CN117729501A

CN117729501A - MEMS speaker and electronic equipment with overlapping structure

Info

Publication number: CN117729501A
Application number: CN202211147486.2A
Authority: CN
Inventors: 庞慰; 张孟伦; 刘承泽
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2022-09-19
Filing date: 2022-09-19
Publication date: 2024-03-19

Abstract

The invention relates to a MEMS speaker and an electronic device. The MEMS speaker includes: at least one vibrating diaphragm, one end of which is fixed and the other end of which is provided with or has a space for vibration; at least one overlapping structure covers the corresponding space for vibration so as to span the corresponding space for vibration, and the overlapping structure and the space for vibration covered thereby are at a distance in the vibration direction. The invention also relates to an electronic device.

Description

MEMS speaker and electronic equipment with overlapping structure

Technical Field

Embodiments of the present invention relate to the field of semiconductors, and more particularly, to a MEMS speaker with an overlapping structure, and an electronic device.

Background

Microelectromechanical systems (Micro-electro Mechanical Systems, MEMS for short) refer to electromechanical systems with internal structures on the order of micrometers or even nanometers. The micro-electromechanical system has the characteristics of small volume, light weight, low power consumption, high reliability, high sensitivity, easy integration and the like.

MEMS speakers are miniature transducers that convert electrical signals into acoustic signals, whose core components (e.g., actuator/driver, diaphragm, thermo-acoustic membrane, etc.) are fabricated on semiconductor materials using MEMS technology. MEMS speakers can be classified into piezoelectric, electrodynamic, electrostatic, and thermo-acoustic types according to the operating principle.

The piezoelectric MEMS speaker operates on the principle that a piezoelectric thin film is used as an active element, and is deformed when a voltage is applied. This mechanical deflection displaces the surrounding air and creates sound waves. One of the main advantages of piezoelectric MEMS speakers is its compatibility with silicon technology, which means that it can be produced at low cost on a large scale and in very small dimensions. In addition to size, piezoelectric MEMS speakers also have very low power and excellent audio quality. The piezoelectric MEMS speaker can also be built on the same PCB substrate as the amplifier, thus saving circuit board space.

Cantilever-beam diaphragms are diaphragm structures commonly used in piezoelectric MEMS speakers. The cantilever beam diaphragm structure with the slit is shown in fig. 1, and the structure comprises two cantilever beam diaphragms arranged oppositely, wherein each cantilever beam diaphragm comprises a support member 100 and a diaphragm 200, one end of the diaphragm is fixedly connected with the upper part of the support member 100, and the other end of the diaphragm is a free end. A slit 300 is present between the free ends of the two cantilever diaphragms. Although the viscous force of the interaction of the slit 300 and air may reduce the leakage of sound to some extent, the wider the slit is, the more serious the acoustic short circuit is. In addition, during the manufacturing or use of the diaphragm 200, stresses (the size of the stresses is represented by the color shade) as shown in fig. 2 are generated inside the diaphragm, and the stresses may cause the cantilever diaphragm to warp, thereby causing the slit 300 between the two diaphragms 200 to become large, and causing an acoustic short circuit. The acoustic short circuit phenomenon may deteriorate the low frequency response of the speaker.

Another cantilever beam diaphragm structure with a slit is shown in fig. 1A, and the structure includes a diaphragm 200 and left and right support members 100, where the left end of the diaphragm 200 is fixedly connected to the upper portion of the left support member 100, and the right end of the diaphragm 200 is a free end, so that the diaphragm 200 and the left support member 100 together form a single cantilever beam diaphragm. The existence of the slit 300 between the free end of the cantilever diaphragm and the right-hand support 100 also reduces leakage of sound to some extent due to the viscous force of the interaction of the slit 300 and air, but the wider the slit, the more serious the acoustic short-circuit. In addition, during the manufacturing or use of the diaphragm 200, stresses (not shown) may be generated therein, which may cause the cantilever diaphragm to warp, thereby causing the slit 300 between the diaphragm 200 and the right support 100 to become large, causing an acoustic short circuit, and resulting in deterioration of the low frequency response of the speaker.

Disclosure of Invention

The present invention has been made to alleviate or solve at least one of the above-mentioned problems of the prior art.

According to an aspect of an embodiment of the present invention, there is provided a MEMS speaker including:

at least one vibrating diaphragm, one end of which is fixed and the other end of which is provided with or has a space for vibration;

at least one overlapping structure covers the corresponding space for vibration so as to span the corresponding space for vibration, and the overlapping structure and the space for vibration covered thereby are at a distance in the vibration direction.

Embodiments of the invention also relate to an electronic device comprising the MEMS speaker described above.

Drawings

These and other features and advantages of the various embodiments of the disclosed invention will be better understood from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate like parts throughout the several views, and wherein:

FIG. 1 is a schematic perspective view of a plurality of cantilever diaphragms according to the prior art;

FIG. 1A is a schematic perspective view of a single cantilever diaphragm according to the prior art;

FIG. 2 is a stress cloud of the cantilever diaphragm of FIG. 1, wherein the magnitude of the stress is represented by the shade of color;

fig. 3 is a schematic perspective view of a MEMS speaker according to an exemplary embodiment of the present invention;

FIG. 3A is a schematic cross-sectional view of the MEMS speaker of FIG. 3;

FIGS. 4 and 5 are different layer structures of a diaphragm according to an exemplary embodiment of the present invention;

FIG. 6 is a simulation effect diagram showing the frequency sound pressure level curves of the diaphragms of FIGS. 1 and 3, wherein the dotted line represents the frequency sound pressure level curve of the cantilever diaphragm of FIG. 1 and the solid line represents the frequency sound pressure level curve of the diaphragm of FIG. 3;

FIG. 6A is a simulation effect diagram showing the frequency sound pressure level curves of the diaphragms of FIGS. 1A and 15, and the result is that the sound pressure level at 2kHz is normalized, wherein the broken line represents the normalized frequency sound pressure level curve of the cantilever beam diaphragm of FIG. 1A, and the solid line represents the normalized frequency sound pressure level curve of the diaphragm of FIG. 15;

fig. 7 and 8 are schematic cross-sectional views of MEMS speakers according to different exemplary embodiments of the present invention, showing different placement positions of the overlapping structures;

FIGS. 9-11 are schematic cross-sectional views of MEMS speakers according to various exemplary embodiments of the invention, illustrating a leveling scheme for the resonant frequency;

fig. 12 is a schematic perspective view of a MEMS speaker according to another exemplary embodiment of the present invention, illustrating a leveling scheme of a vibration mode;

fig. 13 and 14 are perspective views of MEMS speakers according to various exemplary embodiments of the present invention, showing triangular diaphragms;

fig. 15 and 16 are schematic cross-sectional views of MEMS speakers according to various exemplary embodiments of the present invention, illustrating a scheme of providing an overlap structure between a diaphragm and a support;

FIGS. 17-22 are schematic cross-sectional views of MEMS speakers according to various exemplary embodiments of the invention, showing the arrangement in which the overlay is in contact with the diaphragm (including components thereon) or the support (including components thereon);

fig. 23 is a schematic cross-sectional view of a MEMS speaker according to another embodiment of the present invention, showing a solution in which the space for vibration is an opening;

fig. 24 and 24A are schematic cross-sectional views of MEMS speakers according to various exemplary embodiments of the present invention;

fig. 25 and 25A are schematic cross-sectional views of MEMS speakers according to further different exemplary embodiments of the present invention.

Detailed Description

The technical scheme of the invention is further specifically described below through examples and with reference to the accompanying drawings. In the specification, the same or similar reference numerals denote the same or similar components. The following description of embodiments of the present invention with reference to the accompanying drawings is intended to illustrate the general inventive concept and should not be taken as limiting the invention. Some, but not all embodiments of the invention. All other embodiments, which are derived by a person skilled in the art based on the embodiments of the invention, fall within the scope of protection of the invention.

Reference numerals in the present invention are explained as follows:

1: a support layer for forming a support hereinafter, the material being, for example, silicon or the like;

2: a stop layer, for example, silicon oxide, as a stop layer for etching;

3: an elastic layer for changing the neutral plane of the diaphragm, the material being, for example, silicon or the like;

4: an electrode made of a metal such as molybdenum, platinum, gold, etc.;

5: the piezoelectric layer is made of, for example, aluminum nitride (AlN), scandium-doped aluminum nitride (AlScN), lead zirconate titanate (Pb (Tix, zr) _1-x )O ₃ Abbreviated as PZT), zinc oxide (formula ZnO), lithium niobate (LiNbO) ₃ ) Etc.

6. 12: an overlapping structure for covering the corresponding space for vibration so as to cross the corresponding space for vibration (see description below), the material being a thin film material such as silicon, silicon nitride, aluminum oxide, or the like;

10. 11: the vibrating diaphragm drives air to vibrate through self vibration to make sound, and the vibrating diaphragm can adopt a structure shown in fig. 3 or 4 or other structures;

13: a space for vibration, such as a slit or a hole, for providing a condition for vibrating the diaphragm or for eliminating the constraint of the end portion of the diaphragm and freely vibrating the diaphragm;

20: the support member is used for supporting the diaphragm, and the material is, for example, silicon or the like, and can be formed by etching the support layer.

In a cantilever-beam diaphragm structure with slits, such as in fig. 1, the stress in the diaphragms may cause deformation of the diaphragms, warpage, and thus the slits between the two diaphragms become large. Part of sound waves (particularly low-frequency parts) on one side of the diaphragm are diffracted to the other side of the diaphragm through the enlarged slit, so that the sound waves cancel each other, an acoustic short circuit phenomenon occurs, and the low-frequency response of the loudspeaker is deteriorated. The main idea of the invention is to arrange an overlapping structure on the vibrating diaphragm, cover the space for vibration by using the overlapping structure in a mode of crossing the space for vibration (such as a slit), shield the leakage channel of sound waves, reduce the sound leakage brought by the space for vibration, weaken the sound short-circuit effect and improve the low-frequency response of the loudspeaker.

Fig. 3 is a schematic perspective view of a MEMS speaker according to an exemplary embodiment of the present invention. Fig. 3A is a schematic cross-sectional view of the MEMS speaker of fig. 3. As shown in fig. 3 and 3A, the MEMS speaker includes:

at least one diaphragm 10, one end of the diaphragm 10 is fixed and the other end is provided with a diaphragm space 13;

at least one of the overlapping structures 12 covers the corresponding space for vibration 13 so as to span the corresponding space for vibration 13, and the overlapping structure 12 and the space for vibration 13 covered therewith are located at a distance in the vibration direction.

In the embodiment shown in fig. 3 and 3A, the number of the diaphragms 10 is two, including the diaphragms 10 and the diaphragms 11. The diaphragm 10 and the diaphragm 11 may be identical in shape, size, material, structure, and the like, or may be different. Alternatively, in the embodiment shown in fig. 3 and 3A, the diaphragm 10 and the diaphragm 11 are identical in shape, size, material, structure, and the like.

Alternatively, the diaphragm 10 and/or the diaphragm 11 may employ a bimorph (bimorph) structure as shown in fig. 4, which includes two piezoelectric layers 5 and three electrodes 4 respectively located on outer surfaces of the two piezoelectric layers 5 and between the two piezoelectric layers 5. Alternatively, the diaphragm 10 and/or the diaphragm 11 may employ a unimorph (unimorph) structure as shown in fig. 5, which includes the elastic layer 3, the electrode 4, the piezoelectric layer 5, and the other electrode 4 disposed in this order from bottom to top.

In the embodiment shown in fig. 3 and 3A, one end of the diaphragm 10 or the diaphragm 11 is fixed to the upper end of the corresponding support 20, which is a fixed end. The other end of the diaphragm 10 or the diaphragm 11 is a free end. The free ends of the diaphragm 10 and the diaphragm 11 are opposite to each other, adjacent to each other, and the end surfaces are parallel or substantially parallel to each other. The slit between the diaphragm 10 and the free end of the diaphragm 11 is a space 13 for vibration. The existence of the space 13 for vibration allows the free ends of the diaphragm 10 and the diaphragm 11 to be free from constraint and to vibrate in the vertical direction.

In the embodiment shown in fig. 3 and 3A, the overlay 12 is fixedly connected to the diaphragm 10. The overlap structure 12 includes a vertical portion extending upward from a connection point with the diaphragm 10, and a horizontal portion extending rightward from an upper end of the vertical portion. Wherein the horizontal portion spans the space 13 for vibration and covers or shields the space 13 for vibration in a vertical direction (the vertical direction in the figure substantially corresponds to the vibration direction of the diaphragm). The vertical portion makes the overlapping structure 12 a distance in the vertical direction from the space for vibration. In an alternative embodiment, the distance of the overlap structure 12 from the space for vibration in the vertical direction is not greater than the width of the slit. Further, the horizontal portion of the overlap structure 12 may be any portion that overlaps the diaphragm 11 in the vertical direction. Thus, the overlapping structure 12 can block the leakage path of the sound wave, and reduce the sound leakage caused by the space 13 for vibration.

Alternatively, in the embodiment shown in fig. 3 and 3A, the dimension of the overlapping structure 12 in the slit length direction is equal to the slit length or greater than the slit length, so that the slit can be completely covered, and sound leakage can be prevented better.

Fig. 6 shows the frequency sound pressure level curves of the diaphragms of fig. 1 and 3, wherein the dashed lines represent the frequency sound pressure level curves of the cantilever diaphragm of fig. 1, and the solid lines represent the frequency sound pressure level curves of the diaphragm of fig. 3. As shown in fig. 6, the diaphragm in fig. 1, which is not provided with an overlapping structure, has a sound pressure level that varies significantly with frequency, and the sound pressure level corresponding to a low frequency is low, so that the low frequency response is poor. The diaphragm with the overlapping structure in fig. 3 has the sound pressure level stabilized at a larger value when the frequency is changed, and has good response effect at each frequency, and particularly, the low-frequency response effect has obvious advantages compared with the diaphragm in fig. 1.

Fig. 7 and 8 are schematic cross-sectional views of MEMS speakers according to different exemplary embodiments of the present invention, showing different placement positions of the overlapping structures. As shown in fig. 7, the overlap structure 12 is provided on the upper side of the diaphragm. As shown in fig. 8, the overlap structure 12 is provided on the underside of the diaphragm. As shown in fig. 9, the number of the overlapping structures 12 is two, and are provided on both sides of the diaphragm, respectively. The above-mentioned setting positions are all optional.

In the embodiment shown in fig. 3, if the diaphragm 10 and the diaphragm 11 are identical, the additional superposition structure on the diaphragm 10 may cause the resonant frequencies of the diaphragm 10 and the diaphragm 11 to be different, so that the two diaphragms have different vibration conditions at the same frequency, and the gap between the two diaphragms is increased, which is not beneficial to reducing sound leakage. In this regard, the resonant frequencies of the two diaphragms may be "leveled".

Fig. 9-11 are schematic cross-sectional views of MEMS speakers according to various exemplary embodiments of the invention, showing a leveling scheme for the resonant frequency.

Alternatively, as shown in fig. 9, an overlapping structure may be provided on both the diaphragm 10 and the diaphragm 11, wherein the overlapping structure 12 is fixed to the upper surface of the diaphragm 10 and the overlapping structure 14 is fixed to the lower surface of the diaphragm 11. The overlapping structure 12 and the overlapping structure 14 are identical in shape, size and mass and can completely cover the vibration area 13. In this way, the total mass of the diaphragm 10 together with the overlap structure 12 is equal to the total mass of the diaphragm 11 together with the overlap structure 14, so that the diaphragm 10 and the diaphragm 11 have the same or close (e.g. the large resonance frequency differs from the small resonance frequency by no more than 5% of the small resonance frequency).

Alternatively, as shown in fig. 10 and 11, the length of the diaphragm 11, in which the overlap structure is not provided, may be increased so as to increase the mass thereof, so that the mass of the diaphragm 11 is equal to the total mass of the diaphragm 10 together with the overlap structure 12, thereby causing the diaphragms 10 and 11 to have the same or close resonance frequency. Wherein fig. 10 and 11 are resonant frequency leveling for the structures shown in fig. 7 and 8, respectively. Thus, the increase of the slit caused by the non-uniform resonant frequency of the diaphragm can be effectively avoided.

On the basis that the resonance frequencies of the two diaphragms are the same, if the structures of the two diaphragms are not identical, the vibration modes of the two diaphragms are not identical, and the possibility of inconsistent vibration states still exists. In this case, the vibration modes of the two diaphragms can be further "leveled".

Fig. 12 is a schematic perspective view of a MEMS speaker according to another exemplary embodiment of the present invention, showing a leveling scheme of a vibration mode.

Alternatively, as shown in fig. 12, the overlapping structures 12 and 14 having the same size, shape, and mass may be provided on the same side (upper side or lower side is shown in fig. 12) of the diaphragm 10 and the diaphragm 11, respectively. The overlapping structures 12 and 14 are vertically offset from each other, and each overlap structure has a dimension in the slit length direction of about half the slit length, so that the two overlapping structures collectively cover the space 13 for vibration. Therefore, the two diaphragms and the corresponding overlapping structures are in central symmetry, so that the vibration modes of the two diaphragms are identical, and the increase of the slit caused by the inconsistency of the vibration modes of the diaphragms can be effectively avoided.

The shape of the diaphragm in the above-described embodiments is rectangular, but other shapes, such as triangular, may be used.

Fig. 13 and 14 are perspective views of MEMS speakers according to various exemplary embodiments of the present invention, which illustrate triangular diaphragms.

Alternatively, as shown in fig. 13, the MEMS speaker may include two triangular diaphragms 10 and 11. Each triangular vibrating diaphragm has three end faces, one end of which is fixedly connected with the supporting piece 20, and the other two ends are free ends. For the diaphragm 10, one of the free ends and one of the free ends of the diaphragm 11 are opposed to each other, with a space 13 for vibration formed therebetween. The space 13 for vibration is covered with the overlapping structure 12 provided on the diaphragm 11. For triangular diaphragms, overlapping structures arranged as shown in fig. 7-12 may also be employed.

Alternatively, as shown in fig. 14, the MEMS speaker may include four triangular diaphragms. A space for vibration is formed between the opposite free ends of two adjacent diaphragms. The four triangular diaphragms form four spaces for vibration. The four spaces for vibration are covered with corresponding overlapping structures provided on the four diaphragms, respectively.

The vibration space in the previously described embodiments is formed by two adjacent diaphragms, but in addition, in different embodiments, the vibration space may also be formed by a diaphragm and a support.

Fig. 15 and 16 are schematic cross-sectional views of MEMS speakers according to various exemplary embodiments of the present invention, which illustrate a scheme of providing an overlap structure between a diaphragm and a support.

As shown in fig. 15 and 16, the MEMS speaker includes a diaphragm 10 and two supports 20. One end of the diaphragm 10 is fixed to the left support 20, which is a fixed end. The other end of the diaphragm 10 is a free end. The free end of the diaphragm 10 is spaced apart from the support 20 on the right. A space 13 for vibration is formed between the upper edge of the side edge of the support member 10 on the right facing the support member 20 on the left side (i.e. the edge corresponding to the upper left corner of the support member on the right in the cross-sectional view) and the free end of the diaphragm 10. The space 13 for vibration exists so that the free end of the diaphragm 10 is not restrained by the support 20 on the right side and can vibrate in the vertical direction.

Similar to the reason in the embodiment shown in fig. 3, in the embodiments shown in fig. 15 and 16, the space 13 for vibration also causes sound leakage. In contrast, in the embodiment shown in fig. 15 and 16, the free end of the diaphragm 10 extends above the support 20 on the right side so as to span and cover the space for vibration 13, and thus the portion of the diaphragm 10 that spans and exceeds the space for vibration 13 corresponds to the overlap structure 12 in fig. 3. Based on a similar principle to that in the embodiment shown in fig. 3, the embodiments shown in fig. 15 and 16 can also block the leakage path of the sound wave by using the overlapping structure, reducing the sound leakage caused by the space 13 for vibration.

Alternatively, as shown in fig. 15, the diaphragm 10 is entirely smooth, and the free end of the diaphragm 10 is inclined away from the support 20 on the right.

Alternatively, as shown in fig. 16, the end of the diaphragm 10 includes a step facing away from the support 20 on the right.

Fig. 6A shows the frequency sound pressure level curves of the diaphragms of fig. 1A and 15, and the sound pressure level at 2kHz is normalized, wherein the dashed line represents the normalized frequency sound pressure level curve of the cantilever beam diaphragm of fig. 1A, and the solid line represents the normalized frequency sound pressure level curve of the diaphragm of fig. 15. As shown in fig. 6A, the diaphragm in fig. 1A, which is not provided with an overlapping structure, has a sound pressure level that varies significantly with frequency, and the sound pressure level corresponding to a low frequency is low, so that the low frequency response is poor. The diaphragm of fig. 15 with the overlapping structure has the sound pressure level stable at a larger value when the frequency is changed, and has good response effect at each frequency, and particularly, the low-frequency response effect has significant advantages over the diaphragm of fig. 1A.

In the previously described embodiments, there is a certain spacing between the overlap structure and the further diaphragm or support. In addition to this, the overlap structure may also be in contact with another diaphragm (including a component thereon) or with a support (including a component thereon).

Fig. 17-22 are schematic cross-sectional views of MEMS speakers according to various exemplary embodiments of the invention, showing the arrangement of the overlapping structures in contact with the diaphragm (including the components thereon) or the support (including the components thereon).

The embodiment shown in fig. 17 is a modification of the embodiment shown in fig. 7, in that the distance between the overlap structure 12 and the diaphragm 11 in the embodiment shown in fig. 17 is further reduced on the basis of the embodiment shown in fig. 7, so that the overlap structure 12 is in contact with the diaphragm 11.

The embodiment shown in fig. 18 is another modification of the embodiment shown in fig. 7, in that the horizontal portion of the overlap structure in the embodiment shown in fig. 18 is inclined downward so that the overlap structure 12 is in contact with the diaphragm 11, based on the embodiment shown in fig. 7.

In the embodiment shown in fig. 19, the upper surfaces of the diaphragm 10 and the diaphragm 11 are provided with an overlap structure 12 and an overlap structure 14, respectively, and at least one of the overlap structure 12 and the overlap structure 14 can cover the slit. As shown in fig. 19, the height of the overlap structure 14 is greater than the height of the overlap structure 12, and the horizontal portion of the overlap structure 14 is in contact with the horizontal portion of the overlap structure 12.

In the embodiment shown in fig. 20, the free end of the diaphragm 11 extends above the diaphragm 10 and is in contact with the diaphragm 10. The diaphragm 11 spans the slit and forms an overlapping structure with the portion of the diaphragm 10, which is in contact with the diaphragm 10. Although not shown, as can be appreciated, the diaphragm 11 spans the slit and forms an overlapping structure with a portion of the diaphragm 10, which is spaced apart from the diaphragm 10 in the vibration direction.

In the embodiment shown in fig. 21, the height of the support 20 on the right side is smaller than the height of the support 20 on the left side. A space 13 for vibration is formed between the upper edge of the side edge of the support member 10 on the right facing the support member 20 on the left side (i.e. the edge corresponding to the upper left corner of the support member on the right in the cross-sectional view) and the free end of the diaphragm 10. The free end of the diaphragm 10 is inclined in the direction of the support 20 near the right. The portion of the diaphragm 10 that spans and exceeds the space for vibration 13 is an overlapping structure that is in contact with the support 20 on the right. Alternatively, in the embodiment shown in fig. 21, the free end of the diaphragm 10 comprises a step remote from the support 20 on the right.

The embodiment shown in fig. 22 is a variant of the embodiment shown in fig. 16, on the basis of the embodiment shown in fig. 7, the embodiment shown in fig. 22 being provided with an intermediate medium 15 between the diaphragm 10 and the support 20 on the right. The intermediate medium 15 is fixedly connected to the right-hand support 20. A space 13 for vibration is formed between the upper edge of the side edge of the support member 10 on the right facing the support member 20 on the left side (i.e. the edge corresponding to the upper left corner of the support member on the right in the cross-sectional view) and the free end of the diaphragm 10. The portion of the diaphragm 10 that spans and exceeds the space for vibration 13 is an overlapping structure that is in contact with the intermediate medium 15.

In the embodiments of fig. 17-22, the overlapping structures are in contact with the diaphragm (including the components thereon) or the support (including the components thereon), which can further reduce acoustic leakage.

In the embodiment shown in fig. 3, the vibrating space 13 is a slit which completely separates the free ends of the two diaphragms. In addition to this, the vibration space may be of other forms, such as holes or short grooves.

Fig. 23 is a schematic cross-sectional view of a MEMS speaker according to another embodiment of the present invention, showing a scheme in which the space for vibration is perforated or grooved.

As shown in fig. 23, the space 13 for vibration is not a slit between two diaphragms as shown in fig. 3, but an opening or slot provided in the diaphragm 10. The end face of the diaphragm 10 at the opening or slot, which forms a space for vibration, is not constrained. The overlapping structure 12 covers the openings or slots in a manner that spans them, thereby functioning to reduce acoustic leakage. Alternatively, both ends of the overlapping structure are fixedly connected with the diaphragm 10. Alternatively, the shape of the opening or slot may be a rectangular hole, a strip hole, a round hole, or the like.

The diaphragm of the present invention may be flat as shown in fig. 3, 3A, 16, 18, 19, 20, 22 or 23. The diaphragm of the present invention may have warpage as shown in fig. 7, 8, 9, 10, 11, 15, 17, or 21.

Fig. 24 and 24A are schematic cross-sectional views of MEMS speakers according to various exemplary embodiments of the present invention; fig. 25 and 25A are schematic cross-sectional views of MEMS speakers according to further different exemplary embodiments of the present invention, in which a specific film layer structure of a diaphragm is exemplarily shown. In fig. 24, the overlapping structure 6 has one end connected to one diaphragm and the other end spaced apart from the upper surface of the other diaphragm across the gap between the two diaphragms; in fig. 24A, the overlapping structure 6 has one end connected to one diaphragm and the other end in contact with the upper surface of the other diaphragm after crossing the gap between the two diaphragms. In fig. 25, the overlapping structure 6 is an extension structure of one diaphragm and is not in contact with the upper surface of the other diaphragm, and in fig. 25A, the overlapping structure 6 is an extension structure of one diaphragm and is in contact with the upper surface of the other diaphragm.

Based on the above, the invention provides the following technical scheme:

1. a MEMS speaker, comprising:

2. The speaker of claim 1, wherein:

the at least one vibrating diaphragm comprises at least two vibrating diaphragms, corresponding vibrating spaces are arranged between the other ends of the adjacent two vibrating diaphragms, which are opposite to each other, and the overlapping structures are arranged in the vibrating spaces of at least one pair of adjacent vibrating diaphragms.

3. The speaker of claim 2, wherein:

for the overlapping structure of the space setting for vibration of adjacent vibrating diaphragm, the one end of overlapping structure is fixed in the other end of one vibrating diaphragm in the adjacent vibrating diaphragm, the other end of overlapping structure strides across the space for vibration and is not contacted with another vibrating diaphragm in the adjacent vibrating diaphragm.

4. The speaker of claim 2, wherein:

for the overlapping structure of the space setting for vibration of adjacent vibrating diaphragm, the one end of overlapping structure is fixed in the other end of one vibrating diaphragm in the adjacent vibrating diaphragm, the other end of overlapping structure strides over the space for vibration and contacts or fixes with another vibrating diaphragm in the adjacent vibrating diaphragm.

5. The speaker of claim 2, wherein:

the vibration space includes a slit, a hole, or a groove.

6. The speaker of claim 3, wherein:

the resonant frequency of one of the adjacent diaphragms is equal to or close to the resonant frequency of the other of the adjacent diaphragms.

7. The speaker of claim 6, wherein:

the mass of one of the adjacent diaphragms is smaller than the mass of the other of the adjacent diaphragms.

8. The speaker of claim 6, wherein:

the length of one of the adjacent diaphragms is smaller than the length of the other of the adjacent diaphragms.

9. The speaker of claim 3, wherein:

the at least one overlapping structure comprises at least one pair of overlapping structures, and different overlapping structures in the at least one pair of overlapping structures are respectively arranged on different diaphragms in the at least one pair of adjacent diaphragms.

10. The speaker of claim 9, wherein:

different overlapping structures of the at least one pair of overlapping structures are positioned on the same side of the space for vibration and are staggered from each other in the vibration direction.

11. The speaker of claim 9, wherein:

different overlapping structures of the at least one pair of overlapping structures are located on the same side of the space for vibration, have different distances from the space for vibration, and are in contact with each other.

12. The speaker of claim 9, wherein:

different overlapping structures of the at least one pair of overlapping structures are located on different sides of the space for vibration, respectively.

13. The speaker of claim 2, wherein:

the shape of the diaphragm comprises a rectangle or a triangle.

14. The speaker of claim 1, wherein:

the at least one diaphragm includes one diaphragm having one end fixed to the first support member and the other end spaced apart from the second support member to form the space for vibration between an edge of a side of the second support member facing the first support member and the one diaphragm, and the other end of the one diaphragm extends above the second support member to span the space for vibration.

15. The speaker of claim 14, wherein:

an intermediate medium is arranged at the upper end of the second support piece, and the other end of the vibrating diaphragm is in contact with the intermediate medium.

16. The speaker of claim 14, wherein:

the other end of the one diaphragm includes a step remote from the second support.

17. The speaker of claim 14, wherein:

the other end of the one diaphragm is inclined in a direction away from the second support member.

18. The speaker of claim 1, wherein:

the at least one diaphragm includes one diaphragm, one end of the one diaphragm is fixed to the first support member, the other end is spaced apart from an edge of a side of the second support member facing the first support member to form the space for vibration between the edge of the side of the second support member facing the first support member and the one diaphragm, the other end of the one diaphragm extends to above the second support member to span the space for vibration, and the other end of the one diaphragm is in contact with an upper end of the second support member.

19. The speaker of claim 18, wherein:

the height of the second supporting piece is smaller than that of the first supporting piece, and the other end of the vibrating diaphragm is inclined towards the direction approaching to the second supporting piece.

20. The speaker of claim 18, wherein:

21. The speaker of claim 1, wherein:

at least one of the diaphragms is flat or has a warp.

22. The speaker of claim 1, wherein:

the space for vibration is in the form of a slit; and is also provided with

The distance between the overlapping structure and the space for vibration in the vertical direction is smaller than the width of the slit, and/or the dimension of the overlapping structure in the slit length direction is equal to the slit length.

23. An electronic device comprising a speaker according to any one of claims 1-22.

Although embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.

Claims

1. A MEMS speaker, comprising: