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JP2005277899

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DESCRIPTION JP2005277899
PROBLEM TO BE SOLVED: To provide a high-performance acoustic vibration detection apparatus
having sharp directivity and not easily influenced by the surrounding environment. A
microphone unit 4 and a housing 1 surrounding the microphone unit 4 are provided from an
external sound source. Acoustic vibration detection apparatus for detecting and collecting the
vibration of the sound of the first unit, the first opening 10 communicating with the front of the
housing 1 facing the sound source from one surface of the diaphragm 4a of the microphone unit
4; From the back surface of one side to the back surface opposite to the front surface of housing
1 or the second opening 11 communicating with the top surface substantially perpendicular to
the front surface of housing 1, and from the back surface of diaphragm 4a An acoustic vibration
detection apparatus is provided that includes third openings 13, 13, 14, and 14 communicating
with both front and rear positions of the surface. [Selected figure] Figure 2
Acoustic vibration detector
[0001]
The present invention relates to an acoustic vibration detection device which picks up sound and
converts it into an electrical signal.
[0002]
BACKGROUND ART Conventionally, an acoustic vibration detection device attached to an
electronic device having a recording function such as a video camera or the like is known (see,
for example, Patent Document 1).
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1
[0003]
As a well-known acoustic vibration detection apparatus, for example, as shown in FIG. 14, an
apparatus having a structure in which a front detection hole 23 and a rear detection hole 24 are
provided in front and back of a housing 22 surrounding a microphone unit 21 (conventional
apparatus 25) and a device (conventional device 35) having a front detection hole 33 and a rear
detection hole 34 at the front and back of the top surface of the casing 32 surrounding the
microphone unit 31, as shown in FIG. It is done.
[0004]
The conventional device 25 can direct the front detection hole 23 to the sound source, and can
provide directivity by the sound collection from the front detection hole 23 and the sound
collection from the rear detection hole 24.
Also, the conventional device 35 places the housing 32 so that the surface provided with the
front detection hole 33 and the rear detection hole 34 is at the upper side perpendicular to the
direction of the sound source and the front detection hole 33 is on the sound source side The
directivity can be given by the sound collection from both holes 33 and 34.
Thus, the conventional devices 25 and 35 have bi-directional characteristics using the phase
difference between the sound collection from the front detection holes 23 and 33 and the sound
collection from the rear detection holes 24 and 34.
[0005]
JP-A-8-237785 (abstract book etc.)
[0006]
However, the conventional apparatuses 25 and 35 have the following problems.
When the conventional device 25 is used in the vicinity of a wall, it is susceptible to the reflection
from the wall surface 27 of the sound to be acquired.
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2
In order to eliminate such an influence, it is necessary to extend the mounting plate 26 from the
wall surface 27 and install the conventional device 25, resulting in a restriction that the
conventional device 25 must be disposed at a certain distance from the wall surface 27. .
[0007]
On the other hand, in the case of the conventional device 35, by installing the front detection
hole 33 and the rear detection hole 34 in a row with respect to the sound source, even if the
conventional device 35 is placed on the wall 36 and used There is almost no influence of the
reflection from 36. However, since both detection holes 33 and 34 do not face the direction of
the sound source, there arises a problem that the sound quality is degraded. In particular, in the
high sound range where the straight propagation is high, the problems of the deterioration of the
sound collection and the deterioration of the directivity characteristic become remarkable.
[0008]
The present invention has been made in view of such problems, and an object thereof is to
provide a high-performance acoustic vibration detection device having a sharp directivity and
being less susceptible to the influence of the surrounding environment.
[0009]
In order to solve the above-mentioned problems, the present invention is an acoustic vibration
detection apparatus which comprises a microphone unit and a casing surrounding the
microphone unit, and detects and picks up vibration of sound from an external sound source. A
first opening from one side of the plate to the front of the housing facing the sound source, and a
second side from the back of the diaphragm to the rear opposite to the front of the housing or an
upper surface substantially perpendicular to the front of the housing The acoustic vibration
detection device includes the second opening and the third opening that leads from the back
surface of the diaphragm to both the front and rear positions of the side surface of the housing
with respect to the sound source.
[0010]
In another embodiment of the present invention, in addition to the above-described invention, the
acoustic vibration detection apparatus further includes a fourth opening communicating with the
front surface of the housing from the back surface of the diaphragm.
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3
[0011]
According to the present invention, it is possible to provide a highly functional acoustic vibration
detection device that has sharp directivity and is not easily influenced by the surrounding
environment.
[0012]
Hereinafter, embodiments of an acoustic vibration detection device according to the present
invention will be described with reference to the drawings.
[0013]
FIG. 1 is a schematic perspective view of an acoustic vibration detection apparatus according to
an embodiment of the present invention.
Moreover, FIG. 2 is sectional drawing which cut this acoustic vibration detection apparatus
longitudinally.
Hereinafter, the left side in FIG. 2 will be referred to as "front", the right side as "back", the front
and back sides of the paper as "side", and the upper side as "upper".
FIG. 3 is a cross-sectional view of the acoustic vibration detection device shown in FIG.
4 is a cross-sectional view of the acoustic vibration detection apparatus shown in FIG. 2 taken
along the line Y-Y.
[0014]
The housing 1 of the acoustic vibration detection device has a substantially rectangular
parallelepiped shape formed of an upper cover 2 and a lower cover 3.
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4
As shown in FIG. 2, a microphone unit 4 is incorporated in the housing 1. The microphone unit 4
includes the diaphragm 4a, detects the vibration of the sound transmitted to the upper and lower
surfaces of the diaphragm 4a, and converts the vibration into an electric signal.
[0015]
The microphone unit 4 is incorporated in the housing 1 in a state of being covered with an
elastic material 5 such as rubber, and is electrically connected to the lower electronic circuit
board 6. Between the electronic circuit board 6 and the electrical wiring 7 connected thereto, a
rubber packing 8 for fixing the root of the electrical wiring 7 to the housing 1 is provided. The
rubber packing 8 is held in the rubber packing fixing hole 9 in a state where the upper cover 2
and the lower cover 3 are put together.
[0016]
On the other hand, a first opening 10 is provided in front of the upper cover 2. Further, a second
opening 11 is provided above the upper cover 2. Further, a fourth opening 12 is provided
immediately below the first opening 10. Furthermore, third openings 13, 13 are provided on the
front side of the side surfaces of the upper cover 2. In addition, third openings 14 and 14 are
provided on the rear side of both side surfaces of the upper cover 2.
[0017]
The first opening 10 passes through the inside of the housing 1 and reaches one surface of the
diaphragm 4 a of the microphone unit 4 from the hole 15 shown in FIG. 2. In addition, the
second opening 11, the third openings 13, 13, 14, 14 and the fourth opening 12 pass through
the inside of the casing 1 to vibrate the microphone unit 4 from the recess 16 shown in FIG. It
reaches the surface (back side) opposite to one side of the plate 4a. The paths for transmitting
the sound from the openings 10, 11, 12, 13, 14 to the diaphragm 4a will be described in detail
below.
[0018]
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5
FIG. 5 shows the upper cover 2 removed from the lower cover 3 and turned over. A microphone
unit fixing hole 17 is provided on the back of the upper cover 2. The microphone unit 4 shown in
FIG. 5 is fitted in the microphone unit fixing hole 17 while being covered with the elastic material
5. At the time of assembly, with the microphone unit 4 fitted in the microphone unit fixing hole
17 provided in the upper cover 2, the electronic circuit board 6 is covered and electrically
connected to the microphone unit 4, and the lower cover 3 is Combine with the upper cover 2.
[0019]
A diaphragm 4 a is provided inside the microphone unit 4. Holes 4 b and 4 b communicating
with one surface of the diaphragm 4 a are provided on both side surfaces of the microphone unit
4. The elastic material 5 is configured such that the holes 4b and 4b are exposed to the outside.
[0020]
Further, in the partition plates on both sides of the microphone unit fixing hole 17 shown in FIG.
5, concave portions 16 and 16 which are dented on the bottom surface side of the microphone
unit fixing hole 17 are provided. When the microphone unit 4 is fitted into the microphone unit
fixing hole 17, the surface on one side of the diaphragm 4 a (the upper surface of the upper
cover 2) faces the hole 15.
[0021]
In addition, the holes 4 b and 4 b are in a state of coinciding with the concave portions 16 and
16. At the rear of the microphone unit 4, a convex portion 5 is provided. The convex portion 5 is
fitted into the concave portion 18 provided on the rear side partition plate of the microphone
unit fixing hole 17 without any gap. In the state where the microphone unit 4 is fitted in the
microphone unit fixing hole 17, the concave portions 16 and 16 are the second opening 11 and
the third opening 13 from the gap between the concave portions 16 and 16 and the side wall of
the upper cover 2. 13, 14, and 14 and does not communicate only with the first opening 10.
[0022]
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Therefore, the sound from the first opening 10 is transmitted to one surface of the diaphragm 4
(the upper surface of the upper cover 2) through the hole 15 (path A in FIG. 5). On the other
hand, the sound from the second opening 11, the third opening 13, 13, 14, 14 and the fourth
opening 12 both pass through the recess 16 and the hole 4b, and the back surface of one surface
of the diaphragm 4a. It is transmitted to (the lower surface of the upper cover 2) (path B in FIG.
5).
[0023]
Thus, the opening communicating with one surface (the upper surface of the upper cover 2) of
the diaphragm 4a in the microphone unit 2 is only the first opening 10, and the rear surface of
the diaphragm 4a (the lower side of the upper cover 2) The second opening 11, the third opening
13, 13, 14, 14 and the fourth opening 12 make the opening leading to the An acoustic vibration
detection apparatus having directivity can be realized. Moreover, since the openings other than
the first opening 10 and the second opening 11 (i.e., the third openings 13, 13, 14, 14 and the
fourth opening 12) are provided, acoustic vibration is generated. At the time of detection, the
influence of the reflected sound from the wall surface can be reduced.
[0024]
FIG. 6 is a view showing the azimuth sensitivity characteristic at 360 ° around the acoustic
vibration detection apparatus. FIG. 7 is a view showing the azimuth sensitivity characteristic at
360 ° around the acoustic vibration detection apparatus in a state in which the fourth opening
12 is closed. Furthermore, FIG. 8 is a view showing, for comparison, the azimuth sensitivity
characteristic at 360 ° around the conventional acoustic vibration detection device having only
the first opening 10 and the second opening 11. In FIGS. 6, 7 and 8 the direction of 0 ° is the
front of the device. In FIG. 6, FIG. 7 and FIG. 8, the alternate long and short dash line, solid line
and dotted line respectively indicate the acoustic sensitivity curves of sound at 300, 1000 and
3000 Hz and show sensitivity ratios in each direction with respect to the direction of 0 °. is
there.
[0025]
First, comparing FIG. 7 with FIG. 8, by opening the third openings 13, 13, 14, 14, both sides of
the device for three frequencies of 300, 1000 and 3000 are obtained. It can be seen that the
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7
sensitivity in both the 90 ° and 270 ° directions is reduced. This result shows that opening the
third openings 13, 13, 14, 14 improves the forward and backward bi-directionality of the device.
In addition, the sensitivity characteristics on both sides of the device tend to be low, especially
for sounds with high frequencies of 1000 and 3000 Hz, by opening the third openings 13, 13,
14 and 14 in comparison with each frequency. is there.
[0026]
Next, comparing FIG. 6 and FIG. 7, by opening the fourth opening 12, both sides of the device (90
° and 270 ° for sound of three frequencies of 300, 1000 and 3000) It can be seen that the
sensitivity in both directions of This result shows that opening the fourth opening 12 further
improves the forward and backward bi-directionality of the device. In addition, the sensitivity to
both sides of the device tends to be low, particularly for sounds with high frequencies of 1000
and 3000 Hz, by opening the fourth opening 12 as compared to each frequency.
[0027]
From the above results, when the third openings 13, 13, 14, 14 and the fourth opening 12 are
opened, the front and rear bi-directional characteristics are improved more than in the prior art,
especially for high-frequency sounds. Can be seen.
[0028]
FIG. 9 is a diagram showing frequency characteristics in the front (direction of 0 °), the left side
(direction of 90 °) and the right side (direction of 270 °) of the acoustic vibration detection
apparatus.
Further, FIG. 10 shows the frequency characteristics of the acoustic vibration detection apparatus
in the state in which the fourth opening 12 is closed in the front (direction of 0 °), on the left
side (direction of 90 °) and on the right side (direction of 270 °). FIG. Furthermore, as a
comparison, FIG. 11 shows the front (0 ° direction), the left side (90 ° direction) and the
conventional acoustic vibration detection device having only the first opening 10 and the second
opening 11. It is a figure which shows the frequency characteristic in the right side (direction of
270 degrees). As in Figures 6, 7 and 8, the 0 ° direction is the front of the device. Further, in
FIG. 9, FIG. 10 and FIG. 11, curve A shows a frequency characteristic of 0 °, curve B shows a
frequency characteristic of 90 °, and curve C shows a frequency characteristic of 270 °.
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[0029]
Here, since the curve B and the curve C show the frequency characteristics on both the left and
right sides of the device, they show almost the same characteristics. Although this means that the
left and right characteristics are well balanced, the comparison between the curve B and the
curve C will not be mentioned because the relation with the features of the present invention is
low. Here, the curve A, the curve B and the curve C (hereinafter referred to as curves B and
C . Only the relationship with
[0030]
First, comparing FIG. 10 with FIG. 11, the gain of the curves B and C is lowered by opening the
third openings 13, 13, 14, 14. In particular, the drop in gain is significant at frequencies in the
range of 1000 to 3000 Hz.
[0031]
Next, comparing FIG. 9 with FIG. 10, the gain of the curves B and C is further lowered by opening
the fourth opening 12. In particular, the drop in gain is significant at frequencies in the range of
1000 to 3000 Hz.
[0032]
Thus, also from the results shown in FIG. 9, FIG. 10 and FIG. 11, when the third openings 13, 13,
14, 14 and the fourth opening 12 are opened, the front and rear It can be seen that the
directivity characteristic is improved, particularly for high frequency sounds.
[0033]
FIG. 12 is a diagram showing vertical orientation sensitivity characteristics in the upper half
plane of the slope including the front of the acoustic vibration detection apparatus.
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9
FIG. 13 is a view showing vertical orientation sensitivity characteristics in the upper half plane of
the slope including the front of the acoustic vibration detection apparatus in a state in which the
fourth opening 12 is closed. The curves in both figures are curves with a frequency of 1 kHz.
[0034]
As apparent from comparison between FIG. 12 and FIG. 13, when the fourth opening 12 is
provided, the directivity shifts upward by 30 to 60 ° from both the front and rear directions,
and acoustic vibration detection is performed. It can be seen that the directivity is separated from
the side of installing the device. Therefore, for example, when the acoustic vibration detection
device is installed on a ceiling in a car, it is easy to pick up the driver's voice.
[0035]
The embodiment of the present invention has been described above, but the present invention is
not limited to the above-described embodiment, and can be practiced in variously modified
forms.
[0036]
For example, the acoustic vibration detection device may be a device in which only the third
openings 13, 13, 14 and 14 are provided without providing the fourth opening 12.
Even in this case, it is possible to obtain an acoustic vibration detection device excellent in front
and rear bi-directionality in a high frequency region.
[0037]
Further, the third openings 13 may be provided at corner portions on both sides of the acoustic
vibration detection device. Furthermore, the third openings 14, 14 may be provided closer to the
side surface rather than the corner portions on both sides of the acoustic vibration detection
device. Further, the second opening 11 may be provided not behind the housing 1 but behind the
housing 1.
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[0038]
Also, although the first opening 10 of the acoustic vibration detection device is directed in the
direction of the desired sound source, the size of the fourth opening 12 is adjusted when the
sound source is not in front of the acoustic vibration detection device Thus, it is possible to give
an elevation angle on sensitivity and to set an optimum sensitivity characteristic.
[0039]
The present invention can be used as a microphone excellent in bidirectionality.
[0040]
1 is an external perspective view of an acoustic vibration detection device according to an
embodiment of the present invention.
It is sectional drawing cut longitudinally from the top of the acoustic vibration detection
apparatus of FIG.
It is XX sectional drawing of FIG. It is the YY sectional view taken on the line of FIG. It is a figure
which shows the state which turned over the upper cover of the acoustic vibration detection
apparatus of FIG. It is a figure which shows the azimuth ¦ direction sensitivity characteristic in
360 degrees of acoustic vibration detection apparatuses of FIG. It is a figure which shows the
azimuth ¦ direction sensitivity characteristic in 360 degrees around the acoustic vibration
detection apparatus of FIG. 1 in the state which closed the 4th opening part. It is a figure which
shows the azimuth ¦ direction sensitivity characteristic in 360 degrees of the conventional
acoustic vibration detection apparatus which has only the 1st opening part and 2nd opening part
in the acoustic vibration detection apparatus of FIG. It is a figure which shows the frequency
characteristic in the front (direction of 0 degree), the left side (direction of 90 degrees), and right
side (direction of 270 degrees) of the acoustic vibration detection apparatus of FIG. The figure
which shows the frequency characteristic in the front (direction of 0 °), the left side (direction of
90 °) and the right side (direction of 270 °) of the acoustic vibration detection apparatus of
FIG. 1 in the state of closing the fourth opening. is there. The front (0 ° direction), left side (90
° direction) and right side (right direction) of the conventional acoustic vibration detection
device having only the first opening and the second opening in the acoustic vibration detection
device of FIG. Is a diagram showing frequency characteristics in the direction of 270 °). It is a
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figure which shows the perpendicular ¦ vertical direction sensitivity characteristic in the surface
of the upper half of the slope including the front of the acoustic vibration detection apparatus of
FIG. It is a figure which shows the perpendicular ¦ vertical direction sensitivity characteristic in
the surface of the upper half of the slope including the front of the acoustic vibration detection
apparatus of FIG. 1 in the state which closed the 4th opening part. It is a figure which is a
conventional acoustic vibration detection apparatus, Comprising: The apparatus of the structure
which opened the front detection hole and the rear detection hole in the front and the back of the
housing which encloses a microphone unit, respectively. It is a figure which is a conventional
acoustic vibration detection apparatus, Comprising: The apparatus of the structure which opened
the front detection hole and the rear detection hole in the front and the back in the upper surface
of the housing surrounding a microphone unit, respectively.
Explanation of sign
[0041]
Reference Signs List 1 housing 4 microphone unit 4a diaphragm 10 first opening 11 second
opening 12 fourth opening 13 third opening 14 third opening
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