Magnetic levitation type gravity compensation device and fine movement stage

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 gradually increase 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

Technical Field

[0001] This application claims the priority of a patent application filed with the China National Intellectual Property Administration on July 16, 2021, with an application number of 202110804356.0 and an application title of "Magnetic Levitation Gravity Compensation Device and Micro Motion Stage". This application relates to the field of manufacturing integrated circuit devices, and specifically, to a magnetic levitation gravity compensation device and a micro motion stage.

Background Art

[0002] In the fields of semiconductor manufacturing and inspection, the work stage is required to have functions of transferring and precisely positioning a silicon wafer. The core actuator in the work stage is a micropositioner that precisely positions the silicon wafer perpendicular to the three axes of Z, Rx, and Ry. Generally, a vertical three-axis micro motion stage is arranged by adopting a three-point actuator. To ensure vertical performance, a flexible mechanism (such as an elastic sheet, etc.) can be applied as a non-interference and guide for the movement of the micro motion stage. However, 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 according to the vertical displacement. However, as the work stage stroke increases, the non-linearity of the flexible mechanism stiffness also gradually increases.

[0003] Therefore, it is necessary to adjust the output force of the fine movement stage actuator along with the vertical stroke, thereby compensating for the variable stiffness of the flexible structure. Usually, the actuator in the vertical direction of the fine movement stage generally adopts a combination form of a zero stiffness gravity compensation device + a voice coil motor. The zero stiffness gravity compensation device is used to compensate for the gravity of the stage device in the fine movement stage. The stage device is used to place the silicon wafer and drive the silicon wafer to move. 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, there are linear and non-linear regions in the stiffness of the flexible mechanism. Therefore, it is very difficult to completely compensate for the elastic force of the flexible mechanism and the propulsion force of the vertical movement simply by controlling the propulsion force of the voice coil motor. Moreover, in a working situation with high acceleration, the output of the voice coil motor is large, the temperature rise is high, and it is difficult to meet the high movement performance requirements of the fine movement stage.

[0004] In the prior art, generally, an air floating type gravity compensation device that can achieve gravity compensation with a constant stiffness by adjusting the pressure of the compressed gas in real time by a proportional valve is adopted. However, the structure of the air floating type gravity compensation device is very complicated, and there is hysteresis in the control of the air pressure, which affects the improvement of the vertical performance.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The object of the embodiment of the present application is to provide a magnetic levitation type gravity compensation device and a fine movement stage. The magnetic levitation type gravity compensation device in the present application is simple in both structure and control, and has a compact structure. Moreover, it can meet the high movement performance requirements of the work stage.

Means for Solving the Problems

[0006] In order to solve the above problems, the magnetic levitation type gravity compensation device provided by the embodiment of the present application is an inner base magnet extending along the axial direction, and A first end magnetic steel and a second end magnetic steel, each 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 each having an outer diameter that gradually increases along a direction away from the two axial ends of the inner base magnet, An inner magnet ring magnetic steel that forms a cylinder, is located outside the inner base magnet coaxially with the inner base magnet, and is radially spaced from the inner base magnet, An outer coil that is located outside the inner magnet ring magnetic steel coaxially with the inner base magnet, is radially spaced from the inner magnet ring magnetic steel, and is fixed to the inner base magnet, the first end magnetic steel, and the second end magnetic steel.

[0007] In one embodiment, the magnetization direction of the inner base magnet is the axial direction, the magnetization directions of the first end magnetic steel and the second end magnetic steel are outward along the axial direction from the inner base magnet, and the magnetization direction of the inner magnet ring magnetic steel is a direction from inside the ring of the inner magnet ring magnetic steel to outside the ring. In one embodiment, the magnetization direction of the inner base magnet is the axial direction, the magnetization directions of the first end magnetic steel and the second end magnetic steel are from outside along the axial direction toward the inner base magnet, and the magnetization direction of the inner magnet ring magnetic steel is a direction from outside the ring of the inner magnet ring magnetic steel to inside the ring.

[0008] In one embodiment, the magnetic levitation gravity compensation device further includes an outer magnet ring magnetic steel that is located outside the outer coil coaxially with the inner magnet ring magnetic steel, is radially spaced from the outer coil, and is fixed to the inner magnet ring magnetic steel. The magnetization direction of the outer magnet ring magnetic steel is the same as the magnetization direction of the inner magnet ring magnetic steel.

[0009] 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 the radial direction or a direction parallel to the radial direction at the center in the circumferential direction of the arc plate. In one embodiment, the magnetic levitation gravity compensation device further includes an outer guide magnet ring that is located outside the outer coil coaxially with the inner magnet ring magnetic steel and is radially spaced from the outer coil.

[0010] 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 the radial direction or a direction parallel to the radial direction at the center in the circumferential direction of the arc plate.

[0011] The fine movement stage further provided by the present invention is a stage device, a fine movement base connected to the fine movement base such that the stage device is slidable in a direction perpendicular to the fine movement base, a flexible mechanism including an elastic sheet, the elastic sheet extending in the horizontal radial direction, and a radially inner end portion of the elastic sheet being connected to the stage device and a radially outer end portion of the elastic sheet being connected to the fine movement base, the above 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 rotor, the inner magnet ring magnetic steel is the other of the stator and the rotor, the magnetic levitation gravity compensation device is located below the stage device, the stator is fixed to the fine movement base, and the rotor is fixed to the stage device.

[0012] In one embodiment, there are a plurality of the magnetic levitation type gravity compensation devices, and the vertical line passing through the position of the equivalent center of gravity of the plurality of magnetic levitation type gravity compensation devices is the same line as the vertical line passing through the position of the center of gravity of the stage device.

Advantages of the Invention

[0013] Compared with the prior art, the embodiment of the present application solves the problems of the prior art such as the complex structure, complex control, and the existence of hysteresis in control of the pneumatic type gravity compensation device with constant rigidity, and solves the problem that the rigidity of the conventional gravity compensation device is zero or non-linear. When the current of the outer coil is zero, the magnetic levitation output force exhibits a linear characteristic along the stroke in the linear region, and the output force at the zero point can offset the gravity of the stage device. In the non-linear region, by changing the current in the outer coil, the adjustment of the output force is realized, and the compensation of the gravity of the stage device and the elastic force of the flexible mechanism is realized. According to the present application, not only can the gravity of the stage device be compensated, but also the elastic deformation reaction force of the flexible mechanism can be balanced within a large stroke range, reducing the load of the vertical actuator and greatly improving the vertical performance of the fine motion stage. In addition, since the magnetic levitation type gravity compensation device further includes an outer coil, by controlling the direction and magnitude of the current in the outer coil, the output force of the entire magnetic levitation type gravity compensation device that overcomes the gravity of the stage device and the elastic force of the flexible mechanism can be controlled, thereby accurately controlling the moving speed, etc. of the stage device, and meeting the high moving performance requirements of the stage device.

Brief Description of the Drawings

[0014] The accompanying drawings forming a part of this application are used to provide a further understanding of the application. The exemplary embodiments and their descriptions of the application are used to interpret the application and do not constitute an undue limitation to the application. The drawings are as follows.

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Embodiments for Carrying Out the Invention

[0015] Hereinafter, in order to make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, each embodiment of the present application will be described in detail with reference to the drawings. However, as those skilled in the art can understand, in each embodiment of the present application, many technical details are provided for the reader to better understand the present application. However, even without these technical details and various changes and modifications according to the following embodiments, the technical solutions described in the claims of the present application can be realized.

[0016] In the following description, specific details are set forth in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that the embodiments can be practiced without one or more of these specific details. In other instances, well-known devices, structures, and techniques related to the present application may not be shown in detail or described in order to avoid unnecessarily obscuring the description of the embodiments.

[0017] Unless otherwise required, throughout the specification and the claims, the terms "comprise" and its variations, such as "comprises" and "comprising", are to be construed in an open, inclusive sense, that is, as "including, but not limited to". The following will explain each embodiment of the present application in detail with reference to the drawings, in order to more clearly understand the object, features and advantages of the present application. It should be understood that the embodiments shown in the drawings do not limit the scope of the present application, but are for explaining the substantial spirit of the technical solution of the present application.

[0018] Throughout the specification, references to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in the embodiment is included in at least one embodiment. Thus, appearances of "one embodiment" or "an embodiment" in various places throughout the specification are not necessarily all referring to the same embodiment. Also, the particular features, structures, or characteristics may be combined in any manner in one or more embodiments.

[0019] In the specification and claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Unless otherwise specified, the term "or" is generally used in the sense of "and / or". In the following description, in order to clearly show the structure and operation mode of the present application, many directional languages are used for description. However, languages such as "front", "rear", "left", "right", "outer", "inner", "outward", "inward", "up", "down", etc. should be understood as convenient terms and should not be understood as limiting terms. And in the following figures, the direction along the coordinate axis Z (the first direction Z) is the axial direction of the magnetic levitation gravity compensation device, that is, the vertical direction. All of these directional vocabulary are convenient terms and should not be understood as limiting vocabulary. Here, "X direction", "X - direction" and "Y direction", "Y - direction" mean directions intersecting the horizontal direction, and "Z direction" and "Z - direction" mean the vertical direction. In addition, in the following figures, the direction of the arrow "→" indicates the magnetization direction, and "×" indicates the cross - section of the coil.

[0020] Hereinafter, the magnetic levitation type gravity compensation device of Embodiment 1 of the present application will be described with reference to the drawings. As shown in FIGS. 1 and 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 respectively located at two axial ends of the inner base magnet 1 and extend along the axial direction. 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 coaxially located outside the inner base magnet 1 and is radially spaced from the inner base magnet 1. The outer coil 5 is coaxial with the inner base magnet 1 and is located outside the inner magnet ring magnetic steel 4, and the outer coil 5 is radially spaced from the inner magnet ring magnetic steel 4. Since the outer coil 5 is usually provided with a power amplifier, 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, that is, a fixed connection is established between the outer coil 5 and the first end magnetic steel 2 or the second end magnetic steel 3 by brackets or other structures. 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 there is a magnetic interaction between the first frame 101 and the inner magnet ring magnetic steel 4, so that they can move axially relative to each other. The first frame 101 may be used as the mover and the inner magnet ring magnetic steel 4 as the stator, or the inner magnet ring magnetic steel 4 may be used as the mover and the first frame 101 as the stator. When the first frame 101 is the mover, it carries a stage device and drives it to move. When the inner magnet ring magnetic steel 4 is the mover, it carries a stage device and drives it to move.Hereinafter, taking the case where the first frame 101 is a movable element as an example, the magnetic levitation type gravity compensation device 100 of the present application will be described. The stroke or displacement of the magnetic levitation type gravity compensation device 100 described below is the displacement along the first direction (Z) with respect to the inner magnet ring magnetic steel 4 of the first frame 101.

[0021] The magnetic levitation type 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 type gravity compensation device 100 in the above embodiment. The stage device is slidably connected to the fine movement base 104 in a direction perpendicular to the fine movement base 104. As shown in FIGS. 15a and 15b, one end of the flexible mechanism 7 is connected to the stage device, the other end is connected to the fine movement base 104, and the magnetic levitation type gravity compensation device 100 is located below the stage device and is configured to be able to compensate for the gravity of the stage device.

[0022] Specifically, as shown in FIGS. 15a and 15b, the stage device includes a stage 6 and a rotary base 103 provided below the stage 6. Here, the stage 6 is used to adsorb a silicon wafer, and vacuum adsorption, electrostatic adsorption, etc. may be used. The flexible mechanism 7 includes a plurality of elastic sheets 71. The elastic sheets 71 extend horizontally in the radial direction between the fine movement base 104 and the rotary base 103 and are fixedly connected to the fine movement base 104 and the rotary base 103 at both ends respectively. Specifically, the radially inner end of the flexible mechanism 7 is connected to the rotary base 103, and the radially outer end is connected to the fine movement base 104.

[0023] As shown in FIGS. 1 and 2, the first end magnetic steel 2 and the second end magnetic steel 3 are frustum-shaped with axially penetrating holes. As can be understood, the first end magnetic steel 2 and the second end magnetic steel 3 may have a solid structure without departing from the scope of the present application. 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 side close to the two axial ends of the inner base magnet 1. Axially penetrating holes are respectively provided in the first end magnetic steel 2 and the second end magnetic steel 3, and the axially penetrating holes are coaxial with the axially penetrating hole of the inner base magnet 1 and have the same diameter and are communicated with each other. The first end magnetic steel 2 and the second end magnetic steel 3 have the same shape and size as each other and are mirror-symmetrical with respect to the central radial plane of the inner base magnet 1. The inner magnet ring magnetic steel 4 is cylindrical, is located outside the inner base magnet 1 coaxially with the inner base magnet 1, and is radially spaced from the inner base magnet 1. In the shown embodiment, the first end magnetic steel 2 and the second end magnetic steel 3 are adjacent to the inner base magnet 1, but an air gap of about 1 mm or less may usually be provided between them.

[0024] The magnetic levitation gravity compensation device 100 in this embodiment has both the following vertical compensation and vertical drive functions. As shown in FIGS. 2 and 15a, there is no mechanical connection between the first frame 101 and the inner magnet ring magnetic steel 4. Within the linear stroke range, the rigidity of the flexible mechanism 7 is constant, and the interaction between the first frame 101 and the inner magnet ring magnetic steel 4 can generate a vertically biasing force with a constant rigidity. Here, if the inner magnet ring magnetic steel 4 and the inner base magnet 1 are centrally located with respect to each other's axial directions, it becomes the device zero point. Since it is necessary to compensate for the gravity of the stage device when the device is located at the zero point, its external output magnetic levitation force needs to 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 linearly changes 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 linearly changes with the vertical movement of the stage device. Only when the change gradients of both are equal can the magnetic levitation gravity compensation device 100 fully realize the compensation effect on 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. If 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.

[0025] Figure 5b shows the 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 represents the stroke of the magnetic levitation gravity compensation device 100, and the vertical axis represents the output force. Two reverse displacement endpoints, the zero point, and their corresponding output forces are shown in the figure. In the figure, x and -x are the limit displacements in a single direction, G is the gravity of the stage device to be compensated by a single magnetic levitation gravity compensation device 100, and G + F and -F + G are the output forces at the endpoints of the linear stroke range of a single magnetic levitation gravity compensation device 100. When the design stiffness 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 endpoint x is G + F = G + kx. From this, 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, and thereby can compensate for the gravity of the stage device and the elastic force of the linear change generated by the flexible mechanism 7.

[0026] 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 the magnetic levitation gravity compensation device 100 has the characteristic of a constant stiffness.

[0027] This magnetic levitation gravity compensation device 100 can be applied in a larger stroke range than in the linear stroke range. The difference between it and the linear stroke range is that the rigidity of the flexible mechanism 7 is constant within the linear stroke range, but the large stroke range includes the linear stroke range and the non-linear stroke range beyond the linear stroke range, and the rigidity 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 along the first direction (Z) of the magnetic levitation gravity compensation device 100, and the vertical axis is the output force along the first direction (Z) of the flexible mechanism 7. As can be seen from the figure, within the linear region A (i.e., the linear stroke range) of the stroke range of displacement in the first direction, the output rigidity 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 this region, that is, in the non-linear region B within the stroke range, at this time, the output rigidity of the flexible mechanism 7 changes according to the displacement, and its elastic force and displacement also change non-linearly. However, 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 only perform linear compensation, which causes some elastic forces of the flexible mechanism 7 not to be compensated. At this time, by controlling the current direction and amplitude in the outer coil 5, a Lorentz force in the corresponding direction and magnitude can be generated to compensate for the elastic force of the part that is not compensated by the first end magnetic steel 2 and the second end magnetic steel 3. Therefore, this magnetic levitation gravity compensation device 100 also has a vertical compensation effect in the non-linear region B.

[0028] 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) with respect 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, since 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, the change gradient of the outer diameter sizes of the first end magnetic steel 2 and the second end magnetic steel 3 coincides with the change gradient of the output elastic force of the flexible mechanism 7. Within 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.

[0029] In the non-linear region, although the output force of the flexible mechanism 7 exhibits a non-linear change, when the current in the outer coil 5 is zero, since the output magnetic levitation force of the magnetic levitation gravity compensation device 100 still exhibits a linear change, the output magnetic levitation force of the magnetic levitation gravity compensation device 100 does not become 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 the stroke range in the non-linear region with respect 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.

[0030] Therefore, specifically, the magnetic levitation gravity compensation device 100 of the present application is a gravity compensation device with a constant rigidity within the linear stroke range, and is a high-integration device with adjustable 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 movement 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 within the linear region of the flexible mechanism 7. Within the large stroke range, by adjusting the magnitude and direction of the current of the outer coil 5, 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 the compensation force in the non-linear region of the flexible mechanism 7 can be provided.

[0031] Within the linear stroke range, the vertical compensation effect of the magnetic levitation gravity compensation device 100 of this embodiment has further features. As shown in FIG. 5c, in the figure, the horizontal axis is the displacement along the first direction (Z) of the first frame 101 in the magnetic levitation gravity compensation device 100, and the vertical axis is the output force along the first direction (Z) of the magnetic levitation gravity compensation device 100. The five curves in the figure respectively correspond to the output force curves of the magnetic levitation gravity compensation device 100 under the working conditions of different input currents of the outer coil 5.

[0032] It should be noted that although the current in the outer coil 5 in FIG. 5c is constant, in actual situations, when the magnetic levitation gravity compensation device 100 is in a large stroke range, in order to compensate for the elastic force of the flexible mechanism 7, it is necessary to adjust the magnitude of the current step by step as needed. As can be seen from FIG. 5c and FIG. 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 these zero points are m5, m4, m1, m2, and m3 respectively. When the input current is 0A, the output force is the 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.

[0033] When the inner magnet ring magnetic steel 4 and the inner base magnet 1 are centered with respect to each other's axial direction, it becomes the device zero point. When the current in the outer coil 5 is zero, the output force of the magnetic levitation gravity compensation device 100 is equal in magnitude and opposite in direction to the gravity of the stage device. When located at the zero point, if the magnetic levitation gravity compensation device 100 cannot completely compensate for the gravity of the stage device or the compensation force exceeds the gravity of the stage device, 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 matched to the gravity of the stage device. Also, the linearity of each output curve in the figure is good (i.e., all show a constant rigidity), and the linearization of the magnetic field is realized by utilizing the tapers of the first end magnetic steel 2 and the second end magnetic steel 3, and the gravity compensation means of the stage device at the zero point is realized by applying the interaction between the magnetic field by the first frame 101 and the magnetic field by the inner magnet ring magnetic steel 4.

[0034] Therefore, this application can not only compensate for the gravity of the stage device but also be adjusted based on the gravity of the stage device. The operator can simply change the current in the outer coil 5 to maintain the balance at the zero point for the entire device, greatly improving the production efficiency and the stability of the fine movement stage. Also, when the above method is adopted, the structure of the magnetic levitation gravity compensation device 100 can be made more compact, saving the design space and having a very high integration level.

[0035] Note that the figure shown in FIG. 5c above is a figure when the current in the outer coil 5 is a constant value. However, in the actual situation, when the flexible mechanism 7 is in the 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 completely compensate for the gravity of the stage device and the elastic force of the flexible mechanism 7.

[0036] In addition to the above vertical compensation effect, the magnetic levitation type gravity compensation device 100 in this embodiment further has a vertical driving effect. As can be seen from FIG. 5c, when different currents are input to the outer coil 5, the magnetic levitation type gravity compensation device 100 has different output forces. Similarly, by controlling the current direction and amplitude of the outer coil 5, the moving direction and acceleration of the stage device can be controlled, thereby achieving the vertical driving effect.

[0037] Within the linear stroke range, the magnetic levitation type gravity compensation device 100 has the characteristic of constant rigidity, and the magnetic levitation type gravity compensation device 100 can always compensate for the gravity of the stage device and the elastic force of the flexible mechanism 7. When at the initial zero point position, regardless of whether a constant current is flowing through the outer coil 5, by simply changing the current direction and amplitude in the outer coil 5, the acceleration force required for the movement of the stage device can be provided, enabling the stage device to respond rapidly, for example, to accelerate or decelerate rapidly, and simultaneously serving the roles of vertical compensation and vertical driving. And through such control, the current in the coil part is reduced, resulting in a low temperature rise, and the stage device can meet the application requirements of high dynamic response.

[0038] In a large stroke range, the outer coil 5 needs to continuously change the current direction and amplitude to compensate for the non-linear elastic force of a part of the flexible mechanism 7. Moreover, on this basis, the current direction and amplitude in the outer coil 5 can still be changed through calculation to provide the acceleration force required for the movement of the stage device. As described above, the magnetic levitation type gravity compensation device 100 not only has a vertical compensation function but also a vertical driving function. Therefore, when applied to the fine movement stage, there is no need to separately install a vertical driving device, which saves the design space of the fine movement stage, makes the structure of the fine movement stage more compact, and has a very high integration degree. In the present 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. Therefore, the current in the coil portion is small and the temperature rise is low. Therefore, the stage device can meet the application requirements of high dynamic response such as rapid acceleration or deceleration. And since the magnetic levitation type gravity compensation device 100 in the present application has a compact structure, it can save the design space of the stage device and has a very high integration degree.

[0039] In addition, since the outer coil 5 is provided, as shown in FIG. 5a, it is possible to realize the function of compensating the gravity of the stage device and the elastic force of the flexible mechanism 7 even within a large stroke range of the magnetic levitation gravity. Further, since the outer coil 5 is added, if the inner magnet ring magnetic steel 4 and the inner base magnet 1 are centered with respect to each other in the axial direction, it becomes the device zero point, and the weight of the stage device can be additionally compensated by adjusting the magnitude of the current in the outer coil 5.

[0040] Also, as shown in FIGS. 2 to 4, specifically, in this embodiment, the magnetization directions of the first end magnetic steel 2 and the second end magnetic steel 3 are outward along the axial direction from the inner base magnet 1. The magnetization direction of the inner base magnet 1 may be the same as that of either the first end magnetic steel 2 or the second end magnetic steel 3. In this embodiment, the magnetization direction of the inner base magnet 1 is the same as that of 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 generated by the outer coil 5 can be arbitrarily adjusted as required. Of course, in some embodiments, the magnetization directions of the first end magnetic steel 2 and the second end magnetic steel 3 may be in the direction from the outside to the inner base magnet 1 along the axial direction, that is, opposite to the outward direction along the axial direction from the inner base magnet 1 described above, and the magnetization direction of the inner magnet ring magnetic steel 4 may also be provided inward along the radial direction accordingly.

[0041] In some embodiments, as shown in FIGS. 1, 3, and 4, the inner magnet ring magnetic steel 4 is composed of a plurality of adjacent arc plates 41 along the circumferential direction. As shown in FIG. 3, the magnetization direction of each arc plate 41 is provided along the radial direction of the inner magnet ring magnetic steel 4, that is, the magnetization directions at different circumferential positions within the arc plate 41 are all along the radial direction, or as shown in FIG. 4, the magnetization direction of the arc plate 41 is parallel to the radial direction at the center of the circumferential direction of the arc plate 41, that is, all the magnetic flux lines of the arc plate 41 are provided in parallel and are parallel to the symmetric plane in the circumferential direction of the arc plate 41. When all the magnetic flux lines within the arc plate 41 are parallel, it is easy to magnetize each arc plate 41. By simply placing the arc plate 41 in a parallel magnetic field, magnetization can be completed.

[0042] As shown in Fig. 1, the inner magnet ring magnetic steel 4 is formed by joining eight block-shaped magnetic steels. Here, the eight block-shaped magnetic steels are arc plates 41 that are equally divided into eight along the radial direction at an equiangular interval of 45° by a cylinder. However, the inner magnet ring magnetic steel 4 may be joined by other numbers of block-shaped magnetic steels. In order to eliminate the radial unbalanced force generated by the inner magnet ring magnetic steel 4, the number of blocks N is set to an even number, such as 2 blocks, 4 blocks, 6 blocks, etc. The inner magnet ring magnetic steel 4 is formed by joining block-shaped magnetic steels 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.

[0043] Embodiment 2 of the present application provides a magnetic levitation gravity compensation device 100. This embodiment is basically the same as Embodiment 1. The difference is that, as shown in Figs. 6 and 7, the magnetic levitation gravity compensation device 100 in this embodiment may further include an outer magnet ring magnetic steel 8. The outer magnet ring magnetic steel 8 is provided coaxially with the inner magnet ring magnetic steel 4, located outside the outer coil 5, and is spaced apart from the outer coil 5 along the radial direction. The magnetization direction of the outer magnet ring magnetic steel 8 is the same as the magnetization direction of the inner magnet ring magnetic steel 4, that is, the magnetization direction of the outer magnet ring magnetic steel 8 may be radially outward or radially inward.

[0044] Also, the outer magnet ring magnetic steel 8 and the inner magnet ring magnetic steel 4 are relatively fixed. The outer magnet ring magnetic steel 8 and the inner magnet ring magnetic steel 4 may be integrally fixed 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. The second frame 102 may be a stator or a rotor. A mutual magnetic acting force can be generated between the second frame 102 and the first frame 101 to enable mutual movement. Either the first frame 101 or the second frame 102 is a rotor, and the other is a stator.

[0045] 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. Within the stroke range, between 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 magnetic field formed by the inner magnet ring magnetic steel 4 and the outer magnet ring magnetic steel 8 in the second frame 102, they interact to generate a vertically upward magnetic levitation acting force with a constant magnitude. This magnetic levitation acting force is equal in magnitude and opposite in direction to the gravity at the zero point of the vertical movement mechanism of the stage device. The outer tapers of the first end magnetic steel 2 and the second end magnetic steel 3 in the first frame 101 linearize the output magnetic force of the first frame 101. The interaction between the inner base magnet 1, the first end magnetic steel 2, and the second end magnetic steel 3, and the magnetic field formed by the inner magnet ring magnetic steel 4 and the outer magnet ring magnetic steel 8 in the second frame 102 is vertically upward, capable of generating a magnetic levitation acting force with a constant rigidity. By superimposing these two acting forces, a vertical magnetic levitation force with a constant output rigidity can be realized.

[0046] The outer coil 5 is usually equipped with a power amplifier. By adjusting the current input of the outer coil 5, according to the Lorentz force law that the magnetic field generates a Lorentz force on the moving charge, the outer coil 5 is arranged along the radial direction between the inner magnet ring magnetic steel 4 and the outer magnet ring magnetic steel 8. 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. This Lorentz force can relatively displace the first frame 101 and the second frame 102 along a preset trajectory. At this time, the outer coil 5 does not need to overcome the gravity of the stage device. As long as the force of the acceleration 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, 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.

[0047] Also, as shown in FIGS. 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. Alternatively, in some embodiments, the outer magnet ring magnetic steel 8 may be a single complete magnet ring. As shown in FIG. 8, the magnetization direction of each arc plate 81 is provided along the radial direction of the outer magnet ring magnetic steel 8, or as shown in FIG. 9, the magnetization direction of the arc plate 81 is parallel to the radial direction at the center of the circumferential direction of the arc plate 81. That is, each magnetic flux line of the arc plate 81 may be provided along the radial direction of the outer magnet ring magnetic steel 8, or each magnetic flux line of the arc plate 81 may be provided in parallel and parallel to the circumferential symmetry plane of the arc plate 41. When each magnetic flux line is parallel, it is easy to magnetize each arc plate 81. By simply placing the arc plate 81 in a parallel magnetic field, magnetization can be completed.

[0048] As shown in FIG. 6, the outer magnet ring magnetic steel 8 is formed by joining eight block-shaped magnetic steels. Here, the eight block-shaped magnetic steels are arc plate 81 magnetic steels obtained by equally dividing a cylinder into eight equal parts along the radial direction at an equiangular interval of 45°. However, the outer magnet ring magnetic steel 8 may be formed by joining other numbers of block-shaped magnetic steels. In order to eliminate the radial unbalanced force generated by the outer magnet ring magnetic steel 8, the number of blocks N is set to an even number, such as 2 blocks, 4 blocks, 6 blocks, etc. The outer magnet ring magnetic steel 8 is formed by joining block-shaped magnetic steels to facilitate magnetization and processing of the magnetic steel.

[0049] As shown in FIG. 10, the magnetic flux lines of this embodiment show a partial axial cross-sectional schematic view of FIG. 6 in the figure, and in the figure, the traveling direction of the magnetic flux lines substantially coincides with the designed magnetic circuit. Example 3 of the present application provides a magnetic levitation gravity compensation device 100. Example 3 is substantially the same as Example 1, and its main difference is that, as shown in FIG. 11, the magnetic levitation gravity compensation device 100 in this example is located outside the outer coil 5 coaxially with the inner magnet ring magnetic steel 4 and further includes an outer guide magnet ring 10 that is radially spaced from the outer coil 5. The outer guide magnet ring 10 is made of a magnetic permeable material such as iron or a high magnetic permeability (Fe Si B) 98 (Cu Nb) 2 amorphous alloy. The outer guide magnet ring 10 can reinforce the magnetic field of the entire magnetic levitation gravity compensation device 100.

[0050] Further, the outer guide magnet ring 10 is composed of a plurality of arc plates adjacent to each other in the circumferential direction. Of course, it may also be an integral ring. Example 4 of the present application provides a magnetic levitation gravity compensation device 100. Example 4 is basically the same as Example 2, and the main difference is that in Example 2, the inner base magnet 1 is a permanent magnet, but as shown in FIGS. 12 and 13, in this example, the inner base magnet 1 is an inner coil 12. 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 axial ends of the inner ring 11. When the inner ring 11 is formed of a permanent magnet, both the permanent magnet and the inner coil 12 constitute the inner base magnet 1, and together with the first end magnetic steel 2 and the second end magnetic steel 3, form the first frame 101, and interact with the second frame 102 to generate a magnetic levitation force. Note that the inner coil 12 may be fixed in other ways, as long as it is located between the first end magnetic steel 2 and the second end magnetic steel 3 and the conductors thereof are wound circumferentially around the axis. The current direction in the inner coil 12 may be adjusted as required. As shown in FIG. 13, when the inner coil 12 is energized, the magnetic force direction of the inner coil 12 is upward along the axis. 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.

[0051] Normally, a power amplifier for adjusting the input of the inner coil 12 is arranged in the inner coil 12. According to the right-hand rule, by adjusting the direction and amplitude of the input current of the inner coil 12 in the first frame 101, it is adapted to the gravity of the stage device of different weights, thereby improving the applicable range of the magnetic levitation gravity compensation device 100. When the current of the outer coil 5 is zero, when 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, by adjusting the direction and amplitude of the current of the outer coil 5, the magnetic levitation gravity compensation device 100 is moved at a high acceleration along a preset trajectory, improving the moving performance of the stage device along the first direction (Z).

[0052] In this embodiment, as shown in FIGS. 14a and 14b, the magnetic flux lines corresponding to the structure are shown. A partial axial cross-sectional schematic view of FIG. 13 is shown in the figure. FIG. 14a is a magnetic flux line diagram when the inner coil 12 is energized and the outer coil 5 is not energized, and FIG. 14b is a magnetic flux line diagram when neither the inner coil 12 nor the outer coil 5 is energized. As can be seen from the figure, the magnetic flux lines are mirror-symmetric along the first plane (XoY).

[0053] As described above, the preferred embodiments of the present application have been described in detail. However, it will be understood that if necessary, other embodiments may be provided by modifying the embodiments by utilizing the aspects, features, and concepts of each patent, application, and publication. In view of the above detailed description, these and other changes can be made to the embodiments. Generally, in the claims, the terms used are not limited to the specific embodiments disclosed in the specification and claims, but should be understood to include all possible embodiments and all equivalent scopes that these claims may have.

[0054] Also, the details of the related technologies and the achievable technical effects mentioned in each of the above embodiments are still valid in other embodiments. In order to reduce duplication, the description is omitted in some embodiments. This application further provides a fine movement stage. As shown in FIGS. 15a to 16, the fine movement stage includes a stage device, a flexible mechanism 7, a fine movement base 104, and a magnetic levitation gravity compensation device 100 in any one of the above embodiments. The stage device is connected to the fine movement base 104 so as to be slidable in a direction perpendicular to the fine movement base 104. The flexible mechanism 7 includes a plurality of elastic sheets 71. The elastic sheets 71 extend in the horizontal radial direction, and the radially inner end portion of the elastic sheet 71 is connected to the stage device, and the radially outer end portion of the elastic sheet 71 is connected to the fine movement base 104. The magnetic levitation gravity compensation device 100 is located below the stage device and is configured to be able to compensate the force of 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 rotor, and the inner magnet ring magnetic steel 4 is the other of the stator and the rotor. The magnetic levitation gravity compensation device 100 is located below the stage device, and the magnetic levitation gravity mover supports the stage device.

[0055] Specifically, the stage device includes a stage 6 and a rotating base 103 provided below the stage 6. The flexible mechanism 7 extends radially between the fine movement base 104 and the rotating base 103 and is fixedly connected to the fine movement base 104 and the rotating base 103 at both ends. Specifically, the radially inner end portion of the flexible mechanism 7 is connected to the rotating base 103, and the radially outer end portion is connected to the fine movement base 104.

[0056] Also, as shown in FIG. 15b, the flexible mechanism 7 includes a plurality of elastic sheets 71. Each elastic sheet 71 is annularly provided around the center of the stage device on the outer periphery of the stage device. The outer side in the radial direction of each elastic sheet 71 is connected to other members of the fine movement stage. There are a plurality of magnetic levitation gravity compensation devices 100, and each magnetic levitation gravity compensation device 100 is provided in parallel and spaced apart from each other. Naturally, in some embodiments, there may be only one magnetic levitation gravity compensation device 100.

[0057] FIG. 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. In the figure, 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 in, for example, an equilateral triangle, and four magnetic levitation type gravity compensation devices 100 are arranged in a square. Schematic diagrams are shown, but magnetic levitation type gravity compensation devices 100 with other numbers and other arrangement modes may also 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 required. It should be understood that the vertical line where the equivalent center of gravity of the plurality of magnetic levitation type gravity compensation devices 100 is located needs to be the same line as the vertical line where the center of gravity of the vertical movement mechanism is located.

[0058] As shown in FIG. 16, according to the magnetic levitation type gravity compensation device 100 of the present application, a magnetic levitation force that changes linearly with the stroke can be provided, that is, not only can the gravity of the stage device be compensated, but also the elastic force generated by the flexible mechanism 7 can be compensated, and in some cases, the requirements for gravity compensation of the fine movement stage can be met. 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 its coil part is small, the temperature rise is low, and the stage device can meet the application requirements of high dynamic response. And according to the magnetic levitation type gravity compensation device 100 in the present application, since the structure is compact, the design space of the stage device can be saved and the integration degree is very high.

[0059] In addition, for other member structures and connection relationships in the fine movement stage, reference can be made to the description in the application with the publication number CN112259488B, and this patent publication is incorporated herein by reference. As can be understood by those skilled in the art, each of the above embodiments is a specific example for implementing the present application. In actual applications, various changes can be made to the form and details thereof without departing from the spirit and scope of the present application.

Claims

1. 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 each having an outer diameter that gradually increases along a direction away from the two axial ends of the inner base magnet, An inner magnet ring magnetic steel having a cylindrical shape, located outside the inner base magnet coaxially with the inner base magnet, and radially spaced from the inner base magnet, An outer coil located outside the inner magnet ring magnetic steel coaxially with the inner base magnet, radially spaced from the inner magnet ring magnetic steel, and fixed to the inner base magnet, the first end magnetic steel, and the second end magnetic steel, The inner base magnet is a combination of an inner coil or a permanent magnet and the inner coil, The inner coil is wound circumferentially around the axes of the first end magnetic steel and the second end magnetic steel, and a magnetic levitation type gravity compensation device characterized by this.

2. The magnetization direction of the inner base magnet is the axial direction, the magnetization directions of the first end magnetic steel and the second end magnetic steel are outward along the axial direction from the inner base magnet, and the magnetization direction of the inner magnet ring magnetic steel is a direction from inside the ring of the inner magnet ring magnetic steel to outside the ring. The magnetic levitation type gravity compensation device according to Claim 1, characterized by this.

3. The magnetization direction of the inner base magnet is the axial direction, the magnetization directions of the first end magnetic steel and the second end magnetic steel are directions from outside along the axial direction towards the inner base magnet, and the magnetization direction of the inner magnet ring magnetic steel is a direction from outside the ring of the inner magnet ring magnetic steel to inside the ring. The magnetic levitation type gravity compensation device according to Claim 1, characterized by this.

4. An outer magnet ring magnetic steel located outside the outer coil coaxially with the inner magnet ring magnetic steel, radially spaced from the outer coil, and fixed to the inner magnet ring magnetic steel, further including an outer magnet ring magnetic steel, The magnetic levitation type gravity compensation device according to Claim 2 or 3, characterized in that the magnetization direction of the outer magnet ring magnetic steel is the same as the magnetization direction of the inner magnet ring magnetic steel.

5. The outer magnetic 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 the radial direction or a direction parallel to the radial direction at the center in the circumferential direction of the arc plate. The magnetic levitation type gravity compensation device according to claim 4 is characterized by this.

6. The magnetic levitation type gravity compensation device according to claim 1, further comprising an outer guide magnetic ring that is located outside the outer coil coaxially with the inner magnetic ring magnetic steel and is radially spaced apart from the outer coil.

7. The inner magnetic 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 the radial direction or a direction parallel to the radial direction at the center in the circumferential direction of the arc plate. The magnetic levitation type gravity compensation device according to claim 1 is characterized by this.

8. A stage device; A fine movement base connected to the fine movement base such that the stage device is slidable in a vertical direction with respect to the fine movement base; A flexible mechanism including an elastic sheet, the elastic sheet extending in the horizontal radial direction, the radially inner end of the elastic sheet being connected to the stage device, and the radially outer end of the elastic sheet being connected to the fine movement base; A magnetic levitation type gravity compensation device according to any one of claims 1 to 7, 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 rotor, the inner magnetic ring magnetic steel is the other of the stator and the rotor, the magnetic levitation type gravity compensation device is located below the stage device, the stator is fixed to the fine movement base, and the rotor is fixed to the stage device. A fine movement stage characterized by including a magnetic levitation type gravity compensation device.

9. The fine movement stage according to claim 8, wherein there are a plurality of the magnetic levitation type gravity compensation devices, and a perpendicular line passing through the position of the equivalent center of gravity of the plurality of magnetic levitation type gravity compensation devices is the same line as a perpendicular line passing through the position of the center of gravity of the stage device.

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