Patent Publication Number: US-11665494-B2

Title: Bone conduction microphone

Description:
FIELD OF THE PRESENT DISCLOSURE 
     The present invention relates to the technical field of electroacoustic transducers, and more particularly to a bone conduction microphone. 
     DESCRIPTION OF RELATED ART 
     The related bone conduction microphone usually converts the bone conduction signal into a pressure signal by setting a vibration membrane. Then the microphone is picked up and converted into electrical signals, thereby completing the process of sound collection. 
     However, the vibration membrane in the current bone conduction microphone requires an additional vent hole structure, and the manufacturing process is usually more complicated. 
     Therefore, it is necessary to provide an improved bone conduction microphone to solve the above-mentioned problems. 
     SUMMARY OF THE PRESENT INVENTION 
     One of the main objects of the present invention is to provide a bone conduction microphone with simplified structure and easier manufacturing process. 
     To achieve the above-mentioned objects, the present invention provides a bone conduction microphone, including: a housing; a circuit board opposite to the housing; and a vibration assembly locating between the housing and the circuit board. The vibration assembly includes a vibration membrane made of high temperature resistant dustproof breathable material, a weight fixed to the vibration membrane, and a first cavity formed between the vibration membrane and the circuit board. 
     The bone conduction microphone further includes a pressure assembly locating between the vibration assembly and the circuit board for detecting a pressure change generated in the first cavity and converting the pressure change into an electrical signal. 
     In addition, the bone conduction microphone further includes a bracket connecting the vibration membrane to the circuit board, wherein, the housing includes a main part and an extension part extending from the main part toward the pressure assembly. The vibration membrane locates between the extension part and the bracket. The circuit board, the bracket and the vibration membrane enclose for forming the first cavity. The main part, the extension part and the vibration membrane enclose for forming a second cavity which is acoustically connected to the first cavity through the vibration membrane. 
     In addition, the bone conduction microphone further includes a gasket locating between the vibration membrane and the bracket, and/or locating between the vibration membrane and the extension part. 
     In addition, the housing includes a first side facing the pressure assembly. The bone conduction microphone further includes a gasket between the first side surface and the vibration membrane. The housing, the gasket and the vibration membrane enclose for forming a second cavity. The first cavity and the second cavity are acoustically connected through the vibration membrane. 
     In addition, the bone conduction microphone further includes a gasket, wherein the housing includes a main part and an extension part extending from the main part toward the pressure assembly to the circuit board; the main part, the extension part and the circuit board enclose for forming a second cavity; the vibration membrane. The circuit board and the gasket enclose for forming the first cavity, and the first cavity and the second cavity are acoustically connected through the vibration membrane. 
     In addition, the gasket is made of elastic material or soft material. 
     In addition, the weight locates on a side of the vibration membrane away from the pressure assembly, and/or the weight locates on a side of the vibration membrane facing the pressure assembly. 
     In addition, the vibration membrane is made of dust-proof and breathable materials resistant to temperatures greater than 200° C. 
     In addition, the bone conduction microphone further includes least one vent hole in the housing. 
     In addition, the housing includes a sealer for sealing the vent hole. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the exemplary embodiments can be better understood with reference to the following drawings. The components in the drawing are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. 
         FIG.  1    is a cross-sectional view of a bone conduction microphone in accordance with a first embodiment of the present invention. 
         FIG.  2    is a cross-sectional view of a bone conduction microphone in accordance with a second embodiment of the present invention. 
         FIG.  3    is a cross-sectional view of a bone conduction microphone in accordance with a third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     The present disclosure will hereinafter be described in detail with reference to exemplary embodiments. To make the technical problems to be solved, technical solutions and beneficial effects of the present disclosure more apparent, the present disclosure is described in further detail together with the figures and the embodiments. It should be understood the specific embodiments described hereby are only to explain the disclosure, not intended to limit the disclosure. 
     Please refer to  FIG.  1   . A first embodiment of the present invention provides a bone conduction microphone  1 . The bone conduction microphone  1  includes a housing  10 , a circuit board  20  arranged opposite to the housing  10 , a vibration assembly  30  arranged between the housing  10  and the circuit board  20 , and a pressure assembly  40  arranged between the vibration assembly  30  and the circuit board  20 . The vibration assembly  30  includes a vibration membrane  32  and a weight  34  fixed to the vibration membrane  32 . The first cavity  50  is formed between the vibration membrane  32  and the circuit board  20 , and the pressure assembly  40  is used to detect the pressure change generated in the first cavity  50  and convert the pressure change into an electrical signal. 
     The weight  34  generates inertial vibration according to the vibration of the housing  10  or the circuit board  20 , which drives the vibration membrane  32  to vibrate, and the pressure in the first cavity  50  changes. The material of vibration membrane  32  is a high temperature resistant dustproof and breathable material. A high temperature resistant dust-proof and breathable material is arranged as the vibration membrane  32 , which can balance the air pressure and effectively prevent dust. Moreover, there is no need to open an additional vent hole structure on the vibration membrane  32 , which simplifies the manufacturing process of the vibration membrane  32 . 
     The material of the vibration membrane  32  is a breathable material. The air permeability of the vibration membrane  32  can meet the requirement of the circuit board  20  for reflow soldering air leakage. In the prior art, additional holes are usually provided on the vibration membrane to meet the leakage of the circuit board reflow soldering, and the manufacturing process of such a vibration membrane is more complicated. Compared with the prior art, the embodiment of the present invention chooses to adopt the vibration membrane  32  of breathable material. And the vibration membrane  32  with air permeability can leak air during reflow soldering. There is no need for additional openings on the vibration membrane  32  to satisfy reflow soldering leakage. the vibration membrane  32  is integrally formed, which simplifies the manufacturing process of the vibration membrane  32 . 
     In addition, the material of the vibration membrane  32  is a high temperature resistant material. Choosing the vibration membrane  32  made of high temperature resistant material can prevent the circuit board  20  from damaging the vibration membrane  32  during reflow soldering of the soldering device. In this way, the performance of the bone conduction microphone  1  produced is more stable. Exemplarily, considering that the temperature in the constant temperature zone during reflow soldering is about 200° C., the material of the vibration membrane  32  can be a material that can withstand temperatures greater than 200° C. 
     Further, the material of the vibration membrane  32  is a dustproof material, which can effectively prevent external dust from entering the first cavity  50 , thereby preventing external dust from affecting sound collection. 
     It should be noted that the material of the vibration membrane  32  of the embodiment of the present invention can only be a breathable material. High temperature resistant ventilating materials can also be used, and high temperature resistant and dust-proof ventilating materials can also be used. You can choose according to your needs when you use it to meet the requirements of different users. 
     In order to more clearly describe the bone conduction microphone  1  provided by the embodiment of the present invention, the structure of the bone conduction microphone  1  of the embodiment of the present invention will be described below with reference to the accompanying drawings. 
     Exemplarily, please continue to refer to  FIG.  1   , the bone conduction microphone  1  includes a vibration assembly  30 , a pressure assembly  40 , a chip  90 , and a gold wire  100 . The pressure assembly  40 , chip  90  and gold wire  100  are all set in the first cavity  50 . Chip  90  is electrically connected to pressure assembly  40  through gold wire  100 . 
     Wherein, the vibration assembly  30  can be used as a carrier of bone conduction signals to transmit the bone conduction signals to the bone conduction microphone  1 . The vibration assembly  30  includes a vibration membrane  32  and a weight  34 . The weight  34  is fixedly connected to the vibration membrane  32 , and the vibration membrane  32  is arranged between the housing  10  and the circuit board  20 . 
     The material of the vibration membrane  32  can be a high-temperature resistant dust-proof and breathable material to make the circuit board  20  out of air during the reflow soldering process. Of course, the material of the vibration membrane  32  is not limited to this, and the selection of the material of the vibration membrane  32  can refer to the above description, and will not be repeated. The weight  34  is a component with a certain mass, and the weight  34  can be square, round, special-shaped and other shapes. As shown in  FIG.  1   , weight  34  may be integrated. Of course, in some other embodiments, the weight can also be set in sections. 
     The weight  34  is fixedly connected to the vibration membrane  32  so that the weight  34  can drive the vibration membrane  32  to vibrate, so that the pressure assembly  40  picks up the vibration and converts it into an electrical signal. The projection of weight  34  on the vibration membrane  32  can be completely located within the vibration membrane  32 . That is to say, the area of the vibration membrane  32  is larger than the area of the weight  34 , and this setting can make the vibration membrane  32  have a ventilation margin. 
     The weight  34  can increase the amplitude of the vibration of the vibration membrane  32 , so that the pressure assembly  40  can detect the above-mentioned vibration. It should be noted that the weight  34  can be set above the vibration membrane  32 , that is, the side away from the pressure assembly  40 . The weight  34  can also be set below the vibration membrane  32 , that is, toward the side of the pressure assembly  40 . It is also possible to set a weight  34  above and below the vibration membrane  32 , as long as the weight  34  can increase the vibration amplitude of the vibration membrane  32 , and there is no limitation here. In  FIG.  1   , the weight  34  is arranged above the vibration membrane  32  for example. 
     The housing  10  may include a main part  11  and an extension part  12 . The extension part  12  extends from the main part  11  toward the direction of the pressure assembly  40  to form a housing  10  with an accommodation space. The main part  11  can be a square flat plate, and the extension part  12  extends from the periphery of the main part  11 . The housing  10  is also provided with at least one vent hole  14  for venting during reflow soldering during the manufacturing of the bone conduction microphone  1 . The number of vent hole  14  is not limited, as long as it meets the required venting requirements. For example, 9 vent holes  14  evenly distributed on main part  11  can be set to meet the air leakage requirement. 
     The size and shape of the vent hole  14  are not limited. For example, the vent hole  14  may be a circular hole with a diameter of 60 microns. For another example, the vent hole  14  may be a square hole of 40 μm×40 μm. Of course, the vent hole  14  can also have other shapes and other sizes, and no examples are given here. 
     It should be noted that after the bone conduction microphone  1  is manufactured, a sealer  15  can be set on the outer side of the housing  10  corresponding to each vent hole  14  position. The sealer  15  is used to seal the vent hole  14  to prevent external air from interfering with the vibration of the vibration membrane  32 . For example, sealer  15  can use tape, and use tape to block vent hole  14  to achieve a seal. 
     The main part  11 , extension part  12  and vibration membrane  32  enclose to form a second cavity  70 . The bone conduction microphone  1  also includes a bracket  60  connecting the vibration membrane  32  and the circuit board  20 . The vibration membrane  32  is arranged between the extension part  12  and the bracket  60 . 
     The circuit board  20 , the bracket  60  and the vibration membrane  32  enclose to form a first cavity  50 . A first cavity  50  and a second cavity  70  are formed on both sides of the vibration membrane  32 , respectively. And the first cavity  50  and the second cavity  70  are connected through the vibration membrane  32 . The setting of the first cavity  50  and the second cavity  70  can make the vibration membrane  32  have room for vibration. 
     The vibration membrane  32  adopts high temperature resistant dust-proof and breathable material and is arranged between the housing  10  and the circuit board  20 , so that the air pressure can be balanced and the sound collection performance of the bone conduction microphone  1  is better. 
     The circuit board  20  may also be referred to as a PCB (Printed Circuit Board, printed circuit board), which is a support for electronic components, and may also be understood as a carrier for electrical interconnection of electronic components. The circuit board  20  is arranged on the side of the vibration membrane  32  away from the housing  10 . The chip  90  and the pressure assembly  40  are arranged in the first cavity  50 . The chip  90  and the pressure assembly  40  are arranged on the circuit board  20  at intervals. Chip  90  and pressure assembly  40  are connected by gold wire  100 . Chip  90  is used to process the audio signal of pressure assembly  40 . 
     In addition, bone conduction microphone  1  also includes gasket  80 . The gasket  80  can be thin, and the gasket  80  can be made of elastic or soft materials. The gasket  80  can be set at the connecting position between the vibration membrane  32  and the bracket  60 . The gasket  80  can also be set at the position where the vibration membrane  32  and the extension part  12  are connected. It is also possible to set a gasket  80  at both the position where the vibration membrane  32  is connected to the housing  10  and the position where the vibration membrane  32  is connected to the bracket  60 . The gasket  80  is arranged at the position connected to the vibration membrane  32  to buffer and protect the vibration membrane  32 . 
     The pressure assembly  40  may adopt, but is not limited to, an MEMS (Micro-Electro-Mechanical System) microphone. When the bone conduction signal is transmitted to the product in the form of vibration acceleration, the weight  34  in the vibration assembly  30  undergoes relative displacement with the MEMS microphone due to inertial action. The first cavity  50  between the two is compressed and stretched, and the pressure changes periodically. The pressure signal is picked up by a high-sensitivity MEMS microphone and converted into an electrical signal. Since then, the sound signal collection process is completed. 
     The pressure assembly  40  may include a main body  41 , a back plate  42  and a diaphragm  43 . The back plate  42  includes a plurality of sound inlet holes, and the sound signal or vibration signal enters the pressure assembly  40  through the sound inlet hole. The diaphragm  43  is used to generate vibration according to the pressure change in the first cavity  50  to collect the pressure change. The pressure assembly  40  is connected to the circuit board  20  through the main body  41 . The circuit board  20 , the main body  41  and the diaphragm  43  surround a back cavity  44  forming a pressure assembly  40 . The back cavity  44  is used to provide a vibrating space when the diaphragm  43  vibrates to collect the pressure change in the first cavity  50 . 
     Chip  90  can use ASIC (Application Specific Integrated Circuit, application specific integrated circuit) chip, ASIC chip is usually designed according to specific user requirements and specific electronic system needs. Compared with general-purpose integrated circuits, ASICs have the advantages of smaller size, lower power consumption, high reliability, superior performance, strong confidentiality, and low cost in mass production. Chip  90  and pressure assembly  40  are connected through gold wire  100 , so that chip  90  can process the audio signal of pressure assembly  40 . In addition, the chip  90  and the pressure assembly  40  are approximately symmetrically arranged on the circuit board  20  to provide an external bias to the pressure assembly  40 . Such a setting can not only physically balance the pressure assembly  40  and chip  90  so that they will not deviate. Moreover, the pressure assembly  40  can maintain stable acoustic and electrical parameters during operation, thereby making the performance of the bone conduction microphone  1  of the embodiment of the present invention better. 
     It should be noted that the structure of the bone conduction microphone  1  provided by the embodiment of the present invention is not limited to the above-mentioned structure. 
     Exemplarily, please refer to  FIG.  2   . A bone conduction microphone provided by a second embodiment of the present invention. The bone conduction microphone  1  includes a housing  10 , a circuit board  20  arranged opposite to the housing  10 , a vibration assembly  30  arranged between the housing  10  and the circuit board  20 , and a pressure assembly arranged between the vibration assembly  30  and the circuit board  20 . The vibration assembly  30  includes a vibration membrane  32  and a weight  34  fixed to the vibration membrane  32 . The first cavity  50  is formed between the vibration membrane  32  and the circuit board  20 , and the pressure assembly  40  is used to detect the pressure change generated in the first cavity  50  and convert the pressure change into an electrical signal. 
     The weight  34  generates inertial vibration according to the vibration of the housing  10  or the circuit board  20 , and drives the vibration membrane  32  to vibrate to cause pressure changes in the first cavity  50 . The material of vibration membrane  32  is a high temperature resistant dustproof and breathable material. A high temperature resistant dust-proof and breathable material is arranged as the vibration membrane  32 , which can balance the air pressure and effectively prevent dust. Moreover, there is no need to open an additional vent hole structure on the vibration membrane  32 , which simplifies the manufacturing process of the vibration membrane  32 . The bone conduction microphone  1  also includes a chip  90  and a gold wire  100 . The pressure assembly  40 , chip  90  and gold wire  100  are all set in the first cavity  50 . Chip  90  is electrically connected to pressure assembly  40  through gold wire  100 . 
     Wherein, the vibration assembly  30  can be used as a carrier of bone conduction signals to transmit the bone conduction signals to the pressure assembly  40 . The vibration assembly  30  includes a vibration membrane  32  and a weight  34 . The weight  34  is fixedly connected to the vibration membrane  32 . The vibration membrane  32  is arranged between the housing  10  and the circuit board  20 . 
     Wherein, the description of vibration membrane  32  and weight  34  can refer to the structure shown in  FIG.  1   , which will not be repeated here. In  FIG.  2   , the weight  34  is arranged below the vibration membrane  32  as an example for illustration, and it should not be understood as a restriction on the location of the weight  34 . 
     The housing  10  includes a first side surface  13  facing the pressure assembly  40 . It can be understood that the first side  13  facing the pressure assembly  40  is the inner side of the housing  10 . The housing  10  also includes an main part  11  and an extension part  12 . The extension part  12  extends from the main part  11  toward the pressure assembly  40  to form an accommodation space for the housing  10 . 
     The housing  10  is also provided with at least one vent hole  14  and a sealer  15  for sealing the vent hole  14  for air leakage during reflow soldering during the manufacturing of the bone conduction microphone  1 . The vent hole  14  and the sealer  15  can refer to  FIG.  1    and the above description of the vent hole  14  and the sealer  15 , which will not be repeated here. 
     The extension part  12  of the housing  10  is connected to the circuit board  20 . The vibration assembly  30  may also include a bracket  60 , and the bracket  60  may be set between the extension part  12  and the circuit board  20 . It should be noted that the extension part  12  of the housing  10  can be directly connected to the circuit board  20 , or a bracket  60  can be added to connect the extension part  12  to the circuit board  20 . The embodiment of the present invention is described by taking the addition of a bracket  60  as an example. The vibration membrane  32 , the extension part  12 , the bracket  60  and the circuit board  20  enclose to form a first cavity  50 . Both the pressure assembly  40  and the chip  90  are set in the first cavity  50 . The chip  90  and the pressure assembly  40  are arranged on the circuit board  20  at intervals. 
     The bone conduction microphone  1  also includes a gasket  80 , which can be thin. The gasket  80  can be made of elastic material or soft material. The vibration membrane  32  is arranged in the containing space of the housing  10 . In addition, the vibration membrane  32  is connected to the first side surface  13  of the housing  10  through a gasket  80 . The vibration membrane  32 , main part  11  and the gasket  80  enclose to form a second cavity  70 . A first cavity  50  and a second cavity  70  are formed on both sides of the vibration membrane  32 , respectively. The first cavity  50  and the second cavity  70  are connected through a vibration membrane  32 . The setting of the first cavity  50  and the second cavity  70  can make the vibration membrane  32  have room for vibration. The vibration membrane  32  is made of high-temperature resistant dust-proof and breathable material and is arranged between the housing  10  and the circuit board  20 , which can balance the air pressure and make the sound collection performance of the bone conduction microphone  1  better. 
     The pressure assembly  40  can be, but is not limited to, an MEMS microphone. When the bone conduction signal is transmitted to the product in the form of vibration acceleration, the weight  34  in the vibration assembly  30  undergoes relative displacement with the MEMS microphone due to inertial action. The first cavity  50  between the two is compressed and stretched, and the pressure changes periodically. The pressure signal is picked up by a high-sensitivity MEMS microphone and converted into an electrical signal. Since then, the sound signal collection process is completed. Chip  90  and pressure assembly  40  are connected through gold wire  100 , so that chip  90  can process the audio signal of pressure assembly  40 . For the description of the pressure assembly  40  and chip  90 , refer to  FIG.  1    and the above description, which will not be repeated here. 
     Exemplarily, please refer to  FIG.  3   . A bone conduction microphone provided by a third embodiment of the present invention. The bone conduction microphone  1  includes a housing  10 , a circuit board  20  arranged opposite to the housing  10 , a vibration assembly  30  arranged between the housing  10  and the circuit board  20 , and a pressure assembly arranged between the vibration assembly  30  and the circuit board  20 . The vibration assembly  30  includes a vibration membrane  32  and a weight  34  fixed to the vibration membrane  32 . A first cavity  5  is formed between the vibration membrane  32  and the circuit board  20 . 
     The pressure assembly  40  is used to detect the pressure change generated in the first cavity  50  and convert the pressure change into an electrical signal. The weight  34  generates inertial vibration according to the vibration of the housing  10  or the circuit board  20 , and drives the vibration membrane  32  to vibrate to cause pressure changes in the first cavity  50 . The material of vibration membrane  32  is a high temperature resistant dustproof and breathable material. A high temperature resistant dust-proof and breathable material is arranged as the vibration membrane  32 , which can balance the air pressure and effectively prevent dust. 
     Moreover, there is no need to open an additional vent hole structure on the vibration membrane  32 , which simplifies the manufacturing process of the vibration membrane  32 . The bone conduction microphone  1  also includes a chip  90  and a gold wire  100 . The pressure assembly  40  is arranged in the first cavity  50 . Chip  90  is electrically connected to pressure assembly  40  through gold wire  100 . 
     Wherein, the vibration assembly  30  can be used as a carrier of bone conduction signals to transmit the bone conduction signals to the pressure assembly  40 . The vibration assembly  30  includes a vibration membrane  32  and a weight  34 . The weight  34  is fixedly connected to the vibration membrane  32 , and the vibration membrane  32  is arranged between the housing  10  and the circuit board  20 . 
     The material of the vibration membrane  32  of the embodiment of the present invention can be a high-temperature resistant dust-proof and breathable material, so as to make the circuit board  20  vented during the reflow soldering process. The selection of the material of the vibration membrane  32  can refer to the above description, and will not be repeated. The weight  34  is a component with a certain mass, and the weight  34  can be square, round, special-shaped and other shapes. For the design of weight  34 , reference may be made to the introduction of weight  34  in  FIG.  1   , which will not be repeated here. 
     The housing  10  includes a main part  11  and an extension part  12 . The extension part  12  extends from the main part  11  toward the direction of the pressure assembly  40  to form a housing  10  with an accommodation space. The main part  11  can be a square flat plate, and the extension part  12  extends from the periphery of the main part  11 . The extension part  12  is connected to the periphery of the circuit board  20 . The main part  11 , the extension part  12  and the circuit board  20  enclose to form a second cavity  70 . The chip  90  and the vibration assembly  30  are both set in the second cavity  70 . And the pressure assembly  40  is arranged in the first cavity  50 . 
     The housing  10  is also provided with at least one vent hole  14  and a sealer  15  for sealing the vent hole  14 . The vent hole  14  and the sealer  15  can refer to  FIG.  1    and the above description of the vent hole  14  and the sealer  15 , which will not be repeated here. 
     The bone conduction microphone  1  also includes a gasket  80 . The vibration membrane  32  can be connected to the circuit board  20  through the gasket  80 . The vibration membrane  32 , the gasket  80  and the circuit board  20  are enclosed to form a first cavity  50 . The pressure assembly  40  is arranged in the first cavity  50 . The chip  90  is arranged in the second cavity  70  and is separated from the pressure assembly  40  by a gasket  80 . Chip  90  and pressure assembly  40  are connected through gold wire  100  and circuit board  20 . 
     The pressure assembly  40  can be, but is not limited to, an MEMS microphone. When the bone conduction signal is transmitted to the product in the form of vibration acceleration, the weight  34  in the vibration assembly  30  undergoes relative displacement with the MEMS microphone due to inertial action. The first cavity  50  between the two is compressed and stretched, and the pressure changes periodically. The pressure signal is picked up by a high-sensitivity MEMS microphone and converted into an electrical signal. Since then, the sound signal collection process is completed. Chip  90  and pressure assembly  40  are connected through gold wire  100 , so that chip  90  can process the audio signal of pressure assembly  40 . For the description of the pressure assembly  40  and chip  90 , refer to  FIG.  1    and the above description, which will not be repeated here. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present exemplary embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms where the appended claims are expressed.