Acoustic reproduction device

Abstract

The present invention provides, for example, an acoustic reproduction device having a structure capable of effectively vibrating particles which the acoustic reproduction device has.　This acoustic reproduction device comprises: a housing having an internal space; a driver unit stored in the internal space of the housing; and a powder storage part in which powder is stored. The driver unit has a back surface part on the opposite side from the radiation direction of sound reproduced from the driver unit, and at least part of the back surface part and the powder storage part are acoustically and spatially connected.

Description

sound reproduction device

[0001] The present disclosure relates to a sound reproduction device.

[0002] Sound reproduction devices such as earphones that can be worn on the ears are becoming smaller. As sound reproduction devices become smaller, the driver units that reproduce sound also become smaller. As the driver units become smaller, sound pressure, particularly in the low range (low frequency range), becomes insufficient, and techniques to compensate for this insufficient sound pressure have been proposed. For example, Patent Document 1 listed below describes a microspeaker that improves low-range sound pressure by arranging zeolite as an air adsorbent inside the enclosure and causing it to resonate (vibrate).

[0003] Japanese Patent Application Laid-Open No. 2017-123647

[0004] The technology described in Patent Document 1 simply arranges zeolite around the speaker unit, which is insufficient in terms of arrangement that allows the zeolite to vibrate efficiently, and there is room for improvement.

[0005] An object of the present disclosure is to provide a sound reproducing device having a structure that can effectively vibrate particles contained in the sound reproducing device.

[0006] The present disclosure relates to an acoustic reproduction device that has, for example, a housing having an internal space, a driver unit housed in the internal space of the housing, and a powder storage section in which powder is housed, wherein the driver unit has a rear section that is on the opposite side to the radiation direction of sound reproduced from the driver unit, and at least a part of the rear section and the powder storage section are acoustically connected.

[0007] 1A and 1B are diagrams to be referred to when describing the background of the present disclosure. FIG. 1A is a diagram to be referred to when describing the background of the present disclosure. FIG. 1B is a diagram to explain an example of the external configuration of an earphone device according to a first embodiment. FIG. 1C is a diagram to explain an example of the external configuration of an earphone device according to the first embodiment. FIG. 1D is a diagram to explain an example of the external configuration of an earphone device according to the first embodiment. FIG. 1E is a diagram to explain an example of a usage state of the earphone device according to the first embodiment. FIG. 1F is a diagram to explain an example of the internal configuration of an earphone device according to the first embodiment. FIG. 1G is a partial cross-sectional view to explain an example of the internal configuration of an earphone device according to the first embodiment. FIG. 1H is a partial cross-sectional view to explain an example of the internal configuration of an earphone device according to the first embodiment. FIG. 1I is a diagram to explain an example of the internal configuration of an earphone device according to the first embodiment. A and B are diagrams to explain a front part and a rear part of a main body of a MEMS driver unit according to the first embodiment. A and B are diagrams to explain an example of the configuration of a MEMS driver according to the first embodiment. A and B are diagrams to explain an example of the configuration of a MEMS microphone according to the first embodiment. A schematic diagram showing how a MEMS driver and a MEMS microphone are housed in a main body of a MEMS driver unit. FIG. 1 is a diagram for explaining an example of the arrangement of a MEMS driver and a MEMS microphone. FIG. 1 is a diagram referred to when explaining an example of an effect obtained in the first embodiment. FIGS. 1A and 1B are diagrams referred to when explaining an example of an effect obtained in the first embodiment. FIG. 1 is a diagram referred to when explaining an example of an effect obtained in the first embodiment. FIG. 2 is a diagram for explaining an example of the internal configuration of an earphone device according to a second embodiment. FIG. 3 is a diagram for explaining an example of the internal configuration of an earphone device according to the second embodiment. FIG. 4 is a diagram for explaining an earphone device according to a third embodiment. FIG. 5 is a diagram for explaining an example of the internal configuration of an earphone device according to the third embodiment. FIG. 6 is a partial cross-sectional view for explaining the earphone device according to the third embodiment. FIG. 7 is a partial cross-sectional view for explaining the earphone device according to the third embodiment.10A and 10B are cross-sectional views illustrating an example of a configuration near the boundary between a first housing and a second housing of an earphone device according to a third embodiment.

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The description will be made in the following order: <Background of the Present Disclosure> <First Embodiment> <Second Embodiment> <Third Embodiment> <Modification> The embodiments described below are preferred specific examples of the present disclosure, and the contents of the present disclosure are not limited to these embodiments. Note that the size and positional relationship of components shown in the drawings may be exaggerated for clarity. Furthermore, to prevent the illustrations from becoming too complicated, only some reference symbols may be shown, some parts may be simplified, or cross-sectional hatching may be omitted. Furthermore, in the following description, the same names and symbols indicate the same or similar components, and redundant description will be omitted as appropriate. Furthermore, for convenience of description, directions such as up, down, left, and right are defined, but the present disclosure is not limited to the directions in the description.

[0009] <Background of the Present Disclosure> First, to facilitate understanding of the present disclosure, the background of the present disclosure will be described. As described above, sound reproduction devices such as earphones are becoming increasingly smaller. Accordingly, driver units are becoming smaller, and the diameter of the diaphragm that constitutes the driver unit is also becoming smaller. This results in a decrease in sound pressure, particularly in the low frequency range, and therefore improvement of sound pressure in the low frequency range is desired. Furthermore, some driver units have a structure in which a hole that communicates with the external space is provided on the housing of the sound reproduction device on the side opposite the sound radiation direction, in order to prevent damage to the thin diaphragm. In such a structure, air leaks from the hole, which can cause a phenomenon known as roll-off, in which sound pressure suddenly decreases in the low frequency range beyond a certain frequency. Generally, roll-off occurs at the resonant frequency of the sound reproduction device, and therefore it is desirable to lower the resonant frequency. This is because lowering the resonant frequency can suppress the decrease in sound pressure in the low frequency range.

[0010] As a method for solving the above-mentioned problems, a technique of filling an enclosure with powder has been proposed, as in the technique described in Patent Document 1. FIG. 1 is a diagram schematically illustrating an audio playback device (audio playback device 1) in which powder is filled in an enclosure. The audio playback device 1 has an enclosure 2 and a speaker 3. Sound is played back from the speaker 3. Note that the speaker 3 is, for example, a dynamic speaker, and the driver unit that drives the speaker 3 is omitted or simplified as appropriate. A powder 4 is stored in the enclosure 2. The powder 4 is, for example, composed of a plurality of particles (particles 4a).

[0011] The resonance frequency of the sound reproduction device 1 shown in Fig. 1 will be considered. Fig. 2 is a diagram showing an equivalent circuit modeling each component of the sound reproduction device 1. In Fig. 2, Rms corresponds to the resistance component of the speaker, Cms corresponds to the compliance of the speaker, and Mms corresponds to the diaphragm mass. Furthermore, in the equivalent circuit shown in Fig. 2, Rmb corresponds to the resistance component of the enclosure 2, and Cmb corresponds to the compliance of the enclosure 2. Furthermore, in the equivalent circuit shown in Fig. 2, Rmt corresponds to the resistance component of the powder 4, and Cmt corresponds to the compliance of the powder 4.

[0012] In the equivalent circuit shown in Fig. 2, the mechanical impedance can be expressed by the following equation 1. In each equation below, V represents the volume, ρ represents the density, c represents the speed of sound, and A represents the effective cross-sectional area of ​​the diaphragm.

[0013]

[0014] The compliance relationship of each component can be expressed as a parallel combination, that is, by the following Equation 2.

[0015]

[0016] The compliance Cmb can be expressed by the following formula 3. Note that in formula 3, box indicates that it corresponds to the enclosure 2.

[0017]

[0018] The compliance Cmt can be expressed by the following formula 4. Note that the particle in formula 4 indicates that it corresponds to the powder 4.

[0019]

[0020] The resistance of each component can be expressed as a series combination, that is, by the following Equation 5:

[0021]

[0022] ω=2πf ０ When written as follows, the condition of the resonant frequency can be expressed by the following Equation 6.

[0023]

[0024] As shown in the above formula 6, by increasing the compliance using the powder 4, it is possible to lower the resonance frequency.

[0025] Furthermore, the particles 4a constituting the powder 4 are vibrated. By vibrating the particles 4a, the behavior of the particles 4a as an elastic body and the transfer of energy between the particles 4a can be utilized to simulate a change in the medium through which sound is transmitted. This allows for the reproduction of a physical phenomenon that would normally be impossible to change without applying a different medium, thereby increasing the sound pressure in the low range without changing the structure of the sound reproduction device. Therefore, rather than simply arranging the powder 4, a structure that can efficiently vibrate the particles 4a is required. With the above in mind, the details of the present disclosure will be described using embodiments.

[0026] First Embodiment [Configuration Example of Sound Reproducing Device] In this embodiment and other embodiments, an earphone device that can be worn on a user's ear will be described as an example of a sound reproducing device. However, the sound reproducing device according to the present disclosure is not limited to earphone devices, and can also be applied to, for example, headphones, hearing aids, sound collectors, other wearable devices, and small speaker devices that can be worn on the ears. Furthermore, although the present technology is suitable for small sound reproducing devices that are prone to a decrease in low-frequency sound pressure for the reasons described above, it can also be applied to relatively large, stationary speaker devices, etc.

[0027] In addition, in this embodiment, a MEMS driver unit made with MEMS (Micro Electro Mechanical Systems) will be described as an example of a driver unit that the earphone device has. Because MEMS driver units offer the advantages described below, MEMS driver units are preferred as the driver unit. However, the present technology can also be applied to earphone devices that use dynamic or balanced armature driver units other than MEMS drivers.

[0028] 3 to 5 are diagrams showing examples of the external configuration of the earphone device (earphone device 100A) according to the first embodiment. Fig. 3 is a front view of the earphone device 100A. Figs. 4 and 5 are perspective views of the earphone device 100A viewed from different directions.

[0029] The earphone device 100A plays audio signals transmitted wirelessly from, for example, a portable music player or a smartphone (not shown). Examples of communication standards for wireless transmission include, but are not limited to, Bluetooth (registered trademark) and wireless LAN (Local Area Network). The earphone device 100A may also play audio signals transmitted via a cable.

[0030] The earphone device 100A has, for example, a housing 10 having an internal space (hereinafter, also referred to as the internal space, as appropriate). The housing 10 is made of resin, such as ABS (Acrylonitrile Butadiene Styrene) resin, but may also be made of metal, wood, or a combination thereof. The housing 10 according to this embodiment has a configuration in which multiple housing parts are fitted together. For example, the housing 10 has a configuration in which three housing parts (a first housing part 11, a second housing part 12, and a third housing part 13) are fitted together. An example of the boundaries between the housing parts is indicated by boundary lines L1 and L2.

[0031] For example, a convex portion is formed on the end face of the first housing portion 11 at each boundary. A groove portion that engages with the convex portion is formed on the end face of the second housing portion 12 and the end face of the third housing portion 13 at each boundary. The housing portions are integrated by fitting the convex portion into the groove. Note that the end faces of the three housing portions may be flat, for example, and integrated by gluing the end faces together. The housing 10 may also be composed of a single housing portion. Note that in the following description, an example configuration of the housing 10 will be described by defining the up, down, left, and right directions based on the direction as viewed in FIG. 3.

[0032] The first housing 11 has, for example, a generally truncated cone shape and has a generally flat upper surface 11A. A gently sloping downward slope 11B is formed on the right side of the flat surface 11A. The first housing 11 is the largest of the three housings and occupies a large portion of the housing 10.

[0033] The second housing 12 has, for example, a C-shaped end face. The second housing 12 is attached to a part of the peripheral edge of the lower surface of the first housing 11.

[0034] The third housing portion 13 protrudes downward from the right side of the underside of the first housing portion 11. The third housing portion 13 has a sound conduit 13A at its tip. The sound conduit 13A has a cylindrical shape, and its end face is an open end 13B. Sound reproduced by the driver unit arranged inside the housing 10 is emitted to the outside via the open end 13B of the sound conduit 13A.

[0035] When using the earphone device 100A, the sound conduit 13A is inserted into the user's ear canal. However, if the sound conduit 13A comes into direct contact with the ear canal, there is a risk that the user may feel discomfort or pain. Therefore, as shown in Fig. 6, when the user uses the earphone device 100A, the user first attaches the earpiece 14 to the sound conduit 13A.

[0036] The earpiece 14 is made of a material such as silicone rubber, urethane resin, or acrylic resin, and is an elastically deformable attachment component. The earpiece 14 has an internal hole, and as shown in FIG. 6 , the sound conduit 13A is inserted into the hole, thereby attaching the earpiece 14 to the outside of the sound conduit 13A. Because the earpiece 14 is elastically deformable, its diameter increases slightly when inserted into the sound conduit 13A, allowing the earpiece 14 to be smoothly inserted into the sound conduit 13A. The earpiece 14 has an opening at its tip, which is configured so as not to obstruct the passage of sound emitted from the open end 13B into the ear. The earpiece 14 may also have a mesh-like configuration without an opening. When the earphone device 100A is attached to the user's ear, the earpiece 14 elastically deforms to fit closely to the ear canal of the user's ear. This prevents sound reproduced from the sound conduit 13A from leaking to the outside.

[0037] Each of the first housing unit 11, the second housing unit 12, and the third housing unit 13 has an internal space. When the three housing units are fitted together, the internal spaces of the respective housing units communicate with each other, forming the internal space of the housing 10. The housing 10 may be provided with minute holes (e.g., holes with a diameter of 10 μm or more) for connecting the internal space of the housing 10 to the external space, or holes for performing noise cancellation processing.

[0038] (Internal Configuration Example) Next, an internal configuration example of the earphone device 100A will be described with reference to Figs. 7 to 12. Figs. 7 and 8 are diagrams for explaining an internal configuration example of the earphone device 100A, with the outer outline indicated by dotted lines and the components arranged inside the housing 10 indicated by solid lines. Figs. 9 and 10 are partial cross-sectional views for explaining a schematic internal configuration example of the earphone device 100A. Fig. 11 is a diagram for explaining a detailed internal configuration example of the earphone device 100A. Fig. 12A is a diagram for explaining the front section (front section 22 described later), and Fig. 12B is a diagram for explaining the back section (back section 23 described later).

[0039] An internal space S is formed inside housing 10. A MEMS driver unit 20, which is a driver unit according to the present embodiment, is disposed and housed in this internal space S. MEMS driver unit 20 is supported in internal space S using, for example, an appropriate support body (not shown). There are no particular limitations on the position at which MEMS driver unit 20 is disposed in internal space S, but it is preferable that it be in a position close to open end 13B of sound conduit 13A.

[0040] The MEMS driver unit 20 has, for example, a main body 21. The main body 21 is made of resin, metal, or the like. The main body 21 has a substantially cylindrical shape, and a space is formed inside it. However, the shape of the main body 21 may be a shape other than a cylindrical shape (for example, a rectangular prism). A MEMS driver (a MEMS driver 50 described later) and a MEMS microphone (a MEMS microphone 60 described later) are housed in the internal space of the main body 21.

[0041] The end face of the cylindrical main body 21 is, for example, an open end that is open except for the periphery. For example, as shown in Fig. 12A , the front face (hereinafter referred to as the front face 22), which is one end face of the main body 21, has a periphery 22A and a circular opening 22B that leads to the internal space of the main body 21. As shown in Fig. 12B , the back face (hereinafter referred to as the back face 23), which is the other end face of the main body 21, has a periphery 23A and a circular opening 23B that leads to the internal space of the main body 21. Note that the shapes of the openings 22B and 23B may not be circular but may be rectangular, etc.

[0042] Front surface portion 22 is disposed in a position generally opposite open end 13B of sound conduit 13A (see FIG. 7 ). Sound reproduced by MEMS driver unit 20 is emitted into sound conduit 13A via front surface portion 22, and then emitted to the outside via open end 13B of sound conduit 13A. This sound emitted to the outside reaches the user's eardrum, and is heard by the user. In other words, MEMS driver unit 20 has front surface portion 22 which is the direction in which sound is radiated, and back surface portion 23 which is on the opposite side of front surface portion 22, i.e., the opposite side to the direction in which sound reproduced from MEMS driver unit 20 is radiated.

[0043] Additionally, a powder storage section 30 that functions as a resonance region is disposed in the internal space S of the housing 10. The powder storage section 30 is made of, for example, resin or metal. The powder storage section 30 has, for example, a generally cylindrical shape thinner than the main body section 21, circular end face sections 31 and 32 at both ends, and a peripheral surface section 33 connecting the end face sections 31 and 32. For example, the diameters of the end face sections 31 and 32 are generally the same as the diameter of the back surface section 23. The interior of the powder storage section 30 is a space, and powder is stored in this space. This powder is composed of a plurality of particles 35 (see FIGS. 9 and 10 ). The type of particles 35 is not particularly limited, but non-conductive particles are preferable from the viewpoint of safety. Zeolite is an example of such particles 35, but particles other than zeolite (porous carbon materials (e.g., Triporous (a trademark of Sony Group Corporation)) can also be used. The size of the particles 35 is not particularly limited, but from the viewpoint of achieving the effects obtained by this embodiment, it is preferable that the diameter be 5 mm or less. This diameter can be defined as the average particle size when a predetermined number of particles 35 (e.g., approximately 100 particles) are extracted as a sample. Note that the number and arrangement of the particles 35 shown in FIGS. 9 and 10 are merely schematic examples and are not limited to the examples shown.

[0044] The particles 35 are stored (filled) in the powder storage section 30, for example, by the following method. Microscopic holes for injecting the particles 35 are provided in the powder storage section 30. Then, using an appropriate filling device having, for example, a needle-shaped filling member, the filling member is pierced into the microscopic holes, and the particles 35 are pushed out in this state for a predetermined period of time, filling the powder storage section 30. The microscopic holes are then sealed, thereby storing the particles 35 in the powder storage section 30. After storing the particles 35 in the powder storage section 30, the particles 35 are agitated by vibrating the powder storage section 30. When the particles 35 are filled into the powder storage section 30 by this method, the arrangement of the particles 35 is larger than a simple cubic lattice and is equal to or greater than a body-centered cubic lattice, resulting in a filling rate of 68% or more.

[0045] MEMS driver unit 20 and powder storage unit 30 are acoustically spatially connected. Here, in this specification, being acoustically spatially connected means that when a driver unit (e.g., MEMS driver unit 20) operates to play sound, air vibrations toward the rear surface portion (e.g., rear surface portion 23) that accompany the sound playback propagate to the powder storage unit (e.g., powder storage unit 30 and particles 35).

[0046] For example, in this embodiment, one end surface 31 of the powder storage unit 30 is directly connected to the peripheral edge 23A, which is part of the back surface 23 of the main body 21 (see FIGS. 9 and 10 ). For example, one end surface 31 of the powder storage unit 30 is adhered to the peripheral edge 23A. Here, "directly connected" means that no components other than components for connection (e.g., an adhesive layer) are included between the one end surface 31 of the powder storage unit 30 and the peripheral edge 23A of the back surface 23. As a result, when the MEMS driver unit 20 reproduces sound, air vibrations toward the back surface 23 are propagated to the powder storage unit 30 via the opening 23B of the back surface 23.

[0047] As shown in Fig. 11 , the MEMS driver unit 20 and the powder storage section 30 are disposed near the space SA on the far side of the position of the sound conduit 13A. Note that to prevent the illustration from becoming complicated, the MEMS driver unit 20 and the powder storage section 30 are omitted from Fig. 11 .

[0048] In addition to the MEMS driver unit 20 and the powder storage unit 30, the internal space S also contains, for example, a circuit unit 41. The circuit unit 41 is disposed, for example, slightly further back than the position in the internal space S where the powder storage unit 30 is disposed. The circuit unit 41 includes, for example, a substrate and an IC (Integrated Circuit) mounted on the substrate. Examples of the IC include a communication circuit that receives an audio signal from an external device such as a smartphone or a portable audio player, an acoustic processing circuit that performs known acoustic processing, an amplifier that amplifies the audio signal, a circuit that performs noise cancellation processing, and the like.

[0049] For example, the circuit that performs noise cancellation in the circuit unit 41 is connected to a MEMS microphone (MEMS microphone 60 described below), which is a microphone for feedback noise cancellation, and a microphone for feedforward noise cancellation (not shown). The circuit unit 41 is also connected to a MEMS driver (MEMS driver 50 described below), and is configured so that audio signals received by the circuit unit 41 from an external device are appropriately amplified and then supplied to the MEMS driver. The MEMS driver operates based on the supplied audio signals. Note that the illustration of these connection patterns is simplified or omitted as appropriate.

[0050] Within the internal space S, a battery (not shown), for example, is disposed near the internal space SB, which is partitioned mainly by the first housing 11 and has a large capacity. Each part of the earphone device 100A, including the IC included in the circuit unit 41 described above, operates based on power supplied from the battery.

[0051] [Configuration Example of MEMS Driver Unit] Next, a configuration example of the MEMS driver unit 20 will be described. The MEMS driver unit 20 has, for example, a MEMS driver 50 and a MEMS microphone 60. Each of the MEMS driver 50 and the MEMS microphone 60 is a MEMS device manufactured through a MEMS process. Note that in this specification, a MEMS device is a device formed by microfabrication technology (MEMS process) that applies a semiconductor element manufacturing process. Furthermore, the MEMS device in this specification may include, as part of its configuration, mechanical components that are not formed by the MEMS process. However, from the perspective of further miniaturizing the entire MEMS device, it is preferable that the entire MEMS device be formed automatically by the MEMS process.

[0052] An example of a MEMS process will be described. The MEMS process includes, for example, the following steps: S1 Film formation step: A thin film that serves as a mask material is formed on a substrate such as silicon. S2 Photolithography step: A resist (photosensitive resin) is applied or attached to the thin film, and a pattern is formed by irradiating light through a photomask. S3 Etching step: Unnecessary portions of the thin film, silicon substrate, etc. are removed using gas or chemicals. S4 Bonding step: Multiple substrates are bonded together. S5 A cutting (dicing) step and a packaging step are performed to complete the MEMS device. Note that the above MEMS process is an example, and some steps may be omitted or other steps may be added.

[0053] The MEMS driver 50 can be produced using only the MEMS process, which offers the advantage of enabling miniaturization (miniaturization). Furthermore, automated mass production is possible, which offers a price advantage. These advantages apply not only to the MEMS driver 50 but also to the MEMS microphone 60.

[0054] FIG. 13A shows an example of the appearance of a MEMS driver 50 according to this embodiment, and FIG. 13B shows a cross section of the MEMS driver 50 taken along line A-A in FIG. 13A . As shown in FIG. 13A , the MEMS driver 50 according to this embodiment has a housing 51 that is generally rectangular (chip-shaped). The housing 51 has a top surface 51A and a bottom surface 51B opposite the top surface 51A. The top surface 51A is the upper main surface in FIG. 13A (the surface having a larger area than the other surfaces), and the bottom surface 51B is the lower main surface in FIG. 13A . A hole 52 that functions as a sound hole is formed in the top surface 51A. The hole 52 is, for example, a rectangular hole.

[0055] As shown in Fig. 13B , a diaphragm 54 is provided inside the housing 51. The diaphragm 54 is supported by support members or the like so as to span the left and right side surfaces 51C, 51D in Figs. 13A and 13B . As described above, each component of the MEMS driver 50 is formed by the MEMS process. The diaphragm 54 vibrates based on an audio signal supplied to the MEMS driver 50, thereby generating sound corresponding to the audio signal. The sound generated by the diaphragm 54 is emitted from the hole 52.

[0056] FIG. 14A shows an example of the appearance of a MEMS microphone 60 according to this embodiment, and FIG. 14B shows a cross section of the MEMS microphone 60 taken along line B-B in FIG. 14A . As shown in FIG. 14A , the MEMS microphone 60 according to this embodiment has a housing 61 that is generally rectangular (chip-shaped). A hole 62 is formed in, for example, an upper surface 61A of the housing 61. The hole 62 is, for example, a rectangular hole. As shown in FIG. 14B , a diaphragm 64 is provided within the housing 61. The diaphragm 64 is supported by a support member or the like so as to span the left and right side surfaces 61C and 61D in FIGS. 14A and 14B . As described above, each component of the MEMS microphone 60 is formed by a MEMS process.

[0057] The MEMS microphone 60 is a microphone that picks up the reproduced sound reproduced from the above-described MEMS driver 50. That is, the reproduced sound emitted from the hole 52 of the MEMS driver 50 is taken into the housing 61 through the hole 62 of the MEMS microphone 60. The sound taken into the housing 61 causes the diaphragm 64 to vibrate, thereby picking up and detecting the reproduced sound from the MEMS driver 50. Note that the sound picked up by the MEMS microphone 60 may include not only the sound reproduced from the MEMS driver 50 but also noise.

[0058] The MEMS microphone 60 is used, for example, as a feedback noise cancellation microphone for performing noise cancellation using a feedback method. Sound is picked up by the MEMS microphone 60, and a signal that is opposite in phase to the sound signal that may contain noise is generated as a noise cancellation signal. By performing a known noise cancellation process using the noise cancellation signal, noise that may be included in the sound reproduced from the MEMS driver 50 is removed or reduced.

[0059] It should be noted that known devices other than those having the above-described configurations can also be applied as the MEMS driver 50 and the MEMS microphone 60 .

[0060] The MEMS driver 50 and the MEMS microphone 60 are housed in the main body 21 of the MEMS driver unit 20. For example, as schematically shown in Fig. 15 , the MEMS driver 50 and the MEMS microphone 60 are housed in the main body 21 through an opening 23B in the rear surface 23.

[0061] FIG. 16 is a diagram illustrating an example of the arrangement of the MEMS driver 50 and the MEMS microphone 60. For example, the MEMS driver 50 and the MEMS microphone 60 are attached to the inner surface of the main body 21 by adhesive or the like. More specifically, as shown in FIG. 16 , the bottom surface 51B of the MEMS driver 50 is adhered to the inner surface of the main body 21, and the bottom surface 61B of the MEMS microphone 60 is adhered to the inner surface of the main body 21. Furthermore, as shown in FIG. 16 , the MEMS driver 50 and the MEMS microphone 60 are arranged so that the hole 52 of the MEMS driver 50 faces the hole 62 of the MEMS microphone 60. This allows the MEMS microphone 60 to efficiently pick up sound reproduced by the MEMS driver 50. Note that the MEMS driver 50 and the MEMS microphone 60 may be supported within the main body 21 by an appropriate support member or the like instead of by adhesive.

[0062] [Example of Earphone Device Operation] Next, an example of operation of the earphone device 100A will be described. An audio signal is transmitted to the earphone device 100A, for example, via wireless communication. After a communication unit (not shown) of the earphone device 100A receives the audio signal and performs known audio signal processing, the audio signal is supplied to the MEMS driver 50. The diaphragm 54 vibrates based on the audio signal supplied to the MEMS driver 50, thereby generating sound corresponding to the audio signal. The sound generated by the diaphragm 54 is emitted from the hole 52. The sound emitted from the hole 52 is then emitted to the outside of the earphone device 100A through the opening 22B in the front surface 22 of the main body 21, where it is heard by the user. As described above, the sound reproduced from the MEMS driver 50 is picked up by the MEMS microphone 60 and used for noise cancellation processing.

[0063] Furthermore, vibrations caused by the sound emitted from the hole 52 are also propagated to the rear surface 23 of the main body 21. These vibrations are propagated through the opening 23B of the rear surface 23 to the powder storage section 30 connected to the rear surface 23. This causes the particles 35 in the powder storage section 30 to vibrate. The vibration of the particles 35 provides the aforementioned effects of increasing the sound pressure and lowering the resonance frequency.

[0064] [Effects] According to this embodiment, for example, the following effects can be obtained. By acoustically spatially connecting the powder storage unit 30 to the rear surface 23 of the MEMS driver unit 20, vibrations generated during sound reproduction can be efficiently propagated to the powder storage unit 30. This allows the particles 35 stored in the powder storage unit 30 to be effectively vibrated. Because the particles 35 can be effectively vibrated, the effect of increasing sound pressure due to particle vibration can be improved. Furthermore, because particle vibration can increase the viscous resistance of the entire powder consisting of multiple particles 35, the resonance frequency can be lowered. FIG. 17 is a diagram for explaining the effects obtained by this embodiment. In the graph shown in FIG. 17, the horizontal axis represents frequency and the vertical axis represents sound pressure. In addition, in the graph shown in FIG. 17, the solid line LN1 represents the frequency characteristics of the earphone device before applying powder, and the dotted line LN2 represents the frequency characteristics of the earphone device after applying powder. As shown schematically in FIG. 17 , applying powder as in this embodiment can lower the resonant frequency (the frequency at which sound pressure drops sharply) compared to before applying the powder, thereby improving sound pressure, particularly in the low-frequency range. FIGS. 18A and 18B show example measurement results. FIG. 18A shows the measurement results when a piezoelectric MEMS speaker is used as the driver unit, and FIG. 18B shows the measurement results when an electrodynamic speaker is used as the driver unit. The horizontal axis of FIGS. 18A and 18B represents frequency, and the vertical axis represents sound pressure level. Line LN1a in FIG. 18A represents an example in which zeolite was used as the powder, while line LN2a in FIG. 18A represents an example in which no powder was used. Line LN1b in FIG. 18B represents an example in which zeolite was used as the powder, while line LN2b in FIG. 18B represents an example in which no powder was used. As shown in FIGS. 18A and 18B , applying powder can improve low-frequency sound pressure by approximately 5 dB. Fig. 19 shows changes in the resonant frequency and changes in the amount of increase in sound pressure relative to the filling rate of the particles 35 in the powder containing section 30. In the graph shown in Fig. 19, the horizontal axis represents the filling rate of the particles 35, and the vertical axis represents the resonant frequency or the amount of increase in sound pressure.19, the solid line LN3 indicates the change in resonant frequency with respect to the filling rate, and the dotted line LN4 indicates the change in sound pressure increase with respect to the filling rate. As shown in FIG. 19, when the filling rate is 68% or higher, the resonant frequency is significantly reduced and the sound pressure increase is large. In this embodiment, the particles 35 are arranged in a body-centered cubic lattice or higher and the filling rate is 68% or higher, so the resonant frequency can be further reduced and the sound pressure increase can be increased.

[0065] [Modification of First Embodiment] In the above-described embodiment, the configuration in which the rear surface portion 23 has the opening 23B has been described, but the entire rear surface portion 23 may be a mesh surface portion. The end surface portion 31 of the powder containing portion 30 may be connected to the entire mesh surface portion, in other words, the entire rear surface portion 23.

[0066] Second Embodiment Next, a second embodiment will be described. In the description of the second embodiment, the same or similar components as those in the above description will be denoted by the same reference numerals, and duplicated descriptions will be omitted as appropriate. Furthermore, unless otherwise specified, the matters described in the first embodiment can be applied to the second embodiment.

[0067] In this embodiment, generally speaking, at least a part of the rear surface of the driver unit and the powder storage section are acoustically connected via a connecting section.

[0068] 20 is a diagram showing an example of the configuration of an earphone device (earphone device 100B) according to the second embodiment. Like the earphone device 100A, the earphone device 100B has a housing 10, and a MEMS driver unit 20 is housed within the housing 10. In this embodiment, the powder storage unit 30 is not connected to the rear surface portion 23 of the MEMS driver unit 20, but rather to a connecting portion 71. In this embodiment, the powder storage unit 30 is located slightly away from the MEMS driver unit 20, for example, in the space within the first housing portion 11.

[0069] The connecting portion 71 is a member for acoustically connecting the MEMS driver unit 20 and the powder containing portion 30. The connecting portion 71 is made of resin or metal.

[0070] Fig. 21 is a schematic cross-sectional view illustrating an example configuration of the connecting portion 71. Note that Fig. 21 is a diagram showing only some of the components of the earphone device 100B, and the illustration is partially simplified for ease of understanding.

[0071] 20 and 21 , the connecting portion 71 has, for example, a first connecting portion 72 and a second connecting portion 73. In this embodiment, the first connecting portion 72 and the second connecting portion 73 are integrally formed, but the first connecting portion 72 and the second connecting portion 73 may be separate components that are connected together to form an integrated unit.

[0072] The first connecting portion 72 is roughly coin-shaped. Specifically, as shown in FIG. 21 , the first connecting portion 72 has a base 72A with a circular end surface. Furthermore, the first connecting portion 72 has a wall portion 72B extending downward from the periphery of the base 72A. The tip surface of the wall portion 72B forms a ring-shaped end surface 72C. The end surface 72C is connected to the periphery 23A of the rear surface portion 23 of the MEMS driver unit 20 by adhesive or the like. With this configuration, a space SD inside the first connecting portion 72, defined by the base 72A and the wall portion 72B, communicates with the inside of the main body portion 21 of the MEMS driver unit 20 via the opening 23B. A continuous internal space SE is formed inside the base 72A and the wall portion 72B. A hole 72D is formed on the inner surface of the wall portion 72B, communicating the space SD with the internal space SE.

[0073] The second connecting portion 73 has a tubular shape. As shown in Fig. 21 , the second connecting portion 73 is connected to the outer side surface 72E of the wall portion 72B. The second connecting portion 73 also has a tubular internal space SF. One open end of the internal space SF is in communication with the internal space SE of the first connecting portion 72. The other open end of the internal space SF is in contact with the peripheral surface portion 33 of the powder storage portion 30. In other words, the connecting portion 71 according to this embodiment has a hollow shape having the internal space SE and the internal space SF.

[0074] An example of the operation of the earphone device 100B will now be described. An audio signal is transmitted to the earphone device 100B, for example, via wireless communication. After a communication unit (not shown) of the earphone device 100B receives the audio signal and performs known audio signal processing, the audio signal is supplied to the MEMS driver 50. The diaphragm 54 vibrates based on the audio signal supplied to the MEMS driver 50, thereby generating sound corresponding to the audio signal. The sound generated by the diaphragm 54 is emitted from the hole 52. Furthermore, the sound emitted from the hole 52 is emitted to the outside of the earphone device 100B through the opening 22B in the front surface 22 of the main body 21, where the emitted sound is heard by the user. As described above, the sound reproduced from the MEMS driver 50 is collected by the MEMS microphone 60 and used for noise cancellation processing.

[0075] The vibrations caused by the sound emitted from the hole 52 also propagate to the back surface 23 of the main body 21. These vibrations propagate to the space SD through the opening 23B of the back surface 23. The vibrations caused by the sound then propagate further through the hole 72D to the internal space SE of the first connecting portion 72, and then through the internal space SE and the internal space SF to the powder storage portion 30. The propagation of the vibrations causes the particles 35 in the powder storage portion 30 to vibrate. The vibration of the particles 35 provides the aforementioned effects of increasing the sound pressure and lowering the resonant frequency.

[0076] This embodiment also achieves the same effects as the first embodiment. Furthermore, this embodiment uses a connecting portion 71. This allows the powder storage portion 30 to be placed in a location with ample space within the earphone device 100B, for example. In other words, the space within the earphone device 100B can be used effectively. Furthermore, since the powder storage portion 30 can be placed in a location with ample space, the size of the powder storage portion 30 can also be increased. This allows the number of particles 35 to be increased, thereby improving the effects of increasing sound pressure and lowering the resonance frequency.

[0077] It should be noted that the shape of the connecting portion 71 can be changed as appropriate. For example, the connecting portion 71 may be configured to have only the second connecting portion 73, without the first connecting portion 72. Furthermore, one open end of the internal space SF of the second connecting portion 73 may be configured to directly communicate with the space inside the main body portion 21 of the MEMS driver unit 20.

[0078] <Third Embodiment> Next, a third embodiment will be described. In the description of the third embodiment, the same or similar components as those in the above description will be denoted by the same reference numerals, and duplicated descriptions will be omitted as appropriate. Furthermore, unless otherwise specified, the matters described in the first and second embodiments can be applied to the third embodiment.

[0079] An example configuration of an earphone device (earphone device 100C) according to the third embodiment will be described with reference to Figs. 22 to 27. Fig. 22 is a plan view of the earphone device 100C. As shown in Fig. 22, the housing 10 of the earphone device 100C has two housing parts (a first housing part 15 according to the present embodiment and a second housing part 16 according to the present embodiment). As viewed in Fig. 22, the first housing part 15 is disposed on the upper side, and the second housing part 16 is disposed on the lower side. The housing 10 according to the present embodiment is configured by fitting the first housing part 15 and the second housing part 16 together. In Fig. 22, the boundary between the first housing part 15 and the second housing part 16 is indicated by a boundary line L3.

[0080] 23 and 24 , in this embodiment, the powder containing section 30 is disposed along the boundary line L3. The powder containing section 30 according to this embodiment generally has a shape (e.g., a ring shape) that follows the boundary line L3.

[0081] The earphone device 100C has a MEMS driver unit 20 and a connecting portion 71 (a first connecting portion 72 and a second connecting portion 73) housed in a housing 10, similar to the earphone device 100B.

[0082] 23 to 26 , one end of the second connecting portion 73 is connected to an appropriate location on the powder containing portion 30. As a result, similar to the earphone device 100B, the back surface portion 23 of the MEMS driver unit 20 and the powder containing portion 30 are connected in acoustic space.

[0083] A specific example of the configuration will be described with reference to Fig. 27. Fig. 27 is an enlarged cross-sectional view showing components in the vicinity of boundary line L3.

[0084] A convex portion 15A is formed near the center of the end face of the first housing portion 15 (the face that mates with the end face of the second housing portion 16). On the other hand, a substantially concave groove portion 16A that engages with the convex portion 15A is formed on the end face of the second housing portion 16 (the face that mates with the end face of the first housing portion 15).

[0085] The powder containing portion 30 is disposed in the groove portion 16A. For example, the powder containing portion 30 is disposed in the groove portion 16A so that the bottom of the groove portion 16A and the lower end surface portion 31 of the powder containing portion 30 are in contact with each other.

[0086] In this state, the convex portion 15A and the groove portion 16A are fitted together, thereby integrating the first housing portion 15 and the second housing portion 16. At this time, an O-ring 17, which is an elastic member, is used to prevent foreign matter such as moisture from entering the housing 10. For example, the O-ring 17 is placed on the upper end surface portion 32 of the powder storage portion 30, and is crushed when the convex portion 15A and the groove portion 16A are fitted together. This improves the airtightness of the housing 10, making it possible to prevent foreign matter from entering from the outside.

[0087] The second housing 16 has a notch 18 that communicates with the groove 16A. As shown in Fig. 27 , the notch 18 is provided, for example, to communicate from the internal space S of the housing 10 to the bottom of the groove 16A. The second connecting portion 73 is connected to the lower end surface 31 of the powder storage portion 30 via the notch 18. That is, the internal space SF within the second connecting portion 73 comes into contact with the powder storage portion 30.

[0088] An example of the operation of the earphone device 100C will now be described. An audio signal is transmitted to the earphone device 100C, for example, via wireless communication. After a communication unit (not shown) of the earphone device 100C receives the audio signal and performs known audio signal processing, the audio signal is supplied to the MEMS driver 50. The diaphragm 54 vibrates based on the audio signal supplied to the MEMS driver 50, thereby generating sound corresponding to the audio signal. The sound generated by the diaphragm 54 is emitted from the hole 52. Furthermore, the sound emitted from the hole 52 is emitted to the outside of the earphone device 100C through the opening 22B in the front surface 22 of the main body 21, where the emitted sound is heard by the user. As described above, the sound reproduced from the MEMS driver 50 is collected by the MEMS microphone 60 and used for noise cancellation processing.

[0089] Vibrations caused by the sound emitted from the hole 52 also propagate to the rear surface 23 of the main body 21. These vibrations propagate to the space SD through the opening 23B of the rear surface 23. The vibrations caused by the sound then propagate further through the hole 72D to the internal space SE of the first connecting portion 72, and then through the internal space SE and the internal space SF to the powder storage portion 30. The propagation of the vibrations causes the particles 35 in the powder storage portion 30 to vibrate. The vibration of the particles 35 provides the aforementioned effects of increasing sound pressure and lowering the resonant frequency. The sound generated by the vibration of the particles 35 propagates into the housing 10, for example, through the cutout 18.

[0090] This embodiment also achieves the same effects as the first embodiment. Furthermore, earphone devices have become increasingly smaller in recent years, and some earphone devices may not have enough space to place new components in the internal space of the housing 10. In this embodiment, even if there is limited space within the housing 10, the powder storage section 30 can be placed near the boundary between the housing sections. In other words, even if there is limited space within the housing 10, the effect of increasing sound pressure due to the vibration of the particles 35 can be achieved, and the resonant frequency can be lowered.

[0091] Although the present embodiment has been described with reference to an example having two housing sections, even when there are three or more housing sections, it is also possible to arrange the powder storage section 30 on the entire boundary between the housing sections or on part of the boundary. A groove may be formed in the first housing section 15, and a protrusion may be formed in the second housing section 16. Furthermore, to enable the first housing section 15 and the second housing section 16 to be fitted together more firmly, a locking piece or the like that can be hooked onto an appropriate location on the second housing section 16 may be provided on the first housing section 15.

[0092] <Modifications> Although the embodiments of the present disclosure have been specifically described above, the contents of the present disclosure are not limited to the above-described embodiments, and various modifications based on the technical ideas of the present disclosure are possible.

[0093] 28, if there is sufficient space within the housing, the capacity of the powder storage section 30 may be increased and the number of particles 35 may be increased. This can further improve the effects of increasing sound pressure and the like obtained by the vibration of the particles 35.

[0094] The shape of the MEMS driver 50 and the like may be other than those described in the embodiments. For example, the housing of the MEMS driver 50 or the MEMS microphone 60 may be cylindrical. The shape of the holes of the MEMS driver 50 or the MEMS microphone 60 is not limited to rectangular, and may be circular, elliptical, polygonal, or the like.

[0095] In the above-described embodiment, the MEMS driver 50 and the MEMS microphone 60 are described as separate MEMS devices. However, the MEMS driver 50 and the MEMS microphone 60 may be a MEMS device integrally constructed by a single MEMS process. Furthermore, as schematically shown in FIG. 29 , all of the components of the MEMS driver unit 20, such as the main body 21 of the MEMS driver unit 20, the MEMS driver 50, and the MEMS microphone 60, may be a MEMS device integrally constructed by a single MEMS process. For example, the MEMS driver 50 and the MEMS microphone 60 may be formed by a MEMS process on the inner surface of the main body 21 obtained by shaping a silicon substrate or the like. Furthermore, in addition to the MEMS driver 50 and the MEMS microphone 60, the MEMS driver unit 20 may also include a MEMS sensor fabricated by a MEMS process. Examples of the MEMS sensor include a biosensor that acquires biometric information of the user of the earphone device and an environmental sensor that measures the surrounding environment.

[0096] The earphone device may have one or more powder storage compartments arranged within its housing. In this case, different types and sizes of particles may be stored in the different powder storage compartments. The shape of the connecting portion according to the embodiment may be modified as appropriate. For example, the connecting portion 71 may be a mesh-like member instead of a hollow member.

[0097] The configurations, methods, steps, shapes, materials, and values ​​described in the above-described embodiments are merely examples, and different configurations, methods, steps, shapes, materials, and values ​​may be used as needed. The above-described embodiments and modifications can be combined as appropriate.

[0098] The effects described in this specification are merely examples and are not limiting, and other effects may also be obtained.

[0099] The present disclosure may also adopt the following configurations. (1) A sound reproduction device comprising: a housing having an internal space; a driver unit housed in the internal space of the housing; and a powder storage section in which powder is housed, wherein the driver unit has a rear section that is on the opposite side to the radiation direction of sound reproduced from the driver unit, and at least a portion of the rear section and the powder storage section are acoustically connected. (2) The sound reproduction device described in (1), wherein at least a portion of the rear section and the powder storage section are acoustically connected directly. (3) The sound reproduction device described in (2), wherein the entire rear section and the powder storage section are acoustically connected directly. (4) The sound reproduction device described in (1), wherein at least a portion of the rear section and the powder storage section are acoustically connected via a connecting section. (5) The sound reproduction device described in (4), wherein the connecting section has a hollow or mesh-like shape. (6) The sound reproducing device according to (4) or (5), wherein the connecting portion is formed of resin or metal. (7) The sound reproducing device according to any of (4) to (6), wherein the housing has at least a first housing portion and a second housing portion that fits with the first housing portion, wherein one of the end faces of the first housing portion and the second housing portion has a groove portion, and wherein the powder storage portion is disposed in the groove portion. (8) The sound reproducing device according to any of (1) to (7), wherein the powder is composed of a plurality of non-conductive particles. (9) The sound reproducing device according to (8), wherein the non-conductive particles are zeolite. (10) The sound reproducing device according to (8) or (9), wherein a content of the non-conductive particles in the powder storage portion is 68% or more. (11) The sound reproducing device according to any of (1) to (10), wherein the driver unit includes a MEMS driver. (12) The sound reproducing device according to any one of (1) to (11), which is wearable on an ear.

[0100] DESCRIPTION OF SYMBOLS 10: Housing 15: First housing section 16: Second housing section 20: MEMS driver unit 23: Back section 30: Powder storage section 35: Particles 50: MEMS driver 71: Connection section 100A, 100B, 100C: Earphone device

Claims

1. An acoustic reproduction device comprising: a housing having an internal space; a driver unit housed in the internal space of the housing; and a powder storage section in which powder is stored, wherein the driver unit has a rear portion that is opposite to the radiation direction of sound reproduced from the driver unit, and at least a part of the rear portion and the powder storage section are acoustically connected.

2. The sound reproducing device according to claim 1, wherein at least a part of the rear surface and the powder storage section are directly connected in acoustic space.

3. The sound reproducing device according to claim 2, wherein the entire rear portion and the powder storage portion are directly connected in acoustic space.

4. The sound reproducing device according to claim 1, wherein at least a part of the rear surface and the powder storage section are acoustically spatially connected via a connecting section.

5. The sound reproducing device according to claim 4, wherein the connecting portion has a hollow or mesh-like shape.

6. The sound reproducing device according to claim 4, wherein the connecting portion is made of resin or metal.

7. The sound reproducing device of claim 4, wherein the housing has at least a first housing part and a second housing part that fits into the first housing part, one of the end faces of the first housing part and the second housing part has a groove part, and the powder storage part is arranged in the groove part.

8. The sound reproducing device according to claim 1, wherein the powder is composed of a plurality of non-conductive particles.

9. The sound reproducing device according to claim 8, wherein the non-conductive particles are zeolite.

10. The sound reproducing device according to claim 8, wherein the content of said non-conductive particles in said powder storage section is 68% or more.

11. The sound reproducing device of claim 1, wherein the driver unit includes a MEMS driver.

12. The sound reproducing device according to claim 1, which is wearable on the ear.

Images