TWI594545B - Line of the motor, the stage device - Google Patents

Description

Linear motor, stage device

The present application claims priority based on Japanese Patent Application No. 2015-045543, filed on Mar. All contents of this Japanese application are incorporated herein by reference.

The present invention relates to a linear motor.

A linear motor is utilized in order to convert electrical energy into linear motion. Figure 1 is a perspective view of a conventional linear motor. As shown in Fig. 1, the linear motor 2r includes a movable member 10 and a stator 20r. The stator 20r includes a pair of yokes (back yokes) 22a and 22b that face each other so as to sandwich the movable element 10, and an inner side surface S1a and S1b of the back yokes 22a and 22b that follow the movable member 10; A plurality of field magnets 24 are provided in the moving direction (X-axis direction). The plurality of field magnets 24 are attached such that the N poles and the S poles alternately appear in accordance with a predetermined magnetic pole pitch. The yoke 22 and the field magnet 24 form a magnetic circuit.

2(a) and 2(b) are perspective views of the stator 20r. In the linear motor 2r having a large moving range of the movable member, the yoke 22 needs to be lengthened. However, in this case, it is difficult to form the elongated yoke 22 as a whole in terms of cost and processing accuracy, and thus Most cases Next, as shown in Fig. 2(a), a plurality of short yokes 23 are formed, and as shown in Fig. 2(b), the elongate yokes 22 are formed by joining them.

3(a) and 3(b) are plan views of the yoke 22. As shown in Fig. 3(a), when the short yokes 23 are coupled to each other to form the elongated yoke 22, gaps formed by the manufacturing variations of the yokes 23 occur in the connecting portions 25 ( Air layer) 26. This gap 26 becomes a portion having a high magnetic resistance (and thus a low magnetic permeability).

The magnetic flux Φ generated by the field magnet 24 flows into the adjacent field magnet 24 through the yoke 22. However, in the case where the yoke 22 is not a unitary body and has a joint structure, the magnetic flux Φ cannot pass through the portion of the joint portion 25 where the magnetic resistance is high, and a part of the magnetic flux Φ _EXT leaks to the outside of the yoke 22. Alternatively, as shown in Fig. 3(b), when the surface of the yoke 23 is subjected to a plating treatment, the plating 27 becomes a portion having a high magnetic resistance and causes a leakage magnetic field.

Patent Document 1 discloses a technique for reducing a leakage magnetic field by working on the shape of a joint portion of a yoke.

(previous technical literature) (Patent Literature)

Patent Document 1: Japanese Unexamined Patent Publication No. 5-8793

The leakage magnetic flux density of a conventional linear motor is about several tens of mT. It is not a problem in many applications, but in applications where a magnetic field such as an electron beam device affects an object, it is expected to reduce the leakage magnetic field to a lower level.

The present invention has been made in view of such problems, and one of its exemplary objects is to provide a linear motor in which a leakage magnetic field is reduced.

One aspect of the invention pertains to linear motors. The linear motor has a movable member and a stator formed by connecting a plurality of magnetic circuits in a moving direction of the movable member. The magnetic circuit includes a yoke and a plurality of field magnets fixed to the yoke. A high magnetic permeability member having a magnetic permeability higher than that of the yoke is provided at a joint portion of the adjacent magnetic circuits so as to straddle the joint portion.

In this aspect, a path having a low magnetic resistance is formed by providing a high magnetic permeability member at the joint portion to bypass a portion having a high magnetic resistance generated at the joint portion. Thereby, the amount of magnetic flux leaking to the outside of the yoke can be reduced.

The high permeability member may overlap at least a portion of the field magnet of the magnetic circuit at both ends thereof.

Thereby, the magnetic flux generated by the field magnet can be guided to the inside of the high magnetic permeability member, so that the leakage magnetic field can be reduced.

The high permeability member can be buried in the yoke.

Thereby, the area in which the high magnetic permeability member contacts the yoke can be increased, so that more magnetic flux can be guided to the inside of the high magnetic permeability member.

The high magnetic permeability member may be disposed on the surface of the yoke. In this case, the assembly of the magnetic circuit can be easily performed.

The yoke may include a pair of back yokes disposed opposite each other in such a manner as to sandwich the movable member from a direction perpendicular to the moving direction. A plurality of field magnets may be disposed on the inner side of the back yoke. A concave portion that is fitted to the high magnetic permeability member may be formed on the side surface of the end portion of the back yoke.

The yoke may include a pair of back yokes disposed opposite each other in such a manner as to sandwich the movable member from a direction perpendicular to the moving direction. A plurality of field magnets may be disposed on the inner side of the back yoke. The high magnetic permeability member may be disposed on an outer side surface of the adjacent back yoke.

In this case, the assembly of the magnetic circuit can be easily performed.

A groove may be provided on the outer side surface of the back yoke, and the high magnetic permeability member may be buried in the groove.

Thereby, the assembly accuracy when the high magnetic permeability member is mounted on the back yoke can be improved, and the back yoke and the high magnetic permeability member can be placed on the same horizontal plane, so that the leakage magnetic field can be reduced.

The high permeability member may be plate-shaped. The high permeability member may also be in the form of a rod.

Another aspect of the invention pertains to a stage device. The stage device may be provided with any one of the above linear motors.

Further, any combination of the above constituent elements, constituent elements of the present invention, and a method of replacing each other among methods, apparatuses, systems, and the like are also effective as aspects of the present invention.

According to the present invention, the leakage magnetic field can be reduced.

2‧‧‧Linear motor

10‧‧‧ movable parts

20‧‧‧ Stator

22‧‧‧Y yoke

24‧‧ field magnet

30‧‧‧ Magnetic circuit

40‧‧‧High permeability components

42‧‧‧ recess

44‧‧‧ slots

46‧‧‧ holes

50‧‧‧High permeability component

S1‧‧‧ inside side

S2‧‧‧ end side

S3‧‧‧ outside side

Figure 1 is a perspective view of a conventional linear motor.

2(a) and 2(b) are perspective views of the stator.

3(a) and 3(b) are plan views of the yoke.

4(a) and 4(b) are views showing the stator of the linear motor of the first embodiment.

Figure 5 is an assembly view of the stator.

Figure 6 is a plan view of the stator.

7(a) and 7(b) are perspective views of the stator of the first modification.

Fig. 8 is a perspective view of a stator according to a second modification.

Figs. 9(a) and 9(b) are views showing the stator of the linear motor of the second embodiment.

10(a) and 10(b) are perspective views of the stator of the third and fourth modifications.

Fig. 11 is a perspective view of the stator of the fifth modification.

12(a) and 12(b) are cross-sectional views of the stator of the sixth modification.

Fig. 13 is a plan view showing a stage device using a linear motor of the embodiment.

Hereinafter, based on the preferred embodiments, the present invention will be described with reference to the drawings. Description. The same or equivalent constituent elements, members, and processes shown in the drawings are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Further, the embodiments are not limited to the invention, and all the features and combinations described in the embodiments are not necessarily essential to the invention.

(First embodiment)

4(a) and 4(b) are views showing the stator 20 of the linear motor of the first embodiment. The stator 20 is configured by connecting a plurality of magnetic circuits 30 in a moving direction (X-axis direction) of the mover. The magnetic circuit 30 includes a yoke 22 and a plurality of field magnets 24 fixed to the yoke 22. The connecting portion 32 of the adjacent magnetic circuit 30 is provided with a high magnetic permeability member 40 having a magnetic permeability higher than that of the yoke 22 so as to straddle the connecting portion 32.

In the present embodiment, the plate-shaped high magnetic permeability member 40 is buried in the yoke 22. Fig. 5 is an assembled view of the stator 20. In Fig. 5, only one of the pair of back yokes 22a, 22b, that is, 22a, is disposed oppositely in such a manner as to sandwich the movable member from a direction (Y direction) perpendicular to the moving direction (X-axis direction). The other 22b is omitted. The field magnet 24 is provided on the inner side surface S1a of the back yoke 22a. The end side faces (joining faces) S2a of the respective back yokes 22a of the adjacent magnetic circuits 30 are in contact with each other. A concave portion 42 that is fitted to the high magnetic permeability member 40 is formed on the end side surface S2a of the back yoke 22a. The adjacent magnetic circuits 30 are connected in a state in which the high magnetic permeability members 40 are fitted in the respective concave portions 42. The back yoke 22b side is also configured in the same manner.

The material of the high magnetic permeability member 40 is not particularly limited, and the material having a higher magnetic permeability than the yoke 22 may be selected depending on the material of the yoke 22. As the yoke 22, for example, an iron material (SS400) having a specific permeability μ/μ ₀ = 1000 or a low carbon steel is used. In this case, as the high magnetic permeability member 40, the specific permeability (magnetic permeability) is selected as compared with the magnetic yoke. High materials such as pure iron, high magnetic permeability alloy (μ/μ ₀ = 8000, μ = 1.0 × 10 ^-2 H/m) or iron-cobalt alloy can be used. In the case where a high magnetic permeability alloy is used as the yoke 22, a material having a magnetic permeability higher than that such as iron-cobalt alloy or pure iron having a higher purity can be used.

The above is the configuration of the stator 20 of the first embodiment. Next, the advantages will be described.

Fig. 6 is a plan view of the stator 20. The magnetic flux Φ is shown by a dotted line in Fig. 6. The magnetic permeability of the high magnetic permeability member 40 is larger than the magnetic permeability of the yoke 22, and therefore the magnetic flux density B1 passing through the inside of the high magnetic permeability member 40 is larger than the magnetic flux density B2 passing through the inside of the yoke 22. In other words, the magnetic flux Φ generated by the field magnet 24 is concentrated in the high magnetic permeability member 40. Thereby, in the conventional configuration shown in FIG. 3, the magnetic flux Φ leaking from the yoke 23 to the outside can be reduced.

The above is the advantage and effect of the stator 20 of the first embodiment.

In order to improve this advantage and effect, it is important to efficiently guide the magnetic flux Φ generated by the field magnet 24 to the inside of the high magnetic permeability member 40. Therefore, it is preferable to overlap both ends of the high magnetic permeability member 40 and at least a part of the field magnet 24 of the magnetic circuit 30. More preferably, the high magnetic permeability member 40 is preferably overlapped by 1/4 or more of the width W of the field magnet 24 in the moving direction (X-axis direction), and more preferably 1/2 or more. That is, when the overlap width is set to W _OL , W _OL W/2 is preferred.

Further, the high magnetic permeability member 40 is preferably overlapped with at least a part of the field magnet 24 in the height direction (Z direction). In the present embodiment, since the height h of the high magnetic permeability member 40 is higher than the height H of the field magnet 24, the magnetic flux from the back surface (the contact surface with the yoke 22) of the field magnet 24 passes through the high conductivity in the height direction. Magnetic component 40.

By specifying the size of the high magnetic permeability member 40 and the arrangement relationship with the field magnet 24 in this manner, the leakage magnetic field can be appropriately reduced.

(First Modification)

Next, a modification related to the first embodiment will be described. 7(a) and 7(b) are perspective views of the stator 20 of the first modification. In this modification, the height h of the high magnetic permeability member 40 is substantially equal to the height H of the field magnet 24. Also in this modification, the same effects as those of the embodiment can be obtained.

(Second modification)

Fig. 8 is a perspective view of the stator 20 of the second modification. In this modification, the high magnetic permeability member 40 has a rod shape. A plurality of holes (recesses) 46 are provided in the end side faces S2 of the back yokes 22a and 22b. The high permeability member 40 is inserted into the corresponding hole 46. Also in this modification, the same effects as those of the embodiment can be obtained.

(Other variants)

Further, the shape of the high magnetic permeability member 40 is not limited to a plate shape or a rod shape, and may be any shape. Further, the number of the high magnetic permeability members 40 provided in each of the joint portions is also not particularly limited.

(Second embodiment)

Figs. 9(a) and 9(b) are views showing the stator 20 of the linear motor of the second embodiment. In the first embodiment, the high magnetic permeability member 40 is embedded in the yoke 22. In contrast, in the second embodiment, the high magnetic permeability member 50 is attached to the surface of the yoke 22.

Specifically, the high magnetic permeability member 50 is provided on the outer side surface S3 of each of the back yokes 22a and 22b. Grooves 44 are provided at the ends of the outer side faces S3 of the back yokes 22a, 22b. The high permeability member 50 is buried in the groove 44. As shown in Fig. 9(b), the surface of the high magnetic permeability member 50 and the surface of the back yoke 22a (22b) are preferably in the same horizontal plane in a stepless manner. By eliminating the step difference between the high magnetic permeability member 50 and the back yoke 22a (22b), it is possible to reduce the leakage magnetic field from the step, that is, the discontinuous portion.

According to the second embodiment, by providing the high magnetic permeability member 50 having a high magnetic permeability on the surface of the yoke 22 in the connection portion of the magnetic circuit 30, the magnetic flux density inside the high magnetic permeability member 50 is increased, and the yoke 22 is external. The magnetic flux density is relatively low. That is, the magnetic flux that is to be leaked from the surface of the yoke 22 to the outside can be introduced into the inside of the high magnetic permeability member 50, whereby the leakage magnetic field can be reduced.

Further, the second embodiment has an advantage that the assembly of the stator 20 can be easily performed as compared with the first embodiment.

(Third and fourth modifications)

Next, a modification related to the second embodiment will be described. 10(a) and 10(b) are perspective views of the stator 20 of the third and fourth modifications. In the third modification of the tenth (a)th diagram, the height h of the high magnetic permeability member 50 is substantially equal to the height H of the field magnet 24. Also in this modification, the same effects as those of the embodiment can be obtained.

In the fourth modification of the tenth (b) diagram, the high magnetic permeability member 50 covers the outer side surfaces S3a and S3b of the back yokes 22a and 22b and the bottom surface S4 of the yoke 22 at the connection portion of the adjacent magnetic circuit 30. Way has " According to this modification, since only one of the high magnetic permeability members 50 used in one connection portion is sufficient, assembly can be performed more easily, and the leakage magnetic field from the bottom surface of the yoke 22 can also be reduced.

(Fifth Modification)

Fig. 11 is a perspective view of the stator 20 of the fifth modification. The stator 20 includes a first high magnetic permeability member 40 and a second high magnetic permeability member 50. As described in the first embodiment, the first high magnetic permeability member 40 is buried inside the yoke 22. As described in the second embodiment, the second high magnetic permeability member 50 is provided on the surface of the yoke 22. By using the high magnetic permeability member 40 and the high magnetic permeability member 50 in combination, the leakage magnetic field can be further reduced.

(Sixth Modification)

12(a) and 12(b) are cross-sectional views of the stator 20c according to the sixth modification. In the above embodiment or modification, one magnetic circuit 30 The yoke 22 of the word shape is configured as one module. In the sixth modification, the yoke 22c is configured by connecting a plurality of portions 70 and 72. Screws can be used for the connection. Adhesives can also be used with mechanical bonding methods such as 74.

For example, one of the plurality of portions 70 may have a cross-sectional shape of an L shape, and the other 72 may have a cross-sectional shape of an I-shape. A high magnetic permeability member 78 having a magnetic permeability higher than that of the yoke 22c is provided at a joint surface 76 of the plurality of portions 70 and 72 so as to be orthogonal to and across the joint surface 76. The high magnetic permeability member 78 may be plate-shaped.

In the modification of Fig. 12(a), the high magnetic permeability member 78 is attached to " The bottom of the yoke 22c of the shape of the word. The length L of the high magnetic permeability member 78 is longer than the length l _{1 of the} bottom portion. The concave portion 80 fitted to the high magnetic permeability member 78 is formed in the I-shaped portion 72. The portions 70 and 72 are The state in which the high magnetic permeability member 78 is fitted to the concave portion 80 is coupled. The depth l _{2 of the} concave portion 80 can be defined as l ₁ + l ₂ ≒ L. Considering the thickness d _{1 of the} I-shaped portion 72 and the strength, high magnetic permeability member The thickness d ₂ , the strength, and the like of 78 may be determined as the depth l ₂ .

According to this variant, even if " The word-shaped yoke 22c is designed to be divided into a plurality of portions, and the leakage magnetic flux in the joint portion can also be reduced, and the integrated type " Compared with the yoke 22 of the word shape, it is possible to achieve performance that is not inferior.

In the Fig. 12(b), the L-shaped portion 70 and the I-shaped portion 72 are different in the form of division, and the others are the same.

In this modification, the two portions 70 and 72 are divided, but the shape is not particularly limited. For example, you can The center of the bottom surface of the yoke 22c of the word shape is divided into two L-shaped portions, or divided into three or more portions.

Further, in the sixth modification, the high magnetic permeability member 78 is attached to the bottom surface of the portion 70 of the yoke 22c. However, the present invention is not limited thereto, and the groove may be formed as shown in FIG. 9 or FIG. 44 and a high permeability member 78 is embedded in the groove 44.

Further, the shape of the high magnetic permeability member 78 is not limited to a plate shape or a rod shape, and may be any shape. Further, the number of the high magnetic permeability members 78 provided on each of the joint faces 76 is also not particularly limited.

In the first or second embodiment and the first to fifth modifications, it can be understood that one long yoke is divided into a plurality of pieces in each magnetic path in the moving direction of the movable member. Therefore, the following technical ideas can be derived from the entire specification.

One aspect of the invention pertains to a linear motor having a mover and a stator. The yoke may be configured to be divided into a plurality of sections. The yoke may be provided with a high magnetic permeability member which is disposed orthogonally and across the joint faces of the plurality of portions and has a magnetic permeability higher than a plurality of portions of the yoke.

Finally, the use of the linear motor 2 will be described. Fig. 13 is a plan view showing a stage device 100 using the linear motor 2 of the embodiment. The stage device 100 is referred to as an XY stage, and positions the object in the X direction and the Y direction.

The stage device 100 mainly includes a Y stage 120 and an X stage. 130 and platform 140. The Y stage 120 includes a pair of sliders 124 and a transverse mounting member 122 that is laterally disposed between the pair of sliders 124. The X-axis motor 2X that moves the X stage 130 in the X direction is provided on the lateral mounting member 122. The X linear motor 2X includes a stator 20 that is fixed to the lateral mounting member 122 and extends in the X direction, and a movable member (coil) 10 that is coupled to the lower surface of the X stage 130. Thus, by controlling the movable member 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 platform 140. The Y linear motor 2Y includes a movable member 10 and a stator 20, respectively. The slider 124 is fixed to the stator 20 of the Y linear motor 2Y. The Y stage 120 is positioned in the Y direction by controlling the movable member 10 of the Y linear motor 2Y.

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

The present invention has been described with reference to specific embodiments, but the embodiments are merely illustrative of the principles and applications of the present invention, and the embodiments are to be construed as being limited to the scope of the invention as defined in the appended claims. Modifications and changes in configuration.

20‧‧‧ Stator

22‧‧‧Y yoke

22a, 22b‧‧‧ Back yoke

24‧‧ field magnet

30‧‧‧ Magnetic circuit

32‧‧‧Connecting Department

40‧‧‧High permeability components

42‧‧‧ recess

Claims (10)

A linear motor comprising: a movable member; and a stator formed by connecting a plurality of magnetic circuits in a moving direction of the movable member, wherein the linear motor is characterized in that: the magnetic circuit includes: a yoke; and is fixed to the foregoing The plurality of field magnets of the yoke are provided with a high magnetic permeability member having a magnetic permeability higher than that of the yoke so as to straddle the connecting portion at a connecting portion of the adjacent magnetic paths. The linear motor of claim 1, wherein the high magnetic permeability member overlaps at least a portion of the field magnet of the magnetic circuit at both ends thereof. The linear motor according to claim 1 or 2, wherein the high magnetic permeability member is embedded in the yoke. The linear motor according to claim 1 or 2, wherein the high magnetic permeability member is provided on a surface of the yoke. The linear motor of claim 1 or 2, wherein the yoke includes a pair of back yokes opposite to each other in such a manner as to sandwich the movable member from a direction perpendicular to the moving direction, the plurality of fields The magnet is disposed on an inner side surface of the back yoke, and a concave portion that is fitted to the high magnetic permeability member is formed on an end surface side of the back yoke. The linear motor of claim 1 or 2, wherein the yoke includes a pair of back yokes opposite to each other in such a manner as to sandwich the movable member from a direction perpendicular to the moving direction, the plurality of fields The magnet is disposed on an inner side surface of the back yoke, and the high magnetic permeability member is disposed on an outer side surface of the back yoke. The linear motor according to claim 5, wherein a groove is provided on an outer side surface of the back yoke, and the high magnetic permeability member is buried in the groove. A stage device comprising the linear motor according to any one of claims 1 to 7. A linear motor having a movable member and a stator, wherein the linear motor includes: a yoke formed by dividing into a plurality of portions; and a method of arranging orthogonally and across a joint surface of the plurality of portions And the magnetic permeability is higher than the high permeability member of the aforementioned plurality of portions. A stage apparatus comprising the linear motor of claim 9 of the patent application.