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[Object of the Invention 1 (Industrial Field of Application)] The present invention relates to a
piezoelectric actuator having a displacement element using a piezoelectric element as a drive
source. (Prior Art) Piezoelectric ceramic and electrostrictive ceramic. There are piezoelectric
actuators using displacement elements consisting of polymer piezoelectrics or combinations of
these or composite phases of these, and structurally, there are bimorph-type displacement
elements, Langevin-Gray transducers, etc. It is also known that can obtain large displacement and
stress. However, even with such a displacement element, its displacement Ca is at most about
several μm to several mra, and it can not be used for applications requiring a larger amount of
displacement -5. There is also known an actuator called inchworm, which was devised to make
the displacement h1 larger, but at least three piezoelectric elements must be sequentially driven
to drive, and a complex control circuit I needed it. The movement amount of the actuator is equal
to F [displacement h1 of the electric element, and the movement frequency can not be so high
because the movement by the mechanical fh is based on 16 and the large movement speed can
not be 1 q, several cm / It is about a minute. There is also a drawback that the difference greatly
affects the performance and does not operate, or the operation becomes unstable. On the other
hand, there is also an ultrasonic motor called elastic traveling wave type, but since the elastic
traveling wave is present on the elastic body rail, the drive frequency and the mechanical size are
closely related, and the machine dimensional accuracy is severe and difficult to adjust. In
addition, there is a problem that the drive frequency and the vibration frequency change of the
piezoelectric vibrator do not operate as J: or the operation becomes unstable. Both of the abovementioned Inchworm method 9 elastic traveling wave methods are limited to reciprocation, ie,
dimensional movement, and movement on a two-dimensional plane is completely impossible. In
addition, "The 7th Ultrasonic Elect [Symposium Proceedings on the Basics and Applications of
NIX 1st Symposium" held on December 8-10, 1986 at Kyoto Convention Hall "C", pp. 109-110. A
laminated piezoelectric ceramic actuator for scanning tunneling microscopy is described. This is
a configuration using three stacked piezoelectrics, called a double tribod, which applies a direct
current and C-drives, but applying an alternating current is not effective because the
piezoelectrics are stacked. Since the capacitance becomes large, it requires an enormous current
value to drive and is not practical.
In addition, if the number of laminations is reduced to reduce the capacitance, driving can be
performed even by alternating current application, but the distance between displacements
becomes extremely small, and this also indicates only a value far from practical use. And the
displacement direction of this double tribod can only be displaced linearly in three directions of
X-Y-Z. (Problems to be Solved by the Invention) According to the piezoelectric actuator of the
present invention, it is possible to move the two-dimensional, parallel straw surface freely in any
direction, and it requires much mechanical accuracy. The driving circuit is simple, and it is stable
with high moving speed! There is C that you can get FJJ 乍. [Aspect 1 of the Invention (Means for
Solving the Problems)] A piezoelectric actuator C according to the present invention is fixed to
the outer surface of a driving body, and a displacement element consisting of three piezoelectric
elements having their center axes intersecting each other. The movable body is brought into
contact with the driving body of (Operation) In the piezoelectric actuator according to the
present invention, the driving body is a piezoelectric element by changing the positional
relationship between the three piezoelectric elements fixed to the outer surface of the driving
body and the driving voltage #J applied to the piezoelectric element. To provide a piezoelectric
type actuator which moves in a plane as well as a moving body in contact with the driving body,
and thus freely travels on a flat surface, and performs a linear displacement as well as a linear
displacement in the axial direction of the Can. EXAMPLE 1 FIG. 1 shows a displacement element
used for a piezoelectric actuator 1 according to the present invention. For example, the three
rounds of piezoelectric element 5.6.7 having 3.4 are fixed such that their central axes are
perpendicular to each other. The piezoelectric element 6.7 may be attached to the
driving body 1 via elastic bodies 8, 9 and 10 made of metal, resin or elastomer. The position of
the piezoelectric element 5.6.7 of the displacement element 11 thus produced corresponds to the
X-Y-Z axis of the coordinate as shown in FIG. sin ωt, V different in phase to the piezoelectric
element 5 When a signal of COS ωt is applied and driven, the circular motion direction of the
mass point becomes parallel to the Z axis. Also, V in the piezoelectric element 6. When Vocos ωt
is added to sin ωt and the piezoelectric element 7, the circular movement direction of the mass
point becomes parallel to the X axis. Furthermore, when sin ωt is added to the piezoelectric
element 6 and COS ωt is added to the piezoelectric element 5 and the σ piezoelectric element 7,
the direction of the circular motion of the mass point is such that the angle of 45 degrees is right
from the X axis and Z axis. As shown in FIG. 3, one or more displacement elements 11 whose
rotational movement is performed by the mass point are arranged such that the movement
direction of the mass point is one forward as shown in the front view in FIG. 3 and the side view
in B. Contact the moving body 12 to the driving body 1 of the element 11! !
I feel a stomachache. The piezoelectric actuator having such a configuration has the piezoelectric
element 5 as described above. Since the rotational movement at the mass point of the driving
body 1 is vertical, horizontal, and oblique movement, that is, the rotational movement on the XZ
plane by the drive signal applied to '6.7, the moving body 12 in contact with the driving body 1
Move in the direction of the rotational movement at the top of the circular movement of the
driving body 1. Therefore, exactly, the moving body 12 is moved by intermittent movement due
to the apex of the circular movement of the driving body 1, and can be moved in both directions
perpendicular to the plane as shown by arrows in FIG. Further, the angle of movement on the
plane and the like can be freely selected by changing the positional relationship between the
piezoelectric elements 5 and 6.7, the drive signal, and the like. In the embodiment described
above, the case where the drive signal and a voltage different in C phase are applied to the
piezoelectric element and the IC is described, but in the case of changing the voltage amplitude,
the driving body moves in the axial direction to which the voltage with large amplitude is applied.
Perform an elliptical motion with a major axis. If the movement in the major axis direction is
used, the moving speed is increased, and if the movement in the minor axis direction is not used,
the height for lifting the moving body is increased, and the moving distance for one time can be
increased. In addition, when changing the same wave number ratio of the drive voltage applied to
the piezoelectric element, the driving body performs a long eight-shaped movement of the upper
side and the lower side, so use the upper side and the lower side that makes the movement
nearly flat. It is used, for example, when moving a moving body in contact with the upper side
and a moving body in contact with the lower side in opposite directions. Embodiment 2 FIG. 4
shows that the drive cycle of the drive unit 1 is made different and intermittent motion is made
closer to continuous movement, and the alternate long and short dash line in FIG. 4 shows the
displacement state of the drive unit 1. In this embodiment, the feature of increasing the moving
speed is to the right. In this configuration, the movable body 12 can freely move vertically,
horizontally, and diagonally on the plane by the movement of the driving body 1 if the respective
groups of two different 1 to 1 displacement elements 11 for driving are driven in different
directions. Move. Embodiment 3 FIG. 5 shows a self-propelled actuator. That is, the movable body
12 is disposed on the base body 13 of the drive body 1 and on the opposite side of the base body
13. In the actuator having such a configuration, both the displacement element 11 and the
movable body 12 move, that is, self-propelled. Embodiment 4 This embodiment shown in FIG. 6
has a construction in which the moving body 12 is drawn in from both the upper and lower sides
by the driving body 1. In such a configuration, the driving force applied to the moving body 12 is
strong by being absorbed into the driving body 1 from both sides. In this case, the moving body
12 may be a belt-like endless one.
[Effects of the Invention] According to the present invention, the mounting position of the three
piezoelectric elements attached to the displacement element, the phase of the driving voltage for
driving the piezoelectric elements, and the voltage amplitude 1 frequency change the plane of the
moving body. Can be moved freely. In addition, mechanical accuracy is not required so much,
and the circuit requires only a phase shift circuit, so that high moving speed, propulsion and
stable operation can be obtained.
Brief description of the drawings
The drawings all show an embodiment of the present invention, and FIG. 1 is a perspective view
of the displacement element, FIG. 2 is a coordinate diagram showing the displacement direction
of the displacement element, and FIGS. 3 to 6 are embodiments of the piezoelectric actuator. Yes,
Fig. 3 is a block diagram of the embodiment that moves in the perpendicular direction, and Fig. 4
is the vI!
5 is a block diagram showing a self-propelled type, and FIG. 6 is a 64 block diagram of an
embodiment in which the driving body is disposed on both sides of the moving body. 1 ...... driver
5,6.7 ...... piezoelectric Sakuko 11 ...... displacement element 12 ...... mobile resistant Huh filing
human Marcon Electronics Co. 11 perspective view of displacement 4-element displacement
element 1 diagram coordinate direction of displacement direction 2 diagram front view of
piezoelectric actuator 3 diagram (A) side view of piezoelectric actuator diagram 3 (B) diagram 4
diagram 5 Figure 6