JP2007313589A - Positioning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positioning device capable of improving the precision of positioning. <P>SOLUTION: The positioning device is provided with a base 21, an oscillation table 22 with a shaft section 22 loosely fitted in a hole part 21a formed in the central part of the upper surface of the base 21, and a hydrostatic gas bearing 25 arranged between the shaft part 22a of the oscillation table 22 and the hole part 21a of the base 21. Gas supply passages 26a, 26b supplying gas to the hydrostatic gas bearing 25 are provided in the base 21. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a positioning device used in, for example, a semiconductor manufacturing apparatus.

  In a semiconductor manufacturing apparatus or the like, a positioning apparatus 1 as shown in the figure is used as a positioning apparatus for positioning a workpiece at a predetermined position (see Patent Document 1). The moving body 2 of the positioning device 1 is moved to the guide portion 6 by a hydrostatic fluid bearing comprising hydrostatic gas bearing portions 3a and 3b, hydrostatic gas bearing portions 4a and 4b, and a permanent magnet which is a preload biasing means 5. It is supported. Fluid supply lines 7a, 7b, 8a, 8b are individually connected to the static pressure gas bearing portions 3a, 3b, 4a, 4b, and the working fluid is supplied from the fluid supply apparatus (not shown) to the fluid supply lines. 7a, 7b, 8a and 8b are supplied to the respective static pressure gas bearing portions 3a, 3b, 4a and 4b so as to function as a static pressure fluid bearing.

A nut portion 9 is provided on the upper portion of the moving body 2, and the nut portion 9 is engaged with a ball screw 10. The ball screw 10 is connected to a central axis of a servo motor 11, and an encoder 12 is attached to the servo motor 11. It has been.
In the positioning device having such a configuration, since the hydrostatic fluid bearing portions 3a, 3b, 4a, and 4b are used as bearings that support the movable body 2 so as to be linearly movable, no frictional force is generated. Therefore, even when the driving method using the ball screw 10 is used, unlike the case of a contact bearing such as a linear guide, the generation of external force due to elastic deformation of the ball screw 10 and the like remaining after positioning can be suppressed to a low level.
JP-A-10-199803

However, in the positioning device described above, since the static pressure gas bearing is provided on the movable side, it is necessary to provide a gas supply path for supplying a gas such as air to the static pressure gas bearing in the moving body. For this reason, the gas supply path or wiring provided in the moving body may become a disturbance factor during the positioning operation, which may cause a displacement of the moving body.
The present invention has been made paying attention to the above-described problems, and an object thereof is to provide a positioning apparatus capable of improving positioning accuracy.

  In order to achieve the above object, a positioning device according to a first aspect of the present invention includes a base, a swing table having a shaft portion loosely fitted in a hole formed in a surface portion of the base, and the swing table. A non-contact type bearing provided between a shaft portion of the moving table and a hole in the base; and a table driving mechanism for driving the swing table to swing relative to the base; The type bearing is a positioning device including any one of a static pressure gas bearing, a magnetic bearing, and an electrostatic force application bearing, wherein the non-contact type bearing is provided on a fixed side.

  A positioning device according to a second aspect of the present invention includes a slide table, a guide rail for guiding the slide table, a non-contact type bearing for slidably supporting the slide table with respect to the guide rail, and the slide table. A non-contact type bearing comprising a static pressure gas bearing, a magnetic bearing, or an electrostatic force application bearing, The non-contact type bearing is provided on the fixed side.

  In the positioning device according to the first aspect of the invention, the non-contact type bearing is composed of a static pressure gas bearing, and a gas supply path for supplying gas to the static pressure gas bearing is formed in the base to improve positioning accuracy. Is preferable. In addition, in order to improve positioning accuracy, the table drive mechanism is composed of a linear motor having a fixed coil fixed to the base and a movable magnet fixed to the swing table so as to face the fixed coil. preferable. Furthermore, it is preferable in terms of improving positioning accuracy that an exhaust path for evacuating the air in the table suction space formed between the base and the swing table is provided in the base.

  In the positioning device according to the second aspect of the invention, the non-contact type bearing is composed of a static pressure gas bearing, and a gas supply path for supplying gas to the static pressure gas bearing is formed in the guide rail. Is preferable. Further, it is preferable in terms of improving positioning accuracy that the table driving mechanism is composed of a linear motor having a fixed side coil fixed to the guide rail and a movable side magnet fixed to the slide table so as to face the fixed side coil. . Furthermore, it is preferable to provide an exhaust passage in the guide rail for evacuating the air in the table suction space formed between the guide rail and the slide table from the viewpoint of improving positioning accuracy.

According to the positioning device according to the first aspect of the present invention, since it is not necessary to provide a gas supply path or wiring on the movable side, it is possible to improve the positioning accuracy by suppressing the displacement of the swing table.
According to the positioning device according to the second aspect of the present invention, it is not necessary to provide a gas supply path or wiring on the movable side, so that it is possible to improve the positioning accuracy by suppressing the displacement of the slide table.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a plan view of a positioning device according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1, and as shown in FIG. The positioning device according to the embodiment includes a base 21, a swing table 22, and a position detector 23 that detects a swing position of the swing table 22.

The base 21 has a rectangular shape, and a circular hole 21a is recessed in the center of the upper surface as shown in FIG. On the other hand, the swinging table 22 has a disk shape, and a shaft portion 22a that is loosely fitted to the hole portion 21a of the base 21 protrudes from the center portion of the lower surface thereof.
The swing table 22 is driven to swing within a predetermined angle range around the axis of the shaft portion 22a by a linear motor 24 as a table drive mechanism. The linear motor 24 is mounted on the base 21. The fixed side coil 241 is fixed, and the movable side magnet 242 is mounted on the swing table 22 so as to face the fixed side coil 241.

The position detector 23 includes a magnetic scale 231 fixed to the swing table 22 and a scale reading head 232 that magnetically reads the magnetic scale 231. The scale reading head 232 faces the magnetic scale 231 and is a base 21. It is being fixed to the upper surface part.
The linear motor 24 and the position detector 23 are provided at an equal angle of 180 °, and the mass of the movable magnet 242 and the mass of the magnetic scale 231 are substantially equal.

  Between the hole 21a of the base 21 and the shaft part 22a of the swing table 22, a static pressure gas bearing 25 as a non-contact type bearing that supports the swing table 22 so as to be swingable with respect to the base 21. Is provided. The static pressure gas bearing 25 is fixed to the base 21, and gas supply paths 26 a and 26 b for supplying gas to the static pressure gas bearing 25 are formed inside the base 21. Exhaust passages 27a and 27b for exhausting air in the table suction space 28 formed on the outer periphery of the bearing 25 are formed. The upper surface and inner peripheral surface of the static pressure gas bearing 25 are used as bearing surfaces.

The table adsorption space 28 is formed between an annular convex portion 29 provided on the upper surface of the base 21 and the static pressure gas bearing 25, and the air in the table adsorption space 28 is evacuated by a vacuum pump (not shown). By evacuating, the swing table 22 is locked so as not to swing.
The surface to be a seating surface (for example, the upper surface of the convex portion 29) is preferably a surface that can prevent galling and has high hardness, and examples thereof include those coated with a coating such as CVD diamond, TiAlN, or TiN.

In the case of a positioning device in which the oscillating table 22 is provided in the atmosphere, the air in the table adsorption space 28 may not necessarily be exhausted by the vacuum pump while the static pressure gas bearing 25 is in operation. During operation of the pressurized gas bearing 25, the exhaust passages 27a and 27b may be opened to the atmosphere by controlling a control valve (not shown), for example.
However, even in the case of a positioning device in which the swing table 22 is provided in the atmosphere, the air in the table adsorption space 28 may be exhausted by the vacuum pump even during operation of the static pressure gas bearing 27. . In this case, the gap between the convex portion 29 (or the upper surface of the static pressure gas bearing 25) and the lower surface of the swing table 22 is controlled by controlling the pressure of the gas supplied to the static pressure gas bearing 25 and the exhaust pressure by the vacuum pump. The thrust bearing can be controlled and has high bearing rigidity.

  In particular, in the case of a positioning device in which the swing table 22 is provided in a vacuum, it is preferable that the air in the table adsorption space 28 is exhausted by the vacuum pump even during operation of the static pressure gas bearing 25. . Thereby, during the operation of the static pressure gas bearing 25, almost all the gas discharged from the static pressure gas bearing 25 and entering the table adsorption space 28 is discharged to the outside through the exhaust passages 27a and 27b, Leakage from the minute gap with the swing table 22 into the vacuum atmosphere can be suppressed. Thereby, the burden of exhaust in a vacuum atmosphere can be reduced.

  In such a configuration, when a gas such as air is supplied from the gas supply paths 26a and 26b formed in the base 21 to the static pressure gas bearing 25, as shown in FIG. 22 floats from the upper end surface of the static pressure gas bearing 25, and a minute gap is maintained between the inner peripheral surface of the static pressure gas bearing 25 and the outer peripheral surface of the shaft portion 22a. It is supported so that it can swing. Thus, unlike the above-described conventional example, it is not necessary to form a gas supply path for supplying gas to the static pressure gas bearing 25 on the movable side (oscillation table side), so that the displacement of the oscillation table 22 is suppressed. Thus, the positioning accuracy can be improved.

  Further, except during positioning driving by the table driving mechanism, air in the table suction space 28 is exhausted from the exhaust passages 27a and 27b formed in the base 21, and the negative pressure in the table suction space 28 is increased. As shown in FIG. 3B, the swinging table 22 is locked so that it cannot swing by adsorbing the lower surface of the swinging table 22 onto an annular convex portion 29 provided on the upper surface of the base 21. Is done. As a result, there is no need to form an exhaust path for exhausting air in the table suction space on the movable side (oscillating table side). Can be planned. In addition, after the lower surface portion of the swing table 22 is adsorbed on the convex portion 29 provided on the upper surface portion of the base 21, it causes a drift (change with time) of the θ axis. Is preferably OFF. Moreover, since the gas supply to the static pressure gas bearing 25 is unnecessary, it may be stopped.

  In the first embodiment described above, the linear motor 24 including the fixed coil 241 and the movable magnet 242 is used as the table driving mechanism for swinging the swing table 22, so that the linear motor 24 is supplied with power. Since it is not necessary to wire the electric wire on the movable side (the swing table side), the positioning accuracy of the swing table 22 can be further increased.

Further, since the linear motor 24 is used as a table driving mechanism for swinging and driving the swing table 22, a restraining force is exerted on the vertical movement of the static pressure gas bearing 25 by turning off the servo of the linear motor 24. Because it does not have, it is convenient. Further, a position detector 23 for detecting the swing position of the swing table 22 is a magnetic scale 231 fixed to the swing table 22, and a scale reading head fixed on the base 21 so as to face the magnetic scale 231. Since it is not necessary to wire the power supply line to the position detector 23 on the movable side (the swing table side), the positioning accuracy of the swing table 22 can be further increased.
Furthermore, since the linear motor 24 and the position detector 23 are arranged at an equal angle of 180 °, and the mass of the movable magnet 242 and the mass of the magnetic scale 231 are substantially equal, the imbalance can be eliminated as much as possible. .

  In the first embodiment described above, the through hole is exemplified as the hole portion 21a formed in the central portion of the upper surface of the base 21, but a bottomed hole may be used. However, in the case of a bottomed hole, for example, an exhaust hole is preferably formed on the bottom surface. Further, although the static pressure gas bearing 25 is exemplified as the non-contact type bearing that supports the swing table 22 so as to be swingable with respect to the base 21, it may be a magnetic bearing or a bearing to which electrostatic force is applied. In particular, in the case of a bearing that applies electrostatic force, it does not affect the surrounding environment due to magnetic field fluctuations, so it is suitable for applications that hate magnetic field fluctuations, and compared to the case where magnetic bearings are used. There is little fever. Even when a magnetic bearing or a bearing applying electrostatic force is used as a non-contact type bearing, if there is a mechanism capable of switching and controlling repulsion and suction, suction by suction of the suction space 28 using a vacuum pump The mechanism may be omitted, and both the bearing and the suction mechanism may be used. Thereby, the apparatus can be miniaturized.

Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 4 is a plan view of a positioning device according to the second embodiment of the present invention, and FIG. 5 is a cross-sectional view taken along the line V-V of FIG. 4, and as shown in FIG. The positioning device according to the embodiment includes a block-shaped slide table 31 and a guide rail 32 for guiding the slide table 31.

  The guide rail 32 has a concave cross section along the width direction, and an inner surface portion of the guide rail 32 includes a hydrostatic gas bearing 33a as a non-contact type bearing that slidably supports the slide table 31 with respect to the guide rail 32. 33b and 33c (see FIG. 5) are provided to face the left and right side surfaces and the bottom surface of the slide table 31, respectively. These static pressure gas bearings 33 a to 33 c are fitted into recesses 34 a, 34 b, 34 c formed on the inner surface of the guide rail 32, and a gas such as air is introduced into the guide rail 32 by a static pressure gas bearing. Gas supply paths 35a, 35b, and 35c for supplying to 33a to 33c are formed, and air in the table suction spaces 36a and 36b formed between the lower surface portion of the slide table 31 and the inner surface portion of the guide rail 32 is formed. Exhaust passages 37a and 37b are formed. A vacuum pump (not shown) is operated to exhaust the air in the table suction spaces 36a and 36b via the exhaust passages 37a and 37b, and the slide table 31 can be locked.

  Further, the positioning device according to the second embodiment includes a linear motor 38 as a table driving mechanism that slides the slide table 31 in the longitudinal direction of the guide rail 32, and a position detector 39 that detects the slide position of the slide table 31. As shown in FIG. 5, the linear motor 38 is fixed to the slide table 31 so as to face the fixed coil 381 fixed to the upper surface of the guide rail 32 and the fixed coil 381. And a movable side magnet 382. On the other hand, the position detector 39 includes a magnetic scale 391 fixed to the slide table 31 and a scale reading head 392 fixed to the upper surface of the guide rail 32 so as to face the magnetic scale 391.

  In such a configuration, when a gas such as air is supplied to the static pressure gas bearings 33a, 33b, and 33c from the gas supply paths 35a, 35b, and 35c formed in the guide rail 32, it is shown in FIG. Thus, the slide table 31 is brought into a non-contact state with respect to the guide rail 32 by the gas ejected from the static pressure gas bearings 33a, 33b, and 33c. When the linear motor 38 is operated in this state, the slide table 31 slides in the longitudinal direction of the guide rail 32. Thereby, unlike the above-described conventional example, it is not necessary to form a gas supply path for supplying gas to the static pressure gas bearings 33a, 33b, 33c on the movable side (slide table side). And the positioning accuracy can be improved. In this case, the exhaust in the table suction spaces 36a and 36b by the vacuum pump may be performed in the same manner as in the first embodiment or may not be performed.

  Except during positioning driving by the table drive mechanism, the air in the table suction spaces 36a and 36b is exhausted from the exhaust passages 37a and 37b formed in the guide rail 32, and the negative pressure in the table suction spaces 36a and 36b is reduced. As shown in FIG. 6B, the lower surface of the slide table 31 is seated on the static pressure gas bearing 33c so that the slide table 31 is locked so as not to slide. At this time, at least the supply of gas to the static pressure gas bearing 33c is unnecessary and may be stopped. Thereby, there is no need to form an exhaust path for exhausting air in the table adsorption space on the movable side (slide table side), so that the displacement of the slide table 31 is suppressed and the positioning accuracy is further improved. Can do.

  In the second embodiment described above, the linear motor 38 including the fixed coil 381 and the movable magnet 382 is used as the table driving mechanism for swinging the slide table 31. Since it is not necessary to wire to the movable side (slide table side), the positioning accuracy of the slide table 31 can be further increased.

  Further, since the linear motor 38 is used as a table driving mechanism for slidingly driving the slide table 31, the linear motor 38 has no binding force with respect to the vertical movement of the static pressure gas bearing by turning off the servo of the linear motor 38. Therefore, it is convenient. Further, a scale reading head 392 having a position detector 39 for detecting the swing position of the slide table 31 fixed to the guide rail 32, and a magnetic scale 391 fixed to the slide table 31 facing the scale reading head 392, Since it is not necessary to wire the power supply line to the position detector 39 on the movable side (oscillating table side), the positioning accuracy of the slide table 31 can be further increased.

In the second embodiment described above, the static pressure gas bearings 33a to 33c are exemplified as non-contact type bearings that slidably support the slide table 31 with respect to the guide rail 32. However, the bearings may be magnetic bearings or bearings using electrostatic force. There may be. In particular, in the case of a bearing to which electrostatic force is applied, there is no influence on the surrounding environment due to magnetic field fluctuations.
In the second embodiment, air supply / exhaust is performed from the fixed side. However, for example, the technology disclosed in Japanese Patent No. 3261823 may be employed to supply / exhaust air from the movable side. In addition, by adopting the technique disclosed in Japanese Patent No. 1626496 and switching the vacuum region and the hydrostatic bearing portion according to the stroke position, it is possible to prevent the levitation force and the suction force from being lowered.

  In the above-described embodiment, the present invention is applied to a rotating or uniaxial linear mechanism. However, the guide type is a planar guide having no horizontal constraint, and the horizontal direction is determined by two or more drive mechanisms. It may be what performs. In the case of planar guidance, if the driving mechanism is a surface motor, the number of driving mechanisms may be one. Furthermore, although the mechanism for applying the guide and the suction force is a separate mechanism, the same mechanism may be employed. In that case, the vertical position may be controlled smoothly so that a horizontal position shift does not occur due to abrupt position fluctuation.

In the above-described embodiment, the encoder is exemplified as the position detector. However, for example, a position detector using a laser length measurement system may be used.
As the suction means, it is preferable to select an element that operates in an emergency or transportation. A suction means using a permanent magnet is preferred. When a linear motor is used as the drive mechanism, a suction force acting on the motor may be adopted as a means for sucking the movable part to the fixed part by selecting a cored type.
With regard to vacuum suction, it is difficult during transportation, but in the event of an emergency, it is possible to maintain vacuum by adopting a normally closed valve, and it can be realized if the suction force can be maintained within a finite time. If the static electricity is not positively removed, the holding power is maintained.

It is a top view of the positioning device concerning a 1st embodiment of the present invention. It is sectional drawing which follows the II-II line of FIG. It is a figure for demonstrating the effect | action of the positioning device which concerns on the 1st Embodiment of this invention. It is a top view of the positioning device which concerns on the 2nd Embodiment of this invention. It is sectional drawing which follows the VV line of FIG. It is a figure for demonstrating the effect | action of the positioning device which concerns on the 2nd Embodiment of this invention. It is a perspective view of the conventional positioning device.

Explanation of symbols

21 base 21a hole 22 swing table 22a shaft 23 position detector 231 magnetic scale 232 scale reading head 24 linear motor 241 fixed coil 242 movable magnet 25 static pressure gas bearings 26a, 26b gas supply path 28 table adsorption space 31 Slide table 32 Guide rail 33a, 33b, 33c Static pressure gas bearing 35a, 35b, 35c Gas supply path 36a, 36b Table adsorption space 38 Linear motor 381 Fixed coil 382 Movable magnet 39 Position detector 391 Magnetic scale 392 Scale reading head

Claims (8)

A swing table having a base, a shaft portion loosely fitted in a hole formed in the surface portion of the base, and a shaft provided between the shaft portion of the swing table and the hole of the base. A non-contact type bearing, and a table drive mechanism that drives the swing table to swing relative to the base, wherein the non-contact type bearing is one of a static pressure gas bearing, a magnetic bearing, and an electrostatic force application bearing. A positioning device comprising one type of bearing,
A positioning device, wherein the non-contact type bearing is provided on a fixed side.   The positioning device according to claim 1, wherein the non-contact type bearing is a static pressure gas bearing, and the base has a gas supply path for supplying gas to the static pressure gas bearing.   3. The positioning device according to claim 1, wherein the table driving mechanism includes a fixed side coil fixed to the base and a movable side magnet fixed to the swing table so as to face the fixed side coil. A positioning device comprising a linear motor.   The positioning device according to any one of claims 1 to 3, wherein the base has an exhaust path for evacuating air in a table suction space formed between the base and the swing table. A positioning device. A slide table, a guide rail that guides the slide table, a non-contact type bearing that supports the slide table slidably with respect to the guide rail, and a table that slide-drives the slide table in the longitudinal direction of the guide rail A non-contact type bearing comprising a static pressure gas bearing, a magnetic bearing, and an electrostatic force application bearing,
A positioning device, wherein the non-contact type bearing is provided on a fixed side.   6. The positioning device according to claim 5, wherein the non-contact type bearing is a static pressure gas bearing, and the guide rail has a gas supply path for supplying gas to the static pressure gas bearing.   7. The positioning device according to claim 5, wherein the table driving mechanism includes a fixed side coil fixed to the guide rail, and a movable side magnet fixed to the slide table so as to face the fixed side coil. A positioning device comprising a motor.   The positioning device according to any one of claims 5 to 7, wherein the guide rail has an exhaust path for evacuating air in a table suction space formed between the guide rail and the slide table. Characteristic positioning device.

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