JPS6170899

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DESCRIPTION JPS6170899
[0001]
FIELD OF THE INVENTION The present invention relates to a flat speaker used for various
acoustic devices. The structure of the prior art and its problems In general, the flat speaker was
constructed as shown in FIG. That is, the frame 6 is coupled to the magnetic circuit 6 configured
by laminating and combining the ring-shaped magnet 3 and the plate 4 on the ring in the same
manner as the ring-shaped magnet 3 on the plate 2 having the center pole 1. Attach an edge 8
such as a free edge, couple the peripheral edge of the flat diaphragm 9 to this edge 8, couple the
drive cone 10 to the lower surface of this flat diaphragm 9, and connect the above-mentioned
magnetic circuit 5 to the center of this drive cone 10. The voice coil 12 which is embedded in the
magnetic gap 11 is coupled, and the voice coil 12 is held by the damper 13. In such a flat
speaker, the band expansion is performed to the second resonance by driving the position of the
node of the first resonance mode of the flat diaphragm 9. However, since the central portion of
the flat diaphragm 9 causes abnormal resonance such as split resonance, the sound pressure
frequency characteristic is adversely affected to cause remarkable peaks and dips in the high
frequency range. FIGS. 2a and 2c show the sound pressure frequency characteristics and the
second distortion of the conventional flat loudspeaker. The b and d show the sound pressure
frequency characteristics and the second distortion of the flat speaker using the skin material
and the drive cone of the flat diaphragm with a relatively soft material having a high internal
loss. In this configuration, the peaks in the high range are eliminated, but there are problems
such as the deterioration of the sound pressure level of the entire high range, the deterioration of
the sound quality due to the significant increase of the second harmonic distortion, and the like.
There is also a structure in which the central portion of the flat diaphragm is cut off and filled
with a foreign material with a large internal loss, but with this configuration, the high frequency
reproduction frequency is reduced due to the deterioration of the appearance quality and the
reduction of the surface rigidity of the central portion of the flat diaphragm. There was a problem
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such as a drop in bandwidth. SUMMARY OF THE INVENTION The present invention eliminates
the above-mentioned conventional drawbacks, prevents abnormal resonance of the central
portion of the flat diaphragm, and makes the sound pressure frequency characteristic flat with an
extremely simple structure, and is effective. It is an object of the present invention to provide a
flat loudspeaker that SUMMARY OF THE INVENTION In order to achieve the above object, the
present invention provides a circular or non-circular cutting portion at the central portion
through an edge at the peripheral portion of a frame coupled to a magnetic circuit and mounts a
flexible material at the cutting portion. A flat diaphragm with skins attached to both sides of the
core material attached is attached, and a voice coil that fits into the magnetic gap of the magnetic
circuit is coupled to this flat diaphragm, and by this configuration, the strength of the flat
diaphragm is obtained. And the sound pressure frequency characteristics can be flattened with a
simple configuration without deteriorating the appearance quality.
Description of Embodiments Hereinafter, embodiments of the present invention will be described
with reference to the drawings. Since the configuration of the flat speaker is substantially the
same as that shown in FIG. 1, only the flat diaphragm as a feature of the present invention will be
described here. FIG. 3 shows the structure of the flat diaphragm of the flat speaker of the present
invention. The central portion 9b of the honeycomb core material 9a is made of a core material
9b "having a highly flexible material 9b 'mounted on the outer periphery thereof. The flat
diaphragm 9 was formed by sticking aluminum skin material gc, 9d on the upper and lower sides
of this core material 92L which consists of this batting and 7 composition. The diaphragm was
formed in the same manner for the shape shown in FIG. In FIG. 4, a is an example in which the
central portion 9b of the circular core member 9a is cut into a circular shape, and hereinafter,
the central portion 9b of the circular core member 91L is squared and C is the circular core
member 9a. The central portion 9b is elliptical, d is the central portion 9b of the square core
member 9a is square, e is the cutting of the central portion 9b at d shifted by 45 degrees, and f is
the center of the square core member 9a The portion 9b is circular, g is a center portion 9b of a
square core member 9a is elliptical, h is a peripheral portion is a straight line and a circular arc
and the center portion 9b of the core member 9a is square, i is The central portion 9b is cut at
46 degrees r in h, j is a central portion 9b of the core member 9a whose peripheral portion is a
continuous shape of a straight line and a circular arc, and k is a core member 9a of the same
shape as j. The central portion 9b is elliptical, and p is the central portion 9b of the core member
9a having the same shape as n, and has a shape similar to that of the central portion One in
which the. The diameter or size of the cut of the central portion 9b is remarkably effective when
the diameter or size is 10% to 40% with respect to the outer diameter or outer size of the flat
diaphragm 9. The highly flexible material 9b "can be remarkably effective by using a foam or a
rubber component. In addition, the thickness of the highly flexible material 9 b appears
sufficiently at about 0.1 mm to 3 mm in the radial direction. This means that an appropriate
compliance is given near the center of the sound axis by the center 9b of the core material 9a of
the flat diaphragm 9, and this compliance reverse resonance that cancels the abnormal
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resonance of the center in the high region. I was waking up. Furthermore, the weight of only the
central portion of the core member 9a independent of the weight of the flat diaphragm 9 is
present at the central portion, and a loss is given to the amplitude of the flat diaphragm 9 of the
flat speaker. The divided vibration of the part is suppressed. A similar experiment was performed
with the cuts to core 9 made discontinuous. FIG. 5 shows this embodiment, and FIGS. 5a, 5b and
5c respectively show the center portion 9b of the circular core member 9 &, 4 points on the arc,
2 points on the arc, and so on. 6 d, e, f 'are made elliptical as the central part 9b of the square
core member 9 & 2 at four points on an arc. Discontinuous, leaving 4 non-cuts in a square, Fig.
6g.
h and i are not left leaving four non-cut parts of 4 points on the arc and 4 points on the arc,
leaving the center part 9b of the core material 9a whose peripheral part is a continuous line and
arc continuous shape. It is continuous and the remaining part is penetrated. The core material 9b
at the central portion is made of the core material 9b ′ ′ having a highly flexible material 9b
′ mounted on the outer peripheral portion. In this case, the effect was remarkable when the
discontinuous portion was 30% or less. Furthermore, the same experiment was performed also
about what made the cutting part a part of thickness direction of the core material 9a. FIG. 6
shows this embodiment, and FIG. 6a is a front view to the core member 9, and FIG. 6 is a
sectional view of the core member 91L. FIG. 6 shows an example in which a cut is made from one
side in the thickness direction, and FIG. 6C shows a cut made from both sides in the thickness
direction. The sound pressure frequency characteristics and second harmonic distortion of a flat
speaker using a horizontal diaphragm are shown in FIGS. 7 and 8. FIG. 7 shows a circular flat
speaker and FIG. 8 shows a square flat speaker. 6g and rh in each figure show sound pressure
frequency characteristics second harmonic distortion. Compared to the conventional flat
loudspeaker in FIG. 2, the peak of the high range is significantly down, the sound pressure level
of the entire high range is not down, and the distortion is also small. In addition, as a flat speaker,
what showed the thing which couple ¦ bonded the voice coil 12 with the plane diaphragm 9
through the drive cone 10 in FIG. 1 was shown, but the present invention is also considered as a
structure which couple ¦ bonds the voice coil 12 directly to the plane diaphragm 9. The same
effect is obtained. Effects of the Invention As described above, since the flat speaker of the
present invention is configured, the high frequency band peak of the flat speaker can be easily
removed without deteriorating the reproduction band of the speaker with a simple configuration
and without increasing the distortion. It is possible to flatten the sound pressure frequency
characteristics without degrading the appearance quality. It has great industrial value.
[0002]
Brief description of the drawings
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[0003]
FIG. 1 is a cross-sectional view showing a general flat loudspeaker, FIG. 2 is a characteristic
diagram of sound pressure frequency characteristics and second harmonic distortion of the
conventional flat loudspeaker, and FIG. 3 is one embodiment of the flat loudspeaker of the
present invention An exploded perspective view of the flat diaphragm in the example, FIG.
Fig. 5 a% i is a top view showing an embodiment of the core material of the flat diaphragm used
in the flat speaker of the present invention, and Fig. 6 a-C is another embodiment of the core
material of the flat diaphragm. The top view and the cross-sectional view shown in FIG. 7, FIG. 7
and FIG. 8 show the plane 1 of the present invention,..., Center pole, 2. .... Plates, 5 ..... Magnetic
circuits. 6 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · flat
diaphragm, 9a · · · · · core material ·········· Core, 9b ′ ········· Core material forming the central part,
9b ′ ′ ···································· 9b ... Skin material, 10 ..... Drive cone, 11 '' '... Magnetic gap, 12 ...
Voice coil, 13 ... Damper. Name of Agent Attorney Nakao Toshio and 1 other person, $ 1 Figure 3
Figure 4 (α) (b) (c) d <Dcr-District 串 ¥ ° C
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