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JPH11355878

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DESCRIPTION JPH11355878
[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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For example, as shown in FIG. 4A, the speaker 3 is provided with a ring magnet 4 and a plate 5
and a yoke 6 having a central hole attached so as to sandwich the ring magnet 4. A disk-like
member having a cylindrical center pole 6a at its center is formed between the inner diameter
side of the plate 5 and the center pole 6a 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 cone-shaped
diaphragm 10 is held by the edge by the gasket.
[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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[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 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. 4A is the acceleration α0 acting on the diaphragm 10 of the speaker to
the equivalent mass M0 of the speaker 3, that is, F1 = M0 · α0 It can be expressed.
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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3
[0013]
In FIG. 5, 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. 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, since the reaction force of the duct
radiation forces FD1 and FD2 between the first and second ducts 18 and 18b-FD1 are
respectively offset, the first and second speakers 3 and 3b The reaction forces -F1 and -F2 of the
radiation forces F1 and F2 can cancel each other if F1 .apprxeq.F2.
[0017]
However, in the above configuration, a pair of the speaker box 1 is provided to support and
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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
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 present invention is to provide a small and light
speaker box by adding a space forming member to one speaker unit. By counteracting or
attenuating the reaction force of the radiation force of the installed speaker to prevent the swing
of the speaker device, to radiate strong low frequency and reduce Q0, and to shift the speaker's
f0 to the low frequency side It is designed to expand the low band and to emit good low band
radiation.
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[0023]
In the speaker device of the present invention, acoustic compliance is formed between a
diaphragm and a space forming member disposed behind the diaphragm, and a through hole is
formed in the space forming member. When a sound radiation force in a predetermined direction
is given to the diaphragm, air is made to flow in and out through the through hole.
[0024]
According to the speaker apparatus of the present invention, only by providing the space forming
member behind the diaphragm of one speaker, the reaction by the speaker radiation force built
in the small and light speaker box can be offset to prevent the rocking. As the area increases, the
equivalent mass of air passing through a plurality of through holes formed in the diaphragm
forming the space forming member can lower the Q0 of the speaker and expand f0 to the low
side.
[0025]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The small-sized speaker apparatus
of the present invention will be described in detail below with reference to FIGS.
The parts corresponding to the speaker devices shown in FIGS. 4 and 5 in the present invention
are indicated by 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 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 magnetic circuit described above, and the voice coil bobbin 11 is held via the
damper 17 having a corrugated corrugation that can vibrate in the vertical direction. .
[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
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7
periphery of the bottom portion of the frame 8.
Further, the inner diameter of a funnel-shaped second diaphragm 23 which is a space forming
member with a free or fixed edge 9b made of paper or the like is joined to the upper outer
diameter portion of the voice coil bobbin 11, and the second diaphragm 23 is formed. The largest
diameter portion of the second is bonded to the step 8a of the frame 8 via an adhesive.
[0032]
In the second diaphragm 23, as shown in the plan view of FIG. 1 (B), which is a sectional view
taken on line AA 'of FIG. 1 (A), a plurality of thin through holes 21 are formed at predetermined
positions. In 1 (B), for example, three through holes 21 are formed at predetermined radial
positions equally dividing the center of the inner diameter of the second diaphragm 23, but the
positions of the through holes 21 may be randomly formed, The diameter of the through holes
21 is selected to be about 0.5 mmφ to 1 mmφ.
[0033]
Further, the inner diameter of a funnel-shaped first diaphragm 10 with a free or fixed edge 9
made of paper or the like like the second diaphragm 23 is joined to the upper outer diameter of
the voice coil bobbin 11, A predetermined airtight space 25 is formed between the first
diaphragm 10 and the second diaphragm 23 by fixing the largest diameter portion of the
diaphragm 10 to the upper opening edge of the frame 8 through the gasket 19. .
[0034]
The upper end of the voice coil bobbin 11 or the inclined portion of the diaphragm 10 is formed
of a highly airtight material such as aluminum in a dome shape, and the cap 22 is the upper end
of the voice coil bobbin 11 or the central opening of the first diaphragm 10 It is joined via an
adhesive so as to airtightly cover the nearby inclined portion.
[0035]
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.
[0036]
As described above, by assembling the small-sized speaker, the first space 20a between the
second diaphragm 23 and the upper surface of the plate 5 and the above-mentioned second
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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 and the speaker 3 is driven, the driving force F1 = M0.multidot..alpha.0 and the reaction
force -F1 = M0..alpha.0 in the F1 direction act on the first diaphragm 10.
[0040]
On the other hand, assuming that the number of the plurality of through holes 21 pierced in the
second diaphragm 23 is n, the air in the airtight space 25 corresponds to the driving of F1 of the
first and second diaphragms 10 and 23, It flows in from the direction of the first and second
spaces 20a and 20b of the speaker 3 through the through hole 21 and the first and second
spaces 20a and 20a of the speaker 3 from the space 25 for driving in the -F1 direction. Spill in
the direction of 20b.
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9
That is, the pressure in the volume between the space parts 25 will fluctuate.
[0041]
The air flowing into and out of the space 25 generates an acting force FD / n and a reaction force
-FD / n of the acting force at the through hole 21 of the diaphragm 23.
[0042]
Therefore, if counterbalance such that FD / n ≒ F1 holds, the reaction forces -F1 and -F2 are
canceled using the two speakers 3 and 3b as described in FIG. 7, and the reaction of -F1 is also
obtained. The force and the reaction force of -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 (or -FD2) of the above is mutually offset and
supported by setting FD1 ≒ FD2, as a condition for preventing the speaker box 1 from swinging,
the above-mentioned F1 ≒ FD / n is satisfied. It will be good.
[0044]
Now, in the speaker apparatus shown in FIG. 2, the volume of the speaker box 1 is VB, the
volume of the space 25 between the first and second diaphragms 10 and 23 is VC, and the
diaphragms 10 and 23 move. The volume flowing in and out of (VB) to VB (VC) is ΔVC, the
amplitudes of the first and second diaphragms 10 and 23 are X, the effective area of the second
diaphragm 23 is S, and the total area of the through holes 21 Assuming that S.sub.k is S.sub.k,
when the first and second diaphragms 10 and 23 are not driven, the volumes V.sub.B and V.sub.c
may be regarded as 1 atm (hereinafter referred to as P), and the relationship of the equation (1)
is Until it is true, .DELTA.Vc releases or sucks air into the speaker box 1.
[0045]
If the equation (1) is simplified, the volume change ΔVC is
[0046]
Here, since VC << VB, equation (2) can generate FD / n by causing a change in volume.
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10
[0047]
Therefore, in order to support the reaction force -F1 of the sound radiation force F1 of the
diaphragm 10 and the air radiation force FD / n of the through hole 21 of the diaphragm 23 and
the reaction force -FD / n thereof, the through hole 21 is used. The acceleration of the passing air
is S / SK · α0 (where M0 is the equivalent mass of the first diaphragm 10, α0 is the acceleration
of the diaphragm, and MU is the equivalent mass of the second diaphragm 23) FD / n = S / SK ·
α 0 · MU M M 0 · α 0 (4) If the speaker 3 mounted on the speaker box 21 is set to -F 1 ス ピ ー
カ -FD / n, support each other Can do.
[0048]
FIG. 3 shows another configuration of the speaker used in the speaker device of the present
invention, and only differences from FIG. 1 will be described below, the same reference numerals
are given to the same parts, and duplicate explanations will be omitted.
[0049]
In the configuration of FIG. 3, the space forming member disposed on the rear surface of the
diaphragm 10 is formed as an airtight damper 23a.
In order to obtain the airtight damper 23a, for example, two or three thin cloths are stacked to
form the airtight damper 23a, or a synthetic resin solution or the like is applied to the surface of
one damper cloth or the like. What is necessary is just to use.
[0050]
The damper 23a is formed in a substantially concave reverse dome shape, and an inner diameter
substantially the same diameter as the outer diameter of the voice coil bobbin 11 is bored in the
central portion, and the lower portion of the voice coil bobbin 11 under the mounting portion of
the first diaphragm 10 is It is joined to the side with adhesive etc.
[0051]
Further, in the same manner as in FIG. 1, through holes 21 are bored at predetermined angular
01-05-2019
11
range positions from the central portion of the damper 23a in these peaks or valleys in which a
plurality of concentric corrugations are formed.
For example, in FIG. 3, by forming three through holes 21 at one concentric corrugation position,
the radiation forces FD and -FD of air generated by air flowing in and out of the through holes 21
of the damper 23a are FD / 3 and -FD / 3.
[0052]
In the case of FIG. 3, the opening area of the damper 23a may be set to SK, and the abovementioned equation (4) may be defined.
[0053]
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.
[0054]
Now, the effective mass of the vibration system of the speaker shown in FIGS. 1 and 3 described
above is M0, the stiffness of the vibration supporting portion is S0, the internal resistance of the
output amplifier is R0, the resistance of the voice coil is Rv, and the length of the voice coil is Lv
Assuming that the mechanical resistance of the vibration system 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 (5).
[0055]
As apparent from the above equation (5), when the diaphragm 10 is driven, the mechanical
resistance Rm passing through the through hole 21 through the plurality of through holes 21
formed in the air forming members 23 and 23a increases. It is obvious that the denominator of
equation (5) becomes large and works to lower the value of Q0.
[0056]
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.
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12
[0057]
According to the speaker device of the present invention, the single speaker unit is used, and the
space forming member provided below the diaphragm is simply driven by the plurality of
through holes. By counteracting or attenuating the reaction force to the acting force, it is possible
to obtain a speaker device capable of emitting sound by expanding the low range 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 by only forming a through
hole in the second diaphragm or damper which is a space forming member, and the low
frequency range The resonance frequency f0 can be shifted to the low frequency side.
Furthermore, a speaker capable of preventing the swinging of the speaker box by attenuating the
reaction force of the speaker only by arranging one speaker having a through hole in the second
diaphragm or damper described above in the speaker box. The device is obtained.
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