JP2018164371A - Linear motor and stage apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear motor capable of reducing generation of flux leakage at an end of a movable element including a field magnet.SOLUTION: A linear motor 2 includes a movable element 20 comprised of a pair of yokes 22b, 22c and a pair of field magnet arrays 24b, 24c fixed on the pair of yokes 22b, 22c and facing each other, sandwiching a magnetic cavity 34. The field magnet array 24 includes a plurality of magnets 25 arrayed in a first direction. Ends of the pair of yokes 22b, 22c in the first direction is formed with a magnetic collection structure 30 for guiding a part of magnetic fluxes formed by the field magnet array 24 to a magnetic cavity 34.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a linear motor and a stage apparatus.

  Linear motors are used to convert electrical energy into linear motion. For example, Patent Document 1 describes a movable magnet type linear motor including a stator having a multiphase coil and a mover having a permanent magnet.

Japanese Patent Laid-Open No. 10-052024

The present inventor has obtained the following recognition about the linear motor.
In recent years, the performance of measuring devices driven by linear motors has improved, and the specifications of leakage flux for linear motors have become more sophisticated. For example, a movable magnet type linear motor includes a magnetic circuit including a field magnet in a mover. In such a magnetic circuit, since an opening is formed at the end thereof, a part of the magnetic flux of the field magnet leaks to the outside from this end, and the distribution of the leakage magnetic flux in the vicinity of this end. The peak was found to be formed. If the peak position is constant without changing, it is conceivable to concentrate the leakage magnetic flux at that position, but such a countermeasure is difficult to take when the peak position moves.

Moreover, if the peak of the leakage magnetic flux is large, it may affect the characteristics of the device driven by the linear motor. For example, in an electron beam apparatus driven by a linear motor, the measurement accuracy may be affected even when the leakage magnetic flux is weak.
From these viewpoints, the present inventor has recognized that there is room for improvement in the linear motor from the viewpoint of suppressing the leakage magnetic flux at the end of the mover including the field magnet.

  This invention is made | formed in view of such a condition, The objective is to provide the linear motor which can reduce the leakage magnetic flux in the edge part of the needle | mover containing a field magnet.

  In order to solve the above problems, a linear motor according to an aspect of the present invention includes a pair of yokes and a pair of field magnet arrays fixed to the pair of yokes and facing each other with a magnetic gap therebetween. Is provided. The field magnet array includes a plurality of magnets arranged in the first direction. A magnetic flux collecting structure that guides a part of the magnetic flux formed by the field magnet array to the magnetic gap is provided at the ends in the first direction of the pair of yokes.

  According to this aspect, the magnetic flux can be guided to the magnetic gap by providing the magnetic flux collecting structure.

  A stage apparatus according to another aspect of the present invention includes the linear motor described above.

  Note that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention replaced with each other among methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the linear motor which can reduce the leakage magnetic flux in the edge part of the needle | mover containing a field magnet can be provided.

1 is a perspective view of a linear motor according to an embodiment of the present invention. It is a top view of the linear motor of FIG. It is a front view of the linear motor of FIG. It is a side view of the linear motor of FIG. It is explanatory drawing which shows typically the flow of the magnetic flux of the needle | mover of the linear motor of FIG. It is explanatory drawing which shows typically the flow of the magnetic flux in a comparative example. It is a top view of the stage apparatus using the linear motor which concerns on embodiment. It is a side view of the linear motor which concerns on a 1st modification. It is a front view which shows the periphery of the magnetic flux collection structure of the linear motor of FIG. It is a perspective view of the surrounding member of the linear motor of FIG. It is a front view which shows the periphery of the magnetic flux collecting member which concerns on a 2nd modification. It is a front view which shows the periphery of the magnetic flux collecting member which concerns on a 3rd modification. It is a front view which shows the periphery of the magnetic flux collecting member which concerns on a 4th modification. It is a front view which shows the periphery of the magnetic flux collecting member which concerns on a 5th modification.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. In addition, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. Also, in the drawings, some of the members that are not important for describing the embodiment are omitted. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

[Embodiment]
FIG. 1 is a perspective view of a linear motor 2 according to an embodiment. FIG. 2 is a plan view of the linear motor 2. FIG. 2 shows a state in which the yoke 22b is removed. FIG. 3 is a front view of the linear motor 2. FIG. 3 is a partial cross-sectional view of the coil unit 18 with the connecting member 28c removed. FIG. 4 is a side view of the linear motor 2. The linear motor 2 includes a stator 10 and a mover 20. Hereinafter, description will be made based on the XYZ orthogonal coordinate system. The X-axis direction corresponds to the horizontal left-right direction, the Y-axis direction corresponds to the horizontal front-back direction, and the Z-axis direction corresponds to the vertical up-down direction. The Y-axis direction and the Z-axis direction are each orthogonal to the X-axis direction. The X-axis direction may be referred to as the left direction or the right direction, the Y-axis direction may be referred to as the forward direction or the rear direction, and the Z-axis direction may be referred to as the upward direction or the downward direction. Such notation of the direction does not limit the use posture of the linear motor 2, and the linear motor 2 can be used in an arbitrary posture.

  The stator 10 is fixedly supported by a stationary body (not shown). The stator 10 is arranged so that the longitudinal direction is along the first direction that is the X-axis direction. The mover 20 forms a magnetic gap 34 that accommodates at least a part of the stator 10 and is provided so as to be movable in the first direction. The first direction may be referred to as a movable direction. The mover 20 surrounds the coil unit 18 of the stator 10 via a gap. As shown in FIG. 4, the magnetic air gap 34 has an I-shaped cross section in a side view. A part of the coil unit 18 of the stator 10 is accommodated in the magnetic gap 34. 1 to 4, the main magnetic flux of the magnetic air gap 34 faces the Z-axis direction orthogonal to the first direction.

(stator)
Stator 10 includes a coil unit 18 extending in the X-axis direction. The coil unit 18 is a substantially plate-like member that has a rectangular shape in a plan view and is thin in the Z-axis direction, for example. As an example, the coil unit 18 is arranged so that the long side is along the X-axis direction and the short side is along the Y-axis direction in plan view. The coil unit 18 includes a plurality of coils 12 arranged in the X-axis direction. The plurality of coils 12 are integrated, for example, by being wrapped in resin. The coil unit 18 mainly includes an intermediate portion 18m facing the field magnet array 24, and an edge portion 18d provided on both ends of the intermediate portion 18m in the Y-axis direction. The edge portion 18d is formed thicker in the Z-axis direction than the intermediate portion 18m. The coil unit 18 has an I-shaped outline that is horizontally oriented in a side view.

(Movable element)
The mover 20 includes a magnetic circuit unit 23. The magnetic circuit unit 23 mainly includes a pair of yokes 22b and 22c, a pair of field magnet arrays 24b and 24c, a magnetic flux collecting structure 30, and a pair of connecting members 28b and 28c. The yokes 22b and 22c are collectively referred to as the yoke 22. The field magnet rows 24b and 24c are collectively referred to as a field magnet row 24. The connecting members 28b and 28c are collectively referred to as a connecting member 28. The magnetic flux collecting structure 30 includes a pair of magnetic flux collecting structures 30 b and 30 c that are arranged apart from each other in the Z-axis direction with the magnetic gap 34 interposed therebetween.

(yoke)
The pair of yokes 22b and 22c are arranged apart from each other in the Z-axis direction orthogonal to the first direction. The yoke 22 is disposed on the opposite side of the field magnet row 24 from the magnetic air gap 34. The yoke 22 functions as a back yoke for the field magnet array 24. The yoke 22 is, for example, a substantially plate-like member that has a rectangular shape in plan view and is thin in the Z-axis direction. As an example, the yoke 22 is arranged so that the long side is along the X-axis direction and the short side is along the Y-axis direction in plan view. The yoke 22 includes a main body portion 22m that supports the field magnet array 24, and an overhang end portion 22n that protrudes from the main body portion 22m in the first direction. That is, the projecting end portions 22n are continuously provided on both sides of the main body portion 22m in the first direction. A plurality of magnets 25 of the field magnet array 24 are fixed to the main body 22m, and a magnetism collecting member 26 described later is fixed to the overhanging end 22n. The surface 22e to which the field magnet array 24 of the yoke 22 is fixed extends in the first direction and the second direction (Y-axis direction) orthogonal to the first direction. The yoke 22 can be formed from various magnetic materials. As an example, in the embodiment, the yoke 22 is formed of a metal material having soft magnetism.

(Connecting member)
The pair of connecting members 28b and 28c are members that connect the ends in the Y-axis direction of the pair of yokes 22b and 22c. The connecting member 28 b is bridged between one end portions of the yoke 22. The connecting member 28 c is bridged between the other ends of the yoke 22. The connecting member 28 is a substantially plate-like member that is rectangular in a front view and is thin in the Y-axis direction. As an example, the connecting member 28 is arranged so that the long side is along the X-axis direction and the short side is along the Z-axis direction when viewed from the front. The connecting member 28 can be formed from various magnetic materials or nonmagnetic materials. As an example, in the embodiment, the connecting member 28 is made of a steel material. The pair of yokes 22b, 22c and the pair of connecting members 28b, 28c are coupled in a cylindrical shape having a rectangular cross section surrounding the stator 10 in a side view. The yoke 22 and the connecting member 28 may be coupled by, for example, a bolt (not shown).

(Field magnet)
The pair of field magnet arrays 24b and 24c are fixed to the pair of yokes 22b and 22c, respectively, and are disposed facing each other in the Z-axis direction with the magnetic gap 34 interposed therebetween. The pair of field magnet arrays 24 b and 24 c form a field magnetic field in the magnetic gap 34. The field magnet array 24 includes a plurality of (for example, six) magnets 25 in which field magnetic poles are formed. The plurality of magnets 25 have opposing surfaces that face the magnetic gap 34.

  As an example, in the embodiment, the pair of field magnet arrays 24 b and 24 c are arranged symmetrically with the magnetic gap 34 interposed therebetween. The pair of field magnet arrays 24b and 24c may be disposed asymmetrically with the magnetic gap 34 interposed therebetween.

  The magnet 25 is, for example, a substantially plate-like permanent magnet that has a rectangular shape in plan view and is thin in the Z-axis direction. As an example, in the embodiment, the magnet 25 is arranged so that the long side is along the Y-axis direction and the short side is along the X-axis direction in plan view. The plurality of magnets 25 are arranged in the first direction at every constant magnetic pole pitch P. For example, the magnet 25 is magnetized in the Z-axis direction and outputs a magnetic flux in the Z-axis direction. The plurality of magnets 25 are arranged so that, for example, N poles and S poles appear alternately in the first direction. Of the plurality of magnets 25, one disposed at both ends in the first direction is referred to as an end magnet 25 b. Each end magnet 25 b is arranged next to the magnetism collecting member 26. The magnet 25 can be formed from various magnetic materials. As an example, in the embodiment, the magnet 25 is formed of an NdFeB-based bonded magnet material.

(Magnet collecting structure)
The magnetic flux collecting structure 30 is a magnetic structure that suppresses leakage of magnetic flux to the outside. In particular, the pair of magnetic flux collecting structures 30b and 30c are arranged at the end portions in the first direction of the pair of yokes 22b and 22c with the magnetic air gap 34 interposed therebetween, and a part of the magnetic flux formed by the field magnet array 24. To the magnetic gap 34. The magnetic flux collecting structure 30 includes a protruding end portion 22n and a magnetic flux collecting member 26 fixed to the protruding end portion 22n on the magnetic gap 34 side. The magnetic flux collecting member 26 includes a magnetic flux collecting member 26b fixed to the yoke 22b and a magnetic flux collecting member 26c fixed to the yoke 22c. The pair of magnetic flux collecting structures 30b and 30c may be arranged symmetrically with the magnetic gap 34 interposed therebetween.

(Magnet collecting member)
The pair of magnetic flux collecting members 26b and 26c face each other in the Z-axis direction with the magnetic air gap 34 interposed therebetween. The magnetic flux collecting member 26 is, for example, a substantially plate-like member that has a rectangular shape in plan view and is thin in the Z-axis direction. As an example, the magnetic flux collecting member 26 is arranged so that the long side is along the Y-axis direction and the short side is along the X-axis direction in plan view. The magnetic flux collecting member 26 can be formed from various magnetic materials. As an example, in the embodiment, the magnetic flux collecting member 26 is formed of a metal material having soft magnetism. The magnetic flux collecting member 26 is disposed next to the end magnet 25b.

  FIG. 5 is an explanatory diagram schematically illustrating the flow of magnetic flux at the end 20e of the mover 20 according to the embodiment. FIG. 6 is an explanatory diagram schematically showing the flow of magnetic flux in the mover 21 of the comparative example in which the projecting end portion 22n and the magnetic flux collecting member 26 are removed from the mover 20. The magnetic flux Fa output from the magnet 25 is divided into half on both sides in the first direction in the yoke 22 and flows to the magnet 25 arranged next to it. However, since there is no magnet 25 on the end side of the end magnet 25b, a part of the magnetic flux Fb flows along a path that jumps out from the end of the yoke 22, as shown in FIG. For this reason, a large peak of the leakage magnetic flux distribution is formed at the end 21e of the mover 21 of the comparative example. As shown in FIG. 5, the mover 20 has a magnetic flux collecting structure 30 including the protruding end portion 22 n and the magnetic collecting member 26, so that a part of the magnetic flux Fb of the end magnet 25 b is It flows along the magnetic flux collecting member 26 and is guided to the magnetic gap 34. For this reason, the magnetic flux jumping out from the end portion of the yoke 22 decreases, and the leakage magnetic flux is kept small at the end portion 20e of the mover 20.

The position and size of the magnetic flux collecting member 26 can be arbitrarily set according to a desired leakage magnetic flux distribution. According to the inventor's simulation, the following characteristics have been confirmed.
(1) Leakage magnetic flux can be reduced by increasing the overhang dimension Ln in the first direction of the overhang end 22n. For example, the overhanging dimension Ln in the first direction of the overhanging end 22n may be set within a range of 1/3 to 2 times the dimension Wm of the magnet 25 in the first direction, and more preferably the dimension Wm. You may set to 1/2 or more of these. In this range, it has been confirmed that the leakage flux can be reduced.

(2) By increasing at least one of the dimension Wc in the first direction of the magnetic flux collecting member 26, the dimension Hc in the second direction (Y-axis direction), and the dimension Dc in the Z-axis direction, the leakage magnetic flux is increased. Can be small. For example, the dimension Wc of the magnetism collecting member 26 in the first direction may be set to a range of 1/3 to 2 times the dimension Wm of the magnet 25 in the first direction, and more preferably 1/2 of the dimension Wm. You may set to 2 or more. In this range, it has been confirmed that the leakage flux can be reduced.

  As an example, in the embodiment, the dimension Wc in the first direction of the magnetism collecting member 26 is set to be substantially equal to the dimension Wm in the first direction of the magnet 25. The dimension Hc in the second direction of the magnetic flux collecting member 26 is set to be substantially equal to the dimension Hm in the second direction of the magnet 25. The dimension Dc in the Z-axis direction of the magnetic flux collecting member 26 is set substantially equal to the thickness Dm of the magnet 25 in the Z-axis direction. When the difference between one dimension and the other dimension is within 15%, both dimensions are said to be substantially equal.

(3) In the first direction, the leakage flux can be reduced by increasing the distance Pc from the center of the magnetism collecting member 26 to the center of the end magnet 25b. For example, the distance Pc may be set to a range of 1/2 or more and 2 or less of the magnetic pole pitch P of the magnet 25, more preferably 1 or more. In this range, it has been confirmed that the leakage flux can be reduced. As an example, in the embodiment, the distance Pc is set to ½ or more of the pitch P.

  The magnetic flux collecting member 26b and the magnetic flux collecting member 26c may have asymmetric shapes, but in the embodiment, the magnetic flux collecting member 26b and the magnetic flux collecting member 26c have symmetrical shapes. Specifically, the magnetic flux collecting member 26b is substantially equal to the magnetic flux collecting member 26c in the dimension in the first direction. The magnetic flux collecting member 26b is substantially equal to the magnetic flux collecting member 26c in the dimension in the second direction. The magnetic flux collecting member 26b is substantially equal to the magnetic flux collecting member 26c in the dimension in the Z-axis direction. When the difference between one dimension and the other dimension is within 15%, both dimensions are said to be substantially equal. As shown in FIG. 5, the magnetic flux collecting member 26 b and the magnetic flux collecting member 26 c are arranged symmetrically with the magnetic gap 34 interposed therebetween.

  Next, the operation of the linear motor 2 configured as described above will be described. When a drive current is supplied to the plurality of coils 12 from a drive circuit (not shown), a thrust in the first direction is generated in the mover 20 by the interaction between the drive current and the magnetic flux Fa formed by the magnet 25. The linear motor 2 drives the driven object in the first direction by this thrust.

Next, functions and effects of the linear motor 2 according to the embodiment will be described.
The linear motor 2 according to the embodiment includes a pair of yokes 22b and 22c and a pair of field magnet arrays 24b and 24c that are fixed to the pair of yokes 22b and 22c and face each other with a magnetic gap 34 interposed therebetween. The field magnet array 24 includes the mover 20 and includes a plurality of magnets 25 arranged in the first direction. The field magnet array 24 is formed at the ends of the pair of yokes 22b and 22c in the first direction. A magnetic flux collecting structure 30 is provided to guide a part of the magnetic flux to the magnetic gap 34. According to this configuration, the magnetic flux collecting structure 30 guides the magnetic flux from the field magnet array 24 to the magnetic air gap 34, so that the magnetic flux leaking outside from the end 20e of the mover 20 can be reduced.

  In the linear motor 2 according to the embodiment, the yoke 22 includes a main body portion 22m that fixes the field magnet array 24, and an overhanging end portion 22n that protrudes from the main body portion 22m in the first direction. The structure 30 includes a pair of magnetic flux collecting members 26b and 26c that are fixed to the projecting end 22n and face each other with the magnetic gap 34 interposed therebetween. According to this configuration, since the magnetic flux is collected in the magnetic flux collecting member 26 fixed to the magnetic gap 34 side of the overhanging end 22n, the magnetic flux is efficiently guided to the magnetic gap 34, and the magnetic flux leaking to the outside is further reduced. can do.

  In the linear motor 2 according to the embodiment, the plurality of magnets 25 are arranged at a constant pitch P, and adjacent to the magnetism collecting member 26 among the magnets 25 from the center of the magnetism collecting member 26 in the first direction. The distance to the center of the magnets arranged at is set to 1/2 or more of the pitch P. According to this configuration, the magnetic flux leaking to the outside can be reduced as compared with the case where the distance Pc is less than ½ of the distance P.

  In the linear motor 2 according to the embodiment, the pair of magnetic flux collecting structures 30b and 30c are arranged symmetrically with the magnetic gap 34 interposed therebetween. According to this configuration, the symmetry of the magnetic flux distribution in the magnetic gap 34 is improved as compared with the case where the pair of magnetic flux collecting structures 30b and 30c are arranged asymmetrically, which is caused by the unbalanced magnetic flux distribution. Magnetic flux leaking to the outside can be reduced.

  Next, the use of the linear motor 2 will be described. FIG. 7 is a plan view of the stage apparatus 100 using the linear motor 2 according to the embodiment. This stage apparatus 100 is called an XY stage, and positions an object in the X direction and the Y direction.

  The stage apparatus 100 mainly includes a Y stage 120, an X stage 130, and a surface plate 140. The Y stage 120 includes a pair of sliders 124. An X linear motor 2X that moves the X stage 130 in the X direction is provided between the pair of sliders 124. The X linear motor 2X includes a stator 10 that is horizontally mounted on a pair of sliders 124 and extends in the X direction, and a mover 20 that is movably supported by the stator 10 and coupled to the lower surface of the X stage 130. Prepare. Thus, by controlling the stator 10 of the X linear motor 2X, the X stage 130 is positioned in the X direction.

  A pair of Y linear motors 2Y are provided at both ends of the surface plate 140. Each Y linear motor 2Y includes a stator 10 and a mover 20. The slider 124 is fixed to the mover 20 of the Y linear motor 2Y. The Y stage 120 is positioned in the Y direction by controlling the stator 10 of the Y linear motor 2Y.

  The above is the configuration of the stage apparatus 100. The linear motor 2 according to the embodiment can be suitably used for the X linear motor 2X or the Y linear motor 2Y of the stage apparatus 100. The stage apparatus 100 can be used for positioning a wafer or a glass substrate in an exposure apparatus, or can be used for an actuator used in a scanning electron microscope (SEM).

  In the above, it demonstrated based on embodiment of this invention. It is to be understood by those skilled in the art that these embodiments are illustrative, and that various modifications and changes are possible within the scope of the claims of the present invention, and that such modifications and changes are also within the scope of the claims of the present invention. It is understood. Accordingly, the description and drawings herein are to be regarded as illustrative rather than restrictive.

  Hereinafter, modified examples will be described. In the drawings and description of the modified examples, the same reference numerals are given to the same or equivalent components and members as those of the embodiments. The description overlapping with each embodiment will be omitted as appropriate, the configuration different from each embodiment will be described with emphasis, and the overlapping description will be omitted.

[First Modification]
Next, the linear motor 4 according to the first modification will be described. FIG. 8 is a side view showing the linear motor 4. The linear motor 4 is different from the linear motor 2 according to the embodiment in that a magnetic flux collecting structure 32 is provided instead of the magnetic flux collecting structure 30, and the other configurations are the same. Therefore, the periphery of the magnetic flux collecting structure 32 will be described mainly.

  FIG. 9 is a front view showing the periphery of the magnetic flux collecting structure 32. In the linear motor 4, the surrounding structure 72 is included in the magnetism collecting structure 32. FIG. 10 is a perspective view illustrating the surrounding member 72. The surrounding member 72 includes a pair of magnetism collecting members 76b and 76c and a pair of connecting members 74d and 74e. When the pair of magnetic flux collecting members 76b and 76c are collectively referred to as a magnetic flux collecting member 76. When the pair of connection members 74d and 74e are summarized, they are referred to as connection members 74. The magnetic flux collecting member 76 corresponds to the magnetic flux collecting member 26. The magnetic flux collecting member 76b and the projecting end portion 22n constitute a magnetic flux collecting structure 32b. The magnetic flux collecting member 76c and the overhang end portion 22n constitute a magnetic flux collecting structure 32c. The magnetic flux collecting structures 32b and 32c have the same characteristics as the magnetic flux collecting structures 30b and 30c described above.

  The surface fixed to the yoke 22 of the magnetic flux collecting member 76 extends in the first direction and the second direction orthogonal to the first direction. The pair of connection members 74d and 74e are arranged apart from each other in the second direction with the magnetic gap 34 interposed therebetween. The pair of connection members 74d and 74e and the pair of magnetic flux collecting members 76b and 76c are connected in a state of being disposed so as to surround the magnetic gap 34. The connecting member 74d connects one end of the pair of magnetic flux collecting members 76b and 76c in the Y-axis direction, and the connecting member 74e connects the other end of the pair of magnetic flux collecting members 76b and 76c in the Y-axis direction. doing.

  The magnetic flux collecting member 76 is different from the magnetic flux collecting member 26 in that it is connected to the connecting member 74, and the other features are the same as those of the magnetic flux collecting member 26. The contents described above for the magnetic flux collecting member 26 can be referred to. . The magnetic flux collecting member 76 is mainly disposed so as to face the intermediate portion 18m of the coil unit 18 in the Z-axis direction. The connection member 74 is mainly disposed so as to surround two surfaces in the Z-axis direction and one surface in the Y-axis direction of the edge portion 18d of the coil unit 18. The pair of magnetism collecting members 76 b and 76 c and the pair of connection members 74 d and 74 e are arranged so as to surround the magnetic gap 34 and the stator 10. As an example, in the surrounding member 72, a pair of magnetism collecting members 76b and 76c and a pair of connecting members 74d and 74e are integrally formed.

  The surrounding member 72 is provided with an opening 72h through which the coil unit 18 is inserted. The opening 72h has a substantially I-letter shape that is long in the Y-axis direction when viewed from the side. In the state where the surrounding member 72 is attached to the yoke 22, the opening 72 h becomes a part of the magnetic gap 34. The surrounding member 72 can be formed from various magnetic materials. As an example, the surrounding member 72 is formed of a metal material having soft magnetism. The surrounding member 72 may be configured by combining a plurality of members formed separately.

  The linear motor 4 which concerns on a 1st modification has an effect | action and effect similar to the linear motor 2 which concerns on embodiment.

  In the linear motor 4 of the first modified example, the surface of the magnetic flux collecting member 76 fixed to the yoke 22 extends in the first direction and the second direction orthogonal to the first direction, and the first is located across the magnetic gap 34. A pair of connection members 74d and 74e arranged in two directions are provided, and the pair of connection members 74d and 74e and the pair of magnetism collecting members 76b and 76c are connected in a state of being arranged so as to surround the magnetic gap 34. Has been. According to this configuration, the leakage flux can be further reduced by providing the connection members 74d and 74e. Since a part of the magnetic flux of the end magnet 25b flows from the overhanging end portion 22n along the pair of magnetic flux collecting members 76b and 76c and the connecting members 74d and 74e, the magnetic flux jumping from the end face of the yoke 22 is further reduced. It is.

  In the linear motor 4 of the first modification, the pair of magnetic flux collecting members 76b and 76c and the pair of connection members 74d and 74e are integrally formed. According to this structure, compared with the case where each member is formed separately and joined, the labor of joining is reduced and productivity is improved.

(Second modification)
In the embodiment, the example in which the opposing surfaces of the magnetic flux collecting members 26b and 26c are parallel and flat plate-like members has been described, but the present invention is not limited to this. The facing surface of each magnetism collecting member may include an uneven surface or an inclined surface. FIG. 11 is a front view showing the periphery of the pair of magnetic flux collecting members 56b and 56c of the linear motor 5 according to the second modification. The linear motor 5 differs from the linear motor 2 in the shape of the magnetic flux collecting member, and the other configurations are the same. The facing surfaces of the pair of magnetic flux collecting members 56b and 56c include an inclined surface 56h in which the facing gap increases as the end magnet 25b is approached. The magnetic flux collecting member 56b and the overhang end portion 22n constitute a magnetic flux collecting structure 30b. The magnetic flux collecting member 56c and the projecting end portion 22n constitute a magnetic flux collecting structure 30c. The linear motor 5 according to the second modification has the same operations and effects as the linear motor 2 according to the embodiment.

(Third Modification)
FIG. 12 is a front view showing the periphery of the pair of magnetic flux collecting members 57b and 57c of the linear motor 6 according to the third modification. The linear motor 6 is different from the linear motor 2 in the shape of the magnetic collecting member, and the other configurations are the same. The opposing surfaces of the pair of magnetic flux collecting members 57b and 57c include an inclined surface 57h in which the opposing gap decreases as the end magnet 25b is approached. The magnetic flux collecting member 57b and the overhanging end portion 22n constitute a magnetic flux collecting structure 30b. The magnetic flux collecting member 57c and the overhanging end portion 22n constitute a magnetic flux collecting structure 30c. The linear motor 6 according to the third modification has the same operations and effects as the linear motor 2 according to the embodiment.

(Fourth modification)
In the embodiment, the example in which the magnetic flux collecting members 26b and 26c are integral members has been described. However, the present invention is not limited to this. Each magnetism collecting member may be composed of a plurality of members. FIG. 13 is a front view showing the periphery of the pair of magnetic flux collecting members 66b and 66c of the linear motor 7 according to the fourth modification. The linear motor 7 is different from the linear motor 2 in the shape of the magnetic flux collecting member, and the other configurations are the same. Each of the pair of magnetic flux collecting members 66b and 66c is composed of two members, a member 66h and a member 66j. The dimension in the Z-axis direction of the member 66h is larger than the dimension in the Z-axis direction of the member 66j. The member 66j is provided on the end magnet 25b side of the member 66h. The magnetic flux collecting member 66b and the overhanging end portion 22n constitute a magnetic flux collecting structure 30b. The magnetic flux collecting member 66c and the overhang end portion 22n constitute a magnetic flux collecting structure 30c. The linear motor 7 according to the fourth modification has the same operations and effects as the linear motor 2 according to the embodiment.

(5th modification)
FIG. 14 is a front view showing the periphery of the pair of magnetic flux collecting members 67b and 67c of the linear motor 8 according to the fifth modification. The linear motor 8 is different from the linear motor 2 in the shape of the magnetic collecting member, and the other configurations are the same. Each of the pair of magnetic flux collecting members 67b and 67c includes two members, a member 67h and a member 67j. The dimension in the Z-axis direction of the member 67h is larger than the dimension in the Z-axis direction of the member 67j. The member 66h is provided on the end magnet 25b side of the member 67j. The magnetic flux collecting member 67b and the projecting end portion 22n constitute a magnetic flux collecting structure 30b. The magnetic flux collecting member 67c and the overhanging end portion 22n constitute a magnetic flux collecting structure 30c. The linear motor 8 according to the fifth modification has the same operations and effects as the linear motor 2 according to the embodiment.

(Other variations)
In the embodiment, the example including the connecting member 28b that connects between one ends of the pair of yokes 22b and 22c and the connecting member 28c that connects between the other ends has been described, but the present invention is not limited thereto. . For example, the other end portion may be disconnected without providing the connecting member 28c.

  In the embodiment, the example in which the magnetic flux collecting structure 30 includes the magnetic flux collecting member 26 has been described. However, the present invention is not limited to this. For example, by increasing the overhang dimension Ln (see FIG. 5) of the overhang end portion 22n in the first direction within a predetermined range, the leakage magnetic flux can be reduced even in the configuration not including the magnetic flux collecting member 26. Can do. In this case, the overhanging dimension Ln of the overhanging end 22n in the first direction may be set to a range of 1/3 to 2 times the dimension Wm of the magnet 25 in the first direction, preferably the dimension Wm. May be set to 1/2 or more, more preferably set to a dimension Wm or more, and more preferably set to a pitch P or more. In this range, it has been confirmed that the leakage flux can be reduced. The linear motor according to these modified examples has the same operations and effects as the linear motor 2 according to the embodiment.

  In the drawings used for the description, in order to clarify the relationship between members, the cross sections of some members are hatched. However, the hatching does not limit the materials and materials of these members.

  2 .... Linear motor, 10 .... Stator, 12 .... Coil, 18 .... Coil unit, 20 .... Movable, 22 .... Yoke, 22n ..., Overhang end, 24 ..., Field magnet array, 25 .. Magnet, 26 .. Magnetic collecting member, 28 .. Connecting member, 30 .. Magnetic collecting structure, 34 .. Magnetic gap, 74 .. Connecting member, 76 .. Magnetic collecting member, 100. .

Claims (7)

A mover including a pair of yokes and a pair of field magnet rows fixed to the pair of yokes and facing each other with a magnetic gap therebetween,
The field magnet array includes a plurality of magnets arranged in a first direction,
The linear motor according to claim 1, wherein a magnetic flux collecting structure that guides a part of the magnetic flux formed by the field magnet array to the magnetic air gap is provided at an end portion in the first direction of the pair of yokes. The yoke has a main body portion that fixes the field magnet row, and an overhanging end portion that projects from the main body portion in the first direction,
2. The linear motor according to claim 1, wherein the magnetic flux collecting structure includes a pair of magnetic flux collecting members fixed to the projecting end portion and facing each other with the magnetic gap interposed therebetween. The plurality of magnets are arranged at a constant pitch,
In the first direction, a distance from the center of the magnetic flux collecting member to the center of the magnets arranged next to the magnetic flux collecting member among the plurality of magnets is set to ½ or more of the pitch. The linear motor according to claim 2.   4. The linear motor according to claim 2, wherein the pair of magnetic flux collecting structures are arranged symmetrically with the magnetic gap interposed therebetween. The surface of the magnetic flux collecting member fixed to the yoke extends in a first direction and a second direction orthogonal to the first direction,
A pair of connecting members disposed apart in the second direction across the magnetic gap,
5. The linear motor according to claim 2, wherein the pair of connection members and the pair of magnetic flux collecting members are connected in a state of being disposed so as to surround the magnetic gap.   The linear motor according to claim 5, wherein the pair of magnetism collecting members and the pair of connection members are integrally formed.   A stage apparatus comprising the linear motor according to claim 1.

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