An electrostatic MEMS loudspeaker

Abstract

The utility model relates to a sound electric technology field provides a static type MEMS loudspeaker, sets up a pair of driving electrode on the both sides of sounding module symmetry, and driving electrode outputs alternating current drive signal, is equipped with sounding cavity in sounding module, is equipped with a plurality of sound holes on sounding cavity, is equipped with a plurality of first electrode and second electrode of setting up in pairs in sounding cavity, first electrode and second electrode parallelly arranged and mutually insulate, and first electrode inserts first direct current voltage, and second electrode inserts second direct current voltage, first electrode and / or second electrode vibrate along with alternating current drive signal, when through driving electrode and apply alternating current drive signal, first electrode and / or second electrode vibrate along with alternating current drive signal, thereby extrude the air in sounding cavity, produce air flow from sound hole, emit sound, the utility model loudspeaker has no pull in distance's limitation, and because a pair of driving electrode is shared by multiple groups of first electrode and second electrode, can improve the utilization of loudspeaker chip in plane.

Description

Technical Field

[0001] This utility model relates to the field of acoustic and electronic technology, specifically to an electrostatic MEMS loudspeaker. Background Technology

[0002] MEMS loudspeakers are manufactured based on semiconductor processing technology. Compared with traditional moving coil and moving iron loudspeakers, they have advantages such as small size, low power consumption, and good high-frequency response. Currently, they are mainly divided into two categories: MEMS piezoelectric loudspeakers and MEMS electrostatic loudspeakers.

[0003] like Figure 1 As shown, the MEMS piezoelectric loudspeaker utilizes the inverse piezoelectric effect of piezoelectric materials to convert electrical signals into mechanical vibrations that generate sound pressure. The magnitude of the sound pressure follows the formula: p∝S A and S represent the diaphragm area, and A represents the diaphragm displacement. However, when the size of the speaker chip is fixed, the diaphragm area S is a constant, and the displacement A needs to be increased to improve the sound pressure level. Commonly used aluminum nitride (AlN) has a low piezoelectric coefficient, requiring a high driving voltage; lead zirconate titanate (PZT) has a higher piezoelectric coefficient, but due to its large material nonlinearity, its total harmonic distortion (THD) is poor under large displacement.

[0004] like Figure 2 As shown, the MEMS electrostatic loudspeaker drives the diaphragm to move (in the X / Y directions) through the electrostatic force between the diaphragm and the electrode plate. The sound pressure formula is: p∝S_a H and S_a represent the effective area swept by the diaphragm, and H is the device height. The height can be used to reduce the displacement requirements. However, if... Figure 3 As shown, existing MEMS electrostatic loudspeakers suffer from the Pull-In effect, where the maximum diaphragm displacement is only 1 / 3 of the initial spacing, resulting in low in-plane area utilization (approximately 0.17) and a small effective area S_a, which affects sound pressure output.

[0005] Therefore, it is necessary to study a MEMS electrostatic loudspeaker that is not affected by the Pull-In effect to improve the boost output efficiency. Utility Model Content

[0006] Based on the above description, this utility model provides an electrostatic MEMS loudspeaker to solve the problem of poor sound pressure output caused by the Pull-In effect in MEMS electrostatic loudspeakers.

[0007] The technical solution of this utility model to solve the above-mentioned technical problems is as follows: an electrostatic MEMS loudspeaker, including a sound-generating module and a pair of driving electrodes symmetrically disposed on both sides of the sound-generating module, wherein the driving electrodes are used to output AC driving signals. The sound-generating module has a sound-generating cavity inside, and the sound-generating module has multiple sound holes that penetrate the sound-generating cavity. The sound-generating cavity is provided with a plurality of paired first electrodes and second electrodes. The first electrodes and second electrodes are arranged in parallel and are insulated from each other. The first electrode is connected to a first DC voltage and the second electrode is connected to a second DC voltage. The first electrode and / or the second electrode vibrate with the AC drive signal.

[0008] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: This invention provides an electrostatic MEMS loudspeaker. When an AC drive signal is applied through a pair of drive electrodes, the first and / or second electrodes vibrate in response to the AC drive signal, thereby compressing the air between the first and second electrodes and generating airflow that flows out from the sound hole, producing sound. The distance between the first and second electrodes is not limited by pull-in distance, improving the sound pressure output effect. Since multiple pairs of first and second electrodes within the sound-emitting cavity can share a single pair of drive electrodes, the utilization rate of the loudspeaker chip in the plane can be improved.

[0009] Based on the above technical solution, the present invention can be further improved as follows.

[0010] Furthermore, the sound-generating module includes an upper cover plate, a support frame, and a lower cover plate arranged sequentially. The upper cover plate, the support frame, and the lower cover plate cooperate with each other to form a sound-generating cavity, and a pair of driving electrodes are symmetrically arranged on both sides of the support frame. Each of the driving electrodes has a first comb tooth on one side facing the support frame, and the support frame has a second comb tooth on the outer side facing the driving electrode. The first comb tooth and the second comb tooth are staggered and insulated from each other to form a driving comb tooth structure.

[0011] Furthermore, a support spring is fixedly provided on the support frame, and the support spring is installed on the upper cover plate or the lower cover plate through an insulating structure.

[0012] Furthermore, the first electrode and the second electrode are arranged in parallel, with one end of the first electrode fixedly mounted on the support frame and the other end suspended in the air; the upper cover plate, the support frame, and the lower cover plate are insulated from each other, and the second electrode is mounted on the upper cover plate or the lower cover plate through an insulating structure.

[0013] Furthermore, the first electrode is a diaphragm, and the second electrode is a fixed electrode plate; or, The first electrode is a fixed plate, and the second electrode is a diaphragm.

[0014] Furthermore, the support frame includes an L-shaped first frame and a second frame, which are insulated from each other, and a support spring is fixedly provided on the first frame and the second frame respectively. The support spring is connected to the upper cover plate or the lower cover plate through an insulating structure. One end of the first electrode is mounted on the first frame, the other end of the first electrode is suspended, and the second comb tooth on the first frame cooperates with one of the first comb teeth; One end of the second electrode is mounted on the second frame, and the other end of the second electrode is suspended in the air. The second comb tooth on the second frame cooperates with another first comb tooth. The first electrode and the second electrode are arranged in parallel, and both are diaphragms.

[0015] Furthermore, the insulating structure is an insulating ring.

[0016] Furthermore, a gap is provided between the suspended end of the first electrode and the inner wall of the sound-emitting cavity, and a gap is provided between the suspended end of the second electrode and the inner wall of the sound-emitting cavity.

[0017] Furthermore, a plurality of the acoustic holes are disposed on the upper cover plate and / or the lower cover plate, and the acoustic holes are provided between adjacent first electrodes and second electrodes. Attached Figure Description

[0018] Figure 1 A schematic diagram of the existing MEMS piezoelectric loudspeaker principle; Figure 2 This is a schematic diagram of the principle of an existing electrostatic loudspeaker; Figure 3 A schematic diagram of the pull-in effect in an existing electrostatic loudspeaker; Figure 4 A top-view cross-sectional structural diagram of an electrostatic MEMS loudspeaker provided for a certain embodiment of this utility model; Figure 5 A schematic diagram of the front-view cross-sectional structure of an electrostatic MEMS loudspeaker provided in a certain embodiment of the present invention; Figure 6 A schematic diagram of the electrode mounting structure in an electrostatic MEMS loudspeaker, provided as another embodiment of the present invention; Figure 7 A schematic diagram of the top-view cross-sectional structure of an electrostatic MEMS loudspeaker provided for another embodiment of this utility model; Figure 8 This is a schematic diagram of the front-view cross-sectional structure of an electrostatic MEMS loudspeaker, provided as another embodiment of the present invention.

[0019] The attached diagram lists the components represented by each number as follows: 1. Driving electrode; 1a. First comb tooth; 2. Sound-generating module; 201. Upper cover plate; 202. Support frame; 202a. Second comb tooth; 2021. First frame; 2022. Second frame; 203. Lower cover plate; 3. First electrode; 4. Second electrode; 5. Insulating ring; 6. Support spring; 7. Sound hole. Detailed Implementation

[0020] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0022] It is understood that spatial relation terms such as "below," "under," "below," "below," "above," "over," etc., can be used here to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as "below" or "under" or "below" of other elements or features will be oriented "over" of other elements or features. Therefore, the exemplary terms "below" and "under" can include both upper and lower orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0023] It should be noted that when one element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediary element. In the following embodiments, "connection" should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have the transmission of electrical signals or data between them.

[0024] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0025] like Figure 1 The diagram shows the principle of a MEMS piezoelectric loudspeaker. The core principle of a MEMS piezoelectric loudspeaker is to utilize the inverse piezoelectric effect of piezoelectric materials to convert alternating current signals into mechanical vibrations, thereby generating sound pressure. The magnitude of the sound pressure generated by the device is proportional to the speed at which the diaphragm moves and pushes the air, i.e.:

[0026] Where S is the diaphragm area and A is the diaphragm displacement.

[0027] However, Figure 1 In this scheme, with a fixed chip size, the diaphragm area S is almost constant. To achieve high sound pressure level output, the diaphragm displacement amplitude A must be increased. Piezoelectric materials are typically lead zirconate titanate (PZT) and aluminum nitride (AlN). AlN has a low piezoelectric coefficient, requiring a higher driving voltage to generate a large diaphragm displacement. PZT has a higher piezoelectric coefficient than AlN, but its material nonlinearity is relatively large, resulting in poor THD of the device under large displacement.

[0028] Therefore, to address the issue that piezoelectric devices require a large diaphragm displacement to generate sufficient sound pressure level, a vertical diaphragm structure was designed. The vertical diaphragm and electrodes were fabricated using MEMS technology, with the diaphragm positioned between two driving electrodes. For example... Figure 2 As shown in the schematic diagram, a voltage is applied between the diaphragm and the two driving plates. Under the action of electrostatic force, the diaphragm moves. Unlike the diaphragm in a piezoelectric loudspeaker, which moves in the Z direction, the diaphragm in an electrostatic loudspeaker moves in the X / Y directions. The resulting sound pressure is:

[0029] in, H represents the effective area swept by the diaphragm motion in the plane, and H is the height of the device. H is determined by the processing capability. This scheme can utilize the height direction of the device to provide the amount of air to push the diaphragm, thereby reducing the requirements for diaphragm displacement.

[0030] However, when a loudspeaker is electrostatically driven, a pull-in effect occurs, meaning that if the diaphragm displacement exceeds a certain value, the diaphragm and backplate will stick together, leading to device failure. Typically, the maximum diaphragm displacement... , The distance between the diaphragm and the fixed electrode plate results in a pull-in effect, which restricts the diaphragm's displacement in the XY plane, thus leading to a lower effective area. .like Figure 3 As shown, the width occupied by a single Cell (basic speaker unit):

[0031] Assuming the diaphragm maintains a safe distance from adjacent diaphragms when it reaches its maximum displacement. The thickness of the diaphragm is ,and: , The in-plane area utilization rate (Drive structure not considered) satisfies: .

[0032] To overcome the limitations of pull-in distance in electrostatic MEMS loudspeakers and improve the in-plane area utilization of the basic sound-generating unit, such as... Figures 4-8 As shown, this embodiment of the present invention provides an electrostatic MEMS loudspeaker, which includes a sound-generating module 2 and a pair of driving electrodes 1 symmetrically disposed on both sides of the sound-generating module 2. The driving electrodes 1 are used to output AC driving signals.

[0033] The sound-generating module 2 has a sound-generating cavity inside, and the sound-generating module 2 has a plurality of sound holes 7 that penetrate the sound-generating cavity.

[0034] The sound-generating cavity is provided with a plurality of paired first electrodes 3 and second electrodes 4. The first electrodes 3 and second electrodes 4 are arranged in parallel and are insulated from each other. The first electrode 3 is connected to a first DC voltage and the second electrode 4 is connected to a second DC voltage.

[0035] Both the first electrode 3 and the second electrode 4 can be implemented using a movable diaphragm, or either the first electrode 3 or the second electrode 4 can be implemented using a movable diaphragm while the other is implemented using a fixed electrode (e.g., a fixed plate).

[0036] It is understandable that an AC drive signal is output to a pair of drive electrodes 1 on both sides of the sound-generating module 2. Based on the electrostatic drive principle, an electrostatic force is generated by applying voltage to the diaphragm and the electrode plate (or between two adjacent movable diaphragms), which drives the diaphragm to move in the X / Y plane (different from the Z-direction vibration of the piezoelectric speaker), and compresses the air to be output from the sound hole 7, thereby generating sound pressure.

[0037] More specifically, when both the first electrode 3 and the second electrode 4 are movable diaphragms, the first DC voltage and the second DC voltage are the same. Two adjacent diaphragms form a sound-generating unit. When adjacent diaphragms move, they compress the air between them, generating airflow that flows out through the sound hole 7. Multiple diaphragms share a common driving structure, further improving the effective area utilization rate and avoiding the pull-in effect.

[0038] When one of the first electrode 3 and the second electrode 4 uses a movable diaphragm and the other uses a fixed electrode, the first DC voltage and the second DC voltage are different. For example, the first DC voltage can be a positive high voltage DC (e.g., +30V), and the second DC voltage can be grounded. The diaphragm can vibrate with the AC drive signal. Multiple diaphragms are arranged inside the same frame, and each diaphragm and the adjacent fixed electrode plate form a sound-generating unit. When the diaphragm moves, it compresses the air between itself and the fixed electrode plate, generating airflow that flows out from the sound hole 7; multiple diaphragms share a drive structure, and the distance between the diaphragm and the electrode plate is not limited by Pull-In.

[0039] Now Figure 4 as well as Figure 5 Taking the structure as an example, one possible implementation method will be described.

[0040] Combination Figure 4 as well as Figure 5 As shown, the sound-generating module 2 includes an upper cover plate 201, a support frame 202, and a lower cover plate 203 arranged sequentially. The upper cover plate 201, support frame 202, and lower cover plate 203 are made of silicon-doped material and are integrally formed by thin-film deposition or bulk silicon deposition. The three components cooperate to form a sound-generating cavity. A pair of driving electrodes 1 are symmetrically arranged on both sides of the support frame 202 to provide AC driving signals. The support frame 202 can be rectangular, arc-shaped, or other shapes. This embodiment of the invention uses a rectangular shape as an example.

[0041] Combination Figure 4 and Figure 5 As shown, this embodiment uses a diaphragm as the first electrode 3 and a fixed electrode plate as the second electrode 4 as an example. The upper end of the first electrode 3 (diaphragm) is electrically connected to the support frame 202, and the lower end of the second electrode 4 (fixed electrode plate) passes through the lower cover plate 203 and is grounded.

[0042] Each driving electrode 1 has a first comb tooth 1a on its side facing the support frame 202, and a second comb tooth 202a on the outer side of the support frame 202 facing the driving electrode 1. The first comb tooth 1a and the second comb tooth 202a are staggered and insulated from each other to form a driving comb tooth structure. The first comb tooth 1a and the second comb tooth 202a cooperate to transmit the driving force to the diaphragm through the frame, so that the diaphragm movement is no longer limited by the pull-in effect of adjacent plates. The staggered arrangement of the first comb tooth 1a and the second comb tooth 202a increases the contact area between the driving electrode 1 and the sensing structure, improves the transmission efficiency of electrostatic driving force, and enables the sound-generating module 2 to more accurately sense changes in AC driving voltage, reduce sound distortion, and improve the quality of output audio. Multiple diaphragms are set within the support frame 202 and share a pair of driving structures, which reduces the chip area occupied by the driving part inside the speaker, improves the in-plane area utilization of the chip, optimizes acoustic performance, and can significantly increase the output sound pressure level under the same chip size, or reduce the chip size under the same sound pressure level requirement, adapting to miniaturized application scenarios.

[0043] A support spring 6 is fixedly provided on the support frame 202, and the support spring 6 is installed on the upper cover plate 201 or the lower cover plate 203 through an insulating structure.

[0044] The support spring 6 provides a swingable support for the support frame 202, while guiding the support frame 202 and the diaphragm to move in a specific direction (such as the vibration direction corresponding to the driving force) under the action of the AC drive signal. This limits unnecessary lateral offset or swaying, ensuring that the driving force can be efficiently transmitted to the electrodes (first electrode 3 and second electrode 4) in the sound-generating module 2, guaranteeing the directionality and consistency of vibration. Simultaneously, the support spring 6 utilizes its own elastic properties to buffer the vibration of the support frame 202, reducing stress impact during vibration and protecting precision components such as the comb structure. Furthermore, after the driving force disappears, it can drive the support frame 202 back to its initial position, ensuring the reciprocating nature and stability of the vibration, which helps improve the acoustic performance of the speaker (such as reducing distortion). The support spring 6 also enhances the overall structural stability of the support frame 202, preventing accidental contact or collision between the support frame 202 and other components (such as the drive electrode 1) due to vibration or minor external disturbances, thereby ensuring the reliability and safety of the device operation.

[0045] The first electrode 3 and the second electrode 4 are arranged in parallel, and the arrangement direction of the first electrode 3 and the second electrode 4 is consistent with the arrangement direction of the pair of driving electrodes 1. One end of the first electrode 3 is fixedly mounted on the support frame 202, and the other end of the first electrode 3 is suspended. The upper cover plate 201, the support frame 202, and the lower cover plate 203 are insulated from each other, and the second electrode 4 is mounted on the upper cover plate 201 or the lower cover plate 203 through an insulating structure.

[0046] In this embodiment, the insulating structure is an insulating ring 5.

[0047] For example Figure 6 As shown, multiple insulating rings 5 ​​are respectively provided on the upper cover plate 201 and the lower cover plate 203. The insulating ring 5 structure is manufactured on the upper cover plate 201 and the lower cover plate 203 to form multiple electrically independent regions. The conductive material in the middle of the insulating ring 5 can be connected to the support frame 202 or fixed electrodes according to actual needs. For example Figure 6 As shown, the diaphragm (first electrode 3) is mounted on the inner wall of the support frame 202. The support frame 202 is connected to the central area of ​​the insulating ring 5 of the upper cover plate 201 via the support spring 6, achieving electrical isolation between the diaphragm (first electrode 3) and the upper cover plate 201. The fixed electrode (second electrode 4) is mounted on the lower cover plate 203 via the insulating ring 5 on the lower cover plate 203, achieving electrical isolation between the fixed electrode (second electrode 4) and the lower cover plate 203.

[0048] Let the gap between the suspended end of the first electrode 3 and the lower cover plate 203 and the gap between the suspended end of the second electrode 4 and the upper cover plate 201 be d_gap. In order to avoid acoustic leakage, the value of gap d_gap is set to be less than 10um.

[0049] Multiple sound holes 7 are distributed on the upper cover plate 201 and the lower cover plate 203, with a sound hole 7 provided between each pair of adjacent first electrodes 3 and second electrodes 4. Sound holes 7 are also provided between the outermost first electrode 3 and the sound-emitting cavity, and between the outermost second electrode 4 and the sound-emitting cavity. The air compressed by the diaphragm movement is transmitted to the outside through the air channels (sound holes 7) in the upper cover plate 201 and the lower cover plate 203, achieving sound pressure output.

[0050] Now Figure 7 as well as Figure 8 Using the structure as an example, another possible implementation will be described. Figure 7 as well as Figure 8 Compared to the embodiments Figure 4 as well as Figure 5 The main difference in the embodiment lies in the setting of the sound-generating module 2.

[0051] Combination Figure 7 and Figure 8 As shown, in this embodiment, the support frame 202 adopts a split structure, and both the first electrode 3 and the second electrode 4 are diaphragms. Specifically, as... Figure 7 and Figure 8As shown, the upper cover plate 201 and the lower cover plate 203 are respectively connected to the support frame 202 through an insulating structure. The support frame 202 includes an L-shaped first frame 2021 and a second frame 2022, which cooperate to form the support frame 202. An electrical gap is left between the first frame 2021 and the second frame 2022, and they are insulated from each other. Support springs 6 are respectively fixed on the first frame 2021 and the second frame 2022, and the support springs 6 are connected to the upper cover plate 201 or the lower cover plate 203 through an insulating structure.

[0052] One end of the first electrode 3 is mounted on the first frame 2021, and the other end of the first electrode 3 is suspended. The second comb tooth 202a on the first frame 2021 cooperates with one of the first comb teeth 1a. The first electrode 3 and the first frame 2021 can be integrally formed by thin film deposition process or bulk silicon process. One end of the second electrode 4 is mounted on the second frame 2022, and the other end of the second electrode 4 is suspended. The second comb tooth 202a on the second frame 2022 cooperates with another first comb tooth 1a. The second electrode 4 and the second frame 2022 can be integrally formed by thin film deposition process or bulk silicon process. The first electrode 3 and the second electrode 4 are arranged in parallel, and both are diaphragms.

[0053] When an AC driving voltage is applied through a pair of driving electrodes 1, two adjacent diaphragms (first electrode 3 and second electrode 4) form a sound-generating unit. When the adjacent diaphragms move, they compress the air between them, generating flow and flowing out through the sound hole 7. The multiple diaphragm pairs arranged on the first frame 2021 and the second frame 2022 share a common driving structure, further improving the effective area utilization and avoiding the influence of the pull-in effect.

[0054] In this embodiment, the width occupied by a single sound-emitting unit Cell , Assumption Then the area utilization rate within the plane is: .

[0055] By comparison, it can be seen that the electrostatic MEMS loudspeaker provided by this utility model embodiment has an effectively improved in-plane area utilization rate compared with the traditional electrostatic loudspeaker.

[0056] The technical solution of this utility model embodiment increases the theoretical value of the effective area utilization rate of the electrostatic MEMS speaker chip from 16.6% to 29%, which can significantly improve the output sound pressure level under the same chip size, or reduce the chip size under the same output sound pressure level.

[0057] This invention provides an electrostatic MEMS loudspeaker. The sound-emitting cavity contains multiple pairs of first electrodes 3 and second electrodes 4, with corresponding sound holes 7 between adjacent electrodes. When an AC drive signal is applied through a pair of drive electrodes 1, the first electrodes 3 and / or the second electrodes 4 vibrate in response to the AC drive signal, thereby compressing the air between the first electrodes 3 and the second electrodes 4. This generates airflow that exits through the sound holes, producing sound. The distance between the first electrodes 3 and the second electrodes 4 is not limited by pull-in distance, improving sound pressure output efficiency. Since the multiple pairs of first electrodes 3 and second electrodes 4 within the sound-emitting cavity can share a pair of drive electrodes 1, the coordinated vibration of multiple sets of electrodes increases the effective sound-emitting area, improves the utilization rate of the loudspeaker chip in the plane, and, combined with the reasonable layout of the sound holes 7, reduces sound wave propagation loss, thus improving sound pressure output efficiency.

[0058] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An electrostatic MEMS loudspeaker, characterized by, It includes a sound-generating module (2) and a pair of driving electrodes (1) symmetrically arranged on both sides of the sound-generating module (2), the driving electrodes (1) being used to output AC driving signals; The sound-generating module (2) is provided with a sound-generating cavity, and the sound-generating module (2) is provided with a plurality of sound holes (7) penetrating the sound-generating cavity. The sound-generating cavity is provided with a plurality of paired first electrodes (3) and second electrodes (4). The first electrodes (3) and second electrodes (4) are arranged in parallel and are insulated from each other. The first electrode (3) is connected to a first DC voltage and the second electrode (4) is connected to a second DC voltage. The first electrode (3) and / or the second electrode (4) vibrate with the AC drive signal.

2. The electrostatic MEMS loudspeaker of claim 1, wherein, The sound-generating module (2) includes an upper cover plate (201), a support frame (202) and a lower cover plate (203) arranged sequentially. The upper cover plate (201), the support frame (202) and the lower cover plate (203) cooperate with each other to form a sound-generating cavity. A pair of driving electrodes (1) are symmetrically arranged on both sides of the support frame (202). Each of the driving electrodes (1) has a first comb tooth (1a) on one side facing the support frame (202), and the support frame (202) has a second comb tooth (202a) on the outer side facing the driving electrode (1). The first comb tooth (1a) and the second comb tooth (202a) are staggered and insulated from each other to form a driving comb tooth structure.

3. An electrostatic MEMS loudspeaker according to claim 2, wherein, A support spring (6) is fixedly provided on the support frame (202), and the support spring (6) is installed on the upper cover plate (201) or the lower cover plate (203) through an insulating structure.

4. An electrostatic MEMS loudspeaker according to claim 2 or 3, wherein, The first electrode (3) and the second electrode (4) are arranged in parallel. One end of the first electrode (3) is fixed on the support frame (202), and the other end of the first electrode (3) is suspended. The upper cover plate (201), the support frame (202), and the lower cover plate (203) are insulated from each other. The second electrode (4) is installed on the upper cover plate (201) or the lower cover plate (203) through an insulating structure.

5. An electrostatic MEMS loudspeaker according to claim 4, wherein, The first electrode (3) is a diaphragm, and the second electrode (4) is a fixed electrode plate; or, The first electrode (3) is a fixed electrode plate, and the second electrode (4) is a diaphragm.

6. The electrostatic MEMS loudspeaker of claim 2, wherein, The support frame (202) includes an L-shaped first frame (2021) and a second frame (2022), which are insulated from each other. Support springs (6) are fixedly provided on the first frame (2021) and the second frame (2022), and the support springs (6) are connected to the upper cover plate (201) or the lower cover plate (203) through an insulating structure. One end of the first electrode (3) is mounted on the first frame (2021), the other end of the first electrode (3) is suspended, and the second comb tooth (202a) on the first frame (2021) cooperates with one of the first comb teeth (1a); One end of the second electrode (4) is mounted on the second frame (2022), and the other end of the second electrode (4) is suspended in the air. The second comb tooth (202a) on the second frame (2022) is engaged with another first comb tooth (1a). The first electrode (3) and the second electrode (4) are arranged in parallel and both are diaphragms.

7. An electrostatic MEMS loudspeaker according to claim 3 or 6, wherein, The insulating structure is an insulating ring (5).

8. An electrostatic MEMS loudspeaker according to any one of claims 2, 3, 5, 6, wherein, A gap is provided between the suspended end of the first electrode (3) and the inner wall of the sound-emitting cavity, and a gap is provided between the suspended end of the second electrode (4) and the inner wall of the sound-emitting cavity.

9. The electrostatic MEMS loudspeaker of claim 1, wherein, Multiple acoustic holes (7) are provided on the upper cover plate (201) and / or the lower cover plate (203), and the acoustic holes (7) are provided between adjacent first electrodes (3) and second electrodes (4).

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