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JP2009135572

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DESCRIPTION JP2009135572
An object of the present invention is to provide a dynamic microphone which does not
deteriorate the middle to low frequency response even when the directivity is switched from
unidirectionality to omnidirectionality. A support portion 16 provided in a unit case 12
communicates with an air chamber M side secured in the unit case 12, and a space portion 21
secured between a signal conversion means 32 and the unit case 12. Through hole 19 which also
communicates with the side sound hole 15 through the passage hole 19. The through hole 19
and the side sound hole 15 are provided with passage switching means 25 for closing the other
when the one is opened, When the partial sound hole 15 is open, the first sound passage 30 for
obtaining unidirectionality with the diaphragm 33 side constituting the signal conversion means
32 through the space portion 21 side is a through hole. When 19 is open, the second sound
passage 31 for acquiring nondirectionality can be secured between the diaphragm 33 side and
the air chamber M side via the space portion 21 side. [Selected figure] Figure 1
ダイナミックマイクロホン
[0001]
The present invention is a technique relating to a dynamic microphone that can switch the
directivity separately from unidirectionality and nondirectionality.
[0002]
The dynamic microphone is considered to be relatively easy to be unidirectional since it is easy to
provide a side sound hole for introducing a bi-directional component on the side of the unit case.
03-05-2019
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Also, the dynamic microphone can switch the directivity between unidirectionality and
nondirectionality by enabling the side sound holes to be opened and closed.
[0003]
In Patent Document 1 below, by opening and closing the side sound hole of the unit case with an
adjustment ring rotatably disposed on the outer periphery of the unit case, the directivity thereof
can be made unidirectional and non-directional. A dynamic microphone is shown which can be
switched. JP, 2000-295687, A
[0004]
On the other hand, as another example of the conventional type of dynamic microphone capable
of switching directivity between unidirectionality and nondirectionality, there is also a structure
shown in FIG. That is, according to the whole longitudinal cross-sectional view in the state where
the side sound hole shown in FIG. 3A is opened and the main part longitudinal cross-sectional
view in the state where the side sound hole shown in FIG. 1, a bottomed cylindrical unit case 2
having an opening 2a secured via a support 3 formed by increasing the thickness on the inner
peripheral surface, and the received sound wave as an electric signal Protection that covers the
opening 2a of the unit case 2 with the signal conversion means 5 disposed in the unit case 2
through the support portion 3 for conversion and the front sound hole 9a for introducing the
nondirectional component And a cap 9.
[0005]
In this case, the signal conversion means 5 is composed of a diaphragm 6 stretched so as to
cover the opening 2 a side and a magnetic generation circuit 7. The magnetism generating circuit
7 is magnetically connected to the permanent magnet 7a, the pole piece 7b provided on one pole
side of the permanent magnet 7a, and the other pole side of the permanent magnet 7a via a cupshaped yoke 7c. And the ring-shaped yoke 7d.
[0006]
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The ring-shaped yoke 7d is disposed around the pole piece 7b so as to form a magnetic gap G of
uniform width with the pole piece 7b, and is attached to the diaphragm 6 in the magnetic gap G.
The voice coil 6a is disposed so as to be able to vibrate.
[0007]
Therefore, an air chamber M is secured in the unit case 2 between the signal conversion means 5
supported via the support portion 3 and the bottom portion 2 b.
[0008]
Moreover, in the unit case 2, the side sound hole 4 a not communicating with the air chamber M
is provided in the peripheral wall portion 4 in order to introduce the bidirectional component,
and the side sound hole 4 a It is in communication with the diaphragm 6 side.
[0009]
On the other hand, the back side of the diaphragm 6 communicates with the air chamber M via
the magnetic gap G and the through hole 7e provided in the cup-like yoke 7c.
The through holes 7e are covered with an acoustic resistance material R made of a breathable
material such as felt.
[0010]
For this reason, according to the dynamic microphone 1 shown in FIG. 3, as shown in (a), the
bidirectional component introduced into the space portion 8 through the side sound hole 4a and
the front sound hole 9a As a result of being able to combine the nondirectional component
introduced via the interface, the directivity can be made unidirectional.
[0011]
Further, as shown in FIG. 3B, when the side sound hole 4a is closed with a non-air-permeable
material N such as an adhesive tape made of cellophane, for example, the bi-directional
component is no longer introduced, resulting in its directivity It will also be possible to make the
sex omnidirectional.
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In this case, the sound passage that exhibits unidirectionality is present as a space 8 having only
an acoustic capacity when the side sound hole 4a is closed.
[0012]
For this reason, according to the dynamic microphone 1 shown in FIG. 3, by opening and closing
the side sound holes 4a, the directivity can be switched to unidirectionality and nondirectionality
and used.
[0013]
FIG. 4 is an equivalent circuit diagram showing the acoustic system element of the dynamic
microphone 1 shown in FIG. 3 corresponding to each element of the electric circuit.
In the figure, m0 represents the mass of the diaphragm 6, s0 represents the stiffness of the
diaphragm 6, r1 represents the acoustic resistance of the acoustic resistance material R provided
in the air chamber M, and s1 represents the acoustic stiffness of the air chamber M. m1
represents the acoustic mass of the side sound hole 4a, s2 represents the acoustic stiffness
generated in the space 8 when the side sound hole 4a is closed, and P1 represents the sound of
the front sound hole 9a P2 indicates the pressure and the sound pressure on the side sound hole
4a.
Further, T located at the broken line surrounding portion is shown as a switching element for
opening and closing the side sound hole 4a.
[0014]
According to the figure, when the switching element T is connected to m1, that is, when the side
sound hole 4a is opened, the space 8 is interposed between the side sound hole 4a and the
diaphragm 6. A sound passage is formed, and it turns out that it becomes a dynamic microphone
1 of unidirectionality.
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In addition, when the switching element T is connected to the s2 side, that is, when the side
sound hole 4a is closed, it becomes clear that the dynamic microphone 1 becomes
nondirectional.
[0015]
By the way, according to the dynamic microphone 1 shown in FIG. 3, since the mass control is
performed when the directivity is unidirectivity, an acoustic mass (m1) defined by the diameter
dimension of the side sound hole 4a Can make the frequency response flat. In this case, as
apparent from FIG. 4, in the dynamic microphone 1, the acoustic mass (m1) of the side sound
hole 4a and the acoustic stiffness (s1) of the air chamber M form a resonant circuit. Therefore,
the acoustic resistance (r1) of a predetermined resistance value is disposed to be able to damp
resonance.
[0016]
On the other hand, when the directivity is non-directional, the frequency response can be made
flat by adjusting the acoustic resistance value because it is resistance control. However, when the
directivity is switched from unidirectionality to nondirectionality, the resistance value of the
acoustic resistance (r1) for resonance damping is too high. Moreover, the dynamic microphone 1
is not configured to be able to adjust the resistance value, and can be switched from
unidirectionality to nondirectionality without being able to adjust the resistance value, so that the
frequency response in the middle to low range is degraded. There is a disadvantage that it is used
as it is.
[0017]
In addition, the dynamic microphone 1 shown in FIG. 3 has to open and close the side sound
holes 4a by complicated manual work each time, and there is also a problem that the directivity
switching operation can not be performed quickly.
[0018]
SUMMARY OF THE INVENTION In view of the above problems of the prior art, the present
invention can quickly switch between unidirectionality and omnidirectionality as desired, and can
be directed from unidirectionality to omnidirectionality. It is an object of the present invention to
provide a dynamic microphone capable of avoiding deterioration of the frequency response of
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middle to low frequency while eliminating the need to adjust the acoustic resistance value at the
time of switching the polarity.
[0019]
The present invention has been made to achieve the above object, and is provided with a
bottomed cylindrical unit case having an opening partitioned by a support portion projecting
from a peripheral wall portion to the inside, and a bottom portion of the unit case. The opening
of the unit case having signal conversion means disposed in the unit case via the support while
securing an air chamber between the side and the front sound hole for introducing a
nondirectional component Communicating with the diaphragm side constituting the signal
conversion means via a space portion and a gap portion secured between the magnetism
generation circuit constituting the signal conversion means and the unit case In the dynamic
microphone, a side sound hole having a positional relationship not in communication with the air
chamber is provided in the peripheral wall portion of the unit case, the support portion includes
the air chamber And a through hole communicating with the side sound hole through the space
portion, the through hole and the side sound hole being a passage that closes the other when one
is opened. A switching means is provided, and when the side sound hole is open, a first sound
passage is opened between the space side and the diaphragm side via the space portion, and
when the through hole is open, the space portion The second main feature is that the second
sound passage can be secured between the diaphragm side and the air chamber side via the air
gap and the air gap.
[0020]
In this case, the sound passage communicating with the air chamber provided in the cup-shaped
yoke constituting the magnetism generation circuit is connected to the air passage
communicating with the air chamber provided with the first acoustic resistance material in the
support portion. It is preferable to have a second acoustic resistance material.
[0021]
According to the present invention, since the first sound path for functioning as unidirectionality
and the second sound path for functioning as omnidirectionality are formed switchably via the
path switching means, It is possible to exhibit directional characteristics according to the desire.
[0022]
Moreover, when switching to nondirectionality, the second sound passage is secured, and
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communication can be made via the two paths between the opening side and the air chamber.
The resistance value can be lowered by applying and connecting in parallel, and the deterioration
of the frequency response in the middle to low range can be avoided.
Also, the directivity can be switched with one touch through the passage switching means.
[0023]
FIG. 1 is an explanatory view showing an example of the present invention, in which (a) is a
longitudinal cross-sectional view when the first sound passage is secured by opening the side
sound hole, and (b) is The principal part longitudinal cross-sectional view at the time of closing a
side sound hole and ensuring a 2nd sound passage is each shown.
[0024]
According to the figure, the dynamic microphone 11 has a bottomed cylindrical unit case 12
having an opening 13 partitioned by a support portion 15 projecting from the peripheral wall 14
to the inside, and a bottom portion of the unit case 12 20 with the signal conversion means 32
disposed in the unit case 12 via the support portion 16 while securing the air chamber M
between the two and the front sound hole 43 for introducing the nondirectional component At
least a protective cap 42 covering the opening 13 of the case 12 is formed.
[0025]
Among them, the support portion 16 provided on the side of the opening 13 of the unit case 12
is a stepped shelf 17 formed over substantially the entire circumference of the inner peripheral
surface 14 a of the peripheral wall 14; And a bent shelf plate portion 18 having a substantially L
shape with a horizontal piece portion 18a provided at the remaining inner circumferential
portion and an upright piece portion 18b.
For this reason, in the unit case 12, a space 21 communicating with the opening 13 is secured
between the peripheral wall 14 and the bent shelf plate 18.
[0026]
The signal conversion means 32 is supported on the side of the support portion 16 via the
stepped shelf portion 17 and the upright piece 18b of the bent shelf portion 18, and at that time,
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it is substantially between the bottom portion 20 side of the unit case 12 An air chamber M
having a convex shape can be secured.
[0027]
In addition, a through hole 19 is formed in the horizontal piece portion 18 a of the bent shelf
plate portion 18, and the air chamber M communicates with the space portion 21 through the
through hole 19.
The through hole 19 is covered from the air chamber M side by a second acoustic resistance
material R2 made of a breathable material such as felt.
[0028]
Further, the unit case 12 is provided on the peripheral wall portion 14 which is in a positional
relationship opposed to the upright piece 18b of the bent shelf plate portion 18, and is used as
an extra space for raising and lowering the passage switching means 25 described later. An
opening 22 and a side sound hole 15 provided in the peripheral wall 14 above the side opening
22 without being directly connected to the air chamber M and introducing a bidirectional
component are provided.
[0029]
A passage switching means 25 for switchably securing a first sound passage 30 and a second
sound passage 31 which will be described later in the unit case 12 is a cylinder freely disposed in
sliding contact with the outer peripheral surface 12 a of the unit case 12. It comprises the main
body portion 26 and an open / close operating portion 27 which is introduced into the space
portion 21 from the side of the inner peripheral surface 26 a of the cylindrical main body portion
26 through the side opening 22.
[0030]
In this case, when the open / close operation unit 27 closes the through hole 19 of the horizontal
piece 18a, the cylindrical main unit 26 and the open / close operation unit 27 in the passage
switching means 25 are side sound holes. When the cylindrical main body 26 closes the side
sound hole 15, the opening / closing operation part 27 is formed under the positional
relationship of opening the through hole 19 of the horizontal piece 18a.
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[0031]
That is, as shown in FIG. 1A, when the open / close operation unit 27 abuts on the horizontal
piece 18a, the passage switching means 25 opens the side sound hole 15 and the passage
switching means 25 opens. When the hole 19 is closed and the cylindrical main body portion 26
is pulled up as shown in FIG. 1B and the open / close operation portion 27 abuts on the upper
opening edge 22a partitioning the side opening 22, The unit case 12 is disposed in sliding
contact with the unit case 12 so that the through hole 19 is opened when the hole 15 is closed.
[0032]
On the other hand, the signal conversion means 32 for converting the received sound wave into
an electric signal is constituted by a diaphragm 33 stretched so as to cover the opening 13 side
and a magnetic generation circuit 35.
[0033]
In this case, the magnetism generating circuit 35 is magnetically connected to the permanent
magnet 36, the pole piece 37 provided on one pole side of the permanent magnet 36, and the
cuplike yoke 38 on the other pole side of the permanent magnet 36. And a ring-shaped yoke 39
connected thereto.
A sound through hole 38a is formed on the side of the cup-like yoke 38 facing the air chamber
M, and the sound through hole 38a is a first air-permeable material similar to the second
acoustic resistance material R2. It is covered from the air chamber M side by acoustic resistance
material R1.
[0034]
The ring-shaped yoke 39 is disposed around the pole piece 37 so as to form a magnetic gap G
having a uniform width with the pole piece 37, and is attached to the diaphragm 33 in the
magnetic gap G. The voice coil 34 is disposed so as to be able to vibrate.
[0035]
Moreover, the magnetism generating circuit 35 places most of the lower surface side of the cup-
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shaped yoke 38 constituting this on the step-like shelf 17 in the support 16, and the rest is the
upright piece in the bent shelf plate 18 It is disposed in the unit case 12 by being placed on the
surface 18 b.
Therefore, a gap 29 communicating with the space 21 can be secured between the cup-shaped
yoke 38 and the peripheral wall 14 of the portion placed on the upright piece 18b.
[0036]
Next, the operation and effect of the present invention having the above configuration will be
described below based on FIG.
That is, as shown by the downward arrow direction in FIG. 1A, the tubular main body portion 26
in the passage switching means 25 is pulled downward and the opening / closing operation
portion 27 is brought into contact with the horizontal piece 18a in the bending shelf 18 At the
time of contact, the through hole 19 of the horizontal piece portion 18a is closed by the opening
and closing operation portion 27 and the side sound hole 15 on the unit case 12 side closed by
the cylindrical main body portion 26 is It is released.
Therefore, a first sound passage 30 composed of the space 21 and the air gap 29 is formed
between the side sound hole 15 and the diaphragm 33.
[0037]
As a result, the microphone unit 11 introduces a bidirectional component through the first sound
passage 30 secured between the side sound hole 15 and the diaphragm 33 and then introduces
it through the front sound hole 43. By combining with the nondirectional component to be
obtained, unidirectionality is obtained.
[0038]
Further, as shown by the upward arrow direction in FIG. 1B, when the tubular main body portion
26 is pulled upward and the opening / closing operation portion 27 is brought into contact with
the upper opening edge 22a of the side opening 22, The through hole 19 closed by the opening
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and closing operation unit 27 is opened, and the side sound hole 15 is closed by the cylindrical
main body 26.
Therefore, a second sound passage 31 composed of the space 21 and the air gap 29 is formed
between the through hole 19 and the diaphragm 33.
[0039]
As a result, the microphone unit 11 can not introduce the bidirectional component from the side
sound hole 15 and acquires nondirectionality.
[0040]
Moreover, the non-directional component introduced from the front sound hole 43 side passes a
path from the magnetic gap G to the air chamber M through the communication hole 38 a of the
cup-shaped yoke 38 and the through hole 19 from the second sound passage 31. While passing
through the two paths to the air chamber M, the first acoustic resistance material R1 and the
second acoustic resistance material R2 are separately passed.
[0041]
FIG. 2 is an equivalent circuit diagram showing the acoustic elements of the microphone unit 11
corresponding to the elements of the electric circuit, and the effect will be described in more
detail with reference to this figure.
[0042]
Incidentally, in FIG. 2, m0 is the mass of the diaphragm 33, s0 is the stiffness of the diaphragm
33, r1 is the acoustic resistance of the first acoustic resistance material R1, r2 is the acoustic
resistance of the second acoustic resistance material R2, and s1 is The acoustic stiffness of the
air chamber M, m1 indicates the acoustic mass of the side sound hole 15, P1 indicates the sound
pressure on the front sound hole 43 side, and P2 indicates the sound pressure on the side sound
hole 15 side.
Further, a broken line surrounding portion is a portion shown by replacing the operation of the
passage switching means 25 with a switch.
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[0043]
The state in which the switch shown in FIG. 2 is connected to the acoustic stiffness m1 side of the
air chamber M corresponds to the state in FIG. 1A in which the first sound passage 30 is formed
by opening the side sound hole 15. This indicates that the microphone unit 11 is unidirectional.
In this case, the resonance can be damped by arranging the resistance r1 between the acoustic
mass m1 of the side sound hole 15 and the acoustic stiffness s1 of the air chamber M which is an
element for generating the resonance.
[0044]
On the other hand, when the switch is connected to the acoustic resistance r2 side of the second
acoustic resistance material R2 on the opposite side to FIG. 2, the side sound hole 15 is closed
and the second sound passage 31 is secured The microphone unit 11 acquires non-directionality.
In this case, as a result of the acoustic resistance r1 of the first acoustic resistance material R1
and the acoustic resistance r2 of the second acoustic resistance material R2 being connected in
parallel in all stages of the acoustic stiffness s1 of the air chamber M, the overall resistance value
is It will be possible to lower it.
[0045]
Therefore, according to the present invention, when the microphone unit 11 is switched from
unidirectionality to nondirectionality, a resistance value lower than that of the conventional
example shown in FIG. 3 and FIG. 4 can be realized. It is possible to avoid the deterioration of the
middle to low frequency characteristics without adjusting the value.
[0046]
As described above, the microphone unit 11 according to the present invention operates unidirectionally by the first sound passage 30 by merely switching the first sound passage 30 and
the second sound passage 31 by operating the passage switching means 25. The second sound
passage 31 can obtain nondirectionality.
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[0047]
Furthermore, when the second sound passage 31 is formed, the nondirectional component can
be made to reach the air chamber M side through the two routes including the second sound
passage 31, so these two routes are exceptional. 1st acoustic resistance material R1 and 2nd
acoustic resistance material R2 with which it is equipped are connected in parallel.
For this reason, the microphone unit 11 can lower the acoustic resistance value between the
diaphragm 33 and the air chamber M when acquiring nondirectionality, so that it is possible to
avoid the deterioration of the frequency response in the middle to low range. .
[0048]
Moreover, in the present invention, the directivity can be switched quickly by one-touch
operation by simply moving the passage switching means 25 up and down while holding the
microphone unit 11, thus exhibiting excellent operability. It can be done.
Moreover, since the passage switching means 25 can switch the first sound passage 29 and the
second sound passage 31 while maintaining excellent airtightness, sensitivity and S / N ratio can
be increased. Unidirectionality and nondirectionality can be obtained for the microphone unit 11
without deterioration.
[0049]
The above has described the present invention based on the illustrated examples, and the specific
configuration thereof is not limited to this.
For example, by aligning the positions of the side sound hole 15 on the unit case 12 side, the side
opening 22 and the through hole 19 with the position of the opening / closing operation unit 27
on the passage switching means 25 side, It is also possible to switch between the one sound
passage 30 and the second sound passage 31.
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[0050]
It is an explanatory view showing an example of the present invention, and (a) is a longitudinal
section figure when opening a side sound hole and securing a 1st sound passage among them,
(b), a side sound hole Is a longitudinal cross-sectional view of the main part when securing the
second sound passage.
The equivalent circuit schematic which makes the acoustic type element of this invention
respond | correspond to each element of an electric circuit, and shows it.
It is explanatory drawing about a prior art example, The (a) of them is the whole longitudinal
section in the state where the side sound hole was opened, (b) is the principal part longitudinal
section in the state where the side sound hole was closed Each shows a plan view.
FIG. 4 is an equivalent circuit diagram showing the acoustic system element corresponding to
each element of the electric circuit in the conventional example shown in FIG. 3.
Explanation of sign
[0051]
11 dynamic microphone 12 unit case 12a outer peripheral surface 13 opening 14 peripheral
wall 14a inner peripheral surface 15 side sound hole 16 support 17 stepped shelf 18 bent shelf
plate 18a horizontal piece 18b upright piece 19 through hole 20 Bottom portion 21 space
portion 22 side opening portion 22a upper opening edge 25 passage switching means 26
cylindrical main body portion 26a inner circumferential surface 27 opening / closing operation
portion 29 air gap portion 30 first sound passage 31 second sound passage 32 signal conversion
means 33 diaphragm 34 voice Coil 35 Magnetic Generation Circuit 36 Permanent Magnet 37
Pole Piece 38 Cup Yoke 38a Sound Through Hole 39 Ring Yoke 42 Protective Case 43 Front
Sound Hole M Air Chamber R1 First Acoustic Resistance Material R2 Second Acoustic Resistance
Material
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