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JPH09271187

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DESCRIPTION JPH09271187
[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, Japanese
Patent Application Laid-Open No. 63-316674 proposes a piezoelectric vibrator capable of
drawing a locus of curve closure in an arbitrary direction by an electric signal at the tip of the
vibrator. ing. As shown in FIG. 24, in the piezoelectric vibrator 51, a first piezoelectric element
51a having two regions whose polarization directions are opposite to each other and a second
piezoelectric element 51b having the same polarization direction in all the regions are the basis.
It laminates on both sides of electrode 52c. Electrodes 52a and 52b are formed on the first
piezoelectric element 51a so as to face the reference electrode 52c and to divide the piezoelectric
element 51a into two regions. An electrode 52d is formed on the second piezoelectric element
51b so as to face the reference electrode 52c. The vibrator 53 is bonded to the electrodes 52 a
and 52 b of the piezoelectric vibrator 51. Then, in a state where the electrodes 52a and 52b are
short-circuited by the lead wire 54a, a periodic voltage is applied to the first piezoelectric
element 51a from the alternating current power supply 55a via the lead wires 54a and 54b, and
the lead wire 54b is applied to the second piezoelectric element 51b. , 54c to apply a periodic
voltage from the AC power supply 55b.
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[0003]
When a periodic voltage is applied only to the first piezoelectric element 51 a, the piezoelectric
element 51 a causes the tip 53 a of the vibrating body 53 to reciprocate along an arc-like locus.
When a periodic voltage is applied only to the second piezoelectric element 51 b, the
piezoelectric element 51 b causes the tip 53 a of the vibrating body 53 to reciprocate along a
linear trajectory in the central axis direction of the vibrating body 53. Therefore, vibration is
generated by combining the vibrations generated by the first and second piezoelectric elements
51a and 51b by making the periods of the voltages applied to the two piezoelectric elements 51a
and 51b different or making the phases different in the same period. The tip portion 53a of the
body 53 can generate a vibration forming a locus of a closed curve.
[0004]
In addition, as shown in FIG. 25, in JP-A-6-197572, a cylindrical metal block 61, a ring-shaped
piezoelectric vibrator 62, divided electrodes 63a and 63b, a ring-shaped piezoelectric vibrator
64, a ring-shaped electrode 65 and A vibration type drive means (vibrator) 68 is proposed, in
which metal blocks 66 are stacked in an abutting state one after another and clamped and fixed
with a screw 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.
[0005]
SUMMARY OF THE INVENTION In the piezoelectric vibrator disclosed in JP-A-63-316674, since
the first piezoelectric element 51a has different polarization directions on the left and right sides,
the vicinity of the center of the piezoelectric element is used. At the boundary between the two,
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there is an unpolarized region, and it is difficult to apply uniform polarization processing to the
left and right, so it is difficult to match the left and right vibration characteristics. In addition, the
first piezoelectric element 51a causes reciprocal vibration in an arc shape at the tip portion 53a
of the vibrating body 53 by the maximum displacement of the left and right ends. Therefore, in
order to increase the displacement of the arc-shaped reciprocating vibration, the distance
between the left and right ends of the first piezoelectric element 51a is made large.
[0006]
Further, the polarization direction of the first piezoelectric element 51a is different between the
right side and the left side. As a result, as shown in FIG. 26A, when the upper side of the left side
of the piezoelectric vibrator 51 extends, the lower side shrinks, and when the lower side extends,
the upper side shrinks. In addition, as shown in FIG. 26 (b), the right side expands and contracts
in the same manner. Therefore, in the case where the first piezoelectric element 51a has the
second piezoelectric element 51b, the right and left vibrations are different, and the piezoelectric
element is integrally formed. Therefore, the first piezoelectric element 51a is affected by both
vibration displacements. As a result, the vibration displacement of the entire vibrator can be
suppressed to a small value, which may result in a vibrator with low efficiency.
[0007]
Furthermore, although it has also been proposed to laminate a plurality of first piezoelectric
elements 51a and a plurality of second piezoelectric elements 51b in order to expand the
vibration displacement, the first non-uniform vibration displacement characteristic described
above is produced. Since the combination of the piezoelectric element 51a and the second
piezoelectric element 51b is selected, it is considered that the effect can not be expected so
much. Therefore, although this piezoelectric vibrator is effective as a relatively low-thrust
actuator vibrator as judged from its structure, it is not suitable for an actuator vibrator which is
small and requires a large thrust.
[0008]
In the apparatus disclosed in Japanese Patent Application Laid-Open No. 6-197572, the
longitudinal resonance and the bending resonance are utilized in a structure in which the
piezoelectric vibrators 62 and 64 are sandwiched between the metal blocks 61 and 66.
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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.
[0009]
In order to solve the above-mentioned problems, the inventor of the present invention has
proposed a vibrator for an ultrasonic actuator that utilizes synthesis (coupling) vibration of the
expansion and contraction vibration of the piezoelectric element and the vibration other than the
expansion and contraction vibration due to the shape of the entire vibrator. No. 7-196774). As
shown in FIG. 27, in this vibrator 71, a first piezoelectric body 73 and a second piezoelectric
body 74 are disposed between a pair of circular ring-shaped elastic bodies 72, and a hexagonal
socket bolt 75 and a nut 76 are provided. Is fixed by means of a washer 77. The two piezoelectric
members 73 and 74 are composed of half ring-shaped piezoelectric elements 73a, 73b, 74a and
74b polarized in opposite directions, and electrode plates 78a and 78b disposed therebetween,
and They are symmetrically arranged on both sides of a central plane parallel to the axial
direction.
[0010]
In this vibrator 71, the electrode plate 78a of the first piezoelectric body 73 is connected to the
two-phase oscillator 81 via the amplifier 79 and the phase shifter 80, and the electrode plate 78b
of the second piezoelectric body 74 is connected via the amplifier 79. It is connected to the phase
oscillator 81, and used in a state in which both elastic bodies 72 are grounded. The vibrator 71
changes the phase difference of the voltage applied to the first and second piezoelectric members
73 and 74, and when driven with a predetermined frequency voltage, the trajectory of the curve
closure on the tip of the vibrator 71 or the like The resulting vibration is generated.
[0011]
Since this vibrator 71 is a vibrator which does not utilize a specific resonance system, when it is
used as an actuator, its thrust is on the order of several hundreds of grams when one vibrator is
used. In addition, although there is a degree of freedom in the design because a specific
resonance system is not used, design for obtaining high thrust has been difficult.
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[0012]
The present invention has been made in view of the above-described conventional problems, and
its object is to provide a vibration for an ultrasonic actuator which can withstand a large pressing
force of a moving body by using a specific resonance system and obtain high thrust. It is to
provide a child.
[0013]
In order to achieve the above object, in the invention according to claim 1, piezoelectric elements
are arranged in at least two layers in the axial direction of the vibrator, and at least two of them
are arranged. The piezoelectric element is divided into a first piezoelectric body and a second
piezoelectric body at a boundary parallel to the axial direction, and the first piezoelectric body
and the second piezoelectric body are respectively Piezoelectric elements whose polarization
directions are parallel to the axial direction and opposite to each other on different sides of a
plane orthogonal to the axial direction, and rod elastic at the first axial end of the piezoelectric
element When one end of the body is fixed, and the length of the rod-like elastic body is the
second end of the piezoelectric element as the fixed end, the bending secondary vibration is
concomitantly excited when the rod-like elastic body performs longitudinal primary resonance
vibration. The length to be
[0014]
In the invention according to claim 2, the piezoelectric elements are disposed in at least two
layers in the axial direction of the vibrator, and at least two layers of the piezoelectric elements
are arranged at 90 ° around the axis of the vibrator. Divided into four piezoelectric bodies at a
phase-shifted position, one set of piezoelectric bodies is disposed on different sides with respect
to the first plane including the axis of the vibrator, and the other set of piezoelectric bodies is
Piezoelectric elements that are arranged on different sides of a second plane that includes the
axis of the vibrator and is orthogonal to the first plane, and whose polarization directions are
parallel to the axial direction and opposite to each other And fixing one end of the rod-like elastic
body to the first end in the axial direction of the piezoelectric element, and setting the length of
the rod-like elastic body to the second end of the piezoelectric element as the fixed end In the
case of longitudinal primary resonance vibration, the bending secondary vibration was
accompanably excited.
[0015]
In the invention according to claim 3, in the invention according to claim 1 or 2, a groove-like
neck portion is formed in the vicinity of a portion which becomes a node of vibration of the
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vibrator in the rod-like elastic body.
[0016]
In the invention according to claim 4, in the invention according to any one of claims 1 to 3, a
vibrator is supported on the rod-like elastic body by a fixing portion at a second end side of the
piezoelectric element. The female screw part by which the fastener for doing is screwed is
formed.
[0017]
In the vibrator according to the first aspect of the present invention, as shown in FIG. 1, the
vibrator 1 is cantilevered at the fixing portion 3 whose base end is a rigid body on the side where
the rod-like elastic body 2 faces the piezoelectric element. It is fixed by the state and used.
Then, when a phase difference of 90 ° is given to the first piezoelectric body 4 and the second
piezoelectric body 5 at the longitudinal primary resonance length resonance frequency of the
elastic body 2 and an AC drive voltage is applied, the elastic body 2 becomes 1 longitudinal The
bending secondary vibration is concomitantly excited when the next resonance vibration is
performed.
The expansion and contraction vibration of the first piezoelectric body 4 and the second
piezoelectric body 5 disposed on both sides of a plane parallel to the axial direction of the
vibrator 1 makes it possible to obtain I to shown in FIGS. This produces a displacement of the IV
process.
[0018]
In the step I of FIG. 2A, the first and second piezoelectric members 4 and 5 are both stretched,
and as a whole, they are stretched in the axial direction.
In the step II of FIG. 2B, the second piezoelectric body 5 is expanded and the first piezoelectric
body 4 is shrunk, so that the overall bending occurs in the left direction.
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In the step III of FIG. 2 (c), the first and second piezoelectric members 4 and 5 are both shrunk so
that the whole as a whole is shrunk in the axial direction.
In the step IV in FIG. 2D, the first piezoelectric body 4 is stretched and the second piezoelectric
body 5 is contracted, so that the overall bending occurs in the right direction.
[0019]
Therefore, as shown in FIG. 3A, any one point (for example, the mass point M) of the tip end face
2a of the elastic body 2 performs the motion of the elliptical trajectory Q. When an alternating
current drive voltage is applied with a phase difference that the second piezoelectric body 5 is
delayed by 90 ° with respect to the first piezoelectric body 4, in-plane distortion in the vicinity
of the tip portion of the vibrator 1 is as shown in FIG. The movement of the mass point M is an
elliptical locus Q in the counterclockwise direction, as shown in FIG. 3B. Therefore, when the
movable body is placed on the end face 2 a of the elastic body 2, the direction change becomes
possible by changing the phase difference of the drive voltage applied to both the piezoelectric
bodies 4 and 5 by 180 °.
[0020]
Further, switching of the direction of the elliptical trajectory, ie, change of direction of the
moving body is performed by switching between driving of only the first piezoelectric body 4
(phase A) and driving of only the second piezoelectric body 5 (phase B). It becomes possible.
[0021]
Since the vibrator of the present invention utilizes the longitudinal primary length resonance
vibration of the rod-like elastic body, a large vibration amplitude can be obtained.
In addition, since one side of the vibrator is supported by a rigid body to form a fixed part, it can
withstand a large pressing force applied to the vibrator, and an actuator with a higher thrust can
be obtained compared to a conventional ultrasonic actuator vibrator. . Further, by appropriately
selecting the length and the shape of the rod-like elastic body of the vibrator corresponding to
the primary longitudinal resonance frequency, there is an advantage that the design of the
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vibrator for obtaining a high thrust can be simplified.
[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
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 the third aspect, the sharpness of resonance and the dynamic
admittance become better as compared with the case where the groove-like neck portion is not
formed in the vicinity of the portion which becomes the node of vibration of the vibrator.
[0024]
In the invention according to claim 4, the vibrator is supported by the fixed portion (rigid body)
on the second end side of the piezoelectric element through the fastener screwed to the female
screw portion formed in the rod-like elastic body. .
As a means for fixing (stacking) the piezoelectric element and the elastic body, it is more difficult
for the piezoelectric element to shift during driving when it is fixed using a fastener compared to
that by adhesive bonding, and stable vibration characteristics can be obtained. it can.
[0025]
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 use in
[0026]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first
embodiment of the present invention will now be described with reference to FIGS.
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The vibrator 1 is a combination of a cylindrical elastic body 2 as shown in FIG. 5, a half ringshaped piezoelectric element 4a, etc. and a substantially half ring-shaped electrode plate 6a etc.
It is formed by fastening and fixing to the base 8 with the hexagonal socket bolt 7.
[0027]
As shown in FIG. 4, the first piezoelectric body 4 and the second piezoelectric body 5 are
symmetrically arranged on both sides of a central plane parallel to the axial direction of the
vibrator 1.
The two piezoelectric members 4 and 5 are polarized in opposite directions (on different sides of
the plane perpendicular to the axial direction of the vibrator 1, the polarization directions are
parallel to the axial direction of the vibrator and opposite to each other) Of the piezoelectric
elements 4a, 4b, 5a, 5b, and electrode plates 6a, 6b disposed therebetween. The polarization
direction of the piezoelectric element 4a or the like is indicated by an arrow.
[0028]
The elastic body 2 is made of steel and has an outer diameter of 30 mm and a female screw
portion 2b of M10 formed in the vicinity of the central portion, and a hollow portion is formed at
the back of the same. Then, the hexagonal socket bolt 7 is screwed into the female screw 2b. As
the elastic body 2, four types of length 20 mm, 30 mm, 40 mm, and 50 mm were prepared.
[0029]
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
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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. The base 8 is
made of steel and is a block with a length of 100 mm and a thickness of 20 mm. A hole 8a is
formed at the center of the block, and the head of the hexagonal socket bolt 7 is accommodated
at the bottom. A recess 9 is formed.
[0030]
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
each other by the hexagonal socket bolt 7, the elastic body 2 is also grounded by grounding the
base 8.
[0031]
With the base 8 fixed by a plastic vise, the resonance frequency was measured for the vibrator 1
using four types of elastic bodies 2. The results are shown in FIG. In FIG. 6, the vertical axis
represents the longitudinal primary resonance frequency f (kHz), and the horizontal axis
represents the length L of the elastic body 2 of the vibrator 1. In the figure, black circles indicate
the resonance frequencies of the four types of vibrators 1 obtained by measurement, and solid
lines indicate that the material of the vibrator 1 is steel, and the longitudinal primary resonance
frequency obtained under the conditions of one end fixing and the other end free Indicates the
calculated value. The value of the oscillator 1 actually produced was about 1 to 2 kHz higher
than the calculated value, but it was almost the same as the calculated value. Therefore, the drive
(resonance) frequency of the vibrator can be estimated by performing the above-described
correction on the calculated value.
[0032]
Next, in order to examine whether or not it can be used as a vibrator for an actuator, using the
vibrator 1 having a length of 50 mm of the elastic body 2, a voltage is applied to the first
piezoelectric body 4 and the second piezoelectric body 5. The oscillator 1 was driven at a drive
frequency of 19.5 kHz by giving a phase difference of + 90 °. Then, while the bearing was
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pressed against the vibrator 1 (elastic body 2), the rotational direction of the bearing was
observed. The results are shown in FIG. 7 (a).
[0033]
On the end face of the elastic body 2, the bearing was rotated in the left direction
(counterclockwise direction) over the entire area. On the other hand, on the circumferential
surface of elastic body 2, a second surface orthogonal to the first surface P1 (shown by a chain
line in FIG. 8) including the central axis of elastic body 2 in parallel with the gap between the
opposing end faces of piezoelectric bodies 4 and 5. In the movement at a position intersecting
with the plane P2 (shown by a chain line in FIG. 8), there is a node portion where the rotation of
the bearing stops around 11 to 12 mm from the tip end surface. It turned out that the direction
changed. That is, an elliptical locus of displacement in the right direction (clockwise direction) is
generated from about the base 8 to about 75 to 80% of the length of the elastic body 2, and the
tip end side has an opposite direction.
[0034]
The elliptical trajectory of the displacement of the peripheral surface of the elastic body 2 most
notably occurs on the line intersecting the second surface P2, and the displacement does not
occur on the line intersecting the first surface P1. Next, the driving frequency was fixed at 19.5
kHz, the voltage phase difference was changed from + 90 ° to −90 °, and the rotation
direction of the bearing was observed. The result is shown in FIG. 7 (b). It was confirmed that the
rotational direction of the bearing pressed against the end face of the vibrator 1 was in the right
direction (clockwise direction) and in the opposite direction to the case of the phase difference of
+ 90 °. Further, it was also confirmed that the rotational direction of the bearing on the
circumferential surface of the elastic body 2 is also reverse to that in the case of the phase
difference of + 90 °.
[0035]
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, as shown in FIG. 7 (c), it was
found that the movement was almost the same as in the state (FIG. 7 (a)) driven with a phase
difference of + 90 °. Similarly, the movement of the vibrator 1 in the driven state of only the
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second piezoelectric body 5 (B phase) was observed. As a result, it was confirmed that the
movement was in the reverse direction as compared with the driving state of only the A phase.
That is, as shown in FIG. 7 (d), it was found that the movement was almost the same as in the
state (FIG. 7 (b)) driven with a phase difference of −90 °.
[0036]
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.
[0037]
Next, the state of the vibrator 1 was observed in a non-contact state using a laser Doppler
vibration (velocity) meter.
In order to obtain the results of FIGS. 7 (a) to 7 (d), with respect to the portions observed using
the bearings, measurements were made for the vibrator 1 in which the lengths of the elastic
bodies 2 differ. The measurement results are shown in FIG. In FIG. 9, the vibration velocity
waveform a corresponds to the position of the tip of the elastic body 2 shown by a, the vibration
velocity waveform b corresponds to the position shown by b of the elastic body 2, and the
vibration velocity waveform c shows c of the elastic body 2 It corresponds to the position shown
by. The movement of the vibrator 1 is in the vicinity of about 75 to 80% of the length L of the
elastic body 2 of all the vibrators 1 as in the observation with the bearings, and there are
vibration node parts, and the vibration at the upper and lower ends There was a phase change of
the velocity (X direction component in FIG. 9), and it was confirmed that the direction of
vibration was changed.
[0038]
The measurement results are obtained by measuring bending secondary vibration components
(corresponding to the step II and step IV in FIG. 2) in the in-plane strain of the entire vibrator 1
shown in FIG. As is apparent from FIG. 9, the bending secondary vibration (vibration in the X
direction in FIG. 9) can be concomitantly excited at a length at which the elastic body 2 resonates
in the primary longitudinal length (vibration in the Y direction in FIG. 9).
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[0039]
The relationship between the amplitude ratio Y / X in the X and Y directions of the vibrator 1
and the length L of the elastic body 2 when the length of the elastic body 2 of the vibrator 1 is
changed is shown in FIG. It can be seen that the value of the amplitude ratio Y / X of the vibrator
1 can be changed to about 1.8 to 3.0 when the length L of the elastic body 2 is 20 to 50 mm.
[0040]
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. 11, the movable body 13 is mounted on the tip of the
vibrator 1, and the movable body 13 and the spring are applied with a force 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 thrust Fd was also measured for the vibrator 71 shown in FIG. 27 for
comparison. The results are shown in FIG. In the figure, the broken line shows the result of the
vibrator 71 and the solid line shows the result of the vibrator 1.
[0041]
The vibrator 71 obtained a thrust of about 500 g with a weight of 7 kgf, but did not move the
movable body when a weight exceeding 7 kgf was added. On the other hand, in the case of the
vibrator 1, a thrust of 2.5 kg was obtained with a weight of 10 kgf. Although the movable body
13 still moved even when the weight weight was 10 kgf or more, the measurement was
interrupted at the weight weight 10 kgf. From this result, it has been found that the vibrator 1 of
the present invention can sufficiently withstand relatively high pressure and high thrust can be
obtained.
[0042]
This embodiment has the following effects. (A) The vibrator 1 is driven in a cantilevered state
with one end thereof fixed to the fixed portion (base 8) of the rigid body, and bending secondary
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vibration occurs when the rod-like elastic body 2 vibrates in primary longitudinal resonance. It is
excited concomitantly. As a result, the vibrator 1 can sufficiently withstand relatively high
pressure and high thrust can be obtained.
[0043]
(B) The rod-like elastic body 2 is formed with the female screw portion 2b to which the fastener
(hexagonal socket bolt 7) for supporting the vibrator 1 on the fixing portion (base 8) is screwed.
As a means for fixing (laminating) the elements 4a, 4b, 5a, 5b and the elastic body 2, the
piezoelectric element is less likely to be displaced at the time of driving, and stable vibration
characteristics can be obtained as compared with those by adhesive bonding.
[0044]
(C) The tightening portion by the hexagonal socket bolt 7 is the central axis of the vibrator 1, and
the force due to the expansion and contraction vibration generated in the piezoelectric members
4 and 5 symmetrically arranged with the central axis interposed makes it easy to excite bending
vibration.
[0045]
(D) Even if the length of the elastic body 2 constituting the vibrator 1 is changed, the bending
secondary vibration is concomitantly excited by driving the vibrator 1 at the primary longitudinal
resonance frequency corresponding to the length. Therefore, the degree of freedom of the length
of the vibrator 1 is large.
[0046]
(E) When the vibrator 1 is driven, 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 the piezoelectric bodies 4 and 5 one by one 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.
[0047]
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(F) When the vibrator 1 is driven, the directions of the elliptical trajectories of the displacement
generated on the peripheral surface of the elastic body 2 are opposite to each other with the
predetermined position on the tip end side of the elastic body 2 The use of the surface enables
the turning of the moving body by axially changing the part in contact with the moving body.
[0048]
Second Embodiment A second embodiment will now be described with reference to FIG.
In this embodiment, the shape of the elastic body 2 is changed to compare the functions as the
vibrator 1.
The configuration of the vibrator 1 was different only in the elastic body 2 and the other
configurations were all the same.
As the elastic body 2, the elastic primary body 2 of the shape shown by symbols XI to XV in FIG.
The shape and size of the elastic body 2 of XI to XV are as follows.
[0049]
XI has a V-groove 15 mm wide and 10 mm deep formed at the tip of a cylinder 30 mm in
diameter. XII has a 30 mm diameter cylindrical tip with a 50 mm thick flange with an axial
thickness of 5 mm.
[0050]
XIII is formed in the shape of a truncated cone having a diameter of 30 mm at its base end and a
diameter of 20 mm at its tip. The XIV has a neck portion with a diameter of 20 mm and a groove
width of 5 mm in the vicinity of a portion which becomes a node of the vibrator.
[0051]
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XV is parallel to the gap between the opposing end faces of the piezoelectric members 4 and 5
and intersects with a plane orthogonal to a plane including the central axis of the elastic body 2
and in the vicinity of a portion serving as a node of vibration 5 mm wide and 5 mm wide A
constriction is formed.
[0052]
The cylindrical thing of diameter 30 mm was prepared as comparative example STD.
The result of comparing the dynamic admittance characteristics of the studied vibrators is shown
in FIG. In the figure, ○ indicates a resonance frequency (fo), Δ indicates a resonance sharpness
(Q), and x indicates a dynamic admittance (Ymo).
[0053]
For the resonance frequency (longitudinal primary resonance frequency 駆 動 drive frequency) fo
= 19.5 kHz, the elastic bodies of XI to XV fall within the range of 18 to 20 kHz. Among the
studied vibrators, those having good sharpness of resonance (Q) and dynamic admittance (Ymo)
were XIV in which a neck portion was formed at a node serving as a node of vibration.
[0054]
Also, as a result of observing the movement of the vibrator using the bearings using the vibrators
using the five types of elastic bodies as in the first embodiment, it was confirmed that the
movement was similar to that of STD. .
[0055]
From this result, it was found that if the shape of the elastic body of the vibrator is determined in
length, some change in the shape of the elastic body is possible.
In this embodiment, an example of a single shape indicated by symbols XI to XV is shown, but
similar functions of XI to XV and a shape obtained by combining XI to XV exhibit the same
04-05-2019
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function as a vibrator. It can be judged.
[0056]
Third Embodiment A third embodiment will now be described with reference to FIGS. In this
embodiment, as shown in FIG. 14, 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.
[0057]
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
[0058]
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
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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.
[0059]
Further, in a state where the switch 18 is connected to the B phase, ie, in a 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 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
movable body on the tip surface, the movable body is moved to the right in FIG. When a phase
difference of −90 ° is given to the A phase and the B phase and the vibrator 1 is driven by twophase driving, the moving body is moved to the left side of FIG.
[0060]
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 bodies 14, 15, 16, 17 to be driven, the moving
direction of the moving body can be switched between the arrow EW direction and the arrow NS
direction in FIG.
[0061]
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
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(left and right direction in FIG. 17) 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 proximal end side of the
vibrator 1 is fixed to the support frame 20a. 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 21, and the electrode plate 6b of the second piezoelectric body 5 is
connected to the common AC drive source 22. (Amplifier, phase shifter, etc. are not shown).
[0062]
When a voltage is applied from AC drive sources 21 and 22 with a phase difference of + 90 °
with respect to first piezoelectric body 4 and second piezoelectric body 5 of each 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
members 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 21 and 22.
[0063]
The present invention is not limited to the above embodiments, and may be embodied as follows,
for example. (1) As shown in FIG. 18, the polarization direction of the first piezoelectric body 4
may be different from the polarization direction of the second piezoelectric body 5. That is, the
polarization directions of the piezoelectric elements 4a and 4b constituting the first piezoelectric
body 4 are the same as in the first embodiment, and the polarization directions of the
piezoelectric elements 5a and 5b constituting the second piezoelectric body 5 are the first In the
opposite direction to the embodiment of FIG. Alternatively, contrary to FIG. 18, the polarization
directions of the piezoelectric elements 4 a and 4 b constituting the first piezoelectric body 4 are
opposite to those in the first embodiment, and the piezoelectric elements 5 a and 5 b constituting
the second piezoelectric body 5 The polarization direction of 5b may be the same as that in the
first embodiment. In this case, bending vibration is more easily excited in the elastic body 2.
[0064]
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19
(2) 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. A ground electrode 23 is disposed
between adjacent piezoelectric elements forming a pair. 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.
[0065]
(3) 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 °.
[0066]
(4) 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.
[0067]
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20
(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) When using the vibrator 1 as an actuator,
for example, as shown in FIG. 21, a plurality of vibrators 1 are fixed in one row on a rigid support
24 and the tip end face of each vibrator 1 runs The self-propelled actuator 26 may be configured
to be placed on the traveling surface 25 in contact with the surface 25. In this case, the first
piezoelectric body 4 of each vibrator 1 is connected to the two-phase oscillator 12 via the
amplifier 10 and the phase shifter 11, and the second piezoelectric body 5 is connected to the
two-phase oscillator 12 via the amplifier 10. Be done.
[0068]
Then, when an applied voltage having a phase difference is supplied to the first piezoelectric
body 4 and the second piezoelectric body 5, the actuator 26 moves to the left or right in FIG. 21,
and the moving direction thereof changes the phase difference, for example, + 90 °. It changes
direction by changing to and -90 degrees. Further, when this actuator 26 is configured using the
vibrator 1 of the third embodiment, the actuator 26 can be moved not only in the lateral
direction of FIG. 21 but also in the direction orthogonal to the paper surface.
[0069]
(7) 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. 22, a male screw 2c is protruded from the elastic body 2, and the male screw 2c is screwed
into a 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. In addition, in order to facilitate handling before fixing to the base 8
etc., the elastic body 2 and the piezoelectric bodies 4 and 5 etc. are temporarily fixed with an
adhesive, and fastening to the base 8 etc uses fasteners. It may be done to
[0070]
(8) As shown in FIG. 23, the third piezoelectric body 27 may be disposed on the lower side of the
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first and second piezoelectric bodies 4 and 5 across the plane of symmetry of bending vibration.
The third piezoelectric body 27 is composed of ring-shaped piezoelectric elements 27a and 27b
and a ring-shaped electrode plate 27c disposed therebetween.
[0071]
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) In the
first aspect of the invention, the first piezoelectric body and the second piezoelectric body are
configured such that the polarization directions thereof are opposite to each other. In this case,
bending vibration is more easily excited by the rod-like elastic body.
[0072]
(2) The vibrator according to claim 1 and a power supply unit capable of switching the phase
difference of the voltage 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 °.
[0073]
(3) 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.
[0074]
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22
(4) The vibrator according to claim 2 or (3) 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 ±
90 ° or around.
[0075]
As described above in detail, according to the inventions of claims 1 to 4, in a resonance system
capable of obtaining a large amplitude, an actuator having a high thrust force due to a structure
capable of withstanding a large pressing force. An oscillator is obtained.
[0076]
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 the third aspect of the present invention, the sharpness of the resonance and the
dynamic admittance become better as compared with the case where the groove-like neck
portion is not formed in the vicinity of the vibration node of the vibrator.
[0077]
According to the fourth aspect of the present invention, compared with the case where the
piezoelectric element and the elastic body are fixed (laminated) by adhesive bonding, the
piezoelectric element is less likely to be displaced during driving, and stable vibration
characteristics can be obtained.
[0078]
Brief description of the drawings
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23
[0079]
Fig. 1 is a schematic view showing the configuration of a vibrator.
[0080]
Fig. 2 is a schematic view showing the displacement of the tip of the vibrator.
[0081]
Fig. 3 Schematic diagram of the elliptical trajectory of displacement.
[0082]
FIG. 4 is a schematic cross-sectional view showing the vibrator configuration of the first
embodiment.
[0083]
5A is a perspective view of the piezoelectric element, FIG. 5B is a perspective view of the
electrode plate, and FIG. 5C is a perspective view of the elastic body.
[0084]
FIG. 6 is a diagram showing the relationship between the length of an elastic body and the
resonant frequency of a vibrator.
[0085]
Fig. 7 (a) shows a phase difference of + 90 ° between the A and B phases, (b) shows -90 °
between the A and B phases, (c) shows only the A phase and (d) shows only the B phase. The
schematic diagram which shows the state of the elliptical locus ¦ trajectory of a displacement of
the elastic body surface at the time of driving.
[0086]
FIG. 8 is a schematic plan view showing the relationship between the central plane of bending
vibration of the vibrator and the piezoelectric body.
[0087]
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24
Fig. 9 is a schematic view showing the vibration velocity waveform of the vibrator and the
movement of the vibrator.
[0088]
10 is a diagram showing the relationship between the amplitude ratio of the vibrator and the
elastic body length.
[0089]
11 is a schematic view showing a method of measuring the thrust of the vibrator.
[0090]
12 is a diagram showing the relationship between the thrust of the vibrator and the weight of the
weight.
[0091]
13 is a graph showing the relationship between the shape of the elastic body and the
characteristics of the vibrator.
[0092]
14 is a schematic plan view showing the arrangement of the piezoelectric body and the electrode
plate of the third embodiment.
[0093]
FIG. 15 is a schematic perspective view of the vibrator as in FIG.
[0094]
Fig.16 (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.
[0095]
17 is a schematic view of an actuator according to the fourth embodiment.
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25
[0096]
The model front view of the vibrator ¦ oscillator of the modification of FIG.
[0097]
The model front view of the vibrator ¦ oscillator of the example of another change of FIG.
[0098]
20 is a schematic plan view showing the arrangement of the piezoelectric body and the electrode
plate of the vibrator of the modified example of FIG.
[0099]
21 is a schematic side view of a self-propelled actuator.
[0100]
22 is a schematic cross-sectional view of the vibrator of the modification example of FIG.
[0101]
The model front view of the vibrator ¦ oscillator of the example of another change of FIG.
[0102]
FIG. 24 is a schematic perspective view of the conventional device.
[0103]
25 is a schematic exploded perspective view of another conventional device.
[0104]
FIG. 26 is a schematic view showing the operation of the conventional device.
[0105]
27 is a schematic view of another vibrator.
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[0106]
Explanation of sign
[0107]
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: Base as a fixed part, 14-17: Piezoelectric, 14a-17a, 14a-17a:
Piezoelectric element.
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