JPS58156297

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DESCRIPTION JPS58156297
[0001]
The present invention relates to a flat diaphragm for a speaker, and provides a speaker
diaphragm having high rigidity and lightness t. In general, the speaker diaphragm is often formed
by forming pulp into a pulp, and the diaphragm shape is a cone shape. Because of this, there is a
phase difference between the center of the cone and the outer periphery due to the displacement
of the sound source, and the air in the cone resonates, making it difficult to obtain a flat sound
pressure frequency characteristic. On the other hand, the flat plate of the diaphragm is used to
align the position of the sound source, and the flat plate speaker is advantageous for flattening
the frequency characteristic without the front chamber effect which is seen in a cone shape. In
the case of the flat diaphragm, when using conventional paper, the stiffness against bending is
small, and the division vibration is likely to occur from a low frequency, and there is a defect that
flat characteristics can not be obtained over a wide band. On the other hand, there is also an
example in which a polymer foam such as expanded polystyrene is used as a flat diaphragm, but
the rigidity is too small to be suitable as a diaphragm. Therefore, it is a flat plate diaphragm that
utilizes a sandwich structure that is light in weight and high in bending rigidity. In order to
realize this nc), in recent years, a flat diaphragm using a No1 nicham sand innoc structure has
been adopted. Here, when using a so-called nodal drive method in which the voice coil is bonded
and driven to the nodal position at the primary resonance frequency of the planar diaphragm and
the first resonance is canceled, 1h (high frequency limit frequency) Is there an advantage that
can significantly increase the N honeycomb sandwich structure? The diaphragm used is
expensive because of its complicated structure. In order to solve this problem, a frame member
formed by bending a rectangular plate member in a zigzag shape is expanded in an annular
shape so that one side is the inner peripheral surface and the other side is the outer peripheral
surface A sand-inch structure has been proposed in which the surface material is adhered to both
surfaces of the annular frame member. However, in the case of the sand-inch structure which is
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rotationally expanded in this annular shape, the density of the skeletal member becomes sparser
from the inner circumferential surface toward the outer circumferential surface, so that the
bending rigidity of the diaphragm is the outer circumferential surface as shown by There is a
problem that it becomes smaller and the rigidity as the diaphragm becomes smaller and fh
decreases. The present invention solves such a conventional defect, and performs impregnation
treatment of a thermosetting resin on an outer peripheral portion of an annular frame member
obtained by bending and rotating a rectangular plate-like body in a zigzag shape. It has been
strengthened by According to this configuration, the surface material is joined to both surfaces of
the annular frame member to increase the bending rigidity of the diaphragm even at the outer
peripheral portion, and the bending rigidity as a whole can be increased. It has the advantage
that di area can be expanded.
Hereinafter, the speaker diaphragm of the present invention will be described with reference to
the drawings of the embodiments. EXAMPLE 1 A kraft paper having a thickness of 80 .mu.m is
used as a frame member to make a rectangular plate as shown in FIG. 2, and this plate is bent in
a zigzag shape to form a frame block 1; It is rotationally developed so that the side portion 1A is
an inner peripheral surface and the other side portion 1B is an outer peripheral surface, and both
end surfaces are adhered to form an annular frame member 2 as shown in FIG. Then, at a length
of 3 CWL from the outer peripheral surface (B side) of the cyclic skeleton member 2, boron
fluoride, 3 parts of monoethylamine, and diamino diphenyl are added to 100 parts of Epicoat
828 (epoxy resin of Shell Co.) The impregnating agent to which 27 parts of sulfone was added
was impregnated to a content of 30 parts, dried at 10 ° C. for 16 minutes and then heat cured
at 160 ° C. for 40 minutes. Then, the surface material 3 was joined to the both surfaces of the
cyclic ¦ annular frame ¦ skeleton member 2 which carried out the impregnation process to the
said outer peripheral part. At this time, a 40 μm thick aluminum foil is used as the surface
material 3. In the diaphragm of this embodiment, since the outer peripheral portion of the
annular frame member 2 is impregnated with a thermosetting resin, the bending rigidity at the
outer peripheral portion is large 9, and the curve B in FIG. 3 as a whole is Bending stiffness
distribution as shown can be obtained. Therefore, when a flat diaphragm with an outer diameter
of 190 mm is used, the high frequency limit frequency fh before impregnation is 3.1 kIh, while
the high frequency limit frequency 1h is expanded to 3.91 by impregnation, and a wide band I
got a speaker. In addition, since the strength of the outer peripheral portion of the diaphragm is
increased, the reliability of the bonding portion with the edge is increased, and the workability is
improved. EXAMPLE 2 The content of PC-1 (Phenolic resin of Sumisho Bakelite Co., Ltd.) is 30%
at a length of 3 Cfn from the outer peripheral surface (B 1 jltl) of the cyclic skeleton obtained in
Example 1. It was impregnated as such, dried at 1 oOC for 16 minutes and then heat cured at
150 C for 15 minutes. Thereafter, an aluminum foil having a thickness of 40 μm was bonded to
both surfaces as a surface plate to form a flat diaphragm. Example 3 Methyl methacrylate resin
(Methyl ethyl ketone: mixed solvent of toluene 1: 1 mixed solvent to a concentration of 16% at a
length of 3 crn from the outer surface (B side) of the cyclic skeleton member n in Example 1
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Treatment at a content of 30% and dried at 1 oOC for 10 minutes and then heated at 160 C for
10 minutes. Thereafter, an aluminum foil having a thickness of 40 μm was bonded to both
surfaces as a surface material to form a flat diaphragm. As described above, according to the
present invention, according to the present invention, a rectangular plate-like body is bent in a
zigzag shape, and one side portion is developed annularly so that the inner peripheral surface
and the other u11 portion become the outer peripheral surface, Since the surface material is
joined to both surfaces of the annular frame member impregnated with the thermosetting resin
in the outer peripheral portion, the bending rigidity in the outer peripheral portion is increased,
and the bending rigidity as a whole can be increased. Therefore, it has an advantage that the
reproduction frequency band can be expanded by increasing fh.
[0002]
Brief description of the drawings
[0003]
1 is a partially cutaway plan view showing one embodiment of the speaker diaphragm of the
present invention, FIG. 2 is a perspective view of a framework member used for the diaphragm,
and FIG. 3 is a conventional diaphragm of the same diaphragm. It is a distribution characteristic
view in the radial direction of the bending stiffness of
1 ...... backbone block, 2 ..... annular frame member, 3 ...... surface material. Name of agent
Attorney Nakao Toshio Other 1 person Figure 1
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