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DESCRIPTION JP2014192744

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DESCRIPTION JP2014192744
Abstract: To provide a piezoelectric speaker in which a conduction failure does not easily occur
even if sound waves are repeatedly generated. A piezoelectric speaker (1) includes a metal
diaphragm (2), a plate-like piezoelectric body (31), a partial electrode (41a), and lead wires (61,
63). The piezoelectric body 31 is provided on the surface of the diaphragm 2. The partial
electrode 41 a is formed on the surface of the piezoelectric body 31 opposite to the diaphragm 2.
The lead wire 61 is soldered to the partial electrode 41 a. The lead wire 63 is soldered to the
diaphragm 2. The solder 51 for joining the lead wire 61 to the partial electrode 41a is provided
in contact with the outer edge of the partial electrode 41a. The solder 53 for joining the lead wire
63 to the diaphragm 2 is provided in contact with the boundary between the piezoelectric body
31 and the diaphragm 2. [Selected figure] Figure 1
Piezoelectric speaker
[0001]
The present invention relates to a piezoelectric speaker.
[0002]
Conventionally, there has been a siren that issues an alarm sound to the surroundings to notify
an abnormality by using a piezoelectric plate that vibrates when a voltage is applied (see, for
example, Patent Document 1).
[0003]
JP, 2011-53561, A
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1
[0004]
The piezoelectric speaker periodically applies a voltage to the piezoelectric plate to vibrate the
piezoelectric plate, and generates a sound wave by vibrating a diaphragm provided on the
surface of the piezoelectric plate.
Lead wires for applying a voltage to the piezoelectric plate are joined to the electrodes of the
piezoelectric plate by soldering.
[0005]
When the piezoelectric speaker repeatedly generates sound waves, the electrodes of the
piezoelectric body peel off along the outer periphery of the solder, causing conduction failure
between the lead wire and the electrodes of the piezoelectric body, or conduction to the core wire
of the lead wire out of the solder There was a problem that a failure might occur.
[0006]
The present invention has been made in view of the above problems, and an object of the present
invention is to provide a piezoelectric speaker in which a conduction failure does not easily occur
even if sound waves are repeatedly generated.
[0007]
The present invention is a piezoelectric speaker including a metal diaphragm, a plate-like
piezoelectric body, a partial electrode, and a lead wire.
The plate-like piezoelectric body is provided on the surface of the diaphragm.
The partial electrode is formed on the surface of the piezoelectric body opposite to the
diaphragm.
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2
The lead wire is soldered to the partial electrode and the diaphragm, respectively.
Solder for bonding the lead wire to the partial electrode is provided in contact with the outer
edge of the partial electrode. The solder for bonding the lead wire to the diaphragm is
characterized in that it is provided in contact with the boundary between the piezoelectric body
and the diaphragm.
[0008]
In the present invention, the piezoelectric body is also preferably formed of a ceramic material.
[0009]
In the present invention, it is also preferable that at least a part of the solder and a part of the
core wire of the lead wire that has come out of the solder be covered with a rubber-based
adhesive.
[0010]
According to the present invention, the lead wire connected to the partial electrode is soldered at
a position close to the vibration node of the piezoelectric body, ie, a position in contact with the
outer edge of the partial electrode of the piezoelectric body. The stress applied to the partial
electrode of the piezoelectric body can be further reduced.
By reducing the stress applied to the partial electrodes of the piezoelectric along the outer
periphery of the solder, the partial electrodes of the piezoelectric are less likely to peel off along
the outer periphery of the solder, so conduction failure between the lead wire and the partial
electrodes of the piezoelectric Is less likely to occur.
Further, the lead wire connected to the diaphragm is soldered at a position close to the node of
vibration of the piezoelectric body, that is, at a position in contact with the boundary portion
between the piezoelectric body and the diaphragm. Vibration applied to the core wire of the core
wire becomes smaller, and conduction failure of the core wire of the lead wire is less likely to
occur.
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3
[0011]
(A) is a front view of the piezoelectric speaker in this embodiment, (b) is a principal part enlarged
view. FIG. (A) is a right side view of the above, and (b) is a cross-sectional view of a P part.
[0012]
An embodiment in which the technical concept of the present invention is applied to a bimorph
piezoelectric speaker will be described with reference to FIGS. 1 to 3.
[0013]
The piezoelectric speaker 1 includes a metal diaphragm 2, plate-like piezoelectric members 31
and 32, partial electrodes 41 a and 42 a, and lead wires 61 to 63.
[0014]
The diaphragm 2 is formed of a disk-shaped metal plate.
In addition, the shape of the diaphragm 2 is not limited to a disk shape, It may be a suitable
shape formed in the plate shape which can be vibrated.
[0015]
The piezoelectric bodies 31 and 32 are formed of a disc-shaped ceramic material polarized in the
thickness direction, and are adhered and fixed to both surfaces of the diaphragm 2.
The piezoelectric members 31 and 32 are piezoelectric elements that expand and contract in the
radial direction according to the polarity of a voltage when an alternating voltage is applied.
[0016]
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The piezoelectric body 31 is formed in a disk shape having a radius smaller than the radius of the
diaphragm 2. The shape of the piezoelectric body 31 is not limited to the disk shape, and may be
a suitable shape formed in a plate shape that can be vibrated.
[0017]
The partial electrode 41a is formed on one surface of the piezoelectric body 31, and the
electrode 41b is formed on the other surface. The electrode 41 b is formed by baking silver on
substantially the entire surface of the piezoelectric body 31. The electrode 41 b is bonded to the
diaphragm 2 by an adhesive 81 having conductivity. The partial electrode 41 a is formed by
baking silver in a circle having a radius slightly smaller than the radius of the piezoelectric body
31 on the surface of the piezoelectric body 31 opposite to the diaphragm 2. The partial
electrodes 41 a and the electrodes 41 b are not limited to the formation of baked silver on the
surface of the piezoelectric body 31, and may be formed of an appropriate material capable of
applying a voltage to the piezoelectric body 31. Further, the shapes of the partial electrode 41 a
and the electrode 41 b are not limited to the circular shape, and may be an appropriate shape
that can be formed on the surface of the piezoelectric body 31. The piezoelectric body 32 is
formed in a disk shape having a radius smaller than the radius of the diaphragm 2. The partial
electrode 42a is formed on one surface of the piezoelectric body 32, and the electrode 42b is
formed on the other surface. In addition, since the piezoelectric body 32 has the same
configuration as the piezoelectric body 31, the detailed description will be omitted.
[0018]
The lead wire 61 is made of a covered electric wire in which a core 61a is covered with a cover
61b, and one end of the core 61a exposed by peeling the cover 61b at the tip is soldered to the
partial electrode 41a with a solder 51. The other end of the core wire 61a is connected to a
control circuit (not shown) described later. The lead wire 62 is made of a covered electric wire in
which a core 62a is covered with a coating 62b, and one end of the core 62a exposed by peeling
the coating 62b at the tip is soldered to the partial electrode 42a with a solder 52. The other end
of the core wire 62a is connected to the control circuit. The lead wire 63 is a covered electric
wire in which a core 63a is covered with a coating 63b, and one end of the core 63a exposed by
peeling off the coating 63b at the tip is soldered to the diaphragm 2 with a solder 53. The other
end of the core wire 63a is connected to the control circuit. In the present embodiment, the
application amount of the solders 51 to 53 is about 4 to 14 mg, respectively. However, the
application amounts of the solders 51 to 53 may be appropriate.
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[0019]
The control circuit is a circuit that applies a voltage between the partial electrodes 41a and 41b
and between the partial electrodes 42a and 42b in order to vibrate the diaphragm 2. The control
circuit applies an AC voltage of the same phase between the core wires 61a and 63a and
between the core wires 62a and 63a at a desired timing.
[0020]
Here, an operation in which the piezoelectric speaker 1 generates a sound wave will be
described.
[0021]
When the control circuit applies voltages of the same polarity between the partial electrodes 41a
and 41b and between the partial electrodes 42a and 42b, one of the piezoelectric members 31
and 32 contracts in the radial direction, and the other expands in the radial direction. Therefore,
the diaphragm 2 is curved so as to be convex on the side of the expanded piezoelectric body.
When the control circuit reverses the polarity of the voltage applied between the partial
electrodes 41a and 41b and between the partial electrodes 42a and 42b, the diaphragm 2 is
curved to be convex on the opposite side. The control circuit causes the diaphragm 2 to vibrate
to generate sound waves by alternating the polarity of the voltage applied between the partial
electrodes 41a and 41b and between the partial electrodes 42a and 42b at a predetermined
frequency.
[0022]
By the way, when the diaphragm 2 vibrates, the piezoelectric body 31 expands and contracts in
the radial direction, but the solder 51 soldered to the partial electrode 41 a does not expand and
contract in the radial direction. It will be stressed. When the diaphragm 2 vibrates, a node of
vibration is formed at the boundary between the outer edge of the piezoelectric body 31 and the
diaphragm 2. Therefore, the amplitude of the piezoelectric body 31 is closer to the boundary
between the outer edge of the piezoelectric 31 and the diaphragm 2. Becomes smaller. In the
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present embodiment, the solder 51 is provided at a position in contact with the outer edge of the
partial electrode 41 a. The position where the solder 51 is provided is a position where the
amount of expansion and contraction of the piezoelectric body 31 is small, that is, a position
where the amplitude of the piezoelectric body 31 is small. Therefore, stress applied to the partial
electrode 41 a along the outer periphery of the solder 51 is smaller than when the solder 51 is
provided at a position separated from the boundary between the outer edge of the piezoelectric
body 31 and the diaphragm 2. As a result, the partial electrode 41a is less likely to peel off along
the outer periphery of the solder 51, and a conduction failure between the lead wire 61 and the
partial electrode 41a is less likely to occur. Further, the same applies to the partial electrode 42a.
By providing the solder 52 in contact with the outer edge of the partial electrode 42a, stress
applied to the partial electrode 42a along the outer periphery of the solder 52 is reduced, and
the partial electrode 42a is solder 52 It becomes difficult to peel off along the outer
circumference of
[0023]
Similarly, by providing the solder 53 at a position close to the node of vibration of the
piezoelectric body 31, that is, at a position in contact with the boundary between the
piezoelectric body 31 and the diaphragm 2, the vibration applied to the core wire 63a coming
out of the solder 53 It becomes smaller.
[0024]
When the piezoelectric speaker 1 repeatedly generates an acoustic wave, stress is applied to the
core wire 63 a between the portion in the solder 53 and the portion out of the solder 53.
The rubber-based adhesive 73 covers a part of the solder 53, a part of the core wire 63a that has
come out of the solder 53, and an end of the coating 63b. The rubber-based adhesive 73 is an
adhesive made of an appropriate rubber-based material that is cured after application. The
rubber-based adhesive 73 covers a part of the solder 53 and a part of the core 63a. Therefore, in
the core 63a, the part in the solder 53 and the part out of the solder 53 are fixed. . Therefore,
even if the diaphragm 2 vibrates, the conduction defect is unlikely to occur between the portion
in the solder 53 and the portion out of the solder 53 in the core wire 63a. The description of the
rubber-based adhesives 71 and 72 is the same as that of the rubber-based adhesive 73, and thus
the description thereof is omitted. Moreover, although the application amount of the rubberbased adhesive 73 in the present embodiment is about 4 ± 1 mg, the rubber-based adhesive 73
may be an appropriate application amount. Furthermore, in the present embodiment, the rubberbased adhesive 73 covers a part of the solder 53, a part of the core wire 63a, and the end of the
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7
coating 63b, but the end of the coating 63b is rubber-based adhesive 73 It does not have to be
covered with
[0025]
As described above, the present invention is the piezoelectric speaker 1 including the metal
diaphragm 2, the plate-like piezoelectric members 31 and 32, the partial electrodes 41a and 42a,
and the lead wires 61 to 63. The plate-like piezoelectric members 31 and 32 are provided on the
surface of the diaphragm 2. The partial electrode 41 a is formed on the surface of the
piezoelectric body 31 opposite to the diaphragm 2, and the partial electrode 42 a is formed on
the surface of the piezoelectric body 32 opposite to the diaphragm 2. The lead wire 61 is
soldered to the partial electrode 41a, and the lead wire 62 is soldered to the partial electrode
42a. The lead wire 63 is soldered to the diaphragm 2. The solder 51 for joining the lead wire 61
to the partial electrode 41a is provided in contact with the outer edge of the partial electrode
41a, and the solder 52 for joining the lead wire 62 to the partial electrode 42a is provided in
contact with the outer edge of the partial electrode 42a Be The solder 53 for joining the lead
wire 63 to the diaphragm 2 is provided in contact with the boundary between the piezoelectric
body 31 and the diaphragm 2.
[0026]
When the piezoelectric body 31 vibrates, the boundary between the outer edge of the
piezoelectric body 31 and the diaphragm 2 becomes a node of the vibration. By providing the
solder 51 at a position close to a node of vibration of the piezoelectric body 31, ie, a position in
contact with the outer edge of the partial electrode 41a, stress applied to the partial electrode
41a along the outer periphery of the solder 51 can be further reduced. As a result, the partial
electrode 41a is less likely to peel off along the outer periphery of the solder 51, and a
conduction failure between the lead wire 61 and the partial electrode 41a is less likely to occur.
Similarly, providing the solder 52 at a position in contact with the outer edge of the partial
electrode 42a makes it difficult for the partial electrode 42a to peel off along the outer periphery
of the solder 52, so that conduction failure between the lead wire 62 and the partial electrode
42a is less likely to occur. . Further, by providing the solder 53 at a position close to a node of
the vibration of the piezoelectric body 31, that is, at a position in contact with the boundary
between the piezoelectric body 31 and the diaphragm 2, the vibration applied to the core wire
63a coming out of the solder is smaller. As a result, conduction defects of the lead wires 63 are
less likely to occur. Although the bimorph piezoelectric speaker 1 has been described as an
example in the present embodiment, it may be a unimorph piezoelectric speaker in which a
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8
piezoelectric body is provided only on one side of the diaphragm 2.
[0027]
In the present embodiment, the piezoelectric bodies 31 and 32 are formed of a ceramic material.
[0028]
The piezoelectric body 31 formed of a ceramic material has a larger amount of expansion and
contraction when a voltage is applied as compared with the case of being formed of another
material, and therefore, along the outer periphery of the solder 51 when the piezoelectric body
31 vibrates. Therefore, the stress applied to the partial electrode 41a becomes larger.
By providing the solder 51 at a position in contact with the outer edge of the partial electrode
41a, the stress applied to the partial electrode 41a along the outer periphery of the solder 51 can
be further reduced, so that conduction failure between the lead wire 61 and the partial electrode
41a It becomes difficult to happen. Similarly, by providing the solder 52 at a position in contact
with the outer edge of the partial electrode 42a, conduction failure between the lead wire 62 and
the partial electrode 42a is less likely to occur. Therefore, it is possible to realize a piezoelectric
speaker having a larger sound pressure while suppressing conduction failure.
[0029]
In the present embodiment, a part of the solder 53 and a part of the core wire 63 a that has come
out of the solder 53 are covered with the rubber-based adhesive 73. Similarly, a part of the
solder 51 and a part of the core wire 61a that has come out of the solder 51 are covered with the
rubber adhesive 71, and a part of the solder 52 and the core wire 62a that has come out of the
solder 52 The rubber adhesive 72 covers a portion of the
[0030]
In the core wire 63a, by fixing the part contained in the solder 53 and the part drawn out from
the solder 53 with the rubber-based adhesive 73, a conduction failure of the lead wire 63 hardly
occurs. Similarly, the conductive failure of the lead wire 61 is less likely to occur by the rubber-
14-04-2019
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based adhesive 71, and the conductive failure of the lead wire 62 is less likely to occur by the
rubber-based adhesive 72.
[0031]
REFERENCE SIGNS LIST 1 piezoelectric speaker 2 diaphragm 31, 32 piezoelectric body 41 a, 42
a partial electrode 41 b, 42 b electrode 51 to 53 solder 61 to 63 lead wire 61 a to 63 a core wire
61 b to 63 b coating 71 to 73 rubber-based adhesive
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