JPH09269388A - Piezoelectric unit and moving table using the unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a piezoelectric element from being broken by constituting a gate-shaped spring of a piezoelectric unit with a mounting base part and a stay part, and making a rigidity in an X-axis direction larger than that in a Y-axis, a Z-axis direction. SOLUTION: A fine adjustment 20 is a piezoelectric unit and provided with a gate-shaped spring 21, a piezoelectric element 35 between stay parts 23 and 23 of the spring and a press plate 26 screwed to front ends 23a, 23a of the stay parts. The spring 21 consists of a mounting base part 30 screwed to a ball screw nut 13 and stay parts 23, 23 set in parallel to each other at both end parts of the mounting base part 30. The stay parts 23, 23 are formed symmetrically right and left, having notch parts 16, 17 via a distance in an X-axis direction at upper and lower faces. The spring 21 is adjusted so that it has a relatively large rigidity in the X-axis direction and a relatively small rigidity in a Y-axis and a Z-axis directions. In this structure, an external force in the Y-axis, Z-axis directions can be absorbed, and the piezoelectric element 25 is prevented from being broken.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric unit and a moving table using the piezoelectric unit, and more specifically, it is used for an ultra-precision processing machine or semiconductor manufacturing which requires precise moving accuracy in submicron units. It is used as a moving mechanism that allows fine movements and is used as a moving table.

[0002]

2. Description of the Related Art A conventional moving table is disclosed in Japanese Patent Application Laid-Open No. 4-30
As shown in Japanese Patent Publication No. 931, a slide table connected to a push plate, a screw shaft for a ball screw screwed to a nut for a ball screw, a drive motor for driving the screw shaft, the push plate and a ball. A piezoelectric element mounted between the screw nut and a guide shaft that is disposed in parallel with the ball screw and is inserted into a linear ball bush fixed to the table is provided. Then, after the ball screw is rotated by the drive motor to perform the coarse movement, the push plate is finely moved by the drive of the piezoelectric element to finely move the slide table for positioning.

[0003]

The conventional moving table has the following problems. (1) The slide table moves roughly while being guided by the guide shaft as the ball screw nut moves, and further moves slightly due to expansion and contraction of the piezoelectric element. At this time, in order to obtain high accuracy, the ball screw nut, the guide shaft, and the piezoelectric element are installed so that their moving directions are parallel to each other, and there is no error in assembling the slide table with the ball screw nut. The ball screw and the nut for the ball screw are assembled with a very small gap, and the push plate and the piezoelectric element are assembled together in the moving direction of the table without any gap. However, in this way, the slide table, the piezoelectric element, and the nut for the ball screw are placed in the vertical direction (Y-axis direction).
Also, it is practically difficult to assemble in the moving direction (X-axis direction) without assembling error, and it is impossible to assemble as designed. Therefore, the slide table cannot be moved smoothly, and high-speed movement is difficult.

(2) If the guide shaft of the slide table and the ball nut are assembled with a certain degree of parallelism and no assembly error, the ball screw rotates and the vertical force is generated by the spiral movement of the ball nut. May directly contact the piezoelectric element and destroy the piezoelectric element. Therefore, the table may not be moved smoothly.

(3) The piezoelectric element is preloaded by using a coil spring. However, since this coil spring has a small spring constant, displacement in the expansion and contraction direction of the piezoelectric element is absorbed by this spring, and so-called high rigidity cannot be obtained. Therefore, it is possible to increase the coil constant by increasing the coil spring to obtain high rigidity. However, this makes it unsuitable for use in piezoelectric elements that require a large space and is housed in a small space.
An appropriate spring force can be obtained in the expansion / contraction direction of the piezoelectric element, that is, the X-axis direction, but this is not appropriate because elastic deformation in the directions orthogonal to the X-axis, that is, the Y-axis direction and the Z-axis direction is too large.

In view of the above circumstances, the present invention provides a spring having appropriate spring force in the X-axis direction, which is the expansion / contraction direction of the piezoelectric element, and in the Y-axis and Z-axis directions orthogonal to the X-axis direction, and at the same time, the piezoelectric element is provided. The purpose is to prevent the destruction of the device. Another object is to simplify the assembly of a moving table with fine and coarse movement mechanisms.

[0007]

SUMMARY OF THE INVENTION The present invention is a piezoelectric unit having a spring for applying a preload to a piezoelectric element, the spring including a mounting base and a support, and having a rigidity in the X-axis direction. A piezoelectric unit, which is a gate spring that is larger than those in the Y-axis and Z-axis directions.

The present invention is a piezoelectric unit having a piezoelectric element and a spring for applying a preload to the piezoelectric element;
The spring is a gate spring having a mounting base portion and a support portion and having a rigidity in the X-axis direction higher than that in the Y-axis and Z-axis directions, and a piezoelectric element is arranged between the support portions of the gate spring. The piezoelectric unit is characterized in that a pressing plate for pressing the piezoelectric element is pressure-bonded to the tip of the pillar portion of the gate spring.

The present invention is a moving table in which a stage is connected to a coarse movement device via a fine movement device provided with a spring for applying a preload to a piezoelectric element; the spring having a mounting base portion and a column portion. And a rigidity higher in the X-axis direction than that in the Y-axis and Z-axis directions, and a piezoelectric element is disposed between the pillar portions of the gate spring, and the pillar portion of the gate spring. A pressing plate for pressing the piezoelectric element is crimped to the tip, and the coarse movement device includes a ball screw nut fixed to a gate spring and a ball screw screwed to the nut. A moving table using a characteristic piezoelectric unit.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A ball screw nut screwed to a ball screw is connected to a stage via a fine movement device.

This fine movement device is a piezoelectric unit, and comprises a gate spring, a piezoelectric element inserted inside the spring, and a receiving portion for the piezoelectric element, which is fixed to the free end of the gate spring. And a push plate.

The gate spring is, in short, a small space,
That is, it can be mounted in a small space corresponding to the size of the piezoelectric element, and the rigidity in the X-axis direction, that is, the expansion / contraction direction of the piezoelectric element is in the Y-axis and Z-axis directions, that is, in the direction orthogonal to the expansion / contraction direction. Anything larger than that of.

Examples of this spring include the following. (1) A gate-shaped spring in which S-shaped spring portions are formed by forming rectangular notches in the upper and lower surfaces at intervals in the X-axis direction on the support columns. (2) A gate-type spring in which slit slits are formed by providing inclined slits in opposite directions in the upper surface and lower surface directions at intervals in the X-axis direction.

(3) A plurality of cubic vertical through-holes are provided in the upper surface and lower surface directions at intervals in the X-axis direction on the column portion, and cubic horizontal through-holes orthogonal to each vertical through-hole are provided in the inner and outer surface directions. , A gate-shaped spring having a cubic space-shaped spring portion. (4) A plurality of cylindrical vertical through holes are provided in the upper surface and the lower surface direction at intervals in the X-axis direction on the column portion, and cylindrical horizontal through holes orthogonal to each vertical through hole are provided in the inner surface and outer surface directions to form a cylindrical space. Gate-shaped spring with a spring-shaped part.

The push plate is provided with a conical receiving portion. The hemispherical projection of the piezoelectric element is inserted into this receiving portion, and the coupling screw provided on the pushing plate is screwed onto the free end of the gate screw. To wear
An appropriate preload is applied to the piezoelectric element by adjusting the tightening force.

The push plate is fixed to the arm of the stage. Guides are provided on both sides of the stage, and the guides guide the stage along a guide shaft arranged parallel to the ball screw.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 3 and 4, the moving table 1 includes a fine movement device 20 and a coarse movement device 10 which are connected to the stage 5. The coarse moving device 10 includes a ball screw 12 connected to a motor 11 and a ball screw nut 13 screwed to the ball screw.

The fine movement device 20 is a piezoelectric unit, and includes a gate spring 21, a piezoelectric element 25 disposed between the support columns 23 and 23 of the spring 21, and a tip 23 of the support columns 23 and 23.
and a push plate 26 screwed to 23a.

The gate spring 21 is made of, for example, a spring material such as stainless steel, phosphor bronze, or brass, and has a mounting base 30 screwed to the ball screw nut 13, and both ends of the mounting base 30. Pillars 23, 23 provided in parallel with
And consisting of Although the mounting base portion 30 and the column portion 23 are integrally molded, it is not always necessary to do so, and both portions 23 and 30 may be formed separately and connected by a connecting means such as a bolt to be integrated. May be.

The mounting base 30 of the gate spring 21 has a coupling tap 27, a hole 29 for inserting the lead wire 28,
And a center groove 32 into which the center pin 31 is inserted.

The pillars 23, 23 of the gate spring 21 are formed symmetrically, and two notches 16, 17 are provided on the lower surface of the upper surface of the pillar 23 at a distance L1 in the X-axis direction. There is. The notches 16 and 17 are U-shaped grooves that open in mutually opposite directions, the notches 16 face the lower surface 23d side, and the notches 17 face the upper surface 23e side. A spring bent into a letter is formed.

The number and shape of the notches 16 can be appropriately selected according to need, but in the case of a plurality of notches, an even number is formed and the shapes thereof are the same. Also, the distance L1 is appropriately selected as required.

The gate spring 21 has a relatively high rigidity in the X-axis direction, and its spring force is adjusted so that it has a relatively weak rigidity in the Y-axis and Z-axis directions orthogonal to the X-axis direction. .

A center pin 31 fitted in a positioning hole 32 is formed at the rear end of the piezoelectric element 25, and the hemispherical projection 2 is press-fitted into a receiving portion 34 of the push plate 26 at the tip thereof.
4 are provided. The piezoelectric element 25 may be sealed in a hermetically sealed case.

The push plate 26 is screwed to the tip 23a of the column portion 23 by a coupling screw 36, but an appropriate preload can be applied to the piezoelectric element 25 by adjusting the tightening force of the screw 36.

The push plate 26 is connected to the stage 5 via an arm 39. Guide portions 41 are provided on both sides of the stage 5, and the guide portions 41 are used for the ball screw 1
It is mounted on a guide shaft 42 which is parallel to 2.

Next, the operation of this embodiment will be described. When the motor 11 is driven, the ball screw 12 rotates, the ball screw nut 13 moves in the direction of arrow A13, and the stage 5 roughly moves in the same direction.

At this time, since the column portion 23 of the gate spring 21 has a relatively large spring constant in the X-axis direction and a relatively small spring constant in the Y-axis and Z-axis directions, the stage 5 and the ball screw nut 13 are provided. Piezoelectric element 2 assembled between
5, the push plate 26 and the gate spring 21 have a product error, an axial deviation, etc., and even if a force in the Y-axis direction or the Z-axis direction is generated, the spring of the column portion 23 in the Y-axis and Z-axis directions is relatively small. The force can be absorbed by a constant spring force. Further, since the column portion 23 has a relatively large spring force having a spring constant in the X-axis direction, it is possible to withstand the load reaction force of the stage 5.

When the stage 5 reaches the vicinity of the target position,
The driving of the motor 11 is stopped, the rotation of the ball screw is stopped, and the coarse movement is stopped.

Next, the piezoelectric element 25 is connected through the lead wire 28.
When a voltage is applied to the piezoelectric element 25 to extend it, the piezoelectric element 25 presses the push plate 26 in the direction of arrow A13. Then, the pushing plate 26 overcomes the elastic force of the spring 21 and the frictional force between the guide shaft 42 and the guide portion 41 to finely move the stage 5 in submicron units.

At this time, the column portion 23 of the gate spring 21 that has preloaded the piezoelectric element 25 is pulled by the piezoelectric element 25 and extends in the X-axis direction, and the piezoelectric element 25 is also subjected to the Y-axis direction and the Z-axis direction. Is applied, the force is absorbed and displacement of the piezoelectric element 25 in the Y-axis direction and the Z-axis direction is prevented.

The force of the piezoelectric element 25 is transmitted to the push plate 26 via the hemispherical projection 24 and the conical receiving portion 34. Therefore, since the piezoelectric element 25 can be easily rotated,
It can rotate in response to an irregular force and release that force.

A second embodiment of the present invention will be described with reference to FIGS. The difference between this embodiment and the first embodiment is that the spring portion SP of the pillar-shaped spring support portion 23 is a slit space spring portion, the details of which are as follows. Four slit portions 52, 53, 54, 55 are provided at the center of the inner surface 23n and the outer surface 23m of the two bilaterally-supported pillar portions 23, 23 at intervals L2 in the X-axis direction.

Slits 52 and 54 and slits 53 and 55
Are U-shaped grooves that open in mutually opposite directions, the slits 52 and 54 face the outer surface 23n, and the slits 53 and 55 face the inner surface 23m. The number and shape of the slits 52 to 55 can be appropriately selected as necessary, but in the case of a plurality of slits, an even number of slits are formed and the shapes thereof are the same. Also, the distance L2 is appropriately selected as required. Reference numeral 57 is a coupling tap for screwing the push plate, and 58 is a rear end accommodating portion of the piezoelectric element.

A third embodiment of the present invention will be described with reference to FIGS. The difference between this embodiment and the second embodiment is that slits 52 to 55 are provided on both ends of the column 23.
That is, the vine slit space-shaped spring portions SP1 and SP2 are formed. By doing so, a larger spring constant in the Y-axis direction can be obtained than in the above embodiment.

A fourth embodiment of the present invention will be described with reference to FIGS. The difference between this embodiment and the first embodiment is that the spring portion is an inclined slit-shaped spring portion, and the upper surface 23e and the lower surface 23 are
There are four slits 62, 63, 64, 65 inclined in the d direction.
Is formed. These slits 62-6
Depth, inclination angle, width, etc. of 5 are appropriately selected as necessary.

A fifth embodiment of the present invention will be described with reference to FIGS. The difference between this embodiment and the first embodiment is that
The spring portion SP is a cubic space-like spring portion, and is a cubic shape in which a horizontal through hole in the inner surface 23n and the outer surface 23m direction of the pillar portion 23 and a vertical through hole in the upper surface 23e lower surface 23d direction orthogonal to the horizontal through hole are formed. It is to have the space-like portions 72, 73, 74, and 75. The number, size, etc. of the cubic space portions 72 to 75 are appropriately selected as needed.

A sixth embodiment of the present invention will be described with reference to FIGS. The difference between this embodiment and the fifth embodiment is that
The spring portion SP is a cylindrical space spring portion, forms a cylindrical horizontal through hole in the inner surface 23n outer surface 23m direction of the column portion 23, and has a cylindrical vertical through hole orthogonal to each horizontal through hole as the upper surface 23e lower surface 2
That is, it has cylindrical space portions 82, 83, 85 formed in the 3d direction. The number, size, and the like of the cylindrical space portions 82 to 85 are appropriately selected as needed.

[0039]

Since the present invention is constructed as described above, Y
It is possible to absorb an external force in the axial direction or the Z-axis direction. Therefore, the piezoelectric element is prevented from being damaged, and the mounting error is absorbed to facilitate the assembling work. Further, the parallelism error between the guide shaft and the ball screw is also absorbed by the spring force in the Y-axis direction and the Z-axis direction. The stage can move smoothly. Moreover, since the hemispherical projection is provided at the tip of the piezoelectric element and the receiving portion of the displacement receiving member is formed in a conical shape, the piezoelectric element can easily rotate and the force can be released. Therefore, an unreasonable force is not applied to the piezoelectric element, so that a damage accident can be prevented.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention.

FIG. 2 is a plan view showing the first embodiment of the present invention.

FIG. 3 is a front view showing a use state.

FIG. 4 is a side view of FIG. 3;

FIG. 5 is a plan view showing a second embodiment of the present invention.

FIG. 6 is a front view showing a third embodiment of the present invention.

FIG. 7 is a plan view showing a third embodiment of the present invention.

FIG. 8 is a front view showing a third embodiment of the present invention.

FIG. 9 is a front view showing a fourth embodiment of the present invention.

FIG. 10 is a plan view showing a fourth embodiment of the present invention.

FIG. 11 is a plan view showing a fifth embodiment of the present invention.

FIG. 12 is a front view showing a fifth embodiment of the present invention.

FIG. 13 is a plan view showing a sixth embodiment of the present invention.

FIG. 14 is a front view showing a sixth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Moving table 5 Stage 10 Coarse movement device 12 Ball screw 13 Ball screw nut 20 Fine movement device 21 Gate spring 23 Strut part 24 Hemispherical protrusion 25 Piezoelectric element 26 Push plate 30 Mounting base 34 Receiving part 41 Guide part 42 Guide shaft

Claims (9)

[Claims] 1. A piezoelectric unit having a spring for applying a pre-load to a piezoelectric element; the spring comprising a mounting base and a support, and having rigidity in the X-axis direction in the Y-axis and Z-axis directions. A piezoelectric unit, which is a larger gate spring. 2. A piezoelectric unit having a piezoelectric element and a spring for applying a preload to the piezoelectric element, the spring comprising:
It has a mounting base and a support, and has a rigidity of Y in the X-axis direction.
A gate-shaped spring that is larger in the axial and Z-axis directions, in which a piezoelectric element is arranged between the pillars of the gate-shaped spring, and a pressing plate for pressing the piezoelectric element is crimped to the tip of the pillar-shaped spring. A piezoelectric unit characterized in that 3. The piezoelectric unit according to claim 1, wherein the gate-shaped spring is provided with an S-shaped spring portion on its column portion. 4. The gate-shaped spring is provided with a slit-shaped spring portion on the column portion thereof.
The described piezoelectric unit. 5. The gate-type spring is provided with a cubic space spring portion on its column portion.
The described piezoelectric unit. 6. The portal spring according to claim 1 or 2, wherein each of the columns has a cylindrical space spring portion.
The described piezoelectric unit. 7. The piezoelectric element has a hemispherical projection at its tip, and the pressing plate has a conical receiving portion for holding the hemispherical projection. The described piezoelectric unit. 8. The piezoelectric unit according to claim 2, wherein the push plate is screwed to the tip of the column of the gate spring. 9. A moving table, wherein the stage is connected to the coarse movement device via a fine movement device provided with a spring for applying a pre-load to the piezoelectric element; the spring having a mounting base and a support portion. And a rigidity higher in the X-axis direction than that in the Y-axis and Z-axis directions, and a piezoelectric element is arranged between the pillars of the gate-shaped spring, and at the tip of the pillar-shaped spring. A pressing plate for pressing the piezoelectric element is crimped, and the coarse movement device is provided with a ball screw nut fixed to a gate spring and a ball screw screwed to the nut. A moving table using a piezoelectric unit.