JP2003023685

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DESCRIPTION JP2003023685
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
general-purpose speaker capable of faithfully reproducing an acoustic signal for personal
computers, vehicles, BGMs, etc., and for appropriately diffusing directivity. On how to form a soft
sound field.
[0002]
2. Description of the Related Art An audio speaker is a transducer that receives an acoustic
current to generate a sound wave, and generally has a dynamic transducer and a radiation
portion that radiates the vibration of a vibrator as a sound wave. The cones and domes are used
for the small size in this radiation part, and the horn is used for the large size. This type of
speaker often uses a combination of several speakers with different diameters for sound
generation over a wide frequency band, and it is very expensive and requires a large footprint for
high-end products.
[0003]
[0003] On the other hand, since speakers for personal computers and vehicles are naturally
limited in their installation area, relatively small cone speaker units are often used. In this type of
speaker, the cone paper of the speaker unit vibrates acoustically to generate a sound wave, and
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this mechanical vibration is transmitted from the baffle plate and is further transmitted to the
box so that the whole box is easily rocked. When such a box swing occurs, the low frequency of
the sound generated from the cone paper is canceled, and the low frequency range is not
accurately reproduced, resulting in the low frequency range becoming dull or blurred.
[0004]
In the prior art, a free edge is attached between the frame of the speaker unit and the cone paper
in order to prevent the swinging of the box in a small speaker, and the cone paper is easily
moved by the free edge. And absorbs mechanical vibration of corn paper. Since this free edge is
not completely effective, but can not completely absorb mechanical vibration of the cone paper,
some vibration is transmitted to the frame of the speaker unit, and this vibration is transmitted
from the baffle plate to the box and the whole box Swing.
[0005]
The present inventor has continued research on a porous sintered body invented by the present
invention, and this porous sintered body is a metal material having a rough surface and having a
rigid surface, and metal strips of cast iron and aluminum are electrically It is manufactured by
direct current heating and pressurization. This porous sintered body is a hard material different
from conventional glass wool or felt as a sound absorbing material for absorbing sound waves
having a large frequency of energy, and has the same vibration damping property as that of the
vibration proof rubber. It pays attention and it came to think about applying this as a member for
speakers.
[0006]
Therefore, the present invention is proposed to solve the above-mentioned problems with
conventional small speakers, and in particular provides a general-purpose speaker capable of
clearly reproducing an acoustic signal and a bass range. The purpose is that. Another object of
the present invention is to provide a general-purpose speaker which appropriately diffuses the
directivity of the generated sound without losing the sound quality even when the indirect sound
component is present even in the highly directional frequency band. Another object of the
present invention is to provide a speaker mounting method in which the audible sound in the car
is mainly indirect sound of the inner wall of the car and the interference between the sound
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waves is reduced to form a soft sound field.
[0007]
SUMMARY OF THE INVENTION In order to achieve the above object, a general-purpose speaker
according to the present invention comprises a speaker unit on which an acoustic output signal
of an amplifier acts, a baffle plate for mounting a frame of the speaker unit, The present
invention is also applicable to a woofer or the like, including a cabinet that constitutes a speaker
box together with a baffle plate. In the present invention, even if the baffle plate itself is a porous
sintered body in which the pores on the outer surface are sparse and the pores inside are dense,
it is between the speaker unit and the baffle plate or between the baffle plate and the cabinet.
The mount member to be interposed may be a porous sintered body in which the pores on the
outer surface are sparse and the pores inside are dense.
[0008]
In the general-purpose speaker according to the present invention, the porous sintered body of
the baffle plate or the mount member absorbs the mechanical vibration transmitted to the frame
of the speaker unit to make the faithful reproduction of the acoustic signal and the bass region
clear. Reproduce. The general-purpose speaker of the present invention incorporates one or two
speaker units in a cabinet, and when the two speaker units are in series, the acoustic signal can
be reproduced more faithfully and the bass range can be reproduced more clearly.
[0009]
The general-purpose speaker of the present invention preferably includes an acoustic lens
attached to the front of the speaker. This acoustic lens is made of hard and rough metal foam
with a thickness of several mm, and the metal foam is plastically deformed in a convex shape to
control the intensity distribution and phase of the sound source, thereby appropriately diffusing
the directivity of the generated sound Let
[0010]
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The speaker mounting method of the present invention comprises a speaker unit, a baffle plate
for mounting a frame of the speaker unit, and a cabinet which constitutes a speaker box together
with the baffle plate and incorporates one or two speaker units. The two speakers will be
downsized for the car, and both speakers will be installed horizontally or upward below the
driver's seat and the front passenger's seat of the car. The orientations of both speakers are
horizontal forward, showing the sound diagram as shown in FIG. 19, and can be from horizontal
to vertically upward, and the position of the virtual sound image shifts upward according to the
orientation of the speakers. Due to the two speakers, the audible sound in the car mainly consists
of indirect sound and forms a soft sound field.
[0011]
In this speaker attachment method, the baffle plate used in the two speakers is a porous sintered
body, or the porous sintered body between the speaker unit and the baffle plate or between the
baffle plate and the cabinet It is preferable to interpose the mounting member of With the two
speakers having such a structure, the audible sound in the car mainly consists of indirect sound
in the inner wall of the car, and the low frequency range of the generated sound is sufficiently
reproduced to form a soft sound field.
[0012]
More preferably, an acoustic lens made of a hard and rough metal foam with a thickness of
several mm is mounted on the front of the speaker. By plastically deforming this metal foam in a
convex shape and controlling the intensity distribution and phase of the sound source, the
directivity of the generated sound is appropriately diffused in the automobile.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION The general-purpose speaker 1 according to
the present invention is for personal computer, car, BGM, general audio, etc., and the speaker
may be a woofer, and the narrow space is limited. It is compact enough to be installed on the
market, and its structure is relatively simple and inexpensive. In the present invention, the
radiating portions of the speaker unit may be either a cone, a dome or a horn, and the speaker
box including the baffle plate may be referred to as an enclosure.
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[0014]
In the general-purpose speaker 1 or woofer of the present invention, as shown in FIG. 1, a porous
sintered body 3 (see FIG. 4) is used for the baffle plate 2 or a mount member 5 as shown in FIG. ,
7 apply a porous sintered body. The porous sintered body 3 is formed into a flat plate shape by
electric current heating and pressure, and then adhered or bolted as the baffle plate 2 or the
mounting members 5 and 7. The mount members 5 and 7 are usually an annular body having a
rectangular cross section or L-shaped cross section as shown in FIG. 2, but even if only a part of
this annular body is a porous sintered body, the plate pieces are circular It may be distributed
only in the circumferential direction.
[0015]
The porous sintered body 3 is generally formed into a flat plate shape by current heating and
pressure using metal chips with a particle diameter of 6 to 50 mesh, and at the time of this
molding, the surfaces of the respective metal chips melt and the chips As they fuse together and
heat escapes into the sintered body and cools, the pores of the outer surface 10 become sparse
and the pores of the internal 8 become dense (see FIG. 4). For example, when a low frequency
sound wave with high energy strikes the porous sintered body 3 as shown by the arrow in FIG. 4,
it is sucked into the depression into the outer surface 10 of the coarse pores and compressed in
the inside 8 of the dense mechanism. It is done and it escapes to the outside as very minute heat.
[0016]
The porous sintered body 3 is manufactured from one or more types of metal chips having a
particle size of 6 to 50 mesh. The metal chip is metal powder or chips (dalai powder) or the like,
and an alloy having a two-metal component may be mixed, or a plurality of metal chips different
in shape and type may be mixed. As the metal chips, iron-based metals such as cast iron cuttings,
carbon billets, stainless steel billets, aluminum powders, aluminum-based metals such as Al-Si
alloy cutting scraps, titanium-based metals such as copper-based metals and titanium powders
Etc. can be illustrated. The porous sintered body 3 may contain 25% by weight or less of glass
particles, ferrite powder, cement powder and / or thermosetting resin in the mixture of metal
chips. The thermosetting resin is an epoxy resin, a polyester resin, a urethane resin, a phenol
resin, a diallyl phthalate resin or the like, and can be added by being mixed with other additives.
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[0017]
The porous sintered body 3 is manufactured, for example, by a molding apparatus (not shown)
having a square cylindrical mold, and the mixed metal chips are filled in the mold. In this forming
apparatus, a pair of rectangular electrode plates having the same surface area are installed
opposite to each other on a horizontal ceramic plate, and a pair of rectangular heat-resistant side
walls are installed orthogonal to this to form a mold It is formed. The wire from the low voltage
transformer is connected to the side end of one electrode plate, and the wire is also connected to
the opposite side end of the other electrode plate. The metal chip is placed almost uniformly in a
mold, then the press die is lowered, and a high current of several thousand amperes is applied for
heating and pressing to form a flat plate.
[0018]
In the above-mentioned forming apparatus, at the time of sintering, a metal chip is subjected to a
high current of up to 8000 amperes for thermoforming, and the voltage is usually 20 volts. At
this time, even if the heating temperature reaches about 1000 ° C. in the mold, flowing a high
current hardly causes volume diffusion, causing phenomena such as spheroidization of voids and
reduction or disappearance of microvoids. Instead, they are partially melted and bonded to each
other at the contact between the metal chips. In the porous sintered body, even if a small amount
of ceramic or synthetic resin is contained in addition to the metal chip, sound absorption can be
sufficiently maintained even after molding.
[0019]
The molded sintered plate obtained is sufficiently porous when the additive is at most about 10%
by weight, and at 10 to 25% by weight the vibration absorption and the sound absorbing
properties are slightly reduced. In the porous sintered body 3, the content of the metal chip is
usually about 75% by weight or more of the total amount, and preferably about 90% by weight or
more in a speaker application requiring particularly high vibration absorption and sound
absorption.
[0020]
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Even if the molded sintered plate thus obtained is finished into a rectangular plate provided with
a central hole and used for the baffle plate 2, if it is small like the mount members 5 and 7, it is
appropriately cut and then single-sided Alternatively, both surfaces may be finish-polished and a
plurality of sheets may be used in combination in a ring shape. In addition, as the baffle plate 2
or the mounting members 5 and 7, a thin covering layer having a thickness of several mm may
be provided on the surface of the sintered plate. In the baffle plate 2 or the mounting members 5
and 7, the thin coating layer is made of synthetic resin, metal or general purpose ceramic and
covers the whole or a part of the porous sintered plate. General-purpose ceramics include
concrete materials, glass materials, pottery, porcelain, tiles, tile sheets and the like.
[0021]
As desired, in the general-purpose speaker 1, a convex plastically deformed metal foam 26 is
attached so as to cover the cabinet 12, that is, the front surface of the baffle plate 2. The metal
foam 26 may be interpreted as a metal plate in which irregular and huge pores having a
thickness of several millimeters are formed throughout. The metal foam 26 is usually made of
nickel with little shielding of electromagnetic waves, and where metal shielding is needed, metal
corresponding to it is used. The metal foam 26 has an apparent density of 1.0 or less, and a large
number of elongated metal filaments extend randomly in the width direction and combine to
form a steric, relatively hard mesh shape as a whole, as illustrated in FIG. Can be manufactured
by such a plating reactor 28.
[0022]
As shown in FIG. 7, the measurement of the speaker characteristics applied in the present
invention is performed not by the conventional steady state sweep method but by the pulse input
method. In the steady state sweep method, only the level fluctuation of each frequency is used as
the speaker characteristic, whereas in the pulse input method, measurement is performed in the
time domain. In the pulse input method, as shown in FIG. 13 and FIG. 21 to FIG. 23, when using
the FFT method, the speaker characteristics include not only the pulse response in the time
domain (a) but also phase information if the reference level is the same. It is possible to compare
the transfer functions in the frequency domain (b). For the input signal, a square wave pulse with
a time width of 50 microseconds is used. This signal has flat characteristics up to about 10 kHz
in the frequency domain, and then drops sharply at 20 kHz.
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[0023]
A rectangular wave pulse of an input signal recorded on a CD-ROM is amplified by an audio
amplifier and supplied to a speaker. Sound waves emitted from a speaker are recorded from a
microphone through an amplifier to a DAT (digital audio tape recorder). After measurement, DAT
is regenerated, analyzed using an FFT analyzer, and data are organized on a personal computer.
The measurement room is in our factory, and as a noise countermeasure, at least 100 averagings
are performed to improve the SN ratio to obtain measurement results. Even if the sound reflected
from the floor, wall or ceiling is removed to process only the direct sound from the speakers, it is
possible to obtain the direct sound with a sufficient length of time. It is done by this method.
[0024]
EXAMPLES Next, the present invention will be described based on examples, but the present
invention is not limited to the examples. In the small speaker 1 according to the present
invention shown in FIG. 1, the speaker unit 11 is disposed in a box-shaped cabinet 12.
[0025]
The speaker unit 11 generally has a conical frame 14 which covers the whole of a cone paper
(not shown), and the magnet portion 16 is fixed to the flat top of the frame. A cylindrical voice
coil (not shown) is attached in the vicinity of the magnet unit 16 and by glueing the center top
portion of the cone paper to one side of the coil, the corn paper acoustically vibrates with the
coil. The corn paper has its annular peripheral portion glued to the annular inner peripheral
surface of the frame 14 so that the corn paper is stretched to stably generate sound.
[0026]
The conical frame 14 is inserted into the central hole 18 of the baffle plate 2 of the porous
sintered body, and the flange portion 20 at the front peripheral end is fixed to the baffle plate 2
by bolting or bonding. is there. In the baffle plate 2, an annular groove 21 is formed on the front
inner periphery of the central hole 18 so as to be fitted to the flange portion 20. The planar
shape of the baffle plate 2 is substantially the same rectangle as the inner size of the cabinet 12,
and is vertically clasped or adhered to the inner circumferential wall of the cabinet. The flanges
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20 of the frame 14 are preferably bolted to the baffle plate 2 at three points at equal intervals in
the circumferential direction.
[0027]
The box-shaped cabinet 12 constitutes a speaker box together with the baffle plate 2, and a
through hole 22 for heat radiation is provided on the side wall thereof, and the receptacle 23 of
the connector is attached to the rear wall of the cabinet. The cabinet 12 is preferably installed
with the stand 24 so as to be disposed upward.
[0028]
In order to manufacture the porous sintered body 3 shown in FIG. 4, although not shown, a pair
of rectangular electrode plates having the same surface area are disposed opposite to each other
on a horizontal heat-resistant ceramic plate, A molding apparatus is used in which a pair of
rectangular heat-resistant side walls are installed orthogonal to this to form a mold. The
dimensions of this form are a base area of 675 × 675 mm and a height of 15 cm.
Thermocouples are inserted in the horizontal ceramic plate, and it is possible to measure the
temperature in the mold. Lay the release sheet flat on the bottom of this form and cut the cast
iron (FC-25, content: about 3.5% carbon, about 2.5% silicon, about 0.5% manganese) on it Put 17
kg of waste (dalai powder), flatten it to a thickness of about 30 mm, and lay the release sheet flat.
[0029]
In the above-described forming apparatus, the ceramic press die is lowered and simultaneously
the power is turned on, and the press die is lowered and pressurized until the current reaches
5000 amperes. When pressurization is continued at a pressure of 210 kg / cm 2, the current
passing through the mold rises rapidly from 0 to 5000 amps, and then gradually continues to
reach 6400 amps in 10 to 12 minutes after pressurization. Since the current is equilibrated at
6400 amperes, the press die is now raised to take out the sintered plate and cool it.
[0030]
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The sintered plate is appropriately cut and processed, and is further finished and polished to
obtain a baffle plate 2. The obtained porous sintered body 3 (FIG. 4) has a porosity of about 50%,
and the pores on the outer surface are somewhat sparse in the thickness direction and the pores
in the interior are dense. The porous sintered body 3 is a vibration-damping material having a
vibration damping rate of (η) = 0.14 to 0.53.
[0031]
In the small-sized speaker 1, since the speaker unit 11 is installed in the cabinet 12 through the
baffle plate 2 made of porous sintered body, even if mechanical vibration which is a reaction of
acoustic vibration of cone paper is transmitted to the frame 14, The mechanical vibration can be
absorbed by the porous sintered body of the baffle plate 2. The baffle plate 2 does not transmit
the mechanical vibration transmitted from the cone paper to the cabinet 12 when the cone paper
vibrates as the sound signal from the amplifier.
[0032]
In FIG. 5 and FIG. 6, as an experimental example, a baffle plate of a porous sintered body of cast
iron is attached to a 3 cm-diameter speaker, and a time region in the speaker characteristic is
displayed. As a comparative example, in FIG. 6, a wooden baffle plate is attached to the 3 cm
diameter speaker. In FIG. 5, the positive peak value following the first negative peak is about 20
dB greater than that of FIG. The cast iron porous sintered body used in FIG. 5 has high vibration
absorption and is a rigid material, so that the speaker unit can be firmly fixed. The porous
sintered body of cast iron operates more on the film surface of the cone paper by absorbing
more mechanical vibration of the reaction unit when the film surface of the cone paper moves as
compared with the wood of FIG. Becomes smoother, and the amplitude spreads more faithfully to
the input signal. The wood shown in FIG. 6 is easy to move in accordance with its natural
frequency, which adversely affects the movement of the film surface of corn paper.
[0033]
In the small speaker 1 shown in FIG. 1, a convex plastically deformed metal foam 26 is attached
so as to cover the cabinet 12, that is, the front surface of the baffle plate 2. The metal foam 26
has an apparent density of 1.0 or less, and a large number of elongated nickel pieces extend in
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the width direction and randomly bond to form a three-dimensional network shape as a whole,
and its thickness is about 2 mm. There is.
[0034]
The metal foam 26 is manufactured using a plating reactor 28 as schematically shown in FIG. In
the reactor 28, the open-celled polystyrene plates 32, 32 are attached to the metal plate 30 of
the cathode, and the metal plate is a material having high removability from nickel, and is
surface-treated so as to increase releasability. On the other hand, the anode is a nickel plate 34,
and the nickel plating bath 36 contains nickel sulfate, nickel chloride, boric acid, a complexing
agent and the like.
[0035]
When a constant potential is applied using an external power supply 38, at the cathode, nickel
ions diffuse from the inside of the solution through the bubbles of the polystyrene plate 32 to
approach the electrode interface and receive electrons from the cathode to form metallic nickel.
It is reduced. At this time, since metallic nickel is present only in the bubble portion of the
styrene plate 32, it is randomly grown and bonded along the bubble portion. When the
deposition of metallic nickel reaches several millimeters, the cathode is taken out, the
polystyrene plates 32, 32 are peeled off from the metal plate 30, and the styrene content is
further removed. With appropriate surface finishing, a flat metal foam 26 is obtained. The metal
foam 26 can be plastically deformed convexly by a press die or hand.
[0036]
The metal foam 26 can appropriately diffuse the directivity of the generated sound by controlling
the intensity distribution and the phase of the sound source as an acoustic lens. The sound wave
emitted from the speaker unit 14 generates a new sound wave surface on the net surface by the
irregular holes of the metal foam 26. From this sound wave surface, a sound wave passing
straight through the pores of the metal foam 26, a sound wave which bounces once upon hitting
the net, and a sound wave which is diffracted in various directions are generated to hit the
boundary surface of the pores. Further, since the metal foam 26 is a light but hard material, the
sound wave is not absorbed by the metal foam 26 and can pass without changing the sound
quality. That is, the sound waves emitted from the speakers reach the net surface, where they
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travel straight and are diffracted and diffused to be diffused from the net surface to the space
outside. Even if the sound wave emitted from the speaker has some directivity or frequency level
difference, when it passes through the metal foam 26, the sound quality does not change, and it
becomes a stable sound wave that diffuses over a wide area.
[0037]
FIG. 9 shows frequency characteristics in which the direction of the sound receiving point of the
speaker attached with the metal foam 26 is 30 degrees and 60 degrees at the front (0 degree) of
the speaker. FIG. 10 shows the frequency characteristics of 0 degree, 30 degrees, and 60 degrees
when the metal foam is removed for the same speaker as FIG. 9. The frequency characteristics
also depend on the size and number of pores in the metal foam, but here the difference appears
well in the bass range. In FIG. 9, the output sound pressure level drops stepwise from 0 degrees
to 60 degrees, whereas in FIG. 10, the output sound pressure level in the bass region at 30
degrees is lifted and lacks stability. It can be seen that sound waves are being generated.
[0038]
FIG. 2 shows a modification of the present invention, in which the conical frame 14 of the
speaker unit 11 is inserted into the center hole 41 of the baffle plate 40 and the mounting
member 5 of the porous sintered body is the flange portion of the speaker unit 11 It is
interposed between the rear face of 20 and the front face of the baffle plate 40, and is fixed by
bolting or bonding at three or four points in the circumferential direction. The baffle plate 40 is
made of ordinary wood or metal. The mount member 5 is an annular body having a rectangular
cross section and an inner diameter substantially equal to that of the central hole 41 of the baffle
plate 40, and is made of a single porous sintered body or a combination of a plurality of small
plate pieces. The mounting member 5 also has a function of arranging the speaker unit 11
forward.
[0039]
The mounting member 7 shown in FIG. 3 is interposed between the baffle plate 44 and the
cabinet 12, and the baffle plate is made of ordinary wood or metal. The conical frame 14 is
inserted into the central hole 45 of the baffle plate 44, and the flange portion 20 at the front end
and the front circumferential surface are fixed to the central hole 45 of the baffle plate 44. The
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mounting member 7 is a combination of elongated plate members having a rectangular cross
section which has substantially the same thickness as the baffle plate 44, and bonds the upper
and lower surfaces between the outer peripheral surface of the baffle plate 44 and the inner wall
of the cabinet 12 or separately. Fix the bracket or bolt. The veneer 43 is placed in front of the
baffles primarily for decoration.
[0040]
The mount members 5 and 7 absorb mechanical vibration transmitted from the cone paper to
the frame 14 of the speaker unit 11. When the cone members vibrate as the sound signal from
the amplifier, the mount members 5 and 7 do not transmit the mechanical vibration transmitted
from the cone paper to the cabinet 12 so that the mechanical vibration is not combined with the
sound wave. Therefore, in this speaker, the sound pressure level in the low frequency range rises,
and the sound pressure level in the audio frequency band approaches flat, and the speaker
characteristics are improved. In the mounting member 7, since the mechanical vibration of the
baffle plate itself can not be avoided, the vibration noise generated from the baffle plate may
have some adverse effects.
[0041]
As an example, in FIG. 11, in the case of a commercially available 38-cm apertured speaker
(Model I made by UREI, model 811B), a porous sintered body mount member is interposed
between the conical frame of the speaker unit and the enclosure. And the frequency
characteristics of the case without the intervention (in the original state). When the frequency
characteristic is measured, the sound pressure level in the low frequency range of 40 to 50 Hz or
less rises when the mount member is interposed. With this sound pressure level rise, the porous
sintered body with high vibration absorption property and hard absorption absorbs mechanical
vibration of the speaker unit itself and does not transmit box noise etc. to the enclosure, that is,
the speaker box, and against the signal sound of the low frequency band. This is the result of the
film surface of corn paper moving accurately. As a result, in this speaker, the sound pressure
level in the audio frequency band approaches flat, and the speaker characteristics are generally
improved. On the other hand, in the original state, the reaction of the acoustic vibration of the
cone paper is transmitted to the frame of the speaker unit, and further transmitted to the cabinet
to cause the whole box to swing by mechanical vibration. With such a box swing, the low
frequency of the sound generated from the cone paper is canceled, the sound pressure level in
the low range becomes low, and the low range is not accurately reproduced.
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[0042]
Although not shown, in the case of a 30 cm-aperture speaker (manufactured by JBL), an increase
in sound pressure level can be found at a frequency of about 70 Hz or less. As described above,
the rigid porous sintered body may be attached to a commercially available speaker as a retrofit
mounting member, or may be previously incorporated as one component for fixing the speaker
unit to the enclosure. Further, in a speaker with a diameter of 10 cm, the sound pressure level
rises in a bass range of about 200 Hz or less when comparing the mount member made of
porous sintered body and the mount member made of wood.
[0043]
FIG. 12 shows a speaker 50 incorporating two speaker units 46 and 48 at the front and back.
The speaker units 46, 48 usually have the same shape and function, and have conical frames 51,
52 which cover the whole of the cone paper (not shown), and the magnet portion on the flat top
of the frames Fix the 53, 54. A cylindrical voice coil (not shown) is attached in the vicinity of the
magnet parts 53 and 54, and the corn paper acoustically vibrates with the coil by pasting the
center top portion of the cone paper on one side of the coil.
[0044]
The frame 51 of the front unit 46 is inserted into the center hole 57 of the baffle plate 56, and
the flange portion 58 at the front peripheral end is fixed to the baffle plate 56 by bonding or
bolting. In the baffle plate 56, an annular groove 59 is formed on the front inner periphery of the
center hole 57 so as to be fitted with the flange portion 58. The planar shape of the baffle plate
56 is substantially the same as the inner size of the cabinet 60 and is rectangular. On the other
hand, in the frame 52 of the rear unit 48, the flange portion 65 is fitted in the annular groove 64
formed in the rear inner periphery of the central hole 63 in the baffle plate 62 in which the
porous sintered body is resin-coated. Stick. The baffle plates 56 and 62 coat a porous sintered
body having a predetermined shape with a thin resin.
[0045]
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Between the baffle plates 56 and 58, two wood plates 66 and 66 having substantially the same
shape and the same thickness as the baffle plate are disposed. All four plates are intimately
bonded and glued or clasped or glued vertically to the inner circumferential wall of the cabinet
60. The slightly elongated box-like cabinet 60 constitutes a speaker box together with the baffle
plates 56 and 62, and a through hole 67 for heat dissipation is provided on the side wall thereof,
and the receptacle 68 of the connector is attached to the cabinet rear wall.
[0046]
In the speaker 50, even if the reaction of the acoustic vibration of the cone paper is transmitted
to the frames 51 and 52 of the speaker units 46 and 48, the mechanical vibration is absorbed by
the porous sintered body of the baffle plates 56 and 62, and By inputting the same sound signal
to the speaker units 46 and 48, both speaker units will acoustically vibrate in the same phase at
the same time. By this operating environment, the film surface of the front cone paper is more
easily acoustically vibrated corresponding to the vibration of the film surface of the rear cone
paper. While a speaker with a small aperture has difficulty in accurately reproducing the bass
region, the double-unit speaker 50 can confirm an increase in sound pressure level in the bass
region.
[0047]
In FIGS. 13 to 17, the speaker units used in the experiments all have the same aperture of 10 cm,
and each speaker has an aspect in which the metal foam 69 is removed. In FIG. 13, the speaker
characteristics of the single speaker and the double speaker are compared, and the single
speaker uses one speaker unit, the double speaker uses a series of two speaker units as described
above, and all other structures are the same. is there. In FIG. 13, the sound pressure level in the
low range is increased in the single speaker, and the sound pressure level in the low range is
further improved in the double speaker than the single speaker.
[0048]
In FIG. 14, in the case of another double speaker of the same structure, the respective
frequencies of the porous sintered body (trade name: Rusk) for the baffle plate on the one hand
and the wooden baffle plate on the other hand are used. The characteristics are compared. In FIG.
14, it can be seen that the double speaker using the porous sintered body baffle plate has a
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sound pressure level greater than that of the wooden baffle plate in the reproduction of the low
frequency range.
[0049]
FIGS. 15 and 16 show frequency characteristics of different speaker units having an aperture of
10 cm. In both the speaker units, a large dip (drop) occurs in a high range. On the other hand,
FIG. 17 shows frequency characteristics of a double speaker in which two speaker units are
mounted in series. In both speakers, although the dip occurred in the high range, the sound
pressure level in the low range is further increased when the double speakers in FIG. 17 are used,
and the sound pressure in the high range shows more stable characteristics. . According to FIGS.
13 to 17, the double speaker using the baffle plate of the porous sintered body raises the sound
pressure level of the bass region compared to a normal speaker, and uses two different speaker
units. It turns out that it has the characteristic which compensates the fault of each unit.
[0050]
The speaker 70 shown in FIG. 18 incorporates the front speaker unit 72 vertically and the rear
speaker unit 74 horizontally. The speaker units 72 and 74 usually have the same shape and
function. The frame 75 of the front unit 72 is fixed to the resin-coated porous sintered body
baffle plate 76. The rear of the front unit 72 is surrounded by a cabinet 78, and a cone (not
shown) in the frame of the rear unit 74 opens in the closed space 79. The frame 80 of the rear
unit 74 is fixed to the resin-coated porous sintered body baffle plate 82, and the baffle plate 82 is
horizontally disposed below the speaker unit 72, and fixed to the inner peripheral wall of the
cabinet 78 Glue.
[0051]
Similarly to the speaker 50 shown in FIG. 12, even if the reaction of the acoustic vibration of the
cone paper is transmitted to the frames 75 and 80, the speaker 70 is made of the porous
sintered body of the baffle plates 76 and 82 for the mechanical vibration. Since the vibrations of
the two speaker units 72 and 74 are synchronized back and forth while absorbing the vibration,
the mechanical vibrations can be attenuated more effectively. Since the speaker 70 is vertically
long and has a shape similar to that of a conventional speaker, the application thereof is rarely
limited.
03-05-2019
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[0052]
FIGS. 19 and 20 are sound line diagrams drawn according to the installation position of the onvehicle speaker, and it is preferable to appropriately deform and miniaturize the speaker 1 as
exemplified in FIG. 1 and use it as the on-vehicle speaker . Loudspeakers that can be installed are
effective even for normal speakers instead of the speaker 1, and may be a speaker in which two
speaker units are incorporated in series as shown in FIG.
[0053]
In FIG. 19, the speakers 84, 84 are installed horizontally and forwardly below the driver's seat 87
and the passenger's seat 88 of the automobile 86 at the center or slightly forward of the lower
side of the seat. When the speakers 84, 84 are installed upward below the driver's seat 87 and
the passenger seat 88, the direct sound from both speakers is mostly reflected in the front of the
vehicle, and the audible sound of the person in the vehicle is mainly indirect. When the indirect
sound converges, virtual sound images 90, 90 are positioned in front of the car. On the other
hand, FIG. 20 shows sound rays emitted from each speaker in a conventional automobile (for
example, trade name: Corolla) in which two speakers 92, 92 are installed on the left and right of
the dashboard. In FIG. 20, the driver's seat 87 and the passenger's seat 88, which are front seats,
receive a loud direct sound from the near side speaker 92, and then receive a direct sound from
the far side speaker, and then the door or window, You will hear the sound reflected repeatedly
and repeatedly by the ceiling and the rear window.
[0054]
As shown in FIG. 19, when the speakers 84 and 84 are installed under the seat, the direct sound
emitted from the near speaker goes around the seat to reach the listener on the front seat first,
and then the distant speaker I hear the direct sound that came around. That is, instead of
receiving a large direct sound from near, you will first hear the diffracted sound that has turned
around the seat, and then you will hear the sound reflected by the door or ceiling. On the other
hand, direct sound that travels forward in the space at the foot of the front seat without
diffraction becomes a reflected sound accompanied by a time delay to reach the listener, and this
reflected sound is reflected in multiples in the car. Become.
03-05-2019
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[0055]
FIG. 21 is a graph showing the speaker characteristics of the car (trade name: Corolla) measured
by the speakers 84, 84 installed under the seat of FIG. 19 at the front passenger seat. FIG. 22 is a
graph showing speaker characteristics measured by the speakers 84, 84 installed under the seat
of FIG. 19 at another passenger's seat of another car (trade name: Celsior). Moreover, FIG. 23 is a
graph which measured the speaker characteristic by the large number of speakers installed in
the conventional position in the front passenger seat about another motor vehicle (brand name:
Celsior). Each sound source is a rectangular wave pulse as shown in FIG.
[0056]
In the speakers 84 and 84 installed under the seat, in the time domain of FIG. 21 (a), a not so
loud sound arrives first, followed by a certain amount of loudness, and FIG. 23 (a) It has become
a diffuse sound field as well. In the frequency range of FIG. 21 (b), from the low tone range to
around 3 kHz, it has substantially flat characteristics, and after 3 kHz, the sound pressure level
falls faster than in FIG. 23 (b). The speaker characteristic shown in FIG. 22 is even better than
that of FIG.
[0057]
With regard to the speaker characteristics shown in FIG. 23, it can be seen that in the time
domain of FIG. 23A, there are many direct sounds and reflected sounds having large sound
pressure, and they reach the sound receiving point. Large direct and reflected sounds diminish
over time, resulting in a diffuse sound field. In the frequency region of FIG. 23 (b), the sound
pressure is slightly increased around 1 kHz, and the sound pressure level is gradually lowered
from there to the low tone range and further to the middle and high tone range. Therefore, for an
automobile (trade name: Corolla), the speaker characteristics by the speakers 92 and 92 installed
at the conventional position as shown in FIG. 20 are further inferior to those in FIG.
[0058]
Judging from the sound diagrams shown in FIGS. 19 and 20, the measured values shown in FIGS.
03-05-2019
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21 to 23, and further listening, the direct sound from the speakers 84 and 84 is directly a
listener under the seat of FIG. Diffraction sound has reached the ear first. After a short time, the
direct sound that has moved forward to the foot of the seat reaches the receiving point as a
reflected sound. As this reflection sound is repeatedly reflected in the space at the foot, each
reflection sound reaches the sound receiving point one after another, so that a firm sound image
is localized in front of the seat foot. Also in the frequency characteristic, it is a flat characteristic
from the low frequency range to about 3 kHz, and in the high frequency range of 3 kHz or more,
the level drops quickly, thus forming a sound field in which the bass range is reproduced
sufficiently for the ear. ing. Since the virtual sound images 90 and 90 are localized in front of the
front seats, it is possible to feel the sound of the arranged music hall and the listening room
instead of the sounds being disorderly. Since the direct sound from the speaker does not reach
the listener directly, a sound field that is soft and not tired is released from the pressure feeling
of the sound.
[0059]
In general, temporal acoustic characteristics such as an auditorium or a concert hall are such that
the sound played on the stage first reaches the audience directly and then the primary reflection
sound, the secondary reflection sound and the tertiary reflection sound Subsequently, the sound
is transmitted to the audience in a form that directly supports the volume of the sound, which
makes the user feel like being surrounded by a rich volume, a clear sense, and further sound.
Odetrim creates such an acoustic space. In a car, because the acoustic space is small and the
reflection distance is short, direct sound and primary reflection sound, secondary reflection
sound, etc. reach at the same time to the person in the car, and the person in the car Will receive
high sound pressure at one time.
[0060]
On the other hand, as shown in FIG. 19, when the speakers 84, 84 are installed under the seat,
the person inside the car can see the virtual sound image 90 of the reflected sound instead of the
direct sound from both speakers becoming somewhat low. By making it, the primary reflection
sounds like a direct sound, creating a pseudo-space in which a small space is greatly expanded.
Therefore, even in the car, it is possible to create an acoustic space having temporal acoustic
characteristics, such as an auditorium or a concert hall.
[0061]
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19
On the other hand, in the conventional position shown in FIG. 20, the direct sound from the
speakers 92 and 92 and the reflected sound thereof generate a large sound pressure in the
vehicle without any time interval. For this reason, it can not but be judged that the localization of
the sound image is difficult because it is engulfed by the sound from the chaotic direction. Also in
the frequency characteristic, a level rise near 1 to 2 kHz is observed, and an unpleasant sound
field is formed. From this result, installing a speaker using a baffle plate of porous sintered body
under a seat as shown in FIG. 19 can be interpreted as having an excellent effect of improving
the in-vehicle sound field.
[0062]
Industrial Applicability The general-purpose speaker according to the present invention is a
speaker at the time of signal input by fixing the speaker unit to a baffle plate or an enclosure
using a porous sintered body having high vibration absorption and rigidity. By absorbing the
frame vibration of the unit, the film surface of the cone paper can be accurately acoustically
vibrated without being restrained. In addition, when a porous sintered body is intervened,
unnecessary frame vibration is not transmitted to the baffle plate or the enclosure, so that the
sound faithful to the input signal can be reproduced, and a clearer and sharper sound can be
reproduced. It will be. In the speaker of the present invention, in particular, the tendency is
remarkable around the audio frequency, and the sound pressure level of the bass region is
further increased.
[0063]
The metal foam used in the present invention is hard and thick with an apparent density of 1.0 or
less, and the sound wave generated from the speaker can supply a stable sound over a wide
range by going straight or diffracting on the metal foam surface. . In the general-purpose speaker
according to the present invention, when two speaker units are fixed in series, signals are
simultaneously input to the front and rear speaker units in the same phase, so the cone sheet
surface of the front speaker unit It vibrates more smoothly according to the acoustic vibration of
the film surface of cone paper. As a result, in the speaker provided with the two speaker units in
series, the sound pressure level rise and the frequency characteristic in the low frequency range
become more stable as compared with the single unit speaker.
03-05-2019
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[0064]
According to the speaker attachment method of the present invention, by installing the speaker
under the driver's seat and the passenger's seat in the car, the conventional in-vehicle sound field
is a chaotic sound space, but the front of the front seat is Localize the sound image, and achieve
improvement of the sound field like a music hall or listening room planned for rhythmic
arrangement. Further, according to the method of the present invention, since the direct sound
does not reach the listener directly but the sound diffused from the front reaches, a relaxing
sound field space without a feeling of pressure is created.
[0065]
Brief description of the drawings
[0066]
1 is a schematic cross-sectional view showing a general-purpose speaker of the present
invention.
[0067]
FIG. 2 is a cross-sectional view of an essential part of a general-purpose speaker having a
mounting member.
[0068]
FIG. 3 is a cross-sectional view of an essential part of a general-purpose speaker having another
mounting member.
[0069]
FIG. 4 is an enlarged cross-sectional view of a porous sintered body used in the present
invention.
[0070]
FIG. 5 is a graph showing the time domain in the speaker characteristic of the speaker of the
present invention.
03-05-2019
21
[0071]
[FIG. 6] It is a graph which displays the time area ¦ region in a speaker characteristic about the
speaker which attached the wooden baffle board.
[0072]
7 is an explanatory view showing a method of measuring the speaker characteristics.
[0073]
FIG. 8 is a schematic explanatory view of a plating reaction apparatus used for producing a metal
foam.
[0074]
FIG. 9 is a graph showing frequency characteristics in which the direction of the sound receiving
point is the speaker front (0 degree), the inclination is 30 degrees, and 60 degrees with respect
to the speaker to which the metal foam is attached.
[0075]
FIG. 10 is a graph showing frequency characteristics in which the direction of the sound
receiving point is the speaker front (0 degree), the inclination is 30 degrees, and 60 degrees with
respect to the speaker without metal foam.
[0076]
FIG. 11 is a graph showing frequency characteristics with and without a porous sintered body
mounting member interposed between the conical frame and the enclosure of the speaker unit in
the commercially available speaker.
[0077]
12 is a schematic perspective view showing a modification of the general-purpose speaker.
[0078]
(A) is a graph showing the time domain in the speaker characteristics, and (b) is a graph showing
the frequency domain for single and double speakers.
03-05-2019
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[0079]
FIG. 14 is a graph showing frequency characteristics in the case where the baffle plate is a
porous sintered body or wood for another double speaker of the same structure.
[0080]
FIG. 15 is a graph showing frequency characteristics of a 10 cm aperture speaker unit.
[0081]
FIG. 16 is a graph showing frequency characteristics of another speaker unit having an aperture
of 10 cm.
[0082]
18 is a graph showing frequency characteristics of a double speaker using the speaker unit of
FIG. 15 and FIG.
[0083]
FIG. 18 is a schematic perspective view showing another modified example of the generalpurpose speaker.
[0084]
FIG. 19 is an acoustic diagram drawn at the installation position of the on-vehicle speaker
according to the present invention, in which (a) is a side sectional view of a passenger car, and (b)
is a horizontal sectional view.
[0085]
FIG. 20 is an acoustic diagram drawn at the installation position of a conventional car-mounted
speaker, in which (a) is a side sectional view of a passenger car, and (b) is a horizontal sectional
view.
[0086]
At the installation position of the on-vehicle speaker of FIG. 19, (a) is a graph showing the time
domain in the speaker characteristic and (b) is a frequency domain.
03-05-2019
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[0087]
FIG. 22 is a graph showing the same speaker characteristics as FIG. 21 for another car.
[0088]
23 is a graph showing the same speaker characteristic as that of FIG. 21 in the original
installation position of the on-vehicle speaker in another automobile.
[0089]
Explanation of sign
[0090]
DESCRIPTION OF SYMBOLS 1 general-purpose speaker 2 baffle plate 3 porous sintered compact
5, 7 mount member 11 speaker unit 12 cabinet 14 conical frame 16 magnet part
03-05-2019
24

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