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JPH0970095

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DESCRIPTION JPH0970095
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker having a narrow shape and excellent sound quality.
[0002]
2. Description of the Related Art In recent years, with the spread of high vision, wide vision and
the like, television screens having a wide screen are becoming common. On the other hand,
however, narrow and thin television sets as a whole are desired from the housing situation in
Japan.
[0003]
A speaker unit for television is usually attached to both sides of a cathode ray tube, which
contributes to increasing the width of the television set. Therefore, a narrow speaker unit having
a rectangular shape, an elliptical shape, or the like has conventionally been used for television. As
the width of the cathode ray tube is increased, the width of the speaker unit is required to be
further narrowed, and at the same time, it is also required to improve the sound quality of the
audio corresponding to the high image quality of the screen.
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1
[0004]
However, in the case of a general elongated speaker, since the elongated diaphragm is driven, if
the driving force, size, weight, etc. are uneven, the moment about the major axis is smaller than
that for the minor axis. The bias greatly affects the vibration state. Therefore, torsional resonance
in the major axis direction is easily excited. As a result, in the middle to high frequency band, a
peak dip occurs on the reproduced sound pressure frequency characteristic, resulting in an
increase in distortion and deterioration in sound quality.
[0005]
Hereinafter, the configuration of the conventional narrow speaker unit will be described with
reference to the drawings.
[0006]
FIG. 11 is a perspective view showing a conventional speaker unit.
FIG. 12 is a perspective view showing the components. Reference numeral 1 denotes a coneshaped diaphragm which has a major axis and a minor axis as viewed in the vibration direction
and which is concavely curved in the sound emitting direction. An edge 2 is joined to the outer
peripheral portion of the diaphragm 1 and is held by the frame 3. The voice coil bobbin 4 is fixed
to the lower end of the inner peripheral portion of the diaphragm 1. A voice coil 4 ′ is wound
around the outer peripheral surface of the voice coil bobbin 4. A damper 5 is attached to the
voice coil bobbin 4, and the damper is fixed to the frame 3. The voice coil 4 'is suspended in the
magnetic gap 7 of the magnetic circuit 6, and generates a driving force by the audio signal
current and the magnetic flux. The frame 3 is configured in the form of a box, the side of which is
along the edge 2. A magnetic circuit 6 is attached to the bottom of the frame 3. The magnetic
circuit 6 is composed of a center pole 8, a magnet 9 and a plate 10. The magnetic circuit 6 is
attached to the frame 3.
[0007]
However, in the above-mentioned conventional loudspeakers, since the driving force of the
loudspeakers is driven symmetrically with respect to the center of the diaphragm, the
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loudspeaker having an axisymmetric conical diaphragm is asymmetric. Vibration modes are
usually not a problem. However, in a narrow speaker unit such as an angular or elliptical type, in
order to drive an elongated diaphragm, slight nonuniformities in driving force, size, and weight
affect the vibration mode, so that asymmetric torsion is easily generated. Resonance occurs. Due
to this, there is a problem that the sound pressure frequency characteristic is disturbed.
[0008]
FIG. 13 shows the sound pressure frequency characteristics measured in an anechoic chamber
with the above-mentioned conventional speaker in a standard box. The horizontal axis is
frequency, and the vertical axis is sound pressure level. FIG. 13 shows sound pressure frequency
characteristics, second and third harmonic distortion, and electrical impedance characteristics as
viewed from the input terminal of the speaker. From the figure, the peak of sound pressure is at
0.8 kHz, and the second harmonic distortion occurs sharply. Therefore, when a 0.8 kHz signal is
reproduced, distorted sound is heard, which causes deterioration of the sound quality.
[0009]
It is FIG. 15 which analyzed the vibration mode of 0.8 kHz which this 2nd harmonic has
produced. This FIG. 15 is measured using a laser Doppler velocimeter, with the point on the
diaphragm indicated by a two-dot chain line in the plan view of the diaphragm shown in FIG. 14
as a measurement point. The amplitude of each point is overlapped and displayed while shifting
the time, thereby representing a vibration mode for one cycle. In addition, this measurement
frequency is 0.8 kHz and the measurement amplitude value is expanded and shown. As shown in
the figure, the central part of the diaphragm is translationally vibrated evenly, but at the end in
the major axis direction the amplitudes are different at the left and right, and the deviation is
reversed between the upper and lower sides of the end in the figure. Twisted. As described above,
in the above-described conventional speaker, there is a problem that a torsional resonance
occurs in which the phase of the end portion of the long diameter is shifted by 180 degrees at
0.8 kHz.
[0010]
According to a first aspect of the present invention, there is provided an outer peripheral portion
of a cone-shaped diaphragm which has a major axis and a minor axis when viewed from the
vibration direction and which is concavely curved in a sound emitting direction. A visco-elastic
member is fixed in the vicinity of the end of the diaphragm in the longitudinal direction of the
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edge of the edge formed in a strip shape.
[0011]
According to a second aspect of the present invention, the planar shape viewed from the
vibration direction is formed in a band shape along the outer peripheral portion of the nonaxisymmetric diaphragm having a major axis and a minor axis and convexly curved in the sound
radiating direction. A visco-elastic member is fixed in the vicinity of the end of the diaphragm in
the major axis direction of the diaphragm.
[0012]
According to a third aspect of the present invention, the planar shape viewed from the vibration
direction is formed in a band shape along the outer peripheral portion of the non-axisymmetric
diaphragm having a major axis and a minor axis and curved convexly in the sound radiating
direction. The strip-like inner peripheral portion is connected to the outer peripheral portion of
the diaphragm, and the edge for holding the diaphragm in a vibrating manner and the diaphragm
are connected, and the planar shape is a non-axisymmetric shape having a major axis and a
minor axis The voice coil bobbin having straight portions parallel to each other with respect to
the major axis direction of the diaphragm and having the end portions connected by arcs, and the
vibration between the sides opposing each other in the minor axis direction on the inner
peripheral portion of the diaphragm. A thin plate reinforcing member extending parallel to the
vibration direction of the plate and at a right angle to the opposite side, and the thin plate
reinforcing member has a sandwich structure in which a visco-elastic member is sandwiched
between thin paper and aluminum foil, Place the voice coil in the vicinity of the connection
between the straight part and the arc part Lower end with is a speaker, characterized in that it
has extended to the voice coil lower end.
[0013]
The fourth invention is connected to the diaphragm, has a non-axisymmetric planar shape having
a major axis and a minor axis, and forms linear portions parallel to each other in the major axis
direction of the diaphragm, and the terminal end is an arc. A visco-elastic lightweight member
such as foamed butyl or urethane foam is fixed to the end of the connected voice coil bobbin in
the major axis direction.
[0014]
According to a fifth aspect of the present invention, the thin plate-like reinforcing member is
provided on a diagonal of a cone-shaped diaphragm which has a major axis and a minor axis and
a concave shape curved in a sound radiating direction. It is a speaker to be characterized.
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[0015]
In a sixth aspect of the present invention, the planar shape viewed from the vibration direction
has a major axis and a minor axis, and the diaphragm having a cone shape curved concavely in
the sound emitting direction is symmetrical on the major axis and minor axis It is a speaker
characterized in that a visco-elastic member is fixed at a symmetrical position as an axis.
[0016]
According to the first to fourth inventions having such characteristics, since the visco-elastic
member is disposed at the end of the major axis of the diaphragm with the largest torsional
vibration amplitude, the resonance amplitude is obtained by the damping effect by the viscoelasticity. Can be reduced.
[0017]
Further, according to the speaker of the fifth aspect of the present invention, since the
reinforcing members are provided diagonally, the diaphragm strength against twist can be
enhanced.
[0018]
Further, according to the sixth invention, by fixing the visco-elastic member on the major axis of
the major axis, it is possible to reduce the deviation of weight around the major axis, and further,
it is possible to damp the resonance by the visco-elasticity.
[0019]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the
present invention will now be described with reference to the drawings.
[0020]
FIG. 1 is a perspective view of a speaker according to a first embodiment of the present
invention.
FIG. 2 is an exploded configuration view showing the configuration.
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Reference numeral 1 denotes a cone-shaped diaphragm which has a major axis and a minor axis
as viewed in the vibration direction and which is concavely curved in the sound emitting
direction.
An edge 2 is joined to the outer peripheral portion of the diaphragm 1 and is held by the frame
3.
A gel-like viscoelastic member 11 is fixed in four places in the vicinity of the connection point
between the straight line portion and the arc portion at the end of the edge 2 in the major axis
direction.
The voice coil bobbin 4 is fixed to the lower end of the outer peripheral portion of the diaphragm
1.
A voice coil 4 ′ is wound around the outer peripheral surface of the voice coil bobbin 4.
A damper 5 is attached to the voice coil bobbin 4 and fixed to the frame 3.
The voice coil 4 'is suspended in the magnetic gap 7 of the magnetic circuit 6, and generates a
driving force by the audio signal current and the magnetic flux.
The frame 3 is configured in the form of a box, the side of which is along the edge 2.
A magnetic circuit 6 is attached to the bottom of the frame 3. The magnetic circuit 6 comprises a
center pole 8, a magnet 9 and a plate 10, and the magnetic circuit 6 is attached to the frame 3.
[0021]
Subsequently, a loudspeaker according to a second embodiment of the present invention will be
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described with reference to the drawings. FIG. 5 is an exploded configuration view showing the
speaker structure of the second embodiment. The same parts as those of the speaker shown in
FIG.
[0022]
In FIG. 5, reference numeral 12 denotes a non-axisymmetric diaphragm having a major axis and
a minor axis as viewed in the direction of vibration and having a convex shape curved in the
direction of sound emission. The edge 2 is joined to the outer peripheral portion of the
diaphragm and held by the frame 13. A gel-like viscoelastic member 11 is fixed in four places in
the vicinity of the connection point between the straight portion and the arc portion at the end
portion in the major axis direction of the edge 2. The voice coil bobbin 14 is fixed to the lower
end of the outer peripheral portion of the diaphragm 12. The voice coil 15 is wound around the
outer peripheral surface of the voice coil bobbin 14. The planar shape of the voice coil bobbin 14
as viewed from the vibration direction of the diaphragm 12 is non-axisymmetric with a major
axis and a minor axis, and a part of the voice coil bobbin is a linear portion parallel to each other
in the major axis direction of the diaphragm. I Inside the voice coil bobbin 14, a thin plate-like
connecting member 16 is attached which stretches between the facing surfaces in parallel with
the vibration direction of the diaphragm 12 and at a right angle to the facing surface. The lower
end of the thin plate connecting member 16 is extended further downward than the lower end of
the voice coil bobbin 14. And the damper 17 is attached to the lower end part, and it adheres to
the flame ¦ frame 13. As shown in FIG.
[0023]
The voice coil 15 is suspended in the magnetic gap 19 of the magnetic circuit 18, and generates
a driving force by the audio signal current and the magnetic flux. The frame 13 is configured in
the form of a box, the side surfaces of which are along the edge 2. A magnetic circuit 18 is
attached to the bottom of the frame 13. The magnetic circuit 18 is composed of a U-shaped yoke
20, a magnet 21 and a plate 22. A plurality of magnetic circuits 18 are attached to the frame 13
with an air gap 23 for passing the thin plate-like connecting member 16 and a plurality of
magnetic air gaps 19 aligned.
[0024]
The operation and action of the loudspeakers of the first and second embodiments configured as
described above will be described below.
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[0025]
In a narrow speaker unit, asymmetric torsional resonance is likely to occur in order to drive an
elongated diaphragm.
However, in the present embodiment, since the gel-like visco-elastic member 11 is fixed at four
positions near the connection point between the straight portion and the arc portion at the end
of the edge, torsional resonance is damped by this visco-elastic member It becomes. As apparent
from the vibration state of torsional resonance (FIG. 15), when torsional vibration occurs, the
amplitudes at the four end portions of the edge 2 become large. Since the visco-elastic member
acts as a resistance by vibrating, it is effective to suppress torsional resonance if it is disposed at
a portion where the vibration amplitude is large as in this embodiment. Moreover, there is almost
no drop in the reproduction efficiency of the speaker due to the increase in weight of the
vibration system.
[0026]
FIG. 3 is a sound pressure frequency characteristic diagram of the loudspeaker according to the
first embodiment. As compared with FIG. 13, it can be seen that the disturbance of the sound
pressure frequency characteristic of 0.8 kHz and the second harmonic distortion are improved.
FIG. 4 is also a diagram showing a vibration mode of 0.8 kHz. As compared with FIG. 15, it can be
seen that both the central portion and the end portion in the major axis direction of the
diaphragm perform translational vibration, and torsional resonance is suppressed. The same
effect can be obtained in the configuration of the second embodiment.
[0027]
As described above, by adopting the configurations of the speakers of the first and second
embodiments, torsional resonance can be suppressed, and disturbance and distortion of the
sound pressure frequency characteristics can be reduced.
[0028]
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8
Next, a third embodiment of the present invention will be described with reference to the
drawings.
The same parts as those of the loudspeaker (second embodiment) shown in FIG. The
configuration of the present embodiment is basically the same as the configuration (FIG. 5)
shown in the second embodiment, and the method of providing the viscoelastic member is
different.
[0029]
FIG. 6 is a perspective view of a voice coil bobbin showing a third embodiment of the present
invention. The voice coil 15 is wound around the outer peripheral surface of the voice coil
bobbin 14. The planar shape of the voice coil bobbin 14 as viewed from the vibration direction of
the diaphragm 12 is non-axisymmetric with a major axis and a minor axis, and a part of the voice
coil bobbin is a linear portion parallel to each other in the major axis direction of the diaphragm.
I In the inside of the voice coil bobbin 14, thin plate-like connecting members 16 are attached,
which extend between the surfaces facing each other in parallel with the vibration direction of
the diaphragm 12 and at a right angle with the facing surfaces. The end of the straight portion of
the voice coil bobbin 14 has an arc shape. A thin plate-like reinforcing member 24 extending
parallel to the vibration direction of the diaphragm 12 and extending at a right angle to the
opposite surface is attached to the connection portion between the straight portion and the arc
portion.
[0030]
In the present embodiment, the thin plate reinforcing member 24 has a sandwich structure in
which the core material 25 formed of a visco-elastic material such as butyl rubber or asphalt in a
thin plate shape is sandwiched from both sides by a thin plate 26 such as paper or aluminum. .
The upper end of the thin plate reinforcing member 24 is formed in an arc shape and is fixed to
the back surface of the diaphragm 12, and the lower end is extended to the vicinity of the lower
end portion of the voice coil.
[0031]
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The operation and action of the loudspeaker according to the third embodiment configured as
described above will be described. In a narrow speaker unit, asymmetric torsional resonance is
likely to occur in order to drive an elongated diaphragm. However, in the present embodiment,
since the thin plate-like reinforcing member 24 sandwiching the visco-elastic member is fixed in
the vicinity of the end of the voice coil in the longitudinal direction, the torsional resonance is
damped by the visco-elastic member 26. When torsional vibration occurs, the amplitude of the
end increases, and when torsional resonance occurs, the voice coil is also twisted as is apparent
from the vibration mode diagram of FIG. However, according to the configuration of the present
embodiment, a compressive extension force acts on the thin plate reinforcing member 24, and
the thin plate reinforcing member expands and contracts in the minor axis direction of the
diaphragm and bends in the major axis direction. At this time, the visco-elastic member 25 as a
core material is compressed and stretched at the neutral point of the sandwich structure. The
visco-elastic body works in the opposite direction of compression and expansion at the boundary
of the neutral axis, and works to suppress resonance by the viscosity of the material. The sound
pressure frequency characteristic according to the configuration of this embodiment can obtain
the same characteristic as that shown in FIG. As described above, according to the configuration
of the loudspeaker of the present embodiment, it is possible to suppress torsional resonance and
reduce the disturbance and distortion of the sound pressure frequency characteristic.
[0032]
Next, a fourth embodiment of the present invention will be described with reference to the
drawings. The same parts as those of the loudspeaker (second embodiment) shown in FIG. The
configuration of the present embodiment is basically the same as the configuration (FIG. 5)
shown in the second embodiment, and the method of providing the viscoelastic member is
different.
[0033]
FIG. 7 is a perspective view of a voice coil bobbin showing a fourth embodiment of the present
invention. The voice coil 15 is wound around the outer peripheral surface of the voice coil
bobbin 14. The planar shape of the voice coil bobbin 14 as viewed from the vibration direction of
the diaphragm 12 is non-axisymmetric with a major axis and a minor axis, and a part of the voice
coil bobbin is a linear portion parallel to each other in the major axis direction of the diaphragm.
I In the inside of the voice coil bobbin 14, thin plate-like connecting members 16 are attached,
which extend between the surfaces facing each other in parallel with the vibration direction of
the diaphragm 12 and at a right angle with the facing surfaces. The end of the straight portion of
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the voice coil bobbin 14 has an arc shape. A thin plate-like reinforcing member 27 extending
parallel to the vibration direction of the diaphragm 12 and extending at a right angle to the
opposing surface is attached to the connection portion between the straight portion and the arc
portion.
[0034]
In the present embodiment, the visco-elastic lightweight member 28 is fixed to the outside of the
thin plate-like reinforcing member 27. The visco-elastic lightweight member 28 is a material
obtained by foaming a visco-elastic material such as foamed butyl rubber or foamed urethane,
and is formed in a shape conforming to the shapes of the voice coil bobbin and the diaphragm.
The upper end of the viscoelastic lightweight member 28 is formed in an arc shape and is fixed
to the back surface of the diaphragm 12, and the lower end is extended to the vicinity of the
lower end of the voice coil.
[0035]
As in the third embodiment, when the torsional resonance occurs, the viscoelastic lightweight
member 28 is deformed, thereby absorbing the resonance energy. It suppresses the occurrence
of resonance. The sound pressure frequency characteristic according to the configuration of this
embodiment can obtain the same characteristic as that shown in FIG. As described above,
according to the configuration of the loudspeaker of the present embodiment, it is possible to
suppress torsional resonance and reduce the disturbance and distortion of the sound pressure
frequency characteristic.
[0036]
Next, a fifth embodiment of the present invention will be described with reference to the
drawings. The same parts as those of the speaker (first embodiment) shown in FIG. The
configuration of this embodiment is basically the same as the configuration (FIG. 1) shown in the
first embodiment.
[0037]
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FIG. 8 is a perspective view showing a diaphragm according to a fifth embodiment of the present
invention, and FIG. 9 is an exploded view thereof. As apparent from the figure, the planar shape
viewed from the vibration direction has a major axis and a minor axis, and the concave portion of
the cone-shaped diaphragm 1 concavely curved in the sound emitting direction is a linear portion
of the diaphragm A reinforcing member 29 is fixed which diagonally reinforces the connection
point of the arc portion and the arc portion. The reinforcing member 29 is made of paper or a
lightweight and highly rigid material such as thin aluminum foil or titanium foil.
[0038]
In the loudspeaker of the fifth embodiment configured as described above, the reinforcing
members 29 arranged on the diagonal of the diaphragm increase the rigidity of the diaphragm 1
and suppress the amplitude of the diaphragm at torsional resonance. Works. Therefore, in the
loudspeaker of this embodiment, torsional resonance is suppressed, and the sound pressure
frequency characteristic is flat and distortion is reduced.
[0039]
Finally, the loudspeaker according to the sixth embodiment of the present invention will be
described with reference to the drawings. The same parts as those of the speaker shown in FIG.
The configuration of this embodiment is basically the same as the configuration (FIG. 1) shown in
the first embodiment.
[0040]
FIG. 10 (a) is a plan view showing the diaphragm 1 of the speaker of the present embodiment,
and FIG. 10 (b) is a cross-sectional view as seen from the arrow direction in A-A 'of FIG. The
planar shape viewed from the vibration direction has a major axis and a minor axis, and is at a
symmetrical position on the major axis of the cone-shaped diaphragm 1 concavely curved in the
sound radiating direction with the minor axis as the symmetry axis. A lightweight visco-elastic
auxiliary mass 30 such as urethane foam or foam rubber is adhered.
[0041]
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12
The operation and action of the loudspeaker of this embodiment configured as described above
will be described. The torsional resonance of the diaphragm occurs due to an imbalance in shape,
weight, and driving force in the minor axis direction bordering on the major axis, but in the
present embodiment, it is a visco-elastic auxiliary mass bonded on the central axis in the major
axis direction. Acts to move the center of gravity on the central axis, and corrects the weight
imbalance in the minor axis direction. And since it comprises with a visco-elastic member, when
resonance generate ¦ occur ¦ produces, it has an effect ¦ action which absorbs vibration energy
and suppresses resonance. For this reason, the speaker of this embodiment can reproduce a
sound with little distortion.
[0042]
As is apparent from the above description, the loudspeaker according to the present invention is
provided with a visco-elastic member at a predetermined part of the loudspeaker, so that
torsional resonance does not easily occur although it is narrow, whereby a flat frequency is
obtained. It is possible to obtain a speaker with excellent sound quality, which has characteristics
and is less likely to cause abnormal vibration.
[0043]
Brief description of the drawings
[0044]
1 is a perspective view showing the configuration of a speaker according to a first embodiment
of the present invention
[0045]
2 is an exploded perspective view of the speaker according to the first embodiment of the
present invention
[0046]
Fig. 3 Sound pressure frequency characteristics of the first embodiment of the present invention
[0047]
4 vibration mode diagram of the first embodiment of the present invention
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[0048]
5 is an exploded perspective view of a speaker according to a second embodiment of the present
invention
[0049]
6 is a perspective view of the voice coil bobbin of the speaker according to the third embodiment
of the present invention.
[0050]
7 is a perspective view of the voice coil bobbin of the speaker according to the fourth
embodiment of the present invention.
[0051]
8 is a perspective view showing the configuration of the diaphragm of the speaker according to
the fifth embodiment of the present invention.
[0052]
9 is an exploded perspective view of a diaphragm of a speaker according to a fifth embodiment
of the present invention.
[0053]
FIG. 10 (a) is a plan view of the diaphragm of the speaker according to the sixth embodiment of
the present invention.
[0054]
Fig. 11 A perspective view of the conventional speaker
[0055]
Figure 12: An exploded perspective view of the conventional speaker
[0056]
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Fig. 13 Sound pressure frequency characteristics of conventional speakers
[0057]
Fig. 14 An explanatory view of the vibration mode of the conventional speaker
[0058]
Fig.15 Vibration mode diagram of the conventional speaker
[0059]
Explanation of sign
[0060]
Reference Signs List 1 diaphragm 2 edge 3 frame 4 voice coil bobbin 4 'voice coil 5 damper 6
magnetic circuit 7 magnetic gap 8 center pole 9 magnet 10 plate 11 viscoelastic member 12
diaphragm 14 voice coil bobbin 15 voice coil 16 thin plate connection member 17 damper 18
magnetic Circuit 19 magnetic gap 20 yoke 21 magnet 22 plate 23 gap 24 thin reinforcing
member 25 viscoelastic core 26 thin plate reinforcing member 27 thin plate reinforcing member
28 viscoelastic foam member 29 reinforcing member 30 viscoelastic supporting mass
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