JPS556982

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DESCRIPTION JPS556982
Description 1, title of the invention
Diaphragm
3. Detailed Description of the Invention The present invention is intended to obtain a wide band,
low strain diaphragm by using a lightweight, highly rigid micro hollow sphere filling material.
FIG. 1 shows a general cone-shaped speaker, 1 is a diaphragm, 2 is an edge, 3 is a plate, 4 is a
magnet, 6 is a voice coil, 6 is a center ball, 7 is a damper, 8 is a frame. , 9 is a bobbin, 1 o is a
dust cap. Conventionally, the diaphragm 1 of this type of speaker has a problem that when it is
made of paper that is often used, when it is made of paper, its thickness is relatively small and
bending rigidity can not be made large. In order to address such problems, the present invention
provides a diaphragm in which bending stiffness is increased by filling micro hollow spheres. FIG.
2 shows a diaphragm according to an embodiment of the present invention, in which a base
material 11 is filled with hollow hollow spheres 12 whose inside is hollow and whose outside is
covered by an outer shell. In addition, as the base material 11, a thermosetting epoxy resin, a
heat-plasticity polyethylene terephthalate, a polypropylene, etc. can be used. Further, as the
hollow hollow spheres 12, those having as high strength as possible are desirable, and a silica
balloon is suitable in that sense. And this diaphragm can be created by EndPage: 1 in vacuum
forming. In the diaphragm configured in this way, since the specific gravity of the micro hollow
spheres 12 is extremely small such as about O, OS to about 0.6, for example, the specific gravity
of the base material 11 is 1.0. The specific gravity of the micro hollow spheres 12 is 0.1. When
the filling amount is 5 o% in volume ratio, the thickness after filling the micro hollow spheres is
1.8 times under the condition of constant total weight as compared with the case of using only
the base material. In general, the flexural rigidity Y is represented by Y-E-t3 / 12 (1) where E is a
Young's modulus of the material and t is a thickness. Therefore, as described above, when the
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thickness jt- becomes 1.8 times, the bending rigidity at that time is about 1.8-5.8 times as large
as the bending rigidity of the base material 11 alone. Become. Therefore, it is possible to reduce
the weight of the diaphragm and to significantly increase the bending rigidity thereof to obtain a
diaphragm with a wide band and low distortion. As shown in FIG. 3, after filling the hollow
spheres 12 in the base material 11, if both surfaces of the hollow spheres 12 are filled with the
surface material 13, the surface material 13 is extremely excellent. It will be The diaphragm
shown in FIG. 3 is extremely excellent when it is applied to a so-called curved cone 14Vc in
which the diaphragm is bent in the generatrix direction as shown in FIG.
The reason is the following two points. (1) The two frequencies at which the curved cone
performs piston movement are determined by bending vibration. This is confirmed by analysis
using a general purpose structural analysis program (NASTRAN). The bending vibration
described in (2) <1) depends on the bending rigidity of the diaphragm, and the bending rigidity is
compared with the elongation rigidity as described below, and the face material ratio is about 0.4
to 0.5. It becomes relatively large. That is, FIG. 5 forms a diaphragm using the core material of
the elastic modulus EC and the surface material of the elastic modulus Ef, and the elastic modulus
Eb of the diaphragm and the elongation modulus at this time are the elongation modulus E, Et =
Jx + Eo (1-x) ,,,,, (2). On the other hand, we work on the second moment of area of the core and
the surface material respectively. And I (, assuming that the thickness is t0 tf tf, respectively ■.
＝ｔｏ７１２、．０００．（３）１１＝ｔ（／１２・・・・・・（４）となる。 Therefore, the
flexural modulus Eb is expressed as follows: 'Eb = Efh- (1-x) 31 + EC (1-x) 5,. 1. It becomes (s). E
and Eb in FIG. 5 indicate the equations (2) and (6), respectively, and E () Ec, for example, when
the face material ax is 0.5, the bending elastic modulus Eb is an elongation It can be seen that the
modulus of elasticity E is about 75% greater. From this, it can be understood that the diaphragm
shown in FIG. 3 has excellent characteristics, and if this is used for a curved cone, a diaphragm
with high bending rigidity (and hence large bending vibration) can be obtained. It will be
appreciated that the upper limit frequency can be increased. The present invention can be
applied to a diaphragm of a cone type speaker, a diaphragm for a general electroacoustic
transducer, and a similar effect can be obtained. As described above, according to the present
invention, the hollow hollow spheres are filled in the base material to form the diaphragm, and
the diaphragm is made light in weight and has high rigidity. Therefore, a diaphragm with a wide
band and low distortion is realized. be able to.
4. Brief description of the drawings FIG. 1 is a cross-sectional view of a general loudspeaker, FIG.
Diaphragm
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3 is a cross-sectional view of a diaphragm according to one embodiment of the present invention
and another embodiment, FIG. 4 is a perspective view showing a curved cone using the
diaphragm of FIG. 3, and FIG. 5 is a detail of the present invention It is a characteristic view for
explaining. 11, ..., Base material, 12, ..., Micro hollow sphere, 13 · · · · · · · · · · · · · Name of Attorney
Nakano Toshio Nakao and 1 other person EndPage: 2 Fig. 1 Fig. 2 f Fig. 3 /,? 4th rj!
ＪＥｎｄＰａｇｅ： ３
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