a form-fit, force-fit, and / or material-fit connection.

[0015] Particularly when using plastics, housing components can be advantageously formed by deep drawing. This method is suitable for small and medium-sized production runs. To ensure that no liquid diffuses from the coupling section into the transducer when using a plastic housing, an advantageous embodiment of the invention allows the housing to be provided with a liquid-tight metal layer, at least on the coupling side. Such a metal layer can be provided in the form of a film or vapor-deposited and is preferably located on the inside of the housing, as no special precautions for protecting the metal layer are then necessary. Alternatively, the metal layer can also be provided on the coupling side; however, in this case, at least a protective coating or an additional protective layer will generally be required.

[0016] Especially with smaller transducers, it is advantageous to equip the housing with a gel pad as a coupling element on the coupling side. It is advantageous if such a gel pad is replaceable to allow for different penetration depths, particularly with self-focusing transducers.

[0017] According to a further development of the invention, the housing can be designed such that an opening, preferably extending through the front and back, is formed, which is provided for receiving a camera, an ultrasonic transducer, or a sensor. Depending on the requirements, one or more such openings can be provided. Advantageously, one opening is completely sealed by the housing, so that despite the opening, the interior of the housing remains protected by the housing wall.

[0018] The housing design according to the invention makes it possible to manufacture individually adapted housings cost-effectively, even in very small quantities. In this respect, the housing of the transducer according to the invention can advantageously be anatomically adapted to the specific application, at least on the coupling side, but not necessarily only on this side. If both the housing and the carrier are manufactured using 3D printing, then the housing shape and the arrangement of the piezoelectric elements within it can be configured virtually arbitrarily. For example, for the treatment of extremities, it is conceivable to design the housing in a tub-like shape and to form the coupling side through the bottom of the tub. The piezoelectric elements can also be arranged within the housing in such a way that a partially focused wavefront is created, as is advantageous, for example, for soft tissue treatment.

[0019] For arranging the piezoelectric elements within the substrate, it is advantageous if the substrate at least partially encloses the piezoelectric elements completely, so that the piezoelectric elements are free on their front and back sides and thus accessible for electrical wiring. Typically, piezoelectric elements of the same substrate layer are connected in parallel, with the connections of successive substrate layers being brought out separately in order to control the timing of the voltage application and thus the propagation of the wavefronts.

[0020] Depending on the transducer design, the piezoelectric elements can be controlled individually, in groups, or together. The electrical wiring must be configured accordingly. A wide range of control options can be achieved through individual control, but this requires correspondingly complex wiring. With individual or group control, temporally variable control is possible, allowing for the generation of virtually any wavefront.

[0021] The electroacoustic transducer according to the invention is typically manufactured by first arranging the piezoelectric elements in one or more carriers. A carrier is a component that has a plurality of recesses in which a piezoelectric element can be clamped. The elements are then expediently wired electrically, after which the resulting assembly is integrated into the typically multi-part housing, which is then securely and tightly sealed by bonding or ultrasonic welding by joining the housing parts together. The potting compound is then poured in, which typically hardens after a predetermined time, at which point the electroacoustic transducer is complete.

[0022] It should be noted that, in addition to the aforementioned support with recesses, additional support elements may also be provided within the housing. The housing itself can also form such a support element; in this case, it is designed to be correspondingly robust.

[0023] The inventive design of the electroacoustic transducer allows for the production of virtually any shape and structure. This enables the cost-effective manufacture of multiply curved transducers, segmented line transducers, transducers with stepped housings, transducers with integrated individual domes, and other special designs, particularly when the substrates and housing are manufactured using 3D printing. Furthermore, the transducers as a whole can be equipped with acoustic lenses, preferably arranged outside the housing, or the piezoelectric elements can be provided with corresponding lenses, preferably inside the housing.

[0024] The invention is explained in more detail below with reference to exemplary embodiments shown in the figures. The figures show: Fig. 1 shows a highly simplified sectional view of a self-focusing transducer according to the invention, Fig. 2 shows a line-focusing transducer constructed from two carriers arranged one behind the other with piezoelectric elements, as depicted in the figure. Figure 1 and, Fig. 3 in a highly simplified sectional view an anatomically adapted converter for the foot and, Fig. 4a - 4 in a highly simplified schematic representation various converter shapes.

[0025] At the in Figure 1The electroacoustic transducer 1 shown is a self-focusing transducer comprising a two-part plastic housing 2, 3. The housing consists of a first housing part 2, which forms the coupling side of the transducer 1. This first housing part 2 is cup-shaped, has a concave shape facing the coupling side, and is otherwise cylindrical. The cylindrical part of the housing is closed off by a rear housing part 3, also made of plastic, which is firmly and tightly connected to the housing part 2 by ultrasonic welding. A carrier 4 is arranged within the housing 2, 3, in which a plurality of piezoelectric elements 5 are arranged. The piezoelectric elements 5 are essentially cylindrical in shape. They are positively and force-fitted around their circumference in recesses of the carrier 4 and are electrically wired at their end faces.They are arranged within the dome-shaped support 4 in such a way that, when the elements 5 are simultaneously electrically actuated, an acoustic pressure wave is generated, the focus 6 of which lies at a distance from the coupling side opposite the concave housing part 2.

[0026] The carrier 4, with the piezoelectric elements 5 arranged therein, is positively secured within the housing 2, 3 by two cylindrical rings 7. The outer surfaces of these rings abut the inner surfaces of the housing 2, 3, and one end face abuts the front inner surface of the housing part 2 and the rear inner surface of the housing part 3, respectively. The carrier 4 is positively integrated between the other end faces of the rings 7. Connections 8 and 9 are provided circumferentially in the cylindrical area of ​​the front housing part 2. Connection 8 is an opening for filling the housing 2, 3 with a potting compound, and connection 9 is for connecting a vacuum line or as an outlet for air escaping during the filling of the potting compound into the housing 2, 3.The potting compound is therefore filled into the housing 2, 3 via connection 8; the filling process can be supported by connecting a vacuum pump to connection 9; at least degassing takes place via connection 9, meaning that the gas volume displaced by the filled potting compound 10 escapes through this connection 9.

[0027] The potting compound 10 is injected under pressure through the port 8 into the housing 2, 3 after the carrier 4 with the piezoelectric elements 5 arranged therein is fixed between the rings 7 inside the housing 2, 3 and the housing parts 2, 3 are firmly and tightly joined together by gluing or welding. The electrical connections of the piezoelectric elements 5 are already wired, and the corresponding connecting leads 15 are sealed and exit the housing 2, 3 from the rear. After the potting compound 10 has hardened, the ports 8, 9 are sealed by the hardened potting compound 10 inside. The potting compound forms a solid, continuous body that can now be installed in a suitable medical device, with the concave outer surface of the housing part 2 forming the coupling surface to which a correspondingly shaped gel body (not shown) is detachably attached.Alternatively, a liquid-filled coupling section with a membrane can be provided here; in this case, the housing part 2 is preferably provided on the inside with a diffusion-tight metal layer to prevent liquid from penetrating into the transducer 1.

[0028] In the one based on Figure 2 The electroacoustic transducer 1' shown also consists of two housing parts: a front housing part 2' facing the coupling side and a rear housing part 3'. The in Figure 2The housing 2' / 3' shown has the shape of a cylindrical ring section and is designed for a line-focusing transducer 1'. Two carriers 12 are arranged within the housing, each comprising a plurality of piezoelectric elements 5. These elements are wired in parallel on the carrier side but are routed separately to the rear via connecting leads (not shown). In this embodiment as well, the carriers 12 are positively locked within the housing 2', 3' by rings 7' that are essentially rectangular in plan view. The arrangement is such that the piezoelectric elements 5 focus the generated sound wave in a line; the focus area is in Figure 2 Marked with 11. Furthermore, the one based on Figure 2 The converter 1' shown is in the same way as the one shown according to Figure 1The two carriers 12, with integrated piezoelectric elements 5, are firmly connected to each other and to the surrounding housing 2', 3' by a potting compound 10. This housing 2', 3' thus replaces the casting mold during the casting process. The housing parts 2', 3' themselves, as well as the carriers, can be manufactured cost-effectively, e.g., using 3D printing, so that even individual housing shapes can be economically produced on a one-off basis.

[0029] Based on Figure 3The figure schematically illustrates how an anatomically adapted transducer 1" can be designed. The transducer 1" shown is adapted to the lower shape of a foot. In the peripheral areas, where the transducer 1" is curved to encompass the side of the foot, the piezoelectric elements 5 located therein are equipped with acoustic diverging lenses (not shown). This is intended to prevent unwanted focusing in this area. The opposite effect can be achieved analogously by arranging converging lenses. These acoustic lenses are advantageously provided on the housing side and can be located on the inside of the upper housing part 2", but also on the outside or on both sides. In this embodiment as well, the piezoelectric elements 5 are integrated into a carrier 4", which is positively locked within the housing formed by the housing parts 2" and 3".The free space between the piezoelectric elements 5 and the housing 2", 3" is completely filled with hardening plastic.

[0030] Based on the Figures 4a to 4d Other electroacoustic transducers are shown as examples to illustrate the variety of housing designs that can be achieved with this setup. Figure 4a A biaxially curved housing is shown, in which the piezoelectric elements, following the shape of the housing, create a focus which corresponds to a curved line.

[0031] In Figure 4b The transducer is arranged in a stepped fashion to achieve a spreading of the individual piezoelectric elements in depth and thus a defocusing.

[0032] Based on Figure 4c The arrangement shown consists of several linearly focusing transducers in a common housing.

[0033] The execution according to Figure 4dshows a converter with several adjacent point-focusing sections.

[0034] The electroacoustic transducers described above are designed exclusively for medical applications and serve to generate shock waves, as used in medicine for treating the human and animal body. For coupling the transducer to the body, a fluid- or gel-filled pre-conduction section, for example in the form of a gel cushion, is typically provided, as is state of the art. Reference symbol list

[0035] 1, 1', 1" - Electroacoustic transducer 2, 2' - Front housing part 3, 3' - Rear housing part 4, 4" - Carrier 5 - Piezoelectric elements 6 - Focus 7, 7' - Rings 8 - Input terminal 9 - Output terminal 10 - Potting compound 11 - Focus area 12 - Carrier in Fig. 2 15 -connection cable

Claims

1. An electroacoustic transducer (1, 1') for the generation of shock waves for the treatment of the human or animal body, the electroacoustic transducer comprising piezoelectric elements (5), which are arranged in at least one carrier (4, 12) within a housing (2, 3; 2', 3'), wherein a free space formed between the piezoelectric elements (5) and the housing (2, 3; 2', 3') is in-filled with a casting compound (10), characterised in that the housing (2, 3; 2', 3') is formed as a closed housing and replaces a casting tool for the casting compound.

2. The electroacoustic transducer according to claim 1, in which the free space is in-filled with hardening plastic (10).

3. The electroacoustic transducer according to claim 1 or 2, in which the housing (2, 3; 2', 3') has at least one opening (8) for the in-filling of the casting compound (10), and at least one further opening (9) for the escape of gas when in-filling the casting compound (10).

4. The electroacoustic transducer according to one of the preceding claims, in which the housing (2, 3; 2', 3') is formed from at least two housing parts (2, 3; 2', 3'), which are preferably connected to one another in an integrally bonded manner.

5. The electroacoustic transducer according to any one of the preceding claims, in which the housing (2, 3; 2', 3') and / or the carrier (4; 12) is formed from plastic, metal or a composite material.

6. The electroacoustic transducer according to any one of the preceding claims, in which at least one housing part (2, 3; 2', 3') is formed by deep drawing, injection moulding, or with the 3D printing method.

7. The electroacoustic transducer according to any one of the preceding claims, in which the housing (2, 3; 2', 3'), at least on the coupling side, is provided preferably on an inner side with a liquid-tight metal layer.

8. The electroacoustic transducer according to any one of the preceding claims, in which the housing (2, 3; 2', 3') is provided on the coupling side with a preferably exchangeable gel pad as a coupling section.

9. The electroacoustic transducer according to any one of the preceding claims, in which the housing (2, 3; 2', 3') has at least one aperture, preferably running through the front and rear side, for receiving a camera, an ultrasound transducer, or a sensor.

10. The electroacoustic transducer according to any one of the preceding claims, in which the housing (2, 3; 2', 3'), at least on the coupling side, is configured so as to be anatomically adapted to a specific application.

11. The electroacoustic transducer according to any one of the preceding claims, in which the carrier (4; 12) circumferentially surrounds the piezoelectric elements (5), at least in some sections, and the piezoelectric elements (5) are electrically connected on their front side and on their rear side.

12. The electroacoustic transducer according to any one of the preceding claims, in which the piezoelectric elements (5) arranged in the carrier (4, 12) are electrically actuatable individually, in groups, or all together.

13. A method for producing a transducer (1; 1') according to any one of the preceding claims, in which the piezoelectric elements (5) are arranged and electrically connected in at least one carrier (4; 12), in which the at least one carrier (4; 12), populated with piezoelectric elements (5), is arranged in a closed housing (2, 3; 2', 3'), and in which the free space formed between the piezoelectric elements (5), the carrier (4; 12) and the housing (2, 3; 2', 3') is in-filled with a preferably hardening casting compound (10), wherein the housing replaces a casting tool for the casting compound.