JPH11239396

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DESCRIPTION JPH11239396
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
loudspeaker, and more particularly to a loudspeaker for converting an electrical signal into a
sound wave and emitting it.
[0002]
2. Description of the Related Art Conventionally, there are cone type speakers using a cone, horn
type speakers using a horn, and flat type speakers using a flat plate-like piezoelectric element.
[0003]
However, all the conventional loudspeakers have directivity in the direction parallel to the
installation or floor surface, and all directions (360 ° in the direction parallel to the installation
or floor surface). ) Can not emit sound waves.
[0004]
Therefore, the main object of the present invention is to provide a loudspeaker that is
omnidirectional in a direction parallel to the installation surface.
[0005]
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SUMMARY OF THE INVENTION A loudspeaker according to the present invention includes a
hemispherical vibrating body and a driving means for vibrating the vibrating body, and the inner
surface side of the vibrating body is from the inner surface of the vibrating body. The speaker is
a speaker in which phase shifting means of the emitted sound wave is disposed, and the sound
wave emitted from the outer surface of the vibration body and the sound wave emitted from the
inner surface of the vibration body are emitted to the outside of the vibration body with
substantially the same phase.
A loudspeaker according to the present invention includes a vibrator comprising a hemispherical
piezoelectric body, and an electrode as a drive means provided on the inner and outer surfaces of
the vibrator for vibrating the vibrator. The phase shifting means of the sound wave radiated from
the inner surface of the vibrating body is disposed on the inner surface side of the vibrating
body, and the sound wave radiated from the outer surface of the vibrating body and the sound
wave radiated from the inner surface of the vibrating body have substantially the same phase
Radiated to the outside of the speaker.
In the loudspeaker according to the present invention, a horn may be provided on the inner
surface side of the vibrating body.
In the loudspeaker according to the present invention, the phase shift means includes a hole for
propagating the sound wave emitted from the inner surface of the vibrator formed in the horn to
the outside. In the loudspeaker according to the present invention, the phase shifting means
includes a cavity between the inner surface of the vibrating body and the horn. In the
loudspeaker according to the invention, the phase shifting means comprises a passage between
the horn and the mounting surface. In this case, the passage is formed, for example, substantially
in all directions in a direction parallel to the installation surface. Furthermore, a loudspeaker
according to the present invention is a loudspeaker comprising: a vibrating body made of a
hemispherical piezoelectric body; and electrodes as driving means provided on the inner and
outer surfaces of the vibrating body to vibrate the vibrating body. is there. The speaker may also
be provided with a horn on the inner side of the vibrating body.
[0006]
In the loudspeaker according to the present invention, when an electric signal is inputted, the
vibrator vibrates by the drive means, and sound waves are emitted from the curved outer surface
of the vibrator, and the cavity, horn from the curved inner surface of the vibrator. Sound waves
are emitted through the holes and passages of the
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[0007]
In this case, the sound waves emitted from the curved outer surface of the vibrating body are
omnidirectional in all directions in the direction parallel to the installation surface because the
vibrating body is formed in a hemispherical shape.
In addition, sound waves emitted from the curved inner surface of the transducer through the
cavity and the holes and passages of the horn are radiated in all directions since the passages are
formed substantially in all directions in the direction parallel to the installation surface. It
becomes omnidirectional. Therefore, this speaker is omnidirectional in the direction parallel to
the installation surface.
[0008]
According to the present invention, it is possible to obtain a speaker which is nondirectional in
the direction parallel to the installation surface.
[0009]
The above object, other objects, features and advantages of the present invention will become
more apparent from the detailed description of the following embodiments of the present
invention made with reference to the drawings.
[0010]
DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing an
example of an embodiment of the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a
cross-sectional view taken along line III-III in FIG.
The speaker 10 shown in FIGS. 1 to 3 includes a hemispherical vibrator 12.
[0011]
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The vibrator 12 includes a hemispherical vibrator 14 made of a piezoelectric material such as
ceramic.
Electrodes 16a and 16b as drive means for vibrating the vibrating body 14 are formed on the
curved inner and outer surfaces of the vibrating body 14, respectively. An input terminal 20 is
connected to these electrodes 16a and 16b via leads 18a and 18b. The vibrating body 14 is
polarized, for example, from the inner surface to the outer surface in the thickness direction.
[0012]
The vibrator 12 is fixed to a horn 22 made of, for example, aluminum. The horn 22 has a
hemispherical projecting portion 24 corresponding to the shape of the vibrator 12, and a flange
portion 26 is formed around the projecting portion 24. Also, a groove 27 is formed between the
projecting portion 24 and the flange portion 26. Furthermore, a hole (sound path) 28 for
transmitting a sound wave is formed at the center of the projecting portion 24 so as to gradually
spread from the projecting side of the projecting portion 24 to the opposite side. Then, the
vibrator 12 is fixed to the three spacers 29 in the groove 27 so that the vibrator 12 covers the
projecting portion 24 of the horn 22. In this case, a cavity 30 for vibrating the vibrator 12 is
formed between the vibrator 12 and the horn 22 so as to communicate with the hole 28. The
lead wire 18 a is pulled out from the inside to the outside of the vibrator 12 through the groove
27.
[0013]
One end of three prismatic columns 32 made of, for example, aluminum is fixed to the flange
portion 26 of the horn 22 with screws 34, respectively. These columns 32 are for floating the
widest opening of the hole 28 of the horn 22 from the installation surface or floor surface. By
means of these columns 32, a passage 36 for propagating the sound wave is formed substantially
in all directions in a direction parallel to the installation surface or floor surface so as to lead to
the hole 28 of the horn 22.
[0014]
In order to prevent the sound waves radiated from the curved outer surface of the vibrator 12
and the sound waves radiated from the curved inner surface of the vibrator 12 through the
cavity 30, the hole 28 and the passage 36 from being canceled, The cavity 30, the hole 28 and
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the passage 36 are formed such that the sound waves have substantially the same phase in the
direction parallel to the installation or floor surface of the speaker 10.
[0015]
In this speaker 10, when an electric signal is input to the input terminal 20, the vibrator 12
vibrates and a sound wave is emitted from the curved outer surface of the vibrator 12, and the
cavity 30 and the hole from the curved inner surface of the vibrator 12 Sound waves are emitted
through 28 and the passage 36.
[0016]
In this case, the sound waves radiated from the curved outer surface of the vibrator 12 are in all
directions in the direction parallel to the installation surface or the floor surface because the
vibrator 12 to the vibrator 14 are formed in a hemispherical shape. It is emitted and becomes
omnidirectional.
Also, since the sound waves emitted from the curved inner surface of the vibrator 12 through the
cavity 30, the hole 28 and the passage 36 are parallel to the installation surface or the floor
surface, the passage 36 is formed in almost all directions. It is emitted omnidirectionally and
becomes omnidirectional.
Therefore, the speaker 10 is nondirectional in the direction parallel to the installation surface or
the floor surface.
[0017]
Further, the phase difference between the sound wave emitted from the curved outer surface of
the transducer 12 and the sound wave emitted from the curved inner surface of the transducer
12 is 180 °. However, the acoustic waves are brought to substantially the same phase in a
direction parallel to the installation or floor surface by the cavities 30, the holes 28 and the
passages 36 which are also used as phase shifting means. Therefore, in the speaker 10, in the
direction parallel to the installation surface or the floor surface, the sound waves are not
canceled but superimposed in reverse, and the sound pressure is high.
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[0018]
Furthermore, in the speaker 10, the sound pressure of the sound wave radiated from the curved
inner surface of the vibrator 12 is increased by the hole 28 of the horn 22, so the conversion
efficiency from the electric signal to the sound wave is good.
[0019]
Further, in this speaker 10, the size of the passage 36 leading to the opening of the hole 28 of
the horn 22 is changed by changing the length of the support 32, so that the cutoff frequency of
the horn 22 can be adjusted. Characteristics can be adjusted.
[0020]
FIG. 4 is a perspective view showing another example of the embodiment of the present
invention.
In the speaker shown in FIG. 4, compared to the speaker shown in FIGS. 1 to 3, three columns 32
are formed to extend upward, respectively, and a reflection member 38 is disposed above the
curved outer surface of the vibrator 12, The reflecting members 38 are fixed to the upper ends of
the three columns 32 with screws 34 respectively.
The reflecting member 38 is for reflecting the sound wave emitted upward from the curved outer
surface of the vibrator 12 in a direction parallel to the installation surface or the floor surface.
[0021]
In the loudspeaker shown in FIG. 4, as in the loudspeakers shown in FIGS. 1 to 3, there is no
directivity in the direction parallel to the installation surface or floor, the sound pressure is high
in the direction parallel to the installation or floor, The conversion efficiency from signal to sound
wave is good, and cut-off frequency and frequency characteristics can be adjusted.
[0022]
Furthermore, in the loudspeaker shown in FIG. 4, the sound wave emitted upward from the
curved outer surface of the vibrator 12 in the direction parallel to the installation surface or floor
surface by the reflecting member 38 as compared to the loudspeaker shown in FIGS. 1 to 3. Since
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the light is reflected, the sound pressure increases in the direction parallel to the installation
surface or floor surface.
[0023]
FIG. 5 is a cross-sectional view showing still another example of the embodiment of the present
invention.
The speaker 10 shown in FIG. 5 includes two sets of vibrators 12 and a horn 22.
The vibrator 12 and the horn 22 are similar to the vibrator and the horn used for each speaker
shown in FIGS. 1 to 4 and are similarly fixed.
[0024]
In addition, the two sets of vibrators 12 and horns 22 are, for example, three columns 32 of
triangular prisms in which the two horns 22 are made of, for example, aluminum so that the
curved outer surfaces of the two vibrators 12 are spaced apart. Connected by In this case, each
post 32 is secured to the flange portion 26 of the two horns 22 with screws 34. Furthermore, a
disk-shaped top plate 40 made of, for example, aluminum as a baffle is adhered to the upper end
surfaces of the three columns 32.
[0025]
And between the lower horn 22 and the installation surface or floor surface, a passage 36 for
propagating the sound wave is formed in almost all directions in a direction parallel to the
installation surface or floor surface. Similarly, another passage 36 for propagating the sound
wave is formed between the upper horn 22 and the top plate 40 in almost all directions in a
direction parallel to the installation surface or the floor surface. Furthermore, another passage 37
for propagating the sound wave is formed between the two horns 22 substantially in all
directions in a direction parallel to the installation or floor surface.
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[0026]
The sound waves emitted from the curved outer surfaces of the two transducers 12 through the
passage 37 and the sound waves emitted from the curved inner surfaces of the two transducers
12 through the cavity 30, the hole 28 and the passage 36 are The cavities 30, the holes 28, the
passages 36 and 37 are formed such that their sound waves have substantially the same phase in
the direction parallel to the mounting surface or floor surface of the speaker 10 so as not to be
offset.
[0027]
In the speaker 10 shown in FIG. 5, when an electrical signal is input to the two input terminals
20, the two vibrators 12 vibrate, and sound waves are emitted from the curved outer surfaces of
the two vibrators 12 through the passage 37. In addition, sound waves are emitted from the
curved inner surfaces of the two transducers 12 through the cavity 30, the hole 28 and the
passage 36.
[0028]
In this case, the sound waves emitted from the curved outer surfaces of the two transducers 12
through the passage 37 are formed in almost all directions in the direction parallel to the
installation surface or the floor surface, so that all directions are obtained. It is emitted over the
whole and becomes omnidirectional.
Also, the sound waves emitted from the curved inner surfaces of the two transducers 12 through
the cavity 30, the hole 28 and the passage 36 are formed in substantially all directions in the
passage 36 in the direction parallel to the installation or floor surface. Because it is emitted in all
directions, it becomes omnidirectional.
Therefore, the speaker 10 shown in FIG. 5 is nondirectional in the direction parallel to the
installation surface or the floor surface.
[0029]
Further, the phase difference between the sound wave emitted from the curved outer surfaces of
the two transducers 12 and the sound wave emitted from the curved inner surfaces of the two
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transducers 12 is 180 °. However, the acoustic waves are brought to approximately the same
phase in a direction parallel to the installation or floor surface by means of the cavities 30, holes
28, passages 36 and 37 which are also used as phase shifting means. Therefore, in the speaker
10 shown in FIG. 5, in the direction parallel to the installation surface or the floor surface, the
sound waves are not canceled but superimposed in reverse, and the sound pressure is high.
[0030]
Furthermore, in the loudspeaker shown in FIG. 5, since the sound waves are emitted from the two
transducers 12 as compared with the respective loudspeakers shown in FIGS. 1 to 4, the sound
pressure is further increased.
[0031]
Further, in the speaker 10 shown in FIG. 5, the sound pressure of the sound wave radiated from
the curved inner surface of the two vibrators 12 is increased by the holes 28 of the two horns
22, so the conversion efficiency from electric signal to sound wave is good. .
[0032]
Furthermore, in the speaker 10 shown in FIG. 5, since the size of the passage 36 leading to the
holes 28 of the two horns 22 and the size of the passage 37 change by changing the length of
the support 32, the two horns 22 are cut off The frequency can be adjusted individually, and the
overall frequency characteristic can be improved.
[0033]
Although the groove 27 and the spacer 29 are formed to prevent the electrodes 16a and 16b
from being shorted by the lead wire 18a in the embodiment of the invention described above,
instead of forming the groove 27 and the spacer 29, As shown in FIG. 6, at the end of the
vibrating body 14 of the vibrator 12, a removal portion 17 may be formed in which a part of the
electrode 16b is removed.
In this case, in order to prevent the electrodes 16a and 16b from being short-circuited by the
lead wire 18a, the lead wire 18a may be sandwiched between the vibrator 14 and the horn 22 in
the portion where the removal portion 17 is formed.
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[0034]
Further, in the above-described embodiment of the invention, a vibrator in which electrodes are
formed on the curved inner and outer surfaces of a vibrating body made of a piezoelectric
material is used. Instead of such a vibrator, for example, metal, ceramic Alternatively, a vibrator
may be used in which a piezoelectric element as driving means for vibrating the vibrating body is
bonded to a part of a hemispherical vibrating body made of synthetic resin.
[0035]
Furthermore, although the horn, the support and the top plate are formed of aluminum in the
embodiment of the above-mentioned invention, the horn, the support and the top plate are
formed of other metals, wood, synthetic resin, ceramic, glass and the like It is also good.
[0036]
In addition, although three prismatic pillars are used in the above-described embodiment of the
present invention, the shape of the pillars may be arbitrarily changed to a cylindrical shape, a
quadrangular prism, or another pillar. Also, the number of supports is not limited to three, and
may be one, two or four or more.
[0037]
Furthermore, an acoustic equalizer may be provided on the central axis of the hole 28 in order to
increase the accuracy of the aperture ratio of the hole 28 of the horn 22.
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