JPH02211069A - Actuator - Google Patents

Abstract

PURPOSE:To miniaturize an apparatus by changing the direction and magnitude of displacement generated by a stretching means expanding and contracting like a piezoelectric element, etc., and by driving a driven object through displacement after changing the direction and magnitude of said displacement. CONSTITUTION:When a piezoelectric element 18 is stretched, a relative space between first and third parallel members 11, 13 is expanded and accordingly, first and second connecting members 15, 16 relatively rotate with respect to said first and third parallel members, respectively. By said rotation, a second parallel member 12 is relatively displaced parallel to the first and third parallel members 11, 13 in the extended direction. That is, a displacement-changing mechanism 17 is deformed into a state indicated by two dotted chain lines and the direction and magnitude of displacement of said piezoelectric element 18 is changed to a relative displacement between the first and third parallel members 11, 13 and the second parallel member 12, and an object is driven by said displacement. Also, when the space between the first and third parallel members 11, 13 is contracted, said operation is conducted in the reverse order.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention converts the direction and magnitude of displacement generated by an expanding/contracting means such as a piezoelectric element, and uses the converted displacement to transform a driven object. Regarding actuators that drive.

[Conventional technology]

An example of such an actuator is disclosed in Japanese Patent Application Laid-Open No. 60-62
A piezoelectric motor disclosed in Japanese Patent No. 880 is known. In the piezoelectric motor disclosed in the publication, as shown in FIG. A plurality of connecting members 3 are provided to connect them to form a torsion coupler 5, and a piezoelectric vibrator 6 is attached to the outside of a parallel plate 2 constituting the torsion coupler 5. When a high frequency voltage is applied to this piezoelectric vibrator 6 and the piezoelectric vibrator 6 is vibrated in a direction perpendicular to the parallel plates 1 and 2,
The direction and amplitude of vibration are changed by the torsion coupler 5, and the parallel plate 1 constituting the torsion coupler 5 vibrates with an elliptical locus of motion, as shown. By pressing the rotor 7 against the parallel plate 1, the rotor 7 can be moved along the upper surface of the parallel plate 1.

However, in the piezoelectric motor shown in FIG. 14, since the piezoelectric vibrator 6 is disposed outside the torsion coupler 5, it is difficult to miniaturize the device.

[Problem to be solved by the invention]

In view of the above-mentioned circumstances, the present inventor utilized the principle of converting the direction and amplitude of vibration in the piezoelectric motor shown in FIG. As shown in FIG. 2, an actuator (unpublished) was devised in which a piezoelectric element 10 is disposed between parallel flat plates 1 and 2 constituting a displacement conversion mechanism 8. The piezoelectric element 10 is a stack of piezoelectric materials that generate strain (displacement) or force depending on the intensity of the applied voltage when a voltage is applied. The connecting member 3 is configured to swing about a joint portion of the connecting member 3 with the parallel plate 2 as a fulcrum.

As shown in FIG. 15, the dimensions of each part of this actuator are as follows: L1 piezoelectric element 10
ΔL1 is the increase in the mark caused by the elongation of ΔL1 is the distance in the direction in which the parallel plates 1 and 2 extend between both ends of the connecting member 3 is S, and the parallel plate 1.2 caused by the elongation of the piezoelectric element 10 is S.
If the relative movement distance between the parallel plates 1.2 in the direction in which they extend is defined as X, then the relative movement distance X can be approximately determined by the following equation.

X-ΔL (L/S) Therefore, the parallel plate 1 produced by the elongation of the piezoelectric element 10
, the relative movement distance X between the two is L/S times the displacement (ΔL) generated by the piezoelectric element 10.

Here, if L = 20 ms and S -1am,
L/5-20, which means that a displacement 20 times greater than the elongation displacement generated by the piezoelectric element 10 is obtained. That is, if the maximum displacement generated by the piezoelectric element 10 is 20 μm, this actuator can expand this to 0.4 μm.

In this case, the magnitude of the force that can be applied from the actuator to the driven object decreases in approximately inverse proportion to the increase in displacement, and becomes approximately 1/20 of the force generated by the piezoelectric element 10.

Furthermore, as shown in FIG. 16 or 17, if the parallel plates 1 and 2 are formed into an annular or disk shape, the displacement generated by the piezoelectric element 10 can be converted into a circumferential displacement. The actuator shown in FIG. 16 has a structure in which a piezoelectric element 10 is arranged between a plurality of connecting members 3 connecting parallel flat plates 1 and 2 formed in an annular shape. The actuator shown in the figure has a connecting member 3 at the outer periphery between parallel flat plates 1 and 2 formed in the shape of a disk.
A piezoelectric element 1 is connected to the center of the parallel plates 1 and 2.
It has a structure in which 0 is arranged.

In this case, the relative rotation angle α generated between the parallel plates 1 and 2 is determined by the following equation, where R is the distance from the center of the connecting member 3.

α■ Then, it can be found by the following formula.

T-RnF (S/L) As mentioned above, in the actuators shown in FIGS. 15, 16, and 17, a piezoelectric Since the element 10 is arranged, compared to the piezoelectric motor shown in FIG.
It is small.

However, in the actuators shown in FIGS. 15 and 16, when the piezoelectric element 10 expands, the piezoelectric element 10
Due to the relative displacement of the parallel plates 1 and 2, the parallel plates 1 and 2 either collapse as shown in FIG. 18 or receive shearing force as shown in FIG. 19.

In the actuator shown in FIG. 17, although the piezoelectric element 10 does not fall, it is twisted due to the relative rotational displacement between the parallel plates 1 and 2, and is subjected to shearing force due to this twisting.

Such tilting of the piezoelectric element 10 and shearing force acting on the piezoelectric element 10 act as resistance to actuator operation, and also adversely affect the life of the piezoelectric element 10.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, it is an object of the present invention to provide an actuator that can be constructed in a small size and that does not cause collapse or shear force to be applied to the expansion/contraction means such as piezoelectric elements.

[Means to solve the problem]

In order to achieve the above object, in the actuator according to the present invention, first and second parallel members are provided parallel to each other, and at least two first connecting members parallel to each other and inclined with respect to the first and second parallel members are provided between the first and second parallel members. a third parallel member is provided parallel to the second parallel member, and at least one parallel member is provided between the second and third parallel members and is inclined in a direction opposite to the first connecting member with respect to the second parallel member. Connected by two second connecting members, the distance between both ends of the first connecting member in the direction in which the parallel members extend, and the distance between both ends of the second connecting member in the direction in which the parallel members extend. a displacement conversion mechanism formed to be substantially equal;
and an expansion/contraction means provided between the third parallel members to expand/contract the relative distance therebetween.

Further, the first and second connecting members of the displacement conversion mechanism are arranged on a circumference centered on one point, the first, second and third parallel members are connected, and the second parallel member is connected to the first and second parallel members. It may also be formed by twisting three parallel members around the - point.

[Effect]

With such a configuration, in the actuator according to the present invention, relative displacement occurring between the first and second parallel members in the direction in which the parallel members extend;
The relative displacement that occurs between the second and third parallel members is canceled out, and no relative displacement occurs between the first and third parallel members, and the second Only the parallel members of cause relative displacement.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 13.

FIG. 1 is a perspective view showing a portion of an embodiment of an actuator according to the present invention.

As shown in the figure, the actuator according to the present invention includes flat first, second, and third parallel members 11, 12, and 13 that are provided parallel to each other, and a first parallel member 11 and a second parallel member 12 that are connected to each other. a flat first connecting member 15 connected to the
It has a displacement converting mechanism 17 that includes a flat second connecting member 16 that connects the second parallel member 12 and the third parallel member 13 to each other. The first parallel member 11, the second parallel member 12, and the third parallel member 13 are the first parallel member 11 and the second parallel member 13.
The mutual spacing between the parallel members 12 and the second parallel member 12 and the third parallel member 12
The first connecting member 15 is arranged so that the mutual spacing with the parallel members 13 is equal to each other, and the first connecting member 15 is arranged in the direction in which the first, second, and third parallel members 11, 12, and 13 extend (hereinafter, The second connecting member 16 is provided so as to be inclined with respect to the extending direction (simply referred to as the extending direction), and the second connecting member 16 is provided so as to be inclined in the opposite direction to the first connecting member 15 with respect to the extending direction, The first connecting member 15 and the second connecting member 16 are arranged symmetrically with respect to the second parallel member 12. Further, a distance t1 in the extending direction between both ends of the first connecting member 15 and a distance t in the extending direction between both ends of the second connecting member 16.
2 are formed to be equal.

Between the first parallel member 11 and the third parallel member 13,
A piezoelectric element 18 is provided as an expansion/contraction means for expanding/contracting these relative intervals. The piezoelectric element 18 is a layered piezoelectric material that generates strain (displacement) or force depending on the intensity of the applied voltage when a voltage is applied. It penetrates with a gap of , and abuts and is fixed to the first and third parallel members 11 and 13 at both their upper and lower ends.

Note that, as will be described later, the through-hole 20 allows the second parallel member 12 and the piezoelectric element 18 to interfere with each other even when the piezoelectric element 18 expands and contracts and the second parallel member 12 is driven in the extending direction. To prevent this, the dimension in the extending direction is larger than the dimension in the direction perpendicular to this.

The operation of the actuator formed in this way will be explained with reference to FIG. 2.

FIG. 2 is a side view of the actuator configured as described above.

As shown in the figure, when the piezoelectric element 18 is expanded, the relative distance between the first and third parallel members 11 and 13 is expanded, and accordingly, the first and second connecting members 15 and 16 are connected to the first parallel member, respectively. With respect to the member 11 and the third parallel member 13,
rotate relative to each other.

In other words, since the lengths of the first connecting member 15 and the second connecting member 16 do not change, the lengths of the first connecting member 15 and the second connecting member 16 do not change. Rotate.

This rotation causes the second parallel member 12 to move in parallel relative to the first and third parallel members 11 and 13 in the extending direction. That is, the displacement conversion mechanism 17 deforms into the state shown by the two-dot chain line in FIG. This is converted into a relative displacement between the parallel member 12 and the parallel member 12.

Therefore, if the first and third parallel members 11 and 13 are fixed in the extending direction, the object (not shown) can be driven by the displacement of the second parallel member 12; If the two parallel members 12 are fixed, an object (not shown) can be driven by displacement of the first and third parallel members 11 and 13 with respect to the second parallel member 12.

Note that the piezoelectric element 18 is expanded by applying a voltage to the piezoelectric element 18 from a drive circuit (not shown).

By the way, regarding the relative positional relationship between the first parallel member 11 and the third parallel member 13, as the piezoelectric element 18 expands, the mutual interval expands, but in the extending direction, the first
The relative displacement occurring between the second parallel members 11 and 12 and the relative displacement occurring between the second and third parallel members 12 and 13 are canceled out, and the relative displacement occurring between the first and third parallel members 11 and 13 is No relative displacement occurs, and only the second parallel member 12 causes a relative displacement with respect to the first and third parallel members 11 and 13.

Therefore, the piezoelectric element 18 does not fall down, and no shearing force is applied to the piezoelectric element 18.

The above description of the operation is for the operation when the piezoelectric element 18 is expanded, but the piezoelectric element 18
If the space between the first and third parallel members 11 and 13 is contracted by using something that contracts when a voltage is applied, the opposite operation will occur. In this case, due to the contraction of the piezoelectric element 18, the first and third parallel members 11
and 13 also contract, and the second parallel member 12 is displaced in the direction opposite to the direction in which the piezoelectric element 18 extends in the extending direction. Note that, also in this case, no relative displacement occurs between the first parallel member 11 and the third parallel member 13 in the extending direction. Therefore, the piezoelectric element 18 does not fall down, and no shearing force is applied to the piezoelectric element 18.

FIGS. 3 to 7 schematically show modified examples of the actuator according to the present invention described above.

First, in the actuator shown in FIG. 3, the first and second connecting members 15 and 16 constituting the displacement converting mechanism 17 are arranged alternately in the extending direction,
This is a so-called staggered arrangement. The other configurations are similar to those of the actuator shown in FIGS. 1 and 2.

4 to 7 are side views of the actuator seen from the extending direction, and in the actuator shown in FIG. 4, between the first parallel member 11 and the third parallel member 13, Two second parallel members 12 are spaced apart from each other and arranged in parallel, the first and second parallel members 11 and 12 are connected to each other by a first connecting member 15, and the second and third parallel members 12 and 13 are connected to each other by a first connecting member 15. They are connected by a second connecting member 16, and a piezoelectric element 18 is arranged between these second parallel members 12.

In the actuator shown in FIG. 5, the dimensions in the width direction of the first and third parallel members 11 and 13 are made larger than the second parallel member 12, and a first
and the third parallel members 11 and 13 are made to protrude, and the protruding portions of the first parallel member 11 and the third parallel member 13 are opposed to each other so that the space between them is not blocked by the second parallel member 12, and the first
A piezoelectric element 18 is arranged between the third parallel members 11 and 13.

In the actuator shown in FIG. 6, the first
And the width dimension of the third parallel members 11 and 13 is enlarged to make the first and third parallel members 11 and 13 protrude on both sides of the second parallel member 12, so that the first and third parallel members 11 and 13 protrude. It has a structure in which the parts are opposed to each other and piezoelectric elements 18 are arranged on the protruding parts on both sides.

Furthermore, in the actuator shown in FIG.
The mutual distance between the second and third parallel members 12 and 13 is made larger than the mutual distance between the second parallel members 11 and 12, and at the same time, the second connecting member 16 is made larger than the first connecting member 15.
The displacement converter 17 has a longer length. Even in this case, the distance between both ends of the first connecting member in the extending direction is equal to the distance between both ends of the second connecting member in the extending direction. Therefore, similar to the actuator shown in FIGS. 1 and 2, the piezoelectric element 18
Due to the expansion and contraction, the relative distance between the first and third parallel members 11 and 13 expands and contracts, and accordingly, the first and second connecting members 15 and 16 are connected to the first parallel member 11 and the third parallel member 13, respectively. It rotates relative to the other. This rotation causes the second parallel member 12 to move in parallel relative to the first and third parallel members 11 and 13 in the extending direction. That is, the displacement conversion mechanism 17 deforms into the state shown by the two-dot chain line in FIG.
and the second parallel member 12.

Furthermore, regarding the relative positional relationship between the first parallel member 11 and the third parallel member 13, the mutual spacing expands and contracts due to the expansion and contraction of the piezoelectric element 18, but no relative displacement occurs in the extending direction. Therefore, the piezoelectric element 18 does not fall down, and no shearing force is applied to the piezoelectric element 18.

Further, FIGS. 8 and 9 show an actuator having a displacement conversion mechanism 20 that converts the linear displacement of the piezoelectric element 18 into a relative rotational displacement between the first and third parallel members 11 and 13. FIG. 8(a) is a plan view of the actuator, FIG. 8(b) is a longitudinal sectional view thereof, and FIG. 9 is a developed side view thereof.

In the actuator shown in FIGS. 8 and 9,
Basically, the displacement conversion mechanism 20, similar to the displacement conversion mechanism 17 described above, is a flat plate-shaped IJl provided in parallel to each other.
, second and third parallel members 11, 12, 13, a flat first connecting member 15 that interconnects the first parallel member 11 and the second parallel member 12, and a second parallel member 12 and a third parallel member It is composed of a flat second connecting member 16 that connects the members 13 to each other. However, the parallel members 11% 12 and 13 are formed as annular flat plates, and their centers are arranged in a straight line. In addition, the first and second connecting members 1
5 and 16 are arranged on a circumference centered on a straight line in which the centers of the parallel members 11, 12, and 13 coincide, and between the first and second parallel members 11 and 12, and between the second and third parallel members. The members 12 and 13 are connected to each other.

The displacement conversion mechanism 20 first provides the connecting members 15 and 16 perpendicularly to the parallel members 11, 12, 13, and then arranges the second parallel member circularly relative to the first and third parallel members 11, 13. By relative rotation in the circumferential direction, the connecting members 15 and 16 are twisted and formed at an angle with respect to the parallel members 11.degree. 12.13, as shown in FIG. In addition, by cutting or casting,
It is also possible to form the displacement converting mechanism 20 with the connecting members 15, 16 initially inclined relative to the parallel members.

Furthermore, in the actuator shown in FIG.
The inner diameters of the third parallel members 11 and 13 are smaller than the inner diameter of the second parallel member 12, and the portions of the first and third parallel members 11 and 13 that protrude inward from the second parallel member 12 are spaced from each other. A piezoelectric element 18 is disposed at , and the opposing portions of the first and third parallel members 11 and 13 and the second parallel member 12 are connected by connecting members 15 and 16. Further, the outer diameter of the second parallel member 12 is the same as that of the first parallel member 12.
And the outer diameter of the second parallel members 11 and 13 is larger than that of the second parallel members 11 and 13. Therefore, as described later, the second parallel member 12
When trying to drive an object by the rotational displacement of
This rotational displacement can be easily extracted from the outer circumference of the second parallel member 12.

The operation of the actuator configured in this way will be explained.

When the distance between the first and third parallel members 11 and 13 is extended by the piezoelectric element 18, the first and second connecting members 15 and 16 are released from their twisting. By releasing the connecting member from twisting, the second parallel member 12
is adapted to be rotated relative to the first and third parallel members 11 and 13, so that linear displacement of the piezoelectric element 18 is converted into rotational displacement in the circumferential direction.

Therefore, if the first and third parallel members 11 and 13 are fixed in the circumferential direction, the object (not shown) can be driven by the displacement of the second parallel member 12; If the two parallel members 12 are fixed in the circumferential direction, the second parallel members 1 of the first and third parallel members 11 and 13
A target object (not shown) can be rotationally driven by rotational displacement with respect to 2.

10 to 13 show the linear displacement of the piezoelectric element 18 in the first
and a modification of the actuator having a displacement conversion mechanism 20 that converts the relative rotational displacement between the third parallel members 11 and 13.

FIG. 10 is a developed side view similar to FIG. 9, and the actuator shown in this figure has a structure in which the first and second connecting members 15 and 16 are alternately arranged in a staggered manner in the circumferential direction. The other structures and their operations are as follows:
It is similar to the actuator shown in FIG.

11(a), 12(a), and 13(a) are plan views of modified examples of the actuator having the displacement conversion mechanism 20, and FIG. 11(b), figure(
b) and FIG. 13(b) are respective longitudinal cross-sectional views.

In the actuator shown in FIGS. 11(a) and 11(b), the outer diameters of the first and third parallel members 11 and 13 constituting the displacement conversion mechanism 20 are formed larger than the outer diameter of the second parallel member 12. A piezoelectric element 18 is disposed between the portions of the first and third parallel members 11 and 13 that protrude outward from the second parallel member 12. Further, the inner diameter of the second parallel member 12 is smaller than the inner diameter of the first and second parallel members 11 and 13, and the other structure and operation are shown in FIGS. 8 and 9. It is the same as the actuator.

In the actuator shown in FIGS. 12(a) and 12(b), U-shaped notches 12a are formed in the second parallel member 12 at predetermined intervals along the circumferential direction, and adjacent notches 12a are formed in the second parallel member 12 at predetermined intervals. 12a between the first and second connecting members 1
5 and 16 are disposed, and a piezoelectric element 18 is disposed between the first and third parallel members 11 and 13 by penetrating the notch 12a, resulting in a t9 structure. Note that the notch 12a
A predetermined gap is provided between the piezoelectric element 18 passing through the piezoelectric element 18 and the second parallel member 12 in order to avoid interference therebetween. The actuator configured in this manner operates in the same manner as the actuator shown in FIGS. 8 and 9.

Furthermore, in the actuator shown in FIGS. 13(a) and 13(b), through holes 12b are formed in the second parallel member 12 at predetermined intervals along the circumferential direction, and adjacent through holes 12b are First and second connecting members 15 and 16 are disposed between them, and the piezoelectric element 18 passes through the through hole 12b and connects the first
and the third parallel members 11 and 13 are arranged between each other. Note that the piezoelectric elements 18 are arranged as follows, for example:
A through hole 11 is provided in the first parallel member 11 similarly to the through hole 12a.
A is drilled, the piezoelectric element 18 is inserted through the through hole 11a, and then the through hole 11a is closed with a lid 21 or the like that is screwed into the through hole 11a.

Further, a predetermined gap is provided between the piezoelectric element 18 passing through the through hole 11a and the second parallel member 12 in order to avoid interference between them. The actuator configured in this manner operates in the same manner as the actuator shown in FIGS. 8 and 9.

In the actuator having the displacement conversion mechanism 20 described above, the first, second, and third parallel members 11, 12, and 13 constituting the displacement conversion mechanism 20 are annular flat plates, but the shape is The shape is not limited to an annular shape, but may be a polygonal shape such as a triangle or a quadrangle.

In the embodiments described above, the displacement conversion mechanisms 17 and 20 have rigid frame structures, but may have truss structures.

〔Effect of the invention〕

As explained above, in the actuator according to the present invention, the first and second parallel members are provided parallel to each other, and these are connected to each other by at least two first connecting members parallel to each other and inclined with respect to the first and second parallel members. A third parallel member is provided parallel to the second parallel member, and the second and third parallel members are provided in parallel with each other.
between the two ends of the first connecting member in the direction in which the parallel members extend, by at least two second connecting members parallel to each other and inclined in the opposite direction to the first connecting member with respect to the parallel members; a displacement converting mechanism formed so that the distance between the two ends of the second connecting member in the direction in which the parallel members extend is approximately equal; and a displacement converting mechanism provided between the first and third parallel members; Since the configuration includes an expansion/contraction means for expanding/contracting the relative distance, the first and second
In the direction in which the third parallel member extends, the relative displacement that occurs between the first and second parallel members and the relative displacement that occurs between the second and third parallel members are offset, and the first and third parallel members No relative displacement occurs between the parallel members, and only the second parallel member causes relative displacement with respect to the first and third parallel members, causing collapse or shearing of the expansion/contraction means such as piezoelectric elements. No force is applied, and a compact actuator with high energy conversion efficiency can be constructed.

Further, the first and second connecting members of the displacement conversion mechanism are arranged radially around one point to connect the first, second and third parallel members, and the second parallel member is connected to the first and third parallel members. If it is twisted around the - point, the linear displacement caused by the expansion/contraction means can be converted into rotational displacement.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the actuator according to the present invention that produces linear displacement, FIG. 2 is a front view of the actuator shown in FIG. 1, and FIG. 3 is a modification of the actuator shown in FIG. 1. Front view schematically showing, Figures 4 and 5
6 and 6 are side views schematically showing a modification of the actuator shown in FIG. 1, FIG. 7 is a front view schematically showing a modification of the actuator shown in FIG. 1, and FIG. figure(
a) and (b) are a plan view and a vertical sectional view showing an embodiment of the actuator according to the present invention that produces rotational displacement, FIG. 9 is a developed side view of the actuator shown in FIG. 8, and FIG.
The figures are a developed side view showing a modification of the actuator shown in Fig. 8, Fig. 11 (a) and (b), and Fig. 12 (a).
and (b), Figures 13 (a) and (b) are respectively No. 8
FIG. 14 is a front view showing a conventional actuator, and FIG. 15 is a plan view and longitudinal cross-sectional view showing a modified example of the actuator shown in the figure. Front view of actuator, 16th
Figures (a) and (b) and Figures 17 (a) and (b) are actuators devised by the present inventor to miniaturize conventional actuators, and are different from the actuator shown in Figure 15. The plan view and developed side view of the actuator, FIGS. 18 and 19, are diagrams for explaining the problems of the actuator shown in FIGS. 15 and 16. 11... First parallel member, 12... Second parallel member, 1
3... Third parallel member, 15... First connecting member, 16
... second connection member, 17 ... displacement conversion mechanism, 18.
... Piezoelectric element, 20... Displacement conversion mechanism. Patent Applicant Honda Motor Co., Ltd. Representative Patent Attorney Yoshiki Hase
Mountain 1) Row of rows of legs 2nd figure forklift jfJ Figure 1 (b) ) Figure 13 (b) Figure 13 (b) Figure 13 (b) Figure 13 (b) Figure 13 (b) Figure 13 (b) Figure 13 (b) Figure 13 (b) Figure 13 (b) (b) Millet? Machine rice J Figure 16 (0) 嘱? 沫米 4 rows Figure 17

Claims (2)

[Claims] 1. first and second parallel members are provided parallel to each other, and are connected to each other by at least two first connecting members that are inclined and parallel to each other, and a second parallel member that is parallel to the second parallel member. three parallel members are provided, and the second and third parallel members are connected to each other by at least two second connecting members that are inclined in the opposite direction to the first connecting member and parallel to each other, and a distance between both ends of the first connecting member in the direction in which the member extends;
a displacement converting mechanism formed such that the distance between both ends of the second connecting member in the direction in which the parallel member extends is approximately equal; and a displacement converting mechanism provided between the first and third parallel members, An actuator characterized by comprising: expansion and contraction means that expands and contracts the relative distance. 2. Claim characterized in that the first and second connecting members constituting the displacement conversion mechanism are arranged on a circumference centered at one point with respect to the parallel members, instead of being provided parallel to each other. 1. The actuator according to 1.