KR102324106B1 - A distance sensor for measuring a distance to a ferromagnetic element, a magnetic levitation system, and a method for measuring a distance to a ferromagnetic element - Google Patents

Abstract

The present disclosure relates to a distance sensor for measuring a distance to a ferromagnetic element, a magnetic levitation system for magnetically levitating a ferromagnetic element, and a method for compensating for stray magnetic fields in a distance sensor. According to a first aspect, a distance sensor for measuring a distance to a ferromagnetic element is provided. According to a second aspect, there is provided a magnetic levitation system for magnetically levitating a ferromagnetic element, the magnetic levitation system comprising at least one electromagnetic actuator and at least one distance sensor according to the first aspect, the at least one distance sensor is configured to measure the distance to the ferromagnetic element. According to a third aspect, there is provided a method for measuring a distance to a ferromagnetic element, the method comprising: providing a distance sensor comprising a first Hall element and a second Hall element; a first signal of the first Hall element; and detecting a second signal of the second Hall element, and subtracting the second signal from the first signal. According to a fourth embodiment, there is provided use of a distance sensor according to the first aspect, wherein the distance sensor is used in a magnetic levitation device, the distance sensor being configured to measure a distance to an injured body.

Description

A distance sensor for measuring a distance to a ferromagnetic element, a magnetic levitation system, and a method for measuring a distance to a ferromagnetic element

Embodiments of the present disclosure relate to a distance sensor for measuring a distance to a ferromagnetic element. More particularly, embodiments of the present disclosure relate to, inter alia, a magnetic levitation system for magnetically levitating a ferromagnetic element, and a method for compensating for stray magnetic fields in a distance sensor.

[0002] Systems are known for performing various processes, such as coating of a substrate in a processing chamber. Several methods are known for depositing material on a substrate. For example, the substrates use an evaporation process, a physical vapor deposition (PVD) process, such as a sputtering process, a spraying process, etc., or a chemical vapor deposition (CVD) process. can be coated. The process may be performed in a processing chamber of the deposition apparatus in which the substrate to be coated is located. A deposition material is provided to the processing chamber. A plurality of materials may be used for deposition on the substrate, such as small molecules, metals, oxides, nitrides and carbides. Also, other processes such as etching, structuring, annealing, etc. may be performed in the processing chambers.

For example, coating processes may be considered for large area substrates, such as in display manufacturing technology. Coated substrates can be used in many applications and in many fields of technology. For example, an application may be organic light emitting diode (OLED) panels. Additional applications include insulating panels, microelectronics, such as semiconductor devices, substrates with thin film transistors (TFTs), color filters, and the like. OLEDs are solid-state devices made up of thin films of (organic) molecules that generate light upon application of electricity. As an example, OLED displays may provide bright displays on electronic devices, eg, may use reduced power compared to liquid crystal displays (LCDs). In a processing chamber, organic molecules are created (eg, evaporated, sputtered, or sprayed, etc.) and deposited as layers on substrates. Particles may pass through a boundary or mask having a particular pattern, eg, to deposit material at particular positions on the substrate, such as to form an OLED pattern on the substrate.

The processing system may include a magnetic levitation system for guiding the carrier in the processing chamber, such as during a coating process. The magnetic levitation system may be adapted to transport a carrier within a processing chamber and/or to provide a carrier to a processing position. The magnetic levitation system may include one or more levitation units having electromagnetic actuators, sensors, signal processors and power amplifiers to form a closed control loop, such that the levitated carrier is removed from the magnetic bearing. maintained at a predetermined distance.

[0005] In applications where substrates are processed in high vacuum, the metallic shielding of actuators, sensors and other components precludes the use of some types of distance sensors. In such applications, distance sensors based on magnetic effects, such as hall effect sensors, are used because they can measure distances through non-ferrous metallic shielding. am.

[0006] One aspect of a maglev system is to incorporate electromagnetic actuators and distance sensors within a levitation unit to achieve a minimized size of the maglev system and improved control behavior through colocation of the actuator and sensor. positioning close to each other.

[0007] In view of the above, it is an aspect of the present disclosure to provide a distance sensor and method for operation of a distance sensor that overcomes at least some of the problems in the art.

According to a first embodiment, there is provided a distance sensor for measuring a distance to a ferromagnetic element. 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 at a position of the first Hall element The direction of the magnetic field is substantially opposite the direction of the first magnetic field at the position of the second Hall element.

[0009] According to a second embodiment, there is provided a magnetic levitation system for magnetically levitating a ferromagnetic element. The magnetic levitation system comprises at least one electromagnetic actuator and at least one distance sensor according to the first embodiment, wherein the at least one distance sensor is configured to measure a distance to the ferromagnetic element.

According to a third embodiment, a method for measuring a distance to a ferromagnetic element is provided. The method includes providing a distance sensor comprising a first Hall element and a second Hall element, detecting a first signal of the first Hall element and a second signal of a second Hall element, and a second signal from the first signal. 2 comprising subtracting the signal.

[0011] According to a fourth embodiment, there is provided the use of a distance sensor according to the first embodiment. A distance sensor is used in the magnetic levitation device, wherein the distance sensor is configured to measure a distance to the injured body.

Embodiments also relate to apparatus for performing the disclosed methods, including apparatus parts for performing each described method step. These method steps may be performed by hardware components, by a computer programmed by suitable software, by any combination of the two, or in any other manner. Furthermore, embodiments according to the present disclosure also relate to methods of operating the described apparatus. The method includes method steps for performing every respective function of the device.

[0013] In such a way that the above-listed features of the present disclosure may be understood in detail, a more specific description of the present disclosure briefly summarized above may be made with reference to embodiments. The accompanying drawings relate to embodiments of the present disclosure and are described below:
1 shows a schematic front view of a magnetic levitation system according to embodiments described herein;
2A illustrates a cross-sectional side view of a magnetic levitation system in accordance with embodiments described herein;
2B shows a front cross-sectional view of a magnetic levitation system in accordance with embodiments described herein;
3A, 3B show cross-sectional side views of a distance sensor according to embodiments described herein;
4 shows a flow diagram of a method for measuring a distance to a ferromagnetic element, in accordance with embodiments described herein; and
5 shows a flow diagram of a method for further compensation of an erroneous component of a distance signal according to embodiments described herein;

Reference will now be made in detail to various embodiments of the present disclosure, one or more examples of which are illustrated in the drawings. Within the following description of the drawings, like reference numbers refer to like components. In general, only differences to individual embodiments are described. Each example is provided as a description of the disclosure and is not intended as a limitation of the disclosure. Also, features illustrated or described as part of one embodiment may be used on or in conjunction with other embodiments to yield still a further embodiment. The description is intended to cover such modifications and variations.

Embodiments described herein involve magnetic levitation and/or transport of a carrier, such as a substrate carrier. Thus, the magnetic levitation of the carrier can be contactless. The term “contactless” as used throughout this disclosure may be understood to mean that the weight of the carrier is held by magnetic force rather than by mechanical contact or mechanical forces. Specifically, the carrier can be held in a floating or floating state using magnetic forces instead of mechanical forces. In some implementations, there may be no mechanical contact between the carrier and the rest of the device during levitation and eg, movement of the carrier within the system.

[0016] Compared to mechanical devices for guiding a carrier in a processing system, the advantage is that the non-contact levitation is not affected from friction affecting the precision and/or linearity of movement of the carrier. The contactless transport of the carrier enables frictionless movement of the carrier, for example the position of the carrier relative to the mask in the deposition process can be controlled and maintained with high precision. In addition, the levitation enables rapid acceleration or deceleration of the carrier and/or precise adjustment of the carrier speed.

[0017] For example, non-contact flotation or transport of a carrier during the deposition process is beneficial in that no particles are created due to mechanical contact between the carrier and sections of the apparatus, such as mechanical rails, during transport of the carrier. Thus, the contactless magnetic levitation system provides improved purity and uniformity of the layers deposited on the substrate because particle generation is minimized, particularly when using contactless magnetic levitation.

[0018] The magnetic levitation system may be configured to operate within a vacuum environment. 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 turbopumps and/or cryo-pumps, connected to the vacuum chamber for creation of a vacuum within the vacuum chamber. The magnetic levitation system may be configured to transfer a substrate into, out of, or through a vacuum chamber.

[0019] A magnetic levitation system may be used to transport a carrier. The carrier may be adapted to carry a substrate, a plurality of substrates and/or a mask. 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 a mask carrier adapted to carry an edge exclusion mask, for example to prevent the edges of the substrate from being coated in a deposition process.

[0020] A carrier according to embodiments described herein need not be limited to a substrate carrier or a mask carrier. The methods described herein also apply to other types of carriers, ie carriers adapted to carry objects or devices other than, for example, substrates or masks.

As used herein, the term “substrate” refers to both inflexible substrates, eg, glass plate, slices of transparent crystal, such as a glass substrate, wafer, sapphire, etc., or a glass plate, and flexible substrates, such as a web or foil. includes According to embodiments that may be combined with other embodiments described herein, embodiments described herein may be utilized for display PVD, ie, sputter deposition on large area substrates for the display market.

According to embodiments, the large area substrate or individual carrier may have a size of at least 0.67 m 2 . The size may be from about 0.67 m 2 (0.73×0.92 m—Gen 4.5) to about 8 m 2 , more specifically from about 2 m 2 to about 9 m 2 or even up to 12 m 2 . For example, a large area substrate or carrier may include GEN 4.5 corresponding to approximately 0.67 m2 substrates (0.73 x 0.92 m), GEN 5 corresponding to approximately 1.4 m2 substrates (1.1 m x 1.3 m), and approximately 4.29 m2 substrates ( GEN 7.5 corresponding to 1.95 m x 2.2 m), GEN 8.5 corresponding to approximately 5.7 m2 substrates (2.2 m x 2.5 m), or even GEN 10 days corresponding to approximately 8.7 m2 substrates (2.85 m x 3.05 m) can Much larger generations such as GEN 11 and GEN 12 and corresponding substrate areas can be implemented similarly.

The drawings show a vertically oriented carrier. As exemplarily shown in FIG. 1 , the carrier 110 supporting the substrate 120 is oriented in a plane defined by a first direction 192 and a second direction 194 , and the first direction 192 . ) is oriented substantially in the direction of carrier transport, and 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, embodiments described herein are not limited to vertically oriented carriers. Other orientations of the carrier, such as horizontal orientation, may also be provided.

[0024] In this disclosure, the term "substantially parallel" directions may include directions that form a small angle of up to 10°, or even up to 15°, from each other. The term “substantially perpendicular” directions may include directions that form an angle of less than 90° with each other, such as at least 80° or at least 75°. Similar considerations apply to concepts of substantially parallel or perpendicular axes, planes, regions, orientations, and the like.

Some embodiments described herein involve the concept of “vertical direction”. The vertical direction is considered to be a direction parallel or substantially parallel to the direction in which gravity extends. The vertical direction may deviate from the correct vertical, for example by an angle of up to 15° (exact vertical is defined by gravity).

[0026] Embodiments described herein may further involve the concept of “horizontal direction”. A horizontal direction should be understood to be distinct from a vertical direction. The horizontal direction may be perpendicular or substantially perpendicular to the exact vertical direction defined by gravity.

Embodiments described herein relate to a magnetic levitation system for magnetically levitating a ferromagnetic element as well as a distance sensor for measuring a distance to a ferromagnetic element. First, reference is made to FIG. 1 , which shows an example of a magnetic levitation system 100 in accordance with embodiments described herein.

The magnetic levitation system 100 shown in FIG. 1 includes a carrier 110 . The carrier 110 supports the substrate 120 . The carrier 110 comprises a ferromagnetic element 150 , for example a bar of ferromagnetic material. The magnetic levitation system 100 includes a plurality of levitation units 170 including, for example, active magnetic units, such as electromagnetic devices, solenoids, coils or superconducting magnets. Individual injury units of the plurality of injury units 170 are indicated by reference numeral 175 . A plurality of floating units 170 extend in a first direction (192). The carrier 110 is movable along the plurality of floating units 170 . The ferromagnetic element 150 and the plurality of levitating units 170 are configured to provide a magnetic levitation force for levitating the carrier 110 . The magnetic levitation force extends in a second direction 194 .

The magnetic levitation system 100 shown in FIG. 1 may include a plurality of distance sensors (not shown) provided to a plurality of levitation units 170 . A distance sensor may be provided for each levitation unit 175 . Alternatively, a distance sensor may be provided within each levitation unit 175 . The distance sensors may be configured to measure distances between the plurality of flotation 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 magnetic drive units. Individual magnetic drive units of magnetic drive structure 180 are indicated by reference numeral 185 . The carrier 110 may include a second ferromagnetic element 160 for interacting with the magnetic drive units 185 of the magnetic drive structure 180 . The magnetic drive units 185 of the magnetic drive structure 180 drive the carrier within the processing system, for example along the first direction 192 . For example, the second ferromagnetic element 160 may include a plurality of permanent magnets arranged in alternating polarity. The resulting magnetic fields of the second ferromagnetic element 160 mutually interact with the plurality of magnetic drive units 185 of the magnetic drive structure 180 to move the carrier 110 in the first direction 192 in the levitated state. can work

The magnetic levitation system 100 includes a control unit 130 . The control unit 130 may be connected to a plurality of injury 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 controls the carrier 110 and the plurality of magnetic units 170 during levitation of the carrier 110 , for example, based on the measured distances supplied to the control unit 130 by means of distance sensors. It may be configured to control the distance between them. The magnetic drive structure 180 may drive the carrier 110 under the control of the control unit 130 .

Reference is now made to FIGS. 2A and 2B , which show cross-sectional views of the levitating unit 175 . FIG. 2A is a cross-sectional view in a first direction 192 or carrier transport direction, and FIG. 2B shows a third direction 196 perpendicular to the first direction 192 and the second direction 194, or transverse to the carrier transport direction. It is a cross-sectional view in the crossing direction.

According to embodiments of the present disclosure, which may be combined with other embodiments described herein, the levitation unit 175 includes at least an electromagnetic actuator 178 . The electromagnetic actuator 178 may include at least a coil 178a and at least a ferromagnetic core 178b , generating a magnetic field upon application of a current to the coil 178a. The magnetic field generated by the electromagnetic actuator 178 applies a magnetic levitation force to the ferromagnetic element 150 in a second direction 194 , causing the carrier 110 to which the ferromagnetic element 150 is attached to float.

[0034] According to embodiments of the present disclosure, which may be combined with other embodiments described herein, at least one electromagnetic actuator, at least one distance sensor and controller may be contained within an airtight enclosure have. Due to the operation of the magnetic levitation system 100 in high vacuum or ultrahigh vacuum applications, the various components of the levitation unit 175 are shielded from the surrounding vacuum environment. For this purpose, the levitating unit 175 may further include a housing 176 , which encloses the components of the levitating unit 175 so that the components of the levitating unit 175 are placed in an ambient vacuum environment. shielded from The housing 176 may be a hermetic enclosure that encloses the interior volume 177 such that the interior volume 177 is isolated from the surrounding vacuum environment. Isolating the interior volume 177 from the surrounding vacuum environment avoids contamination of the surrounding vacuum environment.

The housing 176 may include a non-ferromagnetic material to enable at least one distance sensor 200 located within the housing 176 to detect a magnetic field through the housing 176 . For example, the housing 176 may comprise a metal, particularly an aluminum alloy or a non-ferromagnetic stainless steel.

The interior volume 177 may be maintained at the same pressure as the surrounding vacuum environment, or at a different pressure than the surrounding vacuum environment. For example, the interior volume 177 may be maintained at a higher pressure than the surrounding vacuum environment. This feature is such that the components of the levitation unit 175 contained within the housing 176 are cooled through convection, or the interior volume 177, such that electrical arcing between the electrical or electronic components contained within the housing 176 is avoided. ) makes it possible to modify the mean free path of Further, the interior volume 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, which may be combined with other embodiments described herein, the levitation unit 175 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 may obtain a distance signal corresponding to the distance X between the distance sensor 200 and the ferromagnetic element 150 from at least the distance sensor 200 . Based on the obtained distance signal, the controller 179 outputs an actuator signal corresponding to the target actuator force to be applied by the electromagnetic actuator 178 .

According to an embodiment of the present disclosure, which may be combined with other embodiments described herein, the controller 179 is a lung of the at least one electromagnetic actuator to control the distance to the ferromagnetic element 150 . It can be configured for closed-loop control. For example, the controller 179 may implement a closed loop control mechanism to maintain the 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 may generate as an output a control signal for the at least one electromagnetic actuator. The closed loop control mechanism may be configured to receive additional input signals. For example, the estimated current signal of the at least one electromagnetic actuator can be used as a further input signal.

As illustratively shown in FIGS. 2A and 2B , the controller 179 may be a component of the levitation unit 175 . In this case, each injury unit 175 of the plurality of injury units 170 may each have a separate controller 179 that can independently control each injury unit 175 . Optionally, each separate controller 179 disposed on each levitation unit 175 may be electrically attached to the control unit 130 as illustratively shown in FIG. 1 . Alternatively, the controller 179 may be a component of the control unit 130 , wherein each controller 179 for each injured unit 175 of the plurality of injured units 170 is a single control unit 130 . ) is incorporated into

According to embodiments of the present disclosure, which may be combined with other embodiments described herein, the levitation unit 175 further comprises at least a distance sensor 200 . As illustratively shown in FIG. 2A , the levitation unit 175 may include two distance sensors 200 arranged 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 , in particular two distance sensors 200 for each electromagnetic actuator 178 .

The distance sensor 200 may include at least one transducer, the at least one transducer changing its 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 a magnetic field of the ferromagnetic element 150 such that a distance X between the distance sensor 200 and the ferromagnetic element 150 can be determined. Accordingly, the distance sensor 200 may be used to non-contactly determine the distance between the levitation unit 175 and the carrier 110 to which the ferromagnetic element 150 is attached. Also, since the magnetic field of the ferromagnetic element 150 is detected, the presence of non-ferromagnetic elements between the distance sensor 200 and the ferromagnetic element 150 does not interfere with the operation of the distance sensor 200 .

The distance sensor 200 may be located in an appropriate position to reliably measure the distance X to the ferromagnetic element 150 . The distance sensor 200 may be mounted on the injury unit 175 , or may be positioned within the injury unit 175 . As illustratively shown in FIGS. 2A and 2B , the distance sensor 200 may be positioned inline with the electromagnetic actuator 178 . To achieve reliable and high-performance control of the levitation unit 175 , co-location of the sensor and actuator in the sensor/actuator pair is desirable. Accordingly, it is desirable for the distance sensor 200 to be positioned in close proximity to the electromagnetic actuator 178 . Also, positioning the distance sensor 200 in close proximity to the electromagnetic actuator 178 has the added effect of allowing the levitation unit 175 to be more compact.

However, positioning the distance sensor 200 in close proximity to the electromagnetic actuator 178 is problematic because the electromagnetic actuator 178 generates an electromagnetic field to levitate the carrier 110 . The stray magnetic fields generated by the electromagnetic actuator 178 may be detected by the distance sensor 200 , creating an undesirable cross-coupling with the electromagnetic actuator 178 . This cross-coupling due to stray magnetic fields influences a reliable determination of the distance X between the distance sensor 200 and the ferromagnetic element 150 and, therefore, a reliable determination of the distance between the carrier and the magnetic levitation system. influence the decisions that are

Reference is now made to FIGS. 3A and 3B , which show cross-sectional side views of a distance sensor 200 in accordance with embodiments 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 , wherein the first permanent magnet element 201 includes a first magnetic field ( 205) is created. the first and second magnetic fields 205 at the position of the first Hall element 203 are substantially opposite the direction of the first magnetic field 205 at the position of the second Hall element 204 . Hall elements 203 , 204 are oriented.

The second magnetic field 206 may be generated by the electromagnetic actuator 178 as an undesirable effect of levitating the carrier 110 . The second magnetic field 206 may include a floating magnetic field. Because the magnitude of the second magnetic field 206 depends on the levitation force applied to the carrier 110 , the effect of the second magnetic field 206 on the distance sensor 200 is the electromagnetic actuator 178 and the distance sensor 200 . create undesirable cross-links between them. By providing a distance sensor 200 according to the present disclosure, this undesirable cross-coupling can be compensated for.

[0046] Providing a distance sensor 200 having at least a first permanent magnet 201 and first and second Hall elements 203, 204 comprises detecting the first magnetic field 205 to thereby detect the ferromagnetic element 150 ) and the distance sensor 200 to be determined, while also enabling the second magnetic field 206 to be compensated. The first magnetic field 205 generates a positive voltage component across the first Hall element 203 and a negative voltage component across the second Hall element 204 . On the other hand, the second magnetic field 206 creates positive voltage components across both the first and second Hall elements 203 , 204 . The first and second Hall elements 203 , 204 by the second magnetic field 206 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 across the , cancels out, and the voltage component generated across the first and second Hall elements 203 and 204 by the first magnetic field 205 is maintained.

[0047] The first and second Hall elements 203, 204 generate a voltage based on a magnetic field applied to them. The first and second Hall elements 203 , 204 are positioned such that the first magnetic field 205 induces a voltage in the first and second Hall elements 203 , 204 . The strength of the first magnetic field 205 is affected by the presence of the ferromagnetic element 150 , such that the first magnetic field 205 between when the ferromagnetic element 150 is closer to or farther from the distance sensor 200 . difference occurs. By positioning the Hall elements 203 , 204 such that the first magnetic field 205 creates a voltage in the Hall elements 203 , 204 , the distance between the distance sensor 200 and the ferromagnetic element 150 can be measured. have.

The first magnetic field 205 is generated by at least the first permanent magnet element 201 . First, referring to the exemplary embodiment shown in FIG. 3A , the distance sensor 200 includes a first permanent magnet element 201 . The magnetic flux direction of one side of the distance sensor 200 is in the first flux direction away from the ferromagnetic element 150 and the magnetic flux direction of the other side of the distance sensor 200 is the second flux direction towards the ferromagnetic element 150 . The first permanent magnet element 201 is positioned such that a magnetic field loop is created in the direction. The distance sensor 200 may further include core elements 202 positioned to direct the first magnetic field 205 . The first and second Hall elements 203 and 204 are such that the first Hall element 203 is in the region of magnetic flux in the first flux direction and the second Hall element 204 is the magnetic flux in the second flux direction. is positioned in the first magnetic field 205 .

An alternative arrangement is exemplarily shown in FIG. 3B . In this embodiment, a first permanent magnet element 201a and a second permanent magnet element 201b are provided. The magnetic flux direction of one side of the distance sensor 200 is in the first flux direction away from the ferromagnetic element 150 and the magnetic flux direction of the other side of the distance sensor 200 is the second flux direction towards the ferromagnetic element 150 . The polarities of the first and second permanent magnet elements 201a, 201b are arranged opposite to each other so that a magnetic field loop is created in the direction. The distance sensor 200 may further include a core element 202 positioned to direct the first magnetic field 205 . The first and second Hall elements 203 and 204 are such that the first Hall element 203 is in the region of magnetic flux in the first flux direction and the second Hall element 204 is the magnetic flux in the second flux direction. is positioned in the first magnetic field 205 .

At least the first permanent magnet elements 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. The plurality of permanent magnet elements are arranged in such a way that 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 side opposite the ferromagnetic element 150 . (Halbach) can be oriented to form an array. The Halbach array does not create a magnetic field on the back surface of the Halbach array, so other components located within the levitation unit, which may be susceptible to magnetic interference, are less compared to conventional magnetic elements. It has the advantage that it is influenced by the first magnetic field to an extent.

According to embodiments of the present disclosure, the first and second Hall elements 203 , 204 cause the first magnetic field 205 to be positive in the first and second Hall elements 203 , 204 . They are oriented opposite to each other to create a voltage. This means that the first Hall element 203 positioned in the region of magnetic flux in the first flux direction is oriented in the first flux direction, and the second Hall element 204 positioned in the region of magnetic flux in the second flux direction is It means that the first and second Hall elements 203 , 204 are oriented such that they are oriented in the second flux direction. Accordingly, in the side cross-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.

[0052] When the first and second Hall elements 203, 204 are oriented opposite to each other, the first magnetic field 205 generates the first Hall element 203 such that the magnitudes of the respective voltages are substantially equal to each other. and a positive voltage at both the second Hall element 204 . However, the second magnetic field 206 creates a positive voltage in one of the first or second Hall elements 203 , 204 such that the magnitudes of the respective voltages are substantially equal to each other, and the first and second Hall elements. It creates a negative voltage at the other of elements 203 , 204 . Accordingly, the voltages generated by the first magnetic field 205 are maintained and the voltages generated by the second magnetic field 206 are canceled, so that the output voltage of the second magnetic field 206 relative to the output voltage of the distance sensor 200 . Voltages generated by each of the first and second Hall elements 203 and 204 may be added to compensate for any effect of the measured voltage.

[0053] As an alternative embodiment, the first and second Hall elements 203, 204 are configured such that the first magnetic field 205 generates a positive voltage at one Hall element and a negative voltage at the other Hall element. They may be oriented in the same direction as each other. Accordingly, in the cross-sectional side views shown in FIGS. 3A and 3B , in this case, the first and second Hall elements 203 , 204 are both upwardly oriented or both downwardly oriented.

[0054] When the first and second Hall elements 203, 204 are oriented in the same direction as each other, the first magnetic field 205 generates the first Hall element ( A positive voltage is generated at 203 and a negative voltage is generated at the second Hall element 204 . However, the second magnetic field 206 creates a positive voltage in both the first and second Hall elements 203 , 204 such that the magnitudes of the respective voltages are substantially equal to each other. Accordingly, the voltages generated by the first magnetic field 205 are maintained and the voltages generated by the second magnetic field 206 are canceled, so that the output voltage of the second magnetic field 206 relative to the output voltage of the distance sensor 200 . The voltages generated by each of the first and second Hall elements 203 and 204 may be subtracted to compensate for any effect of the measured voltage.

By configuring the distance sensor 200 according to the present disclosure, stray magnetic fields may be compensated. The floating magnetic fields may be generated, for example, by an electromagnetic actuator, a magnetic element on a substrate carrier, or a cathode target. Compensating for stray magnetic fields enables the distance sensor 200 to be positioned closer to the electromagnetic actuator, so that improved performance of the magnetic levitation system can be achieved through co-location of the sensor and actuator. Also, by compensating for stray magnetic fields, the distance sensor 200 can produce a more reliable and accurate distance measurement, so that the distance between the carrier and the magnetic levitation system can be maintained more reliably and more accurately.

According to an embodiment of the present disclosure, which may 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 It may be configured to compensate for stray magnetic fields acting on one distance sensor. The controller 179 may be electrically attached to the at least one distance sensor 200 such that the controller 179 may receive first and second signals from the first and second Hall elements, respectively. The controller 179 may be configured to subtract the first and second signals from each other such that signal components generated by the stray magnetic field generated by the at least one electromagnetic actuator are compensated.

[0057] According to a third embodiment of the present disclosure, there is provided a method for measuring a distance to a ferromagnetic element. The method includes providing a distance sensor comprising a first Hall element and a second Hall element, detecting a first signal of the first Hall element and a second signal of a second Hall element, and a second signal from the first signal. 2 subtracting the signal.

Reference is now made to FIG. 4 , which shows a flow diagram for a method 500 for measuring a distance to a ferromagnetic element in accordance with embodiments of the present disclosure. The method 500 begins at a beginning 510 .

At block 511 , a distance sensor comprising a first Hall element and a second Hall element is provided. The distance sensor may be a distance sensor according to embodiments described herein, and the distance sensor may measure a distance to a ferromagnetic element. A distance sensor may be provided, for example, in proximity to an electromagnetic actuator. An unwanted stray magnetic field generated by the electromagnetic actuator may affect the distance sensor, causing cross-coupling between the electromagnetic actuator and the distance sensor.

At block 512 , a first signal of a first Hall element is detected, while at block 513 , a second signal of a second Hall element is detected. The first and second signals of the first and second Hall elements, respectively, may include components of a floating magnetic field signal and a distance measurement signal, respectively. The ranging signal components of each of the first and second signals may be substantially equal in magnitude but opposite in polarity, while the stray magnetic field signal components of each of the first and second signals may be substantially equal in magnitude and , may have the same polarity.

At 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 each of the first and second signals are substantially the same in magnitude and have the same polarity, subtracting the first and second signals from each other may result in stray magnetic field signal components of the first and second signals. offset each of them. Thus, the stray magnetic field signal components can be compensated to generate a distance signal that remains unaffected by the unwanted stray magnetic field. Finally, the method 500 ends at an end 520 .

According to further embodiments, which may be combined with other embodiments described herein, the distance sensor provided at block 511 further comprises at least a first permanent magnet element for generating a first magnetic field. wherein the direction of the first magnetic field at the position of the first Hall element is substantially opposite the direction of the first magnetic field at the position of the second Hall element. Alternatively, the distance sensor provided at 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, wherein the distance sensor at the position of the first Hall element is The direction of the first magnetic field is substantially opposite the direction of the first magnetic field at the position of the second Hall element. Thus, the first magnetic field causes the first Hall element to generate a first ranging signal component, the second Hall element to generate a second ranging signal component, and the polarity of the first ranging signal component is the second The polarity of the distance measurement signal component is reversed. For example, a first magnetic field causes a first Hall element to generate a positive voltage component and a second Hall element to generate a negative voltage component. The magnitude of the first and second ranging signal components generated by the first and second Hall elements, respectively, may be substantially the same, so that in block 514 , the first and second of the first and second Hall elements When the two signals are each subtracted from each other, the first and second ranging signal components do not cancel each other, and the first and second stray magnetic field components are compensated. Thus, a distance signal can be generated that remains unaffected by the effects of the stray magnetic field.

Method 500 may be performed using a controller. For example, referring back to FIGS. 2A and 2B , method 500 may be performed by controller 179 , which may be a component of levitation unit 175 . The controller 179 may be electrically attached to at least the distance sensor 200 such that the controller 179 receives the first signal and the second signal as inputs.

As discussed above, one aspect of a magnetic levitation system is to employ electromagnetic actuators and distance sensors to achieve a minimized size of the magnetic levitation system, and improved control behavior through colocation of the actuator and sensor. Positioning close to each other within the floating unit. One undesirable effect on closer proximity between electromagnetic actuators and distance sensors is that the stray magnetic fields generated by the electromagnetic actuators introduce a cross-coupling effect with the distance sensors. Embodiments described herein address this problem by subtracting their signals to compensate for stray magnetic fields, for example using first and second Hall elements.

However, it is further undesirable in that when the distance sensor is positioned much closer to the electromagnetic actuators, the stray magnetic field may not equally affect the first and second Hall elements in the distance sensor. no effect is introduced. For example, the curvature of the stray magnetic field may be higher in the region where the distance sensor is positioned, or the magnitude of the stray magnetic field may not be uniform. These effects are particularly problematic, for example, for distance sensors that may be positioned between electromagnetic actuators. In such cases, the first and second magnetic field signal components may not be sufficiently equal in magnitude such that the second magnetic field signal is fully compensated through subtraction. Accordingly, further compensation of these effects may be advantageous.

Reference is now made to FIG. 5 , which shows a flow diagram for a method 501 for measuring a distance to a ferromagnetic element. According to embodiments of the present disclosure, which may be combined with other embodiments described herein, method 501 detects a coil current of at least one electromagnetic actuator and is generated by the at least one electromagnetic actuator using the coil current to estimate the magnetic flux, and compensating for an erroneous component of the distance signal measured by the distance sensor. Method 501 begins at start 510 .

The method 501 comprising blocks 511 , 512 , 513 and 514 according to the method 500 described above includes, in block 515 , detecting a coil current of at least one electromagnetic actuator. further includes The coil current of an 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 a coil of the electromagnetic actuator.

Also at block 516 , the magnetic flux generated by the at least one electromagnetic actuator is estimated. The estimate of the generated magnetic flux is based on the coil current of the at least one electromagnetic actuator as detected at block 515 . Estimating the magnetic flux includes generating a magnetic flux compensation signal that can be used to compensate for erroneous components of the distance signal generated by the distance sensor.

Finally, at block 517, the erroneous component of the distance signal measured by the distance sensor is compensated. Compensation is performed by subtracting the magnetic flux compensation signal generated in block 516 from the distance signal detected by the distance sensor, so that the cross-coupling between the electromagnetic actuator and the distance sensor, which has not yet been compensated by block 514 . The additional effects of

Performing the method 501 as described above enables further compensation of stray magnetic fields, such as stray magnetic fields of non-uniform or high curvature, or stray magnetic fields from adjacent electromagnetic actuators. Thus, the distance sensors can be positioned much closer to the electromagnetic actuators, further improving the performance of the magnetic levitation system.

According to embodiments of the present disclosure, which may 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. calculating a model of the magnetic flux. The coil current may induce eddy currents in the housing 176, for example, or may produce a given flux magnitude that is frequency dependent. Also, the ferromagnetic element 150 may be a non-laminate element, which may introduce frequency dependence. The model may include a predetermined or pre-computed model of the magnetic flux generated by the electromagnetic actuator for a given coil current magnitude and/or frequency. For example, the model may include a lookup table of pre-computed values. Alternatively, the model may be calculated in real time based on a mathematical approximation of the magnetic flux generated by the electromagnetic actuator for a given coil current magnitude and/or frequency.

[0072] A model of magnetic flux may be determined by measuring the magnetic flux behavior of an electromagnetic actuator in response to an applied coil current and determining its effect on a distance signal. The ferromagnetic element is fixed at a known distance from the distance sensor, and a coil current is applied to the electromagnetic actuator to generate a distance signal from the distance sensor. Varying the coil current applied to the electromagnetic actuator creates a change in magnetic flux, which under the influence of the magnetic flux changes the distance signal from the distance sensor. By measuring the change in the distance signal based on the coil current, a model for estimating the effect of the magnetic flux of the electromagnetic actuator on the distance signal based on the coil current can be calculated.

The model may take into account additional parameters for estimating the magnetic flux generated by the at least one electromagnetic actuator. For example, the model may include parameters related to the coil current of at least one neighboring electromagnetic actuator. When an electromagnetic actuator is positioned in close proximity to its neighbors, the stray magnetic flux generated by the neighboring electromagnetic actuator may also cross-couple with the neighboring distance sensors. Thus, an erroneous component of the distance signal generated by the distance sensor, caused by the stray magnetic flux acting on the distance sensor, can be further compensated.

According to embodiments of the present disclosure, which may be combined with other embodiments described herein, estimating the magnetic flux is performed on a digital signal processor. Digital signal processors typically include analog-digital converters (ADCs), digital signal processing units, and digital-analog converters (DACs) that allow analog signals to be manipulated in real time. make it possible The digital signal processor may be a separate component provided to the injury unit, or may be integrated into the controller for the injury unit. Performing the estimation of the magnetic flux on a digital signal processor enables real-time estimation of the magnetic flux, allowing for faster acquisition of the distance signal and further of the levitation system in maintaining the target distance between the carrier and the levitation system. Enables high performance.

[0075] While the foregoing relates to embodiments of the present disclosure, other and additional embodiments of the disclosure may be devised without departing from the basic scope of the disclosure, the scope of the disclosure being determined by the claims of

Claims (16)

A distance sensor (200) for measuring a distance to a ferromagnetic element (150), comprising:
at least a first permanent magnet element (201, 201a);
at least a first hall element 203; and
at least a second Hall element (204);
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 direction of the second Hall element substantially opposite the direction of the first magnetic field (205) at the position of (204);
distance sensor 200 . According to claim 1,
further comprising at least a second permanent magnet element (201b) arranged parallel to the first permanent magnet element (201a) and having a polarity opposite to that of the first permanent magnet element (201a);
the first permanent magnet element (201a) and the second permanent magnet element (201b) generate the first magnetic field (205);
distance sensor 200 . According to claim 1,
The first Hall element 203 and the second Hall element 204 are configured such that the first magnetic field 205 generates a positive voltage in the first Hall element 203 and the second Hall element 204 . , oriented opposite to each other,
distance sensor 200 . 3. The method of claim 2,
The first Hall element 203 and the second Hall element 204 are configured such that the first magnetic field 205 generates a positive voltage in the first Hall element 203 and the second Hall element 204 . , oriented opposite to each other,
distance sensor 200 . A magnetic levitation system (100) for magnetically levitating a ferromagnetic element (150), comprising:
at least one electromagnetic actuator 178; and
It comprises at least one distance sensor (200) according to any one of claims 1 to 4,
wherein the at least one distance sensor (200) is configured to measure a distance (X) to the ferromagnetic element (150).
Magnetic Levitation System (100). 6. The method of claim 5,
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);
Magnetic Levitation System (100). 7. The method of claim 6,
the controller (130, 179) is configured to compensate for magnetic fields generated by the at least one electromagnetic actuator (178) and acting on the at least one distance sensor (200);
Magnetic Levitation System (100). 6. The method of claim 5,
wherein the at least one electromagnetic actuator (178) is configured to transport the ferromagnetic element (150) in a transport direction (192).
Magnetic Levitation System (100). 6. The method of claim 5,
wherein the ferromagnetic element is a substrate carrier (110);
Magnetic Levitation System (100). 7. The method of claim 6,
The at least one electromagnetic actuator 178 , the at least one distance sensor 200 and the controller 179 are contained within an airtight housing 176 , the housing 176 containing a non-ferromagnetic material. containing,
Magnetic Levitation System (100). 6. The method of claim 5,
The magnetic levitation system 100 is configured for operation in a vacuum.
Magnetic Levitation System (100). A method for measuring a distance (X) to a ferromagnetic element (150), comprising:
providing a distance sensor (200) comprising a first Hall element (203), a second Hall element (204), and at least a first permanent magnet element (201, 201a) for generating a first magnetic field (205) - the direction of the first magnetic field 205 at the position of the first Hall element 203 is substantially opposite the direction of the first magnetic field 205 at the position of the second Hall element 204 - ;
detecting a first signal of the first Hall element (203) and a second signal of the second Hall element (204); and
subtracting the second signal from the first signal;
A method for measuring a distance (X) to a ferromagnetic element (150). 13. The method of claim 12,
detecting a coil current of at least one electromagnetic actuator (178);
estimating the magnetic flux generated by the at least one electromagnetic actuator (178) using the coil current; and
Compensating for an erroneous component of the distance signal measured by the distance sensor (200),
A method for measuring a distance (X) to a ferromagnetic element (150). 14. The method of claim 13,
The estimating of the magnetic flux comprises calculating a model of the magnetic flux based on at least one of a magnitude or a frequency of the coil current.
A method for measuring a distance (X) to a ferromagnetic element (150). 5. A method of using a distance sensor (200) according to any one of claims 1 to 4 in a magnetic levitation device (100), comprising:
The distance sensor 200 is configured to measure the distance X to the injured body,
How to use the distance sensor 200 . delete

Images