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JPH07162992

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DESCRIPTION JPH07162992
[0001]
FIELD OF THE INVENTION The present invention relates to a loudspeaker diaphragm.
[0002]
2. Description of the Related Art In general, the edge portion of a loudspeaker diaphragm is
required to have a flexibility that does not impede the amplitude movement of the loudspeaker
diaphragm and a proper vibration damping property. Therefore, the diaphragm body portion and
the edge portion are separately formed as separate members, and the diaphragm body portion
and the joint portion provided on the edge portion are bonded and joined to constitute the
speaker diaphragm. The speaker diaphragm configured in this way is generally called a free edge
diaphragm and is used for many speakers.
[0003]
Further, as the edge portion of the free edge diaphragm, one made of a urethane foam molded
into a roll having a substantially semicircular cross-sectional shape has been widely used.
[0004]
However, since the speaker diaphragm configured as described above has a single edge portion
and substantially uniform physical properties, a speaker using this speaker diaphragm is a
specific type. In the frequency, natural resonance occurs over the entire circumference of the
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edge, and due to the natural resonance of the edge, a significant peak or dip appears at the above
specific frequency in the frequency characteristic of the speaker, making it difficult to obtain a
flat sound pressure frequency characteristic. There was a problem that the sound quality was
poor on hearing.
[0005]
An object of the present invention is to provide a speaker diaphragm capable of obtaining a flat
sound pressure frequency characteristic by suppressing natural resonance over the entire
circumference of an edge portion at a specific frequency.
[0006]
According to the present invention, there is provided a speaker vibration in which a diaphragm
body portion and an edge portion are separately formed, and the diaphragm body portion and a
joint portion provided on the edge portion are bonded and joined. In the plate, the width of the
joint portion provided at the edge portion is formed to be uneven along the outer peripheral end
of the diaphragm body portion.
[0007]
Therefore, the rigidity of the outer peripheral end of the diaphragm body is different at each
portion, and the specific frequency resulting from the natural resonance of the edge portion can
be made different at each portion.
[0008]
Embodiments of the present invention will be described in detail with reference to the drawings.
[0009]
FIG. 1 is a longitudinal sectional view showing the structure of a general speaker, FIG. 2 is a front
view (a) and a side sectional view (b) showing an edge portion of a loudspeaker diaphragm
according to an embodiment of the present invention, and FIG. It is a frequency characteristic
view of the speaker using the speaker diaphragm comprised by the same edge part.
[0010]
As shown in FIG. 1, the loudspeaker according to the present embodiment comprises a magnetic
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circuit unit 1 and a vibrating unit 2. Among them, the magnetic circuit unit 1 is disposed at the
center of the circular flat plate 3a and the flat plate 3a. A support plate 3 comprising a cylindrical
center pole 3b provided, an annular magnet 4 concentrically fixed to the center pole 3b on the
side of the center pole 3b of the flat plate portion 3a, and a magnet 4 on the upper end face of
the magnet 4 And an annular top plate 6 provided concentrically.
The air gap formed between the magnet 4 and the upper plate 6 and the center pole 3b is used
as a magnetic gap to guide the magnetic flux from the magnet 4 to a voice coil 5 described later.
[0011]
The vibrating portion 2 has a conical diaphragm body 9, and a central hole portion
corresponding to the cone top of the diaphragm body 9 is a voice of the voice coil 5 as a
vibration source. The coil bobbin 5a is fixed by adhesion or the like.
A flexible annular damper 11 is fixed to the voice coil 5 and the diaphragm body 9 by bonding or
the like, and the outer peripheral portion of the damper 11 has a conical shape fixed to the upper
end surface of the upper plate 6. Is elastically supported by bonding or the like.
On the other hand, the edge portion 8 is bonded to the outer periphery of the cone bottom
portion of the diaphragm body 9 with a bonding portion 8a, and this edge portion 8 is fixed to
the edge support portion 7a of the frame 7 by bonding or the like.
That is, the frame 7 supports the diaphragm body 9 by the edge 8 and the damper 11.
Further, on the voice coil 8 side of the diaphragm body 9, a dust cap 10 for dust protection is
provided.
[0012]
A free edge diaphragm is constituted by the diaphragm body 9 and the edge portion 8 bonded to
the outer periphery of the cone bottom of the diaphragm body 9 with a joint 8a.
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[0013]
Further, as shown in FIG. 2, the above-mentioned edge portion 8 is a joint portion 8a used for
bonding with the diaphragm body 9, an edge roll 8b for appropriately damping the vibration of
the diaphragm body 9, and a frame 7 and the outer peripheral edge 8c used for bonding with the
edge support 7a are integrally formed of urethane foam, and the edge roll 8b and the outer
peripheral edge 8c are concentrically formed in a circular shape. The inner circumference of the
joint portion 8a is formed in an elliptical shape.
[0014]
Therefore, the width of the bonding portion 8 a of the edge portion 8 becomes uneven along the
outer peripheral end of the diaphragm body 9, and the rigidity of the outer peripheral end of the
diaphragm body 9 is different in each portion. It is possible to make the specific frequency
attributable to the different at each portion, and to suppress the natural resonance occurring
around the entire circumference of the edge portion 8 at the specific frequency.
[0015]
Therefore, the frequency characteristic of a 10 cm diameter speaker using a free edge diaphragm
constituted by using the above-mentioned edge portion 8 is shown by a solid line A in FIG.
The broken line B in FIG. 3 corresponds to the edge portion 8 in which the inner periphery of the
joint portion 8a of the edge portion 8 is formed in a circle using the same material as that of this
embodiment and the other shape is the same as that of this embodiment. The frequency
characteristics of the comparative example are shown.
[0016]
Here, it can be seen that in the frequency characteristic of the comparative example shown by
the broken line B in FIG. 3, the peak due to the resonance of the edge portion 8 and the dip due
to the reverse resonance occur at around 2 kHz.
On the other hand, in the frequency characteristics of the present embodiment shown by the
solid line A, such peaks and dips are not recognized.
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[0017]
That is, in the free edge diaphragm formed by using the edge portion 8 in which the inner
periphery of the joint portion 8 a is formed in an elliptical shape, the rigidity of the outer
peripheral end of the diaphragm body 9 is made different at each portion. Since the specific
frequency resulting from the natural resonance can be made different at each part, flat sound
pressure frequency characteristics can be obtained.
Therefore, the resonance between the diaphragm body 9 and the edge portion 8 is eliminated,
and the occurrence of a significant peak or dip in the frequency characteristic of the speaker can
be suppressed.
[0018]
Therefore, the speaker using the speaker diaphragm formed by using the edge portion 8 in which
the inner periphery of the joint portion 8a is formed in an elliptical shape as described above has
excellent acoustic characteristics with excellent frequency characteristics.
[0019]
Although urethane foam is used as a material for molding the edge portion 8 in the present
embodiment, the present invention is not limited to this. For example, a woven or non-woven
fabric is impregnated with a thermosetting resin such as a phenol resin and dried. After that, heat
pressure molding may be performed.
Further, although the shape of the diaphragm body 9 is a cone shape, the present invention is
not limited to this. For example, the diaphragm body 9 having a dome shape, a flat plate shape or
the like may be used.
[0020]
As described above, according to the present invention, the width of the joint portion provided at
the edge portion is formed so as to be uneven along the outer peripheral end of the diaphragm
body, and the unevenly formed joint is formed. The rigidity of the outer peripheral end of the
diaphragm body is different in each portion by bonding the part and the outer peripheral edge of
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the diaphragm body to form a speaker diaphragm, and the specific frequency resulting from the
natural resonance of the edge portion Can be made different at each part, so it is possible to
suppress the natural resonance that occurs over the entire circumference of the edge part at a
specific frequency, and the speaker using this speaker diaphragm suppresses the occurrence of
significant peaks or dips in the frequency characteristics It is possible to have good acoustic
characteristics with good frequency characteristics.
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