WO2021134667A1

WO2021134667A1 - Mems speaker

Info

Publication number: WO2021134667A1
Application number: PCT/CN2019/130902
Authority: WO
Inventors: 但强; 朱国; 程诗阳; 李杨
Original assignee: 瑞声声学科技(深圳)有限公司; 瑞声科技(新加坡)有限公司
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2021-07-08

Abstract

Provided in the present invention is a MEMS speaker, comprising a substrate through which an accommodating cavity is formed, a driving mechanism fixed on the substrate, a piston vibration mechanism opposite from and spaced from the driving mechanism and positioned in the accommodating cavity, and a transmission piece used to connect the driving mechanism and the piston vibration mechanism. The substrate comprises an annular peripheral wall enclosing the accommodating cavity, a gap is provided at an interval between the piston vibration mechanism and the peripheral wall, and the driving mechanism comprises a vibration plate and a first actuator arranged on the vibration plate, the first actuator driving the vibration plate to vibrate. The piston vibration mechanism comprises a piston diaphragm and a second actuator arranged on the piston diaphragm, the second actuator driving the piston diaphragm to vibrate, and the driving mechanism further propelling the piston diaphragm by means of the transmission piece. In the present MEMS speaker, the integration of a driving mechanism and a piston vibration mechanism on a same plane is avoided, reducing surface area, and further reducing the space occupied by the speaker. Compound motion of a piston diaphragm performing piston motion and out-of-plane vibration is made possible, improving the signal-to-noise ratio of the speaker.

Description

A MEMS speaker

Technical field

The utility model relates to the technical field of acoustic-electric conversion, in particular to a MEMS speaker.

Background technique

With the rapid development of personal mobile communications, the simple structure and the ability to operate at low voltage of piezoelectric micro-speakers have promoted its rapid development in this field. Generally, a piezoelectric microspeaker includes a piezoelectric plate and a vibrating membrane. The electrode layers are formed on both sides of the piezoelectric plate, and the vibrating membrane has no piezoelectricity. When a voltage is applied through the electrode layer, the piezoelectric plate deforms, which causes the diaphragm to vibrate and generate sound. In the prior art, the vibration amplitude of the central part of the diaphragm is large and the peripheral vibration amplitude is small, which limits the degree of deformation of the diaphragm, and it is difficult to obtain a sufficient level of sound. At present, there are reports of piezoelectric micro speakers using dual diaphragms. The diaphragm performs out-of-plane vibration, and the other diaphragm performs a composite movement of piston movement and out-of-plane vibration, thereby improving the signal-to-noise ratio. However, the two diaphragms of the piezoelectric micro-speaker are integrated in a plane and occupy a large area. It is not conducive to the miniaturization of the speaker, and there is no limit structure for the displacement of the diaphragm, so the speaker has poor drop and impact reliability.

Therefore, it is necessary to provide a space-saving MEMS speaker with dual diaphragms.

Summary of the invention

technical problem

The purpose of the utility model is to provide a MEMS speaker to solve the technical problem that the in-plane integration of the existing dual-diaphragm MEMS speaker is not conducive to the development of miniaturization.

The solution to the problem

Technical solutions

The technical solution of the present invention is as follows: a MEMS speaker, comprising a substrate formed with a receiving cavity penetrating, a driving mechanism fixed to the substrate, and a piston vibration arranged opposite to the driving mechanism and spaced apart and located in the receiving cavity Mechanism and a transmission member for connecting the driving mechanism and the piston vibration mechanism, the base plate includes an annular peripheral wall enclosing the receiving cavity, and a gap is provided between the piston vibration mechanism and the peripheral wall, so The driving mechanism includes a vibrating plate and a first actuator provided on the vibrating plate, and the first actuator drives the vibrating plate to vibrate; the piston vibrating mechanism includes a piston diaphragm and a first actuator disposed on the piston diaphragm The second actuator, the second actuator drives the piston membrane to vibrate, and the driving mechanism further pushes the piston membrane through the transmission member.

Further, the first actuator and the second actuator are both piezoelectric sheets, and the first actuator and the second actuator are electrically connected via the transmission member.

Further, the driving mechanism includes an extension arm extending from the peripheral wall into the receiving cavity, and a cantilever beam extending from an end of the extension arm away from the peripheral wall, and the cantilever beam is spaced apart from the peripheral wall, The transmission member is connected between the cantilever beam and the piston vibration plate.

Further, opposite ends of the extension arm span across opposite sides of the peripheral wall, and the cantilever beam extends from the extension arm in a direction perpendicular to the extension arm.

Further, the extension arm includes extension sub-arms respectively extending from opposite two peripheral walls to opposite sides, and the two extension sub-arms are spaced apart from each other, and the cantilever beam is away from the extension sub-arm from the peripheral wall. One side is bent and extended in a direction opposite to the extension sub-arm, and is spaced apart from the extension sub-arm.

Further, the opposite sides of each extension sub-arm are spaced apart to form the cantilever beam, and the cantilever beam and the transmission member are arranged in a one-to-one correspondence.

Further, the cantilever beams respectively extend from one end of the extension arm away from the peripheral wall to the opposite side, and are arranged at intervals relative to the two cantilever beams, and the transmission member spans between the two opposite cantilever beams. It is sandwiched between the cantilever beam and the piston vibration mechanism.

Further, the transmission member is columnar and coincides with the central axis of the piston vibration mechanism.

Further, the piston vibration mechanism includes an anchor portion connected with the transmission member and a movable portion extending from the anchor portion.

Further, the gap is less than or equal to 100 microns.

Further, the piston vibration mechanism includes a body part parallel to the driving mechanism and a side plate extending from the edge of the body part toward the driving mechanism, the side plate and the peripheral wall are spaced apart, and the side plate The distance from the peripheral wall is less than or equal to the gap.

The beneficial effects of the invention

Beneficial effect

The beneficial effects of the utility model are: avoid the integration of the driving mechanism and the piston vibration mechanism in the same plane, reduce the plane area, and further reduce the space of the MEMS speaker; realize the compound movement of the piston movement and the out-of-plane vibration of the piston membrane, and improve the MEMS The signal-to-noise ratio of the loudspeaker also limits the piston movement of the piston membrane, which improves the reliability of drops and impacts.

Brief description of the drawings

Description of the drawings

FIG. 1 is a schematic structural diagram of a MEMS speaker provided by the first embodiment of the present invention;

FIG. 2 is a schematic structural diagram of the MEMS speaker shown in FIG. 1 from another angle;

Figure 3 is a cross-sectional view along the line A-A in Figure 2;

Figure 4 is a cross-sectional view along the line B-B in Figure 2;

Fig. 5 is a schematic structural diagram of a MEMS speaker provided by the second embodiment of the utility model;

Figure 6 is a cross-sectional view along line C-C in Figure 5;

7 is a schematic structural diagram of another MEMS speaker provided by the second embodiment of the utility model;

Figure 8 is a cross-sectional view along the line D-D in Figure 7;

FIG. 9 is a schematic structural diagram of a MEMS speaker at one angle according to the third embodiment of the utility model; FIG.

FIG. 10 is a schematic structural diagram of the MEMS speaker shown in FIG. 9 from another angle;

Figure 11 is a cross-sectional view along line E-E in Figure 9;

12 is a schematic structural diagram of another MEMS speaker provided by the third embodiment of the utility model;

Fig. 13 is a cross-sectional view taken along the line F-F in Fig. 12.

In the figure: 100, MEMS speaker; 1, substrate; 11, housing cavity; 12, peripheral wall; 2, drive mechanism; 21, vibrating plate; 22, first actuator; 23, extension arm; 231, extension sub-arm; 24. Cantilever beam; 3. Piston vibration mechanism; 31. Piston membrane; 32. Second actuator; 33. Body part; 331. Anchoring part; 332. Movable part; 34. Side plate; 4. Transmission part; 5. Gap.

Invention embodiment

Detailed ways

The following describes the present utility model in detail with reference to Figs. 1-13.

Example one

1 to 4, an embodiment of the present invention provides a MEMS speaker 100, which includes a substrate 1 formed with a receiving cavity 11 therethrough, a driving mechanism 2 fixed to the substrate 1, opposite to the driving mechanism 2 and spaced apart and located at The piston vibrating mechanism 3 in the receiving cavity 11 and the transmission member 4 for connecting the driving mechanism 2 and the piston vibrating mechanism 3, the base plate 1 includes an annular peripheral wall 12 enclosing the receiving cavity 11, and the piston vibrating mechanism 3 and the peripheral wall 12 are spaced apart There is a gap 5, the driving mechanism 2 includes a vibrating plate 21 and a first actuator 22 disposed on the vibrating plate 21, the first actuator 22 drives the vibrating plate 21 to vibrate; the piston vibrating mechanism 3 includes a piston diaphragm 31 and a first actuator 22 disposed on the piston diaphragm The second actuator 32 on the 31, the second actuator 32 drives the piston membrane 31 to vibrate, and the driving mechanism 2 further pushes the piston membrane 31 through the transmission member 4.

The piston motion is defined as the vibration of the diaphragm when the amplitude of any part of the diaphragm is equal; taking the diaphragm that is fixed to the substrate on all sides as an example, the out-of-plane vibration is defined as the part of the diaphragm that is away from the substrate when the diaphragm is vibrating toward the part of the diaphragm that is close to the substrate. Its amplitude gradually decreases. In the embodiment of the present invention, both the vibrating plate 21 and the piston diaphragm 31 are vibrating diaphragms.

By arranging the driving mechanism 2 and the piston vibrating mechanism 3 opposite to each other, the integration of the two in the same plane is avoided, the plane area is saved, and the space of the MEMS speaker 100 is further reduced; the first actuator 22 is provided to drive the vibrating plate 21 for out-of-plane vibration , The second actuator 32 is provided to drive the piston membrane 31 for out-of-plane vibration, and the transmission member 4 is provided at the same time, so that the driving mechanism 2 further pushes the piston membrane 31 through the transmission member 4 for piston movement, thus realizing the simultaneous piston movement of the piston membrane 31 The combined movement with out-of-plane vibration improves the signal-to-noise ratio of the MEMS speaker 100; by setting the gap 5, it is convenient for the piston membrane 31 to perform piston movement.

Preferably, both the first actuator 22 and the second actuator 32 are piezoelectric sheets, and the first actuator 22 and the second actuator 32 are electrically connected via the transmission member 4.

Preferably, the driving mechanism 2 includes an extension arm 23 extending from the peripheral wall 12 into the receiving cavity 11, a cantilever beam 24 extending from an end of the extension arm 23 away from the peripheral wall 12, the cantilever beam 24 is spaced apart from the peripheral wall 12, and the transmission member 4 is connected to Between the cantilever beam 24 and the piston vibration plate 21. In this embodiment, the extension arm 23 includes extension sub-arms 231 respectively extending from the two opposite peripheral walls 12 to opposite sides. The two opposite extension sub-arms 231 are spaced apart from each other. The cantilever beam 24 extends from the extension sub-arm 231 away from the side of the peripheral wall 12 The extension sub-arm 231 is bent and extended in a direction opposite to the extension sub-arm 231 and is spaced apart from the extension sub-arm 231. The two opposite sides of each extension sub-arm 231 form a cantilever beam 24 at intervals, and the cantilever beam 24 and the transmission member 4 are arranged in a one-to-one correspondence.

Preferably, the piston vibration mechanism 3 includes an anchor portion 331 connected with the transmission member 4 and a movable portion 332 extending from the anchor portion 331. In this embodiment, the piston vibration mechanism 3 is provided with four anchoring parts 331, and the movable parts 332 extending from the four anchoring parts 331 are connected to form a movable part 332, and the anchoring part 331 and the movable part 332 are integrally formed. The piston vibrating mechanism 3, the piston vibrating mechanism 3 is rectangular, and in other embodiments may also be circular, polygonal, or the like.

Specifically, the transmission member 4 is four support columns, which are respectively supported on the four corners of the rectangular piston vibration mechanism 3. It can be understood that, in other embodiments, it may also be a support rod, a support plate, a support block, a support table, and the like.

Preferably, the gap 5 is less than or equal to 100 microns. In this embodiment, the gap 5 is 10 micrometers. It is understandable that the gap 5 is less than 10 micrometers. The arrangement of the gap 5 not only ensures that the piston vibrating mechanism 3 can freely perform piston movement, but also avoids the occurrence of excessively low sound pressure caused by air leakage due to an excessively large gap.

Preferably, the piston vibration mechanism 3 includes a body portion 33 parallel to the drive mechanism 2 and a side plate 34 extending from the edge of the body portion 33 toward the drive mechanism 2. The side plate 34 is spaced from the peripheral wall 12, and the side plate 34 is connected to the peripheral wall 12 The distance between them is less than or equal to the gap 5. By setting in this way, it is further avoided that the sound pressure is too low due to air leakage when the piston vibrating mechanism 3 performs the piston movement.

Example two

Referring to Figures 5 to 8, the difference between this embodiment and the first embodiment is that the opposite ends of the extension arm 23 span the opposite sides of the peripheral wall 12, and the cantilever beam 24 extends from the extension arm 23 along a line perpendicular to the extension arm 23. Direction extension.

The piston vibrating mechanism 3 may be exactly the same as the first embodiment, or may include an anchor portion 331 connected to the transmission member 4 and two movable portions 332 arranged at intervals extending from the anchor portion 331. It can be understood that the movable part 332 can be a cantilever beam, a serpentine beam, a fixed beam, or the like. The transmission member 4 is two support plates connected to the middle of the opposite sides of the piston vibration mechanism 3, and each support plate supports a movable part 332.

Example three

Referring to Figures 9 to 11, the difference between this embodiment and the first embodiment is that the cantilever beams 24 respectively extend from one end of the extension arm 23 away from the peripheral wall 12 to the opposite side. The two cantilever beams 24 are spaced apart from each other, and the transmission member 4 spans It is connected between two opposite cantilever beams 24 and sandwiched between the cantilever beam 24 and the piston vibration mechanism 3. The transmission member 4 is columnar and coincides with the central axis of the piston vibration mechanism 3. One transmission member 4 is provided.

The piston vibration mechanism 3 has a square shape, and includes an anchor portion 331 connected to the transmission member 4 and four movable portions 332 extending from the anchor portion 331, and two adjacent movable portions 332 are arranged at intervals. In other embodiments, the piston vibration mechanism 3 may also be circular or regular polygonal. Please refer to Fig. 12 and Fig. 13, the piston vibrating mechanism 3 is circular, and there are six movable parts 332.

The above are only the embodiments of the present utility model. It should be pointed out here that for those of ordinary skill in the art, improvements can be made without departing from the inventive concept of the present utility model, but these all belong to the present invention. The scope of protection of utility models.

Claims

A MEMS speaker, which is characterized in that it comprises a substrate formed with a receiving cavity penetrating, a driving mechanism fixed to the substrate, a piston vibrating mechanism arranged opposite to and spaced apart from the driving mechanism and located in the receiving cavity, and A transmission member connecting the driving mechanism and the piston vibration mechanism, the base plate includes an annular peripheral wall enclosing the receiving cavity, a gap is provided between the piston vibration mechanism and the peripheral wall, and the driving mechanism includes A vibration plate and a first actuator arranged on the vibration plate, the first actuator drives the vibration plate to vibrate; the piston vibration mechanism includes a piston membrane and a second actuator arranged on the piston membrane The second actuator drives the piston membrane to vibrate, and the driving mechanism further pushes the piston membrane through the transmission member.
The MEMS speaker according to claim 1, wherein the first actuator and the second actuator are both piezoelectric sheets, and the first actuator and the second actuator It is electrically connected via the transmission member.
The MEMS speaker according to claim 1, wherein the driving mechanism comprises an extension arm extending from the peripheral wall into the receiving cavity, and a cantilever beam extending from an end of the extension arm away from the peripheral wall, The cantilever beam and the peripheral wall are spaced apart, and the transmission member is connected between the cantilever beam and the piston vibration plate.
The MEMS speaker according to claim 3, wherein the opposite ends of the extension arm are bridged on opposite sides of the peripheral wall, and the cantilever beam extends from the extension arm perpendicular to the extension arm. Direction extension.
The MEMS speaker according to claim 3, wherein the extension arm comprises extension sub-arms respectively extending from two opposite peripheral walls to opposite sides, and the two extension sub-arms are spaced apart from each other, and the cantilever beam From the side of the extension sub-arm away from the peripheral wall, it bends and extends in a direction opposite to the extension sub-arm and is arranged spaced apart from the extension sub-arm.
The MEMS speaker according to claim 5, wherein the cantilever beams are formed on opposite sides of each extension sub-arm at intervals, and the cantilever beams are arranged in a one-to-one correspondence with the transmission member.
The MEMS speaker according to claim 3, wherein the cantilever beams respectively extend from one end of the extension arm away from the peripheral wall to the opposite side, and are spaced apart from the two cantilever beams, and the transmission member spans It is connected between the two opposite cantilever beams and sandwiched between the cantilever beam and the piston vibration mechanism.
8. The MEMS speaker according to claim 7, wherein the transmission member is cylindrical and coincides with the central axis of the piston vibration mechanism.
The MEMS speaker according to claim 1, wherein the piston vibration mechanism comprises an anchoring part connected with the transmission member and a movable part extending from the anchoring part.
The MEMS speaker of claim 1, wherein the gap is less than or equal to 100 microns.
The MEMS speaker according to claim 1, wherein the piston vibration mechanism comprises a body part parallel to the driving mechanism and a side plate extending from an edge of the body part toward the driving mechanism, and the side plate is connected to the driving mechanism. There is an interval between the peripheral walls, and the distance between the side plate and the peripheral wall is less than or equal to the gap.