JP2011185368A - Magnetic bearing device and magnetic floating stage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic bearing device which maintains desired magnetic bearing characteristics even if weight of a floating body to be supported is changed, in a structure provided with an electromagnet and a permanent magnet for sandwiching an electromagnet target. <P>SOLUTION: This thrust magnetic bearing device 100 (magnetic bearing device) includes: the electromagnet target 1 attached to the floating body 110 and formed of magnetic material; the thrust electromagnet 2 including an upper magnetic pole portion 21 and an exciting coil 22, arranged oppositely to the electromagnet target 1, and supporting the electromagnet target 1 by magnetic attraction; and a thrust magnetic pole 3 arranged oppositely to the portion of the electromagnet target 1 on a side opposite to the thrust electromagnet 2, and including the permanent magnet 31 attracting the electromagnet target 1 by the magnetic attraction. The distance between the electromagnet target 1 and the thrust magnetic pole 3 can be adjusted. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetic bearing device and a magnetic levitation stage, and more particularly, to a magnetic bearing device including an electromagnet that supports an electromagnet target by a magnetic attractive force, and a magnetic levitation stage including such a magnetic bearing portion.

  2. Description of the Related Art Conventionally, a magnetic bearing device including an electromagnet that supports an electromagnet target with a magnetic attractive force is known (for example, see Patent Document 1).

  In Patent Document 1, an electromagnet including a magnetic pole and an excitation winding (excitation coil), an electromagnet target to which a rotating shaft (floating body) is attached and supported by the electromagnet, a housing that houses the electromagnet and the electromagnet target, A thrust bearing portion (magnetic bearing device) having a permanent magnet fixedly supported by a housing is disclosed. In this thrust bearing portion, an electromagnet is disposed below the electromagnet target, and a permanent magnet is disposed above the electromagnet target. As a result, the electromagnet target can be supported by the magnetic attraction force from both the upper and lower sides. Therefore, compared to the case where the electromagnet target is supported by the magnetic attraction force from one side, the rigidity (rigidity) that supports the electromagnet target is increased. It is thought that it can be increased.

JP-A-2-125105

  However, in Patent Document 1, the rigidity of the electromagnet target can be increased by the magnetic attraction force by the permanent magnet, while the magnetic attraction force by the permanent magnet is constant, so the weight of the rotating shaft (floating body) to be supported is When the electric current of the electromagnet is changed to support the rotating shaft at a fixed position, for example, the desired magnetic bearing characteristics can be maintained due to the constant attraction force of the permanent magnet. There is a problem that it is not possible.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to support the weight of a floating body to be supported in a configuration in which an electromagnet and a permanent magnet are provided so as to sandwich an electromagnet target. It is to provide a magnetic bearing device capable of maintaining desired magnetic bearing characteristics and a magnetic levitation stage equipped with such a magnetic bearing portion even when the angle changes.

Means for Solving the Problems and Effects of the Invention

  In order to achieve the above object, a magnetic bearing device according to a first aspect of the present invention includes an electromagnet target made of a magnetic material, a first magnetic pole, and an excitation coil, and is opposed to the electromagnet target. And an electromagnet that supports the electromagnet target with a magnetic attraction force, and a second magnet that includes a permanent magnet that is arranged to face the portion of the electromagnet target opposite to the electromagnet and that attracts the electromagnet target with the magnetic attraction force. The magnetic pole is provided, and the distance between the second magnetic pole and the electromagnet target is adjustable.

  In the magnetic bearing device according to the first aspect of the present invention, as described above, the electromagnet is disposed so as to face the electromagnet target, and the permanent magnet is included so as to face the portion of the electromagnet target opposite to the electromagnet. The magnetic attraction force by the second magnetic pole including the permanent magnet by adjusting the distance between the second magnetic pole and the electromagnet target by arranging the two magnetic poles and adjusting the distance between the second magnetic pole and the electromagnet target. Can be adjusted. Thus, in the configuration in which the electromagnet and the permanent magnet are provided so as to sandwich the electromagnet target, when the current of the electromagnet is changed to support the levitated body at a fixed position when the weight of the levitating body to be supported changes. However, by adjusting the magnetic attraction force by the permanent magnet (second magnetic pole), the magnetic bearing characteristics can be adjusted and the desired magnetic bearing characteristics can be maintained. In the magnetic bearing device according to the first aspect, the magnetic attraction force by the permanent magnet can be adjusted by adjusting the distance of the permanent magnet (second magnetic pole) to the electromagnet target. It can be easily changed according to.

  The magnetic bearing device according to the first aspect preferably further includes an actuator for adjusting the distance between the second magnetic pole and the electromagnet target. If comprised in this way, since the distance of a 2nd magnetic pole and an electromagnet target can be easily adjusted with an actuator, the magnetic attraction force by a 2nd magnetic pole can be adjusted easily. Thereby, even when the weight of the floating body to support changes, a magnetic bearing characteristic can be adjusted easily and a desired magnetic bearing characteristic can be maintained.

  In this case, preferably, the distance between the second magnetic pole and the electromagnet target is set to a desired magnetic bearing characteristic based on the current detection means for detecting the current flowing through the electromagnet and at least the current flowing through the electromagnet detected by the current detection means. And a control unit that controls the actuator so as to be a target distance between the second magnetic pole and the electromagnet target. If comprised in this way, even when the electric current which flows into an electromagnet changes with the weight of the floating body to support, the distance of a 2nd magnetic pole and an electromagnet target will be made into the target distance according to the electric current which flows into an electromagnet. The desired magnetic bearing characteristics can be easily maintained by adjustment.

  In the configuration including the control unit, preferably, a distance detection unit that detects a distance between the second magnetic pole and the electromagnet target, a current that flows through the electromagnet detected by the current detection unit, and a second that is detected by the distance detection unit. And a calculation unit that calculates a target distance between the second magnetic pole and the electromagnet target that provides desired magnetic bearing characteristics based on the distance between the magnetic pole and the electromagnet target. The actuator is configured to control the target distance. If comprised in this way, since the target part of a 2nd magnetic pole and an electromagnet target will be accurately computed by the calculating part based on both the electric current which flows into an electromagnet, and the distance of a 2nd magnetic pole and an electromagnet target, desired Magnetic bearing characteristics can be accurately maintained.

  In the configuration including the calculation unit, the calculation unit is preferably configured based on the current flowing through the electromagnet detected by the current detection unit and the distance between the second magnetic pole detected by the distance detection unit and the electromagnet target. In order to obtain the magnetic bearing characteristics, the target distance between the second magnetic pole and the electromagnet target for maintaining the compliance characteristic as an index of rigidity at a predetermined value is calculated. With this configuration, when the weight of the floating body to be supported changes, even when the current of the electromagnet is changed in order to support the floating body in a fixed position, the compliance characteristic serving as an index of rigidity is set to a predetermined value. By maintaining the value, desired magnetic bearing characteristics can be maintained.

  In the configuration including the actuator, the actuator is preferably configured to be driven by air pressure. If comprised in this way, a vibration can be effectively damped also when a vibration generate | occur | produces in an electromagnet target using the damping effect by the air pressure of the actuator which adjusts the distance of a 2nd magnetic pole and an electromagnet target. As a result, the vibration can be quickly reduced without separately providing a damping device for damping the vibration of the electromagnet target, so that the control response of the magnetic bearing device can be improved.

  In the magnetic bearing device according to the first aspect, preferably, the electromagnet includes a thrust electromagnet that is disposed above the electromagnet target and supports the electromagnet target with a magnetic attraction force in a vertically upward direction, and the second magnetic pole is the electromagnet target. And a thrust magnetic pole including a permanent magnet that attracts the electromagnet target vertically downward by a magnetic attraction force. With this configuration, in the magnetic bearing device that supports the electromagnet target in the vertical direction, even if the weight of the floating body to be supported changes, the magnetic attraction force in the vertical downward direction by the thrust magnetic pole with respect to the electromagnet target and the thrust electromagnet It is possible to maintain desired magnetic bearing characteristics by adjusting each of the magnetic attraction forces in the vertically upward direction.

  A magnetic levitation stage according to a second aspect of the present invention includes a levitation stage portion and a magnetic bearing portion that supports the levitation stage portion in the vertical direction, and the magnetic bearing portion is attached to the levitation stage portion and is made of a magnetic material. An electromagnet target, having a first magnetic pole and an exciting coil, arranged to face the electromagnet target, and opposed to the portion of the electromagnet target opposite to the electromagnet that supports the electromagnet target by magnetic attraction force And a second magnetic pole having a permanent magnet that attracts the electromagnet target with a magnetic attraction force, and is configured such that the distance between the second magnetic pole and the electromagnet target can be adjusted.

  In the magnetic levitation stage according to the second aspect of the present invention, as described above, the electromagnet is disposed so as to face the electromagnet target and the permanent magnet is included so as to face the portion of the electromagnet target opposite to the electromagnet. The magnetic attraction force by the second magnetic pole including the permanent magnet by adjusting the distance between the second magnetic pole and the electromagnet target by arranging the two magnetic poles and adjusting the distance between the second magnetic pole and the electromagnet target. Can be adjusted. Thus, in the configuration in which the electromagnet and the permanent magnet are provided so as to sandwich the electromagnet target, the current of the electromagnet is changed in order to support the levitation stage portion at a fixed position when the weight of the levitation stage portion to be supported changes. Even in this case, by adjusting the magnetic attractive force by the permanent magnet (second magnetic pole), it is possible to adjust the magnetic bearing characteristics and maintain the desired magnetic bearing characteristics. In the magnetic levitation stage according to the second aspect, the magnetic attraction force by the permanent magnet can be adjusted by adjusting the distance of the permanent magnet (second magnetic pole) to the electromagnet target. It can be easily changed according to.

  In the magnetic levitation stage according to the second aspect, preferably, an actuator that adjusts a distance between the second magnetic pole and the electromagnet target, and a first horizontal that drives the levitation stage portion in a non-contact state in a first horizontal direction in a horizontal plane. A direction driving unit, and a second horizontal direction driving unit that drives the levitation stage unit in a non-contact state in a second horizontal direction within a horizontal plane orthogonal to the first horizontal direction. If constituted in this way, even when a disturbance occurs in the levitation stage part due to the movement in the horizontal plane by the first horizontal direction drive unit and the second horizontal direction drive unit, in the magnetic levitation stage according to the second aspect, Since the desired magnetic bearing characteristics can be maintained by adjusting the magnetic bearing characteristics of the magnetic bearing section by the actuator, a stable levitation state of the levitation stage section can be obtained. As a result, the first horizontal driving section and By the second horizontal direction drive unit, the levitation stage unit can be stably operated in the horizontal plane.

It is the schematic which shows the thrust magnetic bearing apparatus by 1st Embodiment of this invention. It is a schematic plan view which shows the whole structure of the magnetic levitation stage by 2nd Embodiment of this invention. It is a schematic sectional drawing in alignment with line 300-300 of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
With reference to FIG. 1, the structure of the thrust magnetic bearing apparatus 100 by 1st Embodiment of this invention is demonstrated. The thrust magnetic bearing device 100 is an example of the “magnetic bearing device” in the present invention.

  As shown in FIG. 1, the thrust magnetic bearing device 100 according to the first embodiment of the present invention is configured to float the floating body 110 in a non-contact manner at a predetermined position (fixed position) in the vertical direction (Z direction). Yes. The thrust magnetic bearing device 100 includes an electromagnet target 1 attached to the levitated body 110, a thrust electromagnet 2 disposed above the electromagnet target 1 (in the Z1 direction) at a predetermined distance, and below the electromagnet target 1. And a thrust magnetic pole 3 including a permanent magnet 31 disposed at a predetermined distance in the (Z2 direction). The thrust electromagnet 2 is an example of the “electromagnet” in the present invention, and the thrust magnetic pole 3 is an example of the “second magnetic pole” in the present invention.

  The electromagnet target 1 is made of a magnetic material and is formed to extend in the horizontal direction. Further, the thrust electromagnet 2 is fixedly attached to the upper frame 120 and is installed so as to face the upper surface (the surface in the Z1 direction) of the electromagnet target 1. The thrust electromagnet 2 includes an upper magnetic pole portion 21 and an exciting coil 22 wound around the upper magnetic pole portion 21. The thrust electromagnet 2 is configured to support the electromagnet target 1 by a magnetic attraction force in a vertically upward direction (Z1 direction). Specifically, the thrust electromagnet 2 causes a current to flow through the exciting coil 22 to generate a magnetic attraction force in the vertically upward direction. The upper magnetic pole portion 21 is an example of the “first magnetic pole” in the present invention.

  The thrust magnetic pole 3 is disposed so as to face the lower surface (the surface in the Z2 direction) of the electromagnet target 1. Moreover, the thrust magnetic pole 3 is comprised by the above-mentioned permanent magnet 31 and the lower magnetic pole part 32 by which the permanent magnet 31 is arrange | positioned in the center part. That is, the lower magnetic pole portion 32 has a concave shape and is disposed so that the permanent magnet 31 is embedded in the central portion of the concave bottom surface. The permanent magnet 31 has an N pole and an S pole arranged in the left-right direction (horizontal direction). In addition, the thrust magnetic pole 3 is configured to attract the electromagnet target 1 by a magnetic attraction force in a vertically downward direction (Z2 direction). Further, by attracting the electromagnet target 1 in the vertical downward direction (Z2 direction) by the magnetic attraction force by the thrust magnetic pole 3 in addition to gravity, the electromagnet target 1 is attracted by gravity alone in the vertical downward direction. Thus, the rigidity of the electromagnet target 1 can be increased.

  Here, in the first embodiment, the thrust magnetic pole 3 is configured to be movable in the vertical direction (Z direction) by the actuator 33, and the separation distance D from the electromagnet target 1 is configured to be adjustable. The actuator 33 is fixedly installed on the upper surface of the lower frame 130 and is disposed on the lower side (Z2 direction side) of the thrust magnetic pole 3. The actuator 33 is configured to be driven by air pressure.

  The thrust magnetic bearing device 100 includes an upper sensor 4 for detecting a separation distance between the electromagnet target 1 and the thrust electromagnet 2 and a lower side for detecting a separation distance D between the electromagnet target 1 and the thrust magnetic pole 3. A sensor 5 is provided. The upper sensor 4 is a gap sensor, and is fixedly attached to the lower surface of the upper frame 120 to which the thrust electromagnet 2 is attached. The lower sensor 5 is a gap sensor and is fixedly attached to the lower magnetic pole portion 32 of the thrust magnetic pole 3. The lower sensor 5 is an example of the “distance detection means” in the present invention.

  The thrust magnetic bearing device 100 controls the drive of the current detector 6 that detects the current flowing through the exciting coil 22, the calculator 7 that calculates the target separation distance between the electromagnet target 1 and the thrust magnetic pole 3, and the actuator 33. And a controller 8. The current detector 6 is an example of the “current detection unit” in the present invention, and the calculator 7 is an example of the “calculation unit” in the present invention. The controller 8 is an example of the “control unit” in the present invention.

  The computing unit 7 is configured to acquire the detection result of the current flowing through the exciting coil 22 from the current detector 6 and to acquire the detection result of the separation distance D between the electromagnet target 1 and the thrust magnetic pole 3 from the lower sensor 5. Has been. Further, the computing unit 7 is based on the current flowing in the exciting coil 22 and the separation distance D between the electromagnet target 1 and the thrust magnetic pole 3 when an external force is generated in the levitated body 110 due to a change in the weight of the levitated body 110 or a disturbance. The external force of the levitated body 110 is estimated and the target separation distance between the electromagnet target 1 and the thrust magnetic pole 3 is calculated. Here, in the first embodiment, in order to maintain desired magnetic bearing characteristics while supporting the electromagnet target 1 at a fixed position when an external force is generated in the levitated body 110 due to a change in weight or disturbance of the levitated body 110. The distance between the electromagnet target 1 and the thrust magnetic pole 3 is set as the target separation distance.

  In the first embodiment, the arithmetic unit 7 has a desired magnetic bearing characteristic while supporting the levitated body 110 at a fixed position even when an external force is generated on the levitated body 110 due to a change in weight or disturbance of the levitated body 110. A distance between the electromagnet target 1 and the thrust magnetic pole 3 for maintaining the value is acquired as a target separation distance. Here, by adjusting the magnetic attraction force of the thrust magnetic pole 3 (permanent magnet 31) with respect to the electromagnet target 1 by adjusting the distance between the electromagnet target 1 and the thrust magnetic pole 3, the unbalanced rigidity Ku of the magnetic bearing device can be reduced. It is possible to adjust. Therefore, by adjusting the distance between the electromagnet target 1 and the thrust magnetic pole 3, it is possible to adjust the compliance characteristic that is an index of rigidity.

  The controller 8 is configured to operate the actuator 33 in the Z direction so that the distance between the electromagnet target 1 and the thrust magnetic pole 3 becomes the target separation distance based on the calculation result by the calculator 7.

  Next, in the thrust magnetic bearing device 100 according to the first embodiment, an operation when an external force is generated in the levitated body 110 will be described.

  First, when an external force is generated in the levitation body 110 due to a change in the weight of the levitation body 110, disturbance, or the like, the current flowing through the exciting coil 22 is changed in order to support the electromagnet target 1 at a fixed position. Vary the magnetic attraction force. Then, based on the current of the thrust electromagnet 2 detected by the current detector 6 and the separation distance D between the electromagnet target 1 and the thrust magnetic pole 3 detected by the lower sensor 5 by the calculator 7, the electromagnet target 1 and the thrust A target separation distance from the magnetic pole 3 is calculated. Specifically, the calculator 7 is a distance between the electromagnet target 1 and the thrust magnetic pole 3 so as not to change the magnetic bearing characteristics while the levitated body 110 is supported at a fixed position before and after an external force is generated in the levitated body 110. Ask for. Thereafter, the controller 8 drives the actuator 33 in the Z direction so that the separation distance D between the electromagnet target 1 and the thrust magnetic pole 3 becomes the target separation distance. As a result, the magnetic attractive force in the vertically downward direction by the thrust magnetic pole 3 can be changed to a desired magnitude.

  In the first embodiment, as described above, the thrust electromagnet 2 is disposed so as to face the upper surface of the electromagnet target 1, and the thrust magnetic pole 3 including the permanent magnet 31 is disposed so as to face the lower surface of the electromagnet target 1. The magnetic attraction by the thrust magnetic pole 3 including the permanent magnet 31 by adjusting the separation distance D between the electromagnet target 1 and the thrust magnetic pole 3 by configuring the separation distance D between the electromagnet target 1 and the thrust magnetic pole 3 to be adjustable. The power can be adjusted. Thus, in the configuration in which the thrust electromagnet 2 and the permanent magnet 31 are provided so as to sandwich the electromagnet target 1, the thrust electromagnet 2 is used to support the levitated body 110 at a fixed position when the weight of the levitated body 110 to be supported changes. Even when this current is changed, by adjusting the magnetic attraction force by the permanent magnet 31 (thrust magnetic pole 3), the magnetic bearing characteristics can be adjusted and the desired magnetic bearing characteristics can be maintained. As a result, a stable floating state can be obtained with respect to the weight change of the floating body 110. Further, in this thrust magnetic bearing device 100, since the magnetic attraction force by the permanent magnet 31 can be adjusted by adjusting the separation distance D of the thrust magnetic pole 3 including the permanent magnet 31 with respect to the electromagnet target 1, the magnetic bearing characteristics once set. Can be easily changed according to the situation.

  In the first embodiment, as described above, by providing the actuator 33 that adjusts the separation distance D between the electromagnet target 1 and the thrust magnetic pole 3, the separation distance D between the electromagnet target 1 and the thrust magnetic pole 3 can be easily set. Since it can be adjusted, the magnetic attractive force by the thrust magnetic pole 3 can be easily adjusted. Thereby, even when the weight of the floating body 110 to support is changed, a magnetic bearing characteristic can be adjusted easily and a desired magnetic bearing characteristic can be maintained.

  Further, in the first embodiment, as described above, based on the current flowing through the thrust electromagnet 2, the separation distance D between the electromagnet target 1 and the thrust magnetic pole 3 is set to the electromagnet target 1 and the thrust magnetic pole that can obtain desired magnetic bearing characteristics. Even if the current flowing through the thrust electromagnet 2 is changed with the change in the weight of the floating body 110 to be supported, the electromagnet is provided. The desired magnetic bearing characteristics can be easily maintained by adjusting the separation distance D between the target 1 and the thrust magnetic pole 3 to the target separation distance corresponding to the current flowing through the thrust electromagnet 2.

  In the first embodiment, as described above, the electromagnet target 1 that obtains desired magnetic bearing characteristics based on the current flowing through the thrust electromagnet 2 and the separation distance D between the electromagnet target 1 and the thrust magnetic pole 3. An arithmetic unit 7 for calculating the target separation distance from the thrust magnetic pole 3 is provided, and the controller 8 is configured to control the actuator 33 so that the target separation distance calculated by the arithmetic unit 7 is obtained. The device 7 accurately calculates the target separation distance between the electromagnet target 1 and the thrust magnetic pole 3 based on both the current flowing through the thrust electromagnet 2 and the separation distance D between the electromagnet target 1 and the thrust magnetic pole 3. Magnetic bearing characteristics can be accurately maintained.

  Further, in the first embodiment, as described above, the computing characteristic 7 causes the compliance characteristic to be an index of rigidity based on the current flowing through the thrust electromagnet 2 and the separation distance D between the electromagnet target 1 and the thrust magnetic pole 3. By calculating the target separation distance between the electromagnet target 1 and the thrust magnetic pole 3 for maintaining a predetermined value, the floating body 110 is supported at a fixed position when the weight of the supporting floating body 110 changes. Even when the current of the thrust electromagnet 2 is changed, the compliance characteristic serving as an index of rigidity can be maintained at a predetermined value. Thereby, desired magnetic bearing characteristics can be maintained.

  In the first embodiment, as described above, the actuator 33 is driven by air pressure, thereby adjusting the separation distance D between the electromagnet target 1 and the thrust magnetic pole 3. The vibration can be effectively damped even when vibration occurs in the electromagnet target 1. As a result, the vibration can be quickly reduced without separately providing a damping device for damping the vibration of the electromagnet target 1, so that the control response of the thrust magnetic bearing device 100 can be improved.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS. In the second embodiment, a case where a thrust magnetic bearing device 100a having the same configuration as the thrust magnetic bearing device 100 of the first embodiment is applied to a magnetic levitation stage 200 will be described. Note that in the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The thrust magnetic bearing device 100a is an example of the “magnetic bearing portion” in the present invention.

  The magnetic levitation stage 200 according to the second embodiment of the present invention is used in an exposure apparatus that develops a circuit pattern on a semiconductor substrate, and is configured to support a wafer. 2 and 3, the magnetic levitation stage 200 extends in the Y direction on both sides of the inverted U-shaped levitation stage portion 201 and the levitation stage portion 201 in the X direction as seen from the Y direction. And two formed thrust magnetic bearing devices 100a. The levitation stage unit 201 is attached to the two electromagnet targets 1 of the two thrust magnetic bearing devices 100a at both ends in the X direction. The levitation stage unit 201 is an example of the “levitation body” in the present invention.

  The magnetic levitation stage 200 further includes a housing 202 that houses two thrust magnetic bearing devices 100 a therein, and a wafer holder 203 installed on the levitation stage unit 201. Two thrust electromagnets 2 of the two thrust magnetic bearing devices 100a are fixedly installed on the inner upper surface of the housing 202. The two thrust electromagnets 2 are arranged so as to sandwich the levitation stage 201 from both sides in the X direction. Each thrust electromagnet 2 is installed so as to face the upper surface (surface in the Z1 direction) of the corresponding electromagnet target 1 attached to the levitation stage unit 201. Further, the upper sensor 4 is fixedly installed on the inner upper surface of the housing 202 so as to be adjacent to each thrust electromagnet 2.

  In addition, two actuators 33 of the two thrust magnetic bearing devices 100a are fixedly installed on the inner lower surface of the housing 202. Two thrust magnetic poles 3 are provided above the two actuators 33 so as to be movable in the vertical direction (Z direction). Each thrust magnetic pole 3 is installed so as to face the lower surface (surface in the Z2 direction) of the corresponding electromagnet target 1 attached to the levitation stage unit 201. Here, also in the second embodiment, the two thrust magnetic poles 3 including the two permanent magnets 31 are driven in the vertical direction by the two actuators 33, so that the separation distance between the electromagnet target 1 and the thrust magnetic pole 3 is increased. It can be adjusted. The lower sensor 5 is fixedly attached to the lower magnetic pole portion 32 of each thrust magnetic pole 3. With the above configuration, the magnetic levitation stage 200 supports the levitation stage unit 201 in a non-contact manner at a predetermined position (fixed position) in the vertical direction (Z direction) by the two thrust magnetic bearing devices 100a.

  Further, as shown in FIG. 2, a pair of X linear motors 204a and 204b for operating the levitation stage unit 201 in the X direction are provided on both sides of the levitation stage unit 201 in the Y direction. The pair of X linear motors 204a and 204b are formed to extend in the X direction. As shown in FIG. 3, a pair of Y linear motors 205 a and 205 b for operating the levitation stage unit 201 in the Y direction are provided inside the levitation stage unit 201. The pair of Y linear motors 205a and 205b are formed to extend in the Y direction. Thereby, in the magnetic levitation stage 200, the levitation stage unit 201 can be operated in the three-axis directions of the X direction, the Y direction, and the Z direction. The X linear motors 204a and 204b are examples of the “first horizontal driving unit” in the present invention, and the Y linear motors 205a and 205b are examples of the “second horizontal driving unit” in the present invention.

  Although not shown in FIGS. 2 and 3, the two thrust magnetic bearing devices 100a of the second embodiment are also provided with the same current detector 6, arithmetic unit 7 and controller 8 as those of the first embodiment. Is provided.

  In addition, the other structure of 2nd Embodiment is the same as that of the said 1st Embodiment.

  In the second embodiment, as described above, the two thrust electromagnets 2 are arranged so as to face the upper surfaces of the two electromagnet targets 1, and the permanent magnet 31 is included so as to face the lower surfaces of the two electromagnet targets 1. The permanent magnet 31 is included by adjusting the separation distance between the electromagnet target 1 and the thrust magnetic pole 3 by arranging two thrust magnetic poles 3 and adjusting the separation distance between the electromagnet target 1 and the thrust magnetic pole 3. The magnetic attractive force by the two thrust magnetic poles 3 can be adjusted. Thus, in the configuration in which the two thrust electromagnets 2 and the two permanent magnets 31 are provided so as to sandwich the two electromagnet targets 1, when the weight of the supported levitating stage 201 changes, the levitating stage 201 is placed at a fixed position. Even when the currents of the two thrust electromagnets 2 are changed in order to support them, the magnetic attraction force by the two permanent magnets 31 (thrust magnetic poles 3) is adjusted, thereby adjusting the magnetic bearing characteristics and the desired magnetism. Bearing characteristics can be maintained. As a result, a stable floating state can be obtained with respect to a change in the weight of the floating stage unit 201. Further, in this magnetic levitation stage 200, the magnetic attraction force by the two permanent magnets 31 can be adjusted by adjusting the separation distance of the permanent magnets 31 (thrust magnetic poles 3) from the electromagnet target 1. Can be easily changed according to the situation.

  In the second embodiment, the two permanent magnets of the two thrust magnetic bearing devices 100a are provided even when a disturbance occurs in the levitation stage 201 as the X linear motors 204a and 204b and the Y linear motors 205a and 205b are driven. By adjusting the magnetic attraction force by 31, the magnetic bearing characteristics can be adjusted and desired magnetic bearing characteristics can be maintained. Thereby, since the stable floating state of the floating stage unit 201 can be obtained, the floating stage unit 201 can be stably operated in the horizontal plane by the X linear motors 204a and 204b and the Y linear motors 205a and 205b. .

  The remaining effects of the second embodiment are similar to those of the aforementioned first embodiment.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the first and second embodiments, the example in which the thrust electromagnet is disposed above the electromagnet target and the thrust magnetic pole as the second magnetic pole is disposed below the electromagnet target is shown. Not limited to. In this invention, the structure which arrange | positions an electromagnet below an electromagnet target and arrange | positions a 2nd magnetic pole above an electromagnet target may be sufficient.

  Moreover, in the said 1st and 2nd embodiment, although the thrust magnetic bearing apparatus which supports an electromagnet target in a perpendicular direction was shown as an example of a magnetic bearing apparatus, this invention is not limited to this. In this invention, the magnetic bearing apparatus which supports an electromagnet target in a horizontal direction may be sufficient, and the magnetic bearing apparatus which supports in directions other than a vertical direction and a horizontal direction may be sufficient.

  In the first and second embodiments, the example in which the distance between the electromagnet target and the thrust magnetic pole as the second magnetic pole is adjusted by the actuator is shown, but the present invention is not limited to this. In the present invention, any configuration may be used as long as the distance between the electromagnet target and the second magnetic pole can be adjusted. For example, the configuration may be such that the distance between the electromagnet target and the second magnetic pole is manually adjusted.

  Moreover, in the said 1st and 2nd embodiment, although the example of the structure which drives an actuator with an air pressure was shown, this invention is not limited to this. In the present invention, the actuator may be driven by other than air pressure.

  In the first and second embodiments, the target separation distance between the electromagnet target and the thrust magnetic pole is set based on both the current flowing through the thrust electromagnet and the distance between the electromagnet target and the thrust magnetic pole as the second magnetic pole. Although the example of the structure which calculates is shown, this invention is not limited to this. In the present invention, as long as it is based on the current flowing through the electromagnet, the target separation distance between the electromagnet target and the thrust magnetic pole may be calculated based only on the current flowing through the electromagnet. The current flowing through the electromagnet and the electromagnet target The target separation distance may be calculated based on other factors in addition to the distance between the first magnetic pole and the second magnetic pole.

  In the first and second embodiments, as an example of the distance detection unit, the lower sensor including the gap sensor that detects the distance between the electromagnet target and the thrust magnetic pole as the second magnetic pole is shown. It is not limited to this. In the present invention, if the distance between the electromagnet target and the second magnetic pole can be detected, for example, the distance between the electromagnet target and the second magnetic pole is obtained by detecting the driving distance of the actuator (movement distance of the second magnetic pole). It may be a distance detection means.

  Moreover, although the example which applies the thrust magnetic bearing apparatus as a magnetic bearing apparatus to the magnetic levitation stage used for exposure apparatus was shown in the said 2nd Embodiment, this invention is not limited to this. You may apply the magnetic bearing apparatus of this invention to the apparatus used for uses other than exposure apparatus.

1 Electromagnet Target 2 Thrust Electromagnet (Electromagnet)
3 Thrust magnetic pole (second magnetic pole)
5 Lower sensor (distance detection means)
6 Current detector (current detection means)
7 Calculator (Calculator)
8 Controller (control unit)
21 Upper magnetic pole part (first magnetic pole)
22 Excitation coil 31 Permanent magnet 33 Actuator 100, 100a Thrust magnetic bearing device (magnetic bearing device, magnetic bearing portion)
DESCRIPTION OF SYMBOLS 110 Levitation body 200 Magnetic levitation stage 201 Levitation stage part 204a, 204b X linear motor (1st horizontal direction drive part)
205a, 205b Y linear motor (second horizontal driving unit)

Claims (9)

An electromagnet target made of a magnetic material attached to a floating body;
An electromagnet including a first magnetic pole and an excitation coil, disposed to face the electromagnet target, and supporting the electromagnet target by a magnetic attraction;
A second magnetic pole including a permanent magnet that is disposed so as to face a portion of the electromagnet target opposite to the electromagnet and that attracts the electromagnet target with a magnetic attraction force;
A magnetic bearing device configured to be capable of adjusting a distance between the second magnetic pole and the electromagnet target.   The magnetic bearing device according to claim 1, further comprising an actuator that adjusts a distance between the second magnetic pole and the electromagnet target. Current detecting means for detecting a current flowing through the electromagnet;
Based on at least the current flowing through the electromagnet detected by the current detection means, the distance between the second magnetic pole and the electromagnet target is determined based on the target between the second magnetic pole and the electromagnet target that provides desired magnetic bearing characteristics. The magnetic bearing device according to claim 2, further comprising a control unit that controls the actuator so as to be a distance. Distance detecting means for detecting a distance between the second magnetic pole and the electromagnet target;
Based on the current flowing through the electromagnet detected by the current detection means and the distance between the second magnetic pole and the electromagnet target detected by the distance detection means, the desired magnetic bearing characteristics can be obtained. A calculation unit for calculating a target distance between the two magnetic poles and the electromagnet target;
The magnetic bearing device according to claim 3, wherein the control unit is configured to control the actuator so that the target distance calculated by the calculation unit is reached.   The calculation unit is configured to generate the desired magnetic bearing characteristics based on a current flowing through the electromagnet detected by the current detection unit and a distance between the second magnetic pole and the electromagnet target detected by the distance detection unit. 5 is configured to calculate a target distance between the second magnetic pole and the electromagnet target for maintaining a compliance characteristic serving as an index of rigidity at a predetermined value. Magnetic bearing device.   The magnetic bearing device according to claim 2, wherein the actuator is configured to be driven by air pressure. The electromagnet is disposed above the electromagnet target and includes a thrust electromagnet that supports the electromagnet target with a magnetic attraction force in a vertically upward direction.
The said 2nd magnetic pole is arrange | positioned under the said electromagnet target, and contains the thrust magnetic pole containing the permanent magnet which attracts | sucks the said electromagnet target vertically downward with a magnetic attraction force. Magnetic bearing device. A floating stage,
A magnetic bearing portion that supports the levitation stage portion in the vertical direction;
The magnetic bearing portion is
An electromagnet target attached to the levitation stage and made of a magnetic material;
An electromagnet having a first magnetic pole and an exciting coil, disposed to face the electromagnet target, and supporting the electromagnet target by a magnetic attraction;
A second magnetic pole having a permanent magnet that is disposed so as to face a portion of the electromagnet target opposite to the electromagnet and that attracts the electromagnet target by a magnetic attraction force;
A magnetic levitation stage configured to be capable of adjusting a distance between the second magnetic pole and the electromagnet target. An actuator for adjusting a distance between the second magnetic pole and the electromagnet target;
A first horizontal driving unit that drives the levitation stage unit in a non-contact state in a first horizontal direction within a horizontal plane;
9. The magnetic levitation stage according to claim 8, further comprising a second horizontal direction drive unit that drives the levitation stage unit in a non-contact state in a second horizontal direction within a horizontal plane orthogonal to the first horizontal direction.

Images