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JP2008042543

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DESCRIPTION JP2008042543
An object of the present invention is to provide a variable pointing type narrow pointing device
capable of changing a pointing angle of sound collection as desired by covering an acoustic
resistor whose sound resistance value can be freely adjusted in an acoustic resistance hole. Of
the sex microphones. SOLUTION: An acoustic resistor 32 formed of an elastic material 33 and a
hard thin plate 34 disposed on the surface is covered in an acoustic resistance hole 23 provided
in the longitudinal direction of the acoustic tube 22, and the hard thin plate 34 is covered. By
compressing and adjusting the elastic member 33 by pressing the elastic member 33, the
acoustic resistance value of the acoustic resistor 32 can be variably adjusted. As a result, the
directivity angle can be narrowed by strong compression to the acoustic resistor 32, and the
compression can be weakened to widen the directivity angle. [Selected figure] Figure 1
Narrow directional microphone
[0001]
The present invention relates to a variable directional narrow directional microphone so that the
directivity angle of sound collection can be changed by making the acoustic resistance value of
the acoustic resistance hole provided in the acoustic tube variable.
[0002]
A narrow directional microphone formed by housing a unidirectional microphone unit at one end
of an acoustic tube is not only easy to flatten the frequency response, but also excellent in
sensitivity and intrinsic noise characteristics. It is often used for collecting sound of professional
video cameras and the like for which sound collection of quality is required.
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[0003]
FIG. 3 is an explanatory view showing a conventional example of a narrow directional
microphone, of which (a) shows a cross-sectional structure, and (b) shows a side view when
90.degree. Around an axis of (a). Show.
[0004]
According to the figure, the narrow directional microphone 1 conventionally includes at least a
microphone unit MU and an acoustic tube 2 accommodating the microphone unit MU on its base
end side. The acoustic tube 2 is a sound wave. It has a distal end opening 3, an acoustic
resistance hole 4, a rear opening 5 and a proximal end opening 6 as an entrance.
[0005]
In this case, the acoustic resistance holes 4 formed along the length direction of the acoustic tube
2 among the sound wave entrances are provided in a pair under the facing positional
relationship.
Further, a rear opening 5 formed along the circumferential direction on the base end side of the
acoustic tube 2 is similarly disposed opposite to the same.
[0006]
Furthermore, each of the acoustic resistance holes 4 is separately covered by an acoustic
resistance material 7 made of, for example, a non-woven fabric, laminated and attached to the
double-sided tape 8 adhered to the acoustic tube 2.
Further, the proximal end opening 5 is airtightly closed by a suitable closing member not shown,
and the sound wave incidence from the proximal end opening 5 is blocked.
[0007]
By the way, since the narrow directivity microphone 1 is generally designed to have directivity in
the middle to low frequency band as a hypercardioid, middle to low frequency noise from the
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rear (180 degrees) is picked up. There's a problem.
[0008]
On the other hand, the narrow directional microphone 1 is designed with the directivity of the
middle to low frequency as a cardioid in order to avoid such noise from the rear, noise of the
frequency band from the side (90 degrees) to the middle frequency It is said that there is a
problem of picking up sound.
[0009]
For this reason, it is required that the narrow directivity microphone 1 can variably adjust the
directivity in the middle to low range in accordance with the situation in which sound is
collected, and does not collect sound waves (noise) other than the sound source to be collected.
ing.
That is, in order to pick up sound in the middle to low range, it is required to realize variable
directivity.
[0010]
On the other hand, as a method of realizing variable directivity in the middle to low range in the
narrow directional microphone 1, a method of making the leakage resistance of the acoustic tube
2, that is, the acoustic resistance value of the acoustic resistance hole 4 variable, microphone unit
MU It is said that there is a method of making the internal acoustic resistance variable.
[0011]
However, making the acoustic resistance value inside the microphone unit MU variable directly
manipulates the acoustic conditions of the microphone unit MU, which is not necessarily
preferable.
Therefore, conventionally, as disclosed in Patent Document 1 below, a switching cover is
provided which can change the acoustic resistance value of the rear opening 5 of the acoustic
tube 2 in place of the acoustic resistance inside the microphone unit MU. By making the acoustic
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resistance value of the rear opening 5 variable, appropriate directivity according to the sound
collection situation was obtained.
Japanese Patent Laid-Open No. 2000-50385
[0012]
As described above, the conventional narrow directional microphone 1 is formed as disclosed in
Patent Document 1, so that the directivity can be switched to the hypercardioid or the cardioid
according to the sound collection situation. It has become possible to realize variable directivity
such that sound waves (noises) other than the sound source to be collected can be reduced.
[0013]
However, since the conventional narrow directional microphone 1 can not make the acoustic
resistance value of the acoustic resistance hole 4 variable, it adjusts the sound wave entering the
acoustic tube 2 through the acoustic resistance hole 4 from the sound source and directs it I
could not change my sex.
[0014]
For this reason, the conventional narrow directional microphone 1 can not change the directivity
angle of sound collection, and when it is fixed to a microphone stand etc., the timbre of the sound
source changes even with a slight movement of the sound source. There was a problem that I
would do it.
[0015]
In view of the above problems of the prior art, the present invention can change the directivity
angle of the sound collection as desired by covering the acoustic resistance body whose acoustic
resistance value can be freely adjusted in the acoustic resistance hole. It is an object of the
present invention to provide a variable directional narrow directional microphone.
[0016]
The present invention has been made to achieve the above object, and a microphone unit is
accommodated on the proximal end side of an acoustic tube having an acoustic resistance hole
formed along the length direction, and the acoustic resistance hole is provided with an acoustic
wave. In the narrow directional microphone in which a resistor is provided, the acoustic resistor
has ventilation and restoration so as to make its acoustic resistance variable according to the
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degree of pressing in the axial direction of the acoustic tube. The main feature is that it is at least
formed of an elastic material.
[0017]
In this case, the acoustic resistor is preferably formed by providing a hard thin plate on the
pressed surface side of the elastic material in order to stabilize the acoustic resistance value
obtained at the time of pressing, and the hard thin plate is preferably It is preferable to provide
and arrange | position the surface size which carries out the facing match with the said to-bepressed surface side in an elastic material.
[0018]
Moreover, a pair of said acoustic resistance hole can be formed in the said acoustic pipe | tube in
the opposing positional relationship, and the said acoustic resistance body can also be covered
separately with respect to each of these acoustic resistance holes.
[0019]
According to the present invention, since the acoustic resistance body made of an elastic material
having ventilation and restoration properties is covered in the acoustic resistance hole of the
acoustic tube, the elastic material is pressed in the axial direction of the acoustic tube. For
example, the acoustic resistance value can be generated and given to the acoustic resistor in
accordance with the degree of the pressure.
[0020]
In addition, when a hard thin plate is provided on the pressed surface of the elastic material, the
elastic material can be uniformly pressed through the hard thin plate, so that a constant acoustic
resistance value is generated in the acoustic resistor.・ Can be granted.
[0021]
Furthermore, in the case where the pair of the acoustic resistance holes are formed under the
facing positional relationship and the acoustic resistor is separately provided to each of the
acoustic resistance holes, each acoustic resistance hole is formed. Since the sound wave incident
on the sound pipe through the through hole can be adjusted weakly, it is possible to provide a
variable directional narrow directional microphone in which the directivity angle of the collected
sound is variable.
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[0022]
FIG. 1 is an explanatory view showing an example of the present invention, in which (a) shows a
longitudinal sectional structure, and (b) shows a side view when 90.degree. About an axis of (a). )
Shows cross-sectional views in the direction of arrows AA in (a).
[0023]
According to these figures, the narrow directional microphone 11 is formed to include at least a
microphone unit MU and an acoustic tube 22 accommodating the microphone unit MU on the
base end side.
[0024]
Among them, the acoustic tube 22 is provided with an acoustic resistance hole 23, a distal end
opening 24, a rear opening 25 and a proximal end opening 26 as a sound wave entrance.
Among these, the proximal end opening 26 is configured to be able to block sound wave
incidence by airtightly closing using a closing member not shown.
[0025]
Further, in the illustrated example, the acoustic resistance holes 23 formed along the longitudinal
direction of the acoustic tube 22 are provided as a pair based on the opposing positional
relationship.
In this case, each of the acoustic resistance holes 23 has an appropriate length and width so as to
have a designed acoustic resistance value and is separately formed in a slit shape.
Similarly, a rear opening 25 provided along the circumferential direction on the base end side of
the acoustic tube 22 is also disposed opposite to each other.
[0026]
Furthermore, each of the acoustic resistance holes 23 is a hard thin plate attached to the pressed
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surface 35 of the elastic member 33 having both air permeability and restorability, and the
elastic member 33 pressed in the axial center direction of the acoustic tube 22. And 34 are
separately covered by an acoustic resistor 32.
[0027]
Among them, as the elastic material 33, a sponge material (for example, HR50 manufactured by
Bridgestone Co., Ltd.) can be suitably used.
In this case, since the elastic material 33 is attached to the acoustic tube 22 by the adhesive, the
elastic material 33 is formed to be larger in size than the acoustic resistance hole 23, thereby
securing the application site of the adhesive. It will be done.
[0028]
Furthermore, since the elastic resistance value of the elastic member 33 is determined in
accordance with the degree of pressing, the range of the acoustic resistance value of the acoustic
resistor 32 is determined according to the change in thickness. Become.
[0029]
In addition, as the hard thin plate 34, a hard plastic or metal which is formed into a thin plate
shape with a rigidity that does not cause bending by pressing can be suitably used.
In this case, the hard thin plate 34 is formed to have a surface size which is matched with the
surface size of the pressure surface 35.
[0030]
Next, the operation and effects of the present invention will be described with reference to FIG. 1.
The narrow directional microphone 11 is provided to pick up a sound source with its tip opening
24 facing.
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In this case, for example, the narrow directional microphone 11 is gripped by the sound
collecting operator with a finger (for example, a thumb and a forefinger) attached to the hard
thin plate 34 in each of the acoustic resistors 32.
[0031]
At this time, the sound collection operator can adjust the degree of pressing on the elastic
member 33 while strongly pressing or loosening the hard thin plate 34 while holding the hard
thin plate 34 with substantially the same force.
[0032]
In particular, in the case where the hard thin plate 34 is provided with a surface size that
matches the surface size of the pressed surface 35, if the pressing point is appropriate, the
pressing force on the elastic member 33 is evenly distributed. The resistor 32 can be uniformly
compressed.
[0033]
Moreover, the sound wave from the sound source enters the acoustic tube 22 through a plurality
of surfaces located at portions excluding the surface of the acoustic resistor 32 in contact with
the acoustic tube 22 of the elastic member 33 and the surface on the hard thin plate 34 side. .
For this reason, the acoustic resistance value will become high by raising the grade of the press
to the elastic material 33, and reducing the air permeability of this elastic material 33. FIG.
[0034]
As described above, since the narrow directional microphone 11 can adjust the level of the
acoustic resistance value of the acoustic resistor 32 to adjust the sound wave passing through
the acoustic resistance hole 23, it changes the directivity angle of the collected sound. Can.
[0035]
FIG. 2 is a polar pattern diagram in which the degree of compression of the acoustic resistor 32
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is measured differently using an example of the present invention, in which (a) shows the one at
low compression and (b) shows the middle compression. (C) shows the time of high compression.
According to the drawing, it is clear that as the narrow directional microphone 11 intensifies the
degree of compression of the acoustic resistor 32, that is, as the acoustic resistance value
increases, the directivity angle (α) becomes narrower.
[0036]
Thus, the narrow directional microphone 11 according to the present invention sets the optimum
acoustic resistance value of the acoustic resistor 32 at which the directional angle is the
narrowest at the time of high compression, and adjusts the acoustic resistance value of the
acoustic resistor 32. By being free, it is possible to realize variable directivity in which the
directivity angle of sound collection is variable according to the sound collection situation.
[0037]
Since the narrow directional microphone 11 according to the present invention is formed in this
manner, when fixed to a microphone stand or the like, the directivity angle is narrowed by
strengthening the compression of the acoustic resistor 32 to increase the acoustic resistance
value. Also, even if the sound source moves, sound can be collected without changing the sound
quality by loosening the compression of the acoustic resistor 32 to lower the acoustic resistance
value and widening the directivity angle.
[0038]
In addition, the narrow directional microphone 11 according to the present invention narrows
the directivity (directional angle) at the time of telephoto (zoom) when attached to a video
camera etc. and widens the directivity (directional angle) at the wide angle. Can be adjusted to
provide an audio zoom effect linked to the lens.
[0039]
Although the present invention has been described based on the illustrated examples, the present
invention is not limited to the illustrated examples.
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For example, in the narrow directional microphone 11 according to the present invention, the
elastic member 33 is pressed via the hard thin plate 34 by the holder's fingertip or the like to
compress and adjust the acoustic resistor 32. The acoustic resistor 32 may be compressed and
adjusted via the pressing means.
In this case, the role of the hard thin plate 34 can be disposed on the side of the separate
pressing means.
The hard thin plate 34 is shown as a desirable mode having a surface size that is made to face
the pressed surface 35 of the elastic member 33, but if the pressing force on the elastic member
33 can be made uniform, The shape and the arrangement with respect to the pressed surface 35
can be freely determined.
[0040]
It is an explanatory view showing an example of the present invention, (a) of which is a
longitudinal sectional structure, (b) is a side view when (a) is rotated 90 ° around the axis, (c) is
Sectional drawing in the AA arrow direction of a) is shown, respectively.
It is a polar pattern figure which measured the compression degree of the acoustic resistor
according to the present invention, and (a) shows the one at low compression, (b) one at middle
compression, (c) Shows the one at high compression respectively.
It is explanatory drawing which shows the conventional narrow directivity microphone, (a) of
them shows a cross-sectional structure, (b) shows the side view at the time of rotating 90 degrees
around (a) about an axis, respectively.
Explanation of sign
[0041]
11 Narrow directional microphone 22 Acoustic tube 23 Acoustic resistance hole 24 Tip opening
25 Rear opening 26 Base end opening 32 Acoustic resistor 33 Elastic material 34 Hard thin plate
35 Pressed surface MU Microphone unit
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