Sound transducer

Abstract

The present invention relates to a sound transducer (1), in particular an ultrasonic transducer, having a diaphragm cup (2) with a side wall (3) and an end diaphragm (4), at least two excitation elements (5), in particular piezo elements, being mounted on the diaphragm (4) within the diaphragm cup (2), at least one web (6) being mounted on the diaphragm (4) between the excitation elements (5), the web (6) being connected to or formed integrally with the diaphragm (4), the web (6) extending between two regions of the side wall (3) and mechanically separating the excitation elements (5) from one another, and the excitation elements (5) being controllable separately from one another.

Description

[0001] R.412181

[0002] - 1 -

[0003] Description

[0004] title

[0005] transducer

[0006] State of the art

[0007] The present invention relates to a sound transducer, in particular an ultrasonic transducer. The invention also relates to a vehicle comprising such a sound transducer.

[0008] Ultrasonic parking sensors are a known technology for vehicles. The measuring principle of ultrasonic parking sensors is based on acoustic waves. These are emitted in the inaudible range and reflected by an obstacle. The reflected signal is received by the ultrasonic parking sensor, and the electronics evaluate the signal using a time-of-flight measurement. All ultrasonic parking sensors utilize a piezoelectric element to convert electrical energy into acoustic energy. However, this single element limits the sensor's operating range to a single direction of sound emission. While other physical effects, such as lidar or radar, could be used for parking sensors, ultrasound enables the production of very cost-effective parking sensors.

[0009] To extend the sensing range of ultrasound sensors, phased ultrasound arrays are already being used in medicine, as revealed, for example, in the following document: AS Savoia, “Design, Fabrication, Characterization, and System Integration of a 1-D PMUT Array for Medical Ultrasound Imaging,” 2021 IEEE International Ultrasonics Symposium (IUS), p. 4, 2021. Phased ultrasound arrays are based on an array of individual ultrasound transducers. If the individual ultrasound transducers are driven with a phase shift, this can be applied to R.412181.

[0010] - 2 -

[0011] The direction of ultrasound radiation can be changed. This allows a volume to be scanned using an ultrasound phased array, and even acoustic imaging can be performed.

[0012] German patent DE 10 2013 213 493 A1 is also known from the prior art. This patent discloses filling the space between two ultrasonic transducers with a plastic material, primarily intended for sealing but also preventing coupling between adjacent ultrasonic transducers. German patent DE 10 2013 222 076 A1 discloses a one-piece resonator, for example, designed as a membrane pot, which can incorporate several piezoelectric elements. Furthermore, US patent 2008 / 0238259 discloses an array of several ultrasonic transducers, wherein the space between the transducers is filled with a resin intended to reduce interference between the transducers.

[0013] Disclosure of the invention

[0014] The transducer according to the invention makes it possible, in particular, to provide the functions of an ultrasonic phased array with multiple excitation elements, for example piezoelectric elements, by inserting several excitation elements into a specially shaped membrane pot. This is a compact and cost-effective solution. The invention presented here also differs significantly from PMUTs (piezoelectric micromachined ultrasonic transducers) because no cleanroom processes are used, thus saving unnecessary costs.

[0015] The membrane pot features a rib. This allows for mechanical decoupling of the excitation elements and enables the use of an ultrasonic phased array. An ultrasonic phased array is a combination of multiple ultrasonic transmitters or receivers. These can be excited with a phase shift to transmit or receive in a specific direction. The advantage of this approach is that the elements are decoupled from each other as effectively as possible. By preventing mechanical crosstalk, the directional detection of a received signal is improved.

[0016] The sound transducer according to the invention is in particular an ultrasonic transducer. The sound transducer has a diaphragm pot with a side wall and an R.412181

[0017] - 3 - end-face membrane. The side wall is formed in particular around the perimeter and thus forms a closed cross-section of the membrane pot. The shape of the end-face membrane therefore determines the shape of the membrane pot, which can be in particular round or oval or rounded or angular or a combination thereof.

[0018] Within the membrane housing, at least two excitation elements are applied to the membrane. These excitation elements are, in particular, piezoelectric elements, preferably piezoelectric substrates. The excitation elements serve, in particular, to set the membrane into vibration so that an ultrasound signal is emitted. Preferably, the excitation elements should be semicircular or quarter-circular in shape, but other arbitrary geometries are also possible, such as: full circle, elliptical, square, or rectangular.

[0019] At least one bridge is applied between the excitation elements on the membrane. The bridge is either connected to the membrane or formed integrally with it and extends between two areas of the side wall. Preferably, the bridge is formed integrally with the side wall or rigidly connected to it. This mechanically separates the excitation elements from one another. In particular, the risk of crosstalk is minimized. The excitation elements can be controlled independently. This allows, in particular, time-shifted control of the excitation elements, thereby controlling the direction of the emitted sound. If the transducer serves as a receiver, the direction of the received sound can be determined. The excitation elements of the transducer can thus be used as an ultrasonic phased array. The transducer's design is simple and cost-effective, while achieving reliable operation.

[0020] The dependent claims describe preferred embodiments of the invention.

[0021] Preferably, at least one bridge has a recess on the side facing away from the diaphragm. This allows parasitic vibrations in this bridge to be dampened or prevented. This reduces or prevents the bridge from vibrating with the diaphragm, thereby avoiding mechanical crosstalk. R.412181

[0022] - 4 - can. Furthermore, this reduces or prevents sensor oscillation.

[0023] Advantageously, at least one strut directly adjacent to the side wall has its greatest extension away from the membrane. This extension decreases with increasing distance from the side wall. This means, in particular, that the strut is attached to the side wall over a large area, thus reducing the amount of free space. As a result, the strut is rigid and the risk of it vibrating with the membrane is reduced. The extension of the strut above the membrane decreases to a minimum value, especially with increasing distance from the side wall. Beyond a predefined distance from the side wall, the extension of the strut above the membrane preferably remains constant at this minimum value. Thus, the extension of the strut across the center of the membrane is minimized.

[0024] The membrane preferably has thickenings that extend, in particular, into the membrane pot. These thickenings are preferably not connected to the side wall. The excitation elements are mounted on these thickenings. Specifically, one excitation element is mounted on each thickening. Since the thickenings, in particular, have no contact with the wall, they act as seismic masses and reduce the membrane's resonance frequency. Thus, even small membrane sections, which can be created by subdividing the membrane with the struts, can be reliably set into vibration to reliably emit or receive sound, preferably ultrasound.

[0025] In a further preferred embodiment, several excitation elements are stacked on top of each other on the membrane. This increases the seismic mass, thereby lowering the membrane's resonance frequency. At least one of the excitation elements in each stack is controllable. In particular, it is not necessary to also control the remaining excitation elements in the stack; these then serve only to increase the seismic mass for adjusting the resonance frequency. R.412181

[0026] - 5 -

[0027] The sound transducer preferably has several struts. Advantageously, the struts extend from the center of the diaphragm in a cross-shaped or star-shaped pattern to a respective region of the side wall. Preferably, a common recess for the struts is provided at the center of the diaphragm, the recess being configured as described above. Alternatively or additionally, the struts advantageously extend separately between two regions of the side wall. The struts do not, in particular, touch each other. It is preferably provided that the separate struts extend parallel to each other. Alternatively or additionally, the struts run in a V-shape between different regions of the side wall.

[0028] In an advantageous embodiment, the at least one bridge has a constant wall thickness. The wall thickness is measured, in particular, perpendicular to the bridge's extent across the membrane. The wall thickness is thus, in particular, a dimension measured parallel to a surface of the membrane. Due to the uniform wall thickness, the area of ​​the membrane fixed by the bridge is minimized. This allows large areas of the membrane to be available for vibration excitation by the excitation elements.

[0029] In an advantageous embodiment, the bridge is designed as a full-surface cover for the membrane. The cover features, in particular, recesses for attaching the excitation elements to the membrane. This achieves optimal damping of the membrane's vibration, resulting in optimal separation of the excitation elements on the membrane. Consequently, the individual areas of the membrane can be used optimally and independently of one another for sound generation and / or sound reception.

[0030] The invention also relates to a vehicle. The vehicle has at least one sound transducer as described above. The vehicle is designed to detect objects in the vicinity of the vehicle by emitting sound and capturing the sound reflected by objects in the vehicle's surroundings. The emission and / or capture of the sound is accomplished with the sound transducer. The sound transducer is, in particular, an ultrasonic parking sensor. R.412181

[0031] - 6 -

[0032] A particularly advantageous feature of the vehicle is its control unit. This control unit is designed to control the excitation elements of the transducer independently. In this way, the individual excitation elements of the transducer form an ultrasonic phased array. This enables spatially varied emission and / or reception of sound. Consequently, the detection range and / or accuracy of an ultrasonic parking sensor based on the transducer is significantly improved.

[0033] Brief description of the drawings

[0034] Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawings. The drawing shows:

[0035] Figure 1 is a schematic representation of a vehicle according to a

[0036] Exemplary embodiment of the invention with a sound transducer,

[0037] Figure 2 is a schematic illustration of a sound transducer according to a first embodiment of the invention,

[0038] Figure 3 shows a schematic sectional view through the sound transducer according to the first embodiment of the invention,

[0039] Figure 4 shows a schematic illustration of a sound transducer according to a second embodiment of the invention.

[0040] Figure 5 is a schematic illustration of a sound transducer according to a third embodiment of the invention.

[0041] Figure 6 shows a schematic sectional view through the sound transducer according to a fourth embodiment of the invention,

[0042] Figure 7 is a schematic illustration of a sound transducer according to a fifth embodiment of the invention,

[0043] Figure 8 is a schematic illustration of a sound transducer according to a sixth embodiment of the invention, R.412181

[0044] - 7 -

[0045] Figure 9 is a schematic illustration of a sound transducer according to a seventh embodiment of the invention, and

[0046] Figure 10 is a schematic illustration of a sound transducer according to an eighth embodiment of the invention.

[0047] Embodiments of the invention

[0048] Preferably, all identical components, elements and / or units in all figures are provided with the same reference numerals.

[0049] Figure 1 schematically shows a vehicle 10 equipped with a sound transducer 1, which is configured as an ultrasonic transducer. The sound transducer 1 can be controlled by a control unit 9, and is used as an ultrasonic parking sensor. The sound transducer 1 serves to emit sound into the area 11 surrounding the vehicle 10 and / or to detect the sound reflected by objects in the area 11 surrounding the vehicle 10. The control unit 9 is configured to detect the objects in the area 11 surrounding the vehicle 10 using the sound transducer 1.

[0050] Figure 2 schematically shows a perspective view of a sound transducer 1 according to a first embodiment of the invention, which can be used in the vehicle 10 according to Figure 1. Figure 3 shows the sound transducer 1 according to the first embodiment of the invention in a sectional view. The sound transducer 1 is, in particular, an ultrasonic transducer and is especially preferably usable as an ultrasonic parking sensor in the vehicle 10 according to Figure 1.

[0051] The sound transducer 1 has a diaphragm pot 2 with a side wall 3 and an end wall 4. The diaphragm pot 2 has a circular cross-section, so that the diaphragm has the shape of a circular surface and the side wall 3 is hollow cylindrical. At least two excitation elements 5 are mounted inside the diaphragm pot 2. The excitation elements 5 serve to set the diaphragm into vibration. For example, the excitation elements 5 are piezoelectric elements. R.412181

[0052] - 8 -

[0053] The various excitation elements 5 are intended to operate independently of each other and without, or at least with minimal, mutual interference. Therefore, a separation of the membrane 4 between the two excitation elements 5 is provided. For this purpose, a bridge 6 is applied to the membrane 4 between the excitation elements 5. The bridge is either connected to or integrally formed with the membrane 4 and extends between two regions of the side wall 3. In particular, the bridge is either integrally formed with or connected to the side wall 3. This mechanically separates the excitation elements 5. The vibration of the membrane 4, excited by one of the excitation elements 5, has no or virtually no effect on the region of the membrane 4 where the other excitation element 5 is located. The excitation elements 5 can be controlled independently of each other.

[0054] The control unit 9 is designed to control the excitation elements 5 of the transducer 1 separately. In particular, this achieves the formation of an ultrasonic phased array.

[0055] The bridge 6 has a recess 7 on one side facing away from the membrane 4. This ensures that the bridge 3 is rigid and does not vibrate with the membrane itself when excited by the excitation elements 5. Nevertheless, it is ensured that the bridge reliably separates the excitation elements 5 from one another. Thus, crosstalk between the excitation elements 5 is avoided or at least reduced.

[0056] The bridge 6 has its greatest extent h away from the diaphragm 4 directly at the side wall 3. This extent h decreases with increasing distance from the side wall 3. In particular, the extent in the middle of the bridge 6 is segmentally constant between the respective areas of the side wall 3. The bridge 6 also has a constant wall thickness d. This results in the separation of the diaphragm 4 into different vibration ranges, but the bridge 6 dampens the vibration of the diaphragm 4 only to the smallest possible extent necessary for this separation. The remaining areas of the diaphragm 4 can continue to vibrate. Thus, the overall damping of the diaphragm by the bridge 6 is minimized. R.412181

[0057] - 9 -

[0058] The sound transducer 1 can be designed in different variants, whereby a bridge 6 is always provided for the mechanical separation of the excitation elements 5 and thus a division of the membrane 4 into several independent vibration ranges. Thus, in all variants, it is common that the excitation elements 5 can be controlled differently in order to achieve the function of an ultrasonic phased array.

[0059] Figure 4 schematically shows a second alternative of the transducer 1. In this case, several struts 6, namely three struts 6, are provided. The struts 6 extend from a center point of the diaphragm 4 in a star-shaped pattern to a respective region of the side wall 3. In this variant, three vibration areas are therefore formed on the diaphragm 4, with three excitation elements 5 being present. This allows the three excitation elements 5 to be controlled independently of each other to form a larger ultrasonic phased array than previously described.

[0060] Figure 5 schematically shows a third alternative of the sound transducer 1. The basic structure is the same, except that here there are four struts 6 which extend in a cross shape from the center of the diaphragm 4 to a respective area of ​​the side wall 3. Therefore, four independent vibration areas of the diaphragm 4 are formed, with an excitation element 5 applied to the diaphragm in each vibration area.

[0061] Figure 6 schematically shows a fourth alternative of the sound transducer 1. Here, the diaphragm 4 is provided with several thickenings 8 or steps. The thickenings extend into the diaphragm pot 2. Furthermore, the thickenings 8 are not connected to the side wall 3. Therefore, the thickenings act as a seismic mass, which alters the resonant frequency of the diaphragm's vibration range. If the diaphragm is divided by the bridge 6, the vibrational area available in each section decreases. This leads to increased stiffness and a higher natural frequency. The thickenings 8 lower the natural frequency again. The excitation elements 5 are mounted on the thickenings 8. Thus, the vibration characteristics of the diaphragm 4 are optimized even with the bridge 6 present. R.412181

[0062] - 10 -

[0063] In an alternative arrangement not shown, a stack of several excitation elements 5 can also be applied one above the other to the membrane 4. It is sufficient if only one of the excitation elements 5 in each stack is controllable. The other excitation elements 5, analogous to the thickenings, serve only to increase the mass and thus to adjust the resonant frequency of the membrane.

[0064] Figure 7 shows a fifth alternative of the sound transducer 1. Here, the diaphragm pot 1 no longer has a round cross-section, but an oval one. Furthermore, several struts 6 are again provided. In contrast to the previous cross-shaped or star-shaped arrangement of the struts, in this variant the struts 6 extend parallel to each other separately between two areas of the side wall 3. Again, several vibration zones of the diaphragm 4 are separated from each other, with each vibration zone having an excitation element 5 applied to the diaphragm 4.

[0065] Figure 8 shows a sixth alternative of the sound transducer 1. Here, the diaphragm pot 1 again has an oval cross-section, and several struts 6 are again provided. Analogous to the second variant, the struts 6 extend from a center of the diaphragm 4 in a cross shape to a respective area of ​​the side wall 3.

[0066] Figure 9 shows an eighth alternative of the sound transducer 1. Again, the diaphragm pot 1 has an oval cross-section. Again, several struts 2 are present. The struts are arranged in a V-shape between different areas of the side wall. Thus, the two struts 6 extend from a common area of ​​the side wall 3 to separate areas of the side wall 3, forming a V-shape for the struts 6. Again, different vibration zones of the diaphragm 4 are formed, which can be set into vibration separately by their own excitation elements 5.

[0067] Figure 10 schematically shows an eighth alternative of the sound transducer 1. In this case, an oval cross-section of the diaphragm pot 2 is provided, with a single strut 6. The strut 6 is designed as a full-surface covering of the diaphragm 4 and has one R.412181 for each excitation element 5.

[0068] - 11 -

[0069] Recess. The excitation elements 5 can be applied to the membrane 4 through the recesses.

[0070] The shape of the vibration elements 5 is not relevant for the described alternatives. The vibration elements 5 can, for example, be round, oval, or angular, in particular rectangular, or sector-shaped, or otherwise configured.

Claims

R.412181 - 12 - Claims 1. Sound transducer (1), in particular ultrasonic transducer, comprising a membrane pot (2) with a side wall (3) and an end-face membrane (4), • wherein at least two excitation elements (5), in particular piezoelectric elements, are applied to the membrane (4) within the membrane pot (2), • wherein at least one bridge (6) is applied between the excitation elements (5) on the membrane (4), • wherein the bridge (6) is connected to the membrane (4) or formed in one piece, • wherein the bridge (6) extends between two areas of the side wall (3) and mechanically separates the excitation elements (5) from each other, and • wherein the excitation elements (5) can be controlled separately from each other.

2. Sound transducer (1) according to claim 1, characterized in that the at least one bridge (6) has a recess (7) on a side facing away from the diaphragm (4).

3. Sound transducer (1) according to claim 2, characterized in that the at least one bridge (6) has a maximum extent (h) away from the diaphragm (4) directly at the side wall (3), wherein the extent (h) is smaller with increasing distance to the side wall (3).

4. Sound transducer (1) according to one of the preceding claims, characterized in that the diaphragm (4) has thickenings (8) which extend in particular into the diaphragm pot (2), wherein the thickenings (8) are not connected to the side wall (3) and wherein the excitation elements (5) are attached to the thickenings (8). R.412181 - 13 - 5. Sound transducer (1) according to one of the preceding claims, characterized in that several excitation elements (5) are stacked on top of each other on the membrane (4), wherein at least one of the excitation elements (5) of each stack is controllable.

6. Sound transducer (1) according to one of the preceding claims, characterized in that several struts (6) are provided, • wherein the webs (6) extend from a center of the membrane (4) in a cross-shaped or star-shaped pattern to a respective area of ​​the side wall (3) and / or • wherein the webs (6) extend separately between two areas of the side wall (3), in particular parallel to each other, and / or • wherein the webs (6) run in a V-shape between different areas of the side wall (3).

7. Sound transducer (1) according to one of the preceding claims, characterized in that the at least one bridge (6) has a constant wall thickness (d).

8. Sound transducer (1) according to one of the preceding claims, characterized in that the bridge (6) is designed as a full-surface cover of the membrane (4), wherein the cover has recesses for attaching the excitation elements (5) to the membrane (4).

9. Vehicle (10) comprising at least one sound transducer (1) according to one of the preceding claims, wherein the vehicle (10) is configured by emitting sound and detecting the sound reflected by objects in the environment (11) of the vehicle, wherein the emission and / or detection can be carried out with the sound transducer (1) to detect the objects in the environment (11) of the vehicle (10).

10. Vehicle (10) according to claim 9, characterized by a control unit (12), wherein the control unit (12) is configured to control the excitation elements (5) of the sound transducer (1) separately, in particular to form an ultrasonic phased array.

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