MEMS transducer

Abstract

A MEMS transducer for interacting with a fluid, comprising: - a substrate, - a vibratory lamella, wherein the lamella has at least one lamella section with two sections, wherein each section has a first end and an opposite, second end when viewed in a y direction, wherein the two sections are arranged opposite one another when viewed in a y-x plane, wherein the two sections are connected to one another by the second end regions, wherein first end regions of the two sections are spaced apart from one another when viewed in the x direction, wherein a pressure chamber is formed between the two sections, wherein a rear chamber is formed between the lamella and the substrate, wherein the pressure chamber is arranged on a first side of the lamella and the rear chamber is arranged on a second side of the lamella, wherein the lamella is connected to the substrate by the first ends, wherein at least one section has an actuator layer, wherein the actuator layer is designed to excite the at least one section to vibrate by electrical actuation in order to produce a change in volume in the pressure chamber and / or in the rear chamber, wherein the pressure chamber or the rear chamber has a controllable closing element which can connect the pressure chamber or the rear chamber to the surroundings of the MEMS transducer, wherein the closing element comprises the actuator layer or a second actuator layer, wherein an actuator opening is provided in the actuator layer, wherein the actuator layer or the second actuator layer is designed to change an opening cross section of the actuator opening by electrical actuation, in particular to open or close the actuator opening.

Description

[0001] Description

[0002] title

[0003] M EMS converter

[0004] The invention relates to an EMS transducer for interaction with a fluid according to claim 1.

[0005] State of the art

[0006] From WO 2021 / 144400 A1, a MEMS transducer for interacting with a volume flow of a fluid is known, comprising a support and a vibrating diaphragm for generating and receiving pressure waves of the fluid in a vertical direction, wherein the vibrating diaphragm is held by a support. The vibrating diaphragm has two or more vertical sections which are substantially parallel to the vertical direction and comprise at least one layer of an actuator material. The vibrating diaphragm is contacted at its end with at least one electrode, such that by actuating the at least one electrode, the two or more vertical sections can be excited to horizontal vibrations, or such that when the two or more vertical sections are excited to horizontal vibrations, an electrical signal can be generated at the at least one electrode.

[0007] Disclosure of the invention

[0008] The object of the invention is to provide an improved MEMS converter.

[0009] The object of the invention is achieved by the MEMS transducer according to claim 1. An MEMS transducer for interaction with a fluid is proposed, comprising:

[0010] - a carrier,

[0011] - a vibrating lamella, wherein the lamella has at least one lamella section with two sections, each section having a first end and a second end opposite it when viewed in a y-direction, wherein the two sections are arranged opposite each other when viewed in a yx-plane, wherein the two sections are connected to each other at their second end regions, wherein the first end regions of the two sections are spaced apart from each other when viewed in the x-direction, wherein a pressure chamber is formed between the two sections, wherein a back chamber is formed between the lamella and the support, wherein the pressure chamber is arranged on a first side of the lamella and the back chamber on a second side of the lamella, wherein the lamella is connected to the support at its first ends, wherein at least one section has an actuator layer, wherein the actuator layer is formedto excite at least one section to vibrations by electrical control in order to generate a volume change in the pressure chamber and / or in the back chamber, wherein the pressure chamber or the back chamber has a controllable closing element that can connect the pressure chamber or the back chamber to an environment of the MEMS transducer, wherein the closing element comprises the actuator layer or a second actuator layer, wherein an actuator opening is provided in the actuator layer or in the second actuator layer, wherein the actuator layer or the second actuator layer is configured to change an opening cross-section of the actuator opening by electrical control, in particular to open or close the actuator opening.

[0012] The lamella can be formed in the form of ribs and / or membranes, in particular in the form of a folded membrane.

[0013] The MEMS transducer can be used to generate ultrasound, particularly in the frequency range above 20 kHz, using the lamella. The closing element can then be used to generate an audio signal from the ultrasound in the range of 20 Hz to 20 kHz. This is achieved by controlling the lamella and the closing element with different signals to produce a combined audio signal. The proposed MEMS transducer features a small form factor and an extended frequency range for outputting audio signals.

[0014] In one embodiment, the actuator layer and / or the second actuator layer change their length and / or width perpendicular to the actuator opening when electrically actuated, thus altering the opening's cross-sectional area. This embodiment enables the simple implementation of a closing element that is simple in design and requires little installation space.

[0015] In one embodiment, the actuator layer and / or the second actuator layer at least partially define an actuator opening in the form of an opening channel, whereby when the actuator layer and / or the second actuator layer is activated, the cross-sectional area of ​​the opening channel of the actuator opening is changed. This embodiment allows for the realization of another reliable embodiment of a closing element.

[0016] In one embodiment, the actuator layer and / or the second actuator layer define two sides of the opening channel. When the actuator layer and / or the second actuator layer is activated, the opening cross-section of the opening channel is changed from both sides. This allows for faster closing or opening of the opening channel. Furthermore, the opening channel can have a greater width.

[0017] In one embodiment, the actuator layer and / or the second actuator layer have a bridge, wherein the bridge is at least partially arranged above or within the actuator opening. When the actuator layer and / or the second actuator layer is electrically actuated, the bridge changes its shape and bends transversely to a longitudinal extent, thus altering the opening cross-section of the actuator opening. This allows for a simple closing element with reliable operation.

[0018] In one embodiment, the closing element has a cover element and at least one web as part of the actuator layer and / or the second actuator layer, wherein the cover element is arranged in the area of ​​the actuator opening and is connected to the web, wherein the shape of the web is changed when the actuator layer and / or the second actuator layer is actuated and thus a position of the cover element is changed in such a way that an opening cross-section of the actuator opening is changed.

[0019] This allows larger actuator openings to be opened and closed more quickly and safely. Furthermore, with this design, sound is emitted laterally relative to the actuator opening.

[0020] In one embodiment, the cover element is designed in the form of a membrane, wherein the membrane in particular comprises or consists of a semiconductor material. A membrane is suitable for forming the cover element due to its low weight.

[0021] In one embodiment, at least a second web is provided as part of the actuator layer and / or the second actuator layer, wherein the second web is connected to the cover element, and wherein the web and the second web are preferably arranged on opposite sides of the cover element, the shape of the web and the second web being changed when the actuator layer and / or the second actuator layers are actuated, thus changing the height position of the cover element relative to the actuator opening and consequently altering the effective cross-sectional area of ​​the actuator opening. In this way, even larger cover elements can be moved quickly and reliably.

[0022] In one embodiment, the second end regions of the two sections of a lamella section are connected to each other via a third section, with the third section being arranged transversely to the orientation of the first and second sections. In this way, a relatively large pressure volume can be provided.

[0023] In one embodiment, the lamella has several lamella sections, wherein the lamella sections are connected to each other via the second ends of the two sections of the lamella section, with each lamella section forming a pressure chamber. In another embodiment, the pressure chambers open into a common outlet chamber, wherein the closing element is arranged at the outlet chamber, and wherein the closing element can connect the outlet chamber to an environment.

[0024] In one version, each pressure chamber leads into a separate one, with each exit chamber having a closing element.

[0025] In one embodiment, the pressure chamber is closed in the area of ​​the two second ends with a cover in the y-direction, wherein the pressure chamber is closed in the z-direction by two side walls, the closing element being arranged in one of the side walls and being able to connect the pressure chamber with the environment.

[0026] In one embodiment, the closing element is formed as part of the actuator layer, wherein the actuator layer of the closing element is designed to cause the closing element to vibrate at a first frequency, wherein the actuator layer is designed in the area of ​​the pressure chamber to vibrate at a second frequency, wherein the first frequency is higher than the second frequency, wherein in particular the first frequency is greater than 20 kHz and the second frequency is between 20 Hz and 20 kHz.

[0027] In this way, both the pressure chambers and the closing element can be implemented with a single actuator layer. This allows for a simple and compact design of the MEMS transducer.

[0028] In one embodiment, the actuator layer is configured in the area of ​​the pressure chamber to oscillate at a first frequency, wherein the closing element is configured as part of the second actuator layer, wherein the second actuator layer of the closing element is configured to cause the closing element to oscillate at a second frequency, wherein the first frequency is higher than the second frequency, wherein in particular the first frequency is greater than 20 kHz and the second frequency is between 20 Hz and 20 kHz.

[0029] The invention is explained in more detail with reference to the figures; Figure 1 shows a schematic, perspective partial sectional view of a MEMS converter.

[0030] Figure 2 is a schematic top view of a top surface of the

[0031] MEMS converter of figure 1,

[0032] Figure 3 is a schematic representation of a top view of a

[0033] Underside of the MEMS transducer of Figure 1 ,

[0034] Figure 4 shows a first embodiment of a MEMS transducer with a closing element in the form of an active layer,

[0035] Figure 5 is a schematic top view of the arrangement shown in Figure 4.

[0036] Figure 6 schematic representations of another embodiment of an M EMS converter with a locking element in the form of a locking channel,

[0037] Figures 7 to 9 show further embodiments of MEMS transducers with

[0038] Locking elements in the form of bars or plates,

[0039] Figures 10 to 12 show further embodiments of a MEMS transducer with a closing element in the form of a cover element.

[0040] Figures 13 and 14 show schematic representations of another embodiment of a MEMS transducer with laterally arranged locking elements.

[0041] Figure 15 shows a schematic cross-sectional view of another

[0042] Design of a MEMS transducer.

[0043] In a preferred embodiment, the at least one layer of the actuator layer and / or the second actuator layer is formed from an actuator material as a vibrating diaphragm with a continuous layer. "Continuous" preferably means that there are no interruptions in the cross-sectional profile. Accordingly, in the aforementioned embodiment, it is preferred that a continuous layer of actuator material is present in both the vertical and horizontal sections. A continuous layer is particularly easy to manufacture and ensures synchronous actuation during the operation of a MEMS loudspeaker. "Vertical" is defined as an orientation essentially along the Y-axis. "Horizontal" is defined as an orientation essentially along the X-axis. The performance of the MEMS transducer, in particular a MEMS loudspeaker or MEMS microphone, can be significantly determined by the number and / or dimensions of the vertical sections.

[0044] In preferred embodiments, the vibrating membrane comprises more than 10 or more than 100 or more vertical sections. Preferably, the vertical sections are planar, meaning in particular that their extent in each of the two dimensions (height, width) of their area is greater than in a dimension perpendicular to it (the thickness). For example, size ratios of at least 2:1, preferably at least 5:1, 10:1 or more, may be preferred. In accordance with the invention, the height of the vertical sections preferably corresponds to the dimension along the direction of sound emission or sound detection, while the thickness of the vertical sections preferably corresponds to the sum of the layer thicknesses of the one or more layers that form the vertical sections. The length of the vertical sections preferably corresponds to a dimension orthogonal to the height or thickness.In the cross-sectional views of the figures shown below, height and thickness are represented schematically (not necessarily to scale), while the length dimension corresponds to a (non-visible) drawing depth of the figures. In a preferred embodiment, the height of the vertical sections is between 1 mm and 1000 mm, preferably between 10 mm and 500 mm.

[0045] In a preferred embodiment, the thickness of the vertical sections is between 100 nm and 10 mm, preferably between 500 nm and 5 mm. With the aforementioned preferred dimensions of the vibrating diaphragm or the vertical sections, a particularly compact MEMS transducer, especially a MEMS loudspeaker or MEMS microphone, can be provided, which simultaneously combines high performance with excellent sound image or audio quality. In a preferred embodiment of the invention, the vibrating diaphragm is formed by a meandering structure with alternating vertical and horizontal sections, wherein support structures are attached to at least two of the horizontal sections, which are connected directly or indirectly to the substrate. The support structures can, for example, be provided by substrate material of the substrate, i.e.,The support structures can be formed directly from the substrate of a bottom wafer. Alternatively, they can be connected to the horizontal sections as separate ridges or raised sections of a top wafer. The support structures can preferably be attached to the vibrating membrane on one and / or both sides, i.e., preferably to the upper and / or lower horizontal sections. Particularly when suspending a larger vibrating membrane between the side walls of a support, the use of support structures advantageously allows for stabilization without negatively affecting sound generation or reception. Since the horizontal sections are at least essentially mechanically neutral in a meandering shape, locking them in place with the support structure advantageously avoids undesirable stresses between the membrane and the support structure or support.The vibrating membrane can be constructed with various layers to ensure the described actuation and excitation of horizontal vibrations or their detection. Electrical contact with one or more actuator layers and / or one or more layers of a mechanical support material, and thus the application or detection of an electrical voltage, can be achieved directly via the end electrodes or supported by a layer of conductive material. In a preferred embodiment, the vibrating membrane therefore comprises at least one layer of conductive material. In preferred embodiments, the conductive material is selected from the group consisting of platinum, tungsten, (doped) tin oxide, monocrystalline silicon, polysilicon, molybdenum, titanium, tantalum, titanium-tungsten alloy, metal silicide, aluminum, graphite, and copper.In a preferred embodiment, the vibrating membrane comprises three layers, wherein an upper layer is formed of a conductive material and is connected to an upper electrode, a middle layer is formed of the actuator material, and a lower layer is formed of a conductive material. Preferably, the conductive material of the upper and / or lower layer can be a mechanical support material, giving this layer a dual function. Firstly, it ensures contact between the actuator layer and an electrical potential that can be applied to the end electrodes. Secondly, it acts as a mechanical support layer, as described, to generate horizontal bulges or vibrations when the actuator layer is appropriately actuated.

[0046] In a preferred embodiment of the invention, the MEMS transducer, preferably a MEMS loudspeaker, comprises a control unit, i.e., a signal controller, configured to drive the at least one electrode such that the two or more vertical sections are excited to horizontal oscillations. Preferably, the control unit is configured to drive the electrodes in a way that ensures a frequency of the horizontal oscillations greater than 20 kHz.

[0047] In one embodiment, the signal control is designed to control the closing elements in such a way that the closing elements open and close the actuator openings at a frequency in the range of 10 Hz to 20 kHz and thus emit an acoustic signal.

[0048] For this purpose, the signal control can preferably include a data processing unit. The data processing unit preferably comprises a unit that is suitable and configured for receiving, transmitting, storing, and / or processing data, preferably with regard to controlling the electrodes or receiving an electrical signal provided at the electrodes. The data processing unit preferably includes an integrated circuit, for example, an application-specific integrated circuit, a processor, a processor chip, a microprocessor, or a microcontroller for processing data, and optionally a data storage device, a random access memory (RAM), a read-only memory (ROM), or a flash memory for storing the data. In preferred embodiments, the signal control is integrated on a printed circuit board (PCB) along with other components of the MEMS transducer (carrier, vibrating membrane).Preferably, the MEMS transducer is seamlessly integrated with the electronics required for control or detection. Various embodiments of MEMS transducers are described below, some of which differ in their closing elements. However, these closing elements can also be used in other embodiments. Thus, the different closing element shapes can be combined with the various lamella designs and / or the different output chamber shapes and lamella arrangements in the MEMS transducers.

[0049] Figure 1 shows, in a schematic perspective partial sectional view, essential parts of a MEMS transducer 1 with a carrier 2 and an oscillating lamella 3. The carrier 2 has four circumferential side elements 4, 5, 6, 7, which define a space 9 and are arranged on a base plate 8. Depending on the chosen embodiment, the side elements 4, 5, 6, 7 and the base plate 8 can be formed in one piece and from a single material. Alternatively, the base plate 8 can also be made of a different material, and the side elements 4, 5, 6, 7, which form a circumferential frame, can be attached to the top surface of the base plate 8. The side elements 4, 5, 6, 7 are, for example, made of a semiconductor material, in particular silicon. Similarly, the base plate 8 can also be made of a semiconductor material.Depending on the embodiment, the base plate 8 can also be made of a different material, in particular a printed circuit board material.

[0050] The lamella 3 is arranged in space 9, which is bounded by the side elements 4, 5, 6, 7. The lamella 3 has several lamella sections 10, 11, 12. In the illustrated embodiment, three lamella sections 10, 11, 12 are provided. Depending on the chosen embodiment, more or fewer lamella sections may be provided. The lamella sections 10, 11, 12 are essentially identical and each has a first and a second section 13, 14. The first and second sections 13, 14 are each arranged essentially parallel to each other and aligned along the y-direction. In addition, in the illustrated embodiment, the first and second sections 13, 14 are connected to each other via a third section 15. In the illustrated embodiment, the third section 15 is arranged essentially transversely, in particular perpendicularly, to the orientation of the first and second sections 13, 14.The first, second, and third sections 13, 14, 15 are formed from the same material. Sections 13, 14, 15 define a pressure chamber 16. The pressure chamber 16 can also be further defined in the Z-direction by a fourth and a fifth section 17, 18 of the first lamella section 10. First end regions of the first and second sections define a pressure chamber opening 19 of the pressure chamber 16 in the zx-plane. Second end regions of the first and second sections are connected to each other via the third section 15 in the illustrated embodiment. Depending on the chosen embodiment, the second end regions of the first and second sections 13, 14 can also be directly connected to each other. Furthermore, depending on the chosen embodiment, the fourth and fifth sections 17, 18 can be omitted.Furthermore, instead of the fourth and fifth sections 17, 18, the corresponding side elements 5, 7 of the carrier 2 can define the pressure chamber 16. The first end regions of the first and second sections are guided laterally outwards via connecting surfaces 58 and attached to the upper surfaces of the side elements 4, 5, 6, 7 or connected to a further lamella section 11, 12.

[0051] The lamella 13 has an active layer 20, for example in the form of aluminum nitride, and preferably a passive layer 21 as a support layer. The active layer 20 is connected to electrical conductors (not shown) via which the active layer 20 can be excited to change its shape. For example, the active layer 20 and the support layer 21 are configured to cause the first and second sections 13, 14 to vibrate in phase or out of phase along the x-axis, as schematically indicated by arrows. The vibrations of the sections 13, 14 change the volume of the pressure chamber 16. This allows for compression of the fluid in the pressure chamber and, for example, the generation of an acoustic signal.

[0052] Preferably, the first and second sections 13, 14 of a lamella section oscillate synchronously in opposite directions to achieve an optimized volume reduction or volume increase of the pressure chamber 16. For example, the lamella, and in particular each lamella section, is designed to exhibit resonance frequencies in an ultrasonic range, especially in the range > 20 kHz. Thus, the pressure chambers 16 can be used as pump elements in the ultrasonic range.

[0053] Figure 2 shows a schematic top view of the arrangement of Figure 1 with the representation of three pressure chambers 16.

[0054] Figure 3 shows a schematic top view of the underside of Figure 1, excluding the base plate 8. This view shows that the first and second sections are connected to the second and fourth side elements 5, 7 at their lateral end regions. A web-like cavity 22, 23 is formed between each pair of lamella sections 10, 11, 12. Additionally, a web-like space 24, 25 is formed between each lamella section and a side element 4, 6, viewed in the x-direction.

[0055] Depending on the chosen embodiment, the fourth section 17 and the fifth section 18 can also be spaced apart in the z-direction by a gap from the corresponding second or fourth side element 5, 7.

[0056] Figure 4 shows a schematic cross-sectional view of a MEMS transducer, which is essentially designed according to the embodiment of Figure 1, but with at least one controllable closing element 26, 27, 28 provided above the pressure chamber openings 19 of the pressure chambers 16.

[0057] The closing element 26, 27, 28 has a second active layer, i.e. a second actuator layer 29, wherein the second actuator layer is designed to change an opening cross-section of an actuator opening 33 by electrical control, in particular to open or close the opening cross-section of the pressure chamber opening 19.

[0058] The closing elements 26, 27, 28 each have a second actuator layer 29, which may also be arranged on a second passive layer 30. In the illustrated embodiment, the closing elements 26, 27, 28 are designed as a single-piece second actuator layer 29 and a single-piece second passive layer 30, i.e., a second support layer. The second actuator layer 29 has an actuator opening 33 adjacent to the pressure chamber opening 19. Depending on the electrical control of the second actuator layer 29, an opening cross-section of the actuator opening 33 expands or narrows in the zx plane, as schematically represented by dashed lines and arrows. The second actuator layer 29 is supplied with current via electrical lines (not shown) at a control frequency preferably in the audio band range of 20 Hz to 20 kHz.In addition, the second actuator layer 29 is designed to achieve a modular action of the opening cross-section of the pressure chamber opening 19 in the audio area.

[0059] Depending on the chosen embodiment, the closing elements 26, 27, 28 can be designed in such a way that the second actuato layer 29 can be lengthened or shortened from different directions in the x-direction and / or z-direction to reduce or increase the opening cross-section of the actuator opening 33.

[0060] The second passive layer 30 can, for example, consist of silicon or polysilicon. Depending on the chosen embodiment, typical opening cross-sections of the actuator opening 33 can range from 1 to 5 pm in the open state and from 3 to 5 pm in the closed state. In particular, for the modulation of a sound signal, it is not necessary for the opening cross-section of the actuator opening 33 to be completely closed or completely open.

[0061] Figure 5 shows a schematic top view of the arrangement in Figure 4, where the actuator openings 33 are schematically represented as rectangles. Two closing elements with two actuator openings 33 are arranged for each pressure chamber 16. The elongation or contraction of the second actuator layer 29 in the zx-plane is schematically represented by arrows. The second actuator layer 29 is designed to extend towards or away from a central region of the actuator opening 33 with two opposing edge regions 31, 32. This movement is schematically represented by dashed lines, which are intended to depict the extended first and second edge regions 31, 32 of the second activation layer 29.Figure 6A shows a schematic cross-section through another embodiment of a MEMS transducer 1, which is essentially designed according to the embodiment of Figures 1 to 3, except that further closing elements 34, 35, 36 are designed in the form of further oscillating lamellae, wherein the further lamella delimits an opening channel 37, the opening channel 37 being arranged above a pressure chamber opening 19. The opening channel 37 connects the pressure chamber opening 19 to the environment. The further lamella has at least one further section 38, wherein the further section 38 represents at least one side of the opening channel 37. The further section 38 has at least one second actuator layer 29, wherein, upon activation of the second actuator layer 29, the further section 38 changes its shape and changes an opening cross-section of the opening channel 37.In the illustrated embodiment, the opening channel 37 is additionally bounded by a second further section, which is arranged opposite the further section 38. Thus, the first further section 38 and the second further section 39 bound the opening channel 37. The second further section also has a second further actuator layer, wherein, when the second actuator layer is activated, the second further section changes its shape and changes the opening cross-section of the opening channel. The first further closing element 34 is designed in the form of a further actuator layer 40, which comprises a passive support layer and an active actuator layer 41.

[0062] 42. The further actuator layer 40 is connected via an insulating layer.

[0063] 43 is arranged on a top side of the lamella 3. The insulating layer 43 can, for example, consist of silicon nitride or another electrically insulating material.

[0064] Figure 6B shows a schematic top view of the arrangement shown in Figure 6A, with the pressure chamber openings 19 represented by dashed lines. Additionally, the bulges of the further sections 38 and 39, which can narrow the opening channel 37, are shown schematically as dashed lines.

[0065] Depending on the chosen embodiment, only one of the two further sections 38, 39 may be configured as an additional actuator layer 40. Figure 7A shows a schematic cross-sectional view of a MEMS transducer 1, which is essentially configured according to Figures 1 to 3, except that the pressure chambers 19 each open into a separate outlet chamber 44, 45, 46. The outlet chambers 44, 45, 46 are separated by intermediate elements 47, 48. The outlet chambers 44, 45, 46 are each covered with an additional actuator layer 40. Furthermore, each outlet chamber 44, 45, 46 is assigned an additional closing element 34, 35, 36. The additional closing elements 34, 35, 36 can be identical.

[0066] Figure 7B shows a schematic top view of the first additional closing element 34. In the illustrated embodiment, the first additional closing element 34 has a first web 49 and a second web 50. The webs 49, 50 project laterally from opposite sides into an area above the pressure chamber opening 19. The first and second webs 49, 50 each have a further support layer 41 and a further actuator layer 42. The first and second webs 49, 50 define an actuator opening 33. The first and second webs 49, 50 are designed such that, by applying a corresponding current to the further actuator layer 42, the webs move with a free end upwards along the y-axis or downwards along the y-axis and open the actuator opening 33.For example, the control can be effected such that the first web 49 moves upwards and the second web 50 moves downwards, as schematically illustrated by the dashed lines in Figure 7a. This results in a change to the opening cross-section of the actuator opening 33 of the further closing element 34, 35, 36.

[0067] Figure 8 shows a schematic cross-sectional view of an arrangement that is essentially based on Figure 7A, except that in this embodiment the additional locking elements 34, 35, 36 have only one web 49 which can change an actuator opening 33 of the additional locking element 34, 35, 36 by means of a corresponding control signal. For this purpose, an additional actuator layer 40 is provided, analogous to the embodiment of Figure 7A.

[0068] Figure 9 shows a schematic cross-sectional view of another embodiment of a MEMS transducer, which is essentially the same as the embodiment of Figure 8, except that the pressure chambers 16 merge into a common output chamber 44. In addition, a web 49 is provided in the further actuator layer 40 to change the opening cross-section of an actuator opening 33.

[0069] Figure 10 shows a further embodiment of a MEMS transducer 1, which is essentially designed according to the embodiment of Figure 7A, except that instead of movable webs 49, 50, the further closing elements 34, 35, 36 each have a cover element 51, which is connected to the further actuator layer 40 via movable further webs 52, 53, 54, 55 and can change the opening cross-section of an actuator opening 33. The further webs 52, 53, 54, 55 can, as schematically shown in Figure 11, each be arranged with a first end at four corner regions of the cover element 51 and connected with their second end to the further actuator layer 40, in particular being formed in one piece and of a single material. Depending on the chosen embodiment, an additional web 52 may also be sufficient to change the position of the cover element in such a way that the opening cross-section of the actuator opening 33 is changed.In the illustrated embodiment, the further webs 52, 53, 54, 55 can be changed by a corresponding electrical current in such a way that the cover is either lifted upwards in the y-axis or lowered downwards, so that in both cases a larger opening cross-section of the actuator opening 33 can be achieved.

[0070] Figure 10 shows the cover elements 51 of the further closing elements 34, 35, 36 in the closed position. The opening of the exit opening is achieved by moving the cover elements 51 either upwards or downwards, as schematically indicated by dashed lines. The cover element 51 can be in the form of a membrane, in particular made of a semiconductor material.

[0071] Figure 11 shows a schematic top view of a cover element 51 with the four further webs 52, 53, 54, 55.

[0072] Figure 12 shows a schematic representation of an arrangement according to Figure

[0073] 9, however, in this embodiment the further closing element 34 is designed in the form of a cover element 51, which is movably formed on the further actuator layer 40 via at least one, in particular up to four further webs 52, 53, 54, 55 analogous to the representation of Figure 11.

[0074] By applying a corresponding current to at least one further web 52, the cover element 51 can be lifted off along the y-axis from the plane of the further actuator layer 40 and thus increase the opening cross-section of the actuator opening 33.

[0075] In the embodiments of Figures 10 to 12, sound can be emitted in a lateral direction in the zx plane.

[0076] Figure 13 shows another embodiment of a MEMS transducer, which is essentially the embodiment of Figure 1, except that in this embodiment the pressure chambers 16 of the lamella 3 are covered by a lid 56 and closed in the y-direction. Furthermore, in this illustrated embodiment, the lamella sections of the lamella 3 rest on the base plate 8 with the third section 15. Thus, the lamella 3 cannot deflect either upwards or downwards along the y-direction.

[0077] Figure 14 shows a schematic cross-section in the xz plane of the arrangement of the lamella sections 10, 11, 12 of the lamella 3 and further closing elements 34, 35, 36, which are arranged in the z-direction at one end of the pressure chambers 16. The further closing elements 34, 35, 36 can also have at least one, in particular two, movable further sections 38, 39 of a further actuator layer 40 according to Figure 6A.

[0078] In this embodiment, the first, second and third further closing elements 34, 35, 36 are each assigned to an exit opening 57, wherein the exit openings 57 are arranged in the fourth side element 7 of the carrier 2.

[0079] Depending on the chosen design, the additional closing elements 34, 35, 36 can also have other shapes, for example, as described in Figures 4 to 12. Figure 15 shows a schematic cross-sectional view of another embodiment of a MEMS transducer 1, which has a vibrating folded lamella 3, as explained in Figure 1. The lamella sections are connected to each other in the first end regions of sections 13, 14 via connecting sections 62. In addition, the first end regions of sections 13, 14, which are arranged adjacent to side walls 4, 6, are also connected to the side walls via connecting sections 62. In this embodiment, at least one closing element 26, 27, 28, 60 with an actuator opening 33 is incorporated in the connecting sections 62 of the lamella 3, i.e. in the actuator layer with the active layer 20 and, if present, also in the support layer 21.The MEMS transducer 1 preferably has a second cover 58 with emission openings 59. The second cover 58 forms an interior space with the base plate 8 in which the carrier 2 with the lamella 3 is arranged. In addition, the space 9, which represents a rear space, is preferably closed by the base plate 8.

[0080] Furthermore, electrical lines are provided that supply the closing elements 26, 27, 28, 60 with electrical first signals and the sections 13, 14 of the lamella sections 10, 11, 12 with electrical second signals, so that the closing elements open and close at a frequency between 20 Hz and 2 kHz, and wherein the sections that delimit the pressure chambers 16 oscillate at a frequency greater than 20 kHz. The first and second signals can be provided by a signal controller 61. Depending on the selected design, the first and second electrical signals are identical, wherein the electrical signals have a base signal with a base frequency in the ultrasonic range above 20 kHz, and wherein the base signal is modulated with a second frequency in the audio range between 20 Hz and 20 kHz.

[0081] For example, the signal control 61 can output only one electrical signal to the locking elements and sections 13, 14 of the lamella sections 10, 11, 12, wherein the signal has a base signal with a base frequency in the ultrasonic range above 20 kHz, and wherein the base signal is modulated with a second frequency in the audio range between 20 Hz and 20 kHz. The locking elements 26, 27, 28, 60 can have natural frequencies in the audio range between 20 Hz and 20 kHz. Sections 13, 14 of the lamella 3 can have natural frequencies in the range of the base signal frequency. Depending on the selected design, several locking elements with actuator openings can be provided in a connecting section 62. In addition, a radiation opening 59 can be provided in the second cover 58 for each actuator opening. The radiation openings 59 can, for example, be arranged in the Y-direction above the actuator openings of the locking elements.

Claims

Claims 1. MEMS transducer (1) for interaction with a fluid comprising: - a carrier (2), - a vibrating lamella (3), wherein the lamella (3) has at least one lamella section (10, 11, 12) with two sections (13, 14), wherein each section (13, 14) has a first end and a second end opposite it when viewed in a y-direction, wherein the two sections (13, 14) are arranged opposite each other when viewed in a yx-plane, wherein the two sections are connected to each other at their second end regions, wherein the first end regions of the two sections (13, 14) are spaced apart from each other when viewed in the x-direction, wherein a pressure chamber (16) is formed between the two sections (13, 14), wherein a back chamber (9) is formed between the lamella (3) and the support (8), wherein the pressure chamber (16) is arranged on a first side of the lamella (3) and the back chamber (9) is arranged on a second side of the lamella (3), wherein the The lamella (3) is connected to the support (2) at its first ends, with at least one section (13,14) has an actuator layer (20), wherein the actuator layer (20) is configured to excite the at least one section (13, 14) to vibrate by electrical control in order to generate a volume change in the pressure chamber (16) and / or in the back chamber (9), wherein the pressure chamber (16) or the back chamber (9) has a controllable closing element (26, 27, 28) that can connect the pressure chamber (16) or the back chamber (9) to an environment of the MEMS transducer (1), wherein the closing element (26, 27, 28) comprises the actuator layer (20) or a second actuator layer (40), wherein an actuator opening (33) is provided in the actuator layer (20) or in the second actuator layer (40), wherein the actuator layer (20) or the second actuator layer (40) is configured to excite a volume change in the pressure chamber (16) and / or in the back chamber (9) by electrical control to change the opening cross-section of the actuator opening (33), in particular to open or close the actuator opening (33).

2. MEMS converter according to claim 1, wherein the actuator layer (20) and / or the second actuator layer (40) change a length and / or width transverse to the actuator opening (33) upon electrical control and thus change the opening cross-section of the actuator opening (33).

3. MEMS converter according to claim 1, wherein the actuator layer (20) and / or the second actuator layer (40) at least partially define an actuator opening (33) in the form of an opening channel (37), wherein when the actuator layer (20) and / or the second actuator layer (40) is actuated, an opening cross-section of the opening channel (37) of the actuator opening (33) is changed.

4. MEMS transducer according to claim 3, wherein the actuator layer (20) and / or the second actuator layer (40) define two sides of an opening channel (37), wherein when the actuator layer (20) and / or the second actuator layer (40) is actuated, the opening cross-section of the opening channel (37) of the actuator opening (33) is changed from two sides.

5. MEMS transducer according to claim 1, wherein the actuator layer (20) and / or the second actuator layer (40) has a bridge (49, 50), wherein the bridge (49, 50) is arranged at least partially above or in the actuator opening (33), wherein the bridge (49, 50) changes its shape when the actuator layer (40) and / or the second actuator layer (40) is electrically actuated and bends transversely to a longitudinal extent, thus changing the opening cross-section of the actuator opening (33).

6. MEMS transducer according to claim 1, wherein the closing element (34, 35, 36) has a cover element (51) and at least one web (49, 50) as part of the actuator layer (20) and / or the second actuator layer (40), wherein the cover element (51) is arranged in the area of ​​the actuator opening (33) and is connected to the web (49, 50), wherein the shape of the web (49, 50) is changed when the actuator layer (20) and / or the second actuator layer (40) is actuated and thus a position of the cover element (51) is changed in such a way that an opening cross-section of the actuator opening (33) is changed.

7. MEMS transducer according to claim 6, wherein the cover element (51) is designed in the form of a membrane, wherein in particular the membrane comprises a semiconductor material or consists of a semiconductor material.

8. MEMS transducer according to claim 6 or 7, wherein at least a second web (50) is provided as part of the actuator layer (20) and / or the second actuator layer (40), wherein the second web (50) is connected to the cover element (51), wherein the web (49) and the second web (50) are arranged on opposite sides of the cover element (51), wherein the shape of the web (49) and the second web (50) is changed when the actuator layer (20) and / or the second actuator layers (40) are actuated, and thus a height position of the cover element relative to the actuator opening is changed, so that the effective opening cross-section of the actuator opening (33) is changed.

9. MEMS transducer according to one of the preceding claims, wherein the second end regions of the two sections (13, 14) of a lamella section are connected to each other via a third section (15), wherein the third section (15) is arranged transversely to the orientation of the first and the second section (13, 14).

10. MEMS transducer according to one of the preceding claims, wherein the lamella (3) has several lamella sections (10, 11, 12), wherein the lamella sections (10, 11, 12) are each connected to each other via the second ends of the two sections of the lamella section by a connecting section (62), wherein each lamella section (10, 11, 12) defines a pressure chamber (16).

11. MEMS transducer according to claim 10, wherein the pressure chambers (16) open into a common outlet chamber (44), wherein the closing element (26, 27, 28) is arranged at the outlet chamber (44), wherein the closing element (26, 27, 28) can connect the outlet chamber (44) to an environment.

12. MEMS transducer according to claim 10, wherein each pressure chamber (16) opens into an output chamber (44, 45, 46), wherein each output chamber has a closing element (26, 27, 28).

13. MEMS transducer according to one of the preceding claims, wherein the pressure chamber (16) in the region of the two second ends of the two sections is closed in the y-direction with a cover (56), wherein the pressure chamber (16) is closed in the z-direction by two side walls (4, 6), wherein the closing element (26, 27, 28) is arranged in one of the side walls (4, 6) and can connect the pressure chamber (16) to the environment.

14. MEMS transducer according to one of the preceding claims, wherein the at least one section (13, 14) of the actuator layer (20) is configured to cause the section (13, 14) to vibrate at a first frequency, wherein the actuator layer (20) and / or the second actuator layer (40) of the closing element (26, 27, 28) are configured to vibrate at a second frequency, wherein the first frequency is higher than the second frequency, wherein in particular the first frequency is greater than 20 kHz and the second frequency is between 20 Hz and 20 kHz.

Images