JPWO2013042316

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DESCRIPTION JPWO2013042316
In a directional speaker that vibrates a diaphragm provided with a piezoelectric element to
generate a sound wave by superimposing an audible sound signal on a carrier wave in an
ultrasonic wave area, the diaphragm is on the outer periphery of the diaphragm. It is being fixed
to a fixing part via a plurality of provided beams.
Directional speaker
[0001]
The present invention relates to a directional speaker in which audio information is transmitted
only to a specific subject.
[0002]
Conventionally, directional speakers are used to transmit voice information only to specific
subjects.
The directional speaker superimposes an audible sound signal as audio information on a carrier
wave in an ultrasonic wave area and inputs it to the piezoelectric element to vibrate the
diaphragm provided with the piezoelectric element to generate a sound wave. A structural crosssectional view of this directional speaker is shown in FIG.
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[0003]
A piezoelectric element 105 is attached to the diaphragm 103 of the directional speaker 101 as a
vibration source. The vibrating plate 103 has a structure in which the insulating adhesive 111 is
attached to the tip of the electrode 109 fixed to the base 107. Furthermore, the piezoelectric
element 105 is connected to each electrode 109 by a lead wire 113. In addition, in order to
enlarge the sound pressure from the directional speaker 101, you may affix the resonator 115
(for example, patent document 1).
[0004]
With such a configuration, a signal in which an audible sound signal is superimposed on a carrier
wave in the ultrasonic wave region from an external electric circuit (not shown) is input to the
piezoelectric element 105 through the electrode 109 and the lead wire 113, The element 105
and the diaphragm 103 vibrate to transmit voice information only to a specific target person,
that is, a user such as an electronic device.
[0005]
JP, 2006-245731, A
[0006]
The present invention is a directional speaker that vibrates a diaphragm provided with a
piezoelectric element to generate an acoustic wave by superimposing an audible sound signal on
a carrier wave in an ultrasonic wave range and inputting the sound signal into the piezoelectric
element.
In this directional speaker, the diaphragm is fixed to the fixing portion via a plurality of beams
provided on the outer periphery of the diaphragm.
[0007]
FIG. 1 is an exploded perspective view of the directional speaker in accordance with the first
exemplary embodiment of the present invention.
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FIG. 2A is a top view of a vibrating portion of the directional speaker in accordance with the first
exemplary embodiment of the present invention. FIG. 2B is a perspective view at the time of
vibration of the vibration section of the directional speaker in accordance with the first
exemplary embodiment of the present invention. FIG. 3 is an assembled perspective view of the
directional speaker in accordance with the first exemplary embodiment of the present invention.
FIG. 4 is a top view of another configuration of the vibration section of the directional speaker in
accordance with the first exemplary embodiment of the present invention. FIG. 5 is a top view of
another configuration of the vibration section of the directional speaker in accordance with the
first exemplary embodiment of the present invention. FIG. 6 is a top view of another
configuration of the vibration section of the directional speaker in accordance with the first
exemplary embodiment of the present invention. FIG. 7A is a top view of a vibrating portion of
the directional speaker in accordance with the second exemplary embodiment of the present
invention. FIG. 7B is a perspective view at the time of vibration of the vibration section of the
directional speaker in accordance with the second exemplary embodiment of the present
invention. FIG. 8 is a top view of a vibrating portion of the directional speaker in accordance with
the third exemplary embodiment of the present invention. FIG. 9A is a top view of a piezoelectric
element of a vibration section of the directional speaker in accordance with the fourth exemplary
embodiment of the present invention. FIG. 9B is a top view of the diaphragm of the vibration
section of the directional speaker in accordance with the fourth exemplary embodiment of the
present invention. FIG. 9C is a top view of a vibrating portion of the directional speaker in
accordance with the fourth exemplary embodiment of the present invention. FIG. 10 is an
exploded perspective view of the directional speaker in the fifth embodiment of the present
invention. FIG. 11 is an exploded perspective view of the directional speaker in the sixth
embodiment of the present invention. FIG. 12 is a cross-sectional view of a conventional
directional speaker.
[0008]
Prior to the description of the embodiment of the present invention, the problems in the
conventional configuration shown in FIG. 12 will be described.
[0009]
In the directional speaker 101 as shown in FIG. 12, the diaphragm 103 to which the piezoelectric
element 105 is attached is attached to the tip of the electrode 109 with the insulating adhesive
111.
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Therefore, the periphery of the diaphragm 103 is a free end. In addition, the insulating adhesive
111 has low rigidity. Therefore, when a signal is input to the piezoelectric element 105, the
diaphragm 103 vibrates in the vertical direction in FIG. 12 with the portion attached with the
insulating adhesive 111 as a node. That is, if the portion of the diaphragm 103 located between
the electrodes 109 is bent downward, the free end is bent upward, and the portion of the
diaphragm 103 located between the electrodes 109 is bent upward. For example, the free end
bends downward. Sound waves are generated by such an operation. However, when the
diaphragm 103 vibrates, stress is repeatedly applied to the insulating adhesive 111. In such a
state, when the deterioration of the insulating adhesive 111 progresses due to the influence of
ambient temperature and humidity, etc., the diaphragm 103 may be peeled off from the tip of the
electrode 109.
[0010]
On the other hand, if the insulating adhesive 111 is replaced with a more rigid material such as
metal bonding and fixed, the possibility of peeling is reduced. However, since the vibration of the
free end hardly occurs, the sound pressure is reduced accordingly.
[0011]
Hereinafter, embodiments of the present invention for solving such a problem will be described
with reference to the drawings.
[0012]
(First Embodiment) FIG. 1 is an exploded perspective view of a directional speaker according to a
first embodiment of the present invention.
FIG. 2A is a top view of a vibrating portion of the directional speaker in accordance with the first
embodiment of the present invention, and FIG. 2B is a perspective view of the vibrating portion
of the directional speaker in accordance with the first embodiment of the present invention. FIG.
3 is an assembled perspective view of the directional speaker in accordance with the first
exemplary embodiment of the present invention. 4 to 6 are top views of other configurations of
the vibrating portion of the directional loudspeaker in accordance with the first exemplary
embodiment of the present invention.
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[0013]
As shown in FIG. 1, the directional speaker includes a vibrating unit 11, a holder 23, and a base
25. The vibrating portion 11 is configured of a vibrating plate 13 having a disk shape, a
piezoelectric element 15, a plurality of beams 17, and a fixing portion 19. A gap between
adjacent beams 17 is called a slit 21. In addition, the diaphragm 13 is within the range of the
circle shown by the thin dotted line in the inner side of FIG. 1 in the vibrating portion 11, and the
fixed portion 19 is from the circle shown in the outer thin dotted line in FIG. Defined as the range
of
[0014]
Here, a plurality (eight in FIG. 1) of beams 17 exist, and they are provided along at the outer
periphery of the diaphragm 13 at least at a part of the outer periphery of the diaphragm 13.
Further, the plurality of beams 17 extend in the plane direction of the diaphragm 13, that is, in
the direction of the same plane as the plane of the diaphragm 13.
[0015]
Further, the other end of the beam 17 is fixed to the fixing portion 19. Specifically, the
diaphragm 13, the plurality of beams 17, and the fixing portion 19 are integrally formed by
pressing a metal plate such as aluminum. As a result, the connection between the diaphragm 13
and the beam 17 and between the beam 17 and the fixing portion 19 becomes strong. Further,
since it is not necessary to use an insulating adhesive or the like, peeling does not occur and the
reliability is enhanced. In addition, the processing method of integral formation is not limited to
press processing, It may be processing by etching. In this case, when the beam 17 is small or the
shape is complicated, it can be processed with high accuracy.
[0016]
The piezoelectric element 15 is formed on the upper surface of the diaphragm 13 obtained in
this manner. As shown in FIG. 2A, the piezoelectric element 15 is circular, and its diameter is
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slightly smaller than the diameter of the diaphragm 13.
[0017]
Here, the details of the beam 17 will be described. The beam 17 holds the diaphragm 13 firmly
in order to obtain high reliability. In addition, when the diaphragm 13 vibrates by inputting a
signal to the piezoelectric element 15, the beam 17 itself also bends to further expand the
displacement of the diaphragm 13. That is, the beam 17 has a role of raising the sound pressure.
Therefore, although the displacement expansion of the diaphragm 13 becomes possible by
providing the beam 17, in order to obtain a more effective displacement expansion, the length of
the beam 17 is set to the diaphragm 13 and the fixing portion in this embodiment. The distance
between them and 19 is set to be longer than the shortest distance between them. Therefore, as
shown in FIG. 2A, the beam 17 is formed in a spiral shape in the diagonal direction from the
diaphragm 13 to the fixing portion 19. As a result, since the diaphragm 17 can be displaced in
the twisting direction by the beam 17 as well as the beam 17 becomes longer, the displacement
can be expanded as a whole. If the sound pressure is larger than necessary, the sound pressure
can also be adjusted by changing the angle of the beam 17 or providing the beam 17 at the
shortest distance between the diaphragm 13 and the fixed portion 19.
[0018]
Next, the perspective view at the time of driving the vibration part 11 is shown to FIG. 2B. Note
that the expansion of the diaphragm 13 and the piezoelectric element 15 and the deflection of
the beam 17 are exaggeratingly shown. When the diaphragm 13 bulges upward in FIG. 2B, it can
be seen that the beam 17 also bows upward accordingly. As a result, the displacement of the
diaphragm 13 due to the deflection of the beam 17 is expanded, and high sound pressure can be
obtained.
[0019]
Furthermore, the beam 17 also has the following features. In the plurality of beams 17, the
distance of the portion fixed to the fixing portion 19 of the adjacent beams 17, that is, the width
of the slit 21 in the fixing portion 19 indicated by the arrow in FIG. 2A fixes the respective beams
17 to the fixing portion 19 It is made to be substantially zero within the accuracy. The term
"fixing accuracy" as used herein refers to the accuracy of pressing and etching.
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[0020]
As shown in FIG. 2A, such a shape of the beam 17 has a shape in which the shape of the slit 21 is
along the outer periphery of the diaphragm 13 (dotted line in FIG. 2A) on the diaphragm 13 side.
On the other hand, this corresponds to the absence of a portion along the inner circumference
(dotted line outside of FIG. 2A) of the fixing portion 19.
[0021]
As a result, the slits 21 hardly exist in the fixing portion 19, so the rigidity of the fixing portion
19 of the beam 17 can be enhanced.
Therefore, even if the deflection of the beam 17 due to the vibration of the diaphragm 13 is
repeatedly applied, the possibility of the beam 17 breaking at the fixing portion 19 can be
reduced, and the reliability can be further enhanced.
[0022]
The specific shape of the beam 17 varies depending on the material and thickness used for the
beam 17, the signal characteristics to be input, the required reliability, the sound pressure, and
the like, and thus may be appropriately determined through simulation or trial production.
[0023]
Here, returning to FIG. 1, the vibrating portion 11 configured as described above is fixed to one
end of the holding body 23 by the fixing portion 19.
Here, the holding body 23 has a cylindrical shape made of metal. Further, since the fixing portion
19 is a portion to which almost no vibration from the diaphragm 13 is transmitted, there is very
little possibility that the sound pressure is reduced even if firmly fixed to the holding body 23.
Therefore, the fixing portion 19 is welded to the holder 23 in order to obtain high reliability. In
addition, joining of both is not limited to welding, For example, the adhesive agent etc. with
which soldering, high reliability were ensured, etc. may be sufficient.
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[0024]
The other end of the holder 23 is fixed to a metal disk-shaped base 25. Here, the method of
welding or adhesion can be applied as described above for fixing the two. Two electrodes 29 are
fixed to the base 25 via an insulator 27. The two electrodes 29 penetrate the base 25, and the
terminals 31A and 31B are formed by flat plate processing of the tip of the electrode 29 on the
base 25 side. In addition, as such a base 25, the base part of the metal package by the metal case
(can) marketed, for example can be used.
[0025]
A perspective view of the directional speaker thus assembled is shown in FIG. Lead wires 33A are
bonded to the surface of the piezoelectric element 15. The other end of the lead wire 33A is
connected to the terminal 31A. In addition, since the piezoelectric element 15 is formed on the
upper surface of the diaphragm 13 made of metal, the back surface (contact surface with the
diaphragm 13) of the piezoelectric element 15 is electrically connected to the fixing portion 19
through the beam 17. Therefore, one end of the lead wire 33B is connected to the fixed portion
19 which is extremely less affected by the vibration of the diaphragm 13. The other end of the
lead 33B is connected to the terminal 31B. These connections are made by wire bonding. The
connection is not limited to wire bonding. For example, a flexible cable may be used as the lead
wires 33A and 33B, or a combination of a wire and a flexible cable may be used. If it is
[0026]
With such a configuration, a signal can be input to the piezoelectric element 15 from the
electrode 29. That is, the diaphragm 13 provided with the piezoelectric element 15 can be
vibrated by inputting a signal obtained by superimposing an audible sound signal on a carrier
wave in the ultrasonic wave region from the electrode 29 to the piezoelectric element 15. As a
result, since a directional sound wave is generated, it becomes possible to transmit voice
information only to a specific subject.
[0027]
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By the above configuration and operation, the diaphragm 13 is held by the plurality of beams 17
provided on at least a part of the outer periphery of the diaphragm 13, so that it is not necessary
to use the conventional insulating adhesive. Therefore, it becomes difficult to be influenced by
the ambient temperature and humidity, and high reliability can be obtained. Further, since the
beam 17 itself is bent, the entire vibration plate 13 can be vibrated even if the vibration plate 13
is held by the beam 17, so high sound pressure can be obtained. Therefore, a high sound
pressure directional speaker with high reliability can be realized.
[0028]
In the present embodiment, although the diaphragm 13, the plurality of beams 17, and the fixing
portion 19 are integrally formed, they may be separately formed. That is, they may be separately
formed, and the diaphragm 13 and one end of the beam 17, and the other end of the beam 17
and the fixing portion 19 may be firmly fixed by welding, soldering, adhesion or the like.
Thereby, the respective materials can be made different. For example, the diaphragm 13 is made
of a material having good adhesion to the piezoelectric element 15, the beam 17 is made of a
flexible material, and the fixing part 19 is made of a highly rigid material, Each can be designed
optimally. In addition, when the diaphragm 13, the plurality of beams 17, and the fixing portion
19 are integrally formed of the same material, optimum reliability and sound pressure may not
be obtained with respect to input signal characteristics and the like. In such a case, by using a
separate configuration, it is possible to configure a directional speaker that achieves both high
reliability and high sound pressure.
[0029]
Further, although the piezoelectric element 15 is formed only on the upper surface of the
diaphragm 13 in the present embodiment, the same effect as in the case of forming the upper
surface (high reliability and high noise can be obtained even if formed on the lower surface (back
surface) of the diaphragm 13 Pressure) is obtained.
[0030]
Furthermore, the piezoelectric elements 15 may be formed on both sides of the vibrating plate
13, or a plurality of piezoelectric elements 15 may be formed so as to be laminated in different
polarization directions.
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As described above, in the case where a plurality of piezoelectric elements 15 are formed, by
connecting them in electrical parallel, it is possible to lower the voltage for obtaining the same
sound pressure, and the circuit configuration is simplified. . Also, if the same voltage is applied,
the sound pressure can be increased. Thus, by forming a plurality of piezoelectric elements 15, in
addition to the effects of high reliability and high sound pressure in the present embodiment, an
effect that cost reduction by simplification of the circuit and further high sound pressure can be
realized is also possible. can get.
[0031]
If it is desired to further increase the sound pressure, the piezoelectric element 15 may be
provided with a resonator having the conventional configuration described in FIG. However, it is
necessary to consider the position of the lead wire 33 so that the resonator does not abut on the
lead wire 33.
[0032]
Moreover, although the shape of the beam 17 was made into the spiral shape from the
diaphragm 13 to the fixing part 19 in this embodiment, it is not limited to this. For example, as
shown in the top view of the vibrating portion 11 in FIG. 4, the beam 17 may be configured as a
straight line. In this case, since the shape of the slit 21 is simplified, the accuracy can be ensured
even by press processing. Therefore, in addition to high reliability and high sound pressure, cost
reduction is also possible.
[0033]
In the configuration of FIG. 4, the slit 21 is formed along both the inner periphery (dotted line
outside of FIG. 4) of the fixing portion 19 and the outer periphery (dotted line inside of FIG. 4) of
the diaphragm 13. . That is, as shown to FIG. 2A, it becomes a shape different from the slit 21 in
which the part along the inner periphery (dotted line of the outer side of FIG. 2A) in the fixing ¦
fixed part 19 hardly exists. However, depending on the required reliability and sound pressure,
the configuration of FIG. 4 may be used rather than the configuration of the slit 21 of FIG. 2A in
the range where the reliability and sound pressure are secured. Sometimes it can be achieved.
Therefore, in addition to the reliability and the sound pressure, cost reduction may be taken into
consideration, and what shape of the beam 17 should be determined in a comprehensive manner.
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[0034]
Similarly, as in the case of the vibrating portion 11 shown in FIG. 5, the angles of the linear
beams 17 may be alternately reversed. In this case, the slit 21 having a large area is formed as
compared with FIGS. 2A and 4. Therefore, in addition to the effect obtained by the configuration
of FIG. 4, two lead wires 33 joined to the upper surface of the piezoelectric element 15 and the
fixing portion 19 can be taken out from the slit 21 to the lower surface. Therefore, the two
terminals 31A and 31B can be provided inside the holder 23 fixed to the base 25 in FIG. 1, and
the directional speaker can be miniaturized.
[0035]
Furthermore, as in the vibrating portion 11 shown in FIG. 6, a part of the beam 17 may be
formed along the circumference of the vibrating plate 13 or the fixing portion 19. In this case,
since the beam 17 has a crank shape, the beam 17 can be made longer than in FIGS. 2A, 4 and 5.
Therefore, the deflection of the beam 17 can be further increased when the diaphragm 13
vibrates. This configuration is effective when additional high sound pressure is required.
[0036]
(Second Embodiment) FIG. 7A is a top view of a vibrating portion of a directional speaker
according to a second embodiment of the present invention, and FIG. 7B is a diagram showing
vibration of the vibrating portion of the directional speaker according to the second embodiment
of the present invention. Each shows a perspective view. In the present embodiment, the same
components as in the first embodiment are assigned the same reference numerals and detailed
explanations thereof will be omitted.
[0037]
The characteristic feature of the present embodiment is that, in the plurality of beams 17, the
distance of the portion of the adjacent beams 17 fixed to the diaphragm 13, that is, the width of
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the slit 21 in the diaphragm 13 indicated by the arrow in FIG. It is to be substantially zero within
the fixing accuracy of each beam 17 to the diaphragm 13. As in the first embodiment, the fixing
accuracy referred to here is the accuracy of press processing or etching processing.
[0038]
As shown in FIG. 7A, such a shape of the beam 17 has a shape in which the shape of the slit 21 is
along the inner periphery (dotted line outside of FIG. 7A) of the fixing portion 19 on the fixing
portion 19 side. On the other hand, this corresponds to the absence of a portion along the outer
periphery of the diaphragm 13 (dotted line inside of FIG. 7A). This shape is opposite to the shape
of the slit 21 of FIG. 2A described in the first embodiment.
[0039]
With such a shape, the slits 21 hardly exist in the diaphragm 13. Therefore, the rigidity of the
diaphragm 13 of the beam 17 can be most enhanced. Accordingly, in the case where stress is
concentrated on the root portion of the beam 17 in the diaphragm 13 by the vibration of the
diaphragm 13 in the required drive characteristics of the directional speaker, the root of the
beam 17 is configured as shown in FIG. 7A. It is possible to reduce the possibility of part
breakage and to obtain further high reliability. That is, when the vibrating plate 13 is vibrated, as
shown in FIG. 7B, when the piezoelectric element 15 and the vibrating plate 13 swell upward, the
beam 17 is bent upward accordingly, but the width of the beam 17 is the vibrating plate 13 Since
the root portion of the driving force is the widest, even drive characteristics in which stress is
concentrated on the root portion can be made more reliable.
[0040]
Also in this embodiment, as in the first embodiment, the specific shape of the beam 17 depends
on the material and thickness used for the beam 17, the signal characteristics to be input, the
required reliability and the sound pressure, etc. As it changes, it may be determined
appropriately through simulation and trial production.
[0041]
By the above configuration and operation, the possibility of breakage of the root portion of the
beam 17 in the diaphragm 13 can be reduced, so that a high sound pressure directional speaker
having high reliability can be realized.
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[0042]
Third Embodiment FIG. 8 is a top view of a vibrating portion of a directional speaker in a third
embodiment of the present invention.
In the present embodiment, the same components as in the first embodiment are assigned the
same reference numerals and detailed explanations thereof will be omitted.
[0043]
The characteristic features of the present embodiment are as follows.
That is, in the plurality of beams 17, the distance of the portion fixed to the fixing portion 19 of
the adjacent beams 17, that is, the width of the slit 21 in the fixing portion 19 is substantially
within the accuracy of fixing each beam 17 to the fixing portion 19. It becomes 0. Moreover, in
the plurality of beams 17, the distance of the portion of the adjacent beams 17 fixed to the
diaphragm 13, that is, the width of the slits 21 in the diaphragm 13 is substantially within the
accuracy of fixing each beam 17 to the diaphragm 13. It becomes 0. In other words, the shape of
the beam 17 of the present embodiment is a shape having both the features of the first
embodiment and the second embodiment, and as shown by the arrows in FIG. It has become.
Therefore, the slit 21 does not have a portion along the outer periphery (dotted line in FIG. 8) of
the diaphragm 13 and does not have a portion along the inner periphery (dotted line on the
outside of FIG. 8) of the fixed portion 19. .
[0044]
With such a configuration, almost no slits 21 exist in the outer periphery of the diaphragm 13
and the inner periphery of the fixed portion 19, so that the rigidity of both the diaphragm 13 of
the beam 17 and the fixed portion 19 is It can be enhanced. As a result, even if the deflection of
the beam 17 due to the vibration of the vibrating plate 13 is repeatedly applied, the possibility of
breakage of the root portion of the beam 17 in the vibrating plate 13 and the fixed portion 19
can be reduced. Become.
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[0045]
Also in this embodiment, as in the first and second embodiments, the specific shape of the beam
17 is the material and thickness used for the beam 17, the signal characteristics to be input, and
the required reliability. Because it changes depending on the sound pressure, etc., it may be
determined appropriately through simulation or trial production.
[0046]
By the above configuration and operation, the possibility of breakage of the root portion of the
beam 17 in both the diaphragm 13 and the fixing portion 19 can be reduced, so that a high
sound pressure directional speaker having higher reliability can be realized.
[0047]
(Fourth Embodiment) FIG. 9A is a top view of a piezoelectric element of a vibration unit of a
directional speaker according to a fourth embodiment of the present invention, and FIG. 9B is a
vibration unit of the directional speaker according to the fourth embodiment of the present
invention. The top view of a diaphragm and FIG. 9C each show the top view of the vibration part
of the directional speaker in Embodiment 4 of this invention.
In the present embodiment, the same components as in the first embodiment are assigned the
same reference numerals and detailed explanations thereof will be omitted.
[0048]
The feature of the present embodiment is that the piezoelectric element 15 approaches the beam
17 at the portion of the diaphragm 13 to which the beam 17 is fixed, that is, at the root of the
beam 17 with respect to the diaphragm 13. .
Specifically, it has the following configuration. First, in the first to third embodiments, the shape
of each piezoelectric element 15 is circular, but in the present embodiment, as shown by the thin
dotted line in FIG. ) Is provided with a piezoelectric element protrusion 35. The piezoelectric
element protruding portion 35 is a portion that protrudes outside the circular shape (the shape
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shown by the thick dotted line in FIG. 9A) in the piezoelectric element 15 of the first to third
embodiments.
[0049]
Next, a top view of the diaphragm 13 before the piezoelectric element 15 is formed is shown in
FIG. 9B. Here, unlike the slit 21 of the third embodiment, there is a portion along the outer
periphery (dotted line inside of FIG. 9B) of the diaphragm 13 and the inner periphery of the fixed
portion 19 (dotted line outside of FIG. 9B) In the shape of the slit 21, there is also a portion along
the. This is because, in the configuration of the present embodiment, when vibrating the
diaphragm 13, the diaphragm 13 is vibrated under the condition that the possibility of breakage
of the root portion of the beam 17 in both the diaphragm 13 and the fixing portion 19 is
extremely low. It is because it is done. With this configuration, the slit 21 can be enlarged as in
FIGS. 4 and 5, so the processing for forming the slit 21 becomes easy, and the cost can be
reduced. Furthermore, by making the beam 17 spiral, the beam 17 can be made longer, and the
deflection of the beam 17 becomes larger, so the sound pressure can be increased accordingly.
[0050]
On the other hand, the portion with the beam 17 and the portion without the beam 17
alternately exist on the outer periphery of the diaphragm 13 (dotted line in the inside of FIG. 9B).
In the configuration shown in FIG. 9B, four beams 17 are formed, so there are four portions with
beams 17 and four portions without beams 17.
[0051]
When such a diaphragm 13 is vibrated, the latter is a free end between the portion where the
beam 17 is present and the portion where the beam 17 is not present, while the former is
restrained by the beam 17, so the rigidity is different. Therefore, when the circular piezoelectric
element 15 is used, depending on the specification of the directional speaker, a desired drive
characteristic may not be obtained.
[0052]
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Therefore, in the present embodiment, in the case where there is a portion where the beam 17 is
present and a portion where the beam 17 is not present on the outer periphery of the diaphragm
13, the piezoelectric element 15 is made to approach the portion where the beam 17 is present.
That is, when the piezoelectric element 15 is formed on the diaphragm 13 so that the
piezoelectric element protrusion 35 in FIG. 9A corresponds to the portion with the beam 17, as
shown in FIG. 9C, the piezoelectric element 15 approaches the portion with the beam 17 Do.
When the diaphragm 13 is vibrated by such a piezoelectric element 15, more stress is applied to
the part of the beam 17 by the piezoelectric element protrusion 35 to the beam 17. As a result, it
is possible to reduce the nonuniformity of the vibration of the diaphragm 13 due to the
difference in rigidity, and to increase the sound pressure by the amount of the piezoelectric
element protruding portion 35, thereby obtaining desired driving characteristics.
[0053]
By the above configuration and operation, the high reliability described in the first to third
embodiments can be obtained, and the diaphragm 13 near the beam 17 that is difficult to vibrate
can also be vibrated, and a directional speaker that can obtain further high sound pressure Can
be realized.
[0054]
In addition, the piezoelectric element protrusion part 35 described in this Embodiment is not
limited to the structure of the vibration part 11 of FIG. 9C, You may apply to the structure of FIG.
2A and FIGS. 4-8.
In particular, the configuration of FIGS. 2A and 4 to 6 in which the portion where the beam 17
exists and the portion where the beam 17 does not exist clearly exists on the outer periphery of
the diaphragm 13. In addition, the piezoelectric element protrusion 35 may be provided in the
configuration of the shape and arrangement of the beams 17 and the slits 21 other than those
shown in FIGS. 2A and 4 to 9C. These also provide the same effects as the configuration shown in
FIG. 9C.
[0055]
Fifth Embodiment FIG. 10 is an exploded perspective view of a directional speaker according to a
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fifth embodiment of the present invention. In the present embodiment, the same components as
in the first embodiment are assigned the same reference numerals and detailed explanations
thereof will be omitted.
[0056]
The configuration that is the feature of the present embodiment is that the vibrating portion 11
and the holding body 23 in the first embodiment are integrated. Specifically, as shown in FIG. 10,
the diaphragm 13, the beam 17, and the fixing portion 19 are integrally formed on the upper
surface of the metal cap 37, and a piezoelectric element (shown in FIG. 10) is formed on the back
surface of the diaphragm 13. It is assumed that the system is provided with Then, the whole of
them is referred to as a vibrating portion 11. The shape and arrangement of the diaphragm 13,
the beam 17, and the slit 21 are the same as those in FIG. 2A. Further, although not shown in FIG.
10, one end of a lead wire 33 is joined to the surface of the piezoelectric element.
[0057]
The other end of the lead wire 33 is connected to the terminal 31A. On the other hand, unlike the
configuration of FIG. 1, the terminal 31B is directly fixed to the metal base 25 without the
insulator 27 interposed. Therefore, the cap 37 is electrically connected to the electrode 29 by
overlapping the cap 37 on the base 25 and welding the bent portion provided at the lower end of
the cap 37 to the base 25. Further, as described above, the piezoelectric element is formed on the
back surface of the diaphragm 13 integrally formed on the upper surface of the cap 37.
Therefore, the bonding surface of the piezoelectric element with the vibrating plate 13 is
electrically connected to the electrode 29. Therefore, only one lead 33 is sufficient. As a result,
the possibility of disconnection of the lead wire 33 is reduced to half as compared with the first
embodiment, so the reliability is enhanced. Furthermore, since the holder 23 is not required, cost
reduction can be achieved, and since the lead wire 33 is disposed inside the cap 37,
miniaturization can also be achieved.
[0058]
Although the position of the piezoelectric element is different from that of the first embodiment,
the other configuration (the shape and arrangement of the beam 17 and the slit 21) is the same
as that of FIG. 1 as described above. The effect of pressure can also be obtained as in the first
embodiment.
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[0059]
By the above configuration and operation, as described in the first embodiment, high sound
pressure is obtained, and in addition to the high reliability by the configuration in which the
diaphragm 13 is held by the beam 17, the possibility of disconnection of the lead wire 33 is
reduced. This makes it possible to realize a more reliable directional speaker.
[0060]
In the present embodiment, only one lead 33 is used, but two leads may be used as in the first
embodiment.
In this case, the second lead wire 33 may be connected between the fixing portion 19 or the
inner surface of the cap 37 and the terminal 31B.
With such a configuration, a directional speaker having high reliability and high sound pressure
can be obtained although the possibility of disconnection of the lead wire 33 is similar to that of
the first embodiment.
[0061]
Further, the shapes and the arrangement of the beams 17 and the slits 21 described in the
present embodiment are not limited to those shown in FIG. 10, and may have the configurations
described in FIGS. 4 to 9C. Moreover, the shape and arrangement of the beam 17 and the slits 21
other than those shown in FIGS. 4 to 9C may be employed. These also provide the same effects as
the configuration shown in FIG.
[0062]
Also in the present embodiment, the piezoelectric element provided with the piezoelectric
element protrusion 35 described in the fourth embodiment may be used. Thereby, the same
effect as that of the fourth embodiment can be obtained.
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[0063]
Sixth Embodiment FIG. 11 is an exploded perspective view of a directional speaker according to a
sixth embodiment of the present invention. In the present embodiment, the same components as
in the first embodiment are assigned the same reference numerals and detailed explanations
thereof will be omitted.
[0064]
The feature of the present embodiment is characterized in that a plurality of (here, seven)
diaphragms 13 are integrally formed together with the beams 17 and the slits 21 on one metal
plate as a substrate, and each diaphragm 13 is formed. The piezoelectric element 15 is provided
on the upper surface of the All parts of the metal plate other than the diaphragm 13, the beam
17 and the slit 21 are fixed parts 19. Accordingly, in FIG. 11, a plurality of combinations of the
diaphragm 13 and the plurality of beams 17 are provided in the fixing portion 19. The metal
plate and the seven piezoelectric elements 15 constitute a vibrating portion 11. The shape and
arrangement of the diaphragm 13, the beam 17, and the slit 21 per one place are the same as in
FIG.
[0065]
The lead wires 33A are joined to the respective piezoelectric elements 15 of the vibration unit
11. These become one and are connected to the input terminal 39A. Further, one end of the lead
wire 33 </ b> B is electrically connected to a part of the fixing portion 19 in the vibrating portion
11. The other end of the lead 33B is electrically connected to the input terminal 39B. With such a
configuration, the seven piezoelectric elements 15 are electrically connected in parallel.
[0066]
The fixing portion 19 of the vibrating portion 11 is fixed to the holding portion 41. Here, a
plurality of bottomed hollow portions 43 having a diameter of the inner periphery (for example,
a thin dotted line outside of FIG. 2A) of the fixed portion 19 in the holding portion 41 at a
position facing each diaphragm 13 (in FIG. 11). 7) are provided. The hollow portion 43 has a
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bottom in order to emit the sound wave in only one direction (upward in the case of FIG. 10).
[0067]
With such a configuration, when the fixing portion 19 is fixed to the holding portion 41, the
diaphragm 13, the beam 17, and the slit 21 are positioned on the upper surfaces of the
respective hollow portions 43. Therefore, in the present embodiment, for example, seven
directional speakers described in the first embodiment are integrally formed. The holding portion
41 may be made of metal, but in the present embodiment, it may be made of resin because the
electric conductivity in the holding portion 41 is unnecessary.
[0068]
Here, if the holding portion 41 is made of resin, an adhesive is used to fix the fixing portion 19.
In this case, almost no vibration is transmitted from the vibrating plate 13 to the fixing portion
19 and bonding can be performed over the entire area on the upper surface of the holding
portion 41 where the hollow portion 43 does not exist, so the possibility of peeling is reduced.
Therefore, even if the holding portion 41 is made of resin, the reliability is high. Furthermore, in
the case of resin, since the cavity 43 can be manufactured by injection molding, the cost can be
reduced.
[0069]
On the other hand, if the holding portion 41 is made of metal, welding can be performed with the
fixing portion 19 of the vibrating portion 11, so that higher reliability can be obtained.
Furthermore, by screwing the lead wire 33B connected to the fixing portion 19 into, for example,
the thick holding portion 41 and strongly connecting it, the possibility of disconnection of the
lead wire 33B can be reduced, and from this point as well, high reliability can be obtained. Be
Therefore, from the viewpoint of the required reliability and cost, an appropriate material may be
selected as the holding portion 41 as appropriate.
[0070]
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In such a directional speaker, the diaphragm 13 provided with the piezoelectric element 15 by
inputting to the seven piezoelectric elements 15 a signal obtained by superimposing an audible
sound signal on the carrier wave in the ultrasonic wave region from the input terminals 39A and
39B. Each vibrate. As a result, since sharp directional sound waves are emitted in the same
direction (upward in FIG. 10) from seven locations, high sound pressure voice information can be
transmitted only to a specific subject.
[0071]
By the above configuration and operation, high reliability can be obtained by the holding
structure of the diaphragm 13 by the beam 17, and high sound pressure can be obtained by the
deflection of the beam 17 by each of the plurality of diaphragms 13. Therefore, it is possible to
realize a directional speaker whose sound pressure is further increased.
[0072]
In the present embodiment, seven diaphragms 13 are provided. However, the number of
diaphragms 13 is not limited to seven. Even if the number of diaphragms 13 is increased or
decreased to obtain the required sound pressure. Good. Furthermore, the outer shapes of the
vibrating portion 11 and the holding portion 41 are not limited to the octagonal shape shown in
FIG. 11, and may be any shape such as a circle.
[0073]
Further, the shape and arrangement of the beam 17 and the slit 21 in the present embodiment
are not limited to the configuration of FIG. 11, and may be the configuration described in FIG. 4
to FIG. 9C. Moreover, the shape and arrangement of the beam 17 and the slits 21 other than
those shown in FIGS. 4 to 9C may be employed. Also by these, the same effect as the
configuration shown in FIG. 11 can be obtained.
[0074]
Also in the present embodiment, the piezoelectric element 15 provided with the piezoelectric
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element protruding portion 35 described in the fourth embodiment may be used. Thereby, the
same effect as that of the fourth embodiment can be obtained.
[0075]
Also in the second to sixth embodiments, as described in the first embodiment, the piezoelectric
elements 15 may be formed on both sides of the diaphragm 13 or may be stacked. As a result, it
is possible to further increase the sound pressure and to drive the piezoelectric element 15 at a
low voltage.
[0076]
According to the embodiment described above, a high sound pressure directional speaker with
high reliability can be obtained by reducing the removability of the diaphragm 13. That is, the
diaphragm 13 is held by the plurality of beams 17 by being fixed to the fixing portion 19 via the
plurality of beams 17 provided on at least a part of the outer periphery of the diaphragm 13. Ru.
Therefore, the beam 17 can also be flexed in response to the vibration of the diaphragm 13.
Therefore, it is not necessary to use the insulating adhesive to obtain the sound pressure
including the deflection of the free end of the diaphragm 13 as in the prior art, and it is not
necessary to use the insulating adhesive. Increase. Further, since the beam 17 itself is bent, the
entire vibration plate 13 can be vibrated even if the vibration plate 13 is held by the beam 17, so
high sound pressure can be obtained. Therefore, a high sound pressure directional speaker with
high reliability can be realized.
[0077]
According to the present invention, a directional speaker with high reliability and high sound
pressure can be obtained, and therefore, it is particularly useful as a directional speaker or the
like that transmits audio information only to a specific target person.
[0078]
DESCRIPTION OF SYMBOLS 11 vibration part 13 diaphragm 15 piezoelectric element 17 beam
19 fixed part 21 slit 23 support body 25 base 27 insulator 29 electrode 31A, 31B terminal 33,
33A, 33B lead wire 35 piezoelectric element protrusion part 37 cap 39A, 39B input terminal 41
Holding portion 43 hollow portion
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