JP2008042622

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DESCRIPTION JP2008042622
[PROBLEMS] A connection resistance of a fixing portion between a ribbon-shaped diaphragm and
an electrode can be reduced, and the conductivity of the fixing portion can be stably maintained.
A ribbon microphone is obtained which is hard to be transmitted to the diaphragm and can avoid
deformation of the ribbon diaphragm. A ribbon diaphragm 1 arranged in a magnetic field, fixing
means 8 for fixing both end portions of the ribbon diaphragm 1, and a permanent magnet for
forming a magnetic field, the fixing means 8 comprising A pair of fixing members 3 and 5
sandwiching the end of the ribbon diaphragm 1 at both ends of the ribbon diaphragm 1 and a
fastening member 6 clamping the pair of fastening members 3 and 5 The conductive cloth 4 is
interposed between the ribbon diaphragm 1 and one of them. [Selected figure] Figure 2
Ribbon type microphone
[0001]
The present invention relates to a ribbon microphone, and is particularly characterized in the
fixing structure of the end of a ribbon diaphragm.
[0002]
In the ribbon microphone, a ribbon-shaped diaphragm is used as a diaphragm.
The ribbon diaphragm is fixed, for example, by sandwiching both ends in the lengthwise
direction thereof with a fixed electrode. On both sides in the width direction of the ribbon
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diaphragm, a pair of permanent magnets are disposed opposite to each other so as to sandwich
the ribbon diaphragm in the width direction, and ribbon electrodes are disposed in a magnetic
field formed by the permanent magnets. ing. The ribbon diaphragm vibrates in the magnetic field
by receiving a sound wave, so that an electrical signal corresponding to the sound wave is
generated in the ribbon diaphragm, and the electric signal can be taken out from both ends of
the ribbon diaphragm. As a material of the ribbon diaphragm, one having good conductivity and
light specific gravity is desirable, and in general, aluminum foil is used.
[0003]
Patent Document 1 is a patent publication related to the applicant's patent application, and FIG. 4
shows an example of a ribbon microphone described in Patent Document 1. In FIG. 4, reference
numeral 10 denotes a ribbon diaphragm. The ribbon-shaped diaphragm 10 is formed, for
example, of an elongated strip-like member made of aluminum foil in a corrugated shape, leaving
both end portions 10a and 10b in the longitudinal direction. As a method of forming the ribbon
diaphragm 10 in a wave shape, for example, there is a method of interposing a belt-like member
between a pair of gears, meshing the pair of gears, and rotating the pair of gears. By rotation of
the pair of gears, the strip-like member is formed into a corrugated shape while being fed. The
strip-like member is shaped in such a way that the longitudinal cross section is corrugated,
except for the longitudinal ends 10a and 10b. Aluminum foil is characterized by good
conductivity and light specific gravity as described above, and is suitable for performing the
above-mentioned bending and is suitable as a material of a ribbon diaphragm of a ribbon
microphone. In particular, it is desirable to use a pure aluminum material which does not contain
other metal components.
[0004]
Flat end portions 10 a and 10 b of the ribbon diaphragm 10 which are not subjected to bending
are fixed to the fixed electrodes 20 and 20. The fixed electrodes 20, 20 each include a pair of
electrode members 20a, 20b. Assuming that one electrode member 20 b is a member fixed to the
microphone body side, both ends 10 a and 10 b of the ribbon diaphragm 10 are mounted on the
electrode members 20 b on both sides, and both ends 10 a of the ribbon diaphragm 10 , 10b,
and the other electrode member 20a is placed on the electrode member 20b. One of the
electrode members 20a has a round hole near the ends on both sides avoiding the position
corresponding to the ribbon diaphragm 10, and the other electrode member 20b is a screw hole
at a position corresponding to the round hole of the electrode member 20a. have. A screw 22 as
a fastening means is inserted into each round hole of each electrode member 20a, each screw 22
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is screwed into each screw hole of the electrode member 20b, and both ends of the ribbon
diaphragm 10 are a pair of electrode members 20a, It is sandwiched between 20b and fixed.
[0005]
A pair of permanent magnets 30, 30 formed in a quadrangular prism shape are disposed in
parallel to the longitudinal direction of the ribbon diaphragm 10 so as to sandwich the ribbon
diaphragm 10 from the width direction thereof. A magnetic field directed from one permanent
magnet to the other permanent magnet is formed between the pair of permanent magnets 30,
30, and the ribbon diaphragm 10 is present in the magnetic field. An appropriate gap is formed
between the ribbon diaphragm 10 and the pair of permanent magnets 30, 30. The ribbon
diaphragm 10 vibrates in response to the sound wave by receiving the sound wave. The ribbon
diaphragm 10 vibrates in the magnetic field to generate an electrical signal corresponding to the
sound wave. That is, the device described above constitutes a ribbon microphone as an
electroacoustic transducer. The electrical signal generated by the ribbon diaphragm 10 is taken
out from the fixed electrodes 20, 20 to the outside. Therefore, the pair of electrode members 20a
and 20b constituting the fixed electrodes 20 and 20 are made of a conductive material, and are
generally manufactured of a copper alloy in consideration of processability.
[0006]
It is preferable to form a gold-deposited film on both the front and back sides of the ribbon
diaphragm 10 made of aluminum foil, including the both ends 10a and 10b. The gold deposited
film desirably has a film thickness of 500 angstroms (50 nm) or more, and a mass to be added to
the ribbon diaphragm 10 is within 10%. The ribbon-shaped diaphragm 10 can prevent the
oxidation of the aluminum foil and can reduce the change in sensitivity by forming a vapor
deposited gold film.
[0007]
JP, 2005-252440, A
[0008]
The present invention is a further improvement of the ribbon microphone described above.
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The ribbon diaphragm is generally made of a material such as an aluminum foil, which has a very
low resistance to electrical conduction. Further, since the ribbon type microphone has a small
signal level, the signal level extracted through the above-mentioned electrode member is raised
by a step-up transformer to be a microphone output. The DC resistance of the ribbon diaphragm
is about 0.1 to 0.2 Ω, and the step-up transformer has, for example, 0.2 Ω on the primary side
and about 600 Ω on the secondary side. As described above, since the conductive resistance of
the ribbon diaphragm is small, even if the electric path from the ribbon diaphragm to the step-up
transformer has an electrical resistance of several tenths Ω, the sensitivity is decreased and the
output impedance is increased. I have a problem. For example, assuming that the connection
resistance is 0.1Ω while the resistance of the ribbon diaphragm is 0.1Ω, the sensitivity of the
microphone decreases, and the output impedance increases according to the transformation ratio
of the step-up transformer. There is a problem that it will end up. Therefore, it is necessary to
minimize the DC resistance of the portion connecting the ribbon diaphragm and the step-up
transformer as much as possible.
[0009]
In order to reduce the DC resistance of the portion connecting the ribbon diaphragm and the
step-up transformer, in the conventional example shown in FIG. 4, it is sufficient to increase the
pressing force between the pair of electrode members 20a and 20b. The tightening force of the
[0010]
However, a gap corresponding to the thickness of the ribbon diaphragm 10 is created between
both ends of the pair of electrode members 20a and 20b in the longitudinal direction, and when
this portion is strongly tightened by the screw 22, the pair of electrodes Both or one of the
members 20a and 20b is bowed and the stress on the widthwise central portion of the ribbon
diaphragm 10 is reduced to increase the connection resistance.
[0011]
In order to solve this problem, a device is also made in which one of the pair of electrode
members 20a and 20b is deformed in advance in the direction opposite to the bending direction
by the tightening of the screw 22.
However, how much the electrode member is deformed depends on the experience and intuition
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of a person involved in manufacturing, and has a problem that the productivity is inferior.
[0012]
In any case, the contact portion between the ribbon diaphragm and the electrode member in the
conventional ribbon microphone is a point contact of several points, and requires skill in order to
stabilize the connection resistance without variation.
[0013]
In addition, since the pair of electrode members 20a and 20b for fixing the both ends of the
ribbon diaphragm 10 is tightened with the screw 22, a slight gap is required between the round
hole of the one electrode member 20a and the screw 22. .
The other electrode member 20b is fixed to, for example, a circuit board fixed in the microphone
case by an appropriate means such as adhesion, and the electrode member 20a is tightened with
a screw 22 to the electrode member 20b.
However, at the moment when the screw 22 comes into contact with the electrode member 20a
and is fixed to the other electrode member 20b, a rotational force is applied to the electrode
member 20a, and the electrode member is equal to the gap between the round hole of the
electrode member 20a is displaced. Although the amount of displacement is small, the ribbon
diaphragm 10 is deformed so as to twist as the end portion of the ribbon diaphragm 10
elongated in a band shape is distorted. When the ribbon diaphragm 10 is deformed as described
above, the response of the ribbon diaphragm 10 to a sound wave is reduced, which causes the
performance of the microphone to be degraded.
[0014]
Thus, it is necessary to carefully tighten the electrode member 20a with the screw 22. When
fixing the electrode member 20a to the other electrode member 20b, the ribbon diaphragm 10 is
not twisted while holding the electrode member 20a with tweezers or the like while alternately
tightening the two screws 22 little by little. I am working carefully.
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[0015]
The present invention solves the problems of the prior art as described above, that is, it is
possible to reduce the connection resistance of the fixed portion between the ribbon diaphragm
and the electrode, and stably maintain the conductivity of the fixed portion. It is an object of the
present invention to provide a ribbon type microphone which can prevent the deformation of the
ribbon diaphragm by preventing the torsional stress from being transmitted to the ribbon
diaphragm by tightening the fixing member with a screw.
[0016]
A ribbon-type microphone according to the present invention includes a ribbon-shaped
diaphragm disposed in a magnetic field, fixing means for fixing both ends of the ribbon-shaped
diaphragm, and a permanent magnet for forming the above-mentioned magnetic field. The means
includes a pair of fixing members sandwiching the end of the ribbon diaphragm at both ends of
the ribbon diaphragm, and a fastening member clamping the pair of fixing members together,
and one of the pair of fixing members and the ribbon The main feature is that the conductive
cloth is interposed between the diaphragm and the diaphragm.
[0017]
The conductive cloth is pressed in a state of being in contact with the ribbon diaphragm and the
fixing member at many points on its surface, and stable electrical conductivity can be obtained,
and the fixing member and the conductive cloth are in contact with the ribbon diaphragm It acts
to reduce the resistance and can lower the resistance of the connection.
In addition, when the end of the ribbon diaphragm is sandwiched and fixed by fastening a pair of
fixing members with a fastening member such as a screw, no torsional stress such as a screw is
directly applied to the ribbon diaphragm, and the screw Even if a torsional stress occurs, the
ribbon-shaped diaphragm can be prevented from being deformed because it is only displaced
between the fixing member and the conductive cloth.
Thus, the ribbon diaphragm can be fixed without requiring skill.
[0018]
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Hereinafter, embodiments of the ribbon microphone according to the present invention will be
described with reference to FIGS. 1 to 3. FIGS. 1 to 3 show the fixing structure on one end side of
the ribbon diaphragm, and the fixing structure on the other end side of the ribbon diaphragm is
similarly configured.
[0019]
In FIGS. 1 to 3, reference numeral 1 denotes a ribbon diaphragm. Like the ribbon diaphragm in
the conventional example shown in FIG. 4, the ribbon diaphragm 1 is obtained by bending an
elongated strip of aluminum foil made of pure aluminum, for example, into a corrugated shape
leaving both end portions in the longitudinal direction. It is. The ribbon-shaped diaphragm 1 may
be formed into a corrugated shape by selecting and using any method from known methods.
Aluminum foil is characterized by good conductivity and light specific gravity, and is suitable for
bending.
[0020]
Flat end portions of the ribbon diaphragm 1 which are not subjected to bending are fixed by
fixing means. FIGS. 1 to 3 show only one end side of the ribbon-shaped diaphragm 1 which is a
flat surface, and only one fixing means 8 for fixing the one end side 1a. The fixing means 8
comprises a pair of fixing members 3 and 5. Assuming that one fixing member 3 is a first fixing
member, the first fixing member 3 is adhered to the back surface side (the lower surface side in
FIGS. 2 and 3) of the circuit board 2 fixed to the microphone body side. It is fixed by an
appropriate fixing means. The first fixing member 3 is a quadrangular prism-shaped member,
and the longitudinal direction thereof is disposed near one side edge of the circuit board 2 in
parallel with the one side edge. The material of the first fixing member 3 is made of, for example,
a conductive material such as a copper alloy.
[0021]
On the front surface side (upper surface side in FIGS. 2 and 3) of the circuit board 2, a circuit
pattern for drawing out an audio signal generated at least by the ribbon diaphragm 1 is formed.
On the surface side of the circuit board 2, one end portion 1 a of the ribbon-shaped diaphragm 1
is mounted on the circuit pattern with the longitudinal direction of the first fixing member 3
orthogonal to the direction perpendicular thereto. . A conductive cloth 4 is placed on the ribbon
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diaphragm 1. The conductive cloth 4 is woven into a cloth shape by winding conductive thin
wires or is formed into a non-woven cloth, and has elasticity by having a certain thickness. The
conductive cloth 4 has substantially the same shape as the planar shape of the first fixing
member 3 and faces the upper surface of the first fixing member 3 with the circuit board 2 and
the one end portion 1 a of the ribbon diaphragm 1 interposed therebetween. It is arranged.
Therefore, the conductive cloth 4 has a length sufficient to cross the one end 1 a of the ribbon
diaphragm 1 in the width direction, and covers the one end 1 a of the ribbon diaphragm 1 in the
width direction.
[0022]
On the conductive cloth 4, the second fixing member 5 constituting the fixing means 8 is placed.
The second fixing member 5 is formed in substantially the same rectangular column as the first
fixing member 3 and placed on the conductive cloth 4 in parallel with the first fixing member in
the same direction as the first fixing member 3 There is. The second fixing member 5 has round
holes near the end portions on both sides in the longitudinal direction, avoiding the position
corresponding to the ribbon diaphragm 1, and the conductive cloth 4 and the circuit board 2 also
have holes at positions corresponding to the above round holes. The first fixing member 3 has
screw holes at positions corresponding to the round holes of the second fixing member 5. Screws
6 as fastening means are inserted through the respective round holes of the second fixing
member 5, and the conductive cloth 4 and the screws 6 penetrating the holes of the circuit board
2 are screwed into the respective screw holes of the first fixing member 3. The first fixing
member 3 and the second fixing member 5 sandwich the conductive cloth 4, the circuit board 2
and the one end portion 1 a of the ribbon diaphragm 1 between them, and are fastened by
screws 6. By doing this, the flat one end 1a of the ribbon diaphragm 1 has the conductive cloth 4
interposed between the one end 1a and the second fixing member 5, and the one end 1a and the
first In a state where the circuit board 2 is interposed between the fixing member and the fixing
member, the pair of fixing members 3 and 5 sandwich and fix the circuit board 2. In the
illustrated example, the pair of screws 6, 6 penetrate near both ends of the conductive cloth 4,
but the length of the conductive cloth 4 may be shorter than the dimension between the pair of
screws 6, 6. However, it is preferable that the length be sufficient to straddle the one end portion
1 a of the ribbon diaphragm 1 in the width direction. The second fixing member 5 is also made
of, for example, a conductive material such as a copper alloy.
[0023]
According to the embodiment configured as described above, when the second fixing member 5
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is tightened to the first fixing member 3 by the screw 6, one end portion of the ribbon diaphragm
1 with the conductive cloth 4 interposed. 1 a is sandwiched between the first fixing member 3
and the first fixing member 3. In the case of the illustrated embodiment, more precisely, between
the first fixing member 3 and the second fixing member 5, the circuit board 2 and the one end
portion 1a of the ribbon diaphragm 1 and the conductive cloth 4 are in this order Overlap is
caught. The conductive cloth 4 has many layers of conductive thin wires, so that one end 1a of
the ribbon diaphragm 1 and the conductive cloth 4, and the conductive cloth 4 and the second
fixing member 5 contact each other at many points, While the mutual conductivity is stabilized,
the conductive cloth 4 functions to reduce the contact resistance with the member in contact
therewith. In this way, stable conductivity can be easily realized. Further, when the screw 6 is
tightened, the second fixing member 5 rotates relative to the conductive cloth 4 by sliding
relative to the conductive cloth 4, so the rotational force acting on the second fixing member 5 is
applied to the one end portion 1 a of the ribbon diaphragm 1 There is no direct application, and
no torsional stress is applied to the ribbon diaphragm 1. Therefore, the ribbon-shaped diaphragm
1 can be easily fixed to the fixing means 8 without requiring skill.
[0024]
1 to 3 show one end 1a of the ribbon diaphragm 1 and its fixing structure, but the other end of
the ribbon diaphragm 1 is also configured in the same manner as the one end 1a. The other end
of the ribbon-shaped diaphragm 1 is fixed with the same fixing structure as in the above, and
thus with the interposition of a conductive cloth similar to the conductive cloth 4. A pair of
permanent magnets are disposed opposite to each other across the ribbon diaphragm 1 in the
width direction, a magnetic field is formed between the opposing surfaces of the pair of
permanent magnets, and the ribbon diaphragm 1 is formed in a corrugated shape. The main part
is located. Therefore, when a sound wave strikes the ribbon diaphragm 1, the ribbon diaphragm
1 vibrates in response to the sound wave, and an electric signal is generated in the ribbon
diaphragm 1 by crossing the magnetic flux. This electrical signal is an audio signal corresponding
to a sound wave, and this audio signal can be taken out through the circuit pattern of the circuit
board 2 at both ends of the ribbon diaphragm 1 or from the second fixing member 5 to the
outside. It is supposed to be.
[0025]
The circuit board 2 is not essential, and when the circuit board 2 is not used, an electrical signal
can be extracted from the electrode member to the outside as in the conventional example shown
in FIG. As described in Patent Document 1, the ribbon-shaped diaphragm 1 is mainly made of
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aluminum foil, and it is preferable to form a gold-deposited film having a film pressure of 50 nm
or more on both surfaces thereof. By doing this, it is possible to prevent galvanic corrosion due to
the joining of dissimilar metals.
[0026]
In fixing the both ends of the ribbon diaphragm 1 by the fixing means 8, one end of the ribbon
diaphragm 1 is temporarily fixed with the screw 6 of the fixing means 8 loosely tightened, and
the ribbon diaphragm 1 is The resonance frequency is measured while pulling from one end, and
when the resonance frequency reaches an appropriate value, the screw 6 is strongly tightened
and fixed at that position. When this work is performed, if there is no conductive cloth 4 having
an elastic force, no pressing force is applied to one end of the ribbon diaphragm 1 in the abovementioned temporarily fixed state. When the hand is released, the ribbon diaphragm 1 is
tightened like a coil spring, and the adjustment operation is difficult. In that respect, according to
the embodiment of the present invention, the ribbon diaphragm 1 is pressed by the elastic force
of the conductive cloth 4 in the temporarily fixed state, and the ribbon diaphragm 1 is stretched
even if the hand is released. There is an advantage that the adjustment work is easy because it is
not.
[0027]
The portion described above is a portion that should be called a microphone unit of a ribbon type
microphone, and a portion corresponding to this microphone unit is incorporated into a
microphone case to become a final product of the microphone.
[0028]
It is a top view which shows only the principal part of the ribbon type microphone concerning
this invention.
It is front sectional drawing of the principal part of a ribbon type microphone same as the above.
It is principal part side sectional drawing of a ribbon type microphone same as the above. It is an
exploded perspective view showing an example of a conventional ribbon type microphone.
Explanation of sign
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[0029]
DESCRIPTION OF SYMBOLS 1 ribbon-shaped diaphragm 1a one end part of a ribbon-shaped
diaphragm 2 circuit board 3 1st fixing member 4 electrically conductive cloth 5 2nd fixing
member 6 screw 8 fixing means
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