JP2007116815A - Linear motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce weight by canceling a magnetic field of a permanent magnet in a prescribed region. <P>SOLUTION: This linear motor 10 is constituted by combining a coil unit 20 and a magnet unit 30, the coil unit 20 is a movable body, and the magnet unit 30 is a stator. When each coil of the coil unit 20 is energized, thrust in the Y direction is generated between a coil and the permanent magnet 34 of the magnet unit 30. The magnet unit 30 comprises a magnetic pole base 32, a plurality of the permanent magnets 34<SB>1</SB>to 34n fixed to the installation face 33 of the magnetic pole base 32, and cancel magnets 36 fixed to both ends of the magnetic pole base 32. The cancel magnet 36 is arranged in a position where a magnetic field of a prescribed region A (shown by a one-dot chained line in Fig. 1) that is apart from the linear motor 10 to the side way (X direction) at a prescribed distance. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a linear motor, and more particularly to a linear motor configured to eliminate the influence of a magnetic field formed around the linear motor.

  The linear motor is configured such that the mover side is linearly moved by electromagnetic thrust generated between a linearly arranged coil and a permanent magnet. In this type of linear motor, since a plurality of permanent magnets are provided so as to face the coil, a magnetic field is formed around the linear motor by magnetic flux from the permanent magnets.

For example, when a linear motor is incorporated as a drive means in a device that irradiates an electron beam, the electron beam is affected by the magnetic field generated by the permanent magnet of the linear motor. In order to eliminate the influence of such a magnetic field, there is one that performs magnetic shielding by configuring the linear motor so that it is covered with a magnetic shield plate (see, for example, Patent Document 1).
JP 2002-191164 A

  However, the linear motor configured to cover the periphery of the linear motor with the magnetic shield plate as described above is not only larger but requires a larger installation space, and the magnetic shield plate also increases the weight. There was a problem that the support part for supporting the substrate was manufactured more firmly.

  In view of the above circumstances, an object of the present invention is to provide a linear motor that solves the problem.

  In order to solve the above problems, the present invention has the following means.

  The invention according to claim 1 includes a coil portion in which a plurality of coils are arranged in a straight line, and a magnet portion arranged in parallel with the coil portion and in which a plurality of permanent magnets are arranged in parallel. In the linear motor for moving any one of the magnet portions, there is provided canceling means for canceling a magnetic field in a predetermined region separated from the magnet portion by a predetermined distance among magnetic fields formed around the magnet portion. .

  The invention according to claim 2 is characterized in that the canceling means is a permanent magnet and is disposed at a position where the magnetic field in the predetermined area is canceled.

  The invention according to claim 3 is characterized in that the canceling means is an electromagnet and is disposed at a position where the magnetic field in the predetermined region is canceled.

  The invention according to claim 4 is characterized in that the canceling means is a combination of a permanent magnet and an electromagnet, and is arranged at a position for canceling the magnetic field in the predetermined region.

  The invention according to claim 5 is characterized in that the canceling means is provided at an end of the magnet portion.

  The invention according to claim 6 is characterized in that the canceling means is provided at a position overlapping with a magnetic field passing through a region extending in parallel with the magnet portion.

  The invention according to claim 7 is characterized in that the canceling means is arranged at a position which is symmetric with respect to a region extending in parallel with the magnet portion.

  The invention according to claim 8 is characterized in that the mounting position is set based on a magnetic field analysis result obtained by analyzing the magnetic field around the linear motor.

  The invention according to claim 9 is characterized in that the canceling means sets a magnetic force based on a magnetic field analysis result obtained by analyzing a magnetic field around the linear motor.

  According to a tenth aspect of the present invention, the canceling unit controls a magnetic field detection sensor that detects a magnetic field around the linear motor, and a current supplied to the electromagnet according to the state of the magnetic field detected by the magnetic field detection sensor. And a control means.

  According to the present invention, since the canceling means for canceling the magnetic field in the predetermined area separated from the magnet part by a predetermined distance among the magnetic fields formed around the magnet part is provided, the configuration is more compact than covering the linear motor with the magnetic shield plate. In addition, the weight can be reduced. In addition, by canceling the magnetic field in a predetermined area separated from the magnet part by a predetermined distance, it becomes possible to obtain a part of the area not affected by the magnetic field, and not canceling the entire magnetic field around the magnet part. It becomes possible to effectively cancel a magnetic field in a specific region that is susceptible to magnetic influence.

  Further, by configuring the canceling means with a permanent magnet or an electromagnet, the configuration can be simplified. Moreover, in order to set the attachment position of the canceling unit based on the magnetic field analysis result obtained by analyzing the magnetic field around the linear motor, it is set to cancel the magnetic field in an arbitrary region according to the magnetic field environment unique to each linear motor. Is possible.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a plan view showing an embodiment of a linear motor according to the present invention. FIG. 2 is a perspective view showing a part of the linear motor. FIG. 3 is a longitudinal sectional view of the linear motor as seen from the moving direction (Ya direction). As shown in FIGS. 1 to 3, the linear motor 10 has a configuration in which a coil unit (coil part) 20 and a magnet unit (magnet part) 30 are combined. In this embodiment, the coil unit 20 is a mover. Yes, the magnet unit 30 is a stator. When energization of each coil 22 of the coil unit 20 is performed, thrust in the Ya and Yb directions is generated between the coil 22 and the permanent magnet 34 of the magnet unit 30.

  The coil unit 20 has a configuration in which a plurality of coils 22 having a bowl-shaped cross section are linearly arranged side by side and integrally held by a coil holder 24 made of a resin mold, and viewed from the moving direction (Ya direction). It is formed in an I shape.

The magnet unit 30 includes a magnetic pole base 32 having a U-shaped cross section, a plurality of permanent magnets 34 _{1 to} 34 n fixed to the mounting surface 33 of the magnetic pole base 32, and a cancel fixed to both ends of the magnetic pole base 32. And a magnet 36. The plurality of permanent magnets 34 _{1 to} 34 n are provided so as to face each other from the left and right sides of the coil unit 20, and are arranged in parallel in the Y direction at regular intervals. The magnetic pole base 32 includes a bottom yoke 38 and a pair of side yokes 39 that stand upward from both ends of the bottom yoke 38 in the Xa and Xb directions. Opposing surfaces of the pair of side yokes 39 serve as attachment surfaces 33 for fixing the permanent magnet 34 and the cancel magnet 36.

Although the cancel magnet 36 is a permanent magnet, a magnet that is smaller than the driving permanent magnet 34 and has a weak magnetic force is used. The cancel magnet 36 is provided at a position separated by a distance Lb longer than the interval La between the plurality of permanent magnets 34 _{1 to} 34 n (La <Lb).

  The cancel magnet 36 is a cancel means for canceling the magnetic field formed by the permanent magnet 34, and is a predetermined area A (shown by a one-dot chain line in FIG. 1) that is separated from the linear motor 10 by a predetermined distance to the side (Xb direction). ) Is provided at a position to cancel the magnetic field. The predetermined area A is an area having a substantially elliptical outline, and a processing area B (shown by a broken line in FIG. 1) is located therein. For example, when the linear motor 10 is used as a driving unit of a charged particle beam exposure apparatus (not shown), the processing region B is a region where a charged particle beam that is easily affected by a magnetic field is irradiated.

FIG. 4 is a diagram showing the state of magnetic flux of the permanent magnet 34 and the cancel magnet 36. As shown in FIG. 4, the permanent magnets 34 _{1 to} 34 n are attached so that the magnetic poles (S pole and N pole) of the magnets facing each other in the Xa and Xb directions are in the same direction, with respect to the Ya and Yb directions. The magnetic poles (S pole, N pole) are alternately attached in different directions.

In order to form a magnetic circuit having the magnetic pole base 32 as a magnetic path between the plurality of permanent magnets 34 _{1 to} 34 n, a magnetic flux (shown by an arrow in FIG. 4) that passes through the magnetic pole base 32 from the N pole is adjacent. Drawn to the south pole. Further, a magnetic flux that linearly passes through the air is formed between the permanent magnets 34 facing in the Xa and Xb directions.

Most of the magnetic flux between the permanent magnets 34 is formed so as to pass through the magnetic pole base 32 and the inside thereof, but a part of the magnetic flux is also formed outside the magnetic pole base 32. The magnetic fluxes of the plurality of permanent magnets 34 _{1 to} 34 n form a closed magnetic circuit with the adjacent permanent magnets 34, so that the magnetic flux formed outside the magnetic pole base 32 hardly reaches the predetermined region A separated in the Xb direction. . Ya, part of the magnetic flux of the magnet 34 ₁ and 34n located at the end of the Yb direction forms respectively ₃₄ 2, _{34 n-1} and the closed magnetic circuit, the remaining flux is arranged on the end of the pole base 32 The closed magnet circuit is formed with the cancel magnet 36. If the magnetic force of the cancel magnet 36 is appropriate, the plurality of permanent magnets 34 _{1 to} 34 n and the cancel magnet 36 form a closed magnetic path with adjacent magnets. A is hardly reached.

  As described above, by providing the cancel magnets 36 at both ends of the magnetic pole base 32, the magnetic field in the predetermined area A that is separated from the magnetic pole base 32 in the Xb direction is canceled, and the magnetic field in the processing area B hardly affects the electron beam or the like. Decrease to a low level.

Here, the state of the magnetic field by the permanent magnet ₃₄ 1 to 34N, the magnetic field generated by the permanent magnet ₃₄ 1 to 34N in the predetermined region A and the processing region B will be described in comparison with the condition being canceled by canceling the magnet 36.

FIG. 5 is a result of analyzing the state of the magnetic field by the permanent magnets 34 _{1 to} 34 n, (A) is a diagram showing the direction of the magnetic field with an arrow, and (B) is a distribution diagram showing the distribution state of the strength of the magnetic field. . As shown in FIG. 5 (A), the magnetic field generated by the permanent magnet ₃₄ 1 to 34N is the magnetic field vector in the vicinity of the permanent magnet ₃₄ 1 to 34N (arrow) is densely shown in FIG. 5 (B) As can be seen, the strength of the magnetic field in the vicinity of the permanent magnets 34 _{1 to} 34 n reaches the maximum level 6 in six stages. Further, in regions A and B that are separated from the permanent magnets 34 ₁ to 34 n by a predetermined distance, vectors (arrows) are formed along the Ya direction, and in the vicinity of the end of the magnetic pole base 32 without the permanent magnet 34, the vector ( An arrow) is formed in the Xa direction.

Thus, it can be seen from the results obtained by performing the magnetic field analysis that the strength of the magnetic field by the permanent magnets 34 _{1 to} 34 n in the regions A and B is maintained at level 3 during the six stages.

6A and 6B show the results of analyzing the state of the magnetic field by the cancel magnet 36. FIG. 6A is a diagram showing the direction of the magnetic field with an arrow, and FIG. 6B is a distribution diagram showing the distribution state of the magnetic field strength. As shown in FIG. 6A, the magnetic field vector (arrow) from the cancel magnet 36 is directed in the Xb direction (a direction opposite to the magnetic field of the permanent magnets 34 _{1 to} 34 n by 180 degrees) away from the cancel magnet 36. In regions A and B separated by a predetermined distance from 36, the magnetic field vector is formed in the Yb direction (direction opposite to the vector (arrow) of the permanent magnets 34 _{1 to} 34 n by 180 degrees). Further, as shown in FIG. 6B, the magnetic field strength in the vicinity of the canceling magnet 36 is the maximum level 6 in six steps, and in the regions A and B, the magnetic field strength by the canceling magnet 36 is six steps. It turns out that it is the middle level 3.

Therefore, the cancel magnet 36 is selected from a material and a size having a magnetic force such that the strength of the magnetic field in the regions A and B is the same as the strength of the magnetic field by the permanent magnets 34 _{1 to} 34 n based on the analysis result of the magnetic field analysis. And is attached in an orientation that forms a vector that is 180 degrees opposite to the vector of the permanent magnets 34 _{1 to} 34 n.

FIG. 7 shows the result of analyzing the state of the magnetic field by the combination of the permanent magnets 34 _{1 to} 34 n and the cancel magnet 36, (A) shows the direction of the magnetic field with an arrow, and (B) shows the strength of the magnetic field. It is a distribution map which shows a distribution state. As shown in FIG. 7A, the magnetic field in the vicinity of the permanent magnets 34 _{1 to} 34 n is hardly canceled by the magnetic field generated by the cancel magnet 36, so that the magnetic field strength distribution state shown in FIG. Is compared with the distribution state of FIG. 5B, it can be seen that a sufficient thrust force on the coil unit 20 can be obtained because the direction and strength of the magnetic field do not change in the coil unit passage region.

Further, it can be seen that the strength of the magnetic field in the regions A and B is lowered to the level 1 during the six stages. This is because the magnetic field vector generated by the cancel magnet 36 is 180 degrees opposite to the magnetic field vector generated by the permanent magnets 34 _{1 to} 34 n and the magnetic field strength is set to the same magnitude. This indicates that the magnetic fields of the permanent magnets 34 _{1 to} 34 n in the regions A and B are canceled.

  Therefore, as shown in FIG. 1, by providing the cancel magnet 36 at the end of the magnetic pole base 32, the magnetic fields in the regions A and B separated from the magnetic pole base 32 by a predetermined distance can be canceled. In A and B, it becomes possible to perform a precision processing process such as an electron beam irradiation process that is easily affected by a magnetic field with higher accuracy. Further, in the linear motor 10, since the canceling magnet 36 as the canceling means is only provided at the end of the magnetic pole base 32, it is not increased in size and covered with a magnetic shield plate. And weight reduction can be achieved.

FIG. 8 is a plan view showing the configuration of the second embodiment. In FIG. 8, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. As shown in FIG. 8, the linear motor 50 of Example 2, 1 pair of cancel magnets _36, 36 ₂ are provided symmetrically to a predetermined distance spaced apart position from the pole base 32. The pair of cancel magnet 36 _1, 36 _2, Ya direction across the processing region B, is disposed at a predetermined distance a location spaced Yb direction, provided so as to cancel the magnetic field passing through the processing region B Yes.

Further, 1 pair of cancel magnets _36, 36 ₂ is disposed so that N poles and S poles facing magnetic poles of the orientation of the magnetic field vector due to the permanent magnet ₃₄ 1 to 34N orientation and (Ya direction) It is attached so as to be in the opposite direction (Yb direction). That is, the cancel magnets 36 ₁ and 36 ₂ have their attachment positions set based on the magnetic field analysis result obtained by analyzing the magnetic field around the linear motor 50. In this configuration, it is easy to design it is possible to cancel the linear flux of Yb direction, it becomes possible to provide the canceling magnet 36 _1, 36 ₂ in the vicinity of the processing region B, cancel magnet 36 _1, 36 directly can cancel the magnetic field of the processing region B of the permanent magnet 34 ₁ to 34N by _two magnetic field, it is possible to reduce the magnetic field in the processing region B on the level 1 is also a weak magnet having correspondingly force .

FIG. 9 shows the result of analyzing the state of Example 2 in which the cancel magnet 36 is installed in the magnetic field of the processing region B. FIG. 9A shows the direction of the magnetic field with an arrow, and FIG. 9B shows the distribution of the strength of the magnetic field. It is a distribution map which shows a state. 9 as (A), the vector of the magnetic field from one cancel magnet 36 ₁ (arrows), the processing region B and symmetrically arranged other cancellation magnet 36 ₂ toward Yb direction (the permanent magnets 34 _{1 to} 34n vectors (arrows) and 180 degrees opposite direction). Further, as shown in FIG. 9B, the strength of the magnetic field in the vicinity of the cancel magnet 36 is the maximum level 6 in six steps, and in the processing region B, the strength of the magnetic field by the cancel magnet 36 is in six steps. It turns out that it is level 3.

Thus, cancellation magnets 36 _1, 36 ₂ is selected the material and size having a magnetic force, such as the strength of the magnetic field is the same as the strength of the magnetic field by the permanent magnets 34 ₁ to 34N in the processing area B, and The permanent magnets 34 _{1 to} 34 n are attached in a direction that forms a vector that is 180 degrees opposite to the vector.

Figure 10 is a result of analyzing the state of the magnetic field due to configuration of the second embodiment in combination with the permanent magnet ₃₄ 1 to 34N and cancellation magnet ₃₆ 1, 36 _2, (A) is a diagram showing the direction of the magnetic field by the arrow, ( B) is a distribution diagram showing the distribution state of the strength of the magnetic field. As shown in FIG. 10 (A), the magnetic field in the vicinity of the permanent magnet ₃₄ 1 to 34N, because not canceled almost by a magnetic field by canceling magnet ₃₆ 1, 36 _2, as shown in FIG. 10 (B) It can be seen that the strength of the magnetic field is the maximum level 6 in six stages, and sufficient thrust for the coil unit 20 can be obtained.

In addition, it can be seen that the strength of the magnetic field in the processing region B is lowered to level 1 during six stages. This is a vector and 180-degree opposite direction of the magnetic field vector of the magnetic field by canceling magnet 36 _1, 36 ₂ described above is due to the permanent magnet 34 ₁ to 34N, and because the strength of the magnetic field is set to the same size This shows that the magnetic field of the permanent magnets 34 _{1 to} 34 n in the regions A and B is canceled by the cancel magnet 36.

Accordingly, as shown in FIG. 8, by providing the canceling magnet 36 _1, 36 ₂ in a magnetic field passing through the processing region B spaced from the pole base 32 in the Xb direction, treated by a predetermined distance away from the pole base 32 regions Since the magnetic field of B can be canceled, for example, in the processing region B, it is possible to perform a precision processing step such as an electron beam irradiation process that is easily affected by the magnetic field with higher accuracy. Further, in the linear motor 10, because only provided in the vicinity of the magnetic field in the processing region B cancel magnet 36 _1, 36 ₂ as canceling means spaced from the pole base 32, without increasing the size than covered with the magnetic shield plate, a compact In addition, the installation space can be reduced and the weight can be reduced.

FIG. 11 is a plan view showing the configuration of the third embodiment. In FIG. 11, the same parts as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof is omitted. As shown in FIG. 11, the linear motor 60 according to the third embodiment includes a pair of coil units 20 ₁ and 20 ₂ and a pair of magnet units 30 ₁ and 30 ₂ , and the pair of coil units 20 ₁ and 20 _2. Are controlled to be translated in the same direction at the same speed. The magnet units 30 ₁ and 30 ₂ are provided with cancel magnets 36 at the ends of the magnetic pole bases 32 ₁ and 32 ₂ . A pair of electromagnets 62 ₁ and 62 ₂ is disposed at a substantially intermediate position between the pair of magnetic pole bases 32 ₁ and 32 ₂ disposed in parallel to the Y direction. The pair of electromagnets 62 ₁ and 62 ₂ are provided at positions that are symmetrical in the Ya and Yb directions with the processing region B as the center.

Therefore, the electromagnets 62 ₁ and 62 ₂ are positioned on the magnetic field line passing through the processing region B, and the direction of the magnetic pole is opposite to the direction of the magnetic field vector (Ya direction) by the permanent magnets 34 _{1 to} 34n (Yb). Direction). In this configuration, since the electromagnets 62 ₁ and 62 ₂ can be provided in the vicinity of the processing region B, the magnetic field of the processing region B by the permanent magnets 34 _{1 to} 34 n is directly generated by the magnetic field of the electromagnets 62 ₁ and 62 _2. Can be canceled. The electromagnets 62 ₁ and 62 ₂ function as auxiliary canceling means that is energized and cancels the magnetic field in the processing region B when a magnetic field that cannot be canceled by the cancel magnet 36 is generated in the processing region B.

Around the processing region B, magnetic sensors (magnetic field detection sensors) 64 ₁ and 64 ₂ made of Hall elements are attached. When the strength of the magnetic field detected by the magnetic sensors 64 ₁ and 64 ₂ is level 2 or higher during the six stages, energization to the electromagnets 62 ₁ and 62 ₂ is started and the strength of the magnetic field is determined. Current control is performed.

Further, when the magnetic field of the processing region B is very weak, it may be difficult to detect the magnetic field of the processing region B by the magnetic sensor 64 _1, 64 _2, in that case provided in the vicinity of the permanent magnet 34 ₁ to 34N Switching to a method of detecting a strong magnetic field in the vicinity of the permanent magnets 34 _{1 to} 34 n by the magnetic sensors 64 ₃ and 64 ₄ . In the detection method using the magnetic sensors 64 ₃ and 64 ₄ , the magnetic field in the processing region B cannot be directly detected. However, the magnetic field analysis data is stored in the memory in advance, and is detected in the vicinity of the permanent magnets 34 _{1 to} 34 n. The magnetic field detection value can be compared with the magnetic field analysis data to estimate the magnetic field of the processing region B by calculation.

  As described above, by switching the magnetic field detection position, the magnetic field in the processing region B can be accurately canceled regardless of the level of the magnetic field in the processing region B.

Here, the control system of the electromagnets 62 ₁ and 62 ₂ will be described with reference to FIG. As shown in FIG. 12, the detection signal indicating the strength of the detected magnetic field by the magnetic sensor ₆₄ 1-64 ₄ is supplied to the control circuit 66 is amplified by the amplifier ₆₅ 1 to 65 _4. In the control circuit 66, with the strength of the cancellation magnetic field from the analysis data table 67 by canceling the magnet 36 from the detected magnetic field strength distribution of the magnetic sensor 64 _{1-64 4,} calculates the magnetic field can not be canceled by the cancel magnet 36 Then, a control signal (current value) corresponding to the magnetic field level is output. Then, the current amplified by the amplifiers 68 ₁ and 68 ₂ is supplied to the electromagnets 62 ₁ and 62 ₂ .

Thus, the electromagnet 62 _1, 62 _2, the processing area the magnetic field B is based on a value detected by the magnetic sensor 64 _{1-64 4} also vary compared to the design value, the current value is energized is controlled by the processing region A magnetic field having a strength that cancels the magnetic field of B is formed. Therefore, in the processing region B, the magnetic fields of the permanent magnets 34 _{1 to} 34 n are canceled by the magnetic fields from the cancel magnet 36 and the electromagnets 62 ₁ and 62 ₂ .

In the control circuit 66, it may be detected value by feeding back the detected value by the magnetic sensor ₆₄ 1-64 ₄ controls the current supplied to the electromagnet ₆₂ 1, 62 ₂ to be zero.

Further, in the control circuit 66, when the magnetic sensor 64 ₁ , 64 ₂ can detect the magnetic field of the processing region B as described above, the electromagnet 62 ₁ is based on the detection value of the magnetic sensor 64 ₁ , 64 _2. , 62 ₂ to control the current supplied, the processing region when the magnetic field B can not be detected in weak, the magnetic sensor ₆₄ 3, 64 ₄ in switching the permanent magnet 34 ₁ provided in the vicinity of the permanent magnet ₃₄ 1 to 34N A strong magnetic field in the vicinity of ˜34n is detected, and the detected value is compared with the magnetic field analysis data to calculate the magnetic field in the processing region B.

Thus, the control circuit 66, by controlling the current supplied from the detection value by the magnetic sensor ₆₄ 1-64 ₄ to the electromagnet ₆₂ 1, 62 _2, also the magnetic field of the processing region B is changed in the processing region B It is possible to reduce the strength of the magnetic field to level 1.

FIG. 13 is a plan view showing the configuration of the fourth embodiment. In FIG. 13, the same parts as those in the first to third embodiments are denoted by the same reference numerals, and the description thereof is omitted. As shown in FIG. 13, the linear motor 70 of the fourth embodiment has a pair of coil units 20 ₁ and 20 ₂ and a pair of magnet units 30 ₁ and 30 ₂ , as in the third embodiment. Control is performed so that the coil units 20 ₁ and 20 ₂ are translationally driven at the same speed in the same direction. Magnet unit ₃₀ 1, 30 _2, the electromagnet ₆₂ 1, 62 ₂ are provided at the end of the pole base ₃₂ 1, 32 _2. A pair of cancel magnets 36 is disposed at a substantially intermediate position between the pair of magnetic pole bases 32 ₁ and 32 ₂ disposed in parallel to the Y direction. A pair of cancel magnet ₃₆ 1, 36 _2, Ya around the treatment area B, and provided symmetrically with a position in the Yb direction.

Thus, cancellation magnets ₃₆ 1, 36 _2, the process is located on the line of the magnetic field passing through the area B, the magnetic poles of the orientation of the magnetic field vector due to the permanent magnet ₃₄ 1 to 34N orientation (Ya direction) in the opposite direction ( (Yb direction). In this configuration, the cancel magnets 36 ₁ and 36 ₂ can be provided in the vicinity of the processing region B. Therefore, the magnetic field of the processing region B by the permanent magnets 34 _{1 to} 34 n is directly generated by the magnetic field of the cancel magnets 36 ₁ and 36 _2. Can be canceled. Further, the electromagnets 62 ₁ and 62 ₂ function as auxiliary canceling means that is energized and cancels the magnetic field in the processing region B when a magnetic field that cannot be canceled by the cancel magnets 36 ₁ and 36 ₂ is generated in the processing region B.

FIG. 14 is a plan view showing the configuration of the fifth embodiment. In FIG. 14, the same parts as those in the first to fourth embodiments are denoted by the same reference numerals, and the description thereof is omitted. As shown in FIG. 14, the linear motor 80 according to the fifth embodiment has a pair of coil units 20 ₁ and 20 ₂ and a pair of magnet units 30 ₁ and 30 ₂ , as in the third and fourth embodiments. Control is performed so that the pair of coil units 20 ₁ , 20 ₂ are translationally driven at the same speed in the same direction. The substantially middle position of the parallel pair of magnetic poles base ₃₂ 1 arranged, 32 ₂ in the Y-direction, 1 pair of cancel magnets _36, 36 ₂ and the electromagnet ₆₂ 1, 62 ₂ are arranged. The pair of cancel magnets 36 ₁ , 36 ₂ and electromagnets 62 ₁ , 62 ₂ are provided at positions that are symmetrical in the Ya and Yb directions with the processing region B as the center.

Accordingly, the cancel magnets 36 ₁ , 36 ₂ and the electromagnets 62 ₁ , 62 ₂ are located on the magnetic field line passing through the processing region B, and the magnetic pole direction is the direction of the magnetic field vector by the permanent magnets 34 _{1 to} 34 n ( (Ya direction) and the opposite direction (Yb direction). In this configuration, the cancel magnets 36 ₁ and 36 ₂ and the electromagnets 62 ₁ and 62 ₂ can be provided in the vicinity of the processing region B. Therefore, the permanent magnet 34 _{1 is} generated by the magnetic fields of the cancel magnets 36 ₁ and 36 ₂ and the electromagnet 62. It is possible to directly cancel the magnetic field of the processing region B by ~ 34n. The electromagnets 62 ₁ and 62 ₂ function as auxiliary canceling means that is energized and cancels the magnetic field in the processing region B when a magnetic field that cannot be canceled by the cancel magnets 36 ₁ and 36 ₂ is generated in the processing region B.

FIG. 15 is a plan view showing the configuration of the sixth embodiment. In FIG. 15, the same parts as those in the first to fifth embodiments are denoted by the same reference numerals, and the description thereof is omitted. As shown in FIG. 15, the linear motor 90 according to the sixth embodiment includes a pair of coil units 20 ₁ and 20 ₂ and a pair of magnet units 30 ₁ and 30 ₂ , as in the _third to fifth embodiments. Control is performed so that the pair of coil units 20 ₁ , 20 ₂ are translationally driven at the same speed in the same direction. Magnet unit ₃₀ 1, 30 _2, the electromagnet ₆₂ 1, 62 ₂ are provided at the end of the pole base ₃₂ 1, 32 _2.

In this configuration, the magnetic field of the processing region B by the electromagnet ₆₂ 1, 62 ₂ of the permanent magnet ₃₄ 1 to 34N by a magnetic field can be canceled directly. Further, since the electromagnets 62 ₁ and 62 ₂ do not form a magnetic field when not energized, the electromagnets 62 ₁ and 62 ₂ are maintained in an off state when it is not necessary to cancel the magnetic fields of the permanent magnets 34 _{1 to} 34 n.

In the above embodiment, the cancel magnet 36 is provided at a height position that is substantially flush with the permanent magnets 34 _{1 to} 34 n. However, the present invention is not limited to this, and based on the result of the magnetic field analysis, the cancel magnet 36 is located above the permanent magnets 34 _{1 to} 34 n. It may be provided below.

  Further, in the above-described embodiment, the configuration example in which the cancel magnet 36 is disposed in the vicinity of the end portion of the magnetic pole base 32 or the processing region B on the side of the magnetic pole base 32 has been described. Based on this, a plurality of cancel magnets 36 may be provided around the processing area B.

It is a top view which shows one Example of the linear motor by this invention. It is a perspective view which cuts out and shows a part of linear motor. It is the longitudinal cross-sectional view which looked at the linear motor from the moving direction (Y direction). It is a figure which shows the state of the magnetic flux of the permanent magnet 34 and the cancellation magnet 36. FIG. A result of analyzing the state of the magnetic field by the permanent magnet 34 ₁ to 34N, is a distribution diagram showing the figure, the (B) is the distribution of the intensity of the magnetic field shown (A) is the direction of the magnetic field by the arrow. It is the result of having analyzed the state of the magnetic field by the cancellation magnet 36, (A) is a figure which shows the direction of a magnetic field with an arrow, (B) is a distribution map which shows the distribution state of the strength of a magnetic field. A result of analyzing the state of the magnetic field by the configuration in combination with the permanent magnet 34 ₁ to 34N and cancellation magnet 36, (A) is a diagram showing the direction of the magnetic field by the arrow, the (B) is the distribution of intensity of the magnetic field It is a distribution map shown. 6 is a plan view showing a configuration of Example 2. FIG. It is the result of having analyzed the state of Example 2 which installed cancellation magnet 36 in the magnetic field of processing field B, (A) shows the direction of a magnetic field with an arrow, and (B) shows the distribution state of the intensity of a magnetic field. It is a distribution map. A result of analyzing the state of the magnetic field due to configuration of the second embodiment in combination with the permanent magnet ₃₄ 1 to 34N and cancellation magnet _{36 1, 36 2, (A} ) is a diagram showing the direction of the magnetic field by the arrow, (B) is It is a distribution map which shows the distribution state of the strength of a magnetic field. 6 is a plan view showing a configuration of Example 3. FIG. It is a systematic diagram which shows the control system of the electromagnets 62 ₁ and 62 ₂ . 10 is a plan view showing a configuration of Example 4. FIG. FIG. 10 is a plan view showing a configuration of Example 5. 10 is a plan view showing the configuration of Example 6. FIG.

Explanation of symbols

10, 50, 60, 70, 80, 90 Linear motor 20 Coil unit 22 Coil 30 Magnet unit 32 Magnetic pole base 34 _{1 to} 34 n Permanent magnet 36 Cancel magnet 62 ₁ , 62 ₂ Electromagnet 64 ₁ to 64 ₄ Magnetic sensor 66 Control circuit 67 Analysis data table

Claims (10)

It has a coil part in which a plurality of coils are arranged in a straight line, and a magnet part in which a plurality of permanent magnets are arranged in parallel, and moves either the coil part or the magnet part. In the linear motor to be
A linear motor comprising canceling means for canceling a magnetic field in a predetermined region spaced apart from the magnet by a predetermined distance among magnetic fields formed around the magnet.   The linear motor according to claim 1, wherein the canceling unit is a permanent magnet and is disposed at a position where the magnetic field in the predetermined region is canceled.   The linear motor according to claim 1, wherein the canceling unit is an electromagnet and is disposed at a position where the magnetic field in the predetermined region is canceled.   The linear motor according to claim 1, wherein the canceling unit is a combination of a permanent magnet and an electromagnet, and is disposed at a position where the magnetic field in the predetermined region is canceled.   The linear motor according to claim 1, wherein the canceling unit is provided at an end of the magnet unit.   5. The linear motor according to claim 1, wherein the canceling unit is provided at a position overlapping with a magnetic field passing through a region extending in parallel with the magnet portion.   5. The linear motor according to claim 1, wherein the canceling unit is disposed at a position that is symmetrical with respect to a region that extends in parallel with the magnet portion.   The linear motor according to claim 1, wherein the canceling unit has an attachment position set based on a magnetic field analysis result obtained by analyzing a magnetic field around the linear motor.   The linear motor according to claim 1, wherein the canceling unit sets a magnetic force based on a magnetic field analysis result obtained by analyzing a magnetic field around the linear motor. The canceling means is
A magnetic field detection sensor for detecting a magnetic field around the linear motor;
Control means for controlling the current supplied to the electromagnet according to the state of the magnetic field detected by the magnetic field detection sensor;
The linear motor according to claim 3, wherein the linear motor is provided.

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