WO2022000792A1

WO2022000792A1 - Vibration sensor

Info

Publication number: WO2022000792A1
Application number: PCT/CN2020/114982
Authority: WO
Inventors: 曾鹏; 王天娇
Original assignee: 瑞声声学科技(深圳)有限公司
Priority date: 2020-06-30
Filing date: 2020-09-14
Publication date: 2022-01-06
Also published as: CN218679380U

Abstract

Provided in the present application is a vibration sensor, comprising a circuit board, an outer shell fixed on the circuit board and with the circuit board enclosing an accommodating cavity, a diaphragm assembly accommodated in the accommodating cavity and dividing the accommodating cavity into a first cavity and a second cavity, a MEMS microphone, and an ASIC chip attached to the side of the second cavity closest to the diaphragm assembly and being electrically connected to the MEMS microphone, the outer shell being provided with a first pressure relief hole, the MEMS microphone being accommodated in the second cavity and being electrically connected to the circuit board, the MEMS microphone comprising a base fixed to the circuit board and provided with a rear cavity, a first diaphragm supported on the end of the base furthest from the circuit board, and a rear electrode plate, the first diaphragm and the rear electrode plate being spaced apart to form a capacitor structure; when the vibration sensor inputs a vibration signal or pressure signal, the diaphragm assembly vibrates and changes the air pressure in the accommodating cavity. The vibration sensor of the present application has higher sensitivity and better reliability.

Description

Vibration sensor

technical field

The utility model relates to the field of acoustic-electrical conversion, in particular to a vibration sensor used for bone conduction electronic products.

Background technique

Vibration sensors are used to convert vibration signals into electrical signals.

technical problem

At present, the existing MEMS vibration sensor includes a diaphragm assembly as a vibration sensing device and a MEMS microphone as a vibration detection device that converts vibration signals into electrical signals. Since the vibration sensing device and the vibration detection device are integrated together, and because the MEMS microphone Using piezoelectric or capacitive induction, it can only be sensed when it is directly squeezed and contacted by pressure, making it sensitive to low-frequency vibration less than 500Hz, but poor response to high-frequency vibration greater than 1KHz, and its performance in the field of audio equipment is relatively high. Difference.

Therefore, it is necessary to provide a new vibration sensor to solve the above technical problems.

technical solutions

The purpose of this utility model is to provide a kind of vibration sensor, described vibration sensor comprises:

circuit board;

a casing, the casing is fixed on the circuit board and forms a receiving cavity with the circuit board, and the casing is provided with a first pressure relief hole passing through it;

a diaphragm assembly, the diaphragm assembly is accommodated in the accommodating cavity and the accommodating cavity is divided into a first cavity and a second cavity;

A MEMS microphone, the MEMS microphone is accommodated in the second cavity and is electrically connected to the circuit board, the MEMS microphone includes a base fixed on the circuit board and having a back cavity, and supported on the base A first vibrating film and a back electrode plate at one end away from the circuit board, the first vibrating film and the back electrode plate are spaced apart to form a capacitor structure;

an ASIC chip, which is attached to the side of the diaphragm assembly close to the second cavity and is electrically connected to the MEMS microphone;

When the vibration sensor inputs a vibration signal or a pressure signal, the diaphragm assembly vibrates and changes the air pressure in the receiving cavity.

Preferably, the diaphragm assembly is provided with a second pressure relief hole therethrough, and the first cavity communicates with the second cavity through the second pressure relief hole.

Preferably, the casing includes a casing plate spaced apart from the circuit board and a side plate that is bent and extended toward the circuit board from a peripheral edge of the casing plate and fixed to the circuit board. The pressing hole penetrates the outer shell plate.

Preferably, the diaphragm assembly includes a gasket fixed on the circuit board and a second diaphragm fixed on an end of the gasket away from the circuit board, the gasket, the second diaphragm and the The circuit boards together form the first cavity, the second diaphragm is provided with a second pressure relief hole passing through it, and the first cavity communicates with the second cavity through the second pressure relief hole .

Preferably, the ASIC chip is attached to a side of the second diaphragm close to the second cavity and is electrically connected to the back plate.

beneficial effect

Compared with the related art, in the vibration sensor of the present invention, the casing is fixed on the circuit board and forms a receiving cavity with the circuit board, the casing is provided with a first pressure relief hole passing through it, and the diaphragm assembly is accommodated in the the accommodating cavity is divided into a first cavity and a second cavity; the MEMS microphone is accommodated in the second cavity and is electrically connected with the circuit board, and the MEMS microphone includes a The circuit board has a base with a back cavity, a first vibrating film and a back plate supported on one end of the base away from the circuit board, and the first vibrating film and the back plate are spaced to form a capacitor structure; The ASIC chip is attached to a side of the diaphragm assembly close to the second cavity and is electrically connected with the MEMS microphone. Through the above structural design, both the diaphragm assembly and the MEMS microphone are accommodated in the receiving cavity, which saves space and facilitates production; while the MEMS microphone can better sense the vibration generated by the diaphragm assembly, and convert the induced vibration signal into an electrical signal. Thereby, a better vibration response to both high-frequency and low-frequency vibrations transmitted by the containment cavity is achieved, and the sensitivity is effectively improved; further, the ASIC chip provides an external bias for the MEMS microphone, and the effective bias will make all The MEMS microphone can maintain stable acoustic sensitivity and electrical parameters in the entire operating temperature range, and can also support the design of microphone structures with different sensitivities, making the design more flexible and reliable. At the same time, the ASIC chip is attached to the diaphragm assembly. To act as a mass block in the related art, the vibration of the diaphragm assembly is further increased, space is saved and cost is reduced.

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 drawings in the following description are only some implementations of the present invention. For example, for those of ordinary skill in the art, under the premise of no creative work, other drawings can also be obtained from these drawings, wherein:

Fig. 1 is the structural representation of the vibration sensor of the utility model;

Fig. 2 is the exploded schematic diagram of the vibration sensor of the utility model;

FIG. 3 is a cross-sectional view along A-A of FIG. 1 .

Embodiments of the present invention

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

It should be noted that the technical solutions between the various embodiments may be combined with each other, but must be based on the realization by those of ordinary skill in the art.

Referring to FIGS. 1-3 , the present invention provides a vibration sensor 100 , which includes a circuit board 1 , a housing 2 , a diaphragm assembly 3 , a MEMS microphone 4 and an ASIC chip 5 .

The casing 2 is fixed on the circuit board 1 and forms a receiving cavity 10 with the circuit board 1 . The casing 2 is provided with a first pressure relief hole 23 therethrough. In this embodiment, the casing 2 includes a casing plate 21 opposite to the circuit board 1 at intervals, and a peripheral edge of the casing plate 21 that is bent and extended toward the circuit board 1 and fixed to the circuit board 1 . In the side plate 22 , the first pressure relief hole 23 is provided through the outer shell plate 21 .

The diaphragm assembly 3 is accommodated in the accommodating cavity 10 and the accommodating cavity 10 is divided into a first cavity 101 and a second cavity 102 . Specifically, the diaphragm assembly 3 includes a gasket 31 fixed on the circuit board 1 and a second diaphragm 32 fixed on an end of the gasket 31 away from the circuit board 1 . The second diaphragm 32 and the circuit board 1 together form the first cavity 101 . The second diaphragm 32 is provided with a second pressure relief hole 30 therethrough to balance the air pressure. The pressure hole 30 communicates the first cavity 101 and the second cavity 102 .

The MEMS (Microelectro Mechanical Systems) microphone 4 , that is, a micro-electromechanical system microphone, is accommodated in the second cavity 102 and is electrically connected to the circuit board 1 . The MEMS microphone 4 includes a base 41 fixed on the circuit board 1 and having a back cavity 40 , a first diaphragm 42 and a back plate 43 supported on an end of the base 41 away from the circuit board 1 .

The first diaphragm 42 and the back plate 43 are spaced apart to form a capacitance structure. By changing the distance between the first diaphragm 42 and the back plate 43, the capacitance generated by the MEMS microphone 4 can be changed, thereby Realize changes in electrical signals.

In order to improve the sensitivity of the vibration sensor 100, in this embodiment, the vibration sensor further includes an ASIC (Application Specific Integrated Circuit) chip 5 , the ASIC chip 5 is attached to the side of the second diaphragm 32 close to the second cavity 102 and is electrically connected to the MEMS microphone 4 . The ASIC chip 5 provides an external bias for the MEMS microphone 4, and an effective bias will enable the MEMS microphone 4 to maintain stable acoustic sensitivity and electrical parameters in the entire operating temperature range, and can also support different sensitivities The microphone structure design is more flexible and reliable. At the same time, the ASIC chip 5 is attached to the second diaphragm 32 to act as a mass block in the related art, further increasing the vibration of the second diaphragm, saving space and reducing cost.

In the vibration sensor 100 of the above structure, when the vibration sensor 100 inputs a vibration signal or a pressure signal, for example, the side of the casing 2 away from the receiving cavity 10 and/or the side of the circuit board 1 away from the receiving cavity 10 . When a vibration signal or a pressure signal is input on one side, the diaphragm assembly 3 vibrates, causing the air pressure in the receiving cavity 10 to change, and the air pressure change causes the first diaphragm 42 of the MEMS microphone 4 to vibrate, changing the The distance between a diaphragm 42 and the back plate 43 changes the capacitance generated by the MEMS microphone 4, thereby converting the vibration signal into an electrical signal, and transmitting the converted electrical signal to the circuit board 1, That is, the synchronously changing electrical signal is transmitted to the circuit board 1 , so that the MEMS microphone 4 converts an external input vibration signal or pressure signal into an electrical signal, and converts the vibration signal into an electrical signal.

For example, the side of the circuit board 1 and/or the casing 2 of the vibration sensor 100 is attached to the neck, and when a person speaks, the bone conduction transmits the vibration signal, so as to realize the above transformation process.

In this process, the MEMS microphone 4 detects the external input vibration signal through the internal air pressure change caused by the vibration of the diaphragm assembly 3, so that the MEMS microphone 4 can ensure the accurate detection of the air pressure change to the greatest extent, especially for high frequencies greater than 1KHz. The vibration also has an accurate response, which effectively improves the sensitivity and reliability of the vibration sensor 100 .

Because the performance of the MEMS microphone 4 is relatively stable under different temperature conditions, its sensitivity is basically not affected by factors such as temperature, vibration, temperature and time, and the reliability and stability are high. Because the MEMS microphone 4 can be subjected to high temperature reflow soldering at 260° C. and the performance is not affected, the basic performance with high accuracy can still be achieved without the audio debugging process after assembly.

More preferably, in this embodiment, the casing 2 is provided with a first pressure relief hole 23 penetrating therethrough. Specifically, the first pressure relief hole 23 is provided through the casing plate 21 . When the whole machine is assembled by SMT (ie, indicating the assembly technology), the setting of the first pressure relief hole 23 plays the role of balancing the air pressure. Specifically, the outer shell plate 21 is attached and fixed to the interior of the mobile device through surface assembly technology, and the first pressure relief hole 23 is blocked to seal the accommodating cavity 10, which effectively avoids the interference of the external air-conducting sound signal, and furthermore The bone conduction sensitivity and frequency characteristics of the vibration sensor 100 are improved. Of course, the position and number of the first pressure relief holes 23 are not limited to this, and the principles are the same.

The diaphragm assembly 4 is provided with a second pressure relief hole 30 therethrough, and the first cavity 101 communicates with the second cavity 102 through the second pressure relief hole 30 to balance the second pressure relief hole 30 . The air pressure of the cavity 102 and the first cavity 101 .

The spacer 31 , the second diaphragm 32 and the circuit board 1 together form the first cavity 101 . That is, the spacer 31 is used to space the second diaphragm 32 from the circuit board 1 to provide a vibration space. Of course, the spacer 31 can also be integrally formed with the second diaphragm 32 . The second pressure relief hole 30 is disposed through the second diaphragm 32 . Of course, the position of the second pressure relief hole 30 is not limited to this, and the principle is the same.

The above are only the embodiments of the present utility model. 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 utility model, but these belong to The scope of protection of the utility model.

Claims

A vibration sensor, characterized in that the vibration sensor comprises:

circuit board;

a casing, the casing is fixed on the circuit board and forms a receiving cavity with the circuit board, and the casing is provided with a first pressure relief hole passing through it;

a diaphragm assembly, the diaphragm assembly is accommodated in the accommodating cavity and the accommodating cavity is divided into a first cavity and a second cavity;

A MEMS microphone, the MEMS microphone is accommodated in the second cavity and is electrically connected to the circuit board, the MEMS microphone includes a base fixed on the circuit board and having a back cavity, and supported on the base A first vibrating film and a back electrode plate at one end away from the circuit board, the first vibrating film and the back electrode plate are spaced apart to form a capacitor structure;

an ASIC chip, which is attached to the side of the diaphragm assembly close to the second cavity and is electrically connected to the MEMS microphone;

When the vibration sensor inputs a vibration signal or a pressure signal, the diaphragm assembly vibrates and changes the air pressure in the receiving cavity.
The vibration sensor according to claim 1, wherein the diaphragm assembly is provided with a second pressure relief hole therethrough, and the first cavity passes through the second pressure relief hole and the second cavity Connected.
The vibration sensor according to claim 2, wherein the casing comprises a casing plate spaced apart from the circuit board, and a peripheral edge of the casing plate is bent and extended toward the circuit board and fixed to the circuit board. The side plate of the circuit board, the first pressure relief hole penetrates through the shell plate.
The vibration sensor according to claim 1, wherein the diaphragm assembly comprises a spacer fixed to the circuit board and a second diaphragm fixed to an end of the spacer away from the circuit board, the The gasket, the second diaphragm and the circuit board together form the first cavity, the second diaphragm is provided with a second pressure relief hole therethrough, and the first cavity passes through the first cavity. Two pressure relief holes communicate with the second cavity.
The vibration sensor according to claim 4, wherein the ASIC chip is attached to a side of the second diaphragm close to the second cavity and is electrically connected to the back plate.