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JP2001025088

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JP2001025088
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker with an expanded piston motion band used for sound reproduction equipment and the
like.
[0002]
2. Description of the Related Art Conventionally, the performance of a loudspeaker has been
improved, and in particular, from the viewpoint of widening a piston motion band, that is,
increasing a first resonance frequency, a registered utility model 2538601 has been proposed.
The speaker described in is known.
[0003]
The speaker described in the same publication has a rib extending in the normal direction and
the circumferential direction having at least one intersection, and the top of the rib at the
intersection is continuous and a three-dimensional structure The diaphragm main body can be
appropriately reinforced by adopting such a configuration, and the piston motion zone can be
expanded by enhancing the strength and rigidity of the diaphragm. It was a thing.
[0004]
However, according to the above-described conventional configuration, the following problems
occur.
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[0005]
【0005】1.
Due to the weight increase of the rib portion, the sound pressure is reduced.
[0006]
【0006】2.
In the case of an integrally formed rib with the diaphragm body, the mold structure becomes
complicated and the cost becomes significantly high.
[0007]
【0007】3.
In the case of a separate piece rib, a separate die having a complicated structure for producing
the rib portion is required, and a separate step for rib attachment is required, which significantly
increases the cost.
[0008]
The present invention solves these problems of the prior art, and widens the piston motion band
with a lightweight diaphragm without causing a significant increase in cost and a decrease in
sound pressure, and a flat speaker with a high frequency characteristic. Intended to be provided.
[0009]
SUMMARY OF THE INVENTION The speaker according to the present invention is a speaker
constituted by a diaphragm having a bent portion in the front direction at the outermost
periphery.
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[0010]
According to this configuration, since the diaphragm outer peripheral portion can be reinforced,
the primary resonance, that is, the piston motion band can be expanded.
In addition, since the bonding angle between the diaphragm and the inner diameter of the edge
roll can be made closer to a straight line, it is difficult for the sound wave propagation to be
folded back, the interference of the propagation sound wave can be reduced, and the high region
characteristic is flattened. It can.
[0011]
Further, the speaker of the present invention is constituted by the diaphragm in which the
density of the bent portion is larger than that of the other portions. With this configuration, the
strength of the bent portion on the outer periphery of the diaphragm can be further enhanced.
Further, since the high density portion is only the bent portion, it is possible to suppress the
weight increase due to the increase of the density as much as possible.
[0012]
DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be
described below with reference to the drawings.
[0013]
(First Embodiment) FIG. 1 is a cross-sectional view of a loudspeaker according to a first
embodiment.
This speaker is 12 cm in diameter. Reference numeral 1 denotes a field portion formed of a
ferrite magnet having an outer diameter of 60 mm and a thickness of 9 mm, an iron top plate
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3
having an outer diameter of 55, and an iron yoke having an outer diameter of 55 in the same
manner. The voice coil 3 with an aperture diameter of 16 is inserted in the magnetic gap portion
formed by the top plate and the yoke. Further, an iron frame 2 of thickness t 0.7 is fixed to the
upper portion of the field section 1, and the outer periphery of the urethane uproll edge 7 of R4
is fixed to the frame 2 and the inner periphery of the voice coil 3 There is disposed a pulp
vibrating diaphragm 5 with a weight of 1.0 g fixed thereto. The diaphragm 5 is a curved cone of
R60 having a center in the back surface direction of the diaphragm, and a bent curved surface 6
of R12 having a center in the front surface direction of the diaphragm is disposed in the
circumferential direction on the outer peripheral portion. The innermost diameter of the
diaphragm is φ17.2, the outermost diameter is φ87, and the junction between the curved
surface R60 and the bent curved surface 6 of the outer peripheral portion R12 is at the position
of diameter φ80. Further, the bonding angle at the bonding portion between the bent portion
and the inner diameter of the edge roll is 130 °. Furthermore, a dust cap 8 made of pulp and
having an outermost diameter of 32 is disposed on the front surface of the diaphragm 5.
[0014]
The physical properties of the diaphragm are as follows: Young's modulus = 2 × 10 9 [N / m 2],
density = 400 [kg / m 3], and internal loss = 0.05. The physical properties of the edge are as
follows: Young's modulus = 1 × 10 8 [N / m 2], density = 800 [kg / m 3], internal loss = 0.3.
[0015]
The operation of the loudspeaker according to this embodiment configured as described above
will be described.
[0016]
FIG. 2 shows simulation results of sound pressure frequency characteristics of the loudspeaker
shown in the first embodiment and the conventional loudspeaker by the finite element method.
Here, the diaphragm of the conventional speaker is a general curved cone of R60 in which the
curved surface inside the bent portion of the diaphragm of the first embodiment is extended to
the outermost diameter of the diaphragm. Furthermore, eight ribs at regular intervals in the
normal direction of the back side of the diaphragm and three ribs at regular intervals in the
circumferential direction are arranged ribs having a height of 2 mm and a width of 2 mm.
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[0017]
As shown in FIG. 2, the piston motion band, that is, both primary resonance frequencies are
equivalent at about 2 kHz, but the peak levels of secondary and tertiary resonances including this
primary resonance are the present embodiment. The form 1 is larger by about 3 dB or more.
That is, the loudspeaker according to the present embodiment exhibits a flatter characteristic at a
higher level of sound pressure than the loudspeaker of the conventional example, and is more
preferable as the loudspeaker characteristic.
[0018]
This is due to the folding of the vibration propagation of the diaphragm. That is, sound waves
propagate from the inner diameter of the diaphragm, but the sound waves are interfered by
folding back at the junction with the edge to disturb the characteristics. Generally, this
phenomenon is more likely to occur as the bonding angle of the bonding portion between the
diaphragm and the edge roll approaches a right angle, and as the internal loss of the diaphragm
and the edge is smaller.
[0019]
Next, in order to explain the superiority of the present invention more quantitatively, the
characteristic change due to the difference in the shape of the diaphragm outer diameter portion
will be described below.
[0020]
3 (a) to 3 (d) show cross-sectional views of the diaphragm.
(A) is a shape according to the present embodiment. (B) is the one where the position of the bent
part is different from (a), (c) is a normal diaphragm without bending, (d) is a diaphragm where
the outside from the bent part of (a) is a horizontal surface . The shape of the diaphragm on the
inner side of the bent portion and the shape of the edge are all the same, and the material is
completely the same.
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[0021]
FIG. 4 shows the simulation results of the sound pressure frequency characteristics of the
speaker having the diaphragm of (a) and (b) of FIG. In the shape of (b), the bending position is a
diameter φ60, and the bending portion is a curved surface of R50 having a center in the upper
surface direction of the diaphragm.
[0022]
From the figure, the shape (b), that is, the characteristic C, is lower than that of the first
embodiment with a first-order resonance frequency of 1.7 kHz. This is because the reinforcing
effect of the diaphragm outer diameter, which is the generation site of the primary resonance, is
reduced. Also, it can be confirmed that the number of resonance peaks is increasing. This is
because the resonance mode of the bending portion itself is further added.
[0023]
That is, the speaker (a) according to the present embodiment has higher primary resonance
frequency and flatter characteristics as compared with the speaker of the shape (b), and is more
preferable as the speaker characteristic. There is.
[0024]
FIG. 5 shows the simulation results of the sound pressure frequency characteristics of the
loudspeaker having the diaphragm of (a) and (c) of FIG.
In addition, about the shape of (c), the outer side from a bending position is a curved shape
which extended the curved surface inside. The bonding angle between the outermost periphery
of the diaphragm and the inner diameter of the edge roll is 105 °.
[0025]
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From the figure, the shape (c), that is, the characteristic D, has a primary resonance frequency of
1.3 kHz, which is lower than that of the first embodiment. This is because the strength of the
diaphragm outer diameter which is the generation site of the primary resonance is low. Also, the
level of the resonance peak is large. This is because the bonding angle between the outermost
periphery of the diaphragm and the inner diameter of the edge roll is small, and the sound wave
is easily folded back.
[0026]
That is, the loudspeaker (a) according to the present embodiment has a higher primary
resonance frequency and flatter characteristics than the loudspeaker of the shape (c), and is
more preferable as the loudspeaker characteristics. There is.
[0027]
FIG. 6 shows the simulation results of the sound pressure frequency characteristics of the
loudspeaker having the diaphragm of (a) and (d) of FIG.
In addition, about the shape of (d), the outer side from a bending position is comprised by the
horizontal surface to an edge roll inner diameter. The bonding angle between the outermost
periphery of the diaphragm and the inner diameter of the edge roll is 90 °.
[0028]
From the figure, the shape (d), that is, the characteristic E has the first primary resonance
frequency substantially the same, but the level of the resonance peak is large. This is because the
outer peripheral portion of the diaphragm is reinforced and the primary resonance frequency
becomes equivalent to that of the first embodiment, but the bonding angle between the
outermost periphery of the diaphragm and the inner diameter of the edge roll is small, and the
sound wave is easily folded back. It is.
[0029]
That is, the loudspeaker (a) according to the present embodiment exhibits flatter characteristics
than the loudspeaker of the shape (d), and is more preferable as the loudspeaker characteristics.
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[0030]
As described above, it is understood that the piston motion band, that is, the first resonance
frequency can be increased and the flattening of the characteristics can be realized by the shape
as in this embodiment.
[0031]
Here, with regard to the bending position, assuming that the cross-sectional width from the
innermost peripheral portion to the outermost peripheral portion of the diaphragm in the
diaphragm cross section is W, and the cross-sectional width from the innermost peripheral
portion to the bending position is W1, W1 It has been confirmed by simulation using the finite
element method that the reinforcement effect as shown in the first embodiment can be obtained
if /W≧0.7.
In the first embodiment, W1 / W = 0.9.
Further, in the shape having the characteristic C in FIG. 3B and FIG. 4, W1 / W = 0.6.
[0032]
As for the bonding angle between the diaphragm and the roll portion of the edge, it can be
confirmed that when the diaphragm having the physical properties according to the first
embodiment and the edge are used, a large peak hardly occurs from about 120 °. There is.
[0033]
Although in the first embodiment, the curved curved surface of R12 is arranged at the outer
peripheral portion of the diaphragm, it goes without saying that similar effects can be obtained
even if a linear curved flat surface is arranged instead of the curved surface. It is
[0034]
Second Embodiment Next, a speaker was prepared, which was made of a diaphragm in which the
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density of the bent portion is 1.5 times that of the same portion of the speaker of the first
embodiment.
The density difference is produced by performing paper separation during pulp vibratory plate
making.
The other configuration is the same as that of the first embodiment.
[0035]
The operation of the loudspeaker of this embodiment configured as described above will be
described.
[0036]
FIG. 7 shows simulation results of sound pressure frequency characteristics of the loudspeaker
according to the present embodiment.
[0037]
As shown in the figure, although the sound pressure is slightly reduced, the first resonance
frequency is higher than 2 kHz in the first embodiment, which is 2.3 kHz.
Also, the level of the resonance peak is almost the same.
This is because the rigidity of the diaphragm is increased due to the density increase of the bent
portion of the diaphragm.
[0038]
That is, according to the present embodiment, the first resonance frequency (piston motion band)
can be increased, and a speaker having more preferable characteristics can be provided.
[0039]
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As described above, according to the speaker of the present invention, the outer peripheral
portion of the diaphragm, which is the generation site of the first resonance mode of the
diaphragm, is reinforced by the bent shape of the outer peripheral portion of the diaphragm. As a
result, the primary resonance, that is, the piston motion band can be expanded.
In addition, since the bonding angle with the edge roll portion can be made more linear, it is
difficult for the sound wave propagation to be folded back, the interference of the propagation
sound wave can be reduced, and as a result, the high frequency characteristic can be flattened.
[0040]
Further, according to the speaker of the present invention, the strength can be further increased
by increasing the density of the diaphragm bending portion. As a result, it is possible to easily
widen the piston motion band while suppressing the sound pressure drop due to the density
increase as much as possible.
[0041]
Thus, the cone type loudspeaker of the present invention is of great industrial value.
[0042]
Brief description of the drawings
[0043]
1 is a cross-sectional view showing a speaker according to a first embodiment of the present
invention
[0044]
Fig. 2 A diagram showing simulation results of sound pressure frequency characteristics of the
same speaker
[0045]
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Fig. 3 Diagram showing the shape of diaphragm and edge roll joint
[0046]
Sound pressure frequency characteristics simulation results of the speakers of (a) and (b) in FIG.
4
[0047]
Sound pressure frequency characteristics simulation results of the speakers of (a) and (c) in FIG.
5
[0048]
6 shows the simulation result of sound pressure frequency characteristics of the speakers of (a)
and (d) of FIG. 3
[0049]
7 is a diagram showing the simulation result of the sound pressure frequency characteristics of
the speaker according to the second embodiment of the present invention.
[0050]
Explanation of sign
[0051]
DESCRIPTION OF SYMBOLS 1 field part 2 frame 3 voice coil 4 damper 5 diaphragm 6 diaphragm
bending part 7 edge 8 dust cap 9-12 diaphragm
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