JP2000075927A - Table mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To actualize a table mechanism whose movable table is displaced linearly. SOLUTION: The movable table 1 is supported by four mouth-shaped springs 2a and 2b, and 3a and 3b having slits. The mouth-shaped springs 2a and 2b are connected directly to a fixed base 11 and the mouth-shaped springs 3a and 3b are connected to the fixed base 11 through lever expansion arms 4a and 4b. The lever expansion arms 4a and 4b have arcuate cuts 8a and 8b nearby the connection part for the fixed base 11. Piezoelectric actuators 10a and 10b have one-end sides fixed to the fixed base 11 and the other-end sides brought into contact with pins 9a and 9b embedded in the expansion arms 4a and 4b. From the expansion arms 4a and 4b, arms 5a and 5b are extended to the opposite sides of the pins 9a and 9b and have arcuate cuts 7a and 7b nearby their centers, and their tip parts are pressed by feed screws 6a and 6b provided to the fixed base 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a table mechanism used for a scanning probe microscope, a scanning laser microscope, and the like.

[0002]

2. Description of the Related Art A stage using an elastic spring guide is often used in a situation where high-precision operation is required, such as an electron microscope and an ultra-precision processing machine. Since the elastic spring guide does not have a sliding portion, high-precision operation is possible without being affected by backlash, friction and wear. XY using spring guide
In general, the Z stage generally has three uniaxial drive stages stacked. However, such a configuration results in an increase in the size of the stage.

[0003] Japanese Patent Application Laid-Open No. 9-89912 and Japanese Patent Application No. 8-133513 have disclosed a stage aiming at miniaturization and high-speed operation.
There is a number. In these stages, only the movable table is X
A piezoelectric actuator is supported by a spring so as to be movable in the YZ directions, and one piezoelectric actuator is fixed to the fixed base one by one in each axial direction.

As an example, FIG. 7 shows a configuration of a stage or a table mechanism disclosed in Japanese Patent Application Laid-Open No. 9-89912. The main table 112 includes three sets of bar springs 114 from three adjacent surfaces.
x, 114y and 114z extend vertically and are fixed to three mutually orthogonal walls of the sub-table 116. The fixed base 122 is provided with three sets of bar springs 120x, 120x from three surfaces facing each wall surface of the sub-table 116.
y, 120z extend and are secured to each wall of the sub-table 116.

The fixed base 122 is fixed to the fixed frame 124 by one surface 122a, and the sub-table 116 is fixed to the fixed frame 1
24 is supported in a floating state. Fixed frame 12
4 has holes 118 provided in each wall of the sub-table 116.
Piezoelectric actuators 126x, 126y, 126z extending in x, y, z directions through x, 118y, 118z
Are fixed, and their free ends are
Is in contact with

[0006]

In this table mechanism, the piezoelectric actuator 12 fixed to the fixed frame 124 is used.
6x, 126y and 126z directly press the main table 112 in each axial direction. Therefore, for example, when the main table 112 is driven along one axis, friction occurs between the other two-axis piezoelectric actuators and the main table. Along with this, the main table 112 receives not only a linear displacement along one axis direction but also a rotational displacement due to receiving a rotational moment due to frictional resistance. It is desirable that such a rotational displacement be as small as possible for applications requiring high-precision positioning.

[0007] The present invention has been made to solve such a problem, and an object of the present invention is to provide a table mechanism in which a movable table is displaced linearly without rotational displacement.

[0008]

A table mechanism according to the present invention comprises a fixed base, a movable table movable with respect to the fixed base, and a first table for supporting the movable table symmetrically with respect to a first axis. A pair of spring members, a second pair of spring members that support the movable table symmetrically with respect to a second axis orthogonal to the first axis, and are arranged symmetrically with respect to the first axis, A first pair of enlarged arms each having one end connected to the first spring member and the other end rotatably connected to the fixed base, and one end disposed symmetrically with respect to the first axis; Presses the first magnifying arm, and presses the first magnifying arm in a direction opposite to a pressing direction of the first pair of piezoelectric actuators, the other end of which is fixed to a fixed base, and the first piezoelectric actuator. A first pair of preload springs, and a load applied to the first preload spring. In addition, adjusting the amount of deflection, characterized in that it comprises a first pair of load adjustment mechanism.

[0009]

[First Embodiment] FIG. 1 shows a table mechanism according to a first embodiment. This embodiment is a table mechanism driven one-dimensionally in the y-axis direction.

The movable table 1 is supported by four mouth-shaped springs 2a, 2b, 3a, 3b having slits. The mouth-shaped springs 2a and 2b are directly connected to the fixed base 11, and the mouth-shaped springs 3a and 3b are connected to the fixed base 11 via the lever expanding arms 4a and 4b. The lever enlargement arms 4a and 4b have arc notches 8a and 8b near the connection with the fixed base 11, and can be rotationally displaced using these notches 8a and 8b as fulcrums.

One end of each of the piezoelectric actuators 10a and 10b is fixed to a fixed base 11, and the other end is connected to pins 9a and 9b embedded near the arc-shaped notches 8a and 8b of the lever expanding arms 4a and 4b. In contact. further,
The lever enlarging arms 4a and 4b are provided with circular arc notches 8a and 8b.
Has arms 5a, 5b extending at right angles from the opposite side of the pins 9a, 9b. Arm 5a,
5b has arc notches 7a and 7b near the center thereof, and feed screws 6a and 6b for pressing forward portions of the arc notches 7a and 7b are provided on the fixed base 11.

All of the above-described components are symmetrically arranged with respect to the drive shaft (y-axis). The movable table 1, the mouth-shaped springs 2a, 2b, 3a, 3b, the lever expanding arms 4a, 4b, the arms 5a, 5b, and the fixed base 11 are integrally manufactured by appropriately cutting a single metal block. .

The movable table 1 includes a piezoelectric actuator 1
It is driven by applying a voltage to 0a and 10b.
The piezoelectric actuators 10a and 10b extend in response to the application of a voltage, and extend through the pins 9a and 9b.
Press a and 4b in the y direction. Thus, the lever expanding arms 4a and 4b are rotationally displaced with the arc notches 8a and 8b as fulcrums.

The pins 9a and 9b are connected to the piezoelectric actuator 1
A material harder than the material forming the lever expanding arms 4a and 4b is used in order to avoid local deformation and absorption of the displacement at the portions where the levers 0a and 10b press the lever expanding arms 4a and 4b. ing. Piezoelectric actuator 1
The positions where 0a and 10b press the lever expanding arms 4a and 4b are near the arc notches 8a and 8b serving as fulcrum of rotation, and the movable table 1 is separated from the arc notches 8a and 8b serving as the rotation fulcrum. Therefore, the displacement of the piezoelectric actuators 10a and 10b is enlarged and transmitted to the movable table 1 by the principle of leverage enlargement.

FIG. 2 shows a mouth-shaped spring connecting the movable table 1 and the lever expanding arms 4a and 4b. In the drawing, the mouth-shaped springs represent the mouth-shaped springs 3a and 3b, and are indicated by reference numeral 3. The mouth-shaped spring 3 has a shape in which a rectangular thin plate extending in the y direction is slit in the longitudinal direction. Therefore, the spring 3 has high rigidity with respect to the force Fy in the y direction, but the force F in the x direction orthogonal to the force Fy.
It has low rigidity for x. Therefore, the rotational displacement of the lever expanding arms 4a and 4b is transmitted to the movable table 1 without being attenuated by the springs 3a and 3b.

Contrary to the mouth-shaped springs 3a and 3b, the mouth-shaped springs 2a and 2b have low rigidity with respect to the force Fy in the y direction and high rigidity with respect to the force Fx in the x direction. Therefore, the movable table 1 does not show a large resistance to the movement in the y direction due to the rotational displacement of the lever expanding arms 4a and 4b, but shows a large resistance to the displacement in the x direction. Suppress movement in the x direction. as a result,
The movable table 1 moves straight in the y direction in response to the rotational displacement of the lever enlargement arms 4a and 4b. in this way,
Since the movable table 1 uses a spring having no sliding portion as a guide, yaw due to friction or the like does not occur.

However, the piezoelectric actuators 10a, 10a
As for b, the displacement varies due to individual differences even when the same voltage is applied. For example, when the piezoelectric actuators 10a and 10b are displaced in order to drive the movable table 1, if the displacement of the piezoelectric actuator 10a is greater than the displacement of the piezoelectric actuator 10b, the left displacement of the movable table 1 becomes large, and thus the Rotationally displaced. Also, the left and right mouth-shaped springs 3a, 3 due to processing errors and the like.
The movable table 1 also depends on the difference in the b-direction flexural rigidity.
Causes rotational displacement. Such a rotational displacement is an unnecessary operation for the purpose of moving the movable table 1 straight.

FIG. 3A shows a state in which a load F in the direction of compressing the piezoelectric actuator which is displaced by the application of a voltage is applied, and FIG. 6 is a graph showing a relationship between a load F and a displacement x in the piezoelectric actuator of FIG. This graph shows that the displacement of the piezoelectric actuator can be adjusted by applying an appropriate load F to the piezoelectric actuator.

In FIG. 1, the arc notches 7a and 7b formed in the arms 5a and 5b work as springs. When the feed screws 6a, 6b are screwed in, the arms 5a, 5b
Is pressed, and the arc notches 7a and 7b are bent and deformed. At this time, the load F that deflects the arc notches 7a and 7b is simultaneously applied to the piezoelectric actuators 10a and 10b.
b also works in the direction of compressing this. Feed screw 6a, 6b
By appropriately adjusting the feed amount of the circular notch 7a,
7b functions as a variable preload spring based on the load pressing the arms 5a and 5b, and the piezoelectric actuators 10a and
The load F applied to 10b can be adjusted. In other words, the arms 5a and 5b and the feed screws 6a and 6b
A load adjusting mechanism that adjusts the load F that deflects the arc cutouts 7a and 7b is configured. By adjusting the load adjusting mechanism, the displacement of the piezoelectric actuators 10a and 10b can be appropriately adjusted. Piezoelectric actuator 10
The displacement of the movable table 1 and the movable spring 1
Monitoring may be performed at the connection points a and 3b. Here, the displacement of the piezoelectric actuator is enlarged and the mouth-shaped spring 3
This is because the variation in the lateral displacement including the variation in the deflection stiffness in the y direction of a and 3b can be confirmed.

Thus, the piezoelectric actuator 10
The movable table 1 can be fed with high accuracy by repeatedly applying and interrupting the voltage to and a and 10b and adjusting the feed screws 6a and 6b so that the lateral displacement becomes equal.

Here, the arc notch springs (arc notches 7a, 7b) used for load adjustment are connected to the arms 5a, 5b.
In addition, the movable table 1, the mouth-shaped springs 2a, 2b, 3
a, 3b, the enlarged arms 4a, 4b and the fixed base 11 are integrally formed. This is to reduce the number of parts, to be compact and easy to assemble. Also, since there is no friction sliding portion, the reproducibility of the movement is good.

The spring for adjusting the load is not limited to an arc-shaped notch, but may be any spring having a spring property, such as a leaf spring or a coil spring. The feed screws 6a and 6b in the load adjusting mechanism may be other members as long as an adjustable load can be applied to the arms 5a and 5b. For example, the same effect can be obtained by using a piezoelectric member having one end fixed to the fixed base 11 and the other end in contact with the arms 5a and 5b. Further, in order to eliminate manual adjustment, a pico motor (manufactured by New Focus Co., USA) may be used for the feed screws 6a and 6b.

The basic configuration of the pico motor will be described. The picomotor has two rod-shaped holding members arranged in parallel with each other, and a piezoelectric body connecting these holding members. A feed screw (6) is provided between the two holding members.
a, 6b).

In this state, when the piezoelectric body is stationary, the feed screw is held stationary by the two holding members. By driving the piezoelectric body, the two holding members expand and contract in opposite directions along the longitudinal direction thereof, and rotate the feed screw. As a result, the lead screw moves in its longitudinal direction.

FIG. 4 shows a modification of the table mechanism according to the first embodiment based on this point. In the figure, FIG.
The members indicated by the same reference numerals as those shown in FIG.

As shown in FIG.
a, 4b are arc notches 7a, 7 (shown in FIG. 1)
b does not have arms 5a, 5b with
One ends of the coil springs 17a and 17b are connected to the same side as the a and 9b. The other ends of the coil springs 17a and 17b are
It is connected to feed screws 16a and 16b provided on the fixed base 11.

The coil springs 17a, 17b are connected to the lever expanding arms 4a, 4b near the mouth-shaped springs 3a, 3b, and connect the lever expanding arms 4a, 4b to the feed screws 16a, 4b.
It is pulling towards 16b. For this reason, the piezoelectric actuators 10a and 10b receive a load in the contracting direction.
The load applied to the piezoelectric actuators 10a, 10b is controlled by operating the feed screws 16a, 16b and the coil springs 17a, 1b.
It can be changed by adjusting the elongation of 7b.

Therefore, the movable table 1 is displaced linearly in the y direction by adjusting the displacement of the left and right piezoelectric actuators 10a and 10b equally using the feed screws 16a and 16b.

In the table mechanism of this modification using a coil spring, since the coil springs 17a and 17b have a linear relationship between the extension and the restoring force, the device is designed and the displacement is adjusted. It has the advantage of being easy.

[Second Embodiment] FIG. 5 shows a table mechanism according to a second embodiment. This embodiment is a table mechanism that drives two-dimensionally in the x-axis direction and the y-axis direction.
In the drawing, members indicated by the same reference numerals as those shown in FIG. 1 indicate equivalent members.

As can be seen from the drawing, the table mechanism of the present embodiment has a configuration in which the same configuration as the drive mechanism in the y-axis direction shown in FIG. 1 is added in the x-axis direction.
Therefore, the mouth-shaped springs 3a, 3b and the lever expanding arms 4a,
4b, arms 5a and 5b, feed screws 6a and 6b, and piezoelectric actuators 10a and 10b are exactly the same as in the first embodiment.

As shown in FIG. 5, the mouth-shaped springs 2a,
2b is the fixed base 1 via the lever expanding arms 4c and 4d.
1 connected. The lever enlarging arms 4c and 4d have arc notches 8c and 8d near the connection with the fixed base 11, and can be rotationally displaced with these notches as fulcrums.

One end of each of the piezoelectric actuators 10c and 10d is fixed to the fixed base 11, and the other end is connected to pins 9c and 9d embedded near the arc-shaped notches 8c and 8d of the lever expanding arms 4c and 4d. In contact.

Further, the lever enlarging arms 4c and 4d have the pins 9c and 9d near the arc notches 8c and 8d.
Have arms 5c and 5d extending at right angles from the opposite side. The arms 5c and 5d have arc notches 7c and 7d near the center thereof, and have the arc notches 7c and 7d.
The feed screws 6c and 6d for pressing the tip of the
It is provided in.

All of the components described above are arranged symmetrically with respect to the drive shaft (x-axis). The arc notch springs (arc notches 7a, 7b, 7c, 7d) are provided together with the arms 5a, 5b, 5c, 5d together with the movable table 1, the mouth-shaped springs 2a, 2b, 3a, 3b, and the enlarged arm 4.
a, 4b, 4c, 4d and the fixed base 11 are integrally processed.

The movable table 1 includes a piezoelectric actuator 1
The piezoelectric actuators 10c and 10d are driven in the y direction by applying a voltage to 0a and 10b, and are driven in the x direction by applying a voltage to the piezoelectric actuators 10c and 10d. Piezoelectric actuator 10
a and 10b extend in response to the voltage application and push the lever enlargement arms 4a and 4b in the y direction. Thus, the lever expanding arms 4a and 4b are rotationally displaced with the arc notches 8a and 8b as fulcrums.

The piezoelectric actuators 10c and 10d
Is extended in response to the voltage application, and the lever enlarging arms 4c,
Press 4d in x direction. Thereby, the lever enlargement arm 4
c and 4d are rotationally displaced with the arc notches 8c and 8d as fulcrums.

The piezoelectric actuators 10a, 10b, 10
Pins 9a, 9b, 9c, 9d in contact with c, 10d
Are located near the arc notches 8a, 8b, 8c, 8d, and therefore, the piezoelectric actuators 10a, 10b, 10
The displacements of c and 10d are enlarged and transmitted to the movable table 1 by the leverage principle.

The mouth-shaped springs 3a and 3b have high rigidity in the y direction, but low rigidity in the x direction orthogonal thereto. Conversely, mouth-shaped spring 2
a and 2b have low rigidity in the y direction, but have high rigidity in the x direction.

For this reason, the mouth-shaped springs 3a and 3b efficiently transmit the rotational displacement of the lever-expanding arms 4a and 4b to the movable table 1 with respect to the rotational displacement of the lever-expanding arms 4a and 4b, and the mouth-shaped springs 2a and 2b. Is the variable table 1 accompanying this
Does not hinder the movement in the y direction. Similarly, lever extension arm 4
The mouth-shaped springs 2a and 2b efficiently transmit the rotational displacement of the lever expanding arms 4c and 4d to the movable table 1 with respect to the rotational displacement of the movable tables c and 4d. Does not hinder movement in the direction. Therefore, the variable table 1 is efficiently moved in the x direction and the y direction.

Further, by adjusting the feed amount of the feed screws 6a and 6b to adjust the load applied to the piezoelectric actuators 10a and 10b, variations due to individual differences between the paired piezoelectric actuators 10a and 10b are compensated. You can do it. In addition, by adjusting the feed amount of the feed screws 6c and 6d to adjust the load applied to the piezoelectric actuators 10c and 10d, it is possible to compensate for variations due to individual differences between the paired piezoelectric actuators 10c and 10d. I can do it. Thereby, the variable table 1 is moved with high linearity in the x direction and the y direction.

That is, the arc notches 7a, 7b, 7c,
7d functions as a variable preload spring based on the load pressing the arms 5a, 5b, 5c, 5d, and is described with reference to FIGS. 3A and 3B in the first embodiment. Similarly, the piezoelectric actuators 10a, 10b, 10
A load adjusting mechanism for adjusting the load F applied to c and 10d is configured, and by adjusting the load adjusting mechanism, the displacement of the piezoelectric actuators 10a, 10b, 10c, and 10d can be appropriately adjusted.

FIG. 6 shows the detailed structure of the feed screw. The feed screw 6 and the arm 5 in the figure are the feed screw 6 respectively.
a to 6d and the arms 5a to 5d. The feed screw 6 is schematically illustrated in FIGS. 1 and 4, but actually has a pressing shaft 13 and a screw 12 as shown in FIG. 6. The pressing shaft 13 is inserted into the fixed base 11 so as to be slidable in the direction of the arrow. The tip of the pressing shaft 13 is fixed to the arm 5 by bonding or the like.

As the screw 12 is screwed into the fixing base 11, the pressing shaft 13 is sent in the direction of pressing the arm 5. Since the tip of the pressing shaft 13 and the arm 5 are fixed, there is no slight slip between the pressing shaft 13 and the arm 5, and no adjustment displacement due to the loosening of the feed screw 6 occurs.

As described in the first embodiment, it is possible to replace the feed screw 6 (the screw 12 and the pressing shaft 13) with a piezoelectric member or a pico motor, and to save time for manually screwing the screw 12. This makes it possible to automate load adjustment using a load adjustment mechanism. The present invention
The present invention is not limited to the above-described embodiment, but includes all implementations that do not depart from the gist of the invention.

[0046]

According to the present invention, there is provided a table mechanism having a movable table which can be linearly displaced without accompanying rotational displacement. Thus, the position of the movable table can be controlled with high accuracy.

[Brief description of the drawings]

FIG. 1 shows a table mechanism according to a first embodiment of the present invention.

FIG. 2 shows the mouth-shaped spring shown in FIG.

FIG. 3A shows a state in which a load F in a direction of compressing the piezoelectric actuator which is displaced by applying a voltage is applied, and FIG. 3B shows a state in which the piezoelectric actuator is under such a condition. 6 is a graph showing a relationship between a load F and a displacement x at the time of FIG.

FIG. 4 shows a modification of the table mechanism of the first embodiment using a coil spring in place of the springy arm of FIG.

FIG. 5 shows a table mechanism according to the first embodiment of the present invention.

FIG. 6 shows a detailed structure of a lead screw schematically shown in FIGS. 1 and 4;

FIG. 7 shows a table mechanism disclosed in JP-A-9-89912.

[Explanation of symbols]

 Reference Signs List 1 movable table 2a, 2b, 3a, 3b mouth-shaped spring 4a, 4b lever expanding arm 5a, 5b arm 6a, 6b feed screw 7a, 7b, 8a, 8b circular notch 9a, 9b pin 10a, 10b piezoelectric actuator 11 fixed base

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01J 37/20 H01J 37/20 D

Claims (3)

[Claims] A fixed table, a movable table movable with respect to the fixed table, a first pair of spring members for supporting the movable table symmetrically with respect to a first axis; A second pair of spring members symmetrically supported with respect to a second axis orthogonal to the one axis; symmetrically disposed with respect to the first axis; one end connected to the first spring member; A first pair of enlarged arms, the other ends of which are rotatably connected to the fixed base, arranged symmetrically with respect to the first axis, one end pressing the first enlarged arm, A first pair of piezoelectric actuators, the other ends of which are fixed to a fixed base; a first pair of preload springs that press the first enlarged arm in a direction opposite to a pressing direction of the first piezoelectric actuator; Apply a load to the first preload spring and adjust the amount of deflection. A table mechanism comprising a pair of load adjusting mechanisms. 2. A second pair of enlarged members symmetrically arranged with respect to the second axis, one end of which is connected to the second spring member, and the other end of which is rotatably connected to the fixed base. An arm, symmetrically disposed with respect to the second axis, a second pair of piezoelectric actuators having one end pressing the second enlarged arm and the other end fixed to a fixed base, A second pair of preload springs that press the second enlarged arm in a direction opposite to the pressing direction of the piezoelectric actuator, and apply a load to the second preload spring to adjust the amount of deflection thereof; The table mechanism according to claim 1, further comprising a load adjusting mechanism. 3. The first and second spring members are mouth-shaped springs having slits, the movable table, the first and second spring members, the first expanding arm, and the first preload. The table mechanism according to claim 1, wherein the spring and the fixed base are integrally formed.