DEVICE FOR HOLDING, POSITIONING AND MOVING AN OBJECT

Abstract

The present invention relates to a device for holding, positioning and/or moving an object, with a base and with a carrier movable relative to the base, at least one magnetic bearing for generating a bearing or holding force between the base and the carrier, wherein the carrier is contactlessly supported on the base via the magnetic bearing, at least one drive acting contactlessly between base and carrier for the displacement of the carrier along the base in at least one transport direction, wherein the drive comprises a linear motor with at least one slider and one stator, which are arranged on the base and on the carrier and which, aside from a displacement force acting along the transport direction, are configured to create a counter-force between base and carrier which counteracts the bearing or holding force.

Claims

1. A device for holding, positioning and/or moving an object (52), with a base (30) and with a carrier (50) movable relative to the base (30), at least one magnetic bearing (10, 100, 200) for generating a bearing or holding force (Hv, Hh) between the base (30) and the carrier (50), wherein the carrier (50) is contactlessly supported on the base (30) via the magnetic bearing (10, 100, 200), at least one drive (40; 140) contactlessly acting between the base (30) and the carrier (50) for a displacement of the carrier (50) along the base (30) in at least one transport direction (T), wherein the drive (40; 140) comprises a linear motor (38) with at least one slider (41; 141) and one stator (43; 143), which are arranged on the base (30) and on the carrier (50) and which, aside from a displacement force (V) acting along the transport direction (T), are configured to create a counter-force (G) between the base (30) and the carrier (50) which counteracts the bearing or holding force (Hv, Hh).

2. The device according to claim 1, wherein the at least one magnetic bearing (10, 100, 200) is configured as an actively controllable magnetic bearing (10, 100, 200) and comprises an electrically controllable electromagnet (12; 112) interacting magnetically with a counter-piece (18; 118) as well as a distance sensor (20, 120) and an electronic unit (15; 115) coupled therewith and configured to adjust a predetermined relative position of the base (30) and the carrier (50).

3. The device according to any one of the preceding claims, wherein at least one magnetic bearing (10) is configured as a vertical magnetic bearing (10) for generating a vertical holding force (Hv) counteracting the weight force of the carrier (50).

4. The device according to any one of the preceding claims, wherein at least one magnetic bearing (100, 200) is configured as a horizontal magnetic bearing for generating a holding force (Hh) acting horizontally between the base (30) and the carrier (50).

5. The device according to claim 4, wherein the horizontal magnetic bearing (100) comprises at least one electromagnet (112) arranged on the base (30) or on the carrier (50), which cooperates with a counter-piece (118) arranged on the carrier (50) or on the base (30) for the displacement of the carrier (50) in the transverse direction (Q).

6. The device according to claim 5, wherein the counter-piece (118) cooperating with the horizontal magnetic bearing (100) comprises at least one row of permanent magnets (118a, 118b) poled in an alternating manner and arranged on the carrier (50) or on the base (30), which permanent magnets are spaced apart from one another in a transverse direction (Q) obliquely or normal to the transport direction (T).

7. The device according to any one of claims 4 to 6, wherein the horizontal magnetic bearing (100, 200) interacts magnetically with an upper side (51) or an underside (53) of the carrier (50).

8. The device according to any one of the preceding claims, wherein the at least one magnetic bearing (10, 100, 200) and the drive (40; 140) interact magnetically with mutually opposite sides (51, 53, 55, 57) of the carrier (50).

9. The device according to any one of the preceding claims, wherein the base (30) comprises a plurality of magnetic bearings (10, 100, 200) spaced apart from one another in the transport direction (T) or in the transverse direction (Q), which magnetic bearings successively enter magnetically into an operative connection with at least one counter-piece (18; 118; 218) arranged on the carrier (50) for moving the carrier (50) along the base (30) in the transport direction (T) or in the transverse direction (Q).

10. The device according to any one of the preceding claims, wherein the base (30) comprises at least two transport paths (31; 131) running normal or obliquely to one another in the transport direction (T) and in the transverse direction (Q), with a plurality of magnetic bearings (10, 100, 200) in each case, wherein the transport paths (31; 131) adjoin one another in an intersection region (32).

11. The device according to claim 10, wherein at least two differently aligned sliders (41; 141) or stators (43; 143) of two drives (40; 140) are arranged on the carrier (50), one whereof is configured for moving the carrier (50) relative to the base (30) in the transport direction (T) and the other whereof is configured for moving the carrier (50) relative to the base (30) in the transverse direction (Q).

12. The device according to any one of preceding claim 10 or 11, wherein at least two sliders (41, 141) or stators (43, 143) aligned in parallel with one another are arranged on the carrier (50) at a predetermined minimum distance (DT, DQ) from one another in the transport direction (T) or in the transverse direction (Q).

13. The device according to any one of preceding claims 10 to 12, wherein each of the transport paths (31, 131) comprises stators (43; 143) or sliders (41; 141) spaced apart from one another in the transport direction (T) or in the transverse direction (Q), wherein the sliders (41; 141) or stators (43; 143) of one transport path (31) are arranged at a level of the intermediate spaces (3, 103) between the sliders (41; 141) or stators (43; 143) of the respective other transport path (131).

14. The device according to any one of preceding claims 11 to 13, wherein, in the intersection region (32), a pair, corresponding with each other, of sliders (41; 141) and stators (43; 143) of the two drives (40, 140) arranged on the carrier (50) and on the base (30), which pair belongs to one of the transport paths (31), can be activated in alternation with a pair of sliders and stators (41; 141, 43, 143) of the respective other transport path (131).

15. The device according to any one of preceding claims 10 to 14, wherein, in the intersection region (32), at least two magnetic bearings (10, 100) assigned to one of the two transport paths (131) can be activated, while two further magnetic bearings (10, 200) assigned to the respective other transport path (131) can be correspondingly deactivated.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Further aims, features and advantageous embodiments of the invention are explained in the following description of examples of embodiment making reference to the figures. In the figures:

[0060] FIG. 1 shows a diagrammatic representation of a magnetic bearing provided with a control circuit,

[0061] FIG. 2 shows a diagrammatic representation of the functional principle of the device according to the invention with a drive, which apart from a driving force also generates a counter-force counteracting the bearing or holding force of the magnetic bearing,

[0062] FIG. 3 shows a development of the example of embodiment shown in FIG. 2 with two horizontal magnetic bearings,

[0063] FIG. 4 shows a further embodiment with two vertical magnetic bearings horizontally spaced apart, a horizontal magnetic bearing and with a drive arranged opposite the horizontal magnetic bearing,

[0064] FIG. 5 shows a further embodiment of the device according to the invention, wherein the horizontal magnetic bearing is arranged outside the carrier,

[0065] FIG. 6 shows a diagrammatic cross-sectional representation of the drive constituted as a linear motor,

[0066] FIG. 7 shows a plan view of a slider of a horizontal magnetic bearing,

[0067] FIG. 8 shows a cross-section through an embodiment of a horizontal magnetic bearing,

[0068] FIG. 9 shows a plan view of the device according to the invention with a base elongated in the transport direction,

[0069] FIG. 10 shows a diagrammatic representation of the sliders of two drives acting in different directions, said sliders being arranged at the underside of the carrier,

[0070] FIG. 11 shows a plan view of two different kinds of counter-pieces at the upper side of the carrier, which cooperate with horizontal magnetic bearings acting in different horizontal directions,

[0071] FIG. 12 shows a diagrammatic representation of two transport paths running at right angles to one another with a carrier located in an intersection region,

[0072] FIG. 13 shows a diagrammatic representation of a configuration of transport paths and traversing or displacement directions for the carrier resulting therefrom and

[0073] FIG. 14 shows a further embodiment of different transport paths together with traversing or displacement possibilities resulting therefrom for the carrier supported contactless on the base.

[0074] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

[0075] FIGS. 4 and 9 show in a simplified and diagrammatic representation a device 1 according to the invention for holding, positioning and/or moving an object 52, which is arranged on a carrier 50. Device 1 can be configured for example as a wafer stage or as a transport system for the vacuum coating of displays. Device 1 comprises a fixed base 30, in the present case in the form of at least two guide rails, which extend in the representation according to FIG. 9 in transport direction (T) or in the z-direction.

[0076] For the contactless bearing and for the contactless transport of carrier 50 on base 30, a plurality of magnetic bearings 10 spaced apart from one another in the transport direction and aligned in the transport direction and lying behind one another in a row are provided in transport direction (T) on the base 30. Magnetic bearings 10 provided in the present case at the, related to the transport direction (T), left-hand and right-hand lateral edges of carrier 50 serve for the contactless bearing of carrier 50 on the stationary or fixed base 30.

[0077] Furthermore, a plurality of discrete stators 43 of a drive 40 are arranged on the base 30 also in transport direction (T), which cooperate contactlessly with at least one slider 41 corresponding thereto on the carrier 50 in the manner of a linear motor 38. A linear motor 38 can be formed by base-side stators 43 and at least one or more carrier-side moving members (sliders 41), which linear motor exerts a displacement force (V) directed in the transport direction on carrier 50 during the operation of device 1. In this way, carrier 50 can be supported contactlessly on the base 30 and can also be moved contactless along the base.

[0078] The fundamental structure of a magnetic bearing 10 is shown in the cross-section of FIG. 2. The magnetic bearing 10 is arranged on the base side, i.e. on the stationary base 30. It comprises at least one electromagnet 12 with a coil 16 and with an iron core 14 or ferrite core. The free ends of the legs of iron core 14 constituted horseshoe-shaped are facing carrier 50. On the carrier 50, a counter-piece 18 interacting magnetically with the electromagnet 12 is arranged facing the magnetic bearing 10. The magnetic bearing 10 further comprises a distance sensor 20, which measures a distance 26 between the carrier 50 and the magnetic bearing 10 arranged on the base side. The counter-piece 18 can be constituted ferromagnetic or permanent-magnetic. It typically extends parallel to the base 30 or parallel to guide rails (not explicitly shown) of the base 30, along which the carrier 50 can be displaced in a contactless manner.

[0079] Distance sensor 20, electromagnet 12 and electronic unit 15 form a control circuit 11, which is shown separately and somewhat detailed in FIG. 1. Apart from distance sensor 26, control circuit 11 also comprises a setpoint generator 25, a controller 22, an amplifier 24 and electromagnet 12 acting as an electromagnetic stator. Instead of an electromagnet 12, other electromagnetic stators, for example bi-directionally acting Lorentz or plunger-coil stators, can in principle also be used for all magnetic bearings 10, 100, 200.

[0080] Control signals that can be generated by controller 22 are amplified by the amplifier 24 and accordingly fed to coil 16 to generate a holding force (H) acting on counter-piece 18. Distance sensor 20 is preferably arranged in the immediate vicinity of electromagnet 12 or the electromagnetic stator, said distance sensor permanently measuring a distance 26 from counter-piece 18 or carrier 50. Distance 26 determined by distance sensor 20 is fed in the form of a distance signal to setpoint generator 25. The setpoint value and the actual value are compared with one another in setpoint generator 25. Corresponding to the difference between the setpoint value and the actual value, a corresponding comparison signal is fed to controller 22, which generates therefrom a control signal provided for controlling electromagnet 12 and feeds said control signal to amplifier 24.

[0081] The amplified control signal fed to coil 16 is calculated and determined in such a way that a predetermined distance 26 between carrier 50 and base 30 is maintained, and that, in the event of deviations from the required distance, the force arising from the electromagnetic stator or electromagnet 12 for maintaining distance 26 is adapted dynamically.

[0082] The electronic components of magnetic bearing 10 are typically combined in a single electronic unit 15. All the electronic components, such as for example amplifier 24, controller 22 and setpoint generator 25, can at least be accommodated on a common printed circuit board, for example in the form of a single integrated switching circuit. The space requirement for the electronic unit and an accompanying cabling requirement can in this respect be reduced to a minimum.

[0083] Control circuit 11 can optionally also be provided with an acceleration or movement sensor 28 configured to determine excitation of oscillations of the base 30. The signals that can be generated by movement sensor 28 are typically fed to an oscillation damper 23, which can be integrated for example in controller 22. With a control 29 coupled with the setpoint generator 25, different required distances 26 between base 30 and carrier 50 can be adjusted in a targeted manner and as required.

[0084] A reference portion 19 can also be arranged on carrier 50, which is facing the distance sensor 20, and which, roughly related to transverse direction (Q), is arranged approximately overlapping, but at a vertical distance from, distance sensor 20 on carrier 50.

[0085] Magnetic bearing 10 represented diagrammatically in FIGS. 1 and 2 is configured as a vertical magnetic bearing. It generates a holding force (H), in particular a vertical holding force (Hv), which at least compensates for or applies the weight force of carrier 50 and an object 52 arranged thereon.

[0086] In the example of embodiment shown in FIGS. 2, 3 and 5, a drive 40 in the form of a linear motor 38 is provided at the underside of carrier 50. Linear motor 38 comprises here at least one or more sliders 41 arranged on carrier 50, which cooperate with stators 43 corresponding thereto, said stators being arranged on base 30, for the purpose of moving carrier 50 in transport direction (T). The specific geometrical shape of base 30 is not shown in the present case. It goes without saying that the components of the drive arranged on the base side, i.e. stators 43 and also magnetic bearings 10, are arranged stationary and immobile relative to one another along transport path 31 predetermined by base 30.

[0087] The structure of drive 40 is shown diagrammatically in FIGS. 6 and 7. Drive 40 provided in the manner of a linear motor 38 comprises permanent magnets 42a, 42b with alternating polarity arranged at regular intervals in transport direction (T) on carrier 50. Permanent magnet 42a is poled in the opposite direction to adjacent permanent magnet 42b. Permanent magnet 42a following the latter in the transport direction is poled in the same direction as the last but one permanent magnet 42a. The regular arrangement of magnets 42a, 42b poled in an alternating manner on carrier 50 forms an elongated slider 41, which can cooperate with an electrically controllable stator 43, which is arranged on base 30.

[0088] Stator 43 comprises an iron or ferrite core 44 provided with a plurality of legs, wherein a coil 45, 46, 47 is wound round every second or next but one leg in transport direction (T). Coils 45, 46, 47 form the three phases of stator 43 and an electric current can be applied to them alternately. The periodicity or the centre-to-centre distance of individual equidistantly arranged legs 44.1, 44.2, 44.3, 44.4, 44.5, 44.6 and 44.7 of iron core 44 is somewhat smaller than the centre-to-centre distance or the periodicity of permanent magnets 42a, 42b, 42a, 42b arranged in an alternating manner in transport direction (T). By alternately applying an electric current to individual coils 45, 46, 47, a displacement force (V) acting in transport direction (T) can thus be exerted on carrier 50 relative to base 30.

[0089] The use of permanent magnets 42a, 42b, which are typically arranged on a steel plate of carrier 50, in combination with slider 43 leads to an attractive counter-force (G) also being exerted on carrier 50 aside from a displacement force (V) in transport direction (T), said counter-force pointing vertically downwards in the examples of embodiment of FIGS. 2, 3 and 5. Drive 40 thus performs a dual function. On the one hand, it generates a displacement force (V) for moving carrier 50 in transport direction (T). On the other hand it generates a counter-Force (G) counteracting the holding force (H) of magnetic bearing 10. In this way, drive 40 can contribute to an improved transverse stabilisation of carrier 50 with respect to a transverse direction (Q), i.e. especially when counter-force (G) acts at right angles or obliquely to the holding force (H) of magnetic bearing 10.

[0090] It can be seen in the plan view according to FIG. 7 that permanent magnets 42a, 42b of slider 41 of linear motor 38, relative to transport direction (T), are not aligned exactly vertical, i.e. in the x-direction, but rather at a certain angle of inclination to the x-direction or transverse direction (Q). Slider 43, i.e. its iron core 44, can on the other hand be aligned corresponding to a rectangular imaginary outer contour 60 formed by permanent magnets 42a, 42b. The orientation of permanent magnets 42a, 42b inclined slightly with respect to transverse direction (Q) ensures that, when there is a translation movement of slider 41 with respect to stator 43, a counter-force (G) that is as homogeneous and constant as possible is generated. In terms of control technology, this proves to be advantageous for magnetic bearing or bearings 10, 100 lying opposite drive 40 during a movement of carrier 50 in transport direction (T).

[0091] Furthermore, and independently of the specific embodiment of slider 41 and stator 43 of drive 40, drive 40 can also, as shown in FIG. 5, be provided with a position sensor 48 and with a coding 49 corresponding thereto on the base and on carrier 50. Coding 49 extends in transport direction (T). It is preferably arranged on carrier 50 directly opposite a position sensor 48 corresponding thereto, said position sensor typically being located in the immediate vicinity of stators 43 of drive 40. The given actual position of carrier 50 in transport direction (T) can be determined with the coding 49 and the position sensor 48.

[0092] Any disturbances or disturbing forces acting laterally on the carrier can be compensated for much more easily by counter-force (G) acting for example downwards in the vertical direction on carrier 50. As a result of providing a counter-force (G) arising from drive 40, any disturbing influences occurring in the horizontal direction and in transverse direction (Q) have much smaller effects on an undesired movement of carrier 50 in transverse direction (Q).

[0093] This also has the advantage that the outlay for a lateral or transverse stabilisation for carrier 50 supported contactless on base 30 can be reduced. This enables a far more compact design and possibly also a more cost-effective implementation of device 1.

[0094] In FIG. 3, as a supplement to FIG. 2, two magnetic bearings 100 arranged at the left-hand and right-hand lateral edges of carrier 50 are provided. These bearings 100 are also arranged fixedly on base 30. They each cooperate with a lateral counter-piece 118 facing them, the latter in each being arranged at opposite sides of carrier 50 facing respective magnetic bearing 100. The mode of action and the structure of magnetic bearing 100 can be essentially identical or similar to that of magnetic bearing 10. Similar to the vertical bearing of carrier 50 via magnetic bearing 10 arranged above carrier 50, a lateral guidance or a transverse stabilisation of carrier 50 in transverse direction (Q) can take place via magnetic bearings 100 arranged at opposite sides of carrier 50. Although a row of horizontal magnetic bearings 100 provided for the lateral stabilisation is not explicitly shown in FIG. 9, they extend more or less in the same way as vertical magnetic bearings 100 represented there.

[0095] A plurality of horizontal magnetic bearings 100 spaced apart from one another in transport direction (T) are provided at the two opposite sides, in the present case both at left-hand side 55 and also at right-hand side 57, of carrier 50 for a lateral guidance of carrier 50. In the embodiment shown here in the present case with electromagnets 12, which can exert only an attractive force on carrier 50 or on its counter-pieces 118, a guidance of carrier 50 in transverse direction (Q) therefore requires horizontal magnetic bearings 100 arranged on both sides of carrier 50.

[0096] In the further embodiment according to FIG. 4, a horizontal magnetic bearing 100 is provided only on right-hand side 57 of carrier 50, while drive 40 is arranged at opposite left-hand side 55. In this example of embodiment, two vertical magnetic bearings 10 spaced apart from one another in transverse direction (Q) are also provided above carrier 50. Object 52 to be held on the carrier is located at underside 53 of carrier 50. In this example of embodiment of device 1, drive 40 generates a counter-force (G) acting in the horizontal direction, which counteracts the lateral holding force (Hh) of horizontal magnetic bearing 100 lying opposite.

[0097] For example, the mode of action of horizontal magnetic bearing 100 arranged at left-hand side 55 of carrier 50 in FIG. 3 can thus be completely replaced by drive 40. The saving of one of horizontal magnetic bearings 100 ultimately results through the arrangement shown in FIG. 4 and through the dual function of drive 40. The replacement of a horizontal magnetic bearing 100 by drive 40 arranged laterally along carrier 50 brings a considerable saving potential.

[0098] It should further be noted in this regard that FIGS. 2, 3, 4 and 5 can only reproduce by way of example a cross-section through the device shown diagrammatically in FIG. 9, and that all magnetic bearings 10, 100 shown in cross-section and drive components slider 41 and stator 43 are arranged in a regular or recurrently equidistant manner in transport direction (T), i.e. perpendicular to the plane of the paper of FIGS. 2, 3, 4.

[0099] The arrangement of two rows of individual magnetic bearings 10 running in parallel and spaced apart from one another in transverse direction (Q), as represented in FIGS. 9 and 12, does not necessarily have to be provided. For a vertical magnetic bearing, it is in principle sufficient if only a single vertical magnetic bearing 10 is provided in transverse direction (Q) and if a plurality of such magnetic bearings 10 are arranged in a row in transport direction (T), as is shown diagrammatically for example in FIGS. 2 and 3. In such an embodiment, carrier 50 is supported in a suspended manner virtually only pointwise on base 30. Any oscillations or swinging movements of carrier 50 in transverse direction (Q) can be compensated for or at least damped by the counter-force (G) arising from linear drive 38.

[0100] A further embodiment of a horizontal magnetic bearing 100 is shown in FIGS. 5 and 8. The latter comprises, in the same way as linear drive 38, an iron or ferrite core 114 provided with a plurality of legs 144.1, 144.2 and 144.3. A coil 116 is wound round a central leg 144.2. To that extent, iron core 114 and coil 116 form an electromagnet 112 which, like stator 43 of linear motor 38, cooperates with a counter-piece 118. Counter-piece 118 comprises, in the same way as slider 41, a plurality of, in the present case at least two or at least three, alternatingly polarised permanent magnets 118a, 118b, 118a, which in the embodiment shown in FIGS. 5 and 8 are arranged on carrier 50 spaced apart from one another in transverse direction (Q).

[0101] As described previously in respect of linear motor 38, a force directed in transverse direction (Q) from base 30 onto carrier 50 can be exerted by applying an electric current to coil 116. Horizontal magnetic bearing 100 shown in FIG. 8 differs in this respect from vertical magnetic bearing 10 not only with regard to its arrangement and mode of action, but also with regard to its structure.

[0102] The variant of embodiment of a horizontal magnetic bearing 100 shown in FIGS. 5 and 8 is advantageous in that magnetic bearing 100 acting in the horizontal direction or in transverse direction (Q) can also be arranged outside the lateral region of carrier 50 and thus for example above carrier 50. For example, horizontal magnetic bearing 100 can be arranged on the base between two vertical magnetic bearings spaced apart from one another in transverse direction (Q). Horizontal magnetic bearing 100 can also be provided with a position sensor 120, which can cooperate with a reference portion 119 arranged opposite on carrier 50 for the determination of the position in transverse direction (Q). Position sensor 120 as well as distance sensors 20 measuring in the vertical direction can be implemented optically, capacitively or also magnetically.

[0103] The embodiment of horizontal magnetic bearing 100 shown in FIG. 8 can admittedly bring about only comparatively little travel or a comparatively small movement of carrier 50 in transverse direction (Q). On account of counter-force (G) arising from drive 40, which in the example of embodiment according to FIG. 5 acts against vertical holding force (Hv) of the two vertical magnetic bearings 10, such a small displacement of carrier 50 in transverse direction (Q) by the horizontal magnetic bearing 100 may already be sufficient.

[0104] The embodiment according to FIG. 5 is advantageous in that no structural measures at the side of carrier 50 need to be provided for the transverse stabilisation and for the lateral guidance of carrier 50 in respect of transverse direction (Q). The freedom from barriers, so to speak, prevails to the left and right of carrier 50, so that, as a result of the bearing proposed here, the possibilities in principle for the moveability of the carrier both in transport direction (T) and also in transverse direction (Q) are now in principle provided.

[0105] Finally, the base can thus provide a plurality of differently orientated transport paths 31, 131, along which magnetic bearings 10, 100 provided for the corresponding movement of carrier 50 are arranged. For example, the most diverse transport paths 31 and 131, as shown in FIGS. 13 and 14, are conceivable, wherein transport paths 31 extend in transport direction (T) and transport paths 131 extend in transverse direction (Q). Transport paths 31, 131 are typically orientated as right angles to one another in the horizontal plane. In this regard, FIGS. 13 and 14 show a plan view from above.

[0106] Individual transport paths 31, 131 do not necessarily have to comprise two parallel rows of magnetic bearings 10 spaced apart in transport direction (T) or transverse direction (Q), as is shown for example in FIG. 9. A transport path 31 can in principle also be formed by an individual bearing rail with only a single row of discrete magnetic bearings 10 spaced apart from one another in transport direction (T) or transverse direction (Q), as is indicated for example in FIG. 2 or FIG. 3. A single-row vertical bearing is suitable in particular for a suspended arrangement and bearing of carrier 50 on base 30.

[0107] A left-hand transport path 31a is shown in FIG. 13, which extends in transport direction (T), and which in an intersection region 32a adjoins a further transport path 131 running at right angles thereto. Located at an end of transport path 131 facing away from intersection region 32a is a further intersection region 32b, in which transport path 131 again changes over into a further transport path 31b extending in transport direction (T).

[0108] In the embodiment according to FIG. 14, the two parallel transport paths 31a, 31b spaced apart from one another in transverse direction (Q) are connected to one another by two transport paths 131a, 131b spaced apart from one another in transport direction (T). A total of four intersection regions 32a, 32b, 32c, 32d results. Accordingly, a carrier 50 can be moved almost arbitrarily between intersection regions 32a, 32b, 32c, 32d along one of transport paths 31a, 31b, 131a, 131b in each case.

[0109] In FIG. 12, one of intersection regions 32 is represented somewhat enlarged, but diagrammatically simplified. Thus, a plurality of stators 43 of drive 40 spaced apart from one another in transport direction (T) are arranged on base 30 along a transport path 31 extending in transport direction (T), which stators each cooperate with sliders 41 of carrier 50 provided correspondingly at underside 53 of carrier 50. Intermediate spaces 3 are provided between individual stators 43 arranged on the base side. Two transport paths 31, 131 orientated at right angles to one another intersect in intersection region 32, wherein second transport path 131 runs in transverse direction (Q).

[0110] Transport path 131 is also provided on the carrier side with stators 143 of a further drive 140. Intermediate spaces 103 are also provided between stators 143 of further drive 140, which stators are arranged offset and spaced apart in transverse direction (Q). Individual stators 43, 143 of the two drives 40, 140 are arranged in intersection region 32 in such a way that an imaginary connecting line of all stators 43 of first transport path 31 runs in an intermediate space 103 between two stators 143 of drive 140 which follow one another in transverse direction (Q).

[0111] Conversely, provision is also made such that an imaginary connecting line of all stators 143 of drive 140 runs through an intermediate space 3 between stators 43 of drive 40 which are adjacent in transport direction (T).

[0112] In the centre of intersection region 32, intermediate spaces 3, 103 of the two transport paths 31, 131 possibly come to lie overlapping at least in sections.

[0113] Corresponding to the orientation and arrangement of stators 43, 143 of the two drives 40, 140, corresponding sliders 41, 141 are provided at the underside of carrier 50, which sliders each comprise previously described permanent magnets 42a, 42b and 142a, 142b arranged in an alternating manner. The orientation of permanent magnets 42a, 42b of slider 41 is rotated through 90 with respect to the orientation of permanent magnets 142a, 142b of slider 141 of drive 140. In addition, sliders 41, 141 are arranged beside one another and free from overlap at underside 53 of carrier 50.

[0114] At least two sliders 41 of a drive 40 should be arranged spaced apart from one another at underside 53 of carrier 50. Two sliders 141 of a drive 140 are arranged on carrier 50 spaced apart from one another at a minimum distance DQ in transverse direction (Q). The same applies to sliders 41 of other drive 40 lying in parallel with one another. The latter are arranged on carrier 50 spaced apart from one another by a minimum distance DT in transport direction (T).

[0115] In this way, a configuration in intersection region 32 indicated diagrammatically in FIG. 12 can be obtained, wherein sliders and stators 41, 43 of a drive 40 and also stators and sliders 141, 143 of other drive 140 come to lie geometrically overlapping one another. In order that carrier 50 arrives in intersection region 32 coming for example from the left from transverse direction (Q), an activation of stators 143 of drive 140 is required, which runs along second transport path 131. Upon reaching a position in intersection region 32, drive 140 can be stopped. Stators 143 of drive 140 can then be deactivated and stators 43 of other drive 40 can be activated. Carrier 50, proceeding from intersection region 32, can thus be moved along first transport path 31.

[0116] It goes without saying that, corresponding to FIG. 9, transport paths 31, 131 are each also provided with a row of a vertical magnetic bearings 10, which are arranged on the base at regular intervals along respective transport paths 31, 131 and are activated as required corresponding to the movement of carrier 50 relative to the base.

[0117] Finally, FIG. 11 also shows by way of example that individual counter-pieces 118, 218 of two different horizontal magnetic bearings 100, 200 are arranged at upper side 51 of carrier 50. Counter-pieces 118 spaced apart from one another on carrier 50 in transport direction (T) each comprise two or more permanent magnets 118a, 118b, which are spaced apart from one another in transverse direction (Q) and the longitudinal alignment whereof runs essentially parallel to transport direction (T). The two counter-pieces 118 arranged on carrier 50 at the front and at the rear in transport direction (T) each cooperate with horizontal magnetic bearings 100, which are arranged on base 30 at regular intervals in transport direction (T), and which can provide a horizontal holding force (Hh) exerted on carrier 50 in transverse direction (Q).

[0118] The two further counter-pieces 218 arranged on carrier 50 at the front and at the rear in transverse direction (Q), on the other hand, cooperate with horizontal magnetic bearings 200, which are arranged on base 30 spaced apart at regular intervals in transverse direction (Q) along transport path 131, and which can provide a holding force (Hh) acting on the carrier in transport direction (T). Accordingly, permanent magnets 118a, 118b are arranged on carrier 50 also rotated through 90 with respect to permanent magnets 218a, 218b of counter-pieces 218. Counter-pieces 118, 218, which in the present case are arranged at upper side 51 of the carrier, can, in the same way as sliders 41, 141 provided at the underside, come to lie geometrically overlapping with corresponding horizontal magnetic bearings 100, 200 in the intersection region of two transport paths 31, 131.

[0119] Insofar as a change in direction is provided for carrier 50, horizontal magnetic bearings 100 assigned to transport path 31 for example have to be deactivated, while horizontal magnetic bearings 200 assigned to other transport path 131 have to be activated.

[0120] The same is of course also to be provided for vertical magnetic bearings 10. If vertical magnetic bearings 10 of the one transport path 31 are configured for the most part identical to those of the other transport path 131, it may however be sufficient twice if double the number of vertical magnetic bearings 10 of the two transport paths 31, 131 is not provided in intersection region 32 itself. In the course of a change in direction of the movement of the carrier in intersection region 52, it may be sufficient if only vertical magnetic bearings 10 of first and/or second transport path 31, 131 are always activated as required as soon as carrier 50 leaves intersection region 32 and arrives in the area of action of magnetic bearings 10, which belong solely to one of transport paths 31, 131.