JP2001298970A - Piezo actuator - Google Patents

Abstract

(57) [Problem] To provide a piezoelectric actuator suitably used as a drive device for a linear motor, a rotary table, an XY table, and the like. A piezoelectric actuator 1 supports a stage (transported body) 23 and has a first member and a second member positioned across a guide rail 21.
And a support member 22 in the length direction (X-axis direction) of the guide rail 21 in each of the first portion and the second portion.
First piezoelectric elements 2a and 2b arranged so as to sandwich
And second piezoelectric elements 3a and 3b disposed so as to sandwich the first piezoelectric elements 2a and 2b. The first piezoelectric elements 2a and 2b extend and contract in the length direction of the guide rail 21,
The second piezoelectric elements 3a and 3b are brought into contact with the guide rail 21 at a predetermined pressure, and expand and contract in the direction of separation and contact with the guide rail 21. In the piezoelectric actuator 1, the relative movement between the support member 22 and the guide rail 21 becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric actuator suitably used as a driving device for a linear motor, a rotary table, an XY table and the like.

[0002]

2. Description of the Related Art A linear motor utilizing a piezoelectric material thickness-longitudinal displacement mode (33 mode) and resonance has a simpler mechanism, superior stop holding force, and a higher electromagnetic force than a conventional electromagnetic motor. It has excellent features such as low noise.

As such a linear motor, for example,
As shown in FIGS. 8A and 8B, a linear actuator 55 that is disposed so as to be sandwiched between two rails 50 is known. The linear actuator 55 includes two piezoelectric elements 51.5 that expand and contract in a direction perpendicular to the length direction of the rail 50.
3, a piezoelectric element 52 whose length direction is the same as the length direction of the rail 50 is arranged and has an integrated structure.

As shown in FIG. 8, the drive mechanism of the linear actuator 55 is, for example, to set the position of the first piezoelectric element 51 on the rail 50 as a reference point P, extend the piezoelectric element 51, and The position is fixed (a), then the piezoelectric element 52 is extended to move the piezoelectric element 53 away from the piezoelectric element 51 (b), and then the piezoelectric element 53 is extended to fix the position of the linear actuator 55 (c). . Subsequently, the extension of the piezoelectric element 51 is released (d), and the extension of the piezoelectric element 52 is released (e),
Thereafter, the operation of releasing the extension of the piezoelectric element 53 (f) is repeated.

[0005]

However, in such a linear actuator 55, two rails 50 are required.
If the distance between the linear actuators 55 is not always constant, there is a problem that the contact pressure of the linear actuator 55 with the rail 50 changes, the moving speed changes depending on the location, and in the worst case, the linear actuator 55 cannot move and stops. In addition, when one of the used piezoelectric elements 51 to 53 fails, there is a problem that the driving becomes impossible.

Further, in order to prevent the linear actuator 55 from dropping, it is necessary to form a guide groove or the like on the rail 50 for the linear actuator 55 to move. If the movable stage and / or the rail 5 are arranged on the rail 55, the linear actuator 55 may be deformed by the movable stage and drive characteristics may be changed.
It is conceivable that a need arises for providing a guide portion at the position 0, and a problem such as an increase in processing cost occurs.

The present invention has been made in view of such problems of the prior art, and one of the objects is as follows.
First, for example, by adopting a structure that can move along one rail, it is easy to adjust the contact pressure between the actuator and the rail, and one actuator cannot be used. Another object of the present invention is to provide an inexpensive piezoelectric actuator which can be operated continuously even in the case where the moving stage and the rail are not specially shaped.

Another object of the present invention is not limited to one-way movement, but is to move in two directions that intersect at a predetermined angle in one plane, and to combine such two-way movements. Provided is a piezoelectric actuator which can be used as an XY stage or a rotary stage by enabling a movement to an arbitrary position in a plane and further enabling a rotational movement by controlling a driving mode of a piezoelectric element. It is in.

[0009]

That is, according to the present invention, as a first piezoelectric actuator, a first portion and a second portion which support a transferred object and are located across a guide rail are provided.
A first piezoelectric element disposed so as to sandwich the support member in a length direction of the guide rail in each of the first portion and the second portion; A second piezoelectric element disposed so as to sandwich the piezoelectric element, wherein the first piezoelectric element expands and contracts in the length direction of the guide rail, and the second piezoelectric element is mounted on the guide rail. A piezoelectric actuator that is brought into contact with a predetermined pressure, expands and contracts in a direction of separation and contact with the guide rail, and is capable of relative movement between the support member and the guide rail. Is done.

Further, according to the present invention, as the second piezoelectric actuators, two first piezoelectric actuators are provided so that the expansion and contraction directions coincide with each other in two directions intersecting at a predetermined angle. A piezoelectric element, a connecting member disposed at the center of the first piezoelectric element, and joined to one end of the first piezoelectric element in the direction of expansion and contraction, and joined to the other end of the first piezoelectric element in the direction of expansion and contraction A second piezoelectric element; and a weight body disposed so as to apply a load to the second piezoelectric element via an anti-friction material, wherein the second piezoelectric element is configured to apply a load from the weight body. Wherein the connecting member is connected to the ground plane of the weight body or the second piezoelectric element, and the relative movement between the weight body and the ground plane is possible. An actuator is provided.

The second piezoelectric actuator may be configured such that the connecting member is not connected to a heavy object but is connected to a ground plane on which the piezoelectric actuator is provided, for example, a table. That is, according to the present invention, as a third actuator, in each of two directions intersecting at a predetermined angle, two first piezoelectric elements are arranged so that the direction of expansion and contraction coincides with the direction. A connecting member arranged at the center of the first piezoelectric element and joined to one end of the first piezoelectric element in the direction of expansion and contraction; and a second piezoelectric element joined to the other end of the direction of expansion of the first piezoelectric element. And a pedestal connected to the connecting member and grounding the second piezoelectric element via an anti-friction material; and a movable weight body disposed to apply a load to the second piezoelectric element. Also provided is a piezoelectric actuator, wherein the second piezoelectric element expands and contracts in a direction in which a weight is applied from the weight body.

Here, in the second and third piezoelectric actuators, the two directions intersecting at a predetermined angle are preferably two orthogonal directions. In addition, the first aspect of the present invention
In the third to third piezoelectric actuators, laminated piezoelectric elements are suitably used as various types of piezoelectric elements.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings, but it goes without saying that the present invention is not limited to the following embodiments. The piezoelectric actuator of the present invention performs a predetermined motion by combining a plurality of piezoelectric elements using the thickness-longitudinal displacement (33-mode displacement) of the piezoelectric body. The material (piezoelectric ceramic, polymer piezoelectric, single crystal piezoelectric, etc.) or form (plate, block, etc., single plate, laminate, etc.) of the piezoelectric material used is not limited. ₃₃ is 5
00 × 10 ⁻¹² m / V lead zirconate titanate (PZ
If a 10 mm thick piezoelectric block made of T) -based piezoelectric ceramics is to be displaced by 10 μm,
A voltage of as much as 0 V is required. This does not pose any problem on the operation principle of the piezoelectric actuator of the present invention, but is not practical.

Therefore, in the piezoelectric actuator of the present invention, the piezoelectric ceramic is used, and the thickness of the piezoelectric body is reduced.
As shown in FIG. 7A, a single piezoelectric element 95 is known as a piezoelectric element using the longitudinal displacement mode (33 mode).
A so-called laminated piezoelectric element 97a in which the thickness of the piezoelectric element 97a is reduced and the internal electrode 96 is alternately layered in several layers is preferably used. The internal electrodes 96 are alternately connected to the external electrodes 98 to form a pair, and are used for both polarization and driving.

In the laminated piezoelectric element 97a, when the thickness of the single piezoelectric body 95 is set to, for example, 100 μm and the layers are laminated into 100 layers, the internal electrodes can be formed as thin as about 2 to 3 μm. In this case, a displacement of 10 μm can be obtained at a voltage of 200 V.

The multilayer piezoelectric element 97a shown in FIG. 7 (a) is generally called a multilayer capacitor type. In addition, as shown in FIG. The electrode 96 is exposed on the side surface of the element, and the insulating layer 99 is formed on every other layer, and the laminated piezoelectric element 97b called a full-surface electrode type in which the internal electrode 96 is connected to the external electrode 98 on every other layer, and FIG. c) As shown in FIG.
And a slit type piezoelectric element 97c called a slit type in which a stress relaxation layer 94 is formed in a portion where the internal electrode 96 does not overlap in the laminating direction. There is no limitation.

Next, the structure of the first piezoelectric actuator of the present invention using the above-described piezoelectric element will be described. FIG. 1A shows a side view of the piezoelectric actuator 1, and FIG. 1B shows a plan view. As shown in FIG. 1, a U-shaped support member 22 is straddled on a guide rail 21 having a substantially square cross section, and a stage 23 as a transferred object is disposed above the support member 22. Has been established. In FIG. 1B, the illustration of the stage 23 and the bearing 24 is omitted.

Here, the length direction of the guide rail 21 is X
Assuming that the axial direction and the lateral direction are the Y-axis direction, and the vertical direction is the Z-axis direction, the support member 22 is mounted on the guide rail 2 from above the Z-axis direction.
1, the support member 22 does not fall, and is in a movable state so as to be able to move along the length direction of the rail 21.

The shape of the support member 22 is not limited to the U-shape, and the straddling direction is not limited to the Z-axis direction. For example, FIG. 2A illustrates a case where the U-shaped support member 22 illustrated in FIG. 1 is disposed so as to straddle the guide rail 21 from the Y-axis direction, as illustrated in FIG. In addition, a hollow support member 22a through which the guide rail 21 penetrates may be used, or a support member 2 suspended from the guide rail 21 as shown in FIG.
2b or the like can also be used.

As described above, the support member 22 only needs to have the first portion and the second portion located over the guide rail 21. In the piezoelectric actuator 1, the side surface (the Y-axis direction) of the guide rail 21 is provided. Support member 2 located on the side)
2 correspond to the first portion and the second portion. As will be described later, a piezoelectric element is provided in the first portion and the second portion. In the example of FIG. 2A, the support member 22 is prevented from coming off the guide rail 21.
Preferably, a guide mechanism is provided.

The stage 23 is arranged on the guide rail 21 via a bearing 24, and the load of the stage 23 is applied to the guide rail 21 via the bearing 24. The bearing 24 is fixed to the stage 23 side, and since the bearing 24 functions as an anti-friction material, the bearing 24 does not hinder the movement of the stage 23 along the guide rail 21.

On the other hand, the load of the stage 23 may be applied to the upper surface of the guide rail 21 through the support member 22 without using the bearing 24. However, due to the load of the stage 23 applied to the guide rail 21 via the support member 22, especially the piezoelectric actuator 1
It is necessary to prevent the displacement of the first piezoelectric elements 2a and 2b that constitute the above. In addition, bearing 2
Talc (talc, pyroxene), sericite (mica), carbon, boron nitride, fluororesin, or the like can also be used as an antifriction material instead of 4.

On each side surface (side surface in the Y-axis direction) of the guide rail 21, two first piezoelectric elements 2a and 2b are disposed so as to sandwich the support member 22, and two second piezoelectric elements 2a and 2b are further provided. The elements 3a and 3b are the first piezoelectric elements 2a and 3b.
2b. Thus, a total of four first piezoelectric elements 2a and 2b and four second piezoelectric elements 3
a.3b are arranged so as to be substantially line-symmetric with the guide rail 21 as the axis of symmetry. First piezoelectric elements 2a and 2
b expands and contracts in the length direction (X-axis direction) of the guide rail 21, that is, the direction in which the first piezoelectric elements 2a and 2b sandwich the support member 22, and the second piezoelectric elements 3a and 3b It expands and contracts in the direction of contact and detachment (Y-axis direction) with respect to 21.

The joining between the support member 22 and the first piezoelectric elements 2a and 2b and the joining between the first piezoelectric elements 2a and 2b and the second piezoelectric elements 3a and 3b are performed using a resin adhesive or the like. However, as the resin adhesive, the first piezoelectric elements 2a and 2b have a small amount of displacement absorption and, on the other hand, the first piezoelectric elements 2a and 2b due to expansion and contraction deformation of the second piezoelectric elements 3a and 3b.
It is preferable to select a material having an appropriate hardness and adhesive strength so that a joint portion between b and b does not peel off.

The second piezoelectric elements 3a and 3b are brought into contact with the side surface of the guide rail 21 at a predetermined pressure. Thus, in a normal state, a predetermined compressive stress is applied to the second piezoelectric elements 3a and 3b.
A state in which no voltage is applied to the second piezoelectric elements 3a and 3b,
Alternatively, in a state where a negative voltage (a voltage in which the direction of the applied electric field is opposite to the direction of the polarization of the piezoelectric body in the second piezoelectric elements 3a and 3b) is applied to the second piezoelectric elements 3a and 3b and contracted, The second piezoelectric elements 3a and 3b are
To the extent that it can slide on the side of the vehicle. It is preferable that a wear-resistant member, for example, a member made of alumina, zirconia, silicon nitride, silicon carbide, or the like be attached to the end face of the second piezoelectric elements 3a and 3b on the guide rail 21 side.

For this contact, the piezoelectric actuator 1
Then, the two second piezoelectric elements 3 opposed to each other with the guide rail 21 interposed therebetween using the U-shaped pressing jigs 25a and 25b.
a, the second piezoelectric elements 3b are
1, a structure is employed in which the space is restrained at a predetermined pressure by utilizing the lower space. The above-mentioned resin adhesive can be used for joining the pressure welding jigs 25a and 25b and the second piezoelectric elements 3a and 3b.

Guide rail 2 for second piezoelectric elements 3a and 3b
For example, a method in which a spring plate is joined to the side surface in the Y-axis direction of the support member 22 and the second piezoelectric elements 3a and 3b are pressed against the guide rail 21 can be used for contact with the support member 22. In this case, since no member is provided in the lower space of the guide rail 21, the structure is simplified, and the guide rail 21 does not need to be linear having four sides. That is, it is possible to dispose the rail-shaped protrusion having three sides so as to move in the length direction.

The U-shaped press-welding jigs 25a and 25b
The first piezoelectric element 2a, 2b is similarly connected to the first piezoelectric element 2a, 2b by using a U-shaped jig so that a predetermined compressive stress is applied to the second piezoelectric element 3a, 3b. Element 2a
It may be constrained so that a predetermined compressive stress is applied within a range where a predetermined amount of displacement is obtained in 2b.

Next, the driving mode of the piezoelectric actuator 1 will be described with reference to FIG. In FIG.
Reference points Q1 and Q2 shown on the guide rail 21 indicate the positions of the first second piezoelectric elements 3a and 3b, respectively.

First, a voltage is applied so that the second piezoelectric element 3a extends in the Y-axis direction, the guide rail 21 is tightened, and the second piezoelectric element 3a is fixed (step 1). At this time, no voltage is applied to the first piezoelectric elements 2a and 2b. Further, regarding the second piezoelectric element 3b,
No voltage is applied, or the guide rail 21
Any of the states in which a negative voltage is applied so as to shrink in the Y-axis direction in order to reduce the compressive stress to the substrate may be adopted. That is, the second piezoelectric element 3b only needs to be in a state where the guide rail 21 can be moved according to the displacement when the first piezoelectric elements 2a and 2b are expanded in the next step.

Next, the second piezoelectric element 3a is
1 in a state where the first piezoelectric element 2a
A voltage is applied to 2b so as to extend in the X-axis direction (step 2). Thus, the second piezoelectric element 3b moves in the X-axis direction by the total displacement of the first piezoelectric elements 2a and 2b. Subsequently, a voltage is applied to the second piezoelectric element 3b so as to extend in the Y-axis direction, and the guide rail 21 is tightened.
The position of the second piezoelectric element 3b is fixed (Step 3).

Thereafter, the second piezoelectric element 3a is contracted in the Y-axis direction (Step 4). In this step 4, the voltage applied to the second piezoelectric element 3a may be returned to the original state by setting it to 0 V, or a negative voltage may be applied to the second piezoelectric element 3a to reduce the voltage from the initial state. It is good also as a state.

After the second piezoelectric element 3a is released from being fixed to the guide rail 21 and the second piezoelectric element 3a is movable along the guide rail 21, the first piezoelectric elements 2a and 2b are removed. Shrink (step 5). This step 5 is also a method of setting the voltage applied to the first piezoelectric elements 2a and 2b to 0 V, and applying a negative voltage to the first piezoelectric elements 2a and 2b to make the first piezoelectric elements 2a and 2b contracted from the initial state. Method may be used. As a result, the second piezoelectric element 3a moves in the X-axis direction by the total displacement of the first piezoelectric elements 2a and 2b.

Subsequently, a voltage is applied to the second piezoelectric element 3a so as to extend in the Y-axis direction, and the second piezoelectric element 3a is fixed to the guide rail 21 again, and then the second piezoelectric element 3b is contracted. Then, the fixing of the second piezoelectric element 3b to the guide rail 21 is released (step 6). By the end of step 6,
The piezoelectric actuator 1 returns to the state before the start of Step 1, and thereafter repeats Step 1 to Step 6 a predetermined number of times to move the piezoelectric actuator 1 and the stage 23 along the guide rail 21 in the positive direction in the X-axis direction. It can be moved in the direction by a predetermined distance.

It should be noted that if the order of the expansion and contraction of the second piezoelectric elements 3a and 3b is reversed, the piezoelectric actuator 1 can be made to move in the negative direction along the X-axis. In the above description, the case where the guide rail 21 is fixed and the piezoelectric actuator 1 is moved along the length direction of the guide rail 21 has been described. 21
Can also be moved.

The movement of the piezoelectric actuator 1 described above
By controlling the expansion and contraction of the first piezoelectric elements 2a and 2b, the piezoelectric elements can be used both statically and dynamically. That is,
In order to perform static control such as when performing fine positioning of the stage 23, voltage is gradually applied to the first piezoelectric elements 2a and 2b, the displacement amount is set to a predetermined value, and the position of the piezoelectric actuator 1 is fixed. do it. On the other hand, when the stage 23 is used dynamically as a transport mechanism or the like, the first piezoelectric element 2
Steps 1 to 6 described above are repeated by applying a pulse signal of a constant frequency to the a.2b and the second piezoelectric elements 3a and 3b, and the moving speed can be changed by changing the frequency. Of course, such dynamic control and static control can be used in combination.

By the way, in the piezoelectric actuator 1, even when the first and second piezoelectric elements 2a, 2b, 3a, 3b arranged on one side of the guide rail 21 are used, the movement along the guide rail 21 does not occur. It is possible. That is, even if a failure occurs in one piezoelectric element used in the piezoelectric actuator 1, the piezoelectric actuator 1 can be driven. However, the condition is that the second piezoelectric elements 3a and 3b used for driving can generate enough pressure to be fixed to the guide rail 21.

In driving the piezoelectric actuator 1,
Unlike the linear actuator 55 described with reference to FIG.
Adjustment of the distance between them is unnecessary, and installation is easy. Also, as for the rail shape, a simple shape such as a substantially square cross section can be used, and since there is no need to provide a guide groove or the like for positioning the piezoelectric element, the installation cost can be reduced. It becomes possible. In addition, guide rail 2
By providing a wear-resistant member between the first and second piezoelectric elements 3a and 3b and adjusting the shape of the wear-resistant member to the outer shape of the guide rail 21, a pipe having a substantially circular cross section is used as the guide rail 21. It can also be used.

Next, a second piezoelectric actuator according to the present invention will be described with reference to FIG. FIG.
4A is a plan view of the piezoelectric actuator 10, and FIG.
4B is a cross-sectional view taken along line AA in FIG. Although a cross-sectional view taken along line BB in FIG. 4A is not shown, it is the same as FIG. 4B.

In the piezoelectric actuator 10, two first piezoelectric elements 12a and 12b and another two first piezoelectric elements 12c and 12d are arranged in each of the X-axis direction and the Y-axis direction which are orthogonal to each other. The direction of expansion and contraction is
The first piezoelectric elements 12a and 12b match in the X-axis direction, and the first piezoelectric elements 12c and 12d match in the Y-axis direction. Then, these first piezoelectric elements 12a to 12d
One connecting member 11 is disposed in the center of the first piezoelectric element 12a to 12d.
1.

Second piezoelectric elements 13a to 13d are joined to the other end faces in the expansion and contraction directions of the first piezoelectric elements 12a to 12d, respectively. Then, the second piezoelectric elements 13a to 13d
The wear resistant members 14a to 14d are joined to the upper surface of the stage 16, and the stages 16 are mounted on the wear resistant members 14a to 14d via bearings 15a to 15d (15c and 15d are not shown). Is arranged. In addition, instead of the bearings 15a to 15d, the above-described anti-friction material can be used.
Is mounted on the stage 16 side.

The stage 16 is also connected to the connecting member 11 and moves together with the connecting member 11 as described later. However, it is preferable that the load of the stage 16 is not applied to the connecting member in view of the driving characteristics of the second piezoelectric elements 13a to 13d. The second piezoelectric elements 13a to 13a
d, it is preferable to dispose a wear-resistant member so as to be joined to the second piezoelectric elements 13a to 13d. The joining between the connecting member 11 and the first piezoelectric elements 12a to 12d, the first piezoelectric element 12a to 12d and second piezoelectric elements 13a to 13
Bonding with d can be performed using a resin adhesive as in the case of the piezoelectric actuator 1 described above.

The load on the stage 16 is the bearing 15a
To 15d and the wear-resistant members 14a to 14d,
The second piezoelectric element is pressed against the piezoelectric elements 13a to 13d with a predetermined pressure on the ground plane on which the piezoelectric actuator 10 is placed. Here, the ground plane refers to an upper surface of various tables such as an anti-vibration table on which the piezoelectric actuator 10 is mounted, a flat plate surface formed on the apparatus, and the like.

On the other hand, the direction of expansion and contraction of the second piezoelectric elements 13a to 13d is set to the Z-axis direction which coincides with the load direction of the stage 16. That is, the second piezoelectric elements 13a to 13d receive a particularly large load from the stage 16 when one of them expands, and is fixed at a predetermined position between the stage 16 and the ground plane. Becomes Conversely, the stage 16 needs to have a predetermined weight so that when one of the second piezoelectric elements 13a to 13d is expanded, the element is fixed.

Next, a method of driving the piezoelectric actuator 10, that is, a method of moving the stage 16, will be described by taking, as an example, a case in which the stage 16 is moved in the positive X-axis direction. First, by applying a predetermined voltage to the second piezoelectric element 13a to expand the element, the second piezoelectric element 13a supports the weight of the stage 16 and the state where the second piezoelectric element 13a is fixed between the stage 16 and the ground plane. I do. Next, a voltage is applied to the first piezoelectric elements 12a and 12b so that the elements are expanded and displaced, and the second piezoelectric element 13b is moved by the amount of the displacement. At this time, since the connecting member 11 also moves, the stage 16 also moves. The first piezoelectric elements 12c and 12d, the second piezoelectric elements 13c and 13d, the wear-resistant members 14c and 14d, and the bearings 15c and 15d.
(Not shown) also moves in parallel with the connecting member 11 in the X-axis direction.

Subsequently, a voltage is applied to the second piezoelectric element 13b to expand the element, and the weight of the stage 16 is also applied to the second piezoelectric element 13b.
a, first piezoelectric elements 12a and 12b, second piezoelectric element 13b
The element length is returned to the original length in the following order. Thus, the piezoelectric actuator 10 is placed on the ground plane with the first piezoelectric elements 12a and 1a.
It can be moved in the positive direction in the X-axis direction so as to run by the displacement length of 2b. By repeating the above-described operation, the piezoelectric actuator 10 can be moved by an arbitrary length in the X-axis direction. If the driving order of the second piezoelectric elements 13a and 13b is reversed, the piezoelectric actuator 10 is moved in the negative direction in the X-axis direction. Can be moved.

The movement of the piezoelectric actuator 10 in the Y-axis direction is caused by the first piezoelectric elements 12 c and 12 d and the second piezoelectric element 13.
Obviously, the movement in the X-axis direction can be performed by using c · 13d. Therefore, the piezoelectric actuator 10 moves in the X-axis direction and
By combining the movements in the axial direction, it is possible to move the stage 16 together with the stage 16 so as to move to an arbitrary position in the XY plane.

Regarding the above-described piezoelectric actuator 10, it is also possible to move only the stage 16 while fixing the connecting member 11 of the piezoelectric actuator 10 to the ground plane without fixing it to the stage 16. In this case, the bearing is arranged between the ground plane and the second piezoelectric elements 13a to 13d so as to be fixed to the ground plane. Such a form is an example of the third piezoelectric actuator of the present invention.

In this case, the stage 16 may be moved by, for example, extending the second piezoelectric element 13b and supporting the stage 16 to extend the first piezoelectric element 12b. The first piezoelectric element 12b moves in the X-axis direction by a displacement amount without sliding between the element 13b. Then, the stage 1 is moved by the second piezoelectric element 13b.
While supporting the second piezoelectric element 6, the first piezoelectric element 12a is extended, and the second piezoelectric element 13a is extended. At this time, the stage 16 does not move.

Next, when the displacement of the second piezoelectric element 13b is returned to its original state, the second piezoelectric element 13a supports the stage 16, and in this state, the first piezoelectric element 12a and the first piezoelectric element 12b The stage 16 moves in the X-axis direction by the amount of displacement of the first piezoelectric element 12a while being supported by the second piezoelectric element 13a. Thus, the stage 16 can be moved by the amount of displacement of the first piezoelectric elements 12a and 12b by performing the expansion and contraction of each piezoelectric element once.

For driving such a piezoelectric actuator 10, as in the case of the piezoelectric actuator 1 described above,
It is possible to perform both static driving and dynamic driving. Taking advantage of such features, the piezoelectric actuator 10 is suitably used as a drive mechanism for an XY table or the like that requires precise positioning.

By using a plurality of the piezoelectric actuators 10 described above, it is possible to realize an XY self-propelled table capable of performing more complicated position control. FIG.
Means eight piezoelectric actuators 10 (10a to 10h)
2 shows an XY table 20 using. The support members of the piezoelectric actuators 10a to 10h are attached to a common stage 26,
Piezoelectric actuators 10a-1 attached to corners
0d enables movement in the X-axis direction and the Y-axis direction, as is apparent from the above-described form and driving method of the piezoelectric actuator 10.

On the other hand, the piezoelectric actuators 10e to 10h located in the middle of each side of the stage 26 are such that the second piezoelectric elements constituting the piezoelectric actuators 10e to 10h sandwich the first piezoelectric elements in the X-axis direction. It is arranged so as to coincide with a direction forming an angle of 45 ° with the Y-axis direction (the X1-axis direction and the Y1-axis direction). Therefore, when the piezoelectric actuators 10e to 10h are used, X
-It is possible to directly move the Y table 20 in the X1 axis direction and the Y1 axis direction.
In combination with the driving of 0a to 10d, XY
Movement and positioning of the table 20 to an arbitrary position can be performed more quickly.

Further, for example, the piezoelectric actuator 10
When the drive is performed so as to move the a and 10b in the positive direction in the X-axis direction and the piezoelectric actuators 10c and 10d are driven to move in the negative direction in the X-axis direction, the XY table 20 can be rotated in a clockwise direction. Such a rotational movement is performed so that the piezoelectric actuators 10a and 10d move in the positive direction in the Y-axis direction.
0c can also be achieved by driving to move in the negative direction in the Y-axis direction.

The piezoelectric actuators 10e to 10h
By using, for example, the piezoelectric actuators 10e and 10f
The XY table 20 is also rotated clockwise by driving the piezoelectric actuators 10g and 10h to move in the negative direction of the X1 axis so as to move in the positive direction of the X1 axis. The XY table 20 can be rotated counterclockwise by reversing the driving direction described above. In the XY stage 20, only the stage 26 is moved while the piezoelectric actuators 10a to 10h are fixed to the ground plane, so that only the stage 16 can be moved. It is also possible.

The above-described second piezoelectric actuator 10
Is provided with two first piezoelectric elements 12a to 12d in two directions orthogonal to each other, that is, an X-axis direction and a Y-axis direction, and each of the first piezoelectric elements 12a to 12d has a second piezoelectric element 13a to 1d.
In the present invention, the two directions in which the first piezoelectric elements are provided are not limited to such orthogonal directions.

For example, the piezoelectric actuator 3 shown in FIG.
0, two first piezoelectric elements 31a.3 in the X-axis direction.
1b is arranged so that its expansion and contraction direction coincides with the X-axis direction, and another two first piezoelectric elements 31c and 31d are extended and contracted in a 60 ° direction crossing the X-axis direction at an angle of 60 °. The first piezoelectric elements 31a to 31d are disposed so as to coincide with the 60 ° direction.
d so that one end face in the direction of extension and contraction of
3 and the second piezoelectric elements 32a to 32d extending and contracting in the Z-axis direction are provided on the other end faces in the extending and contracting direction of the first piezoelectric elements 31a to 31d.
32d, and on the second piezoelectric elements 32a to 32d,
A structure in which the stage 35 is mounted via wear-resistant members 34a to 34d and bearings (not shown) may be adopted.

Such a piezoelectric actuator 30 has a Y
To move in the axial direction, the movement in the 60 ° direction and the movement in the X-axis direction must be combined, but the movement in the 60 ° direction is performed by the first piezoelectric elements 31c and 31d and the second piezoelectric element 32c.
The operation can be performed only by the driving of c · 32d. Thus, the direction in which the piezoelectric actuator is frequently moved and the first
It is also possible to make the expansion and contraction directions of the piezoelectric elements coincide.

Further, the above-described piezoelectric actuator 10
In 30, four first piezoelectric elements were used, but the number of first piezoelectric elements used is not limited as long as two first piezoelectric elements are arranged in one direction. For example, if a connecting member having a substantially hexagonal cross section is used, two first piezoelectric elements are provided in each of three directions crossing each other at 60 °, and each of the first piezoelectric elements has a second piezoelectric element. It is also possible to provide a configuration in which an element is provided and a stage is mounted on the second piezoelectric element.

[0060]

As described above, the first piezoelectric actuator of the present invention has an advantage that it can be easily arranged by adopting a structure capable of moving along one guide rail. In addition, even if one actuator becomes unusable, it can be operated continuously, and furthermore, there is no need for special shaping of the stage or rail shape, so the service life is long and the cost is low. This has the effect of being able to be manufactured at a high speed.

The second piezoelectric actuator of the present invention is not limited to one-way movement, but can be moved to an arbitrary position within one plane, and a plurality of such piezoelectric actuators are provided. In the XY table,
By controlling the driving form of the piezoelectric element in each piezoelectric actuator, not only movement to an arbitrary position in the XY plane, but also in-plane rotational movement becomes possible. Thus, according to the second piezoelectric actuator, there is a remarkable effect that quick and precise positioning becomes possible.

[Brief description of the drawings]

FIG. 1 is a side view and a plan view showing an embodiment of a piezoelectric actuator of the present invention.

FIG. 2 is a sectional view showing another embodiment of the support member.

FIG. 3 is an explanatory diagram showing a driving mode of the piezoelectric actuator shown in FIG. 1;

FIG. 4 is a plan view and a sectional view showing another embodiment of the piezoelectric actuator of the present invention.

FIG. 5 is an XY diagram using the piezoelectric actuator shown in FIG. 4;
The top view showing one embodiment of a table.

FIG. 6 is a plan view showing still another embodiment of the piezoelectric actuator of the present invention.

FIG. 7 is a sectional view showing one embodiment of a piezoelectric element suitably used for the piezoelectric actuator of the present invention.

FIG. 8 is an explanatory view showing a conventional linear motor and its driving form.

[Explanation of symbols]

1.10.10a to 10h.30; piezoelectric actuator 2a.2b.12a to 12d.31a to 31d; first piezoelectric element 3a.3b.13a to 13d.32a to 32d; second piezoelectric element 11.33. 14a to 14d, 34a to 34d; abrasion resistant members 15a, 15b, 24; bearings 16, 23, 26, 35; stage 20, XY table 21, guide rail 22, support member 25, pressure welding jig

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Kazumasa Asumi, 1-2-2 Kiyosumi, Koto-ku, Tokyo Inside the Central Research Institute of Pacific Cement Co., Ltd. (72) Yuyoshi Kato 1-2-2 Kiyosumi, Koto-ku, Tokyo No. 23 Taiheiyo Cement Co., Ltd. Central Research Laboratory (72) Inventor Masako Kataoka 1-2-3 Kiyosumi, Koto-ku, Tokyo (23) Inside Taiheiyo Cement Co., Ltd. (72) Inventor Ryoichi Fukunaga 1-1-2 Kiyosumi, Koto-ku, Tokyo No. 23 Taiheiyo Cement Co., Ltd. Central Research Laboratory (72) Inventor Junko Seki 1-2-2 Kiyosumi, Koto-ku Tokyo Metropolitan Cement Co., Ltd. Central Research Laboratory F-term (reference) 5H680 AA12 BB13 BC10 DD01 DD23 DD59 DD95 EE01 EE10 FF08 GG02 GG11 GG20 GG42

Claims (5)

[Claims] A support member that supports the object to be transported and has a first portion and a second portion that are located across a guide rail; and a length of the guide rail in each of the first portion and the second portion. A first piezoelectric element disposed to sandwich the support member in a vertical direction, and a second piezoelectric element disposed to sandwich the first piezoelectric element, The element expands and contracts in the length direction of the guide rail, and the second piezoelectric element abuts on the guide rail at a predetermined pressure and expands and contracts in a direction in which the second piezoelectric element separates from the guide rail. A relative movement between the piezoelectric actuator and the guide rail. 2. In each of two directions intersecting at a predetermined angle, two first piezoelectric elements are arranged so that the direction of expansion and contraction coincides with the direction, and the first piezoelectric element is disposed at the center of the first piezoelectric element. A connecting member to which one end of the first piezoelectric element in the expansion and contraction direction is joined; a second piezoelectric element to be joined to the other end of the first piezoelectric element in the expansion and contraction direction; and the connection member, A weight body disposed so as to apply a load to the second piezoelectric element via a friction reducing material, wherein the second piezoelectric element expands and contracts in a direction in which a weight is applied from the weight body. Piezoelectric actuator. 3. In each of two directions intersecting at a predetermined angle, two first piezoelectric elements are arranged so that the direction of expansion and contraction coincides with the direction, and the first piezoelectric element is disposed at the center of the first piezoelectric element. A connecting member to which one end of the first piezoelectric element in the expansion and contraction direction is joined; a second piezoelectric element to be joined to the other end of the first piezoelectric element in the expansion and contraction direction; and the connection member, A base portion to which the second piezoelectric element is grounded via an anti-friction material; and a movable weight body disposed so as to apply a load to the second piezoelectric element, wherein the second piezoelectric element is A piezoelectric actuator that expands and contracts in a direction in which a weight is applied from the weight body. 4. The piezoelectric actuator according to claim 2, wherein the predetermined angle is 90 °. 5. The piezoelectric actuator according to claim 1, wherein the piezoelectric element is a laminated piezoelectric element.