JP2020533781A - Distance sensors for measuring distances to ferromagnetic elements, magnetic levitation systems, and methods for measuring distances to ferromagnetic elements - Google Patents

Abstract

The present disclosure relates to a distance sensor for measuring the distance to a ferromagnetic element, a magnetic levitation system for magnetically levating the ferromagnetic element, and a method for correcting a stray magnetic field in the distance sensor. According to the first aspect, a distance sensor for measuring the distance to the ferromagnetic element is provided. According to the second aspect, a magnetic levitation system for magnetically levitation of a ferromagnetic element is provided. The magnetic levitation system comprises at least one electromagnetic actuator and at least one distance sensor according to the first embodiment, the at least one distance sensor configured to measure the distance to a ferromagnetic element. There is. According to the third aspect, a method for measuring the distance to the ferromagnetic element is provided. In this method, a distance sensor including a first Hall element and a second Hall element is provided, and a first signal of the first Hall element and a second signal of the second Hall element are detected. This includes subtracting the second signal from the first signal. According to the fourth aspect, the use of the distance sensor according to the first aspect is provided. The distance sensor is used in a magnetic levitation device and the distance sensor is configured to measure the distance to the levitation body. [Selection diagram] FIG. 3a

Description

An embodiment of the present disclosure relates to a distance sensor for measuring a distance to a ferromagnetic element. More specifically, embodiments of the present disclosure relate, in particular, to magnetic levitation systems for magnetically levitation of ferromagnetic elements and methods for compensating for stray magnetic fields in distance sensors.

Systems are known to perform a variety of processes (eg, coating the substrate in a processing chamber). There are several known methods for depositing material on a substrate. As an example, the substrate can be coated by using an evaporation process, a physical vapor deposition (PVD) process (such as a sputtering process or a spray process), or a chemical vapor deposition (CVD) process. The treatment can be performed in the processing chamber of the depositor. The substrate to be coated is arranged here. The deposited material is fed into the treatment chamber. Multiple materials such as small molecules, metals, oxides, nitrides, and carbides can be used for deposition on substrates. In addition, other processes such as etching, structuring and annealing can be performed in the processing chamber.

For example, coating treatments can be considered for large area substrates, for example in display manufacturing techniques. The coated substrate can be used in several applications and in some technical fields. For example, one application may be an organic light emitting diode (OLED) panel. Further applications include insulating panels, microelectronics such as semiconductor devices, substrates with thin film transistors (TFTs), color filters and the like. An OLED is a solid device composed of a thin film of (organic) molecules that generate light when electricity is applied. As an example, an OLED display can be provided with a bright display in an electronic device and uses less power than, for example, a liquid crystal display (LCD). In the processing chamber, organic molecules are generated (eg, evaporation, sputtering, spraying, etc.) and deposited as layers on the substrate. The particles can pass, for example, a boundary or a mask having a particular pattern, whereby the material is deposited at a particular location on the substrate, for example, an OLED pattern is formed on the substrate.

The processing system may include, for example, a magnetic levitation system for guiding carriers in the processing chamber during the coating process. The magnetic levitation system may be adapted to provide the carrier in the processing position and / or to transport the carrier within the processing chamber. The magnetic levitation system may include one or more levitation units having an electromagnetic actuator, a sensor, a signal processor, and a power amplifier to form a closure control loop, whereby the levitation carrier is defined from the magnetic bearing. Is maintained at a distance of.

In applications where the substrate is processed in high vacuum, metal shielding of actuators, sensors, and other components renders some types of distance sensors unusable. In such applications, distance sensors based on magnetic effects, such as Hall effect sensors, are used. This is because such distance sensors can measure distance through a non-ferrous metal shield.

One aspect of the magnetic levitation system is to place the electromagnetic actuator and the distance sensor in close proximity to each other in the levitation system. This achieves a minimized size of the magnetic levitation system and improved control behavior due to juxtaposition of actuators and sensors.

In view of the above, an aspect of the present disclosure is to provide a distance sensor and a method for operating the distance sensor that overcomes at least some of the problems in the art.

According to the first embodiment, a distance sensor for measuring the distance to the ferromagnetic element is provided. The distance sensor includes at least a first permanent magnet element, at least a first Hall element, and at least a second Hall element, the first permanent magnet element generating a first magnetic field and a first Hall element. The direction of the first magnetic field at the position of is substantially opposite to the direction of the first magnetic field at the position of the second Hall element.

According to the second embodiment, a magnetic levitation system for magnetically levitation of a ferromagnetic element is provided. The magnetic levitation system comprises at least one electromagnetic actuator and at least one distance sensor according to the first embodiment, the at least one distance sensor configured to measure the distance to a ferromagnetic element. There is.

According to the third embodiment, a distance sensor for measuring the distance to the ferromagnetic element is provided. In this method, a distance sensor including a first Hall element and a second Hall element is provided, and a first signal of the first Hall element and a second signal of the second Hall element are detected. This includes subtracting the second signal from the first signal.

According to the fourth embodiment, the use of the distance sensor according to the first embodiment is provided. The distance sensor is used in a magnetic levitation device and the distance sensor is configured to measure the distance to the levitation body.

The embodiments further cover the apparatus for performing the disclosed methods and include parts of the apparatus for performing each of the described method steps. These method steps may be performed by hardware components, a computer programmed with the appropriate software, any combination of the two, or any other method. Furthermore, the embodiments according to the present disclosure also cover the methods by which the described devices operate. Includes method steps for performing all functions of the device.

By referring to embodiments, a more specific description of the present disclosure briefly summarized above can be obtained so that the above-mentioned features of the present disclosure can be understood in detail. The accompanying drawings are described below with respect to embodiments of the present disclosure.
A schematic front view of the magnetic levitation system according to the embodiment described in the present specification is shown. A side sectional view of the magnetic levitation system according to the embodiment described in the present specification is shown. A front sectional view of the magnetic levitation system according to the embodiment described in the present specification is shown. A side sectional view of the distance sensor according to the embodiment described in the present specification is shown. A side sectional view of the distance sensor according to the embodiment described in the present specification is shown. The flow chart of the method for measuring the distance to a ferromagnetic element which concerns on embodiment described in this specification is shown. A flow chart of a method for further correcting an erroneous component of a distance signal according to an embodiment described in the present specification is shown.

The various embodiments of the present disclosure will be referred to in more detail. One or more embodiments of these embodiments are shown in the drawings. In the following description of the drawings, the same reference numbers represent the same components. In general, only differences regarding individual embodiments are explained. Each example is provided for illustration purposes of the present disclosure, but is not intended to limit the present disclosure. Furthermore, the features illustrated and described as part of one embodiment may be used in other embodiments or in conjunction with other embodiments, thereby resulting in yet another embodiment. .. This description is intended to include such modifications and modifications.

The embodiments described herein relate to magnetic levitation and / or transport of carriers (eg, substrate carriers). Thus, the magnetic levitation of the carrier can be non-contact. The term "contactless" as used throughout this disclosure can be understood to mean that the weight of the carrier is not held by mechanical contact or mechanical force, but by magnetic force. .. In particular, magnetic forces can be used instead of mechanical forces to keep the carriers in a floating or floating state. In some implementations, there may be no mechanical contact between the carrier and other devices during levitation of the carrier in the system and, for example, movement.

Compared to mechanical devices that guide carriers within a processing system, non-contact levitation has the advantage of not being bothered by friction that affects the linearity and / or accuracy of carrier motion. The non-contact transport of the carriers enables frictionless motion of the carriers, for example, the position of the carriers with respect to the mask can be controlled and maintained with high accuracy in the deposition process. Further, levitation allows for rapid acceleration or deceleration of the carrier and / or fine adjustment of the carrier speed.

For example, non-contact levitation or transfer of carriers during the deposition process is beneficial in that no particles are generated by mechanical contact between the carrier and the section of the device (eg, mechanical rails) during carrier transfer. Is. Therefore, non-contact magnetic levitation systems provide, in particular, improvements in the purity and uniformity of the layers deposited on the substrate, as the use of non-contact levitation minimizes particle generation.

The magnetic levitation system can be configured to operate in vacuum space. The processing system may include at least one vacuum chamber and the deposition process is performed on the substrate. The at least one vacuum chamber may include one or more vacuum pumps, such as turbo pumps and / or cryopumps, connected to the vacuum chamber to create a vacuum inside the vacuum chamber. The magnetic levitation system may be configured to transport the substrate in and out of the vacuum chamber or through the vacuum chamber.

Magnetic levitation systems can be used to carry carriers. The carrier may be adapted to carry a substrate, multiple substrates, and / or masks. The carrier may be, for example, a substrate carrier adapted to carry a large area substrate and / or a plurality of large area substrates. Alternatively, the carrier may be, for example, a mask carrier adapted to carry an edge exclusion mask that prevents coating of the edges of the substrate in the deposition process.

The carriers according to the embodiments described herein need not be limited to substrate carriers or mask carriers. The methods described herein also apply to other types of carriers, i.e., carriers adapted to carry objects or devices other than, for example, substrates or masks.

As used herein, the term "subject" refers to non-flexible substrates (eg, slices of transparent crystals such as glass substrates, wafers, sapphires, or glass plates) and flexible substrates (eg, web or foil). Including both. According to embodiments that can be combined with other embodiments described herein, the embodiments described herein are for display PVD, ie, sputter deposition on large area substrates for the display market. Can be used for.

According to embodiments, the large area substrate or corresponding carrier can have a size of at least 0.67 m ² . This size may range from about 0.67 m ² (0.73 x 0.92 m-Gen4.5) to about 8 m ² , more specifically from about ² m ² to about 9 m ² or even up to. It may be 12 m ² . For example, large area substrates or carrier, corresponds to GEN4.5 corresponds to about 0.67 m ² substrate (0.73 × 0.92 m), about 1.4 m ² substrate (1.1 m × 1.3 m) GEN5, GEN7.5 corresponding to a substrate of about 4.29 m ² (1.95 m x 2.2 m), GEN 8.5 corresponding to a substrate of about 5.7 m ² (2.2 m x 2.5 m), or Further, it may be GEN10 corresponding to a substrate (2.85 m × 3.05 m) of about 8.7 m ² . Further next generations such as GEN11 and GEN12, and corresponding substrate areas may be similarly mounted.

The drawings show vertically oriented carriers. As illustrated in FIG. 1, the carrier 110 support substrate 120 is oriented in a plane defined by a first direction 192 and a second direction 194, with the first direction 192 being substantially in the carrier transport direction. The second direction 194 is oriented substantially parallel to the direction of gravity. The first direction 192 is oriented substantially perpendicular to the second direction 194. However, the embodiments described herein are not limited to vertically oriented carriers. Other orientations of the carrier, such as horizontal orientation, may be further provided.

In the present disclosure, the expression "substantially parallel" may include the two directions forming a small angle of up to 10 degrees or even an angle of up to 15 degrees with respect to each other. The expression "substantially perpendicular" can include an angle between the two directions of less than 90 degrees, eg, at least 80 degrees, or at least 75 degrees with respect to each other. A similar idea applies to the notions of axes, planes, regions, and orientations that are substantially parallel or perpendicular to each other.

Some embodiments described herein are associated with the concept of "vertical direction". The vertical direction is considered to be a direction parallel to or substantially parallel to the direction along the extension of gravity. The vertical direction may deviate from the exact verticality (defined by gravity), for example, at an angle of up to 15 degrees.

The embodiments described herein may further accompany the concept of "horizontal direction". It should be understood that the horizontal direction is distinguished from the vertical direction. The horizontal direction can be perpendicular to or substantially perpendicular to the exact vertical direction defined by gravity.

The embodiments described herein relate to a distance sensor for measuring the distance to a ferromagnetic element and a magnetic levitation system for magnetically levitation of the ferromagnetic element. First, FIG. 1 showing an embodiment of the magnetic levitation system 100 according to the embodiment described in the present specification is referred to.

The magnetic levitation system 100 shown in FIG. 1 includes a carrier 110. The carrier 110 supports the substrate 120. The carrier 110 includes a ferromagnetic element 150, such as a bar of ferromagnetic material. The magnetic levitation system 100 includes a plurality of levitation units 170 including, for example, an electromagnetic device, a solenoid, a coil, or an active magnet unit such as a superconducting magnet. The individual levitation units of the plurality of levitation units 170 are designated by reference numeral 175. The plurality of magnet units 170 extend in the first direction 192. The carrier 110 is movable along a plurality of levitation units 170. The ferromagnetic element 150 and the plurality of levitation units 170 are configured to apply a magnetic levitation force for levitation of the carrier 110. The magnetic levitation force extends in the second direction 194.

The magnetic levitation system 100 shown in FIG. 1 may include a plurality of distance sensors (not shown) provided in the plurality of levitation units 170. Distance sensors may be provided in each levitation unit 175. Alternatively, the distance sensor may be provided inside each levitation unit 175. The distance sensor may be configured to measure the distance between the plurality of magnet units 170 and the carrier 110 during non-contact levitation of the carrier 110.

The magnetic levitation system 100 shown in FIG. 1 includes a magnetic drive structure 180. The magnetic drive structure 180 includes a plurality of magnet drive units. The individual magnet drive units of the magnetic drive structure 180 are designated by reference numeral 185. The carrier 110 may include a second ferromagnetic element 160 that interacts with the magnetic drive unit 185 of the magnetic drive structure 180. The magnetic drive unit 185 of the magnetic drive structure 180 drives the carriers in the processing system, for example, along a first direction 192. For example, the second ferromagnetic element 160 may include a plurality of permanent magnets arranged in alternating polarities. The magnetic field generated as a result of the second passive magnetic unit 160 can interact with the second ferromagnetic element 160 of the magnetic drive structure 180 to move the carrier 110 in the first direction 192 while floating it. it can.

The magnetic levitation system 100 includes a control unit 130. The control unit 130 may be connected to a plurality of levitation units 170 and / or distance sensors. The control unit 130 may be configured to control the magnetic levitation of the carrier 110. The control unit 130 is configured to control the distance between the carrier 110 and the plurality of magnet units 170 during the levitation of the carrier 110, for example, based on the measured distance value given to the control unit 130 by the distance sensor. Can be done. The magnetic drive structure 180 can drive the carrier 110 under the control of the control unit 130.

From this, reference is made to FIGS. 2a and 2B showing a cross-sectional view of the levitation unit 175. FIG. 2a is a cross-sectional view in the first direction 192 or the carrier transport direction, and FIG. 2b is a third direction 196 or a carrier transport direction perpendicular to the first direction 192 and the second direction 194. It is sectional drawing in the orthogonal direction.

According to the embodiments of the present disclosure that can be combined with other embodiments described herein, the levitation unit 175 comprises at least a magnetic actuator 178. The electromagnetic actuator 178 may include at least a coil 178a and at least a ferromagnetic core 178b and will generate an electric field when a current is applied to the coil 178a. The magnetic field generated by the electromagnetic actuator 178 applies a magnetic levitation force to the ferromagnetic element 150 in the second direction 194 to levitate the carrier 110 to which the ferromagnetic element 150 is attached.

According to embodiments of the present disclosure that can be combined with other embodiments described herein, the at least one electromagnetic actuator, at least one distance sensor, and controller may be included within an airtight enclosure. During the operation of the magnetic levitation system 100 in high vacuum or ultra high vacuum applications, the various components of the levitation unit 175 are shielded from the surrounding vacuum environment. For this purpose, the levitation unit 175 may further include a housing 176. The housing 176 surrounds the components of the levitation unit 175 and shields the components of the levitation unit 175 from the surrounding vacuum environment. The housing 176 can be an airtight enclosure surrounding the interior space 177 so that the interior space 177 is separated from the surrounding vacuum environment. By separating the internal space 177 from the surrounding vacuum environment, contamination of the surrounding vacuum environment can be avoided.

Housing 176 may include non-ferromagnetic material. This allows at least one distance sensor 200 to be placed inside the housing 176 to detect the magnetic field through the housing 176. For example, the housing 176 may include a metal, specifically an aluminum alloy or non-ferromagnetic stainless steel.

The interior space 177 may be maintained at the same pressure as the surrounding vacuum environment, or may be maintained at a pressure different from the surrounding vacuum environment. For example, the interior space 177 may be maintained at a higher pressure than the surrounding vacuum environment. Due to this feature, the components of the levitation unit 175 contained within the housing 176 are cooled via convection, or the mean free path of the interior space 177 is modified between the electrical or electronic components contained within the housing 176. It becomes possible to avoid the electric arc of. Further, the interior space 177 may contain a gas composition that is the same as or different from the surrounding vacuum environment.

According to embodiments of the present disclosure that can be combined with other embodiments described herein, the levitation unit 176 may further include a controller 179. The controller 179 is electrically attached to at least the distance sensor 200 and at least the electromagnetic actuator 178. The controller 179 can acquire at least the distance signal from the distance sensor 200, which corresponds to the distance X between the distance sensor 200 and the ferromagnetic element 150. Based on the acquired distance signal, the controller 179 outputs an actuator signal corresponding to the target actuator force given by the electromagnetic actuator 178.

According to embodiments of the present disclosure that can be combined with other embodiments described herein, the controller 179 is a closed loop control of at least one electromagnetic actuator for controlling the distance to the ferromagnetic element 150. Can be configured for. For example, controller 179 may implement a closed-loop control mechanism for maintaining a target distance. The closed-loop control mechanism may include a PI controller, a PID controller, or any other closed-loop controller in the art. The closed loop control mechanism may take at least one distance signal as an input and generate a control signal for at least one electromagnetic actuator as an output. The closed loop control mechanism may be configured to receive additional input signals. For example, the estimated current signal of at least one electromagnetic actuator may be used as an additional input signal.

As illustrated in FIGS. 2a and 2b, the controller 179 can be a component of the levitation unit 175. In this case, each levitation unit 175 in the plurality of levitation units 170 may each have a separate controller 179. The individual controllers 179 can independently control each levitation unit 175. Optionally, a separate controller 179, located within each levitation unit 175, can be electrically attached to the control unit 130, as illustrated in FIG. Alternatively, the controller 179 can be a component of the control unit 130. Each controller 179 for each levitation unit 175 in the plurality of levitation units 170 is integrated within a single control unit 130.

According to embodiments of the present disclosure that can be combined with other embodiments described herein, the levitation unit 176 further includes at least the distance sensor 200. As illustrated in FIG. 2a, the levitation unit 176 may include two distance sensors 200 located on either side of the electromagnetic actuator 178. The number of distance sensors 200 may be at least one distance sensor for each electromagnetic actuator 178, specifically two distance sensors 200 for each electromagnetic actuator 178.

The distance sensor 200 may include at least one transducer that varies the output voltage in response to a magnetic field. For example, the distance sensor 200 may include a Hall effect sensor or a giant magnetoresistive (GMR) sensor. The distance sensor 200 is configured to detect the magnetic field of the ferromagnetic element 150, whereby the distance X between the distance sensor 200 and the ferromagnetic element 150 can be determined. Therefore, the distance sensor 200 can be used to determine the distance between the levitation unit 175 and the carrier 110 to which the ferromagnetic element 150 is attached in a non-contact manner. Further, since the magnetic field of the ferromagnetic element 150 is detected, even if there is a non-ferromagnetic element between the distance sensor 200 and the ferromagnetic element 150, the operation of the distance sensor 200 is not hindered.

The distance sensor 200 can be arranged in an appropriate position to reliably measure the distance X to the ferromagnetic element 150. The distance sensor 200 may be attached to the levitation unit 175 or may be positioned inside the levitation unit 175. As illustrated in FIGS. 2a and 2b, the distance sensor 200 may be positioned in-line with the electromagnetic actuator 178. In order to achieve reliable and high-performance control of the levitation unit 175, it is preferable to juxtapose the sensor and actuator in the sensor / actuator pair. Therefore, it is preferable that the distance sensor 200 is positioned so as to be close to the electromagnetic actuator 178. Further, by bringing the distance sensor 200 close to the electromagnetic actuator 178, there is a further effect that the levitation unit 175 can be made more compact.

However, since the electromagnetic actuator 178 generates an electromagnetic field to float the carrier 110, it is a problem to position the distance sensor 200 close to the electromagnetic actuator 178. The stray magnetic field generated by the electromagnetic actuator 178 can be detected by the distance sensor 200, which causes undesired cross-coupling with the electromagnetic actuator 178. The cross-coupling caused by this stray magnetic field affects the reliable determination of the distance X between the distance sensor 200 and the ferromagnetic element 150, which in turn affects the reliable determination between the carrier and the magnetic levitation system. To exert.

From this, reference is made to FIGS. 3a and 3b showing a side sectional view of the distance sensor 200 according to the embodiment of the present disclosure. Here, a distance sensor 200 for measuring the distance X to the ferromagnetic element 150 is provided. The distance sensor 200 includes at least a first permanent magnet element 201, at least a first Hall element 203, and at least a second Hall element 204, and the first permanent magnet element 201 has a first magnetic field 205. Generate. In the first and second Hall elements 203 and 204, the direction of the first magnetic field 205 at the position of the first Hall element 203 is substantially the same as the direction of the first magnetic field 205 at the position of the second Hall element 204. Oriented as opposed to.

As an undesired effect in levitation of the carrier 110, a second magnetic field 206 may be generated by the electromagnetic actuator 178. The second magnetic field 206 may include a stray magnetic field. Since the magnitude of the second magnetic field 206 depends on the buoyancy force applied to the carrier 110, the effect of the second magnetic field 206 on the distance sensor 200 causes an undesired cross-cup between the electromagnetic actuator 178 and the distance sensor 200. A ring is created. By providing the distance sensor 200 according to the present disclosure, this undesired cross-coupling can be corrected.

By providing at least the first permanent magnet 201 and the first and second Hall elements 203 and 204 in the distance sensor 200, the first magnetic field 205 is detected and between the ferromagnetic element 150 and the distance sensor 200. It becomes possible to determine the distance X, and at the same time, it becomes possible to correct the second magnetic field 206. The first magnetic field 205 generates a positive voltage component over the first Hall element 203 and a negative voltage component over the second Hall element 204. On the other hand, the second magnetic field 206 generates a positive voltage component over both the first and second Hall elements 203 and 204. By subtracting the voltage generated by the second Hall element 204 from the voltage generated by the first Hall element 203, the voltage component generated over the first and second Hall elements 203 and 204 by the second magnetic field 206 is generated. The voltage components that are offset and generated by the first magnetic field 205 over the first and second Hall elements 203 and 204 remain.

The first and second Hall elements 203 and 204 generate a voltage based on the applied magnetic field. The first and second Hall elements 203 and 204 are positioned such that the first magnetic field 205 induces a voltage within the first and second Hall elements 203 and 204. Since the strength of the first magnetic field 205 is affected by the presence of the ferromagnetic element 150, the first magnetic field is between when the ferromagnetic element 150 is closer to the distance sensor 200 and when it is farther from the distance sensor 200. There is a difference at 205. By positioning the Hall elements 203 and 204 so that the first magnetic field 205 generates a voltage in the Hall elements 203 and 204, the distance between the distance sensor 200 and the ferromagnetic element 150 can be measured. ..

The first magnetic field 205 is generated by at least the first permanent magnet element 201. First referring to the embodiment illustrated in FIG. 3a, the distance sensor 200 includes a first permanent magnet element 201. The first permanent magnet element 201 is positioned so that a magnetic field loop is generated, and the magnetic flux direction on one side of the distance sensor 200 is the first magnetic flux direction away from the ferromagnetic element 150, and the other side of the distance sensor 200. The magnetic flux direction on the side of is the second magnetic flux direction toward the ferromagnetic element 150. The distance sensor 200 further includes a core element 202 positioned to direct the first magnetic field 205. In the first and second Hall elements 203 and 204, the first Hall element 203 is in the magnetic flux region in the first magnetic flux direction, and the second Hall element 204 is in the magnetic flux region in the second magnetic flux direction. It is positioned in the first magnetic field 205.

An alternative arrangement is illustrated in FIG. 3b. In the present embodiment, the first permanent magnet element 201a and the second permanent magnet element 201b are provided. The polarities of the first and second permanent magnet elements 201a and 201b are arranged opposite to each other so that a magnetic field loop is generated, and the magnetic flux direction on one side of the distance sensor 200 is from the ferromagnetic element 150. It becomes the first magnetic flux direction away, and the magnetic flux direction on the other side of the distance sensor 200 becomes the second magnetic flux direction toward the ferromagnetic element 150. The distance sensor 200 further includes a core element 202 positioned to direct the first magnetic field 205. In the first and second Hall elements 203 and 204, the first Hall element 203 is in the magnetic flux region in the first magnetic flux direction, and the second Hall element 204 is in the magnetic flux region in the second magnetic flux direction. It is positioned in the first magnetic field 205.

At least the first permanent magnet element 201 may be included in a plurality of permanent magnet elements. For example, the distance sensor 200 may include at least two first permanent magnet elements, or may include at least two first permanent magnet elements and at least two second magnet elements. A plurality of permanent magnet elements may be oriented so as to form a Halbach array. As a result, the magnetic field generated by the plurality of permanent magnet elements is strong on the side facing the ferromagnetic element 150 and weak on the opposite side of the ferromagnetic element 150. The Halbach array has the advantage of not generating a magnetic field behind it, and other components located within the levitation unit, which are susceptible to magnetic interference, are affected by the first magnetic field compared to conventional magnetic elements. The degree of receiving is small.

According to an embodiment of the present disclosure, the first and second Hall elements 203, 204 relative to each other so that the first magnetic field 205 produces a voltage within the first and second Hall elements 203, 204. Oriented in the opposite direction. This is because the first Hall element 203 positioned in the magnetic flux region in the first magnetic flux direction is oriented in the first magnetic flux direction, and the second Hall element 204 positioned in the magnetic flux region in the second magnetic flux direction It means that the first and second Hall elements 203 and 204 are oriented so as to be oriented in the second magnetic flux direction. In the side sectional views shown in FIGS. 3a and 3b, the first Hall element 203 is oriented upward, and the second Hall element 204 is oriented downward.

When the first and second Hall elements 203 and 204 are oriented in opposite directions to each other, the first magnetic field 205 generates a positive voltage in both the first Hall element 203 and the second Hall element 204. , The magnitude of each voltage is almost equal to each other. However, the second magnetic field 206 generates a positive voltage in either the first hose element 203 or the second Hall element 204 so that the magnitudes of the respective voltages are substantially equal to each other. A negative voltage is generated in either the hose element 203 or the second Hall element 204 of the above. The voltage generated by each of the first and second Hall elements 203 and 204 is set so that the voltage generated by the first magnetic field 205 is retained and the voltage generated by the second magnetic field 206 is offset. It can be added, which will correct the measured voltage of any effect of the second magnetic field 206 on the output voltage of the distance sensor 200.

As an alternative embodiment, the first and second Hall elements 203, 204 have the first and second Hall elements 203, 204 such that the first magnetic field 205 produces a positive voltage on one Hall element and a negative voltage on the other Hall element. , May be oriented in the same direction with respect to each other. In the side sectional views shown in FIGS. 3a and 3b, in this case, the first and second Hall elements 203 and 204 are both oriented upward or both downward.

When the first and second Hall elements 203 and 204 are oriented in the same direction, the first magnetic field 205 uses the first Hall element 203 so that the magnitudes of the respective voltages are substantially equal to each other. A positive voltage is generated in the second Hall element 204, and a negative voltage is generated in the second Hall element 204. However, the second magnetic field 206 generates a positive voltage in both the first and second Hall elements 203 and 204 so that the magnitudes of the respective voltages are substantially equal to each other. The voltage generated by each of the first and second Hall elements 203 and 204 is set so that the voltage generated by the first magnetic field 205 is retained and the voltage generated by the second magnetic field 206 is offset. It can be deducted, which will correct the measured voltage of any effect of the second magnetic field 206 on the output voltage of the distance sensor 200.

By setting the distance sensor 200 according to the present disclosure, the stray magnetic field can be corrected. The stray magnetic field can be generated, for example, by an electromagnetic actuator, a magnetic element on a substrate carrier, or a cathode target. The correction of the stray magnetic field allows the distance sensor 200 to be positioned closer to the electromagnetic actuator, and the juxtaposition of the sensor and actuator can achieve improved performance of the magnetic levitation system. Further, by correcting the stray magnetic field, the distance sensor 200 can perform more reliable and more accurate distance measurement so that the distance between the carrier and the magnetic levitation system can be maintained more reliably and more accurately. it can.

According to embodiments of the present disclosure that can be combined with other embodiments described herein, the controller 179 shown in FIGS. 2a and 2b is generated by at least one electromagnetic actuator and at least one distance sensor. It may be configured to compensate for the stray magnetic field acting on the. The controller 179 may be electrically attached to at least one distance sensor 200 so that the controller 179 can receive the first and second signals from the first and second Hall elements, respectively. The controller 179 may be configured to subtract a first signal and a second signal from each other so as to correct the signal components generated by the stray magnetic field generated by at least one electromagnetic actuator.

According to a third embodiment of the present disclosure, a distance sensor for measuring the distance to a ferromagnetic element is provided. In this method, a distance sensor including a first Hall element and a second Hall element is provided, and a first signal of the first Hall element and a second signal of the second Hall element are detected. This includes subtracting the second signal from the first signal.

From this, reference is made to FIG. 5 showing a flow chart of the method 500 for measuring the distance to the ferromagnetic element according to the embodiment of the present disclosure. Method 500 begins at start 510.

The block 511 is provided with a distance sensor including a first Hall element and a second Hall element. The distance sensor can be the distance sensor described herein, and the distance sensor is capable of measuring the distance to a ferromagnetic element. The distance sensor may be provided close to, for example, the electromagnetic actuator. An unwanted stray magnetic field generated by the electromagnetic actuator can affect the distance sensor, resulting in cross-coupling between the electromagnetic actuator and the distance sensor.

The block 512 detects the first signal of the first Hall element, and the block 513 detects the second signal of the second Hall element. The first and second signals of the first and second Hall elements may include components of the distance measurement signal and the stray magnetic field signal, respectively. The distance measurement signal components of the first and second signals may have opposite polarities even if they are approximately equal in magnitude, but the stray magnetic field signal components of the first and second signals are of magnitude. They can be approximately equal and have the same polarity.

In block 514, the first signal of the first Hall element and the second signal of the second Hall element are subtracted from each other. Since the stray magnetic field signal components of the first and second signals are approximately equal in magnitude and have the same polarity, subtracting the first and second signals from each other is a deduction of the first and second signals. The stray magnetic field signal components of each of the two signals are offset. Therefore, the stray magnetic field signal component can be corrected to produce a distance signal that remains unaffected by the undesired stray magnetic field. Finally, method 500 ends at end 520.

According to a further embodiment that can be combined with other embodiments described herein, the distance sensor provided in block 511 has at least a first permanent magnet element for generating a first magnetic field. Further included, the direction of the first magnetic field at the position of the first Hall element is substantially opposite to the direction of the first magnetic field at the position of the second Hall element. Alternatively, the distance sensor provided in block 511 may further include at least a first permanent magnet element and at least a second permanent magnet element for generating a first magnetic field, the first Hall element. The direction of the first magnetic field at the position of is substantially opposite to the direction of the first magnetic field at the position of the second Hall element. Therefore, the first magnetic field causes the first Hall element to generate the first distance measurement signal component and the second Hall element to generate the second distance measurement signal component, in which case the first distance measurement. The polarity of the signal component is opposite to the polarity of the second distance measurement signal component. For example, the first magnetic field may cause the first Hall element to generate a positive voltage component and the second Hall element to generate a negative voltage component. The magnitudes of the first distance measurement signal component and the second distance measurement signal component generated by the first and second Hall elements, respectively, may be substantially equal, whereby in the block 514, the first Hall element When the first signal of the first signal and the second signal of the second Hall element are subtracted from each other, the first distance measurement signal component and the second distance measurement signal component do not cancel each other out. The first and second stray magnetic field components are corrected. Therefore, a distance signal that remains unaffected by the stray magnetic field can be generated.

Method 500 can be performed using a controller. For example, with reference to FIGS. 2a and 2b again, method 500 can be performed by controller 179, which can be a component of levitation unit 175. The controller 179 can be electrically attached to at least the distance sensor 200 to receive the first and second signals as inputs.

As described above, one aspect of the magnetic levitation system is to place the electromagnetic actuator and the distance sensor in close proximity to each other in the levitation system. This achieves a minimized size of the magnetic levitation system and improved control behavior due to juxtaposition of actuators and sensors. One of the undesired effects caused by the closer the electromagnetic actuator and the distance sensor is is that the stray magnetic field generated by the electromagnetic actuator provides a cross-coupling effect with the distance sensor. The embodiments described herein solve this problem by, for example, using first and second Hall elements to subtract their signals from each other and correct the stray magnetic field.

However, when the distance sensor is positioned closer to the electromagnetic actuator, it has the further undesired effect that the stray magnetic field cannot affect the first and second Hall elements in the distance sensor equally. .. For example, the stray magnetic field may be more curved in the region where the distance sensor is located, or the stray magnetic field may be non-uniform in magnitude. These effects are particularly problematic, for example, in distance sensors located between electromagnetic actuators. In this case, in order to completely correct the second magnetic field signal by subtraction, the first magnetic field signal component and the second magnetic field signal component may not be sufficiently equal in magnitude. Therefore, additional correction of these effects may be advantageous.

From this, it is referred to FIG. 6 which shows the flow chart of the method 501 for measuring the distance to a ferromagnetic element. According to embodiments of the present disclosure that can be combined with other embodiments described herein, method 501 uses coil currents to estimate the magnetic flux generated by at least one electromagnetic actuator. Further includes the additional step of detecting the coil current of at least one electromagnetic actuator and correcting the erroneous component of the distance signal measured by the distance sensor. Method 501 begins at start 510.

Method 501, including blocks 511, 512, 513, and 514 according to method 500 described above, further comprises detecting coil currents in at least one electromagnetic actuator in block 515. The coil current in the electromagnetic actuator is proportional to the magnetic flux generated by the electromagnetic actuator. The coil current may be detected from a current signal transmitted to the electromagnetic actuator, or may be detected by using a current sensor configured to measure the current in the coil of the electromagnetic actuator.

Further, in block 516, the magnetic flux generated by at least one electromagnetic actuator is estimated. The estimation of the generated magnetic flux is based on the coil current of at least one electromagnetic actuator detected in block 515. Estimating the magnetic flux involves generating a magnetic flux correction signal. The magnetic flux correction signal can be used to correct an erroneous component of the distance signal generated by the distance sensor.

Finally, block 517 corrects for erroneous components of the distance signal measured by the distance sensor. The correction is performed by subtracting the magnetic flux correction signal generated in block 516 from the distance signal detected by the distance sensor, whereby the cross between the electromagnetic actuator and the distance sensor that has not already been corrected in block 514. Further effects of coupling are corrected.

By performing method 501 as described above, it is possible to further compensate for non-uniform or multi-curved stray magnetic fields, or stray magnetic fields such as stray magnetic fields from adjacent electromagnetic actuators, thereby making the distance sensor electromagnetic. It can be positioned closer to the actuator, further improving the performance of the magnetic levitation system.

According to the embodiments of the present disclosure that can be combined with other embodiments described herein, estimating the magnetic flux at block 516 is based on the magnitude and / or frequency of the coil current. Includes calculating the model. The coil current can, for example, induce eddy currents within the housing 176 or generate a frequency-dependent magnetic flux of a given magnitude. Further, the ferromagnetic element 150 can be a non-stacked element capable of introducing frequency dependence. The model may include a pre-determined or pre-computed model of the magnetic flux generated by the electromagnetic actuator in relation to the magnitude and / or frequency of a given coil current. For example, the model may include a look-up table of precomputed values. Alternatively, the model can be calculated in real time based on a mathematical approximation of the magnetic flux generated by the electromagnetic actuator in relation to the magnitude and / or frequency of a given coil current.

The model of the magnetic flux can be determined by measuring the magnetic flux behavior of the electromagnetic actuator according to the applied coil current and determining its effect on the distance signal. The ferromagnetic element is fixed at a well-known distance from the distance sensor, a coil current is applied to the electromagnetic actuator, and a distance signal is generated from the distance sensor. By changing the coil current applied to the electromagnetic actuator, a change in magnetic flux is caused, which changes the distance signal from the distance sensor under the influence of the magnetic flux. By measuring the change in the distance signal based on the coil current, it is possible to calculate a model for estimating the influence of the magnetic flux of the electromagnetic actuator on the distance signal based on the coil current.

The model may take into account additional parameters for estimating the magnetic flux generated by at least one electromagnetic actuator. For example, the model may include parameters related to the coil current of at least one adjacent electromagnetic actuator. When the electromagnetic actuators are located close to adjacent electromagnetic actuators, the stray magnetic flux generated by the adjacent electromagnetic actuators may also cross-coup with the adjacent distance sensor. Therefore, it is possible to further correct the erroneous component of the distance signal generated by the distance sensor caused by the stray magnetic flux acting on the distance sensor.

According to the embodiments of the present disclosure that can be combined with other embodiments described herein, the estimation of magnetic flux is performed on a digital signal processor. A digital signal processor usually includes an analog-to-digital converter (ADC), a digital signal processing unit, and a digital-to-analog converter (DAC), and can process an analog signal in real time. The digital signal processor may be a separate component provided within the levitation unit, or may be incorporated within a controller for the levitation unit. Performing magnetic flux estimation on a digital signal processor enables real-time estimation of magnetic flux, which allows for faster acquisition of distance signals and in maintaining the target distance between the carrier and the levitation system. , Allows for better performance of levitation system.

Although the above description is intended for the embodiments of the present disclosure, other embodiments and further embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure. The scope is determined by the following claims.

Claims (16)

A distance sensor (200) for measuring the distance to the ferromagnetic element (150).
At least the first permanent magnet element (201, 201a),
At least the first Hall element (203), and at least the second Hall element (204)
With
The first permanent magnet element (201, 201a) generates a first magnetic field (205), and the direction of the first magnetic field (205) at the position of the first Hall element (203) is the said. A distance sensor (200) that is substantially opposite to the direction of the first magnetic field (205) at the position of the second Hall element (204). A second permanent magnet element (201b) arranged parallel to the first permanent magnet element (201a) and having the opposite polarity is further provided, and the first permanent magnet element (201a) and The distance sensor (200) according to claim 1, wherein the second permanent magnet element (201b) generates the first magnetic field (205). The first Hall element (203) and the first Hall element (203) and the first Hall element (203) so that the first magnetic field (205) generates a positive voltage in the first Hall element (203) and the second Hall element (204). The distance sensor (200) according to claim 1 or 2, wherein the Hall elements (204) of 2 are oriented in opposite directions with respect to each other. A magnetic levitation system (100) for magnetically levitation of a ferromagnetic element (150).
At least one electromagnetic actuator (178) and at least one distance sensor (200) according to any one of claims 1 to 3.
With
The magnetic levitation system (100), wherein the at least one distance sensor (200) is configured to measure the distance (X) to the ferromagnetic element (150). It further comprises a controller (130, 179) configured for closed loop control of the at least one electromagnetic actuator (178) to control the distance (X) to the ferromagnetic element (150). The magnetic levitation system (100) according to claim 4. 5. The controller (130, 179) is configured to compensate for a magnetic field generated by the at least one electromagnetic actuator (178) and acting on the at least one distance sensor (200). The magnetic levitation system described. The magnetic levitation system according to any one of claims 4 to 6, wherein the at least one electromagnetic actuator (178) is configured to transport the ferromagnetic element (150) in the transport direction (192). (100). The magnetic levitation system (100) according to any one of claims 4 to 7, wherein the ferromagnetic element is a substrate carrier (110). Any one of claims 5 to 8, wherein the at least one electromagnetic actuator (178), the at least one distance sensor (200), and the controller (179) are contained inside an airtight housing (176). The magnetic levitation system (100) according to the section. The magnetic levitation system (100) according to any one of claims 4 to 9, wherein the magnetic levitation system (100) is configured to operate in a vacuum. A method for measuring the distance (X) to a ferromagnetic element (150).
Providing a distance sensor (200) including a first Hall element (203) and a second Hall element (204), and
To detect the first signal of the first Hall element (203) and the second signal of the second Hall element (204),
A method comprising subtracting the second signal from the first signal. The distance sensor (200) further comprises at least a first permanent magnet element (201, 201a) for generating a first magnetic field (205), said the first at the position of the first Hall element (203). The method according to claim 11, wherein the direction of the magnetic field (205) of 1 is substantially opposite to the direction of the first magnetic field (205) at the position of the second Hall element (204). To detect the coil current of at least one electromagnetic actuator (178)
Using the coil current to estimate the magnetic flux generated by the at least one electromagnetic actuator (178).
The method of claim 11 or 12, further comprising correcting an erroneous component of the distance signal measured by the distance sensor (200). 13. The method of claim 13, wherein estimating the magnetic flux comprises calculating a model of the magnetic flux based on the magnitude and / or frequency of the coil current. 13. The method of claim 13 or 14, wherein estimating the drifting magnetic flux is performed on a digital signal processor. The use of the distance sensor (200) according to any one of claims 1 to 3 in the magnetic levitation device (100), wherein the distance sensor (200) determines the distance (X) to the buoyant body. Use of a distance sensor (200) that is configured to measure.

Images