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JPH11262090

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JPH11262090
[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]
In such a phase-reversal type speaker device, as shown in FIG. 4A, the speaker 3 is fixed 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. 4A, the speaker 3 is provided with a ring-shaped magnet 4 and a
plate 5 and a yoke 6 with a central hole attached so as to sandwich the ring-shaped 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.
The frame 8 of the speaker 3 is attached to the plate 5, and an edge 9 is provided on the outer
periphery of the frame 8. The edge 9 holds the outer periphery of the cone-shaped diaphragm 10
with arrows 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 represented as shown in FIG. 4 (B).
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2
[0009]
4A and 4B, 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 bass 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. 4A 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. 5, and in FIG. 5, the corresponding parts to FIG.
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[0013]
In FIG. 5, the speaker box 1 is made of synthetic resin and molded integrally with the baffle plate
2 in a box shape.
The speaker 3 having the same configuration as that described in detail in FIG. 4A 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. 5 described above, the reaction force of the duct
radiation forces 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 also difficult to lower.
[0021]
Furthermore, in the two loudspeakers in which the vibration system of the loudspeakers is made
equal, the higher the value of f0, the larger the Q becomes in proportion to f0.
[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.
[0023]
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In the speaker device of the present invention, a plurality of through holes are formed in an
airtight damper for holding a diaphragm and a voice coil bobbin, the upper portion of the voice
coil bobbin is closed with an airtight cap, and under the damper and cap A speaker provided with
a space portion capable of taking in and out air from the through hole of the damper is disposed
in the speaker box.
[0024]
According to the speaker apparatus of the present invention, only by performing simple
processing on one speaker, the reaction due to the speaker radiation force built in the small and
light speaker box can be offset to prevent the rocking and increase the low range and the damper
The equivalent mass of air passing through the plurality of through holes can provide a speaker
capable of lowering Q0 and expanding f0 to the low frequency side.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION The small-sized speaker of 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. 4 and 5 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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6
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 the voice coil 12 is
disposed in a magnetic gap 7 formed between the inner diameter periphery of the through hole
and the outer diameter of the center pole 6a. It will be set up.
[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.
[0031]
In order to obtain the damper 17 having airtightness, two or three thin cloths are stacked and
joined to form a damper, or a surface of the damper 17 coated with a synthetic resin solution or
the like is used. A plurality of thin through holes 21 are formed at predetermined positions as
shown in the plan view of FIG. 1 (B), which is a sectional view taken along line AA 'of 1 (A). In
FIG. 1 (B) The four through holes 21 are formed at the peak position of the corrugation that is
divided into four equal parts from the center of the inner diameter of the hole, but even in the
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7
valley portion of the corrugation or the position of the through holes 21 may be randomly
formed The diameter 21 is selected to be about 0.5 mmφ to 1 mmφ.
[0032]
The inner diameter of the damper 17 as described above is joined to the upper end portion of the
voice coil bobbin 11 via an adhesive, and the outer diameter portion is joined 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 of the diaphragm 10 is the upper opening rim of the frame 8 The gasket 19 is fixed via
the gasket 19.
[0033]
A cap 22 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 made of a highly airtight material such as
aluminum in a dome shape such that the upper end of the voice coil bobbin 11 is airtightly
covered. It is joined via an adhesive.
[0034]
Further, the tinsel wire 16 is connected to the voice coil 12, and an audio signal is supplied to the
voice coil 12 through an input terminal 15 attached to the frame 8.
[0035]
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.
[0036]
Furthermore, as shown by a broken line in the second space 20b of the center pole 6a or the
yoke 6, the through holes 24a or 24b may be formed as required by the first and second spaces
20a and 20b in the lower part of the damper 17. The impedance formed in 20b may be lowered
to raise the sound pressure level in the low range of the speaker device.
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[0037]
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 18a and 18b
having the same configuration as FIG. FIG.
In FIG. 2, the speaker 3 has substantially the same structure as the one described in FIGS. 1A and
1B except that the through holes 24a and 24b are not formed in the center pole 6a and / or the
yoke 6. The overlapping description with 1 (A) and FIG. 1 (B) is omitted.
[0038]
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.
[0039]
On the other hand, assuming that the number of the plurality of through holes 21 drilled in the
highly airtight damper 17 is n, the diaphragm 10 vibrates in the first and second space portions
20a and 20b formed on the back side of the damper 17 Air flows in, and the pressure in the
volumes of the first and second space portions 20a and 20b fluctuates.
[0040]
Due to the air flowing into the first and second space portions 20a and 20b, an acting force FD /
n and a reaction force -FD / n against this acting force are generated in the through hole 21 of
the damper 17.
[0041]
Therefore, countering the reaction forces -F1 and -F2 with the two speakers 3 and 3b as
described in FIG. 5 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.
[0042]
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Further, in the case of FIG. 2, the opening 18 c of the second duct 18 b with respect to the duct
radiation force FD 1 (or −FD 1) of the opening 18 a of the first duct 18 using the first duct 18 a
and the second duct 18 b. 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.
[0043]
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.
[0044]
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
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).
[0045]
As apparent from the above equation (1), when the diaphragm 10 is driven, the air resistance Rm
passing through the through hole 21 through the plurality of through holes 21 formed in the
damper 17 is increased, (1) It is clear that the denominator of the equation increases and works
to lower the value of Q0.
[0046]
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.
[0047]
Although FIG. 1 (A), FIG. 1 (B), and FIG. 2 demonstrated 1 sheet of damper with corrugation 9,
the upper damper 17a on the upper side with high airtightness and the lower lower damper with
good ventilation are shown in FIG. 17b is disposed inside the inner diameter of the coil bobbin
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10
11 and the inside of the frame 8. In FIG. 3, for example, a plurality of small air-permeable vents
in the valley portion near the outer periphery of the corrugation of the highly airtight upper
damper 17a. Since the lower damper 17b is made of a well-ventilated damper material, the air 26
entering and exiting the plurality of through holes 21 by the vibration of the diaphragm 10 is a
lower one as shown by the arrows in FIG. The action force and reaction force of FD / n and -FD /
n are generated to flow into and out of the second space 20a through the damper 17b, for
example, reaction of action force F1 generated by driving the diaphragm 10 of the speaker 3
Power up F1 It is possible to cancel out by the action force FD / n of air when passing through
the plurality of through holes 21 bored in the pad 17a.
In addition, because of the double damper structure, the volume of the first space 20a below the
upper damper 17a can be increased, and the acting forces FD / n and -FD / n of the double
damper portion can be increased. Can do.
[0048]
According to the speaker apparatus of the present invention, a simple structure having only one
speaker unit and only a plurality of through holes in the damper cancels or attenuates the
reaction force to the acting force when the diaphragm is driven. Thus, it is possible to obtain a
speaker device capable of emitting sound by expanding the 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 thin
through hole in the damper, and the low band resonance frequency f0 can be shifted to the low
band 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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