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JPH1028932

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DESCRIPTION JPH1028932
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
vibrator for an ultrasonic actuator using a piezoelectric element.
[0002]
2. Description of the Related Art Compared to other actuators such as electromagnetic actuators,
ultrasonic actuators are characterized by their small size, light weight, and low cost, and high
thrust can be obtained. As a piezoelectric vibrator for this type of ultrasonic actuator, as shown in
FIG. 23, a cylindrical metal block 61, a ring-shaped piezoelectric vibrator 62, divided electrodes
63a and 63b, and a ring are disclosed in JP-A-6-197572. The vibratory drive means (vibrator) 68
is proposed, in which the piezoelectric vibrator 64, the ring electrode 65 and the metal block 66
are sequentially stacked in contact and fixed by screws 67. By applying a high frequency AC
voltage between any one of the divided electrodes 63a and 63b and the ring electrode 65, this
vibration type drive means 68 generates longitudinal vibration and bending vibration in the axial
direction, and the drive surface 61a Any one of the points above moves in an elliptical trajectory.
If the length of the vibration type drive means 68 (length from the lower end of the metal block
66 to the drive surface 61a) is properly selected, the vibration type drive means 68 resonates
with the longitudinal vibration and the bending vibration to generate the longitudinal vibration
and the bending. The maximum amplitude of the vibration appears on the drive surface 61a. The
movement direction of the elliptical trajectory can be changed by switching the divided
electrodes 63a and 63b to which an alternating voltage is applied.
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[0003]
SUMMARY OF THE INVENTION In the device disclosed in Japanese Patent Application Laid-Open
No. 6-197572, longitudinal resonance and bending oscillation length resonance are used in a
configuration in which the piezoelectric vibrators 62 and 64 are sandwiched between metal
blocks 61 and 66. doing. Therefore, since there is no optimal method for supporting and fixing
the vibrator, it is necessary to provide a flange near the vibration node (node) or to provide
peripheral support and fixing parts at several locations on the outer periphery, resulting in a
problem of upsizing of the device. There is.
[0004]
In order to solve the above-mentioned problems, the inventor of the present invention fixes one
end of the rod-like elastic body, and sets the length of the rod-like elastic body to a length which
accompanies bending secondary vibration when performing longitudinal primary resonance
vibration. Proposed a vibrator for an ultrasonic actuator (Japanese Patent Application No. 875957).
[0005]
The configuration is shown in FIG.
The vibrator 71 is used by being fixed in a cantilever state to a fixing portion 73 whose base end
is a rigid body on the side where the rod-like elastic body 72 faces the piezoelectric element.
When a phase difference of 90 ° is given to the first piezoelectric body 74 and the second
piezoelectric body 75 at the longitudinal primary resonance length resonance frequency of the
elastic body 72 and the AC drive voltage is applied, the elastic body 72 becomes 1 The bending
secondary vibration is concomitantly excited when the next resonance vibration is performed.
[0006]
As a result, the stretching vibration of the first piezoelectric body 74 and the second piezoelectric
body 75 disposed on both sides of the plane parallel to the axial direction of the vibrator 71 is
shown in FIGS. It produces the indicated vibrational displacement.
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[0007]
This vibrator can withstand a large pressing force of the moving body by using a specific
resonance system, and can obtain high thrust.
However, since the rod-like elastic body requires a specific length, the whole vibrator is apt to be
a little large, and it is difficult to make it compact.
[0008]
The present invention has been made in view of the above-mentioned conventional problems,
and its object is to shorten the length of a rod-like elastic body of a vibrator and to realize
coupled (synthetic) vibration with a base. The present invention is to provide a transducer for an
ultrasonic actuator which can be made compact by the above to obtain a high thrust.
[0009]
[Means for Solving the Problems] In order to achieve the above object, according to the invention
as set forth in claim 1, the rod-like elastic body and the base are sandwiched between the
piezoelectric body in series with the axial direction of the vibrator. The piezoelectric body
comprises first and second piezoelectric bodies disposed on different sides with respect to a
plane including the axial center of the rod-like elastic body, and the polarization direction of each
of the piezoelectric bodies is parallel to the axial direction. And fix one end of the rod-like elastic
body whose axial length is shorter than the length in the direction orthogonal to the axial
direction on the first end side in the axial direction of the piezoelectric body. A base of a crosssectional shape that easily generates torsional vibration is fixed to the second end side so as to be
orthogonal to the axis of the rod-like elastic body, and primary bending is generated in the rodlike elastic body and the base The torsional vibration was to be coupled.
[0010]
In the invention according to claim 2, the rod-like elastic body and the base are fixed with the
piezoelectric body interposed therebetween in series with respect to the axial direction of the
vibrator, and the piezoelectric body is centered on the axis of the vibrator. It comprises four
piezoelectric bodies arranged at 90 ° out of phase, one set of piezoelectric bodies being
arranged on different sides of a first plane including the axis of the vibrator, and the other set
The piezoelectric bodies of the above are disposed on different sides with respect to a second
plane that includes the axis of the vibrator and is orthogonal to the first plane, and the
polarization direction of each group is parallel to the axial direction. Fixing one end of a rod-like
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elastic body having a length in the axial direction shorter than a length in a direction orthogonal
to the axial direction on the first end side in the axial direction of the piezoelectric body. The base
of the cross-sectional shape which is likely to generate torsional vibration so as to be orthogonal
to the axis of the rod-like elastic body is fixed In addition, the rod-like elastic body is caused to
generate primary vibration in bending and torsional vibration is coupled to the base.
[0011]
In the invention according to claim 3, in the invention according to claim 1 or 2, the rod-like
elastic body is formed in a cylindrical shape whose diameter is longer than the length in the axial
direction, and the base has a rectangular shape in cross section. Is formed.
[0012]
In the vibrator according to the first aspect of the present invention, the AC drive voltage is
obtained by giving a predetermined phase difference to the piezoelectric bodies 4 and 5 arranged
on different sides of a plane including the axial center of the rod-like elastic body 2. By applying,
vibration modes of two resonance frequencies can be used.
[0013]
In FIG. 2, the size of the base 8 having a rectangular cross section is made constant (width W =
35 mm, thickness T = 20 mm, length L = 100 mm), and the cylindrical elastic body 2 is 30 mm in
diameter. Is a dynamic admittance characteristic of the vibrator 1 when.
In particular, an example is shown in which the length is made shorter than the diameter of the
cylindrical elastic body.
The characteristics shown by white symbols (.smallcircle., .DELTA., .Smallcircle.) Are vibration
modes which can be used as a lower vibrator with a resonance frequency of about 25 kHz, and
are hereinafter referred to as low order modes for convenience.
The characteristics shown by black symbols (●, 、, ♦) are vibration modes that can be used as
higher transducers with a resonance frequency of about 40 kHz, and are hereinafter referred to
as high-order modes for convenience.
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[0014]
As shown in FIG. 1 (a), in the low-order mode, bending vibration occurs in the cylindrical elastic
body 2 in the circumferential primary vibration mode, and the base 8 is primary in the width
direction and 2 in the longitudinal direction. The next vibration mode is considered to be
coupled.
[0015]
The movement (displacement) of the entire vibrator in the low order mode is indicated by a solid
line and a dotted line on the lower side of FIG. 1 (a).
That is, when the base 8 is convex upward, the cylindrical elastic body 2 bends to the right.
Similarly, when the base 8 is convex downward, the cylindrical elastic body 2 bends to the left.
[0016]
On the other hand, in the case of the high-order mode, it is considered that bending vibration is
generated in the cylindrical elastic body 2 in the circumferential direction secondary vibration
mode, and the width direction secondary and the length direction secondary vibration mode are
coupled to the base. .
[0017]
In the high-order mode, the right side of the base 8 is twisted clockwise with respect to the base
axis and the left side is twisted counterclockwise with respect to the base axis, as shown in the
lower side of FIG. 1 (b) When the cylindrical elastic body 2 bends to the right.
When the right side of the base 8 is twisted counterclockwise with respect to the base axis and
the left side is twisted clockwise with respect to the base axis, the cylindrical elastic body 2 bends
to the left.
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Then, with the movement of the entire vibrator 1, the tip of the cylindrical elastic body produces
an elliptical locus of displacement.
[0018]
For example, the piezoelectric elements of the left and right first and second piezoelectric
members 4 and 5 have a phase difference of −90 ° (the left piezoelectric (A phase) is 90 °
delayed with respect to the right piezoelectric (B phase)) ) Is applied, the vertical displacement of
the left and right portions of the tip surface of the elastic body 2 changes as shown in FIG. . The
movement of the left and right portions of the tip surface of the elastic body 2 corresponding to
each of the times I to VIII on the time axis of FIG. 3A is shown in FIG.
[0019]
At time I, since the first piezoelectric body 4 is contracted and the second piezoelectric body 5 is
expanded, bending as a whole is produced in the left direction. At time II, the first piezoelectric
body 4 is shrunk, and the second piezoelectric body 5 is not displaced, resulting in bending in the
left direction as a whole. At time III, since both the piezoelectric members 4 and 5 are contracted,
the whole as a whole is contracted in the axial direction. At time IV, the first piezoelectric body 4
is not displaced, and the second piezoelectric is contracted, so that the overall bending occurs in
the right direction. At time V, since the first piezoelectric body 4 is expanded and the second
piezoelectric is contracted, bending as a whole occurs in the right direction. At time VI, the first
piezoelectric body 4 is stretched, and the second piezoelectric element is not displaced, and as a
whole, bending occurs in the right direction. At time VII, both piezoelectric members 4 and 5
extend together as a whole. At time VIII, the first piezoelectric body 4 is not displaced, and the
second piezoelectric element is stretched, so that a bending is generally generated in the left
direction. Therefore, as shown in FIG. 3C, an elliptical locus of displacement in the
counterclockwise direction occurs at any one point (for example, mass point M) of the tip surface
of the vibrator 1.
[0020]
In addition, the piezoelectric elements of the left and right first and second piezoelectric
members 4 and 5 have a phase difference of + 90 ° (the left piezoelectric (A phase) leads by 90
° with respect to the right piezoelectric (B phase)) When the a.c. drive voltage is applied, the
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vertical displacement of the left and right portions of the tip end surface of the elastic body 2
changes as shown in FIG. 4 (a). The movement of the left and right portions of the tip surface of
the elastic body 2 corresponding to each of the times I to VIII on the time axis of FIG. 4A is as
shown in FIG. 4B. That is, at time I, both the piezoelectric members 4 and 5 extend together as a
whole. At time II, the first piezoelectric body 4 is stretched, and the second piezoelectric body 5 is
not displaced, and as a whole, bending occurs in the right direction. At time III, the first
piezoelectric body 4 is expanded and the second piezoelectric body 5 is contracted, so that the
overall bending occurs in the right direction. At time IV, the first piezoelectric body 4 is not
displaced, and the second piezoelectric is contracted, so that the overall bending occurs in the
right direction. At time V, since both the piezoelectric members 4 and 5 are contracted, the whole
as a whole is contracted in the axial direction. At time VI, the first piezoelectric body 4 is
contracted, and the second piezoelectric element is not displaced, and as a whole, bending occurs
in the left direction. At time VII, the first piezoelectric body 4 is contracted and the second
piezoelectric element is extended, so that the overall bending occurs in the left direction. At time
VIII, the first piezoelectric body 4 is not displaced, and the second piezoelectric element is
stretched, so that a bending is generally generated in the left direction. Accordingly, as shown in
FIG. 4C, an elliptical locus of clockwise displacement occurs at any one point (for example, mass
point M) of the tip surface of the vibrator 1. That is, by changing the phase difference of the drive
voltage applied to both the piezoelectric members 4 and 5 by 180 °, the direction of the
elliptical trajectory can be changed.
[0021]
The elliptical trajectories of these displacements are similarly generated if the elastic body is not
limited to a cylindrical shape, but is partially hollow or entirely hollow rod-like. As described
above, the motions of the elastic body and the base are different in the low order mode and the
high order mode, but using the coupled system of the torsional vibration which is the high order
mode of the base and the bending primary vibration of the elastic body, The following features
are shown. (1) It is not necessary to select an elastic body to a specific length, and the axial
length of the vibrator can be shortened, which makes it possible to make it compact (thin). (2)
Since torsional vibration is used in the base, there is a node of vibration, so a strong supporting
and fixing method can be realized if supported by the node. (3) By selecting an optimal shape
that causes torsional vibration in the base, the electrical characteristics of the vibrator can be
improved, and an improvement in thrust as an actuator can be expected.
[0022]
According to the second aspect of the invention, when driving the piezoelectric body located on
the opposite side with respect to the first plane and the piezoelectric body located on the
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opposite side with respect to the second plane. In the case of driving, the moving direction of the
moving body is changed by 90 °.
[0023]
In the invention according to claim 3, since the rod-like elastic body is formed in a cylindrical
shape, and the base is formed in a rectangular shape in cross section, the manufacture becomes
easy.
The ultrasonic actuator using the vibrator of the present invention is a device, a device, etc.
which are required to be light in weight, low in speed and high in a special environment (under
high magnetic field, high vacuum, etc.) difficult to use with electromagnetic actuators. Suitable
for the purpose of direct drive to use.
[0024]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first
embodiment of the present invention will now be described with reference to FIGS. The vibrator
1 has a base 8 having a rectangular cross section, as shown in FIG. 5, a cylindrical elastic body 2,
a half ring-like piezoelectric element 4a, etc., a substantially half ring-like electrode plate 6a, etc.
And by fixing them with a fastener, an adhesive or the like.
[0025]
As shown in FIG. 6, the first piezoelectric member 4 and the second piezoelectric member are
separated on both sides of a plane including the axial center of the vibrator 1, that is, a plane (not
shown) including the axial center of the elastic body 2. The bodies 5 are arranged symmetrically.
The two piezoelectric members 4 and 5 are respectively constituted by two layers of piezoelectric
elements 4a, 4b, 5a and 5b, and electrode plates 6a and 6b disposed therebetween. The two
piezoelectric members 4 and 5 are arranged such that the polarization directions are different
from each other, and the upper and lower polarization directions are also parallel to the axial
direction of the vibrator 1 and opposite to each other. The polarization direction of each
piezoelectric element 4a etc. is indicated by an arrow.
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[0026]
The elastic body 2 is made of steel and has an outer diameter of 30 mm and a length of 23 mm,
and a female screw portion 2a of M10 is formed in the vicinity of the central portion, and a
hollow portion is formed at the back. Then, a hexagonal socket bolt 7 as a fastener is screwed to
the female screw portion 2 a via the base 8.
[0027]
The base 8 was made of steel, and had a constant width (35 mm), and had a thickness of 20 mm
and four lengths of 40, 75, 100, and 150 mm. Moreover, the width | variety was made constant
(35 mm), length was 100 mm and three types, thickness 10, 20, and 30 mm, were also prepared.
A hole 8a is formed at the center of the base 8, and a recess 9 for accommodating the head of the
hexagonal socket bolt 7 is formed at the bottom.
[0028]
Piezoelectric elements 4a etc. are made of PZT (polyzirconate zirconate / titanate-based
polycrystal), which is a half of a circular ring with an outer diameter of 30 mm, an inner diameter
of 10 mm and a thickness of 0.5 mm. There is. For the electrode plates 6a and 6b, a copper plate
having a thickness of about 0.1 mm and having a protrusion on the outside of a half ring with an
outer diameter of 30 mm and an inner diameter of 10 mm is used. Then, when the piezoelectric
members 4 and 5 in which the piezoelectric elements 4a and the like and the two electrode
plates 6a and 6b are stacked are disposed between the elastic body 2 and the base 8, there is a
gap between the end faces thereof. Each of the piezoelectric elements 4a and the like and the
electrode plates 6a and 6b have a shape in which the divided end faces are cut.
[0029]
Then, the electrode plate 6 a of the first piezoelectric body 4 was connected to the two-phase
oscillator 12 via the amplifier 10 and the phase shifter 11. The electrode plate 6 b of the second
piezoelectric body 5 was connected to the two-phase oscillator 12 via the amplifier 10. Also, the
base 8 was grounded. Since the elastic body 2 and the base 8 are in a state of being conducted to
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each other by the hexagonal socket bolt 7, the elastic body 2 is also grounded by grounding the
base 8.
[0030]
The dynamic admittance characteristics when the width W and the thickness T of the base 8 are
constant and the length L of the base 8 is changed, and the length L and the width W of the base
8 are constant Dynamic admittance characteristics when the thickness T is changed are shown in
FIGS. FIGS. 7 and 8 show dynamic admittance characteristics that can obtain the higher order
mode (a mode in which torsional vibration occurs in the base 8) shown in FIGS. 1 and 2. In the
figure, ○ indicates the resonance frequency (fo), Δ indicates the sharpness of the resonance (Q),
and ◇ indicates the dynamic admittance (Ymo).
[0031]
As shown in FIG. 7, when the width W and the thickness T of the base 8 are constant, the
dynamic admittance (Ymo) is the highest when the length L of the base 8 is 100 mm, and the
resonance frequency (fo) is It increased as the base 8 became longer. Moreover, when the
thickness T of the base 8 was 20 mm, the dynamic admittance (Ymo) became the highest.
[0032]
As shown in FIG. 8, when the length L and the width W of the base 8 were constant, the
resonance frequency (fo) decreased as the base 8 became thicker. Thus, the length L and
thickness T of the base 8 have optimum dimensions.
[0033]
From this result, the length of the base 8 is preferably about 3 times the width of the base 8, and
the thickness of the base 8 is preferably about 1/2 of the width of the base 8. The width of the
base 8 is estimated to be a value close to the diameter of the cylindrical elastic body.
[0034]
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The optimum dimensions of the base 8 in the case of using the cylindrical elastic body 2 having a
diameter of 30 mm and a length of 23 mm were a width of 35 mm, a length of 100 mm, and a
thickness of 20 mm.
Then, the vibration mode of the vibrator 1 was observed by double pulse laser holography. The
results are shown in FIGS. FIG. 9 shows the case of driving at a resonance frequency fo 周波 数
25 kHz (low order mode), and FIG. 10 shows the case of driving at a resonance frequency fo ≒
40 kHz (high order mode). It can be seen that the low order mode and the high order mode are
almost the same as the vibration state shown in FIG.
[0035]
Furthermore, in order to reconfirm that torsional vibration is generated in the base 8 in the highorder mode state, the points of six places (symbols A to F) of the base 8 were observed using a
laser Doppler vibrometer . The results are shown in FIG.
[0036]
It was found that the measurement points A, C, E and B, D, F had the same vibration displacement
waveform and were in a state of being shifted by 180 °. Since the vibration waveform is the
same at the point forming the diagonal of the base 8 and the phase of the vibration displacement
is different by 180 °, it can be said that the torsional vibration is apparently generated.
[0037]
Next, a steel piece serving as a moving body and a weight was prepared, and the thrust of the
vibrator 1 was measured. As shown in FIG. 13, the movable body 13 is placed on the tip of the
vibrator 1, and a force is applied to the spring SB in a direction (horizontal direction) orthogonal
to the axial direction of the vibrator 1. The weight SB of the weight (not shown) added to the
moving body 13 is changed by connecting only the SB, and the measurement value of the spring
only SB when the moving body 13 moves is used as the thrust Fd. The results are shown in FIG.
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[0038]
In the case of using the high-order mode (o), about 3.6 kg of thrust can be obtained with a weight
of about 11 kg. On the other hand, in the case of low-order mode utilization (marked with Δ), a
thrust of 0.7 kg was obtained with a weight of about 4 kg. However, when the weight of 4 kg or
more was added, in the low-order mode, the moving body 13 remained stationary and stopped.
From this result, it was found that higher mode use can withstand relatively high pressure and
high thrust can be obtained.
[0039]
Next, the movement of the vibrator 1 in the driving state of only the first piezoelectric body 4 (A
phase) was observed at the same driving frequency. As a result, it was found that the phase
difference of + 90 ° was given and almost the same movement as in the driven state. Similarly,
the movement of the vibrator 1 in the driven state of only the second piezoelectric body 5 (B
phase) was observed. As a result, it was confirmed that the movement was in the opposite
direction as compared with the driving state of only the first piezoelectric body 4 (A phase). That
is, it was found that the phase difference of −90 ° was given and almost the same movement as
in the driven state.
[0040]
From these facts, it was found that it is possible to change the direction of the elliptical trajectory
of the displacement of the vibrator 1 by changing the phase difference of the voltage applied to
the two piezoelectric members 4 and 5 or switching the drive source.
[0041]
This embodiment has the following effects.
(A) The vibrator 1 is driven by the coupled vibration of the bending primary vibration of the rodlike (cylindrical) elastic body 2 and the torsional vibration of the base 8, so that the elastic body 2
has a specific length. Since it is possible to shorten the axial length of the vibrator 1 and to make
it compact (thin). In addition, the vibrator 1 can sufficiently withstand relatively high pressure,
and high thrust can be obtained.
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[0042]
(B) Since the torsional vibration of the base 8 is used, the node of the vibration exists in the base
8. Therefore, if supported by the node, a strong supporting and fixing method of the vibrator 1
can be realized. (C) By selecting the optimal shape that causes torsional vibration in the base 8,
the electrical characteristics of the vibrator 1 can be improved, and an improvement in thrust as
an actuator can also be expected.
[0043]
(D) Since the shape of the elastic body 2 is cylindrical and the cross-sectional shape of the base 8
is rectangular, the manufacture of the elastic body 2 and the base 8 and, in turn, the manufacture
of the vibrator 1 become easy. (E) Since the elastic body 2 is fixed to the base 8 through the
fastener (hexagonal socket bolt 7), adhesive bonding is performed as a means for fixing the
piezoelectric elements 4a, 4b, 5a, 5b and the elastic body 2. As compared with the device
according to the above, it is possible to obtain stable vibration characteristics with less
displacement of the piezoelectric element at the time of driving.
[0044]
(F) When driving the vibrator 1, the change of the direction of the elliptical trajectory of the
displacement of the elastic body 2 changes the phase difference of the voltage applied to both
the piezoelectric bodies 4 and 5 or It becomes possible by changing the piezoelectric body to
drive while driving. Therefore, when it is used as a vibrator for actuator, the change of direction
of the moving body 13 is simplified.
[0045]
Second Embodiment A second embodiment will now be described with reference to FIG. This
embodiment is different from the above-described embodiment in that elastic members and
piezoelectric members are disposed on both sides of the base 8. That is, the elastic body 2 u and
the piezoelectric bodies 4 u and 5 u are fixed to the lower side of the base 8 symmetrically with
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the elastic body 2 and the piezoelectric bodies 4 and 5.
[0046]
Among the components, elastic body 2u, piezoelectric elements 4ua, 4ub, 5ua, 5ub and electrode
plates 6ua, 6ub are the elastic body 2, piezoelectric elements 4a, 4b, 5a, 5b and electrode plates
6a, 6b of the first embodiment. And each is the same. As a fastener, in place of the hexagonal
socket bolt 7, a stud 3 having male threads 3a at both ends is used, and the stud 3 is fixed to the
base 8 with the male threads 3a at both ends projecting from the base 8. ing. The elastic
members 2 and 2 u are fixed to the base 8 in a state in which the female screw portion 2 a is
screwed to the male screw portion 3 a of the implantation bolt 3. The upper and lower electrode
plates 6a and 6ua and the electrode plates 6b and 6ub are connected to the amplifier 10 in pairs.
[0047]
Also in this embodiment, the change of the phase difference of the voltage applied to the
piezoelectric members 4, 5, 4u, 5u or the switching of the drive source makes it possible to
change the direction of the elliptic locus of the displacement of the elastic body tip as in the
above embodiment. It can do. In this embodiment, in particular, it is also possible to switch the
combination of the piezoelectric members 5 and 4 u and the piezoelectric members 4 and 4 u in
the diagonal direction.
[0048]
Third Embodiment A third embodiment will now be described with reference to FIGS. In this
embodiment, as shown in FIG. 15, the four quarter-arc shaped piezoelectric members 14, 15, 16
and 17 about the axis of the vibrator 1 are shifted in phase by 90 degrees on the same plane. In
this state, the piezoelectric members 14, 15, 16 and 17 are disposed so as not to interfere with
each other. Each of the piezoelectric members 14, 15, 16, 17 is A-phase through the electrode
plates 14c, 15c, 16c, 17c disposed between the pair of piezoelectric elements 14a, 14b, 15a,
15b, 16a, 16b, 17a, 17b. Alternatively, the B phase AC drive voltage is applied respectively.
[0049]
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14
The electrode plate 14c is connected to the two-phase oscillator 12 via the amplifier 10 and the
phase shifter 11, so that the voltage of the A phase is applied. In the electrode plate 15c, a state
in which the voltage of A phase is applied from the two phase oscillator 12 through the amplifier
10 and the phase shifter 11 and a state in which a voltage of B phase is applied from the two
phase oscillator 12 through the amplifier 10 It is configured to be switched and connected via
the switch 18. The electrode plate 16c is connected to the two-phase oscillator 12 via the
amplifier 10 so that a B-phase voltage is applied. In the electrode plate 17c, a state in which the
voltage of A phase is applied from the two phase oscillator 12 through the amplifier 10 and the
phase shifter 11 and a state in which a voltage of B phase is applied from the two phase
oscillator 12 through the amplifier 10 It is configured to be switched and connected via the
switch 19. The two switches 18 and 19 are interlocked with each other. When the electrode plate
15c is connected to the A phase, the electrode plate 17c is connected to the B phase, and when
the electrode plate 15c is connected to the B phase, the electrode plate 17c is A phase It is
supposed to be connected with
[0050]
Therefore, in the state where the switch 18 is connected to the A phase, ie, in the state where the
switch 19 is switched to the B phase, the vibrator 1 includes the axis of the vibrator 1 as shown
in FIG. The piezoelectric bodies 14 and 15 connected to the A phase and the piezoelectric bodies
16 and 17 connected to the B phase are respectively provided on different sides with respect to a
first plane parallel to the end face facing the piezoelectric body 16 It will be placed. When the
oscillator 1 is driven by two-phase drive by giving a phase difference of + 90 ° to the A-phase
and the B-phase, the oscillator vibrates about the first plane, similarly to the oscillator 1 of the
first embodiment. When moving the moving body on the tip surface, the moving body is moved
to the left side of FIG. When a phase difference of −90 ° is given to the A phase and the B
phase and the vibrator 1 is driven by two-phase driving, the moving body is moved to the right
side of FIG.
[0051]
Further, in the state where the switch 18 is connected to the B phase, that is, in the state where
the switch 19 is switched to the A phase, the vibrator 1 includes the axis of the vibrator 1 as
shown in FIG. Piezoelectric bodies 14 and 17 connected to the A phase on different sides of a
second plane parallel to the end face facing the piezoelectric body 14 (piezoelectric body 17) and
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the piezoelectric body 15 (piezoelectric body 16); The piezoelectric members 15 and 16
connected to the B phase are in a state of being disposed. Then, when the oscillator 1 is driven by
two-phase drive by giving a phase difference of + 90 ° to the A phase and the B phase, it
oscillates around the second surface, and similarly to the oscillator 1 of the first embodiment
When moving the moving body on the tip surface, the moving body is moved to the right side of
FIG. When a phase difference of −90 ° is given to the A phase and the B phase and the vibrator
1 is driven by two-phase driving, the moving body is moved to the left side of FIG.
[0052]
That is, the vibrator 1 of this embodiment can move the movable body with the same thrust as
the vibrator 1 of the first embodiment without increasing the overall shape, and switches the
switches 18 and 19. By selecting the piezoelectric members 14, 15, 16, 17 to be driven, the
moving direction of the moving member can be switched between the arrow EW direction and
the arrow NS direction in FIG.
[0053]
Fourth Embodiment Next, an embodiment applied to an actuator using a large number of
vibrators 1 will be described according to FIG.
A plurality (three in this embodiment) of vibrators 1 are disposed along the longitudinal direction
(left and right direction in FIG. 18) of the long movable body 13. A guide roller 20 is disposed on
the opposite side of the movable body 13 to the vibrator 1. The vibrator 1 is configured
substantially the same as the vibrator 1 of the first embodiment. The base 1 of the vibrator 1 is
fixed to the support frame 21. The base 8 is fixed to the support frame 21 at a node of the
vibration by a fastener such as a bolt (not shown). The guide roller 20 is disposed in a state of
pressing the movable body 13 to the vibrator 1 side via a pressing means (not shown) such as a
spring. The electrode plate 6a of the first piezoelectric body 4 of each vibrator 1 is connected to
the common AC drive source 22, and the electrode plate 6b of the second piezoelectric body 5 is
connected to the common AC drive source 23. (Amplifier, phase shifter, etc. are not shown).
[0054]
When voltages are applied from the AC drive sources 22 and 23 with a phase difference of + 90
° with respect to the first piezoelectric body 4 and the second piezoelectric body 5 of each
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vibrator 1, the tip of each vibrator 1 is shown in FIG. An elliptical trajectory, which is a
counterclockwise displacement, is generated, and the moving body 13 is moved in the left
direction of FIG. In addition, when a voltage of -90 ° phase difference is applied to each of the
piezoelectric bodies 4 and 5, an elliptical locus, which is a clockwise displacement in FIG. 13 is
moved to the right in FIG. That is, in the actuator using the large number of vibrators 1, it is
possible to change the moving direction of the moving body 13 by changing the phase difference
between the voltages applied to the two AC drive sources 22 and 23.
[0055]
The present invention is not limited to the above embodiments, and may be embodied as follows,
for example. (1) As shown in FIG. 19, the piezoelectric elements 4a and 4b constituting the first
piezoelectric body 4 disposed between the elastic body 2 and the base 8 and the piezoelectric
elements constituting the second piezoelectric body 5 The elements 5a and 5b may each have
four layers, or may have an even layer structure of four or more layers. The ground electrode 24
is disposed between the adjacent pair of piezoelectric elements. In this case, the displacement
increases. Also in the piezoelectric members 4, 5, 14, 15, 16 and 17 of the first embodiment and
the third embodiment, the piezoelectric elements 4a, 4b, 5a, 4 and 5 of the piezoelectric
members 4 and 5, etc. If 5b etc. are made an even number structure of four or more layers,
displacement will be expanded.
[0056]
(2) As shown in FIG. 20, the central axis of the vibrator 1 among the piezoelectric members 14,
15, 16, 17 disposed at a positional phase difference of 90 ° between the elastic member 2 and
the base 8. The A-phase and B-phase AC drive voltages are applied through the electrode plates
14c and 16c respectively to the piezoelectric members 14 and 16 disposed at mutually opposing
positions across the electrode (oscillator, phase shifter, amplifier Etc. not shown). In addition, AC
drive voltages of C phase and D phase are respectively applied to the piezoelectric members 15
and 17 via the electrode plates 15c and 17c (oscillator, phase shifter, amplifier and the like are
not shown). In this case, the movable body is switched by switching to a state in which the
vibrator 1 is driven by two-phase driving of A phase and B phase, and a state in which the
vibrator 1 is driven by two-phase driving of C phase and D phase. The direction of movement of
can be changed by 90 °.
[0057]
04-05-2019
17
(3) The shape of the elastic body 2 is not limited to a cylindrical shape, and the cross-sectional
shape orthogonal to the axial direction may be a polygonal pillar such as a quadrangle, a triangle,
a hexagon, or an octagon, or a hollow rod. Then, as the first piezoelectric body 4 and the second
piezoelectric body 5 or the like, a ring-shaped piezoelectric element corresponding to a half or a
shape divided into four is used.
[0058]
(4) The shape of the base 8 is not limited to the rectangular cross section, as long as torsional
vibration is easily generated in the base 8. That is, the cross section of the base 8 may be square,
circular, oval or the like. In addition, it may have an odd-shaped combined cross-section that
partially combines rectangular and square. In addition, a hole, a slit or the like may be provided
at a node position of vibration.
[0059]
(5) The thicknesses of the piezoelectric elements 4a, 4b, etc., the electrode plates 6a, 6b, etc. may
be different from those in the above embodiment. (6) As a means for laminating the elastic body
2 and the piezoelectric elements 4a, 4b, 5a, 5b, etc., another bolt may be used instead of using
the hexagonal socket bolt 7. Further, as shown in FIG. 21, the male screw 2b is protruded from
the elastic body 2, and the male screw 2b is screwed into the screw hole 8b formed on the base 8
side, so that the piezoelectric elements 4a, 4b, 5a, 5b, etc. May be clamped between the elastic
body 2 and the base 8. Further, the form is not limited to the form of fastening and fixing by a
fastener or the like, and a form of bonding and bonding may be employed. However, it is more
preferable to fix by means of a fastener or the like than fixing by adhesive bonding. Also, in order
to make handling before fixing on the base 8 etc convenient, the elastic body 2 and the
piezoelectrics 4 and 5 etc are temporarily fixed with an adhesive, and for fixing on the base 8 etc,
a fastener is used It may be done to
[0060]
(7) As shown in FIG. 22, the third piezoelectric body 25 may be disposed on the lower side of the
first and second piezoelectric bodies 4 and 5 across the both sides of the plane of symmetry of
04-05-2019
18
bending vibration. The third piezoelectric body 25 is composed of ring-shaped piezoelectric
elements 25a and 25b and a ring-shaped electrode plate 25c disposed therebetween.
[0061]
The inventions other than those described in the claims that can be grasped from the
embodiments and the modifications will be described together with the effects thereof. (1) The
vibrator according to claim 1 and a power supply unit capable of switching the phase difference
of the voltages applied to the first and second piezoelectric members constituting the vibrator at
± 90 ° or around Ultrasonic actuator. In this case, the moving direction of the moving body can
be easily switched with a simple configuration in which the phase difference of the applied
voltage is switched at or around ± 90 °.
[0062]
(2) The four piezoelectric members according to claim 2 are disposed so as to be positioned two
by two on both sides of the first surface and the second surface, and the electrode plate provided
on each of the piezoelectric members is A state in which the same voltage is applied to each of
two piezoelectric bodies located on the same side across the first surface, and a state in which
two piezoelectric bodies located on the same side across the second surface are respectively It is
configured to be connected to the power supply via the switchable switch when the same voltage
is applied. In this case, the moving direction of the movable body can be switched to four
directions by switching the connection state of the piezoelectric body to be driven and the power
source by switching the switch, and a large thrust can be obtained without enlarging the overall
shape of the vibrator. Can be secured.
[0063]
(3) The vibrator according to claim 2 or (4) and the four piezoelectric members constituting the
vibrator are located on the opposite side of a first plane including the axis of the vibrator.
Provided with a power supply unit that applies a drive voltage to the piezoelectric bodies or
between the piezoelectric bodies located on the opposite side across the second plane while
switching the phase difference of the applied voltage at ± 90 ° or around Ultrasonic actuator.
In this case, the moving direction of the movable body can be easily changed to four directions
by a simple configuration in which the phase difference of the applied voltage is switched at ±
04-05-2019
19
90 ° or around.
[0064]
(4) In the invention according to any one of claims 1 to 3, (1) to (3), the rod-like elastic body is
fixed to the base via a fastener. In this case, as compared with the case where the piezoelectric
element and the elastic body are fixed (laminated) by the adhesive, the piezoelectric element is
less likely to be displaced during driving, and stable vibration characteristics can be obtained.
[0065]
As described above in detail, according to the first to third aspects of the present invention, the
length of the rod-like elastic body of the vibrator is shortened to couple with the base (synthesis
(synthesis) ) By realizing the vibration, it is possible to realize compactification and obtain a
higher thrust.
[0066]
According to the second aspect of the present invention, the moving direction of the movable
body can be changed to four orthogonal directions (for example, four directions of front and rear,
right and left).
According to invention of Claim 3, manufacture of a rod-shaped elastic body and a base becomes
easy.
[0067]
Brief description of the drawings
[0068]
Fig. 1 A schematic view showing the configuration of the vibrator and the vibration mode.
[0069]
Fig. 2 Graph showing the dynamic admittance characteristics of the oscillator.
04-05-2019
20
[0070]
Fig. 3 (a) is a graph showing the time change of displacement of the tip surface when driven with
a phase difference of -90 °, (b) is a schematic view of the displacement of the tip surface, (c) is a
diagram showing the elliptical locus of displacement. .
[0071]
4 (a) is a graph showing the time change of displacement of the tip surface when driven with a
phase difference of + 90 °, FIG. 4 (b) is a schematic view of the displacement of the tip surface,
and FIG. 4 (c) is a diagram showing an elliptical locus of displacement.
[0072]
FIG. 5 shows components of the vibrator according to the first embodiment, wherein (a) is a
perspective view of a piezoelectric element, (b) is a perspective view of an electrode plate, (c) is a
perspective view of an elastic body, (d) Is a perspective view of a base.
[0073]
FIG. 6 is a schematic view showing a configuration of a vibrator of the first embodiment.
[0074]
Fig. 7 Graph showing dynamic admittance characteristics when base length is changed.
[0075]
Fig. 8 Graph showing dynamic admittance characteristics when base thickness is changed.
[0076]
Fig. 9 is a schematic view showing a photograph of the low-order mode vibration mode of the
vibrator by double pulse laser holography, wherein (a) is a top view (view from arrow A), (b) is a
front view (view from arrow B) Figure, (c) is a bottom view (arrow C).
[0077]
Fig. 10 is a schematic view showing a photograph of the vibration mode of the high-order mode
of the vibrator by double pulse laser holography as a schematic view, wherein (a) is a top view
04-05-2019
21
(view from arrow A) and (b) is a front view (view from arrow B) Figure, (c) is a bottom view
(arrow C).
[0078]
11 is a schematic view showing the vibration velocity waveform of the vibrator and the
movement of the vibrator.
[0079]
12 is a diagram showing the relationship between the thrust of the vibrator and the weight of the
weight.
[0080]
13 is a schematic view showing a method of measuring the thrust of the vibrator.
[0081]
14 is a schematic view showing a configuration of a vibrator of the second embodiment.
[0082]
15 is a schematic plan view showing the arrangement of the piezoelectric body and the electrode
plate of the third embodiment.
[0083]
Similarly FIG. 16 is a schematic perspective view of a vibrator.
[0084]
Fig.17 (a) is a model front view of a vibrator | oscillator, (b) is a model side view which looked at
a vibrator | oscillator from the piezoelectric materials 16 and 17 side.
[0085]
18 is a schematic view of an actuator according to the fourth embodiment.
[0086]
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22
The model front view of the vibrator | oscillator of the modification of FIG.
[0087]
20 is a schematic plan view showing the arrangement of the piezoelectric body and the electrode
plate of the vibrator of another modified example of FIG.
[0088]
21 is a schematic cross-sectional view of a vibrator of another modified example of FIG.
[0089]
The model front view of the vibrator | oscillator of the example of another change of FIG.
[0090]
23 is a schematic exploded perspective view of the conventional device.
[0091]
24 is a schematic view showing the displacement of another transducer.
[0092]
Explanation of sign
[0093]
DESCRIPTION OF SYMBOLS 1 ... vibrator | oscillator 2 elastic body 4 1st piezoelectric body 4a,
4b piezoelectric element 5 2nd piezoelectric body 5a 5b piezoelectric element 7 hexagonal bolt
with bolt as a fastener 8, 8: base, 14-17: piezoelectric body, 14a-17a, 14b-17b: piezoelectric
element.
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