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JP2015037199

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DESCRIPTION JP2015037199
[PROBLEMS] To provide a sound generator module for a display device which is thin, has high
sound pressure and high sound quality characteristics, and can reduce a bezel width of a display
unit. A piezoelectric sounding body 50 is supported on the back side of a liquid crystal display
unit 20 of a smartphone 10 by a sound conduction attachment 32. The sound conduction
attachment 32 is composed of a bottom 34 and a side 36 that receive the piezoelectric sounding
body 50. The bottom surface portion 34 forms a first air gap 60 between the piezoelectric
sounding body 50 and the housing bottom surface 12B. Further, the side surface portion 36 is
formed on the side of the piezoelectric sounding body 50 and the liquid crystal portion 20,
communicates with the first gap portion 60, and is connected to the sound emission hole 64 on
the surface side of the liquid crystal display portion 20 and opens. A second air gap 62 is
provided. By configuring the sound conduction path by the first air gap 60 and the second air
gap 62, the distance for transmitting the sound becomes longer, the sound pressure level in the
high sound range is reduced, and the sound quality as a whole is improved. [Selected figure]
Figure 1
Sounding body module and electronic device
[0001]
The present invention relates to a sound generator module and an electronic device, and more
particularly to a sound generator module for a display device including a display unit such as a
liquid crystal panel and an electronic device using the same.
[0002]
03-05-2019
1
At present, in the mobile field such as smartphones and tablet PCs, products equipped with a
liquid crystal touch panel having a haptic function are beginning to be on the market.
In addition, attempts have been made to use a piezoelectric sounding body used for the haptic
function to realize a speaker function. For example, in Patent Document 1 below, a speaker
whose case is covered with a case around a vibrating portion in which a piezoelectric element is
attached to the main surface of a diaphragm is disposed on the back surface of a liquid crystal
display panel via a cushion material. A touch panel device is disclosed that has a sound emission
hole formed along a side wall.
[0003]
Unexamined-Japanese-Patent No. 2013-20467
[0004]
In the background art using the piezoelectric sounding body described above, there is a problem
that secondary resonance is generated, an offensive peaky sound is generated in a high sound
area (10 kHz), and a good sound pressure and sound quality can not be secured as a speaker. is
there.
However, in the present situation where thinning of equipment progresses, it is indispensable to
use a piezoelectric sounding body, and it is necessary to be able to obtain good sound pressure
and sound quality even in a high sound area in a speaker using the piezoelectric sounding body.
In addition, if the bezel (frame) width of the display unit can be reduced, the device itself can be
thinned.
[0005]
The present invention focuses on the above points, and has an object of providing a sound
generator module having high sound pressure and high sound quality characteristics and
suitable for thinning, and an electronic device using the same. I assume.
[0006]
The present invention relates to a sound generator module for a display device in which a display
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unit is attached to a housing, and a piezoelectric sound generator arranged between the back
surface of the display unit and the housing, and the piezoelectric sound generator Soundconducting attachment for supporting the piezoelectric sounding body, the sound-conducting
attachment supporting the piezoelectric sounding body such that a first air gap is formed
between the piezoelectric sounding body and the housing And the second gap portion
communicating with the first gap portion and opened on the surface side of the display portion is
the display portion and the piezoelectric sounding body And a side surface formed in the lateral
direction, and a sound conduction path is formed by the first gap and the second gap.
[0007]
One of the main modes is to provide a protector for covering the periphery of the piezoelectric
sounding body, and the protector is characterized in that at least a part of the sound emitting
side of the piezoelectric sounding body is open.
Another embodiment is characterized in that the sound emitting side of the piezoelectric
sounding body of the protector is open on the side opposite to the second gap portion.
[0008]
An electronic device according to the present invention is characterized by including the sound
generator module according to any one of the above.
The above and other objects, features and advantages of the present invention will be apparent
from the following detailed description and the accompanying drawings.
[0009]
According to the present invention, the piezoelectric sounding body supported by the sound
guiding attachment is disposed between the housing and the back surface of the display unit.
Then, the sound conduction attachment is in communication with the bottom portion forming a
first gap between the piezoelectric sounding body and the housing, and the first gap and is open
at the surface side of the display unit. A second air gap portion is formed by the display portion
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3
and a side surface portion formed on the side of the piezoelectric sounding body. As a result,
since the sound guiding path is formed by the first air gap and the second air gap, the distance
through which the sound is transmitted is long while being thin, and the sound pressure in the
low sound region is not reduced. Only the sound pressure can be reduced to improve the sound
quality. In addition, the bezel width of the display portion can be reduced.
[0010]
BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the smart phone of Example
1 of this invention, (A) is a whole external appearance perspective view, (B) is a cross section
which cut said (A) along # A- # A line and was seen in the arrow direction. The figure, (C) is a
sectional view showing the lamination structure of a piezoelectric element. It is a graph which
shows the frequency characteristic of the sound pressure level of the said Example 1 and a
comparative example. It is a figure which shows the stereo mounting model of Example 2 of this
invention, (A) is a top photograph of a model housing ¦ casing, (B) cut said (A) along # B- # B line,
and is an arrow direction. It is sectional drawing of the mounting part seen. It is a graph which
shows the frequency characteristic of the sound pressure level (SPL) of the model housing ¦
casing of the said Example 2. FIG. It is a graph which shows the frequency characteristic of
distortion factor (THD) of a model case of the above-mentioned Example 2. It is a figure which
shows the stereo mounting model of Example 3 of this invention, (A) is a top photograph of a
model housing ¦ casing, (B) cut said (A) along # C- # C line, and it is an arrow direction. It is
sectional drawing of the mounting part seen. It is a graph which shows the frequency
characteristic of the sound pressure level (SPL) of the model housing ¦ casing of the said Example
3. FIG. It is a graph which shows the frequency characteristic of distortion factor (THD) of a
model case of the above-mentioned Example 3. It is a figure which shows the other Example of
this invention, (A) is sectional drawing of the sound generator module mounting part of Example
4, (B) is a figure which shows another Example.
[0011]
Hereinafter, the best mode for carrying out the present invention will be described in detail
based on examples.
[0012]
First, the basic structure of the present embodiment will be described with reference to FIGS. 1
and 2.
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The present invention mounts a speaker having an acoustic function of high sound pressure and
high sound quality to an electronic device having a display panel portion (such as a liquid crystal
panel portion) such as a mobile phone or a smartphone, or a car navigation device or a game
machine, for example. Related to technology. In the present embodiment, a smartphone will be
described as an example of the electronic device. FIG. 1 (A) is an external perspective view
showing the entire smartphone according to this embodiment, FIG. 1 (B) is a sectional view of the
above (A) cut along the # A- # A line and viewed in the arrow direction 1 (C) is a cross-sectional
view showing the laminated structure of the piezoelectric element. FIG. 2 is a diagram showing
frequency characteristics of sound pressure levels of the present embodiment and the
comparative example, in which (A) shows the present embodiment and (B) shows the
comparative example. In FIG. 1 and FIG. 2, one piezoelectric element with a size of 22 mm × 16
mm is used.
[0013]
As shown to FIG. 1 (A) and (B), the smart phone 10 of a present Example is provided in the
surface 12A side of the housing ¦ casing 12 with the liquid crystal display part 20 of a touchpanel type. The sound emission hole 64 of the sound generator module 30 built in the housing
12 and the operation switch 66 are provided on the surface 12A. In the present invention, the
direction in which the liquid crystal display unit 20 is viewed visually is defined as the surface
side (or upper side) and the opposite side as the back side (or lower side). The liquid crystal
display unit 20 has a configuration in which a display device is provided under a touch panel (not
shown), and as the touch panel, in addition to the electrostatic capacitance type, a known existing
method such as a resistive film type may be used. it can. In addition to the display device using
liquid crystal, a display device using organic EL or the like can also be used for the display
device. One sounding body module 30 is built in the housing portion 14 inside the housing 12 at
one end side in the longitudinal direction of the housing 12 (the left end side in FIG. 1A).
[0014]
The sound generator module 30 supports the piezoelectric sound generator 50 disposed between
the back surface of the liquid crystal display unit 20 and the bottom surface 12B of the housing
12 and the piezoelectric sound generator 50 and forms a sound conduction path. The sound
introducing attachment 32 is configured. The sound conduction attachment 32 is substantially
orthogonal to the bottom surface portion 34 attached so as to be partially embedded in the
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housing bottom surface 12 B and the bottom surface portion 34, and the piezoelectric sounding
body 50 and the liquid crystal display portion 20. It is comprised by the side part 36 formed in
the side part. The bottom surface portion 34 has a receiving portion 38 for receiving the
piezoelectric sounding body 50 and forms a first void portion 60 between the piezoelectric
sounding body 50 and the housing bottom surface 12B, for example, an adhesive layer 35. Are
attached to the housing bottom surface 12B. Further, the side surface portion 36 has a second
gap portion 62 which is in communication with the first gap portion 60 and connected to the
sound output hole 64 on the surface side of the liquid crystal display portion 20. The first air gap
60 and the second air gap 62 form a sound introducing passage having a substantially L-shaped
cross section.
[0015]
Further, the sound conduction attachment 32 supports the piezoelectric sounding body 50 so
that the first gap 60 is formed between the piezoelectric sounding body 50 and the housing 12,
and the housing 12. The first attachment 32A (portion indicated by a broken line in FIG. 1B)
having a bottom portion 32 attached to the bottom surface 12B of the liquid crystal and the first
gap portion 60 and the surface of the liquid crystal display portion 20 A second attachment 32B
(a portion shown by a broken line in FIG. 1B) having a side surface portion 36 formed on the side
of the liquid crystal display unit 20 and the piezoelectric sounding body 50, with a second air
gap 62 opened on the side. And may be separated. By making the structure so separable in this
manner, when the thickness of the housing 12 is thin and the second air gap 62 is short, the first
attachment 32A is formed long in the longitudinal direction, whereby the first attachment 32A is
formed. The length of the air gap 60 can be increased to increase the length of the sound guiding
path as a whole.
[0016]
The piezoelectric sounding body 50 has a structure in which the piezoelectric element 52 is
attached to one main surface of the diaphragm 51, the liquid crystal display unit 20 side is
covered by the display unit side protector 40, and the housing bottom surface 12B side Is
covered by the housing-side protector 42. The display unit side protector 40 is provided with a
back through hole 41 for moving air, and the housing side protector 42 is provided with a sound
output hole 44. The sound release holes 44 are round in this embodiment, but may be square or
rectangular. The edge of the piezoelectric sounding body 50 is attached to the receiving portion
38 of the sound conduction attachment 32 via a cushioning material 46.
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[0017]
In this embodiment, as the piezoelectric element 52, as shown in FIG. 1C, a laminated element
which forms a bimorph structure in the element is used. The piezoelectric element 52 shown in
FIG. 1C has a structure in which a plurality of piezoelectric layers 54 and electrode layers 56 are
alternately stacked, and in the present embodiment, the upper 52A and the lower 52B of the
center in the thickness direction The thing of the bimorph structure polarized so that the
polarization direction to an electric field was reverse was used. The piezoelectric element 52 may
have a single plate structure which is not laminated at all although it depends on the structure of
the electronic device to be mounted, or in the case of laminating, all piezoelectric layers are
polarized in the same direction with respect to an electric field. Although it is possible to adopt
the unimorph structure, it is preferable to use a laminated structure from the viewpoint of
suppressing the input voltage low, and to use a bimorph structure from the viewpoint of
increasing the generation displacement and generation force. Is desirable. As a material of the
piezoelectric layer 54, for example, a piezoelectric material obtained by adding an additive to
lead zirconate titanate is used, but other materials may be used in the case of generally known
piezoelectric ceramics. Good. As a material of the electrode layer 56, various known electrode
materials such as silver and platinum can be used, for example. In addition, since the diaphragm
51 needs to support the piezoelectric element 52 without inhibiting the bending vibration of the
piezoelectric element 52, for example, a film of a soft material such as urethane elastomer or
rubber is used.
[0018]
Further, since the display unit side protector 40 covering the periphery of the piezoelectric
element 52 and the housing side protector 44 require high rigidity, a metal material (for
example, stainless steel) having a Young's modulus of 100 GPa or more is used, and the thickness
is 0. It is preferable to set it as .1 mm or more. Further, the sound introducing attachment 32 is
formed of, for example, a SUS material having a thickness of about 0.4 mm. Further, as the
cushion material 46, for example, a rubber material is used.
[0019]
Next, the operation of the present embodiment will be described. The sound generated by the
vibration of the piezoelectric element 52 is, as shown by the arrow in FIG. The sound is emitted
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to the air gap portion 60, and is emitted to the outside from the sound emission hole 64 provided
on the surface side of the liquid crystal display unit 20 through the second air gap portion 62. In
this manner, the back side of the smartphone 10 is emitted, and by passing the first air gap 60
and the second air gap 62, the sound is introduced to the front surface side of the smartphone
10, thereby making it thin. The distance the sound travels will be longer. Therefore, while the
sound pressure in the bass region is transmitted without reduction, the sound pressure in the
treble region is reduced, and the sound quality as a whole is improved. Further, compared to the
case where a dynamic speaker is used, since the sound generator module 30 can be configured
to be thin, the bezel width of the liquid crystal display unit 20 (the width portion of the housing
surface 12A) can be reduced. In the embodiment of FIG. 1, since the liquid crystal display unit 20
and the sound generator module 30 are separated in the inside of the housing 12, the vibration
from the sound generator module 30 is not transmitted to the liquid crystal display unit 20. It is
possible to make the disturbance of the image in the part 20 less likely to occur.
[0020]
FIG. 2 shows the frequency characteristics of the sound pressure level of Example 1 in
comparison with the comparative example, and FIG. 2 (A) is a comparative example of the same
structure as the present example and (B) the background art. . The vertical axis in the figure is
the sound pressure level (SPL), and the horizontal axis is the frequency. As shown in FIG. 2 (B),
secondary resonance occurs in the comparative example, and a peaky sound is generated in the
high-tone area (10000 Hz). On the other hand, in the present embodiment, the sound conduction
path becomes longer, and the distance through which the sound travels becomes longer.
Therefore, as shown in FIG. 2A, the high sound area (10000 Hz) is not reduced without reducing
the sound pressure in the bass area. Only the sound pressure is reduced, and it can be seen that
the sound function as a speaker is improved.
[0021]
As described above, according to the first embodiment, the piezoelectric sounding body 50
supported by the sound conduction attachment 32 is disposed between the housing bottom
surface 12B and the back surface of the liquid crystal display unit 20 and on the back surface
side of the smartphone 10 Since the emitted sound is made to be emitted to the surface side of
the smartphone 10 through the substantially L-shaped sound introduction path (voids 60, 62)
formed in the sound introduction attachment 32, There is an effect like. (1)Since the sound
guiding path is formed by the first air gap 60 and the second air gap 62, the distance through
which the sound is transmitted is long despite being thin, and the sound pressure in the low
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sound region is not reduced, and only the high sound region Sound pressure can be reduced to
improve sound quality. In addition, the bezel width of the liquid crystal display unit 20 can be
reduced (for example, 1 mm or less). (2)Since the bottom surface portion 34 of the sound
conduction attachment 32 is mounted so as to be embedded in the housing bottom surface 12B,
the sound conduction path is lengthened without changing the thickness itself of the smartphone
10 to further improve the sound quality. Can. (3)Since the liquid crystal display unit 20 and the
sound generator module 30 are separated in the inside of the housing 12, the vibration from the
sound generator module 30 is not transmitted to the liquid crystal display unit 20, and the image
disturbance in the liquid crystal display unit 20, etc. Can be difficult to occur.
[0022]
Next, a second embodiment of the stereo mounting will be described with reference to FIGS. In
the second embodiment, the same 22 mm × 16 mm piezoelectric elements as in the first
embodiment are disposed at both ends of the housing to make a stereo mounting. That is, two
piezoelectric elements are used. FIG. 3 is a view showing a stereo mounting model of the present
embodiment, (A) is a plan photograph of a model case, (B) is a sectional view taken along the # B# B line of (A) and the arrow direction It is sectional drawing of the mounting part seen to FIG.
FIG. 4 is a graph showing the frequency characteristics of the sound pressure level (SPL) of the
model case of the present embodiment, and FIG. 5 is a graph showing the frequency
characteristics of the distortion factor (THD) of the model case of the present embodiment It is.
The same or corresponding elements as or to those of the first embodiment described above are
designated by the same reference numerals (the same applies to the other embodiments).
[0023]
As shown in FIG. 3A, the pseudo body 74 of the substrate disposed in the inside of the model
case 70 is disposed in the approximate center of the model case 70. As the dummy body 74, a
SUS plate was used. Sound generator modules 72A and 72B are mounted on the left and right of
the dummy 74, respectively. The basic structure of the sound generator modules 72A and 72B is
the same as that of the sound generator module 30 shown in FIG. 1 (B), but in the present
experimental example, the housing side protector 42 is omitted. The side is fully open. Also, the
thickness T of the smartphone 10 is 7.4 mm, the width Wh of the sound output hole 64 is 18
mm, the bezel width is 1 mm, the mounting height Ha of the piezoelectric speaker 50 is 2.2 mm,
and the height of the first gap 60 Hb is 0.7 mm, and the width (vertical direction in FIG. 3A) is 18
mm (corresponding to the width Wh).
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[0024]
From FIGS. 4 and 5, as in the first embodiment, the sound conduction path becomes longer and
the distance for transmitting the sound becomes longer. Therefore, the sound pressure only in
the high sound area (10000 Hz) is not reduced without reducing the sound pressure in the low
sound area. It can be seen that the sound function as a speaker is improved.
[0025]
Next, a third embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, piezoelectric elements having a size (33 mm × 18 mm) different
from that of the first embodiment are disposed at both ends of the housing to implement stereo
mounting. That is, two piezoelectric elements are used. FIG. 6 is a view showing a stereo
mounting model of Example 3, (A) is a plan photograph of a model housing, (B) is a sectional
view taken along the # C- # C line of (A) and the arrow direction It is sectional drawing of the
mounting part seen to FIG. FIG. 7 is a graph showing the frequency characteristics of the sound
pressure level (SPL) of the model case of the third embodiment, and FIG. 8 is a graph showing the
frequency characteristics of the distortion factor (THD) of the model case of the third
embodiment. It is. As shown in FIG. 6A, a pseudo body 74 similar to that of the second
embodiment is provided substantially at the center of the model case 80, and the sounding body
modules 82A and 82B are stereo-mounted on the left and right. ing. The basic structure of the
sound generator modules 82A and 82B is the same as the example shown in FIG. 1 (B), but in the
present embodiment, both the display side protector 40 and the housing side protector 42 are
omitted, It is fully open. The thickness T of the smartphone 10 is 7.4 mm, the width Wh of the
sound release hole 64 is 18 mm, the bezel width is 1 mm, the mounting height Ha of the
piezoelectric sounding body 50 is 2.0 mm, and the height Hb of the first gap 60 The width is 0.7
mm and 18 mm (corresponding to the width Wh).
[0026]
From FIG. 7 and FIG. 8, as in the first embodiment, the sound conduction path becomes longer
and the distance for transmitting the sound becomes longer, so the sound pressure only in the
high sound area (10000 Hz) is not reduced without reducing the sound pressure in the low
sound area. It can be seen that the sound function as a speaker is improved.
[0027]
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10
A fourth embodiment of the present invention will now be described with reference to FIG. 9 (A).
In the example shown in FIG. 9A, in the sound conduction attachment 30 of the sound generator
module 90, the housing side protector 42 (the sound output side of the piezoelectric sound
generator of the protector) is on the side opposite to the second gap 62 It is open. That is, a part
of the first air gap 60 is on the piezoelectric sounding body side 60A (the space between the
housing side protector 42 and the piezoelectric element 52) and the housing side 60B (the space
between the housing side protector 42 and the housing bottom surface 12B) It is divided. The
sound generated from the piezoelectric element 52 travels from the piezoelectric sound
producing body side 60A of the first air gap portion 60 through the housing side 60B to the
second air gap portion 62, so compared to the form of the first embodiment, The total length of
the sound guiding path can be further lengthened. For this reason, the sound pressure is further
suppressed to improve the sound quality. The other basic actions and effects are the same as in
the first embodiment.
[0028]
The present invention is not limited to the embodiments described above, and various
modifications can be made without departing from the scope of the present invention. For
example, the following are also included. (1)The shapes, dimensions, etc. shown in the above
embodiments are merely examples, and may be changed as appropriate. For example, in the
above embodiment, the shape of the piezoelectric sounding body 50 is a rectangle, and a specific
example of the dimensions is shown by an experimental example, but this is also an example, and
the length, width, and thickness of the piezoelectric sounding body 50 are the same. The amount
may be increased or decreased as appropriate within the range in which the effect of (2)Although
the piezoelectric sounding body 50 shown in the first embodiment has a unimorph structure, this
is also an example, and may be a bimorph structure. (3)The piezoelectric speaker 50 may have a
laminated structure or a single layer structure. Also in the case of a laminated structure, the
number of laminations may be appropriately increased or decreased as necessary.
[0029]
(4)
Various known materials can be used as the materials for forming the piezoelectric element 52,
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the diaphragm 51, or the protectors 40 and 42. Similarly, in the above embodiment, SUS was
used for the material forming the sound introducing attachment 32, but this is also an example,
and various known materials may be used within the range of achieving the same effect. Good.
(5)The number of mounted sounding body modules is also an example, and in the second and
third embodiments, two sounding body modules are mounted at both ends in the longitudinal
direction of the case to form a stereotype, but a touch panel device and an electronic device
provided with the same Depending on the configuration of the device (the smartphone 10 or the
like), as shown in the first embodiment, the number of mounted sound generator modules may
be one. Also, three or more may be used. Also, even in the case of stereotype, in the second and
third embodiments, one set of sound generator modules is disposed at both ends in the
longitudinal direction of the case, but as shown in the example shown in FIG. A pair of sound
generator modules 30A and 30B may be disposed at both ends in the short direction of the
direction.
[0030]
(6)
The case side protector 42 shown in the said Example 4 is also an example, and the position and
shape of an open part are changeable in the range which produces the same effect. (7)In the
above embodiment, the smart phone has been described as an example, but this is an example,
and can be applied to various electronic devices such as a mobile phone, a car navigation device,
a game machine, and the like. Moreover, it can be used as a receiver other than a speaker, and
may be changed to monaural or stereo according to need. (8)The above embodiments mainly use
the case where the piezoelectric sounding body is used as a sound source of the speaker, but it
does not prevent the use of the haptic function in the touch panel.
[0031]
According to the present invention, the piezoelectric sounding body supported by the sound
guiding attachment is disposed between the bottom of the housing and the back of the liquid
crystal display unit, and the sound emitted to the back of the smartphone is for the sound
guiding. Since it is made to be discharged to the surface side of the smartphone through the gap
formed in the attachment, the distance for transmitting the sound becomes long while being thin,
and the sound pressure in the bass region is not reduced, only the high-tone region Sound
pressure can be reduced to improve sound quality. For this reason, it is particularly suitable as a
sound generator module for mobile devices.
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[0032]
10: Smartphone 12: Case 12A: Surface 12B: Bottom 12C, 12D: Side 14: Storage unit 20: Liquid
crystal display unit 30, 30A, 30B: Sounding body module 32: Sound conduction attachment 32A:
First attachment 32B: Second attachment 34: bottom portion 35: adhesive layer 36: side portion
38: receiving portion 40: display side protector 41: through hole 42 on the back side: case side
protector (sound emitting side protector) 44: sound emitting hole 46: Cushion material 50:
Piezoelectric sounding body 51: Diaphragm 52: Piezoelectric element 52A: Upper side 52B:
Lower side 54: Piezoelectric layer 56: Electrode layer 60: First air gap 60A: Piezoelectric
sounding body side 60B: Housing side 62: No. Void part 2 of 2: sound emission hole 66:
operation switch 70, 80: model housings 72A, 72B, 82A, 82B, 90: sound generator module 74:
pseudo body
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