WO2022000636A1

WO2022000636A1 - Piezoelectric ultrasonic transducer

Info

Publication number: WO2022000636A1
Application number: PCT/CN2020/103901
Authority: WO
Inventors: 童贝; 石正雨; 沈宇; 李杨
Original assignee: 瑞声声学科技(深圳)有限公司; 瑞声科技（南京）有限公司
Priority date: 2020-07-02
Filing date: 2020-07-23
Publication date: 2022-01-06
Also published as: CN215918085U

Abstract

Provided is a piezoelectric ultrasonic transducer comprising: a substrate, and a diaphragm arranged facing the substrate at an interval, wherein the diaphragm comprises a first surface close to the substrate, and a second surface away from the substrate. The piezoelectric ultrasonic transducer further comprises a support member that connects the substrate and the first surface, and a piezoelectric element on the second surface. The diaphragm further comprises a central portion and an edge portion that extends from an edge of the central portion, wherein the support member is connected to the central portion; and the piezoelectric unit is arranged at the edge portion. Compared with the related art, in the piezoelectric ultrasonic transducer, a diaphragm is supported over a substrate by means of a support member, and the diaphragm is arranged in a suspended manner, such that the effective vibration area and the motion capacitive reactance of the diaphragm are increased, thereby improving the effective electromechanical coupling coefficient and the sound pressure output of the piezoelectric ultrasonic transducer.

Description

Piezoelectric ultrasonic transducer

technical field

The invention relates to the technical field of acoustics and electricity, in particular to a piezoelectric ultrasonic transducer.

Background technique

Ultrasonic sensors have a wide range of applications in social production and life, including ultrasonic processing, ultrasonic positioning, ultrasonic detection, and ultrasonic imaging. As a device that converts electrical energy and mechanical energy into each other, ultrasonic transducer is an important component of ultrasonic sensor. Traditional ultrasonic transducers are usually fabricated based on machining, so they have the disadvantages of large volume, low machining accuracy, high machining cost, and difficulty in forming an array structure. Based on MEMS (Microelectromechanical Ultrasonic transducers of Micro-Electro-Mechanical Systems) technology are processed by microelectronics technology, the diameter size can be reduced to micron level, and the resonant frequency can reach hundreds of megahertz. The higher resonant frequency greatly increases the imaging and detection capabilities. precision. In addition, the ultrasonic transducer processed by the MEMS process can form a large-scale array unit, and the consistency of each unit is good, which is convenient to use the phase control technology to realize the functions of focusing, discrete and directional scanning of the ultrasonic beam, which greatly enhances the application of ultrasonic technology. flexibility. Among them, piezoelectric ultrasonic transducers are particularly widely used.

In the piezoelectric ultrasonic transducer of the related art, the edge of the diaphragm is fixed by the base and then placed on the substrate. However, due to the restriction of the diaphragm edge of the piezoelectric ultrasonic transducer, only a part of the diaphragm structure in the middle is transmitted/received, which weakens the effective electromechanical coupling coefficient and sound pressure output of the piezoelectric ultrasonic transducer to a certain extent, and reduces the The performance of the piezoelectric ultrasonic transducer mentioned above.

Therefore, a new piezoelectric ultrasonic transducer must be provided to solve the above technical problems.

technical problem

The object of the present invention is to provide a piezoelectric ultrasonic transducer with high sensitivity.

technical solutions

In order to achieve the above object, the present invention provides a piezoelectric ultrasonic transducer, comprising: a base; a vibrating membrane, which is disposed opposite to the base and spaced apart, the vibrating membrane includes a first surface close to the base and a surface far away from the the second surface of the base; at least one supporting member connecting the base and the first surface to support the vibrating film on the base; and a piezoelectric unit arranged on the second surface; wherein, the The diaphragm further includes a center portion and an edge portion extending from an edge of the center portion, the support member is connected to the center portion, and the piezoelectric unit is disposed on the edge portion.

Preferably, the support member is a hollow cylinder or a solid cylinder.

Preferably, the support is cylindrical.

Preferably, the diaphragm is supported on the base by a plurality of the support members, and the plurality of the support members are distributed in an array.

Preferably, the piezoelectric ultrasonic transducer further includes a sealing member, the sealing member covers the diaphragm and the piezoelectric unit and is fixedly connected to the base.

Preferably, the sealing member and the substrate are fixed by bonding.

Preferably, the piezoelectric unit is annular, and includes a first electrode layer, a piezoelectric layer and a second electrode layer that are stacked in sequence.

Preferably, the diaphragm is configured as a curved surface structure and protrudes or recesses from the central portion.

beneficial effect

Compared with the related art, the above-mentioned piezoelectric ultrasonic transducer provided by the present invention supports the vibrating film on the base through a support member, and the vibrating film is suspended in the air, which increases the effective vibration area and motion capacitance of the vibrating film, thereby improving the performance of the vibrating film. Effective electromechanical coupling coefficient and sound pressure output of the piezoelectric ultrasonic transducer described above.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort, among which.

FIG. 1 is a schematic three-dimensional structural diagram of a first embodiment of a piezoelectric ultrasonic transducer provided by the present invention.

FIG. 2 is a schematic diagram of an exploded structure of the piezoelectric ultrasonic transducer shown in FIG. 1 .

FIG. 3 is a cross-sectional view of the piezoelectric ultrasonic transducer shown in FIG. 1 along the line A-A, and the base is connected to the diaphragm through one of the support members.

FIG. 4 is a cross-sectional view of the piezoelectric ultrasonic transducer shown in FIG. 1 along the line A-A, and the base is connected to the diaphragm through the two support members.

FIG. 5 is a schematic three-dimensional structural diagram of the piezoelectric ultrasonic transducer shown in FIG. 1 after removing the sealing member.

FIG. 6 is a schematic three-dimensional structural diagram of a second embodiment of the piezoelectric ultrasonic transducer provided by the present invention.

FIG. 7 is a cross-sectional view of the piezoelectric ultrasonic transducer shown in FIG. 6 along the line B-B, and the base is connected to the diaphragm through one of the support members.

FIG. 8 is a cross-sectional view of the piezoelectric ultrasonic transducer shown in FIG. 6 along the line B-B, and the base is connected to the diaphragm through a plurality of the support members.

Embodiments of the present invention

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

FIGS. 1-5 are the first embodiment of the present invention, please refer to FIGS. 1-5 at the same time, in this embodiment, the piezoelectric ultrasonic transducer 100 includes a base 10 and a sealing member sealingly connected with the base 10 and forming a closed space 20. The vibrating membrane 30 , the support member 40 and the piezoelectric unit 50 arranged in the sealed space. The vibrating membrane 30 and the base 10 are relatively spaced apart, and two ends of the support member 40 are respectively connected to the vibrating membrane 30 and the base 10 to support the vibrating membrane 30 on the base. 10 , and the piezoelectric unit 50 is disposed at the end of the diaphragm 30 away from the base 10 .

Specifically, the diaphragm 30 includes a center portion 33 and an edge portion 34 extending from an edge of the center portion 33 , a first surface 31 and a first surface 31 formed on two opposite surfaces of the center portion 33 and the edge portion 34 . The second surface 32 , wherein the first surface 31 is close to the substrate 10 , and the second surface 32 is far from the substrate 10 . That is, the first surface 31 is formed by the surface of the center portion 33 and the edge portion 34 close to the substrate 10 , and the second surface 32 is formed by the center portion 33 and the edge portion 34 away from the surface The surface of the base 10 is formed, one end of the support member 40 is connected to the central portion 33 of the first surface 31 , and the other end is joined to the base 10 , so that the edge of the diaphragm 30 is The portion 34 is suspended in the air, which increases the effective vibration area and motion capacitance of the diaphragm 30 . The piezoelectric unit 50 is annular, and includes a first electrode layer 51 , a piezoelectric layer 52 and a second electrode layer 53 that are stacked in sequence. The first electrode layer 51 is attached to the edge portion 34 of the second surface 32 . The piezoelectric unit 50 and the support member 40 are arranged staggered from each other, and the orthographic projections of the support member 40 and the piezoelectric unit 50 on the substrate 10 do not overlap, so that the piezoelectric unit 50 and the piezoelectric unit 50 do not overlap with each other. The edge portions 34 together form a suspended structure, which improves the effective electromechanical coupling coefficient of the piezoelectric unit 50 , thereby increasing the sound pressure output of the piezoelectric ultrasonic transducer 100 .

Wherein, the diaphragm 30 is configured as a curved structure and protrudes or recesses from the central portion 33 , that is, the central portion 33 is bent and deformed toward the base 10 or protrudes in a direction away from the base 10 , so that the The surface of the diaphragm 30 close to the substrate 10 is convex or concave. Compared with the edge fixing method of the diaphragm in the prior art, it is easier to set the diaphragm 30 in a concave or convex structure by setting the edge portion 34 of the diaphragm 30 in the air, which can increase the electromechanical coupling factor. , the directivity can also be improved to a certain extent, thereby improving the performance of the piezoelectric ultrasonic transducer 100 .

The base 10 is connected to the diaphragm 30 through at least one of the support members 40 , and the number and arrangement of the support members 40 can be set according to the situation. As shown in FIG. 2 , the base 10 is connected to the diaphragm 30 through a support member 40 . Specifically, the support member 40 is a hollow cylinder, preferably a hollow cylinder. A through hole 41 is provided, and a single supporting member 40 is used to support the diaphragm 30 on the base 10 . The hollow structure of the supporting member 40 can increase the stability of the connection between the diaphragm 30 and the base 10 .

The base 10 is also connected to the diaphragm 30 through a plurality of the support members 40 and 40' distributed in an array. As shown in FIG. 3 , the base 10 is not only connected to the diaphragm 30 through the support member 40 , but also connected to the diaphragm 30 through a support member 40 ′. The support member 40 and the support member 40' is coaxial and the outer diameter of the support member 40' is smaller than that of the support member 40. The support member 40 is sleeved on the outside of the support member 40', and the support member 40 and the support member 40' together The vibrating film 30 is supported on the base 10 , which further increases the stability of the connection between the vibrating film 30 and the base 10 .

Further, the sealing member 20 is generally in the shape of a cover, which includes a top wall 21 and a side wall 22 connected with the edge of the top wall 21 . The top wall 21 and the side wall 22 together surround the vibrating film 30 and the piezoelectric unit 50 , and one end of the side wall 22 away from the top wall 21 is fixedly connected to the base 10 , thereby The diaphragm 30 and the piezoelectric unit 50 are sealed to reduce the damping effect of the piezoelectric ultrasonic transducer 100 . Optionally, the top wall 21 and the side wall 22 and the side wall 22 and the base 10 are fixed by bonding. In other embodiments, the top wall 21 and the side wall 22 may be an integral structure.

5-8 are the second embodiment of the piezoelectric ultrasonic transducer 200 of the present invention. The difference between the second embodiment and the first embodiment lies in the structure of the support member 60 , so only the structure of the support member 60 is discussed. Description, other structures will not be repeated.

As shown in FIG. 7 , the support member 60 is a solid cylinder, preferably a solid cylinder, and a single support member 60 is used to support the diaphragm 30 on the base 10 . Compared with the hollow cylinder, the solid cylinder has fewer manufacturing processes, and setting the support member 60 as a solid cylinder can improve its processing efficiency. As shown in FIG. 8 , the diaphragm 30 is supported on the base 10 by a plurality of the support members 60 , and the plurality of support members 60 are distributed in a circular array between the base 10 and the center of the diaphragm 30 . During the time, the two ends of the plurality of the support members 60 are respectively connected with the diaphragm 30 and the base 10 , and the stability of the connection between the diaphragm 30 and the base 10 is increased by arranging the plurality of the support members 60 .

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

Claims

A piezoelectric ultrasonic transducer, comprising:

base;

a vibrating membrane, which is arranged at an interval relative to the base, and the vibrating membrane includes a first surface close to the base and a second surface far away from the base;

at least one supporting member connecting the base and the first surface to support the diaphragm on the base; and

a piezoelectric unit, arranged on the second surface;

Wherein, the diaphragm further includes a center portion and an edge portion extending from an edge of the center portion, the support member is connected to the center portion, and the piezoelectric unit is arranged on the edge portion.
The piezoelectric ultrasonic transducer according to claim 1, wherein the support member is a hollow cylinder or a solid cylinder.
The piezoelectric ultrasonic transducer according to claim 2, wherein the support member is in the shape of a cylinder.
The piezoelectric ultrasonic transducer according to claim 1, wherein the diaphragm is supported on the base by a plurality of the support members, and the plurality of the support members are distributed in an array.
The piezoelectric ultrasonic transducer according to claim 1, wherein the piezoelectric ultrasonic transducer further comprises a sealing member, the sealing member covers the diaphragm and the piezoelectric unit and is connected with the Base fixed connection.
The piezoelectric ultrasonic transducer according to claim 5, wherein the sealing member and the substrate are fixed by bonding.
The piezoelectric ultrasonic transducer according to claim 1, wherein the piezoelectric unit is annular, and comprises a first electrode layer, a piezoelectric layer and a second electrode layer that are stacked in sequence.
The piezoelectric ultrasonic transducer according to claim 1, wherein the diaphragm is arranged in a curved surface structure and protrudes or recesses from the central portion.