JP2000249207A - Displacement enlarging mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized displacement magnifying mechanism, having a high resonance frequency, which is capable of obtaining a large displacement. SOLUTION: A displacement enlarging mechanism has a first arm 22 supported on a supporting member 20 through a first resilient portion 18 at a base end side thereof, a second arm 26 supported on a supporting member 20 through a second resilient portion 24 at a base end side thereof, a connecting member 28 connecting the first arm 22 and the second arm 26, and an actuator which is capable of exerting a predetermined pressing force to the first arm 22. The first resilient portion 18 and the second resilient portion 24 are relatively different in shape from each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement magnifying mechanism used for finely moving a table of, for example, a scanning probe microscope or a scanning laser microscope.

[0002]

2. Description of the Related Art Conventionally, for example, as shown in FIG.
An arm 6 whose base end is supported by a base 4 via an elastic portion (for example, an arcuate hinge) 2, and a predetermined pressing force via a pressing portion 8 provided at a portion of the arm 6 near the elastic portion 2. (For example, a laminated piezoelectric body) 10 capable of causing the arm 6 to act on the arm 6 is known. Note that the actuator 10 is fixed to the base 4.

According to such a displacement enlarging mechanism, when the actuator 10 is displaced by a predetermined length Y ₁ and a predetermined pressing force is applied to the pressing portion 8, the distal end (displacement output end) 6 a of the arm 6 is moved to Y. Can be displaced by _two .

In this case, the displacement Y of the actuator 10
₁ and the distal end of the arm 6 (displacement output end) 6a displacement of Y ₂ of satisfying the following relationship. Y ₂ / Y ₁ = L ₂ / L ₁ L ₁ : Length from elastic portion 2 to pressing portion 8 L ₂ : Length from elastic portion 2 to tip 6a of arm 6 according to lengthen 6 of length L _2, it is possible to increase the displacement of Y ₂ of the tip of the arm 6 (displacement output end) 6a.

[0005]

[SUMMARY OF THE INVENTION However, in order to increase the displacement of Y ₂ of the tip (displacement output end) 6a of the arm 6, it is necessary to increase the length L ₂ of the arm 6,
For this reason, the displacement enlarging mechanism becomes large in the length direction.

To realize a small displacement enlargement mechanism capable of obtaining a large displacement, for example, FIG.
A displacement enlargement mechanism as shown in (b) has been proposed (see “Types and Applications of Piezoelectric Actuators”, Nobuyuki Iwatsuki, Mechanical Design, 36, 8 (1992)).

[0007] In addition to the configuration shown in FIG. 4A, the displacement enlarging mechanism further includes an output arm 12 provided in parallel above the arm 6. The output arm 12 has its base end side supported by the base 4 via an elastic portion (for example, an arcuate hinge) 14. A portion of the output arm 12 near the elastic portion 14 has a connection portion having elasticity (for example, , An arcuate hinge 16 is connected to the distal end 6 a side of the arm 6.

According to such a displacement enlarging mechanism, the actuator 10 is displaced by a predetermined length Y ₁ and the arm 6 is displaced.
When the tip (displacement output end) 6a is displaced by Y _2, the pressing force corresponding to the displacement amount Y ₂ acts on the output arm 12 via the connection 16, as a result, the output arm 12 tip (displacement an output terminal) 12a can be largely displaced by Y _3.

However, in the displacement enlarging mechanism shown in FIG. 4B, the length L of the arm 6 and the output arm 12 in the longitudinal direction (specifically, from the elastic portion 2 of the arm 6 to the output arm 12). Although it is possible to reduce the length L) up to the elastic portion 14, the height H of the displacement enlarging mechanism in the height direction is increased by the additional output arm 12 provided in parallel above the arm 6. . As a result, there arises a problem that the displacement enlarging mechanism becomes large in the height direction.

Further, the displacement enlarging mechanism described above (FIG. 4)
When (a) and (b) are used in, for example, a scanning probe microscope, it is required to constitute a displacement magnifying mechanism excellent in responsiveness with high positioning speed between a probe and a measurement point of a sample. . In order to satisfy this requirement, it is necessary to increase the resonance frequency of the entire displacement enlarging mechanism. However, in the displacement enlarging mechanism described above (particularly, see FIG. 4B), the elastic portion 2 of the arm 6 and the elastic portion 14 of the output arm 12 increase the resonance frequency of the entire displacement enlarging mechanism. The above considerations are not taken into account (the elastic part 2 and the elastic part 14 are formed in the same shape).

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a displacement enlargement mechanism having a high resonance frequency and capable of obtaining a large displacement. .

[0012]

In order to achieve such an object, a displacement enlarging mechanism according to the present invention comprises a first arm having a base end supported by a support member via a first elastic portion; The second end of which the base end is supported by the support member via the second elastic portion
Arm, a connecting member for connecting the first arm and the second arm, and an actuator capable of applying a predetermined pressing force to the first arm. The elastic portions are configured to have relatively different shapes.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A displacement magnifying mechanism according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

As shown in FIGS. 1A to 1C, the displacement enlarging mechanism according to the present embodiment has a first arm whose base end is supported by a support member 20 via a first elastic portion 18. 22 and
A second arm 26 whose base end is supported by the support member 20 via the second elastic portion 24, a connecting member 28 connecting the first arm 22 and the second arm 26, and a first arm And an actuator 30 capable of applying a predetermined pressing force to the first and second elastic portions 1.
8, 24 are configured to have relatively different shapes.

The first and second arms 22 and 26 both extend in the direction of arrow X. The first arm 22 can transmit the pressing force of the actuator 30 to the first arm 22. A possible pressing portion 32 is provided near the first elastic portion 18. In this case, the pressing portion 32 is preferably formed of a material having higher rigidity than the first arm 22, and can transmit the pressing force of the actuator 30 to the first arm 22 without being concentrated. It is preferable to form such a shape as possible (for example, a round shape or a substantially triangular shape).

The support member 20 is fixed to a base 34, and has an opening 36 (see FIG. 1B) having a size that allows the actuator 30 to be inserted and arranged in the arrow Y direction (the direction orthogonal to the arrow X direction). ).

The actuator 30 is fixed to a base 34.
6 extend in the direction of arrow Y toward the first arm 22. The extending end of the actuator 30 is in contact with a pressing portion 32 provided on the first arm 22. As the actuator 30, for example, a laminated piezoelectric body can be used, and by applying a predetermined voltage, the actuator 30 can be expanded and contracted by a desired amount in the arrow Y direction.

The connecting member 28 includes a connecting arm 38 extending in the arrow Y direction, and first and second connecting elastic portions 40 and 42 provided at both ends of the connecting arm 38 in the arrow Y direction.
The connecting arm 38 is connected to the first and second arms 22 and 26 via the first and second connecting elastic portions 40 and 42. Specifically, the connecting arm 38 is connected to the distal end side of the first arm 22 via the first connecting elastic portion 40, and is connected to the second arm via the second connecting elastic portion 42. 26 is connected to the second elastic portion 24.

In this embodiment, the first and second elastic portions 18 and 24 and the first and second connecting elastic portions 4 are provided.
As an example, arc hinges as shown in FIG. 1C are applied to 0 and 42, respectively. As will be described later, the arc-shaped hinge can appropriately select an arc radius R and a minimum width t between the arc radii as shape parameters for setting its rigidity. Since these shape parameters can be set in detail, the displacement enlarging mechanism is used. It can be said that this is an effective shape for the configuration. In the present embodiment, the thickness of the entire displacement enlarging mechanism is considered to be constant, and the thickness direction is not set as the shape parameter of the arcuate hinge. However, this may be set as the shape parameter. . In the drawings, the first and second elastic portions 18 and 24 are integrally connected to the first and second arms 22 and 26 and the support member 20. 2 elastic parts 18, 24
May be formed of a separate material from the first and second arms 22 and 26 and the support member 20. Similarly, the first and second connecting elastic portions 40 and 42 are integrally connected to the connecting arm 38 and the first and second arms 22 and 26. The two connecting elastic portions 40 and 42 may be formed of a separate material from the connecting arm 38 and the first and second arms 22 and 26.

According to such a configuration, as shown in FIG. 2B, when the actuator 30 is expanded and contracted, the pressing force of the actuator 30 is transmitted to the first arm 22 via the pressing portion 32, Tip 22a of first arm 22
Rotates around the first elastic portion 18 by a predetermined tilt angle θ ₁ . At this time, the rotational movement of the first arm 22 is transmitted to the second arm 26 via the connecting member 28 described above, and as a result, the tip (displacement output end) of the second arm 26
26a is a predetermined inclination angle θ about the second elastic portion 24.
₂ (> θ ₁ ).

[0021] As can be seen from FIG. 2 (b), since the inclination angle theta ₁ of the first arm 22 a different value (θ _2> θ ₁₎ and the inclination angle theta ₂ of the second arm 26, the 1st and 2nd elastic parts 18 and 24 and 1st and 2nd elastic parts 4 for connection
The stresses applied to the arcuate hinges applied to 0, 42 also differ. In this case, the first and second elastic portions 18 and 24 and the first and second connecting elastic portions 40 and 42 (that is, the arc hinges 18, 24, 40 and 42) are connected to the respective arc hinges 18 and 24. It is necessary to set the shape so as not to exceed the maximum allowable stress of the materials 24, 40 and 42. In particular,
The arc radii R on both sides of each of the arcuate hinges 18, 24, 40, 42 so that a predetermined displacement (ie, a tilt angle θ ₂ ) is obtained at the tip (displacement output end) 26a of the second arm 26. Further, a minimum width t between the arc radii R is set (see FIG. 1C).

The lever ratio of the first and second arms 22 and 26 is set based on such setting conditions.
Specifically, as shown in FIG.
2 length L ₁ (specifically, from the first elastic portion 18 to the first
(The length of the first arm 22 up to the connecting elastic portion 40).
The length b ₁ from the first elastic portion 18 to the pressing portion 32,
The length L ₂ of the arm 26 (specifically, the second elastic portion 2
4 of the second arm 26 distal lengths up (displacement output terminal) 26a), the second length b ₂ from the elastic portion 24 to the second connecting elastic unit 42, respectively, are set.

In this case, the first and second arms 22, 2
The length L (see FIG. 2A) of the entire displacement enlarging mechanism in the direction of the arrow X also changes based on the leverage ratio of 6, but the first and second elastic portions 18 and 24 and the first and second elastic portions 18 and 24 also change. Connecting elastic portions 40, 42 (that is, arcuate hinges 18, 24, 40,
By setting the shape of each of the arcuate hinges 18, 24, 40, 42 within a range not exceeding the maximum allowable stress of the material of 42), the length L of the entire displacement magnifying mechanism in the arrow X direction is minimized. be able to.

Hereinafter, each of the arcuate hinges 18, 24, 4
The relationship between the shapes 0 and 42 and the length L of the entire displacement enlarging mechanism in the arrow X direction will be described in detail.

Here, the displacement of the actuator 30 in the direction of the arrow Y is represented by y _PZT , and the displacement of the tip 22a of the first arm 22 in the direction of the arrow Y (specifically, the first arm 22 and the first connecting elastic Assuming that y _{1 is} the displacement of the connection portion with the part 40 and y is the displacement of the tip (displacement output end) 26 a of the second arm 26 in the direction of the arrow Y, the following equation is established.

[0026]

(Equation 1)

[0027]

(Equation 2)

At this time, the first and second arms 2
The inclination angles θ ₁ and θ ₂ of ₂ , 26 are represented by the following equations.

[0029]

(Equation 3)

[0030]

(Equation 4)

Generally, arcuate hinges 18, 24, 40,
The rotational moment M of 42 is represented by the following equation.

[0032]

(Equation 5)

In this case, E is the modulus of longitudinal elasticity, and w is the width of the displacement magnifying mechanism (see FIG. 1B).

[0034] Here, both sides of the arc radius of the first elastic portion and is arcuate hinge 18 R _18, a minimum width between these arc radius and t _18, also arcuate hinge is a second elastic portion Assuming that the arc radii on both sides of the arc ₂₄ are R ₂₄ and the minimum width between the arc radii is t ₂₄ , the rotational moments M ₁₈ and M ₂₄ of the arc hinges ₁₈ and ₂₄ are represented by the following equations.

[0035]

(Equation 6)

[0036]

(Equation 7)

As described above, the arcuate hinges 40 and 42, which are the first and second connecting elastic portions, provide a predetermined displacement (ie, a displacement output end) at the tip (displacement output end) 26a of the second arm 26. , The inclination angle θ ₂ ) is appropriately set in a shape that can be obtained, and thus no particular description is given here.

An arcuate hinge 1 as a first elastic portion
Minimum thickness of 8 elastic coefficient (a portion corresponding to a minimum width t ₁₈₎ Z _18, the minimum thickness portion of the arc-shaped hinge 24 which is a second elastic portion (portion corresponding to the minimum width t ₂₄₎ Modulus of elasticity is Z ₂₄
Then, the elastic coefficients Z ₁₈ ,
Z ₂₄ is represented by the following equation.

[0039]

(Equation 8)

[0040]

(Equation 9)

Further, the arcuate hinge 1 as the first elastic portion
8 of the stress concentration factor to alpha _18, when the stress concentration factor of alpha ₂₄ of the second elastic part and is arcuate hinge 24, the stress sigma ₁₈ of each arcuate hinge 18, 24, sigma ₂₄ is the following formula expressed.

[0042]

(Equation 10)

[0043]

[Equation 11]

[0044] In this case, the stress sigma ₁₈ of each arcuate hinge 18, 24, sigma _24, the maximum allowable stress sigma _a less possessed by each arcuate hinges _{18,24 (σ 18 ≦ σ a,} σ 24 ≦ σ a) Needs to be

[0045] Here, considering the arcuate hinge 18, which is a first elastic part, the shape of the arcuate hinge 18 with the maximum allowable stress sigma _a, when the constant b ₁ of (9), the actuator 30 Is determined only by the displacement y _{PZT of}

FIG. 3A is a graph of the equation (9). Assuming a case where the first arm 22 is displaced by the tilt angle θ ₁ , the arcuate hinge as the first elastic part is used. The relationship between the shape parameters R ₁₈ and t ₁₈ and the stress σ ₁₈ is shown. Note that in this graph, the horizontal axis represents the arc radius R _18, the vertical axis represents the stress sigma _18. The solid line in the drawing, the dotted line, dashed line, respectively, change the minimum width t ₁₈ between arc radius shows a case in which is (increasing the minimum width in the direction of the arrow), the minimum width solid, dotted, in the order of a broken line t ₁₈ is larger.

As can be seen from the solid line, dotted line, and broken line graphs, the stress σ ₁₈ decreases as the arc radius R ₁₈ increases, and the minimum width t ₁₈ between the arc radii increases as the arc radius R ₁₈ increases.
The stress σ ₁₈ also increases.

A dashed line extending parallel to the horizontal axis in the figure defines the maximum allowable stress σ _a of the material of the arcuate hinge 18 as the first elastic portion. The shape parameter R ₁₈ of the arcuate hinge 18 used as a part,
t ₁₈ needs to be set to the maximum allowable stress σ _a . In this case, by appropriately selectively combining the shape parameters R ₁₈ and t ₁₈ of the arcuate hinge 18 on the one-dot chain line indicating the maximum allowable stress σ _a , the first allowable stress σ _a is maintained within a range not exceeding the maximum allowable stress σ _a . The rigidity of the arcuate hinge 18 used as the elastic portion can be increased. Thus, the shape of the arcuate hinge 18 is determined.

Next, the length L of the entire displacement enlarging mechanism (FIG. 2)
(See (a)) to determine the length L of the first arm 22.
₁ (see FIG. 2A) and the length L of the second arm 26
₂ (see FIG. 2A) is obtained as follows using the shape parameters R ₂₄ and t ₂₄ of the arcuate hinge 24.

The length L ₁ of the first arm 22 (FIG. 2A)
) By replacing the stress σ ₂₄ of the arcuate hinge 18 as the first elastic portion with the maximum allowable stress σ _a .
It is obtained from equation (10). Specifically, when the expression (10) is modified for L ₁ and σ ₂₄ is replaced with the maximum allowable stress σ _a , the length L ₁ of the first arm 22 is expressed by the following expression.

[0051]

(Equation 12)

The length L ₂ of the second arm 26 (FIG. 2)
(A)) is obtained from the equations (2) and (11).
Specifically, after substituting equation (11) into equation (2), L ₂
Is modified to be represented by the following equation.

[0053]

(Equation 13)

The length L (see FIG. 2A) of the entire displacement enlarging mechanism is

[0055]

[Equation 14]

Therefore, (1) is obtained from the equation (13).
By substituting the expressions 1) and (12), the following expression is obtained.

[0057]

(Equation 15)

FIG. 3B is a graph of the equation (14). Assuming that the second arm 26 is displaced by the inclination angle θ ₂ , the arcuate hinge as the second elastic part is formed. 24
The relationship between the shape parameters R ₂₄ and t ₂₄ and the length L of the entire displacement enlarging mechanism is shown. Note that in this graph, the horizontal axis represents the arc radius R _24, the vertical axis represents the length L of the entire displacement enlargement mechanism. The solid line in the drawing, the dotted line, dashed line, respectively, change the minimum width t ₂₄ between arc radius shows a case in which is (increasing the minimum width in the direction of the arrow), the minimum width solid, dotted, in the order of a broken line t ₂₄ is larger. In this embodiment, R ₂₄ > R ₁₈ and t ₂₄ <t
₁₈ is assumed.

The dashed line in the figure indicates that the arcuate hinge 18 as the first elastic part and the arcuate hinge 24 as the second elastic part have the same shape (R ₂₄ = R ₁₈ ,
The length L of the entire displacement enlarging mechanism at t ₂₄ = t ₁₈ ) is shown (prior art).

As can be seen from this graph, the overall length L of the displacement enlarging mechanism has an extreme value according to the shape parameters R ₂₄ and t ₂₄ of the arc hinge 24. Considering the extreme value by comparing the above-described prior art with the present invention,
The shape parameters R ₁₈ , t ₁₈ and R _{24 of} each of the arcuate hinges ₁₈ , 24 are set such that the shape of the arcuate hinge 18, which is the elastic portion of the second embodiment, and the shape of the arcuate hinge 24, which is the second elastic portion, are relatively different. , And t ₂₄ as appropriate, the length L of the entire displacement enlarging mechanism can be reduced as compared with the prior art.

In this case, there are the following three methods for making the shape parameters of the arcuate hinges 18 and 24 relatively different. A first method is to make the arc radii R ₁₈ and R _{24 the} same and to make the minimum widths t ₁₈ and t ₂₄ different from each other. As a second method, the minimum widths t ₁₈ and t ₂₄
And making the arc radii R ₁₈ and R ₂₄ different from each other. As a third method, the arc radii R ₁₈ and R ₂₄ are different from each other, and the minimum widths t ₁₈ and t ₂₄ are different from each other.

As described above, according to the present embodiment, each of the circular hinges 18 as the first elastic portion and the circular hinge 24 as the second elastic portion are relatively different in shape. The shape parameters R ₁₈ , t ₁₈ and R of the arcuate hinges ₁₈ , 24
₂₄ and t ₂₄ as appropriate,
The length L (see FIG. 2A) of the entire displacement enlarging mechanism can be extremely reduced as compared with the related art. Further, according to the present embodiment, the actuator 30 extends from the base 34 through the opening 36 of the support member 20 toward the first arm 22, and the extended end of the actuator 30 is connected to the pressing portion 32 of the first arm 22. Due to the contact, the dimension H (see FIG. 2A) in the height direction of the entire displacement enlarging mechanism can be made smaller than that of the related art. As a result, according to the present embodiment, it is possible to realize a displacement enlarging mechanism that is small and can obtain a large displacement. In other words, even if a displacement enlargement mechanism having the same external dimensions as that of the present embodiment is configured using the conventional technology, it is not possible to obtain the same displacement as that of the present embodiment.

According to the present embodiment, the stresses σ ₁₈ and σ ₂₄ of the arcuate hinges ₁₈ and ₂₄ as the first and second elastic portions are the maximum allowable stresses of the arcuate hinges ₁₈ and _24. as a sigma _a, by setting the shape parameter R _18, t ₁₈ and R _24, t ₂₄ arcuate hinge 24 is arcuate hinge 18 and the second elastic portion which is a first elastic portion The rigidity of each of the arcuate hinges 18 and 24 can be increased, and as a result, a displacement enlarging mechanism having a high resonance frequency can be realized. In this case, for example, when the tip (displacement output end) 26a of the second arm 26 is connected to the microscope stage, the positioning speed of the microscope stage can be increased.

In the above embodiment, arcuate hinges are applied to the first and second elastic portions 18 and 24 and the first and second connecting elastic portions 40 and 42, respectively. The present invention is not limited to this, and the same operation and effect as those of the above-described embodiment can be realized even if the arc-shaped hinge is made of, for example, a leaf spring or rubber having rigidity equivalent to this.

[0065]

According to the present invention, it is possible to provide a displacement enlarging mechanism having a high resonance frequency and capable of obtaining a large displacement with a small size.

[Brief description of the drawings]

1A is a diagram showing a configuration of a displacement magnifying mechanism according to an embodiment of the present invention, and FIG. 1B is a view bb of FIG.
Sectional drawing which follows a line, (c) is a figure which shows the structure of the arc-shaped hinge applied to this Embodiment.

FIG. 2A is a diagram showing a leverage ratio of a displacement magnifying mechanism according to an embodiment of the present invention, and FIG. 2B is an operation explanatory diagram of the displacement magnifying mechanism according to the embodiment of the present invention.

FIG. 3A is a diagram illustrating a relationship between a shape parameter of an arcuate hinge as a first elastic portion and stress, and FIG. 3B is a diagram illustrating a relationship between a shape parameter of an arcuate hinge as a second elastic portion; The figure which shows the relationship with the length of the whole displacement enlargement mechanism.

FIG. 4A is a diagram showing a conventional displacement enlarging mechanism,
FIG. 2B is a diagram showing a configuration of a conventional displacement enlarging mechanism according to the improvement of FIG.

[Explanation of symbols]

 18 First elastic part 20 Support member 22 First arm 24 Second elastic part 26 Second arm 28 Connecting member 30 Actuator

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 26, 1999 (1999.3.2
6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction contents]

An arcuate hinge 1 as a first elastic portion
8, the section modulus of the minimum thickness portion (the portion corresponding to the minimum width t ₁₈ ) is Z ₁₈ , and the minimum thickness portion (the portion corresponding to the minimum width t ₂₄ ) of the arcuate hinge 24 which is the second elastic portion. Section modulus is Z ₂₄
Then, the section modulus Z ₁₈ of each of the arcuate hinges ₁₈ , 24,
Z ₂₄ is represented by the following equation.

Claims (3)

[Claims] A first arm having a base end supported by a support member via a first elastic portion; and a second arm having a base end supported by the support member via a second elastic portion. A connecting member for connecting the first arm and the second arm; and an actuator capable of applying a predetermined pressing force to the first arm, wherein the first and second elastic portions are A displacement enlarging mechanism, which is configured to have a relatively different shape. 2. The displacement enlarging mechanism according to claim 1, wherein the first and second elastic portions are set in a shape that does not exceed a maximum allowable stress of the material. 3. The connecting member is connected to the first arm through a first connecting elastic portion, and is connected to the second arm through a second connecting elastic portion. Yes,
The displacement enlarging mechanism according to claim 1, wherein the first and second elastic portions and the first and second connecting elastic portions are formed by arcuate hinges.