ULTRASONIC TRANSDUCER

Abstract

The application relates to an ultrasonic transducer comprising a carrier with conductor traces and a piezoelectric element with electrodes, wherein the piezoelectric element has a contact side which is fixed on the carrier, and wherein the conductor traces and the electrodes are electrically coupled via the contact side of the element.

Claims

1. An ultrasonic transducer comprising: a carrier with conductor traces; and a piezoelectric element with electrodes, wherein the piezoelectric element has a contact side which is fixed on the carrier, and wherein the conductor traces and the electrodes are electrically coupled via the contact side of the element.

2. An ultrasonic transducer comprising: a container with a bottom designed as a carrier, a wall and an installation opening that is closable with a lid; electronics integrated in the container and/or in the lid; a piezoelectric element having a contact side fixed on the carrier; and conductor traces electrically connecting electrodes of the piezoelectric element and connection points of the electronics.

3. The ultrasonic transducer according to claim 2, wherein the conductor traces and the electrodes are electrically coupled via the contact side of the piezoelectric element.

4. The ultrasonic transducer according to claim 2, wherein the ultrasonic transducer is configured such that the electrodes are differently polarized during operation.

5. The ultrasonic transducer according to claim 2, wherein the ultrasonic transducer is configured to apply a voltage between the electrodes during operation.

6. The ultrasonic transducer according to claim 2, wherein the lid can be fixed to the container by means of an electrically conductive lid adhesive and the electronics integrated in the lid can be electrically contacted with the conductor traces.

7. The ultrasonic transducer according to claim 6, wherein a damping element is arranged in a cavity in the container between the carrier with the piezoelectric element and the lid.

8. The ultrasonic transducer according to claim 2, wherein the electrodes on the piezoelectric element and the connection points of the electronics are electrically connected exclusively by the conductor traces.

9. The ultrasonic transducer according to claim 2, wherein the piezoelectric element is a piezoelectric disk.

10. The ultrasonic transducer according to claim 2, wherein the electrodes electrically contact the conductor traces of the carrier.

11. The ultrasonic transducer according to claim 2, wherein the electrodes comprise a first electrode and a second electrode, wherein the first electrode is arranged areally on the contact side of the piezoelectric element and wherein the second electrode is arranged substantially areally on a side of the piezoelectric element opposite to the contact side and furthermore, wherein parts of the second electrode are arranged on a side surface and on the contact side of the piezoelectric element.

12. The ultrasonic transducer according to claim 2, wherein the contact side of the piezoelectric element is fixed to the support by means of a support adhesive.

13. The ultrasonic transducer according to claim 12, wherein the carrier adhesive is electrically insulating.

14. The ultrasonic transducer according to claim 13, wherein the electrodes and the conductor traces have rough surfaces that are spaced such that the electrodes and the conductor traces are in direct contact.

15. The ultrasonic transducer according to claim 13, wherein portions of the electrodes and the conductor traces are exposed to their surroundings and are in direct contact with each other.

16. The ultrasonic transducer according to claim 13, wherein the electrodes and the conductor traces are capacitively coupled.

17. The ultrasonic transducer according to claim 12, wherein the carrier adhesive means is anisotropically electrically conductive, so that the carrier adhesive means is formed as an electrical contact between the electrodes and the conductor traces and at the same time different electrodes are insulated from each other.

18. The ultrasonic transducer according to claim 2, wherein the conductor traces are arranged on an inner surface of the container.

19. The ultrasonic transducer according to claim 2, wherein the conductor traces are integrated inside the container.

20. The ultrasonic transducer according to claim 2, wherein the container has rotational symmetry.

21. The ultrasonic transducer according to claim 20, wherein the container is cylindrical, conical or frustoconical.

22. The ultrasonic transducer according to claim 2, wherein the container comprises means interconnected with the electronics to provide shielding of radiated electromagnetic disturbances in the form of Faraday shielding.

23. The ultrasonic transducer according to claim 22, wherein a metallic coating is applied to an inner and/or outer side of the container as means for Faraday shielding.

24. The ultrasonic transducer according to claim 22, wherein internal electrode structures or metal meshes such as copper meshes are applied to an inner side of the container as means for Faraday shielding.

25. The ultrasonic transducer according to claim 2, wherein a protective mechanical coating is applied to the outside of the container.

26. An ultrasonic transducer comprising a container with an installation opening which can be closed by a lid that has integrated electronics, wherein the lid can be fixed to the container by means of an electrically conductive lid adhesive and the electronics can be electrically contacted with conductor traces of the container.

27. A method of manufacturing an ultrasonic transducer, comprising the steps: a) providing a container which can be closed by a lid that has integrated electronics and the container having an installation opening that comprises a bottom designed as a support and conductor paths; and b) fixing a piezoelectric element in the container on the support so that electrodes arranged on the piezoelectric element are electrically connected via the conductor traces to connection points of the electronics.

28. The method of manufacturing an ultrasonic transducer according to claim 27, wherein step b comprises: fixing the piezoelectric element so that the electrodes are electrically coupled to the conductor traces; and closing the installation opening with the lid, wherein connection points of the electronics are electrically coupled to the conductor traces so that the electronics are electrically connected to the electrodes in a wireless manner.

29. The method of manufacturing an ultrasonic transducer according to claim 27, further comprising: inserting a damping element that fills the container between the piezoelectric element and the lid.

Description

[0132] The figures show:

[0133] FIG. 1: Perspective sectional view of a container according to a first embodiment of the ultrasonic transducer.

[0134] FIG. 2: Perspective top view of a piezoelectric element according to the first embodiment of the ultrasonic transducer.

[0135] FIG. 3: Perspective sectional view of the container and the piezoelectric element of the first embodiment of the ultrasonic transducer.

[0136] FIG. 4: schematic sectional view of the first embodiment of the ultrasonic transducer in the assembled state.

[0137] FIG. 5: Detailed illustration of a contact area with groove-shaped cutouts and elevations.

[0138] FIG. 6: Sectional view of a piezoelectric element and a carrier of a second embodiment.

[0139] FIG. 7: schematic sectional view of the fourth embodiment of the ultrasonic transducer in the assembled state.

[0140] FIG. 8: schematic sectional view of the fifth embodiment of the ultrasonic transducer in the assembled state.

[0141] FIG. 9: detailed cross-sectional view of an assembled ultrasonic transducer.

[0142] FIG. 10: detailed exploded view of an assembled ultrasonic transducer.

[0143] FIG. 1 shows a section through a container 2 of a first embodiment of an ultrasonic transducer 1.

[0144] In the present case, the container 2 is made in one piece. The container 2 comprises a support 3 corresponding to a bottom 3 of the container 2, a wall 4 and an opening 5 on its upper side. The support 3 serves as a membrane of the ultrasonic transducer 1. The container 2 has a rotationally symmetrical shape corresponding substantially to a cylinder. The carrier 3 is circular in shape and forms the base of the cylinder. The wall 4 comprises several cylinder sections of different diameters, which are arranged one above the other in a step-like manner. The diameter of the cylinder section adjacent to the carrier 3 is the smallest. The diameter of the cylinder section adjacent to the opening 5 is the largest.

[0145] The number of cylinder sections can vary depending on the application and technical requirements. For example, the wall 4 can comprise exactly one cylinder section.

[0146] In further, not shown, embodiments, the container 2 may take any other shape. Examples of further shapes of the container 2 are a conical shape or a cubic shape.

[0147] The container 2 has a cavity 6 on the inside. The cavity 6 is bounded at the bottom by the support 3 and at the sides by the wall 4. The cavity 6 is open at the top because the container 2 has the opening 5 there.

[0148] The surfaces of the carrier 3 and the wall 4 that face toward the cavity 6 inside the container 2 are referred to as the inner surfaces. The carrier 3 has an inner side of the carrier 3A and the wall 4 has an inner side of the wall 4A.

[0149] Accordingly, the outwardly facing surfaces of the container 2 are referred to as the outer surfaces.

[0150] In the first embodiment, the container 2 comprises an electrically conductive material. The electrically conductive material is, for example, aluminum or an aluminum alloy. In further examples, the container 2 may comprise further electrically conductive or electrically non-conductive materials.

[0151] In the present embodiment, the container 2 is therefore electrically conductive. The surfaces of the electrically conductive container 2 are coated with an insulation layer 7. If the container is made of aluminum, for example, this can be oxidized so that an electrically insulating anodised layer is formed. The electrically insulating anodised layer preferably has a thickness of between 5 and 25 ?m.

[0152] The insulation layer 7 completely covers both the inner sides and the outer sides of the container 2.

[0153] Two separate, electrically conductive conductor traces 8A and 8B are applied to the inside of the container 2. The conductor traces extend from contact areas 9A and 9B on the inner side of the carrier 3A over the inner side of the wall 4A to the opening 5 of the container 2.

[0154] In another embodiment, not shown, the conductor traces 8A and 8B do not extend to the opening 5 of the container 2. In this case, the conductor traces 8A and 8B extend over only a portion of the inner side of the wall 4A in the direction of the opening 5 and terminate, for example, at any point on the inner side of the wall or at a step between the of cylinder sections.

[0155] The conductor traces 8A and 8B and the contact areas 9A and 9B comprise an electrically conductive material such as copper, silver, nickel or chromium. The conductor traces 8A and 8B or the contact areas 9A and 9B can be applied by sputtering or by printing, for example screen printing. Alternatively, the conductor traces 8A and 8B or the contact areas 9A and 9B can be formed by applying a conductive polymer. The contact areas 9A and 9B may additionally be reinforced with conductive material.

[0156] FIG. 2 shows a piezoelectric element 10 of the first embodiment of the ultrasonic transducer 1.

[0157] The piezoelectric element 10 is designed as a disk, or more precisely as a flat cylinder. The diameter of the cylinder is significantly larger than the height of the cylinder. The piezoelectric element 10 has a lower side 11, an upper side 12 and a side surface 13.

[0158] In further, not shown, embodiments, the piezoelectric element 10 may have any other shape, for example, another rotationally symmetric shape, an elliptical shape, an n-cornered shape, or a cubic shape.

[0159] The lower side 11 is the contact side of the piezoelectric element 10, which is applied to the inner side of the carrier 3A when installed, points upward in FIG. 2 for clarity.

[0160] The piezoelectric element includes a piezoelectric material.

[0161] A first electrode 14A is applied to the lower side 11. The first electrode 14A is applied exclusively to the lower side 11. In the first exemplary embodiment, the first electrode 14A covers a large part of the lower side 11.

[0162] A second electrode 14B is applied to the upper side 12 of the piezoelectric element in a planar manner. In the first embodiment, the second electrode 14B covers a large part of the upper side 12.

[0163] The second electrode 14B further extends over the side surface 13 and the lower side 11, with the electrode 14B being formed contiguously. The first electrode 14A and the second electrode 14B are formed spaced apart and are not in contact with each other. Rather, an insulation gap is formed on the lower side 11 between the two electrodes 14A and 14B.

[0164] The electrodes 14A and 14B comprise electrically conductive materials such as copper, silver, nickel or chromium. The electrodes 14A and 14B can be applied, for example, by sputtering or by printing, preferably by screen printing.

[0165] FIG. 3 shows how the piezoelectric element 10 is inserted into the container 2. The lower side 11 of the piezoelectric element 10 is applied to the inner side of the carrier 3A in such a way that the first electrode 14A is in direct contact with the first contact area 9A and thus with the first conductor track 8A and that the second electrode 14B is in direct contact with the second contact area 9B and thus with the second conductor track 8B. There is no contact between the first electrode 14A and the second contact area 9B or the second conductor track 8B, and there is no contact between the second electrode 14B and the first contact area 9A or the first conductor track 8A.

[0166] FIG. 4 shows the ultrasonic transducer 1 according to the first embodiment in the assembled state.

[0167] The piezoelectric element 10 is arranged in the container 2 as described above. In the assembled state, the piezoelectric element 10 is attached to the carrier 3 by means of an adhesive connection not explicitly shown in FIG. 4. The adhesive connection is applied between the lower side 11 of the piezoelectric element 10 and the opposite section of the inner side of the carrier 3A.

[0168] The adhesive connection is electrically non-conductive. In the first embodiment, the adhesive connection comprises a thermally curing epoxy adhesive that is electrically non-conductive. In further embodiments, the adhesive connection may comprise other adhesives that are electrically non-conductive, for example UV-curing adhesives.

[0169] The adhesive connection may have non-conductive particles or fillers. These particles or fillers have diameters of less than 0.3 ?m, for example 0.2 ?m. Preferably, the adhesive layer has even smaller particles. Particularly preferably, the adhesive layer is completely free of particles or fillers.

[0170] Electrical contact between the electrodes 14A and 14B and the contact areas 9A and 9B is created by their surface roughness. If the surface roughness is sufficiently high, individual direct contacts are formed between elevations on the surface of electrodes 14A and 14B and elevations on the surface of contact areas 9A and 9B, which ensure electrical contacting. There is no adhesive connection between the electrodes 14A and 14B and the contact areas 9A and 9B at the points of electrical contact.

[0171] Such sufficient surface roughness is achieved, for example, at an average roughness Ra of 0.53 ?m, and a roughness depth Rz of 3.4 ?m of said surfaces.

[0172] Since the adhesive is electrically non-conductive, the adhesive connection acts as an electrical insulator, in particular as an insulator between the first electrode 14A and the second electrode 14B or the first contact area 9A and the second contact area 9B.

[0173] Furthermore, the adhesive connection protects the electrodes and the contact areas from environmental influences, for example from oxidation, so that the service life of the ultrasonic transducer 1 is increased.

[0174] The opening 5 of the container 2 is closed with a lid 16. Electronics 17 are integrated in the lid 16 and are designed to control and read out the piezoelectric element 10.

[0175] In the present example, the lid 16 is mechanically attached to the wall 4 by an annular, elastic adhesive connection 18. The annular, elastic adhesive connection 18 is not electrically conductive. The annular, elastic adhesive connection 18 seals the container 2 between the wall 4 and the lid 5 so that the cavity 6 is completely enclosed.

[0176] The annular elastic adhesive connection 18 comprises, for example, a non-electrically conductive silicone adhesive.

[0177] In addition, two electrically conductive elastic adhesive connections 19 are applied between the electronics 17 and the wall 4 to electrically connect the connection points of the electronics 17A and 17B and the conductor traces 8A and 8B. A first electrically conductive elastic adhesive connection 19A electrically connects a first connection point 17A and the conductor track 8A. A second electrically conductive elastic adhesive connection 19B electrically connects a second connection point 17B and the conductor track 8B.

[0178] For example, the electrically conductive elastic adhesive connections 19A and 19B comprise a conductive silicone adhesive. The electrically conductive elastic adhesive connections 19A and 19B have, for example, a resistivity between 1?10.sup.?3 and 3?10.sup.?2 Ohm.Math.cm.

[0179] The use of an elastic adhesive for the adhesive connections 18 and 19, ensures that, on the one hand, with respect to the adhesive connections 19A and 19B, a reliable electrical connection is established and, on the other hand, that vibrations of the container 2 are not transmitted to the printed circuit board or are transmitted only at a weakened level, which otherwise could lead, for example, to unwanted sound radiation in the rearward direction.

[0180] In the present exemplary embodiment, the cavity 6 is hollow. Such an embodiment simplifies the construction of the ultrasonic transducer 1. In further exemplary embodiments, which are not shown here, the cavity 6 can be filled with an insulating material. Since the cavity 6 does not have any other interfering internals, such as wires, the insulating material can be preformed and precured. The preformed insulating material can then simply be inserted into the cavity.

[0181] In an alternative embodiment of the first embodiment, specific areas of the contact areas 9A/9B or the electrodes 14A/14B are roughened. The roughening can be performed by means of laser irradiation. Thus, contact areas in the form of elevations on the surface of the electrodes 14A and 14B and elevations on the surface of the contact areas 9A and 9B can be selectively formed. The contact areas may form a predetermined pattern. For example, as shown in FIG. 5, groove-shaped recesses 9C can be formed by laser irradiation, between which parallel, elongated elevations 9D are formed.

[0182] In the following, a second exemplary embodiment of the ultrasonic transducer 1 is described which is not explicitly shown in the drawings. The second embodiment of the ultrasonic transducer 1 is mainly identical to the first embodiment of the first embodiment of the ultrasonic transducer 1. Identical features of the two embodiments are not described again to avoid repetition. Differences between the two embodiments will be described below.

[0183] FIG. 6 shows a piezoelectric element 10 and a carrier 3 of the second embodiment. As in the first embodiment, a lower side 11 of the piezoelectric element 10 is bonded to the inner side of the carrier 3A by means of an adhesive connection 15.

[0184] In contrast to the first embodiment, the adhesive connection in the second embodiment is anisotropically electrically conductive. The adhesive connection 15 is electrically conductive only in a direction perpendicular to the lower side 11 and perpendicular to the inner side of the carrier 3A. In any direction parallel to the lower side 11 or parallel to the inner side of the carrier 3A, the adhesive connection 15 is electrically insulating.

[0185] Thus, the adhesive connection 15 has an electrically insulating effect between the first electrode 14A and the second electrode 14B. Furthermore, the adhesive connection 15 has an electrically insulating effect between the first contact area 9A and the second contact area 9B. In contrast, between the first electrode 14A and the first contact area 9A, the adhesive connection 15 has an electrically conductive effect. Likewise, the adhesive connection 15 has an electrically conductive effect between the second contact area 9B and the second electrode 14B.

[0186] For example, the adhesive connection 15 includes an anisotropic, electrically conductive adhesive based on a non-conductive epoxy or acrylate matrix that includes a small amount of at least partially conductive or conductively coated particles 20.

[0187] In the following, a third exemplary embodiment of the ultrasonic transducer 1 is described that is not explicitly shown in the drawings. The third exemplary embodiment of the ultrasonic transducer 1 is mainly identical to the first exemplary embodiment of the ultrasonic transducer 1. Identical features of the two exemplary embodiments are not described again to avoid repetition. Differences between the two embodiments will be described below.

[0188] In contrast to the first exemplary embodiment, in the third exemplary embodiment the electrodes 14A and 14B protrude noticeably from the lower side 11. Likewise, the contact area 9A and 9B protrude noticeably from the inner side of the carrier 3A.

[0189] To achieve this, the electrodes 14A and 14B and the contact areas 9A and 9B are reinforced during the manufacturing process. For example, the electrodes or the contact areas are reinforced by sputtering chromium, nickel, silver or copper. Alternatively, the electrodes and the contact areas can be reinforced by electroplating or electroplating, for example.

[0190] In the third embodiment, the adhesive connection 15 is exclusively formed around the non-protruding surfaces of the lower side 11 and the inner side of the carrier 3A. In contrast, no adhesive connection is formed between the protruding surfaces of the electrodes 14A, 14B and the contact areas 9A, 9B. This is because the adhesive is displaced when the piezoelectric element 10 and the carrier 3 are pressed together.

[0191] A fourth exemplary embodiment of the ultrasonic transducer 1 is described below. The fourth exemplary embodiment of the ultrasonic transducer 1 is substantially similar to the first exemplary embodiment of the ultrasonic transducer 1. Identical features of the two exemplary embodiments are not described again to avoid repetition. Differences between the two embodiments will be described below.

[0192] In the fourth embodiment, the first contact point 9A is electrically connected to the electronics 17 via the first conductor track 8A. Instead of the second conductor track, the container 2, which is made of electrically conductive aluminum, itself acts as an electrical conductor between the second contact point 9B and the electronics 17, as shown in FIG. 7. For this purpose, the electrically insulating anodised layer 2A, is interrupted at a first breakthrough point at the second contact point 9B and at a second breakthrough point in the wall 4, which is opposite the second connection point 17B of the lid 16. The electrically conductive container 2 can therefore be electrically contacted at these points. In this embodiment, the carrier 3 and the wall 4 form a coherent and electrically conductive container 2.

[0193] At the first breakthrough point, the second contact point 9B is formed, for example, by means of an electrically conductive metal layer made of chromium, copper, silver or nickel. The metal layer can be applied, for example, by sputtering, electroplating, inkjet printing or screen printing. The second contact point 9B electrically connects the electrically conductive container 2 and the second electrode 14B.

[0194] A further electrically conductive layer, for example a metal layer or a conductive adhesive layer, is applied to the second breakthrough point in the wall 4, which electrically connects the electrically conductive container 2 and the second connection point 17B of the electronics 17.

[0195] In alternative embodiments, the second breakthrough point is formed at any location in the wall 4. A second conductor track 8B is then applied to the inner side of the wall 4A from the second breakthrough point to the second connection point 17B.

[0196] A fifth embodiment is mainly identical to the fourth embodiment and has the following differences.

[0197] The electrically conductive container 2, which acts as the second conductor track, is not in contact with the second electrode 14B. The anodised layer 2A on the inner side of the carrier 3A is not interrupted at the point where the second contact area 9B is applied.

[0198] In the fifth embodiment, the container 2 and the second contact area 9B form an electrical capacitor 21. Via the capacitor 21, the applied AC circuit can be closed capacitively (AC capacitor), as shown in FIG. 8.

[0199] Thus, a separate AC capacitor in the electronics 17 can be dispensed with and the apparatus design of the ultrasonic transducer 1 is simplified. Furthermore, this embodiment enables electrical contacting of the container 2 with ground.

[0200] In a further embodiment, the second contact point 9B may be dispensed with entirely. The capacitor is then formed between the container 2 and the second electrode 14B.

[0201] In the following, a sixth exemplary embodiment of the ultrasonic transducer 1 is described that is not explicitly shown in the drawings. The sixth exemplary embodiment of the ultrasonic transducer 1 is substantially similar to the first exemplary embodiment of the ultrasonic transducer 1. Identical features of the two exemplary embodiments are not described again to avoid repetition. Differences between the two embodiments will be described below.

[0202] In contrast to the first embodiment, the sixth embodiment has a container 2 made of non-conductive material. The non-conductive material is, for example, a liquid crystal polymer (LCP). Alternatively, the non-conductive material may comprise another suitable material or a mixture of different materials. Examples include, in particular, polymers or composite materials that are also commonly used for printed circuit boards, for example FR-4 composite material.

[0203] The container 2 can have means connected to the electronics 17 which ensures sufficient shielding from radiated electromagnetic interference (Faraday shielding) despite the non-conductive container material. For example, the container may contain internal electrode structures or metal meshes (copper network) which are suitably connected to ground with the electronics 17.

[0204] In a seventh embodiment not explicitly shown in the drawings, the electronics 17 may be wholly or partially arranged within the container 2 or form the container 2. For example, conductor traces, passive electrical components, active electrical components, or electrical circuits may be arranged in the container material.

[0205] An eighth exemplary embodiment, which is not explicitly shown in the drawings, is substantially similar to the sixth exemplary embodiment. In contrast to the sixth exemplary embodiment, at least one conductor trace is structured inside the container 2.

[0206] The container 2 consists here, for example, of LCP doped with 4% electrically conductive metal particles. The electrically conductive metal particles can be structured inside the container 2 so that they form a conductor trace 8B between the contact point 9B and the associated connection point 17B of the electronics 17, which is not exposed at the surface. At the contact point or at the connection point, the conductor trace 8A is structured as far as the inner side of the carrier 3A or as far as the inner side of the wall 4A and is thus exposed there. One possible method for forming the conductor trace 8B is to fuse the conductive metal particles using a laser-based process.

[0207] Conductive material can then be applied to the inside of the carrier 3A at the point where the conductor trace 8B is exposed, by chemical processes such as electroplating or galvanization, to form the electrical contact area 9B. The patterned, electrically conductive surface of the conductor trace 8B can serve as a seed layer for this purpose. Similarly, an electrical contact area can be formed at the location of the inner side of the wall 4A where the conductor trace 8B is exposed.

[0208] The electrically non-conductive layer of the container 2 over the structured conductor trace 8B is removed, for example, and the metal particles are exposed and fused together. Further electrically conductive material can be applied.

[0209] In all other respects, the ultrasonic transducer 1 of the eighth embodiment may be formed analogously to the fourth embodiment.

[0210] Furthermore, the formation of AC capacitors as in the fifth embodiment is also possible if the conductor trace 8B, inside the container 2, is not patterned up to the inner side of the carrier 3A, so that a non-conductive layer of the container 2 remains between the conductor trace 8B and the inner side of the carrier 3A.

[0211] In the eighth embodiment, in contrast to the fifth embodiment, two separate conductor traces 8A and 8B can be structured in the container 2, since the container 2 itself is not conductive. In this case, no further conductor traces applied to the inner side of the carrier 3A or the inner side of the wall 4A are necessary.

[0212] Furthermore, in the present embodiment, two AC capacitors may be formed, one each between first electrode 14A and first conductor track 8A and one between second electrode 14B and second conductor track 8B.

[0213] A ninth exemplary embodiment of the ultrasonic transducer 1, which is not explicitly shown in the drawings, is described below. The ninth exemplary embodiment of the ultrasonic transducer 1 is mainly identical to the first exemplary embodiment of the ultrasonic transducer 1. Identical features of the two exemplary embodiments are not described again to avoid repetition. Differences between the two embodiments will be described below.

[0214] In contrast to the first embodiment, the ninth embodiment does not feature an adhesive connection 15 between the piezoelectric element 10 and the carrier 3. Rather, the electrodes 14A and 14B are directly bonded to the corresponding contact areas 9A and 9B, respectively.

[0215] This is achieved, for example, by first forming the electrode 14A, electrode 14B, the contact area 9A, and the contact area 9B by sputtering. In a second step, the piezoelectric element 10 and the inner side of the carrier 3A are then pressed together so that the first electrode 14A rests on the first contact area 9A and the second electrode 14B rests on the second contact area 9B. The entire assembly described is then heated so that an electrical and mechanical material connection is formed between the contact areas and the electrodes. In this way, a particularly good coupling can be achieved between the piezoelectric element 10 and the carrier 3. The piezoelectric element 10 is thus also attached to the carrier 3.

[0216] The ultrasonic transducer 1 according to any of the embodiments may include additional components and elements beyond those previously shown. An exemplary detailed structure of such an ultrasonic transducer 1 is shown in FIGS. 9 and 10.

[0217] The double-cylinder-shaped container 2 has a cylindrical lower part with a smaller diameter and a cylindrical upper part with a larger diameter. The lower part is adjacent to the support 3, and the upper part is adjacent to the lid 16. The lower and upper parts are connected to each other by a connecting surface oriented parallel to the support 3 and the lid 16.

[0218] The wall 4 of the lower part of the container 2 is externally covered with a vibration damping component 22. The connecting surface between the lower and the upper part of the container 2 is provided with adhesive material 23 from the outside. The piezoelectric element 10 is fixed on the support 3 inside the container 2. Above this, the damping element 24, which fills most or all of the cavity 6 of the container 2, is arranged. The damping element 24 can already be manufactured and hardened before the ultrasonic transducer is assembled.

[0219] Depending on the embodiment, electrical contact areas 9A/9B and an adhesive 15 may be arranged between the carrier 3 and the piezoelectric element 10. The contact areas 9A/B can be part of the conductor traces 8A/8B (see FIG. 10).

[0220] The connecting surface between the upper and lower portions of the container 2 is thicker than the remainder of the container 2. The reinforced connecting surface is designed to be used as support surfaces on a fixture, scaffold, or support structure in an application.

[0221] The carrier 3, which is also used as a membrane, is thinner than 1 mm. On the one hand, the carrier 3 must be elastic enough not to strongly hinder the deflection of the piezoelectric element 10. On the other hand, the carrier 3 must have a certain stability so that it will not be damaged when an external force is applied, such as when it is irradiated with water for cleaning. An advantageous compromise was found with a thickness of the carrier 3 of less than 1 mm and more than 0.2 mm.

[0222] The walls are at least 1.5 times as thick as the carrier 3, but should be thicker than 3 times the thickness of the carrier 3 if possible. Such a thick wall thickness is suitable to reduce the transmission of vibrations of the carrier 3 or the membrane to the connecting surface between the upper and lower parts of the container 2. Since the connecting surface may be a supporting surface of the ultrasonic transducer 1 to a mounting, vibrations and deflections should be avoided especially at these connecting surfaces. Otherwise, vibrations may be transmitted to an adjacent fixture that is part of the application. The transmitted vibrations can in turn be reflected and therefore be falsely detected in the ultrasonic transducer 1 as a phantom signal. A wall thickness that is at least 1.5 times the thickness of the membrane reduces the transmission of vibrations from the carrier 3 to other parts of the container 2, thus helping to pervent this problem.

[0223] The lid 16 is a printed circuit board and has a digital I/O interface 25 on one side facing outward.

[0224] The digital I/O interface 25 is not only used to communicate with the outside, but also to supply the electronics 17 and thus the piezoelectric element 10 with electricity. The electronics 17 are arranged on one side of the lid 16, which faces into the interior of the container 2.

[0225] The arrangement of the digital I/O interface 25 on the lid 16 enables a compact design of the ultrasonic transducer 1 and simple contacting, since no further connections need to be considered. In contrast to analog interfaces, a digital I/O interface 25 has a high tolerance with respect to interference signals, which may come from nearby electric motors, for example. For example, the interface can also be implemented with an FFC connector. This provides a debug interface via its eight contacts, which offers a variety of readout options that can be particularly advantageous for developers and for more complex applications. As a particularly simple alternative, a 2- or 3-wire interface can be used as an interface. These are the most cost-effective interfaces compared to the previously mentioned alternatives. Simple pin headers provided with two to eight pins are also possible as an interface for the ultrasonic transducer 1.

[0226] The lid 16 is mechanically attached to the container 2 by an annular, elastic adhesive connection 18. The annular, elastic adhesive connection 18 is not electrically conductive. The annular, elastic adhesive connection 18 is attached to the side of the lid 16 facing into the interior of the container 2, between the lid 16 and the container 2.

[0227] Additionally or alternatively, electrically conductive elastic adhesive connections 19 are provided between the electronics 17 and the container 2, electrically connecting the connection points of the electronics 17 and the conductor traces 8A and 8B. The electrically conductive elastic adhesive connections 19 can replace sections of the annular elastic adhesive connection 18 (cf. FIG. 10).

[0228] In addition, a second annular elastic adhesive connection 26 may be provided between the lid 16 and the container 2 on the side of the lid 16 facing outward. The second annular, elastic adhesive connection 26 seals the container 2 to the outside. The second annular, elastic adhesive connection 26 may have the same properties as the first annular, elastic connection 18 or other properties.

LIST OF REFERENCE SIGNS

[0229] 1 ultrasonic transducer [0230] 2 container [0231] 2A anodised layer [0232] 3 Carrier, bottom [0233] 3A inner side of the carrier [0234] 4 wall [0235] 4A inner side of the wall [0236] 5 opening [0237] 6 cavity [0238] 7 insulation layer [0239] 8 conductor trace [0240] 8A first conductor trace [0241] 8B second conductor trace [0242] 9 contact area [0243] 9A first contact area [0244] 9B second contact area [0245] 9C recesses [0246] 9D elevation [0247] 10 piezoelectric element [0248] 11 lower side [0249] 12 upper side [0250] 13 side surface [0251] 14 electrodes [0252] 14A first electrode [0253] 14B second electrodes [0254] 15 adhesive connection [0255] 16 lid [0256] 17 electronics [0257] 17A first connection point [0258] 17B second connection point [0259] 18 first annular, elastic adhesive connection [0260] 19 electrically conductive, elastic adhesive connections [0261] 19A First electrically conductive elastic adhesive connection [0262] 19B second electrically conductive elastic adhesive connection [0263] 20 conductive particles [0264] 21 AC capacitor [0265] 22 vibration damping component [0266] 23 adhesive material [0267] 24 damping element [0268] 25 I/O interface [0269] 26 second annular elastic adhesive connection