JP2015088908

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DESCRIPTION JP2015088908
PROBLEM TO BE SOLVED: To provide an electronic device capable of transmitting voice
information with small distortion. SOLUTION: A piezoelectric element 14 having a long shape in a
first direction and bendingly vibrating so as to change its amplitude in the first direction, and a
panel to which the piezoelectric element 14 is attached and which vibrates together with the
piezoelectric element 14 12 and a housing 19 to which the panel 12 is attached and which
vibrates together with the panel 12. The housing 19 has a mass on one side in the first direction
and a mass on the other side in the first direction. , But different electronic devices. It is possible
to obtain an electronic device capable of transmitting voice information with small distortion.
[Selected figure] Figure 6
Electronics
[0001]
The present invention relates to an electronic device.
[0002]
Conventionally, an electronic apparatus is known in which a diaphragm is vibrated by fixing a
plate-like piezoelectric bimorph element to a diaphragm and vibrating the piezoelectric bimorph
element (see, for example, Patent Document 1).
[0003]
Unexamined-Japanese-Patent No. 2006-238072
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[0004]
However, in the conventional electronic device described above, the amplitude of the diaphragm
changes rapidly at a specific frequency, and when the audio information is transmitted by the
vibration of the diaphragm, distortion occurs in the transmitted audio information. There was a
problem.
[0005]
The present invention has been made in view of the problems in the prior art as described above,
and it is an object of the present invention to provide an electronic device capable of transmitting
voice information with small distortion.
[0006]
The electronic device according to the present invention has a long shape in a first direction, and
a piezoelectric element that bends and vibrates so that the amplitude changes in the first
direction, and the piezoelectric element is attached to the piezoelectric element together with the
piezoelectric element. The panel has a vibrating panel, and a housing to which the panel is
attached and vibrating together with the panel, the housing has a mass on one side in the first
direction, and the other side in the first direction. And their mass are different.
[0007]
According to the electronic device of the present invention, it is possible to obtain an electronic
device capable of transmitting audio information with small distortion.
[0008]
It is a perspective view which shows typically the electronic device of the 1st example of
embodiment of this invention.
It is a perspective view for demonstrating the structure of the electronic device shown in FIG.
It is a perspective view for demonstrating the structure of the electronic device shown in FIG.
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It is the A-A 'line sectional view in FIG.
It is the B-B 'line sectional view in FIG.
It is the C-C 'line sectional view in FIG.
It is a perspective view which shows typically the electronic device of the 2nd example of
embodiment of this invention.
It is a perspective view for demonstrating the structure of the electronic device shown in FIG. It is
the E-E 'line sectional view in FIG.
[0009]
Hereinafter, the electronic device of the present invention will be described in detail with
reference to the attached drawings.
[0010]
First Example of Embodiment FIG. 1 is a perspective view schematically showing an electronic
device according to a first example of the embodiment of the present invention.
FIG. 2 is a perspective view schematically showing the structure of the housing 19 in the
electronic device shown in FIG. FIG. 3 is a perspective view schematically showing the panel 12
and the piezoelectric element 14 and the display 18 attached to the panel 12 in the electronic
device shown in FIG. FIG. 4 is a cross-sectional view taken along the line A-A 'in FIG. FIG. 5 is a
cross-sectional view taken along the line B-B 'in FIG. 6 is a cross-sectional view taken along the
line C-C 'in FIG. The electronic device of this example includes a panel 12, a piezoelectric element
14, a display 18, and a housing 19 as shown in FIGS.
[0011]
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The piezoelectric element 14 has a long shape in the x-axis direction. Specifically, the
piezoelectric element 14 has a rectangular parallelepiped shape in which the x-axis direction is
the length direction, the y-axis direction is the width direction, and the z-axis direction is the
thickness direction. The piezoelectric element 14 is a laminate formed by laminating a plurality
of polarized piezoelectric layers and a plurality of electrode layers in the z-axis direction. Then, in
the z-axis direction, the electrode layers and the piezoelectric layers are alternately arranged.
[0012]
Also, the piezoelectric element 14 is such that the polarization direction with respect to the
direction of the electric field applied at a certain moment is reversed on one side and the other
side in the z-axis direction. Thus, for example, when an electrical signal is applied and one side in
the z-axis direction extends at a certain moment in the x-axis direction, the other side in the
thickness direction of the piezoelectric element 14 is contracted in the x-axis direction. Thus, the
piezoelectric element 14 has a bimorph structure, and when an electric signal is applied, the
piezoelectric element 14 flexurally vibrates in the z-axis direction so that the amplitude changes
in the x-axis direction.
[0013]
The piezoelectric element 14 has, for example, a length of about 15 mm to 40 mm, a width of
about 1 mm to 6 mm, and a thickness of about 0.2 mm to 1.0 mm. The piezoelectric layer
constituting the piezoelectric element 14 is preferably made of, for example, lead-free
piezoelectric material such as lead titanate (PT), lead zirconate titanate (PZT), Bi layer compound,
tungsten bronze structure compound, or the like. Although other piezoelectric materials may be
used. The thickness of one layer of the piezoelectric layer can be set to, for example, about 0.01
to 0.1 mm. The electrode layer constituting the piezoelectric element 14 can be formed
preferably using, for example, one containing a ceramic component and a glass component in
addition to a metal component such as silver or an alloy of silver and palladium. It may be
formed using other known metal materials.
[0014]
Such a piezoelectric element 14 can be manufactured, for example, by the following method.
First, a binder, a dispersant, a plasticizer, and a solvent are added to the powder of the
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piezoelectric material and the mixture is stirred to prepare a slurry, and the obtained slurry is
formed into a sheet to form a green sheet. Next, a conductor paste is printed on a green sheet to
form an electrode layer pattern, and the green sheet on which the electrode layer pattern is
formed is laminated to produce a laminated molded body, which is then degreased and fired to a
predetermined size. A laminate is obtained by cutting. Next, a conductor paste for forming a
surface electrode is printed, and after baking at a predetermined temperature, a DC voltage is
applied through the electrode layer to polarize the piezoelectric layer. Thus, the piezoelectric
element 14 can be obtained.
[0015]
The piezoelectric element 14 only needs to have the function of bending and vibrating based on
the input electric signal. The piezoelectric element 14 may be, for example, a unimorph type
piezoelectric element.
[0016]
The panel 12 has a rectangular thin plate shape. The piezoelectric element 14 is attached to the
surface of the panel 12 in the -z direction. In addition, only the peripheral edge of the surface in
the −z direction of the panel 12 is attached to the housing 19 and is vibratably attached to the
housing 19. The panel 12 vibrates together with the piezoelectric element 14 as the piezoelectric
element 14 vibrates. Such a panel 12 can be formed by suitably using a material having high
rigidity and elasticity such as an acrylic resin or glass, but may be formed by using other
materials. The thickness of the panel 12 is set to, for example, about 0.4 mm to 1.5 mm. Then, for
joining of the panel 12 and the piezoelectric element 14 and joining of the panel 12 and the
housing 19, known joining members such as a double-sided tape and an adhesive can be used.
The panel 12 may have an input device such as a touch panel.
[0017]
The display 18 is a display device having a function of displaying image information, and for
example, known displays such as a liquid crystal display, a plasma display, and an organic EL
display can be suitably used. The display 18 may also have an input device such as a touch panel.
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[0018]
The display 18 is attached to the surface of the panel 12 in the −z direction and integrated with
the panel 12. That is, the panel 12 functions as a cover for protecting the display 18. The display
18 may be attached to the housing 19. Also, the display 18 is not necessarily required, and may
be absent.
[0019]
The housing 19 has a box-like shape in which one surface is open, and the periphery of the panel
12 is joined to the opening. Thus, the housing 19 forms the outer shape of the electronic device
together with the panel 12 and functions as a support that vibratably supports the panel 12. The
housing 19 vibrates together with the panel 12 as the panel 12 vibrates. Such a housing 19 can
be formed preferably using a material such as a synthetic resin having high rigidity and elasticity,
but may be formed using other materials.
[0020]
In the electronic device of this example having such a configuration, an electrical signal having
audio information is input from the electronic circuit (not shown) to the piezoelectric element 14,
and the piezoelectric element 14 bends and vibrates based on the electrical signal. The bending
vibration of the piezoelectric element 14 causes the panel 12 and the housing 19 to bend and
vibrate. Therefore, by bringing the panel 12 or the housing 19 into contact with the human body,
audio information can be transmitted to the human body.
[0021]
Further, in the electronic device of this example, the first portion 21 which is a portion thicker
than the other portions of the housing 19 is provided on the −x direction side of the housing 19.
Further, by the housing 19 having the first portion 21, the mass on the −x direction side of the
housing 19 is larger than the mass on the + x direction side of the housing 19. That is, the mass
on one side (−x direction side) of the housing 19 in the x-axis direction is different from the
mass on the other side (+ x direction side) in the x-axis direction of the housing 19. As a result, in
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the bending vibration of the panel 12 and the housing 19, a rapid increase in the amplitude at a
specific frequency can be reduced, and thus an electronic device capable of transmitting an audio
signal with small distortion can be obtained. It is presumed that the reason why this effect is
obtained is that the level of the peak due to the resonance in the frequency characteristic of the
sound pressure of the electronic device is reduced by the decrease in the symmetry of the
bending vibration of the housing 19. The −x direction side of the housing 19 means the −x
direction side of the center of the housing 19 in the x-axis direction (shown by the line DD ′ in
FIGS. 6 and 9). The + x direction side of + means the + x direction side of the center (shown by
the DD ′ line in FIGS. 6 and 9) in the x axis direction of the housing 19. Further, by bending and
vibrating the piezoelectric element 14 so that the amplitude changes in the x-axis direction, the
panel 12 and the housing 19 also bend and vibrate so that the amplitude changes in the x-axis
direction. It is assumed that the above-mentioned effect can be obtained by the reduction of.
[0022]
The thickness of the first portion 21 is preferably 1.5 times or more of the thickness of the other
portion, and more preferably 2 times or more, but the thickness, width, etc. of the first portion 21
are desired. It can set suitably according to the size of the effect to be carried out. The position of
the first portion 21 is not limited to the position shown in FIG. 2, and may be another position.
Also, a plurality of first portions 21 may be provided. In addition, for example, the first portion
21 may be formed on the entire −x direction side of the housing 19.
[0023]
Moreover, although the case where the 1st part 21 was a part with thickness thicker than
another part was shown in the electronic device of this example, it is not limited to this. The first
portion 21 may be, for example, a portion formed of a material having a density higher than that
of the other portions.
[0024]
Second Example of Embodiment FIG. 7 is a perspective view schematically showing an electronic
device of a second example of the embodiment of the present invention. FIG. 8 is a perspective
view schematically showing the structure of the housing 19 in the electronic device shown in
FIG. FIG. 9 is a cross-sectional view taken along the line E-E 'in FIG. In the present example, only
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the points different from the first example of the embodiment described above will be described,
and the same components as those in the first example will be assigned the same reference
numerals and overlapping descriptions will be omitted.
[0025]
In the electronic device of this example, the second portion 22 which is a portion thinner than
the other portions of the housing 19 is provided on the + x direction side of the housing 19. And
since the housing ¦ casing 19 has the 2nd part 22, the mass by the side of + x of the housing 19
is smaller than the mass by the side of-x of the housing 19. That is, the mass on one side (−x
direction side) of the housing 19 in the x-axis direction is different from the mass on the other
side (+ x direction side) in the x-axis direction of the housing 19. Thereby, as in the electronic
device of the first example of the above-described embodiment, in the bending vibration of the
panel 12 and the housing 19, a sharp increase in the amplitude at a specific frequency can be
reduced. An electronic device capable of transmitting a small audio signal can be obtained.
[0026]
The thickness of the second portion 22 is preferably 2/3 or less of the thickness of the other
portion, and more preferably 1/2 or less, but the thickness, width, etc. of the second portion 22
are desired. It can set suitably according to the size of the effect to be carried out. The position of
the second portion 22 is not limited to the position shown in FIG. 8, and may be another position.
Also, a plurality of second portions 22 may be provided. In addition, for example, the second
portion 22 may be formed on the entire + x direction side of the housing 19.
[0027]
Moreover, although the case where the 2nd part 22 was a part whose thickness is thinner than
another part was shown in the electronic device of this example, it is not limited to this. For
example, the second portion 22 may be a portion formed of a material having a smaller density
than the other portions.
[0028]
(Modification) The present invention is not limited to the examples of the embodiments described
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above, and various changes and improvements can be made without departing from the scope of
the present invention.
[0029]
For example, in the first example of the embodiment described above, an example is shown in
which the housing 19 has the first portion 21 thicker than the other portions on the −x direction
side, and the first example of the embodiment described above Although the case where the
housing 19 has the second portion 22 thinner than the other portions on the + x direction side is
shown in the second example, the present invention is not limited to this.
For example, the housing 19 has one or more first portions 21 thicker than the other portions on
the −x direction side and has a second portion 22 thinner than the other portions on the + x
direction side. You may make it have one or more.
[0030]
12: panel 14: piezoelectric element 19: housing 21: first portion 22: second portion
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