JP2607766B2 - Linear step motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear step motor of a worm type, and more particularly to a linear step motor having a clamp mechanism using compressed air.

[0002]

2. Description of the Related Art In recent years, in the field of microlithography and the like, a positioning mechanism with high resolution, for example, positioning accuracy of 10 nm or less and high reproducibility has been demanded. In.

FIG. 5 is a diagram, for example, described in Japanese Patent Laid-Open Publication No. 2-41670, schematically showing the operation of a linear step motor using a thermal expansion / contraction element or a piezoelectric element as an actuator. The figure shows an actuator in which, for example, three stacked piezoelectric elements 1, 2, and 3 are combined in an H-shape.
And press the flat plates 4 and 5 to fix them (Fig. 5 (a)),
Next, the piezoelectric element 2 is extended to advance the piezoelectric element 3 (FIG. 5 (b)). Subsequently, the piezoelectric element 3 is extended and fixed between the flat plates 4 and 5 (FIG. 5 (c)). After contraction, the piezoelectric element 1 is advanced by contracting the piezoelectric element 2 (FIG. 5 (d)). By repeating the above operation, a stepping motion is obtained for each displacement of the piezoelectric element 2, thereby realizing high-resolution positioning accuracy.

FIG. 6 shows a structure of an example in which the principle of the linear step motor shown in FIG. 5 is put to practical use. As shown in FIG. 6, the direction in which the laminated piezoelectric elements 6, 7, 8 expand and contract is changed. While being arranged so as to be parallel to the parallel rails 9 and 10,
Moving parts 11 and 12 connected to left and right laminated piezoelectric elements 6 and 8 are provided, and left and right laminated piezoelectric elements 6 and 8 are connected to movable parts 11 and 12 and rails.
The system clamps 9,10. For example, when the piezoelectric element 6 expands, the tip of the movable part 11 is compressed so as to press the rails 9 and 10, and the tip of the movable part 11 is fixed to the rails 9 and 10. When the piezoelectric element 6 contracts,
The pressing force of the tip of 11 is weakened, and the tip of movable portion 11 slides on rails 9 and 10. The linear step motor shown in FIG. 6 operates on the same principle as that shown in FIG.

[0005]

However, the above-described linear step motor has the following problems. In other words, when a multilayer piezoelectric element is used, (1) since at least three multilayer piezoelectric elements are used, a driving device for driving them is complicated and expensive. (2) In a series of operations, A high positioning resolution and an unnecessarily high generating force are not required for turning on and off the clamp. In addition, many linear step motors of this type are manufactured for the purpose of positioning a large stroke with high resolution rather than increasing the driving speed. Therefore, the characteristics of the piezoelectric element such as high resolution, high power, and high-speed response are not fully utilized only in the clamp part. (3) Since the number of piezoelectric elements used is large, when driven at a high frequency, The generated heat is a problem. In addition, when a thermal expansion element is used, (1) the same problem as above occurs. (2) A thermal expansion element using thermal expansion due to a temperature change is:
Accuracy is on the order of microns and response is lower than piezoelectric elements. Therefore, it is not suitable for high-precision positioning. (3) Since the number of thermal expansion and contraction elements used is large, heat generated from the elements becomes a problem.

The present invention has been made in view of the above circumstances, and has as its object to provide a linear step motor capable of positioning an on / off stroke of a clamping operation with high resolution.

[Structure of the Invention]

[0008]

According to a first aspect of the present invention, there is provided a linear step motor comprising: a guide; an actuator made of an electrostrictive material which expands and contracts at a predetermined timing along the guide; A clamping mechanism which has a deformed portion having a static pressure guide surface for guiding compressed air while being clamped, and a clamp mechanism for clamping the guide by deforming the deformed portion with compressed air supplied at a predetermined timing; A control unit for controlling the supply of the compressed air to the mechanism unit.

According to a second aspect of the present invention, in the linear step motor, the deformable portion has an elastic body attached to a surface facing the guide, and a cutout is formed near one end of the elastic body. It is characterized by.

[0010]

Since the present invention is constructed as described above, the clamping mechanism for clamping the actuator performs the clamping operation on the guide by bending and deforming the deformed portion with the compressed air supplied at a predetermined timing. The motor body moves forward. Therefore, only one electrostrictive material is used for the actuator, and high-speed, high-precision positioning can be performed.

Further, in the present invention, since the deformed portion is configured as described above, a large contact area with the guide at the time of bending deformation is obtained, and the area of the elastic body to be stuck is also increased, so that a stable clamping state is obtained. Can be In addition, the formation of the notch facilitates the occurrence of bending deformation.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a linear step motor according to one embodiment of the present invention.

As shown in FIG. 1, clampers 22 and 23 which float by compressed air in a space constrained by a guide 20 and a rail 21 are provided with electrostrictive elements 24 which are one of electrostrictive materials.
Are arranged in such a manner as to hold the. The electrostrictive element 24 operates as a forward actuator in a linear step motor. Each clamper 22 and 23 has a clamper.
Compressed air for floating the 22, 23 is supplied via a pipe 25, and compressed air for bending and deforming the respective clampers 22, 23 is supplied from a pipe 26. Compressed air that causes the clampers 22 and 23 to bend and deform is controlled by servo valves 27 and 28 so as to be intermittently and alternately supplied to the clampers 22 and 23, and then is connected to the respective clampers 22 through pipes 26a and 26b. , 23 respectively.

2 and FIG. 3 is an enlarged view of a portion B of FIG. 3, the clamper 23 has a filling chamber 23a filled with compressed air supplied through a pipe 26b. A static pressure guide surface for guiding compressed air to the filling chamber 23a is formed of, for example, a metal outer wall portion 23b formed on the inner surface,
The outer wall portion 23b is configured to wrap one protruding portion 21a of the rail 21 having an H-shaped cross section fixed to the side wall of the guide 20 from above and below. Further, at the tip of the outer wall 23b of the clamper 23, there are formed bending deformation portions 23c, 23c having a predetermined angle of inclination. The thin plates of the bodies 29, 29 are affixed. Further, notches 23d, 23c on the outer surface side are provided near one ends of the elastic bodies 29, 29 so that the flexures 23c, 23c easily undergo flexure when compressed air is supplied from the pipe 26b.
d is formed.

Next, the operation of the clamper 23 having the above configuration will be described.

When the servo valve 28 is turned off and compressed air is not supplied from the pipe 26b, the clamper 23 maintains the state shown by the solid line in FIGS.
Has not caused bending deformation.

When the servo valve 28 is turned on, compressed air is supplied from the pipe 26b and guided by the static pressure guide surface of the outer wall 23b to fill the filling chamber 23a with the compressed air. Since flexure deformation is likely to occur due to the presence of 23d, 23d, the flexure deforms in the direction of arrow C as shown by the broken line in FIG. When the bending portion 23c is bent, the elastic bodies 29, 29 push the upper and lower surfaces of the guide 20, and the clamper 23 is fixed to the guide 20. At this time, the contact area between the elastic bodies 29, 29 and the guide 20 becomes large because the bending deformation portion 23c has an inclination,
The clamper 23 is fixed to the guide 20 in a more stable state.

The clamper 22 has the same configuration and performs the same operation.

Next, the operation of the linear stepping motor having the above-described configuration in the tapeworm type will be described with reference to FIG.

As shown in FIG. 1, first, the compressed air is supplied to the clamper 22 and the supply of the compressed air to the clamper 23 is stopped. As a result, when the elastic body 30 comes into contact with the guide 20, the clamper 22 is fixed to the guide 20, while the clamper 23 is not in contact with the guide 20, that is, a so-called clamp O.
The state becomes FF. (See FIG. 4 (a)).

Next, an electrostrictive element is driven by a driving device (not shown).
24 extends and the clamper 23 moves forward. Thus the electrostrictive element
As the 24 is extended and displaced, the linear step motor body moves forward. The electrostrictive element 24 used here has a high speed
An actuator suitable for high-precision positioning is desired. (See FIG. 4 (b)).

Subsequently, the servo valve 28 is turned on and compressed air is supplied to the clamper 23. Thereby, the elastic body 29
Is brought into contact with the guide 20, and the clamper 23 is fixed to the guide 20, that is, in a so-called clamp ON state. (See FIG. 4 (c)).

When the clamper 23 is in the clamp ON state, the servo valve 27 is controlled to be turned off, the supply of compressed air to the clamper 22 is stopped, and the clamper 22 is turned off.
State. At this time, the clamper 22 is turned off.
As a result, the electrostrictive element 24 contracts, and the clamper 22 moves forward. (See FIG. 4 (d)).

Subsequently, compressed air is supplied to the clamper 22 again. Clamper 22 is fixed to guide 20 and clamp ON
State. At this time, the clamper 23 keeps the clamp ON state. (See FIG. 4 (e)).

By repeating the above operation, a stepping motion is obtained for each displacement of the electrostrictive element 24, and highly accurate positioning is performed.

In the above embodiment, an electrostrictive element is used as the electrostrictive element. However, the present invention is not limited to this, and a piezoelectric element may be used.

Further, the present invention is not limited to the above embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

[0029]

As described in detail above, according to the linear stepping motor of the present invention, the clamping mechanism for clamping the actuator is configured to perform the clamping operation by deforming the deformed portion, so that it is used for the actuator. Requires only one electrostrictive element such as an electrostrictive element.
Positioning can be performed with high accuracy. Further, the driving circuit of the actuator composed of the electrostrictive element is simplified, and the amount of heat generated when driving at a high frequency can be reduced. Further, as compared with the case where an actuator composed of a thermal expansion / contraction element is used, high-speed and high-accuracy can be achieved, and the thermal effect can be greatly reduced.

Further, since the present invention employs a clamping mechanism for clamping by bending deformation, it is easy to increase the size of the apparatus, and it is possible to apply the apparatus in a wide range of fields.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a linear step motor according to one embodiment of the present invention.

FIG. 2 is a sectional view of a linear step motor according to one embodiment of the present invention.

FIG. 3 is an enlarged view of a main part of the linear step motor according to one embodiment of the present invention.

FIG. 4 is a flowchart showing an outline of a flow of a stepping motion.

FIG. 5 is a diagram illustrating the principle of a linear step motor.

FIG. 6 is a diagram showing a conventional linear step motor.

[Explanation of symbols]

 20: Guide 22: Clamp (clamp mechanism) 23: Clamp (clamp mechanism) 23c: Deflection part 23d: Notch 24: Electrostrictive element (actuator) 27: Servo valve (control unit) 28: Servo valve (control) Part) 29 ... elastic body 30 ... elastic body

Claims (2)

(57) [Claims] A guide, an actuator made of an electrostrictive material which expands and contracts at a predetermined timing along the guide, and a deformable portion which sandwiches the actuator and has a static pressure guide surface for guiding compressed air. equipped with clamping mechanism for performing clamp operation to the guide by the deformable portion is deformed, and a control unit for controlling the supply of the compressed air to the clamping mechanism with compressed air supplied at a predetermined timing A linear step motor characterized by the above-mentioned. Wherein deformations the elastic body is affixed on a surface facing the guide, the linear step motor according to claim 1, wherein a cutout portion at one end near the elastic body is formed.