Sound pickup device

Abstract

A sound pickup device (1) comprises a diaphragm (102) that vibrates in response to the acoustic pressure of an inputted sound, an acoustic member (11) having a sound channel (131) that is formed in order to guide a sound to the diaphragm (102), and a Helmholtz resonator (14) having an opening (143) formed on a wall surface that encloses the sound channel (131). The diaphragm (102) is arranged in the inside of a microphone (10) in which a sound hole (101) is formed. The acoustic member (11) includes: a first substrate (12) having a through-hole (121) formed at the same position as the sound hole (101), said first substrate (12) being attached to the microphone (10); and a second substrate (13) having a sound channel (131) formed at a position that corresponds to the through-hole (121), said second substrate (13) being attached to the first substrate (12).

Description

Technical Field

[0001] The present disclosure relates to a technique for sound collection using a microphone.

Background Art

[0002] In recent years, MEMS (Micro Electro Mechanical Systems) microphones have become widespread, replacing electret condenser microphones (ECMs).

[0003] MEMS microphones are characterized by being miniaturizable and having high heat resistance, enabling reflow mounting. Therefore, MEMS microphones are used in sound collection devices such as smartphones and smart speakers.

[0004] As the diaphragm of MEMS microphones is miniaturized, they have sensitivity up to the ultrasonic band of about 100 kHz and are used for ultrasonic sensing or high-resolution music recording. However, MEMS microphones may have peaks in the ultrasonic band due to acoustic factors (sound holes, front volume, and resonance of the diaphragm). Therefore, MEMS microphones have the problem that flat frequency characteristics cannot be obtained due to the peaks generated in this ultrasonic band.

[0005] Also, the maximum signal level of a microphone amplifier, analog-digital conversion circuit, or digital arithmetic processing device needs to be designed according to the peak frequency. Therefore, MEMS microphones have the problem that the signal-to-noise ratio deteriorates outside the peak frequency.

[0006] To solve this problem, for example, the electronic device shown in Patent Document 1 has a housing provided with holes, a substrate disposed inside the housing, a microphone disposed at a position corresponding to the holes of the housing, a partition wall disposed between the substrate and the housing to surround the periphery of the microphone, and a sound-absorbing material disposed in a space partitioned by the substrate, the partition wall, and the housing to cover the microphone.

[0007] However, in the above conventional technology, there is a possibility that the sensitivity may decrease in the entire frequency band, and further improvement has been required.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

[0009] The present disclosure has been made to solve the above problems, and an object thereof is to provide a technology capable of reducing peaks generated in the ultrasonic band and preventing a decrease in sensitivity in the entire frequency band.

[0010] The sound collection device according to one aspect of the present disclosure includes a diaphragm that vibrates in response to the sound pressure of an input sound, an acoustic member having a sound path formed to guide the sound to the diaphragm, and a resonator having an opening formed in a wall surface surrounding the sound path.

[0011] According to the present disclosure, it is possible to reduce peaks generated in the ultrasonic band and prevent a decrease in sensitivity in the entire frequency band.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0013] (Findings underlying the present disclosure) In the above conventional electronic device, since the microphone is covered with a sound-absorbing material, there is a risk that the sensitivity may decrease in the entire frequency band. In addition, since the sound-absorbing material may cause a more significant decrease in sensitivity at higher frequencies, it is difficult to achieve high-sensitivity sound collection in the ultrasonic band.

[0014] In order to solve the above problems, a sound collection device according to an aspect of the present disclosure includes a diaphragm that vibrates in response to the sound pressure of an input sound, an acoustic member having a sound path formed to guide the sound to the diaphragm, and a resonator having an opening formed in a wall surface surrounding the sound path.

[0015] According to this configuration, the resonator has an opening formed in a wall surface surrounding the sound path for guiding the sound to the diaphragm. The sound passing through the sound path enters the resonator from the opening. The resonator has a peak in the sound absorption rate near its resonance frequency. Therefore, by designing the resonator so that the resonance frequency becomes a specific peak frequency generated in the ultrasonic band, the peak generated in the ultrasonic band can be reduced, and the frequency characteristics can be made substantially flat. In addition, since the sound path for guiding the sound to the diaphragm is not provided with a sound-absorbing material for absorbing the sound, it is possible to prevent the sensitivity from decreasing in the entire frequency band.

[0016] Further, in the above sound collection device, the resonator may be a Helmholtz resonator.

[0017] According to this configuration, by changing the shape of the Helmholtz resonator, it is possible to easily reduce the peak of a desired frequency.

[0018] Also, in the above-described sound collection device, the diaphragm is disposed inside a microphone in which a sound hole is formed, the acoustic member has a through hole formed at the same position as the sound hole, and includes a first acoustic member attached to the microphone, and a second acoustic member having the sound path formed at a position corresponding to the through hole and attached to the first acoustic member, and the resonator may be formed in a direction perpendicular to a wall surface surrounding the sound path.

[0019] According to this configuration, the sound that enters from the entrance of the sound path of the second acoustic member passes through the sound path, the through hole of the first acoustic member, and the sound hole of the microphone, and is guided to the diaphragm inside the microphone. On the other hand, the sound that enters from the entrance of the sound path is also guided into the resonator formed in a direction perpendicular to the wall surface surrounding the sound path. Therefore, the resonator formed in the second acoustic member can reduce the peak generated in the ultrasonic band and make the frequency characteristics substantially flat.

[0020] Also, in the above-described sound collection device, the diaphragm is disposed inside a microphone in which a sound hole is formed, and further includes a substrate on which the microphone is mounted such that a surface facing the surface on which the sound hole is formed is in contact, the acoustic member has a through hole formed at the same position as the sound hole, and includes a first acoustic member attached to the microphone, and a second acoustic member having the sound path formed at a position corresponding to the through hole and attached to the first acoustic member, and the resonator may be formed in a direction perpendicular to a wall surface surrounding the sound path.

[0021] According to this configuration, even in a top port type microphone in which a sound hole is formed on a surface facing the surface in contact with the substrate, the resonator formed in the second acoustic member can reduce the peak generated in the ultrasonic band and make the frequency characteristics substantially flat.

[0022] Also, in the above-described sound collection device, the sound path of the second acoustic member may be formed in a tapered shape from the sound input port toward the inside of the sound path.

[0023] According to this configuration, since the sound path is formed in a tapered shape from the sound input port toward the inside of the sound path, the sound path becomes wider, and changes in the high-frequency characteristics of the sound can be reduced.

[0024] Further, in the above-described sound collection device, the diaphragm is disposed inside a microphone in which a sound hole is formed, the acoustic member is disposed between the sound hole and the diaphragm, and the resonator may be formed in a direction perpendicular to a wall surface surrounding the sound path.

[0025] According to this configuration, since the resonator is formed inside the microphone, the sound collection device can be miniaturized.

[0026] Further, in the above-described sound collection device, the resonator may include a neck portion formed around the sound path and having a space with a first volume, and a cavity portion formed around the neck portion and having a space with a second volume larger than the first volume.

[0027] According to this configuration, by designing the first volume of the neck portion and the second volume of the cavity portion so that the resonance frequency approaches the peak frequency to be reduced, the peak at the desired frequency can be reduced.

[0028] Further, in the above-described sound collection device, the neck portion may be an annular space surrounding the sound path, and the cavity portion may be an annular space surrounding the neck portion.

[0029] According to this configuration, by cutting the periphery of the sound path into an annular shape, the neck portion is formed, and by further cutting the periphery of the neck portion into an annular shape, the cavity portion is formed, so that the resonator can be easily formed.

[0030] Further, in the above-described sound collection device, the neck portion may be a tubular space extending radially from the wall surface of the sound path, and the cavity portion may be an annular space surrounding the neck portion.

[0031] According to this configuration, by changing the number of neck portions, the degrees of freedom in designing the resonance frequency and the sharpness of the signal characteristics of the resonance frequency can be improved. Further, by including a plurality of neck portions having different cross-sectional areas of the openings in the resonator, peaks at a plurality of frequencies can be reduced.

[0032] Further, in the above-described sound collection device, the neck portion may be a tubular space extending radially from the wall surface of the sound path, and the cavity portion may be provided separately from the neck portion.

[0033] According to this configuration, by changing the number of neck portions and cavity portions, the degrees of freedom in designing the resonance frequency and the sharpness of the signal characteristics of the resonance frequency can be improved. Further, by including a plurality of neck portions having different cross-sectional areas of the openings in the resonator, peaks at a plurality of frequencies can be reduced. Further, by including a plurality of cavity portions having different volumes in the resonator, peaks at a plurality of frequencies can be reduced.

[0034] Further, in the above-described sound collection device, a sound absorption material disposed inside at least one of the neck portion and the cavity portion may be further provided.

[0035] According to this configuration, by disposing the sound absorption material inside at least one of the neck portion and the cavity portion of the resonator, the sharpness of the signal characteristics of the resonance frequency can be controlled.

[0036] Further, in the above-described sound collection device, the resonator may include a first resonator formed in a direction perpendicular to the wall surface surrounding the sound path, and a second resonator formed outside the first resonator and having an opening connected to the first resonator.

[0037] According to this configuration, by forming the first resonator and the second resonator having different resonance frequencies from each other, peaks at a plurality of frequencies can be reduced.

[0038] Further, in the above-described sound collection device, the microphone may be a MEMS (Micro Electro Mechanical Systems) microphone.

[0039] According to this configuration, even in a MEMS microphone that can be miniaturized and can be reflow-mounted, the resonator can reduce the peak generated in the ultrasonic band, and the frequency characteristics can be made substantially flat.

[0040] Further, in the above-described sound collection device, the diaphragm is disposed inside the microphone in which sound holes are formed, the acoustic member has the sound path formed at a position corresponding to the sound holes, a first acoustic member attached to the microphone, and a second acoustic member attached to the first acoustic member and having a through hole formed at the same position as the sound input port of the sound path. The resonator may be formed in a direction perpendicular to the wall surface surrounding the sound path.

[0041] According to this configuration, the sound that enters from the through hole of the second acoustic member passes through the through hole of the second acoustic member, the sound path of the first acoustic member, and the sound holes of the microphone, and is guided to the diaphragm inside the microphone. On the other hand, the sound that enters from the entrance of the sound path is also guided into the resonator formed in a direction perpendicular to the wall surface surrounding the sound path. Therefore, the resonator formed in the first acoustic member can reduce the peak generated in the ultrasonic band, and the frequency characteristics can be made substantially flat.

[0042] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that the following embodiments are an example of embodying the present disclosure and do not limit the technical scope of the present disclosure.

[0043] (Embodiment 1) FIG. 1 is a cross-sectional view showing the configuration of the sound collection device according to Embodiment 1 of the present disclosure.

[0044] The sound collection device 1 shown in FIG. 1 includes a microphone 10, an acoustic member 11, and a Helmholtz resonator 14.

[0045] The microphone 10 is a MEMS microphone. The microphone 10 includes an electronic component and a cover that covers the electronic component. A sound hole 101 for guiding sound into the microphone 10 is formed in the cover. The electronic component includes, for example, a diaphragm 102 and an audio amplifier (not shown). The microphone 10 includes a diaphragm 102. The diaphragm 102 vibrates according to the sound pressure of the input sound. The cross section of the sound hole 101 is, for example, circular.

[0046] A MEMS microphone in which the sound hole 101 is formed on the side of the first substrate 12 below the microphone 10 is called a bottom port type MEMS microphone. Also, a MEMS microphone in which the sound hole 101 is formed in the cover above the microphone 10 is called a top port type MEMS microphone. The microphone 10 in the first embodiment is a bottom port type MEMS microphone.

[0047] The diaphragm 102 is disposed inside the microphone 10 in which the sound hole 101 is formed. The diaphragm 102 vibrates due to the sound pressure of the sound input from the sound hole 101. The diaphragm 102 forms a capacitor together with a counterposed back electrode (back plate). When the diaphragm 102 vibrates due to the sound pressure, the capacitance of the capacitor changes. The changed capacitance is converted into an electrical signal. The converted electrical signal is amplified by an audio amplifier and output to the outside.

[0048] The acoustic member 11 has a sound path 131 formed to guide sound to the diaphragm 102. The acoustic member 11 includes a first substrate 12 and a second substrate 13.

[0049] The first substrate 12 has a through hole 121 formed at the same position as the sound hole 101 and is attached to the microphone 10. Note that the first substrate 12 is an example of a first acoustic member. The first substrate 12 may be a rigid substrate or a flexible substrate. The microphone 10 is mounted on one surface of the first substrate 12. The cross section of the through hole 121 is, for example, circular. It is preferable that the diameter of the through hole 121 is the same as the diameter of the sound hole 101 of the microphone 10.

[0050] The second substrate 13 has a sound path 131 formed at a position corresponding to the through hole 121 and is attached to the first substrate 12. Note that the second substrate 13 is an example of a second acoustic member. The second substrate 13 may be a housing of an electric device including the sound collection device 1. Also, the second substrate 13 may be an elastic member for suppressing vibration. The other surface of the first substrate 12 is bonded to the surface of the second substrate 13 on which the Helmholtz resonator 14 is formed.

[0051] The Helmholtz resonator 14 has an opening 143 formed in a wall surface surrounding the sound path 131. The Helmholtz resonator 14 is formed in a direction perpendicular to the wall surface surrounding the sound path 131. The Helmholtz resonator 14 is an example of a resonator.

[0052] The Helmholtz resonator 14 includes a neck portion 141 and a cavity portion 142. The neck portion 141 is formed around the sound path 131 and has a space with a first volume. The cavity portion 142 is formed around the neck portion 141 and has a space with a second volume larger than the first volume. The Helmholtz resonator 14 resonates with sound of a specific frequency and mainly reduces peaks generated in the ultrasonic band. The cross-sectional area of the opening 143 of the neck portion 141, the length of the neck portion 141, and the volume of the cavity portion 142 are determined so that the peak is reduced by the resonance frequency.

[0053] The neck portion 141 is an annular space surrounding the sound path 131. The cavity portion 142 is an annular space surrounding the neck portion 141.

[0054] Here, a method for forming the Helmholtz resonator 14 on the second substrate 13 will be described with reference to FIG. 2.

[0055] FIG. 2 is a view of the second substrate in Embodiment 1 of the present disclosure as seen from above.

[0056] First, through holes are formed in the thickness direction of the second substrate 13. The through holes formed in the second substrate 13 are the sound channels 131. The cross-sections of the open ends on the input side and the output side of the sound channel 131 are circular. The sound channel 131 is cylindrical. It is preferable that the diameters of the open ends on the input side and the output side of the sound channel 131 are the same as the diameter of the through hole 121 in the first substrate 12.

[0057] Next, an annular region from the outer edge of the sound channel 131 to a position corresponding to the horizontal length of the neck portion 141 is cut from the surface of the second substrate 13 to a position at a predetermined depth. Thereby, the neck portion 141 is formed.

[0058] Next, an annular region from the outer edge of the neck portion 141 to a position corresponding to the horizontal length of the cavity portion 142 is cut from the surface of the second substrate 13 to a position at a predetermined depth. Thereby, the cavity portion 142 is formed. Note that the depth from the surface of the second substrate 13 in the cavity portion 142 is deeper than the depth from the surface of the second substrate 13 in the neck portion 141.

[0059] Note that the neck portion 141 and the cavity portion 142 of the Helmholtz resonator 14 may be formed by resin transfer processing instead of the above-described cutting process.

[0060] Next, the surface of the first substrate 12 that faces the surface on which the microphone 10 is mounted (i.e., the surface on which the microphone 10 is not mounted) is bonded to the surface of the second substrate 13 on which the Helmholtz resonator 14 is formed. At this time, the first substrate 12 and the second substrate 13 are bonded together so that the central axis of the through-hole 121 of the first substrate 12 coincides with the central axis of the sound path 131 of the second substrate 13. Thereby, a Helmholtz resonator 14 is formed between the first substrate 12 and the second substrate 13.

[0061] FIG. 3 is a diagram showing the frequency characteristics of the sound collection device without the second substrate, the frequency characteristics of the sound path of the second substrate, and the frequency characteristics of the sound collection device with the second substrate in Embodiment 1 of the present disclosure. In FIG. 3, the horizontal axis represents the frequency, and the vertical axis represents the relative sensitivity.

[0062] As shown in FIG. 3, when the sound collection device 1 does not include the second substrate 13 and includes only the first substrate 12, the frequency characteristics 301 of the sound collection device 1 have a peak in the ultrasonic band of 20 kHz or higher. On the other hand, the frequency characteristics 302 of the sound path 131 of the second substrate 13 including the Helmholtz resonator 14 absorb sounds of specific frequencies in the ultrasonic band of 20 kHz or higher due to the resonance of the Helmholtz resonator 14. Therefore, when the sound collection device 1 includes the second substrate 13 including the Helmholtz resonator 14, the peak generated in the ultrasonic band of 20 kHz or higher in the frequency characteristics 303 of the sound collection device 1 is reduced and becomes substantially flat.

[0063] According to Embodiment 1, the Helmholtz resonator 14 has an opening 143 formed in a wall surface surrounding a sound path 131 for guiding sound to the diaphragm 102. The sound passing through the sound path 131 enters the Helmholtz resonator 14 from the opening 143. The Helmholtz resonator 14 has a peak in the sound absorption rate near its resonance frequency. Therefore, by designing the Helmholtz resonator 14 so that the resonance frequency becomes a specific peak frequency generated in the ultrasonic band, the peak generated in the ultrasonic band can be reduced, and the frequency characteristics can be made substantially flat. Further, since no sound absorbing material is provided in the sound path 131 for guiding sound to the diaphragm 102, it is possible to prevent a decrease in sensitivity in the entire frequency band.

[0064] Subsequently, various modifications of the shape of the Helmholtz resonator 14 in Embodiment 1 will be described.

[0065] FIG. 4 is a view of the second substrate in Modification 1 of Embodiment 1 of the present disclosure as viewed from above.

[0066] The Helmholtz resonator 14 in Modification 1 of Embodiment 1 includes at least one neck portion 141 and a cavity portion 142. The at least one neck portion 141 is a tubular space extending radially from the wall surface of the sound path 131. Note that the Helmholtz resonator 14 in Modification 1 of Embodiment 1 includes four neck portions 141. The cavity portion 142 is an annular space surrounding the at least one neck portion 141. One open end of the at least one neck portion 141 is connected to the sound path 131, and the other open end of the at least one neck portion 141 is connected to the cavity portion 142.

[0067] The cross-sectional shape of the opening 143 of the neck portion 141 may be a quadrilateral, and the neck portion 141 may be a prismatic shape. Further, the cross-sectional shape of the opening 143 of the neck portion 141 may be circular, and the neck portion 141 may be a cylindrical shape. Furthermore, the neck portion 141 may be a fan shape that gradually expands from the open end connected to the sound path 131 toward the open end connected to the cavity portion 142.

[0068] Note that the number of the neck portions 141 is not limited to four. For example, when the number of the neck portions 141 decreases, the signal characteristics of the resonance frequency become steeper, and when the number of the neck portions 141 increases, the signal characteristics of the resonance frequency become gentler. Therefore, the Helmholtz resonator 14 may include the number of neck portions 141 corresponding to the sharpness (i.e., Q value) of the signal characteristics of the peak frequency to be reduced. Further, the Helmholtz resonator 14 may include a plurality of neck portions 141 having different cross-sectional areas of the openings 143 according to the number of frequencies for which the peaks are to be reduced.

[0069] In Modification Example 1 of Embodiment 1, by changing the number of the neck portions 141, the design freedom of the resonance frequency and the sharpness of the signal characteristics of the resonance frequency can be improved. Further, since the Helmholtz resonator 14 includes a plurality of neck portions 141 having different cross-sectional areas of the openings 143, the peaks of a plurality of frequencies can be reduced. Further, since the area where the first substrate 12 and the second substrate 13 are in contact becomes larger, the support strength of the first substrate 12 can be increased. As a result, the vibration of the microphone 10 can be suppressed. In particular, the shape of the Helmholtz resonator 14 in Modification Example 1 of the present Embodiment 1 exhibits a more remarkable effect when the first substrate 12 is thin like a flexible substrate.

[0070] FIG. 5 is a view of the second substrate in Modification Example 2 of Embodiment 1 of the present disclosure as viewed from above.

[0071] In Modification 2 of Embodiment 1, the Helmholtz resonator 14 includes at least one neck portion 141 and at least one cavity portion 142. At least one neck portion 141 is a tubular space extending radially from the wall surface of the sound path 131. At least one cavity portion 142 is provided separately from at least one neck portion 141. Note that the Helmholtz resonator 14 in Modification 2 of Embodiment 1 includes four neck portions 141 and four cavity portions 142. One open end of at least one neck portion 141 is connected to the sound path 131, and the other open end of at least one neck portion 141 is connected to the cavity portion 142.

[0072] The cross-sectional shape of the opening 143 of the neck portion 141 may be a quadrilateral, and the neck portion 141 may be a prismatic shape. Also, the cross-sectional shape of the opening 143 of the neck portion 141 may be circular, and the neck portion 141 may be a cylindrical shape.

[0073] The cross-sectional shape of the cavity portion 142 may be a quadrilateral, and the cavity portion 142 may be a prismatic shape. Also, the cross-sectional shape of the cavity portion 142 may be circular, and the cavity portion 142 may be a cylindrical shape. Also, the cavity portion 142 may be spherical.

[0074] Note that the number of the neck portions 141 and the cavity portions 142 is not limited to four. For example, when the number of the neck portions 141 and the cavity portions 142 decreases, the signal characteristics of the resonance frequency become steep, and when the number of the neck portions 141 and the cavity portions 142 increases, the signal characteristics of the resonance frequency become gentle. Therefore, the Helmholtz resonator 14 may include the neck portions 141 and the cavity portions 142 in a number corresponding to the sharpness (i.e., Q value) of the signal characteristics of the peak frequency to be reduced. Also, the Helmholtz resonator 14 may include a plurality of neck portions 141 having different cross-sectional areas of the opening 143 and a plurality of cavity portions 142 having different volumes according to the number of frequencies for which the peak is to be reduced.

[0075] In Modification 2 of Embodiment 1, by changing the number of the neck portion 141 and the cavity portion 142, the degree of freedom in designing the resonance frequency and the sharpness of the signal characteristics of the resonance frequency can be improved. Further, by including a plurality of neck portions 141 having different cross-sectional areas of the opening 143 in the Helmholtz resonator 14, peaks at a plurality of frequencies can be reduced. Further, by including a plurality of cavity portions 142 having different volumes in the Helmholtz resonator 14, peaks at a plurality of frequencies can be reduced. Further, since the area where the first substrate 12 and the second substrate 13 are in contact becomes larger, the support strength of the first substrate 12 can be increased. As a result, the vibration of the microphone 10 can be suppressed. In particular, the shape of the Helmholtz resonator 14 in Modification 2 of Embodiment 1 has a more remarkable effect when the first substrate 12 is thin like a flexible substrate.

[0076] (Embodiment 2) The shape of the sound path formed on the second substrate in Embodiment 1 is a cylindrical shape. On the other hand, in Embodiment 2, the shape of the input port of the sound path is different from that in Embodiment 1.

[0077] FIG. 6 is a cross-sectional view showing the configuration of the sound collection device in Embodiment 2 of the present disclosure.

[0078] The sound collection device 1A shown in FIG. 6 includes a microphone 10, an acoustic member 11A, and a Helmholtz resonator 14. In the present Embodiment 2, the same components as those in Embodiment 1 are denoted by the same reference numerals, and the description thereof is omitted.

[0079] The acoustic member 11A has a sound path 131A formed to guide sound to the diaphragm 102. The acoustic member 11A includes a first substrate 12 and a second substrate 13A.

[0080] The sound path 131A of the second substrate 13A is formed in a tapered shape from the sound input port toward the inside of the sound path 131A.

[0081] When sound passes through a narrow sound path, the high-frequency characteristics of the sound may change. Therefore, the sound path 131A is formed in a tapered shape from the sound input port toward the inside of the sound path 131 A so that the sound path 131 A becomes wider, and the change in the high-frequency characteristics of the sound can be reduced.

[0082] (Embodiment 3) In Embodiment 1, the interiors of the neck portion 141 and the cavity portion 142 of the Helmholtz resonator 14 are hollow. In contrast, in Embodiment 3, a sound-absorbing material is disposed inside the neck portion 141 and the cavity portion 142 of the Helmholtz resonator 14.

[0083] FIG. 7 is a cross-sectional view showing the configuration of the sound collection device in Embodiment 3 of the present disclosure.

[0084] The sound collection device 1B shown in FIG. 7 includes a microphone 10, an acoustic member 11, a Helmholtz resonator 14, and a sound-absorbing material 144. In Embodiment 3, the same components as those in Embodiment 1 are denoted by the same reference numerals, and the description thereof is omitted.

[0085] The sound-absorbing material 144 is disposed inside at least one of the neck portion 141 and the cavity portion 142. That is, the sound-absorbing material 144 may be disposed inside both the neck portion 141 and the cavity portion 142, may be disposed only inside the neck portion 141, or may be disposed only inside the cavity portion 142. The position where the sound-absorbing material 144 is disposed may be determined according to the frequency to be reduced.

[0086] The sound-absorbing material 144 is, for example, a sponge made of polyurethane. The structure of the sound-absorbing material 144 is preferably open-cell. The material of the sound-absorbing material 144 may be determined according to the frequency to be reduced. The shape of the Helmholtz resonator 14 in Embodiment 3 is the same as the shape of the Helmholtz resonator 14 in Embodiment 1.

[0087] According to the third embodiment, by arranging the sound-absorbing material 144 inside the Helmholtz resonator 14, the sharpness of the signal characteristics of the resonance frequency can be controlled.

[0088] In addition, the sound path 131 of the second substrate 13 in the third embodiment may be formed in a tapered shape from the sound input port toward the inside of the sound path 131, similar to the second embodiment.

[0089] (Embodiment 4) In the first embodiment, a Helmholtz resonator is formed around the sound path. In contrast, in the fourth embodiment, a first Helmholtz resonator is formed around the sound path, and a second Helmholtz resonator is further formed around the first Helmholtz resonator.

[0090] FIG. 8 is a cross-sectional view showing the configuration of the sound collection device in the fourth embodiment of the present disclosure.

[0091] The sound collection device 1C shown in FIG. 8 includes a microphone 10, an acoustic member 11C, a first Helmholtz resonator 14A, and a second Helmholtz resonator 14B. In the fourth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[0092] The acoustic member 11C has a sound path 131 formed to guide sound to the diaphragm 102. The acoustic member 11C includes a first substrate 12 and a second substrate 13C.

[0093] The first Helmholtz resonator 14A and the second Helmholtz resonator 14B are formed on the second substrate 13C. The resonance frequency of the first Helmholtz resonator 14A and the resonance frequency of the second Helmholtz resonator 14B are different from each other.

[0094] The first Helmholtz resonator 14A is formed in a direction perpendicular to the wall surface surrounding the sound path 131.

[0095] The first Helmholtz resonator 14A has an opening 143 formed in the wall surface surrounding the sound path 131. The first Helmholtz resonator 14A is formed in a direction perpendicular to the wall surface surrounding the sound path 131. The first Helmholtz resonator 14A is an example of the first resonator.

[0096] The first Helmholtz resonator 14A includes a first neck portion 141A and a first cavity portion 142A. The first neck portion 141A is formed around the sound path 131 and has a space with a first volume. The first cavity portion 142A is formed around the first neck portion 141A and has a space with a second volume larger than the first volume. The first Helmholtz resonator 14A resonates with sounds of a specific frequency and mainly reduces peaks generated in the ultrasonic band. The cross-sectional area of the opening 143 of the first neck portion 141A, the length of the first neck portion 141A, and the volume of the first cavity portion 142A are determined so that the peak is reduced by the resonance frequency.

[0097] The first neck portion 141A is an annular space surrounding the sound path 131. The first cavity portion 142A is an annular space surrounding the first neck portion 141A.

[0098] The second Helmholtz resonator 14B is formed outside the first Helmholtz resonator 14A and has an opening 145 connected to the first Helmholtz resonator 14A.

[0099] The second Helmholtz resonator 14B has an opening 145 formed in the wall surface of the first cavity portion 142A of the first Helmholtz resonator 14A. The second Helmholtz resonator 14B is formed in a direction perpendicular to the wall surface surrounding the sound path 131. The second Helmholtz resonator 14B is an example of the second resonator.

[0100] The second Helmholtz resonator 14B includes a second neck portion 141B and a second cavity portion 142B. The second neck portion 141B is formed around the first cavity portion 142A of the first Helmholtz resonator 14A and has a space with a third volume smaller than the first volume. The second cavity portion 142B is formed around the second neck portion 141B and has a space with a fourth volume larger than the third volume and smaller than the second volume. The second Helmholtz resonator 14B resonates with sounds of a specific frequency and mainly reduces peaks occurring in the low frequency region. The cross-sectional area of the opening 145 of the second neck portion 141B, the length of the second neck portion 141B, and the volume of the second cavity portion 142B are determined so that the peak is reduced by the resonance frequency.

[0101] The second neck portion 141B is an annular space surrounding the first cavity portion 142A of the first Helmholtz resonator 14A. The second cavity portion 142B is an annular space surrounding the second neck portion 141B.

[0102] Note that in the fourth embodiment, the sizes of the first Helmholtz resonator 14A and the second Helmholtz resonator 14B become smaller as they are farther from the sound path 131, but the present disclosure is not particularly limited thereto. The sizes of the first Helmholtz resonator 14A and the second Helmholtz resonator 14B may become larger as they are farther from the sound path 131.

[0103] Here, a method of forming the first Helmholtz resonator 14A and the second Helmholtz resonator 14B on the second substrate 13C will be described with reference to FIG. 9.

[0104] FIG. 9 is a view of the second substrate in the fourth embodiment of the present disclosure as seen from above.

[0105] First, through holes are formed in the thickness direction of the second substrate 13C. The through holes formed in the second substrate 13C are the sound channels 131. The cross-sections of the open ends on the input side and the output side of the sound channel 131 are circular. The sound channel 131 has a cylindrical shape. It is preferable that the diameters of the open ends on the input side and the output side of the sound channel 131 are the same as the diameter of the through hole 121 of the first substrate 12.

[0106] Next, an annular region from the outer edge of the sound channel 131 to a position corresponding to the horizontal length of the first neck portion 141A of the first Helmholtz resonator 14A is cut from the surface of the second substrate 13C to a position of the first depth. Thereby, the first neck portion 141A of the first Helmholtz resonator 14A is formed.

[0107] Next, an annular region from the outer edge of the first neck portion 141A to a position corresponding to the horizontal length of the first cavity portion 142A of the first Helmholtz resonator 14A is cut from the surface of the second substrate 13C to a position of the second depth. Thereby, the first cavity portion 142A of the first Helmholtz resonator 14A is formed. Note that the second depth from the surface of the second substrate 13C in the first cavity portion 142A is deeper than the first depth from the surface of the second substrate 13C in the first neck portion 141A.

[0108] Next, an annular region from the outer edge of the first cavity portion 142A of the first Helmholtz resonator 14A to a position corresponding to the horizontal length of the second neck portion 141B of the second Helmholtz resonator 14B is cut from the surface of the second substrate 13C to a position of the third depth. Thereby, the second neck portion 141B of the second Helmholtz resonator 14B is formed. Note that the third depth from the surface of the second substrate 13C in the second neck portion 141B of the second Helmholtz resonator 14B is shallower than the first depth from the surface of the second substrate 13C in the first neck portion 141A of the first Helmholtz resonator 14A.

[0109] Next, an annular region from the outer edge of the second neck portion 141B to a position corresponding to the horizontal length of the second cavity portion 142B of the second Helmholtz resonator 14B is cut from the surface of the second substrate 13C to a position at the fourth depth. Thereby, the second cavity portion 142B of the second Helmholtz resonator 14B is formed. Note that the fourth depth from the surface of the second substrate 13C in the second cavity portion 142B is deeper than the third depth from the surface of the second substrate 13C in the second neck portion 141B of the second Helmholtz resonator 14B, and shallower than the second depth from the surface of the second substrate 13C in the first cavity portion 142A of the first Helmholtz resonator 14A.

[0110] Note that the first neck portion 141A and the first cavity portion 142A of the first Helmholtz resonator 14A may be formed by resin transfer processing instead of the above-described cutting process. Also, the second neck portion 141B and the second cavity portion 142B of the second Helmholtz resonator 14B may be formed by resin transfer processing instead of the above-described cutting process.

[0111] Next, the surface of the first substrate 12 that faces the surface on which the microphone 10 is mounted (that is, the surface on which the microphone 10 is not mounted) and the surface of the second substrate 13C on which the first Helmholtz resonator 14A and the second Helmholtz resonator 14B are formed are bonded together. At this time, the first substrate 12 and the second substrate 13C are bonded together so that the central axis of the through hole 121 of the first substrate 12 coincides with the central axis of the sound path 131 of the second substrate 13C. Thereby, the first Helmholtz resonator 14A and the second Helmholtz resonator 14B are formed between the first substrate 12 and the second substrate 13C.

[0112] According to the fourth embodiment, by forming the first Helmholtz resonator 14A and the second Helmholtz resonator 14B having different resonance frequencies from each other, peaks at a plurality of frequencies can be reduced.

[0113] Note that the sound path 131 of the second substrate 13C in the fourth embodiment may be formed in a tapered shape from the sound input port toward the inside of the sound path 131, similar to the second embodiment.

[0114] Also, in at least one of the first neck portion 141A and the first cavity portion 142A of the first Helmholtz resonator 14A in the fourth embodiment, a sound-absorbing material may be disposed therein, similar to the third embodiment. Further, in at least one of the second neck portion 141B and the second cavity portion 142B of the second Helmholtz resonator 14B in the fourth embodiment, a sound-absorbing material may be disposed therein, similar to the third embodiment.

[0115] Subsequently, various modifications of the shapes of the first Helmholtz resonator 14A and the second Helmholtz resonator 14B in the fourth embodiment will be described.

[0116] FIG. 10 is a view of the second substrate in Modification 1 of the fourth embodiment of the present disclosure as viewed from above.

[0117] The shape of the first Helmholtz resonator 14A in Modification 1 of the fourth embodiment is the same as the shape of the first Helmholtz resonator 14A in the fourth embodiment.

[0118] On the other hand, the second Helmholtz resonator 14B in Modification 1 of the fourth embodiment includes at least one second neck portion 141B and a second cavity portion 142B. At least one second neck portion 141B is a tubular space extending radially from the wall surface of the first cavity portion 142A of the first Helmholtz resonator 14A. Note that the second Helmholtz resonator 14B in Modification 1 of the fourth embodiment includes four second neck portions 141B. The second cavity portion 142B is an annular space surrounding at least one second neck portion 141B. One open end of at least one second neck portion 141B is connected to the first cavity portion 142A of the first Helmholtz resonator 14A, and the other open end of at least one second neck portion 141B is connected to the second cavity portion 142B.

[0119] The cross-sectional shape of the opening 145 of the second neck portion 141B may be a quadrilateral, and the second neck portion 141B may be a prism shape. Also, the cross-sectional shape of the opening 145 of the second neck portion 141B may be circular, and the second neck portion 141B may be a cylindrical shape. Further, the second neck portion 141B may be a fan shape that gradually expands from the opening end connected to the first cavity portion 142A of the first Helmholtz resonator 14A toward the opening end connected to the second cavity portion 142B.

[0120] Note that the number of the second neck portions 141B is not limited to four. For example, when the number of the second neck portions 141B decreases, the signal characteristics of the resonance frequency become steeper, and when the number of the second neck portions 141B increases, the signal characteristics of the resonance frequency become gentler. Therefore, the second Helmholtz resonator 14B may include the second neck portions 141B in a number corresponding to the sharpness (i.e., Q value) of the signal characteristics of the peak frequency to be reduced. Also, the second Helmholtz resonator 14B may include a plurality of second neck portions 141B having different cross-sectional areas of the opening 145 according to the number of frequencies for which the peak is to be reduced.

[0121] In Modification 1 of Embodiment 4, by changing the number of the second neck portions 141B of the second Helmholtz resonator 14B, the degree of freedom in designing the resonance frequency and the sharpness of the signal characteristics of the resonance frequency can be improved. Also, by the second Helmholtz resonator 14B including a plurality of second neck portions 141B having different cross-sectional areas of the opening 145, the peaks of a plurality of frequencies can be reduced. Also, since the area where the first substrate 12 and the second substrate 13C are in contact becomes larger, the support strength of the first substrate 12 can be increased. As a result, the vibration of the microphone 10 can be suppressed. In particular, the shape of the second Helmholtz resonator 14B in Modification 1 of the present Embodiment 4 exhibits a more remarkable effect when the first substrate 12 is thin like a flexible substrate.

[0122] FIG. 11 is a view of the second substrate in Modification 2 of Embodiment 4 of the present disclosure as seen from above.

[0123] The shape of the first Helmholtz resonator 14A in Modification 2 of Embodiment 4 is the same as the shape of the first Helmholtz resonator 14A in Embodiment 4.

[0124] The second Helmholtz resonator 14B in Modification 2 of Embodiment 4 includes at least one second neck portion 141B and at least one second cavity portion 142B. At least one second neck portion 141B is a tubular space extending radially from the wall surface of the first cavity portion 142A of the first Helmholtz resonator 14A. At least one second cavity portion 142B is provided individually for at least one second neck portion 141B. Note that the second Helmholtz resonator 14B in Modification 2 of Embodiment 4 includes four second neck portions 141B and four second cavity portions 142B. One open end of at least one second neck portion 141B is connected to the first cavity portion 142A of the first Helmholtz resonator 14A, and the other open end of at least one second neck portion 141B is connected to at least one second cavity portion 142B.

[0125] The cross-sectional shape of the opening 145 of the second neck portion 141B may be a quadrilateral, and the second neck portion 141B may be a prismatic shape. Also, the cross-sectional shape of the opening 145 of the second neck portion 141B may be circular, and the second neck portion 141B may be a cylindrical shape.

[0126] The cross-sectional shape of the second cavity portion 142B may be a quadrilateral, and the second cavity portion 142B may be a prismatic shape. Also, the cross-sectional shape of the second cavity portion 142B may be circular, and the second cavity portion 142B may be a cylindrical shape. Also, the second cavity portion 142B may be spherical.

[0127] Note that the numbers of the second neck portion 141B and the second cavity portion 142B are not limited to four. For example, when the numbers of the second neck portion 141B and the second cavity portion 142B decrease, the signal characteristics of the resonance frequency become steep, and when the numbers of the second neck portion 141B and the second cavity portion 142B increase, the signal characteristics of the resonance frequency become gentle. Therefore, the second Helmholtz resonator 14B may include the second neck portion 141B and the second cavity portion 142B in a number corresponding to the sharpness (i.e., Q value) of the signal characteristics of the peak frequency to be reduced. Further, the second Helmholtz resonator 14B may include a plurality of second neck portions 141B having different cross-sectional areas of the opening 145, and may include a plurality of second cavity portions 142B having different volumes, according to the number of frequencies for which the peaks are to be reduced.

[0128] In Modification 2 of Embodiment 4, by changing the numbers of the second neck portion 141B and the second cavity portion 142B, the degrees of freedom in designing the resonance frequency and the sharpness of the signal characteristics of the resonance frequency can be improved. Further, by the second Helmholtz resonator 14B including a plurality of second neck portions 141B having different cross-sectional areas of the opening 145, peaks at a plurality of frequencies can be reduced. Further, by the second Helmholtz resonator 14B including a plurality of second cavity portions 142B having different volumes, peaks at a plurality of frequencies can be reduced. Further, since the area where the first substrate 12 and the second substrate 13C are in contact becomes larger, the support strength of the first substrate 12 can be increased. As a result, the vibration of the microphone 10 can be suppressed. In particular, the shape of the second Helmholtz resonator 14B in Modification 2 of Embodiment 4 of the present disclosure exhibits a more remarkable effect when the first substrate 12 is thin like a flexible substrate.

[0129] FIG. 12 is a view of the second substrate in Modification 3 of Embodiment 4 of the present disclosure as viewed from above.

[0130] The first Helmholtz resonator 14A in Modification 3 of Embodiment 4 includes at least one first neck portion 141A and a first cavity portion 142A. At least one first neck portion 141A is a tubular space extending radially from the wall surface of the sound path 131. Note that the first Helmholtz resonator 14A in Modification 3 of Embodiment 4 includes four first neck portions 141A. The first cavity portion 142A is an annular space surrounding at least one first neck portion 141A. One open end of at least one first neck portion 141A is connected to the sound path 131, and the other open end of at least one first neck portion 141A is connected to the first cavity portion 142A.

[0131] The cross-sectional shape of the opening 143 of the first neck portion 141A may be a quadrilateral, and the first neck portion 141A may be a prismatic shape. Also, the cross-sectional shape of the opening 143 of the first neck portion 141A may be circular, and the first neck portion 141A may be a cylindrical shape. Further, the first neck portion 141A may be a fan-shaped shape that gradually expands from the open end connected to the sound path 131 toward the open end connected to the first cavity portion 142A.

[0132] Note that the number of the first neck portions 141A is not limited to four. For example, when the number of the first neck portions 141A decreases, the signal characteristics of the resonance frequency become steep, and when the number of the first neck portions 141A increases, the signal characteristics of the resonance frequency become gentle. Therefore, the first Helmholtz resonator 14A may include the first neck portions 141A in a number corresponding to the sharpness (i.e., Q value) of the signal characteristics of the peak frequency to be reduced. Also, the first Helmholtz resonator 14A may include a plurality of first neck portions 141A having different cross-sectional areas of the opening 143 according to the number of frequencies for which the peak is to be reduced.

[0133] The shape of the second Helmholtz resonator 14B in Modification 3 of Embodiment 4 is the same as the shape of the second Helmholtz resonator 14B in Modification 1 of Embodiment 4.

[0134] In Modification 3 of Embodiment 4, by changing the number of the first neck portion 141A and the second neck portion 141B, the design freedom of the resonance frequency and the sharpness of the signal characteristics of the resonance frequency can be improved. Further, by including a plurality of first neck portions 141A and a plurality of second neck portions 141B having different cross-sectional areas of the openings 143 and 145 in the first Helmholtz resonator 14A and the second Helmholtz resonator 14B, peaks at a plurality of frequencies can be reduced. Further, since the area where the first substrate 12 and the second substrate 13C are in contact becomes larger, the support strength of the first substrate 12 can be increased. As a result, the vibration of the microphone 10 can be suppressed. In particular, the shape of the first Helmholtz resonator 14A and the second Helmholtz resonator 14B in Modification 3 of Embodiment 4 of the present disclosure exhibits a more remarkable effect when the first substrate 12 is thin like a flexible substrate.

[0135] FIG. 13 is a view of the second substrate in Modification 4 of Embodiment 4 of the present disclosure as viewed from above.

[0136] The shape of the first Helmholtz resonator 14A in Modification 4 of Embodiment 4 is the same as the shape of the first Helmholtz resonator 14A in Modification 3 of Embodiment 4.

[0137] Further, the shape of the second Helmholtz resonator 14B in Modification 4 of Embodiment 4 is the same as the shape of the second Helmholtz resonator 14B in Embodiment 4.

[0138] In Modification 4 of Embodiment 4, by changing the number of the first neck portions 141A, the design freedom of the resonance frequency and the sharpness of the signal characteristics of the resonance frequency can be improved. Further, by including a plurality of first neck portions 141A having different cross-sectional areas of the opening 143 in the first Helmholtz resonator 14A, peaks at a plurality of frequencies can be reduced. Further, since the area where the first substrate 12 and the second substrate 13C are in contact becomes larger, the support strength of the first substrate 12 can be increased. As a result, the vibration of the microphone 10 can be suppressed. In particular, the shape of the first Helmholtz resonator 14A in Modification 4 of Embodiment 4 of the present disclosure exhibits a more remarkable effect when the first substrate 12 is thin like a flexible substrate.

[0139] FIG. 14 is a view of the second substrate in Modification 5 of Embodiment 4 of the present disclosure as seen from above.

[0140] The first Helmholtz resonator 14A in Modification 5 of Embodiment 4 includes at least one first neck portion 141A and at least one first cavity portion 142A. At least one first neck portion 141A is a tubular space extending radially from the wall surface of the sound path 131. At least one first cavity portion 142A is provided separately from at least one first neck portion 141A. Note that the first Helmholtz resonator 14A in Modification 5 of Embodiment 4 includes four first neck portions 141A and four first cavity portions 142A. One open end of at least one first neck portion 141A is connected to the sound path 131, and the other open end of at least one first neck portion 141A is connected to the first cavity portion 142A.

[0141] The cross-sectional shape of the opening 143 of the first neck portion 141A may be a quadrangle, and the first neck portion 141A may be a prism shape. Further, the cross-sectional shape of the opening 143 of the first neck portion 141A may be a circle, and the first neck portion 141A may be a cylinder shape.

[0142] The cross-sectional shape of the first cavity portion 142A may be a quadrilateral, and the first cavity portion 142A may have a prismatic shape. Also, the cross-sectional shape of the first cavity portion 142A may be circular, and the first cavity portion 142A may have a cylindrical shape. Further, the first cavity portion 142A may be spherical.

[0143] Note that the number of the first neck portions 141A and the first cavity portions 142A is not limited to four. For example, when the number of the first neck portions 141A and the first cavity portions 142A decreases, the signal characteristics of the resonance frequency become steep, and when the number of the first neck portions 141A and the first cavity portions 142A increases, the signal characteristics of the resonance frequency become gentle. Therefore, the first Helmholtz resonator 14A may include the first neck portions 141A and the first cavity portions 142A in a number corresponding to the sharpness (i.e., Q value) of the signal characteristics of the peak frequency to be reduced. Also, the first Helmholtz resonator 14A may include a plurality of first neck portions 141A having different cross-sectional areas of the opening 143 and a plurality of first cavity portions 142A having different volumes according to the number of frequencies for which the peaks are to be reduced.

[0144] The shape of the second Helmholtz resonator 14B in Modification 5 of Embodiment 4 is the same as the shape of the second Helmholtz resonator 14B in Modification 1 of Embodiment 4.

[0145] In Modification 5 of Embodiment 4, the second Helmholtz resonator 14B includes at least one second neck portion 141B and a second cavity portion 142B. At least one second neck portion 141B is a tubular space that extends radially from the wall surface of at least one first cavity portion 142A of the first Helmholtz resonator 14A. Note that the second Helmholtz resonator 14B in Modification 5 of Embodiment 4 includes four second neck portions 141B. The second cavity portion 142B is an annular space that surrounds at least one second neck portion 141B. One open end of at least one second neck portion 141B is connected to at least one first cavity portion 142A of the first Helmholtz resonator 14A, and the other open end of at least one second neck portion 141B is connected to the second cavity portion 142B.

[0146] In Modification 5 of Embodiment 4, by changing the number of the first neck portion 141A and the first cavity portion 142A, the degree of freedom in designing the resonance frequency and the sharpness of the signal characteristics of the resonance frequency can be improved. Further, by including the first Helmholtz resonator 14A with a plurality of first neck portions 141A having different cross-sectional areas of the opening 143, peaks at a plurality of frequencies can be reduced. Further, by including the first Helmholtz resonator 14A with a plurality of first cavity portions 142A having different volumes, peaks at a plurality of frequencies can be reduced. Further, by changing the number of the second neck portions 141B of the second Helmholtz resonator 14B, the degree of freedom in designing the resonance frequency and the sharpness of the signal characteristics of the resonance frequency can be improved. Further, by including the second Helmholtz resonator 14B with a plurality of second neck portions 141B having different cross-sectional areas of the opening 145, peaks at a plurality of frequencies can be reduced. Further, since the area where the first substrate 12 and the second substrate 13C are in contact becomes larger, the support strength of the first substrate 12 can be increased. As a result, vibration of the microphone 10 can be suppressed. In particular, the shapes of the first Helmholtz resonator 14A and the second Helmholtz resonator 14B in Modification 5 of Embodiment 4 exhibit a more remarkable effect when the first substrate 12 is thin like a flexible substrate.

[0147] FIG. 15 is a view of the second substrate in Modification 6 of Embodiment 4 of the present disclosure as seen from above.

[0148] The shape of the first Helmholtz resonator 14A in Modification 6 of Embodiment 4 is the same as the shape of the first Helmholtz resonator 14A in Modification 5 of Embodiment 4.

[0149] Also, the shape of the second Helmholtz resonator 14B in Modification 6 of Embodiment 4 is the same as the shape of the second Helmholtz resonator 14B in Modification 2 of Embodiment 4.

[0150] The second Helmholtz resonator 14B in Modification 6 of Embodiment 4 includes at least one second neck portion 141B and at least one second cavity portion 142B. At least one second neck portion 141B is a tubular space extending radially from the wall surface of at least one first cavity portion 142A of the first Helmholtz resonator 14A. At least one second cavity portion 142B is provided separately for at least one second neck portion 141B. Note that the second Helmholtz resonator 14B in Modification 6 of Embodiment 4 includes four second neck portions 141B and four second cavity portions 142B. One open end of at least one second neck portion 141B is connected to at least one first cavity portion 142A of the first Helmholtz resonator 14A, and the other open end of at least one second neck portion 141B is connected to at least one second cavity portion 142B.

[0151] In Modification Example 6 of Embodiment 4, by changing the number of the first neck portion 141A and the first cavity portion 142A of the first Helmholtz resonator 14A, the design freedom of the resonance frequency and the sharpness of the signal characteristics of the resonance frequency can be improved. Further, by including a plurality of first neck portions 141A having different cross-sectional areas of the opening 143 in the first Helmholtz resonator 14A, peaks at a plurality of frequencies can be reduced. Further, by including a plurality of first cavity portions 142A having different volumes in the first Helmholtz resonator 14A, peaks at a plurality of frequencies can be reduced. Further, by changing the number of the second neck portion 141B and the second cavity portion 142B of the second Helmholtz resonator 14B, the design freedom of the resonance frequency and the sharpness of the signal characteristics of the resonance frequency can be improved. Further, by including a plurality of second neck portions 141B having different cross-sectional areas of the opening 145 in the second Helmholtz resonator 14B, peaks at a plurality of frequencies can be reduced. Further, by including a plurality of second cavity portions 142B having different volumes in the second Helmholtz resonator 14B, peaks at a plurality of frequencies can be reduced. Further, since the area where the first substrate 12 and the second substrate 13C are in contact becomes larger, the support strength of the first substrate 12 can be increased. As a result, the vibration of the microphone 10 can be suppressed. In particular, the shapes of the first Helmholtz resonator 14A and the second Helmholtz resonator 14B in Modification Example 6 of Embodiment 4 exhibit a more remarkable effect when the first substrate 12 is thin like a flexible substrate.

[0152] Note that in Modification Example 6 of Embodiment 4, although one second neck portion 141B of the second Helmholtz resonator 14B is connected to one first cavity portion 142A of the first Helmholtz resonator 14A, the present disclosure is not particularly limited thereto. A plurality of second neck portions 141B of the second Helmholtz resonator 14B may be connected to one first cavity portion 142A of the first Helmholtz resonator 14A.

[0153] (Embodiment 5) The microphone in Embodiment 1 is a bottom port type MEMS microphone with sound holes formed on the first substrate side at the bottom of the microphone. In contrast, the microphone in Embodiment 5 is a top port type MEMS microphone with sound holes formed in the cover at the top of the microphone.

[0154] FIG. 16 is a cross-sectional view showing the configuration of the sound collection device in Embodiment 5 of the present disclosure.

[0155] The sound collection device 1D shown in FIG. 16 includes a microphone 10D, an acoustic member 11D, a Helmholtz resonator 14, a substrate 15, and a gasket 16. In this Embodiment 5, the same components as those in Embodiment 1 are denoted by the same reference numerals, and the description thereof is omitted.

[0156] The microphone 10D is a MEMS microphone. The microphone 10D includes an electronic component and a cover that covers the electronic component. A sound hole 101D for guiding sound into the microphone 10D is formed in the cover.

[0157] The sound hole 101D in this Embodiment 5 is formed in the cover at the top of the microphone 10D. The microphone 10D in this Embodiment 5 is a top port type MEMS microphone.

[0158] The diaphragm 102 is disposed inside the microphone 10D in which the sound hole 101D is formed.

[0159] The substrate 15 mounts the microphone 10D such that a surface facing the surface in which the sound hole 101D is formed is in contact. The microphone 10D is mounted on the substrate 15.

[0160] Note that although the diaphragm 102 shown in FIG. 16 is mounted on the cover (lid) at the top of the microphone 10D, the present disclosure is not particularly limited thereto. The diaphragm 102 may be mounted on the substrate 15 at the bottom of the microphone 10D.

[0161] The acoustic member 11D has a sound path 181 formed to guide sound to the diaphragm 102. The acoustic member 11D includes a first housing 17 and a second housing 18.

[0162] The first housing 17 has a through hole 171 formed at the same position as the sound hole 101D of the microphone 10D and is attached to the microphone 10D. Note that the first housing 17 is an example of a first acoustic member.

[0163] The second housing 18 has a sound path 181 formed at a position corresponding to the through hole 171 of the first housing 17 and is attached to the first housing 17. Note that the second housing 18 is an example of a second acoustic member. The first housing 17 and the second housing 18 are the housings of an electric device including the sound collection device 1D.

[0164] The gasket 16 is disposed between the microphone 10D and the first housing 17 and connects the microphone 10D and the first housing 17. The gasket 16 prevents the sound input into the sound path 181 from leaking. Note that the sound collection device 1D may not include the gasket 16, and the microphone 10D may be directly attached to the first housing 17 without passing through the gasket 16.

[0165] One surface of the first housing 17 is bonded to the surface on which the sound hole 101D of the microphone 10D is formed via the gasket 16. Also, the other surface of the first housing 17 is bonded to the surface on which the Helmholtz resonator 14 of the second housing 18 is formed.

[0166] The Helmholtz resonator 14 has an opening 143 formed in the wall surface surrounding the sound path 181. The Helmholtz resonator 14 is formed in a direction perpendicular to the wall surface surrounding the sound path 181. The Helmholtz resonator 14 is an example of a resonator. The shape of the Helmholtz resonator 14 in the fifth embodiment is the same as the shape of the Helmholtz resonator 14 in the first embodiment.

[0167] According to the fifth embodiment, even if the microphone 10D is a top port type MEMS microphone, the Helmholtz resonator 14 can reduce the peak generated in the ultrasonic band and make the frequency characteristics substantially flat.

[0168] In addition, the sound path 181 of the second housing 18 in the fifth embodiment may be formed in a tapered shape from the sound input port toward the inside of the sound path 181, similar to the second embodiment.

[0169] Also, a sound-absorbing material may be disposed inside at least one of the neck portion 141 and the cavity portion 142 of the Helmholtz resonator 14 in the fifth embodiment, similar to the third embodiment.

[0170] Moreover, the sound collection device 1D in the fifth embodiment may include a first Helmholtz resonator 14A and a second Helmholtz resonator 14B, similar to the fourth embodiment.

[0171] Also, although the Helmholtz resonator 14 in the fifth embodiment is formed in the second housing 18, the present disclosure is not particularly limited thereto, and the Helmholtz resonator 14 may be formed in the first housing 17 instead of the second housing 18. In this case, one surface of the second housing 18 in which the through hole is formed and one surface of the first housing 17 in which the Helmholtz resonator 14 is formed are bonded together.

[0172] (Sixth Embodiment) In the first embodiment, the Helmholtz resonator 14 is formed outside the microphone. In contrast, in the sixth embodiment, the Helmholtz resonator 14 is formed inside the microphone.

[0173] FIG. 17 is a cross-sectional view showing the configuration of the sound collection device in the sixth embodiment of the present disclosure.

[0174] The sound collection device 1E shown in Fig. 17 includes a microphone 10E and a substrate 19. In the sixth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[0175] The microphone 10E includes a diaphragm 102, a support member 104, and a Helmholtz resonator 14.

[0176] The diaphragm 102 is disposed inside the microphone 10E in which a sound hole 101 is formed.

[0177] The support member 104 is disposed between the sound hole 101 and the diaphragm 102. The support member 104 supports the diaphragm 102. The support member 104 has a sound path 103 formed to guide sound to the diaphragm 102. Note that the support member 104 is an example of an acoustic member.

[0178] The Helmholtz resonator 14 has an opening 143 formed in a wall surface surrounding the sound path 103. The Helmholtz resonator 14 is formed in a direction perpendicular to the wall surface surrounding the sound path 103. The Helmholtz resonator 14 is an example of a resonator. The shape of the Helmholtz resonator 14 in the sixth embodiment is the same as the shape of the Helmholtz resonator 14 in the first embodiment.

[0179] The substrate 19 has a through hole 191 formed at the same position as the sound hole 101 and is attached to the microphone 10E. The substrate 19 may be a rigid substrate or a flexible substrate. The microphone 10E is mounted on one surface of the substrate 19. The cross section of the through hole 191 is, for example, circular. It is preferable that the diameter of the through hole 191 is the same as the diameter of the sound hole 101 of the microphone 10E.

[0180] According to the sixth embodiment, since the Helmholtz resonator 14 is formed inside the microphone 10E, the sound collection device 1E can be miniaturized.

[0181] Note that, similar to Embodiment 3, a sound-absorbing material may be disposed inside at least one of the neck portion 141 and the cavity portion 142 of the Helmholtz resonator 14 in Embodiment 6.

[0182] Further, similar to Embodiment 4, the sound collection device 1E in Embodiment 6 may include a first Helmholtz resonator 14A and a second Helmholtz resonator 14B.

[0183] Also, the microphone 10E in Embodiment 6 is a bottom port type MEMS microphone, but the present disclosure is not particularly limited thereto, and the microphone 10E may be a top port type MEMS microphone similar to Embodiment 5.

[0184] (Embodiment 7) The microphone in Embodiment 1 is a MEMS microphone. In contrast, the microphone in Embodiment 7 is an electret condenser microphone.

[0185] FIG. 18 is a cross-sectional view showing the configuration of the sound collection device in Embodiment 7 of the present disclosure.

[0186] The sound collection device 1F shown in FIG. 18 includes a microphone 10F, an acoustic member 11F, and a Helmholtz resonator 14. In Embodiment 7, the same components as those in Embodiment 1 are denoted by the same reference numerals, and the description thereof is omitted.

[0187] The microphone 10F is an electret condenser microphone. The microphone 10F includes an electronic component and a cover covering the electronic component. A sound hole 101 for guiding sound into the microphone 10F is formed in the cover. The electronic component includes, for example, a diaphragm 102 and an audio amplifier (not shown). The diaphragm 102 vibrates in response to the sound pressure of the input sound. The cross-section of the sound hole 101 is, for example, circular.

[0188] The diaphragm 102 is the microphone 10 in which the sound hole 101 is formedF It is disposed inside

[0189] The acoustic member 11F has a sound path 211 formed to guide sound to the diaphragm 102. The acoustic member 11F includes a covering member 20 and a housing 21.

[0190] The covering member 20 is an elastic member such as rubber, for example, and absorbs vibrations to the microphone 10F. The covering member 20 has a through hole 201 formed at the same position as the sound hole 101 and is attached around the microphone 10F. Note that the covering member 20 is an example of a first acoustic member. The cross section of the through hole 201 is, for example, circular. The diameter of the through hole 201 is preferably the same as the diameter of the sound hole 101 of the microphone 10F.

[0191] The housing 21 has a sound path 211 formed at a position corresponding to the through hole 201 and is attached to the covering member 20. Note that the housing 21 is an example of a second acoustic member. The housing 21 is the housing of an electric device including the sound collection device 1F. The cross sections of the open end on the input side and the open end on the output side of the sound path 211 are circular. The sound path 211 is cylindrical. The diameters of the open end on the input side and the open end on the output side of the sound path 211 are preferably the same as the diameter of the through hole 201 of the covering member 20. The covering member 20 is bonded to the surface on which the Helmholtz resonator 14 of the housing 21 is formed.

[0192] The Helmholtz resonator 14 has an opening 143 formed in the wall surface surrounding the sound path 211. The Helmholtz resonator 14 is formed in a direction perpendicular to the wall surface surrounding the sound path 211. The Helmholtz resonator 14 is an example of a resonator. The shape of the Helmholtz resonator 14 in the seventh embodiment is the same as the shape of the Helmholtz resonator 14 in the first embodiment.

[0193] According to Embodiment 7, even if the microphone 10F is an electret condenser microphone, the peak generated in the ultrasonic band can be reduced by the Helmholtz resonator 14, and the frequency characteristics can be made substantially flat.

[0194] Note that the sound path 211 of the housing 21 in Embodiment 7 may be formed in a tapered shape from the sound input port toward the inside of the sound path 211, similar to Embodiment 2.

[0195] Also, a sound-absorbing material may be disposed inside at least one of the neck portion 141 and the cavity portion 142 of the Helmholtz resonator 14 in Embodiment 7, similar to Embodiment 3.

[0196] Also, the sound collection device 1F in Embodiment 7 may include a first Helmholtz resonator 14A and a second Helmholtz resonator 14B, similar to Embodiment 4.

[0197] Subsequently, the sound collection device in a modification of Embodiment 7 will be described.

[0198] The Helmholtz resonator 14 in Embodiment 7 is formed in the housing 21 (second acoustic member). In contrast, the Helmholtz resonator 14 in the modification of Embodiment 7 is formed in the covering member 20 (first acoustic member).

[0199] FIG. 19 is a cross-sectional view showing the configuration of the sound collection device in a modification of Embodiment 7 of the present disclosure.

[0200] The sound collection device 1G shown in FIG. 19 includes a microphone 10F, an acoustic member 11G, and a Helmholtz resonator 14. In the modification of Embodiment 7, the same components as those in Embodiments 1 and 7 are denoted by the same reference numerals, and the description thereof is omitted.

[0201] The acoustic member 11G has a sound path 202 formed to guide sound to the diaphragm 102. The acoustic member 11G includes a covering member 20G and a housing 21G.

[0202] The covering member 20G is an elastic member such as rubber, for example, and absorbs vibration to the microphone 10F. The covering member 20G has a sound path 202 formed at a position corresponding to the sound hole 101 and is attached around the microphone 10F. Note that the covering member 20G is an example of a first acoustic member.

[0203] The housing 21G has a through hole 212 formed at the same position as the sound input port of the sound path 202 and is attached to the covering member 20G. Note that the housing 21G is an example of a second acoustic member. The housing 21G is the housing of an electric device including the sound collection device 1G. The housing 21G is joined to the surface on which the Helmholtz resonator 14 of the covering member 20 is formed.

[0204] The cross sections of the open end on the input side and the open end on the output side of the sound path 202 are circular. The sound path 202 is cylindrical. It is preferable that the diameters of the open end on the input side and the open end on the output side of the sound path 202 are the same as the diameter of the sound hole 101 of the microphone 10F. The cross section of the through hole 212 is, for example, circular. It is preferable that the diameter of the through hole 212 is the same as the diameter of the open end on the input side of the sound path 202.

[0205] The Helmholtz resonator 14 has an opening 143 formed on the wall surface surrounding the sound path 202. The Helmholtz resonator 14 is formed in a direction perpendicular to the wall surface surrounding the sound path 202. The Helmholtz resonator 14 is an example of a resonator. The shape of the Helmholtz resonator 14 in the modification of Embodiment 7 is the same as the shape of the Helmholtz resonator 14 in Embodiment 1.

[0206] According to the modification of Embodiment 7, even if the microphone 10F is an electret condenser microphone, the peak generated in the ultrasonic band can be reduced by the Helmholtz resonator 14, and the frequency characteristics can be made substantially flat. Further, since the Helmholtz resonator 14 is formed in the covering member 20G that covers the microphone 10F, the formation process of the Helmholtz resonator 14 is easy, and the existing housing 21G can be used.

[0207] Note that the through hole 212 of the housing 21G in the modification of Embodiment 7 may be formed in a tapered shape from the sound input port toward the inside of the through hole 212, similar to Embodiment 2.

[0208] Further, a sound absorbing material may be disposed inside at least one of the neck portion 141 and the cavity portion 142 of the Helmholtz resonator 14 in the modification of Embodiment 7, similar to Embodiment 3.

[0209] Further, the sound collecting device 1G in the modification of Embodiment 7 may include a first Helmholtz resonator 14A and a second Helmholtz resonator 14B, similar to Embodiment 4.

Industrial Applicability

[0210] The technology according to the present disclosure can reduce the peak generated in the ultrasonic band and can prevent the sensitivity from decreasing in the entire frequency band, and thus is useful as a technology for collecting sound using a microphone.

Claims

1. A diaphragm that vibrates according to the sound pressure of the input sound, An acoustic member having a sound path formed to guide sound to the diaphragm, A resonator having an opening formed in a wall surface surrounding the sound path, Comprising, The diaphragm is disposed inside a microphone in which sound holes are formed, The acoustic member is disposed between the sound hole and the diaphragm, The resonator is formed in a direction perpendicular to the wall surface surrounding the sound path, A sound collection device.

2. The resonator is a Helmholtz resonator, The sound collection device according to Claim 1.

3. The resonator is, A neck portion formed around the sound path and having a space with a first volume, A cavity portion formed around the neck portion and having a space with a second volume larger than the first volume, Including, The sound collection device according to Claim 1 or 2.

4. The neck portion is an annular space surrounding the sound path, The cavity portion is an annular space surrounding the neck portion, The sound collection device according to Claim 3.

5. The neck portion is a tubular space extending radially from the wall surface of the sound path, The cavity portion is an annular space surrounding the neck portion, The sound collection device according to Claim 3.

6. The neck portion is a tubular space extending radially from the wall surface of the sound path, The cavity portion is provided separately from the neck portion, The sound collection device according to Claim 3.

7. Further comprising a sound absorption material disposed inside at least one of the neck portion and the cavity portion, The sound collection device according to Claim 3.

8. The resonator is, A first resonator formed in a direction perpendicular to the wall surface surrounding the sound path, A second resonator formed outside the first resonator and having an opening connected to the first resonator, Including, The sound collection device according to Claim 1 or 2.

9. The microphone is a MEMS (Micro Electro Mechanical Systems) microphone, The sound collection device according to Claim 1 or 2.

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