TW201735500A - Linear motor and stage device - Google Patents

Abstract

In this linear motor, a stator 20 includes: a field magnet 24 that is provided facing a movable element; a base yoke 28 that is provided on a first direction side, removed from the field magnet 24; and a back yoke 23a to which the field magnet 24 is fixed. The back yoke 23a is fixed to an end surface 28a of the base yoke 28 by fastening a fastening implement to a fastening section, said fastening section being provided to the end surface 28a of the base yoke 28. When the back yoke 23a is a lever and a magnetic attractive force that the field magnet 24 generates is a load at a point of effort, the fastening section sandwiches a fulcrum manifesting on the end surface 28 and exhibits a fastening force that is a load at a point of load to balance with the load at the point of effort, and the fastening section is provided to the opposite side as the side on which the fulcrum manifests, when the end surface 28 is bisected in the first direction.

Description

Linear motor, stage device

The present invention relates to a linear motor.

A linear motor can be utilized to convert electrical energy into linear motion. For example, Patent Document 1 describes a linear motor including a fixing member and a movable member that are disposed to face each other via a magnetic gap.

The linear motor described in Patent Document 1 includes a flat-plate field yoke and a plurality of field magnets arranged and fixed to the field yoke on the fixing member. The field yoke includes a center yoke and a pair of side yokes extending upward from both ends of the center yoke, and a plurality of field magnets are fixed to respective inner side faces of the pair of side yokes. The linear motor described in Patent Document 1 works on the shape of the center yoke, thereby reducing the amount of deflection of the side yoke.

(previous technical literature) (Patent Literature)

Patent Document 1: Japanese Laid-Open Patent Publication No. 2005-237087

Regarding the fixing member including the base yoke and the linear motor that extends the rear yoke from both ends of the base yoke to the upper side, it is conceivable to fasten the rear yoke to both end faces of the respective base yokes by bolts. However, in the case of such a configuration, if the fastening force of the bolt is insufficient, there is a problem that the rear yoke is tilted inward due to the magnetic attraction force of the field magnet provided on the inner side surface of the rear yoke. If the rear yoke is tilted inward, the passage of the movable member is narrowed, and in the worst case, there is a concern that the movable member is in contact with the field magnet.

In the linear motor of such a configuration, in order to reduce the tilting of the rear yoke due to the magnetic attraction force of the field magnet, it is conceivable to increase the number of fastening bolts to increase the overall fastening force. However, if the number of fastening bolts is increased, there is a problem that the weight of the linear motor increases, or the number of processing of the number of holes or the number of fastenings of the fastening bolts increases, and productivity is lowered.

In other words, in the conventional linear motor, there is room for improvement from the viewpoint of suppressing the weight increase or the decrease in productivity while suppressing the collapse of the rear yoke due to the attraction force of the field magnet.

An object of the present invention is to provide a linear motor capable of suppressing the fall of the rear yoke due to the attraction force of the field magnet while suppressing an increase in weight or a decrease in productivity.

In order to solve the above problems, a linear motor of the present invention is provided with a fixing member including a field magnet disposed opposite to the movable member, and The base yoke provided by the field magnet separated from the first direction side and the rear yoke of the field magnet are fixed. The rear yoke is coupled with a fastener at a fastening portion provided on an end surface of the base yoke, thereby being fixed to an end surface of the base yoke, and the rear yoke is set as a lever and the magnetic attraction force generated by the field magnet is used as a force. At the point load, the fastening portion exerts a fastening force that is present at the fulcrum of the end face and acts as a load point for balancing the load with the force point, and the fastening portion is provided to divide the end face into two parts in the first direction. In the case of the opposite side of the side of the fulcrum.

According to this aspect, since the fastening portion is provided on the opposite side of the end surface on the side of the fulcrum, the distance between the fastening portion and the fulcrum can be increased.

Another stage device of the present invention includes the linear motor described above.

According to the present invention, it is possible to provide a linear motor capable of suppressing the tilting of the rear yoke due to the attraction force of the field magnet.

2‧‧‧Linear motor

10‧‧‧ movable parts

20‧‧‧Fixed parts

23a‧‧‧Back yoke

24‧‧‧Excitation magnet

25‧‧‧Main magnet

26‧‧‧Auxiliary pole magnet

28‧‧‧ base yoke

28h‧‧‧ Hole Department

29‧‧‧Bolts

100‧‧‧stage device

Fig. 1 is a perspective view of a linear motor of an embodiment.

Fig. 2 is a plan view showing a fixing member of the embodiment.

Fig. 3 is a cross-sectional view showing a fixing member of the embodiment.

Fig. 4 is a cross-sectional view showing a base yoke of the embodiment.

Fig. 5 is a cross-sectional view showing a fixing member of a comparative example.

Fig. 6 is a cross-sectional view showing a base yoke of a comparative example.

Figure 7 is a plan view of the stage device using the linear motor of the embodiment. Surface map.

Fig. 8 is a cross-sectional view showing a fixing member of a first modification.

Fig. 9 is a cross-sectional view showing a base yoke of a first modification.

Fig. 10 is a cross-sectional view showing a fixing member of a second modification.

Fig. 11 is a partial cross-sectional view showing a base yoke portion of a second modification.

The invention will now be described in accordance with preferred embodiments and with reference to the accompanying drawings. The same or equivalent constituent elements, members, and processes are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Further, for the sake of easy understanding, the member sizes in the respective drawings are appropriately enlarged and reduced to be displayed. Further, in the respective drawings, some components that are not important in the description of the embodiment will be omitted. Further, the embodiments are not intended to limit the invention, and are merely illustrative, and all of the features described in the embodiments or combinations thereof are not necessarily limited to the essential content of the invention.

(embodiment)

Fig. 1 is a perspective view of a linear motor 2 of the embodiment. The linear motor 2 includes a fixing member 20 and a movable member 10. The fixing member 20 mainly includes a field magnet 24, a base yoke 28, and rear yokes 23a, 23b. The field magnet 24 includes a main magnet 25 and an auxiliary pole magnet 26. The fixture 20 forms an exciting magnetic field in the magnetic gap 34. The movable member 10 is disposed to be movable in the movable direction of the magnetic gap 34 of the fixing member 20. The following description will be based on the XYZ orthogonal coordinate system. The X-axis direction corresponds to the horizontal left and right direction, and the Y-axis direction and water The flat front and rear directions correspond, and the Z-axis direction corresponds to the vertical up-and-down direction. The Y-axis direction and the Z-axis direction are orthogonal to the X-axis direction, respectively. Sometimes the X-axis direction is marked as the left direction or the right direction, the Y-axis direction is marked as the front direction or the back direction, and the Z-axis direction is marked as the up direction or the down direction. The first figure shows a state in which the movable direction of the mover 10 is set to the horizontal direction (X-axis direction), and the base yoke 28 to be described later is placed on the lower side of the field magnet 24. Furthermore, the marking of this direction does not limit the use posture of the linear motor 2, and the linear motor 2 can be used in any posture.

(Fastener)

Fig. 2 is a plan view showing the fixing member 20 of the embodiment. The base yoke 28 and the rear yokes 23a and 23b constitute a yoke 22. The yoke 22 supports the field magnet 24 and constitutes a magnetic circuit as a rear yoke of the field magnet 24. The field magnet 24 is disposed opposite to the movable member 10 (see also FIG. 1). The base yoke 28 is provided to be separated from the field magnet 24 in the Z-axis direction side as the first direction. The field magnet 24 is fixed to each of the rear yokes 23a and 23b. The rear yokes 23a and 23b and the base yoke 28 will be described later.

The main magnet 25 forms an exciting magnetic field in the magnetic gap 34. The auxiliary pole magnet 26 forms a Hobba array structure together with the main magnet 25, and reinforces the exciting magnetic field of the magnetic gap 34. The main magnet 25 is arranged inside the rear yokes 23a and 23b (on the magnetic gap 34 side) in the movable direction (X-axis direction) of the movable member 10, and is bonded and fixed in a plurality of straight lines. The auxiliary pole magnet 26 is fixed between the adjacent two main magnets 25. The field magnet 24 is made of, for example, a magnetic material containing a rare earth element, and is formed by a sintering method as an example. Excitation magnet 24 can also have There are surface layers such as plating. The field magnet 24 is formed, for example, in a rectangular plate shape. Further, the present invention is not necessarily required to include the auxiliary pole magnet 26.

The main magnet 25 has a thin rectangular parallelepiped shape in the Y-axis direction, and has a front surface and a rear surface on which magnetic pole faces are respectively formed, and the back surface is fixed to the inner side surfaces S1a and S1b of the rear yokes 23a and 23b (see also FIG. 1). . That is, the magnetization direction 25m of the main magnet 25 is formed to be parallel to the Y-axis. The auxiliary pole magnet 26 has a thin rectangular parallelepiped shape in the Y-axis direction and has a front surface and a back surface parallel to the X-axis, and its back surface is fixed to the inner side surfaces S1a and S1b of the rear yokes 23a and 23b (see also FIG. 1). . Magnetic pole faces are formed on both side faces of the auxiliary pole magnet 26, respectively. That is, the magnetization direction 26m of the auxiliary pole magnet 26 is formed to be parallel to the X axis.

As shown in Fig. 2, magnetic poles having mutually opposite polarities are provided on the front surface of the two field magnets 24 which are sandwiched by the magnetic gap 34 and opposed to each other. Therefore, the field magnets 24 generate magnetic attraction forces that attract each other. Due to this magnetic attraction force, a load directed inward is input to the rear yokes 23a and 23b via the magnetic gap 34, respectively.

In order to suppress the saturation of the rear yokes 23a, 23b and to improve the characteristics of the motor, the magnetic circuit of the linear motor is preferably configured to concentrate the magnetic field of the main magnet 25 on the side of the magnetic gap 34. Therefore, the magnetization direction 26m of the auxiliary pole magnet 26 of the embodiment is formed in a direction which is different from the magnetization direction 25m of the main magnet 25 by 90°. With the above configuration, the main magnet 25 and the auxiliary pole magnet 26 can form a Hobba array structure, and the magnetic field of the main magnet 25 can be concentrated on the magnetic gap 34 side.

(rear yoke)

Fig. 3 is a cross-sectional view taken along line A-A of the fixing member 20 of the embodiment. The rear yokes 23a, 23b are provided to sandwich the movable member 10 in the Y-axis direction. The field magnet 24 is provided on the inner side surface of each of the rear yokes 23a and 23b, and the field magnet 24 is opposed to the magnetic gap 34. The rear yokes 23a and 23b are plate-like members that extend in the left-right direction (X-axis direction) and the vertical direction (Z-axis direction). Each of the rear yokes 23a and 23b may be formed in a substantially rectangular shape having a long side in the X-axis direction, for example. A yoke hole 23h into which the bolt 29 as a fastener is fitted is provided in each of the rear yokes 23a and 23b. The yoke hole 23h is provided in the Y-axis direction.

(base yoke)

Fig. 4 is an enlarged cross-sectional view showing the base yoke 28 of the embodiment. The base yoke 28 is sandwiched between the rear yokes 23a, 23b on the lower side of the field magnet 24. The base yoke 28 is disposed in the negative direction on the Z-axis as the first direction side of the field magnet 24 so as to maintain the interval between the rear yokes 23a and 23b. That is, the rear yokes 23a and 23b are fixed to both end faces of the base yoke 28, thereby maintaining a predetermined interval. The base yoke 28 is a member having a rectangular parallelepiped shape having a long long side in the X-axis direction. The longitudinal section of the base yoke 28 along the Y-axis has a substantially rectangular shape. The base yoke 28 has end faces 28a at both ends in the Y-axis direction. The rear yokes 23a and 23b are coupled to the end portion 28a of the base yoke 28 by coupling a bolt 29 as a fastening member to a hole portion 28h provided as a fastening portion on the end surface 28a of the base yoke 28. The hole portion 28h is bored in the end surface 28a of the base yoke 28. End face 28a along the Z axis And extending in the X-axis direction. The hole portion 28h may be a through hole in the Y-axis direction or a non-through hole. An internal thread 28s is formed in the hole portion 28h. The internal thread 28s of the hole portion 28h can be screwed into the bolt 29 of the fastener. The rear yokes 23a and 23b are inserted into the bolt 29 from the outside of the yoke hole 23h, and are screwed into the hole portion 28h, thereby being fixed to the end surface 28a of the base yoke 28.

(Comparative example)

Among them, first, the base yoke 528 of the comparative example will be described. Fig. 5 is a cross-sectional view taken along line A-A of the fixing member 20 including the base yoke 528 of the comparative example. Fig. 6 is an enlarged cross-sectional view showing the base yoke 528 of the comparative example. The base yoke 528 is different from the base yoke 28 in that the position of the hole portion 28h is different, and the other structures are the same. Therefore, the description of the repetition is omitted and the differences are mainly explained. In the base yoke 528, the hole portion 28h is bored above the center 28m of the upper and lower ranges of the end surface 28a. In particular, the center 28n of the upper and lower ranges of the hole portion 28h on the end surface 28a is located above the center 28m of the end surface 28a. That is, as shown in Fig. 6, the distance Ln from the upper end portion 28u of the end surface 28a of the base yoke 28 to the center 28n of the hole portion 28h is smaller than the distance Lm from the upper end portion 28u to the center 28m of the end surface 28a.

When the base yoke 528 is used for the fixing member 20, the bolt 29 may have insufficient fastening force Ft as a force for pressing the rear yokes 23a and 23b toward the base yoke 28 side. When the fastening force Ft of the bolt 29 is insufficient, there is a problem that the rear yokes 23a and 23b are tilted inward due to the magnetic attraction force Fm of the field magnet 24. Therefore, it is considered to increase the tightening screw. The number of the bolts 29 is increased to increase the tightening force Ft for the total. However, when the number of the bolts 29 is increased, the number of processing of the yoke hole 23h and the hole portion 28h increases, and the number of the mounting bolts 29 increases, and the productivity is lowered.

The fastener 20 of the embodiment of the present invention will be described based on the examination of the above comparative example. In the relationship between the attraction force Fm and the fastening force Ft, when each of the rear yokes 23a and 23b is a lever and the magnetic attraction force Fm generated by the field magnet 24 is used as a force point load, the fastening force Ft can be understood as The load point occurring at the fulcrum of the end face 28a and balanced with the attractive force Fm as the load point load is clamped. This fulcrum is, for example, the upper end portion 28u of the end surface 28a of the base yoke 28. That is, the hole portion 28h as the fastening portion and the bolt 29 as the fastener exert a fastening force Ft which is a load balanced with the attraction force Fm of the field magnet 24 by the lever principle. At this time, if the load or the distance on the force receiving point side is made constant, the distance from the fulcrum to the action point side of the action point is increased, whereby the smaller the fastening force Ft can be balanced with the suction force Fm. That is, the distance from the upper end portion 28u of the end surface 28a of the base yoke 28 to the action point side of the hole portion 28h as the fastening portion is increased, whereby the balance force Ft which can be balanced can be reduced.

See Figures 3 and 4 again. The hole portion 28h as the fastening portion is provided on the opposite side of the side where the fulcrum appears when the end surface 28a is divided into two portions in the Z-axis direction as the first direction. In particular, in the Z-axis direction, the center of the hole portion 28h as the fastening portion in the end surface 28a is located on the opposite side of the side on which the fulcrum appears when the end surface 28a is divided into two portions. That is, the fulcrum is the upper end portion 28u of the end surface 28a of the base yoke 28. In the case, the center 28n of the upper and lower ranges of the hole portion 28h in the end surface 28a of the base yoke 28 is located lower than the center 28m of the range of the end surface 28a in the Z-axis direction. As shown in Fig. 4, the distance Ln from the upper end portion 28u of the end surface 28a of the base yoke 28 to the center 28n of the hole portion 28h is larger than the distance Lm from the upper end portion 28u to the center 28m of the end surface 28a. Since the center 28n of the hole portion 28h is located away from the upper end portion 28u, the distance on the side of the action point is increased, and the tightening force Ft at which the balance can be obtained can be reduced.

From the viewpoint of reducing the tightening force Ft that can be balanced, the distance on the side of the action point is preferably larger. Therefore, in the stator 20 of the embodiment, the upper and lower ranges of the hole portion 28h in the end surface 28a of the base yoke 28 are located lower than the center 28m of the upper and lower ranges of the end surface 28a. Since the range of the hole portion 28h is located lower than the center 28m, the distance on the side of the action point is further increased, and the tightening force Ft at which the balance can be obtained can be further reduced.

From the viewpoint of further reducing the tightening force Ft which can be balanced, the distance on the side of the above-mentioned action point is preferably a larger one. Therefore, in the stator 20 of the embodiment, the entire hole portion 28h of the base yoke 28 is located lower than the center 28m of the upper and lower ranges of the end surface 28a of the base yoke 28. That is, since the entire hole portion 28h is located lower than the center 28m, the distance on the side of the action point is further increased, and the tightening force Ft at which the balance can be obtained can be further reduced.

Next, the features of the linear motor 2 of the embodiment configured as above will be described.

In the linear motor 2, the hole portion 28h as the fastening portion is provided in the case where the end surface 28a is divided into two portions in the Z-axis direction as the first direction. The opposite side of the one side of the fulcrum appears, so that the rear yokes 23a and 23b can be pressed toward the base yoke 28 side at a position farther from the fulcrum than when the hole portion 28h is provided on one side of the fulcrum. . As a result, it is possible to reduce the fastening force Ft which is balanced with the attractive force Fm of the field magnet 24. The balance tightening force Ft is small, so the number of the bolts 29 for fastening the rear yokes 23a, 23b can be reduced. By reducing the number of the bolts 29, it is possible to suppress an increase in the weight of the linear motor 2, and it is possible to reduce the number of processing of the yoke hole 23h and the hole portion 28h or the number of mounting of the bolts 29. Also, a smaller bolt 29 can be used. In other words, it is possible to suppress a drop in productivity and suppress the tilting of the rear yokes 23a and 23b due to the attraction force Fm of the field magnet 24.

In the linear motor 2, in the Z-axis direction as the first direction, the center of the hole portion 28h in the end surface 28a is located on the side opposite to the side on which the fulcrum appears when the end surface 28a is divided into two portions, so that it is possible to The rear yokes 23a and 23b are pressed toward the base yoke 28 side at the lower position.

Next, the use of the linear motor 2 will be described. Fig. 7 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, an X stage 130, and a stage 140. The Y stage 120 includes a pair of sliders 124 and a cross member 122 that is transversely disposed between the pair of sliders 124. An X linear motor 2X for moving the X stage 130 in the X direction is provided on the cross member 122. The X linear motor 2X is fixed to the cross member 122 and extends in the X direction. The fixing member 20 and the movable member (coil) 10 coupled to the lower surface of the X stage 130. The movable member 10 of the X linear motor 2X is controlled as above, whereby 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 is provided with a movable member 10 and a fixing member 20, respectively. The above-described slider 124 is fixed to the fixing member 20 of the Y linear motor 2Y. The movable member 10 of the Y linear motor 2Y is controlled, whereby the Y stage 120 is positioned in the Y direction.

The above is the structure of the stage device 100. 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 device, or can be used in an actuator or the like used in a scanning electron microscope (SEM).

The above has been described based on the embodiments of the present invention. It is to be understood by those skilled in the art that these embodiments are merely illustrative, and that various modifications and changes can be made within the scope of the invention. Accordingly, the description and drawings are to be regarded as

(First Modification)

Next, a first modification will be described. Fig. 8 is a cross-sectional view taken along line A-A of the fixing member 20 including the base yoke 28 of the first modification. Fig. 9 is an enlarged cross-sectional view showing the base yoke 28 of the first modification. In Fig. 9, the upper and lower ranges of the end face 28a of the base yoke 28 are divided into three regions 28aa which are divided into three parts by the bisector 28t1 and the bisector 28t2, 28ab, 28ac to express. As shown in Fig. 8, in the base yoke 28 of the modification, the center 28n of the hole portion 28h as the fastening portion in the end surface 28a is located at a distance separating the end surface 28a in the Z-axis direction as the first direction. In the case of three equal parts, the area farthest to the fulcrum is 28ac. Further, as shown in Fig. 8, in the modified example, the range of the bolt 29 as the fastener in the Z-axis direction is included on the opposite side of the side where the fulcrum appears when the end surface 28a is divided into two portions. In the range. That is, the bolt 29 includes its head portion 29a located lower than the center 28m of the upper and lower ranges of the end surface 28a. Also in this modification, the same effects as those in the configuration common to the embodiment can be obtained. In addition, according to the base yoke 28 of this modification, the distance on the side of the action point is further increased, and the tightening force Ft at which the balance can be obtained can be further reduced.

(Second Modification)

In the description of the embodiment, an example has been described in which the end yokes 23a and 23b are fastened to the end faces 28a on both sides of the base yoke 28 by bolts 29. However, the present invention is not limited thereto. One of the rear yokes may also be integrally formed with the base yoke. In other words, the L-shaped yoke integrally formed with the rear yoke and the base yoke may be combined with the other I-shaped rear yoke. Fig. 10 is a cross-sectional view showing the fixing member 220 of the second modification. Fig. 11 is a partial cross-sectional view showing the base yoke portion 228 of the yoke 223, mainly showing the periphery of the end surface 28a. Fig. 10 corresponds to Fig. 3, and Fig. 11 corresponds to Fig. 4, and the same or equivalent constituent elements are given the same reference numerals. The yoke 223 includes a magnetic shape having an L-shaped cross section of the rear yoke portion 223b and the base yoke portion 228. yoke. The fixing member 220 is different from the fixing member 20 of the embodiment in that the rear yoke portion 223b and the base yoke portion 228 are integrally formed, and the other structures are the same. That is, the rear yoke portion 223b has the same features as the rear yoke 23b of the embodiment, and the base yoke portion 228 has the same features as the base yoke 28 of the embodiment. Therefore, the repeated explanation is omitted, and the differences are highlighted.

As shown in Fig. 10, the rear yoke 23a is inserted into the bolt 29 as a fastener from the outside of the yoke hole 23h, and is screwed into the hole portion 28h as a fastening portion, thereby being fixed to the base yoke portion of the yoke 223. End face 28a of 228. The hole portion 28h is provided on the opposite side of the side on which the fulcrum appears when the end surface 28a is divided into two portions in the Z-axis direction. In particular, in the Z-axis direction, the center of the hole portion 28h as the fastening portion in the end surface 28a is located on the opposite side of the side on which the fulcrum appears when the end surface 28a is divided into two portions. In other words, when the fulcrum is the upper end portion 28u of the end surface 28a of the base yoke portion 228, the center 28n of the upper and lower ranges of the hole portion 28h in the end surface 28a of the base yoke portion 228 is located in the Z-axis direction of the end surface 28a. The center 28m is on the lower side. As shown in Fig. 11, the distance Ln from the upper end portion 28u of the end surface 28a of the base yoke portion 228 to the center 28n of the hole portion 28h is larger than the distance Lm from the upper end portion 28u to the center 28m of the end surface 28a. Since the center 28n of the hole portion 28h is located away from the upper end portion 28u, the distance on the side of the action point can be increased, and the tightening force Ft at which the balance can be obtained can be reduced. Also in this modification, the same effects as those in the configuration common to the embodiment can be obtained. In addition, according to the fixing member 220 of the modification, the rear yoke portion 223b and the base yoke portion 228 are integrally formed, so that it can be reduced for use. The number of processors combined with the holes or the number of bolts installed.

(Other variants)

In the description of the embodiment, the fastening portion has the hole portion 28h of the internal thread 28s and the fastener-type bolt 29 has been described. However, the present invention is not limited thereto, and these may be other types of fastening means. For example, the fastener may be a rivet, and the fastening portion may be a rivet hole.

In the description of the embodiment, the example in which the hole portion 28h is provided in parallel with the Y-axis direction has been described. However, the present invention is not limited thereto. For example, the hole portion 28h may be inclined.

In the description of the embodiment, the case where the rear yokes 23a and 23b are fixed to the end surface 28a of the base yoke 28 by the bolts 29 has been described, but the invention is not limited thereto. In addition to the bolts 29, for example, an auxiliary fixing means such as a binder may be used in combination.

In the drawings used in the description, in order to clarify the relationship of the members, the cross-sections of the partial members are hatched, but the shading does not limit the materials or materials of the members.

20‧‧‧Fixed parts

22‧‧‧Y yoke

23a‧‧‧Back yoke

23b‧‧‧Back yoke

23h‧‧‧ yoke hole

24‧‧‧Excitation magnet

28‧‧‧ base yoke

28a‧‧‧ end face

28h‧‧‧ Hole Department

28n‧‧‧Center of the Ministry of Confucius

28m‧‧‧ the center of the end face

28u‧‧‧Upper

29‧‧‧Bolts

34‧‧‧ Magnetic gap

Fm‧‧‧ attractive

Ft‧‧‧ fastening force

Claims (6)

A linear motor comprising: a fixing member comprising: a field magnet disposed opposite to the movable member; a base yoke disposed apart from the first direction side of the field magnet; and the aforementioned fixing a field magnet yoke, the rear yoke is coupled to a fastening portion provided on an end surface of the base yoke, and is fastened to an end surface of the base yoke, and the rear yoke is a lever When the magnetic attraction force generated by the field magnet is used as a load point load, the fastening portion exerts a fastening force that is applied to a fulcrum of the end surface and serves as a load point at a load balance with the load point. The solid portion is provided on the opposite side of the side on which the fulcrum appears when the end surface is divided into two portions in the first direction. The linear motor according to claim 1, wherein in the first direction, the center of the fastening portion in the end surface is located on one side of the fulcrum when the end surface is divided into two portions The opposite side. The linear motor according to claim 1 or 2, wherein in the first direction, the center of the fastening portion of the end surface is located at a distance from the end surface into three equal parts The farthest area of the fulcrum area. The linear motor according to claim 1 or 2, wherein, in the first direction, the range of the fastener includes one side of the fulcrum on the side where the end surface is divided into two portions On the opposite side of the range. The linear motor according to claim 1 or 2, wherein the fastening portion is threaded through the threaded hole of the end surface, and the fastener is screwed to the threaded hole. A stage apparatus comprising the linear motor according to claim 1 or 2 of the patent application.