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DESCRIPTION JPH1147689

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DESCRIPTION JPH1147689
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
piezoelectric vibrator for use in a vibration calling device of a mobile communication device such
as a portable telephone or pager, which generates bodily sensation vibration to notify a user of
an incoming call or call. On what is suitable for
[0002]
2. Description of the Related Art A conventional piezoelectric vibrator is shown in FIG. The figure
(a) is a perspective view of the basic composition of a piezoelectric vibrator, and (b) is a side view
showing typically the state at the time of vibration. In the same figure, the piezoelectric members
2a and 2b are disposed on both surfaces at one end side (fixed end side) of the plate spring 1
with a conductive adhesive or the like to constitute a bimorph type piezoelectric vibrator, and
support of the fixed end side The portion 3 is fixed to a support matrix such as a package or a
housing, and the other end side (free end side) of the plate spring 1 is oscillated around the
resonance frequency by applying an alternating voltage to the piezoelectric members 2a and 2b. .
In the same figure (b), S shows the maximum amplitude of vibration.
[0003]
Another conventional vibrator for vibration calling apparatus is an electromagnetic vibrator,
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which is configured by attaching an eccentric weight to a shaft of a small motor. At the time of
calling, an eccentric weight provided on the shaft of the small motor rotates to generate vibration
to notify the user (see Japanese Patent Application Laid-Open No. 3-270771).
[0004]
Recently, in mobile communication devices such as pagers and mobile phones, a ringing tone
notifying an incoming call or call often causes the user and the user to feel uncomfortable, and
therefore ringing vibration is used instead of ringing tone. The use is increasing.
[0005]
However, in the above-mentioned conventional electromagnetic vibrator, electromagnetic noise is
generated due to the internal contact of the brush (rotor) in the small motor while rotating, and
the surrounding electromagnetic environment is deteriorated. It was done.
In addition, since the current supplied to the coil in the small motor is large in order to drive the
small motor, the battery is consumed, and there is a problem that the continuous call time and
the waiting time after energization are shortened. Furthermore, the brush has a short life due to
friction due to rotation, and can not be operated stably for a long time.
[0006]
On the other hand, although the piezoelectric vibrator can avoid the above-mentioned problems,
in order to obtain the amplitude which exhibits a sufficient reporting function by the
configuration of the conventional piezoelectric vibrator, the length of the leaf spring is increased
to increase the amplitude. Needed, the whole was getting larger. Then, as a configuration to
obtain a large amplitude without increasing the size, it is conceivable to strengthen the excitation
force of the piezoelectric body by increasing the width of the piezoelectric body or increasing the
length of the piezoelectric body. Since the plate spring having a shape is used, there is a problem
that the rigidity of the plate spring is also increased by enlarging the piezoelectric body. That is,
when the piezoelectric body is made larger, the excitation force is increased, but the rigidity of
the plate spring is also increased. As a result, the effect of increasing the amplitude is offset and a
vibration having a sufficient notification function is not obtained.
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[0007]
It has also been proposed to add weight to the free end of the leaf spring to reduce the frequency
of vibration without increasing the size so that a vibration close to the sensational vibration can
be obtained, but in that case sufficient amplitude is obtained. And there is a problem that the
informing function is lowered (refer to JP-A-8-314467).
[0008]
As described above, although it is necessary to lengthen the leaf spring to lower the frequency
and increase the amplitude in order to obtain an amplitude having a sufficient informing
function, it can not be miniaturized, and hence the miniaturization And the increase in amplitude
contradict each other, and it was extremely difficult to satisfy both simultaneously.
[0009]
Accordingly, the present invention has been completed in view of the above circumstances, and
the object thereof is to realize a small size, light weight and thin structure with a simple
configuration, and a sufficiently strong vibration for notification at 100 Hz or less of the
sensation frequency. It is to be a thing.
[0010]
In the piezoelectric vibrator of the present invention, a piezoelectric body is disposed on a fixed
end side or a free end side of a center line orthogonal to the longitudinal direction of a leaf
spring, and the fixed end side is provided on the fixed line side. And a notch is provided at a
position excluding the piezoelectric body, and the rigidity of the leaf spring can be decreased by
the notch, and the amplitude can be increased while maintaining the short leaf spring. And
strong enough vibration can be obtained.
[0011]
Preferably, the notch portion is provided in a pair in the width direction of the plate spring, and
the width of the plate spring is w, and the notch depth of the one notch portion (depth in the
width direction of the plate spring) is d When satisfied, it is assumed that 0.05 ≦ d / w ≦ 0.45 is
satisfied.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION Piezoelectric vibrators 10 to 12 of the
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present invention are shown in FIGS.
In FIG. 1, the piezoelectric body is installed on the fixed end side of the center line m orthogonal
to the longitudinal direction of the leaf spring, and the notch 4 is provided on the fixed end side
of the center line m and excluding the piezoelectric body. Configuration.
[0013]
In the figure, 1 is a leaf spring made of phosphor bronze or the like, and 2a and 2b are installed
on both sides of the fixed end of the leaf spring 1 via a conductive adhesive or the like, lead
zirconate (PbZrO3), lead titanate ( Piezoelectric body made of piezoelectric ceramics such as
PbTiO3), lead zirconate titanate (PbZrTiO3), barium titanate (BaTiO3) or piezoelectric crystal, 3 is
a screw of the fixed end side of the plate spring 1 to another package or housing Support
portions for fixing by means such as stoppers, 4 are a pair of notches provided in the vicinity of
the installation portions of the piezoelectric bodies 2a and 2b between the piezoelectric bodies
2a and 2b and the free end side of the plate spring 1 .
In addition, electrodes (not shown) for applying an alternating voltage are provided on the
surfaces of the piezoelectric bodies 2a and 2b.
[0014]
Then, an alternating voltage of opposite phase is applied to the piezoelectric members 2a and 2b
so that their displacements are opposite, and the plate spring 1 is vibrated at a frequency near
the resonance point. It vibrates largely with the end side as a free end and functions as a
piezoelectric vibrator.
[0015]
In the present invention, the leaf spring 1 preferably has a high elastic limit, rigidity and
toughness, and a material having a Young's modulus of 5000 kgf / mm 2 or more, for example, a
metal such as phosphor bronze, spring steel, stainless steel, or an alloy.
On the other hand, materials such as plastics and rubbers having a Young's modulus of less than
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5000 kgf / mm 2 have no resistance to cyclic fatigue due to vibration and are not suitable as the
leaf spring 1.
Further, the thickness of the plate spring 1 is preferably 0.1 mm or more, in which case the
strength is maintained and a large vibration is easily obtained.
[0016]
The shape of the leaf spring 1 is a rectangular shape, a flat plate shape, an L-shaped, a U-shaped,
a spiral or other folded shape in a horizontal surface, a flat plate shape, a Y-shaped in a
horizontal surface, U A shape in which the free end side of the character shape or the like is
branched into a plurality, a shape in which a square shape is folded back in the vertical direction
(a shape as represented by a symbol 側面 in a side view), etc. is preferable. In that case, since the
shape is simple, it is easy to obtain a single resonance frequency with a large amplitude.
[0017]
The plate spring 1 is preferably wide at the fixed end side of the installation portion of the
piezoelectric body and narrow at the free end side. With this configuration, the piezoelectric
elements 2a and 2b having a large area can be used and the excitation force is Becomes larger.
As a result, the excitation force can be further enhanced without increasing the rigidity of the
plate spring 1.
For the same purpose, the thickness of the plate spring 1 may be increased at the installation
portion of the piezoelectric body and may be reduced at the other portions, or the width and
thickness may be simultaneously configured as described above.
[0018]
The piezoelectric bodies 2a and 2b are preferably located on the fixed end side of the free end
side where the plate spring 1 vibrates, and a plurality of piezoelectric bodies 2a and 2b may be
provided.
[0019]
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The piezoelectric members 2a and 2b are preferably flat and square, and energy of vibration can
be efficiently transmitted to the plate spring 1.
The thickness of one of the piezoelectric members 2a and 2b is preferably 0.1 mm to 0.5 mm,
and if it exceeds 0.5 mm, the rigidity of the piezoelectric members 2a and 2 b is high, so the
frequency of vibration is high and the amplitude is small. Become.
If it is less than 0.1 mm, the strength of the piezoelectric members 2a and 2b is reduced, and the
manufacture becomes difficult.
[0020]
The notches 4 and 4 are provided in a pair in the width direction of the spring 1, and the width
of the leaf spring 1 is w, and the depth of one notch 4 (depth in the width direction of the leaf
spring 1) is d. When this is done, it is preferable to set 0.05 ≦ d / w ≦ 0.45. If it is less than
0.05, there is almost no effect of increasing the amplitude and downsizing, and if it exceeds 0.45,
the strength decreases and the reliability is poor. More preferably, 0.2 ≦ d / w ≦ 0.4 is
preferable.
[0021]
Although either one of the notches 4 may be provided, it is preferable that a pair of the notches 4
and 4 be provided in the width direction of the plate spring 1 be suitable for the vibration mode.
Also, the shape of the notch 4 is a triangle, a U-shape, a semicircle, a concave, etc., which is cut at
an acute angle as shown in FIG. 1, and a triangle having a simple shape and having little
influence on vibration is preferable. In this case, it is difficult to generate a large number of
unnecessary resonance frequencies such as secondary resonance.
[0022]
In addition, it is preferable that the notches 4 and 4 be provided at positions close to the
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piezoelectric members 2a and 2b as much as possible and not to overlap the piezoelectric
members 2a and 2b. The reason is that the largest distortion occurs at the boundary between the
piezoelectric members 2a and 2b and the plate spring 1 on the main surface of the plate spring
1, and the boundary is the most deformed. Specifically, the distance between the end faces of the
piezoelectric members 2a and 2b and the center of the notch of the notches 4, 4 is preferably 0.1
mm to 1 mm. If the distance is less than 0.1 mm, position adjustment is difficult. If it exceeds 1
mm, the effect of the present invention of increasing the amplitude with a short leaf spring and
obtaining a sufficiently strong vibration is difficult to exhibit.
[0023]
Therefore, notches 4 may be further provided between the piezoelectric members 2a and 2b and
the fixed end of the plate spring 1, that is, in the vicinity of the installation portion of the
piezoelectric member in the support portion 3, for the same reason.
[0024]
FIG. 2 shows another embodiment of the present invention. In the piezoelectric vibrator 11 in the
figure, the piezoelectric members 2a and 2b are disposed on the free end side of the center line
m orthogonal to the longitudinal direction of the plate spring 1 It is the structure by which the
notch part 4 is provided in the fixed end side rather than the line m.
In the present embodiment, the piezoelectric members 2a and 2b also serve as a vibration source
and a weight, there is no need to separately provide a weight, and a plate spring is provided by
the notch 4 on the fixed end side and the piezoelectric members 2a and 2b as a weight. The
stiffness can be reduced and the amplitude can be increased with a short leaf spring.
[0025]
In the present embodiment, the material and shape of the plate spring 1, the shape and thickness
of the piezoelectric members 2a and 2b, and the notch depth d and the shape of the notches 4, 4
are the same as those of the embodiment of FIG.
[0026]
Further, the present invention can adopt the configuration as shown in FIG.
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The piezoelectric vibrator 12 in the same figure is characterized in that a plurality of
piezoelectric bodies are installed at a predetermined interval on the fixed end side of the leaf
spring, and the width of the portion of the leaf spring where the piezoelectric body is installed is
narrow. The stiffness of the leaf spring can be reduced at the installation part of the body, so that
the amplitude can be increased with the short leaf spring, so that a compact and sufficiently
strong vibration can be obtained.
[0027]
In the figure, reference numerals 7a and 7b denote a plurality of piezoelectric members disposed
on both sides of the fixed end of the plate spring 1, and the width of the plate spring 1
corresponding to the installation portion of the piezoelectric members 7a and 7b is narrow. Each
of the piezoelectric members 7a and 7b is provided at an interval of the gap 5, and the other
configuration is basically the same as that of FIG. In the figure, the width of the plate spring 1
corresponding to the piezoelectric members 7a and 7b at both ends is not narrowed, and thus
the width of the plate spring 1 is at least partially narrowed at the installation portion of the
piezoelectric member Good.
[0028]
The width of the plate spring 1 at the installation portion of the piezoelectric members 7a and 7b
is narrow, and the piezoelectric members 7a and 7b are divided into plural pieces, so that the
plate spring 1 corresponding to the gap 5 is reduced in rigidity and easily deformed. As a result,
a strong excitation force is obtained.
[0029]
The gap 5 is not particularly limited, but if the gap 5 is too large, the area of the piezoelectric
members 7a and 7b decreases and the excitation force decreases. Therefore, one piezoelectric
member in the longitudinal direction of the plate spring 1 It may be approximately the same as
the length of the plate 12a (about 1 to several mm).
[0030]
In the present invention, it is desirable that the piezoelectric members 7a and 7b be disposed so
that the upper and lower piezoelectric members overlap with each other, in order to make the
leaf spring 1 easy to deform.
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[0031]
Although the bimorph type has been described in the above embodiment, it may be a unimorph
type, or the configurations of the invention of FIGS. 1 to 3 may be used in combination.
If necessary, a weight may be added to the free end side of the plate spring.
[0032]
Thus, the present invention can partially reduce the stiffness of the leaf spring, so that the leaf
spring can be miniaturized and the excitation force can be increased to obtain a large amplitude.
Moreover, in order to strengthen the excitation force of a piezoelectric material, a piezoelectric
material having a large width and length can also be used.
[0033]
The present invention is not limited to the above embodiment, and various modifications may be
made without departing from the scope of the present invention.
[0034]
EXAMPLES Examples of the present invention are shown below.
[0035]
The piezoelectric vibrator 10 of FIG. 1 was produced by the following steps (1) to (5).
[0036]
(1) In order to produce a piezoelectric ceramic as a piezoelectric material, a PZT-based ceramic
raw material prepared so as to obtain desired electrical characteristics is wet-mixed, the mixture
is dewatered and dried, and then 800 to 1200 ° C. The mixture is calcined for 1 to 3 hours, and
the calcined material is ground again with a ball mill.
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[0037]
(2) The ground material is mixed with an organic binder, and a sheet-like piezoelectric molded
body having a predetermined thickness is formed by a doctor blade method or an extrusion
molding method.
[0038]
(3) A conductive paste such as Ag-Pd for an electrode is printed on both sides of the sheet-like
piezoelectric molded body.
[0039]
(4) The binder is removed at a predetermined temperature in the air, and firing is carried out at a
temperature of 1200 to 1300 ° C. for 2 to 6 hours in the air to prepare a piezoelectric substrate
which can be removed in large numbers.
[0040]
(5) A polarization process is performed by applying an electric field of about 3 kV / mm to both
surfaces of the piezoelectric substrate in silicon oil, and then cut into individual piezoelectric
materials with a wire saw or dicing saw so as to have a predetermined shape, The piezoelectric
body of the present invention is obtained.
In order to stabilize the polarization, heat aging may be performed at 150 to 250 ° C. for one
hour after the polarization treatment.
[0041]
A conductive adhesive made of silver paste or the like is used on both sides of the fixed end of
the plate spring 1 made of phosphor bronze having a Young's modulus of about 1.1 × 10 4 kgf /
mm 2 using the piezoelectric body obtained in this manner. The piezoelectric vibrator 10 of the
present invention was obtained.
[0042]
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Then, when the notch depth d of one of the notches 4, 4, the total length L of the plate spring 1,
the maximum amplitude S of vibration, and the resonance frequency fr are variously changed,
the result when the maximum amplitude S is measured is It is shown in Table 1.
In Table 1, NO. When 1 to 9 are constant at fr = 100 Hz, NO. 10 to 18 is the case where L = 41.9
mm is constant.
Moreover, NO. The reference numerals 19 and 20 indicate comparative examples, in which a leaf
spring 1 made of polychlorotrifluoroethylene having a Young's modulus of about 2000 kgf / mm
2 is used.
[0043]
At this time, the width w of the leaf spring 1 is 4 mm, the thickness is 0.4 mm, and the
piezoelectric members 2a and 2b are each (length = 10 mm) × (width = 4 mm) × (thickness =
0.15 mm) It was a size.
[0044]
From Table 1, as d is larger, L is smaller and S is larger.
Moreover, when d / w exceeded 0.45, the intensity | strength of the leaf | plate spring 1 fell, and
durability fell.
Comparative example NO. In S.19 and 20, although S is large, the leaf spring 1 is soft, so the fr
decreases and the vibration is weak, so that the strength of the leaf spring 1 is weak and the
durability is deteriorated and can not be put to practical use.
Moreover, NO. As in the case of No. 20, there was almost no effect by providing the notch 4.
[0045]
The piezoelectric vibrator 11 shown in FIG. 2 was manufactured in the same manner as
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described above, and was examined for d, L, and S. As a result, substantially the same effect as
that shown in FIG.
[0046]
Furthermore, the piezoelectric vibrator 12 of FIG. 3 is manufactured in the same manner as
above, and the difference d1 between the width of the portion of the plate spring 1 of the
installation portion of the piezoelectric body and the width w of the other portions is variously
set. Table 2 shows the results when the total length L of the plate spring 1 is adjusted under the
condition of a constant of 0.9 mm and a constant of fr = 100 Hz.
The thickness of the plate spring 1 is 0.4 mm, w = 5.0 mm, and the size of one of the
piezoelectric members 7a and 7b is (length = 1.38 mm) × (width = 5.0 mm) × (thickness) And
the gap 5 was 1.38 mm.
Accordingly, four piezoelectric members were provided on one main surface of the plate spring 1
and the length of the entire piezoelectric member was 9.66 mm.
[0047]
At the free end of the leaf spring 1, a flat plate weight made of phosphor bronze (length = 8.0
mm) x (width = 5.0 mm) and weighing 0.55 g is superimposed on the leaf spring 1 Attached.
[0048]
As shown in Table 2, as d1 increased, L decreased.
In particular, when d1 exceeded 1 mm, L was shortened by about 20%.
[0049]
According to the present invention, the piezoelectric body is disposed on the fixed end side or the
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free end side of the center line orthogonal to the longitudinal direction of the leaf spring, and is a
position on the fixed end side of the center line excluding the piezoelectric body. By providing
the notched portion, the rigidity of the leaf spring can be reduced, and the piezoelectric vibrator
can be miniaturized to increase the amplitude of vibration of the leaf spring.
Therefore, a compact, lightweight and thin structure is realized with a simple configuration, and a
piezoelectric vibrator that can obtain strong vibration for notification can be obtained.
[0050]
Brief description of the drawings
[0051]
1 is a perspective view of the basic configuration of the piezoelectric vibrator of the present
invention.
[0052]
2 is a perspective view of the basic configuration of the piezoelectric vibrator of the present
invention.
[0053]
3 is a perspective view of the basic configuration of the piezoelectric vibrator of the present
invention.
[0054]
FIG. 4 (a) is a perspective view of the basic configuration of a conventional piezoelectric vibrator,
and FIG. 4 (b) is a side view schematically showing the state of vibration in the conventional
piezoelectric vibrator.
[0055]
Explanation of sign
[0056]
1: leaf spring 2a: piezoelectric body 2b: piezoelectric body 3: support portion 4: notch 5: space
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7a: piezoelectric body 7b: piezoelectric body 10: piezoelectric vibrator 11: piezoelectric vibrator
12: piezoelectric vibrator
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