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JPH09224299

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JPH09224299
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
piezoelectric speaker driven by electromagnetic induction used in a composite speaker.
[0002]
2. Description of the Related Art As a piezoelectric type speaker driven by electromagnetic
induction used in a conventional composite type speaker, a diaphragm is a combination of a cone
type and a dome type, and the outer periphery of a dome portion and a piezoelectric element are
joined. Have been announced so far. These conventional examples will be described based on FIG.
FIG. 6 shows a built-in state of the composite speaker. Reference numeral 15 denotes a
piezoelectric speaker driven by electromagnetic induction used as a tweeter of the composite
speaker, and reference numeral 20 denotes a woofer of the composite speaker. The tweeter 15
comprises a diaphragm 19 having a combination of a cone shape and a dome shape attached to
the frame 6, an induction coil 7 for electromagnetic coupling disposed below the frame 6, and an
outer periphery of a dome portion of the diaphragm 19. It comprises the piezoelectric element 5
joined.
[0003]
The woofer 20 is composed of a vibration system including a diaphragm 21, a voice coil 23, and
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a damper 24, a magnetic circuit including a magnet 25, a top plate 26, and a center pole 27, a
frame 22, and the like. The tweeter 15 is mounted on the center pole 27 of the woofer 20, and
the induction coil 7 is fixed in the vicinity of the voice coil 23. An induced voltage is generated in
the induction coil 7 by the voltage generated in the voice coil 23 by the voice current, and this
induced voltage is applied to the piezoelectric element 5.
[0004]
However, although the diaphragm of a piezoelectric speaker driven by electromagnetic induction
used in a conventional composite speaker is used to enhance the exchange efficiency of the
piezoelectric element, the reproduction frequency is used. There is a problem that the band is
narrow and the frequency characteristics are not flat.
[0005]
The present invention has been made in view of these points, and it is an object of the present
invention to provide a piezoelectric speaker which can obtain flat frequency characteristics and
efficiently reproduce a wide band.
[0006]
SUMMARY OF THE INVENTION In the piezoelectric speaker according to the present invention,
therefore, the diaphragm is formed into a rectangular shape consisting of a plurality of
continuous semi-cylindrical surfaces in parallel, in order to eliminate the drawbacks of the prior
art.
In addition, the piezoelectric element is supported on the diaphragm by line or point bonding on
the concave portion which is the boundary of the semi-cylindrical surface of the diaphragm.
By this, in the vicinity of the junction of the diaphragm and the piezoelectric element, the rigidity
in the vibration direction is large and the high region resonance frequency becomes high, and the
reproduction frequency band can be broadened. Furthermore, since the diaphragm of this
piezoelectric speaker is rectangular when viewed from the direction of the sound wave, the
vibration area is large when the external dimensions are the same, and therefore the efficiency is
higher than that of a conventional circular diaphragm speaker. In addition, since the diaphragm
has a semi-cylindrical surface shape, the slope angle of the diaphragm continuously changes
from the bonding surface to the piezoelectric element to the top, and the longitudinal direction of
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the semi-cylindrical surface vibrates in the same phase. In the reproduction frequency band,
reproduction can be continuously performed at a higher level than in the case of the above, and
the flat characteristic is obtained.
[0007]
DESCRIPTION OF THE PREFERRED EMBODIMENTS The piezoelectric speaker according to the
present invention comprises a diaphragm 1 attached to a frame 6, an induction coil 7 for
electromagnetic coupling disposed below the frame 6, and a piezoelectric element supported by
the diaphragm 1. In the piezoelectric speaker driven by the electromagnetic induction consisting
of 5, the diaphragm 1 comprises a plurality of parallel semi-cylindrical surfaces 1a, 1b,... Which
are adjacent to each other, and the outer periphery 1s, 1s Are attached to the frame 6, and the
piezoelectric element 5 is supported by the diaphragm 1 by line bonding at the recess 1r at a
position where the plurality of semi-cylindrical surfaces 1a, 1b,... Of the diaphragm 1 are adjacent
to each other. It has a feature in
[0008]
Further, another piezoelectric speaker according to the present invention includes the diaphragm
3 attached to the frame 6, the induction coil 7 for electromagnetic coupling disposed in the lower
part of the frame 6, and the piezoelectric element 5 supported by the diaphragm 3. In the
piezoelectric speaker driven by the electromagnetic induction, the diaphragm 3 is composed of a
plurality of parallel semi-cylindrical surfaces 3a, 3b,... Adjacent to each other, and the outer
periphery 3s, 3s of the frame 6 The piezoelectric element 5 is attached to the diaphragm 3 by
point bonding at the projection 11 on the recess 3r at a position where the plurality of semicylindrical surfaces 3a, 3b... Of the diaphragm 3 are adjacent to each other. It is characterized in
that it is supported.
[0009]
First Embodiment Corresponding to Claim 1 An embodiment of the present invention will be
described based on the drawings.
FIG. 5 is a perspective view of a diaphragm used in the first embodiment of the present invention.
The diaphragm 1 comprises a plurality of parallel semi-cylindrical surfaces 1a and 1b adjacent to
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each other, and is attached to a frame (not shown) at its outer periphery 1s and 1s. Reference
numeral 1 r denotes a recess at a position where the plurality of semicylindrical surfaces 1 a and
1 b of the diaphragm 1 are in contact. As a material of the diaphragm 1, in addition to resin films
such as polyester, polyimide (PI) and PPTA, paper, silk and the like can be considered.
[0010]
FIG. 1A is a plan view and FIG. 1B is a front longitudinal sectional view in the first embodiment of
the present invention. In the figure, the diaphragm 1 is the same as that described in FIG. The
diaphragm 1 is attached to the frame 6 at the outer periphery 1s on both sides. The bimorphtype or unimorph-type piezoelectric element 5 is supported on the diaphragm 1 by wire bonding
at the recess 1 r of the diaphragm 1. The induction voltage in the induction coil 7 for
electromagnetic coupling disposed in the lower part of the frame 6 is applied to the piezoelectric
element 5 through the lead wire 9 from the induction coil 7, the relay terminal 10 and the lead
wire 8. If the lead wire 9 from the induction coil 7 is directly connected to the electrode of the
piezoelectric element 5, the relay terminal 10 and the lead wire 8 become unnecessary.
[0011]
Since this piezoelectric speaker is an electromagnetic coupling type, it can be used as a tweeter of
a coaxial unit because the necessary voltage can be obtained by coaxially arranging the voice coil
of a normal dynamic speaker. In addition, since the speaker is an electromagnetic coupling type,
electrical wiring is unnecessary. Further, by making the diaphragm shape as shown in FIG. 5, the
rigidity in the vibration direction is large near the junction of the diaphragm 1 and the
piezoelectric element 5, the high region resonance frequency becomes high, and the
reproduction frequency band is broadened. it can.
[0012]
FIG. 2 is a frequency characteristic diagram of output levels in the first embodiment of the
present invention and the prior art. In the figure, the vertical axis indicates the output level of the
speaker, and the horizontal axis indicates the frequency. The solid line A is the characteristic in
the first embodiment of the present invention, and the broken line B is the characteristic in the
conventional example. As apparent from the figure, the solid line A enables reproduction at a
higher level than the broken line B, and has a flat characteristic.
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[0013]
Second Embodiment Corresponding to Claim 1 FIG. 3 is a plan view of the second embodiment of
the present invention, and FIG. 3 (b) is a front longitudinal sectional view. The diaphragm 2 is
composed of three half-cylindrical surfaces 2a, 2b and 2c, and forms two recesses 2r. The
diaphragm 2 is attached to the frame 6 at the outer periphery 2s on both sides. The bimorphtype or unimorph-type piezoelectric element 5 is supported on the diaphragm 2 by wire bonding
at two recesses 2 r of the diaphragm 2. In this case, since the semi-cylindrical surface portions
having different dimensions are combined, the vibration modes of the respective portions are
different, and the frequency characteristics thereof are also different. Therefore, the reproduction
band is wider and the frequency characteristics become flat. Further, compared to the first
embodiment, the support of the piezoelectric element 5 on the diaphragm 2 is easy and accurate.
The other components are basically the same as those of the first embodiment, and have the
same functions and effects.
[0014]
Third Embodiment Corresponding to Claim 2 FIG. 4 is a plan view of the third embodiment of the
present invention, and FIG. 4 (b) is a front longitudinal sectional view. The diaphragm 3 is
composed of two half-cylindrical surfaces 3a and 3b, and forms a recess 3r. The diaphragm 3 is
attached to the frame 6 at the outer periphery 3s on both sides. The center of the bimorph-type
or unimorph-type piezoelectric element 5 is supported on the diaphragm 3 by point bonding at a
projection 11 on the recess 3 r of the diaphragm 3. Therefore, the movement of the piezoelectric
element 5 can be transmitted to the diaphragm 3 without loss and the efficiency can be further
enhanced by forming the joint portion of the diaphragm 3 with the piezoelectric element 5 in a
projecting shape, as compared with the first embodiment. Is possible. Further, although not
shown, when two projections 11 are provided on the recess 3 r and the piezoelectric element 5 is
supported at two points, the work is easy and accurate. The other components are basically the
same as those of the first embodiment, and have the same functions and effects.
[0015]
Although the piezoelectric element 5 has been described as having a structure in which the
piezoelectric element 5 is supported only by the vibration plate 1, the piezoelectric element 5 has
a large diameter and / or weight. It is also possible to provide auxiliary means such as bonding a
part of the outer circumference of the frame to the frame 6 or the like.
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[0016]
As described above, in the piezoelectric speaker of the present invention, the diaphragm 1 is
composed of a plurality of parallel semi-cylindrical surfaces 1a and 1b adjacent to each other,
and the outer periphery 1s and 1s thereof. Since the piezoelectric element 5 is attached to the
frame 6 and is supported by the diaphragm 1 by wire bonding at the recess 1 r at a position
where the plurality of semicylindrical surfaces 1 a and 1 b of the diaphragm 1 are adjacent to
each other, The diaphragm 3 comprises a plurality of parallel semi-cylindrical surfaces 3a and 3b
adjacent to each other, and is attached to the frame 6 at its outer periphery 3s and 3s, and the
piezoelectric element 5 is a plurality of diaphragms 3 Is supported by the diaphragm 3 by point
bonding at the projection 11 on the recess 3r at a position where the half-cylindrical surfaces 3a
and 3b are adjacent to each other, flat frequency characteristics are obtained, and broadband is
efficiently achieved. To provide a piezoelectric speaker to reproduce It can be.
[0017]
Brief description of the drawings
[0018]
1 (a) is a plan view, and (b) is a front longitudinal sectional view in the first embodiment of the
present invention.
[0019]
2 is a frequency characteristic diagram of the output level in the first embodiment of the present
invention and the conventional example.
[0020]
In the second embodiment of the present invention (a) is a plan view, (b) is a front longitudinal
sectional view.
[0021]
In the third embodiment of the present invention (a) is a plan view, (b) is a front longitudinal
sectional view.
[0022]
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5 is a perspective view of a diaphragm used in the first embodiment of the present invention.
[0023]
6 is a cross-sectional view showing a built-in state of the composite speaker in the conventional
example.
[0024]
Explanation of sign
[0025]
1, 2, 3 diaphragm 1a, 1b half cylindrical surface 2a, 2b, 2c half cylindrical surface 3a, 3b half
cylindrical surface 1r, 2r, 3r recess 1s, 2s, 3s outer periphery 5 piezoelectric element 6 frame 7
induction coil 8 lead Wire 9 Lead wire 10 Relay terminal 11 Projection 15 Tweeter 19
Diaphragm 20 Woofer 21 Diaphragm 22 Frame 23 Voice coil 24 Damper 25 Magnet 26 Top
plate 27 Center pole
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