WO2022000852A1

WO2022000852A1 - Vibration sensor

Info

Publication number: WO2022000852A1
Application number: PCT/CN2020/121263
Authority: WO
Inventors: 曾鹏; 王凯
Original assignee: 瑞声声学科技(深圳)有限公司
Priority date: 2020-06-30
Filing date: 2020-10-15
Publication date: 2022-01-06
Also published as: CN218679382U

Abstract

The present utility model provides a vibration sensor. The vibration sensor comprises: a circuit board having a resonant cavity, one side of the circuit board being provided with a through hole penetrating through the circuit board; a housing, the housing being fixed to the circuit board in a covering manner and covering the through hole, and the housing and the circuit board jointly defining an accommodating cavity; an MEMS microphone accommodated in the accommodating cavity and electrically connected to the circuit board, the MEMS microphone comprising a base fixed to the circuit board and having a back cavity, a first diaphragm supported at the end of the base away from the circuit board, and a back electrode board, wherein the base surrounds the through hole and enables the back cavity and the through hole to be communicated, and the first diaphragm is spaced from the back electrode board to form a capacitor structure; and a diaphragm assembly which is accommodated in the resonant cavity and partitions the resonant cavity into a first cavity and a second cavity, the first cavity and the back cavity being communicated by means of the through hole. When a vibration signal or a pressure signal is inputted from the side of the circuit board away from the resonant cavity, the diaphragm assembly vibrates and causes air pressure in the resonant cavity to change. Compared with the related art, the vibration sensor of the present utility model 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. Existing MEMS vibration sensors include a diaphragm assembly as a vibration sensing device and a MEMS microphone as a vibration detection device that converts vibration signals into electrical signals.

technical problem

Since the vibration sensing device and the vibration detection device are integrated together, and because the MEMS microphone adopts piezoelectric or capacitive sensing, it can only be sensed under the condition of direct pressure contact, making it sensitive to low-frequency vibration less than 500Hz, but not sensitive to low-frequency vibration. The high-frequency vibration greater than 1KHz has poor response, and it has better performance in the field of audio equipment.

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

technical solutions

The purpose of the utility model is to provide a vibration sensor with high sensitivity and good reliability.

In order to achieve the above purpose, the utility model provides a vibration sensor, which includes:

a circuit board, the circuit board encloses a resonant cavity, and one side of the circuit board is provided with a through hole passing through it;

a casing, the casing cover is fixed on the circuit board and covers the through hole, and the casing and the circuit board together form a receiving cavity;

A MEMS microphone, the MEMS microphone is accommodated in the accommodating cavity and is electrically connected to the circuit board, the MEMS microphone comprises a base fixed on the circuit board and having a back cavity, and is supported on the base away from a first diaphragm and a back plate at one end of the through hole; the base surrounds the through hole and makes the back cavity communicate with the through hole; the first diaphragm and the back plate are spaced apart forming a capacitive structure; and,

a diaphragm assembly, the diaphragm assembly is accommodated in the resonant cavity, and the resonant cavity is divided into a first cavity and a second cavity, and the first cavity is communicated with the back cavity through the through hole;

The casing is provided with a first pressure relief hole therethrough, 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 pressure relief hole. cavity communication;

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

Preferably, the vibration sensor further includes an ASIC chip, and the ASIC chip is accommodated in the accommodating cavity and is electrically connected to the MEMS microphone.

Preferably, the casing is provided with a first pressure relief hole passing through it, and the first pressure relief hole communicates the receiving cavity with the outside world; the diaphragm assembly is provided with a second pressure relief hole passing through it. , the second pressure relief hole communicates the first cavity and the second cavity.

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 arranged around the through hole, and a second diaphragm fixed on the side of the gasket away from the through hole, the gasket, The second diaphragm and the circuit board together form the first cavity, and the second pressure relief hole penetrates the second diaphragm.

Preferably, the diaphragm assembly further includes a mass block fixedly connected to the second diaphragm; the mass block is attached to a side of the second diaphragm close to the first cavity and/or the The second diaphragm is close to one side of the second cavity.

Preferably, the mass blocks located on the same side of the second diaphragm include a plurality of mass block units spaced apart from each other.

Preferably, the diaphragm assembly further includes a mass block wrapped and fixed by the second diaphragm.

Preferably, the second diaphragm includes two second diaphragms fixed on the spacer and stacked on each other, and the mass block is sandwiched and wrapped between the two second diaphragms.

Preferably, the orthographic projection area of the first diaphragm on the circuit board along the vibration direction is smaller than the orthographic projection area of the second diaphragm on the circuit board along the vibration direction.

beneficial effect

Compared with the related art, in the vibration sensor of the present invention, a resonant cavity is formed by the circuit board, a through hole is provided on one side of the circuit board, and a diaphragm assembly is arranged in the resonant cavity to separate the resonant cavity into a shape. A first cavity and a second cavity; the housing and the circuit board are arranged to jointly enclose a receiving cavity, and a MEMS microphone is arranged in the receiving cavity, and the MEMS microphone includes a base fixed on the circuit board and having a back cavity. a seat, a first vibrating film supported on the base, and a back plate; the base surrounds the through hole and makes the back cavity communicate with the through hole; the through hole connects the first cavity with the through hole The back cavity is communicated. Through the above structural design, the diaphragm assembly is accommodated in the resonant cavity of the circuit board, which saves space and facilitates production; and the MEMS microphone can better sense the vibration generated by the vibration assembly, and convert the induced vibration signal into an electrical signal. Thereby, better vibration response to both high-frequency vibration and low-frequency vibration transmitted by the resonant cavity is achieved, and the sensitivity is effectively improved.

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 three-dimensional structure schematic diagram of the vibration sensor of the present invention;

Fig. 2 is the partial three-dimensional structure exploded schematic diagram of the vibration sensor of the present invention;

3 is a cross-sectional view of the first embodiment of the vibration sensor of the present invention along the line A-A in FIG. 1;

FIG. 4 is a schematic structural diagram of the second embodiment of the fixing method of the mass block and the second diaphragm of the vibration sensor in FIG. 3;

FIG. 5 is a schematic structural diagram of the third embodiment of the fixing method of the mass block and the second diaphragm of the vibration sensor in FIG. 3;

FIG. 6 is a schematic structural diagram of another embodiment after the structure of the mass block in FIG. 5 is changed;

FIG. 7 is a schematic structural diagram of a fourth embodiment of the way of fixing the mass block and the second diaphragm in the vibration sensor in FIG. 3 .

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 MEMS microphone 3 and a diaphragm assembly 4 .

The circuit board 1 encloses a resonant cavity 10 , and one side of the circuit board 1 is provided with a through hole 11 extending therethrough. For example, the circuit board 1 is designed to be a hollow integral molding structure, and the resonant cavity 10 is formed inside; or, the circuit board 1 includes a two-layer structure of an upper-layer circuit board 12 and a lower-layer circuit board 13 arranged at intervals from each other , and a spacer 14 is arranged between the upper circuit board 12 and the lower circuit board 13 . The upper circuit board 12 and the lower circuit board 13 are respectively fixed on opposite sides of the spacer 14 and together form the resonant cavity 10 .

The casing 2 is covered and fixed on the circuit board 1 and covers the through hole 11 , and the casing 2 and the circuit board 1 together enclose a receiving cavity 20 . That is, the through hole 11 communicates with the receiving cavity 20 .

In this embodiment, the casing 2 includes a casing plate 21 opposite to the circuit board 1 at intervals, and a casing plate 21 that is bent and extended toward the circuit board 1 from the periphery of the casing plate 21 and is fixed to the circuit board 1 . side panel 22.

The MEMS (Microelectro Mechanical Systems) microphone 3 , that is, a micro-electromechanical system microphone, which is accommodated in the accommodation cavity 20 and is electrically connected to the circuit board 1 . The MEMS microphone 3 includes a base 31 fixed on the circuit board 1 and having a back cavity 30 , a first diaphragm 32 and a back plate 33 supported on an end of the base 31 away from the through hole 11 .

The first diaphragm 32 and the back plate 33 are spaced apart to form a capacitance structure. By changing the distance between the first diaphragm 32 and the back plate 33, the capacitance generated by the MEMS microphone 3 can be changed, thereby Realize changes in electrical signals.

The base 31 surrounds the through hole 11 and makes the back cavity 30 communicate with the through hole 11 .

The diaphragm assembly 4 is accommodated in the resonant cavity 10 and divides the resonant cavity 10 into a first cavity 101 and a second cavity 102 , and the first cavity 101 is connected to the back cavity through the through hole 11 . 30 connections.

In the vibration sensor 100 of the above structure, when the vibration sensor 100 inputs a vibration signal or a pressure signal, when the vibration sensor 100 inputs a vibration signal or a pressure signal, the vibration component 4 vibrates and makes the air pressure in the resonant cavity 10. make a difference. The change in air pressure causes the vibration of the first diaphragm 32 of the MEMS microphone 3 , which changes the distance between the first diaphragm 32 and the back plate 33 , that is, changes the capacitance generated by the MEMS microphone 3 . , so as to convert the vibration signal into an electrical signal, and transmit the converted electrical signal to the circuit board 1, so that the MEMS microphone 3 converts the external input vibration signal or pressure signal into an electrical signal, and realizes the conversion of the vibration signal into an electrical signal. 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 3 detects the external input vibration signal through the internal air pressure change caused by the vibration of the diaphragm assembly 4, so that the MEMS microphone 3 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 3 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 is good and the stability is high. Because the MEMS microphone 3 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 order to further improve the sensitivity of the vibration sensor 100 , in this embodiment, the vibration sensor further includes an ASIC (Application Specific Integrated Circuit) chip 5 , and the ASIC chip 5 is accommodated in the accommodation cavity 20 and It is electrically connected with the MEMS microphone 3 . The ASIC chip 5 provides an external bias for the MEMS microphone 3, and an effective bias will enable the MEMS microphone 3 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.

In this embodiment, the casing 2 is provided with a first pressure relief hole 23 penetrating the casing 2 . Specifically, the first pressure relief hole 23 is one and is provided through the casing plate 21 . When the whole machine is assembled by SMT (Surface Mount Technology), the setting of the first pressure relief hole 23 plays a role of positioning and balancing the air pressure, so that the vibration sensor 100 can be accurately installed in a specific position of the mobile device. Specifically, the 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 20, which effectively avoids electromagnetic and radio frequency interference with external air conduction. The acoustic signal interferes, thereby improving the high-frequency characteristic of the bone conduction sensitivity and frequency characteristic of the vibration sensor 100 . Of course, the position and number of the first pressure relief holes 23 are not limited to this, and the principles are the same.

Similarly, the diaphragm assembly 4 is provided with a second pressure relief hole 40 therethrough, and the second pressure relief hole 40 communicates the first cavity 101 and the second cavity 102 to balance all the The air pressures of the second cavity 102 and the first cavity 101 are balanced, that is, the air pressures of the second cavity 102 and the back cavity 30 are balanced.

Specifically, the diaphragm assembly 4 includes a gasket 41 fixed on the circuit board 1 and disposed around the through hole 11 and a second diaphragm fixed on the side of the gasket 41 away from the through hole 11 42. The spacer 41 , the second diaphragm 42 and the circuit board 1 together form the first cavity 101 . That is, the spacer 41 is used to space the second diaphragm 42 from the circuit board 1 to provide a vibration space. Of course, the spacer 41 can also be integrally formed with the second diaphragm 42 . The second pressure relief hole 40 is disposed through the second diaphragm 42 . Of course, the position of the second pressure relief hole 40 is not limited to this, and the principle is the same.

In this embodiment, the diaphragm assembly 4 further includes a mass block 43 fixedly connected to the second diaphragm 42 . The mass block 43 is attached to the side of the second diaphragm 42 close to the first cavity 101 and/or the side of the second diaphragm 42 close to the second cavity 102 .

As shown in FIG. 1 , the mass block 43 is attached to the side of the second diaphragm 42 close to the first cavity 101 . The mass block 43 , the second diaphragm 42 and the spacer 41 are all located in the resonant cavity 10 of the circuit board 1 , which saves space and facilitates production.

More preferably, the orthographic projection area of the first diaphragm 32 on the circuit board 1 along the vibration direction is smaller than the orthographic projection area of the second diaphragm 42 on the circuit board 1 along the vibration direction. In this structural design, the contact area between the second diaphragm 42 and the gas in the resonant cavity 10 is larger, so that it can vibrate the gas better. Speaker-induced PCB noise results in lower vibration coupling, better acoustic performance, and ease of use.

Please refer to FIG. 4 , which is a schematic structural diagram of the second embodiment of the fixing mode of the mass block and the second diaphragm of the vibration sensor in the embodiment of FIG. 3 . The difference between the vibration sensor 200 of this embodiment is that the mass block 243 is attached to the side of the second diaphragm 242 close to the second cavity 2102 . The modification of this embodiment reduces the occupation of the volume of the first cavity 2101 by the mass 243 , increases the volume of the first cavity 2101 , and further improves the sensitivity of the vibration sensor 200 . Other than that, the basis is the same as that of the above-mentioned embodiment shown in FIG. 1 , and details are not repeated here.

Please refer to FIG. 5 , which is a schematic structural diagram of the third embodiment of the fixing method of the mass block and the second diaphragm of the vibration sensor in FIG. 3 . The difference between the vibration sensor 300 of this embodiment is that the mass block 343 is attached to the side of the second diaphragm 342 close to the first cavity 3101 and the second diaphragm 342 is close to the second diaphragm 342 one side of cavity 3102. That is, the mass blocks 343 include two groups, which are respectively attached to opposite sides of the second diaphragm 342 . This structural design further increases the inertia of the vibration component 34, thereby further improving the sensitivity. Other than that, the basis is the same as that of the above-mentioned embodiment shown in FIG. 1 , and details are not repeated here.

Please refer to FIG. 6 , which is a schematic structural diagram of another embodiment after the structure of the mass block in FIG. 5 is changed. In the vibration sensor 400 of this embodiment, the mass 443 located on the same side of the second diaphragm 442 includes a plurality of mass units 4431 spaced apart from each other. This structure is also designed to increase the inertia of the diaphragm assembly 44 to further improve the sensitivity, and, compared with the embodiment shown in FIG. 5, this structure can also increase the compliance of the second diaphragm 442, so that the second diaphragm 442 can The membrane 442 is more susceptible to vibration, further increasing the sensitivity of the vibration sensor 400 . Other than that, the basis is the same as that of the above-mentioned embodiment shown in FIG. 3 , and details are not repeated here.

Please refer to FIG. 7 , which is a schematic structural diagram of the fourth embodiment of the fixing method of the mass block and the diaphragm in FIG. 3 . Compared with other embodiments of the present invention, the main difference is that the mass block 543 is wrapped by the second diaphragm 542 to form a fixation.

Specifically, the second diaphragm 542 includes two second sub-diaphragms 5421 fixed on the spacer 541 and stacked on each other, and the mass block 543 is sandwiched and wrapped around the two second sub-diaphragms Between 5421. This structural design increases the fixing strength of the mass block 543 and further improves the reliability.

Compared with the related art, in the vibration sensor of the present invention, a resonant cavity is formed by the circuit board, a through hole is provided on one side of the circuit board, and a diaphragm assembly is arranged in the resonant cavity to separate the resonant cavity into a shape. A first cavity and a second cavity; the housing and the circuit board are arranged to jointly enclose a receiving cavity, and a MEMS microphone is arranged in the receiving cavity, and the MEMS microphone includes a base fixed on the circuit board and having a back cavity. a seat, a first vibrating film supported on the base, and a back plate; the base surrounds the through hole and makes the back cavity communicate with the through hole; the through hole connects the first cavity with the through hole The back cavity is communicated. Through the above structural design, the diaphragm assembly is accommodated in the resonant cavity of the circuit board, which saves space and facilitates production; and the MEMS microphone can better sense the vibration generated by the vibration assembly, and convert the induced vibration signal into an electrical signal, thereby It achieves better vibration response to both high-frequency vibration and low-frequency vibration transmitted by the resonant cavity, and effectively improves the sensitivity. Other than that, the basis is the same as that of the above-mentioned embodiment shown in FIG. 1 , and details are not repeated here.

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:

a circuit board, the circuit board encloses a resonant cavity, and one side of the circuit board is provided with a through hole passing through it;

a casing, the casing cover is fixed on the circuit board and covers the through hole, and the casing and the circuit board together form a receiving cavity;

A MEMS microphone, the MEMS microphone is accommodated in the accommodating cavity and is electrically connected to the circuit board, the MEMS microphone comprises a base fixed on the circuit board and having a back cavity, and is supported on the base away from a first diaphragm and a back plate at one end of the through hole; the base surrounds the through hole and makes the back cavity communicate with the through hole; the first diaphragm and the back plate are spaced apart forming a capacitive structure; and,

a diaphragm assembly, the diaphragm assembly is accommodated in the resonant cavity, and the resonant cavity is divided into a first cavity and a second cavity, and the first cavity is communicated with the back cavity through the through hole;

The casing is provided with a first pressure relief hole therethrough, 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 pressure relief hole. cavity communication;

When the vibration sensor inputs a vibration signal or a pressure signal, the diaphragm assembly vibrates and changes the air pressure in the resonant cavity.
The vibration sensor according to claim 1, wherein the vibration sensor further comprises an ASIC chip, and the ASIC chip is accommodated in the accommodation cavity and is electrically connected to the MEMS microphone.
The vibration sensor according to claim 1, 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 gasket fixed on the circuit board and disposed around the through hole, and a gasket fixed on a side of the gasket away from the through hole The second diaphragm, the gasket, the second diaphragm and the circuit board together form the first cavity, and the second pressure relief hole penetrates the second diaphragm.
The vibration sensor according to claim 4, wherein the diaphragm assembly further comprises a mass block fixedly connected with the second diaphragm; the mass block is attached to the second diaphragm close to the One side of the first cavity and/or the side of the second diaphragm close to the second cavity.
The vibration sensor according to claim 5, characterized in that, the mass blocks located on the same side of the second diaphragm comprise a plurality of mass block units spaced apart from each other.
The vibration sensor according to claim 4, wherein the diaphragm assembly further comprises a mass block wrapped and fixed by the second diaphragm.
The vibration sensor according to claim 7, wherein the second diaphragm includes two second sub-diaphragms fixed on the spacer and stacked on each other, and the mass block is sandwiched and wrapped around the two sub-diaphragms. between the second sub-diaphragms.
The vibration sensor according to claim 5, wherein the orthographic projection area of the first diaphragm on the circuit board along the vibration direction is smaller than that of the second diaphragm on the circuit board along the vibration direction orthographic projection area on .