JP2014171108A - Sound collection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound collection device for satisfying both requests, i.e. the reduction of the influence of reflection sound from the front surface of a desk and the attainment of strength improvement, flat frequency characteristics, and directivity.SOLUTION: A circuit board 6 is supported above a base 4 in parallel. Directional microphones 2 are attached to the outer peripheral part of the base 4 so as to be arranged within the range of a height between the base 4 and the circuit board 6. A cover member 5 is disposed to cover the directional microphones 2 and the circuit board 6 with the base 4. Sidewall parts 11 made of a rigid member are arranged along the base 4 concerning the cover member 5. Open holes 15 opening behind sound collection surfaces 2a of the directional microphones 2 are formed in the sidewall parts 11 to be positioned lower than at least the circuit board 6.

Description

  The present invention relates to a sound collection device that houses a microphone in a housing and collects sound in a space around the housing.

In a telephone conference system or the like, a sound collecting device in which a microphone is housed in a housing is placed on a table so as to collect sound in a space around the housing.
As this type of sound collecting device, there are devices described in Patent Document 1 and Patent Document 2.
The sound collecting device described in Patent Document 1 includes a directional microphone disposed so that a sound collecting surface is substantially vertical on a base, and a circuit board disposed behind the microphone. It is covered with a member. The cover member is constituted by a punching plate having a large number of holes, and the central portion thereof is fixed to the upper end of the support boss on the base with screws.
Also in the sound collecting device described in Patent Document 2, a microphone mounted on a circuit board is attached on a base, and these are covered with a cover member. As the cover member, a punching plate or a metal net is used, and the center portion is fixed to the upper end of the boss on the base with a screw, as in the case of Patent Document 1.
In addition, a configuration in which a cover member that covers a circuit board and a microphone is formed of a resin or a metal plate and a hole is formed in the vicinity of the microphone is also known.

Utility Model Registration No. 2515812 JP-A-2005-333180

By the way, a sound collecting device used on a table needs to be designed to avoid deterioration in sound quality due to reflected sound from the surface of the desk. In the sound collection devices described in both patent documents, it is considered that the microphone is arranged near the center of the device, so that the reflected sound from the surface of the desk is difficult to reach. This increases the area and impairs downsizing.
In this case, it becomes particularly remarkable when the circuit board and the microphone are arranged side by side as described in Patent Document 1. If the microphone is arranged on the circuit board as described in Patent Document 2, it is considered that the space efficiency is improved. However, since the microphone position is increased, the reflection from the surface of the desk is easily collected. It is necessary to further widen the size, and downsizing is difficult.

On the other hand, when used on a desktop, mechanical strength against dropping or impact is also required, but simply covering the whole with a punching plate as described in both patent documents is weak in strength against dropping and impact and is likely to be deformed. In order to increase the strength, it is conceivable to use a plurality of punching plates in piles, but this causes an increase in cost.
On the other hand, when the cover member is formed of resin or the like, the wall can be made rigid to obtain a high strength, but the peak and dip occur in the frequency characteristics of the microphone due to sound reflection. In particular, a unidirectional microphone picks up a reflected sound from an obstacle around the microphone sensitively and easily causes a peak dip. In addition, directivity is also impaired.

  The present invention has been made in view of such circumstances, and is capable of reducing sound quality deterioration due to reflected sound from a desk, and satisfying the requirements of both improvement in strength, flat frequency characteristics, and directivity. An object is to provide an apparatus.

  In the sound pickup device of the present invention, the circuit board is supported in parallel on the base, and is arranged on the outer periphery of the base within the range of the height between the base and the circuit board. A directional microphone is attached, and a cover member that covers the directional microphone and the circuit board between the base and the base is provided, and the cover member has a side wall portion formed of a rigid member along the outer peripheral portion of the base. An open hole is formed at a position below the circuit board at least in the side wall portion, and an opening is formed on the rear side of the sound collecting surface of the directional microphone.

Since the microphone is placed between the base and the circuit board, the installation height of the microphone can be lowered, so that even if the microphone is installed on the outer periphery of the base, direct sound and reflected sound from the surface of the desk No phase difference occurs and the sound quality is not deteriorated. Therefore, the area of the base can be reduced and the size can be reduced.
On the other hand, since the microphone is arranged between the base and the circuit board, the space between the base and the circuit board is covered by the cover member behind the microphone, and when this becomes a box-shaped closed space, Sound may be reflected inside the cover member, and the reflected sound may be picked up by a microphone or resonance at a specific frequency may occur, which may degrade sound collection characteristics. Since the sound collecting device of the present invention is provided with the opening hole opened on the rear side of the sound collecting surface of the microphone in the side wall portion of the cover member, the reflected sound on the rear side of the microphone can be reduced. In particular, since the microphone is provided within the range of the height between the base and the circuit board, it is easy for the sound to resonate between the base and the circuit board. The situation is equivalent to the situation where the periphery of the microphone is open, and the sound collection characteristics can be prevented from deteriorating.
Further, since the side wall portion of the cover member is formed of a rigid member and the opening is formed, the strength as the cover member can be secured, and deformation due to external force such as dropping or impact can be prevented. .

In the sound collecting device according to the aspect of the invention, it is preferable that a plurality of the opening holes are formed and arranged at positions that are asymmetric with respect to the directional microphone.
The peak or dip of the sound collection frequency characteristic of the microphone that is generated when the reflection component from the side wall portion is in phase with the microphone can be suppressed, and deterioration of the sound collection characteristic of the microphone can be prevented.

In the sound collecting device of the present invention, it is preferable that a plurality of the opening holes are formed and arranged at a position that is non-rotational symmetric with respect to the center of the base.
Resonance due to reflection by the wall surface arranged together with each open hole is suppressed, and a peak or dip is less likely to occur in the sound collection frequency characteristic of the microphone.

In the sound collecting device of the present invention, it is preferable that a plurality of the opening holes are formed, and that the width dimension along the length direction of the side wall portion in each opening hole is different.
Since the reflection frequency characteristics of the side wall determined by the open hole and the wall surface are different, resonance at a specific frequency can be suppressed, and a peak or a dip hardly occurs in the sound collection frequency characteristic of the microphone.

In the sound collecting device of the present invention, a sound absorbing material may be disposed between the base and the circuit board behind the directional microphone.
Since the sound that circulates behind the directional microphone is absorbed by the sound absorbing material, it is possible to reduce the generation of reflected sound.

  According to the sound collecting device of the present invention, since the microphone installation height is low and it is difficult to be affected by the reflected sound from the surface of the desk, the base can be made small and downsizing can be achieved. An open hole that opens at the rear side of the sound collection surface is formed at least below the circuit board on the side wall of the cover member that covers the microphone, so that the reflected sound behind the microphone can be reduced. Thus, it is possible to eliminate the peak dip and provide a sound collecting device having flat frequency characteristics and directivity. In addition, since the side wall portion of the cover member is formed of a rigid member, deformation due to dropping or impact can be prevented.

It is a perspective view which shows the sound collection device of 1st Embodiment of this invention. It is a front view of the state which opened one of the sound collection holes in the sound collection device of FIG. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. It is a front view similar to FIG. 2 which shows the sound collection device of 2nd Embodiment of this invention. FIG. 5 is a cross-sectional view taken along line B-B in FIG. 4.

Embodiments of the present invention will be described below with reference to the drawings.
1 to 3 show the sound collection device of the first embodiment. The sound collection device 1 includes three unidirectional microphones (hereinafter simply referred to as microphones) 2, and a case 3 formed in an equilateral triangle as a whole in plan view has a triangular apex portion. The microphones 2 are arranged one by one, and each microphone 2 can collect sound in three different directions with an interval of 120 °.
The housing 3 includes a flat base 4 and a cover member 5 attached so as to be placed on the base 4.
The base 4 is formed by chamfering the apexes of triangles, and the microphones 2 are attached to the apexes, and the circuit board 6 connected to the microphones 2 is at a central position surrounded by the three microphones 2. It is fixed.

The microphone 2 is formed in a cylindrical block-shaped outer shape, and one end surface thereof is a sound collection surface 2a. Between the pair of spring members 7 fixed on the base 4, the sound collection surface 2 a is attached detachably so as to face outward from the apex of the triangle and away from the upper surface of the base 4. .
The circuit board 6 is provided in parallel with the surface of the base 4 and is mounted with an impedance converter, a sound quality adjustment circuit, an output circuit (all not shown) and the like, and is fixed in a state of being electrically connected to the microphone 2. Has been. Further, since the base 4 and the circuit board 6 are provided in parallel, a space portion having a constant height is formed between them. The microphone 2 is installed within a height range between the base 4 and the circuit board 6.
In addition, a sound absorbing material 8 made of a porous resin such as urethane foam is provided in the space between the base 4 and the circuit board 6 so as to be disposed between the three microphones 2. This sound absorbing material 8 is for suppressing the influence of reflection of sound waves, which will be described later, and is formed in a slightly similar similar triangular shape in plan view with respect to the triangle having the installation position of each microphone 2 as the apex, Each of the apexes is arranged in a posture facing the microphone 2.

The cover member 5 is integrally formed with a side wall portion 11 and a canopy portion 12 that covers a space surrounded by the side wall portion. The cover member 5 has a planar shape in which a vertex of a triangle is cut as a whole. By being fixed, the sound collection hole 13 is opened by the cut portion. Each microphone 2 is disposed with the sound collection surface 2 a facing outward from the sound collection hole 13.
Further, in this cover member 5, the side wall portions 11 between the sound pickup holes 13 are formed perpendicular to the surface of the base 4, but a plurality of side walls are provided except for the side wall portions where the external connection portions 14 are provided. An open hole 15 is formed. These open holes 15 are formed in a range of height between the circuit board 6 and the base 4 in each side wall portion 11, and all of them are formed in a rectangular shape. The width dimension W along the direction is different for each open hole 15.

Moreover, these open holes 15 are not only formed in mutually different width dimensions W in the side wall part 11 to which they belong, but also different between the side wall parts 11 arranged on each side of the triangle. The width W is formed. Further, the positions of the open holes 15 are also differently arranged, and when the perpendicular from the apex of the triangle is the center line X (see FIG. 3), the side walls 11 on both sides are asymmetrical. In addition, the open holes 15 are arranged so as to be non-rotationally symmetric in each side wall portion 11 when the triangular figure center P is the center.
The cover member 5 is made of a highly rigid material such as a synthetic resin such as polycarbonate resin or ABS resin, or a metal plate.

  And the exterior members 16 and 17 which consist of a punching plate which has many holes are provided so that the three sound collection holes 13 of the cover member 5 and each open hole 15 of the side wall part 11 may be covered. Among these exterior members, the exterior member 16 that covers the sound collection holes 13 is formed by press working, and includes an upper plate portion 16a that extends so as to extend the canopy portion 12 from the notch portion 5a of the cover member 5, and a notch It is comprised from the raising part 16b standingly arranged from the peripheral part of the base 4 exposed to the part 5a. Further, the exterior member 17 that covers the open holes 15 in the side wall portion 11 of the cover member 5 is formed in a long strip shape that can cover all the open holes 15 of one side wall portion 11. It is attached to the outer surface of the.

The sound collecting device 1 configured as described above is placed at the center of a desk where the conference person gathers as a terminal of a telephone conference system or the like, and collects the sound emitted by the conference person. The microphone 2 has the sound collection surface 2a facing outward, and can accurately pick up the voices of the surrounding conference participants. In this case, since the microphone 2 is disposed below the circuit board 6, the installation height of the microphone 2 is lowered, and the reflected sound and direct sound from the surface of the desk on which the sound collecting device 1 is placed are reduced. And the phase difference is less likely to occur. Therefore, the frequency at which a peak or dip occurs in the sound collection frequency characteristic of the microphone due to reflection from the desk surface increases, and the microphone 2 can be installed on the outer periphery of the base 4, thereby reducing the area of the base 4. Therefore, the size can be reduced.
On the other hand, the sound wave incident from the sound collection hole 13 passes through the space around the microphone 2 and enters the housing 3 behind the sound collection surface 2 a of the microphone 2.
When this sound wave enters behind the sound collection surface 2 a of the microphone 2, it reaches the inner surface of the side wall portion 11 of the cover member 5 in the housing 3, but a plurality of open holes 15 are formed in the side wall portion 11. Therefore, most of the sound waves are diffused from the open hole 15 to the outside of the housing 3 and are reflected from the inner surface of the side wall portion 11. Moreover, even if some reflection occurs in the bridge portion of the side wall portion 11 remaining between the open holes 15, since the open holes 15 are formed in the other side wall portions 11, most of them are repeatedly subjected to irregular reflection. Sound waves that are emitted to the outside from any of the open holes 15 and reach the sound collection surface 2a of the microphone 2 from the inside of the housing 3 can be extremely reduced.

  In this case, since the open holes 15 are arranged asymmetrically (asymmetrically with respect to the center line X in FIG. 3) in the side wall portions 11 arranged on both sides around the single microphone 2, On the other hand, reflection components from the side wall portions 11 are prevented from being incident in the same phase and the influence on the microphone 2 is emphasized. Further, in each side wall portion 11, each open hole 15 is arranged so as to be rotationally asymmetric (rotationally asymmetric with respect to the center P in FIG. 3), so that resonance caused by each open hole 15 is incident in the same phase. Thus, the emphasis on the influence on the microphone 2 is suppressed. Further, since all the open holes 15 have different sizes, there is no common resonance frequency caused by these open holes 15.

  Moreover, the sound absorbing material 8 installed between the microphones 2 can absorb the sound wave incident in the housing 3, reduce the sound wave reaching the side wall 11, and reduce the reflected sound. Can do. In particular, when the formation of the opening hole 15 in the side wall portion 11 is restricted due to the installation of other devices or the like, the sound absorbing material 8 may be arranged to block between the side wall portion 11 and the microphone 2.

Due to the above synergistic action, the sound collecting device 1 is less susceptible to the reflected sound from the surface of the desk on which the sound collecting device 1 is placed and also reduces the reflected sound behind each microphone 2. It is possible to reduce the occurrence of peaks and dips on the frequency characteristics, and to have unidirectionality with flat frequency characteristics.
Since the sound collecting device 1 collects a human voice as a terminal of a telephone conference system or the like, the sound collecting device 1 targets a sound of about 10 kHz or less which is a frequency band of the human voice. If the entire width of the side wall 11 remaining by the open hole 15 is less than half of the wavelength, the influence of the reflection from the side wall 11 hardly occurs. If the entire width of the side wall 11 is 10 cm, the influence of reflection can be reduced if the width of the wall left by the open hole 15 is 2 cm or less, which is half the shortest wavelength (about 4 cm or less) of the frequency band. it can.

In addition, although the circuit board 6 is provided horizontally in the housing 3, the acoustic vibrations of the upper and lower spaces are different, but there is an open hole 15 in the lower space where the microphone 2 is disposed. The sound dissipation effect is higher.
The sound collection hole 13 and the opening hole 15 are both covered by the exterior member 17 but are the exterior member 17 made of a punching plate, and more than half of the area is opened by a large number of holes. It does n’t matter if you do n’t.
Furthermore, since the microphone 2 of the present embodiment is supported by the spring member 7 so as to be separated from the upper surface of the base 4, vibration from the base 4 is not easily transmitted, and the acoustic characteristics can be further improved.

By the way, this type of sound collection device 1 is used by being installed on a table in a conference call or the like, and even when an external force such as an impact is applied during handling or the like, the internal circuit board 6 or the microphone 2 is deformed due to deformation or the like. However, since the sound collecting device 1 is made of a synthetic resin such as polycarbonate resin or ABS resin or a highly rigid material such as a metal plate, the sound collecting device 1 is Deformation due to impact or the like can be prevented, and the strength can be significantly improved compared to a cover member made of a conventional punching plate.
In addition to dropping and impact, for example, an external force may be assumed by applying a load to the sound collecting device 1 when a conference participant stands up from a chair. However, even in that case, sufficient mechanical strength is assumed. Can be demonstrated.
Moreover, since the open hole 15 is formed below the circuit board 6, the bias stress at the time of impact is small, which is advantageous in terms of strength.

4 and 5 show a sound collecting apparatus according to the second embodiment of the present invention. In the first embodiment, the housing 3 is formed in a triangular shape in plan view. However, in the sound collecting device 21 in the second embodiment, the housing 22 is formed in a circular shape in plan view.
In the sound collecting device 21, the casing 22 includes a circular plate-like base 23 and a cover member 24 that covers the base 23, and the three sound collecting holes 13 are spaced from the cover member 24 by 120 °. Are formed, and the microphone 2 is attached to the sound collection holes 13. In this case, the circuit board 6 is fixed in parallel on the base 23, and the microphone 2 is installed in a height range between the base 23 and the circuit board 6. The cover member 24 is made of a high-rigidity material such as a synthetic resin such as polycarbonate resin or ABS resin, or a metal plate.

Further, a plurality of open holes 15 are formed in the side wall portion 25 of the cover member 24 except for the side wall portion where the connecting portion 14 to the outside is provided. These open holes 15 have different width dimensions W and are formed to have different width dimensions W between the side wall portions 25. Further, the positions of the open holes 15 are also differently arranged, and are arranged so as to be asymmetrical between the side wall portions 25 on both sides thereof with respect to the center line Y passing through the sound collecting holes 13, and the center Q of the circle Are arranged so as to be non-rotational symmetric.
In addition, the configuration of the first embodiment is the same as that of the first embodiment in that a sound-absorbing material 8 having a triangular planar shape with each microphone 2 as a vertex is provided between the circuit board 6 and the base 23.
The exterior member 26 such as a punching plate that covers the open hole 15 is formed in a shape that covers not only the side wall portion 25 of the cover member 24 but also the whole.

  Similarly to the first embodiment, the sound collecting device 21 can also reduce the influence of the reflected sound behind each microphone 2, eliminate peaks and dips in the sound collecting frequency characteristics of the microphone, and achieve a flat frequency. It can have characteristics and directivity. Further, since the cover member 24 is formed of a rigid member, it is possible to prevent deformation due to an external force such as dropping or impact.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
The number of microphones is not limited to three in the embodiment, and can be one, and can also be applied to four or more microphones, and the number is not limited.

DESCRIPTION OF SYMBOLS 1 ... Sound collection apparatus, 2 ... Microphone, 2a ... Sound collection surface, 3 ... Housing | casing, 4 ... Base, 5 ... Cover member, 5a ... Notch part, 6 ... Circuit board, 7 ... Spring member, 8 ... Sound absorption material, DESCRIPTION OF SYMBOLS 11 ... Side wall part, 12 ... Canopy part, 13 ... Sound collection hole, 14 ... Connection part, 15 ... Opening hole, 16 ... Exterior member, 17 ... Exterior member, 21 ... Sound collection device, 22 ... Housing, 23 ... Base 24 ... Cover member, 25 ... Side wall, 26 ... Exterior member

Claims (5)

  A circuit board is supported in parallel on the base, and a directional microphone is attached to the outer periphery of the base so as to be disposed within a height range between the base and the circuit board. A cover member for covering the directional microphone and the circuit board with the base is provided, and the cover member is provided with a side wall portion formed of a rigid member along an outer peripheral portion of the base, The sound collecting device, wherein an opening hole is formed at least at a position lower than the circuit board and opens on the rear side of the sound collecting surface of the directional microphone.   The sound collecting device according to claim 1, wherein a plurality of the open holes are formed and are disposed at positions that are asymmetric with respect to the directional microphone.   The sound collecting device according to claim 1, wherein a plurality of the open holes are formed and are arranged at positions that are non-rotationally symmetric with respect to a center of the base.   The sound pickup according to any one of claims 1 to 3, wherein a plurality of the open holes are formed, and width dimensions along the length direction of the side wall portions in the open holes are different from each other. apparatus.   The sound collecting device according to any one of claims 1 to 4, wherein a sound absorbing material is disposed between the base and the circuit board at the rear of the directional microphone.

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