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JP2013030846

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DESCRIPTION JP2013030846
Abstract: In a piezoelectric exciter provided with a cantilever beam, desired vibration
characteristics are secured without any abnormality in use in a state of attachment to an
excitation panel. A base plate (40) is fixed in contact with the lower surface of a beam supporting
member (30) for supporting the beam (20) in a cantilevered manner. At that time, the base plate
40 has a substantially U-shaped cross-sectional shape provided with a pair of left and right side
walls 44 rising on both left and right sides of the beam support member 30, and the free end of
the beam 20 while maintaining this cross-sectional shape. It is configured to extend to the side to
the middle position. This prevents stress from concentrating on the free end side of the base
plate 40 even if the vibrational force is increased, while reducing the possibility that the free end
of the beam 20 abuts on the base plate 40, and excitation There is no risk that the tactile
sensation when pressing the panel 2 may be uncomfortable or the base plate 40 may be peeled
off. [Selected figure] Figure 1
Piezoelectric exciter
[0001]
The present invention relates to a piezoelectric exciter used in a state of being attached to an
excitation panel (for example, a touch panel of a liquid crystal display) in a state of being
attached to the excitation panel, and in particular, a cantilever beam The present invention
relates to a piezoelectric exciter having the
[0002]
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1
2. Description of the Related Art Conventionally, in portable terminals and the like provided with
a liquid crystal display, those configured to vibrate a touch panel of the liquid crystal display are
known as the speaker.
Then, as an actuator for driving the speaker, a piezoelectric exciter having a cantilever beam is
known.
[0003]
As a configuration of such a piezoelectric exciter, a beam in which a piezoelectric element is fixed
to the upper surface and / or a lower surface of a flat plate-like shim, a beam supporting member
for supporting the beam in a cantilever shape, It is widely known to have a base plate fixed to the
lower surface of the beam support member in contact with the lower surface of the beam
support member.
[0004]
In the piezoelectric exciter, a voltage is applied to the piezoelectric element in a state of being
attached to an excitation panel on the lower surface of the base plate, and the beam is vertically
bent and vibrated, thereby vibrating the touch panel It is configured to let you
[0005]
In the patent document 1, as a configuration of a base plate in such a piezoelectric exciter, it has
a substantially U-shaped cross-sectional shape provided with a pair of left and right side walls
rising on both left and right sides of a beam support member, An arrangement is described which
extends to the free end of the beam while maintaining this substantially U-shaped cross-sectional
shape.
JP, 2011-129971, A
[0006]
FIG. 8 is a side view showing a conventional piezoelectric exciter in use (that is, in a state of being
turned upside down and attached to the lower surface of the excitation panel 2).
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[0007]
As a configuration of the piezoelectric exciter, as shown in FIG. 8 (a1), the base plate 106 is
disposed only in the portion where the beam supporting member 104 for supporting the
proximal end of the beam 102 is located. Has the following problems.
[0008]
That is, as shown in FIG. 8 (a2), when the input voltage to the piezoelectric exciter increases and
the vibrational force increases, the end of the free end side of the beam 102 in the base plate
106 attached to the excitation panel 2 Stress concentrates on 106a.
For this reason, the base plate 106 floats up from the lower surface of the excitation panel 2 at
the end portion 106 a on the free end side, and a desired reaction force from the excitation panel
2 can not be obtained.
And if such a reaction force loss arises, a variation will arise in a vibration characteristic.
In FIG. 8 (a2), for the convenience of explanation, the state of the bending deformation of the
beam 102 is shown exaggeratingly more than the actual state.
[0009]
Also, due to the lifting of the end 106 a of the base plate 106, the effective length of the beam
102 is greater than the length L from the position of the free end of the beam support member
104 to the free end of the beam 102. It becomes L + α which is longer by the length α. For this
reason, as shown in FIG. 9 (a), the lowest resonance frequency F0 that should be maintained at a
constant value regardless of the magnitude of the vibrational force is increased as shown in FIG.
9 (b). As a result, the desired vibration characteristics can not be obtained.
[0010]
On the other hand, if the configuration as described in the above-mentioned "patent document 1"
is adopted, the contact area between the excitation panel 2 and the base plate 206 is set in the
longitudinal direction of the beam 102 as shown in FIG. The base plate 206 can be configured as
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a substantially rigid body, so that stress concentration on a part of the base plate 106 due to an
increase in vibration force can be prevented in advance. It becomes.
[0011]
However, in such a case, there is a problem that when the beam 102 vibrates, the free end abuts
on the base plate 206 to easily generate noise.
Further, since the base plate 206 is configured as a substantially rigid body, there is a problem
that when the user presses the excitation panel 2 with a finger or the like, a sense of discomfort
is generated in the tactile sensation. Furthermore, when the excitation panel 2 is strongly pressed
by the operation of the user, the excitation panel 2 tries to be bent and deformed. , 206b, there is
a problem that there is a risk of peeling off from the excitation panel 2.
[0012]
The present invention has been made in view of such circumstances, and in a piezoelectric
exciter provided with a cantilever beam, it is intended without any abnormality in use in a state
of attachment to an excitation panel. It is an object of the present invention to provide a
piezoelectric exciter capable of securing the vibration characteristics of the above.
[0013]
The present invention achieves the above object by devising the configuration of the base plate.
[0014]
That is, a piezoelectric exciter according to the present invention comprises: a beam in which a
piezoelectric element is fixed to the upper surface and / or the lower surface of a flat plate-like
shim; a beam support member supporting the beam in a cantilever shape; A piezoelectric exciter
comprising: a base plate fixed to the beam supporting member in contact with the lower surface
of the beam supporting member, wherein the base plate is attached to the excitation panel at the
lower surface of the base plate. The beam support member has a substantially U-shaped crosssectional shape with a pair of left and right side walls standing up on the left and right sides of
the beam support member, and while maintaining the substantially U-shaped cross-sectional
shape It is characterized in that it is formed so as to extend to an intermediate position of the
beam.
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[0015]
In the above configuration, the term indicating the directionality such as “upper surface” or
“lower surface” is used for the sake of convenience in order to clarify the positional
relationship between the members constituting the piezoelectric exciter, and piezoelectric The
directionality in the actual use of the mold exciter is not limited.
[0016]
In the above configuration, "while maintaining the substantially U-shaped cross-sectional shape"
does not necessarily have to maintain the same cross-sectional shape, and a range in which the
base plate can be configured as a substantially rigid body over the entire length If it is inside, it
may be constituted so that height of a pair of side wall on either side may change.
[0017]
As shown in the above configuration, in the piezoelectric exciter according to the present
invention, the base plate is fixed in contact with the lower surface of the beam supporting
member that supports the beam in a cantilever shape. And the base plate has a substantially Ushaped cross-sectional shape with a pair of left and right side walls standing up on the left and
right sides of the beam support member, and Since it is formed to extend to a midway position of
the beam toward the free end side of the beam while maintaining the substantially U-shaped
cross-sectional shape, the following effects can be obtained.
[0018]
That is, the base plate is not disposed only at the portion where the beam supporting member is
located, but extends as a substantially rigid body toward the free end of the beam to an
intermediate position of the beam while maintaining the substantially U-shaped cross-sectional
shape Therefore, even if the input voltage to the piezoelectric exciter is increased and the
vibration force thereof is increased, the stress is not concentrated on the end of the base plate on
the free end side.
Therefore, it is possible to prevent the base plate from rising from the excitation panel at the end
on the free end side.
As a result, it is possible to prevent in advance the occurrence of variations in vibration
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characteristics due to the reaction force loss from the excitation panel, and the floating of the end
of the base plate makes the effective length of the beam apparently longer. As a result, it is
possible to prevent in advance that the lowest resonance frequency F0 is lowered with the
increase of the vibration force and the desired vibration characteristics can not be obtained.
[0019]
At that time, since the base plate configured as a substantially rigid body extends up to an
intermediate position of the beam, it is possible to reduce the possibility that the free end abuts
on the base plate due to the beam vibration Thus, the generation of abnormal noise can be
effectively suppressed.
In addition, when the user presses the excitation panel with a finger or the like, there is a
possibility that the user may feel discomfort in the tactile sensation or the excitation panel is
strongly pressed, so that the base plate is moved from the excitation panel at both ends in the
longitudinal direction. There is no risk of peeling.
[0020]
As described above, according to the present invention, in a piezoelectric exciter having a
cantilever beam, expected vibration characteristics can be secured without causing abnormality
in use in a state of attachment to an excitation panel. .
[0021]
In the above configuration, if the left and right side walls are formed to extend above the
thickness center of the shim at the position of the free end side of the beam support member,
stress is concentrated The rigidity of the base plate can be sufficiently secured at the easy-to-use
portion, whereby the above-described effects can be further enhanced.
[0022]
In the above configuration, the position of the end on the free end side of the base plate is not
particularly limited as long as the position of the end on the free end side is in the middle of the
beam. The above-mentioned operation and effect can be reliably ensured if the position of the
length from the position of to the free end of the beam is set within the range of 1/4 to 3/4.
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[0023]
In the above configuration, if the stopper at the end of the free end of the base plate is in contact
with the beam when the beam is bent upward by a predetermined amount or more, the following
effects can be obtained. You can get it.
[0024]
That is, when a portable terminal or the like incorporating a piezoelectric exciter receives an
external impact due to a drop or the like, the beam will have an excessive amplitude, but the base
plate extending to the middle position of the beam is free Since the stopper is formed at the end
on the end side, excessive bending deformation of the beam upward can be prevented in
advance.
As a result, it is possible to prevent the beam from coming into contact with a component such as
a printed circuit board or a cover member in a portable terminal or the like and damaging it in
advance.
In addition, even if the beam does not contact strongly enough to cause such damage, the beam
abuts on the printed circuit board, the cover member, etc. with the increase of the vibrational
force, thereby generating noise. It can be prevented.
[0025]
In this case, the specific configuration of the stopper is not particularly limited, but the pair of
left and right cross claws extending substantially along the horizontal surface in the direction
approaching each other from the upper end edge of the pair of left and right side walls of the
base plate If the stopper is constituted by the part, the length of each of the horizontal claws can
be set relatively freely, whereby the function as the stopper can be surely exhibited.
[0026]
Instead of this, if the stopper is constituted by a pair of left and right longitudinal claws
extending substantially along the vertical surface in the direction approaching each other from
the end edge of the free end of the pair of left and right side walls in the base plate The
respective longitudinal claws can be made to abut on the shim only, whereby damage to the
piezoelectric element can be prevented in advance.
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[0027]
In the above configuration, when the flat cushion member is attached in a region from the
vicinity of the edge on the free end side of the base plate on the top surface of the beam to the
vicinity of the free end of the beam, the piezoelectric exciter When a portable terminal or the like
into which the device is incorporated receives an external impact, the cushion member can be
made to abut against the printed circuit board, the cover member, etc., and the beam may be
broken by its buffer action. Can be effectively prevented.
[0028]
In the above-described configuration, the following effects can be obtained if a projection
projecting upward is formed at the end on the free end side of the bottom wall of the base plate.
[0029]
That is, depending on the vibration mode of the beam, the beam will have a maximum amplitude
at an intermediate position in the longitudinal direction.
At this time, by setting a projection projecting upward at the end on the free end side of the
bottom wall of the base plate extending to the middle position of the beam, the amplitude in the
middle of the beam in the longitudinal direction is excessive. It is possible to make the beam abut
on the projection before the occurrence of the phenomenon, thereby reducing the possibility of
the beam being broken.
At that time, it is more preferable from the viewpoint of preventing breakage of the beam to use
an elastically deformable configuration as the configuration of the projection.
[0030]
In the above configuration, the left and right end portions of the edge on the free end side of the
beam support member are formed with a pair of left and right guide walls projecting to the free
end along the left and right side walls of the base plate Then, if the beam support members are
bonded and fixed to the side walls of the base plate at their guide walls, the following effects can
be obtained.
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[0031]
That is, with the configuration in which each guide wall of the beam supporting member and
each side wall of the base plate are bonded and fixed, the stress generated intensively at the free
end side of the base plate is a protrusion of both guide walls It can be dispersed in the direction.
As a result, the beam supporting member can be maintained in close contact with the bottom
wall of the base plate, so that the minimum resonance frequency F0 is more surely lowered as
the vibration force increases. It can be blocked.
[0032]
(A) is a side view showing a state in which a piezoelectric exciter according to an embodiment of
the present invention is disposed upward, (b) is a plan view of FIG. 1 (b) along the line II-II. The
III-III line section detailed view of a perspective view which shows the above-mentioned
piezoelectric exciter from diagonally above, a perspective view which disassembles the abovementioned piezoelectric exciter into main components and is seen from diagonally above In the
1st modification of the above-mentioned embodiment The perspective view (a) showing the
principal part of the piezoelectric exciter concerned is a side sectional view showing the principal
part in the state where the piezoelectric exciter concerning the 2nd modification of the abovementioned embodiment is arranged upwards, (b) is a perspective view (B) is a side view showing
the action of the conventional example, and (b) shows the state of use of another conventional
example. (A) is a graph showing proper vibration characteristics of the piezoelectric exciter, (b) is
a graph Graph showing vibration characteristics of the conventional example
[0033]
Hereinafter, embodiments of the present invention will be described using the drawings.
[0034]
FIG. 1 is a view showing a state in which a piezoelectric exciter 10 according to an embodiment
of the present invention is disposed upward, wherein (a) is a side view and (b) is a plan view.
2 is a cross-sectional detail view taken along line II-II in FIG. 1 (b), and FIG. 3 is a cross-sectional
detail view taken along line III-III in FIG.
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Furthermore, FIG. 4 is a perspective view showing the piezoelectric exciter 10 viewed obliquely
from above, and FIG. 5 is a perspective view showing the piezoelectric exciter 10 disassembled
into main components and viewed obliquely from above.
[0035]
As shown in these figures, the piezoelectric exciter 10 according to the present embodiment
includes a bimorph beam 20 in which piezoelectric elements 24 are fixed to upper and lower
surfaces of a flat plate-shaped shim 22, and the beam 20. And a base plate 40 fixed to the beam
support member 30 in a state of being in contact with the lower surface of the beam support
member 30.
[0036]
The piezoelectric exciter 10 is mounted on the lower surface of the base plate 40 in a state of
being attached to an excitation panel 2 such as a touch panel of a liquid crystal display by
adhesion or the like.
At this time, when a voltage is applied to the piezoelectric element 24, the piezoelectric exciter
10 is configured such that the beam 20 bends up and down and vibrates, thereby vibrating the
excitation panel 2.
[0037]
The shim 22 of the beam 20 is a metal plate such as a stainless steel plate having a rectangular
outer shape in a plan view, and the dimension in the longitudinal direction is about 30 to 40 mm
(for example, about 35 mm), and the dimension in the width direction is 3 to 6 mm The thickness
is set to a value of about 0.2 to 0.4 mm (for example, about 0.3 mm).
[0038]
One end of the shim 22 in the longitudinal direction is embedded in and fixed to the beam
support member 30 by insert molding, whereby cantilever support of the beam 20 is performed.
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At that time, the upper surface of the base end 22b of the shim 22 is partially exposed from the
beam support member 30, and the exposed portion constitutes the first terminal of the
piezoelectric exciter 10.
[0039]
The pair of upper and lower piezoelectric elements 24 are attached to the portions of the upper
and lower surfaces of the shim 22 exposed from the beam support member 30.
Each of the piezoelectric elements 24 has a rectangular outer shape slightly smaller than the
shim 22 in plan view.
That is, in the longitudinal direction of each of the piezoelectric elements 24, the free end
(hereinafter simply referred to as the “free end”) of the beam support member 30 is positioned
from the position of the end 30 a of the beam 20. Specifically, it is formed in the region between
the vicinity of the edge 22a) of the shim 22, and in the width direction, it is formed in the region
within a slightly narrower range than the shim 22.
The thickness of each of these piezoelectric elements 24 is set to a value of about 0.2 to 0.4 mm
(for example, about 0.3 mm).
[0040]
A metal foil 26 is attached to the upper surface of the piezoelectric element 24 located on the
upper side and the lower surface of the piezoelectric element 24 located on the lower side over
the entire range.
The metal foil 26 is made of a high hardness metal material such as stainless steel or 42 nickel
alloy, and the thickness thereof is set to a value of about 0.02 to 0.04 mm (for example, about
0.03 mm). .
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[0041]
The beam support member 30 is configured as a resin molded product in which the shim 22 is
formed as an insert.
The thickness of the beam support member 30 is set to a value of about 1.5 to 2.5 mm (for
example, about 1.9 mm), and the upper and lower surfaces of the beam support member 30 are
substantially equidistant to the center of the thickness of the shim 22. It is formed in position.
At this time, the end 30a on the free end side of the beam support member 30 is formed in a
vertical plane, but the left and right ends of the end 30a have a trapezoidal shape that tapers
toward the free end. A pair of left and right guide walls 30b are formed.
[0042]
A groove 30c extending in the longitudinal direction is formed in the beam support member 30,
and a U-shaped pin 60 is fitted into the groove 30c from the proximal end side of the beam
support member 30. ing.
The pair of open ends of the pins 60 are conductively fixed to the upper and lower metal foils 26
of the beam 20 by solder 62. The pin 60 constitutes a second terminal of the piezoelectric exciter
10.
[0043]
The base plate 40 has a bottom wall 42 extending in the horizontal direction along the lower
surface of the beam support member 30, and a pair of left and right side surfaces rising vertically
from the bottom wall 42 along both side walls of the beam support member 30 on both left and
right sides. It has a wall 44 and has a square U-shaped cross section. The base plate 40 is formed
by bending a metal plate such as a stainless steel plate having a thickness of about 0.05 to 0.2
mm (e.g., about 0.1 mm).
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[0044]
In the base plate 40, caulking claws 40c are respectively formed in the vicinity of the base end
edge (that is, the end opposite to the free end end edge) of the left and right pair of side walls 44.
Then, with the bottom plate 42 in contact with the lower surface of the beam support member
30, the base plate 40 crimps the pair of left and right crimp claws 40c from the left and right
sides to the upper surface of the beam support member 30. It is fixed to the support member 30.
[0045]
The left and right side walls 44 of the base plate 40 are formed at a relatively lower height on the
base end side than the left and right pair of crimped claws 40c, but are freer than the pair of left
and right crimped claws 40c At the end side, it is formed at a relatively high height. Specifically,
the upper end edge 44b of each side wall 44 is formed at substantially the same height as the
lower surface of the shim 22 on the base end edge side of the pair of left and right crimped claws
40c, while the pair of left and right The upper end edge 44a of each side wall 44 is formed at
substantially the same height as the upper surface of the beam support member 30 on the free
end side of the crimped claw 40c.
[0046]
The base plate 40 maintains the substantially U-shaped cross-sectional shape in which the upper
end edge 44 a of each side wall 44 is positioned at substantially the same height as the upper
surface of the beam support member 30. It is formed to extend in the horizontal direction to an
intermediate position. At this time, the position of the free end side edge 40 c of the base plate
40 is from the position of the free end side edge 30 a of the beam support member 30 to the free
end of the beam 20 (ie, the free end side edge 22 a of the shim 22). It is set to the position of
length L1 (for example, L1 = about 2 / 5xL) within the range of 1/4-3/4 to the length L to).
[0047]
In the base plate 40, lateral claws 40b are formed at the free end side of the left and right side
walls 44 respectively. The pair of left and right transverse claws 40b are formed to extend
substantially along a horizontal plane by bending substantially at right angles from upper end
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edges of the pair of left and right side walls 44 in a direction approaching each other. At this
time, the horizontal claws 40 b are formed such that the upper surfaces thereof are substantially
flush with the upper end edges of the side walls 44. The pair of left and right lateral claws 40b
function as a stopper that abuts against the beam 20 when the beam 20 is bent upward by a
predetermined amount or more.
[0048]
At the free end side of the bottom wall 42 of the base plate 40, a projection 40d is formed which
protrudes upward. The protrusion 40 d is configured by deforming in a step-up manner so that
the width direction central portion of the end on the free end side of the bottom wall 42 is
increased by approximately the thickness of the base plate 40.
[0049]
The beam support member 30 is adhesively fixed to each of the left and right side walls 44 of the
base plate at each of the left and right pair of guide walls 30 b. This bonding and fixing is
performed, for example, by caulking and fixing the base plate 40 to the beam support member
30, and then injecting the adhesive 64 between the guide walls 30b and the side walls 44.
[0050]
A flat cushion member 50 is attached to the upper surface of the beam 20 by adhesion or the
like in a region between the vicinity of the free end side edge of the base plate 40 and the vicinity
of the free end of the beam 20. The cushion member 50 has a rectangular outer shape slightly
narrower than the piezoelectric element 24 in plan view. The thickness of the cushion member
50 is set to about 0.4 to 0.6 mm (e.g., about 0.5 mm).
[0051]
Next, the operation and effect of the present embodiment will be described.
[0052]
In the piezoelectric exciter 10 according to the present embodiment, the base plate 40 is fixed in
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contact with the lower surface of the beam support member 30 supporting the beam 20 in a
cantilevered manner. Although the base plate 40 is configured to be attached to the excitation
panel 2, the base plate 40 has a substantially U-shaped cross-sectional shape including a pair of
left and right side walls 44 rising on both left and right sides of the beam support member 30 In
addition, since the beam 20 is formed to extend halfway to the free end of the beam 20 while
maintaining the substantially U-shaped cross-sectional shape, the following effects can be
obtained.
[0053]
That is, the base plate 40 is not disposed only at the portion where the beam support member 30
is located, but as a substantially rigid body while maintaining the substantially U-shaped crosssectional shape toward the free end of the beam 20. Since it extends to an intermediate position,
stress does not concentrate on the free end side of the base plate 40 even if the input voltage to
the piezoelectric exciter 10 is increased to increase its oscillating force. .
Therefore, it is possible to prevent the base plate 40 from rising up from the excitation panel 2 at
the free end side thereof.
As a result, it is possible to prevent in advance the occurrence of variations in the vibration
characteristics due to the reaction force loss from the excitation panel 2, and the floating of the
end of the base plate 40 makes the effective length of the beam 20 apparent. By making the
upper end longer, it is possible to prevent in advance that the lowest resonance frequency F0 is
lowered with the increase of the vibration force and the desired vibration characteristics can not
be obtained.
[0054]
At that time, since the base plate 40 configured as a substantially rigid body extends up to an
intermediate position of the beam 20, the possibility that the free end will abut against the base
plate 40 due to the vibration of the beam 20 is reduced. This can effectively suppress the
generation of abnormal noise. In addition, when the user presses the excitation panel 2 with a
finger or the like, the base plate 40 may be excited at both ends in the longitudinal direction due
to the possibility that the sense of touch may be uncomfortable or the excitation panel 2 is
strongly pressed. The risk of peeling off from the panel 2 can be eliminated.
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[0055]
As described above, according to the present embodiment, in the piezoelectric exciter 10
provided with the cantilever beam 20, desired vibration characteristics are secured without
causing abnormality in use in a state of attachment to the excitation panel 2. can do.
[0056]
At this time, in the present embodiment, the pair of left and right side walls 44 is formed to
extend above the thickness center of the shim 22 at the position of the end 30 a of the beam
support member 30 on the free end side. Therefore, the rigidity of the base plate 40 can be
sufficiently secured in the portion where stress is likely to be concentrated, whereby the abovedescribed effects can be further enhanced.
[0057]
Further, in the present embodiment, the position of the end 40 a on the free end side of the base
plate 40 is from the position of the end 30 a on the free end side of the beam support member
30. Since the position of the length L1 within the range of 1⁄4 to 3⁄4 with respect to the length L
to the edge 22a) of the above, the above-mentioned operation and effect can be reliably ensured.
[0058]
Furthermore, in the present embodiment, at the end on the free end side of the base plate 40, a
pair of left and right transverse claws extending substantially along a horizontal surface in a
direction approaching each other from the upper end edge of the left and right pair of side walls
44 40b is formed, and when the beam 20 is bent and deformed upward by a predetermined
amount or more, the pair of left and right horizontal claws 40b are made to abut against the
beam 20 as a stopper. An effect can be obtained.
[0059]
That is, if a portable terminal or the like into which the piezoelectric exciter 10 is incorporated
receives an external impact due to a drop or the like, the beam 20 will have an excessive
amplitude, but the base plate 40 extending to the middle position of the beam 20 Since the pair
of left and right lateral claws 40b as stoppers are formed at the end on the free end side,
excessive bending deformation of the beam 20 upward can be prevented in advance. .
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And thereby, it can prevent beforehand that the beam 20 contact | abuts and is damaged by
structural members, such as a printed circuit board in a portable terminal etc., and a cover
member.
In addition, even if the contact is not strong enough to cause such damage, the beam 20 contacts
the printed circuit board, the cover member, etc. with the increase of the vibrational force,
thereby generating abnormal noise. Can be prevented.
[0060]
At that time, since the stopper is constituted by the pair of left and right horizontal claws 40b,
the length of each of the horizontal claws 40b can be set relatively freely, thereby ensuring the
function as the stopper It can be demonstrated.
[0061]
Further, since the metal foil 26 is attached to the surface of each piezoelectric element 24, when
the beam 20 abuts on each horizontal claw portion 40b, the piezoelectric element 24 is
prevented from being damaged in advance. Can.
[0062]
Furthermore, in the present embodiment, a flat cushion member 50 is attached in a region
between the vicinity of the end 40 a on the free end side of the base plate 40 on the upper
surface of the beam 20 and the vicinity of the free end of the beam 20. Therefore, when a
portable terminal or the like into which the piezoelectric exciter 10 is incorporated receives an
external impact, the cushion member 50 can be made to abut against the printed circuit board,
the cover member, etc. Can effectively prevent the beam 20 from being broken.
[0063]
And in this embodiment, since the projection part 40d which protrudes upwards is formed in the
edge part of the free end side in the bottom face wall 42 of the base plate 40, the following
effects can be obtained.
[0064]
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That is, depending on the vibration mode (specifically, in the second and third vibration modes),
the beam 20 generates a maximum amplitude at an intermediate position in the longitudinal
direction.
At this time, a projection 40d projecting upward is formed at an end of the bottom surface 42 of
the base plate 40 extending to an intermediate position of the beam 20 at the free end side, so
that the intermediate part of the beam 20 in the longitudinal direction is formed. The beam 20
can be made to abut on the projection 40 d before the occurrence of excessive amplitude at the
position, which can reduce the possibility of the beam 20 being broken.
[0065]
Such an effect is also achieved by the fact that a pair of left and right lateral claws 40 b
configured as a stopper abuts on the beam 20 before an excessive amplitude occurs in the
middle of the beam 20 in the longitudinal direction. You can get it.
[0066]
Further, in the present embodiment, at the left and right end portions of the end 30 a on the free
end side of the beam support member 30, a pair of left and right guides protruding along the left
and right side walls 44 of the base plate 40 toward the free end. Since the walls 30b are formed
and the beam support members 30 are adhesively fixed to the side walls 44 of the base plate 40
at the respective guide walls 30b, the following effects can be obtained.
[0067]
That is, with the configuration in which each guide wall 30b of the beam support member 30 and
each side wall 44 of the base plate 40 are bonded and fixed, stress that is generated intensively
at the free end side of the base plate 40 It can be dispersed in the protruding direction of the
guide wall 30b.
As a result, the beam support member 30 can be maintained in close contact with the bottom
wall 42 of the base plate 40, so that the minimum resonance frequency F0 is more surely
reduced as the vibration force increases. It can be blocked.
[0068]
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In the above-described embodiment, the upper end edge 44a on the free end side of the caulking
claw 40c in each side wall 44 of the base plate 40 is formed to extend horizontally at
substantially the same height as the upper surface of the beam support member 30. Although
described in the above, it is also possible to form, for example, the position of the upper end edge
44 a so as to be gradually lowered toward the free end side.
Even in this case, the base plate 40 can be maintained as a substantially rigid body extending to
the middle of the beam 20 toward the free end of the beam 20, so that the weight of the base
plate 40 can be reduced. The same effect as that of the embodiment can be obtained.
[0069]
Although the case where the beam 20 is configured as a bimorph beam has been described in the
above embodiment, the same effect as that of the above embodiment can be obtained in the case
where the beam 20 is configured as a monomorph beam or a laminated beam. You can get
[0070]
Next, modifications of the above embodiment will be described.
[0071]
First, a first modification of the above embodiment will be described.
[0072]
FIG. 6 is a perspective view showing the main part of a piezoelectric exciter 110 according to this
modification.
[0073]
As shown in the figure, the basic structure of the piezoelectric exciter 110 according to this
modification is the same as that of the above embodiment, but the configuration of the stopper
formed on the base plate 140 is the above embodiment. It is different from the case.
[0074]
That is, in the present modification, when the beam 20 bends upward by a predetermined
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19
amount or more, the stoppers that abut the beam 20 are the pair of left and right side walls 144
at the free end side edge 140 a of the base plate 140. A pair of left and right longitudinal claws
140b extend substantially along a vertical plane by bending at substantially right angles in the
direction approaching each other from the upper end.
[0075]
When the configuration of the present modification is adopted, it is possible to make each of the
longitudinal claws 140 b abut against the beam 20 only against the shim 22, thereby preventing
damage to the piezoelectric element 24. Can be prevented.
[0076]
Next, a second modification of the above embodiment will be described.
[0077]
FIG. 7 is a view showing the piezoelectric exciter 210 according to the present modification
disposed upward, wherein (a) is a side cross-sectional view of the main part, and (b) is a crosssectional view taken along the line bb.
[0078]
As shown in the figure, the basic structure of the piezoelectric exciter 210 according to the
present modification is the same as that of the above embodiment, but the configuration of the
projection 240 d formed on the base plate 240 is the same as that described above. It differs
from the case of the embodiment.
[0079]
That is, also in the present modification, a protrusion 240 d that protrudes upward is formed at
the end on the free end side of the bottom wall 242 of the base plate 240, but this protrusion
240 d corresponds to the end of the bottom wall 242 The central portion in the width direction
at the end is cut and raised over a predetermined length from the end edge 240a on the free end
side, and formed in a cantilever shape in a stepped manner so as to be higher by approximately
the plate thickness of the base plate 240 There is.
[0080]
When the configuration of this modification is adopted, the beam 20 can be made to abut on the
projection 240d before an excessive amplitude occurs in the middle of the beam 20 in the
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20
longitudinal direction. Since the projection 240d can be bent and elastically deformed, the risk of
breakage of the beam 20 can be effectively reduced.
[0081]
The numerical values shown as specifications in the embodiment and the modifications are
merely examples, and it is needless to say that these may be set to different values as
appropriate.
[0082]
Reference Signs List 2 excitation panel 10, 110, 210 piezoelectric exciter 20 beam 22 shim 22a,
30a, 40a, 140a, 240a free end side edge 22b base end portion 24 piezoelectric element 26 metal
foil 30 beam support member 30b guide wall 30c groove portion 40, 140, 240 Base plate 40b
Lateral claw (stopper) 40c Crimping claw 40d, 240d Protrusion 42, 242 Bottom wall 44, 144
Side wall 44a, 44b Top edge 50 Cushion member 60 Pin 62 Solder 64 Adhesive 140b Vertical
claw (Stopper)
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