JP2005295278

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DESCRIPTION JP2005295278
PROBLEM TO BE SOLVED: To rationally configure a microphone device which can be
miniaturized and can be unidirectional. SOLUTION: A thin and bidirectional microphone M is
provided inside a case C, and a first sound hole H1 and a second sound hole H2 are formed in the
front wall portion 11 of the case C, and the first sound hole H1 is formed. Inside the case C, a
first sound introducing space S1 for guiding an acoustic signal from the microphone to the front
face F of the microphone M and a second sound introducing space S2 for guiding an acoustic
signal from the second sound hole H2 to the rear face R of the microphone M By forming an
acoustic resistance material D in the second sound introducing space S2, a sound pressure
difference is created between the front face F and the rear face R of the microphone M to
enhance the sensitivity. [Selected figure] Figure 2
Microphone device
[0001]
The present invention relates to a microphone device provided with a microphone inside a case
and configured to guide an acoustic signal from a sound hole formed in the case to the
microphone.
[0002]
As a technique related to the microphone device configured as described above, one described in
Patent Document 1 exists.
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In this patent document 1, an open / close body (case of the present invention) is supported in a
freely openable and closable manner via a hinge on a mobile phone, and a bidirectional
microphone is disposed inside the open / close body, and an inner side wall portion of the open /
close body An inner sound hole is formed in the outer wall, an outer sound hole is formed in the
outer wall, a sound path connecting the inner sound hole and the front sound hole of the
microphone is formed inside the opening / closing body, and the outer sound hole and the rear
sound hole of the microphone Form a sound path connecting the In this microphone device,
sound collection with a large S / N ratio is realized from the pressure difference between the
sound waves entering the inside of the opening and closing body from the two sound holes.
[0003]
JP, 2003-110676, A (paragraph number [0018]-[0023], FIG. 4)
[0004]
Recently, on-vehicle information systems that change cars from simple moving spaces to
communication spaces are attracting attention, and in order to realize this communication space,
real-time traffic information can be obtained by mounting a computer connected to the Internet
to a car, Acquisition of navigation information, automatic notification at the time of theft, etc. are
being realized.
Also, in order to realize such a communication space, a microphone with good directivity is
desired.
[0005]
As a specific usage form of the microphone, it can be considered to be built in a map light or a
room mirror in a car, or a steering wheel portion or a front panel portion in order to catch a
voice from a driver or a passenger in the front passenger seat. Although microphones provided at
such places need to be unidirectional in order to obtain voices at relatively distant locations, such
unidirectional microphones have the disadvantage of being limited in thinness and
miniaturization. There is.
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[0006]
When an electret microphone is considered as a microphone that can be miniaturized, there are a
bidirectional microphone and a unidirectional microphone described in Patent Document 1.
Bidirectionals are easier to miniaturize and cheaper than bidirectionals and unidirectionals. From
this point of view, it is desirable to create a unidirectional microphone device using a
bidirectional microphone.
[0007]
An object of the present invention is to rationally configure a microphone device that can be
miniaturized and can be unidirectional.
[0008]
A feature of the present invention is that, in the microphone device provided with a microphone
inside a case and configured to guide an acoustic signal from a sound hole formed in this case to
the microphone, the microphone is a sound from both directions along the axial direction. A first
sound hole and a second sound hole are formed as the sound holes in the same wall portion of
the case while being configured in a bi-directional type for acquiring a signal, and the first sound
hole is formed in the inside of the case A first sound introducing space for guiding an acoustic
signal from the microphone to the front surface of the microphone, and a second sound
introducing space for introducing an acoustic signal from the second sound hole to a rear surface
of the microphone; And the second sound introducing space is provided with an acoustic
resistance material.
[0009]
According to this configuration, the acoustic signal guided to any one of the first sound
introducing space and the second sound introducing space is delayed by the acoustic resistance
material, so that the front surface of the microphone from the first sound hole through the first
sound introducing space It is possible to create a sound pressure difference between the sound
signal guided to the sound signal and the sound signal guided from the second sound hole to the
rear surface of the microphone through the second sound introducing space, and the sound
signal can be acquired by the bidirectional microphone Become.
In particular, since the first sound hole and the second sound hole are formed in the same wall
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portion of the second sound hole and the case, directivity can be obtained in the direction in
which the respective sound holes are opened.
As a result, a uni-directional microphone device that can be downsized using an inexpensive and
easily manufactured bi-directional microphone is rationally configured.
[0010]
In the present invention, the case is composed of a front housing and a rear housing, and the first
sound hole and the second sound hole are formed on a front wall portion of the front housing in
a posture orthogonal to the axial center of the front housing. A wall is formed on the inner
surface side of the front wall to separate a space connected to the first sound hole and a space
connected to the second sound hole, and the wall, the front housing, and the rear housing
surround the wall. The second sound introducing space may be formed by the space being
generated.
[0011]
According to this configuration, the second sound introducing space is formed by the space
surrounded by the wall, the front housing and the rear housing, only by forming the wall in the
front housing and providing the rear housing.
That is, even if a special member for forming the second sound introducing space is not attached,
the setting of the structure of the front housing makes it possible to guide the acoustic signal
from the second sound hole to the rear surface of the microphone.
[0012]
The present invention arranges a partition inside the front housing so as to isolate the front
housing and the rear housing at right angles to the axis, and the first space is surrounded by the
partition and the front housing. A sound introducing space may be formed.
[0013]
With this configuration, it is possible to form a first sound introducing space in a state of being
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surrounded by the partition wall and the front housing.
That is, in the case where a bidirectional microphone is provided inside the case, the first sound
introducing space is formed on the front side of the microphone and the second sound
introducing space is formed on the rear side of the microphone. It will be arranged at the middle
position in the longitudinal direction of the case, but by arranging the partition wall, it is possible
to create the first sound introducing space and to guide the acoustic signal from the first sound
hole to the front of the microphone .
[0014]
In the present invention, the microphone may be supported by a substrate, and the substrate
may be disposed parallel to the partition wall.
[0015]
With this configuration, by disposing the substrate at a position parallel to the partition wall, the
acoustic signal is not disturbed even if the substrate is disposed on the side exposed to the first
sound introducing space.
[0016]
In the present invention, the microphone may be configured as an electret type in which a
diaphragm and an impedance conversion element are housed inside a disk-like capsule in which
an acoustic opening is formed on the front side and the rear side.
[0017]
With this configuration, downsizing of the entire microphone device is realized by using the diskshaped capsule-type microphone.
[0018]
Hereinafter, embodiments of the present invention will be described based on the drawings.
As shown in FIGS. 1 and 2, a microphone device is configured by housing a microphone M
having a bi-directionality in a case C.
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This microphone device guides an acoustic signal from the first sound hole H1 formed in the
case C to the front surface F of the microphone M through the first sound introducing space S1,
and an acoustic signal from the second sound hole H2 formed in the case C Is guided to the rear
surface R side of the microphone M by the second sound introducing space S2, and the acoustic
resistance material D provided in the second sound introducing space S2 is an acoustic guided to
the second sound introducing space S2. The signal is delayed, and a sound pressure difference is
created between the front surface F and the rear surface R of the microphone M to obtain voice.
In the present embodiment, the acoustic resistance material D is provided in the second sound
introduction space S2, but the acoustic resistance material D may be provided in the first sound
introduction space S1.
In particular, in the present invention, the acoustic resistance material D may be provided in both
the first sound introducing space S1 and the second sound introducing space S2 (all of the first
sound introducing space S1 and the second sound introducing space S2 If the acoustic resistance
material D is provided in the first sound introducing space S1, the acoustic resistance material D
may be disposed in the vicinity of the first sound hole H1 or in front of the microphone M. In the
case where the second sound introducing space S2 is provided with the acoustic resistance
material D, the second sound introducing space S2 can be disposed at a position near the second
sound hole H2 in addition to the position shown in the drawing.
[0019]
The microphone device according to the present invention is compact and unidirectional for
catching voices from the driver and the passenger in the front passenger seat by incorporating it
in a map light, a rearview mirror, etc. provided in the car. The specific structure will be described
below.
[0020]
As shown in FIG. 3, the bi-directional microphone M has a plurality of acoustic apertures Ma
formed on the front face F and the rear face R, and the impedance of the diaphragm, FET, etc.
inside the capsule Mb made of metal is thin. It is configured in an electret type including a
conversion element (not shown), and is configured to take in good acoustic signals from both the
front and back sides along the axis X passing through the center position of the capsule Mb.
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Also, the microphone M is supported at one end of the substrate 1. In this substrate 1, a printed
wiring is formed of an insulating material such as glass epoxy, and an chip circuit is fixed to the
printed wiring by soldering to form an amplifier circuit for amplifying a signal from the
microphone M. The other end of the substrate 1 is connected to a cable 3 for taking out a signal
amplified by an amplifier circuit. The substrate 1 does not necessarily have to have an amplifier
circuit, but has a structure in which only printed wiring for taking out a signal from the
microphone M is formed, or a structure having a circuit for wirelessly transmitting signals other
than the amplifier circuit. It may be
[0021]
The case C is a resin-made front housing 10 integrally formed with a rectangular front wall 11 in
which the first sound hole H1 and the second sound hole H2 are formed, and a side wall 12
surrounding the same. The rear housing 20 is made of a resin and is formed in a plate shape so
as to close an opening at the rear of the front housing 10.
[0022]
That is, as shown in FIGS. 4 and 5, in the front housing 10, the first sound hole H1 and the
second sound hole H2 are formed in a slit shape at an end position of the front wall portion 11,
and the front wall A first holder 13 is integrally formed on the inner surface side of the portion
11 so as to support the front side of the microphone M.
The first holder 13 is formed in a ring shape having an open portion 13A in which a part on the
side of the first sound hole H1 is opened. An arc-shaped wall 14 is disposed on the front housing
10 on the side of the second sound hole H2 with respect to the first holder 13 so as to separate
the space connected to the first sound hole H1 and the space connected to the second sound hole
H2. It is integrally formed with. Further, at the end of the side wall portion 12, a cable guide
portion 15 which allows insertion of the cable 3 is formed.
[0023]
The rear housing 20 has a rear wall 21 and a second holder 22 integrally supported on the inner
surface of the rear wall 21 so as to be in contact with the rear surface of the microphone M.
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There is. The second holder 22 is formed in a ring shape having an open portion 22A in which a
part on the side of the second sound hole H2 is opened. Thereafter, a pair of positioning portions
23 are provided in a projecting manner on the inner surface side of the housing 20. Further, a
cable guide portion 24 which allows insertion of the cable 3 is formed at an end portion of the
housing 20 thereafter.
[0024]
Inside the case C, a first intermediate member A and a second intermediate member B are
accommodated. That is, the first intermediate member A includes the partition wall 31 forming a
space connected to the first sound hole H1 and the open portion 13A of the first holder 13 and
the ring-shaped portion 32 externally fitted to the first holder 13. The ring-shaped portion 32 of
the first intermediate member A is formed of an integrated flexible resin, and an open portion
32A is formed at a portion corresponding to the open portion 13A of the first holder 13. In
addition, the second intermediate member B is a flexible integrated ring-like portion 35 in
contact with the second holder 22 and a guide portion 36 having an open portion 36A opened to
the second sound hole H2 side. It is formed of resin.
[0025]
Thus, since the case C and the microphone M are formed, when the microphone device of the
present invention is assembled, the first holder 13 is set after the first intermediate member A is
set on the inner surface side of the front housing 10. , The microphone M is set in a state where
the front face F is in contact. When the intermediate member A is set as described above, the
partition wall 31 formed on the intermediate member A is in a parallel posture (a posture
orthogonal to the axial center X) with the front wall portion 11. Next, the second intermediate
member B is set on the inner surface side of the rear housing 20, and the acoustic resistance
material D made of a foam resin pad is set, and then the rear housing 20 is fitted to the front
housing 10. It is closed and fixed with an adhesive or the like, and a cross 40 having a large
number of fine openings (a gap between fibers) through which an acoustic signal passes is stuck
and fixed to the outer surface of the front wall portion 11. When the rear housing 20 is fixed in
this manner, the acoustic resistance material D is sandwiched between the second intermediate
member B and the rear wall portion 21 of the rear housing 20 and compressed, thereby the
inside of the second sound introducing space S2 The acoustic resistance material D can be filled
with no gap.
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[0026]
In this assembled state, the case C is a space closed by the front wall 11, the rear wall 21 and the
four side walls 12 (the first sound hole H1 and the second sound hole H2 are open). The position
of the microphone M is determined by sandwiching the microphone M in the front-rear direction
(direction along the axis X) by the first holder 13 and the second holder 22. Further, the end
edge portion of the substrate 1 is sandwiched between the end edge portion of the partition 31
of the first intermediate member A and the pair of positioning portions 23 formed in the rear
housing 20, and the first intermediate member A and The position relative to the substrate 1 is
determined, and the partition 31 of the first intermediate member A and the substrate 1 are
brought into contact in a parallel posture and supported in a stable state. Further, by
sandwiching the cable 3 connected to the substrate 1 between the cable guide portion 15 of the
front housing 10 and the cable guide portion 24 of the rear housing 20, the tension from the
cable 3 does not act on the substrate 1 There is.
[0027]
In this microphone device, the first sound hole H1 to the front surface F of the microphone M are
continuous from the first sound hole H1 to a portion surrounded by the front wall 11 and the
side wall 12 of the front housing 10 and the partition 31 of the first intermediate member A 1 at
a location where a sound introducing space S1 is formed, and is surrounded by the side wall 12
and the wall 14 of the front housing 10, the rear wall 21 of the rear housing 20, and the guide
36 of the second intermediate member B The second sound introducing space S2 continuing
from the second sound hole H1 to the rear surface R of the microphone M is formed, and the
acoustic resistance material D is provided in a form filling the second sound introducing space
S2.
[0028]
Then, in this microphone device, acoustic signals from the directions in which the first sound
hole H1 and the second sound hole H2 are opened are taken into the inside of the case C from
the first sound hole H1 and the second sound hole H2, An acoustic signal from the first sound
hole H1 is guided to the front surface F of the microphone M through the first sound introducing
space S1, and an acoustic signal from the second sound introducing space S2 is transmitted
through the second sound introducing space S2. When it is guided to the rear surface R, it is
delayed by contact with the acoustic resistance material D, and an acoustic signal is transmitted
to the rear surface R of the microphone M at this delayed timing, so it is added to the front
surface F of the microphone M and the rear surface R The sound pressure difference is created in
the sound signal to be converted, and the sound signal can be converted into the electric signal
with high sensitivity.
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[0029]
As described above, the microphone device according to the present invention is the case in
which the microphone M having the bidirectionality is accommodated in the case C, and the first
sound hole H1 and the second sound hole H2 formed in the front wall portion 11 of the case C
Not only can it be used as a single directional microphone with high sensitivity in the direction of
opening, but a thin, inexpensive microphone can be used as the bidirectional microphone M, so
the overall size of the device can be reduced. Not only is it possible, but it can be manufactured
cheaply.
[0030]
Another Embodiment The present invention may be provided in a recording apparatus for
recording voice in a cellular phone or a semiconductor memory, in addition to the abovedescribed embodiments.
Further, it is possible to form the first sound introducing space S1 and the second sound
introducing space S2 formed in the inside of the case C only by the members constituting the
case C, and the substrate 1 for supporting the microphone M is not limited to the above. You may
comprise so that it may be used for a partition.
[0031]
The sectional view of the microphone device The sectional view of the microphone device The
perspective view showing the front side and the back side of the microphone The sectional view
showing the structure of each part of the microphone device The exploded perspective view of
the microphone device
Explanation of sign
[0032]
Reference Signs List 1 substrate 10 front housing 11 front wall portion 14 wall 20 rear housing
31 partition C case D acoustic resistance material F front surface of microphone R rear surface of
microphone M microphone acoustic aperture Mb capsule X axis core H1 first sound hole / sound
hole H2 2nd sound hole · sound hole S1 1st sound conduction space S 2 2nd sound transmission
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space
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