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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker diaphragm having a sand-in structure in which a surface material is bonded to both sides
of a core material. The configuration of the prior art and its problems In general, the diaphragm
of the speaker has the same phase over the entire frequency band to be used, that is, it is ideal
that the piston vibrates and sound is generated if the diaphragm is deformed or split vibration
occurs during vibration. Pressure frequency characteristics, distortion factor. The phase
characteristics and the like deteriorate to hinder high fidelity reproduction. In order to solve
these problems, in recent years, a flat diaphragm using a Nickhamzund inch structure or the like
has been adopted. 0 A surface material of a diaphragm using an aluminum honeycomb core
conventionally used in FIG. A top view showing a core shape partially cut away is shown. 1 is an
axisymmetric core in which honeycombs made of aluminum of 20 I typx q are expanded radially,
and 50 ? 722 thick aluminum 2 is adhered to both sides of 1. The diameter of the diaphragm is
200 m1 lr and the height is 61 Hm. However, the flat diaphragm made of the honeycomb zand
inch structure is complicated in structure, and it is considerably expensive because it requires
several tens of manufacturing steps and many kinds of members, which is more expensive than
conventional cone paper etc. It was also difficult to make it cheap. A speaker using a plane
diaphragm made of a honeycomb sandwich structure has a high limit frequency fh 2 dog width
by a so-called joint drive system in which a voice coil is adhered to and driven by a voice coil at
the first resonance frequency of the J peristaltic plate. Although the system to increase is taken,
there is a phenomenon that the sound pressure beak at this fh becomes considerably higher than
that by corn paper. And there is a problem that the high sound pressure beak at this fh makes
the design of the speaker system all the more difficult. That is, even when a speaker having high
fh 2 is viewed as a system, it is necessary to flatten the overall frequency characteristics, and
therefore the level of high sound pressure beak must be attenuated. Therefore, there is a problem
that the frequency band used is naturally limited due to the fact that the level must be lowered
from a considerably low frequency. SUMMARY OF THE INVENTION The present invention solves
the conventional drawbacks, and provides a speaker diaphragm that can significantly reduce the
sound pressure beak without a drop in fh and expand the working band in the vicinity of fh. The
purpose is Structure of the Invention The flat diaphragm of the present invention is one in which
at least three or more core members are gathered together on a fan-shaped piece having a
plurality of ribs disposed at an angle that does not converge, and the entire surface material is
adhered. As the core material, a sheet in which high density polyethylene is mixed in a base
material as a high elastic fiber total reinforcing material is used.
With this configuration, the bending stiffness in the diametrical direction changes in the
circumferential direction, so that the positions of the nodes of the entire diaphragm become
wavy. When the center is driven by a circular voice coil, a single resonance is unlikely to occur,
so the high-frequency sound pressure beak is suppressed and a flatter high-frequency
characteristic can be obtained. In addition, since a sheeter is used in which high-elasticity fiber is
mixed as a reinforcing rod into the core material of high density polyethylene in all base
materials, the rigidity of the diaphragm is largely high fh. Description of the embodiment Fig. 2
shows a cross section when the diaphragm of the present invention is assembled to a speaker. In
this case, the open end of the coupling cone 4 is adhered to the portion of the nodal circle a, and
the other end is connected to the magnetic circuit through the voice coil. In FIG. 2, 5 is a yoke
having a center pole 6, 7 is an annular magnet disposed on 6, and 8 is an upper plate disposed
on 7, so that the outer peripheral portion of the center ball 6 is an edge. It is supported on the
frame 1 o by a member 9. In the flat diaphragm 3, the opening of the coupling core / 4 is joined
to the portion of the node circle a, and the voice coil 12 wound around the voice coil bobbin 11
provided at the other end is in the air gap of the magnetic circuit. It is supported. FIG. 3 shows an
embodiment of the flat diaphragm 3 described above. In FIG. 3, 21 is a core material, and a
surface material (not shown) is attached to the surface and the back surface by an adhesive. The
core material 21 is an assembly of six fan-shaped small pieces 22 and each fan-shaped small
piece 22 is formed in a cross-sectional waveform as shown in FIG. 3 and has a plurality of
parallel ribs 23 ing. The six fan-shaped tJh pieces 22 are assembled such that the extension lines
of the ribs 23 intersect the center line of the core 21. The nodal circle shape of the primary
resonance of the flat diaphragm thus configured is formed to have a waveform centering on the
approximately 68 circle of the outer diameter of the diaphragm as shown by a broken line 24 in
FIG. This is because the bending stiffness in the diametrical direction of the diaphragm is
different, and the location of the node of the node where the core is bonded to the surface
material from the center to the periphery is the closest to the periphery. And in the opposite
position, the position of the nodal circle approaches the center. Therefore, the positions of the
nodes of the entire diaphragm can be made wavy. A circle shown by a solid line 25 in FIG. 3 is a
node circle of a diaphragm using a conventional center-symmetrical aluminum honeycomb core,
and is a nearly perfect circle. The above-mentioned speaker diaphragm is totally adhered to the
voice coil bobbin on its node circle and driven in a node manner. In this case, the voice coil
bobbin uses a circular one as in the prior art.
Since this nodal circle has a waveform, the same effect as driving a perfect circular nodal plate
with a corrugated voice coil bobbin can be obtained. This means that since the nodes are
dispersed, the sound pressure beak of the high limit frequency fh of the speaker according to the
movement of the node part can be completely made smooth. Specifically, a diaphragm having a
diameter of 200 and a height of 6 in order was prepared, and the frequency characteristic was
measured when it was used as a speaker for bass. First of all, high ff as heartwood material! In 70
parts of polyethylene fibers, carbon fibers (fiber length 6?11. Fiber diameter 10?) 11) Add 3o
parts and make it 200! A sheet of / nf was thermoformed into a shape shown in FIG. 81 to obtain
a core material. A 60 ??z thick aluminum foil was attached to both sides of this core material
using an EVA-based hot melt adhesive to prepare a whole diaphragm. The sound pressure
frequency characteristics when the obtained diaphragm was assembled to a speaker by the
method of (1) and (2) of the prior art were measured and are shown in FIG. Also, for comparison,
the characteristics according to the conventional example are shown in FIG. The frequency
characteristics were measured at 17 n / I W according to JIS standard BOX. As can be
understood from this result, in the present embodiment, the peak level at the upper limit
frequency fh is reduced by about 8 dB. Here, carbon fiber was used as a reinforcing material for
the core material, but other high modulus fibers (aramid fibers). The same effect can be obtained
by using a glass fiber having a Young's modulus of 1 О 10 12 dyn / cA or more). These
composite materials have relatively large internal loss compared to aluminum, and contribute a
little to the reduction of sound pressure beaks. In addition, the greatest advantage of using a
plastic composite material as the core material is that integral molding can be performed in a
short time, and it can be produced in about 1/2 o of man-hours in the case of conventional
aluminum, which is inexpensive and significantly improves quality stability. It is. Effects of the
Invention As described in detail above, according to the present invention, a composite
diaphragm of carbon fiber and high density polyethylene is used as a core material of a plane
diaphragm, and at least three or more fan-shaped pieces having parallel ribs are assembled. Since
the center core is formed in a circular shape and the surface material is adhered to both surfaces
to form a planar diaphragm, the nodal shape of the first resonance mode can be made to be a
waveform. Therefore, by driving the nodes of the waveform with a circular voice coil bobbin, it is
possible to reduce the level of the sound pressure beak at the high frequency limit frequency and
to flatten the frequency characteristics. In addition, since the level of the sound pressure beak is
small, it is easy to take measures against the attenuation of the sound pressure peak level on the
old speaker system and also has the advantage of facilitating the system design.
Brief description of the drawings
FIG. 1 is a partially cutaway top view showing a conventional flat diaphragm, FIG. 2 is a crosssectional view showing the structure of a speaker unit using the "sliding plate of the present
invention", and FIG. FIG. 3 is a cross-sectional view taken along the line A-A of FIG. 3. FIG. 4 is a
comparison characteristic diagram of sound pressure frequency characteristics according to an
embodiment of the present invention and a conventional example.
3 иииииииииииииииииииииииииииииииииииииииииииииииииииииииииииии Name of agent Attorney Nakao Toshio is one brother = 74 Figure
1 Figure 3 ?3
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