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JP2008103876

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DESCRIPTION JP2008103876
An object of the present invention is to prevent a ribbon from coming in contact with magnetic
powder by capturing the magnetic powder before it reaches a microphone unit even if magnetic
powder intrudes from the outside, thereby making a gap formed in a head case large. Thus, a
ribbon-type microphone unit and a ribbon-type microphone capable of enhancing the high
frequency response of the microphone are obtained. SOLUTION: A plate surface is formed in a
parallel magnetic field formed between a pair of square-pole shaped parallel magnetic field
forming permanent magnets 2 and 4 and a parallel magnetic field forming permanent magnet 2
and 4 arranged parallel to each other at intervals. In the direction of the parallel magnetic field
and opposed to the parallel magnetic field formed between the ribbon-shaped diaphragm 5
disposed parallel to the parallel magnetic field forming permanent magnets 2 and 4 and the
parallel magnetic field forming permanent magnets 2 and 4. A pair of magnetic powder
attracting permanent magnets 10 and 11 are provided in parallel with each other and spaced
apart from the parallel magnetic field forming permanent magnets 2 and 4. [Selected figure]
Figure 1
Ribbon type microphone unit and ribbon type microphone
[0001]
The present invention relates to a ribbon-type microphone unit and a ribbon-type microphone,
and is particularly characterized in that it has a configuration capable of avoiding an adverse
effect of magnetic powder entering from the outside.
[0002]
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The ribbon microphone is formed by arranging a ribbon serving as a diaphragm and a conductor
in a parallel magnetic field formed between a pair of permanent magnets.
When the ribbon vibrates in response to the acoustic wave, an electric signal proportional to the
vibration velocity is output from both ends of the ribbon as the ribbon cuts the parallel magnetic
field. This is the principle of the ribbon microphone. The ribbon is made of, for example,
aluminum foil.
[0003]
6 to 8 show an example of a unit for converting sound waves into electrical signals in a
conventional ribbon microphone. 6 to 8, on the inner side surface of the frame 21 formed in a
rectangular frame shape, a pair of rectangular prism-shaped permanent magnets 22 and 24 are
provided on both sides in the long side direction of the frame 21. It is fixed at a predetermined
interval between them. The permanent magnets 22 and 24 are magnetized in the width direction
(the left and right direction in FIGS. 7 and 8), and the magnetization directions of the pair of
permanent magnets 22 and 24 are the same. Therefore, a parallel magnetic field is formed
between the permanent magnets 22 and 24.
[0004]
In the parallel magnetic field, a ribbon 25 which doubles as a diaphragm and a conductor is
disposed. The ribbon 25 has an elongated strip shape, and both ends in the lengthwise direction
are fixed to electrode lead portions 27 and 29 (see FIG. 8) provided at both ends in the
lengthwise direction of the frame 21. The electrode lead portions 27 and 29 are insulated from
the frame 21 and conduct to the ribbon 25 by sandwiching both ends of the ribbon 25 and hold
the ribbon 25 in a state where the ribbon 25 is given a suitable tension. . The ribbon 25 is
formed in a triangular wave shape by bending the portions other than the electrode lead portions
27 and 29 alternately at constant intervals (see FIG. 6). The direction of the line formed by the
bending, that is, the direction of the line drawn by the crests and valleys of the triangular wave is
the width direction of the ribbon 25, and the lines are formed at regular intervals.
[0005]
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The ribbon 25 receives the sound wave and vibrates in accordance with the sound wave. The
vibration direction is a direction crossing the magnetic flux between the permanent magnets 22
and 24, and the ribbon 25 made of a conductor generates electric power by crossing the
magnetic flux, and both ends of the ribbon 25 in the lengthwise direction, hence the electrode
lead portions 27 and 29. An electrical signal is generated between them. Since this electrical
signal becomes a signal of frequency and amplitude corresponding to the frequency and
amplitude of the ribbon 25, the acoustic wave striking the ribbon 25 is converted into an
electrical signal corresponding to the acoustic wave.
[0006]
As a conventional technique related to a ribbon microphone, for example, the diaphragm made of
a ribbon-like aluminum foil is made durable, and the diaphragm so that a good electrical
connection state can be obtained over a long period of time also at the joint portion with the
fixed electrode A ribbon type microphone is known in which a gold deposited film is formed on
each of the two surfaces of the substrate and on the inner surface of the electrode plate (see
Patent Document 1). JP, 2005-252440, A
[0007]
As described above, the ribbon microphone has a weak point that it is easily damaged by
magnetic powder such as iron powder which intrudes from the outside due to its unique
configuration. The reason is explained in more detail. Not only ribbon type microphones, but also
general microphones are made of a material in which a large number of gaps, such as metal
mesh and punching metal, are arranged in order to introduce external sound waves into the
microphone unit and shield the microphone unit inside. Some head cases surround the
microphone unit. Therefore, when fine magnetic powder such as iron powder floats in the air, the
magnetic powder passes through the gap of the head case and is adsorbed by the permanent
magnet constituting the ribbon microphone. FIG. 7 shows how the magnetic powder 30 is
adsorbed to the permanent magnets 22 and 24 in the prior art. Since the magnetic flux crossing
the air gap between the permanent magnets 22 and 24 is a parallel magnetic flux, the magnetic
powder adsorbed to one of the permanent magnets 22 and 24 stands up toward the other
permanent magnets 22 and 24 and is parallel to each other. Is adsorbed. Since the gap between
the permanent magnets 22 and 24 and the ribbon 25 is very small, when the magnetic powder
30 is adsorbed to the permanent magnets 22 and 24, the ribbon 25 hits the magnetic powder 30
and functions as a microphone or performance. Would be a major loss.
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[0008]
In order to solve such problems, it is conceivable to reduce the gap formed in the head case as
much as possible, but this causes the acoustic resistance of the head case to increase and the
problem that the frequency response of the high range of the microphone becomes worse. Will
occur.
[0009]
The present invention was conceived to solve the problems of the conventional ribbon
microphone as described above, and even if magnetic powder intrudes from the outside, the
magnetic powder is captured before reaching the microphone unit. As a result, the ribbon can be
prevented from coming into contact with the magnetic powder, thereby increasing the gap
formed in the head case to enhance the high frequency response of the microphone and maintain
the high frequency response. It is an object of the present invention to provide a ribbon
microphone unit and a ribbon microphone.
[0010]
The ribbon-type microphone unit according to the present invention includes a pair of squarepillar parallel magnetic field forming permanent magnets arranged in parallel with each other at
an interval and a parallel magnetic field formed between the pair of parallel magnetic field
forming permanent magnets. And a ribbon-shaped vibrating plate disposed with its plate surface
directed in the parallel magnetic field direction and separated from the pair of parallel magnetic
field forming permanent magnets, and a parallel magnetic field formed between the pair of
parallel magnetic field forming permanent magnets The main feature of the present invention is
to provide a pair of magnetic powder adsorbing permanent magnets which are arranged parallel
to each other and spaced apart from the pair of parallel magnetic field forming permanent
magnets.
The magnetic path formed by the magnetic powder adsorption permanent magnet may be an
open magnetic path.
The ribbon type microphone according to the present invention is characterized in that the
ribbon type microphone unit incorporated in the microphone case comprises the ribbon type
microphone unit according to the present invention.
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[0011]
The magnetic powder approaching the ribbon microphone unit is captured by the magnetic
powder adsorption permanent magnet before entering the gap between the pair of parallel
magnetic field forming permanent magnets and the ribbon diaphragm, and the magnetic powder
is ribbon diaphragm. Does not interfere with The magnetic path formed by the pair of parallel
magnetic field forming permanent magnets is a closed magnetic path, and the parallel magnetic
field of the pair of parallel magnetic field forming permanent magnets is a strong magnetic field,
and is hardly affected by the external magnetic field. The arrangement of the permanent magnet
for adsorption does not impair the performance of the microphone unit. Further, when the
magnetic path formed by the permanent magnet for magnetic powder adsorption is made an
open magnetic path, the influence of the magnetic field by the permanent magnet for magnetic
powder adsorption on the parallel magnetic field can be further reduced.
[0012]
Hereinafter, embodiments of a ribbon microphone unit and a ribbon microphone according to
the present invention will be described with reference to FIGS. 1 to 5. First, an embodiment of a
ribbon microphone unit according to the present invention will be described. In FIG. 1 to FIG. 3,
the ribbon microphone unit 20 is assembled based on the frame 1 formed in a rectangular frame
shape, and the inner side surface of the frame 1 The parallel magnetic field forming permanent
magnets 2 and 4 in the form of a square pole are fixed in parallel and opposite to each other at
predetermined intervals between the two parallel magnetic field forming permanent magnets 2
and 4. The parallel magnetic field forming permanent magnets 2 and 4 are magnetized in the
width direction (left and right direction in FIGS. 1 and 2), and the magnetization directions of the
pair of parallel magnetic field forming permanent magnets 2 and 4 are the same. ing. Therefore,
a parallel magnetic field is formed between the parallel magnetic field forming permanent
magnets 2 and 4.
[0013]
In the parallel magnetic field, a ribbon-shaped diaphragm 5 which serves both as a diaphragm
and a conductor is disposed. The ribbon-shaped diaphragm 5 can be formed using a thin
conductive material, for example, an aluminum foil having a thickness of several μm. The
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ribbon-shaped diaphragm 5 is formed of the above-described material in the form of an
elongated strip, and both ends in the longitudinal direction are provided at the ends in the
longitudinal direction of the frame 1 (see FIG. 2). It is fixed to The electrode lead portions 7 and 9
are insulated from the frame 1 and are conducted to the diaphragm 5 by sandwiching both ends
of the diaphragm 5, and the diaphragm 5 is operated in a state where the diaphragm 5 is given a
suitable tension. keeping. The diaphragm 5 is formed in a triangular wave shape by bending the
portions other than the electrode lead portions 7 and 9 alternately at constant intervals, like the
ribbon diaphragm in a conventional ribbon microphone unit. . The direction of the line formed by
the above-mentioned bending, that is, the direction of the line drawn by the crest and the valley
bottom of the triangular wave is the width direction of the diaphragm 5, and this line is formed at
a constant interval.
[0014]
Similar to a conventional ribbon microphone unit, the ribbon diaphragm 5 receives a sound wave
and vibrates in accordance with the sound wave. The vibration direction is a direction crossing
the magnetic flux between the parallel magnetic field forming permanent magnets 2 and 4, and
the diaphragm 5 made of a conductive material generates electric power by crossing the
magnetic flux. An electrical signal is generated between the electrode lead portions 7 and 9.
Since this electrical signal is a signal of frequency and amplitude corresponding to the frequency
and amplitude of the diaphragm 5, the sound wave striking the diaphragm 5 is converted into an
electrical signal corresponding to this sound wave. Since the ribbon microphone is an inertial
control system, the resonance frequency of the ribbon diaphragm 25 is lower than the lower
frequency of the sound wave to be collected, in other words, lower than the lowest frequency of
the frequency range in which sound can be collected. You need to For this reason, the tension of
the diaphragm 5 is set extremely low. As described above, the diaphragm 5 achieves low tension
by being bent into a corrugated shape.
[0015]
A feature of the ribbon microphone unit 20 according to the present invention is that the ribbon
microphone unit 20 is provided with a pair of magnetic powder-adsorbing permanent magnets
described below. In FIGS. 1 and 2, the parallel magnetic field formed between the pair of parallel
magnetic field forming permanent magnets 2 and 4 is opposed to and in parallel with each other
and separated from the pair of parallel magnetic field forming permanent magnets 2 and 4 in
pair. A permanent magnet 10, 11 for magnetic powder adsorption is disposed. The pair of
magnetic powder adsorbing permanent magnets 10 and 11 are square-prism permanent
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magnets, and one surface of each of the magnetic powder adsorbing permanent magnets 10 and
11 is disposed opposite to each other with the ribbon-shaped diaphragm 5 interposed
therebetween. The pair of magnetic powder adsorbing permanent magnets 10 and 11 are longer
than the parallel magnetic field forming permanent magnets 2 and 4, and both end portions in
the length direction extend outward than the both end faces of the parallel magnetic field
forming permanent magnets 2 and 4 ing. The pair of magnetic powder adsorbing permanent
magnets 10 and 11 are supported so as to be sandwiched between support plates (not shown)
whose both longitudinal ends extend from the frame 1, and a pair of permanent magnets for
forming a parallel magnetic field 2 and 4 are integrally fixed to the frame 1.
[0016]
As shown in FIG. 1, the pair of parallel magnetic field forming permanent magnets 2 and 4 and
the pair of magnetic powder attracting permanent magnets 10 and 11 are fixed so that their
cross sectional shapes are square and their cross sections are parallel to each other. There is.
Further, the pair of parallel magnetic field forming permanent magnets 2 and 4 and the pair of
magnetic powder attracting permanent magnets 10 and 11 are disposed at predetermined
intervals between the permanent magnets. The pair of parallel magnetic field forming permanent
magnets 2 and 4 are arranged along the inner surface of the frame 1 as described above, so that
the frame functions as a yoke, and the parallel magnetic field forming permanent magnets 2 and
4 and the frame 1 A closed magnetic path is formed. Therefore, a strong parallel magnetic field is
formed between the pair of parallel magnetic field forming permanent magnets 2 and 4. On the
other hand, the pair of magnetic powder adsorbing permanent magnets 10 and 11 are formed by
the pair of magnetic powder adsorbing permanent magnets 10 and 11 because only both ends in
the longitudinal direction are supported and no other members are added. The magnetic path to
be formed is an open magnetic path, and around each of the magnetic powder adsorption
permanent magnets 10 and 11, a magnetic field is formed which returns from the permanent
magnet itself and returns to the permanent magnet itself. Therefore, the magnetic field formed
around each of the magnetic powder adsorption permanent magnets 10 and 11 is relatively
weak, and the magnetic field does not affect the parallel magnetic field of the pair of magnetic
powder adsorption permanent magnets 10 and 11.
[0017]
According to the embodiment of the ribbon microphone unit 20 described above, when the
surrounding magnetic powder 30 approaches the microphone unit, the magnetic powder 30 is
attracted to the parallel magnetic field forming permanent magnets 2 and 4 before the magnetic
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powder 30 is attracted to the permanent magnets 2 and 4. It is attracted to the permanent
magnets 10 and 11. Therefore, the magnetic powder 30 does not adhere to the gap between the
pair of parallel magnetic field forming permanent magnets 2 and 4 and the ribbon-shaped
diaphragm 5, and the movement of the diaphragm 5 is inhibited by the magnetic powder 30.
Performance can be prevented from decreasing.
[0018]
In the illustrated embodiment, as shown in FIG. 1, when the opposing faces of the pair of parallel
magnetic field forming permanent magnets 2 and 4 face each other with the diaphragm 5 in
between, except for the front, the left and right The sound wave guiding members 18 and 19 are
fixed to the surfaces (upper and lower in FIG. 1), and the rear surface is fixed to a part of the
frame 1. The sound wave guide members 18 and 19 have an arc-shaped guide surface so as to
guide the sound wave toward the microphone unit 20 toward the diaphragm 5. Therefore, the
parallel magnetic field forming permanent magnets 2 and 4 are guarded from the magnetic
powder approaching the microphone unit 20, and the magnetic powder is along the surface of
the sound wave guiding members 18 and 19. , 11 and is attracted to the permanent magnets 10
and 11 for magnetic powder adsorption. In this manner, the magnetic powder adsorption
permanent magnets 10 and 11 prevent the magnetic powder from reaching the parallel magnetic
field forming permanent magnets 2 and 4. A gap is formed between the magnetic powder
adsorption permanent magnets 10 and 11 and the sound wave guiding members 18 and 19 to
such an extent that the passage of the sound wave toward the diaphragm 5 is not impeded.
[0019]
Next, an embodiment of a ribbon microphone according to the present invention will be
described. The ribbon microphone according to the present invention uses the ribbon
microphone unit 20 according to the present invention as a microphone unit. 4 and 5 show an
embodiment of a ribbon microphone according to the present invention. 4 and 5, the housing of
the microphone mainly includes the lower microphone case 12 and the upper head case 15. A
head case 15 is coupled to the upper end of the open microphone case 12. The head case 15 is
provided to introduce an external sound wave into the microphone unit and shield the
microphone unit inside, and is made of a material in which a large number of gaps such as a
metal mesh and a punching metal are arranged. The head case 15 surrounds the microphone
unit 20 incorporated in the housing. The lower end portion of the microphone case 12 is a small
diameter cylinder, and the tip end portion of the cylinder is a microphone connector portion 16.
For example, a cable-side connector provided at an end of a microphone cable can be inserted
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into the microphone connector portion 16, and an audio signal converted by the microphone is
transmitted to the outside through the cable.
[0020]
An appropriate number of columnar support portions 13 vertically extend in the microphone
case 12, and the circuit board 14 is fixed to the upper end of the support portions 13. The circuit
board 14 is fixed so as to close the open upper end of the microphone case 12, the lower end
face of the ribbon microphone unit 20 described above is mounted on the circuit board 14, and
the microphone unit 20 is fixed to the circuit board 14. ing. The microphone unit 20 rises from
the circuit board 14, and a portion of the microphone unit 20 is surrounded by the head case 15.
Therefore, the sound waves coming in from a large number of gaps formed in the head case 15
can be received by the diaphragm 5 of the microphone unit 20. On the lower surface side of the
circuit board 14, a transformer 35 that boosts and outputs the audio signal converted by the
microphone unit is disposed.
[0021]
In the above-described embodiment of the ribbon microphone, in order to enhance the frequency
response in the high sound range, it is desirable to make the gap formed in the head case as large
as possible to reduce the acoustic resistance of the head case. Then, the magnetic powder is
likely to intrude into the microphone, and the magnetic powder is adsorbed to the pair of parallel
magnetic field forming permanent magnets, and the magnetic powder contacts the ribbon-like
vibrator to deteriorate the performance of the microphone. It becomes. However, according to
the ribbon type microphone unit and the ribbon type microphone according to the present
invention, since the intruding magnetic powder is captured by the magnetic powder adsorption
permanent magnet before reaching the parallel magnetic field forming permanent magnet, the
microphone performance is improved. There is no deterioration. Therefore, it is possible to
increase the gap formed in the head case as much as possible to reduce the acoustic resistance of
the head case, and it is possible to enhance the frequency response of the high range and
enhance the frequency response of the high range. Can be maintained.
[0022]
It is a plane sectional view showing the example of the ribbon type microphone unit concerning
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the present invention. It is a front view of the said Example. It is a side view of the said Example.
It is a side sectional view showing the example of the ribbon type microphone concerning the
present invention. It is front sectional drawing of the said Example. It is a perspective view which
shows the outline | summary of the example of the conventional common ribbon type
microphone unit. It is a plane sectional view showing the example of the conventional common
ribbon type microphone unit. It is a front view of the said prior art example.
Explanation of sign
[0023]
Reference Signs List 1 frame 2 permanent magnet for forming parallel magnetic field 4
permanent magnet for forming parallel magnetic field 5 ribbon-shaped diaphragm 10 permanent
magnet for magnetic powder adsorption 11 permanent magnet for magnetic powder adsorption
12 microphone case 15 head case 20 ribbon type microphone unit 30 magnetic powder
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