JPH0284085A - Piezoelectric motor and driving method thereof - Google Patents

Abstract

PURPOSE:To form a simple miniature piezoelectric-motor for enabling fine rotational movement to be performed, by using a spring as a driving force, and by using the one side of adjacent piezoelectric elements and piezoelectric laminators to expand or shrink spring sections, to use the other side to transmit a rotational force to when the spring sections are controlled. CONSTITUTION:In the state of (a), four piezoelectric elements 3a-3d are arranged to be shrunk or expanded, and are separated from a rotary shaft 4. When the piezoelectric elements 3a, 3c are expanded, then rigid bodies 1a, 1b are moved in the vertical direction, and spring sections 2b, 2d are expanded, and the state of (b) is set. After that, when the piezo-electric elements 3b, 3d are expanded and the rotary shaft is constrained, then the state of (c) is set, and the circumferential surface positions of the piezoelectric elements 3b, 3d on the rotary shaft 4 are rotationally displaced compared with those in the state of (a). In this case, when the piezo-electric elements 3a, 3c are shrunk or expanded, then the spring sections 2b, 2d are shrunk, and the rotary shaft 4 is rotated, and the state of (d) is set. After this, by shrinking or expanding the piezoelectric elements 3b, 3d and by returning the piezoelectric elements 3a, 3c to neutral positions, one cycle is completed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to the rotation drive unit of devices that require fine rotation, such as semiconductor manufacturing equipment, micromanipulators for biological cell manipulation, and optical path control of optical devices. The present invention relates to an applied piezoelectric motor and a method for driving the same.

[Conventional technology]

In recent years, high-precision rotation mechanisms have been required for, for example, positioning of semiconductor manufacturing equipment and optical path control of optical devices. Research is being conducted on the rotational fine movement mechanism used.

There are various methods of drive mechanisms using piezoelectric elements, but an inchworm-shaped mechanism is suitable for performing large stroke movements such as rotation while maintaining accuracy.

FIG. 14 shows the configuration of a rotational fine movement mechanism disclosed in, for example, Japanese Patent Application Laid-Open No. 60-118072, and FIG. 14 (al is its top view, in FIG. 14) is its cross-sectional view,
23a, 23b, 23c, and 23d are driving piezoelectric elements, one end of which is a fixed part 26a.

26b, and the other end is fixed to the movable parts 21a, 21b, and the movable parts 21a, 21b can be slightly deformed in a rotational manner around the hinge part. 29 is a pivot bearing provided in the shape of the hinge portion, and the rotary plate 24 can rotate around this pivot. Fixed piezoelectric elements 23e and 231 are fixed on the movable parts 21a and 21b and are configured to restrain and release the rotary plate 24 by expansion and contraction.

Next, the operation will be explained. First, fixing piezoelectric element 231
3 is retracted to restrain the rotary plate 24 to the movable part 21a, and then the drive piezoelectric element 23a is extended and 23b is retracted.
The movable part 21a and the rotary plate 24 restrained by the movable part 21a rotate in the direction of the arrow. Thereafter, the fixing piezoelectric element 2313 is expanded to release the rotating plate 4, and the driving piezoelectric element 23a is retracted and the driving piezoelectric element 23b is expanded, so that the movable part 21 can return to its original position.

By repeating the above operations, it is possible to give the rotating part a large angle of rotation. Furthermore, driving piezoelectric elements 23c and 23d and fixing piezoelectric element 23 provided on the opposite side of the rotating plate
Since the movable portion f and the movable portion 21b also operate in the same manner as the aforementioned portions, by alternately operating one set of devices, it is possible to rotate the rotating plate without losing its restraint.

[Problem to be solved by the invention]

Conventional piezoelectric motors are constructed as described above, and the inchworm-shaped rotation fine movement mechanism uses separate piezoelectric elements to perform inchworm movement in the rotational direction and to fix the rotating part, which increases the number of piezoelectric elements used. Because the rotating part needs to be deformed,
The device is complicated due to the piezoelectric element itself, its support, and the mechanisms involved in transmitting displacement.

There is a problem in that it is large in size, and it is difficult to use it as a drive motor in fields that require a compact drive device, such as small optical devices and micromanipulators.

This invention was made in order to solve the above-mentioned problems, and its object is to obtain a piezoelectric motor that is small and has a highly accurate rotational fine movement ability.

[Means to solve the problem]

A piezoelectric motor according to a first aspect of the present invention includes a rotating shaft or a rotating cylinder, and a pair of piezoelectric elements or piezoelectric laminates arranged on the outer periphery of the rotating shaft or inside the rotating cylinder and expanding and contracting in the radial direction of the shaft. It consists of one or more rigid body parts with high rigidity and a spring part with low rigidity that fixes the rigid body parts to the fixed part, and one of the pair of piezoelectric elements or piezoelectric laminates is used to expand and contract the spring part. expands and contracts,
The other of the pair is adapted to expand and contract in order to contact the outer periphery of the rotating shaft or the inner periphery of the rotating cylinder and transmit rotational force to the rotating shaft or the rotating cylinder only when the spring part is restored.

Further, a method for driving a piezoelectric motor according to a second invention of the present invention is a method for driving a piezoelectric motor according to the first invention, wherein the rotation by one of the pair of piezoelectric elements or the piezoelectric laminate. When transitioning from contact with one part to contact with the rotating part by the other, one of the elastic parts is contracted and contracted in order to make the spring part expand and contract, and the spring part contacts the rotating part only when the spring part returns to its original state. The other part that contacts and transmits rotational force to the rotating part is extended.

Further, a piezoelectric motor according to a third aspect of the present invention is the piezoelectric motor according to the first aspect, in which a bearing capable of parallel movement of the rotation center axis is used as a bearing supporting the rotation shaft or rotation cylinder. , a function is added in which the rotation axis or the center of the rotation cylinder is moved by expanding the piezoelectric elements or piezoelectric laminates provided on the plurality of rigid body parts.

[Effect]

In the first aspect of the present invention, a spring is used as a driving force, and in order to cause one of the adjacent piezoelectric elements or piezoelectric laminates to expand and contract with the spring part, the other is moved around the outer periphery of the rotating shaft when the spring part returns to its original position. Alternatively, since the structure is used to transmit rotational force by contacting the inner circumference of the rotating cylinder, it is possible to omit the piezoelectric element that fixes the rotating part used in conventional rotary fine movement devices using piezoelectric elements, and the rotating part Since the piezoelectric motor does not deform, it is possible to obtain a piezoelectric motor that is small and has a simple structure and can perform fine rotational movements.

Further, in the second aspect of the present invention, at the time of transition from contact of one of the pair of piezoelectric elements or piezoelectric laminates to the rotating part to contact of the other of the pair of piezoelectric elements or the piezoelectric laminate to the rotating part,
Since the contraction of one side and the expansion of the other side are operated in conjunction with each other, it is possible to suppress slippage on the surface of the shaft, and improve the characteristics and reliability of the motor.

Further, in the third aspect of the present invention, a bearing capable of parallel movement of the rotation center axis is used as a bearing for supporting the rotating shaft or rotating cylinder of the piezoelectric motor of the first invention, and the piezoelectric element or piezoelectric laminated By extending the body, the rotating axis or the center of the rotating cylinder can be moved, so in addition to highly accurate rotation, it is also possible to perform highly accurate linear motion.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a piezoelectric motor according to an embodiment of the first invention, and FIG. 2 is a diagram showing the operating principle of the embodiment shown in FIG. 1. In the figure, la and lb are rigid body part,
2a, 2b, 2c, 2d are spring parts, 3a, 3b, 3c,
3d is a piezoelectric element, and 4 is a rotating shaft.

Next, the operation will be explained.

In the state shown in FIG. 2(a), there are four piezoelectric elements 3a and 3b.

3c and 3d are contracted, and if the sixth piezoelectric elements 3a and 3C, which are separated from or in slight contact with the rotating shaft 4, are expanded, the rigid body parts 1a and lb will change due to the displacement of the piezoelectric elements 3a and 3c. As it moves in the vertical direction, the spring part 2 due to the generated force
b, 2d are stretched to reach the state shown in FIG. 2(b), and at this time, piezoelectric elements 3b, 3
d is a circle on the rotation axis 4 of the piezoelectric elements 3b, 3d. The position of the circumferential surface is rotationally displaced compared to the state shown in FIG. 2(a).

Here, if the piezoelectric elements 3a, 3c are shortened, the rigid body parts 1a, l
The vertical restraint of b is released, the spring parts 2b and 2d contract, and the rotating shaft 4 rotates in the direction of the arrow as shown in Fig. 2(d).
). Thereafter, one cycle is completed by returning the piezoelectric elements 3a, 3c to their neutral positions.The expansion and contraction patterns of the piezoelectric elements 3a, 3C, 3b, and 3d described above are shown in FIG.

By repeating the above operations, it is possible to rotate the piezoelectric element 3 through a large angle and through multiple rotations.
It is also possible to rotate in the opposite direction by switching a, 3c and 3b, 3d.

Although the above description shows the basic operation of the piezoelectric motor according to the present invention, the above-mentioned pattern includes a portion where a large amount of friction occurs between the shaft and the piezoelectric element contact portion. Third
The sections (bl~(C) and <c>~(dl) in the figure correspond to this, and slipping occurs when one piezoelectric element is expanded and the other piezoelectric element expands and contracts, and friction causes the shaft to The amount of rotation and rotational torque will decrease, and the shaft will wear out.

In order to eliminate this slippage, it is sufficient to provide an operation pattern in which the rigid body portion moves without changing the distance between the contact points on the rotation of the shaft. FIG. 4 is a diagram showing an operation pattern of a piezoelectric motor driving method according to an embodiment of the second aspect of the present invention. As shown in this figure, in this embodiment, in order to move from FIG.

It is driven to extend 3d. Therefore, no slipping occurs at the contact point between the piezoelectric element and the rotating shaft in this section, and slipping occurs when transitioning from Fig. 2 (dl to Fig. 2 (a)), but the pressing force at this time is 0. Yes, there will be no reduction in torque or wear on the shaft.

FIG. 5 is a diagram showing an example of a specific configuration of the piezoelectric motor according to the embodiment shown in FIG. This is a compression screw for fixing, and the driving plate 1 is attached to the fixing part 6 via the fixing plate 7 with fixing screws 8. A bearing is provided on the fixed plate 7 and the fixed part 6 to support the rotating shaft 4.

FIG. 6 is a diagram showing the structure of the drive plate 1 shown in FIG.
2a, 12b, 12c, 12d and supporting parts 13a, 13b for support by the fixing part 6 are integrated. Each of the rigid bodies 11a, llb is provided with two seats for housing the piezoelectric elements, and the inner circumference of the drive plate at the seats is thin so as not to hinder the expansion of the piezoelectric elements. Moreover, the spring parts 12 a, 12 b, 12
12d and 12d utilize the bending deformation of a beam with a rectangular cross section, and by giving a specific cross-sectional shape, the rigid body part is deformed in parallel as shown in FIG.

7 to 11 are views showing other embodiments of the present invention, and in these figures, the same reference numerals as in FIG. 1 represent the same or corresponding parts.

The embodiment shown in FIG. 7 is obtained by omitting one side of the opposing piezoelectric elements in the embodiment shown in FIG. 1, and can constitute the smallest piezoelectric motor of the present invention. Further, FIG. 8 shows a configuration in which three sets of piezoelectric elements are used, and the same effect can be obtained even if the number of sets of piezoelectric elements used is different.

Furthermore, as shown in FIGS. 9 and 10, it goes without saying that the same effect can be obtained by changing the shape of the portion corresponding to the spring portion, and as shown in FIG. It can also be in a driven format.

Further, in the above embodiment, the rotary shaft 4 and the cylinder 14 were described as rotating, but it goes without saying that the shaft 4 or the cylinder 14 side can be fixed and the drive plate 1 side can be rotated.

By the way, in precision positioning equipment such as semiconductor manufacturing equipment,
In addition to high-precision rotation, high-precision linear motion is often required. This linear motion is achieved by combining fine motion actuators such as XY child table piezoelectric elements for coarse motion.
There was a problem in that adding a rotation mechanism to this would make the device even larger and more complicated.

FIG. 12 is a diagram showing the configuration of a piezoelectric motor according to an embodiment of the third aspect of the present invention, and FIG. 13 is a diagram showing the operating principle of the embodiment shown in FIG. , 5th
The same reference numerals as in the figure indicate the same or equivalent parts, 9 is the bearing, 1
0 is an elastic support rod that holds the bearing 9 on the fixed part 6.

Next, the operation will be explained.

In the state shown in FIG. 13(a), there are four piezoelectric elements 3a, 3b,
3c and 3d are contracted, and if the piezoelectric element 3a is expanded, as in the state shown in the zeroth order (b), where it is either away from the rotating shaft 4 or in slight contact with it, the bearing 9 of the rotating shaft 4 Since it is elastically supported, the rotating shaft 4 is pushed by the piezoelectric element 4 and moves downward. Similarly, when the piezoelectric elements 3b, 3c, and 3d are expanded, the rotating shaft 4 moves in each direction, so the piezoelectric element 3a.

By operating 3b, 3c, and 3d, the position of the center of the rotation axis can be controlled. In addition, in order to prevent the rotating shaft 4 from tilting when moving, the piezoelectric elements 3a, 3b, 3c, 3
The position of the bearings and the spring constant of the elastic support rod are adjusted so that the force exerted by d acts equally on the two bearings.

In this way, in this embodiment, the bearing 9 that supports the rotating shaft is
Since the configuration is such that the rotation center axis is held by the elastic support rod 10 on the fixed part 6 to enable parallel movement, the piezoelectric elements provided in the rigid body part are arranged facing each other around the rotation center axis. By differentially expanding and contracting the piezoelectric element, the center axis of rotation can be moved in parallel as the piezoelectric element moves. Therefore, by using the piezoelectric motor according to this embodiment, a precision positioning device such as a semiconductor manufacturing device that can perform not only high-precision rotation but also high-precision linear motion can be extremely miniaturized.

〔Effect of the invention〕

As described above, according to the first aspect of the present invention, in the piezoelectric motor, a spring is used as a driving force, and in order to cause one of the adjacent piezoelectric elements or piezoelectric laminates to expand and contract the spring part, the other is moved by the spring part. When the rotating part is restored, it comes into contact with the outer periphery of the rotating shaft or the inner periphery of the rotating cylinder to transmit rotational force, so it fixes the rotating part that was used in conventional rotary fine movement devices using piezoelectric elements. Since the piezoelectric element can be omitted and there is no deformation of the rotating part, it is possible to obtain a piezoelectric motor that is small in size, has a simple structure, and can perform fine rotational movements.

According to a second aspect of the present invention, in the piezoelectric motor driving method for driving the piezoelectric motor according to the first aspect, one of the pair of piezoelectric elements or piezoelectric laminates is brought into contact with the rotating portion by the other. Since the contraction of one side and the expansion of the other side are linked during the transition to contact with the rotating part, it is possible to eliminate slippage that occurs around the shaft, which has the effect of improving the characteristics of the motor. There is.

According to a third aspect of the present invention, in a piezoelectric motor having the same basic configuration as the first aspect, the bearing supporting the rotating shaft or the rotating cylinder is provided with a bearing capable of parallel movement of the central axis of rotation. Since the piezoelectric motor is used, the center of the rotation axis can be moved by extending the piezoelectric element provided on the rigid body. Therefore, by using this piezoelectric motor, it is possible to perform high-precision rotation as well as high-precision rotation. This has the effect of making it possible to extremely downsize precision positioning devices such as semiconductor manufacturing equipment that can perform motions.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of a piezoelectric motor according to an embodiment of the first invention of the present invention, FIG. 2 is a diagram for explaining the basic operation of the embodiment of FIG. 1, and FIG. A diagram showing an example of the operation pattern of the piezoelectric element in the basic operation shown in FIG.
FIG. 4 is a diagram showing an operation pattern of a piezoelectric element in a method for driving a piezoelectric motor according to an embodiment of the second aspect of the present invention, and FIG. 5 is a diagram showing a specific configuration of the piezoelectric motor in FIG. 1.
Figure 6 is a diagram showing the configuration of the drive plate in Figure 5, Figures 7 to 1
Figure 1 is a diagram showing another embodiment of the first invention of the present invention.
FIG. 2 is a diagram showing the configuration of a piezoelectric motor according to an embodiment of the third aspect of the present invention, FIG. 13 is a diagram showing the operation of the embodiment of FIG. 12, and FIG. 14 is a diagram showing a conventional rotation fine movement mechanism. It is a diagram. 1 is a drive plate, 1a is a first rigid body part, 1b is a second rigid body part, 2a to 2d are first to fourth spring parts, 3 is a piezoelectric element, 4
is a rotating shaft, 5 is a compression screw, 6 is a fixed part, 7 is a fixed plate, 8
9 is a fixing screw, 9 is a bearing, and 10 is an elastic support rod. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (3)

[Claims] (1) A rotating shaft or a rotating cylinder, and one or more rigid parts having a pair of piezoelectric elements or piezoelectric laminates arranged on the outer periphery of the rotating shaft or the inner periphery of the rotating cylinder and expanding and contracting in the radial direction of the shaft, respectively. and a spring portion with low rigidity that fixes the rigid body portion to a fixed portion, wherein one of the pair of piezoelectric elements or piezoelectric laminates expands and contracts in order to expand and contract the spring portion. , the other of the pair expands and contracts in order to contact the outer periphery of the rotating shaft or the inner periphery of the rotating cylinder and transmit rotational force to the rotating shaft or the rotating cylinder only when the spring part is restored. piezoelectric motor. (2) A piezoelectric motor driving method for driving a piezoelectric motor according to claim 1, wherein one of the pair of piezoelectric elements or piezoelectric laminates contacts the rotating part and the other of the pair of piezoelectric elements or piezoelectric laminates contacts the rotating part. When transitioning to contact, one of the elastic parts is contracted in order to expand and contract the spring part, while the other part that contacts the rotating part and transmits rotational force to the rotating part is expanded only when the spring part is restored. A method for driving a piezoelectric motor, characterized in that: (3) The piezoelectric motor according to claim 1, further comprising a bearing that supports the rotating shaft or the rotating cylinder and allows the rotation center axis to move in parallel, and includes piezoelectric elements or piezoelectric elements provided on the plurality of rigid body parts. A piezoelectric motor characterized in that the rotating shaft or the center of the rotating tube moves by expanding the laminate.