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JPH11215589

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JPH11215589
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
diaphragm of a speaker, and in particular, a diaphragm is provided with a mechanical impedance
changing portion which locally and asymmetrically changes the rigidity and viscoelasticity of a
material to obtain a good frequency. The present invention relates to a diaphragm of a speaker
adapted to obtain characteristics.
[0002]
2. Description of the Related Art A diaphragm for a conventional speaker is, as is well known, for
the purpose of improving frequency characteristics of output sound pressure. In order to
eliminate the divided vibration of the diaphragm, the shape and the material are devised to make
the rigidity as large as possible, and the frequency characteristic is made flat in the reproduction
band. Or 2. Means of concentrically providing a diaphragm on the diaphragm and expanding the
reproduction band using multiple resonances at a plurality of frequencies, and improving the
frequency characteristics by avoiding significant resonance at high levels at natural frequencies,
etc. Is adopted. Further, in both of the means, a damping material is applied to the outer
peripheral edge portion, that is, the edge portion of the diaphragm, and means for absorbing
energy of divided vibration and suppressing resonance is used in combination.
[0003]
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1
Among the above-mentioned prior art, in the means for increasing the rigidity of the former
diaphragm to eliminate divided vibrations in the reproduction zone, the rigidity of the diaphragm
is of a finite size or more. It is extremely difficult to expand the reproduction band, and there is a
disadvantage that only a limited band of speakers can be applied, and in the latter case in which
the corrugation is provided concentrically on the diaphragm surface, the corrugation is
circumferential. As a result, the sharp multiple resonance occurs at a plurality of frequencies,
which disturbs the frequency characteristics or degrades the timbre. In addition, also in the
means for applying a damping material to the edge portion, resonance suppression is limited to
the outer peripheral portion and a sufficient effect can not be obtained. There is a problem to be
solved that the efficiency of
[0004]
Therefore, according to the present invention, mechanical impedance changing portions in which
rigidity and viscoelasticity locally change are formed asymmetrically in the diaphragm to prevent
split resonance with high sharpness and extend the reproduction band, and also by simple
means. It is an object of the present invention to provide a diaphragm for a speaker which can
improve the frequency characteristics and prevent the decrease in efficiency as much as possible.
[0005]
The speaker diaphragm according to the present invention for achieving the above object is the
same as that shown in FIG. 1 showing the first embodiment and FIG. 2 showing the second
embodiment. In the speaker diaphragm of the present invention, the mechanical impedance
changing portion 1 having a spiral shape of at least one turn or more is formed from the inner
peripheral portion to the outer peripheral portion, to be described using the reference numerals
used in the drawings. It is characterized by
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION In order to practice the speaker diaphragm of
the present invention having the above-described construction, first, the shape of the diaphragm
2 is a cone-shaped diaphragm in each of the embodiments shown in FIGS. However, it may be flat
or dome-shaped regardless of this shape.
Also, the material may be a material that is usually used for a speaker diaphragm, but in the
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2
present embodiment it is a so-called paper using a fibrous material.
[0007]
In the first embodiment, the mechanical impedance changing portion 1 in the form of a spiral has
a shape of 11.2 cm in diameter as shown in a plan view in FIG. 1 and in a cross-sectional view in
FIG. The damping material 1a is formed on the surface of the plate 2 in a spiral form from the
inner circumference to the outer circumference by applying a round of 5 mm in width.
The damping material 1a is a synthetic resin paint to which a plasticizer has been added, and
stably holds high viscosity for a long time after application, absorbs the energy of local vibration
of the diaphragm, and suppresses the occurrence of resonance. In the present embodiment, the
damping material 1a is applied in a spiral form and is distributed asymmetrically and
continuously in the circumferential direction as well as in the radial direction, so no significant
split resonance occurs as in the conventional diaphragm. The frequency characteristic is good.
[0008]
Another embodiment of the mechanical impedance changing portion 1 is a groove-shaped
corrugation 1b as shown in a plan view in FIG. 3 as a second example and as a cross-sectional
view in FIG. Form a spiral. In the second embodiment, the spiral corrugation 1b is formed in a
range of two turns. In this groove-shaped corrugation 1b, the bending stiffness along the
direction perpendicular to the groove is small, and the portion with small rigidity is helical and
asymmetrical in both the circumferential direction and the radial direction continuously. Since it
is present, a mechanical distributed constant circuit having a clear characteristic value is not
formed as a whole of the diaphragm, and the frequency characteristics are improved in a wide
frequency range without causing significant split resonance.
[0009]
The mechanical impedance changing unit 1 in a spiral shape described above functions to
suppress the vibration or disperse the resonance at the part where the diaphragm splits and
vibrates in both embodiments, so the effect of improving the frequency characteristics is
extremely large. In the first embodiment, the effect is large even with a small amount of damping
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3
material to be applied, and when compared with the conventional example, the weight increase
of the diaphragm is not so large, so the efficiency hardly decreases. Also, in the second
embodiment, the weight of the diaphragm does not increase at all. Thus, both embodiments can
improve the frequency characteristics without reducing the efficiency.
[0010]
Further, the helical shape of the mechanical impedance changing portion 1 is not limited to the
above embodiments, and at least one turn or more between the inner periphery and the outer
periphery of the diaphragm so that the changing portion 1 exists on the entire surface of the
diaphragm. It is desirable to provide about 3 turns. If the number of turns is small, an area where
the mechanical impedance changing portion 1 does not exist is generated on the diaphragm
surface, and the action is reduced because it approaches the radial corrugation. It is equivalent to
densely formed concentric corrugations, which lowers the efficiency of the high region, and
rather, split resonance occurs. In the case of the first embodiment, the application width of the
damping material is also a problem, but about 10% to 30% with respect to the diameter of the
diaphragm is appropriate. If the application width is narrow, the effect can not be expected, and
if the application width is too wide, the weight of the diaphragm becomes excessive and the
efficiency of the speaker decreases.
[0011]
The frequency characteristics of the first example loudspeaker having the diaphragm shown in
FIGS. 1 and 2 are shown by solid lines in FIG. Compared with the frequency characteristics of the
original speaker before applying the damping material, the level difference between the peak of
the frequency characteristics and the dip becomes smaller compared to the frequency
characteristics of the original speaker before applying the damping material, and the average
sound pressure is reduced. Shows the effect of the diaphragm of the present invention in which
the helical mechanical impedance changing portion 1 is formed. Further, FIG. 6 shows the
frequency characteristics of the second embodiment speaker shown in FIG. 3 to FIG. 4 by a solid
line. Since the level difference between the peak of the frequency characteristic and the dip is
smaller in the band of 300 Hz to 10 KHz as compared with the frequency characteristic of the
original speaker shown by the dotted line in the figure, the average sound pressure is increased,
The effect of the diaphragm of this invention which formed the helical mechanical impedance
change part 1 is shown.
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[0012]
The basic configuration, action, and effects of the speaker diaphragm of the present invention
have been described above, and the first embodiment and the second embodiment have been
described in detail, but modifications of each embodiment will be described below. Do. FIG. 7
shows the front shape of the first modification of the first embodiment. The application width of
the damping material 1a is 5 mm and is a two-turn spiral. FIG. 8 is a front view of a modification
2 of the first embodiment. The application width of the damping material 1a is 5 mm and is a
three-turn spiral.
[0013]
FIG. 9 shows the front shape of the third modification of the first embodiment. The application
width of the damping material 1a is 10 mm and is a one-turn spiral. FIG. 10 is a front view of a
modification 4 of the first embodiment. The application width of the damping material 1a is 15
mm, and is a one-turn spiral. Although illustration of the frequency characteristic is omitted for
the above-described Modifications 1 to 4, the same effects as those of the first embodiment are
obtained. If the application width is larger than this range, the weight of the diaphragm increases
and the regeneration efficiency tends to decrease.
[0014]
FIG. 11 is a front view of a modification 1 of the second embodiment. The mechanical impedance
changing portion 1 of the first modification of the second embodiment is formed by helically
forming two groove-shaped corrugations 1b and 1b 'by mutually shifting them 180 degrees.
Although illustration of the frequency characteristic is omitted also in the first modification, the
same effect as the second embodiment is obtained.
[0015]
FIG. 12 shows, as a reference, the frequency characteristics of a conventional type speaker in
which a damping material is applied to the edge portion of the diaphragm, which is
conventionally employed for vibration suppression of the diaphragm in the above-described
original speaker. In order to improve the frequency characteristics to the same extent as in the
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5
embodiment, the damping material is applied to the edge portion of the diaphragm over the
entire circumference of the damping material 1c. As a result of applying a large amount of
damping material, the average sound pressure is reduced by about 2 dB because the diaphragm
weight is increased.
[0016]
Although the embodiments considered to be representative of the present invention have been
described above, the present invention is not necessarily limited to only the structures of these
embodiments and modifications, and includes the above-described components according to the
present invention, The present invention is intended to achieve the object of the present
invention, and can be appropriately modified and implemented within the range having the
effects described below.
[0017]
As is apparent from the above description, in the speaker using the speaker diaphragm according
to the present invention, the resonance due to the high-frequency resonance and the divisional
vibration of the diaphragm is dispersed and damped. Peaks and dips in the frequency
characteristics due to resonance are suppressed to improve the frequency characteristics, and
the tone quality and timbre of the reproduced sound are improved.
[0018]
In addition, since the mechanical impedance changing portion of the diaphragm adopted to
obtain the above-described effect hardly causes an increase in weight due to its structure, the
electro-acoustic conversion efficiency of the speaker does not decrease.
Further, with regard to the provision of such a mechanical impedance changing portion, in the
second embodiment, no extra material is required since it is completed simultaneously with the
diaphragm molding, and the amount of use of the damping material is small in the first
embodiment Therefore, the cost of materials does not increase in the production cost.
Therefore, the effect that a high-performance speaker can be provided at low cost can be
expected.
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[0019]
Brief description of the drawings
[0020]
1 is a plan view of the appearance of the first embodiment of the present invention.
[0021]
2 is a side cross-sectional view of the first embodiment.
[0022]
3 is a plan view of the appearance of the second embodiment.
[0023]
4 is a side cross-sectional view of the second embodiment.
[0024]
5 is a frequency characteristic diagram of the first embodiment.
[0025]
6 is a frequency characteristic diagram of the second embodiment.
[0026]
7 is a plan view of the appearance of a modification 1 of the first embodiment.
[0027]
8 is a plan view of the appearance of a modification 2 of the first embodiment.
[0028]
9 is a plan view of the appearance of a modification 3 of the first embodiment.
[0029]
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10 is a plan view of the appearance of a modification 4 of the first embodiment.
[0030]
11 is a plan view of the appearance of a modification 1 of the second embodiment.
[0031]
12 is a frequency characteristic diagram of the conventional example.
[0032]
Explanation of sign
[0033]
1 mechanical impedance changing portion 1a damping material 1b corrugation 2 diaphragm 3
edge 4 voice coil 5 magnetic circuit 6 frame
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