JP2005295150

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DESCRIPTION JP2005295150
PROBLEM TO BE SOLVED: In the human auditory sense, since the sound quality is substantially
specified at the rising edge of the sound wave, the sound wave oscillated from the vibrator
collides with the baffle plate to cause energy loss, thereby resulting in a waveform with a bad
rising edge. Sound quality sounds bad. Therefore, a speaker device, such as a tweeter, capable of
improving the sound quality is provided. SOLUTION: A porous layer is formed on the surface of a
baffle plate surrounding a vibrator. This porous layer is obtained, for example, by attaching a
particle group such as quartz having a particle diameter of about 0.5 mm to 1 mm into a plurality
of layers with a paint or the like and removing a paint component to some extent with a solvent
to form a cavity. Be [Selected figure] Figure 4
Speaker apparatus and speaker system for reproduction
[0001]
The present invention relates to a reproduction speaker device and a speaker system.
[0002]
As a speaker system, a multi-speaker system such as a two-way system including a tweeter (a
speaker device for high frequency range reproduction) and a woofer (a speaker device for low
frequency range reproduction) is known (for example, Patent Document 1).
Although the speaker technology is focused on improving the sound quality of the woofer, the
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current situation is that it is not focused much on the sound quality of the tweeter.
[0003]
In the tweeter, the sound wave emitted from the vibrator is turned to the rear side and collides
with the baffle plate to be reflected and travels forward, but the air layer existing on the surface
of the baffle plate before the collision collides. The energy of the sound waves is, so to speak,
kicked off and runs away along the surface. That is, the energy of the sound wave to be reflected
is reduced because the energy of the sound wave to be collided is consumed by the escape of the
air layer. For this reason, as shown in FIG. 6, the rising portion of the waveform (solid line) of the
sound wave before the collision is broken and becomes a dotted waveform. On the other hand, in
the human auditory sense, the sound quality is substantially specified at the 1⁄4 wavelength of
the sound wave, so if the waveform becomes bad due to the energy loss at the time of the sound
wave collision, the sound may sound like poor sound quality.
[0004]
Japanese Patent Application Laid-Open No. 2003-111190
[0005]
The present invention has been made under such circumstances, and an object thereof is to
provide a reproduction speaker device and a speaker system that can be heard as good sound
quality.
[0006]
The present invention is characterized in that, in the speaker device for reproduction provided
with a vibrator and a reflection surface part that reflects the sound wave from the vibrator to the
front side, a porous layer is formed on the surface of the reflection surface part.
The porous layer is formed, for example, by forming a large number of particles in layers, and in
this case, it is preferable to be laminated in a plurality of layers rather than a single layer.
The present invention is suitable for a speaker for reproducing sound in a high frequency range.
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Further, as an example of the reflective surface portion, a ring-shaped plate configured to
surround the vibrator or a horn extending forward from the vibrator can be mentioned. Another
invention is a speaker system using the above-mentioned speaker device as a speaker device for
high frequency range reproduction and including this speaker device and a low frequency range
reproduction speaker device.
[0007]
According to the present invention, the porous layer is formed by forming, for example, a large
number of particles in layers on the surface of the reflective surface portion, so that sound waves
from the vibrator are present on the surface when they strike the surface. The air layer is
confined in the porous layer, the amount of air escaping along the surface of the reflecting
surface decreases, and as a result, the degree of the rising of the sound wave waveform
decreases. As described above, the sound quality felt by a person is determined by the rise of the
sound wave, and as a result, it can be heard as a good sound quality. Furthermore, since the
porous layer is formed, the secondary wave at the time of the collision of the sound wave is
absorbed, the sound of the material of the reflective surface portion is hardly emitted, and the
sound quality is also improved from this point.
[0008]
In the embodiment of the speaker system according to the present invention, as shown in FIG. 1,
a tweeter (a speaker device for high frequency range reproduction) 2 and a woofer (for low
frequency range reproduction) are provided on a front part 11 of a housing 1 which is a speaker
box. And the speaker device 3). The tweeter 2, for example, is responsible for the output of the
frequency range of 1 kHz or more, and the woofer 3 is responsible for the output of the
frequency range lower than that, but is not limited to this frequency value. Incidentally, to cover
the frequency range of 1 kHz or more means that the sound pressure increases as the frequency
increases until it reaches 1 kHz, and the sound pressure becomes stable when it exceeds 1 kHz.
The tweeter 2 corresponds to an embodiment of the speaker device of the present invention, and
in this example, is configured as a so-called dome-shaped speaker, and a ring-shaped baffle which
is a reflection surface portion so as to surround the dome-shaped vibrator 21. A plate 22 is
provided.
[0009]
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The structure of the tweeter 2 will be described in detail with reference to FIG. 2. Reference
numeral 12 denotes an opening formed in the front surface portion 11 of the housing 1, and a
reflecting surface portion is formed on the outer surface side to close the opening 12. A ringshaped baffle plate 22 made of, for example, aluminum is fixed by fastening a screw 23 around
the periphery. In the central hole 24 of the baffle plate 22, a hemispherical (dome-shaped)
vibrator 21 projecting to the front side is provided at the tip of the bobbin 41. A voice coil 42 is
wound around the bobbin 41. The voice coil 42 is disposed in the magnetic circuit formed by the
pole piece 43, the first metal member 44, the magnet (permanent magnet) 45, and the second
metal member 46. It is located in The pole piece 43, the first metal member 44, the magnet 45
and the second metal member 46 are fixed to each other by an adhesive to form a magnetic
circuit unit, and the magnetic circuit unit is fixed to the back surface of the baffle plate 22 (not
shown). It is attached by a member.
[0010]
The porous layer 5 is formed on the surface of the baffle plate 22. An example of a method of
forming the porous layer 5 will be described with reference to FIG. 3. First, a stock solution of
acrylic paint, for example, is applied to the surface of the baffle plate 22 as the adhesive 51 (FIG.
3 (a)). When a particle group of about 0.5 to 1 mm in diameter made of quartz is placed on this
surface and the baffle plate 22 is inclined to spill the particle group, a particle layer 52 is formed
on the surface of the baffle plate 22 (FIG. b). Subsequently, before the adhesive 51 is dried, the
adhesive 51 is further applied from above the particle layer 52 (FIG. 3 (c)), and the particle group
is placed on the surface, and the baffle plate 22 is inclined to When the group is spilled, a second
particle layer 53 is formed on the already formed first particle layer 52 (FIG. 3 (d)). Then, before
the adhesive 51 is dried, a thin paint 54 previously diluted with an acrylic paint with a solvent
and adjusted to a concentration of 20% is supplied, for example, by coating from above the
particle layers 52, 53.
[0011]
After the particles are adhered to the surface of the baffle plate 22 using an adhesive as
described above to form the particle layers 52, 53, a thin paint (adhesive) 54 is applied from
above as shown in FIG. When supplied, the excess paint component in the gaps between the
particle layers 52, 53 is dissolved and descended to obtain a porous layer (porous structure) 5 as
shown in FIG. 3 (f).
[0012]
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Next, the operation of this embodiment will be described.
When an audio signal is output from the amplifier (not shown) to the voice coil 42 and the dome
shaped vibrator 21 vibrates, the sound wave spreads as shown in FIG. 4 (a). The waveform shown
by the dashed line shows the longitudinal wave in the air, and the arc-shaped solid line shows the
wave front of the longitudinal wave. The wavefront travels forward but spreads on both sides and
collides with the baffle plate 22 located on the back side of the vibrator 21.
[0013]
The collided sound wave is reflected on the surface of the baffle plate 22. However, if the surface
is flat as shown in FIG. 4 (b), the energy of the sound wave will escape sideways at the time of the
collision. This point will be described in more detail in the "Background Art" section, but since air
is originally present on the surface of the baffle plate 22, when the wave front of the sound wave
collides, the energy of the collision causes The air that was present is pushed sideways. This
means that the energy of the sound wave is consumed in the form of pushing air sideways, and
the energy of the reflected wave is reduced. This phenomenon is that, for example, when a ball is
dropped on a floor covered with rubber balls, the rubber balls spread laterally, and as a result, a
part of the collision energy of the ball is used, so that the rebound energy of the ball is reduced.
It is similar to As described above, when energy loss occurs at the time of collision of sound
waves, the rising of the sound waves reflected forward is deteriorated.
[0014]
On the other hand, when the porous layer 5 is formed on the surface of the baffle plate 22 as
shown in FIG. 4 (b), when the sound waves collide, the air tends to be pushed laterally by the
impact, Since it is confined in the porous layer 5, there is no escape place for the air, and hence
the energy consumed for the escape of the air originally existing on the surface of the baffle plate
22 is reduced, so the energy loss is reduced. The energy of the split reflected wave is larger than
in the case of a flat surface. In the case of a rubber ball, for example, since the rubber ball group
on the floor can not move, it means that the energy of ball rebound is large.
[0015]
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As a result, the degree of collapse of the rising of the sound wave reflected forward is
suppressed, and as described above, the sound quality of the human ear is determined at the
quarter wavelength of the rising of the sound wave. I can hear you. Here, if the frequency of the
sound wave is high and the wavelength is short, and most of one cycle of the sound wave enters
the cavity in the porous layer, the energy loss when the sound wave is reflected becomes large. In
order to avoid this, the particle size of the particle group may be reduced, but this time, in the
low frequency region, the effect of confining air in the porous layer at the time of the sound wave
collision will diminish. Therefore, in order to suppress energy loss during reflection over a wide
frequency range, it is preferable to select the particle size distribution so that the size of the
cavity varies depending on the location.
[0016]
Furthermore, according to the above-described embodiment, since the porous layer 5 is formed,
the secondary wave is absorbed when the sound wave collides with the baffle plate 22 and the
sound of the material of the baffle plate 22 is hardly emitted. Thus, the sound quality is also
improved from this point. Here, the particle group constituting the porous layer 5 is not limited
to quartz, and may be alumina, zeolite, or the like, or may be metal. Further, the porous layer 5 is
not limited to the above-described manufacturing method, and for example, a porous layer
prepared in advance by particles may be attached to the surface of the baffle plate 22.
Furthermore, when the porous layer is formed of particles, it is not limited to one in which the
particles are bonded by an adhesive, and for example, the particles may be sintered together. In
the case of using a sintered body, a binder is added to particles made of metal or ceramic in
advance and mixed, and the mixed powder is applied to the surface of the baffle plate, and then
the baffle plate is heated to form particles. And sintering the particles and the surface of the
baffle plate.
[0017]
In addition, the front surface portion of the housing 1 also functions as a reflection surface
portion in that the sound wave to be wound around later is reflected, and a porous layer may be
formed also on the surface of the front surface portion.
[0018]
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Furthermore, the speaker device of the present invention is not limited to the above-described
dome type, but can be applied to a horn type speaker as shown in FIG.
In FIG. 5, reference numeral 61 denotes a transducer unit portion provided with a transducer,
and reference numeral 62 denotes a horn which surrounds the transducer, extends forward from
there, and is further expanded in diameter. In this speaker device, the sound wave oscillated from
the vibrator spreads forward while the sound wave is reflected by the horn 62. That is, the horn
62 also corresponds to a reflection surface portion, and if the porous layer 5 is formed on the
inner surface as described above, the amount of sound wave escaped along the surface when
colliding with the horn 62 decreases. The energy loss at the time of reflection is reduced, and the
same effect can be obtained.
[0019]
The confirmation of the effect of the present invention is not performed using a measuring
instrument, but the speaker system having the structure shown in FIG. 1 and the comparison
speaker system having the same configuration except that the porous layer is not formed on the
tweeter. The sound quality was compared between each other, and it was confirmed that the
system of the present invention is superior in the sound quality of the range that the twitter
handles. The panelists who are skilled in the audio field cooperated with them, and when they
asked me to make similar comparisons, I received the opinion that the sound quality was
significantly improved.
[0020]
BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic perspective view which shows the
speaker system provided with the speaker apparatus concerning embodiment of this invention. It
is a vertical side view which shows said speaker apparatus. It is explanatory drawing which
shows a mode that a porous layer is formed in said speaker apparatus. It is explanatory drawing
which shows the effect ¦ action in said speaker apparatus. It is a vertical side view which shows
the speaker apparatus concerning other embodiment of this invention. It is explanatory drawing
which showed a mode that the standup ¦ rising part of the waveform of a sound wave collapses
by a collision.
Explanation of sign
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[0021]
DESCRIPTION OF SYMBOLS 1 case 11 front part 2 tweeter 21 vibrator 22 baffle plate 3 woofer
5 porous layer 51 adhesive agent 52, 53 particle layer 61 vibrator unit part 62 horn
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