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DESCRIPTION JPH09322294

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DESCRIPTION JPH09322294
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
triple coil speaker which can reduce the resonance sharpness Q0 at the lowest resonance
frequency and is suitable as a small and inexpensive magnetic shield type speaker.
[0002]
2. Description of the Related Art In general, in a small and inexpensive speaker, it is necessary to
reduce the resonance acuity Q0 at the lowest resonance frequency of the speaker to make the
bass reproduction advantageous in a small bus reflex system. When the resonance sharpness Q0
when attached to a small speaker is 0.58, it is considered that the bass reproduction is best, and
for that purpose, it is necessary to reduce the resonance sharpness Q0 in the speaker body.
Conventionally, it is very difficult to reduce the resonance acuity Q0 at the lowest resonance
frequency in such a small, low-cost speaker, and even if the drive magnet is made larger to
increase the magnetic energy, the magnetic saturation at the center pole And expensive.
[0003]
On the other hand, a magnetically shielded speaker using a cancel magnet magnetized in the
opposite polarity to the drive magnet has been known as an excellent device from the viewpoint
of solving such problems. In such a magnetically shielded speaker, as shown in FIG. 7, the cancel
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magnet 102, which is magnetized in the opposite polarity to the drive magnet 101, has two steps
so that the yoke 103 side has the same S pole via the yoke 103. In the figure, the N pole of the
drive magnet 101 in the upper stage in the figure is connected to the plate 105 facing the gap
with the peripheral portion of the voice coil 104, and the N pole of the cancel magnet 102 in the
lower stage is in contact with the shield cover 106. This is a speaker having a configuration in
which the shield cover 106 is raised near the outer periphery of the plate 105.
[0004]
In the same figure, reference numeral 107 denotes a center pole portion raised from the yoke
103 and disposed in the voice coil 104, 108 a damper, 109 a cone paper, 110 a cone-shaped
frame, 111 a tinsel wire, 112 an input terminal , 113 is a gasket. According to the magnetic
shield type speaker having such a configuration, not only the magnetic shielding effect but also
the magnetic flux of the gap of the magnetic circuit can be increased by about 10%, and the
resonance sharpness Q0 can be slightly lowered.
[0005]
However, even with the above-described magnetic shield type, that is, the configuration using the
cancel magnet magnetized in the opposite polarity to the drive magnet, the magnetic flux in the
gap of the magnetic circuit is No more than 10% could increase the flux. Therefore, although it is
possible to slightly lower the resonance sharpness Q0 at the lowest resonance frequency, there is
a problem that it is insufficient to make the bass reproduction advantageous.
[0006]
Therefore, in view of the above-mentioned problems, the present invention is a triple coil speaker
capable of significantly reducing the resonance sharpness Q0 at the lowest resonance frequency
by making effective use of magnetic energy, thereby making it possible to advantageously
reproduce bass. It is an issue to provide
[0007]
SUMMARY OF THE INVENTION In order to solve the above problems, a triple coil speaker
according to the present invention comprises a first plate, a first magnet, a second plate, a second
magnet and a second magnet each having an air gap coaxially. A magnet unit in which three
plates are arranged in this order from the front side of the speaker and the magnetization of the
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second magnet is opposite to the magnetization of the first magnet, and the circumference of the
voice coil bobbin arranged in the air gap The first, second and third voice coils provided on the
surface and spaced apart from each other by gaps on the gap side of the first plate, the second
plate and the third plate, and Do.
[0008]
According to the triple coil speaker having such a configuration, since the first to third voice coils
are provided, the second coil in the middle with respect to the current flow direction of the first
and third voice coils on both sides. The driving forces of the three coils are added by reversing
the direction of the current flow, and the driving forces become large.
Therefore, it is possible to make the best use of the energy of the first magnet and the energy of
the second magnet, thereby significantly reducing the resonance acuity Q0 at the lowest
resonance frequency of the speaker to advantageously reproduce the bass. Can.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below with reference to the drawings.
1 to 6 are views showing a triple coil speaker according to a first embodiment of the present
invention. FIG. 1 is a cross-sectional view of a magnetic shield type speaker which is a triple coil
speaker according to the present embodiment. In the present specification, hereinafter, "upper
side" will be described as meaning "front side" of the speaker.
[0010]
In FIG. 1, a cancel magnet (second magnet) 2 magnetized in the opposite polarity to the drive
magnet (first magnet) 1 magnetized to form a magnetic circuit is an intermediate of magnetic
permeability. The plate (second plate) 3 is disposed so as to overlap each other such that the
middle plate 3 side becomes the south pole together.
[0011]
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A magnetically permeable front plate (first plate) 4 is on the N pole surface of the drive magnet 1
on the front side (upper side in FIG. 1), and on the N pole surface of the cancel magnet 2 on the
rear side (lower side in FIG. 1). A magnetically permeable back plate (third plate) 5 is disposed,
which are assembled together as a magnet unit 6 as described later.
[0012]
Here, although the drive magnet 1, the cancel magnet 2, the front plate 4, the intermediate plate
3 and the rear plate 5 are all formed in an annular shape having a through hole (air gap) at the
center, they are divided in the circumferential direction It may be configured.
[0013]
The shield cover (magnetically permeable cover) 7 is formed of a bowl-shaped magnetically
permeable material whose upper portion is opened, and the lower portion is formed smaller in
diameter than the diameter of the upper portion through the step portion 7a.
The magnet unit 6 is disposed in the shield cover 7 in such a manner that the lower peripheral
portion is placed on the step portion 7a, and the N pole of the lower canceling magnet 2 is in
contact with the shield cover 7.
Further, the shield cover 7 is formed at a height near the outer periphery of the front plate 4, and
a cone-shaped frame 10 with a front end is attached to the top of the magnet unit 6, that is, the
front plate 4.
[0014]
A magnetically permeable center pole 8 is erected from the center of the bottom of the shield
cover 7. The center pole 8 is a through hole for the drive magnet 1 of the magnet unit 6 and the
cancel magnet 2, and each plate 4, 3 , 5 through the through holes 40, 30 and 50 provided at the
center, and the upper end is terminated at a position coincident with the upper surface of the
front plate 4.
[0015]
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Further, gaps a, b, c are formed between the center pole 8 and the inner peripheral surfaces of
the through holes 40, 30, 50 of the plates 4, 3, 5, respectively.
Therefore, a magnetic circuit that returns from the N pole of the drive magnet 1 to the S pole of
the drive magnet 1 through the front plate 4, the gap a, the center pole 8, the gap b and the
intermediate plate 3 and the N pole of the cancel magnet 2 to the back plate 5 , A gap c, a center
pole 8, a gap b, and a magnetic circuit that returns to the S pole of the cancel magnet 2 via the
intermediate plate 3 are formed, and a magnetic circuit as a sum of these two is configured.
[0016]
A cylindrical voice coil bobbin 9 is fitted around the center pole 8 at three locations facing the
gaps a, b and c of the voice coil bobbin 9, and more precisely, each plate 4, 3, 4 of the magnet
unit 6. First, second and third voice coils 13a, 13b and 13c are wound around the outer
circumference of the fifth through holes 40, 30 and 50 facing the inner circumferential surface.
[0017]
A front damper (first damper) 11 is attached between the upper end outer periphery of the voice
coil bobbin 9 and the frame 10, and a rear damper (a first damper) is installed between the lower
end outer periphery of the voice coil bobbin 9 and the bottom of the shield cover 7. 2) Damper
12 is attached.
Accordingly, the voice coils 13a, 13b, 13c are disposed in the respective gaps a, b, c and are
movably supported via the front damper 11 and the rear damper 12.
And each voice coil 13a, 13b, 13c is mutually connected in parallel. In FIG. 1, reference numeral
14 is a cone paper, 15 is a cap, 16 is a tinsel wire, 17 is an input terminal, and 18 is a gasket.
[0018]
Therefore, the configuration of the triple coil speaker can be summarized as follows. (A) Three
plates 3 to 5 are used to form three gaps a, b, c between the center pole 8 and the other. (Ii) The
voice coil 13a, 13b, 13c is wound around three circumferential surfaces of the voice coil bobbin
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9, and the positions thereof are opposed to the respective plates 4, 3, 5 via the gaps a, b, c. I
assume. (C) Using the cancel magnet 2 magnetized in the reverse polarity to the drive magnet 1,
the shield cover 7 is attached so as to cover the drive magnet 1 and the cancel magnet 2. (D) The
rear damper 12 is attached between the shield cover 7 and the voice coil bobbin 9 so as to
prevent the rolling motion of the voice coil bobbin 9. Preferably, the rear damper 12 and the
front damper 11 are formed symmetrically to each other. Further, the dampers 11 and 12 are
attached at positions sandwiching the drive magnet 1 and the cancel magnet 2. (E) The driving
forces of the three gaps a, b and c are operated to be added. That is, the direction of the current
flowing through the voice coils 13a and 13c in the upper and lower gaps a and c and the
direction of the current flowing through the voice coil 13b in the middle gap b are reversed.
[0019]
As in the above (e), three voice coils 13a, 13b and 13c are configured so that the directions of
the currents flowing through the coils 13a and 13b on both sides and the coil 13c in the middle
are mutually reversed. The driving force of the voice coil is added to become a large driving
force. Therefore, the energy of the drive magnet 1 and the energy of the cancel magnet 2 can be
utilized to the maximum, whereby the resonance sharpness Q0 at the lowest resonance
frequency of the speaker can be reduced.
[0020]
Now, assuming that the sizes of the drive magnet 1 and the cancel magnet 2 are equal, the
magnetic flux of the gaps a, b and c at three places of the magnetic circuit is B1 for the upper gap
a and 2 × B1 for the middle gap b. The lower gap c is B1 and the driving force is added to the
driving force of each of the three gaps a, b and c, so that the total B1 + 2 x B1 + B1 = 4 x B1.
[0021]
Since the three coils 13a, 13b and 13c are connected in parallel, the linear length of the coil
wound around the voice coil may be three times the impedance per one.
Therefore, the linear shape of the wire becomes thin and the resistance is tripled, so the effective
length of the voice coil becomes long.
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[0022]
Further, since the magnetic flux B1 of the gap is approximately 1⁄2 of the magnetic flux B of the
conventional magnetic shield type speaker, the entire three gaps are approximately 2 × B, which
is very large. Further, as described above, since the effective length of the coil is increased, it is
understood that the resonance sharpness Q0 at the lowest resonance frequency is significantly
reduced.
[0023]
It is known that the resonance sharpness Q0 can be expressed by the following equation. Q0 =
2πF0ReM0 / (B2L2) F0 = minimum resonance frequency of speaker Re = direct current
resistance of voice coil M0 = effective mass of vibration system B = magnetic flux of gap L =
effective length of voice coil in gap
[0024]
And although the weight of the voice coil is about twice the weight of the conventional voice coil
in the effective mass M0 of the vibration system, it only increases by about 30% as the mass of
the vibration system. The sharpness Q0 is equal to or less than half of the resonance sharpness
Q0 of the conventional magnetically shielded speaker, and the structure of the magnetic circuit
and the voice coil is excellent in lowering the resonance sharpness Q0.
[0025]
As a specific numerical value, the resonance sharpness Q0 of the conventional magnetic shield
type speaker is about 0.8, and the resonance sharpness Q0 of the triple coil speaker of the
present invention is about 0.25.
The direction of the current flowing through the middle voice coil 13b is opposite to that of the
voice coils 13a and 13c on both sides since the direction of the magnetic flux is reversed.
[0026]
As described above, in the small and inexpensive magnetic shield type speaker having the voice
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coil and the shield type magnetic circuit, the voice coil 13a, 13b, 13c is wound around three
places of the voice coil bobbin 9, and each voice coil 13a, 13b, 13c is Are connected in parallel,
and the magnetic energy possessed by the drive magnet 1 and the cancel magnet 2 is utilized to
the utmost, the resonance sharpness Q0 at the lowest resonance frequency of the speaker can be
significantly reduced.
[0027]
In addition, since the dampers 11 and 12 are located above and below the drive magnet 1 and
the cancel magnet 2, the speaker is very resistant to rolling motion, can withstand a large input,
and emits a large sound as a small speaker Will be able to
Furthermore, by forming the upper and lower dampers 11 and 12 in a symmetrical shape, nonlinearity of the dampers can be canceled and distortion can be reduced.
[0028]
Next, a method of assembling the triple coil speaker of FIG. 1 will be described with reference to
FIGS. 2 to 6. First, FIG. 2 will be described. FIG. 2 shows the magnet unit 6 in which the drive
magnet 1 and the cancel magnet 2 are combined with the three plates 3 to 5. The assembling
method of the magnet unit 6 will be described with reference to FIG.
[0029]
As shown in FIG. 3, a jig for assembly having a pole 22 as a plate inner diameter guide at the
center of the bottom surface 21, a hole 23 at the bottom of the periphery, and a step 25 at the
upper inside of the side wall 24. 20 is prepared, and the rear plate 5 is put into the jig 20 first.
[0030]
Next, an adhesive is applied to the upper surface of the back surface plate 5, and the cancel
magnet 2 which is not magnetized is placed thereon and adhered.
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The inner diameter of the back surface plate 5 is centered at the pole 22 portion of the jig 20,
and the outer diameter of the cancel magnet 2 is positioned approximately at the inner diameter
of the side wall 24 of the jig 20.
[0031]
Next, an adhesive is applied to the upper surface of the cancel magnet 2 and the intermediate
plate 3 is placed thereon. The inner diameter of the intermediate plate 3 is centered at the pole
22 of the jig 20. After the adhesive is dried, the cancel magnet 2 is magnetized while being put in
the jig 20.
[0032]
On the other hand, an adhesive assembly in which the front plate 4 and the drive magnet 1 are
bonded in advance, and in which the drive magnet 1 is magnetized in the opposite polarity to the
cancel magnet 2 is prepared. Then, an adhesive is applied onto the intermediate plate 3 that is in
the jig 20 and magnetized as described above, and the adhesive assembly is placed in the jig 20
with the drive magnet 1 facing down and driven. The magnet 1 is adhered to the intermediate
plate 3.
[0033]
Next, after the adhesive is dried, the rod is inserted from the hole 23 and the magnet unit 6 is
taken out of the jig 20 to obtain the magnet unit 6. On the other hand, as shown in FIG. 4, the
center pole 8 is attached to the center of the bottom of the shield cover 7 by using an adhesive
together with a fixing means such as a fixing screw 19 or the like.
[0034]
As shown in FIG. 5, a shield cover 7 to which the center pole 8 is attached, a rear damper 12, a
voice coil bobbin 9 with voice coils 13a, 13b and 13c, and a first voice coil spacer 26 are
prepared. The first voice coil spacer 26 has a cylindrical portion 26 a having an inner diameter
and an outer diameter of such a size as to form a thickness that enters the gap between the
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center pole 8 and the voice coil bobbin 9, and the voice coil bobbin 9. It has a projecting head
26b and a through hole 26c coaxially provided in the head 26b.
[0035]
First, the cylindrical portion 26a of the first voice coil spacer 26 is inserted into the inner
diameter of the voice coil bobbin 9, and the height positions of the voice coils 13a, 13b and 13c
are predetermined at the three gaps a, b and c of the magnetic circuit. Adjust so that it comes to
the height position (height position of plates 4, 3 and 5).
[0036]
Then, the first voice coil spacer 26 is inserted into the center pole 8, and the rear damper 12
interposed between the voice coil bobbin 9 and the shield cover 7 is adhered to the lower end
(rear end) of the voice coil bobbin 9.
That is, the outer peripheral edge of the rear damper 12 is bonded to the bottom peripheral edge
of the shield cover 7, and the inner peripheral edge of the rear damper 12 is bonded to the outer
peripheral surface of the voice coil bobbin 9.
[0037]
Next, a second voice coil spacer 27 as shown in FIG. 6 is prepared. The second voice coil spacer
27 has an inner diameter that is large enough to form a thickness that enters the gap between
the outer circumferences of the voice coils 13a, 13b, 13c and the inner circumferences of the
plates 4, 3, 5. It has a cylindrical portion 27a having an outer shape, a head 27b protruding
beyond the head 26b of the voice coil bobbin 9 and the voice coil spacer 26, and a through hole
27c coaxially provided in the head 27b.
[0038]
First, as shown in FIG. 6, the second voice coil spacer 27 is inserted to the outside of the voice
coil bobbin 9, precisely to the outside of the voice coils 13a, 13b and 13c, and the lower surface
of the head 27b is the first voice coil spacer. Insert until the top of the head 26b of 26 is hit. In
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this state, an adhesive is applied to the bottom peripheral step portion 7a of the shield cover 7,
and the magnet unit 6 is covered from above the voice coil spacer 27, and the inner diameter of
each plate 4, 3, 5 is made second. The cylinder is fitted to the cylindrical portion 27a of the voice
coil spacer 27, and the peripheral portion of the cancel magnet 2 is put in contact with the
stepped portion 7a of the shield cover 7, adhered by the adhesive, and then dried.
[0039]
After the adhesive dries, the second voice coil spacer 27 is removed, and the outer peripheral
edge of the front damper 11 is attached to the bottom peripheral edge of the frame 10 as shown
in FIG. Bond to the outer peripheral surface of 9 respectively. At this time, the first voice coil
spacer 26 remains inserted in the center pole 8. The frame 10 is attached on the front plate 4 in
advance by means such as caulking. In this state, the outer peripheral edge of the edged cone
paper 14 is adhered to the outer peripheral edge of the frame 10, and the inner peripheral edge
of the cone paper 14 is adhered to the outer peripheral surface of the voice coil bobbin 9.
[0040]
After the adhesive has dried, the tinsel wire 16 is soldered to the input terminal 17. The first
voice coil spacer 26 is then removed from the center pole 8 and the cap 15 is bonded to the
bottom of the cone 14 or to the tip of the voice coil bobbin 9. Then, a gasket 18 is adhered on
the outer peripheral edge of the frame 10 to complete the speaker.
[0041]
Since the triple coil speaker of such a configuration has the dampers 11 and 12 at the upper and
lower sides sandwiching the drive magnet 1 and the cancel magnet 2, the speaker is very strong
against rolling motion and can withstand a large input, which is small The speaker can emit a
loud sound. Further, by forming the front and rear dampers 11 and 12 in symmetrical shapes, it
is possible to cancel the non-linearity of the dampers and to reduce the distortion.
[0042]
As described above, it can be seen that by providing three voice coils and by attaching the
dampers 11 and 12 to the front and back of the magnet unit 6, it is possible to provide a speaker
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with a large allowable input.
[0043]
Furthermore, even in the case of a small speaker, there is an advantage that the resonance
sharpness Q0 can be reduced.
Then, by making the direction of the current flowing through the middle coil opposite to that of
the coils on the other two sides, the driving forces of the three coils are added, resulting in a
large driving force.
[0044]
Although the drive magnet 1 is disposed on the front side of the cancel magnet 2 with respect to
the speaker in the above embodiment, the cancel magnet 2 may be replaced so as to be disposed
on the front side of the drive magnet 1.
[0045]
In the above embodiment, the intermediate plate 3 between the drive magnet 1 and the cancel
magnet 2 is a common S pole, but the intermediate plate 3 between the drive magnet 1 and the
cancel magnet 2 is a common N pole. May be
[0046]
As described above, according to the present invention, the following excellent effects can be
obtained.
(1) Since the first to third voice coils are provided, the current flow direction of the middle
second coil is reversed with respect to the current flow direction of the first and third voice coils
on both sides. By configuring as described above, the driving forces of the three coils are added
to become a large driving force.
Therefore, it is possible to make the best use of the energy of the first magnet and the energy of
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the second magnet, thereby significantly reducing the resonance acuity Q0 at the lowest
resonance frequency of the speaker to advantageously reproduce the bass. Can.
[0047]
(2) Further, according to the above embodiment, since the dampers 11 and 12 are located above
and below the drive magnet 1 and the cancel magnet 2, the speaker is very strong against rolling
motion and can withstand a large input. As a small speaker, it becomes possible to emit a loud
sound.
[0048]
(3) Further, according to the above embodiment, by forming the front and rear dampers of the
magnet unit in a symmetrical shape, non-linearity of the damper can be canceled and distortion
can be reduced.
[0049]
(4) Further, by providing three voice coils and by attaching dampers to the front and back of the
magnet unit, it is possible to provide a speaker having a large allowable input.
[0050]
(5) Furthermore, as an effect of the above-described embodiment, the speaker box can be
miniaturized, and the improvement of the sound quality can be achieved.
[0051]
Brief description of the drawings
[0052]
1 is a cross-sectional view of a triple coil speaker according to a first embodiment of the present
invention.
[0053]
2 is a cross-sectional view showing a magnet unit 6 of the triple coil speaker of FIG.
[0054]
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3 is a cross-sectional view showing an assembly method using the assembly jig 20 of the magnet
unit 6 of FIG.
[0055]
4 is a cross-sectional view showing the shield cover 7 to which the center pole 8 is attached.
[0056]
5 is a cross-sectional view showing how to attach the voice coil bobbin 9 to the center pole 8 of
FIG.
[0057]
6 is a cross-sectional view showing how to attach the magnet unit 6 of FIG. 2 to the voice coil
bobbin 9 of FIG.
[0058]
7 is a cross-sectional view showing a conventional magnetic shield type speaker.
[0059]
Explanation of sign
[0060]
DESCRIPTION OF SYMBOLS 1 ...... Drive magnet (1st magnet), 2 ...... Cancel magnet (2nd magnet),
3 ...... Intermediate plate, 4 ...... Front plate, 5 ...... Back plate, 6 ...... Magnet unit, 7 ...... Shield Cover,
8 ... center pole, 9 ... voice coil bobbin, 10 ... frame, 11 ... front damper (second damper), 12 ...
rear damper (first damper), 13a, 13b, 13c ... ... voice coil, 14 ... cone paper, 15 ... cap, 16 ... tinsel
wire, 17 ... input terminal, 18 ... gasket, 19 ... fixing screw, 20 ... jig, 21 ... bottom surface, 22 ......
Pole (plate inner diameter guide), 23: hole, 24: side wall, 25: step portion, 26: first voice coil
spacer, 26a: tube portion, 26b: head, 2 c: through hole, 27: second voice coil spacer, 27a:
cylindrical portion, 27b: head, 27c: through hole, 40, 30, 50: through hole, a, b, c, ... ... Gap, 101 ...
Drive magnet, 102 ... Cancel magnet, 103 ... Yoke, 104 ... Voice coil, 105 ... Plate, 106 ... Shield
cover, 107 ... Center pole, 108 ... Damper, 109: cone paper, 110: frame, 111: tinsel wire, 112:
input terminal, 113: gasket
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