Linear guideway assembly for non-contact linear displacement of a rigid body relative to another rigid body along a linear displacement path - Patents.com

Abstract

The present invention relates to a linear guideway assembly for non-contact linear displacement of one rigid body relative to another rigid body along a linear displacement path (x), comprising one single rigid body formed as a linear guideway defining the linear displacement path, and at least one rigid body formed as a product carrier displaceable along the single linear guideway, the linear guideway assembly further comprising a plurality of magnetic bearing assemblies for enabling non-contact linear displacement of at least one product carrier relative to the single linear guideway, all of the magnetic bearing assemblies being attached to the product carrier such that the magnetic bearing assemblies are positioned to constrain five degrees of freedom (y, z, θ, Φ, ψ) of the product carrier relative to the single linear guideway while allowing one translational degree of freedom (x) of the product carrier along the single linear guideway, and all of the magnetic bearing assemblies are attached to the side of the product carrier closest to the single linear guideway in the translational direction (x) of the linear displacement path.

Description

[Technical field]

[0001] The present invention relates to a linear guideway assembly for the non-contact linear displacement of a rigid body relative to another rigid body along a linear displacement path (x).

[0002] The present invention also relates to a linear guideway assembly that implements one or more magnetic bearing assemblies. [Background technology]

[0003] Magnetic bearing assemblies or short magnetic bearings may offer an advantageous alternative to conventional rolling bearings that implement rolling elements or hydrodynamic bearings. Given that magnetic bearings are contactless, there is no mechanical friction and therefore little particle generation. Furthermore, the absence of the need for lubrication allows vacuum operation without significant release of molecular contaminants. These aspects allow the omission of contamination seals. The main challenges of applying magnetic bearings in high-tech in-vacuum systems are to minimize the heat dissipation of the coils, minimize the effects of eddy currents, implement a stable control system and generally linearize the nonlinear characteristics.

[0004] Magnetic bearing technology is already used in industrial applications. Rotary magnetic bearings are commercially available and are applied, for example, in medical systems, turbomolecular vacuum pumps, cryogenic systems, and machine tools. Another category is bearingless motors, where the rotor is magnetically suspended. Magnetic levitation is generally based on the Lorentz force and is widely used in the actuation of planar stages. Other types of magnetic bearings are based on magnetic reluctance forces, in which case a similar concept can also be used as an actuator.

[0005] Although used in other fields, further development of commercial scale magnetic bearing applications, for example in high-clean substrate processing robotics, is subject to technical and structural constraints. Generally known magnetic bearing applications are characterized by their limited design dimensions, while known magnetic bearing applications involving multiple degrees of freedom are complex to design and expensive. Furthermore, scaled-up implementation of magnetic bearing applications requires the development of magnetic bearings of significant weight, size and cost, while conventional rolling bearings can still be utilized for similar purposes.

[0006] Preloading known linear rolling bearings improves their accuracy in terms of displacement, but the preload also increases the risk of increased particulate contamination. Also, although ceramic or hybrid rolling bearings do not require any lubrication and therefore contribute little molecular contamination, such bearings may have limited preload capabilities and are therefore less suitable for high load / high precision applications such as those in vacuum systems and under vacuum conditions.

[0007] Similarly, hydrodynamic bearings present a risk of turbulence (contamination) in atmospheric systems and impose undesirable gas loads in vacuum systems.

[0008] All of the above bearing concepts result in some contamination, either particulate or molecular or both, and in such applications seals are used to prevent the migration of contaminants into the clean environment.

[0009] Known prior art applications such as JP 62-165019, US Patent Publication No. 5,196,745, WO 2012 / 165872, and China Patent No. 103277409 implement linear guideway assemblies for non-contact linear displacement of rigid bodies, where the rigid bodies are completely surrounded or locked by the structure of the linear guideway. Such applications have some limitations such as flexibility regarding transportation of the rigid bodies, but also limit the accessibility of the rigid bodies, especially when such applications are implemented in a robotic handling system or a vacuum system. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 62-165019 [Patent Document 2] U.S. Patent Publication No. 5,196,745 [Patent Document 3] International Publication No. 2012 / 165872 Brochure [Patent Document 4] Chinese Patent No. 103277409 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention aims to provide a solution to the above identified problems, which allows for the linear displacement of one rigid body relative to another along a linear displacement path, and in particular allows for contactless and frictionless control of the translational degree of freedom of one rigid body relative to another, while any preload acting on the rigid body to be displaced does not cause further pollution of the environment. [Means for solving the problem]

[0012] Therefore, a linear guideway assembly is proposed, comprising one single rigid body formed as a linear guideway defining said linear displacement path, and at least one rigid body formed as a product carrier displaceable along said single linear guideway, the linear guideway assembly further comprising a plurality of magnetic bearing assemblies for enabling non-contact linear displacement of at least one product carrier relative to the single linear guideway, all magnetic bearing assemblies being mounted on the product carrier such that the magnetic bearing assemblies are positioned constraining five degrees of freedom (y, z, θ, Φ, ψ) of the product carrier relative to the single linear guideway while allowing one translational degree of freedom (x) of the product carrier along the single linear guideway, and all magnetic bearing assemblies are mounted on the side of the product carrier closest to the single linear guideway in the translational direction (x) of the linear displacement path.

[0013] By implementing one single linear guideway as the linear displacement path guideway and mounting all magnetic bearing assemblies on the side of the product carrier closest to the single linear guideway in the translational direction (x) of the linear displacement path, i.e., on one longitudinal side, the product carrier can be displaced in one translational degree of freedom (x), while the five degrees of freedom (y, z, θ, Φ, ψ) of the product carrier relative to the single linear guideway are constrained. Such a simple yet inexpensive structure provides a good alternative to conventional rolling bearings or hydrodynamic bearings.

[0014] Additionally, the non-contact nature of such linear guideway assemblies prevents any contamination and eliminates vacuum seals. Magnetic bearings impose no gas load on vacuum systems and do not cause turbulence in atmospheric systems.

[0015] In one example, the single linear guideway is provided with a first guide recess on a side of the linear path facing away from the product carrier, as viewed in the translation direction (x) of the linear displacement path, and a second guide recess on the other side of the linear path facing towards the product carrier, and each magnetic bearing assembly is at least partially received in one of the guide recesses.

[0016] In particular, two first magnetic bearing assemblies (y, θ) are respectively mounted on the front and rear sides of the product carrier in the translation direction (x) of the linear displacement path and received in the first guiding recesses.

[0017] To enable proper balancing of the gravitational forces acting on the product carrier, while it is supported on one side relative to the single linear guideway, two second magnetic bearing assemblies (z, ψ) are mounted respectively on the front and rear sides of the product carrier in the translation direction (x) of the linear displacement path and are received in second guide recesses.

[0018] To constrain rotation of the product carrier within the linear guideway assembly, one third magnetic bearing assembly (Φ) is mounted between the front and rear sides of the product carrier in the translation direction (x) of the linear displacement path and is received in the first guide recess.

[0019] Each of the magnetic bearing assemblies is mounted to a product carrier; *Ferromagnetic core, a first magnetic element located on a first side of the ferromagnetic core and oriented toward a single linear guideway; a coil wound around the ferromagnetic core; At least one magnetic bearing module, The one bearing module is positioned to maintain a clearance distance with a single linear guideway during use.

[0020] In this way, a magnetic bearing assembly is obtained that allows for non-contact linear displacement of one rigid body relative to another without friction, resulting in no particle generation or out-gassing of lubricant. In particular, linear displacement of the rigid bodies relative to one another is thereby possible perpendicular to the direction of stiffness of the overall structure.

[0021] In a particularly advantageous embodiment, the magnetic bearing module further comprises a setting module located on the other side of the ferromagnetic core opposite to the first side and received in either the first or second guiding recess of the single linear guideway, said setting module being arranged to set the gap distance between the magnetic bearing module (product carrier) and the single linear guideway.

[0022] In particular, the setting module is a controllable setting module which allows greater control of the net force exerted on the magnetic bearing module, thereby also controlling the position (gap distance) of the magnetic bearing module mounted on the product carrier relative to a single linear guideway.

[0023] In another embodiment, the setting module comprises a second magnetic element configured as a second permanent magnetic element. The second magnetic element creates a magnetic force acting in the opposite direction to the active bearing module to help provide a preload and static force balance. For example, the second magnetic element creates a constant reaction force or provides a static, constant force required to counteract the gravitational force created by the weight of the product carrier and its load, thus minimizing power losses.

[0024] One of both elements is mechanically adjustable relative to the other to adjust the steady-state force balance to compensate for tolerances (e.g., tolerances of the permanent magnets). A further advantage of this configuration is that there is no power loss in the steady state. This allows further configurability of the magnetic bearing module by applying a constant preload in a direction opposite to the direction of the attractive force towards the first static back iron generated by the ferromagnetic core and the first magnetic element, thereby controlling the distance gap between both rigid bodies and therefore the non-contact linear displacement of said bodies relative to each other with zero heat dissipation.

[0025] In particular, the ferromagnetic core is an E-core having a base, a central leg, and two outer legs, where the first magnetic element is located in the central leg and the coil is wound around the central leg. In another example, the E-core is a laminated E-core.

[0026] Additionally, the first magnetic element can be a permanent magnet.

[0027] The invention will now be described in more detail with reference to the accompanying drawings. [Brief description of the drawings]

[0028] [Figure 1] 1 illustrates a schematic example of one embodiment of a magnetic bearing assembly. [Figure 2a] 1 shows a schematic example of another embodiment of a magnetic bearing assembly. [Figure 2b] 13 shows a schematic example of yet another embodiment of a magnetic bearing assembly. [Figure 3a] 1 shows a top view of a schematic example of one embodiment of a linear guideway assembly according to the present invention; [Figure 3b] FIG. 1 shows a front view of a schematic example of one embodiment of a linear guideway assembly according to the present invention. [Figure 3c] A detailed view of FIG. 3b is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] For a better understanding of the invention, like parts in the drawings are designated with like reference numerals. The proposed concept of a magnetic bearing assembly shown in the attached drawings consists of a small bearing element that constrains a single translational degree of freedom of one rigid body relative to another. It should be noted that multiple bearing elements can be combined to constrain or control multiple degrees of freedom, for example as shown in the embodiment of Figures 3a and 3b.

[0030] A first schematic example of a variable reluctance magnetic bearing assembly is shown in Figure 1. The example magnetic bearing assembly of Figure 1 is designated by reference numeral 10 (reference numeral 10' in Figures 2a-b) and allows for non-contact linear displacement (or a single translational degree of freedom) of one rigid body relative to another rigid body along a linear displacement path. In Figure 1, one of the rigid bodies is designated by reference numeral 30 (as well as in Figures 2a-b and as reference numeral 300 in Figure 3), and the other rigid body is designated by reference numeral 20 (reference numerals 20a-20b in Figures 2a-b and reference numeral 110 in Figure 3).

[0031] The magnetic bearing assembly 10 comprises at least one bearing module 31-34 attached to one of the rigid bodies 30 and consisting of at least a ferromagnetic core 31. For the sake of understanding, it should be noted that any ferromagnetic core configuration can be implemented. However, in this preferred example, the ferromagnetic core 31 is an E-core having a base 31a, a central leg 33 and two outer legs 32a-32b. A first magnetic element 34 is located on a first side of the ferromagnetic core 31, and in this example, a first end of the ferromagnetic core 31 is located and defined at a free end face 33a of the central leg 33. Also, in this example, a coil 35 is wound around the central leg 33 of the E-core.

[0032] However, it should be noted that any ferromagnetic core configuration having a coil wound around the core element and a magnetic element located on a first side of the ferromagnetic core may be implemented in the magnetic bearing assembly 10.

[0033] Further, the magnetic bearing assembly 10 interacts with a first static back iron or back bearing 20 which is attached to (or is part of) the other of the rigid bodies 20 and is positioned in use a certain gap distance 40, indicated as g1 in FIG. 1, from the one of the bearing modules 31-34.

[0034] Preferably, but not necessarily, the ferromagnetic core designated as E-core 31 consists of a laminated E-core, and the first magnetic element 34 is understood as a permanent magnet 34 .

[0035] In use or operation, the first static back bearing or back iron 20 is positioned a gap distance 40 (g1) away from the E-core assembly 31-34-35. This configuration defines a low reluctance path where the resulting magnetic flux density within the air gap g1 defined by the gap distance 40 results in a gap dependent attractive force between the E-core assembly 31-34-35 (and thus one rigid body 30) relative to the other rigid body shown diagrammatically as the first static back bearing (back iron) 20.

[0036] The coil 35 wound around the central leg or tooth 35 of the E-core 31 is used to increase or decrease the magnetic flux density in the air gap g1 (40) depending on the direction and magnitude of the current flowing through the coil 35. It should be noted that the magnetic bearing assembly 10 (actually, at least one bearing module 31-34-51) can only generate an attractive force between the E-core 31 and the first static back bearing (back iron) 20, but cannot generate a repulsive force.

[0037] 2a-b, another example of a magnetic bearing assembly, designated 10', is shown. In this embodiment, the magnetic bearing assembly 10' is provided with a further setting module 50, which is located on the opposite side of the E-core 33 to the first magnetic element side 33a-34. Preferably, but not necessarily, the setting module 50 comprises a second magnetic element 51.

[0038] The setting module 50 provides or applies a constant preload to the magnetic bearing assembly 10' in a direction opposite to the direction of the attractive force generated by the E-core 31 and the first magnet 34. The resulting net force acting on the magnetic bearing module 31-34-50 itself can be controlled, and thereby also the position (actually the distance g1) of the rigid body 30 at which the magnetic bearing module 31-34-50 is attached relative to the further static back-iron 20b which is part of the other static back-iron 20a of said rigid body 20.

[0039] It should be noted that in Figures 2a-2b, both reference numerals 20a-20b are considered to represent structural elements that are part of one and the same rigid body defined in the pending claims as a single linear guideway, while reference numeral 30 constitutes the other of the rigid body defined in the pending claims as a product carrier, and that the magnetic bearing assembly described herein enables non-contact linear displacement of the substrate / product carrier (30) relative to the single linear guideway (20a-20b) of the linear guideway assembly along a linear displacement path (x).

[0040] Depending on the orientation of the bearing module 31-34-50 attached to the substrate / product carrier (30), gravitational balance (based on the weight of the magnetic bearing module 31-34-50) may provide at least a portion of this preload.

[0041] Thus, reference numeral 20a defines a first static back bearing or back iron, while reference numeral 20b defines a further static back bearing or back iron.

[0042] The preload can be increased by configuring the setting module 50 as a second magnet 51 located on the opposite side of the E-core / spoil / first magnet configuration 33-35-34, as shown in Fig. 2a. The second magnet 51, which may in particular be a permanent magnet 51, can be attached to the other side of the E-core 31, in particular to the other side of the base 31a.

[0043] This second (permanent) magnet 51 provides a preload force in the air gap g2 (41) between the magnetic bearing module 31-34-35-50 attached to one of the rigid bodies 30 and the other of the rigid bodies 20b. The energy dissipation of the bearing modules can be minimized by adjusting the magnetic preload force exerted by the setting module 51 so that all static forces are balanced. In this case, only the electromagnets (E-core 31 and spoiler 35) are needed to counteract dynamic disturbances during the linear displacement of one of the rigid bodies 30 relative to the other rigid body 20a-20b. Manufacturing tolerances and relatively large variations in the dimensions and magnetic moments of the permanent magnets may result in deviations from this static force balance.

[0044] In a further example 10'' of a magnetic bearing assembly according to the invention (see FIG. 2b), the setting module 50 comprises a controllable adjustment mechanism 52 which is located next to the second permanent magnet 51, between the base 31a of the E-core 31 and the second (permanent) magnet 51. This allows presetting of the distance or air gap g2 (41) between the magnetic bearing module 31-34-35-50 attached to one of the rigid bodies 30 and the other 20b of the rigid body, thereby allowing the preload force to be adjusted so that the static forces exerted by both the first and second magnets 34-51 are balanced, minimizing any energy dissipation.

[0045] This example, when combined with a position sensor (or magnetic flux sensor) and motion control software (not shown) consisting of a current control loop and a position control loop, can be used to actively control the air gap 40 (g1) between the magnetic bearing module 31-34-35 and the first static back iron 20 attached to one of the rigid bodies (30; 20a-20b) to compensate for dynamic disturbances that occur during the linear displacement of one of the rigid bodies relative to the other rigid body by adjusting the current through the electromagnets 33-35.

[0046] 3a, 3b and 3c show an example (top view, front view and detailed view respectively) of an implementation or application of multiple magnetic bearing assemblies in a linear guidance assembly 100. In this non-limiting example, a total of five magnetic bearing assemblies 30-1; 30-2; 30-3; 30-4+50-4; 30-5+50-5 are shown interacting with rigid bodies 110, 300. Rigid body 300 is defined as a substrate / product carrier while rigid body 110 is defined as a single linear guideway that serves as a fixed world along which substrate / product carrier 300 moves.

[0047] The magnetic bearing assemblies 30-1; 30-2; 30-3; 30-4+50-4; 30-5+50-5 described herein enable non-contact linear displacement of a product carrier 300 relative to a single linear guideway 110 along a linear displacement path (x). The carrier 300 is preferably configured as a flat, square or rectangular support element for supporting a semiconductor product during its transportation along the linear displacement path (x). The carrier 300 has a first longitudinal side 300a, a second longitudinal side 300b opposite the first longitudinal side 300a, a front side 300c and a rear side 300d (opposite the front side 300c), both viewed in the direction of transportation or linear displacement path (x) along the single linear guideway 110.

[0048] The linear guideway assembly 100 comprises one single linear guideway or guide rail 110. This means that the carrier 300 is supported, guided and transported at its first longitudinal side 300a along a linear displacement path (x) by the single linear guideway or guide rail 110, while its other, second opposite longitudinal side 300b is unsupported and free to move along the linear displacement path (x).

[0049] In this non-limiting example, the single linear guide rail 110 is provided with a first guide recess 110a, which extends in the longitudinal direction (x) of the guide rail 110 on the side of the guide rail 110 facing away from the product carrier 300. Furthermore, the single linear guide rail 110 is provided with a second guide recess 110b, which extends in the longitudinal direction (x) of the guide rail 110 on the side of the guide rail 110 facing towards the product carrier 300. Both guide recesses 110a-110b serve to partially receive one or more magnetic bearing assemblies 30-1; 30-2; 30-3; 30-4+50-4; 30-5+50-5. The magnetic bearing assemblies 30-1; 30-2; 30-3; 30-4+50-4; 30-5+50-5 are attached to a carrier 300 by a number of carrier supports 300-1; 300-2; 300-3; 300-4; 300-5. The product carrier 300 is attached to and guided along a linear guideway 100 formed by a single linear guide rail 110.

[0050] It should be noted that, as defined in the pending claims and as illustrated in connection with the examples of Figures 2a-2b and 3a-3c, the product carrier 300 constitutes one of the rigid bodies and the guide rail 110 constitutes the other of the rigid bodies.

[0051] In particular, in this example of a linear guideway assembly 100, several magnetic bearing assemblies 30-1; 30-2; 30-3; 30-4+50-4; 30-5+50-5 are implemented in a linear guideway with a displacement stroke of, for example, 600 mm as part of a substrate carrier handling robot in a high cleanliness substrate processing environment. The single straight or linear guideway 110 allows one translational degree of freedom (x) available for actuation, which allows the carrier 300 to be displaced in the x-direction along a linear displacement path defined by the single linear guideway 110.

[0052] The remaining five degrees of freedom y, z, θ, Φ, ψ are constrained as shown diagrammatically in Figures 3a-3b-3c. Magnetic bearing assemblies 30-1; 30-2; 30-3; 30-4+50-4; 30-5+50-5 are connected or attached to the product carrier 300 and constrain the five degrees of freedom y, z, θ, Φ, ψ to a displacement beam (not shown) that is part of the travel link or arm of the robot. In this example, five magnetic bearing assemblies 30-1; 30-2; 30-3; 30-4+50-4; 30-5+50-5 are applied.

[0053] The magnetic bearing modules implemented in this example are characterized by being based on the variable reluctance principle and consisting of an electromagnetic actuator, a permanent magnet for position measurement and, optionally, a preload, the latter being used to provide a static, constant force to generate a constant reaction force or to minimize power losses by counteracting the gravitational force generated by the weight of the product carrier and its load. Each of these bearing modules can generate only an attractive force (and therefore only a force in one direction). To allow actuation in both directions, a preload in the opposite direction to the attractive force is required.

[0054] Three magnetic bearing assemblies 30-1; 30-2; 30-3 constrain the out-of-plane degrees of freedom, i.e., z, Φ, ψ directions, of the carrier 300 relative to a single linear guideway or guide rail 110. Two further magnetic bearing assemblies 30-4+50-4; 30-5+50-5 impose the remaining in-plane degrees of freedom, y, θ.

[0055] Any preload application described above for the three out-of-plane magnetic assemblies 30-1; 30-2; 30-3 is performed (biased) by gravity and therefore does not implement an additional setting module 50 as shown in Figures 2a-b, which acts as a prestressed bearing, which is a clear advantage of this embodiment.

[0056] Adjustment or preloading of the three out-of-plane magnetic bearing assemblies 30-1, 30-2, 30-3 is performed by the electromagnets formed by the E-cores 31 and coils 35 of each magnetic bearing assembly 30-1; 30-2; 30-3 by adjusting the air gaps 40b-1; 40b-2; 40b-3 for each magnetic bearing assembly, thereby matching the static forces of the assembly with gravity and minimizing steady state dissipation (see Figures 2a-b).

[0057] Similarly, the electromagnets formed by the E-cores 31 and coils 35 of each magnetic assembly 30-1; 30-2; 30-3, together with their respective first permanent magnets 34-1; 34-2; 34-3, preset and control the gap distance g1 (40b-1; 40b-2; 40b-3) between the product carrier 300 and the single linear guide rail 110.

[0058] The preloading of the magnetic assemblies 30-1; 30-2; 30-3 can be done using permanent magnets 34-1; 34-2; 34-3 rather than by the weight of the mechanism, at the expense of additional negative stiffness that needs to be compensated for by the control loop.

[0059] The magnetic bearing modules 30-1, 30-2 constrain the out-of-plane degrees of freedom z, ψ and are received in the second guide recess 110b of the single linear guide rail 110. These magnetic bearing modules are preloaded by the carriage's gravity and the payload mass. These two magnetic bearing modules 30-1, 30-2 therefore contain permanent magnets 34 (see Fig. 2a-b) to generate a static force that compensates for the weight of the substrate / product carrier 300 and its payload (e.g. semiconductor substrate) attached thereto. The air gaps of these bearings can be mechanically adjusted to balance the static permanent magnet 34 force with the constant force required to carry the weight, thereby minimizing power losses. The magnetic bearing modules 30-1, 30-2 can compensate for the permanent magnet tolerances and mechanical tolerances. To close the control loop, displacement sensors are used, one for each individual bearing module.

[0060] The magnetic bearing module 30-3 constrains the rotational degree of freedom Φ, thereby preventing unwanted rotation of the substrate / product carrier 300 in the plane defined by the carrier. The magnetic bearing module 30-3 includes a permanent magnet 34 that is received in a first guide recess 110a of a single linear guide rail 110 and is gravitationally preloaded to balance static forces to minimize dissipation. A displacement sensor is used to close the control loop.

[0061] The in-plane degrees of freedom y, θ are preloaded by two magnetic assemblies 30-4+50-4 and 30-5+50-5. The position control loop is closed using a displacement sensor (capacitive, optical, etc.). Each individual setting module 50-4, 50-5 requires one displacement sensor but does not implement a second permanent magnet 51, since there are no static forces acting on these bearings. Alternatively, the preloading of the setting modules 50-4, 50-5 can be done using a permanent magnet 51, but this would result in an additional negative stiffness that needs to be compensated for by the control loop.

[0062] The setting modules 50-4, 50-5 are received in the first guide recess 110a of the single linear guideway / guide rail 110 and provide a preload force to the y and θ bearing modules 30-4, 30-5. In a static state, both the bearing modules 30-4+30-5 and the setting modules 50-4+50-5 generate a small (opposing) attractive force of a few newtons to avoid magnetic hysteresis. The preload bearings do not require any position sensor. Other preload mechanisms can consist of only a permanent magnet 51 to generate a constant force, but in this case the negative stiffness inherent in two permanent magnets acting against each other is avoided. The air gap of the preload bearings can be mechanically adjusted to compensate for mechanical tolerances.

[0063] Here, setting modules 50-4, 50-5 and magnetic bearing modules 30-4, 30-5 (each consisting of an E-core 31, coil 35, and first permanent magnet 34-4, 34-5, respectively) are mounted on the same side of the product carrier 300 to control or maintain the desired gap 20a-4, 20a-5 between the substrate / product carrier 300 and a single linear guide rail 110.

[0064] In contrast to conventional rolling linear bearings where five degrees of freedom are constrained, the five constrained degrees of freedom can be actively controlled using active controllable magnetic bearing assemblies 30-1; 30-2; 30-3; 30-4+50-4; 30-5+50-5, thereby compensating for undesirable dynamic behavior of the robot displacing the substrate / product carrier 300 along the guide rails 110 of the linear guideway assembly 100.

[0065] The above example of the magnetic bearing assembly defined in the pending claims is highly suitable for commercial scale implementation in high-clean substrate processing robotic applications. In particular, the product carrier is supported, guided and transported on one single longitudinal side thereof by one single linear guideway, while the other opposite longitudinal side of the product carrier as well as its front and rear sides are unsupported and free to move along a linear displacement path (x) defined by one single linear guideway, thus greatly improving the accessibility and visibility of the working area around the product carrier.

[0066] In particular, such product carriers, in which one longitudinal side is supported, guided and transported and the opposite side is unsupported and free to move, offer improved accessibility for robotic applications, such as robotic pick-and-place arms.

[0067] The magnetic bearing assembly of the present invention can be constructed at low cost due to its limited dimensions and can be easily implemented in thermally critical systems and vacuum environments such as substrate wafer processing applications where stable and well-controlled linear displacement of one rigid body (the substrate carrier 300) relative to another rigid body (the guideway assemblies 100-110) is essential for quality assurance purposes.

[0068] In particular, the proposed magnetic bearing assembly enables displacement stability, stiffness, and energy dissipation in such thermally critical systems and vacuum environments that are not possible with commonly known rolling bearings.

Claims

1. 1. A linear guideway assembly for non-contact linear displacement of a moveable rigid body relative to another rigid body along a linear displacement path (x), comprising: a single rigid body formed as a single linear guideway, the other rigid body defining the linear displacement path; and at least one movable rigid body formed as a product carrier displaceable along said single linear guideway; Equipped with the linear guideway assembly further comprising a group of a plurality of magnetic bearing assemblies for enabling non-contact linear displacement of the at least one product carrier relative to the single linear guideway; the group of magnetic bearing assemblies is attached to the product carrier such that the group of magnetic bearing assemblies is positioned constraining five degrees of freedom (y, z, θ, Φ, ψ) of the product carrier relative to a single linear guideway while allowing one translational degree of freedom (x) of the product carrier along the single linear guideway; the product carrier includes at least a unique first longitudinal side that faces in a direction of the linear displacement path (x) and is closest to the single linear guideway, and a second longitudinal side that is opposite the first longitudinal side; the product carrier is supported, guided and transported at a first longitudinal side thereof along the linear displacement path (x) by a single linear guideway, while an opposite second longitudinal side is unsupported and free to move along the linear displacement path (x), and the group of magnetic bearing assemblies is attached only to the first longitudinal side of the product carrier; Linear guideway assembly.

2. 2. The linear guideway assembly of claim 1, wherein the single linear guideway is provided with a first guide recess facing away from the product carrier and a second guide recess facing towards the product carrier when viewed in a translation direction (x) of the linear displacement path, and each magnetic bearing assembly is at least partially received in one of the guide recesses.

3. 3. The linear guideway assembly of claim 2, wherein two first magnetic bearing assemblies (y, θ) are mounted on the front and rear sides of the product carrier in the translation direction (x) of the linear displacement path and are received in the first guide recesses.

4. 4. The linear guideway assembly according to claim 2 or 3, wherein two second magnetic bearing assemblies (z, ψ) are mounted on the front and rear sides of the product carrier in the translation direction (x) of the linear displacement path and are received in the second guiding recesses.

5. 5. The linear guideway assembly according to claim 2, 3 or 4, wherein one third magnetic bearing assembly (Φ) is mounted between a front side and a rear side of the product carrier in the translation direction (x) of the linear displacement path and is received in the first guiding recess.

6. Each of the magnetic bearing assemblies comprises: - attached to said product carrier; A ferromagnetic core; a first magnetic element located on a first side of the ferromagnetic core and oriented toward the single linear guideway; A coil wound around the ferromagnetic core; At least one magnetic bearing module, At least the one bearing module is positioned to maintain a clearance distance with the single linear guideway during use; A linear guideway assembly according to any one of claims 2 to 5.

7. 7. The linear guideway assembly of claim 6, wherein the magnetic bearing module further comprises a setting module located on the other side of the ferromagnetic core opposite the first side and received in either the first or second guide recess of the single linear guideway.

8. The linear guideway assembly of claim 7 , wherein the setting module is positioned to set the gap distance between the magnetic bearing module and the single linear guideway.

9. 9. The linear guideway assembly according to claim 7 or 8, wherein the setting module is a controllable setting module.

10. 9. The linear guideway assembly of claim 7 or 8, wherein the setting module comprises a second magnetic element configured as a second permanent magnetic element.

11. 11. The linear guideway assembly of claim 6, wherein the ferromagnetic core is an E-core having a base, a central leg, and two outer legs.

12. The linear guideway assembly of claim 11 , wherein the first magnetic element is located on the central leg.

13. The linear guideway assembly of claim 11 , wherein the coil is wound around the central leg.

14. 14. A linear guideway assembly according to any one of claims 11 to 13, wherein the E-core is a laminated E-core.

15. 15. A linear guideway assembly according to any one of claims 6 to 14, wherein the first magnetic element is a permanent magnet.

16. 16. A linear guideway assembly according to any one of claims 6 to 15, wherein each said magnetic bearing assembly is arranged to exert a force in only one direction.

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