WO2015015646A1

WO2015015646A1 - Microphone cover and sound pickup device

Info

Publication number: WO2015015646A1
Application number: PCT/JP2013/071058
Authority: WO
Inventors: 晃後藤; 好孝村山; 晴丈大野
Original assignee: 共栄エンジニアリング株式会社
Priority date: 2013-08-02
Filing date: 2013-08-02
Publication date: 2015-02-05

Abstract

Provided is a microphone cover that, in addition to water resistance and dust resistance, has a wind resistance function and will not suffer loss of sound quality even if wet with water. Also provided is a sound pickup device using such a microphone cover. A sound pickup device (1) primarily comprises a microphone (11), a holder (6), and a microphone cover (2). The microphone (11) is housed in the holder (6). The microphone cover (2) engages with the holder (6) so as to cover the microphone (11). The microphone cover (2) is made of a mixed material in which an electrically conductive material is mixed in with a resin that is the primary material. The microphone cover (2) is provided with a sound hole surface (3) having a plurality of open holes (4) with aperture widths of at least 0.01 mm and less than 0.8 mm, and the microphone cover suppresses the intrusion of wind into the interior thereof while allowing sound waves to pass through.

Description

Microphone cover and sound collecting device

The present invention relates to a microphone cover that suppresses pressure fluctuation due to wind inside the cover while allowing sound waves to pass through, and a sound collecting device that covers the microphone cover on the microphone.

The microphone is used for sound collection such as acoustic measurement and recording, and converts sound wave vibration into an electrical signal. Examples of the microphone include a dynamic microphone and a condenser microphone.

Dynamic type microphone uses coil electromagnetic induction. The sound wave strikes the diaphragm, the coil swings, and current flows by electromagnetic induction. The vibration change is converted into a current change and collected as an electric signal. The dynamic microphone has an advantage in that the structure is simple and durable.

A capacitor type microphone is provided with a capacitor between a fixed electrode and a vibrating membrane, and changes in the capacitance of the capacitor caused by sound waves vibrating the vibrating membrane are converted into electric signals and collected. The condenser microphone has advantages such as the ability to pick up sound in a wide frequency band, the ability to pick up minute sounds, and the miniaturization.

The microphone is housed in a holder and is covered with a cover from the viewpoint of dustproof, waterproof and windproof. A signal line extending from the microphone is led out from the holder. A device including the microphone, the holder, and the cover is called a sound collecting device.

As a cover for dustproof and waterproof applications, a hard hard cover made of metal or resin is often used (for example, see Patent Document 1). Sound holes are formed in the hard cover, and sound waves are taken from the sound holes to reach the internal microphone.

This hard cover allows the invasion of wind along with sound waves from the sound holes in outdoor, indoor environments where air conditioning is installed, inside the vehicle, indoors where the outside air circulation occurs, and inside the vehicle. The wind that reaches the inside of the hard cover vibrates the diaphragm and the diaphragm in the microphone, and the vibration is collected as wind noise, resulting in a decrease in sound quality.

Therefore, in a windy environment, cover the hard cover with a cloth cover or sponge cover. The sponge cover is made of a porous material such as urethane. The cloth cover and the sponge cover have a windproof effect, and are further covered from the top of the hard cover, thereby providing the sound collecting device with a dustproof, waterproof, and windproof effect for the microphone.

JP 2011-49752 A

In recent years, it is also assumed that a sound collecting device is mounted outside a moving body capable of high speed running such as an automobile. Of course, if the moving body travels at a high speed, the wind pressure against the sound collection device will increase, and it will be possible to sufficiently enter the wind even if it is covered with a sponge cover or cloth cover for windproof purposes as well as a hard cover that is not supposed to be windproof. It cannot be suppressed, and a serious deterioration in sound quality is expected. In particular, in the conventional hard cover, sponge cover, or cloth cover, it is difficult to suppress the internal entry of the wind by the wind pressure exceeding the fluctuation range of the sound pressure.

That is, both sound and wind are pressure fluctuations in the air, but the fluctuation range is greatly different between sound pressure and wind pressure. The audible sound pressure range is 20 μPa to 20 Pa. On the other hand, the fluctuation range of the wind pressure extends to several hundred Pa. For example, the wind pressure at a wind speed of 5 m / s is equivalent to 18.6 Pa≈116 dBSPL, and has a large amplitude with respect to sound. Sponge covers and cloth covers easily allow the wind to pass through wind pressure exceeding the audible sound pressure, allowing the hard cover to enter through the sound holes. Therefore, the microphone picks up wind noise and the sound quality deteriorates.

Furthermore, in a wind and rain environment, the high frequency sound collection performance is degraded by the water absorption of the cloth cover and sponge cover. In particular, when the sound is picked up by a condenser microphone that can pick up sounds in a wide frequency band including high frequencies, the characteristics cannot be fully utilized.

The present invention has been proposed in order to solve the above-described problems. In addition to waterproofing and dustproofing, the present invention has a windshield function and does not cause deterioration in sound quality even when wet, and a cover using the same. An object is to provide a sound device.

In order to achieve the above object, the microphone cover of the present invention is a microphone cover that suppresses the ingress of wind into the cover while allowing sound waves to pass, and is a mixture in which a conductive material is mixed with a resin as a main material. It is characterized by comprising a sound hole surface made of a material and having a plurality of openings having an opening width of 0.01 mm or more and less than 0.8 mm.

In order to achieve the above object, the sound collection device of the present invention includes a microphone, a holder that accommodates the microphone, and the holder that engages with the holder and allows sound waves to pass therethrough while wind enters the cover. A microphone cover that suppresses noise, and the microphone cover is made of a mixed material obtained by mixing a conductive material with a resin as a main material, and has a plurality of openings having an opening width of 0.01 mm or more and less than 0.8 mm. It is characterized by providing a surface.

In the microphone cover and the sound collecting device, the opening of the sound hole surface preferably has an opening width of 0.01 mm to 0.5 mm, and more preferably 0.01 mm to 0.3 mm. It is good to have.

The sound hole surface is made of a mixed material containing a resin as a main material and a conductive material of 0.01 wt% or more and 20 wt% or less when the opening of the sound hole surface has an opening width of 0.5 mm or less. It is desirable to make it.

The sound hole surface may have a streamlined shape with a rounded tip, and the opening width may be an opening width when viewed from a direction perpendicular to the surface where the opening expands. Alternatively, the sound hole surface may have a streamline shape with a rounded tip, and the opening width may be a front projection opening width.

The hemisphere having an oval shape that encloses a holder containing a microphone, and the hemisphere opposite to the sound hole surface may be streamlined.

According to the present invention, not only a dustproof and waterproof effect but also a windproof effect can be imparted to the resin microphone cover. Therefore, even under an environment where the wind blows, a wind noise can be suppressed and a good sound collection can be achieved without the need for a sponge cover or a cloth cover. Moreover, since it is resinous, there is no worry of water absorption even in rainy environments, and sound waves in a high frequency region can be collected well. Furthermore, since dustproof, waterproof, and windproof can be achieved with only the microphone cover, the cost is reduced.

It is an external view of the sound collection device which concerns on 1st Embodiment. It is an internal perspective view of the sound collection device which concerns on 1st Embodiment. It is sectional drawing of the sound collection device which concerns on 1st this embodiment. It is a graph which shows the pressure loss rate with respect to the wind pressure of various covers. It is an external view which shows the modification of the microphone cover which concerns on 1st Embodiment. It is an external view of the sound collection device which concerns on 2nd Embodiment. It is an external view of the sound collection device which concerns on 3rd Embodiment.

(First embodiment)
The sound collection device according to the first embodiment will be described below. The sound collection device 1 shown in FIGS. 1 to 3 is configured by accommodating a microphone 11 in a holder 6 and covering the microphone cover 2 from above. The head of the microphone cover 2 is provided with a sound hole surface 3 in which a large number of apertures 4 are formed. A signal line extending from the microphone 11 is led out from the holder 6.

The microphone 11 is a sound collection element that converts sound wave vibration into an electric signal and outputs it to a signal line. The microphone 11 is composed of components such as a coil, a diaphragm, a fixed electrode, a diaphragm, and a capacitor, and the components are covered with a conductive material such as metal or are accommodated in a container made of a conductive material such as metal. . The microphone 11 has, for example, a cylindrical shape as a whole, and a plurality of holes are formed in the surface on the diaphragm or diaphragm side. A surface having a hole on the diaphragm or diaphragm side is called a sound receiving surface 12.

Any of various types of microphones 11 can be applied. For example, a dynamic microphone, a condenser microphone, or the like is applicable. A dynamic microphone uses electromagnetic induction of a coil. The vibration caused by the sound wave strikes the diaphragm and the coil swings, and current flows by electromagnetic induction. The vibration change becomes a current change and is collected as an electric signal. The condenser microphone forms a capacitor between the fixed electrode and the diaphragm, and converts a change in the capacitance of the capacitor caused by the sound pressure generated by the sound wave to vibrate the diaphragm as an electrical signal to collect sound.

The microphone 11 is fitted in the rubber holder 13. The rubber holder 13 is a ring body and has the same inner diameter as the outer diameter of the microphone 11. Four protrusions are formed on the outer periphery of the rubber holder 13 at equal circumferential positions. The height of the rubber holder 13 is lower than that of the microphone 11. The rubber holder 13 is fitted to the microphone 11 so that the entire outer peripheral surface of the microphone 11 and the entire inner peripheral surface of the rubber holder 13 are in close contact with each other and are flush with the sound receiving surface 12 of the microphone 11.

The holder 6 has a shape according to the microphone 11. When the microphone 11 has a cylindrical shape, the holder 6 has a cup shape with one end having a bottom and the other end being open. In the middle of the inner cylindrical wall surface of the holder 6, a two-stage upper step portion 7 and a lower step portion 8 bulging in the radial direction of the cylindrical holder 6 are formed over the entire circumference.

The inner diameter of the holder 6 in the upper stage portion 7 is larger than the outer diameter of the microphone 11 and is the same as the diameter up to the protruding portion of the rubber holder 13. The width of the upper step portion 7 in the radial direction is the same as the thickness of the protruding portion of the rubber holder 13. The step between the upper step portion 7 and the lower step portion 8 corresponds to the difference in height between the rubber holder 13 and the microphone 11. The lower step portion 8 bulges in the center direction until the diameter of the space surrounded by the lower step portion 8 becomes smaller than the diameter of the microphone 11. A lead-out port 9 through which a signal line is led out is provided in a side wall near the bottomed portion of the holder 6.

The microphone cover 2 has a cup shape with one end having a bottom and the other end opened, and a sound hole surface 3 is provided on the bottomed surface. The inner diameter of the microphone cover 2 is the same as the outer diameter at the opening of the holder 6. The waistline of the microphone cover 2 and the sound hole surface 3 may be integrally formed, or the waistline and the sound hole surface 3 may be formed separately, and the sound hole surface 3 may be fitted into one inner edge of the waistline.

The sound hole surface 3 has a disk shape, and a large number of apertures 4 are formed through the plate. The opening width of the opening 4 is formed to be within 0.01 mm and less than 0.8 mm. Desirably, the opening width of the opening 4 is 0.01 mm or more and 0.5 mm or less, and more desirably 0.01 mm or more and 0.3 mm or less. The partition 5 between the apertures 4 is formed to fit within a wire diameter of 0.3 mm or less, preferably 0.1 mm or less.

When the sound hole surface 3 is mesh-shaped, the opening width is an aperture A (mm) = (25.4 / M) −d. In the formula, 25.4 is 1 inch in mm, M is a mesh (number of meshes), and d is a wire diameter (mm). When the opening 4 is closer to a circle than a rectangle, the diameter is the maximum. If the opening width varies, an average value may be used.

In such a sound collecting device 1, the microphone 11 is fitted into the lower part 8 of the holder 6. The protruding portion of the rubber holder 13 is hooked on the upper step portion 7 and the side surface is fitted into the inner wall surface of the holder 6. The microphone 11 is placed with the sound receiving surface 12 facing the opening of the holder 6.

Furthermore, the microphone cover 2 faces the opening of the holder 6 so that the sound hole surface 3 faces the head of the sound collecting device 1 and covers the microphone 11 accommodated in the holder 6. Fit into the opening. The contact surface between the microphone cover 2 and the holder 6 is welded.

Here, the holder 6 is made of metal or a mixed material obtained by mixing a conductive material with a resin such as polypropylene as a main material. The conductive material is a carbon material such as a carbon nanotube. The holder 6 is made of metal, or the holder 6 is made of a mixed material in which a conductive material is mixed with resin as a main material, thereby imparting conductivity to the holder 6 and grounding the microphone 11 in contact with the lower step portion 8. To do.

The sound hole surface 3 is formed of a mixed material in which conductive materials are mixed in a mixing ratio of 0.01 wt% or more and 20 wt% or less using a resin such as polypropylene as a main material. The conductive material is a carbon material such as a carbon nanotube. First, the mixing of the conductive material imparts conductivity to the sound hole surface 3, increases the volume of the conductive material surrounding the microphone 11, and facilitates grounding of the microphone 11.

However, in the case of simply imparting conductivity to the sound hole surface 3, the mixing ratio of the conductive material may be determined in consideration of the balance between cost and conductivity, but the mixing ratio of the conductive material to the sound hole surface 3 is further increased. A range of opening width allowed for manufacturing is set in the opening 4. That is, the present inventors have found that the opening width of the opening 4 can be reduced depending on the mixing ratio of the conductive material in order to create the microphone cover 2 for windproof use. Based on this knowledge, the present inventors provide the sound hole surface 3 with an opening 4 for the microphone cover 2 that allows sound waves to pass therethrough and suppresses intrusion of wind.

Specifically, the sound hole surface 3 is molded by pouring a mixed material in which a resin and a conductive material are mixed into a mold. When the mixture ratio of the conductive material is over 20 wt% and the formation of the opening 4 having an opening width of 0.5 mm or less is attempted, or the formation of the partition 5 having a wire diameter of 0.3 mm or less is attempted simultaneously, the mixed material And the opening 4 is easily broken at the time of mold release.

On the other hand, when the mixing ratio of the conductive material is set to less than 0.01 wt% and an attempt is made to form the opening 4 having an opening width of 0.5 mm or less, or the formation of the partition 5 having a wire diameter of 0.3 mm or less is attempted simultaneously. In addition, due to insufficient viscosity of the mixed material, the opening width of the opening 4 varies due to the collapse of the opening 4 or the connection between adjacent openings 4.

If the mixing ratio of the conductive material is 0.01 wt% or more and 20 wt% or less, an opening width of at least 0.5 mm or less can be achieved by the appropriate viscosity of the mixed material, and the opening width can be reduced to about 0.01 mm. . Moreover, the wire diameter of the partition 5 can achieve 0.3 mm or less, and can be made small to about 0.01 mm.

As with the holder 6, the periphery of the microphone cover 2 is formed of a mixed material in which a conductive material is mixed with a resin such as polypropylene as a main material. The mixing of the conductive material is for imparting conductivity to the microphone cover 2 to increase the volume of the conductive material surrounding the microphone 11 so that the microphone 11 can be easily grounded. However, in the case of integral molding with the sound hole surface 3, it is formed of the same composition as the sound hole surface 3.

FIG. 4 shows the wind pressure loss rate due to the sound hole surface 3 in the sound collecting device 1. The wind pressure loss rate is calculated by {(1/2) ρV1 ^2- (1/2) ρV0 ² } / {(1/2) ρV0 ² }. In the equation, ρ is the air density, V0 is the wind speed before passing through the sound hole surface 3, and V1 is the wind speed after passing through the sound hole surface 3. The wind pressure loss rate was measured from 20 μPa to 20 Pa, which is the audible range of sound pressure, exceeding the upper limit of 20 Pa of the audible range.

The measurement object is a microphone cover 2 including a sound hole surface 3 in which an opening 4 having an opening width of 0.3 mm is divided by a partition 5 having a wire diameter of 0.3 mm, and an opening 4 having an opening width of 0.5 mm is set to have a wire diameter of 0. A microphone cover 2 having a sound hole surface 3 partitioned by a 3 mm partition 5 and a conventional microphone cover having a sound hole surface 3 in which an opening 4 having an opening width of 0.8 mm is partitioned by a partition 5 having a wire diameter of 0.3 mm. And a porous sponge cover of polyurethane. Ideally, the wind pressure loss rate should be 100% for wind pressures exceeding the audible sound pressure.

As shown in FIG. 4, in the porous sponge cover, the maximum wind pressure loss rate in the audible sound pressure range is about 16 Pa and reaches 88%. However, the wind pressure loss rate decreased at a wind pressure higher than 16 Pa, and the wind pressure loss rate decreased to 78% at a wind pressure of 32 Pa or higher exceeding the wind speed of 7 m / s. The wind pressure of 32 Pa corresponds to a case where the vehicle travels at a speed of 25 km / h in a windless environment. That is, even if the sound collecting device 1 is provided with the porous sponge cover, it can be seen that the wind noise cannot be sufficiently suppressed under windy weather or high-speed traveling environment.

The conventional microphone cover with an opening width of 0.8 mm achieves the maximum wind pressure loss rate near 6 Pa in the audible sound pressure range, but still the wind pressure loss rate reaches only 80%. When the wind pressure is around 16 Pa, the wind pressure loss rate is reduced to 75%. Moreover, the degree of decrease further increases after the vicinity of 32 Pa exceeding the audible sound pressure range. In other words, the conventional microphone cover having an opening width of 0.8 mm or more cannot fulfill the windshield function and cannot suppress the wind noise at all against the pressure fluctuation of the air exceeding the audible sound pressure range. It can be seen that even wind ingress due to wind pressure cannot be suppressed and wind noise is generated.

On the other hand, the microphone cover 2 having an opening width of 0.5 mm approximates the wind pressure loss rate of the porous sponge cover in the audible region up to 20 Pa, and exhibits the same performance as the porous sponge cover in the audible region. I understand that Furthermore, the porous sponge cover reduces the wind pressure loss rate at wind pressures greater than 16 Pa, whereas the microphone cover 2 having an opening width of 0.5 mm increases the wind pressure loss rate as the wind pressure increases. I am letting. That is, it can be seen that the microphone cover 2 having an opening width of 0.5 mm exhibits a windproof effect that surpasses a porous sponge cover for windproof use.

Furthermore, the microphone cover 2 having an opening width of 0.3 mm exceeds the wind pressure loss rate of the porous sponge cover in the entire measurement region, and the wind pressure loss rate is the lowest even when the wind pressure exceeds the audible range of more than 20 Pa. 90% is maintained. Moreover, the wind pressure loss rate is increased as the wind pressure increases. A pressure loss rate of over 93% is achieved for a wind pressure of 32 Pa, and a pressure loss rate of over 95% is achieved for a wind pressure of 42 Pa.

In other words, the microphone cover 2 having the sound hole surface 3 in which the opening 4 having an opening width of 0.3 mm is formed can also be used even if the microphone cover 2 surpasses the porous sponge cover and receives wind pressure exceeding the audible sound pressure range. It can be seen that the air is well prevented from entering the inside. That is, it can be seen that the microphone cover 2 has not only dust resistance and waterproofness but also wind resistance exceeding that of the porous sponge cover, and particularly good wind resistance against wind pressure exceeding the audible sound pressure range.

It should be noted that as a provision for preparatory or even larger air pressure fluctuations, and also for the provision of fine rainwater, the sound collection device 1 can be provided with slits 10 to allow wind and rainwater that has entered the interior to escape to the outside. If the rubber holder 13 is provided with a protrusion and the space between them is made hollow, the accommodation space of the microphone 11 becomes large, an increase in internal pressure is suppressed, and a further windproof effect is brought about.

It is possible to further improve the waterproof effect by arranging a waterproof film or porous sponge in the holder 6. A spacer is disposed on the edge of the sound receiving surface 12 of the microphone 11, and a waterproof film and a porous sponge are stacked on the spacer in this order.

The spacer has a donut shape and does not block the sound receiving surface 12 of the microphone 11. The spacer forms a gap between the waterproof membrane and the sound receiving surface 12 of the microphone 11 so that the vibration of the waterproof membrane caused by water droplets that reach the microphone 11 is not directly transmitted to the microphone 11.

The porous sponge is a windshield against wind that could not be blocked by the microphone cover 2, and prevents water droplets such as rainwater that has entered from the opening 4 of the sound hole surface 3 from reaching the lower microphone 11. . The waterproof membrane further prevents water droplets that could not be removed by the sound hole surface 3 and the porous sponge from reaching the microphone 11. For this waterproof film, for example, a breathable polymer film is used.

As described above, the sound collection device 1 includes the microphone cover 2 for windproof use that suppresses pressure fluctuation due to wind inside the cover while allowing sound waves to pass therethrough. The microphone cover 2 has a sound hole in the head. The sound hole surface 3 is made of a mixed material obtained by mixing a conductive material with resin as a main material, and has a plurality of openings 4 having an opening width of 0.01 mm or more and less than 0.8 mm.

Thus, not only a dustproof and waterproof effect but also a windproof effect is imparted to the resin microphone cover 2. Therefore, even under an environment where the wind blows, a wind noise can be suppressed and a good sound collection can be achieved without the need for a sponge cover or a cloth cover. Moreover, since it is resinous, there is no worry of water absorption even in rainy environments, and sound waves in a high frequency region can be collected well. Furthermore, since only the microphone cover 2 exhibits the dustproof, waterproof, and windproof effects, the cost is reduced.

The sound hole surface 3 is formed from a mixed material containing resin as a main material and containing 0.01 wt% or more and 20 wt% or less of a conductive material. Thereby, even if it is the opening width of 0.01 mm or more and 0.5 mm or less in the sound hole surface 3, the opening 4 can be formed and the windproof function can be provided to the microphone cover 2. FIG. In particular, by forming the opening 4 having an opening width of 0.5 mm or less in the sound hole surface 3, the windproof effect of the microphone cover 2 is dramatically increased, and the pressure fluctuation of the air exceeding the audible sound pressure range is satisfactorily suppressed. Therefore, it is possible to pick up sound even in a strong wind environment, and it can be mounted outside a moving body that travels at high speed.

Furthermore, by forming the opening 4 having an opening width of 0.3 mm or less in the sound hole surface 3, the windproof effect of the microphone cover 2 surpasses the porous sponge cover for windproof use in all wind pressure regions, Sound can be collected without the need for a porous sponge cover in any environment.

In addition, by providing conductivity to the holder 6 and the microphone cover 2, a conductive material having a large volume comes into contact with the microphone 11, and grounding treatment can be performed while eliminating the need for separately laying a ground wire or installing a metal plate. Applied. As a result of measuring the resistance between the microphone 11 and the holder 6, when the conductive material is mixed with the composition of the holder 6 and the conductive material is mixed with the composition of the microphone cover 2, the resistivity is 4.7 × 10 6. It was ⁻⁶ Ω · cm.

For this reason, since the number of parts constituting the sound collection device 1 can be reduced, it is possible to reduce the size of the sound collection device 1 by omitting the production process, reducing the production cost, and simplifying the structure. Furthermore, since the sound collecting device 1 is entirely covered by the microphone cover 2 and the holder 6, electrical noise due to external electromagnetic waves can be reduced, so that high-quality sound can be collected.

(Modification)
In the sound collecting device 1 according to the first embodiment, the sound hole surface 3 may be formed on the entire head portion of the cup-shaped microphone cover 2, but as shown in FIG. It can also be formed. Combined with the suppression of the wind intrusion into the cover by forming the opening 4 having an opening width of 0.01 mm or more and less than 0.8 mm, further suppression of the wind intrusion by limiting the wind intrusion area is achieved. be able to.

(Second Embodiment)
FIG. 6 is an external view showing a sound collecting device 1 according to the second embodiment. The microphone cover 2 of the sound collecting device 1 according to the second embodiment has a streamline shape with a rounded tip, and the sound hole surface 3 is formed in the streamlined portion. That is, the microphone cover 2 has a semi-elliptical sphere such as a rugby ball, an egg shape, or a bullet shape, and an opening 4 is formed in the whole.

In the microphone cover 2, an opening 4 having an opening width of 0.01 mm or more and less than 0.8 mm viewed from a direction perpendicular to a surface where the opening 4 expands (hereinafter referred to as an opening surface) may be formed. The opening 4 may be formed so that the front projection opening width is less than 0.8 mm. The front projection opening width is the width of the opening 4 when viewed from the head side along the long axis of the microphone cover 2. When forming the opening 4 having an opening width of 0.01 mm or more and 0.5 mm or less as viewed from the direction perpendicular to the opening surface, the conductive material is mixed at a mixing ratio of 0.01 wt% or more and 20 wt% or less. Mix.

When the opening 4 having an opening width of 0.01 mm or more and less than 0.8 mm as viewed from the direction perpendicular to the opening surface is formed, the front projection opening width is further smaller than the numerical range. For example, when the aperture surface is inclined by 30 degrees with respect to the major axis of the microphone cover 2, if the aperture width viewed from the direction perpendicular to the aperture surface is 0.6 mm, the front projection aperture width Is 0.3 mm. Further, when the aperture surface is inclined by 30 degrees with respect to the axis of the microphone cover 2, when the aperture width viewed from the direction perpendicular to the aperture surface is 0.01 mm, the front projection aperture width is 0.005 mm.

Further, when the opening 4 is formed so that the front projection opening width is less than 0.8 mm, the opening width viewed from the direction perpendicular to the opening surface can be formed with a numerical value larger than less than 0.8 mm. For example, when the aperture surface is inclined by 45 degrees with respect to the axis of the microphone cover 2, in order to make the front projection aperture width less than 0.8 mm, the aperture width viewed from the direction perpendicular to the aperture surface is It may be less than about 1.13 mm.

The microphone cover 2 provided in such a sound collecting device 1 has a streamlined shape with a rounded tip, so that wind can be received, the resistance value against wind is reduced aerodynamically, and the wind covers the microphone cover 2. It becomes difficult to go through.

Furthermore, when the opening 4 having an opening width of 0.01 mm or more and less than 0.8 mm as viewed from the direction perpendicular to the opening surface is formed, the front projection opening width is further reduced, and the windproof effect can be further improved. Alternatively, even if the opening width viewed from the direction perpendicular to the aperture surface is 0.8 mm or more, the front projection opening width can be suppressed to less than 0.8 mm, and the yield is improved by facilitating the manufacture of the microphone cover 2. It is also possible to direct the mixing ratio of the conductive materials in a direction in which importance is placed on grounding the microphone 11 and blocking external electromagnetic waves to the microphone 11, and it is possible to reduce costs by reducing the conductive material.

(Modification)
In the sound collection device 1 according to the second embodiment, all the openings 4 formed in the sound hole surface 3 may have the same opening width, but may be changed to an opening width corresponding to the formation position. For example, the opening 4 in the vicinity of the streamlined tip has a small difference between the opening width viewed from the direction perpendicular to the opening surface and the front projection opening width. Maintains a front projected aperture width of 0.5 mm or less, more preferably 0.3 mm or less.

On the other hand, the opening 4 in the vicinity of the streamlined skirt has a large difference between the opening width seen from the direction perpendicular to the opening surface and the front projected opening width, so that a larger opening 4 is formed and less than 0.8 mm, desirably Maintains a front projected aperture width of 0.5 mm or less, more preferably less than 0.3 mm. Alternatively, the opening 4 is not formed near the streamline tip. Thereby, the yield can be improved by facilitating the manufacture of the microphone cover 2.

(Third embodiment)
FIG. 7 is an external view of the sound collection device 1 according to the third embodiment. The microphone cover 2 includes a holder 6 that houses the microphone 11. The shape has an elliptical sphere such as a rugby ball or an egg shape. For example, after separately molding at the position of the maximum diameter, the openings are joined together after accommodating the holder. The sound hole surface 3 is formed on the hemispherical side toward which the sound receiving surface 12 of the microphone 11 faces. The other hemisphere can also be used in which the opening 4 is formed from the viewpoint of sharing parts.

The microphone cover 2 has a narrow tip with respect to the flow of the wind, and gradually becomes thicker as it goes in the downstream direction, and gradually becomes thinner as it goes from the middle to the further downstream direction. In the microphone cover 2, separation of the fluid from the device hardly occurs from the middle to the downstream side of the sound collection device 1. Therefore, an increase in the air resistance of the sound collecting device 1 due to the separated flow is prevented, and the sound collecting device 1 can easily receive the wind, and wind noise can be further reduced.

(Other embodiments)
In the present specification, a plurality of embodiments according to the present invention have been described. However, these embodiments are presented as examples and are not intended to limit the scope of the invention. Specifically, the first to third embodiments and combinations of all or any of the modifications are also included. The above embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof as well as included in the scope and gist of the invention.

DESCRIPTION OF SYMBOLS 1 Sound collecting device 2 Microphone cover 3 Sound hole surface 4 Opening hole 5 Partition 6 Holder 7 Upper stage part 8 Lower stage part 9 Outlet 10 Slit 11 Microphone 12 Sound receiving surface 13 Rubber holder

Claims

A microphone cover that suppresses the entry of wind into the cover while allowing sound waves to pass through,
It is composed of a mixed material obtained by mixing a conductive material with a resin as a main material, and includes a sound hole surface having a plurality of openings having an opening width of 0.01 mm or more and less than 0.8 mm,
A microphone cover characterized by.
The opening of the sound hole surface has an opening width of 0.01 mm or more and 0.5 mm or less;
The microphone cover according to claim 1.
The opening of the sound hole surface has an opening width of 0.01 mm or more and 0.3 mm or less;
The microphone cover according to claim 1.
The sound hole surface is made of a mixed material containing a resin as a main material and a conductive material in an amount of 0.01 wt% to 20 wt%.
The microphone cover according to any one of claims 1 to 3.
The sound hole surface has a streamlined shape with a rounded tip.
The opening width is an opening width when viewed from a direction perpendicular to a surface where the opening expands;
The microphone cover according to any one of claims 1 to 4.
The sound hole surface has a streamlined shape with a rounded tip.
The opening width is a front projection opening width;
The microphone cover according to any one of claims 1 to 4.
It has an oval shape that encloses a holder containing a microphone,
The hemisphere opposite to the sound hole surface is also streamlined,
The microphone cover according to claim 5 or 6.
A microphone,
A holder for accommodating the microphone;
A microphone cover that engages with the holder and suppresses the ingress of wind into the cover while allowing sound waves to pass through;
With
The microphone cover is
It is composed of a mixed material obtained by mixing a conductive material with a resin as a main material, and includes a sound hole surface having a plurality of openings having an opening width of 0.01 mm or more and less than 0.8 mm,
A sound collecting device.
The opening of the sound hole surface has an opening width of 0.01 mm or more and 0.5 mm or less;
The sound collecting device according to claim 8.
The opening of the sound hole surface has an opening width of 0.01 mm or more and 0.3 mm or less;
The sound collecting device according to claim 8.
The sound hole surface is made of a mixed material containing a resin as a main material and a conductive material in an amount of 0.01 wt% to 20 wt%.
The sound collecting device according to claim 8, wherein:
The sound hole surface has a streamlined shape with a rounded tip.
The opening width is an opening width when viewed from a direction perpendicular to a surface where the opening expands;
The sound collecting device according to claim 8, wherein
The sound hole surface has a streamlined shape with a rounded tip.
The opening width is a front projection opening width;
The sound collecting device according to claim 8, wherein
Including a holder containing the microphone, and having a streamlined shape on the side opposite to the sound hole surface;
The sound collecting device according to claim 12 or 13,