MEMS loudspeakers and method for generating an audio signal

Abstract

The invention relates to MEMS loudspeakers comprising at least one pump chamber, within which an individually controllable piston is movably arranged. A MEMS loudspeaker comprises, for example, two passive valves or comprises, for example, one or more active valves which can be controlled independently of the piston. The movable parts, in particular pistons and valves, are driven, for example, using ultrasound. The invention further relates to systems for generating an audio signal, to devices for generating an audio signal, and to a computer program and a machine-readable storage medium.

Description

[0001] R.412195 - 1 -Description Title MEMS loudspeaker and method for generating an audio signal The invention relates to MEMS loudspeakers, methods for generating an audio signal, devices, systems for generating an audio signal, a computer program, and a machine-readable storage medium. State of the art The published patent application WO 2022 / 053165 A1 discloses a MEMS component. Disclosure of the invention The object underlying the invention is to provide a concept for efficiently generating an audio signal. This object is achieved by means of the respective subject matter of the independent claims. Advantageous embodiments of the invention are the subject matter of respective dependent subclaims.According to a first aspect, a MEMS loudspeaker is provided, comprising: at least one inflation element adjacent to a first and a second volume for pumping fluid, in particular air, from the first volume into the second volume, at least one deflation element adjacent to the first volume and the second volume for pumping fluid from the second volume into the first volume, R.412195 -. 2 -wherein the at least one inflation element and the at least one discharge element each have a pumping chamber within which an individually controllable piston is movably arranged, wherein the pumping chambers each have at least two passive valves, each of which has a greater flow resistance in one flow direction than in the opposite flow direction, wherein the at least two valves of the at least one inflation element are arranged such that a flow resistance for a flow from the first volume through the pumping chamber into the second volume is smaller than vice versa, wherein the at least two valves of the at least one discharge element are arranged such that a flow resistance for a flow from the second volume through the pumping chamber into the first volume is smaller than vice versa,such that, upon each actuation of the pistons, fluid can be pumped from the first volume through the pumping chamber of the at least one pumping element into the second volume and / or fluid can be pumped from the second volume through the pumping chamber of the at least one pumping element into the first volume to generate an audio signal. According to a second aspect, a method for generating an audio signal using the MEMS loudspeaker according to the first aspect is provided, comprising the following steps: receiving a request signal representing a request to generate an audio signal, determining a respective drive signal for respectively driving the pistons based on the received request signal such that upon each drive of the pistons, the audio signal is generated based on the respective drive signal, outputting the determined drive signals,to drive the pistons based on the corresponding drive signals. According to a third aspect, an apparatus for generating an audio signal is provided, which is configured to perform all the steps of the method according to the second aspect. R.412195 -, 3 -According to a fourth aspect, a system for generating an audio signal is provided, comprising the MEMS loudspeaker according to the first aspect and the device according to the third aspect. According to a fifth aspect, a MEMS loudspeaker is provided, comprising: at least one pumping element adjacent to a first and a second volume for pumping fluid, in particular air, from the first volume into the second volume or vice versa, wherein the at least one pumping element has a pumping chamber within which a controllable piston is movably arranged, wherein the pumping chamber has at least two accesses for a respective access to the pumping chamber from the first volume and from the second volume, at least one valve controllable independently of the piston for closing either one or the other of the at least two accesses, so that the respective other access is at least partially open,or to at least partially release the at least two accesses so that the at least two accesses are at least partially open, so that upon a respective actuation of the piston and the valve, fluid can be pumped from one of the first and second volumes through the corresponding access into the pumping chamber and through the other access into the other volume, or vice versa, in order to generate an audio signal. According to a sixth aspect, a method for generating an audio signal using the MEMS loudspeaker according to the fifth aspect is provided, comprising the following steps: receiving a request signal representing a request to generate an audio signal, determining a respective drive signal for respectively driving the piston and the at least one valve based on the received request signal such thatthat upon each drive of the piston and the at least one valve based on the respective drive signal, the audio signal is generated, outputting the determined drive signals in order to drive the piston and the at least one valve based on the corresponding drive signals. R.412195 -, 4 -According to a seventh aspect, a device for generating an audio signal is provided, which is configured to carry out all the steps of the method according to the sixth aspect. According to an eighth aspect, a system for generating an audio signal is provided, comprising the MEMS loudspeaker according to the fifth aspect and the device according to the seventh aspect. According to a ninth aspect, a computer program is provided, which comprises instructions which, when the computer program is executed by a computer, for example by the device according to the third aspect and / or by the system according to the fourth aspect and / or by the device according to the seventh aspect and / or by the system according to the eighth aspect, cause the computer to carry out a method according to the second aspect according to the sixth aspect.According to a tenth aspect, a machine-readable storage medium is provided on which the computer program according to the ninth aspect is stored. The invention is based on and includes the finding that the above object is achieved by using, for example, a MEMS loudspeaker which has two passive valves and individually controllable pistons. The fact that the pistons are individually controllable means in particular that they can be controlled independently of one another. This in particular provides the technical advantage that inflation can be controlled independently of deflation. This allows an audio signal to be generated efficiently. The provision of passive valves has the technical advantage in particular that the design is particularly simple. In particular, this has the technical advantage that mechanical wear is reduced.In particular, such a MEMS loudspeaker can be manufactured particularly easily and cost-effectively. R.412195 -. 5 -The second volume is, for example, an ear canal. The above task can also be solved, for example, by using a MEMS loudspeaker to generate an audio signal, which comprises at least one pump element whose pump chamber comprises a controllable piston. This controllable piston can be controlled independently of the valve. This means that the piston can be moved independently of the valve. This allows an audio signal to be generated particularly efficiently. In particular, pumping from the first into the second volume or vice versa can be carried out particularly efficiently, so that the audio signal can be generated efficiently via this. This therefore provides the technical advantage of providing a concept for efficiently generating an audio signal. A particular feature common to both MEMS loudspeakers is that they are operated, for example, at ultrasonic frequencies.This means that a drive frequency of one or more or all of the moving parts of the corresponding MEMS loudspeaker is operated at a frequency that lies in the ultrasonic range, i.e., in particular, above the perception threshold of human hearing. Moving parts are therefore pistons and valves. Ultrasound refers to sound with frequencies above the human audible frequency range. Ultrasound includes, in particular, frequencies from, for example, 20 kHz to, for example, 1 GHz. Thus, an ultrasonic frequency range within the meaning of the description is, in particular, a closed interval from 20 kHz to 1 GHz, in particular a closed interval from 20 kHz to 1 MHz. In one embodiment of the MEMS loudspeaker according to the first aspect, it is provided that at least one of the passive valves is a Tesla valve. This results in the technical advantage, for example, of using a particularly suitable passive valve. R.412195 -.6 -In one embodiment of the MEMS loudspeaker according to the first aspect, it is provided that at least one of the pump chambers has at least four passive valves, which are arranged opposite one another in pairs. This provides, for example, the technical advantage that pumping and deflation can be carried out efficiently. The opposing arrangement of the valve pairs each defines a straight line. The corresponding piston can be displaced, in particular, orthogonally to the respective straight line. In one embodiment of the method according to the second aspect, it is provided that, for a rising section of the audio signal to be generated, determining the drive signal for the piston of the at least one pumping element comprises determining the time derivative of the audio signal to be generated with respect to the rising section and using the determined derivative as the amplitude of the drive signal.This results in the technical advantage, for example, that the drive signal can be determined efficiently, so that the audio signal can be generated efficiently. In one embodiment of the method according to the second aspect, it is provided that for a rising section of the audio signal to be generated, determining the drive signal for the piston of the at least one pumping element comprises setting that an amplitude of the drive signal is zero. This results in the technical advantage, for example, that the drive signal can be generated efficiently, so that the audio signal can be generated efficiently. In one embodiment of the method according to the second aspect, it is provided that for a falling section of the audio signal to be generated, determining the drive signal for the piston of the at least one pumping element comprises determining the time derivative of the audio signal to be generated. 7 -related to the falling section and using an amount of the determined derivative as the amplitude of the drive signal. This results in the technical advantage, for example, that the drive signal can be generated efficiently, so that the audio signal can be generated efficiently via this. In one embodiment of the method according to the second aspect, it is provided that, for a falling section of the audio signal to be generated, determining the drive signal for the piston of the at least one pumping element comprises specifying that an amplitude of the drive signal is zero. This results in the technical advantage, for example, that the drive signal can be generated efficiently, so that the audio signal can be generated efficiently via this.According to one embodiment of the method according to the second aspect, it is provided that for an audio signal to be generated which, upon generation, generates a constant sound pressure level not equal to zero Pa, the respective drive signals are determined such that, upon each drive of the piston, they are pumped up and down with equal force based on the respective drive signal, in particular after reaching the sound pressure level to be generated, which is generated in particular by pure pumping. This results in the technical advantage, for example, that an audio signal can be efficiently generated which has a constant sound pressure not equal to zero Pa. In one embodiment of the method according to the second aspect, it is provided that a frequency in the ultrasonic range is used as the drive frequency for at least one of the drive signals, in particular for all drive signals.This results in the technical advantage, for example, that the audio signal can be generated efficiently. R.412195 -. 8 -The aforementioned time derivative is a first-order time derivative. In one embodiment of the MEMS loudspeaker according to the fifth aspect, the pumping chamber is open on one side or closed on both sides with respect to a direction of movement of the piston. A pumping chamber open on one side has the particular technical advantage that the negative influence of a compressed gas spring due to compression of fluid by the piston can be efficiently reduced. In particular, such a MEMS loudspeaker can be easily manufactured because, for example, fewer trench processes need to be used. A further advantage of the one-sided design lies particularly on the control side because, for example, only two electrical drive signals are required. The valves all act in parallel, for example, so only one phase relative to the piston needs to be adjusted.The design closed on both sides, for example, has the technical advantage that pumping efficiency is increased compared to the design open on one side, since both sides of the pump chamber can be used for pumping. The design closed on both sides, for example, has the technical advantage that ultrasound radiation can be efficiently reduced, provided the drive frequency is in the ultrasonic range.In one embodiment of the MEMS loudspeaker according to the fifth aspect, the pumping chamber closed on both sides is formed as a double pumping chamber having four or more accesses, via which, in pairs, access to the pumping chamber is possible from the first volume and from the second volume, wherein two individually controllable valves are provided to close either one or the other of the two accesses of the pair, so that the other access of the pair is at least partially open. R.412195 -. 9 -This results in the technical advantage, for example, that pumping can be carried out efficiently, so that an audio signal can be generated efficiently. Here, for example, it is provided that both sides of the piston can be used for pumping. The valves that close or at least partially open the paired accesses are, for example, controlled in opposite directions. Thus, for example, three drive signals are determined: a first drive signal for the piston, a second drive signal for one valve, and a third drive signal for the other of the valves. In one embodiment of the MEMS loudspeaker according to the fifth aspect, it is provided that the piston is arranged to be laterally or vertically movable, so that a pumping movement of the piston is lateral or vertical. This results in the technical advantage, for example, that particularly suitable directions can be provided with regard to the pumping movement.A vertical pumping direction, for example, has the technical advantage that a pumping area can be larger than a substrate area, in particular the chip area, on which the MEMS loudspeaker is arranged. In other words, it is provided, for example, that the MEMS loudspeaker is arranged or formed on a substrate, for example a wafer. The substrate or wafer defines a main extension plane, the size of which limits a maximum pumping area for MEMS loudspeakers whose pumping movements are lateral, i.e., parallel to the main extension plane. In contrast, with a vertical pumping movement, the pumping area is relocated deeper, so that the pumping area can be significantly larger than the substrate area. Thus, a substrate area can be efficiently utilized with regard to a pumping area.The design involving a lateral pumping motion has the particular technical advantage that such a structure can be manufactured particularly easily. R.412195 -. 10 -In one embodiment of the MEMS loudspeaker according to the fifth aspect, it is provided that a closure part of the valve is arranged to be vertically movable, so that the corresponding access can be closed by a vertical movement of the closure part. This results in the technical advantage, for example, that the corresponding access can be closed efficiently. The wording "at least partially" was used above, i.e., for example, "at least partially open" or "at least partially to be released." This means that the access can, for example, be partially open or, for example, completely open. In other words, the wording "at least partially" includes the following: "partially" and "completely."In one embodiment of the method according to the sixth aspect, it is provided that a frequency in the ultrasonic range is used as the drive frequency for at least one of the drive signals, in particular for all drive signals. This results in the technical advantage, for example, that the audio signal can be generated efficiently. Device features result analogously from corresponding method features and vice versa. This means that features of the MEMS loudspeakers result from corresponding features of the corresponding methods and vice versa. The same applies analogously to the systems whose features result analogously from method features and / or device features.Features of the MEMS loudspeaker according to the first aspect, the method according to the second aspect, the device according to the third aspect and the system according to the fourth aspect result, for example, analogously from the MEMS loudspeaker according to the fifth aspect, from the method according to R.412195 -. 11 -sixth aspect, from the device according to the seventh aspect and from the system according to the eighth aspect and vice versa. Corresponding statements made for the subject matters of aspects 1 to 4 result analogously from statements relating to the subject matters according to aspects 5 to 8 and vice versa. A method within the meaning of the description is, for example, a computer-implemented method. A device and / or a system within the meaning of the description is, for example, program-technically configured to execute the computer program. A method within the meaning of the description comprises, for example, a step of driving the piston and / or the valve based on the corresponding output drive signal. Statements made in connection with one piston apply analogously to multiple pistons and vice versa. Statements made in connection with one valve apply analogously to multiple valves and vice versa.A second volume within the meaning of the description is, for example, an ear canal. A MEMS loudspeaker is, for example, enclosed in a pair of headphones. A pair of headphones is, for example, an in-ear headset. Control within the meaning of the description is, for example, an electrical control. A drive signal within the meaning of the description is, for example, an electrical drive signal. R.412195 -. 12 -Statements made in connection with one drive signal apply analogously to multiple drive signals and vice versa. A headphone in the sense of the description is, for example, an earphone, an earbud, a headphone, a head-mounted speaker, or, for example, a bone conduction earphone. The phrase "at least one" means "one or more." MEMS stands for "micro-electro-mechanical system." The invention is explained in more detail below using preferred embodiments. Herein: Fig. 1 shows a MEMS loudspeaker according to the first aspect. Fig. 2 shows a flowchart of a method according to the second aspect. Figs. 3 to 8 each show a MEMS loudspeaker according to the fifth aspect. Fig. 9 shows a flowchart of a method according to the sixth aspect. Fig. 10 shows a device according to the third aspect. Fig. 11 shows a device according to the seventh aspect.12 a system according to the fourth aspect,Fig.13 a system according to the eighth aspect,Fig.14 a machine-readable storage medium according to the tenth aspect, R.412195 -. 13 -Fig. 15 shows a graph, and Figs. 16 to 46 each show a view of an exemplary embodiment of elements of a MEMS loudspeaker according to the concept described here. In the following, the same reference numerals may be used for the same features. It should also be noted at this point that if only the term "loudspeaker" is used, "MEMS" should always be included, so that the term "loudspeaker" stands for "MEMS loudspeaker." It should also be noted that if the term "lamella" is used in the description, it should be understood that this can be an exemplary embodiment of a piston or a valve or a closure part of a valve, depending on the corresponding context. The term "valve opening" refers to the access to the pumping chamber. Fig. 1 shows a MEMS loudspeaker 101 according to the first aspect.The MEMS loudspeaker 101 comprises an inflating element 103 and a discharging element 105. The inflating element 103 borders a first volume 107 and a second volume 109. The discharging element 105 borders the first volume 107 and the second volume 109. The inflating element 103 is configured to pump fluid, in particular air, from the first volume 107 into the second volume 109. The discharging element 105 is configured to pump fluid, in particular air, from the second volume 109 into the first volume 107. Both pumping elements, i.e. the inflating element 103 and the discharging element 105, each comprise a pumping chamber: The inflating element 103 comprises R.412195 -. 14 -a first pumping chamber 111. The pumping element 105 comprises a second pumping chamber 113. Within each of the two pumping chambers 111, 113, an individually controllable piston is movably arranged: a first piston 115 is arranged in the first pumping chamber 111. A second piston 117 is arranged in the second pumping chamber 113. Both pistons 115, 117 are individually controllable and movably arranged within the corresponding pumping chamber 111, 113. The pistons 115, 117 move in a lateral direction. Thus, both pistons 115, 117 can be driven independently of one another. The pumping chambers 115, 117 each have four passive valves, each of which has a greater flow resistance in one flow direction than the opposite flow direction. The first pumping chamber 111 has a first valve 119, a second valve 121, a third valve 123, and a fourth valve 125. The first valve 119 borders the second volume 109.The second valve 121 borders the first volume 107. The third valve 123 borders the second volume 109. The fourth valve 125 borders the first volume 107. The first valve 119 and the second valve 121 are arranged opposite one another and form a first pair of passive valves. The third valve 123 and the fourth valve 125 form a second pair of passive valves. The third valve 123 and the fourth valve 125 are arranged opposite one another. The four valves 119, 121, 123, 125 are arranged such that a flow resistance for a flow from the first volume 107 through the first pumping chamber 111 into the second volume 109 is smaller than vice versa. Thus, the flow resistance for flow from the first pump chamber 111 through the first valve 119 into the second volume 109 is smaller than the other way around. R.412195 -. 15 -Thus, a flow resistance for a flow from the first volume 107 through the second valve 121 into the first pumping chamber 111 is smaller than the other way around. Thus, a flow resistance for a flow from the first pumping chamber 111 through the third valve 123 into the second volume 109 is smaller than the other way around. Thus, a flow resistance for the flow from the first volume 107 through the fourth valve 125 into the first pumping chamber 111 is smaller than the other way around. The second pumping chamber 113 has a fifth valve 127, a sixth valve 129, a seventh valve 131, and an eighth valve 133. The four valves 127, 129, 131, 133 are arranged such that a flow resistance for a flow from the second volume 109 through the second pumping chamber 113 into the first volume 107 is smaller than the other way around. The fifth valve 127 and the sixth valve 129 are arranged opposite each other and form a third pair of valves.The seventh valve 131 and the eighth valve 133 are arranged opposite one another and form a fourth pair of valves. The fifth valve 127 borders the second volume 109. The sixth valve 129 borders the first volume 107. The seventh valve 131 borders the first volume 109. The eighth valve 133 borders the first volume 107. A flow resistance for a flow from the second volume 109 through the fifth valve 127 into the second pumping chamber 113 is smaller than the other way around. A flow resistance for a flow from the second pumping chamber 113 through the sixth valve 129 into the first volume 107 is smaller than the other way around. A flow resistance for a flow from the second volume 109 through the seventh valve 131 into the second pumping chamber 113 is smaller than the other way around. A flow resistance for a flow from the second pump chamber 113 through the eighth valve 133 into the first volume 107 is smaller than vice versa.When the pistons 115, 117 are respectively actuated, fluid can thus be pumped from the first volume 107 through the first pump chamber 111 into the second volume 109 and / or fluid can be pumped from the second volume 109 R.412195 -. 16 -through the second pumping chamber 113 into the first volume 107 to generate an audio signal. The second volume 109 can be, for example, an ear canal. The pistons 115, 117 can each be operated at frequencies that are above the frequency range audible to a human. For example, the corresponding drive frequencies are in the ultrasonic range. Fig. 2 shows a flow diagram of a method for generating an audio signal using a MEMS loudspeaker according to the first aspect.The method comprises the following steps: receiving 201 a request signal representing a request to generate an audio signal, determining 203 a respective drive signal for respectively driving the pistons based on the received request signal such that the audio signal is generated upon each drive of the pistons based on the respective drive signal, outputting 205 the determined drive signals in order to drive the pistons based on the corresponding drive signals. An exemplary control of the two pistons according to Fig. 1 is described below in order to generate an audio signal, for example a 1 kHz sine signal. Here, the pumping element 103 is referred to as the left pump or pump 1. The pumping element 105 is referred to below as the right pump or pump 2. The second volume 109 is the "adjacent volume (ear canal)" according to the following descriptions.The left pump (hereinafter referred to as Pump 1) is used to pump air into the adjacent volume (ear canal) due to the preferred direction of the valves. The right pump (hereinafter referred to as Pump 2) is used to pump air (R.412195) due to its preferred direction. 17 - from the adjacent volume. The pumping intensity is controlled by the amplitude of the applied voltage (higher voltage -> higher deflection -> stronger pumping intensity). The pumps are operated with the drive signal ^^ = ^(^) ⋅ sin(2 ⋅ ^ ⋅ ^^ ⋅ ^). ^: Amplitude^^: Drive frequency (In the ultrasonic range – greater than 20 kHz, e.g., 40 kHz) ^: Zeit Case 1: rising audio signal For a rising section of the audio signal (^ ^ ^ > 0) the derivative of the audio signal to be generated ^ ^ as amplitude of the drive signal. Only pump 1 is driven, or for pump 2, ^^ = 0.^^(^) = ^ ⋅ ^^ ^(^)^ : (Constant) factor for converting required voltage / per desired pump power Case 2: falling audio signal For a falling section of the audio signal (^ ^ ^ < 0) the amount of the derivative of the audio signal to be generated ^ ^ as amplitude ^ ^ of the drive signal. Only pump 2 is driven or for pump 1 = 0 . ^^(^) = ^ ⋅ |^^ ^ (^)| Example: Control for a 1 kHz sine signal For an exemplary 1 kHz audio signal with a voltage amplitude of 1 V, the two drive signals should look like this: R.412195 - 18 - Audio signal: cos(2 ⋅ ^ ⋅ 1 Pump drive signal sin(2 ⋅ ^ ⋅ ^^ ⋅ ^) , for ^ ^ ^^ > 0 and ^^^ = 0 , for ^^ ≤ 0Drive signal pump sin(2 ⋅ ^ ⋅ ^ ⋅ ^) , for ^ ^^ ^^ < 0 and ^^^ = 0 , for ^^ ≥ 0Summary Generating an audio signal with two high-frequency pumps with their respective preferred directions 1. With a positive slope of the audio signal, pump with pump 1. The higher the slope, the greater the deflection of pump 1. The pump frequency of the pump is constant in the inaudible ultrasonic range. Pump 2 is stopped. 2. With a negative slope of the audio signal, pump with pump 2. The higher the magnitude of the negative slope, the greater the deflection of pump 2 in the inaudible ultrasonic range. Pump 1 is stopped. 3. At a constant sound pressure level (e.g. 0): Both pumps pump up and down with the same amplitude / pump power. Figs. 3 to 8 each show a MEMS loudspeaker according to the fifth aspect. The MEMS loudspeaker is described in detail below with reference to Fig. 3. Regarding Figs. 4 to 8, reference is made to the explanations for Fig. 3.In this regard, the differences will be discussed accordingly. Fig. 3 shows a MEMS loudspeaker 301 according to the fifth aspect. R.412195 -. 19 -The MEMS loudspeaker 301 comprises a pumping element 303, which borders a first volume 305 and a second volume 307. The second volume 307 is, for example, an ear canal. The pumping element 303 is configured to pump fluid, in particular air, from the first volume 305 into the second volume 307 or vice versa. The pumping element 303 has a pumping chamber 309, within which a controllable piston 311 is arranged. The piston 311 can also be referred to as a pumping lamella. Furthermore, the pumping chamber 309 has a first access 313 and a second access 315. Access to the pumping chamber 309 from the second volume 313 is possible via the first access 313. Access to the pumping chamber 309 from the first volume 305 is possible via the second access 315. The two inlets 313, 315 can be closed or at least partially opened by means of a valve 317. The valve 317 can be controlled individually, i.e., independently of the piston 311.Thus, piston 311 and valve 317 can be actuated independently of one another. The valve 317 comprises a closure part 319, which can be controlled individually, i.e., independently of the piston 311. The closure part 319 is arranged to be movable in the vertical direction. The piston 311 is arranged to be movable vertically. The closure part 319 can thus close the first access 313 and open the second access 315, or vice versa. With a respective control of the piston 311 and the valve 317, in particular the closure part 319, fluid can be pumped from the first volume 305 through the second access 315 and through the pump chamber 309 and through the first access 313 into the second volume 307, or vice versa, in order to generate an audio signal. R.412195 -. 20 -The pump chamber 309 further has a third inlet 321 and a fourth inlet 323. The third inlet 321 enables access from the second volume 307 into the pump chamber 309. The fourth inlet 323 enables access from the first volume 305 into the pump chamber 309. The valve 317 can be referred to as a first valve. The closure part 319 can be referred to as a first closure part. Furthermore, a second valve 325 comprising a second closure part 327 is provided. The valve 325 and here the second closure part 327 can be controlled independently of the piston 311 and the first valve 317 or the first closure part 319. Thus, the piston 311, the first closure part 319, and the second closure part 327 can be operated or actuated independently of one another. Depending on the control, the valve 325 closes the third access 321 or the fourth access 327.The second closure part 327 is arranged to be movable in the vertical direction. Analogous to the explanations in connection with the first valve 317, air can thus also be pumped into the pump chamber 309 and out of the other of the accesses through the third access 321 or the fourth access 323, or vice versa, in order to generate an audio signal. In other words, by appropriately controlling the piston 311, the first closure part 319, and the second closure part 327, fluid, in particular air, can be pumped from the first volume 305 into the second volume 309, or vice versa, in order to generate an audio signal. Piston 311, first closure part 319, and second closure part 327 can each be operated at a drive frequency that lies above the range audible to humans. For example, the corresponding drive frequencies lie in the ultrasonic range. R.412195 -. 21 -The pump chamber 309 of the MEMS loudspeaker 301 is open on one side, in this case open at the top, to efficiently reduce the gas spring effect. Fig. 4 shows a MEMS loudspeaker 401 in which the pump chamber 309 is also open on one side, but in this case open at the bottom, to efficiently reduce the gas spring effect. Fig. 5 shows an exemplary embodiment of a MEMS loudspeaker 501 that is closed on both sides, thus reducing the radiation of frequencies that are at or near the drive frequency, such as ultrasound. Fig. 6 shows an exemplary embodiment of a MEMS loudspeaker 601, wherein the pumping chamber 309 is closed on both sides and is a double pumping chamber. In the MEMS loudspeakers according to Figs. 3 to 6, both piston 311 and closure parts 319, 327 move in the vertical direction. Fig.Figure 7 shows a MEMS loudspeaker 701, according to which the closure parts 319, 327 continue to move vertically. The piston 311 moves laterally or horizontally. Figure 7 shows the MEMS loudspeaker 701 with multiple pump chambers, with only the middle pump chamber being provided with reference numerals for the sake of clarity. To reduce the movement path for the valves, it is provided, for example, to extend the side walls of the pump chamber 309 toward the center, which is shown by way of example in Figure 7. R.412195 -. 22 -To achieve the same effect, i.e., a reduction in the travel distance, the height of the valve blocks can also be increased, as exemplified by the MEMS loudspeaker 801 in Fig. 8. For example, it is intended that piston 311 and the closure parts 319, 327 have the highest possible resonant frequency. Ideally, the piston 311 and the closure parts 319, 327 are operated at or near their corresponding resonant frequency (1st vibration mode). This should be outside the audible frequency range (over 20 kHz). This leads to a resonance increase in the deflection. This means lower power consumption for the same deflection. The resonant frequency depends in particular on the mass and flexural rigidity of the elements, i.e., on their geometry. Thus, "high resonant frequency" means a frequency greater than or equal to 20 kHz.A closure part of a valve is formed, for example, as a valve membrane or is a valve membrane. Fig. 9 shows a flow diagram of a method for generating an audio signal using a MEMS loudspeaker according to the fifth aspect. The method comprises the following steps: receiving 901 a request signal representing a request to generate an audio signal, determining 903 a respective drive signal for respectively driving the piston and the valve based on the received request signal such that the audio signal is generated upon each drive of the piston and the valve based on the respective drive signal, outputting 905 the determined drive signals in order to drive the piston and the valve based on the corresponding drive signals. R.412195 -. 23 -Fig. 10 shows a device 1001 for generating an audio signal, which is configured to carry out all steps of the method according to the first aspect. Fig. 11 shows a device 1101 for generating an audio signal, which is configured to carry out all steps of the method according to the sixth aspect. Fig. 12 shows a system 1201 for generating an audio signal, comprising a MEMS loudspeaker 1203 according to the first aspect, which for the sake of clarity is only symbolically represented by a square, and the device 1001 according to Fig. 10. Fig. 13 shows a system 1301 for generating an audio signal, comprising a MEMS loudspeaker 1303 according to the fifth aspect, which for the sake of clarity is only symbolically represented by a square, and the device 1101 according to Fig. 11.At this point, it should be noted that a device within the meaning of the description can, for example, have an input which is configured to receive the corresponding request signal. A device within the meaning of the description comprises, for example, one or more processors for determining the respective drive signal(s). The processor(s) are, for example, configured to determine the corresponding drive signal(s). Determining a drive signal comprises, for example, generating a drive signal. A device within the meaning of the description comprises, for example, an output which is configured to output the determined drive signals, i.e., the generated drive signals. The output is thus configured to output the determined drive signal(s). R.412195 -. 24 -Fig. 14 shows a machine-readable storage medium 1401 on which a computer program 1403 is stored. The computer program 1403 comprises instructions which, when executed by a computer, cause the computer program 1403 to carry out a method according to the second aspect and / or according to the sixth aspect. Fig. 15 shows a graph 1501 graphically representing a temporal voltage profile of several voltages. The time in seconds is entered on the abscissa 1503. The voltage in volts is entered on the ordinate. A legend is also drawn, according to which three differently displayed lines are shown: a first line 1507, a second line 1509, and a third line 1511. The first line 1507 shows the temporal voltage profile of the 1 kHz sinusoidal signal described above: U S The second line 1509 shows the voltage curve of the drive signal for pump 1 described above: U D1The third line 1511 shows the voltage curve of the drive signal for pump 2 described above: U D2 The concept described here describes, in particular, an exemplary control principle of MEMS loudspeakers for generating sound signals. Several possibilities for suspending and driving the MEMS loudspeakers, specific dimensions and aspect ratios of the loudspeaker design, as well as design variations of the individual loudspeaker elements are described by way of example. For example, a distinction is made between an exemplary first embodiment (Embodiment A), which comprises three superimposed, autonomously movable layers, and an exemplary R.412195 - 25 -second embodiment (embodiment B), which comprises three superimposed layers with only two movable element groups in the middle layer. Embodiment A Basic structure The MEMS loudspeaker comprises, for example, three layers. The middle layer comprises, for example, several beams (or lamellae or fins) moving in phase and static or non-movable beams. These are arranged alternately, for example. The upper and lower layers each consist, for example, of several beams arranged above the movable beams of the middle layer. Alternatively, the upper and lower layers consist, for example, of a slotted plate in which there is one or two slots (one per adjacent pumping chamber) per static beam of the middle layer (cf. Fig. 17 to Fig. 20).Two static lamellae, one movable lamella and one cover or two slots, each from the upper and lower layer, together form a pumping chamber (see Fig. 16). The loudspeaker comprises several identical pumping chambers. All elements of the upper layer are moved in phase, for example. The same applies to the lower layer, for example. The movable lamellae of the middle layer either all move in phase or alternately in opposite directions, depending on the drive concept. The area in which the pumping chambers are located is referred to below as the pumping zone. Control principle For the control principle described here, it is assumed, as an example, that the pumping beam is at 0 deflection in the middle of a pumping chamber, i.e. exactly midway between two static lamellae. The valve openings are at 0 deflection in a position that represents a half-open valve. R.412195 -. 26 -Pure pumping of an adjacent volume (e.g., the ear canal) with maximum pumping power is achieved with a constant phase relationship between the movement of the three layers: upper valve layer 270°, middle pumping layer: 0°, lower valve layer: 90°. A sinusoidal tone of frequency f s is generated by the following phase relationship of the movement of the three layers: upper valve layer: ^ ∙ sin (2^^^^) middle pump layer: 0 lower valve layer: −^ ∙ sin (2^^^^) a: factor / amplitude of the phase modulation f s: Frequency of the generated sine signal t: Time. Suspension and drive of the loudspeaker elements The loudspeaker elements are mechanically suspended by various microstructured elements. Each level is moved, for example, by its own drive. a) Suspension concepts and design of the valve level 1. The valve level consists, for example, of either a slotted plate or of several beams located above and below the pumping chambers. i. The slotted plate of the valve layer is connected, for example, via one or more shuttles to the drive of the respective valve level (see Fig. 21 to Fig. 23). R.412195 - 27 -ii. All beams of the valve level are firmly connected to one another and to the respective drive of the valve layer, e.g. via a frame or a shuttle (see Fig. 21 to Fig. 23). The plate, the frame, the shuttle and / or the movable elements of the valve drive are suspended, e.g., with one or more spring elements (e.g., by various spring elements: beam springs clamped on both sides, beam springs clamped on one side, folded beam springs, crab leg suspension, Y-springs, meandering springs, etc.) attached to an armature, also by one or both sides of fixed clamping. The spring elements are, e.g., more flexible in the direction of movement of the drive than in the two other spatial directions (see Fig. 21 to Fig. 23). 2. The beams of the valve layer are firmly connected to one another, e.g. via a shuttle. Each beam is attached to its own spring element and connected to an anchor (one or more anchors) (see Fig.24 and Fig.25).b) Actuation of the valve plane 1. For example, there is an external drive outside the pumping zone of the loudspeaker. This is connected to the movable valve elements via a shuttle or similar device. Example drives: Comb drive A, piezoelectric, electrodynamic (see Fig. 21 Fig. 25). 2. Valve variation: Bending actuator Piezoelectric / ES (electrostatic) The valves can be realized, for example, by movable valve beams above the static beams of the pumping plane. When actuated (e.g., electrostatically or piezoelectrically), the valve beams move away from the pumping plane, thereby opening the valve opening. The rest of the pumping chamber is covered, for example, by a static cover (top and bottom) (see Fig. 30 and Fig. 31). R.412195 -. 28 -3. A valve layer comprises, for example, several valve beams. One or more of these valve beams are located above and below each pump chamber. When the valve beams are at zero deflection, the valves on the right and left are each half open. Above each static lamella there is, for example, a stator element to which an electrical potential is applied. The stator element can be suspended or firmly connected to the static lamella. A positive and negative potential is alternately applied to the stator elements. An alternating electrical potential is applied to the valve beam, for example. Due to the electrostatic attraction of two plates with different electrical potentials, the valve beam is moved alternately from one stator element to the other, and the valve openings open and close. For example, it is intended to apply the alternating potential to the stator element and the constant potential to the valve beam (see Fig. 32 and Fig. 33).c) Suspension concepts for the pumping level 1. All movable pumping beams in the middle level are connected, for example, by a frame or a shuttle. All static beams in the middle level are connected, for example, by a frame or a shuttle. The frames of the static and movable beams are not connected, for example, but lie one above the other. The frames are each attached to one or more anchors with one or more spring elements. The frame of the movable beams is connected, for example, to one or more drives (e.g., via a shuttle) (cf. Fig. 21 to Fig. 23). 2. Each movable element is connected, for example, to one or more anchors with its own spring element (cf. Fig. 24 to Fig. 29). 3. Each static element is connected, for example, directly to an anchor or via a spring element to one or more anchors (cf. R.412195 -. 29 -Fig.24 to Fig.29). Individual armatures can, for example, be used to apply different electrical potentials to the static and movable lamellae.d) Pump level drives1. For example, there is an external drive next to the pump zone of the loudspeaker. This is connected, for example, to the movable beams of the pump layer via a shuttle (cf. Fig.21 to Fig.23). Example drives: comb drive A, piezoelectric, electrodynamic). 2. The internal actuation of the movable pump beams occurs, for example, via different electrical potentials that are applied to the movable and static beams of the middle layer.i. For an alternating actuation direction of the pump beams in each pump chamber, the following electrical potentials are applied, for example (cf. Fig.26 and Fig.27): Static lamella A: -U0Movable lamella C: ^^sin (2^^^^)Static lamella B: U0The movable beam in pumping chamber 1 is thus first moved towards static beam A (left wall of the pumping chamber) and then towards static beam B (right wall of the pumping chamber). Since beam B is the left side wall of the next, adjacent pumping chamber 2 on the right, the pumping beam in chamber 2 moves first to the right and then to the left. The gaps in the valve layer are, for example, adjusted to achieve the same pumping direction and intensity in all pumping chambers (cf. Fig. 26 and Fig. 27). The deflection of the valve plane is ideally greater than that of the pumping plane. R.412195 -. 30 -ii. For one actuation direction in all pumping chambers, the following electrical potentials are applied accordingly (see Fig. 28 and Fig. 29): Static lamella A: -U0 Movable lamella C: ^^sin (2^^^^) Static lamella B: U0 Movable lamella D: −^^sin (2^^^^) The various suspension and drive options can be combined as desired with minor adjustments. Dimensions and aspect ratios The pumping chamber is, for example, between 5 µm and 100 µm high, ideally around 20 µm. Large trench depths lead to stronger damping effects and thus to power loss. The ratio between maximum valve opening VG and clearance Cl between the beams is, for example, at least: VG = 1.5 Cl. The maximum valve opening is at least 0.5 µm and ideally larger than 1.2 µm to avoid or reduce excessive flow resistance.This prevents volume flow limitation, and high sound pressure can be achieved with small geometries. The first bending mode of the pump fin, for example, is located at the drive frequency to achieve higher deflection at a constant voltage. Design variations of pump fin geometry ^. Konkav ○ A concave volume of the movable or static fins allows a lower pumping chamber pressure to be achieved with the same pumping chamber footprint. ^ Konvex R.412195 - 31 - ○ A convex volume of the movable or static vanes allows for a higher pumping chamber pressure with the same pumping chamber footprint. Higher pressure in a pumping chamber leads to higher flow out of the pumping chamber. Lower flow reduces the force required to actuate the pumping vane. ^ T-Ende○ The T-end on the static fin results in greater overlap with the valve outlet. This leads to lower leakage flow when the valve is closed. ^Taper○ The taper on the static fin results in a higher average flow when the valve opens due to the higher cross-sectional geometry. Design B Basic structure The loudspeaker, for example, comprises 3 layers. In the middle layer, there are two groups of moving elements. Each group performs an identical movement and consists of several (identical) bars / fins / fins. The upper and lower layers each consist of a slotted plate or similar. The slots are located above or directly next to the pumping elements (bars / fins / fins) of the middle layer (see Fig. 28). The slots are located alternately at the top and bottom.When the pump elements are moved: ^The pressure in the adjacent pump chambers changes^ The gap above / below is opened / closed and closed / opened to the other adjacent pump chamber R.412195 -. 32 - Control principle The two moving element groups are operated with a phase offset in their movement to pump air in one direction. With a fixed phase offset, a constant pumping power (in several pumping pulses) is achieved in one direction. For the maximum pumping power in one direction, the phase relationship is: PG = pump group PG1: 0°, PG2: 90° Generation of a sine tone: PG1: ^ ∙ sin (2^^^^), PG2: −^ ∙ sin (2^^^^) a: Factor / amplitude of the phase modulation f s: Frequency of the generated sine signal t: Time Suspension and drive of the loudspeaker elements 1. The static valve layers (top and bottom) can be suspended a. e.g. by various spring elements: double-clamped beam springs, single-clamping beam springs, folded beam springs, crab leg suspension, Y-springs, meandering springs, etc. b. They can be firmly connected to the system by anchors or a frame. c. They can be structured in a substrate and a cover wafer. 2. The two movable groups in the middle layer can be suspended, for example, as follows: R.412195 - 33 -a. On one or more frames or shuttles per element group, each of which is attached with one or more spring elements: e.g., beam springs clamped on both sides, beam springs clamped on one side, folded beam springs, crab leg suspension, Y-springs, meander-shaped springs, etc. The frames or shuttles are located in different planes for the various moving element groups (see Fig. 39 to Fig. 41) or run through an edge area of ​​the slats of the other group (structured opening in the slat). b. The individual slats are each individually attached with their own spring element (see Fig. 44: clamped-clamped variant. Other spring elements are also provided, for example). 3. Drive a. The moving object groups are driven, for example, with a drive outside the pumping zone. E.g.a comb drive, several plate capacitors arranged one behind the other (comb drive version B), a piezoelectric bending actuator, or an electrodynamic drive (electrostatic most likely) (see Fig. 39 to Fig. 41). b. The moving object groups are driven, for example, by an electrostatic drive in a plane (direction of movement parallel to the short sides of the electrode surfaces). The electrodes are located, for example, above and below the movable beams. The slots of the valves are located, for example, only in the middle area of ​​the pump chambers, the electrostatic drives, for example, in the outer area (see Fig. 42 to Fig. 44). The moving object groups are driven by an electrostatic drive in a plane (direction of movement parallel to the short sides of the electrode surfaces). The electrodes are located, for example, above and below, over the entire length of the movable beams. The slots of the valves are located, for example,In the direction of actuation, directly next to the electrostatic drives. Each R.412195 -. 34 -in front of and behind. The slots are located, for example, only in the regions where a high deflection of the movable beams is to be expected, i.e. in the central region (cf. Fig. 45 and Fig. 46). Dimensions and aspect ratios The pump chamber is, for example, between 5 µm and 100 µm high, ideally around 20 µm. Large trench depths lead to stronger damping effects and thus to a loss of power. The ratio between maximum valve opening VG and clearance Cl between the beams is, for example, at least: VG = 1.5 Cl. The maximum valve opening is, for example, at least 0.5 µm and ideally larger than 1.2 µm in order to avoid or reduce excessive flow resistance. This prevents limitation of the volume flow, and high sound pressure can be achieved with small geometries and a small footprint. Ideally, the deflection of the slats in both directions is at least half the width of the valve gap.In this way, the maximum effect of valve opening and volume change on pump performance can be achieved. The first bending mode of the pump plate, for example, is located at the drive frequency to achieve greater deflection with constant voltage. Valve design variations ^By beveling or conically shaping the valve gap, flow optimization in one direction can be achieved (see Fig. 1: pumping-deflating principle). Pump plate geometry ^. Konkav ○ A concave volume of the movable or static vanes allows for a lower pumping chamber pressure with the same pumping chamber footprint. R.412195 - 35 - ^ Konvex ○ A convex volume of the movable or static vanes allows a higher pumping chamber pressure to be achieved with the same pumping chamber footprint. ^ T-Ende○ The T-end on the static lamella results in greater overlap with the valve outlet. This leads to lower leakage flow when the valve is closed. ^Taper○ The taper on the static lamella results in a higher average flow when the valve is opened due to the higher cross-sectional geometry. An embodiment of a MEMS loudspeaker according to the first aspect comprising passive valves is described below, wherein the MEMS loudspeaker can be operated, for example, according to the pump-up-pump-down principle. A volume (e.g., in English: "ear coupler") is adjacent to one or more pumping elements, wherein one or more of the pumping elements are specifically designed to inflate the volume and some are designed to pump fluid, e.g., air, out of the volume. This is possible with the loudspeaker concepts described above.This can also be achieved using pumping elements that include pumping chambers with passive valves. These valves have a narrowing or widening shape, resulting in a higher flow resistance in one direction. Other passive valves, such as Tesla valves, are also available. If two of these valves are arranged in a chamber such that one valve has a higher flow resistance for flow out of the chamber (connected to volume A, the second volume) and the other one for flow out, the resulting flow resistance can be increased. 36 -higher flow resistance for flow into the chamber (connected to volume B, first volume), then with an alternating volume change in this chamber more air can be pumped from volume B into volume A up to a certain pressure difference. This can be used in various arrangements to create a loudspeaker with the described pump-up-pump-down principle (see Fig. 1). The system of valve and pump chamber can also be implemented in other configurations. Figs. 3 - 6 show a purely vertical structure. The valves here consist of a movable membrane, for example, which can either at least partially open or at least partially block access to the top or bottom. The pump chamber only compresses a volume on one side at a time. The back of the pump membrane is open either at the top or at the bottom to reduce the negative influence of the compressed gas spring.The main advantage of these variants is simpler production, as fewer trench processes are used. Another advantage of the single-sided design is on the control side, as only two electrical signals are required. The valves all act in parallel; only the phase with respect to the pump membrane needs to be adjusted. The disadvantage is the lower efficiency, as only one side of the pump chamber is used. All horizontal principles have the disadvantage that the utilization of the wafer area is lower, since the membrane area can correspond at most to the chip area. In vertical variants, the pump area is placed deeper and can therefore be significantly larger than the chip area. To increase efficiency, the other side of the pump chamber can also be used in parallel, as shown in Fig. 6. However, the control then requires at least three signals for the pump chamber and two separate valves. Fig.7 and 8 show the combination of a horizontal pumping chamber and two vertical valves.The MEMS loudspeakers (embodiment A and embodiment B, as well as pump-up-pump-down principle) can be described as micro-electromechanical R.412195 -. 37 -Systems (MEMS) can be realized using common manufacturing processes in microsystems technology. In this case, layers are alternately applied, structured, and removed on a silicon substrate to create functional layers with movable structures. In addition to coatings with polycrystalline silicon or silicon oxide, lithography steps for structuring as well as etching and trench processes for exposing functional structures are among the most important manufacturing methods for producing the loudspeakers. Fig. 16 shows a pumping chamber 1601. Reference numeral 1603 indicates an upper layer of the pumping chamber 1601. Reference numeral 1605 indicates a lower layer of the pumping chamber 1601. Reference numeral 1607 indicates a first static lamella. Reference numeral 1608 indicates a second static lamella. Reference numeral 1609 indicates a piston arranged within the pumping chamber 1601.Reference numeral 1611 indicates a passage between piston 1609 and upper layer 1603. Reference numeral 1613 indicates a valve opening. Fig. 17 shows an exemplary valve layer 1701. Fig. 18 shows the valve layer 1701 with an underlying pumping layer 1801. Reference numeral 1803 indicates a static lamella of the pumping layer 1801. Reference numeral 1805 indicates a movable lamella of the pumping layer 1801. Fig. 19 shows another valve layer 1901. Fig. 20 shows the valve layer 1901 with an underlying pumping layer 2001. Reference numeral 2003 indicates a static lamella of the pumping layer 2001. Reference numeral 2005 indicates a movable lamella of the pumping layer 2001. Fig. 21 shows a pumping chamber 2101 in a side sectional view. Reference numeral 2103 denotes an upper drive layer. Reference numeral 2105 denotes a frame valve layer. The reference number 2107 designates R.412195 -. 38 -static elements of the frame. Reference numeral 2109 denotes pumping elements, i.e., pistons, of the frame. Reference numeral 2111 denotes a drive for movable vanes. Reference numeral 2113 denotes a lower drive layer. Fig. 22 shows a plan view of an exemplary pumping chamber 2201. Reference numeral 2203 indicates a drive valve layer. Reference numeral 2205 indicates a static vane. Reference numeral 2207 indicates a movable vane. Reference numeral 2209 indicates a frame valve layer. Reference numeral 2211 indicates an armature. Reference numeral 2213 indicates movable and static frame elements, which have different deflections in the Z direction. The Z direction here denotes the plane of the paper. Reference numeral 2215 denotes spring elements belonging to the valve. The reference number 2217 indicates spring elements which belong to the static elements.Reference numeral 2219 indicates spring elements belonging to the movable elements. Fig. 23 shows an exemplary pump chamber 2301. Reference numeral 2302 indicates spring elements of the drive. Reference numeral 2303 indicates static elements of the frame. Reference numeral 2305 indicates pump elements, i.e., pistons. Reference numeral 2307 indicates the frame of the pump elements 2305. Reference numeral 2309 indicates a movable drive plate. Reference numeral 2311 indicates static elements. Fig. 24 shows an exemplary pump chamber 2401. Reference numeral 2403 indicates a shuttle valve layer. Reference numeral 2405 indicates shuttle pump elements. Reference numeral 2407 indicates spring elements of the valve. Fig. 25 shows an exemplary pumping chamber 2501. Reference numeral 2503 indicates a movable vane. Reference numeral 2505 indicates a static vane. Reference numeral 2507 indicates a shuttle valve layer.Reference numeral 2508 indicates spring elements of the valve layer. R.412195 -. 39 -Fig. 26 shows an example pumping chamber 2601: valve level with a common frame, pumping levels: separate springs plus internal drive, static lamellae: separate springs, side view (section through pumping chamber). Fig. 27 shows an example pumping chamber 2701: valve level with a common frame, pumping level: separate springs plus internal drive, static lamellae: separate springs, top view. Fig. 28 shows an example pumping chamber 2801: valve level with a common frame and suspension, pumping elements each with their own springs and internal drive, static elements with their own armature and their own contact, side view (section through pumping chambers). Fig. 29 shows an example pumping chamber 2901: valve level with a common frame and suspension, pumping elements each with their own springs and internal drive, static elements with their own armature and their own contact, top view. Fig.Fig. 30 shows a front view of a bending valve 3001 in a sectional view through a static lamella 3005. Reference numeral 3003 indicates a first bending valve. Reference numeral 3007 indicates a second bending valve. Fig. 31 shows the bending valves according to Fig. 30 in a side view 3103 according to a section through a pumping chamber. Reference numeral 3105 indicates an open valve. Reference numeral 3107 indicates a static valve element. Reference numeral 3109 indicates a movable lamella. Fig. 32 shows an exemplary pumping chamber 3201 according to an internal actuation of the valves in a plan view. Reference numeral 3205 indicates spring elements of the static valve elements. Reference numeral 3207 indicates spring elements of the static valve elements. Reference numeral 3209 indicates spring elements of the movable valve elements. R.412195 -. 40 -Fig. 33 shows a side view 3301 of a section through pumping chambers. Internal actuation of the valves is shown. Reference numeral 3303 indicates a drive for the movable lamella. Reference numeral 3305 indicates frame pumping elements. Reference numeral 3307 indicates a static valve element. Reference numeral 3309 indicates a static valve element. Reference numeral 3311 indicates static frame elements. Fig. 34 shows several pumping chambers 3401, each having concave pumping beams 3403. Fig. 35 shows several pumping chambers 3501, each having convex pumping beams 3503. Fig. 36 shows several pumping chambers 3601, each having pumping beams 3503 with T-ends. Fig.37 shows several pump chambers 3701, each having a pump bar 3503 with tapers. Fig.38 shows a pump chamber 3801 according to embodiment B. Fig.39 shows a common frame 3901 with regard to the valve levels: common frame for pump elements 3903 and common frame for pump elements 3905. One external drive 3907 is provided per side and pump group or pump elements. Reference numeral 3909 indicates spring elements of the pump elements. Fig. 39 shows a plan view. Fig. 40 shows a plan view 4001 according to a section through pump chambers. Reference numeral 4003 indicates first pump elements. Reference numeral 4005 indicates second pump elements. Reference numeral 4007 indicates static frame elements. Reference numeral 4009 indicates spring elements of the drive. Reference numeral 4011 indicates spring elements of the first pump elements 4003. Reference numeral 4013 indicates spring elements of the second pump elements 4005. R.412195 -. 41 -Fig. 41 shows a side view 4101 according to a section through pumping chambers. Reference numeral 4103 indicates a drive for first pumping elements. Reference numeral 4105 indicates a frame for the first pumping elements. Reference numeral 4107 indicates a frame for the second pumping elements. Reference numeral 4109 indicates a lower valve layer. Reference numeral 4111 indicates a lower frame layer. Reference numeral 4113 indicates a drive for the second pumping elements. Reference numeral 4115 indicates an upper frame layer. Reference numeral 4117 indicates an upper valve layer. Fig. 42 shows a side view 4201 according to a section through pumping chambers. Reference numeral 4203 indicates an electrostatic actuator. A common frame for the valve levels is provided, each with its own suspension for each pumping element. Each pump element has its own electrostatic actuator. Fig.Fig. 43 shows a plan view 4301 of a lower valve level. A common frame is provided for the valve levels, each with its own suspension for each pump element, as well as its own electrostatic drive for each pump element. Fig. 44 shows a plan view 4401 of a pump level. Reference number 4403 indicates slots in the upper layer. Reference number 4405 indicates first pump elements. Reference number 4407 indicates second pump elements. Fig. 45 shows the arrangement according to Fig. 44 in a further view 4501. Fig. 46 shows a plan view 4601 of a pump level. Reference number 4603 indicates first pump elements. Reference number 4605 indicates second pump elements. A common frame is provided for the valve levels, each with its own suspension for each pump element, as well as an electrostatic drive for each pump element.

Claims

R.412195 - 42 -Claims 1. MEMS loudspeaker (101), comprising: at least one pumping element (103) adjacent to a first (107) and a second volume (109) for pumping fluid, in particular air, from the first volume (107) into the second volume (109), at least one pumping element (105) adjacent to the first volume (107) and the second volume (109) for pumping fluid from the second volume (109) into the first volume (107), wherein the at least one pumping element (103) and the at least one pumping element (105) each have a pumping chamber (111, 113) within which an individually controllable piston (115, 117) is movably arranged, wherein the pumping chambers (111, 113) each have at least two passive valves (119, 121, 123, 125, 127, 129, 131, 133), each having a greater flow resistance in one flow direction than in the opposite flow direction, wherein the at least two valves (119, 121, 123, 125, 127, 129, 131,133) of the at least one pumping element (103) are arranged such that a flow resistance for a flow from the first volume (107) through the pumping chamber (111, 113) into the second volume (109) is smaller than vice versa, wherein the at least two valves (119, 121, 123, 125, 127, 129, 131, 133) of the at least one pumping element (105) are arranged such that a flow resistance for a flow from the second volume (109) through the pumping chamber (111, 113) into the first volume (107) is smaller than vice versa, so that upon a respective actuation of the pistons (115, 117), fluid from the first volume (107) through the pumping chamber (111, 113) of the at least one pumping element (103) into the second volume (109) and / or fluid from the second volume (109) can be pumped through the pumping chamber (111, 113) of the at least one pumping element (105) into the first volume (107) to generate an audio signal. R.412195 - 43 -2. The MEMS loudspeaker (101) according to claim 1, wherein at least one of the passive valves (119, 121, 123, 125, 127, 129, 131, 133) is a Tesla valve.

3. The MEMS loudspeaker (101) according to claim 1 or 2, wherein at least one of the pumping chambers (111, 113) has at least four passive valves (119, 121, 123, 125, 127, 129, 131, 133) arranged in pairs opposite one another.A method for generating an audio signal using the MEMS loudspeaker (101) according to one of the preceding claims, comprising the following steps: receiving (201) a request signal representing a request to generate an audio signal; determining (203) a respective drive signal for respectively driving the pistons (115, 117) based on the received request signal such that the audio signal is generated upon each driving of the pistons (115, 117) based on the respective drive signal; outputting (205) the determined drive signals to drive the pistons (115, 117) based on the corresponding drive signals.Method according to claim 4, wherein for a rising section of the audio signal to be generated, determining the drive signal for the piston (115, 117) of the at least one pumping element (103) comprises determining the time derivative of the audio signal to be generated with respect to the rising section and using the determined derivative as the amplitude of the drive signal.

6. Method according to claim 4 or 5, wherein for a rising section of the audio signal to be generated, determining the drive signal for the piston (115, 117) of the at least one pumping element (105) comprises specifying that an amplitude of the drive signal is zero.

7. Method according to one of claims 4 to 6, wherein for a falling section of the audio signal to be generated, determining the drive signal for the piston (115, 117) of the at least one pumping element (105) comprises determining. R.412195 - 44 -the time derivative of the audio signal to be generated with respect to the falling section and using an amount of the determined derivative as the amplitude of the drive signal.

8. The method according to one of claims 4 to 7, wherein for a falling section of the audio signal to be generated, determining the drive signal for the piston (115, 117) of the at least one inflation element (103) comprises specifying that an amplitude of the drive signal is zero.

9. The method according to one of claims 4 to 8, wherein for an audio signal to be generated which, upon generation, generates a constant sound pressure level not equal to zero Pa, the respective drive signals are determined such that, upon each drive of the piston (115, 117), the pistons (115, 117) are pumped up and down with equal force based on the respective drive signal.Method according to one of claims 4 to 9, wherein a frequency in the ultrasonic range is used as the drive frequency for at least one of the drive signals, in particular for all drive signals.

11. A device (1001) for generating an audio signal, which is configured to perform all steps of the method according to one of claims 4 to 10.

12. A system (1201) for generating an audio signal, comprising the MEMS loudspeaker (1203) according to one of claims 1 to 3 and the device (1001) according to claim 11.13.MEMS loudspeaker (301, 401, 501, 601, 701, 801), comprising:at least one pump element (303) adjacent to a first (305) and a second volume (307) in order to pump fluid, in particular air, from the first volume (305) into the second volume (307) or vice versa, wherein the at least one pump element (303) has a pump chamber (309) within which a controllable piston (311) is movably arranged, wherein the pump chamber (309) has at least two accesses (313, 315, 321, 323) for a respective access (313, 315, 321, 323) to the pump chamber (309). R.412195 - 45 -first volume (305) and from the second volume (307), at least one valve (317, 325) which can be controlled independently of the piston (311) in order to either close one or the other of the at least two accesses (313, 315, 321, 323) so that the respective other access (313, 315, 321, 323) is at least partially open, or to at least partially release the at least two accesses (313, 315, 321, 323) so that the at least two accesses (313, 315, 321, 323) are at least partially open, so that upon a respective control of the piston (311) and the valve (317, 325), fluid from one of the first and the second volume (307) through the corresponding access (313, 315, 321, 323) into the pumping chamber (309) and through the other access (313, 315, 321, 323) into the other volume (305) or vice versa, to generate an audio signal. 14.MEMS loudspeaker (301, 401, 501, 601, 701, 801) according to claim 13, wherein the pump chamber (309) is open on one side or closed on both sides with respect to a direction of movement of the piston (311).

15. MEMS loudspeaker (301, 401, 501, 601, 701, 801) according to claim 14, wherein the pumping chamber (309) closed on both sides is formed as a double pumping chamber having four or more accesses (313, 315, 321, 323), via which in pairs an access (313, 315, 321, 323) to the pumping chamber (309) is possible from the first volume (305) and from the second volume (307), wherein two individually controllable valves (317, 325) are provided to close either one or the other of the two accesses (313, 315, 321, 323) of the pairs, so that the respective other access (313, 315, 321, 323) of the couple is at least partially open. 16.MEMS loudspeaker (301, 401, 501, 601, 701, 801) according to one of claims 13 to 15, wherein the piston (311) is arranged to be laterally or vertically movable, so that a pumping movement of the piston (311) is lateral or vertical.

17. MEMS loudspeaker (301, 401, 501, 601, 701, 801) according to one of claims 13 to 16, wherein a closure part (319, 327) of the valve (317, 325) is arranged to be vertically movable, so that a vertical movement of the. R.412195 - 46 -The corresponding access (313, 315, 321, 323) can be closed by means of the closure part (319, 327).

18. A method for generating an audio signal using the MEMS loudspeaker (301, 401, 501, 601, 701, 801) according to one of claims 13 to 17, comprising the following steps: receiving (901) a request signal representing a request to generate an audio signal, determining (903) a respective drive signal for respectively driving the piston (311) and the at least one valve (317, 325) based on the received request signal such that the audio signal is generated upon respective driving of the piston (311) and the at least one valve (317, 325) based on the respective drive signal, outputting (905) the determined drive signals in order to drive the piston (311) and the at least one valve (317, 325) based on the corresponding drive signals. 19.Method according to claim 18, wherein a frequency in the ultrasonic range is used as the drive frequency for at least one of the drive signals, in particular for all drive signals.

20. Device (1101) for generating an audio signal, which is configured to carry out all steps of the method according to claim 18 or 19.

21. System (1301) for generating an audio signal, comprising the MEMS loudspeaker (1303) according to one of claims 13 to 17 and the device (1101) according to claim 20.

22. Computer program (1403) comprising instructions which, when the computer program (1403) is executed by a computer, cause the computer to carry out a method according to one of claims 4 to 10 and / or according to claim 18 or 19.

23. Machine-readable storage medium (1401) on which the computer program (1403) according to claim 22 is stored.

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