JPS6119299

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DESCRIPTION JPS6119299
[0001]
FIELD OF THE INVENTION The present invention relates to a diaphragm for a speaker. [Prior Art]
Conventionally, for example, a diaphragm for a so-called hard dome speaker is made of
aluminum (AA), titanium (T i>, magnes, ram (M (J), beryllium (Be), boron CB), etc. It is often made
of a single plate of metal or alloy thereof, ceramic, other inorganic material, synthetic resin,
paper, cloth and the like. And, in order to improve the acoustic effect, the diaphragm made of this
single plate J: J is intended to reduce its thickness and weight. (Problems to be solved by the
invention) However, if the thickness of the diaphragm is made thin and lightened, the rigidity is
reduced, and distortion due to asymmetry vibration of the diaphragm is generated in a low
frequency region, Distortion due to the axisymmetric split resonance increases, resulting in a
large peak dip in frequency characteristics. Also, it is known that the primary resonance of the
dome-shaped diaphragm occurs at a relatively low frequency at a portion slightly inside the
peripheral portion of the dome-shaped diaphragm. Then, since the wide-range reproduction limit
frequency of the speaker is limited to this resonance, it is necessary to make the rigidity of the
diaphragm as high as possible to prevent the resonance. By the way, if the rigidity is simply
increased, the thickness of the diaphragm may be increased, but on the other hand, the weight is
increased to lower the efficiency of the speaker. Therefore, it is necessary to increase the rigidity
and to reduce the weight. As a technology to satisfy such requirements, a diaphragm with a
laminated structure in which several kinds of lightweight members are stacked can be
considered, and in fact, a planar diaphragm with a core moon of d3 having a honeycomb
structure is used. It has been put to practical use. However, since it is extremely difficult in terms
of formability and adhesion to form a dome shape with a small radius of curvature in a
honeycomb structure, a dome-shaped diaphragm of fr 4 layer structure utilizing a honeycomb
structure is still put to practical use. Not. In general, the rigidity of the diaphragm (D> is the
following formula% equation% E · · · Young's modulus of the diaphragm (dyne / cm) t · · · ·
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thickness of the diaphragm cm · γ · · · Poisson of the diaphragm The ratio and Poisson's ratio in
this equation are small and squared, and may be omitted. Equation (1) is transformed as follows.
D = Et 3/12 ... (2) However, the material is assumed to be uniform. As seen from this equation (2),
the thickness (1) is proportional to the rigidity (D> and is raised to the third power, so that the
rigidity (D) of the J-plate is greatly increased by only a slight increase of (16). To be high.
By the way, now, if the surface density (σ) of the diaphragm is changed to a constant, the density
(は) has a relationship of σ− パ t ··············· (3) Substituting the equation (3) into the equation, D =
(E / 12) x (σ / ρ) 3 = (σ3 / 12) X (E / G) (4) From this equation, DCxE / D3 It can be seen that
(5). Then, U (-((r 77) / ・ ・ ・ (6) where L shoulder 1] sword; -Therefore, when the density (ρ)
is small and the Young's modulus (E) is large, the rigidity (D) is high, and the speed of sound (/ E
#)> is large, and the vibration appropriately occurs over a wide frequency. High efficiency, low
distortion, wide area reproduction limit increased, flat and wide frequency characteristics. In
addition, it is desirable that the internal loss (tan δ) be large to prevent resonance and reduce
distortion. The present invention has been made under such a background, so that it is
lightweight, high in rigidity, has a suitable internal loss, has a low distortion, has excellent
frequency characteristics, and is not only dome-shaped] -n type, flat type The purpose of this is
to provide a speaker diaphragm of a laminated structure. [Means for Solving the Problems] In
order to solve the above-mentioned problems, the diaphragm of the present invention is a
laminated structure in which light metal layers are respectively superposed on both sides of a
substrate formed of a foamable hard resin. . [Operation] The diaphragm of the present invention
is formed of foam + IU hard resin and light metal! Thus, it is light in weight, can be formed into
various shapes, and the density per month is small, and since these are put into one west layer
state to increase the V blow rate, the rigidity becomes high and the weight is light. And stiffness.
An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.
The diaphragm of this embodiment has a three-layered laminated structure in which light metal
layers 2 are superimposed on both sides of a diameter (35 mm of a substrate 1) formed in a
dome shape with a foamable hard resin. The substrate 1 is made of a material that can be
subjected to heat molding and bonding, and is made of an acrylic resin foamed 25 times, and its
thickness is 2 mm. Each light metal layer 2 is formed of an aluminum foil 3a having a thickness
of 20 μ or 30 μ on the convex side of the substrate 1 and is formed of aluminum g 3 b on the
concave side of the substrate 1 having a thickness of 20 μ. The respective aluminum foils 3a
and 3b are stuck on both sides of the substrate 10 (= J-type IC). Next, a method of manufacturing
the speaker diaphragm of this embodiment will be described. For making the speaker diaphragm
of this embodiment, a mold 11 shown in FIG. 2 is used.
This mold 11 is provided with a dome-shaped depression / v 1 die 12 and a projection 1 [die 13
corresponding to the 1 ′ ′ l ′ ′ 12 corresponding to the 1 ′ ′ l ′ ′ 12]. Have the heater
14 on the right. Then, first, the flat disk-like substrate 1 which is not yet dome-shaped is placed
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between the excitation die 12 and the male die 13 and molded into a dome-shape by a heat
press. The molding temperature at this time is 115 ° C., and the pressurizing time is about 5
minutes. Next, the respective aluminums e3a and 3b previously formed into a dome shape by
vacuum molding are respectively disposed on the convex surface side and the concave surface
side of the dome-shaped substrate 1, and the aluminum foil 3a, the substrate 1 and the aluminum
are further provided. The sheet-like heat-meltable resin adhesive 15 is sandwiched between the
foil 3 b and the substrate 1, and the mold 11 is again subjected to pressure heating and molding.
The heat fusible resin adhesive 15 melts on this, and the respective aluminum p 3 a and 3 b are
attached to both sides of the substrate 1 respectively. By the way, nylon non-woven hola 1-melt
is used as the heat melting resin adhesive 15 for weight reduction. Then, it is taken out of the
mold 11 and the outer periphery is trimmed to form a diaphragm having a three-layer structure,
and as shown in FIG. By the way, the acrylic resin foam forming the substrate 1 has a small
density (ρ) and is very light in weight to increase the rigidity (D) 1), and therefore, high rigidity
and weight reduction can be realized together. Furthermore, aluminum <Aj contributes to weight
reduction because it can easily form a tie foil. Then, the light metal layers 2 of the aluminum foils
3a and 3b are stacked on both sides of the substrate 1 to form three layers, and the synergetic
effect makes the entire A7 scale (E) larger than the individual Young's modulus (E) of each layer,
In addition, the weight was not less than 0.878 g to 1.077 g. This weight is approximately equal
to a dome-shaped aluminum diaphragm having a diameter of 55 mm and a thickness of 100 μ.
And, form like this! The frequency characteristic of the diaphragm is high in rigidity and light
weight, so as shown in FIG. 4, it is referred to as an aluminum single plate (hereinafter referred to
as A1 single plate). (2) The extension of the high region is better than the dome-shaped
diaphragm formed, and secondly, the harmonic distortion is also small. Although the diaphragm
of the embodiment is formed in a dome shape, the present invention is not limited to this shape,
and may be a cone shape or a planar shape. In this respect, since the substrate 1 is formed of a
foamable hard synthetic resin, it can be formed into any shape. Furthermore, the thickness of the
substrate 1 may not be constant, and may be nonuniform as needed.
In particular, since the driving position of the diaphragm that determines the high-frequency
reproduction limit frequency (Fil) of the speaker is in the vicinity of the outermost periphery of
the diaphragm, this portion may be thickened. Further, the substrate 1 is not limited to acrylic,
and may be a foam such as vinyl chloride. Also, the thickness of the light metal layer 2 may be
changed as appropriate. The light metal layer 2 in the embodiment is formed of aluminum foils
3a and 3b, but other light metals such as Ti and MqSBe or alloys thereof may be used, and the
aluminum foils 3a and 3b are anodized to form an oxide film. (Aj! zD3 may be formed to improve
its physical properties such as Young's modulus. Furthermore, in the embodiment, the aluminum
foils 3a and 3b are attached with the heat melting resin adhesive 15 and the light metal layer 2 is
superposed on the concave side of the substrate 1, but the light metal layer 2 is directly attached
by vapor deposition of aluminum or the like. It may be formed on both sides of the substrate 1.
そして、AI! The physical properties of the diaphragm formed of the single plate and the
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titanium (T i) single plate and the physical properties of the diaphragms of various three-layer
structures according to the present invention are as shown in Table 1 below. The diameter of
each of the diaphragms of Table 1 is 65 mm. A type: A 30 μ thick aluminum foil is attached to
the convex side of a 25 × foamed dome-shaped acrylic substrate, and a 20 μ thick aluminum
foil is attached to the concave side. B type: A 30 μ thick aluminum foil pasted on both sides of a
dome-shaped acrylic substrate of 25 times foam. Type C: A 20 μm thick aluminum foil pasted on
both sides of a 25 × foamed dome-shaped acrylic substrate. ρ
······················································································································· Speed of sound (cm) × 105tanδ ······
internal loss D ············ stiffness (dyne-cm) X 107C ············ Afl veneer stiffness Calculate the surface
density (σ) of the diaphragm with a three-layer structure and derive the stiffness (6) of the A1
deck having the thickness 1) · · which is the same as the one sided load (σ), Aj2 veneer The ratio
of the stiffness (D) of the diaphragm of the 3F structure to the stiffness (D ′) of the following
was determined. t · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · As evident from this Table 1, 3 The
diaphragm with a layered structure has a Young's modulus (E) lower than that of an Al single
plate or Ti single plate, but has a smaller density ()), so the speed of sound (rΣ;-) becomes equal
to or greater than that of an area density (σ). The rigidity is as high as 400 times or more
compared to the same Al single plate or Ti single plate, which greatly contributes to the
improvement of the frequency characteristics.
また、Aj! Since the internal loss (tan δ) is about four times or more as compared with a
single plate or a single Ti plate, resonance hardly occurs and so-called squeal of the diaphragm
can be stopped. As described above, the reason why the internal loss (tan δ) is large is based on
the difference in the material itself and the three-layer structure. [Effects of the Invention]
According to the present invention, since it is formed using a material having a low density,
weight reduction can be achieved, the rigidity tends to increase, and a light metal layer is further
superimposed on both sides of the substrate. Because of the layered structure, the rigidity is
further enhanced, and a large vibration damping effect, that is, internal loss occurs from the
characteristics of the material and the three-layered structure. Therefore, the frequency
characteristic is improved, distortion is reduced, and good sound quality can be obtained. In
addition, since the shape can also be freely, it is possible to easily manufacture one having an
optimum shape in terms of acoustic characteristics.
[0002]
Brief description of the drawings
[0003]
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The first weir is a longitudinal sectional view showing an embodiment of the diaphragm of the
present invention, FIG. 2 is a view showing the manufacturing process thereof, and FIG. 3 is a
longitudinal sectional view of a loudspeaker using the diaphragm of the present invention, The
figure is a comparison diagram of the frequency characteristics of the present invention and the
prior art.
1 ·· Substrate, 2 ··· Light metal layer.
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