AU2021224835B2

AU2021224835B2 - Waterborne sound transducer

Info

Publication number: AU2021224835B2
Application number: AU2021224835A
Authority: AU
Inventors: Nils Theuerkauf; Christoph Zimmer
Original assignee: ThyssenKrupp AG; Atlas Elektronik GmbH
Current assignee: ThyssenKrupp AG; Atlas Elektronik GmbH
Priority date: 2020-02-21
Filing date: 2021-02-11
Publication date: 2023-08-10
Anticipated expiration: 2041-02-11
Also published as: EP4107543A1; AU2023226679A1; WO2021165146A1; AU2021224835A1; DE102020202275A1

Abstract

A waterborne sound transducer (20) having a multiplicity of transducer units (22) is disclosed. The transducer units are arranged in a two-dimensional manner, wherein the transducer units (22) each have a first and a second contact face. The first contact faces of the transducer units (22) are each connected to a first electrode (24a). The second contact faces of the transducer units (22) are each connected to a second electrode (24b). The transducer units (22) are arranged in such a way that an envelope of the first contact faces of the transducer units (22) is pillow-shaped.

Description

WATERBORNE SOUND TRANSDUCER

1. FIELD OF THE INVENTION

The invention relates to the optimization of waterborne sound transducers for specific tasks.

2. BACKGROUND OF THE INVENTION

Waterborne sound transducers (both transmitters and receivers) are typically designed with respect to their directional characteristic for a certain frequency range. o Outside this frequency range, the transducers deviate from the desired behavior, so that, for example, the required coverage and detection performance is no longer provided. That is to say, waterborne sound transducers, also referred to as hydrophones, are optimized to achieve the greatest possible sensitivity in a frequency range that is bounded depending on the field of use of the waterborne sound transducers. Such waterborne sound transducers are then designed to receive, for example, waterborne sound signals emitted by active sonar, so-called pings, or to record signatures of water vehicles by means of passive sonar. The waterborne sound transducers have the disadvantage for certain applications, however, that they are only optimized for a predefined, narrow frequency range of, ,0 for example, ±10% of a center frequency. The frequency response is then strongly dependent on frequency and direction. Frequencies which are detected worse can thus be overlaid by frequencies which are detected better. An image is thus generated which distorts reality if the surroundings are to be searched over a large frequency range.

Against this background it would be advantageous to provide an improved concept for waterborne sound transducers.

3. SUMMARY OF THE INVENTION

The present invention provides (i) a waterborne sound transducer, (ii) an array of waterborne sound transducers, (iii) a method for producing a waterborne sound

19321957_1 (GHMatters) P118142.AU transducer and (iv) a method for optimizing a waterborne sound transducer as defined in the independent patent claims, respectively..

A waterborne sound transducer in accordance with the invention has a plurality of transducer units which are arranged two-dimensionally, wherein the transducer units each have a first and a second contact surface. The first contact surfaces of the transducer units are each connected (in particular at least electrically) to a first electrode (which is in particular shared) and the second contact surfaces of the o transducer units are each connected (in particular at least electrically) to a second electrode (which is in particular shared). Furthermore, the transducer units are arranged in such a way that an envelope of the first contact surfaces of the transducer units is cushion-shaped. The envelope is also referred to as the contour of the waterborne sound transducer. Cushion-shaped means that the envelope is shaped convexly, thus curved outward. The cushion shape can be symmetrical, in particular symmetrical in a vertical and/or in a horizontal extension of the waterborne sound transducer. The vertical and horizontal extensions, respectively, refer to a predetermined orientation during the use of the waterborne sound transducer. In accordance with the invention, the cushion shape envelope is curved in two o dimensions (x, y). An elevation of the waterborne sound transducer in both dimensions thus results. A directional characteristic of the waterborne sound transducer can thus be set for both dimensions independently of one another.

The transducer units are, for example, rods made of a piezoelectric material, in particular a piezoceramic, for example lead-zirconate-titanate (PZT). The transducer units can be potted using a potting compound, for example a resin or a plastic, to form a piezocomposite matrix, in particular a piezocomposite ceramic.

The concept of the invention is to arrange the transducer units not only in a two dimensional, flat plane, but also three-dimensionally so that the first contact surfaces are contained in curved plane, i.e. the cushion-shaped envelope. A desired behavior, for example a frequency response, of the waterborne sound transducer can thus be

19321957_1 (GHMatters) P118142.AU set by the three-dimensional arrangement of the transducer units. The cushion shape has the result that the horizontal frequency response of the waterborne sound transducer is optimized in such a way that the sensitivity of the waterborne sound transducer remains constant over a large frequency range of, for example, 350 kHz +70% (= the operating range of the waterborne sound transducer) over a receiving angle. For adjacent receiving angles, the sensitivity (ideally) decreases linearly. A triangular sensitivity over the direction ideally results for all frequencies in the working range. The damping at 150 is, for example, approximately 6 dB. Expressed more precisely, the triangular sensitivity ideally has the shape of a straight prism having o triangular base and cover surfaces. A waterborne sound transducer can thus receive sound waves horizontally over a (single) transmitting or receiving angle and a large frequency range, without the sound waves being influenced by the transducer characteristic. To achieve this, a reduction of the sensitivity of the waterborne sound transducer is also accepted for some frequencies.

The potential of such a waterborne sound transducer becomes clear when a plurality of waterborne sound transducers are arranged in a circle, more precisely in a regular polygon, to form an array . That is to say that, for example, 12 waterborne sound transducers are arranged to form a regular dodecagon. Such an arrangement o enables an essentially constant sensitivity of the array of waterborne sound transducers to be obtained over the complete azimuth, thus over a horizontal angle of 3600. The constant sensitivity of the array of the waterborne sound transducers is provided here via the three-dimensional arrangement of the transducer units in relation to one another. In other words, the triangular sensitivity of adjacent waterborne sound transducers adds up to form an (ideally) constant sensitivity.

Furthermore, the vertical frequency response of the waterborne sound transducer is also set by the three-dimensional arrangement of the transducer units according to a desired behavior by the cushion shape. The cushion shape has the result that the frequency response of the waterborne sound transducer is optimized in such a way that the sensitivity of the waterborne sound transducer remains constant over a large frequency range of, for example, 350 kHz + 70% (= the operating range of the

19321957_1 (GHMatters) P118142.AU waterborne sound transducer) over a large receiving angle of, for example, 15. A trapezoidal sensitivity ideally results over the direction for all frequencies in the working range. Expressed more precisely, the trapezoidal sensitivity ideally has the shape of a straight prism having trapezoidal base and cover surfaces. The waterborne sound transducer can thus receive sound waves vertically over a large transmitting or receiving angle of, for example, 300 and a large frequency range without the sound waves being influenced by the transducer characteristic.

In exemplary embodiments, the transducer units are arranged on a base element. An o upper side of the base element, which faces in the direction of the transducer units, and a lower side of the base element opposite to the upper side, and the envelope have the same shape. That is to say, in the event of a parallel displacement of the envelope on the upper side or the lower side of the base element, the envelope and the upper side or the lower side of the base element are congruent. Such an embodiment is advantageous if the waterborne sound transducer is subjected to various ambient pressures, for example underwater at various water depths. The envelope (contour) of the contact surfaces is not to change due to external pressure, in particular also due to water pressure as a function of the immersion depth. Otherwise, the properties of the waterborne sound transducer, in particular its o sensitivity, would change depending on frequency and/or direction. It is advantageous to also select the shape of the lower side of the base element like the shape of the upper side of the base element. A constant change of the properties of the waterborne sound transducer, i.e. independent of frequency and/or direction, can then be obtained in the event of pressure changes. The base element is then compressed over the entire surface to the same extent in the event of a pressure increase.

However, this finding also applies to transducer units not arranged in a cushion shape. Thus, one exemplary embodiment of a second aspect discloses a waterborne sound transducer having a plurality of transducer units which are arranged two dimensionally on a base element. The transducer units each have a first and a second contact surface. The first contact surfaces of the transducer units are

19321957_1 (GHMatters) P118142.AU connected (advantageously electrically and mechanically) to a first electrode and the second contact surfaces of the transducer units are connected (advantageously electrically and mechanically) to a second electrode. An upper side of the base element, which faces in the direction of the transducer units, and a lower side of the base element opposite to the upper side, and an envelope of the first contact surfaces have the same shape. The waterborne sound transducer of the second aspect differs from the above-mentioned waterborne sound transducer solely in that the shape of the envelope of the transducer units is arbitrary and that this shape is obligatorily (and not optionally) transferred to the upper side and the lower side of the o base element. However, the cushion shape is also a possible configuration in the second exemplary embodiment. The following exemplary embodiments can relate to both waterborne sound transducers - wherein exemplary embodiments of the cushion shape relate to the exemplary embodiment of the second aspect which introduces the cushion shape.

The waterborne sound transducers can be constructed in stacked form. The waterborne sound transducers in exemplary embodiments thus have a stack having the following layers: in a first layer, the stack comprises the base element, in a second layer, the second electrode is arranged above the upper side of the base o element, in a third layer, the transducer units are arranged two-dimensionally above the second electrode, in a fourth layer, the first electrode is arranged above the transducer units. The transducer units can each electrically contact the first electrode using a first contact and can electrically contact the second electrode using a second contact. The transducer units are typically also mechanically connected to the first or the second electrode, respectively, in the event of an electrical contact.

Exemplary embodiments show that the cushion shape Zh(x) has a contour in a first (for example horizontal) dimension (x), which is bounded by the polynomial Zh(X) = X2 . x2 + X 4 . x 4 +X 6 x 6 + X8 . x 8 + X 10 - x1 0 + X1 2 . X12 + X 14 . x 14 + X16 - X 16 .

with X2 = -1.102248436127560E - 01 X4 = -7.798252809214000E + 04

19321957_1 (GHMatters) P118142.AU

X6= 3.080405149858780E + 08 X8= 4.015851040327540E + 11 Xi = -4.977431310325020E + 15 X12 = 2.614009340410490E + 18 X14= 2.687463597223600E + 22 Xi6= -3.790562133342640E + 25 and a tolerance of 0.001 m, preferably 0.0005 m, particularly preferably 0.0001 m. The tolerance describes an offset of the functionZh(X), i.e. a displacement along the z axis. In other words, the tolerance is added as a constant term to the function or o subtracted therefrom. That is to say, the contour lies in the first dimension inside the area which is enclosed by the polynomial and the maximum tolerance, in particular the contour in the first dimension has the shape of the polynomialZh(x). An extension of the cushion in the first dimension is preferably between 0.03 m and 0.05 m, preferably between 0.035 m and 0.045 m, particularly preferably between 0.038 m and 0.040 m, for example 0.039 m.

If the cushion shape is within the described limits for the first dimension, a waterborne sound transducer results which has a triangular sensitivity over the frequency in the first dimension. This is advantageous if waterborne sound o transducers are arranged in an array, so that they have a constant sensitivity over the direction in total. The contour is optimized, for example, for a waterborne sound transducer, the transducer units of which are arranged equidistantly and/or the transducer units of which have a density of 40 to 60 transducer units per square centimeter. The first dimension is, for example, the horizontal.

Similarly, one exemplary embodiment shows that the cushion shape z,(y) has a contour in a second (for example vertical) dimension (y) which is bounded by the polynomial 30 z,(y) = y22vY y2 + y44 y4 + ya y6 + ye y8+Y 1 - Y10 + Y12 . y12 + Y14 - y14 + Y16 -y16.

with Y2 = -15.6474404327660 Y4= 81025.7633563034

19321957_1 (GHMatters) P118142.AU

Y6= -1246494097.34679 Y8= 13481472680661.9 Yi = -8.53691186195647e + 16 Y2 = 2.29508952803708e + 20 Y1 =-2.12497987038051E + 22 Y16 =-6.32568522314303E + 26 and a tolerance of 0.001 m, preferably 0.0005 m, particularly preferably 0.0001 m. The tolerance describes an offset of the function z,(y), i.e. a displacement along the z axis. In other words, the tolerance is added as a constant term to the function or o subtracted therefrom. That is to say, the contour is within the area which is enclosed by the polynomial and the maximum tolerance, in particular the contour has the shape of the polynomial z,(y) in the second dimension. An extension of the cushion in the second dimension is preferably between 0.023 m and 0.04 m, preferably between 0.027 m and 0.035 m, particularly preferably between 0.030 and 0.032 m, for example 0.031 m.

If the cushion shape is within the described limits for the second dimension, a waterborne sound transducer results which has a trapezoidal sensitivity over the frequency in the second dimension. The contour is optimized, for example, for a o waterborne sound transducer, the transducer units of which are arranged equidistantly and/or the transducer units of which have a density of 40 to 60 transducer units per square centimeter. The second dimension is, for example, the vertical.

The first dimension is arranged, for example, perpendicularly to the second dimension. In other words, the first and the second dimension span an area from which the cushion shape rises in a third direction. That is to say, in still other words, that an elevation (= third dimension) of the cushion shape results from the superposition of the cushion shape in the first dimension and the cushion shape in the second dimension. The cushion shape z(x,y) is mathematically described as follows: z(x,y) = Zh(X) + z(y). The tolerances can also add up here. The resulting cushion shape can thus be located within a volume which is formed by the function

19321957_1 (GHMatters) P118142.AU z(x,y) with the tolerance in the z direction. In particular, the cushion shape can have the shape of the function z(x,y).

The cushion shape has, for example, a maximum elevation of less than 0.007 m. In other words, a transducer unit which is arranged centrally (in the x-y direction) in the cushion shape can be arranged up to 0.007 m higher (in the z direction) than a transducer element which is arranged at the edge (in the x-y direction) of the cushion shape.

o The shape of the envelope, thus the cushion shape, can accordingly be describable by a polynomial, but also, for example, by a Fourier series or by a function defined in sections, for example a step function. If the cushion shape is within the described limits for the volume, a waterborne sound transducer results which, because of the geometry, already has a triangular sensitivity over the frequency in the first dimension and a trapezoidal sensitivity over the frequency in the second dimension within a frequency range of 100 kHz to 600 kHz. The contour is optimized, for example, for a waterborne sound transducer, the transducer units of which are arranged equidistantly and/or the transducer units of which have a density of 40 to 60 transducer units per square centimeter.

In exemplary embodiments, the transducer units (of the plurality of transducer units) have the same distance between the first and the second contact surface. In other words, all transducer units have the same length. This is advantageous to avoid nonlinear effects due to the transducer units as such, which would have to be taken into consideration in the dimensioning of the waterborne sound transducer. If the transducer units were of different lengths, they would output a different output voltage at equal incident sound pressure. However, this is to be avoided.

In exemplary embodiments, the base element is designed to absorb sound waves. In other words, the base element can have a material which damps and thus absorbs sound. The waterborne sound transducer can thus be designed as much as possible not to generate scattered sound due to reflections, so as not to worsen the set

19321957_1 (GHMatters) P118142.AU properties of the waterborne sound transducer. However, it is also possible in principle to design the waterborne sound transducer so that reflections are taken into consideration. The base element can then also be designed as a sound reflector.

It was already described above that the waterborne sound transducers can advantageously be arranged to form an array. An array of waterborne sound transducers is thus disclosed which has a plurality of the described waterborne sound transducers. The waterborne sound transducers of the plurality of waterborne sound transducers are arranged in a ring shape to form the array. The first contact o surfaces each face outward and the second contact surfaces each face toward the ring center. Due to the planar configuration of the waterborne sound transducers, of course, the ring can only be approximated. More precisely, the waterborne sound transducers are arranged to form a (regular) polygon. Adjacent waterborne sound transducers advantageously adjoin one another, i.e. the ring or the polygon is closed.

Exemplary embodiments furthermore disclose the array, wherein further waterborne sound transducers, in particular further ones of the above-mentioned waterborne sound transducers, are arranged separately from the ring of waterborne sound transducers, wherein the further waterborne sound transducers are arranged at an o angle between 20 degrees to 50 degrees in relation to the waterborne sound transducers of the ring. This is advantageous so that sound waves which are incident laterally on the ring, thus vertically on the waterborne sound transducers, can be detected better. In other words, the further waterborne sound transducers cover the upper hemisphere of the array.

Similarly, a method for producing a waterborne sound transducer having the following steps is disclosed: two-dimensionally arranging a plurality of transducer units, wherein the transducer units each have a first and a second contact surface; connecting each of the first contact surfaces of the transducer units to a first electrode; connecting each of the second contact surfaces of the transducer units to a second electrode; wherein the transducer units are arranged in such a way that an envelope of the first contact surfaces of the transducer units is cushion-shaped;

19321957_1 (GHMatters) P118142.AU and/or wherein the transducer units are arranged on a base element, wherein an upper side of the base element, which faces in the direction of the transducer units, and a lower side of the base element opposite to the upper side, and the envelope have the same shape.

Furthermore, a method for optimizing a waterborne sound transducer having the following steps is disclosed: calculating an output signal of a waterborne sound transducer having a plurality of transducer units for a plurality of sound waves which are incident on the waterborne sound transducer from different directions; varying an o elevation of a selection of transducer units of the plurality of transducer units; repeating the calculation of the output signal and the variation of the elevation until the waterborne sound transducer is optimized for predefined boundary conditions.

A computer model thereof is advantageously used as the waterborne sound transducer, which simulates the properties of a real waterborne sound transducer. The calculation can therefore also be referred to as a simulation. The elevation of the individual transducer units can furthermore also be carried out in the model. The model of the waterborne sound transducer can furthermore also comprise the (evaluation) electronics thereof. The boundary conditions can be the constant o sensitivity described in this disclosure for the array of the waterborne sound transducers. A further or alternative boundary condition can be the reduction of the influence of interference noises, for example for the selection of the base element.

The deviation of the real directional characteristic from the desired directional characteristic of the transducer element is minimized, for example, by the variation of the elevation by computer. The directional characteristic can be a predefined boundary condition, so that the minimization represents the optimization of the predefined boundary condition. The sensitivity depending on frequency and angle is referred to as the directional characteristic. That is to say, the directional characteristic is optimized over all frequencies of the operating range. In other words, the sensitivity depending on frequency and angle is adapted to the desired directional characteristic.

19321957_1 (GHMatters) P118142.AU

A method is accordingly also disclosed for optimizing an array of waterborne sound transducers, wherein the output signal of a plurality of waterborne sound transducers is calculated and wherein the elevation of the selection of transducer units is carried out for the corresponding transducer units of each waterborne sound transducer in the array.

Preferred exemplary embodiments of the present invention are explained hereinafter with reference to the appended drawings.

4. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1: shows a schematic illustration of a waterborne sound transducer, wherein figure 1a shows a schematic sectional illustration and figure 1b shows a schematic perspective illustration of the waterborne sound transducer;

Figure 2: shows a schematic idealized illustration of a plot of the sensitivity of the waterborne sound transducer over the frequency and the direction of the incident sound waves, wherein figure 2a illustrates the horizontal sensitivity and figure 2b illustrates the vertical sensitivity;

Figure 3: shows a schematic illustration of two transducer units, on which sound waves S(t) are incident;

Figure 4: shows a schematic perspective illustration of an array of the waterborne sound transducers; and

Figure 5: shows a schematic idealized illustration of a plot of the sensitivity of the array of waterborne sound transducers over the frequency and the direction of the incident sound waves.

5. DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

19321957_1 (GHMatters) P118142.AU

Before exemplary embodiments of the present invention are explained in more detail on the basis of the drawings hereinafter, it is to be noted that identical, functionally similar, or similarly acting elements, objects, and/or structures are provided with the same reference signs in the various figures, so that the description of these elements represented in different exemplary embodiments can be exchanged with one another or can be applied to one another.

Figure 1a shows a schematic sectional illustration of a waterborne sound transducer 20. The waterborne sound transducer 20 has a plurality of transducer units 22, a first o electrode 24a, and a second electrode 24b. Furthermore, an optional base element 26 and an optional structure element 28 are shown.

The transducer units 22 have a first and a second contact surface, which are at least electrically connected to the first or the second electrode 24a, 24b, respectively. The contact surfaces are formed, for example, by the (opposing) end faces of the transducer units. The transducer units 22 are arranged two-dimensionally (x, y) (cf. figure 1b). Furthermore, the transducer units 22 also have an elevation (z) in a third dimension (perpendicular to the first and the second dimension). A cushion-shaped, i.e. convex, envelope of the transducer units results here due to the elevation. The o shape of the envelope corresponds here to the shape of the first electrode 24a. In principle, the shape or contour of the envelope can be freely selected for waterborne sound transducers which are optimized differently. The cushion-shaped envelope is advantageous, however, to obtain the most constant possible sensitivity over the direction and the frequency (within an operating range of the transducer units).

In exemplary embodiments, the individual transducer units 22 are potted by means of a potting compound 30, for example a resin or a plastic. The potting compound 22 fills up the spaces between the transducer units 22. The contact surfaces of the transducer units 22 remain free or are subsequently exposed, however. A piezocomposite matrix thus results. If the transducer units are molded from a piezoceramic, the matrix is also referred to as a piezocomposite ceramic.

19321957_1 (GHMatters) P118142.AU

The optional base element 26 is designed to exert a defined influence on the incident sound waves. Typical influences are the reflection or the absorption of the sound waves. The selection of the base element is dependent on the optimization of the envelope of the transducer units. That is to say, the base element is already also to be taken into consideration in the optimization of the envelope of the transducer units. On the other hand, reflected or non-reflected sound waves could destroy the set properties of the waterborne sound transducer.

The optional structure element 28 offers the required strength for the waterborne o sound transducer. Furthermore, the structure element 28 offers the option of simpler fastening of the waterborne sound transducer for example on a watercraft, in particular a submarine.

Figure 1b shows a schematic perspective illustration of the waterborne sound transducer 20. The two-dimensional arrangement of the transducer units 22 in the x-y plane is also visible here. The transducer units 22 can be arranged equidistantly. The cushion-shaped envelope of the transducer units 22 can also be seen. The first electrode 24a is not shown, so that the view of the transducer units 22 is exposed. The transducer units can have a density of 40 to 60 transducer units per square o centimeter (in the x-y plane). The density or the size of the transducer units is substantially dependent, however, on the operating range (frequency range) for which the waterborne sound transducer is used.

The shape of the envelope, i.e. the cushion shape, is implemented, for example, by the superposition of the polynomials 14 Zh(X) = X2 - x 2 + X4 . 4 x +X 6 x 6 + X8 . x 8 + X1 0 - x1 + X1 2 . X12 + X1 4 . x + X16 . X16.

with X2 = -1.102248436127560E - 01 X4 = -7.798252809214000E + 04 X6 = 3.080405149858780E + 08

X8 = 4.015851040327540E + 11

Xio = -4.977431310325020E + 15

19321957_1 (GHMatters) P118142.AU

X12 = 2.614009340410490E + 18 X14= 2.687463597223600E + 22 X16= -3.790562133342640E + 25 and Z,(y) Y 2 2 y 4 y4 +Y 6 y 6 +y y 8+ Y 10 +Y 12 -y12 + Y14 y 14 +Y 16 y16.

with Y2 = -15.6474404327660 Y4= 81025.7633563034 Y6= -1246494097.34679 Y8= 13481472680661.9 Y10 = -8.53691186195647e + 16 Y 12 = 2.29508952803708e + 20 Y1 4 = -2.12497987038051E + 22 Y1 6 = -6.32568522314303E + 26

Figure 1a and figure 1b furthermore disclose a stacked structure of the waterborne sound transducer 22. The stack has the following layers: on the structure element (optional) as the starting layer, the stack comprises the base element 26 (optional) in a first layer, in a second layer, the second electrode 24b is arranged above an upper o side of the base element 26, in a third layer, the transducer units 22 are arranged two-dimensionally above the second electrode, in a fourth layer, the first electrode 24a is arranged above the transducer units 22. The layers are stacked so that a lower side of the present layer is opposite to, in particular mechanically contacts, the upper side of the preceding layer.

Figure 2a shows an exemplary smoothed sensitivity curve 32 of the waterborne sound transducer over the frequency and the horizontal direction (azimuth) of the incident sound waves on the waterborne sound transducer. The waterborne sound transducer is optimized in such a way that it has the most constant possible sensitivity for the same direction of incidence in the frequency range between 100 kHz and 600 kHz. The triangular configuration of the horizontal sensitivity curve thus results.

19321957_1 (GHMatters) P118142.AU

Figure 2b shows an exemplary smoothed sensitivity curve 32 of the waterborne sound transducer over the frequency and the vertical direction (elevation) of the incident sound waves on the waterborne sound transducer. The waterborne sound transducer is optimized in such a way that it has the most constant possible sensitivity for as many directions of incidence as possible in the frequency range between 100 kHz and 600 kHz. The trapezoidal configuration of the horizontal sensitivity curve thus results.

o Figure 3 shows a schematic perspective illustration of two transducer units 22a, 22b. The transducer units 22a, 22b have a (center) distance x in relation to one another. Waterborne sound waves S(t) are incident on the transducer units 22a, 22b. Due to the direction of incidence, i.e. an angle of incidence a between the transducer units and the wavefront of the waterborne sound waves, a distance d results which the waterborne sound waves cover between the incidence of the waterborne sound waves on the first transducer unit 22a and the second transducer unit 22b. This distance has the result that waterborne sound waves having a frequency f, which cover a multiple of twice the speed of sound in water c divided by the distance d

(f = ), extinguish one another. The waterborne sound waves interfere. This is the o reason why waterborne sound transducers having a plurality of transducer units have a direction-dependent sensitivity. This can be compensated for by corresponding signal processing of the individual transducer units.

In particular for receiving high frequencies, however, the transducer units are very small, so that a separate connection of the individual transducer units is possible only with great difficulty or not at all. The summation signal is therefore preferably analyzed, so that the transducer units each have a shared first and second electrode. In this case, however, separate signal processing of the individual signals of the transducer units is not possible. The distance d, in other words the runtime difference, which the waterborne sound S(t) covers after incidence on the first transducer unit 22a until arriving on the second transducer unit 22b, can be reduced by displacing the second transducer unit 22b in the arrow direction 34, i.e. an

19321957_1 (GHMatters) P118142.AU elevation thereof. The displaced second transducer unit 22b is shown by dashed lines.

Figure 4 shows an array 36 of waterborne sound transducers 20. The array 36 has a plurality of waterborne sound transducers 20a - 20e, which are arranged in a ring shape to form the array. The first contact surfaces of the waterborne sound transducers face outward, the second contact surfaces of the waterborne sound transducers face inward. In other words, the cushion shape, i.e. the elevation, of the waterborne sound transducers faces outward. In this arrangement, a constant o sensitivity over a large frequency range (approximately 100-600 kHz) is achieved over the entire azimuth using the described waterborne sound transducers.

Further waterborne sound transducers 20f, 20g, 20h are arranged separately from the ring of the waterborne sound transducers. These have an angle of inclination # in relation to the waterborne sound transducers 20a - 20e of the ring. The angle of inclination # is preferably between 200 and 500. In this arrangement, the elevation, i.e. the upper hemisphere, is furthermore also simulated by the array. The coverage of the vertical angle for the array in which the sensitivity is constant is then between 150 and 900.

Figure 5 shows an exemplary smoothed sensitivity curve 32 of the array of waterborne sound transducers over the frequency and the horizontal direction (azimuth) of the incident sound waves on the waterborne sound transducer. The waterborne sound transducer is optimized in such a way that it has the most constant possible sensitivity for the same direction of incidence in the frequency range between 100 kHz and 600 kHz. The triangular configuration of the horizontal sensitivity curve thus results.

All exemplary embodiments were directed to received waterborne sound waves. However, the disclosure is also similarly applicable to transmitted waterborne sound waves.

19321957_1 (GHMatters) P118142.AU

The disclosed acoustic transducers (waterborne sound transducers) are designed for use underwater, in particular in the ocean. The acoustic transducers are designed to convert waterborne sound into an electrical signal (for example voltage or current) corresponding to the sound pressure, the waterborne sound signal. In addition, the acoustic transducers are designed to convert an applied electrical signal (waterborne sound signal) into waterborne sound. The acoustic transducers can accordingly be used as waterborne sound receivers and/or as waterborne sound transmitters. The acoustic transducers are not usable for medical applications. The ratio of sound intensity to the resulting output signal of the waterborne sound transducer (for o example output voltage) is understood as the sensitivity of the acoustic transducer. The output signal of the waterborne sound transducer is also referred to as the waterborne sound signal.

Although some aspects were described in conjunction with a device, it is apparent that these aspects also represent a description of the corresponding method, so that a block or a component of a device is also to be understood as a corresponding method step or as a feature of a method step. Similarly thereto, aspects which were described in conjunction with a method step or as a method step also represent a description of a corresponding block or detail or feature of a corresponding device.

The above-described exemplary embodiments merely represent an illustration of the principles of the present invention. It is obvious that modifications and variations of the arrangements and details described herein can be apparent to other persons skilled in the art. It is therefore intended that the invention is solely restricted by the scope of protection of the following patent claims and not by the specific details which were presented herein on the basis of the description and the explanation of the exemplary embodiments.

19321957_1 (GHMatters) P118142.AU

List of reference signs:

20 waterborne sound transducer 22 plurality of transducer units 24 electrodes 26 base element 28 structure element 30 potting compound 32 sensitivity curve o 34 arrow direction

S(t) waterborne sound waves x (center) distance between two transducer units d distance for the waterborne sound waves a angle of incidence

19321957_1 (GHMatters) P118142.AU

Claims

PATENT CLAIMS

1. A waterborne sound transducer, comprising: a plurality of transducer units which are arranged two-dimensionally (x,y), wherein the transducer units each have a first and a second contact surface; a first electrode to which the first contact surfaces of the transducer units are each connected; and a second electrode to which the second contact surfaces of the transducer units are each connected; wherein the transducer units are further arranged in such a way that an envelope of the first contact surfaces of the transducer units is a cushion-shaped envelope curved along the two dimensions (x,y) resulting in an elevation of the waterborne sound transducer in both of the two dimensions (x,y) by which a directional characteristic of the waterborne sound transducer can be set for both dimensions (x,y) independently of one another.

2. The waterborne sound transducer as claimed in claim 1, further comprising a base element on which the transducer units are arranged.

3. The waterborne sound transducer of claim 2, wherein an upper side of the base element, which faces in the direction of the transducer units, a lower side of the base element opposite to the upper side, and the envelope have the same shape.

4. The waterborne sound transducer as claimed in any one of claims 1 to 3, wherein the cushion shapezh(x) has a contour in the first dimension (x), which is bounded by the polynomial ZhW X2 X2 + X4. X4 + X6 . X6 + X8 - X8 + X10 - X1° + X12 . X12 + X14 - x14 + X16 . X16

with X2= -1.102248436127560E - 01 X4= -7.798252809214000E + 04 X6= 3.080405149858780E + 08

19990917_1 (GHMaters) P118142.AU

X8 = 4.015851040327540E + 11 X10 = -4.977431310325020E + 15

X12 = 2.614009340410490E + 18 X14 = 2.687463597223600E + 22 X16 = -3.790562133342640E + 25 and a tolerance of 0.001 m, in particular 0.0005 m or in particular 0.0001 m.

5. The waterborne sound transducer as claimed in any one of claims 1 to 4, wherein the cushion shape z,(y) has a contour in the second dimension (y), which is bounded by the polynomial z(y) = Y 2 y 2 + 4 . y 4 +Y 6 6 + y 8. y 10 +Y 12 ' y 12+ Y 14 y 14 +Y 16 y 16

. with Y2 = -15.6474404327660 Y4 = 81025.7633563034 Y6 = -1246494097.34679 Y8 = 13481472680661.9 Y1o = -8.53691186195647e + 16 Y1 2 = 2.29508952803708e + 20 Y14 = -2.12497987038051E + 22 Y16 = -6.32568522314303E + 26 and a tolerance of 0.001 m, preferably 0.0005 m, particularly preferably 0.0001 m.

6. The waterborne sound transducer as claimed in claim 4 and 5, wherein the cushion shape z(x,y) results from the superposition of the cushion shape in the first dimension zh(x) and the second dimension z,(y).

7. The waterborne sound transducer as claimed in any one of the preceding claims, wherein the transducer units have a piezoceramic.

8. The waterborne sound transducer of claim 7, wherein the plurality of the transducer units are arranged to form a piezocomposite ceramic.

19990917_1 (GHMaters) P118142.AU

9. The waterborne sound transducer as claimed in any one of claims 2 to 8, wherein the base element is designed to absorb sound waves.

10. The waterborne sound transducer as claimed in any one of the preceding claims, wherein the waterborne sound transducer has a stack having the following layers: in a first layer, the stack comprises a or the base element, in a second layer, the second electrode is arranged above an upper side of the base element, in a third layer, the transducer units are arranged two-dimensionally above the second electrode, in a fourth layer, the first electrode is arranged above the transducer units.

11. The waterborne sound transducer as claimed in any one of the preceding claims, wherein the transducer units each electrically contact the first electrode with a first contact and electrically contact the second electrode with a second contact.

12. The waterborne sound transducer as claimed in any one of the preceding claims, wherein the transducer units are arranged equidistantly and/or have a density of 40 to 60 transducer units per square centimeter.

13. An array of waterborne sound transducers, comprising: a plurality of waterborne sound transducers as claimed in any one of the preceding claims, wherein the plurality of waterborne sound transducers are arranged in a ring shape to form the array, and wherein the first contact surface faces outward in each case and the second contact surfaces each face toward a center of the ring.

14. The array as claimed in claim 13, wherein further waterborne sound transducers as claimed in any one of claims 1 to 12 are arranged separately from the ring of the waterborne sound transducers, wherein the further waterborne sound transducers are arranged at an angle between 20 degrees to 50 degrees in relation to the waterborne sound transducers of the ring.

15. A method for producing a waterborne sound transducer comprising the following steps:

19990917_1 (GHMaters) P118142.AU two-dimensionally arranging a plurality of transducer units that each have a first and a second contact surface such that the first contact surfaces of the transducer units define a cushion-shaped envelope curved along the two dimensions (x,y) thereby providing a varying elevation (z) of the waterborne sound transducer in both of the two dimensions (x,y) that allows setting of a directional characteristic of the waterborne sound transducer for both dimensions (x,y) independently of one another; connecting each of the first contact surfaces of the transducer units to a first electrode; and connecting each of the second contact surfaces of the transducer units to a second electrode.

16. The method of claim 15, wherein the transducer units are arranged on a base element; and wherein an upper side of the base element, which faces in the direction of the transducer units, a lower side of the base element opposite to the upper side, and the envelope have the same shape.

17. A method for optimizing a waterborne sound transducer having the following steps: calculating an output signal of a waterborne sound transducer having a plurality of transducer units arranged in a two-dimensional array (x, y) for a plurality of sound waves which are incident on a first surface of the transducer units from different directions on the waterborne sound transducer; varying an elevation (z) of the first surface of a selection of transducer units of the plurality of transducer units; and repeating the calculation of the output signal and the variation of the elevation until a three-dimensionally curved envelope of the first contact surfaces is obtained and the waterborne sound transducer is optimized for a predefined boundary condition in which the sensitivity of the transducer remains constant over a large

19990917_1 (GHMaters) P118142.AU predetermined frequency range over a receiving angle but decreases linearly for adjacent receiving angles.

19990917_1 (GHMaters) P118142.AU