JP2009272893A - Sound pickup apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound pickup apparatus having a microphone which forms directivity using phase difference of voice made incident in front and rear of a diaphragm, and whose casing is made thin with refined design without deteriorating the directivity. <P>SOLUTION: A holding member 4 for holding a plurality of microphones 2 (2A-2C) is installed inside the casing 10 of a sound emitting/pickup apparatus 1. The holding member 4 is provided with a storage part 42 which stores the microphones 2 at its center and is provided with storage parts 41, 43 which store a speaker SP on both sides. A bucket-like recessed part 5 is installed approximately at the center of the bottom part 421 in the storage part 42. The microphones 2 are installed so as to cover the surroundings of a surface where the microphones 2 come into contact with the holding member 4 inside a bucket of the recessed part 5. Namely, the surface where the microphones 2 come into contact with the holding member 4 is installed at a lower part (lower surface side) rather than an upper surface side casing 11. In addition, in the recessed part 5, a sound pickup member 6 having the same thickness as height of a surrounding wall part 51 is engaged into the inside of the bucket. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sound collection device including a microphone (for example, a unidirectional microphone or a bi-directional microphone) that forms directivity by using a phase difference between sounds incident before and after a diaphragm.

  Conventionally, various sound collection devices including a unidirectional microphone and a bidirectional microphone have been proposed (see, for example, Patent Document 1).

In the stereo microphone of Patent Document 1, signal processing is performed on the output signal of the unidirectional microphone and the output signal of the bidirectional microphone, respectively, and the left channel and right channel audio signals are generated. In the stereo microphone, it is necessary to provide a space in the central axis direction with the central axis direction with respect to the sound collection surface of the unidirectional microphone and the bi-directional microphone as the directional direction. However, in order to install in the housing so as to provide a space around these microphones, for example, the microphone 2 is installed on the upper surface of the housing 100A as shown in FIG. In this case, since the microphone 2 protrudes from the upper surface of the housing 100A, the protrusion on the upper surface is conspicuous and the design is not refined. Further, for example, as shown in FIG. 4B, when the microphone 2 is installed in the housing 100B and the directivity direction with respect to the sound collection surface of the microphone 2 in the housing 100B is meshed (shaded portion), the housing Since the body 100B becomes thick, the housing 100B becomes large. As described above, thin stereo microphones with unidirectional microphones and bidirectional microphones that form directivity using the phase difference between the sound incident on the front and back of the diaphragm with a sophisticated design. It ’s difficult.
Japanese Patent Laid-Open No. 11-205888

  Therefore, for example, as shown in FIG. 4C, in order to reduce the thickness of the stereo microphone, it is conceivable to install these microphones 2 below the upper surface of the housing 100C. Specifically, a recess 5 ′ is provided in the housing 100 </ b> C, and the microphone 2 is installed inside the recess 5 ′. However, as shown in FIG. 5, the microphone 2 installed inside the recess 5 ′ of the casing 100 </ b> C picks up the reflected sound 72 of the sound 71 incident on the recess 5 ′ of the casing 100 </ b> C. At this time, the sound 71 and the reflected sound 72 directly picked up by the microphone 2 have a difference in sound collection time, so that a phase shift occurs and the directivity of the microphone 2 deteriorates. Arise. In particular, as the time difference is larger, the deterioration in the practical band is more remarkable.

  Accordingly, the present invention provides a sound collecting device having a microphone that forms directivity using the phase difference of sound incident before and after the diaphragm, and is thin with a sophisticated design without degrading directivity. An object of the present invention is to provide an integrated sound collecting device.

  A sound collecting device according to the present invention is a sound collecting device including a microphone that forms directivity by using a phase difference between sounds incident before and after a diaphragm, and is provided inside a housing. A holding member that holds the microphone so that an installation surface is located below the upper surface of the housing; a bowl-shaped recess that is provided inside the holding member and covers the periphery of the microphone; And a sound-absorbing member that is fitted inside and has the same thickness as the height of the inside of the bag.

  In this configuration, the sound collection device includes a microphone that forms directivity by using a phase difference between sounds incident before and after the diaphragm, such as a unidirectional microphone or a bidirectional microphone. A holding member for holding the microphone is provided inside the housing of the sound collecting device. The holding member is installed in the housing such that the microphone is installed inside the holding member, and the installation surface of the microphone on the holding member is located below the upper surface of the housing. In addition, a hook-shaped recess is provided inside the holding member, and the periphery of the installation surface of each microphone on the holding member is covered with the recess. A sound absorbing member having the same thickness as the height inside the bag is fitted into the bag inside the recess. Thereby, since the sound collection device can reduce the time difference between the sound collected by the microphone and the reflected sound by providing the bowl-shaped recess, it is possible to suppress the deterioration of directivity in the practical band. . Moreover, since the microphone is difficult to collect the reflected sound by providing the sound absorbing member, the sound collecting device can further suppress the deterioration of directivity. Furthermore, since the bottom surface of the microphone is positioned below the top surface of the housing, the sound collection device can prevent the microphone from protruding from the housing. For this reason, the sound collecting device can reduce the thickness of the housing with a sophisticated design without deteriorating directivity.

  Further, the sound absorbing member of the sound collecting device of the present invention is characterized in that it absorbs sound in a frequency band in which the distance between the opposing side surfaces of the concave portion is approximately half the wavelength of the sound wave.

  In this configuration, the sound absorbing member provided in the sound collecting device has a frequency band in which the distance between the opposing side surfaces of the concave portion of the holding member is approximately half the wavelength of the sound wave, that is, the sound that directly enters the diaphragm of the microphone and its reflection. It has a high sound absorption coefficient in a frequency band where interference with sound occurs. As a result, the level of the reflected sound collected by the microphone decreases in the frequency band where interference occurs. As a result, sound can be collected without degrading directivity in the voice band.

  The sound collecting device according to the present invention is a sound collecting device including a microphone that forms directivity by using a phase difference between sounds incident before and after a diaphragm, and is refined without degrading directivity. The housing can be thinned by design.

  A sound emitting and collecting apparatus 1 according to the present invention will be described with reference to FIG. FIG. 1 is an external view of a sound emission and collection device. FIG. 1A is a top view of the sound emission and collection device, and FIG. 1B is a perspective view of the sound emission and collection device. The surface shown in FIG. 1A is referred to as the upper surface, the lower side toward the paper surface in FIG. 1A is referred to as the front surface, and the right side toward the paper surface in FIG. The left side of the sheet of 1 (A) is referred to as the left side.

  As shown in FIG. 1A, the sound emitting and collecting apparatus 1 has a substantially rectangular shape when viewed from the top. In the sound emission and collection device 1, a microphone cover 21 that has been meshed is provided in the approximate center of the housing 10. A microphone 2 (see FIG. 2) is provided inside the housing 10 and below the microphone cover 21. The microphone 2 includes two bidirectional microphones 2A and 2B and one omnidirectional microphone 2C, and picks up surrounding sounds and generates a sound collection signal. By performing various types of signal processing on the collected sound signal, the sound emitting and collecting apparatus 1 forms a collected sound beam signal having directivity.

  In the sound emission and collection device 1, a plurality of slits 22 are formed in a continuous shape on both sides of the microphone cover 21. Speakers SP are respectively provided below the slits 22 in the housing 10. The speaker SP emits a sound emission signal.

  The sound emission and collection device 1 is provided with an operation unit 31 on the upper surface of the housing 10 along the front side wall, and a display unit 33 corresponding to the operation unit 31 on the side facing the front side wall with respect to the operation unit 31. Is provided on the upper surface of the housing 10. The operation unit 31 receives a user operation input and outputs an operation signal corresponding to the operation input content to a control unit (not shown). The control unit performs various processes according to the operation signal. The display unit 33 is made of a light emitter such as an LED or a lamp, and is provided to correspond to the operation unit 31. In response to an instruction from the control unit, the display unit 33 causes the light emitter corresponding to the input operation unit 31 to emit light. Thereby, the user can confirm the operation input content to the operation part 31 visually.

  The sound emission and collection device 1 includes a power cable 35 on the front side wall of the device. The sound emission and collection device 1 supplies power from a power source (not shown) via the power cable 35. In addition, the sound emission and collection device 1 communicates with another sound emission and collection device 1 via the PLC via the power cable 35. The sound emission and collection device 1 transmits the generated sound collection beam signal to another sound emission and collection device via the power cable 35, and receives a sound emission signal from the other sound emission and collection device via the power cable 35. Receive.

  As shown in FIG. 1B, the housing 10 of the sound emitting and collecting apparatus 1 includes an upper surface side housing 11 and a lower surface side housing 12. A holding member 4 for holding the microphone 2 is installed inside the housing 10. Details of the holding member 4 will be described later.

  The sound emission and collection device 1 is provided with a volume 32 and an audio input terminal 34 on the right side wall of the device. The volume 32 is an operation unit that adjusts the sound output volume from the speaker SP. The audio input terminal 34 is connected to a playback device such as an audio player, and a sound emission signal is input from the playback device.

  Next, the holding member 4 which is a characteristic part of the present invention will be described with reference to FIG. FIG. 2 is an external view of the holding member. FIG. 2A shows a top view of the holding member, and FIG. 2B shows a perspective view of the holding member. 2A is referred to as an upper surface, a surface viewed from the back side of the paper surface of FIG. 2A is referred to as a lower surface, and a lower side toward the paper surface of FIG. 2A is referred to as a front surface. The upper side toward the paper surface of FIG. 2 (A) is referred to as the back surface, the right side toward the paper surface of FIG. 2 (A) is referred to as the right side surface, and the left side toward the paper surface in FIG. .

  As shown in FIGS. 2A and 2B, the holding member 4 is provided with a storage portion 42 for storing the microphone 2 in the center, and storage portions 41 and 43 for storing the speaker SP on both sides of the storage portion 42, respectively. Is provided. The storage unit 41 includes a bottom portion 411 and a peripheral wall portion 412 that covers the periphery of the bottom portion 411. The storage unit 41 is open on the upper surface side in the opening 413. Similarly, the storage part 42 includes a bottom part 421 and a peripheral wall part 422 that covers the periphery of the bottom part 421. The storage unit 42 is open on the upper surface side at the opening 423. The storage portion 43 includes a bottom portion 431 and a peripheral wall portion 432 that covers the periphery of the bottom portion 431. The storage unit 43 is open on the upper surface side in the opening 433. Note that the peripheral wall portion 412 and the peripheral wall portion 422 partially share the same wall, and the peripheral wall portion 422 and the peripheral wall portion 432 partially share the same wall.

  In the holding member 4, the openings 413, 423, and 433 of the storage portions 41 to 43 are formed on the same surface. The holding member 4 includes a bottom portion 411 and a bottom portion 431 that are formed on the same plane, and the bottom portion 421 is formed closer to the opening 423 than the bottom portion 411. For this reason, in the holding member 4, the peripheral wall portion 412 and the peripheral wall portion 432 are formed at the same height, and the peripheral wall portion 422 is formed at a height shorter than the peripheral wall portion 412.

  In the holding member 4, screw fixing portions 441 to 444 are formed on the outer peripheral surfaces of the peripheral wall portion 412 and the peripheral wall portion 432. The holding member 4 has bottom portions 411, 421, 431 arranged on the lower surface side housing 12 side and openings 413, 423, 433 arranged on the upper surface side housing 11 side, and screwed portions 441 to 444 to the housing 10. Screwed.

  The storage portion 41 is provided with a fitting portion 414 that is opened in a circular shape at the approximate center of the bottom portion 411, and a notch portion 415 is provided on the front side of the peripheral wall portion 412. The speaker SP is fixed by being fitted into the fitting portion 414 with the sound emitting surface facing the opening 413. The wiring from the speaker SP is led out of the storage unit 41 from the notch 415.

  Similarly, the storage portion 43 is provided with a fitting portion 434 that is opened in a circular shape at substantially the center of the bottom portion 431, and a notch portion 435 is provided on the front side of the peripheral wall portion 432. The speaker SP is fixed by being fitted into the fitting portion 434 with the sound emitting surface directed toward the opening 433. The wiring from the speaker SP is led out of the storage unit 43 from the notch 435.

  In the storage part 42, a bowl-shaped recess 5 is provided at the approximate center of the bottom part 421. The peripheral wall 51 of the recess 5 is formed at the same height as the peripheral wall 422. Therefore, the opening 52 of the recess 5 is formed on the same plane as the opening 423.

  Microphones 2 </ b> A to 2 </ b> C are installed in the order of the microphones 2 </ b> A, 2 </ b> B, and 2 </ b> C from the back direction to the front direction inside the bag of the recess 5. The bidirectional microphone 2A is installed with the diaphragm facing the left side and the right side, and the bidirectional microphone 2B is installed with the diaphragm facing the front and back. The omnidirectional microphone 2 </ b> C is installed with the diaphragm facing the opening 52. Moreover, the microphone 2 is installed inside the ridge of the recess 5 so as to cover the periphery of the surface where the microphone 2 is in contact with the holding member 4 (corresponding to the installation surface of the microphone in the present invention). Thereby, since the microphone 2 is surrounded by the recess 5, the sound collection time difference between the directly incident sound and the reflected sound is reduced, so that the wavelength at which the directly incident sound and the reflected sound are opposite in phase is shortened. Since the frequency becomes high, it is possible to reduce the degradation of directivity due to interference in the practical band.

  Here, if the path difference d between the directly incident sound and the reflected sound is d and the sound speed v, the frequency f at which the directly incident sound and the reflected sound are in opposite phases can be expressed by f = v / 2d. For example, when the sound velocity is v = 340 m / s and the sound is incident on the diaphragm of the microphone 2 in the horizontal direction, since the diameter of the concave portion 5 of this embodiment is about 35 mm, the thickness of the microphone can be ignored. In this case, the path difference d is 0.035 m. At this time, f = 340 / 0.07 = 4.857 kHz. Actually, since the sound wave is also incident from an oblique direction, the frequency band affected by the interference is further lowered, but the difference is small because the incident angle of the reflected sound is limited by the concave portion 5 and is about 4.8 kHz. Interference can be reduced in the following frequency bands.

  Further, since the microphone 2 is installed inside the bag of the recess 5, the surface on which the microphone 2 is in contact with the holding member 4 is installed below the lower surface side housing 11 (lower surface side). Thereby, the sound emission and collection device 1 can minimize the protrusion of the microphone 2 from the housing 10. For this reason, while refine | purifying the design of the sound emission and collection apparatus 1, the housing | casing 10 of the sound emission and collection apparatus 1 can be reduced in thickness.

  Further, at this time, if the microphone 2 is installed so that the diaphragm of the microphone 2 is above (upper surface side) than the upper surface side housing 11, the housing 10 and the holding member 4 become a barrier for sound incident on the microphone 2. Sound can be picked up. That is, when the surface of the microphone 2 in contact with the holding member 4 is below the lower surface side housing 11 (lower surface side) and the diaphragm of the microphone 2 is above the upper surface housing 11 (upper surface side), The apparatus 1 can collect sound appropriately and can make the casing 10 as thin as possible.

  Further, the sound absorbing member 6 having the same thickness as the height of the peripheral wall portion 51 is fitted into the recess 5 inside the bag. The sound absorbing member 6 is made of a porous sound absorbing material such as urethane and absorbs incident sound, thereby suppressing the level of reflected sound.

  Next, the effect obtained by fitting the sound absorbing member 6 into the inside of the recess 5 will be described with reference to FIG. FIG. 3 is an explanatory diagram visualizing the sound incident on the microphone. As shown in FIG. 3, the sound 71 that has entered the recess 5 is absorbed by the sound absorbing member 6 provided inside the ridge of the recess 5, and the level of reflected sound decreases. For this reason, since the microphone 2 picks up the directly incident sound 71 at a high level and does not pick up the reflected sound, there is no interference between the directly incident sound and the reflected sound, so the directivity is not deteriorated. Can be picked up.

  In addition, the sound absorbing member 6 made of a porous sound absorbing material generally has a characteristic that the sound absorption coefficient becomes high in a high sound range, but the sound absorption coefficient can be adjusted by density, thickness, etc. Can be adjusted as appropriate. For example, if the sound absorption rate is adjusted so as to exceed about 50% at about 4.8 kHz or higher, interference due to reflected sound can be reduced. As a result, interference in the voice band can be reliably reduced, and sound can be collected without degrading the directivity of the voice band.

  In the present embodiment, the sound emission and collection device 1 including the two bidirectional microphones 2A and 2B and the one omnidirectional microphone 2C has been described as an example. However, the configuration of the microphone is not limited to this. In a sound emission and collection device equipped with a microphone that forms directivity using the phase difference of the sound incident before and after the diaphragm, by applying the present invention, the design can be refined without degrading the directivity. The housing can be thinned.

  In the present embodiment, the holding member 4 holds the microphone 2 and the speaker SP. However, the holding member 4 may not hold the speaker SP, and only the microphone 2 may be held.

  Furthermore, in the present embodiment, the sound emitting and collecting apparatus 1 has been described as an example. However, it is not necessary to provide a sound emitting function, and directivity is formed by using a phase difference between sounds incident before and after the diaphragm. Any sound collecting device including a microphone, for example, a unidirectional microphone or a bidirectional microphone may be used.

It is an external view of a sound emission and collection device. It is an external view of a holding member. It is explanatory drawing which visualized the incident sound to a microphone. It is explanatory drawing regarding attachment of the housing | casing and the microphone in the conventional sound collection device. It is explanatory drawing which visualized the incident sound to the microphone in the conventional sound collection device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sound emission and collection apparatus, 2 (2A-2C) ... Microphone, 4 ... Holding member, 5 ... Recessed part, 6 ... Sound absorption member, 10, 100A-100C ... Housing | casing, 11 ... Upper surface side housing | casing, 12 ... Lower surface side Housing, 21 ... Microphone cover, 22 ... Slit, 31 ... Operation part, 32 ... Volume, 33 ... Display part, 34 ... Audio input terminal, 35 ... Power cable, 41-43 ... Storage part, 51 ... Perimeter wall part of recess 52, recess opening, 71, sound, 72, reflected sound, 411, 421, 431 ... bottom of storage, 412, 422, 432 ... peripheral wall of storage, 413, 423, 433 ... opening of storage Part, 414, 434 ... fitting part of storage part, 415, 435 ... notch part of storage part, 441-444 ... screwing part, SP ... speaker

Claims (2)

A sound collecting device including a microphone that forms directivity by using a phase difference of sound incident before and after a diaphragm,
A holding member that is provided inside the housing and holds the microphone so that an installation surface of the microphone is positioned below the upper surface of the housing;
A hook-shaped recess provided inside the holding member and covering the periphery of the microphone;
And a sound-absorbing member that is fitted into the inside of the ridge of the recess and has the same thickness as the height inside the heel.   The sound collecting device according to claim 1, wherein the sound absorbing member absorbs a frequency band in which a distance between opposing side surfaces of the concave portion is approximately a half wavelength of a sound wave.

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