JPH04170200

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DESCRIPTION JPH04170200
[0001]
FIELD OF THE INVENTION The present invention relates to a directional dynamic microphone
unit whose main application is vocal and speech amplification. 2. Related Art Conventionally,
directional microphones are often used to enhance the sound emitted from a specific person,
such as vocals and speech. FIG. 3 is a side sectional view showing the internal structure of a
conventional conventional directional dynamic microphone unit. In FIG. 3, the symbol {circle over
(1)} was attached to the diaphragm, and 2 was affixed to the diaphragm 1. An annular voice coil
3 is a magnetic yoke to which the diaphragm 1 is fixed on the upper surface, 4 is a magnet
disposed in the magnetic yoke 3 so as to face the inner peripheral side of the voice coil 2, 5 is An
internal air chamber 6 formed between the magnetic yoke 3 and the magnet 4 is disposed on the
upper surface of the magnetic yoke so as to face the upper side of the diaphragm 1 to buffer air
vibration outside the diaphragm 1. Is an equalizer for Further, 7 is a space formed between the
diaphragm 1 and the magnetic yoke 3, and the diaphragm inner surface air chamber
communicating with the internal air chamber 5, 8 is between the magnetic yoke 3 and the
equalizer 6. A phase circuit acoustic terminal 9 disposed on the front side is an acoustic
resistance material attached to the phase circuit acoustic terminal 8. Further, 10 is a microphone
body case for holding the magnetic yoke 3, 11 is a rear air chamber formed by the magnetic
yoke 3 and the microphone body case 10, and directivity is provided at the bottom of the
magnetic yoke 3. It communicates with the internal air chamber 5, the diaphragm inner surface
air chamber 7, and the phase circuit acoustic terminal 8 through the through holes 3a for
increasing the frequency. The magnetic yoke 3, the equalizer 6, and the microphone body case
10 form a microphone unit housing A. Next, the operation of the conventional directional
dynamic microphone unit according to the above configuration will be described. In FIG. 3, when
air vibration occurs due to the voice emitted by the user, the vibration is attenuated by the
equalizer 6 to vibrate the diaphragm 1. When the diaphragm 1 vibrates, air vibration is
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generated in the internal air chamber 5 and the diaphragm inner surface air chamber 7
accordingly. For this reason, air vibrations in the internal air chamber 5 and the air chamber 7
inside the diaphragm inner surface caused by the vibration of the diaphragm 1 act on the
diaphragm l as an equivalent mass, and the resonance frequency fo of the diaphragm 1 can be
obtained. It contributes to the decision. Thus, the resonant frequency [0 and Q (quality factor) at
the resonant frequency fn of the directional dynamic microphone according to the above
configuration are the mass of the voice coil 2 attached to the diaphragm 1, the vibration The
equivalent mass of the inner surface air chamber 7 of the inner surface side, the equivalent
quality 11 of the inner air chamber 5 formed by the magnetic yoke 3 and the magnet 4, and the
equivalent mass of the rear air chamber 11 formed inside the microphone body case 10 It is
determined by
SUMMARY OF THE INVENTION In the above-described conventional directional dynamic
microphone, as a means for reducing the stiffness of the diaphragm l in order to realize a wide
band of the output frequency characteristic, it is necessary to reduce the thickness of the
diaphragm 1 or There is a method of increasing the mass of the voice coil 2 or increasing the
equivalent mass of the internal air chamber 5 and the rear air chamber 11. However, if the
thickness of the diaphragm 1 is reduced, the diaphragm l itself becomes unstable, and if the mass
of the voice coil 2 is increased, the output sensitivity is reduced. In order to reduce the stiffness,
it is considered preferable to increase the equivalent mass of the inner air chamber 5 and the
rear air chamber 11. However, in order to increase the equivalent mass of the internal air
chamber 5 and the rear air chamber 11, the shapes of the magnetic yoke 3, the magnet 4 and the
microphone body case 10 which form these must be enlarged, There is a problem that it
contradicts the needs of general users. The present invention is intended to solve the abovementioned problems, and to reduce the stiffness of the diaphragm without increasing the size of
the microphone, and to realize a wide band of output frequency characteristics while maintaining
high output sensitivity. It is an object of the present invention to provide a directional dynamic
microphone unit capable of Means for Solving the Problems In order to achieve the above object,
according to the present invention, a diaphragm is covered on an open surface of a cylindrical
magnetic yoke forming a microphone unit housing, and the above-mentioned magnet on which
the diaphragm is covered. While covering the equalizer on the open surface of the yoke, at least
an opening for communicating the internal air chamber formed by the diaphragm and the
magnetic yoke provided on the side surface of the open portion of the magnetic yoke to the
outside of the microphone unit housing A directional dynamic microphone unit in which an
acoustic resistance material covering the opening is adhered, wherein the acoustic resistance
material is formed with a small hole communicating the outside of the microphone unit housing
with the internal air chamber. . Therefore, according to the present invention, the equivalent
mass of the internal air chamber can be increased by the equivalent mass of the small hole
portion, and therefore, the stiffness of the diaphragm can be reduced without increasing the size
of the microphone, thereby achieving high efficiency. A wide band of output frequency
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characteristics can be realized while maintaining the output sensitivity. EXAMPLES Examples of
the present invention will be described below based on the drawings. FIG. 1 is an enlarged side
sectional view showing the main part structure of a directional dynamic microphone unit
according to one embodiment of the present invention.
In FIG. 1, the same components as those of the conventional directional dynamic microphone
unit of FIG. 3 are designated by the same reference numerals as those of FIG. 3, and the
description thereof will be omitted. In FIG. 1, 9a is a small hole drilled in the acoustic resistance
material 9 attached to the phase circuit acoustic terminal 8, and the diameter of the small hole 9a
is in the end face of the small hole 9a. The flange portion 9b is formed in the direction of the
diaphragm inner surface air chamber 7 so that the protrusion length is longer than the
dimension. Next, the operation of the directional dynamic microphone unit of the present
embodiment having the above configuration will be described. In FIG. 1, when air vibration
occurs due to the voice emitted by the user, the vibration is attenuated by the equalizer 6 to
vibrate the diaphragm l. When the diaphragm 1 vibrates, air vibration is generated in the internal
air chamber 5 and the diaphragm inner surface air chamber 7 accordingly. On the other hand, air
vibration around the directional dynamic microphone unit generated by the voice emitted by the
user is also propagated to the periphery of the acoustic resistance material 9, whereby the small
hole 9a and the flange portion of the small hole 9a In 9b, a space having an equivalent mass
exceeding the equivalent mass in the internal air chamber 5 and the diaphragm inner surface air
chamber 7 is generated. Through the inner air chamber 5 and the inner surface of the diaphragm
inner air chamber 7. For this reason, the equivalent mass in the internal air chamber 5 and the
diaphragm internal air chamber 7 is increased by the equivalent mass of the small hole 9 a of the
acoustic resistance material 9 and the flange portion 9 b of the small hole 9 a. The resonant
frequency io is lowered to increase the Q at the resonant frequency [o. Then, the stiffness of the
diaphragm 1 is reduced, and the broadening of the output frequency characteristics of the
present dynamic microphone unit 7-7 is realized. This will be described with reference to FIG. 2
showing the output frequency characteristics of the directional dynamic microphone unit
according to the conventional configuration and the output frequency characteristics of the
directional dynamic microphone unit of the present embodiment. In FIG. 2, reference numeral 21
denotes an output frequency characteristic of the directional dynamic microphone unit according
to the conventional configuration, and reference numeral 22 denotes an output frequency
characteristic of the directional dynamic microphone unit of the present embodiment. In
particular, the frequency characteristics in the middle to low range are improved compared to
the case of In the present embodiment, although the flange portion 9b is provided in the small
hole 9a of the acoustic resistance material 9, the small hole 9a without the flange portion 9b may
simply be formed. In the present embodiment, although the flange portion 9b is formed in the
direction of the diaphragm inner surface air chamber 7 direction, the flange portion 9b is formed
outward of the directivity dynamic microphone unit. It may be
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As described above, according to the present invention, the diaphragm is covered on the open
surface of the sieve-like magnetic yoke forming the microphone unit housing, and the diaphragm
is mounted on the open surface of the magnetic yoke covered. An acoustic wave covering at least
this opening is provided in an opening for connecting an internal air chamber formed by the
diaphragm and the magnetic yoke, provided on the side surface of the open portion of the
magnetic yoke, to the outside of the microphone unit housing. It is a directional dynamic
microphone unit made by sticking a resistance material, and the above-mentioned sound
resistance material is made to form a small hole which makes the outside of a microphone unit
housing and an internal air room connect. For this reason, the equivalent mass of the internal air
chamber can be increased by the equivalent mass of the small hole portion, and therefore the
stiffness of the diaphragm is reduced without increasing the shape of the microphone, and high
output sensitivity is maintained. It is possible to realize wide band of output frequency
characteristics as it is.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is an enlarged side sectional view showing the structure of the main part of a directional
dynamic microphone unit according to an embodiment of the present invention, and FIG. 2 is an
output frequency characteristic of the directional dynamic microphone unit according to the
prior art. FIG. 3 is a side sectional view showing an internal structure of a conventional
directional dynamic microphone unit.
DESCRIPTION OF SYMBOLS 1 ... Diaphragm, 3 ... Magnetic yoke, 5 ... Internal air chamber, 6 ...
Equalizer, 9 ... Sound resistance material, 9a ... Small hole, A ... Microphone unit housing .
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