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JPH11239393

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DESCRIPTION JPH11239393
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker which is a kind of audio equipment.
[0002]
2. Description of the Related Art Conventionally, as a speaker for bass band reconstruction,
limited by intentionally providing a secondary resonance at a higher frequency in addition to the
resonance of the lowest resonance frequency f0 in order to increase the sound pressure to be
reconstructed. There is a method to improve the sound pressure of the selected frequency band.
[0003]
That is, as shown in FIG. 6A, the speaker S is attached to the central partition baffle 21 formed at
the center of the speaker enclosure 20 having two chambers a and b, and the resonance port C is
attached to one of the outer baffles 22. There is a speaker system of the so-called BANDPASSBOX type, provided so as to obtain desired characteristics by total four-order resonance as
shown in FIG. 6 (b).
[0004]
Moreover, as shown to Fig.7 (a), the resonance port C is each provided in both the outer baffles
22, and as shown to FIG. 7 (b), there exist some which implement | achieve a characteristic by a
total of six-order resonance.
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[0005]
Furthermore, as shown in FIG. 8, an additional suspension 23 is provided on the speaker itself,
which is not of the type as shown in FIGS. 6 (a) and 7 (b) but is desired by a speaker enclosure
with a simple configuration of one room. Some have realized the characteristics of
[0006]
The conventional speaker systems shown in FIGS. 6 to 8 require the BAND-PASS BOX and the
additional suspension 23 and have a complicated structure, which makes the manufacture
complicated and There was a problem that the cost was high.
[0007]
The present invention has been proposed in view of the above, and an object thereof is to provide
a speaker capable of achieving desired characteristics by simplifying the configuration.
[0008]
SUMMARY OF THE INVENTION In the present invention, in a speaker comprising a diaphragm
having an inner peripheral end connected to a voice coil and an outer peripheral end connected
to a frame via an edge, the diaphragm extends from the neck to the periphery Form a part where
the change of tangent angle α at any given point A gradually becomes zero, or a part where the
change of tangent angle α changes gradually and forms a top, and provides resonance as a
mechanical filter The construction is made to achieve the above object.
In this case, the resonance frequency is set to be two to five times the lowest resonance
frequency f0.
[0009]
DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view showing the
basic concept of the present invention.
In the figure, point A is an arbitrary point on the outer surface of the diaphragm from the neck to
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the periphery of the speaker diaphragm 1, and α is a tangent angle at the arbitrary position A.
[0010]
Therefore, in the body portion of speaker diaphragm 1, when attention is paid to tangent angle
α at an arbitrary position A located from neck portion 1a to peripheral portion 1b, if tangent
angle α is sufficiently large, point A in the drive direction The shape rigidity is considered to be
secured, and the diaphragm can be considered as a rigid body in the low range.
[0011]
However, if the trunk shape is formed so as to reduce the tangent angle α at point A, that is, to
be zero degrees, the shape rigidity of point A decreases and it functions as a compliance. It is
necessary to provide a new resonator.
[0012]
The resonance frequency can be arbitrarily set by considering the position of the point A and the
depth of the entire trunk from the relationship between the compliance and the mass.
In the present invention, a portion is provided such that the change of the tangent angle α from
the inner periphery to the outer periphery gradually becomes zero, and the change of the
inclination to that point is relaxed to create resonance as a mechanical filter. It is characterized in
that
[0013]
[Embodiment 1] FIG. 2 shows an embodiment of the present invention in which the abovementioned portion is formed and the change in inclination of the diaphragm body shape is made
gentle and the whole is laid down, as a result, it is also made thin. Indicates the sound pressure /
frequency characteristic.
[0014]
First, in FIG. 2, 1 is a diaphragm attached to the outer peripheral fixing portion 4a of the frame 4
with the inner peripheral end connected to the upper end outer peripheral portion of the voice
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coil 2 and the outer peripheral end via the edge 3; Reference numeral 5 is a dustproof cap
provided at the center of the diaphragm 1, 6 is a damper for vibratably supporting the voice coil
2, the inner peripheral end is connected to the voice coil 2, and the outer peripheral end is a
frame 4 It is connected to the attaching part 4b of.
A magnetic circuit 7 comprises a yoke 8 having a through hole 8a for exhaust, a ring-shaped
magnet 9, and a plate 10 provided thereon, and the plate 10 and the center pole outer periphery
8b of the yoke 8 The voice coil 2 is disposed so as to be able to vibrate in the magnetic gap
formed between the two via the damper 6.
The reference numeral 11 denotes a tinsel wire to which one end of the voice coil 2 is connected
at the back side of the diaphragm 1, and the other end is connected to a terminal plate 12
provided at an appropriate position of the frame 4.
[0015]
Thus, the feature of the present invention lies in the shape of the diaphragm 1 as described
above.
That is, according to the present invention, the diaphragm 1 is provided with a point A at which
the tangent angle α described in FIG. 1 becomes zero from the neck to the outer periphery, and
the change in inclination of the diaphragm 1 is gentle.
The point A is formed in the circumferential direction of the outer peripheral portion of the
diaphragm 1.
[0016]
With this configuration, the diaphragm 1 is a rigid body in a sufficiently low frequency band, but
can not follow the vibration velocity as the frequency becomes higher, causing secondary
resonance and improving the sound pressure in the band of that portion be able to.
[0017]
That is, in FIG. 3, a is a limited band used as low-frequency band reconstruction, and when the
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driving force of the magnetic circuit 7 is small due to weight reduction etc., the characteristic
tends to be downward sloping as shown by the dotted line in the band a. become.
[0018]
Therefore, as shown in the lower part of the band a, the diaphragm a itself functions as a
mechanical filter to form a secondary resonance in a frequency portion higher than the lowest
resonance frequency f0 in the band a. As shown by a solid line, sound pressure can be improved.
The hatched portion in the figure indicates the portion where the sound pressure has risen.
[0019]
FIG. 4 is a diagram of a vibration mode by computer simulation corresponding to the above
embodiment, showing that the change is large from the vicinity of the point A 'in the peripheral
portion, and the change in the vicinity of the point A on the outer periphery is large.
Moreover, FIG. 5 shows the graph of the frequency characteristic same as the above.
This is obtained by calculating and plotting the relationship between the acceleration (in
proportion to the sound pressure) at a point on the diaphragm of the actually manufactured
speaker and the input frequency by FEM analysis.
[0020]
That is, in FIG. 5, the first peak on the left side corresponds to the lowest resonance frequency f0,
and the second peak on the right side corresponds to the resonance as the mechanical filter of
the present invention.
The frequency of the first peak is about 64 Hz, and the second peak is about 240 Hz at 239 Hz,
which substantially matches the measurement. The resonance frequency of the second peak is
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preferably set to be in the range of 2 to 5 times the lowest resonance frequency 50.
[0021]
As mentioned above, since the shape, the material, etc. which can obtain the desired
characteristic of the present invention can be set beforehand by computer simulation, the
optimum design of the actual product is also easy.
[0022]
Therefore, the present invention is particularly effective for a speaker having a small driving
force by reducing the size and weight of the magnetic circuit 7 for the purpose of reducing the
weight and the like in recent years.
That is, usually, such a speaker tends to have a characteristic that it goes downward to the right
after the lowest resonance frequency f0 because Q0 indicating damping in the low band is high.
On the other hand, by adopting the present invention, it is possible to realize the flattening of the
characteristics by the improvement of the sound pressure in the limited band a.
[0023]
As described above, according to the present invention, the diaphragm itself is caused to produce
resonance as a mechanical filter, and the sound pressure can be improved in a band limited by
this resonance. There is an advantage that a speaker enclosure of a special structure called
BAND-PASS BOX and an additional suspension are not required, the configuration is simplified,
the manufacture is easy, and the cost can be reduced.
[0024]
In the above embodiment shown in FIG. 2, an example of the diaphragm shape in which the
change of the tangent angle α at an arbitrary point A of the diaphragm 1 becomes zero
gradually is shown. In this case, the shape becomes a so-called broken line shape at point A, that
is, the change of the tangent angle α changes gently, and the point A becomes a portion forming
the top, and there is resonance as a mechanical filter Even if it is a point, almost the same effect
can be obtained.
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