CN209882085U - Electret bone conduction vibration microphone - Google Patents

Abstract

The utility model discloses an electret bone conduction vibration microphone, which comprises a shell, a vibration unit, an air medium pad, a fixed electrode, a conduction ring, an insulation ring and a PCBA, wherein the vibration unit comprises a stretched film ring, a vibration film arranged on the stretched film ring in a tensioning manner, and a gravity vibration block arranged on the vibration film; the gravity vibrating block is a circular or polygonal metal block, and a leakage hole for reducing acoustic resistance is formed in the gravity vibrating block. The utility model provides an electret bone conduction vibration microphone that can discernment human bone acoustic vibration, its advantage lies in: the electret microphone can be manufactured by using the existing electret microphone production process, can greatly attenuate environmental noise, can be manufactured into a fully-closed structure, improves the waterproof grade of the microphone, and can reduce the receiving of low-frequency signals caused by airflow and reduce the low-frequency sensitivity by the leakage holes.

Description

Electret bone conduction vibration microphone

Technical Field

The utility model relates to a sensing device technical field, concretely relates to electret bone conduction vibration microphone.

Background

Currently, a known electret microphone generally includes a case, a PCBA (Printed Circuit Board + Assembly), an insulating ring, a copper ring, a fixed electrode, an FEP (Fluorinated ethylene propylene copolymer) film, an air dielectric spacer, a diaphragm, a dust screen, and the like. The diaphragm consists of a tension ring and a vibration membrane and is a vibration unit of the microphone. The FEP film is an electret material, and is attached to a fixed electrode or a diaphragm, on which permanent charges reside. The fixed electrode and the diaphragm constitute a capacitor. When the sound wave signal is transmitted to the vibrating membrane, the vibrating membrane correspondingly vibrates, the vibration interval changes, the capacitance of the capacitor correspondingly changes, and therefore an electric signal synchronous with the sound signal is output for subsequent amplification processing and the like.

However, many acoustic noise signals are unrecognizable by electret microphones, and especially at high ambient noise, the information conveyed by the acoustic signals cannot be clearly distinguished. In addition, the existing microphone only adopts sealing treatment for waterproof treatment, reduces the permeation of water pressure to the inside so as to protect internal elements and electric potential from loss, but presents a contradiction phenomenon for the airflow transmission pushed by sound wave signals in the waterproof sealing process, and the higher the waterproof grade is, the greater the sound signal loss is. The water-proof structure can isolate and lose the sound signal outside the receiving unit and is easy to generate distortion.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide an electret bone conduction vibration microphone that can discernment human bone acoustic vibration. The utility model discloses a still lie in conveniently attenuating environmental noise by a wide margin, solve current microphone and be difficult to distinguish the not enough of useful sound signal source. The utility model discloses a still aim at improves the waterproof grade of microphone.

In order to achieve the above object, the present invention provides an electret bone conduction vibration microphone, which comprises a housing, a vibration unit, an air medium pad, a fixed electrode, a conduction ring, an insulation ring and a PCBA, wherein the vibration unit, the air medium pad, the fixed electrode, the conduction ring, the insulation ring and the PCBA are accommodated in the housing, the vibration unit comprises a tensioned membrane stretching ring, a vibration membrane arranged on the tensioned membrane stretching ring, and a gravity vibration block arranged on the vibration membrane; the gravity vibration block is a circular or polygonal metal block, and a leakage hole for reducing acoustic resistance is formed in the gravity vibration block; the shell bottom with constitute preceding sound chamber between the vibration unit, the vibration unit with constitute back sound chamber between the PCBA, preceding sound chamber's volume is less than the volume in back sound chamber.

In one implementation, the elastic diaphragm further comprises a metal backing ring accommodated in the shell and positioned between the bottom of the shell and the vibration unit, and the membrane tightening ring is electrically communicated with the shell through the metal backing ring. Optionally, a leakage groove for reducing acoustic resistance is formed in the metal backing ring, and the leakage groove is a notch of the metal backing ring.

In one implementation, the housing is a totally enclosed housing, or a pressure equalizing hole is formed in the bottom of the housing. And the pressure equalizing hole is reserved or closed after the electret bone conduction vibration microphone is processed.

According to the technical scheme, the utility model has the advantages of it is following:

(1) the electret bone conduction vibration microphone capable of recognizing the bone-sound vibration of the human body is provided, the electret bone conduction vibration microphone is formed by improving the traditional electret microphone, the existing mature electret microphone can be used for manufacturing, the structure is simple, a large amount of cost does not need to be increased, and use and safety risks do not exist.

(2) The utility model discloses an electret bone conduction vibration microphone mainly utilizes the acoustic signal vibration transmission, and the sensitivity output that the weakening air current arouses can be attenuated to environmental noise by a wide margin, solves current microphone and is difficult to distinguish the not enough of useful acoustic signal source.

(3) The utility model discloses an electret bone conduction vibration microphone does not rely on air current sound wave signal, can make into totally closed structure to improve the waterproof grade of microphone.

(4) The utility model discloses an electret bone conduction vibration microphone, the design has the hole of revealing on the gravity vibration piece of vibration unit for reduce the acoustic resistance, can reduce and receive the low frequency signal that arouses because of the air current, reduce the low frequency sensitivity.

(5) The utility model discloses a microphone can be used to reach the personal information identification of high accuracy through the algorithm of later stage development, as the new born strength of biological identification technique.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without inventive work.

Fig. 1 is a schematic structural view of an electret bone conduction vibration microphone according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a vibration unit according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a metal backing ring according to an embodiment of the present invention.

Detailed Description

In order to make the technical solution of the present invention better understood, the technical solution of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts shall belong to the protection scope of the present invention.

The terms "including" and "having," and any variations thereof, in the description and claims of this invention and the above-described drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.

The following will explain details by way of specific examples.

The embodiment of the utility model provides an electret bone conduction vibration microphone (hereinafter referred to as bone conduction microphone for short) that can discernment human bone acoustic vibration. The bone conduction microphone is improved on the basis of a traditional electret microphone. The main improvement is a vibration unit, and a gravity vibration block attached to a vibration membrane is additionally arranged in the vibration unit, so that the vibration unit can detect/pick up vibration signals and is used as a bone conduction vibration sensing device. In order to improve the performance of the bone conduction microphone, corresponding improvements are made on other aspects.

The technical idea of the utility model mainly lies in:

(1) a gravity vibrating block is added on the vibrating membrane, so that the vibrating unit can pick up a vibration signal. Moreover, a leakage hole (or called as a resistance reducing hole) which plays a role of vibration resistance reduction is formed on the gravity vibrating block, and a vibration elastic space is reserved between the gravity vibrating block and the film stretching ring; when the gravity vibrating block vibrates under the action of external force, the resistance is smaller, and therefore time delay and distortion are reduced.

(2) The metal backing ring with the leakage groove is additionally arranged at the bottom of the shell, the leakage groove can be used for reducing the vibration acoustic resistance of the gravity vibrating block and balancing the air pressure difference caused by vibration of the front surface and the back surface of the gravity vibrating block. When the low-frequency-range large-amplitude movement is carried out, part of sound pressure can flow to the reverse side of the gravity vibrating block through the leakage groove to form a pressure phase difference, and therefore resonance caused by sound wave compressed air when a user speaks is reduced. The metal backing ring is also used for raising the distance between the gravity vibrating block and the bottom of the shell, and the gravity vibrating block is prevented from colliding with the bottom of the shell when vibrating.

(3) The housing completely encloses or is designed with a pressure equalizing opening which should be much smaller than the sound opening in a conventional microphone housing. Through designing the pressure equalizing hole, the shell is sealed to be in the hole conducting state, can reduce the product and be heated the inside and outside pressure that arouses in the course of working. External sound pressure can also directly act on the gravity vibrating block through the pressure equalizing hole. The shell is totally closed or is designed to be a pressure equalizing hole far smaller than the sound hole, so that other interference signals except vibration can be reduced.

Referring to fig. 1 and 2, an embodiment of the present invention provides an electret bone conduction vibration microphone based on the above technical idea.

As shown in fig. 1, the bone conduction microphone includes a case 10 and a vibration unit, an air dielectric pad 2, a fixed electrode 8, a conductive ring 12, an insulating ring 11, and PCBA13, which are accommodated in the case 10. In this case, an electret material layer such as FEP film 6 may be selectively provided on the fixed electrode 8, and an impedance transformation IC (integrated circuit) 15 and a capacitor 14 may be provided on the PCBA.

As shown in fig. 2, the vibration unit comprises a tension ring 1, a vibration membrane 3 arranged on the tension ring 1 in a tensioned manner, and a gravity vibration block 4 arranged on the vibration membrane 3; the gravity vibrating block 4 is a circular or polygonal metal block, and a leakage hole 5 for reducing acoustic resistance is formed in the gravity vibrating block 4. Here, the electret material layer such as the FEP film 6 may be selectively provided on the diaphragm 3 instead of the fixed electrode 8.

As shown in fig. 1, the bone conduction microphone of the present invention has a housing 10 and a PCBA13 enclosing a receiving space, and a vibration unit, an air dielectric pad 2, a fixed electrode 8, a conducting ring 12, and an insulating ring 11 are all received inside the receiving space. Wherein, the vibration unit separates whole accommodation space into two sound chambeies, namely constitutes preceding sound chamber between shell 10 bottom and the vibration unit, constitutes the back sound chamber between vibration unit and PCBA13, and the volume in preceding sound chamber is far less than the volume in back sound chamber.

The following describes the functions and features of the components of the bone conduction microphone:

and the membrane stretching ring 1 is used for tensioning the vibrating membrane 3 and supporting the gravity vibrating block to do synchronous reciprocating motion. Can be made of metal materials. The outer shape may be circular or polygonal.

And the vibrating membrane 3 is tightened on the vibrating membrane ring 1 and is used for supporting the gravity vibrating block to vibrate synchronously.

And a gravity vibration block 4 attached to a central region of the diaphragm 3 for receiving external vibration energy to resonate and reciprocate. The gravity vibrating block can be made of metal materials with higher density, such as stainless steel, copper materials or steel sheets, and the like, and preferably materials which are not rusty and are easy to bond are selected. Optionally, the ratio of the diameter of the gravity vibrating mass 4 to the inner diameter of the bandage ring 1 is between 0.2 and 0.8, preferably between 0.5 and 0.8, in order to leave a suitable vibration-elastic space between the gravity vibrating mass 4 and the bandage ring 1. Optionally, the thickness ratio of the gravity vibrating mass 4 to the film stretching ring 1 is between 0.3 and 0.6, so as to avoid collision between the gravity vibrating mass 4 and the bottom of the casing 10 when vibrating.

And the leakage hole 5 is used for reducing the acoustic resistance of the vibration of the gravity vibrating block 4, reducing the pushing generated by low-frequency airflow and attenuating the low-frequency sensitivity. Optionally, the leakage hole 5 is disposed at a central position of the gravity vibration block 4 and penetrates through the gravity vibration block 4. Optionally, the diameter of the leakage hole is between 0.02 and 0.3 mm, so as to achieve a better drag reduction effect.

In some embodiments, the position of the diaphragm 3 corresponding to the leakage hole 5 may be correspondingly provided with a through hole. The through hole may have the same or smaller diameter than the leakage hole 5. The through hole is used for penetrating through the front sound cavity and the rear sound cavity so as to further reduce the acoustic resistance of the gravity vibrating block 4 to vibrate.

In some embodiments, the housing 10 is a fully enclosed housing without any openings. After the bone conduction microphone is processed, the shell 10 and the PCBA13 form a full sealing structure, and air flow can not enter the bone conduction microphone. At this time, the bone conduction microphone is only used to pick up a vibration signal.

In other embodiments, the bottom of the housing 10 is provided with a pressure equalizing hole 16. The pressure equalizing hole 16 may have a diameter of about 0.2 mm, for example between 0.05 and 0.3 mm, which is much smaller than the sound hole in a conventional microphone housing. The number of the pressure equalizing holes 16 may be one or plural. The pressure equalizing holes 16 serve to reduce/equalize the internal and external pressure of the product caused by heat during processing. The pressure equalizing hole 16 may optionally be left or closed after the bone conduction microphone has been machined. If closed, the bone conduction microphone becomes a fully sealed structure, only for picking up vibration signals. The pressure equalizing holes 16, if left, may also function as part of the sound holes, allowing air flow caused by external sound vibrations to enter, pushing the vibration unit to vibrate. However, since the vibration energy of the low-frequency noise signal is low, it is difficult to push the diaphragm to which the gravity vibrating mass is attached, and therefore, it is possible to avoid picking up the low-frequency noise signal.

In some embodiments, the bone conduction microphone further comprises a metal backing ring 17 accommodated in the housing 10 and located between the bottom of the housing 10 and the vibration unit, and the membrane tightening ring 1 is electrically communicated with the housing 10 through the metal backing ring 17. The metal backing ring 17 can be used for raising the distance between the gravity vibrating mass 4 and the bottom of the shell 10, and avoiding collision between the gravity vibrating mass 4 and the bottom of the shell 10 when vibrating.

Further, a leakage groove 9 for reducing acoustic resistance is formed in the metal backing ring 17, and the leakage groove 9 is a notch of the metal backing ring. As shown in fig. 3, is a schematic structural view of a metal backing ring 17 having a leakage groove 9. The leakage groove 9 can play a similar role as the leakage hole 5, and can reduce the vibration acoustic resistance of the gravity vibrating block 4. The leakage groove 9 can be communicated with the front sound cavity and the rear sound cavity and is used for balancing the air pressure difference caused by the vibration of the front surface and the back surface of the gravity vibrating block 4. When the low-frequency-range large-amplitude movement is carried out, part of sound pressure can flow to the reverse side of the gravity vibrating block 4 through the leakage groove 9 to form a pressure phase difference, and therefore resonance caused by sound wave compressed air when a user speaks is reduced.

The following explains the utility model discloses an electret bone conduction vibration sensor's theory of operation:

the whole vibration unit of the bone conduction microphone is sealed in a closed shell 10 and is isolated from the outside air, the only pressure equalizing hole 16 is used for balancing the pressure difference between the inside and the outside caused by heating and the like in the processing process, and the processing can be completely sealed, for example, the bone conduction microphone is sealed in the process of reflow soldering. After sealing, external wind-driven airflow and sound wave compressed air cannot directly act on the internal vibrating membrane 3 and the gravity vibrating block 4, so that the signal transmitted by air is weak.

When the bone conduction microphone receives a vibration signal provided from the outside, the vibration signal is transmitted to the internal gravity vibration block 4, and the gravity vibration block 4 is attached to the vibration membrane 3, so that the vibration damping of the vibration membrane 3 is small, and the vibration energy consistent with the external vibration frequency can be presented to enable the gravity vibration block 4 to do reciprocating motion.

In the vibration process, the leakage hole 5 and the leakage groove 9 are used as leakage channels for providing low-frequency large-amplitude pressure balance, the pressure on the vibrating membrane caused by airflow in the front sound cavity is reduced, and the noise can be reduced and the pressure difference between the front side and the back side of the vibrating membrane block can be balanced.

The reciprocating motion of the gravity vibrating block 4 causes the distance between the metal vibrating block 4 and the fixed electrode 8 to change synchronously with the vibration of external pushing energy due to the rigidity of the gravity vibrating block 4. The fixed electrode 8 and the metal vibrating block 4 form a plate capacitor, and the distance between the fixed electrode and the metal vibrating block is changed when the metal vibrating block vibrates, so that the capacitance of the plate capacitor is changed, and an alternating signal with the same frequency is obtained on the fixed electrode. The alternating signal is conducted to the PCBA13 through the conducting ring 12, causing the impedance transformation IC15 to work, and the capacitor 14 can bypass the useless high-frequency interference signal, reduce the radio frequency interference, and further output the electrical signal for the post-processing. Therefore, the process of sound-electricity energy conversion is realized, and the bone conduction vibration signal is converted into the electric signal.

It should be noted that in order to provide a better vibration unit structure, the applicant also designed various other structures for comparative verification.

In a comparative embodiment, the vibration unit comprises a stretching ring, a vibration membrane arranged on the stretching ring in a tensioning mode, a gravity vibration block arranged on the vibration membrane, and a fixing ring fixed on the vibration membrane and surrounding the gravity vibration block, wherein the gravity vibration block is not provided with a leakage hole.

This comparative example is also able to pick up the vibration signal, but it has the following drawbacks, as verified and analyzed: because set up solid fixed ring at the vibrating diaphragm, can produce acoustic interference, acoustic interference leads to the vibration signal to change into the distortion can appear in the signal of telecommunication. This is because the energy of vibration is low, and even contact interference causes large membrane-breaking noise. If the distance between the fixed ring and the vibrating block is increased, the fixing significance is not existed.

And the utility model discloses in the vibration unit, do not establish solid fixed ring, and set up the drag reduction hole in the middle of the gravity vibrating mass to acoustic resistance when reducing the vibration. By designing the resistance reducing holes, the acoustic resistance can be reduced, and the distortion can be reduced. If the resistance reducing holes are not arranged, when the vibration amplitude is large, the resistance change in the front sound cavity is too large, and distortion is easily generated. The arrangement of the drag reduction holes can help the low frequency extension of the product because the product receives vibration signals. For the pushing caused by the external airflow, the sensitivity is very low due to the resistance reducing holes, and the purpose of reducing wind-driven noise can be achieved.

As described above, embodiments of the present invention provide an electret bone conduction vibration microphone. The vibrating unit comprises a circular or polygonal stretched membrane ring, a vibrating membrane is arranged on the stretched membrane ring in a tensioning mode, a circular or polygonal gravity vibrating block is attached to the vibrating membrane, and a leakage hole used for reducing acoustic resistance is formed in the gravity vibrating block. The bone conduction vibration signal is picked up by the attached gravity vibration block. The leakage holes formed in the gravity vibrating block can reduce acoustic resistance and receive low-frequency signals caused by airflow. The leakage groove formed in the metal backing ring can further reduce acoustic resistance. The shell of the whole bone conduction microphone is provided with no hole or a tiny pressure equalizing hole, so that a sound pressure signal (airflow signal) directly acting on the vibration unit can be avoided or weakened.

The key technical points comprise that: 1. the vibration transmission of the acoustic signal is enhanced, and the sensitivity output caused by the air flow is weakened. 2. The low-frequency sensitivity is reduced by forming a reverse pressure difference through the leakage hole and the leakage groove. 3. The vibration unit for receiving the vibration signal can be sealed and waterproof, and a sound source air flow channel (sound hole) is not required.

To sum up, the utility model discloses a following technological effect:

(1) the electret bone conduction vibration microphone capable of recognizing the bone-sound vibration of the human body is formed by improving the traditional electret microphone, can be manufactured by utilizing the existing mature electret microphone production process, is simple in structure, does not need to increase a large amount of cost, and does not have use and safety risks.

(2) The utility model discloses a microphone mainly utilizes the acoustic signal vibration transmission, and the sensitivity output that the weakening air current arouses can be attenuated to environmental noise by a wide margin, solves current microphone and is difficult to distinguish the not enough of useful acoustic signal source.

(3) The utility model discloses a microphone does not rely on air current sound wave signal, can make into totally closed structure to improve the waterproof grade of microphone.

(4) The utility model discloses a microphone, the design has the hole of revealing (optional, and it has the groove of revealing still to design on the bottom metal backing ring) on its vibration unit's the gravity vibration piece for reduce the acoustic resistance, can reduce the low frequency signal that the receipt arouses because of the air current, reduce the low frequency sensitivity.

(5) The utility model discloses a microphone can be used to reach the personal information identification of high accuracy through the algorithm of later stage development, as the new born strength of biological identification technique.

In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to the related descriptions of other embodiments.

The above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; those of ordinary skill in the art will understand that: the technical solutions described in the above embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention in its corresponding aspects.

Claims (10)

1. The utility model provides an electret bone conduction vibration microphone, includes shell and holding vibration unit, air dielectric pad, fixed electrode, switch on ring, insulating ring and PCBA in the shell, its characterized in that:

the vibration unit comprises a stretched film ring, a vibration film arranged on the stretched film ring in a tensioning mode, and a gravity vibration block arranged on the vibration film; the gravity vibration block is a circular or polygonal metal block, and a leakage hole for reducing acoustic resistance is formed in the gravity vibration block;

the shell bottom with constitute preceding sound chamber between the vibration unit, the vibration unit with constitute back sound chamber between the PCBA, preceding sound chamber's volume is less than the volume in back sound chamber.

2. The electret bone conduction vibration microphone according to claim 1,

the leakage hole is formed in the center of the gravity vibrating block and penetrates through the gravity vibrating block.

3. The electret bone conduction vibration microphone according to claim 1,

the aperture of the leakage hole is between 0.02 and 0.3 mm.

4. The electret bone conduction vibration microphone according to claim 1,

and through holes are correspondingly formed in the positions, corresponding to the leakage holes, of the vibrating membrane.

5. The electret bone conduction vibration microphone according to claim 1,

the ratio of the diameter of the gravity vibrating block to the inner diameter of the film stretching ring is between 0.2 and 0.8.

6. The electret bone conduction vibration microphone according to claim 1,

the ratio of the thickness of the gravity vibrating mass to the thickness of the tension ring is between 0.3 and 0.6.

7. The electret bone conduction vibration microphone according to any one of claims 1 to 6,

the membrane stretching ring is electrically communicated with the shell through the metal backing ring.

8. The electret bone conduction vibration microphone according to claim 7,

the metal backing ring is provided with a leakage groove for reducing acoustic resistance, and the leakage groove is a notch of the metal backing ring.

9. The electret bone conduction vibration microphone according to any one of claims 1 to 6,

the shell is a totally-enclosed shell, or,

the bottom of the shell is provided with a pressure equalizing hole.

10. The electret bone conduction vibration microphone according to claim 9,

and the pressure equalizing hole is reserved or closed after the electret bone conduction vibration microphone is processed.