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JP2017085235

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DESCRIPTION JP2017085235
Abstract: A flat sound pressure characteristic is obtained by suppressing split resonance in the
middle to low range even if the diaphragm is made thin. A diaphragm (11) and a voice coil (12)
mounted at a position (70 ± 5)% from the center with respect to the outer diameter of the
diaphragm (11). [Selected figure] Figure 1
スピーカ
[0001]
The present invention relates to, for example, a speaker that reproduces an audio signal.
[0002]
In recent years, thinning of liquid crystal televisions and the like has progressed, and thinning of
speakers mounted thereon is also required.
There are various methods for thinning the speaker, such as one using a cone-shaped diaphragm
and one using a dome-shaped diaphragm (see, for example, Patent Documents 1 and 2). For
example, in Patent Document 1, part of the center of the dome-shaped diaphragm is recessed so
that split resonance does not occur when the diaphragm is thinned.
[0003]
12-05-2019
1
JP, 2004-260736, A JP, 2007-005906, A
[0004]
On the other hand, in the case of a cone-shaped diaphragm, in order to strengthen the structure,
it has a depth in the vibration direction so that flexural vibration is generated in the high region.
However, this depth increases the depth of the speaker, which is a drawback for thinning.
Therefore, in order to make the depth of the speaker thin, it is necessary to make the coneshaped diaphragm thin (shallow). On the other hand, in the cone-shaped diaphragm, if the depth
is small or the material does not have rigidity, split resonance which is mechanical resonance is
likely to occur. Also, when driven with a small diameter VC diameter (drive diameter), flexural
vibration is likely to occur. That is, when the cone-shaped diaphragm is made thin, divided
vibration is likely to occur, and the sound pressure characteristic fluctuation occurs from the low
frequency, so there is a problem that the sound quality is adversely affected.
[0005]
In addition, the depth of the cone-shaped diaphragm forms a recessed space in front of the
diaphragm. This hollow space causes a fluctuation in the sound pressure characteristic of the
high region in the speaker, and has an acoustic defect that impairs the flatness (hollow effect).
[0006]
The present invention has been made to solve the above-described problems, and provides a
speaker capable of suppressing flat resonance characteristics and achieving flat sound pressure
characteristics even if the diaphragm is made thin. The purpose is that.
[0007]
A loudspeaker according to the present invention comprises a diaphragm and a voice coil
attached at a position (70 ± 5)% from the center with respect to the outer diameter of the
diaphragm.
[0008]
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2
According to the present invention, as configured as described above, even if the diaphragm is
made thin, it is possible to suppress split resonance in the middle to low range and obtain flat
sound pressure characteristics.
[0009]
It is a sectional view showing an example of composition of a speaker concerning Embodiment 1
of this invention.
It is sectional drawing which shows another structural example of the speaker based on
Embodiment 1 of this invention.
It is sectional drawing which shows another structural example of the speaker based on
Embodiment 1 of this invention.
[0010]
Hereinafter, embodiments of the present invention will be described in detail with reference to
the drawings.
Embodiment 1 FIG. 1 is a cross-sectional view showing a configuration example of a loudspeaker
according to Embodiment 1 of the present invention. The speaker is, for example, a thin speaker
that reproduces an audio signal. The speaker includes a vibration system 1, a magnetic circuit 2
for applying a magnetic force to the vibration system 1, and a frame 3 which holds the vibration
system 1 and is coupled to the magnetic circuit 2. The magnetic circuit 2 comprises a magnet 21,
a plate 22 and a pole piece 23, and a gap is provided between the plate 22 and the pole piece 23.
[0011]
The vibration system 1 includes a diaphragm 11, a voice coil (bobbin) 12, an edge 13, a damper
14 and the like as shown in FIG.
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3
[0012]
The diaphragm 11 is a diaphragm having a circular shape in a front view, and emits a sound
wave upon receiving a vibration from the voice coil 12.
In the example of FIG. 1, the case where the diaphragm 11 is comprised using the dome shaped
diaphragm 111 and the cone shaped diaphragm 112 is shown.
[0013]
The dome-shaped diaphragm 111 is a diaphragm having a convex cross-sectional shape
protruding toward the center. The cone-shaped diaphragm 112 is a diaphragm provided
concentrically around the periphery of the dome-shaped diaphragm 111. In FIG. 1, the coneshaped diaphragm 112 is connected to the dome-shaped diaphragm 111 by adhesion or the like.
[0014]
The voice coil 12 reacts with the magnetic circuit 2 by supplying a signal, vibrates, and transmits
the vibration to the diaphragm 11. The voice coil 12 is disposed in the gap portion of the
magnetic circuit 2. Further, one end of the voice coil 12 is connected to the diaphragm 11 by
adhesion or the like. Here, in the present invention, one end of the voice coil 12 is attached at a
position (70 ± 5)% from the center with respect to the outer diameter D 1 of the diaphragm 11.
Further, a signal is supplied to the voice coil 12 from the terminal 5 through the lead wire 4.
[0015]
The edge 13 is a member having a convex cross-sectional shape that supports the diaphragm 11
on the frame 3. The inner periphery of the edge 13 is connected to the outer periphery of the
diaphragm 11 with an adhesive or the like, and the outer periphery is fixed to the frame 3 by
adhesion or the like.
[0016]
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4
The damper 14 is for damping the vibration of the voice coil 12. In the damper 14, one end is
connected to the voice coil 12 by adhesion or the like, and the other end is fixed to the frame 3
by adhesion or the like.
[0017]
Moreover, the diaphragm 11 is comprised so that the area which planarly viewed the inner side
and the outer side of the position where the voice coil 12 was attached may become the same. In
the example of FIG. 1, the inclination of the dome-shaped diaphragm 111 and the inclination of
the cone-shaped diaphragm 112 are designed such that the areas of the inside and the outside
viewed in plan are the same.
[0018]
Next, the effect of the speaker according to the present invention will be described. Here, it is
known that in the "node driving" theory, the influence of the resonance on the sound pressure
characteristics can be canceled by driving the nodes of the axisymmetric resonance mode of the
circular plate with the force of the same diameter. On the other hand, in the present invention,
the voice coil 12 is attached at a position (70 ± 5)% from the center with respect to the outer
diameter D 1 of the diaphragm 11. In other words, the ratio of the VC diameter (drive diameter)
D 2 to the outer diameter D 1 of the diaphragm 11 is set to (70 ± 5)%. This means that the drive
diameter D 2 substantially matches the node diameter of the axisymmetric resonance mode
which occurs in the integral diaphragm 11 on the inside and the outside, and the node drive is
performed. Therefore, from the above configuration, it is possible to cancel the influence of the
resonance on the sound pressure characteristic.
[0019]
Further, this makes it possible to adopt a structure close to a flat plate in which the depth of the
diaphragm 11 is reduced, that is, the ratio of the depth / outer diameter of the diaphragm 11 is
reduced. And by using the diaphragm 11 with a small depth, the volume of the hollow space of
the front surface of the diaphragm 11 can be made small, and the sound pressure characteristic
fluctuation | variation by a "hollow effect" can be suppressed.
12-05-2019
5
[0020]
Further, the diaphragm 11 is configured such that the area of the inside and the outside of the
position (position of the driving diameter D 2) to which the voice coil 12 is attached is the same
in front view. Thus, by setting the same surface area on the outer side and the inner side of the
drive diameter D 2, the balance of drive becomes uniform, and split resonance can be prevented.
[0021]
In the above description, the dome-shaped diaphragm 111 and the cone-shaped diaphragm 112
are connected by bonding or the like. However, the present invention is not limited to this, and
the dome-shaped diaphragm 111 and the cone-shaped diaphragm 112 may be separated, or may
be integrally formed.
[0022]
Further, the direction of the dome-shaped diaphragm 111 and the cone-shaped diaphragm 112
may be in any direction with respect to the sound radiation direction of the speaker (upward in
the figure). For example, the dome shape may be a convex shape or a concave shape. In addition,
the dome inner circumferential portion may be recessed in the reverse direction to form a dome
groove shape in which a convex and a concave are combined. Note that FIG. 2 shows a case
where an inverted dome-shaped diaphragm 113 having a concave cross-sectional shape which is
recessed toward the center is used instead of the dome-shaped diaphragm 111 of FIG.
[0023]
Moreover, in FIG. 3, in order to set it as a structurally strong structure, the case where the
diaphragm 15 whose cross-sectional shape consists of several curved surfaces is used is shown.
In the example of FIG. 3, the case where the diaphragm 15 which provided the curved surface
which has 3 types of curvatures concentrically is shown is shown. The diaphragm 15 also has an
effect of suppressing the fluctuation of the sound pressure characteristic due to the "dentation
effect".
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6
[0024]
As described above, according to the first embodiment, diaphragm 11 and voice coil 12 attached
at a position of (70 ± 5)% from the center with respect to outer diameter D 1 of diaphragm 11
are provided. Therefore, even if the diaphragm 11 is made thin, it is possible to suppress split
resonance in the middle to low range and obtain flat sound pressure characteristics.
[0025]
In the present invention, within the scope of the invention, modifications of optional components
of the embodiment or omission of optional components of the embodiment is possible.
[0026]
Reference Signs List 1 vibration system, 2 magnetic circuit, 3 frame, 4 lead wire, 5 terminal, 11
diaphragm, 12 voice coil, 13 edge, 14 damper, 15 diaphragm, 21 magnet, 22 plate, 23 pole
piece, 111 dome shape vibration Plate, 112 cone-shaped diaphragm, 113 inverted dome-shaped
diaphragm.
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