JP2024524733A - Magnetic levitation gravity compensation device and fine movement stage - Google Patents

Abstract

This application discloses a magnetic levitation gravity compensation device and a fine movement stage, the magnetic levitation gravity compensation device includes an inner base magnet, a first end magnetic steel, a second end magnetic steel, an inner magnet ring magnetic steel and an outer coil, the inner base magnet extends along the axial direction, the first end magnetic steel and the second end magnetic steel are respectively located at the two axial ends of the inner base magnet and extend along the axial direction, and the outer diameters of the first end magnetic steel and the second end magnetic steel are gradually increased along the direction away from the two axial ends of the inner base magnet, the inner magnet ring magnetic steel is cylindrical and located outside the inner base magnet coaxially with the inner base magnet, the outer coil is located outside the inner magnet ring magnetic steel coaxially with the inner base magnet, and is fixed to the inner base magnet, the first end magnetic steel and the second end magnetic steel. Because of the outer coil, the output force of the entire magnetic levitation gravity compensation device, which overcomes the gravity of the work stage and the elastic force of the flexible mechanism, can be controlled by controlling the direction and magnitude of the current in the outer coil, and meets the high movement performance requirements of the fine movement stage.

Description

This application claims priority to a patent application filed with the China Intellectual Property Office on July 16, 2021, bearing application number 202110804356.0 and title "Magnetic levitation gravity compensation device and micromotion stage."
This application relates to the field of integrated circuit device manufacturing, and more particularly to magnetically levitated gravity compensation devices and fine motion stages.

In the fields of semiconductor manufacturing and inspection, the work stage is required to transfer silicon wafers and to perform precise positioning. The core actuator in the work stage is a micropositioner that precisely positions the silicon wafer vertically along the three axes of Z, Rx, and Ry. In general, a vertical three-axis micropositioning stage is arranged using a three-point actuator, and a flexible mechanism (such as an elastic sheet) can be applied as a movement non-interference and guide for the micropositioning stage to ensure vertical performance. Within a small stroke range, the spring stiffness of the flexible mechanism is a constant value, and the reaction force acting on the vertical actuator increases or decreases linearly with the vertical displacement, but as the work stage stroke increases, the non-linearity of the flexible mechanism stiffness also gradually increases.

Therefore, the output force of the fine stage actuator needs to be adjusted along with the vertical stroke, thereby compensating for the variable stiffness of the flexible structure. Usually, the fine stage vertical actuator usually adopts a combination of a zero-stiffness gravity compensation device and a voice coil motor. The zero-stiffness gravity compensation device is used to compensate for the gravity of the stage device in the fine stage, and the stage device is used to mount the silicon wafer and drive and move the silicon wafer. The voice coil motor provides the elastic force of the flexible mechanism and the pushing and pulling force required for the vertical movement of the stage device. Within different vertical stroke ranges, the stiffness of the flexible mechanism has linear and non-linear regions, so it is very difficult to completely compensate for the elastic force of the flexible mechanism and the thrust force of the vertical movement by simply controlling the thrust force of the voice coil motor. In addition, in high acceleration working conditions, the output of the voice coil motor is large and the temperature rise is high, making it difficult to meet the high movement performance requirements of the fine stage.

Conventional technology generally employs an air-floating gravity compensation device that can achieve constant rigidity gravity compensation by adjusting the compressed gas pressure in real time using a proportional valve. However, the structure of the air-floating gravity compensation device is very complicated, and there is hysteresis in the air pressure control, which affects the improvement of vertical performance.

The purpose of the embodiments of the present application is to provide a magnetic levitation gravity compensation device and a fine movement stage, and the magnetic levitation gravity compensation device in the present application has a simple structure and control, a compact structure, and is capable of meeting the high movement performance requirements of the work stage.

In order to solve the above problems, a magnetic levitation gravity compensation device according to an embodiment of the present application includes:
an inner base magnet extending along an axial direction;
a first end magnetic steel and a second end magnetic steel respectively located at two axial ends of the inner base magnet and extending along the axial direction, the first end magnetic steel and the second end magnetic steel respectively having an outer diameter gradually increasing along a direction away from the two axial ends of the inner base magnet;
an inner magnet ring magnetic steel having a cylindrical shape, positioned outside the inner base magnet coaxially with the inner base magnet and radially spaced from the inner base magnet;
an outer coil positioned coaxially with the inner base magnet and outside the inner magnet ring magnetic steel, the outer coil being radially spaced apart from the inner magnet ring magnetic steel and fixed relative to the inner base magnet, the first end magnetic steel, and the second end magnetic steel.

In one embodiment, the magnetization direction of the inner base magnet is axial, the magnetization direction of the first end magnetic steel and the second end magnetic steel is axially outward from the inner base magnet, and the magnetization direction of the inner magnet ring magnetic steel is from inside the ring to outside the ring of the inner magnet ring magnetic steel.
In one embodiment, the magnetization direction of the inner base magnet is axial, the magnetization directions of the first end magnetic steel and the second end magnetic steel are axially directed from the outside toward the inner base magnet, and the magnetization direction of the inner magnet ring magnetic steel is from the outside of the inner magnet ring magnetic steel toward the inside of the ring.

In one embodiment, the magnetic levitation gravity compensation device further includes an outer magnet ring magnetic steel located outside the outer coil coaxially with the inner magnet ring magnetic steel, the outer magnet ring magnetic steel being radially spaced apart from the outer coil and fixed relative to the inner magnet ring magnetic steel;
The magnetization direction of the outer magnet ring magnetic steel is the same as that of the inner magnet ring magnetic steel.

In one embodiment, the outer magnet ring magnetic steel is composed of a plurality of arc plates adjacent to each other along the circumferential direction,
The magnetization direction of each of the arc plates is a radial direction or a direction parallel to the radial direction of the circumferential center of the arc plates.
In one embodiment, the magnetic levitation gravity compensation device further includes an outer guide magnet ring positioned coaxially with the inner magnet ring magnetic steel outside the outer coil and radially spaced apart from the outer coil.

In one embodiment, the inner base magnet is a permanent magnet or an inner coil or a combination of the permanent magnet and the inner coil, and the inner coil is wound circumferentially around the axis of the first end magnetic steel and the second end magnetic steel.
In one embodiment, the inner magnet ring magnetic steel is composed of a plurality of arc plates adjacent to each other along the circumferential direction, and the magnetization direction of each of the arc plates is radial or parallel to the radial direction of the circumferential center of the arc plates.

The present invention further provides a fine movement stage,
A stage device;
a fine movement base to which the stage device is connected so as to be slidable in a direction perpendicular to the fine movement base;
a flexible mechanism including an elastic sheet, the elastic sheet extending in a horizontal radial direction, a radially inner end of the elastic sheet being connected to the stage device, and a radially outer end of the elastic sheet being connected to the fine motion base;
The magnetic levitation gravity compensation device includes the above-mentioned magnetic levitation gravity compensation device, wherein the inner base magnet, the first end magnetic steel, the second end magnetic steel and the outer coil are incorporated into one of a stator and a mover, and the inner magnet ring magnetic steel is the other of the stator and the mover, the magnetic levitation gravity compensation device is located below a stage device, the stator is fixed to the fine movement base, and the mover is fixed to the stage device.

In one embodiment, the magnetic levitation gravity compensation devices are multiple, and the perpendicular lines on which the equivalent centers of gravity of the multiple magnetic levitation gravity compensation devices are located are the same line as the perpendicular line on which the center of gravity of the stage device is located.

Compared with the prior art, the magnetic levitation gravity compensation device of the present application solves the problems of the prior art pneumatic constant stiffness gravity compensation device, such as complex structure, complex control, and hysteresis in control, and solves the problem of the stiffness of the prior art gravity compensation device being zero or non-linear. In the present application, when the outer coil current is zero, the magnetic levitation output force exhibits linear characteristics along the stroke in the linear region, and the output force can offset the gravity of the stage device at the zero point, and in the non-linear region, the output force is adjusted by changing the current in the outer coil to realize compensation for the gravity of the stage device and the elastic force of the flexible mechanism. According to the present application, not only can the gravity of the stage device be compensated for, but the elastic deformation reaction force of the flexible mechanism can also be balanced within a large stroke range, reducing the load on the vertical actuator and greatly improving the vertical performance of the fine movement stage. In addition, since the magnetic levitation gravity compensation device further includes an outer coil, by controlling the direction and magnitude of the current in the outer coil, it is possible to control the output force of the entire magnetic levitation gravity compensation device, which overcomes the gravity of the stage device and the elastic force of the flexible mechanism, thereby enabling the movement speed, etc. of the stage device to be accurately controlled and also meeting the high movement performance requirements of the stage device.

The accompanying drawings, which form part of this application, are used to provide a further understanding of the present application, and the exemplary embodiments and their descriptions are used to interpret the present application and do not constitute undue limitations to the present application.
1 is a schematic diagram of the structure of a magnetic levitation type gravity compensation device according to a first embodiment of the present application. FIG. 2 is a cross-sectional view taken along the axial direction of FIG. 1 . FIG. 13 is a schematic diagram of a structure in which magnetic flux lines in an arc plate are arranged along a radial direction. FIG. 13 is a structural schematic diagram in which the magnetic flux lines in the arc plate are arranged in parallel. 1 is an output force graph of a flexible mechanism. 1 is a graph of the output force of a magnetic levitation gravity compensator within a linear stroke range when the outer coil current is zero. 1 is a graph showing the output force of the magnetic levitation type gravity compensation device within a linear stroke range in the first embodiment of the present application. FIG. 11 is a structural schematic diagram of a magnetic levitation type gravity compensation device according to a second embodiment of the present invention. FIG. 7 is a cross-sectional view taken along the axial direction of FIG. 6 . FIG. 13 is a schematic diagram of a structure in which magnetic flux lines in a circular arc plate are provided along a radial direction. FIG. 13 is a schematic diagram of a structure in which magnetic flux lines in a circular arc plate are arranged in parallel. FIG. 11 is a magnetic flux diagram when an outer coil in the second embodiment of the present invention is not energized. FIG. 11 is a structural schematic diagram of a magnetic levitation type gravity compensation device according to a third embodiment of the present invention. FIG. 11 is a structural schematic diagram of a magnetic levitation type gravity compensation device according to a fourth embodiment of the present invention. FIG. 13 is a cross-sectional view taken along the axial direction of FIG. 12 . FIG. 11 is a magnetic flux diagram when neither the inner coil nor the outer coil is energized in the fourth embodiment of the present invention. FIG. 11 is a magnetic flux diagram when current is applied to the inner coil and not to the outer coil in the fourth embodiment of the present invention. 1 is a schematic diagram of the structure of a fine movement stage according to the present application. FIG. 2 is a structural schematic diagram of a flexible mechanism in the present application. 1 is a schematic diagram of the structure of a fine movement stage when the number of magnetic levitation gravity compensation devices in the present application is different, where the above drawings include the following reference numerals: 1...inner base magnet, 11...inner ring, 12...inner coil, 2...first end magnetic steel, 3...second end magnetic steel, 4...inner magnet ring magnetic steel, 41...arc plate, 5...outer coil, 6...stage, 7...flexible mechanism, 71...elastic sheet, 8...outer magnet ring magnetic steel, 81...arc plate, 10...outer guide magnet ring, 100...magnetic levitation gravity compensation device, 101...first frame, 102...second frame, 103...rotation base, 104...fine movement base.

In the following, in order to clarify the objectives, technical solutions and advantages of the embodiments of the present application, each embodiment of the present application will be described in detail with reference to the drawings. However, as will be understood by those skilled in the art, many technical details are provided in each embodiment of the present application to allow the reader to better understand the present application. However, the technical solutions described in the claims of the present application can be realized without these technical details and the various changes and modifications made in each of the following embodiments.

In the following description, specific details are set forth for the purpose of describing various disclosed embodiments to provide a thorough understanding of the various disclosed embodiments. However, one of ordinary skill in the art will recognize that an embodiment may be practiced without one or more of these specific details. In other circumstances, well-known devices, structures, and techniques related to the present application may not be shown or described in detail to avoid unnecessarily confusing the description of the embodiments.

Unless otherwise required, throughout the specification and claims, the term "comprises" and variations thereof, such as "contains" and "having," should be understood to be openly inclusive, i.e., to be interpreted as "including, but not limited to."
The following describes in detail each embodiment of the present application with reference to the drawings, in order to make the objectives, features and advantages of the present application more clearly understood. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present application, but are intended to describe the substantial spirit of the technical solution of the present application.

Throughout the specification, a reference to "one embodiment" or "one embodiment" means that a particular feature, structure, or characteristic described in the embodiment is included in at least one embodiment. Thus, the occurrences of "one embodiment" or "one embodiment" in various locations throughout the specification do not necessarily all refer to the same embodiment. Also, particular features, structures, or characteristics may be combined in any manner in one or more embodiments.

As used in the specification and claims, the singular forms "a,""an," and "the" include plural referents unless expressly stated otherwise. Additionally, the term "or" is generally used in its sense including "and/or" unless expressly stated otherwise.
In the following description, in order to clearly show the structure and operation method of the present application, many directional terms are used, but terms such as "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", and "down" should be understood as convenient terms and should not be understood as limiting terms. In addition, in each of the following drawings, the direction along the coordinate axis Z (first direction Z) is the axial direction of the magnetic levitation gravity compensation device, that is, the vertical direction, and all of these directional terms are convenient terms and should not be understood as limiting terms. Here, "X direction", "X direction", "Y direction", and "Y direction" mean a direction intersecting the horizontal direction, and "Z direction" and "Z direction" mean a vertical direction.
In the following figures, the arrow "→" indicates the magnetization direction, and "x" indicates the coil cross section.

Hereinafter, the magnetic levitation type gravity compensation device of the first embodiment of the present application will be described with reference to the drawings. As shown in FIG. 1 and FIG. 2, the magnetic levitation type gravity compensation device 100 includes an inner base magnet 1, a first end magnetic steel 2, a second end magnetic steel 3, an inner magnet ring magnetic steel 4, and an outer coil 5. Here, the inner base magnet 1 is cylindrical and extends along the axial direction, and the inner base magnet 1 is a permanent magnet. The first end magnetic steel 2 and the second end magnetic steel 3 are located at the two axial ends of the inner base magnet 1, respectively, and extend along the axial direction, and the outer diameters of the first end magnetic steel 2 and the second end magnetic steel 3 gradually increase along the direction away from the two axial ends of the inner base magnet 1, respectively. The inner magnet ring magnetic steel 4 is cylindrical, and the inner magnet ring magnetic steel 4 is located outside the inner base magnet 1 coaxially with the inner base magnet 1, and is radially separated from the inner base magnet 1. The outer coil 5 is coaxial with the inner base magnet 1 and located outside the inner magnet ring magnetic steel 4, and the outer coil 5 is radially spaced apart from the inner magnet ring magnetic steel 4. The outer coil 5 is usually equipped with a power amplifier, so that the magnetic field generated by the outer coil 5 can be adjusted by adjusting the current in the outer coil 5. The outer coil 5 is fixed to the inner base magnet 1, the first end magnetic steel 2, and the second end magnetic steel 3, i.e., the outer coil 5 and the first end magnetic steel 2 or the second end magnetic steel 3 are fixedly connected by a bracket or other structure. The inner base magnet 1, the first end magnetic steel 2, the second end magnetic steel 3, and the outer coil 5 together constitute a first frame 101, and the first frame 101 and the inner magnet ring magnetic steel 4 interact magnetically with each other, so that they can move axially with each other. The first frame 101 may be a mover and the inner magnet ring magnetic steel 4 may be a stator, or the inner magnet ring magnetic steel 4 may be a mover and the first frame 101 may be a stator. When the first frame 101 is the mover, it is supported by the first frame 101 to drive and move the stage device, and when the inner magnet ring magnetic steel 4 is the mover, it is supported by the inner magnet ring magnetic steel 4 to drive and move the stage device. Below, the magnetic levitation gravity compensation device 100 of the present application will be described using the case where the first frame 101 is the mover as an example, and the stroke or displacement of the magnetic levitation gravity compensation device 100 described below is the displacement of the first frame 101 relative to the inner magnet ring magnetic steel 4 along the first direction (Z).

The magnetic levitation gravity compensation device 100 in the present application can be applied in a fine movement stage. Generally speaking, the fine movement stage includes a stage device, a flexible mechanism 7, a fine movement base 104, and the magnetic levitation gravity compensation device 100 in the above embodiment, and the stage device is connected to the fine movement base 104 so as to be slidable vertically relative to the fine movement base 104. As shown in Figures 15a and 15b, one end of the flexible mechanism 7 is connected to the stage device and the other end is connected to the fine movement base 104, and the magnetic levitation gravity compensation device 100 is located below the stage device and is configured to be able to force compensate for the gravity of the stage device.

Specifically, as shown in Figs. 15a and 15b, the stage device includes a stage 6 and a rotating base 103 provided below the stage 6. Here, the stage 6 is used to adsorb the silicon wafer, and vacuum adsorption, electrostatic adsorption, etc. may be used. The flexible mechanism 7 includes a plurality of elastic sheets 71, which extend horizontally in the radial direction between the fine movement base 104 and the rotating base 103, and are fixedly connected at both ends to the fine movement base 104 and the rotating base 103, respectively. Specifically, the radially inner end of the flexible mechanism 7 is connected to the rotating base 103, and the radially outer end is connected to the fine movement base 104.

As shown in Figs. 1 and 2, the first end magnetic steel 2 and the second end magnetic steel 3 are in the shape of a truncated cone with an axial through hole, but as can be understood, the first end magnetic steel 2 and the second end magnetic steel 3 may be of solid structure without departing from the scope of the present application. The size of the outer diameter of each of the first end magnetic steel 2 and the second end magnetic steel 3 gradually increases from the side close to the two axial ends of the inner base magnet 1 toward the bottom and the top. The first end magnetic steel 2 and the second end magnetic steel 3 are each provided with an axial through hole, which is coaxial with the axial through hole of the inner base magnet 1 and has the same diameter and communicates with each other. The first end magnetic steel 2 and the second end magnetic steel 3 have the same shape and size, and are mirror images of each other with respect to the central radial plane of the inner base magnet 1. The inner magnet ring magnetic steel 4 is cylindrical, coaxial with the inner base magnet 1, located outside the inner base magnet 1, and radially spaced from the inner base magnet 1. In the embodiment shown, the first end magnetic steel 2 and the second end magnetic steel 3 are adjacent to the inner base magnet 1, but there may be some air gap between them, typically 1 mm or less.

The magnetic levitation type gravity compensation device 100 in this embodiment has both the functions of vertical compensation and vertical drive described below.
As shown in Fig. 2 and Fig. 15a, there is no mechanical connection between the first frame 101 and the inner magnet ring magnetic steel 4, the rigidity of the flexible mechanism 7 is constant within the linear stroke range, and the interaction between the first frame 101 and the inner magnet ring magnetic steel 4 can generate a vertical biasing force with no change in rigidity. Here, if the inner magnet ring magnetic steel 4 and the inner base magnet 1 are positioned in the center of each other's axial direction, it is the device zero point, and when the device is positioned at the zero point, it is necessary to compensate for the gravity of the stage device, so its external output magnetic levitation force must be equal to the gravity of the stage device. At this time, the elastic force of the flexible mechanism 7 is zero, the outer coil 5 is not energized, and the direction of the output magnetic levitation force of the magnetic levitation gravity compensation device 100 is vertical and upward. Since the elastic force of the flexible mechanism 7 provided between the stage device and the base changes linearly with the vertical movement of the stage device within the linear stroke range, the output magnetic levitation force of the magnetic levitation gravity compensation device 100 also changes linearly with the vertical movement of the stage device, and only when the gradients of the two changes are equal can the magnetic levitation gravity compensation device 100 fully realize the compensation action for the gravity of the stage device and the elastic force of the flexible mechanism 7. Based on this, the outer diameter sizes of the first end magnetic steel 2 and the second end magnetic steel 3 in the device gradually increase downward and upward respectively from the sides close to both ends of the inner base magnet 1, and when the stage device is within the linear stroke range, the output magnetic levitation force of the magnetic levitation gravity compensation device 100 is equal to the sum of the output elastic force of the flexible mechanism 7 and the gravity of the stage device.

Figure 5b shows an output force simulation curve within the linear stroke range when the current in the outer coil 5 of the magnetic levitation gravity compensation device 100 is zero. In the figure, the horizontal axis indicates the stroke of the magnetic levitation gravity compensation device 100, and the vertical axis indicates the output force. The figure shows two reverse displacement end points, a zero point, and their corresponding output forces. In the figure, x and -x are the limit displacement in one direction, G is the gravity of the stage device that a single magnetic levitation gravity compensation device 100 should compensate for, and G+F and -F+G are the output forces at the linear stroke range end points of a single magnetic levitation gravity compensation device 100. If the design rigidity of the magnetic levitation gravity compensation device 100 is k, the output force amplitude of the magnetic levitation gravity compensation device 100 at the forward stroke end point x is G+F=G+kx, and it can be seen that the output force range of the magnetic levitation gravity compensation device 100 is "-F+G, F+G". As can be seen from the figure, the output force of the magnetic levitation gravity compensation device 100 changes linearly with the stroke, thereby compensating for the gravity of the stage device and the linearly changing elastic force generated by the flexible mechanism 7.

As described above, within the linear stroke range, when the current in the outer coil 5 is zero, the magnetic levitation gravity compensation device 100 has a vertical compensation effect, can compensate for the gravity of the stage device and the elastic force of the flexible mechanism 7, and has constant rigidity characteristics.

The magnetic levitation gravity compensation device 100 can be applied in a larger stroke range than in the linear stroke range. The difference between the linear stroke range and the large stroke range is that the stiffness of the flexible mechanism 7 is constant within the linear stroke range, but the large stroke range includes the linear stroke range and a non-linear stroke range that exceeds the linear stroke range, and the stiffness of the flexible mechanism 7 is not constant within the non-linear stroke range. Also, as shown in FIG. 5a, the horizontal axis in the figure is the displacement of the magnetic levitation gravity compensation device 100 along the first direction (Z), and the vertical axis is the output force of the flexible mechanism 7 along the first direction (Z). As can be seen from the figure, in the linear region A (i.e., the linear stroke range) within the stroke range displaced in the first direction, the output stiffness of the flexible mechanism 7 is constant, and its elastic force and displacement change linearly; however, when the magnetic levitation gravity compensation device 100 moves outside of that region, i.e., in the non-linear region B within the stroke range, the output stiffness of the flexible mechanism 7 changes according to the displacement, and its elastic force and displacement also change non-linearly, but the force compensated by the first end magnetic steel 2 and the second end magnetic steel 3 always changes linearly; when moving in the non-linear region, the first end magnetic steel 2 and the second end magnetic steel 3 can still only perform linear compensation, causing some of the elastic force of the flexible mechanism 7 to be uncompensated; at this time, by controlling the direction and amplitude of the current in the outer coil 5, a Lorentz force of the corresponding direction and magnitude can be generated to compensate for the elastic force of the part not compensated by the first end magnetic steel 2 and the second end magnetic steel 3. Therefore, the magnetic levitation gravity compensation device 100 has a vertical compensation effect even in the non-linear region B.

Combining the above linear stroke range and non-linear stroke range, the output force of the magnetic levitation gravity compensation device 100 is used to compensate for the gravity of the stage device and the elastic force of the flexible mechanism 7. When the first frame 101 of the magnetic levitation gravity compensation device 100 is displaced within the stroke range of the linear region A along the first direction (Z) relative to the inner magnet ring magnetic steel 4, the output elastic force of the flexible mechanism 7 changes linearly. When the current in the outer coil 5 is zero, the outer diameter sizes of the first end magnetic steel 2 and the second end magnetic steel 3 both gradually increase downward and upward from the sides close to both axial ends of the inner base magnet 1, respectively, so that the change gradient of the outer diameter size of the first end magnetic steel 2 and the second end magnetic steel 3 is consistent with the change gradient of the output elastic force of the flexible mechanism 7. In the linear region A, the output magnetic levitation force of the magnetic levitation gravity compensation device 100 is equal to the sum of the output elastic force of the flexible mechanism 7 and the gravity of the stage device.

In the non-linear region, the output force of the flexible mechanism 7 exhibits a non-linear change, but when the current in the outer coil 5 is zero, the output magnetic levitation force of the magnetic levitation gravity compensation device 100 still exhibits a linear change, so the output magnetic levitation force of the magnetic levitation gravity compensation device 100 is not equal to the sum of the output elastic force amplitude of the flexible mechanism 7 and the gravity of the stage device. In this case, a current can be passed through the outer coil 5, and the output force of the magnetic levitation gravity compensation device 100 is adjusted by the axial magnetic field generated in the outer coil 5. When the first frame 101 is displaced within a stroke range that is in the non-linear region relative to the inner magnet ring magnetic steel 4, the output magnetic levitation force of the magnetic levitation gravity compensation device 100 is still equal to the sum of the output elastic force of the flexible mechanism 7 and the gravity of the stage device.

Therefore, specifically, the magnetic levitation gravity compensation device 100 of the present application is a gravity compensation device with constant stiffness within the linear stroke range, and is a highly integrated device capable of adjusting the output force within a large stroke range including the linear stroke range and the non-linear stroke range. That is, within the linear stroke range of the fine stage vertical movement module, when the current of the outer coil 5 is zero, the output force of the magnetic levitation gravity compensation device 100 can compensate for the gravity of the stage device and the elastic force in the linear region of the flexible mechanism 7. By adjusting the magnitude and direction of the current of the outer coil 5 within the large stroke range, the interaction force between the first frame 101 and the inner magnet ring magnetic steel 4 can be adjusted, the output force of the magnetic levitation gravity compensation device 100 can be adjusted, and a compensation force in the non-linear region of the flexible mechanism 7 can be provided.

Within the linear stroke range, the vertical compensation action of the magnetic levitation gravity compensation device 100 of this embodiment has another feature, as shown in FIG. 5c, in which the horizontal axis is the displacement of the first frame 101 in the magnetic levitation gravity compensation device 100 along the first direction (Z), and the vertical axis is the output force of the magnetic levitation gravity compensation device 100 along the first direction (Z). The five curves in the figure correspond to the output force curves of the magnetic levitation gravity compensation device 100 under working conditions with different input currents to the outer coil 5.

It should be noted that in FIG. 5c, the current in the outer coil 5 is constant, but in practical situations, when the magnetic levitation gravity compensation device 100 is in a large stroke range, the magnitude of the current needs to be adjusted stepwise as necessary to compensate for the elastic force of the flexible mechanism 7.
As can be seen from Figures 5c and 16, the preset input currents of the outer coil 5 are -2A, -1A, 0A, 1A and 2A, respectively, and the output forces corresponding to the magnetic levitation gravity compensation device 100 at the zero point are m5, m4, m1, m2 and m3, respectively; when the input current is 0A, the output force is an acting force m1 along the first direction, and the product of the output force and the number of magnetic levitation gravity compensation devices 100 in the fine movement stage is the gravity of the stage device.

When the inner magnet ring magnetic steel 4 and the inner base magnet 1 are positioned in the center of each other's axial direction, it is the zero point of the device. When the current of the outer coil 5 is zero, the output force of the magnetic levitation gravity compensation device 100 is equal in magnitude to the gravity of the stage device and opposite in direction. When the magnetic levitation gravity compensation device 100 is unable to completely compensate for the gravity of the stage device or the compensation force exceeds the gravity of the stage device at the zero point, the output force of the magnetic levitation gravity compensation device 100 can be adjusted by changing the magnitude of the current in the outer coil 5, and the output force can be adjusted to match the gravity of the stage device. In addition, the linearity of each output curve in the figure is good (i.e., all show constant rigidity), and the tapered first end magnetic steel 2 and second end magnetic steel 3 are used to realize the linearization of the magnetic field, and the interaction between the magnetic field of the first frame 101 and the magnetic field of the inner magnet ring magnetic steel 4 is applied to realize the gravity compensation means of the stage device at the zero point.

Therefore, the present application not only compensates for the gravity of the stage device, but also allows adjustments based on the gravity of the stage device, and the operator can maintain balance at the zero point for the entire device by simply changing the current in the outer coil 5, greatly improving production efficiency and the stability of the fine movement stage. Furthermore, by adopting the above method, the structure of the magnetic levitation gravity compensation device 100 can be made more compact, saving design space and achieving a very high degree of integration.

Note that while the diagram shown in Figure 5c above is a diagram when the current in the outer coil 5 is a constant value, in actual situations, when the flexible mechanism 7 is in a non-linear region, the current in the outer coil 5 needs to change based on the change in the elastic force of the flexible mechanism 7, so that the output force of the magnetic levitation gravity compensation device 100 can fully compensate for the gravity of the stage device and the elastic force of the flexible mechanism 7.

The magnetic levitation gravity compensation device 100 in this embodiment has a vertical drive function in addition to the above-mentioned vertical compensation function. As can be seen from FIG. 5c, when different currents are input to the outer coil 5, the magnetic levitation gravity compensation device 100 has different output forces. Similarly, by controlling the current direction and amplitude of the outer coil 5, the movement direction and acceleration of the stage device can be controlled, thereby achieving a vertical drive function.

Within the linear stroke range, the magnetic levitation gravity compensation device 100 has a constant rigidity characteristic, and the magnetic levitation gravity compensation device 100 can always compensate for the gravity of the stage device and the elastic force of the flexible mechanism 7. When in the initial zero point position, regardless of whether a constant current flows through the outer coil 5, the acceleration force required for the movement of the stage device can be provided by simply changing the current direction and amplitude in the outer coil 5, allowing the stage device to react quickly, for example to accelerate or decelerate quickly, and simultaneously fulfilling the roles of vertical compensation and vertical drive. Moreover, this control reduces the current in the coil part, so the temperature rise is low and the stage device can meet the application requirements of high dynamic response.

In a large stroke range, the outer coil 5 needs to constantly change the current direction and amplitude to compensate for the non-linear elastic force of some flexible mechanism 7, and then the current direction and amplitude in the outer coil 5 can be further changed by calculation to still provide the acceleration force required for the movement of the stage device.
As described above, the magnetic levitation gravity compensation device 100 not only has a vertical compensation function, but also has a vertical driving function. Therefore, when applied to a fine stage, there is no need to install a separate vertical driving device, which saves the design space of the fine stage, makes the structure of the fine stage more compact, and has a very high degree of integration. In this application, the outer coil 5 only needs to provide the axial acceleration force required for the movement of the stage device and the compensation force in the non-linear region of the flexible mechanism 7, so the current in the coil part is small and the temperature rise is low, so that the stage device can meet the application requirements of high dynamic response, such as rapid acceleration or deceleration. And, since the magnetic levitation gravity compensation device 100 in this application has a compact structure, it can save the design space of the stage device and has a very high degree of integration.

In addition, since the outer coil 5 is provided, as shown in FIG. 5a, it is possible to realize the action of compensating for the gravity of the stage device and the elastic force of the flexible mechanism 7 even when the magnetic levitation gravity is within a large stroke range. Also, since the outer coil 5 is added, if the inner magnet ring magnetic steel 4 and the inner base magnet 1 are positioned in the center of each other's axial direction, it becomes the device zero point, and the weight of the stage device can be compensated for auxiliarily by adjusting the magnitude of the current in the outer coil 5.

Also, as shown in Figures 2 to 4, specifically, in this embodiment, the magnetization direction of the first end magnetic steel 2 and the second end magnetic steel 3 is outward from the inner base magnet 1 along the axial direction, and the magnetization direction of the inner base magnet 1 may be the same as either the first end magnetic steel 2 or the second end magnetic steel 3, and in this embodiment, the magnetization direction of the inner base magnet 1 is the same as the first end magnetic steel 2, and the magnetization direction of the inner magnet ring magnetic steel 4 is outward along the radial direction. The magnetic field by the outer coil 5 can be adjusted as needed. Of course, in some embodiments, the magnetization direction of the first end magnetic steel 2 and the second end magnetic steel 3 may be in a direction from the outside toward the inner base magnet 1 along the axial direction, that is, opposite to the outward direction from the inner base magnet 1 along the axial direction, and the magnetization direction of the inner magnet ring magnetic steel 4 may also be set radially inward accordingly.

In some embodiments, as shown in Figures 1, 3 and 4, the inner magnet ring magnetic steel 4 is composed of a number of arc plates 41 adjacent to each other along the circumferential direction, and the magnetization direction of each arc plate 41 is arranged along the radial direction of the inner magnet ring magnetic steel 4 as shown in Figure 3, i.e., the magnetization directions at different circumferential positions in the arc plate 41 are all along the radial direction, or as shown in Figure 4, the magnetization direction of the arc plate 41 is parallel to the radial direction of the circumferential center of the arc plate 41, i.e., each magnetic flux line of the arc plate 41 is arranged in parallel and is parallel to the circumferential symmetry plane of the arc plate 41. When each magnetic flux line in the arc plate 41 is parallel, each arc plate 41 is easy to magnetize. The magnetization can be completed by simply placing the arc plate 41 in a parallel magnetic field.

As shown in FIG. 1, the inner magnet ring magnetic steel 4 is made of eight blocked magnetic steel pieces joined together. Here, the eight blocked magnetic steel pieces are arc plates 41 divided into eight equal parts along the radial direction at equal intervals of 45° by a cylinder. However, the inner magnet ring magnetic steel 4 may be joined with other numbers of blocked magnetic steel pieces, and the number of blocks N is set to an even number, for example, 2 blocks, 4 blocks, 6 blocks, etc., in order to eliminate the radial unbalanced force generated by the inner magnet ring magnetic steel 4. The inner magnet ring magnetic steel 4 is made of blocked magnetic steel pieces joined together to facilitate magnetization and processing of the magnetic steel. Of course, in some embodiments, the inner magnet ring magnetic steel 4 may be an integral magnetic ring.

The second embodiment of the present application provides a magnetic levitation type gravity compensation device 100, which is basically the same as the first embodiment, with the difference being that, as shown in Figures 6 and 7, the magnetic levitation type gravity compensation device 100 in this embodiment may further include an outer magnet ring magnetic steel 8, which is arranged coaxially with the inner magnet ring magnetic steel 4, located outside the outer coil 5, and spaced apart from the outer coil 5 in the radial direction. The magnetization direction of the outer magnet ring magnetic steel 8 is the same as that of the inner magnet ring magnetic steel 4, i.e., the magnetization direction of the outer magnet ring magnetic steel 8 may be radially outward or radially inward.

The outer magnet ring magnetic steel 8 and the inner magnet ring magnetic steel 4 are fixed relative to each other, and the outer magnet ring magnetic steel 8 and the inner magnet ring magnetic steel 4 may be fixed together by a device such as a bracket or a connecting rod, that is, the outer magnet ring magnetic steel 8 and the inner magnet ring magnetic steel 4 together form a second frame 102, which may be a stator or a mover, and a mutual magnetic force is generated between the second frame 102 and the first frame 101 to move relative to each other, and either the first frame 101 or the second frame 102 is a mover and the other is a stator.

In the magnetic levitation gravity compensation device 100 of the present application, there is no mechanical connection between the first frame 101 and the second frame 102, and within the stroke range, a magnetic levitation force of a constant magnitude can be generated vertically upward by interaction between the magnetic field generated by the inner base magnet 1, the first end magnetic steel 2, and the second end magnetic steel 3 in the first frame 101 and the inner magnet ring magnetic steel 4 and the outer magnet ring magnetic steel 8 in the second frame 102, and the magnetic levitation force is generated vertically upward by interaction between the magnetic field generated by the inner magnet ring magnetic steel 4 and the outer magnet ring magnetic steel 8 in the second frame 102 ... The force is equal to but opposite to the force of gravity, and the outer taper of the first end magnetic steel 2 and the second end magnetic steel 3 in the first frame 101 linearizes the output magnetic force of the first frame 101, and the interaction between the magnetic field of the inner base magnet 1, the first end magnetic steel 2, and the second end magnetic steel 3 and the inner magnet ring magnetic steel 4 and the outer magnet ring magnetic steel 8 in the second frame 102 is vertically upward and generates a magnetic levitation force with constant stiffness, and by superimposing the two forces, a vertical magnetic levitation force with constant output stiffness can be realized.

The outer coil 5 is usually equipped with a power amplifier to adjust the current input of the outer coil 5. According to the Lorentz force law, the magnetic field generates a Lorentz force on the moving charge, the outer coil 5 is arranged between the inner magnet ring magnetic steel 4 and the outer magnet ring magnetic steel 8 along the radial direction. By adjusting the direction and amplitude of the input current of the outer coil 5 in the first frame 101, different Lorentz forces are generated in the magnetic field interaction between the outer coil 5 and the second frame 102, and the Lorentz force can relatively displace the first frame 101 and the second frame 102 according to a preset trajectory. At this time, the outer coil 5 does not need to overcome the gravity of the stage device, and only the acceleration force required for movement and the elastic force of the flexible mechanism 7 provide a compensation force that exceeds the interference force of the linear part in the non-linear region. Therefore, the current of the magnetic levitation gravity compensation device 100 is small, the temperature rise is low, and the stage device can meet the application requirements of high dynamic response.

Also, as shown in Figures 6, 8 and 9, the outer magnet ring magnetic steel 8 may be composed of a plurality of arc plates 81 adjacent to each other in the circumferential direction, or in some embodiments, the outer magnet ring magnetic steel 8 may be one complete magnet ring, and the magnetization direction of each arc plate 81 is arranged along the radial direction of the outer magnet ring magnetic steel 8 as shown in Figure 8, or the magnetization direction of the arc plate 81 is parallel to the radial direction of the circumferential center of the arc plate 81 as shown in Figure 9. That is, each magnetic flux line of the arc plate 81 may be arranged along the radial direction of the outer magnet ring magnetic steel 8, or each magnetic flux line of the arc plate 81 is arranged in parallel and is parallel to the circumferential symmetric plane of the arc plate 41. When each magnetic flux line is parallel, each arc plate 81 is easy to magnetize. Magnetization can be completed by simply placing the arc plate 81 in a parallel magnetic field.

As shown in FIG. 6, the outer magnet ring magnetic steel 8 is made of eight blocked magnetic steel pieces joined together. Here, the eight blocked magnetic steel pieces are arc plates 81 magnetic steel pieces obtained by dividing a cylinder into eight equal parts along the radial direction at equal angular intervals of 45°. However, the outer magnet ring magnetic steel 8 may be made of other numbers of blocked magnetic steel pieces joined together, and the number of blocks N is set to an even number, for example, 2 blocks, 4 blocks, 6 blocks, etc., in order to eliminate the radial unbalanced force generated by the outer magnet ring magnetic steel 8. The outer magnet ring magnetic steel 8 is made of blocked magnetic steel pieces joined together to facilitate magnetization and processing of the magnetic steel.

The magnetic flux lines in this embodiment are shown in FIG. 10, which shows a part of the schematic axial cross-sectional view of FIG. 6, and in the figure, the running direction of the magnetic flux lines almost coincides with the designed magnetic circuit.
The third embodiment of the present application provides a magnetic levitation gravity compensation device 100, which is almost the same as the first embodiment, and the main difference is that, as shown in FIG. 11, the magnetic levitation gravity compensation device 100 in this embodiment further includes an outer guide magnet ring 10 located outside the outer coil 5 coaxially with the inner magnet ring magnetic steel 4 and radially spaced from the outer coil 5. The outer guide magnet ring 10 is made of a magnetically permeable material such as iron or a highly magnetically permeable (Fe 2 Si 3 B) 98 (Cu 2 Nb) 2 amorphous alloy. The outer guide magnet ring 10 can reinforce the magnetic field generated by the entire magnetic levitation gravity compensation device 100.

Furthermore, the outer guide magnet ring 10 is made up of a plurality of arc plates adjacent to each other in the circumferential direction, but it may of course be an integral circular ring.
The fourth embodiment of the present application provides a magnetic levitation gravity compensation device 100, which is basically the same as the second embodiment, with the main difference being that in the second embodiment, the inner base magnet 1 is a permanent magnet, while in the present embodiment, the inner base magnet 1 is an inner coil 12, as shown in Figs. 12 and 13. Of course, in order to fix the inner coil 12, the inner coil 12 may be wound around the inner ring 11 along the axis of the inner ring 11, and the inner ring 11 may be made of a general material, or may be a permeable body or a permanent magnet. The first end magnetic steel 2 and the second end magnetic steel 3 are provided at both ends of the inner ring 11 in the axial direction. When the inner ring 11 is made of a permanent magnet, the permanent magnet and the inner coil 12 together constitute the inner base magnet 1, and together with the first end magnetic steel 2 and the second end magnetic steel 3, form a first frame 101, which interacts with the second frame 102 to generate a magnetic levitation force. In addition, the inner coil 12 may be fixed in other manners as long as it is located between the first end magnetic steel 2 and the second end magnetic steel 3 and its conductor is wound circumferentially around the axis, and the current direction in the inner coil 12 may be adjusted as necessary. As shown in FIG. 13, when current is applied to the inner coil 12, the magnetic force direction of the inner coil 12 is upward along the axis, and in some embodiments, when the current direction of the inner coil 12 is reversed, the magnetic force direction of the inner coil 12 is downward along the axis.

A power amplifier is usually placed in the inner coil 12 to adjust the input of the inner coil 12, and according to the right-hand rule, the direction and amplitude of the input current of the inner coil 12 in the first frame 101 can be adjusted to match the gravity of stage devices of different weights, thereby improving the application range of the magnetic levitation gravity compensation device 100.
When the current in the outer coil 5 is zero, the magnetic force generated by the magnetic levitation gravity compensation device 100 compensates for the gravity of the stage device and the elastic force of the flexible mechanism 7, and by adjusting the direction and amplitude of the current in the outer coil 5, the magnetic levitation gravity compensation device 100 is moved at high acceleration along a preset trajectory, thereby improving the movement performance of the stage device along the first direction (Z).

The magnetic flux lines corresponding to this embodiment of the structure are shown in Figures 14a and 14b, which show a portion of the schematic axial cross-sectional view of Figure 13. Figure 14a is a magnetic flux line diagram when current is applied to the inner coil 12 and not to the outer coil 5, and Figure 14b is a magnetic flux line diagram when current is not applied to the inner coil 12 and not to the outer coil 5. As can be seen from the figures, the magnetic flux lines are mirror symmetric along the first plane (XoY).

Although the preferred embodiment of the present application has been described in detail above, it will be understood that aspects of the embodiment may be modified, if necessary, to provide other embodiments by utilizing aspects, features and concepts of each patent, application and publication.
These and other changes can be made to the embodiments in light of the above detailed description. In general, in the claims, the terms used should be understood not to be limited to the specific embodiments disclosed in the description and claims, but to include all possible embodiments and all equivalents to which these claims may be entitled.

In addition, the details of the related technologies and the technical effects that can be achieved mentioned in each of the above embodiments are still valid in other embodiments, and in order to reduce duplication, the description will be omitted in some embodiments.
The present application further provides a fine-motion stage, as shown in Figures 15a to 16, the fine-motion stage includes a stage device, a flexible mechanism 7, a fine-motion base 104, and a magnetic levitation type gravity compensation device 100 in any of the above-mentioned embodiments, wherein the stage device is connected to the fine-motion base 104 so as to be slidable vertically relative to the fine-motion base 104, the flexible mechanism 7 includes a plurality of elastic sheets 71, the elastic sheets 71 extend in a horizontal radial direction, and the radial inner end of the elastic sheets 71 is connected to the stage device, and the radial outer end of the elastic sheets 71 is connected to the fine-motion base 104, and the magnetic levitation type gravity compensation device 100 is positioned below the stage device and is configured to be able to force compensate the stage device, Specifically, the inner base magnet 1, the first end magnetic steel 2, the second end magnetic steel 3 and the outer coil 5 are incorporated into one of the stator and the mover, the inner magnet ring magnetic steel 4 is the other of the stator and the mover, the magnetic levitation gravity compensation device 100 is located below the stage device, and the magnetic levitation gravity mover supports the stage device.

Specifically, the stage device includes a stage 6 and a rotating base 103 provided below the stage 6, and the flexible mechanism 7 extends radially between the fine-motion base 104 and the rotating base 103 and is fixedly connected at both ends to the fine-motion base 104 and the rotating base 103. Specifically, the radially inner end of the flexible mechanism 7 is connected to the rotating base 103, and the radially outer end is connected to the fine-motion base 104.

Also, as shown in FIG. 15b, the flexible mechanism 7 includes a plurality of elastic sheets 71, each of which is arranged around the center of the stage device on the outer periphery of the stage device, and the radial outer side of each elastic sheet 71 is connected to other members of the fine movement stage, and there are a plurality of magnetic levitation gravity compensation devices 100, each of which is arranged in parallel and spaced apart from each other. Of course, in some embodiments, there may be only one magnetic levitation gravity compensation device 100.

Figure 16 shows a bottom view of a stage device using the magnetic levitation type gravity compensation device 100 according to the present application. A cavity is provided below the stage device and is used to accommodate the magnetic levitation type gravity compensation device 100 according to the present application. Here, the number of cavities below the stage device may be one, two, three, or four. The figure shows a schematic diagram in which one magnetic levitation type gravity compensation device 100 is arranged at the center point, two magnetic levitation type gravity compensation devices 100 are arranged in parallel, three magnetic levitation type gravity compensation devices 100 are arranged, for example, in an equilateral triangle, and four magnetic levitation type gravity compensation devices 100 are arranged in a square, but other numbers and arrangements of magnetic levitation type gravity compensation devices 100 may be provided. The shape of the work table using the magnetic levitation type gravity compensation device 100 is not limited to the square shown in the figure, and may be set to any shape as necessary. It should be understood that the perpendicular line on which the equivalent center of gravity of the multiple magnetic levitation gravity compensation devices 100 is located must be collinear with the perpendicular line on which the center of gravity of the vertical movement mechanism is located.

As shown in FIG. 16, the magnetic levitation type gravity compensation device 100 of the present application can provide a magnetic levitation force that changes linearly with the stroke, that is, it can not only compensate for the gravity of the stage device, but also compensate for the elastic force generated by the flexible mechanism 7, and in some cases, can meet the requirements for gravity compensation of the fine movement stage. In addition, since the outer coil 5 only needs to provide the acceleration driving force required for the movement of the stage device and the compensation force in the variable stiffness region of the flexible mechanism, the current in the coil part is small and the temperature rise is low, so that the stage device can meet the application requirements of high dynamic response. Furthermore, the magnetic levitation type gravity compensation device 100 of the present application has a compact structure, which can save design space of the stage device and has a very high degree of integration.

In addition, for the structure and connection relationships of other members in the fine movement stage, reference can be made to the description in the application with publication number CN112259488B, which is incorporated herein by reference.
As can be understood by those skilled in the art, the above embodiments are specific examples for implementing the present application, and in practical applications, various changes in form and details may be made thereto without departing from the spirit and scope of the present application.

Claims (10)

an inner base magnet extending along an axial direction;
a first end magnetic steel and a second end magnetic steel respectively located at two axial ends of the inner base magnet and extending along the axial direction, the first end magnetic steel and the second end magnetic steel respectively having an outer diameter gradually increasing along a direction away from the two axial ends of the inner base magnet;
an inner magnet ring magnetic steel having a cylindrical shape, positioned outside the inner base magnet coaxially with the inner base magnet and radially spaced from the inner base magnet;
and an outer coil located coaxially with the inner base magnet and outside the inner magnet ring magnetic steel, the outer coil being radially spaced apart from the inner magnet ring magnetic steel and fixed relative to the inner base magnet, the first end magnetic steel, and the second end magnetic steel. The magnetic levitation gravity compensation device according to claim 1, characterized in that the magnetization direction of the inner base magnet is axial, the magnetization direction of the first end magnetic steel and the second end magnetic steel is outward from the inner base magnet along the axial direction, and the magnetization direction of the inner magnet ring magnetic steel is from inside the ring to outside the ring of the inner magnet ring magnetic steel. The magnetic levitation gravity compensation device according to claim 1, characterized in that the magnetization direction of the inner base magnet is axial, the magnetization directions of the first end magnetic steel and the second end magnetic steel are axially directed from the outside toward the inner base magnet, and the magnetization direction of the inner magnet ring magnetic steel is directed from the outside of the inner magnet ring magnetic steel toward the inside of the ring. an outer magnet ring magnetic steel located outside the outer coil and coaxial with the inner magnet ring magnetic steel, the outer magnet ring magnetic steel being radially spaced apart from the outer coil and fixed relative to the inner magnet ring magnetic steel;
4. A magnetic levitation gravity compensation device according to claim 2, wherein the magnetization direction of the outer magnet ring magnetic steel is the same as the magnetization direction of the inner magnet ring magnetic steel. The outer magnet ring is made of a plurality of arc plates adjacent to each other along the circumferential direction.
5. The magnetic levitation gravity compensation device according to claim 4, wherein the magnetization direction of each of said arc plates is a radial direction or a direction parallel to the radial direction of the circumferential center of said arc plates. The magnetic levitation gravity compensation device according to claim 1, further comprising an outer guide magnet ring located outside the outer coil and coaxially with the inner magnet ring magnetic steel and radially spaced from the outer coil. the inner base magnet is a permanent magnet or an inner coil or a combination of the permanent magnet and the inner coil;
2. The magnetic levitation gravity compensation device according to claim 1, wherein the inner coil is wound circumferentially around an axis of the first end magnetic steel and the second end magnetic steel. The inner magnet ring magnetic steel is composed of a plurality of arc plates adjacent to each other along the circumferential direction,
2. The magnetic levitation gravity compensation device according to claim 1, wherein the magnetization direction of each of said arc plates is a radial direction or a direction parallel to the radial direction of the circumferential center of said arc plates. A stage device;
a fine movement base to which the stage device is connected so as to be slidable in a direction perpendicular to the fine movement base;
a flexible mechanism including an elastic sheet, the elastic sheet extending in a horizontal radial direction, a radially inner end of the elastic sheet being connected to the stage device, and a radially outer end of the elastic sheet being connected to the fine motion base;
9. A fine movement stage comprising: a magnetic levitation type gravity compensation device according to any one of claims 1 to 8, wherein the inner base magnet, the first end magnetic steel, the second end magnetic steel and the outer coil are incorporated into one of a stator and a mover, and the inner magnet ring magnetic steel is the other of the stator and the mover, the magnetic levitation type gravity compensation device being located below a stage device, the stator being fixed to the fine movement base, and the mover being fixed to the stage device. The fine movement stage according to claim 9, characterized in that there are a plurality of the magnetic levitation gravity compensation devices, and the perpendicular line on which the equivalent centers of gravity of the plurality of the magnetic levitation gravity compensation devices are located is the same line as the perpendicular line on which the center of gravity of the stage device is located.

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