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JP2011147010

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DESCRIPTION JP2011147010
[PROBLEMS] A ribbon in which a vibration is effectively suppressed by devising a circuit so that
a larger braking current flows than when an impact force is applied, rather than simply shorting
both ends of a ribbon diaphragm. Obtain a microphone. SOLUTION: A magnet 4 for forming a
magnetic gap, a ribbon diaphragm 5 arranged in the magnetic gap and vibrating by sound waves,
a frame 7 for holding both ends of the magnet 4 and the ribbon diaphragm 5 in the longitudinal
direction , And an output transformer 30 for boosting the signal voltage appearing at both ends
of the ribbon diaphragm 5. An end of the ribbon diaphragm 5 is mechanically coupled to detect
the acceleration force applied to the ribbon diaphragm 5, and a detection signal when the
piezoelectric electron 10 detects the acceleration force of the output transformer 30. The both
ends of the primary winding 31 of the output transformer 30 are respectively connected to both
ends of the ribbon diaphragm 5. [Selected figure] Figure 1
Ribbon type microphone
[0001]
The present invention relates to a ribbon microphone designed to more effectively prevent
breakage of a ribbon diaphragm due to an impact applied during transportation or installation.
[0002]
The ribbon microphone mainly comprises a magnet for forming a magnetic field and a ribbon
diaphragm.
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The magnets are disposed on both sides of the ribbon diaphragm, and a magnetic field is formed
between the magnets on both sides. The ribbon diaphragm is disposed in the magnetic field with
an appropriate tension applied, and both longitudinal ends are fixed. The ribbon diaphragm
receives a sound wave and vibrates in a magnetic field, whereby a current corresponding to the
sound wave flows through the ribbon diaphragm and the sound wave is converted into an
electric signal. Aluminum foil is widely used as a material of the ribbon diaphragm. Aluminum is
suitable as a ribbon diaphragm of a ribbon microphone because it has better conductivity and
lighter specific gravity than other metal materials.
[0003]
The ribbon diaphragm (hereinafter sometimes referred to simply as "ribbon") is an elongated
strip-shaped member, and both longitudinal ends are provided so as to be insulated from the
frame at the longitudinal ends of the window frame. It is fixed to the electrode lead-out part. Each
electrode lead portion conducts to the ribbon by sandwiching each end of the ribbon, and holds
the ribbon in a state where the ribbon is appropriately tensioned. Both ends of the ribbon are
formed in a triangular shape by alternately bending portions other than the portions
corresponding to the electrode lead portions at constant intervals. The direction of the broken
line corresponding to the top and the valley bottom of the triangular wave is the width direction
of the ribbon, and the broken lines are formed at regular intervals. Each electrode lead-out part
has a terminal board, and an output signal of a ribbon type microphone unit can be obtained
from these terminal boards.
[0004]
The ribbon receives a sound wave and vibrates in accordance with the sound wave. The vibration
direction is a direction crossing the magnetic flux between the permanent magnets, and a ribbon
made of a conductor is generated by crossing the magnetic flux to generate an electrical signal
between both ends in the longitudinal direction of the ribbon and thus between the electrode
lead portions . Since this electrical signal becomes a signal of frequency and amplitude
corresponding to the frequency and amplitude of the ribbon, the sound wave striking the ribbon
will be converted into an electrical signal corresponding to this sound wave. The resonance
frequency of the ribbon needs to be lower than the lower frequency of the sound wave to be
collected, in other words, lower than the lowest frequency of the frequency band in which the
sound can be collected. For this reason, the tension of the ribbon is set very low. As mentioned
above, the ribbon is crimped into a corrugated shape to achieve low tension.
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2
[0005]
Since the directivity of the ribbon microphone is bi-directional and the control method is mass
control, the resonant frequency of the ribbon needs to be lower than the lowest frequency of the
frequency range in which sound can be collected. The tension of the ribbon is adjusted so that
[0006]
Ribbon microphones have the disadvantage of being vulnerable to impact forces.
The major factor is that when an impact force is applied to the ribbon formed as described above,
the corrugated portion of the ribbon is stretched by the inertia force by the mass of the ribbon. If
the ribbon is stretched, the frequency response is degraded due to the shift of the resonance
frequency. Also, if the ribbon is stretched excessively, the ribbon contacts the magnetic pole, ie,
the permanent magnet, and the frequency response is extremely degraded.
[0007]
Since the microphone is likely to be subjected to a large impact force during transportation, a
cushioning material is mounted in a box for housing the microphone, and the microphone is
protected from the impacting force by holding the microphone via the cushioning material.
Therefore, a certain buffering effect can be expected against the impact force applied during
transportation.
[0008]
However, the presence of the cushioning material alone limits the magnitude of the impact force
that can be protected, and the extension of the ribbon can not be avoided if an impact force
exceeding the expected level is applied. In addition, an unexpected impact force may be applied
to the microphone, such as erroneous removal when attaching the microphone to the
microphone stand, and the ribbon may be extended by this impact force.
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[0009]
Therefore, the present applicant has a magnet for forming a magnetic gap, a ribbon diaphragm
that is disposed in the magnetic gap and vibrates by sound waves, and a frame that holds both
ends of the magnet and the ribbon diaphragm in the longitudinal direction. A ribbon type
microphone comprising a microphone side connector capable of electrically connecting both
ends of a ribbon type diaphragm with a cable side connector, wherein the microphone side
connector has a switch that is switched by the attachment and detachment of the cable side
connector This switch electrically opens both ends of the ribbon diaphragm when the
microphone connector and the cable connector are coupled, and when the cable connector is
pulled out from the microphone connector, both ends of the ribbon diaphragm A ribbon-type
microphone characterized in that the switch is an electrical short circuit Iterator destination filed
(see Patent Document 1).
[0010]
JP, 2009-218685, A
[0011]
According to the invention described in Patent Document 1, in a mode in which the cable-side
connector is pulled out from the microphone-side connector, the switch electrically shorts both
ends of the ribbon diaphragm to form a closed circuit.
In this state, when an impact force is applied to the microphone and the ribbon diaphragm moves
relative to the magnetic gap, a counter electromotive force is generated in the ribbon diaphragm,
and a current due to the back electromotive force flows through the closed circuit to cause
electromagnetic Generates a braking force.
Since this braking force acts in the opposite direction to the vibration direction of the ribbon
diaphragm, the vibration of the ribbon diaphragm due to the impact force is suppressed.
Therefore, even when a large impact force is applied during transportation or installation work,
and thus when the cable side connector is not coupled to the microphone side connector, the
impact force applied to the ribbon type diaphragm is relaxed, and the ribbon type is formed. It is
possible to avoid such a problem that the diaphragm is extended or deformed.
[0012]
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The inventor of the present invention understands that the vibration of the ribbon diaphragm
due to an impact force is effectively suppressed by devising the output circuit including the
output transformer with the invention described in Patent Document 1 as a hint. It came to The
present invention is derived from such a process, and when an impact force is applied to the
ribbon diaphragm, a larger braking current flows than when only both ends of the ribbon
diaphragm are electrically shorted. An object of the present invention is to provide a ribbon-type
microphone in which a circuit is devised to effectively suppress vibration.
[0013]
The present invention comprises a magnet forming a magnetic gap, a ribbon diaphragm arranged
in the magnetic gap and vibrating by sound waves, a frame holding the magnet and both
longitudinal ends of the ribbon diaphragm, and A ribbon type microphone comprising an output
transformer for boosting and outputting a signal voltage appearing at both ends of a ribbon type
diaphragm, wherein the ribbon type diaphragm is mechanically coupled to an end of the ribbon
type diaphragm. And a photo relay for shorting the secondary winding of the output transformer
with a detection signal when the piezoelectric electrons detect an acceleration force, and the
primary of the output transformer The main feature is that both ends of the winding are
respectively connected to both ends of the ribbon diaphragm.
[0014]
When a large impact is applied during transport of the ribbon microphone, the ribbon diaphragm
tries to vibrate rapidly, and an acceleration force is applied to piezoelectric electrons to which the
end of the ribbon diaphragm is mechanically coupled.
The piezoelectric electrons detect this acceleration force and output a signal, which causes the
photorelay to short the secondary winding of the output transformer. Assuming that the turns
ratio of the primary winding and the secondary winding of the output transformer is 1: N, the
impedance of the primary winding is N <2> times the impedance of the secondary winding. Since
the impedance or electrical resistance when the photorelay shorts the secondary winding of the
output transformer is several tenths Ω, if this is multiplied by N <2>, the impedance of the
primary winding will be infinitely zero It is close to Therefore, both ends of the ribbon diaphragm
are substantially the same as being short-circuited by an impedance or electrical resistance as
close to zero as possible, and the vibration of the ribbon diaphragm causes the counter
electromotive current flowing to the ribbon diaphragm to increase. A large braking force can be
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generated to effectively suppress the vibration of the ribbon diaphragm.
[0015]
Further, according to the present invention, regardless of whether the microphone cord is
connected to the microphone, when an impact force is applied, the vibration of the ribbon
diaphragm due to the impact force is suppressed. Therefore, even if the microphone cord is not
connected, even if the microphone is alone, when an impact force is applied during handling, the
vibration of the ribbon diaphragm is suppressed and the ribbon diaphragm is protected.
[0016]
FIG. 1A is a side sectional view and an electrical connection diagram showing an embodiment of
a ribbon microphone according to the present invention. It is a front view of the ribbon type
microphone which concerns on the said Example.
[0017]
Hereinafter, embodiments of a ribbon microphone according to the present invention will be
described with reference to the drawings.
[0018]
In FIGS. 1 and 2, the ribbon microphone unit 3 includes a frame 7 formed in the shape of a
vertically long rectangular window frame.
In the frame 7, a pair of permanent magnets 4 are fixed on both sides along the long side
direction inner side surface of the vertically long window frame (only one permanent magnet is
shown in FIG. 1). Both permanent magnets 4 are fixed at predetermined intervals. Both
permanent magnets 4 are magnetized in the width direction. The magnetization directions of the
pair of permanent magnets 4 are the same, and a parallel magnetic field is formed between both
permanent magnets 4.
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[0019]
In the above-mentioned parallel magnetic field, a ribbon diaphragm (which may be simply
referred to as a "ribbon" hereinafter) 5 which also serves as a diaphragm and a conductor is
disposed. The ribbon 5 is an elongated strip-shaped member, and both longitudinal direction end
portions 51 are fixed to the electrode lead-out portions 18 provided at the longitudinal direction
both end portions of the frame 7. The electrode lead-out portion 18 is insulated from the frame
7, and the ribbon 5 is conducted by holding the both ends of the ribbon 5 between the holding
members 8, and holds the ribbon 5 in a state where the ribbon 5 is given appropriate tension.
doing. The holding members 8 at the both ends are stacked on the terminal plate 9. These
terminal boards 9 are electrically conducted to the respective end portions of the ribbon 5
together with the holding members 8, and output audio signals electroacoustically converted by
the ribbon microphone unit 3 from the respective terminal boards 9. It has become.
[0020]
The shape of the ribbon 5 is not particularly limited, but in the illustrated example, the other
portions except the portion corresponding to the electrode lead-out portion 18 are alternately
bent at constant intervals to form a triangular vibration portion 52. The vibrator 52 vibrates in
response to the sound wave. The direction of the constant intervals forming the triangular wave
vibrating portion 52 is the width direction of the ribbon 5. The number of ribbons 5 may be only
one as shown in the example shown, or two ribbons arranged in parallel at an appropriate
interval may be provided, and these two ribbons may be connected in series or in parallel. You
may
[0021]
Usually, an output transformer for boosting and outputting an output voltage is provided on the
output side of the ribbon microphone unit. In the illustrated embodiment, both ends of the
primary winding 31 of the output transformer 30 are connected to both ends of the ribbon
diaphragm 5, more specifically to the terminal plates 9 at both ends, and the secondary winding
of the output transformer 30 is Audio signals are output from both ends of the line 32.
[0022]
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Then, piezoelectric electrons 10 for detecting an acceleration force applied to the ribbon 5 by
arranging the end 51 of the ribbon 5 mechanically are disposed at one of the electrode lead-out
portions 18 at both ends. The piezoelectric electron 10 is formed, for example, by laminating a
plurality of piezoelectric elements, and when the ribbon 5 is subjected to a rapid acceleration
force, that is, an impact force, the ribbon 5 can be detected. The ends 51 of the two are
overlapped and coupled. The piezoelectric electron 10 has a maximum sensitivity direction as
shown by an arrow 15 in FIG. 1, and the maximum sensitivity direction 15 is disposed in the
direction of the sound collection axis 55 of the ribbon 5. In the ribbon 5, the vibrating portion 52
is a sound collecting surface, and the sound collecting axis 55 includes the center position of the
sound collecting surface and is in the direction orthogonal to the sound collecting surface.
[0023]
The light emitting element 21 of the photo relay 20 is connected between the electrodes 11 and
12 on both sides of the piezoelectric electron 10. The photorelay 20 includes a switch 22 that
receives light from the light emitting element 21 and turns it on and off. The photorelay 20 can
be configured by, for example, a photo MOSFET. That is, the light emitting element 21 is
constituted by an LED (light emitting diode), and the switch 22 is a light receiving element for
receiving light from the LED, for example, a photoelectric cell and an FET electrically conducted
by a current flowing by the photoelectric cell It can be configured. The photo relay 20 configured
in this way has a resistance of 0. 0 when the switch 22 is turned on. It is characterized in that it
is as low as several Ω, for example 0.2 Ω. The switch 22 is connected in parallel to the
secondary winding 32 of the output transformer 30, and thus shorts the secondary winding 32
when the switch 22 is turned on. When the photo relay 20 is configured by a photo MOSFET, the
portion corresponding to the switch 22 is configured by two FETs forming a pair, so that it can
be a bidirectional switch.
[0024]
The components shown in FIG. 1 provided with the ribbon microphone unit 3, the photo relay
20, and the output transformer 30 described above are housed in a microphone case (not
shown). In addition, a circuit board is incorporated in the microphone case as necessary, and a
connector for connecting a microphone cable is also attached, whereby a ribbon microphone is
configured.
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[0025]
Next, the operation of the above embodiment will be described. Under normal conditions of use,
when the ribbon 5 made of a conductor receives a sound wave, the ribbon 5 generates power by
oscillating across the magnetic flux between the permanent magnets 4, and between the
longitudinal ends of the ribbon 5 and hence the electrode lead portion An electrical signal is
generated between 18. Since this electrical signal becomes a signal of frequency and amplitude
corresponding to the frequency and amplitude of the ribbon 5, the acoustic wave striking the
ribbon 5 is converted into an electrical signal corresponding to the acoustic wave. This electrical
signal is input to the primary winding 31 of the output transformer 30, boosted by the output
transformer 30, and output from the secondary winding 32 thereof.
[0026]
If the ribbon microphone according to the above embodiment is dropped and impacted during
use, or if it is roughly handled and impacted during transportation, the impact force causes the
ribbon 5 to vibrate largely and accelerates to both ends of the ribbon 5. Power is added. This
acceleration force is applied to the piezoelectric electrons 10 mechanically coupled to the end of
the ribbon 5, and the piezoelectric electrons 10 detect this acceleration force and output a signal.
The detection signal causes a current to flow in the light emitting element 21 to cause the light
emitting element 21 to emit light, and the light is received by the photocell, and the FET or the
like constituting the switch 22 is turned on by the light receiving signal of the photocell to output
the output transformer 30 secondary windings 32 are shorted.
[0027]
Assuming that the turns ratio of the primary winding 31 and the secondary winding 32 of the
output transformer 30 is 1: N, the impedance of the primary winding 31 is N <2> times the
impedance of the secondary winding 32. Since the impedance or electrical resistance when the
photorelay 20 shorts the secondary winding 32 of the output transformer 30 is several tenths Ω,
for example, about 0.2 Ω, multiplying the above by N <2> by 1 The impedance of the winding 31
becomes as close to zero as possible. Therefore, both ends of the ribbon 5 become substantially
the same as being short-circuited with an impedance or electrical resistance as close to zero as
possible, and the counter electromotive current flowing in the ribbon 5 is increased by the ribbon
5 vibrating and a large braking force is generated. Thus, the vibration of the ribbon 5 can be
effectively suppressed.
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[0028]
The direction in which the ribbon 5 is most easily vibrated is the direction of the sound collection
axis 55. When a large acceleration force is applied in this direction, the ribbon 5 extends and
tends to be slack, and desired acoustic characteristics can not be obtained. Alternatively, the
ribbon 5 comes in contact with the permanent magnet 4 or the like and can not perform a
predetermined operation. Therefore, in the illustrated embodiment, the piezoelectric electrons 10
are disposed such that the maximum sensitivity direction is the same as the sound collecting axis
55 of the ribbon 5 so that the ribbon 5 is rapidly moved in the sound collecting axis 55 direction
by impact force. If it is going to vibrate, this vibration is detected with high sensitivity by the
piezoelectric electrons 10, so that both ends of the ribbon 5 can be shorted quickly, and the
ribbon 5 can be braked quickly.
[0029]
The ribbon type microphone has a problem that the mechanical component is bulky and the
characteristic is easily deteriorated due to the impact when it is dropped or the like, which is an
obstacle to the spread. According to the present invention, the problem of the characteristic
deterioration due to impact can be significantly improved, which can contribute to the spread of
ribbon microphones.
[0030]
Reference Signs List 3 ribbon type microphone unit 4 magnet 5 ribbon type diaphragm 7 frame
10 piezoelectric 20 photo relay 21 light emitting element 22 switch 30 output transformer 31
primary winding 32 secondary winding
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