JP2001022445A - Displacement enlarging mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small displacement enlarging mechanism which can stately be operated at high speed. SOLUTION: An arm 5 whose base end side is supported by a fixing stand 1 through a hinge 3, a spring 6 whose one end is connected to the tip side of the arm and other end to the fixing strand and an actuator 2 which presses a part of the arm 5 against the elastic force of the spring and displaces the tip side of the arm 5 along a displacement direction are installed. The arm 5 is maintained to a state where it is inclined by a prescribed inclination angle θ1 toward this side of the displacement direction by the spring in a state where the actuator is not expanded and contracted.

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 driving a stage of, for example, an electron microscope, an ultra-precision processing machine, a scanning probe microscope, a scanning laser microscope, or the like.

[0002]

2. Description of the Related Art Conventionally, when a stage such as an electron microscope, an ultra-precision processing machine, a scanning probe microscope, or a scanning laser microscope is driven, actuators such as piezoelectric bodies are often used. Since the displacement of the actuator is very small, in recent years, as shown in FIG. 4, a technique of driving the stage by a displacement enlarging mechanism utilizing the principle of leverage has been proposed (Japanese Patent Laid-Open No. 1-21).
No. 9602).

More specifically, as shown in FIG. 4A, the displacement magnifying mechanism includes an arm 5 whose base end is supported by a fixed base 1 via a hinge 3, and the arm 5 is orthogonal. It extends along a horizontal axis H parallel to the X-axis direction of the coordinates XY. An output displacement end 5a of the displacement enlarging mechanism is formed on the distal end side of the arm 5, and the output displacement end 5a is positioned on the horizontal axis H.

In such a displacement enlarging mechanism, when a part of the arm 5 is pressed by a load F by an actuator (not shown) such as a piezoelectric body, as shown in FIG.
The arm 5 is inclined by an angle θ with the hinge 3 as a fulcrum.

In this case, the length of the arm 5 (the length from the hinge 3 to the output displacement end 5a) is L, and the load F is applied to the arm 5 at a point separated from the hinge 3 by a distance b (b <L). If it is made to act, the output displacement Y of the displacement enlarging mechanism (output displacement end 5a) is calculated based on the relational expression of Y = Lθ (1).

When the arm 5 is tilted by the angle θ, a stress σ is generated in the hinge 3. In this case, hinge 3
Is E, the stress concentration coefficient is α, the thickness is t,
Assuming that the arc radius is R, the inclination angle θ of the arm 5 and the stress σ
And the following equation (2) holds.

(Equation 1)

As can be seen from equation (2), the arm 5
Increases (increase in output displacement Y), the stress σ of the hinge 3 also increases.

However, in order to prevent the hinge 3 from being damaged even if the displacement enlarging mechanism is used repeatedly, the stress σ is limited to a certain allowable stress (allowable stress of the material constituting the hinge 3) σa or less. Is required. In this case, σ
= Σa, the inclination angle θ of the arm 5 becomes the maximum θmax, and the output displacement at that time is as follows:
It is calculated from the formula.

(Equation 2)

As can be seen from equation (3), when the target output displacement is large, the length L of the arm 5 is increased or the shape of the hinge 3 is changed (for example, the thickness t is reduced). Or increasing the arc radius R), it is possible to increase the maximum inclination angle θmax.

[0010]

However, if the length L of the arm 5 is increased, the displacement enlarging mechanism becomes large. Further, if the shape of the hinge 3 is changed to increase the maximum inclination angle θmax, the rigidity of the hinge 3 is reduced, so that the resonance frequency of the displacement magnifying mechanism is reduced, and the displacement magnifying mechanism is stabilized. And cannot operate at high speed.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a displacement enlarging mechanism which is small in size and can be operated stably at high speed.

[0012]

In order to achieve the above object, a displacement enlarging mechanism according to the present invention comprises an arm whose base end is supported by a fixed base via a hinge and one end of which is connected to the distal end of the arm. An elastic body connected and having the other end connected to the fixed base, and pressing a part of the arm against the elastic force of the elastic body to displace the distal end side of the arm in a predetermined displacement direction. The arm is maintained in a state of being inclined by a predetermined inclination angle toward the near side in the displacement direction by the elastic body.

[0013]

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

As shown in FIG. 1A, the displacement enlarging mechanism according to the present embodiment has an arm 5 whose base end is supported by a fixed base 1 via a hinge 3 and one end of which is located at the distal end of the arm 5. An elastic body or spring 6 which is connected and has the other end connected to the fixed base 1
And an actuator (for example, a piezoelectric member, an electromagnetic member, or the like) capable of pressing a part of the arm 5 against the elastic force of the spring 6 and displacing the distal end side of the arm 5 in a predetermined displacement direction Y. Type motor) 2. The arm 5 is maintained in a state where the arm 5 is inclined by the predetermined inclination angle θ1 toward the near side in the displacement direction Y by the spring 6 in a state where the actuator 2 is not extended and retracted.

The arm 5 extends along a horizontal axis H parallel to the X-axis direction of the rectangular coordinates XY, and an output displacement end 5a of a displacement enlarging mechanism is formed at the tip end thereof.

The actuator 2 is arranged along the Y-axis direction of the rectangular coordinates XY (that is, the displacement direction Y), and its base end is fixed to the fixed base 1 and its tip is attached to the arm 5. Applied to pin 4. In this case, when the actuator 2 is driven to extend (extend in the Y-axis direction), a pressing force corresponding to the amount of extension acts on the arm 5 via the pin 4, and as a result, the arm 5 is pivoted about the hinge 3. The tip side can be displaced along the predetermined displacement direction Y. After that, when the actuator 2 is driven to contract (to contract in the Y-axis direction), the arm 5 is returned to the original position by the elastic force of the spring 6.

Further, when the pressing force is applied to the arm 5 via the pin 4 as described above, the shape of the pin 4 is set to, for example, the whole so that local stress concentration does not occur on the arm 5. Is preferably spherical or hemispherical only on the arm 5 side. In this case, by forming the pin 4 with a material harder than the arm 5, local deformation of the arm 5 can be reduced.

In this embodiment, the arm 5 moves in the displacement direction Y
The type of the spring 6 (the elastic force and the length of the spring 6, etc.) is selected so as to be maintained at a predetermined inclination angle θ1 toward this side.

For example, as shown in FIG.
When the arm 5 is tilted toward the near side by the tilt angle θ1, the appropriate type (the elastic force and the length of the spring 6, etc.) of the spring 6 is selected, and the contact state between the tip of the actuator 2 and the pin 4 is selected. Is adjusted, the arm 5 is applied by the spring 6 to the front end of the actuator 2 via the pin 4 without rattling, and the arm 5 is positioned on the near side in the displacement direction Y (on the front side with respect to the horizontal axis H). (Hereinafter, this state is referred to as an initial state).

Next, from this initial state, the actuator 2
FIG. 1 shows an operation of driving the output displacement end 5a of the displacement enlarging mechanism by driving the extension
This will be described with reference to FIG.

In this case, the output displacement end 5a of the arm 5 positioned at the initial inclination angle θ1 is further displaced by θ2 (= θ1) beyond the horizontal axis H by extending the actuator 2. Is assumed.

In this case, the length of the arm 5 (the length from the hinge 3 to the output displacement end 5a) is L1, and the pin 4 provided at a position separated from the hinge 3 by a distance b (b <L).
When the pressing force of the actuator 2 is applied to the arm 5 through the following formula, the output displacement Y1 of the displacement magnifying mechanism (output displacement end 5a) is calculated based on the relational expression: Y1 = L1 (θ1 + θ2) (4) You.

As described above, while the arm 5 is inclined by the angle θ1 + θ2, the stress σ generated in the hinge 3 must be equal to or less than the allowable stress σa of the material constituting the hinge 3. In this case, when σ = σa is satisfied, the inclination angle θ of the arm 5 becomes the maximum θmax, and the maximum inclination angle θmax is calculated from the following equation (5) using the above equation (2). Is done.

(Equation 3)

R1 is the radius of the arc of the hinge 3, and t1 is the thickness of the hinge 3.

The output displacement Y1 at this time is calculated from the following equation (6) by substituting equation (4) into equation (3).

(Equation 4)

Here, the output displacement Y1 based on the equation (6)
And the output displacement Y of the conventional displacement enlarging mechanism (see (3) above).
When the output displacements are equal to each other, for example, the following equation (7) is obtained.

(Equation 5)

In this relational expression, when the shapes of the hinges 3 are equal, R1 = R and t1 = t, so that the length of the arm 5 has the relation of the following expression (8).

(Equation 6)

As can be seen from the equation (8), in the displacement enlarging mechanism of the present embodiment, the length L
With the length L1 of 1/2, it is possible to realize the same output displacement as in the prior art. As a result, the displacement enlarging mechanism of the present embodiment can be made smaller than in the prior art.

In the displacement enlarging mechanism of the present embodiment, the rigidity of the hinge 3 does not change because the shape of the hinge 3 is the same as that of the prior art, but the length L1 of the arm 5 is reduced. Since the mass of the arm 5 can be reduced by that much, the resonance frequency can be increased, and as a result, a displacement magnifying mechanism that can operate stably at high speed can be realized.

Further, in the displacement enlarging mechanism of this embodiment,
By maintaining the arm 5 in the initial state in which the arm 5 is inclined by the inclination angle θ1 with respect to the horizontal axis H, and displacing the output displacement end 5a from that state (for example, see FIG. 1),
Compared to the case where the arm 5 is positioned on the horizontal axis H and the output displacement end 5a is displaced from that state (for example, see FIG. 4) as in the prior art (for example, see FIG. 4), the output displacement ｛ (4) Expression｝ can be increased.

Next, a displacement enlarging mechanism according to a second embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 2A, in the displacement enlarging mechanism of the present embodiment, the spring 6 has the other end connected to the fixed base 1 via the connecting member 7 and the connecting member 7.
Is configured to be movable along the Y-axis direction with respect to the fixed base 1. By moving the connecting member 7, the tilt angle θ1 of the arm 5 can be adjusted.

The other configuration is the same as that of the first embodiment described above, and a description thereof will be omitted.

According to such a configuration, it is possible to use any kind of spring 6 irrespective of the kind of the spring 6 (elastic force and length of the spring 6). In a state where the end is connected to the fixed base 1 via the connecting member 7, the connecting member 7 is fixed with respect to the fixed base 1 by a predetermined amount y '
By moving the arm 5 only through the pin 4, the arm 5 is applied to the front end of the actuator 2 via the pin 4 without rattling, and the predetermined inclination angle θ1 is set on the near side in the displacement direction Y (on the front side with respect to the horizontal axis H). (Hereinafter, this state is referred to as an initial state).

Note that, from this initial state, the actuator 2
The operation (see FIG. 2 (b)) of driving the output to extend (in the Y-axis direction) and displacing the output displacement end 5a of the displacement enlarging mechanism is the same as in the first embodiment.
The description is omitted.

The effect of this embodiment is as follows.
In addition to the effect of the embodiment, the moving amount y 'of the connecting member 7 is
Is adjusted, the tilt angle θ1 of the arm 5 can be changed, so that not only the fine adjustment of the stress generated in the hinge 3 can be performed, but also the preload applied to the actuator 2 can be finely adjusted. The displacement amount of the output displacement end 5a of the enlargement mechanism can be changed according to the purpose of use.

The present invention is not limited to the configurations of the first and second embodiments described above, but can be variously modified as follows.

For example, as shown in FIG. 3, by replacing the position where the pressing force of the actuator 2 acts on the arm 5 with the displacement output end 5a, it is possible to constitute a displacement reduction mechanism. Specifically, the relationship between the length L1 from the hinge 3 to the output displacement end 5a and the length b from the hinge 3 to the position where the actuator 2 presses the arm 5 via the pin 4 is L1 <b. Become. For this reason, the output displacement of the displacement output end 5a becomes smaller than the displacement of the actuator 2, and functions as a displacement reducing mechanism. According to such a configuration, not only the same effects as in the first embodiment can be obtained, but also the resolution of the actuator 2 can be increased.

[0039]

According to the present invention, it is possible to provide a displacement enlarging mechanism which is small and can be operated stably at high speed.

[Brief description of the drawings]

FIG. 1A is a diagram schematically showing a configuration of a displacement magnifying mechanism according to a first embodiment of the present invention, and FIG. 1B is a state in which an output displacement end of the displacement magnifying mechanism is displaced; FIG.

FIG. 2A is a view schematically showing a configuration of a displacement magnifying mechanism according to a second embodiment of the present invention, and FIG. 2B is a state in which an output displacement end of the displacement magnifying mechanism is displaced; FIG.

FIG. 3 is a diagram schematically showing a configuration of a displacement reduction mechanism according to a modification of the present invention.

4A is a diagram schematically showing a configuration of a conventional displacement enlarging mechanism, and FIG. 4B is a diagram showing a state in which an output displacement end of the displacement enlarging mechanism is displaced.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed base 2 Actuator 3 Hinge 5 Arm 6 Spring θ1 Tilt angle

Claims (3)

[Claims] 1. An arm having a base end supported by a fixed base via a hinge, an elastic body having one end connected to the distal end of the arm and the other end connected to the fixed base, and an elastic force of the elastic body. Press a part of the arm against
An actuator capable of displacing the distal end side of the arm in a predetermined displacement direction, wherein the arm is inclined by a predetermined inclination angle toward the near side in the displacement direction by an elastic body. Displacement magnification mechanism characterized by being maintained. 2. The hinge according to claim 1, wherein a stress generated in the hinge when the distal end of the arm is displaced by the actuator is equal to or less than an allowable stress of a material forming the hinge. Displacement enlargement mechanism. 3. The elastic body has the other end connected to a fixed base via a connecting member, and the connecting member is configured to be movable with respect to the fixed base, and moves the connecting member. The displacement magnifying mechanism according to claim 1, wherein the tilt angle of the arm is adjusted by the adjustment.