JPH089664A - Electromechanical conversion actuator - Google Patents

Abstract

(57) [Summary] [Purpose] To suppress the bouncing and rotation of the moving body by applying pressure to the moving body from a prescribed direction. [Structure] A movable body 1 and an inertial body 2 connected to both ends of a piezoelectric element 3, and a pressure member 1 disposed on the upper surface of the movable body 1.
Applied to an electromechanical conversion actuator comprising
When the piezoelectric element 3 is suddenly extended, the moving body 1 overcomes the frictional force and moves to the left. At this time, since the moving body 1 is pressed by the pressing member 11, it does not bounce or rotate. When the piezoelectric element 3 is contracted slowly, the position of the moving body 1 does not change due to the frictional force. When the expansion / contraction of the piezoelectric element 3 is suddenly stopped when the piezoelectric element 3 returns to the original length, the moving body 1 moves to the left by receiving the kinetic energy of the inertial body 2. On the other hand, if the contraction of the piezoelectric element 3 is reversed, the moving body 1 moves to the right. In this way, since the moving body 1 is moved while the pressure applied by the pressurizing member 11 is applied to the center of gravity of the moving body 1, the moving body 1 moves left and right stably without bouncing or rotating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromechanical conversion actuator that moves a moving body by utilizing a force associated with rapid deformation of an electromechanical conversion element.

[0002]

2. Description of the Related Art A piezoelectric element or an electrostrictive element is rapidly expanded or contracted,
An electromechanical conversion actuator that drives a moving body by utilizing the force generated at that time is known (Japanese Patent Laid-Open No. 63-299785).
(See the official gazette). FIG. 6 is a view for explaining the operation of this type of electromechanical conversion actuator, and the operation principle will be described with reference to this figure. The electromechanical conversion actuator shown in FIG. 6 includes a moving body 1 to be driven, an inertial body 2 that generates a force that drives the moving body 1, and a piezoelectric element 3 that expands and contracts in response to an electric signal. Both the body 1 and the inertial body 2 are fixed to the piezoelectric element 3. Although the moving body 1 is movable left and right on the base substrate 4, the moving body 1 does not move in a normal state because a frictional force acts on the contact surface between the moving body 1 and the base substrate 4. On the other hand, an electrode (not shown) is attached to the piezoelectric element 3, and the piezoelectric element 3 expands and contracts in the left-right direction in FIG. 6 by applying a voltage of a predetermined frequency to this electrode.

In order to move the moving body 1 to the left from the state shown in FIG. 6 (a), a voltage having a sharp rising edge is first applied to the piezoelectric element 3 to extend the piezoelectric element 3 to the left and right (FIG. 6).
(B)). As a result, the moving body 1 overcomes the frictional force and moves to the left, while the inertial body 2 moves to the right. Next, as shown in FIG. 6C, when the piezoelectric element 3 is slowly contracted by changing the applied voltage, the moving body 1 stays in place due to the frictional force, while the inertial body 2 is left. Move in the direction. As shown in FIG. 6D, when the piezoelectric element 3 returns to the original length, the supply of the voltage is suddenly stopped to stop the contraction of the piezoelectric element 3. As a result, the moving body 1 moves leftward by the kinetic energy of the inertial body 2 (see FIG. 6).
(See (e)).

On the other hand, in order to move the moving body 1 to the right, first, the piezoelectric element 3 is expanded while the piezoelectric element 3 is expanded.
Shrink sharply. As a result, the moving body 1 moves to the right side in the figure, and the inertial body 2 moves to the left side in the figure. Next, when the piezoelectric element 3 is slowly extended and the voltage supply to the piezoelectric element 3 is suddenly stopped when the piezoelectric element 3 returns to the original length, the moving body is moved by the kinetic energy of the inertial body 3. 1 moves to the right.

When the moving body 1 shown in FIG. 6 is moved by such a principle, the movement of the moving body 1 can be controlled on the order of nanometers. Therefore, the electromechanical conversion actuator of FIG. 6 can be used for positioning control of the sample stage of the semiconductor control device that requires high accuracy.

[0006]

The electromechanical conversion actuator of FIG. 6 moves the moving body 1 to the left or right by repeating the cycle of FIGS. 6 (a) to 6 (e). At that time, in order to increase the moving efficiency of the moving body 1, the frictional force acting on the moving body 1 when the moving body 1 moves as shown in FIGS. 6 (a), 6 (c), 6 (d) at which the movement of No. 1 stops, it is desirable to increase the frictional force acting on the moving body 1 as much as possible. For this reason, in Japanese Patent Application Laid-Open No. 4-207982, as shown in FIG. 7, not only the side surface of the moving body 1 but also the upper surface of the moving body 1 is connected to the inertial body 6 via the piezoelectric element 5 and moved. The frictional force acting on the body 1 can be adjusted.

In FIG. 7, when moving the moving body 1 to the left, for example, first the piezoelectric element 3 is rapidly contracted and the piezoelectric element 5 is rapidly expanded. As a result, the frictional force becomes small, and the moving body 1 easily moves to the left. Next, the piezoelectric element 3 is slowly extended and the piezoelectric element 5 is slowly contracted. As a result, the frictional force of the moving body 1 increases and the moving body 1 becomes hard to move. Thus, by changing the frictional force between the moving body 1 and the base substrate 4, the moving body 1 can be moved efficiently.

However, since the electromechanical conversion actuators shown in FIGS. 6 and 7 move the moving body 1 by the force associated with the rapid deformation of the piezoelectric element 3, when the force is strong, the moving body 1 moves in the moving direction. May bounce or rotate in a direction perpendicular to. In particular, the actuator of FIG. 7 that reduces the frictional force when moving the moving body 1 is likely to cause the above problem. Further, the above problem is likely to occur when the contact surface between the moving body 1 and the base substrate 4 is not flat, or when the expansion / contraction direction of the piezoelectric element 3 and the moving direction of the moving body 1 are deviated.

An object of the present invention is to provide an electromechanical conversion actuator in which the moving body is prevented from bouncing or rotating by pressing the moving body from a predetermined direction.

[0010]

[Means for Solving the Problems] FIGS.
5, the present invention will be described. In the present invention, the electromechanical conversion element 3 expands and contracts according to an electric signal, the moving body 1 connected to one end of the electromechanical conversion element 3, and the electromechanical conversion element 3 are connected. Of the electromechanical conversion element 3 by utilizing the reaction of the force acting on the inertial body 2 according to the expansion and contraction of the electromechanical conversion element 3. The above-described object is achieved by providing a pressurizing means 11 that is applied to an electromechanical conversion actuator that moves in the expansion / contraction direction and pressurizes the moving body 1 from a predetermined direction so that the moving body 1 does not move in a direction other than the expansion / contraction direction. To be done. In the electromechanical conversion actuator according to claim 2, a plurality of electromechanical conversion elements 3 and 14 that expand and contract according to an electric signal, and one ends of the plurality of electromechanical conversion elements 3 and 14 are respectively connected to different places. The moving body 1 and the plurality of inertial bodies 2 and 15 respectively connected to the respective one ends of the plurality of electromechanical conversion elements 3 and 14 that oppose each other, and are used to expand and contract the electromechanical conversion elements 3 and 14. Accordingly, it is applied to an electromechanical conversion actuator that moves the moving body 1 in a plurality of directions by utilizing the reaction of the forces acting on the plurality of inertial bodies 2 and 15, so that the moving body 1 does not move in a direction other than the plurality of directions. In addition, the above object is achieved by providing the pressurizing means 11 for pressurizing the moving body 1 from a predetermined direction. The electromechanical conversion actuator according to claim 3 is the electromechanical conversion actuator according to claim 1 or 2, wherein the upper surface of the moving body 1 is pressed so as to press the moving body 1 from the center of gravity of the moving body 1. The pressing means 11 is arranged at a predetermined position. Claim 4
The electromechanical conversion actuator described in claim 1.
In the electromechanical conversion actuator described in any one of 1 to 3, a protrusion 16 is provided on the lower surface of the moving body 1 along the center of gravity of the moving body 1. An electromechanical conversion actuator according to a fifth aspect is the electromechanical conversion actuator according to any one of the first to third aspects, so that moments of forces acting on the moving body 1 are balanced.
A plurality of protrusions 17 and 18 are provided on the lower surface of the moving body 1.

[0011]

According to the first aspect of the invention, the moving body 1 is moved in the expansion / contraction direction of the electromechanical conversion element 3 by utilizing the reaction of the force acting on the inertial body 2 in response to the expansion / contraction of the electromechanical conversion element 3. While the moving body 1 is being pressed, the moving body 1 is pressed from the predetermined direction by the pressing means 11, so that the moving body 1 does not move in a direction other than the expansion / contraction direction. In the invention according to claim 2, the moving body 1 is moved in any of a plurality of directions by utilizing the reaction of the force acting on the plurality of inertial bodies 2 and 15 according to the expansion and contraction of the plurality of electromechanical conversion elements 3 and 14. While moving, since the moving body 1 is pressed from the predetermined direction by the pressing means 11, the moving body 1 does not move in a direction other than a plurality of directions. According to the third aspect of the invention, the pressing means 11 is provided at a predetermined position on the upper surface of the moving body 1 so that the moving body 1 can be pressed from the center of gravity of the moving body 1. In the invention according to claim 4, since the protrusion 16 is provided on the lower surface of the moving body 1 along the center of gravity of the moving body 1, the pressure force easily acts on the center of gravity line when pressure is applied by the pressing means 11. Become. In the invention according to claim 5, since the plurality of protrusions 17 and 18 are provided on the lower surface of the moving body 1, the moving body 1
It becomes easy to balance the moments of the forces acting on, and the movement of the moving body 1 is stabilized.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used for the purpose of making the present invention easy to understand. It is not limited to.

[0013]

【Example】

-First Embodiment- A first embodiment of the electromechanical conversion actuator according to the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view of a first embodiment of an electromechanical conversion actuator according to the present invention. In FIG. 1, the same components as those of the conventional actuator shown in FIGS.
The difference will be mainly described below. One end of the piezoelectric element 3 shown in FIG. 1 is connected to the moving body 1, and the other end on the opposite side is connected to the inertial body 2. On the upper surface of the moving body 1, a pressing member 1 for pressing the moving body 1 in the vertical direction (downward in FIG. 1).
1 is disposed, and the upper surface of the pressing member 11 is connected to the fixing portion 13 via the bearing 12. In addition,
The pressing member 11 is arranged near the center of the upper surface of the moving body 1 so that the pressing force by the pressing member 11 acts on the center line L of the moving body 1, and is made of an elastic member such as rubber or a disc spring. And leaf springs and spring springs.

On the other hand, the bottom surface of the moving body 1 is in contact with the base substrate 4, and the moving body 1 receives a frictional force F from this contact surface when moving. This frictional force F causes the weight of the moving body 1 to be M,
When the pressure applied by the pressure member 11 is P and the friction coefficient is μ, the formula (1) is given.

## EQU1 ## F = μ (Mg + P) (1) As shown in the equation (1), the frictional force F acting on the moving body 1 is increased by pressurizing by the pressurizing member 11.

FIG. 2 is a perspective view of the electromechanical conversion actuator of FIG. 1 with the fixing portion 13 facing down, in which the base substrate 4 is omitted. As shown in the figure, on the surface of the fixed portion 13, a plurality of columnar bearings 12 are arranged at a constant interval perpendicular to the moving direction of the moving body 1, and these bearings 12 allow the moving body 1 and the pressure member to be pressed. 11
Are integrally movable in the direction of the arrow shown.

The operation of the electromechanical conversion actuator shown in FIGS. 1 and 2 will be described below. First, when the moving body 1 is moved to the left side in FIG. 1, a voltage is applied to an electrode (not shown) attached to the piezoelectric element 3 to extend the piezoelectric element 3 to the left and right.
At this time, when the rise of the voltage applied to the electrodes is made steep, the piezoelectric element 3 expands rapidly, so that the moving body 1 is strongly pushed to the left. When this force exceeds the frictional force F acting on the moving body 1, the moving body 1 moves to the left. At this time, if there is unevenness on the contact surface between the moving body 1 and the base substrate 4, the moving body 1 may bounce or rotate, but the moving body 1 is pressed vertically by the pressing member 11. Therefore, the moving body 1 is not affected by the above.
Moves stably to the left, which is the original direction of movement.

Next, when the piezoelectric element 3 is contracted slowly by changing the phase of the voltage or the like while the piezoelectric element 3 is expanded, the inertial body 2 moves to the left, which is the direction of contraction of the piezoelectric element 3. At this time, the moving body 1 should originally move rightward, which is the direction in which the piezoelectric element 3 contracts.
Is slower, the force for moving the moving body 1 to the right is smaller than the frictional force F acting on the moving body 1. Therefore, the position of the moving body 1 does not change.

When the piezoelectric element 3 is gradually contracted to its original length and the voltage supply to the piezoelectric element 3 is suddenly stopped, the inertial body 2 also stops moving. At this time, the moving body 1 receives a force in the left direction by receiving the kinetic energy that the inertial body 2 had just before the stop. Since this force is larger than the frictional force acting on the moving body 1, the moving body 1 moves to the left. In this case as well, since the moving body 1 is pressed by the pressing member 11, it does not move in a direction other than the left direction. With the above operation, the moving body 1 stably moves to the left.

On the other hand, when moving the moving body 1 to the right side of FIG. 1, first, the piezoelectric element 3 is rapidly contracted. As a result, the moving body 1 overcomes the frictional force F and moves to the right.
At this time, the moving body 1 does not move in a direction other than the right direction because it is pressed by the pressing member 11. Next, when the piezoelectric element 3 is slowly extended and the extension of the piezoelectric element 3 is stopped in a state where the piezoelectric element 3 returns to the original length, the moving body 1
Moves to the right under the force of the kinetic energy of the inertial body 2.

As described above, in the first embodiment, the moving body 1
To press the moving body 1 from the direction perpendicular to the moving direction of
Since the moving body 1 does not bounce or rotate, the force associated with the expansion and contraction of the piezoelectric element 3 can be transmitted to the moving body 1 without loss, and the driving efficiency of the moving body 1 is improved. Further, since the bearing 12 that is rotatable in the moving direction of the moving body 1 is provided on the upper surface of the pressing member 11, the movement of the moving body 1 is not hindered by the pressing member 11.

-Second Embodiment- In the second embodiment described below, the piezoelectric elements 3 are attached to the movable body 1 at a plurality of locations. FIG. 3 is a sectional view of the second embodiment. In FIG. 3, the same components as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals, and the differences will be mainly described below. As shown in FIG. 3, in the electromechanical conversion actuator of the third embodiment, the piezoelectric element 14 and the inertial body 15 are arranged not only on the right side surface of the moving body 1 but also on the left side surface thereof. A pressure member 11 is provided on the upper surface of the same as in the first embodiment.

In the electromechanical conversion actuator of the third embodiment having such a structure, when the moving body 1 is moved to the left side in FIG. 3, for example, the piezoelectric element 14 is rapidly contracted and the piezoelectric element 3 is moved. Stretch rapidly. As a result, a leftward force acts on the moving body 1. Since this force works in common with the piezoelectric elements 3 and 14, the moving body 1 moves to the left at a speed about twice that of the first embodiment. Further, at this time, since the moving body 1 is pressed by the pressing member 11, the moving body 1 does not bounce or rotate.

Next, the piezoelectric element 14 is slowly extended and the piezoelectric element 3 is slowly contracted. In this state, a force acts in the direction of moving the moving body 1 to the right, but the position of the moving body 1 does not change because the frictional force F of the moving body 1 is larger.
When the piezoelectric element 14 expands and the piezoelectric element 3 contracts, and when the piezoelectric elements 3 and 14 both return to their original lengths, the voltage supply to the electrodes of both piezoelectric elements 3 and 14 is suddenly stopped. As a result, a leftward force acts on the moving body 1. Since this force is about twice as large as that in the first embodiment,
The moving body 1 moves to the left at a speed about twice as fast as in the first embodiment. On the other hand, when moving the moving body 1 to the right, the extension order of the piezoelectric elements 3 may be reversed.

As described above, in the second embodiment, the moving body 1
Since the piezoelectric elements 3 and 14 and the inertial bodies 2 and 15 are arranged on two surfaces orthogonal to the moving direction of the moving body 1, the moving speed of the moving body 1 can be improved. Further, since the moving body 1 is pressurized from the direction perpendicular to the moving direction of the moving body 1, the moving body 1 does not bounce or rotate even if the moving speed of the moving body 1 is increased.

In the second embodiment, the piezoelectric elements 3 and 14 and the inertial member 15 are provided on the two surfaces orthogonal to the moving direction of the moving body 1.
However, the piezoelectric element 3 and the inertial body 2 may be provided on another surface. By doing so, the moving body 1 can be moved in a direction other than the lateral direction shown in the drawing.

-Third Embodiment- In a third embodiment described below, a protrusion is provided on the bottom surface of the moving body 1 which comes into contact with the base substrate 4. FIG. 4 is a sectional view of the electromechanical conversion actuator of the third embodiment. As shown in FIG. 4, a protrusion 16 is provided near the center of the bottom surface of the moving body 1, and the bottom surface of the protrusion 16 is in contact with the base substrate 4. Further, when the moving body 1 is pressed by the pressing member 11, the bottom surface of the protrusion 16 is processed to be flat so that the pressing force acts on the center line L of the moving body 1. If the width of the protrusion 16 is too narrow, the moment caused by the force f acting in the moving direction of the moving body 1 and the moment caused by the force in the direction (vertical direction) orthogonal to the moving direction become unbalanced, and the moving body 1 rolls. There is a risk. Therefore, in this third embodiment, the protrusion 1
The width S of 6 is set to satisfy the condition of the expression (2). (2)
In the formula, the force acting on the moving body 1 is f, and the center of gravity G of the moving body 1 is
Is R, the weight of the moving body 1 is M, and the pressing force is P.

[Equation 2] (Mg + P) · S> R · f (2)

As described above, the protrusion 16 is formed on the bottom surface of the moving body 1.
By providing, the area in contact with the base substrate 4 becomes smaller than that in the first embodiment.
It becomes easier to apply the pressing force due to the force on the center of gravity line. Therefore, the bouncing and rotation of the moving body 1 can be effectively prevented. Also,
Since the area of contact is small, it is easy to improve the flatness, and the labor of processing can be reduced.

-Fourth Embodiment- In the fourth embodiment, the moving body 1 is provided with protrusions at a plurality of locations.
The moments of the forces acting on are balanced. FIG. 5 is a cross-sectional view of the fourth embodiment. As shown in the figure, the protrusions 17 and 18 are provided near both ends of the bottom surface of the moving body 1.
Are provided, and the bottom surfaces of the protrusions 17 and 18 are processed to be flat. Other points are common to the third embodiment.

As described above, the protrusions 17 and 1 are formed on both ends of the bottom surface.
8 is provided, the directions of the moments of the forces acting on the protrusions 17 and 18 are opposite to each other, so that the moving body 1 stably moves in the moving direction. Further, since the bottom surfaces of the protrusions 17 and 18 are flat, the pressure applied by the pressure member 11 is applied to the moving body 1.
Can be made to act on the center of gravity line, and the bouncing and rotation of the moving body 1 can be effectively prevented.

In the above embodiment, an example in which the piezoelectric element 3 is used as the electromechanical conversion element has been described, but any element other than the piezoelectric element 3 may be used as long as it can convert an electric signal into a mechanical extension motion, for example, an electrostrictive element. May be used. In each of the above embodiments, the example in which the pressing member 11 is provided separately on the upper surface of the moving body 1 has been described, but the moving body 1 and the pressing member 11 may be integrally formed. In FIG. 2, an example in which a plurality of columnar bearings 12 are provided has been described, but the shape and number of bearings are not limited to the embodiment. Similarly, the shapes and arrangements of the moving body 1, the piezoelectric element 3, and the pressing member 11 are not limited to those in the embodiment. Further, the numbers of the piezoelectric elements 3 and the pressing members 11 connected to the moving body 1 are not limited to those in the embodiment.

In the embodiment thus constructed, the piezoelectric element 3 corresponds to the electromechanical conversion element, and the pressing member 11 corresponds to the pressing means.

[0032]

As described in detail above, according to the present invention, since the moving body is pressurized from the predetermined direction while the moving body is moving, the moving body does not move in any direction other than the expansion / contraction direction. According to the invention described in claim 3, since the moving body is pressed from the center of gravity of the moving body, the moving body is stably pressed in the direction of the center of gravity and does not bounce or rotate during movement. . According to the invention as set forth in claim 4, since the protrusion is provided along the center of gravity of the moving body, when the pressure is applied by the pressurizing means, the pressing force easily acts on the center of gravity. According to the invention described in claim 5, since the plurality of protrusions are provided on the lower surface of the moving body, the moments of the forces acting on the moving body are easily balanced, and the movement of the moving body is stabilized.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of an electromechanical conversion actuator according to the present invention.

FIG. 2 is a perspective view of the electromechanical conversion actuator according to the first embodiment.

FIG. 3 is a sectional view of a second embodiment according to the present invention.

FIG. 4 is a sectional view of a third embodiment according to the present invention.

FIG. 5 is a sectional view of a fourth embodiment according to the present invention.

FIG. 6 is a diagram illustrating an operation of a conventional electromechanical conversion actuator.

FIG. 7 is a sectional view of a conventional electromechanical conversion actuator.

[Explanation of symbols]

 1 moving body 2 inertial body 3 piezoelectric element 4 base substrate

Claims (5)

[Claims] 1. An electromechanical conversion element that expands and contracts in response to an electric signal, a moving body connected to one end of the electromechanical conversion element, and an inertial connection connected to the other end of the electromechanical conversion element that opposes the other end. And an electromechanical conversion actuator that moves the moving body in the expansion and contraction direction of the electromechanical conversion element by using a reaction of a force acting on the inertial body according to the expansion and contraction of the electromechanical conversion element. An electromechanical conversion actuator comprising: a pressurizing unit that pressurizes the moving body from a predetermined direction so that the body does not move in a direction other than the expanding and contracting direction. 2. A plurality of electromechanical conversion elements which expand and contract according to an electric signal, a mobile body in which one end of each of the plurality of electromechanical conversion elements is connected to a different location, and a plurality of electromechanical conversion elements. A plurality of inertial bodies that are connected to the respective other ends that oppose the respective one ends, and a plurality of the movable bodies are utilized by utilizing the reaction of the force acting on the plurality of inertial bodies according to the expansion and contraction of the electromechanical conversion element. In the electromechanical conversion actuator for moving in the direction of, the electromechanical conversion is provided with pressurizing means for pressurizing the moving body from a predetermined direction so that the moving body does not move in a direction other than the plurality of directions. Actuator. 3. The electromechanical conversion actuator according to claim 1, wherein the pressing unit presses the moving body from a center of gravity of the moving body at a predetermined position on the upper surface of the moving body. An electromechanical conversion actuator characterized in that 4. The electromechanical conversion actuator according to claim 1, wherein a protrusion is provided on a lower surface of the moving body along a center line of the moving body. Conversion actuator. 5. The electromechanical conversion actuator according to claim 1, wherein a plurality of protrusions are provided on a lower surface of the moving body so that moments of forces acting on the moving body are balanced. An electromechanical conversion actuator characterized in that