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JP2002320292

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DESCRIPTION JP2002320292
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
spherical speaker using a piezoelectric vibrator as a driving source, and more particularly to a
spherical speaker having a frameless structure and easy to carry and excellent in frequency
characteristics.
[0002]
2. Description of the Related Art A piezoelectric speaker used as an audio speaker has a
piezoelectric element (mainly a group of piezoelectric ceramics such as PZT), a piezoelectric
vibrator consisting of a metal diaphragm and an electrode as a sound source, and its sound
pressure-frequency characteristics In most cases, it is incorporated into a speaker unit for
tweeter use.
[0003]
On the other hand, a spherical diaphragm or a so-called "breathing sphere speaker" which
generates non-directional sound by vibrating the entire spherical surface as if the alveoli breathe
(called respiratory vibration) with a spherical diaphragm or vibrator. There is a speaker.
[0004]
In this regard, Japanese Patent Application Laid-Open No. 9-163498 discloses a spherical
03-05-2019
1
piezoelectric speaker of a breathing sphere which uses a piezoelectric element of a spherical
shell as a driving source as shown in FIG.
That is, the spherical piezoelectric speaker 60 has a hollow spherical shell type piezoelectric
ceramic 61 and an external electrode 62 on the outer surface of the piezoelectric ceramic 61 and
an internal electrode 63 on the inner surface as driving means for driving the piezoelectric
ceramic 61. A sound absorbing material 64 is provided in the hollow portion of the piezoelectric
ceramic 61, and a frame 65 for holding the piezoelectric ceramic 61 is provided on the outer
surface of the piezoelectric ceramic 61 with a damper 66 for reducing the influence of external
vibration. It is the structure arrange | positioned via.
Reference numerals 67 and 68 denote lead terminals connected to a driving device (not shown).
[0005]
The spherical piezoelectric speaker 60 of the above configuration is structurally characterized in
that the piezoelectric element of the spherical shell is a component, and all the sounds outputted
from the outer surface of the piezoelectric ceramic 61 have the same phase, Since the sound to
be output is absorbed by the sound absorbing material 64, it is said that the sound to be output
from the outer surface is not canceled out.
[0006]
However, in the above-described conventional spherical piezoelectric speaker 60, the
piezoelectric ceramic 61 itself of the spherical shell which is a component thereof has a very
unique structure, and the external electrode 62 on the outer surface thereof There is a problem
in terms of manufacturing cost in combination with the formation of the inner electrode 63 on
the inner surface.
[0007]
There is no doubt that the sound pressure-frequency characteristics are still lacking.
That is, only a relatively low sound pressure is obtained in the frequency range of 100 to 1000
Hz, which is the most important middle bass range as an audio speaker, and it is far from being
compatible with the full range.
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2
[0008]
In terms of handling, it must be considered easy to transport and install because of its spherical
shape, but with the above-mentioned spherical speaker 60 whose shape is fixed, it is difficult to
increase the size, and it is easy to break it. The total weight can not be ignored.
As a result, it will be limited to the case of using for tweeter.
[0009]
Further, the holding frame 65 surrounds the piezoelectric ceramic 61 and is boneless and does
not look good in appearance.
[0010]
As described above, in the spherical speaker using the conventional piezoelectric element, a full
range speaker excellent in cost, handling and appearance eye catch has not been realized.
[0011]
The present invention has been made in consideration of the above circumstances, and provides
a spherical speaker having a novel structure that is lightweight and easy to handle, and that uses
a piezoelectric vibrator as a sound source to cope with a full range.
[0012]
According to the present invention, there are provided (1) a ball-shaped vibrator 5 of soft sheet
material in which a gas is contained and expanded, and a part of the ball-shaped vibrator 5 is
perforated to form a ball-shaped And a thin plate-like piezoelectric vibrator 7 attached by
attaching its peripheral edge so as to be integrated with the vibrating body 5, and the drive signal
is inputted to the piezoelectric vibrator 7 so as to vibrate. The above problem is solved by
providing a spherical speaker 20 characterized in that the entire vibrating body 5 is vibrated to
generate sound.
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(2) Further, a reinforcing plate 15 made of doughnut-shaped foamed resin provided around the
piezoelectric vibrator 3 on the inner surface side of the spherical vibrator 5 and the piezoelectric
vibrator 7 on the surface side of the spherical vibrator 5 The spherical speaker 20 according to
the above (1) is characterized in that it comprises: a doughnut-shaped synthetic resin sheet 16
attached around the periphery; and a weight 17 attached to the center of the piezoelectric
vibrator 7. The above problems are solved by providing.
(3) Further, a spherical vibrator 21 having light transmittance, a light emitting diode 23 disposed
inside the spherical vibrator 21 and emitting light in response to a drive signal of the
piezoelectric vibrator 7; A pattern 25 drawn on the outer surface or the inner surface of the
sphere-shaped vibrator 21 or a decoration 26 disposed inside the sphere-shaped vibration body
21; The above problem is solved by providing the spherical speaker 30 according to the above
(1) or (2) characterized in that the light is illuminated to the outside of the spherical vibrator 21.
[0013]
Embodiments of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 is a perspective view of a spherical speaker according to the present invention, and FIG. 2
is a sectional structural view of a piezoelectric vibrator attached to the spherical speaker
according to the present invention.
FIG. 3 is a sound pressure-frequency characteristic diagram of the spherical speaker according to
the present invention.
FIG. 4 is a cross-sectional view showing another embodiment of the spherical speaker according
to the present invention. FIG. 5 shows an example of a drive circuit of a light emitting diode.
[0015]
In FIG. 1 or 2, the spherical speaker 20 is a gas (usually air) from an open / close plug (for
example, a beach ball air plug structure) not shown, but other gas such as helium or nitrogen is
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assumed. A ball-shaped vibrating body 5 of a soft sheet material such as vinyl chloride or
polypropylene with a thickness of 0.3 to 1.5 mm, such as a beach ball, and a portion of the ballshaped vibrating body 5 A thin plate-like piezoelectric vibrator 7 (disk-like) attached by attaching
an adhesive (not shown) at its periphery so as to form a circular hole, close the hole and become
integral with the spherical vibrator 5 The amplified sound input signal from an external driving
device (not shown) is inputted to the piezoelectric vibrator 7 through the lead terminals 8 and 9
and vibrated so as to breathe the whole of the spherical vibrator 5 as if it were It has a basic
structure that vibrates to generate sound.
[0016]
The spherical vibrator 5 is hollow and has a size and a material corresponding to a beach ball
having a diameter of 20 to 50 cm.
[0017]
The piezoelectric vibrator 7 may be a bimorph type or a monomorph type, but a large bimorph
type is preferable in order to obtain a sufficient sound pressure.
[0018]
In the prototype of the inventor of the present embodiment, piezoelectric ceramics 12 and 13
(PZT) having a diameter of about 50 mm are attached to both surfaces of a metal diaphragm 11
having a diameter of about 60 mm as the piezoelectric vibrator 7 with silver paste or the like.
The bimorph type of the structure which formed the electrode on the surface is used.
Instead of piezoelectric ceramics, polyvinylidene fluoride (PVDF) having a piezoelectric effect
may be used.
[0019]
In the spherical speaker 20 as described above, the vibration of the piezoelectric vibrator 7 is
directly conducted to the whole spherical vibrator 5 which is expanded by the internal pressure
and formed into a spherical shape with an appropriate tension, so that the directivity is almost
zero. It does not appear, and it is made very lightweight with a frameless structure.
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Therefore, although it may be mounted on a support as a usage form, as shown in FIG. 1, it can
be used by being sucked to the suction cup 2 and suspended from a ceiling. In addition, since the
spherical vibrator 5 itself is like a beach ball, the volume can be reduced by removing the gas
inside and deflating, and it is easy to carry and store.
[0020]
Next, in the spherical speaker 20 shown in (a) and (b) of FIG. 2, in addition to the abovedescribed structure, a donut-shaped foamed resin is provided around the piezoelectric vibrator 7
on the inner surface side of the spherical vibrator 5. A reinforcing plate 15 is attached by an
adhesive, and a doughnut-shaped synthetic resin sheet 16 is similarly attached by an adhesive
around the piezoelectric vibrator 7 on the surface side of the spherical vibrator 5; It has become.
And a weight 17 attached to the center of the piezoelectric vibrator 7.
[0021]
The reinforcing plate 15 has a division vibration control action, and an effect of improving the
sound pressure in the low / medium range can be obtained. For example, the expanded
polystyrene foam, which is a high magnification foam material, has an outer diameter of 130
mm, an inner diameter of 70 mm, and a thickness of about 10 mm. Processed into a donut shape.
[0022]
The synthetic resin sheet 16 is for reducing the metallic sound peculiar to the piezoelectric
vibrator, and is, for example, a PET foam sheet having an outer diameter of 130 mm, an inner
diameter of 70 mm, and a thickness of about 0.3 to 2 mm. is there.
[0023]
The weight 17 is about 10 to 50 g (20 g in the prototype of this embodiment is the best mode).
And the like, and has the effect of absorbing a sudden change in sound pressure in the high
range to obtain a stable flat sound pressure characteristic.
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[0024]
FIG. 3 is a sound pressure-frequency characteristic diagram at a drive input voltage of 5 Vrms / 1
m of the spherical speaker 20 (diameter 400 mm) of the above structure.
Although there is a singular point near 180 Hz, a relatively high sound pressure is obtained in
the mid-low range, and a relatively stable sound pressure is obtained in the high range above 2
KHz. As described above, the present spherical speaker 20 is a speaker that is extremely
lightweight and is compatible with a full range that is excellent in the mid-low range
characteristics.
[0025]
Next, in addition to the configuration of the above-mentioned spherical speaker 20, in the case of
the spherical speaker 30 shown in FIG. 4, a transparent to translucent so-called skeleton
spherical vibrator, in particular, in which the spherical vibrator 21 is light transmissive. The light
emitting diodes 23 (three in FIG. 4) that emit light corresponding to the drive signal of the
piezoelectric vibrator 7 are disposed inside the spherical vibrator 21, and The pattern 25 on the
outer surface or the inner surface, or the ornament 26 (for example, a plastic accessory colored
in the shape of a flower, a bird, a butterfly, etc.) disposed inside the spherical vibrator 21; A
configuration effect can be obtained by a combination of sound and light that the pattern 25 or
the decoration 26 is illuminated to the outside of the skeleton-shaped vibrating body 21 together
with the sound by the diode 23 and the light and the visual synthesis. .
[0026]
If the light emitting diode 23 is attached to the position of the weight 17 as shown in FIG. 4, it is
possible to save time and labor for newly providing the position, and the light source is not
detected somewhere from the outside, which is desirable as a rendering effect. .
In addition, by using an ultraviolet light emitting diode as the light emitting diode 23 and
applying a fluorescent paint to the pattern 25 or the decoration 26 in the dim light, the graphic
pattern 25 or the decoration 26 appears with a fantastic image representation An effect is
obtained.
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[0027]
The drive circuit of the light emitting diode 23 can be realized, for example, by a simple drive
circuit 40 as shown in FIG. 5 separately provided inside or outside the spherical vibrator 21. The
audio input signal S passes through the high pass filter 41 (fc = 100 Hz), the low pass filter 42 (fc
= 30 Hz), the automatic level control amplifier 43, and the detection circuit 44 to turn on the
drive transistor 45 to match the rhythm of the bass and the light emitting diode 23 Drive. In this
point, in the experiment of the inventor of the present invention, it is better to extract the abovementioned signal in the low frequency range and drive the light emitting diode 23 than to simply
input the audio input signal S for driving the speaker to the drive transistor 45 as it is. It was
found that the changes in rhythm and light were more consistent, and the best effects were
obtained.
[0028]
As described above in detail, the spherical speakers 20 and 30 according to the present invention
have extremely simple and low-cost configurations, and various features such as light weight,
novel appearance, ease of transportation and storage, etc. It is a full range spherical speaker that
can be applied to an application.
[0029]
The spherical speaker according to the present invention has the following excellent effects.
(1) It is a spherical speaker of a breathing sphere which uses as a drive source a piezoelectric
vibrator which is excellent in the acoustic characteristic of the mid-low range. (2) It is lightweight
and easy to suspend from the ceiling, and it can be made smaller by removing the gas contained
therein, so it can be easily transported and stored. (3) It has a visual effect such that the pattern
and ornaments of the spherical vibrator light up according to the sound. (4) Low cost.
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