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DESCRIPTION JP2009188801

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DESCRIPTION JP2009188801
An object of the present invention is to provide a piezoelectric speaker which can be used in
combination with an antenna, can be used at a frequency of MHz band, and can minimize an
increase in shape due to being used in combination with an antenna. An antenna 4 is provided on
a frame 2 a which is a peripheral portion of a diaphragm 2. As a result, it is possible to minimize
the increase in size while achieving dual use with an antenna, and when applied to a small
electronic device such as a mobile phone, it is possible to save space in the device. Further, the
antenna 4 is a loop antenna formed in a loop shape. This enables, for example, use at the
frequency of the MHz band used in contactless IC card technology. Further, the magnetic
material sheet 5 was provided on the other surface of the frame 2 a so as to face the antenna 4.
As a result, it is possible to suppress a decrease in reception sensitivity when there is a metal
material in the vicinity of the antenna 4. [Selected figure] Figure 2
Piezoelectric speaker
[0001]
The present invention is a stationary or portable electronic device having at least one of a
noncontact communication function, a digital television broadcast reception function, a short
distance wireless communication function, a wireless LAN communication function, and an audio
output function. The present invention relates to a piezoelectric speaker suitable for use in a
device.
[0002]
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1
Conventionally, a piezoelectric speaker is known as a small-sized, low-current-driven acoustic
device using a piezoelectric body as an electroacoustic transducer, and is used as an acoustic
output device of a small electronic device (see, for example, Patent Document 1) .
Generally, a piezoelectric speaker has a structure in which a piezoelectric element in which an
electrode of a silver thin film or the like is formed is attached to a metal diaphragm. The sound
generation of the piezoelectric speaker is caused by applying an alternating voltage to both
surfaces of the piezoelectric element to cause shape distortion in the piezoelectric element and
vibrating the metal plate to which the element is attached and integrated.
[0003]
The piezoelectric speaker disclosed in Patent Document 1 is connected to a frame, a diaphragm, a
piezoelectric element disposed on the diaphragm, a frame and a diaphragm, and the diaphragm
can be linearly amplified. And an edge formed to fill a gap between the diaphragm and the
damper and the frame, and the diaphragm, the damper and the edge are formed on the same
plane. "Linearly" means that the entire diaphragm oscillates in a form close to parallel, in contrast
to drum movement. This increases the amplitude volume and facilitates the reproduction of the
low band.
[0004]
On the other hand, there is a proposal in which functions of a piezoelectric speaker and an
antenna are integrated (see, for example, Patent Documents 2 and 3). The selective calling device
disclosed in Patent Document 2 includes a wireless reception unit, a piezoelectric speaker for
alarm sound generation, and an alarm sound generation unit, and connects an input of the
wireless reception unit and a metal base unit of the piezoelectric speaker to make an antenna.
And
[0005]
Further, the speaker integrated antenna disclosed in Patent Document 3 includes a flat first
antenna element to which a piezoelectric material is attached, and a flat antenna disposed at a
predetermined distance from the first antenna element. A second antenna element and a
connecting line electrically connecting the first and second antenna elements, wherein the first
and second antenna elements are formed by applying an audio signal to the piezoelectric
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2
material. Vibrate.
[0006]
JP-A-1-115347 JP-A-2001-016692 (Patent No. 3160271) JP-A-2006-186881
[0007]
However, although the selective calling device disclosed in Patent Document 2 uses the metal
base portion of the piezoelectric speaker as an antenna, the size of a general piezoelectric
speaker as disclosed in Patent Document 2 is used. The metal plate used can not cover the
frequency in the MHz band.
For example, in Japan, terrestrial digital broadcasting for mobile terminals (so-called one-seg
broadcasting) uses 470 to 770 MHz, so it can not be applied to electronic devices for the
purpose of receiving one-seg broadcasting.
[0008]
Further, in the speaker integrated antenna disclosed in Patent Document 3, the shape of the
element can be changed for the second element in which two antenna elements exist and the
piezoelectric ceramic member is not provided, so that a predetermined frequency is obtained. It
is possible to cover the frequency in the MHz band by designing the size to be able to
However, since it is a flat antenna element, a large area is required to cover the above-mentioned
frequency band, and in the case of two antenna elements, one of the antenna elements is
arranged three-dimensionally, thus saving space. And the layout of parts is limited.
[0009]
The present invention has been made in view of such circumstances, and corresponds to a
frequency band of MHz by being a part of a piezoelectric speaker and using a frame-like frame
surrounding the periphery of a piezoelectric element as an antenna. An object of the present
invention is to provide a piezoelectric speaker capable of securing an antenna length to enable
use in a MHz band, and suppressing an increase in size due to the combined use with an antenna.
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[0010]
The piezoelectric speaker according to the present invention includes a diaphragm, a
piezoelectric element stacked on the diaphragm, and a frame for supporting the periphery of the
piezoelectric element, and at least a part of the frame is formed as an antenna.
[0011]
According to this configuration, since at least a part of the frame of the piezoelectric speaker is
formed as an antenna, it is possible to minimize an increase in size of the shape by using the
piezoelectric speaker as the antenna.
Further, by making the shape of the antenna in a loop shape, it is possible to cover the frequency
in the MHz band.
[0012]
Further, a piezoelectric speaker of the present invention includes a diaphragm and a piezoelectric
element stacked on the diaphragm, and an antenna is formed on the same plane as the
piezoelectric element and around the piezoelectric element.
[0013]
According to this configuration, since the antenna is formed around the piezoelectric element, it
is possible to minimize the enlargement of the shape by using the piezoelectric speaker and the
antenna together.
Further, by making the shape of the antenna in a loop shape, the antenna length can be secured
more than a plate-like antenna, so that the frequency in the MHz band can be covered.
[0014]
In the above configuration, the antenna is supported by a magnetic sheet.
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[0015]
According to this configuration, when there is a metal material in the vicinity of the antenna,
cancellation of the positive magnetic flux due to the demagnetizing field generated by the eddy
current can be suppressed to a low level.
As a result, even if there is a metal material in the vicinity of the antenna, the decrease in
reception sensitivity can be minimized.
This configuration is particularly effective in the case of an electromagnetic induction system
used for a noncontact IC card or the like.
[0016]
In the above configuration, the antenna is a loop antenna formed in a loop shape.
[0017]
According to this configuration, for example, it is possible to cover the frequency in the MHz
band such as 470 to 770 MHz used in one segment broadcasting.
[0018]
Further, in the above configuration, the antenna is a plate-like antenna formed in a plate shape.
[0019]
According to this configuration, space saving can be achieved.
The plate antenna is particularly effective in short distance wireless communication such as
Bluetooth (registered trademark) using a GHz (gigahertz) band, wireless LAN communication, and
the like.
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For example, in the case of 2.4 GHz, the half wavelength is 62.5 mm, and if the speaker unit has a
size of about 35 mm square, two antennas can be configured using the four sides of the frame.
[0020]
Further, in the above configuration, an elastic material is disposed between the diaphragm and
the antenna.
[0021]
According to this configuration, since the elastic material acts as an edge, the lowest resonance
frequency can be moved to the low band side, and the reproduction band can be expanded.
[0022]
Further, a mobile communication terminal of the present invention includes any one of the above
piezoelectric speakers.
[0023]
According to this configuration, it is possible to minimize the size increase of the shape by
sharing the piezoelectric speaker and the antenna.
In addition, by forming the shape of the antenna in a loop shape surrounding the periphery of
the piezoelectric element, it is possible to secure an antenna length that can cope with the MHz
band, so that it is possible to cover the frequency of the MHz band.
[0024]
According to the present invention, the piezoelectric speaker and the antenna can be used
together, for example, it can be used at the frequency of the MHz band used in the noncontact IC
card technology and the like, and the shape by being used also as the antenna Can be minimized.
[0025]
Hereinafter, preferred embodiments for carrying out the present invention will be described in
detail with reference to the drawings.
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[0026]
First Embodiment FIG. 1 is a diagram showing a schematic configuration of a piezoelectric
speaker according to a first embodiment of the present invention.
2 is a cross-sectional view taken along line a-A of FIG.
In FIG. 1 and FIG. 2, the piezoelectric speaker 1 of this embodiment includes one of a diaphragm
2 formed in a disk shape, two piezoelectric elements 3 provided on both sides of the diaphragm
2, and one of the diaphragm 2. Loop antenna 4 provided at the periphery of the surface of the
surface, a magnetic material sheet 5 made of a magnetic material provided at the periphery of
the other surface of the diaphragm 2, and a portion of the periphery of the diaphragm 2 And an
input / output terminal 6.
[0027]
As shown in FIG. 2, the diaphragm 2 is mainly composed of a core layer 7 and a skin layer 8, and
has a laminated structure in which the core layer 7 is an intermediate layer and is laminated so
as to sandwich both surfaces with the skin layer 8. ing.
The core layer 7 is made of an insulating material, and the skin layer 8 is made of a conductive
material (electrode material).
Although polyimide is mainly used as the insulating material constituting the core layer 7, a
modified polyimide may be used, and rubber-based polymer materials (SBR, NBR, acrylonitrile,
etc.), liquid crystal polymers and general-purpose plastic materials (polyethylene) Materials
having insulating properties such as terephthalate, polycarbonate, polyarylate film, etc. may be
used.
[0028]
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Moreover, although 42 alloy is mainly used as a conductive material which comprises the skin
layer 8, you may use stainless steel elsewhere, and any metals, such as copper, aluminum,
titanium, and silver (silver paste), are used. A thin film material containing them or an alloy thin
film material of them may be used.
Moreover, you may use the electroconductive thin film material which apply | coated and
hardened the paste-form thing in which the metal component was mix | blended. An adhesive is
mainly used for connection between the core layer 7 and the skin layer 8.
[0029]
In the present embodiment, the peripheral portion of the diaphragm 2 is referred to as a frame
2a. The antenna 4 is provided on one surface of the frame 2a, and the magnetic sheet 5 is
provided on the other surface. The two piezoelectric elements 3 have a so-called bimorph
structure which is attached to the diaphragm 2 with the polarization directions reversed. By
adopting the bimorph structure, it is possible to obtain approximately twice the displacement and
force as compared to the case of one piezoelectric element.
[0030]
As shown in FIG. 1, the antenna 4 is a loop antenna which is planarly wound on one surface of
the frame 2 a. The antenna 4 is formed as a part of the skin layer 8 constituting the diaphragm 2.
By making the antenna 4 a loop antenna, for example, it becomes possible to use at the
frequency of the MHz band used in the contactless IC card technology.
[0031]
The magnetic sheet 5 is provided on the other surface of the frame 2 a so as to face the antenna
4. The magnetic material sheet 5 suppresses the decrease in the reception sensitivity due to the
influence of the demagnetizing field generated when the metal material is in the vicinity of the
antenna 4. That is, if there is a metal material in the vicinity of the antenna 4, a demagnetizing
field is generated by the eddy current generated there and the positive magnetic flux is canceled,
but the magnetic sheet 5 suppresses the influence of the demagnetizing field to a low level. The
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input / output terminal 6 has two input terminals and two output terminals, the two piezoelectric
elements 3 are connected to the input terminal, and the antenna 4 is connected to the output
terminal. An electrode for connecting the piezoelectric element 3 to the input terminal of the
input / output terminal 6 is formed as a part of the skin layer 8 similarly to the antenna 4. The
method of forming the electrodes of the piezoelectric element 3 and the antenna 4 is the same as
in the following embodiments.
[0032]
As described above, according to the piezoelectric speaker 1 of the present embodiment, since
the antenna 4 is provided on the frame 2 a which is the peripheral portion of the diaphragm 2,
enlargement of the shape is minimized while achieving dual use with the antenna. Can be limited.
Thus, when applied to a small electronic device such as a mobile phone, space saving can be
achieved in the device. Further, since the antenna 4 is a loop antenna, it can be used at the
frequency of the MHz band used in the noncontact IC card technology and the like. For example,
it is also possible to use at a frequency of MHz band such as 470 to 770 MHz used in one
segment broadcasting. Further, since the magnetic material sheet 5 is provided on the other
surface of the frame 2 a so as to face the antenna 4, it is possible to suppress a decrease in
reception sensitivity when there is a metal material in the vicinity of the antenna 4.
[0033]
Second Embodiment FIG. 3 is a view showing a schematic configuration of a piezoelectric speaker
according to a second embodiment of the present invention. 4 is a cross-sectional view taken
along line b-B of FIG. In FIG. 3 and FIG. 4, the piezoelectric speaker 10 of the present
embodiment is not a united body that integrates the diaphragm such as the piezoelectric speaker
1 of the first embodiment described above and the frame forming the antenna, but is separate An
edge (elastic material) 13 is provided between the diaphragm 11 and the frame 12 which are
separately provided.
[0034]
Like the diaphragm 2 of the piezoelectric speaker 1 according to the first embodiment, the
diaphragm 11 includes the core layer 7 and the skin layer 8, and the core layer 7 is an
intermediate layer and laminated so that both surfaces thereof are sandwiched by the skin layers
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8. Has a laminated structure. Further, as the insulating material used for the core layer 7 and the
conductive material (electrode material) used for the skin layer 8, the same one as the diaphragm
2 of the piezoelectric speaker 1 of the first embodiment is used.
[0035]
The frame 12 is formed in a ring shape of a flat plate whose inner diameter is larger than the
diameter of the diaphragm 11 by the provision of the edge 13. The same insulating material as
the core layer 7 of the diaphragm 11 is used for the frame 12. A loop antenna 4 is provided on
one side of the frame 12, and a magnetic sheet 5 is provided on the other side of the frame 12 so
as to face the antenna 4.
[0036]
Plastic films, such as PET, polycarbonate, polyimide, etc. are used for the insulating material used
for the core layer 7 and the frame 12 of the diaphragm 11, and silver paste or ITO (indium tin
oxide) is used for the skin layer 8 of the diaphragm 11. A material having conductivity such as is
applied. The edge 13 is made of a material having a low Young's modulus (= high flexibility), such
as a rubber material, a soft epoxy resin, or a silicon material, relatively to the material used for
the core layer 7 of the diaphragm 11 Be In order to form the edge 13, thin films made of the
material are laminated on both surfaces of the diaphragm 11 and the frame 12, and the abovedescribed material is filled in the space between the diaphragm 11 and the frame 12. . However,
other than this method, the present invention is not limited to this type as long as there is a
method of filling the gap between the diaphragm 11 and the frame 12. By supporting the
diaphragm 11 by the edge 13, the lowest resonance frequency of the diaphragm 11 can be
moved to the low frequency side, and the reproduction band can be expanded.
[0037]
As described above, according to the piezoelectric speaker 10 of the present embodiment, a
material having a low Young's modulus, such as a rubber-based material, a flexible epoxy resin,
or a silicon-based material, is formed between the diaphragm 11 and the frame 12 separately.
Since the edge 13 using the above is provided, the reproduction band can be expanded and the
sound characteristic can be improved. Further, as in the piezoelectric speaker 1 according to the
first embodiment, since the frame 4 is provided with the antenna 4, enlargement of the shape can
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10
be minimized while achieving dual use with the antenna, and a mobile phone to be applied And
so on can be saved. In addition, since the antenna 4 is a loop antenna, it can be used at the
frequency of the MHz band used in contactless IC card technology and the like. For example, it is
also possible to use at a frequency of MHz band such as 470 to 770 MHz used in one segment
broadcasting. Further, since the magnetic material sheet 5 is provided on the other surface of the
frame 12 so as to face the antenna 4, in particular, in the antenna used for non-contact
communication which is an electromagnetic induction type, there is a metal material in the
vicinity of the antenna 4 It is possible to suppress a decrease in reception sensitivity in the case.
[0038]
Third Embodiment FIG. 5 is a diagram showing a schematic configuration of a piezoelectric
speaker according to a third embodiment of the present invention. Moreover, the a-A line
sectional view of FIG. 5 is the same as FIG. 2, and the b-B line sectional view of FIG. 5 is the same
as FIG. 5, 2 and 4, although the piezoelectric speaker 30 of the present embodiment integrates
the diaphragm and the frame, it has an arc shape between the diaphragm 31 and the frame 31 a
which is the peripheral portion thereof. A plurality of edges 32 are formed at regular intervals
along the circumferential direction. The edge 32 is obtained by forming a void in the arc-like
region by punching or the like to the core layer 7 exposed by etching and loading the void with a
resin such as a polymer having appropriate flexibility. Be The portion other than the air gap for
forming the edge 32 is the damper 31 b.
[0039]
In the second embodiment described above, since the diaphragm 11 and the frame 12 are
separated, it is necessary to match the axial centers of the diaphragm 11 and the frame 12 when
forming the edge 13, but in the present embodiment the diaphragm Since the frame 31a and the
frame 31a are integrated, it is not necessary to perform the axis alignment, and the manufacture
becomes easier. A loop antenna 4 is provided on one side of the frame 31a, and a magnetic sheet
5 is provided on the other side of the frame 31a so as to face the antenna 4.
[0040]
As described above, according to the piezoelectric speaker 30 of the present embodiment, since a
plurality of arc-shaped edges 32 are provided along the circumferential direction between the
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diaphragm 31 and the frame 31a which is the peripheral portion, the reproduction band Can be
expanded, and speech characteristics can be improved. Further, as in the piezoelectric speaker 1
according to the first embodiment, the antenna 4 is provided on the frame 31a, so that the
enlargement of the shape can be minimized while achieving dual use as an antenna, and a mobile
phone or the like to be applied It is possible to save space in small electronic devices of the In
addition, since the antenna 4 is formed in a loop shape surrounding the piezoelectric element to
secure the antenna length, the antenna 4 can be used at the frequency of the MHz band used in
the noncontact IC card technology. For example, it is also possible to use at a frequency of MHz
band such as 470 to 770 MHz used in one segment broadcasting. In addition, since the magnetic
material sheet 5 is provided on the other surface of the frame 31 a so as to face the antenna 4, it
is possible to suppress a decrease in reception sensitivity when there is a metal material in the
vicinity of the antenna 4.
[0041]
Fourth Embodiment FIG. 6 is a diagram showing a schematic configuration of a piezoelectric
speaker according to a fourth embodiment of the present invention. 7 is a cross-sectional view
taken along the line c-C in FIG. 6 and 7, in the piezoelectric speaker 50 according to the present
embodiment, as in the piezoelectric speaker 10 according to the second embodiment described
above, the diaphragm and the frame forming the antenna are not integrated, but separately. An
edge 52 is provided between the body diaphragm 51 and the frame 51a. Further, the
piezoelectric speaker 50 of the present embodiment has two sets of piezoelectric elements 53
having a bimorph structure.
[0042]
As shown in FIG. 6, there are a plurality of sets of edges 52 having the same shape, and the edges
52 are provided along the periphery of the diaphragm 51. Similarly to the piezoelectric speaker
30 according to the third embodiment described above, the formation of the edge 52 forms a
void by punching or the like with respect to the core layer 7 exposed by the etching process, and
the void has a high degree of appropriate flexibility. It is obtained by loading a resin such as a
molecule. The portion other than the air gap for forming the edge 52 is the damper 54. The
diaphragm 51 is supported by the edge 52 and the damper 54 on the frame 51 a.
[0043]
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The piezoelectric element 53 is formed in a rectangular shape having a size equal to or smaller
than 1⁄4 of the diaphragm 51, and is separately disposed on both surfaces of the diaphragm 51.
In this case, in order to form a bimorph structure, the piezoelectric element 53 on one surface of
the diaphragm 51 and the piezoelectric element 53 on the other surface of the diaphragm 51 are
disposed to face each other. The piezoelectric speaker 50 of the present embodiment has two
sets of piezoelectric elements 53 having such a bimorph structure. The shapes of the diaphragm
51, the edge 52, the piezoelectric element 53 and the damper 54 and the materials used for each
are described in detail in the prior document (WO 2006/087866 A1) filed by the present
applicant.
[0044]
The loop antenna 4 is provided on one surface of the frame 51a which is the peripheral portion
of the diaphragm 51, and the magnetic sheet 5 is provided on the other surface of the frame 51a
so as to face the antenna 4 ing.
[0045]
As described above, according to the piezoelectric speaker 50 of the present embodiment, since
the plurality of edges 52 are provided along the periphery of the diaphragm 51, the reproduction
band can be expanded, and the sound characteristics can be improved.
Further, as in the piezoelectric speaker 1 according to the first embodiment, the antenna 4 is
provided on the frame 51a, so that the enlargement of the shape can be minimized while
achieving dual use with the antenna. It is possible to save space in small electronic devices of the
Further, by securing the antenna length by using the antenna 4 as a loop shaped antenna
surrounding the piezoelectric element, it is possible to use at the frequency of the MHz band
used in the noncontact IC card technology and the like. For example, it is also possible to use at a
frequency of MHz band such as 470 to 770 MHz used in one segment broadcasting. Further,
since the magnetic material sheet 5 is provided on the other surface of the frame 51 a so as to
face the antenna 4, it is possible to suppress a decrease in reception sensitivity when there is a
metal material in the vicinity of the antenna 4.
[0046]
The piezoelectric speaker according to the present invention is not limited to the above-described
first to fourth embodiments, and may have any shape as long as it has a frame for supporting the
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diaphragm. .
[0047]
The present invention enables dual use with an antenna, for example, enables use at frequencies
in the MHz band used in non-contact IC cards etc., and minimizes an increase in the size of the
shape by dual use with an antenna. Stationary or portable type having at least one of non-contact
communication function, digital television broadcast reception function, short distance
communication function, wireless LAN function, and sound output function. Application to smallsized electronic devices is possible.
[0048]
1 is a cross-sectional view taken along line a-A of FIG. 1 showing a schematic configuration of the
piezoelectric speaker according to Embodiment 1 of the present invention. FIG. 3 is a schematic
view showing a piezoelectric speaker according to Embodiment 2 of the present invention. The
sectional view which shows the schematic structure of the piezoelectric speaker based on
Embodiment 3 of this invention The figure which shows the schematic structure of the
piezoelectric speaker based on Embodiment 4 of this invention sectional drawing taken along the
line c-C of FIG. 6
Explanation of sign
[0049]
DESCRIPTION OF SYMBOLS 1, 10, 30, 50 Piezoelectric speaker 2, 11, 31, 51 Diaphragm 2a, 12,
31a, 51a Frame 3, 53 Piezoelectric element 4 Antenna 5 Magnetic material sheet 6 Input-output
terminal 7 Core layer 8 Skin layer 13, 32 , 52 edge 31 b, 54 damper
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