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JPH0346500

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DESCRIPTION JPH0346500
[0001]
Hereinafter, the present invention will be described as follows. A, Industrial Application Field B0
Outline of the Invention C0 Prior Art 9 Problems to be Solved by the Invention 1 Means for
Solving the Problems 73 Action G, Embodiment CG-1) First Embodiment 1 to 4 (G-2) Second
embodiment (FIG. 5) (G-3) Third embodiment (FIGS. 6 and 7) (G-4) Fourth embodiment Example
(FIGS. 8 and 9) (G-5) Fifth embodiment (FIGS. 10 and 11 (G-6) Sixth embodiment (FIG. 12 to 14 H
1 effect of the invention) FIG. A) Industrial Application Field The present invention relates to a socalled electromagnetic induction type electroacoustic transducer used as a speaker or a
microphone. SUMMARY OF THE INVENTION The present invention relates to a so-called
electromagnetic induction type electroacoustic transducer, which supports a vibration temporary
having a conductive portion at least in a part so as to be movable back and forth, and the fourelectric part of this diaphragm is in direct / JtLil field By placing the induction coil opposite to
the conductive portion while positioning the diaphragm, the diaphragm has a sufficient area, and
at least one of the conductive portion and the induction coil is made of a superconducting
material. When it is configured as (1), a reproduced sound with a sufficient sound pressure and
faithful to the input signal can be obtained, and heat generation accompanying driving can be
suppressed. C1 Conventional Technology Conventionally, so-called electromagnetic induction
type speakers have been proposed as electroacoustic transducers. For example, Japanese Utility
Model Application Laid-Open No. 50-105438 has a dome-shaped vibrator which is formed in a
substantially hemispherical shape and is formed into a dome shape by a conductive material, and
the dome-shaped vibrator can be advanced and retracted in the axial direction A speaker is
shown in which the open end of the dome-shaped vibrator is disposed in a DC magnetic field
formed by the magnetic circuit unit. In this speaker, the inner side or the outer side of the open
end of the dome-shaped vibrating body is concentric with the ring formed by the end so as to
face the inner side or the outer side of the open end. An induction coil is disposed in the shape of
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a circle. In this speaker, by supplying a signal current to the induction coil, a secondary current
due to electromagnetic induction is induced along the ring forming the end on the open end of
the dome-shaped vibrator, The dome-shaped vibrator is driven to vibrate. In this speaker, since
the dome-shaped vibrating body must be formed to have good conductivity, the material
constituting the dome-shaped vibrating body is limited, and m mechanical loss, specific gravity,
etc. can be reproduced for sound reproduction. It is difficult to use suitable materials.
When the vibrator is made of a material having a small mechanical loss and a relatively large
specific gravity, such as metal, resonance at a specific frequency is likely to occur, and the
response to an input signal is It becomes worse and good sound reproduction characteristics can
not be obtained. On the other hand, the present orderer proposes an electromagnetic induction
type speaker configured using a flat diaphragm made of a conductive material. That is, as shown
in FIG. 15, this speaker has a yoke 102 in which a center ball 101 is integrally protruded at a
central portion, an annular magnet 103 disposed on the yoke +02, and the magnet 103. It has a
magnetic circuit unit configured by an annular top plate 104 disposed on the upper side. An
opposing gap between the center ball 101 and the tongue play 1104 is a magnetic gap 105, in
which a direct current magnetic field in which magnetic fluxes become radial is formed. On the
inner peripheral portion of the magnet 103, a flat diaphragm 106 formed in a disk shape
corresponding to the inner peripheral portion of the magnetotoe 03 advances and retracts in a
direction substantially orthogonal to the DC magnetic field indicated by the arrow r in FIG. It is
freely supported. That is, the flat diaphragm 106 is supported by and attached to the inner
peripheral surface of the magnet 103 via the predetermined damper member 107. An induction
coil 108 is disposed in close proximity to the vibrations 41i and 106. In this speaker, when a
signal current is supplied to the induction coil +08, a secondary current is induced in the flat
diaphragm 106 by electromagnetic induction. The induced current flows in the circumferential
direction of the planar vibration FiI 06, and the planar diaphragm 106 is driven to vibrate in the
direction orthogonal to the DC magnetic field. Then, sound is emitted from the flat diaphragm
106. In this speaker, since the diaphragm is directly driven, resonance is unlikely to occur over a
wide frequency band, and the sound is faithful and responsive to human-powered signal current.
Be regenerated. D9 By the way, in the electromagnetic induction type speaker configured by
using the above-mentioned flat diaphragm, it is difficult to perform sound reproduction of
sufficient sound pressure over a wide frequency band . That is, in this speaker, in order to
increase the sound pressure of the reproduced sound, the signal current '' supplied to the
induction coil 108:! ! As the flow rate is increased, the amount of heat generation in the induction
coil 10B is increased.
When the amount of heat generation in the 4-conductor coil 108 increases, the electrical
resistance of the wire forming the induction coil 108 increases, and the signal current does not
easily flow. Therefore, in this speaker, it is difficult to effectively increase the sound pressure of
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the reproduction sound by increasing the amount of the signal current. Further, in the speaker,
when the heat generation amount in the induction coil 108 is increased, the entire speaker may
be heated, and thus, the speaker may be damaged. Also, the induction coil 108 acts as a bypass
filter for the signal current. Therefore, when the signal current has a frequency equal to or lower
than a so-called low cutoff frequency, the sound pressure of the reproduction sound from the
speaker is lowered. In this speaker, in order to increase the sound pressure of the reproduced
sound in the low frequency band by setting the low frequency cutoff frequency to a lower
frequency, the induction coil may be increased by, for example, increasing the number of turns.
The inductance of 108 needs to be increased. However, when the number of turns of the
induction coil 10B is increased, the electrical resistance of the induction coil 108 increases, and it
becomes difficult to supply a sufficient signal current to the induction coil 108. Therefore, the
present invention has been proposed in view of the above-mentioned circumstances, and can
reproduce sound with faithful and sufficient sound pressure to a signal manually input over a
wide frequency band, and can be driven. An object of the present invention is to provide an
electroacoustic transducer in which the accompanying heat generation is suppressed. Means for
Solving the E0 Problem In order to solve the above problems and achieve the above object, the
electroacoustic transducer according to the present invention comprises a magnetic circuit unit
for forming a direct current magnetic field and at least a part of a conductive unit. A diaphragm
including at least a part of the conductive portion positioned in the DC magnetic field and
supported to be movable back and forth; and an induction coil disposed opposite to the
conductive portion of the diaphragm, the conductive portion and the induction coil At least one
of them is made of a superconducting material. In the electro-acoustic transducer according to
the present invention, at least a part of the electro-acoustic transducer according to the present
invention is supported so as to be movable, and at least a part of the conductive part is
positioned in a DC magnetic field formed by the magnetic circuit part. In the diaphragm, when a
signal current is supplied to the induction coil disposed opposite to the conductive portion, a
secondary current by electromagnetic induction is induced in a portion corresponding to the
induction coil of the conductive portion, thereby causing direct current to flow. It receives force
from a magnetic field, vibrates and emits sound.
And, since at least one of the conductive portion and the induction coil is made of a
superconducting material, the electrical resistance for the signal current and / or the secondary
current is substantially zero, so that the amount of current can be easily made. While being able
to increase, heat generation is suppressed. G. Examples Hereinafter, specific examples of the
present invention will be described with reference to the drawings. The following example is an
example in which the electroacoustic transducer according to the present invention is configured
as a speaker. (G-1) First Embodiment (FIGS. 1 to 4) As shown in FIGS. 1 and 2, the loudspeaker
according to the present invention has a so-called external magnetic type magnetic circuit unit 1.
A flat diaphragm 7 in the form of a thin flat plate and a feed coil 9 serving as an induction coil
are attached to the magnetic circuit unit 1. The magnetic circuit portion 1 is configured to have a
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yoke 3 which is formed in a disk shape and in which a cylindrical center ball 2 is integrally
protruded at a central portion. The center ball 2 and the yoke 3 are formed of a predetermined
magnetic material such as a high magnetic permeability metal. An annular magnet 4 is disposed
around the upper surface of the yoke 3. The magnet 4 is made of, for example, a neodymiumbased material. Then, on the upper surface of the magnet 4, a top plate 5 formed in an annular
shape by the above-mentioned yoke 3 and an old-like material is disposed. The opening 5 a of
the top plate 5 is smaller in diameter than the opening 4 a of the magnet 4. Therefore, the
magnetic flux generated from the magnet 4 which is made to project slightly inward from the
inner peripheral surface 4b of the magnet 4C is indicated by an arrow B in the second row of the
inner peripheral edge 5b of the top plate 5 as shown by the arrow B. Forming a magnetic path
extending from the periphery of the yoke 3 to the magnet 4 through the center ball 2 and the
inner peripheral portion 5a of the top plate 5 from the outer peripheral surface of the center ball
2; . That is, an annular gap formed by the tip side circumferential surface of the center ball 2 and
the inner circumferential portion of the top plate 5 is formed as a magnetic gearing 6, and a
direct current whose magnetic flux is radial is formed in the magnetic gap 6. A magnetic field is
formed. The planar diaphragm 7 is attached to the magnetic circuit unit 1 configured as
described above. The flat diaphragm 7 is formed in a circular shape having a size corresponding
to the opening 4 a of the magnet 4 from a thin metal plate. As a material for forming the flat
diaphragm 7, a metal having a small specific gravity in order to make the response of the speaker
good, and a small specific resistivity so that a current can easily flow is suitable.
Such metals include aluminum, titanium, helilium, magnesium, copper or alloys thereof. The flat
diaphragm 7 is spaced above the center ball 2 at a predetermined distance from the tip surface
so as not to contact the tip surface of the center ball 2 even when it is vibrated as will be
described later. The peripheral edge is supported and attached to the inner peripheral surface 4
b of the magnet 4 via the damper member 8. The height of the center ball 2 is slightly lower than
that of the magnet 4 so that the flat diaphragm 7 can be attached. The flat diaphragm 7 is
movable back and forth in a direction substantially orthogonal to the magnetic flux in the
magnetic gap 6 as indicated by an arrow F in FIG. The damper member 8 is formed of a
predetermined material which reliably supports the flat diaphragm 7 and does not inhibit the
forward and backward movement of the flat vibration Fi 7 over a wide frequency band and in
which split resonance does not easily occur. . That is, the material forming the damper member 8
is lightweight, the specific longitudinal elastic modulus E / ? expressed by the ratio of the
longitudinal elastic modulus E to the density ? is large, and the value of the internal loss Tan ?
is appropriate. Large materials are suitable. The damper member 8 may not be used if a plurality
of concentrically formed bent portions are provided on the peripheral edge portion of the flat
diaphragm 7 to form a so-called geared shape. Also, if the plane vibration Fj, 7 is formed
sufficiently thin. The peripheral portion of the flat diaphragm 7 may be directly supported by the
inner peripheral surface 4 a of the magnet 4. Then, the feed coil 9 is disposed around the center
ball 2 and the inner circumferential surface 4 a of the magnet 4 so as to be closely opposed to
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one side of the flat diaphragm 7 located in the magnetic gear knob 6. It is supported and
provided by the partition 10 provided so that it may be passed between. That is, the feeding coil
9 is formed by winding a wire to form an annular shape, and is disposed so as to surround the
periphery on the tip end side of the center ball 2. As materials for forming the feeding coil 9,
superconducting materials such as Nb * Sn, YBazCuzuz11, or Bi-based materials such as BizSr,
CazCu, O, etc. or TI-based materials such as TI, BazCazCu, 309, etc. It is used. A signal current
based on an acoustic signal or the like is supplied to the feeding coil 9 via the one end 2 a and
the other end 2 b of the winding forming the feeding coil 9. The feed coil 9 is used at a
temperature corresponding to liquid nitrogen or liquid helium.
That is, the speaker is provided with a cooling bag 211 configured to cool the center ball 2 and
the feeding coil 9 by circulating a cooling liquid composed of liquid nitrogen or liquid helium
around the center ball 2. It is done. The cooling device 11 has a pump device 13 driven by a
drive motor 12 and delivers the cooling fluid onto the yoke 3 via a transport pipe 15 from a
storage tank 14 storing the cooling fluid. The cooling fluid delivered onto the yoke 3 circulates in
a circulation path constituted by the upper surface of the yoke 3, the peripheral surface of the
center ball 2, the inner peripheral surface 4 a of the magnet 4 and the lower surface of the
partition 10. Thus, the feed coil 9 is cooled and dissipated into the air through a predetermined
discharge hole. In addition, since the magnet 4 is formed of a neodymium-based material, the Ml
effect is reduced even if it is cooled. The cooling device 11 may be configured to recover the
cooling liquid after cooling the center ball 5 and the like in the storage tank 14 after performing
a predetermined cooling process. In the speaker according to the present invention configured as
described above, when the signal current is supplied to the feeding coil 9, the feeding coil 9
forms an alternating magnetic field of a frequency corresponding to the supplied signal current.
The AC magnetic field closely interlinks with the portion of the flat diaphragm 7 facing the feed
coil 9. Then, in the planar diaphragm 7, second-order xi is induced by electromagnetic induction
between the planar diaphragm 7 and the feeding coil 9. The secondary current is the ring-shaped
portion including the portion facing the feeding coil 9 in the planar diaphragm 7, that is, the
magnetic coupling portion 7a where the AC magnetic field formed by the feeding coil 9
interlinks. Circulate so as to increase the current density. The current density of the secondary
current is low at the central portion and the peripheral portion of the flat diaphragm 7. The
secondary current has a frequency corresponding to the signal current. The portion through
which the secondary current flows is positioned in the magnetic gap 6, and therefore, the driving
force is received by the DC magnetic field formed in the magnetic gap 6, and the flat diaphragm
7 is driven to vibrate. Do. Then, this vibration is emitted as reproduction sound. And in this
speaker, since the feeding coil 9 is formed of a superconducting material, the electrical resistance
of the signal current is substantially zero, and the amount of the signal current can be efficiently
increased easily. Can.
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Further, in this speaker, the heat generated by the signal current is substantially zero. Further,
since the electrical resistance of the feed coil 9 is substantially zero, this speaker can be driven
by a so-called constant current drive amplifier. If this speaker is driven by a constant current
drive amplifier, the current supplied to the feeding coil 9 is made constant over a wide frequency
band, and sound reproduction having good frequency characteristics can be performed. Further,
in the speaker, the feeding coil 9 may be formed of a conductive material such as copper, and the
flat diaphragm 7 may be formed of a superconducting material. In this case, as shown in FIG. 3,
the cooling device 11 has the cooling liquid in the above-mentioned plane through the through
hole 16 provided on the top plate 5 so as to extend from the outer peripheral side to the inner
peripheral side. It is configured to be sent around the diaphragm 7. Furthermore, in the speaker,
both the feeding coil 9 and the flat diaphragm 7 may be formed of a superconducting material.
By the way, in this speaker, a magnetic fluid groove may be provided between the feeding coil 9
and the flat diaphragm 7. The magnetic fluid is a mixture of a predetermined solvent and
magnetic powder in the form of a colloidal solution. This magnetic fluid makes the magnetic
coupling between the feeding coil 9 and the flat diaphragm 7 more dense and makes the 1iis
induction between them more efficient. Further, since the magnetic fluid has viscosity, it gives
predetermined attenuation to the reciprocating motion of the flat diaphragm 7 in the forward
and backward directions. Then, since the magnetic fluid is removed by the cooling device 11, it is
held at a predetermined place without volatilization. The speaker according to the present
invention is not limited to one including the annular magnet 4 and the circular flat diaphragm 7
as described above, and may be configured using a rectangular frame-shaped magnet and a
rectangular flat diaphragm. Alternatively, it may be configured using a flat diaphragm of another
shape. Further, the diaphragm of the speaker according to the present invention is not limited to
the above-described planar vibration, but a dome-shaped diaphragm may be used which is
formed in a dome shape by a thin flat plate. Furthermore, the magnetic circuit portion for
constituting the speaker according to the present invention is not limited to the so-called external
magnet type as described above, and is a so-called so-called magnet type configured to have a
spring type yoke and a cylindrical magnet. It may be of the internal magnet type. Further, as
shown in FIG. 4, an equalizer 40 is disposed on the flat diaphragm 7, and a horn 41 is attached to
the top plate 5 to use this speaker as a so-called horn driver. It is also good.
In this case, the heat generation of the flat diaphragm 7 is dissipated through the equalizer 40,
the horn 41 and the like, and the flat diaphragm 7 can be more favorably dissipated. (G-2)
Second Embodiment (FIG. 5) As shown in FIG. 5, the loudspeaker according to the present
invention is a magnetic circuit in which a pair of magnetic gearings are formed on both sides of a
pole piece. You may comprise using a part. That is, as shown in FIG. 5, this magnetic circuit
portion is configured to have a rectangular yoke 18 in which a pole piece 17 having a
rectangular cross section is integrally protruded. A pair of first and second rod-like magnets
1920 are attached on the yoke one day so as to face both side surfaces of the pole piece 17,
respectively. Plate-shaped first and second pair of top plates 21.22 are correspondingly attached
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to the upper surfaces of the pair of magnets 19 and 20, respectively. In this magnetic circuit
portion, the gap between the pole piece 17 and the first top plate 21 and the gap between the
pole piece 17 and the second top plate 22 are respectively the first and the second. It becomes a
magnetic gap of 2. In this speaker, a rectangular flat diaphragm 23 is mounted on the upper side
of the pole piece 17 at a predetermined distance from the upper face of the pole piece 17 so as
not to contact the upper face of the pole piece 17 . The height of the pole piece 17 is slightly
lower than that of the pair of magnets 19.20 so that the flat diaphragm 23 can be attached. The
flat diaphragm 23 is formed of the same material as the circular flat diaphragm 7 described
above. The flat diaphragm 23 is supported by the pair of magnets 19.20 on two sides parallel to
both side surfaces of the pole piece 17, and moves back and forth in a direction perpendicular to
the magnetic flux in the first and second magnetic gaps. It is attached to be free. Further, the
sides of the flat diaphragm 23 which are both end sides of the pole piece 17 are attached to and
supported by a pair of support plates 24. The support plates 24 are attached on the yoke 18 so
as to be fitted between the one end side and the other end side of the respective magne 7) 19.20,
and the support plate 24 is mounted on the back side of the flat diaphragm 23 The space is
almost sealed. Then, a substantially rectangular feeding coil 25 formed of a superconducting
material is closely opposed to the portion of the flat diaphragm 23 located in the first and second
magnetic gaps so as to surround the pole piece 17. Are arranged.
The feed coil 25 is attached to a partition wall 26 provided so as to extend between the pole
piece 17 and the magnets 19 ░ 20. And this feed coil 25 is made to use salinity equivalent to
liquid nitrogen or liquid helium. That is, the cooling device 11 is provided in this speaker as in
the case of the speaker in the first embodiment described above. The cooling device 11 delivers
the coolant onto the yoke 18 through the transport vibrator 15 from a storage tank 14 for
storing the coolant. The cooling fluid delivered onto the yoke 18 forms a circulation path
constituted by the upper surface of the yoke 18, the circumferential surface of the pole piece 17,
the inner surface of the magnetic members 19.20, and the lower surface of the partition 26. By
circulating, the feed coil 25 is cooled and dissipated into the air through a predetermined
discharge hole. In order to reproduce the sound by the loudspeaker shown in FIG. 5, a signal
current based on an acoustic signal or the like is supplied to the feeding coil 25 as in the
loudspeaker in the first embodiment described above. Then, the feeding coil 25 forms an
alternating magnetic field of a frequency corresponding to the supplied signal current, and a
secondary current is induced in the planar diaphragm 23 by the alternating magnetic field. The
interaction between the secondary current and the DC magnetic field formed by the magnets
19.20 excites the planar diaphragm 23 to radiate sound. (G-3) Third Embodiment (FIG. 6 and FIG.
7) Further, as shown in FIG. 6, the loudspeaker according to the present invention is a conductive
polymer film having conductivity of the flat diaphragm 27. It may be formed by That is, this
speaker is provided with a so-called external magnet type magnetic circuit unit 1 similarly to the
speaker in each of the embodiments described above. The magnetic circuit portion 1 is composed
of a yoke 3 provided with a center ball 2, an annular magnet 4 and an annular top plate 5, and
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the tip end side of the center ball 2 and the inner peripheral edge of the top plate 5. Annular gap
force between the part 5b (fri! It is made to be a gamble 6. A flat diaphragm 27 formed to
correspond to the opening 9114 a of the magnet 4 is attached to the magnetic circuit portion I.
The flat diaphragm 27 is formed of a conductive polymer film so as to have conductivity likeover the entire surface. The flat diaphragm 27 is spaced upward from the center ball 2 by a
predetermined distance so as not to contact the tip end face of the center ball 2, and its
peripheral portion is supported by the inner circumferential surface 4b of the magnet 4 to
advance and retract. It is attached to be free.
The conductive polymer film constituting the flat diaphragm 27 is a film formed of a material
obtained by mixing carbon, metal powder or the like in a polymer material. Further, for example,
a film made of a material obtained by doping iodine in a polyacetylene haze to have conductivity
can also be used. A feed coil 9 made of a superconducting material is passed between the
periphery of the center ball 2 and the inner circumferential surface 4 a of the magnet 4 so as to
face the portion of the flat diaphragm 27 located in the magnetic gap 6. It is supported and
arranged by the partition 10 provided in this way. Further, similarly to the speaker in each of the
above-described embodiments, a circulation path formed by the upper surface of the yoke 3, the
circumferential surface of the center ball 2, the inner circumferential surface 4a of the magnet 4
and the lower surface of the partition 10. A cooling device 11 is provided which cools the feeding
coil 9 by circulating the cooling fluid. In the speaker configured as described above, when a
signal current based on an acoustic signal or the like is supplied to the feeding coil 9, the feeding
coil 9 forms an alternating magnetic field of a frequency according to the signal current supplied,
The alternating current magnetic field induces a secondary current in the planar vibration Fi21.
The interaction between this secondary current and the direct [one field formed in the magnetic
gap 6 excites the planar diaphragm 27 to emit sound. In this speaker, since the flat diaphragm
27 is formed of a polymer material, the mechanical loss in the flat diaphragm 27 is relatively
large and can be made light. Therefore, there is no resonance at a specific frequency, and good
acoustic reproduction characteristics with good responsiveness can be realized. When the flat
diaphragm 27 is thus formed of a conductive polymer film, as shown in FIG. 7, only a
predetermined portion of the flat vibration Fi 27 may have conductivity. In this case, the planar
vibration Fi 27 is made of a conductive polymer film processed to have conductivity only in a
predetermined portion, and a position where the conductive portion faces the feeding coil 9 It is
attached to the said magnetic circuit part 1 so that it may become. In the speaker configured as
described above, only the magnetic coupling portion 27 a facing the feeding coil 9 has
conductivity in the plane vibration Fi 27. In the speaker configured as described above, the
induction of the surface layer current (so-called skin effect) in the portion other than the
magnetic coupling portion 27a is prevented, and the secondary current is concentrated only in
the magnetic coupling portion 27a. Is further improved.
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Also in this speaker, the flat diaphragm 27 can be formed not only in a circular shape but also in
a rectangular shape or other shapes. Further, as shown in FIG. 5, a magnetic circuit unit may be
used in which magnetic gear pumps are formed on both sides of the pole piece. Furthermore, the
magnetic circuit portion for constituting this speaker is not limited to the so-called external
magnet type, but it may be a so-called internal magnetic type 1 ░ and this speaker can also be
used as a so-called horn driver . (G-4) Fourth Embodiment (FIG. 8 and FIG. 9) In the loudspeaker
according to the present invention, in the case where only the magnetic coupling portion of the
flat diaphragm has conductivity, the speaker has high insulation properties. You may comprise
using the plane diaphragm by which the conductor plate of a defined shape is attached to a
molecular film. That is, as shown in FIG. 8, this speaker is provided with a so-called externalmagnet-type magnetic circuit unit 1 like the speakers in the above-described embodiments. The
magnetic circuit portion 1 is composed of a yoke 3 provided with a center pole 2, an annular
magnet 4 and an annular top plate 5, and the tip end of the center ball 2 and the inner peripheral
edge of the top plate 5. An annular gap between the portion 5 b and the portion 5 b is a magnetic
gap 6. A planar diaphragm 28 is attached to the magnetic circuit portion 1 above the center pole
2 at a predetermined distance from the top surface so as not to contact the top surface of the
center ball 2. The flat diaphragm 28 has a peripheral edge portion supported by the inner
circumferential surface 4 b of the magnet 4 and is attached so as to be movable back and forth in
a direction perpendicular to the magnetic flux in the magnetic gap 6. The flat diaphragm 28 is
formed of a metal, a conductive polymer film, or a superconducting material on one surface of a
diaphragm main body 28 a formed in a shape corresponding to the opening 4 a of the magnet 4
from an insulating polymer film. The first conductor plate 29 is attached and configured. The
attachment of the first conductor plate 29 to the diaphragm main body 22 is made by bonding
using an adhesive or the like. The first conductor plate 29 is formed in a shape corresponding to
the magnetic gearing 6 and is attached at a position in the magnetic gap 6 of the diaphragm
main body 22. The feed coil 9 is supported by the partition wall 10 provided so as to extend
between the periphery of the center ball 2 and the inner circumferential surface 4 a of the
magnet 4 so as to face the first conductor plate 29. Being arranged.
Also, like the speakers in the above-described embodiments, an i-ring comprising the upper
surface of the yoke 3, the peripheral surface of the center pole 2, the inner peripheral surface 4a
of the magnet 4 and the lower surface of the upper partition wall 10 A cooling device ii is
provided to cool the feeding coil 9 by ringing the coolant with W1. In the speaker configured as
described above, when a signal current based on an acoustic signal or the like is supplied to the
feeding coil 9, the feeding coil 9 forms an alternating magnetic field of a frequency according to
the signal current, and this alternating current is generated. A secondary current is induced in
the first conductor plate 29 constituting the planar diaphragm 28 by the magnetic field. The
interaction between the secondary current and the DC magnetic field formed in the magnetic gap
6 excites the flat diaphragm 28 to emit sound. Further, as shown in FIG. 9, the flat diaphragm 28
is formed on one surface and the other surface of the diaphragm main body 28a in the same
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manner as the first vibrating conductor plate 29 and the first conductor plate, respectively. The
second conductor plate 30 may be attached and configured. Thus, also in the speaker in which
the flat diaphragm 28 is constituted by the diaphragm body 28a and the conductor plate
attached to one side or both sides of the diaphragm body 28a, the flat diaphragm 28 is not only
circular but also rectangular. And other shapes can be formed. Further, this speaker is configured
using a so-called internal magnetic type magnetic circuit unit and a magnetic circuit unit
configured such that magnetic gaps are formed on both sides of the pole piece as shown in FIG.
May be Also in this speaker, this speaker can be used as a horn driver. (G-5) Fifth Embodiment
(FIG. 10 and FIG. 11) And, when the loudspeaker according to the present invention is
constructed by using a planar diaphragm having conductivity on the entire surface, You may
comprise so that the reiki resistance per area may change with parts. That is, as shown in FIG. 10
and FIG. 11, this speaker is provided with a so-called external-magnet-type magnetic circuit unit
1 similarly to the speakers in the above-described embodiments. The magnetic circuit portion 1
is composed of a yoke 3 provided with a center pole 2, an annular magnet 4 and an annular top
plate 5, and the tip side of the center pole 2 and the inner periphery of the top plate 5. An
annular gap between the surface and the surface is a magnetic gap 6. A flat diaphragm 31 is
attached to the magnetic circuit portion l.
The flat diaphragm 31 is formed of a metal plate in a shape corresponding to the opening 4 a of
the magnet 4. The flat diaphragm 31 is disposed on the upper side of the center ball 2 at a
predetermined distance from the upper surface so as not to contact the upper surface of the
center ball 2, and the peripheral portion is the inner periphery of the magnet 4. It is supported
on the surface 4 b via the damper member 8 and is mounted so as to be able to move forward
and backward. A feed coil 9 made of a superconducting material is disposed between the
periphery of the center pole 2 and the inner circumferential surface 4 a of the magnet 4 so as to
face the portion of the flat diaphragm 3I located in the magnetic gap 6. It is supported and
arranged by the partition 10 provided so that it might cross. Further, similar to the speaker in
each of the above-described embodiments, in the circulation path constituted by the upper
surface of the yoke 3, the circumferential surface of the center ball 2, the inner circumferential
surface 4a of the magnet 4 and the lower surface of the partition wall IO. A cooling device 111 is
provided to cool the feeding coil 9 by circulating a liquid. In the flat diaphragm 31, only the
magnetically coupled portion 31a in which the magnetic field generated by the feed coil 9
including the portion facing the feed coil 9 is closely interlinked reduces the electric resistance
per area. It is formed thick. As described above, in order to form only the magnetic coupling
portion 31a of the flat diaphragm 31 to be thick, the diaphragm main body 31b made of a flat
metal plate is made of the same or different material as the diaphragm main body 31b. A platelike member 31c made of a metal or a superconducting material having a shape corresponding to
the shape of the feeding coil 9 is attached by means such as bonding using a conductive
adhesive. Thus, as shown in FIG. 10, the plate-like member 31c attached to make the magnetic
coupling portion 31a thick may be attached only to one side of the diaphragm main body, or, as
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shown in FIG. It may be mounted on both sides as shown. In the speaker configured as described
above, when a signal current based on an acoustic signal or the like is supplied to the feeding coil
9, the feeding coil 9 forms an alternating magnetic field of a frequency according to the signal
current, and this alternating current is generated. A secondary current is induced in the magnetic
coupling portion 31 a of the flat diaphragm 31 by the magnetic field. The interaction between
the secondary current and the DC magnetic field formed in the magnetic gear knob 6 excites the
flat diaphragm 31 to radiate sound. In this speaker, by making only the magnetic coupling
portion 3Ia thick, the electrical resistance per area of the magnetic coupling portion 31a is
reduced, and the secondary current is more easily made to flow. .
Therefore, in this speaker, when the secondary current flows more, the flat diaphragm 3I is
driven with a stronger force, the sensitivity is improved, and the sound pressure of the
reproduction sound is increased. When the plate-like member 31c attached to the magnetic
coupling portion 31a is formed of metal, the plane vibration plate 31 is formed of, for example, a
material having a very low specific resistivity, such as gold or silver. It is possible to reduce the
electric resistance of the magnetic coupling portion 31a while suppressing the increase of the
total weight 1 of the flat diaphragm 31. Further, in order to make only a predetermined portion
of the flat diaphragm 31 thick, a predetermined metal is formed on one side or both sides of the
flat plate body 31b of the flat vibration Fi 31 by means such as plating or vapor deposition
(sputtering). Materials may be written or glued. Furthermore, the planar diaphragm 31 is
relatively thinned by increasing the electrical resistivity per area by thinning the portion other
than the magnetic coupling portion 31a by means of so-called cutting or machining. The
magnetic coupling portion 31a may be configured to be thick and to reduce the electrical
resistance. In this case, the flat diaphragm 31 can be configured to have a sufficient thickness for
reducing the electrical resistance of the magnetic coupling portion 31a, and can be configured to
be lightweight as a whole. Therefore, by configuring the flat diaphragm 31 in this manner, the
sensitivity of the speaker configured using the flat diaphragm 31 can be improved. Furthermore,
in the flat diaphragm 31, in order to increase the electrical resistivity of the portion other than
the magnetic coupling portion 31a, the oxide n? may be formed in the portion where the
electrical resistivity is desired to be increased. The more the oxide film is formed over a portion
deeper than the surface of the flat diaphragm 31, the larger the effect of increasing the electric
resistance. In this case, in the plane diaphragm 31, induction of surface layer current (so-called
skin effect) in the portion other than the GR magnetic coupling portion 31a is prevented, and the
secondary current is concentrated only in the magnetic coupling portion 31a. . Therefore, in the
speaker configured using the flat diaphragm 31 configured as described above, the driving
efficiency is further improved. Also in this speaker, the plane diaphragm 31 may be formed not
only in a circular shape but also in a rectangular shape or any other shape. Further, the speaker
may be a so-called internal magnet type magnetic circuit unit or the FIG. As shown in the above,
the magnetic piece may be configured to have magnetic gearing formed on both sides of the pole
piece, and this speaker can also be used as a horn dry eight.
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(G-6) Sixth Embodiment (FIGS. 12 to 14) The second and third examples of the speaker according
to the present invention are also i! ! In the example, as shown in FIG. 6 and FIG. 8, in the case
where only a predetermined portion of the flat diaphragm is made to be the conductive portion,
the conductive portion is a closed loop having a helical portion. It may be That is, in this example,
as shown in FIG. 12, in the flat diaphragm 2728, a conductive portion 32 provided by processing
to have conductivity or attachment of a conductive plate is formed on one surface of the flat
diaphragm 2728. It is formed and configured to draw a spiral shape. The conductive portion 32
is formed to be located in a magnetic coupling portion including a portion facing the feeding coil
9 of the flat diaphragm 27.28. The conductive portion 32 has the one end 32a and the other end
32b facing the other surface of the flat diaphragm 27.2, and the other end 32a, 32b is a shorting
member 33 on the other surface. A short circuit is formed to form a closed loop. When a speaker
is configured using a flat diaphragm 27. 28 in which a portion having such conductivity has a
helical portion, in this speaker, the secondary current is applied to a coil having a plurality of
turns. Thus, the plane diaphragm 27.28 can be driven more efficiently. That is, in this speaker,
assuming that the force for driving the flat diaphragm 27. 28 is F, the strength of the DC
magnetic field formed by the magnetic circuit unit 1 is B, and the amount of the secondary
current is Assuming that the length of the flowing portion of the secondary current in the DC
magnetic field is 2, F = B I j! Relationship is established. If the strength B of the direct current
magnetic field and the "S @ amount of the secondary xtl" are constant, the force F for driving the
flat diaphragm 27. 28 is proportional to the length l. In the above-described speaker, the length i
is made longer by the spiral shape of the conductive portion 32, and the size of driving the flat
diaphragms 27, 28 is increased. In addition, the conductive portion of the flat diaphragm 27. 28
of the speaker may be formed of a plurality of closed loops. That is, in this example, as shown in
FIG. 13, the flat diaphragm 27.28 has a plurality of four ridges 34 provided by processing to
have conductivity or attachment of a conductor plate, the flat vibration Closed plates are formed
on one side or both sides of the plate 27.28 so as to be concentric with each other.
The conductive portions 34 are formed so as to be located in the magnetic coupling portion
including the portion of the planar diaphragm 27.28 facing the feeding coil 9, respectively. When
the speaker is configured using the flat diaphragm 27. 28 configured in this way, the same action
as flowing the secondary current through the coil having a plurality of turns can be obtained.
That is, in this speaker, by lengthening the length i in the DC magnetic field of the portion
through which the secondary current flows, the force F for driving the planar diaphragm 27. 28
is made large, and the planar diaphragm 27.28 is driven more efficiently. Furthermore, the
planar vibration FL27.28 of the above-mentioned speaker may be formed and configured so that
the conductive portions are formed of a plurality of closed loops spaced apart in parallel with
each other. That is, as shown in FIG. 14, in the flat diaphragm 27.28, a plurality of conductive
parts 35 provided by processing to have conductivity or attachment of a conductive plate is the
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same as that of the flat diaphragm 27.28. They are formed in parallel and spaced apart from
each other so as to form a closed loop on one side or both sides, respectively. The conductive
portions 35 are formed so as to be located in the magnetic coupling portion including the portion
of the planar vibration Fi 27.28 facing the feeding coil 9, respectively. When the speaker is
configured using the flat diaphragm 27.28 configured in this way, in this speaker, the same
action as flowing the secondary current through the coil having a plurality of turns is obtained,
The planar vibration Fi 27. 28 can be driven more efficiently. The electroacoustic transducer
according to the present invention can be configured not only as a speaker but also as a
microphone as in the above-described embodiments. When the electroacoustic transducer
according to the present invention is configured as a microphone, in this microphone, the planar
diaphragm is vibrated by air vibration that is propagated as sound from the outside, and the
vibration of the planar diaphragm and the DC magnetic field The interaction with this induces an
electric current in the planar diaphragm. The current induced in the planar diaphragm is
transmitted to the induction coil by fir11 induction. And in this microphone, an acoustic
detection output is obtained from the both ends of the above-mentioned induction coil. Further,
on each side described above, by appropriately providing through holes etc. in the yoke,
adjustment of air elasticity on the back side of the flat diaphragm when configured as a speaker
or directivity when configured as a microphone Adjustments can be made.
As described above, in the electro-acoustic transducer according to the present invention, as
described above, a signal is sent to the induction coil opposed to the above-mentioned conductive
portion of the diaphragm at least a part of which is made the conductive portion and supported
to advance and retract. By supplying a current, a secondary current due to electric fdl1M
conduction is generated in the portion corresponding to the induction coil of the conductive
portion, and the whole diaphragm is vibrated by the action of the secondary current and the DC
magnetic field to produce acoustics. It can be played back. That is, when the electroacoustic
transducer according to the present invention is configured as a speaker, the diaphragm can be
directly driven to perform acoustic reproduction of good characteristics without causing
resonance or distortion. And, since at least one of the conductive part of the diaphragm and the
induction coil is made of a superconducting material, the electrical resistance for the signal
current and / or the secondary current is substantially zero, and the amount of current is easy
The heat generation can be quickened. That is, according to the present invention, faithful sound
reproduction without resonance or distortion can be performed with a sufficient sound pressure
over a wide frequency band, and heat generation accompanying driving can be suppressed. An
electroacoustic transducer can be provided.
[0002]
Brief description of the drawings
13-05-2019
13
[0003]
FIG. 1 is a partially broken perspective view showing the construction of a first embodiment in
which the electro-acoustic transducer according to the present invention is configured as a
speaker, and FIG. 2 shows the construction of the electro-acoustic transducer FIG. 3 is a
longitudinal sectional view, FIG. 3 is a longitudinal sectional view showing another example of
the configuration of the above-mentioned electroacoustic transducer, and FIG. 4 is a longitudinal
sectional view showing a state in which this electric N acoustic transducer is used as a horn
driver FIG.
FIG. 5 is a perspective view showing a partially broken view of the configuration in the second
embodiment in which the electroacoustic transducer according to the present invention is
configured as a speaker using a magnetic circuit different from the first embodiment. is there.
FIG. 6 is a longitudinal sectional view showing the construction of the third embodiment in which
the electroacoustic transducer according to the present invention is configured as a speaker, and
FIG. It is a longitudinal cross-sectional view which shows the example of. FIG. 8 is a longitudinal
sectional view showing the construction of the fourth embodiment in which the electro-acoustic
transducer according to the present invention is constructed as a speaker, and FIG. 9 is another
construction of this embodiment of the electric sound 9 converter. It is a longitudinal crosssectional view which shows the example of. FIG. 10 is a longitudinal sectional view showing the
construction of the fifth embodiment in which the electro-acoustic transducer according to the
present invention is configured as a speaker, and FIG. 11 is another embodiment of the electroacoustic transducer described above. It is a longitudinal cross-sectional view which shows an
example. FIG. 12 is a plan view showing the configuration of a flat diaphragm in a sixth
embodiment in which the electro-acoustic transducer according to the present invention is
configured as a speaker, and FIG. 13 is a plan view of this embodiment of the electro-acoustic
transducer FIG. 14 is a plan view showing another example of the configuration of the
diaphragm, and FIG. 14 is a plan view showing still another example of the configuration of the
planar diaphragm in this embodiment of the electric sound V converter. FIG. 15 is a longitudinal
sectional view showing the configuration of a conventional electromagnetic induction type
speaker having a flat diaphragm. l иииииииииииииииииииииииииииииииииииииииииииииииииииииииииииии ииииииииииииииииииииииииииииииииииииииииииииииииииииииииииии
иииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииии ........ 30 ............... magnetic circuit magnetic gap flat diaphragm
feeding coil flat diaphragm feeding coil flat diaphragm flat diaphragm diaphragm body first
Conductor plate second conductor plate 1 ........... 2 ........... 4 .....
иииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииии иии
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