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DESCRIPTION JPH11262091

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DESCRIPTION JPH11262091
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
small and light speaker device, and more particularly to a speaker device capable of canceling the
reaction of the sound radiation of the speaker device using a single speaker.
[0002]
2. Description of the Related Art Conventionally, as an effective means for extending the low
range reproduction limit of a speaker device, for example, an opening and a duct are provided in
a baffle plate provided with a speaker, and the phase of sound emitted from the back of the
diaphragm of the speaker is detected. It is well known that a bass reflex type (phase reversal
type) speaker device that inverts and radiates from the opening through the duct to intensify the
sound wave emitted to the front from the diaphragm of the speaker so as not to distort the bass
region. It is done.
[0003]
As shown in FIG. 6A, such a phase-reversal type speaker device fixes the speaker 3 so as to face
the speaker sound emission hole 2a formed in the baffle plate 2 provided on the front surface of
the speaker box 1.
[0004]
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1
For example, as shown in FIG. 6A, the speaker 3 is provided with a ring magnet 4 and a plate 5
and a yoke 6 with a central hole attached so as to sandwich the ring magnet 4. A magnetic air
gap 7 is formed between the inner circumferential side of the magnetic head and the center pole
6 a of the yoke 6.
Further, the frame 8 of the speaker 3 is attached to the plate 5, and an edge 9 is provided on the
outer peripheral portion of the frame 8, and the outer peripheral portion of the conical
diaphragm 10 is held by the edge by this gasket 9 or the like.
[0005]
On the other hand, a voice coil bobbin 11 is attached to the inner peripheral portion of the
diaphragm 10. A voice coil 12 is wound around the voice coil bobbin 11. The voice coil 12 is
formed by the plate 5 and the center pole 6a of the yoke 6. The magnetic gap 7 is inserted.
A damper 17 holds the voice coil 12 in the magnetic gap 7.
[0006]
Further, an acoustic signal from the input terminal 13a provided at a predetermined position
outside the speaker box 1 is supplied to the terminal 15 of the speaker 3 via the connection line
14a, and an acoustic signal from the terminal 15 is via the tinsel wire 16. The voice coil 12 is
supplied.
[0007]
In addition, a duct 18 having an opening 18a in the same plane as the speaker sound emission
hole 2a of the baffle plate 2 is provided, and the phase of the sound emitted from the back
surface of the diaphragm 10 of the speaker 3 is reversed. And radiate the sound out of the front
of the diaphragm 10 to a wide range.
[0008]
The electrical equivalent circuit in the phase inversion type speaker device as described above
can be expressed as shown in FIG. 6 (B).
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[0009]
6A and 6B, S0 is the stiffness of the support system of the speaker 3, M0 is the equivalent mass
of the support system of the speaker 3, Rms0 is the mechanical resistance of the speaker support
system, and Rm0 is the air load of the speaker The mechanical resistance R0 is the equivalent
mechanical resistance of the speaker and can be expressed as Rm0 + Rms0 = R0.
SC is the stiffness in the speaker box 1, RD is the mechanical resistance of the air load of the duct
18 portion, and MD is the air mass of the duct 18 portion.
[0010]
As described above, by employing the phase-reversal type speaker device, the bass reproduction
limit can be lowered compared to the closed type, and the low range reproduction range is
expanded to about 80% of the lowest resonance frequency f0 of the speaker 3 It is supposed to
be possible.
[0011]
In such a speaker device, the sound radiation force F1 due to the vibration of the diaphragm 10
of the speaker 3 in FIG. 6A can be expressed by the acceleration α0 acting on the diaphragm 10
of the speaker 3 on the equivalent mass M0 of the speaker 3, that is, F1 = M0 α0 .
With respect to such a sound radiation force F1, the reaction force -F1 directed from the back
side of the diaphragm 10 toward the inside of the speaker box 1 is also remarkable when the
speaker apparatus is small and light and the volume of the speaker box 1 is small. The air in the
speaker box 1 repeats compression and expansion due to the vibration of 10, and this air acts as
a force to return the diaphragm 10 to the original position, thereby swinging the speaker box 1,
and the bass reproduction is inhibited. Had a problem.
[0012]
In order to solve such a problem, the present applicant has previously proposed a speaker
apparatus as shown in FIG. 7, and in FIG. 7, the same parts as in FIG.
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[0013]
In FIG. 7, the speaker box 1 is formed integrally with the baffle plate 2 in a box shape of
synthetic resin.
The speaker 3 having the same configuration as that described in detail in FIG. 6A is fixed so as
to face the speaker sound emission hole 2 a formed on the upper side of the baffle plate 2.
The first duct 18 and the opening 18 a disposed on the lower side of the baffle plate 2 are
integrally molded when the baffle plate 2 is molded.
[0014]
In the upper part of the back plate 1B, a speaker sound emitting hole 2b is formed at a position
facing the speaker sound emitting hole 2a formed in the baffle plate 2, and the second speaker
3b, preferably the speaker 3 and the back face face each other. Similarly, the second duct 18b
fixed to the rear plate 1B to face the speaker sound emission hole 2b and having a larger duct
diameter than the first duct 18 is overlapped within a predetermined length of the first duct 18
And an integral mass of air which radiates to the opening 18a of the first duct 18 through the
opening 18c of the second duct 18b, and is integrally embedded with the rear face plate 1B so
that a concentric cross section is formed. It is configured to increase RD.
[0015]
Further, acoustic signals of the same input are supplied to the first and second speakers 3 and 3b
via the input terminals 13a and 13b disposed on the rear plate 1B and the connection lines 14a
and 14b.
[0016]
According to the speaker apparatus of FIG. 7 described above, the reaction force of the duct
radiation force FD1 and FD2 / 2 + FD2 / 2 between the first and second ducts 18 and 18b-FD1
and -FD2 / 2 + (-FD2 / 2) respectively Because of the cancellation, the reaction forces -F1 and -F2
of the radiation forces F1 and F2 of the first and second speakers 3a and 3b can cancel each
other if F1 .apprxeq.F2.
[0017]
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However, in the above configuration, a pair of the speaker box 1 is provided to support and
prevent the reaction force -F1 due to the action force F1 of the speaker 3 of the small and light
speaker box 1 from being supported. The speakers 3 and 3b having substantially the same
structure are required, and there is a problem that they become not only a bottleneck for
miniaturization but also become expensive.
[0018]
Furthermore, in the conventional small speaker, the magnet of the magnetic circuit for driving
the diaphragm is very small, and the voice coil is wound around the voice coil bobbin with a
small diameter to increase the sound pressure of the speaker. The resonance sharpness
(hereinafter referred to as Q0) of f0) is necessarily increased.
[0019]
Also, when such a small speaker with a large Q0 is disposed in a speaker box with a small
volume, the reproduction expansion of the low band can not be performed, and the Q0 at f0
becomes larger, so that the sound quality in the low band is significantly degraded. was there.
[0020]
Generally, a very small speaker often uses a fixed edge that simultaneously produces an edge
when making a diaphragm, but the fixed edge of such a small speaker is hard and the voice coil is
also lightweight, so the speaker's f0 There was a problem that it was difficult to lower.
[0021]
Furthermore, in the two loudspeakers in which the vibration system of the loudspeakers is
equally made, Q0 increases in proportion to f0 as the higher one of f0 becomes worse for
reproduction in the low band.
[0022]
The present invention is intended to provide a speaker device that solves the problems of
overhead, and the problem to be solved by the invention is to arrange in a small and light
speaker box by subjecting one speaker unit to simple processing. The counteracting force of the
radiated power of the speaker is canceled or attenuated to prevent the swing of the speaker
device, to radiate strong low frequency and reduce Q0, and to shift the speaker's f0 to low
frequency side. It is designed to expand the area and to emit good low-frequency radiation.
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[0023]
According to the speaker apparatus of the present invention, an airtight plate for reflecting the
sound of the diaphragm into the speaker box is provided on the front surface of the diaphragm,
and the diaphragm or cap facing the airtight plate is provided. It was made to make a through
hole in the
[0024]
According to the speaker apparatus of the present invention, only by applying a simple process
to one speaker, the reaction by the speaker radiation force built in the small and light speaker
box can be offset to prevent the rocking and increase the low frequency range and the vibration.
The equivalent mass of air passing through a plurality of through holes formed in the plate can
lower the Q0 of the speaker and can expand f0 to the low frequency side.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION The small-sized speaker according to the
present invention will be described in detail below with reference to FIGS.
In the present invention, parts corresponding to the speakers shown in FIGS. 6 and 7 are given
the same reference numerals.
[0026]
FIG. 1 (A) is a side sectional view of the speaker used in the speaker device of this embodiment,
FIG. 1 (B) is a sectional view taken along line AA 'of FIG. 1 (A). In the example, a small speaker is
shown, and the yoke 6 is a disk-like portion made of a plate material such as pure iron, a
cylindrical center pole 6a erected at the center position of the disk-like portion, and concentric
with the center pole 6a. A magnet guide portion 6b composed of a step formed in a disk-like
portion is integrally formed.
[0027]
A ring-shaped magnet 4 magnetized in the thickness direction of ferrite or the like is adhered
onto the disk-like portion of the yoke 6 described above via an adhesive.
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The inner diameter of the ring-shaped magnet 4 is fitted to the step of the magnet guide portion
6 b formed in the disk-shaped portion of the yoke 6 and positioned.
[0028]
The plate 5 is joined to the magnet 4.
In this case, the gap guide is placed in the center pole 6a as it is inserted, an adhesive is applied
to the upper surface of the magnet 4, and the inner diameter of the plate 5 is inserted into the
outer diameter of the gap guide and fixed.
The plate 5 is made of pure iron or the like in the shape of a disk, and is a punched plate material
having a through hole at its center and is a voice coil 12 in the magnetic gap 7 formed between
the inner peripheral edge of the through hole and the outer diameter of the center pole 6a. Is
provided.
[0029]
The metal part of the magnetic circuit is constituted by fixing the frame 8 formed in a funnel
shape with steel or the like to the plate 5, and the lower part of the magnetic gap 7 is surrounded
by the outer periphery of the center pole 6 a and the inner diameter of the magnet 4. The second
space 20b is formed.
[0030]
The voice coil 12 wound around a cylindrical voice coil bobbin 11 is inserted into the magnetic
gap 7 of the above-described magnetic circuit, and the voice coil bobbin is airtightly vibrated in
the vertical direction via the airtight damper 17 having a corrugated corrugation. Hold 11.
In order to obtain the damper 17 having airtightness, two or three thin cloths are stacked and
joined to make a damper, or a surface of the damper 17 coated with a synthetic resin solution or
the like is used.
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[0031]
The inner diameter of the damper 17 as described above is bonded to the middle portion of the
voice coil bobbin 11 via an adhesive, and the outer diameter portion is bonded to the outer
periphery of the bottom portion of the frame 8.
Further, the inner diameter of a funnel-shaped diaphragm 10 with a free or fixed edge 9 made of
paper or the like is joined to the upper outer diameter of the voice coil bobbin 11 and the largest
diameter portion of the diaphragm 10 is the upper opening rim of the frame 8 It fixes to the part
via the gasket 19.
[0032]
As shown in the plan view of FIG. 1 (B), which is a view on arrow AA 'of FIG. 1 (A), a plurality of
thin through holes 21 are formed in the diaphragm 10 at predetermined positions. In the above,
for example, three through holes 21 are formed at predetermined radial positions equally
dividing into three from the center of the inner diameter of the diaphragm 10. However, the
through holes 21 may be formed at random positions. It is selected to be about 0.5 mmφ to 1
mmφ.
[0033]
A cap 22 is formed on the upper end of the voice coil bobbin 11 or the inclined portion of the
diaphragm 10 together with the bonding portion 23 of a highly airtight material such as
aluminum in a dome shape so that the upper end of the voice coil bobbin 11 is airtightly covered.
Are bonded to each other via an adhesive.
[0034]
Furthermore, it is configured in a funnel shape so as to cover the largest outer diameter diameter
portion of the frame 8 and does not emit sound from the diaphragm 10 configured to have a
substantially constant distance to the diaphragm. An airtight plate 24 made of synthetic resin or
the like is fixed on the gasket 19, and a predetermined airtight space 25 is formed between the
airtight plate 24 and the diaphragm 10.
[0035]
Further, the tinsel wire 16 is connected to the voice coil 12, and an audio signal is supplied to the
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voice coil 12 through an input terminal 15 attached to the frame 8.
[0036]
As described above, by assembling a small speaker, the first space 20a between the diaphragm
10 and the upper surface of the plate 5 and the above-described second space 20b are formed.
[0037]
Furthermore, as shown by a broken line in the center pole 6a or the yoke 6, the through holes
26a or 26b may be formed as necessary to lower the impedance formed in the first and second
space portions 20a and 20b under the damper 17. The sound pressure level of the low range of
the speaker device may be increased.
[0038]
FIG. 2 is a side sectional view of the speaker apparatus in the case where the speaker 3 shown in
FIGS. 1A and 1B is disposed in the speaker box 1 having the phase inversion ducts 18 and 18b of
the same configuration as FIG. FIG.
The speaker 3 shown in FIG. 2 has substantially the same structure as that described with
reference to FIGS. 1A and 1B except that the through holes 26a and 26b are not formed in the
center pole 6a and / or the yoke 6. The overlapping description with FIG. 1 (A) and FIG. 1 (B) is
omitted.
[0039]
The above speaker box 1 is made of ABS resin or the like, which is small and light with a volume
of about 1 to 3 liters, and when the diameter of the speaker 3 is 8 cmφ or less in diameter,
acoustic signals are transmitted from the terminal 13a to the voice coil 12 When the speaker 3 is
driven, the driving force F1 = M0.alpha.0 and the reaction force -F1 = M0.alpha.
[0040]
On the other hand, assuming that the number of the plurality of through holes 21 formed in the
diaphragm 10 is n, air flows into the first space 20 a formed on the front side of the damper 17
by the vibration of the diaphragm 10. The pressure in the volume of the first and second space
portions 20a and 20b fluctuates.
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[0041]
Due to the air flowing into the first space portion 20a, an acting force FD / n and a reaction force
-FD / n against this acting force are generated in the through hole 21 of the diaphragm 10.
[0042]
Therefore, countering the reaction forces -F1 and -F2 with the two speakers 3 and 3b as
described in Fig. 7 if counterbalanced such that FD / n + FD / n + ... = F1 like this The reaction
force of -F1 and the reaction force of-(FD / n + FD / n + ....) can be offset.
[0043]
Further, in the case of FIG. 2, the first duct 18 and the second duct 18b are used, and the opening
18c of the second duct 18b to the duct radiation force FD1 (or -FD1) of the opening 18a of the
first duct 18 Since the duct radiation force FD2 / 2 + FD2 / 2 {or-FD2 / 2 + (-FD2 / 2)} is
mutually offset and supported by FD1 FD FD2 / 2 + FD2 / 2, the speaker box 1 is swung As a
condition for preventing this, it is sufficient to satisfy the above-mentioned F1 ≒ FD / n + FD / n.
[0044]
The radiation force FD / n of the air passing through the through hole 21 formed in the
diaphragm 10 of the speaker 3 and the reaction force -FD / n make the equivalent mass of air by
the movement of the diaphragm 10 MA, and the through hole Assuming that the acceleration of
the air passing through 21 is αA, for example, the radiation force of the air radiated from the
through hole 21 when the diaphragm 10 moves forward becomes FD = MA · αA, and the
effective vibration area of the diaphragm 10 is SP · Assuming that the total area of the through
holes 21 formed in the diaphragm 10 is SA, then αA = SP / SA · αA, MA = 16/3 · aa 3 (ρ is the
density of air, a is the effective radius of the diaphragm The radiation force FD acting on the
through hole 21 can be easily determined.
[0045]
Furthermore, it is well known that the low frequency characteristic of the vibration system of the
speaker 3 is generally determined by Q0 at f0.
[0046]
Now, the effective mass of the speaker's vibration system is M0, the stiffness of the vibration
supporting portion is S0, the internal resistance of the output amplifier is R0, the voice coil
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10
resistance is Rv, the voice coil length is Lv (cm), the vibration system machine Assuming that the
resistance is Rm, the stiffness of the internal volume of the speaker box is Sc, the resistance in
the speaker box is Ra, and the magnetic flux is Bg, Q0 can be expressed by the following equation
(1).
[0047]
As apparent from the above equation (1), when the diaphragm 10 is driven, the mechanical
resistance Rm passing through the through holes 21 through the plurality of through holes 21
formed in the diaphragm 10 is increased, It is obvious that the denominator of the equation
increases and works to lower the value of Q0.
[0048]
Therefore, with the decrease of Q0, the transition of f0 to the high band side can be prevented,
the low band is expanded, and a speaker device capable of emitting a high-quality low band can
be obtained.
[0049]
In the loudspeakers of FIGS. 1 and 2, the airtight plate 24 completely covers the upper surface of
the diaphragm 10, but FIG. 3 shows a relatively large through hole 26 at the position of the
airtight plate 24 opposed to the center position of the cap 22. In this case, the other
configuration is the same as that of the speaker 3 described in detail in FIGS. 1 and 2.
In the case shown in FIG. 1 and FIG. 2, the condition for canceling or attenuating the reaction
force -F1 to the acting force F1 of the diaphragm 10 using one speaker 3 is F1 ≒ (FD / n + FD /
n + ...) In the configuration shown in FIG. 3, an action force FD3 and a reaction force -FD3 are
generated when air is driven in and out when the diaphragm 10 is driven by the through hole 26
formed in the airtight plate 24. Since FD3 or reaction force-FD3 is added to the equation to
support when the speaker 3 is driven, it is possible to increase the balancing condition at the
time of design by selecting F1 + FD3 ((FD / n + FD / n + ...).
[0050]
FIGS. 4 and 5 show still another embodiment of the speaker according to the present invention.
In these cases, airtight aluminum or the like joined to the upper portion of the diaphragm 10 of
the speaker 3 or the voice coil bobbin 11 is used. The dome-shaped cap has a double structure.
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11
[0051]
In the embodiment of FIG. 4, the first cap 22 is joined via the bonding portion 23 so as to cover
the upper surface of the voice coil bobbin 11 airtightly, and a plurality of through holes 21 are
formed at diameter positions larger than the outer diameter of the bonding portion 23. For
example, n pieces are drilled at an angular position n equally divided from the central position of
the diaphragm 10, and the second cap 27 rich in airtightness is laminated at a predetermined
distance L from the first cap 22. A plurality of through holes 21 which are bonded to the
diaphragm 10 and are bored in the diaphragm 10 are disposed between the first and second
caps 22 and 27.
[0052]
Furthermore, one through hole 28 is formed at a central position of the second cap 27.
[0053]
When the speaker 3 of this configuration is disposed in the speaker box 1 in the same manner as
in FIGS. Assuming that the air radiation force of the through hole portion 28 formed in the cap
27 is FD4 and -FD4, and the air radiation force of the through hole 21 formed in the diaphragm
10 is FD / n and -FD / n It suffices to satisfy / n + FD / n +...), And a force for supporting the
reaction force −F 1 can be provided in the speaker 3.
[0054]
In the embodiment of the invention shown in FIG. 5 of the same concept, in the same
configuration as FIG. 4, one through hole 29 is formed at the center of the first cap 22.
In this case, when a material having high airtightness is selected for the damper 11 and, for
example, a solution such as a synthetic resin is applied, the air radiated through the through hole
29 into the volume of small air in the second space 20b. Since the radiation force FD5 and its
reaction force -FD5 can be added, the balance equation can be F1.apprxeq.FD4 + (FD / n + FD / n
+...) + FD5.
[0055]
In the embodiment described above, the case where the airtight plate 24 has a funnel shape
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12
having substantially the same shape as the diaphragm 10 has been described, but the
configuration in which the speaker sound emitting hole 2a formed in the baffle board 2 of the
speaker box 1 of FIG. It is also possible to increase the volume of air in the space formed with the
diaphragm 10, that is, the stiffness SC1.
[0056]
According to the speaker apparatus of the present invention, the reaction to the action force
when the diaphragm is driven can be achieved by a simple structure in which only a single
speaker unit is used and a plurality of through holes are made in the diaphragm and an airtight
plate is provided. By offsetting or attenuating the force, it is possible to obtain a speaker device
capable of expanding and emitting a low frequency without swinging the small and light speaker
device.
Furthermore, according to the speaker of the present invention, the value of the resonance
sharpness Q0 at the lowest resonance frequency f0 can be reduced only by forming a through
hole in the diaphragm so that the low resonance frequency f0 can be shifted to the low frequency
side It becomes.
Furthermore, a speaker device capable of attenuating the reaction force of the speaker can be
obtained by disposing only one speaker having a through hole in the above-described diaphragm
in the speaker box.
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