KR940001608B1 - Positioning drive comprising pre-stressed contactless bearings - Google Patents

Abstract

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Description

Positioning device with prestressed contactless bearings

1 is a perspective view of a first embodiment of a positioning device.

2 is a side view of the positioning device shown in FIG.

3 is a plan view of the positioning device of FIG. 1 after rotation of the carrier about the Z axis.

4 is a plan view of a second embodiment of a positioning device.

5 is a plan view of a third embodiment of a positioning device.

6 is a longitudinal sectional view of a part of the positioning device shown in FIG.

7 is a plan view of a part of the sixth degree positioning device from the first side.

8 is a plan view of a part of the sixth degree positioning device from the second side.

9 is a perspective view of the trust and tension bearing with respect to the coordinate direction of the positioning device.

10 is a graph showing the principle of operation of trust and tension bearings.

11 is a bottom perspective view of the carrier drawn on a scale smaller than the scales of FIGS. 6, 7 and 8;

12 is a longitudinal sectional view of a translation drive for a positioning device.

* Explanation of symbols for main parts of the drawings

1: flat table 5: carrier

11, 13, 15: Translation drive body 21, 23, 25: Straight rod

27, 29, 31: support legs 33, 35, 37: permanent magnet

39, 41: magnet yoke 49: plate

77: magnet 79, 83, 85: magnet yoke

109: axis 111, 113: pressure roller

131: measuring device

The present invention includes a horizontal plate carrier which is slidably supported on a flat table and which can be displaced in two orthogonal coordinate directions, the first translational drive being connected to the carrier for applying a compressive force to the carrier in a first coordinate direction, A second translational drive connected to the carrier for applying a compressive force to the carrier in a second coordinate direction perpendicular to the coordinate direction, the positioning being capable of acting on one horizontal plane by the force applied to the carrier by the first and second drives Relates to a device. In a known positioning device as described in US Pat. No. 3466514, the translational drive connected to the carrier is constituted by a screw spindle, on the opposite side of which a spring load plunger is arranged. The direction of motion of the screw spindle and plunger coincides with each other. A relatively high frictional pressure contact exists between the end of the screw spindle and the end of the plunger rod connected to the plunger on one side and the carrier on the other. This friction is undesirable due to the hysteresis accompanying it, especially if the carrier must perform very small displacements in the micron and submicron ranges.

It is an object of the present invention to provide a positioning device for overcoming the above disadvantages.

For this purpose, in the present invention, the first drive is connected to the carrier in a contactless manner by means of a first horizontal actuating static thrust and a tension bearing via a viscous medium, and the second drive is second horizontal actuated through the viscous medium. Connected to the carrier in a contactless manner by means of thrust and tension bearings, the first and second thrust and tension bearings having a greater force than the maximum tensile force between the first and second drives on one side and the carrier on the other It characterized in that the pre-stress in the first and second coordinate direction.

The use of pre-stressed contactless bearings as a connecting means between the drive and the carrier eliminates almost all the amount of friction between the drive and the carrier (only very small viscous friction remains) and thus the hysteresis problem is avoided. The pre-stress state of the contactless bearings allows the carrier to exert a tensile force on the carrier and thus, in effect, thrust and tension bearings are formed. Bearings have a dual function because of their role as guides and connections.

British patent application 2060332 describes a positioning device comprising a vertical actuating air static pressure thrust bearing that can be prestressed by a spring. However, these thrust bearings serve for horizontal guidance of the carrier on the table. The connection of the spindle drive to the carrier is by pivot.

In a particular embodiment of the positioning device of the present invention in which the carrier can also perform rotation about a vertical axis in addition to translational movement in two coordinate directions, connected to the carrier for applying compressive and tensile forces to the carrier in a direction parallel to the second coordinate direction. A third translational drive is provided, wherein each of the first, second and third drives can pivot about a vertical axis with respect to the carrier.

In another embodiment of the positioning device, in which the pre-stress of the three bearings is to be obtained structurally simply, the first, second and third bearings are characterized by being prestressed by the permanent magnet.

In a preferred embodiment of the positioning device in which the load fluctuations lead to relatively small fluctuations in the bearing capacity, a part of the magnet yoke corresponding to the permanent magnet is characterized by being in a state of magnetic saturation.

In another embodiment of the positioning device suitable for use in the control room, the viscous medium is characterized by air.

In another embodiment of the positioning device with a relatively simple arrangement of permanent magnets, the second and third bearings are characterized by being prestressed by a plurality of permanent magnets which act in common to both bearings arranged in the carrier.

In another embodiment of the positioning device, in which the carrier has a relatively high degree of strength with respect to rotation about the vertical axis, the second and third bearings are beam type capable of pivoting about the second and third drives around the vertical axis. It is characterized by being connected to each other by a guide, the first drive being pivotable about a vertical axis with respect to the carrier.

The present invention will be described in more detail with reference to the drawings.

The first embodiment of the positioning device shown in FIG. 1 includes a fixedly arranged flat table 1 in the form of a rectangular parallel plate, the side of which is located in a horizontal plane. The rectangular plate-shaped carrier 5 is slidably supported on the upper surface 3 of the table 1 by four (multiple) vertical actuating air static pressure thrust bearings 7, the bearing being near the corners of the carrier 5. On the carrier 5 an object 9 to be positioned is arranged, which can be fixed on the carrier, for example by means of vacuum suction means, in the form of a plate. For example, the object 9 may be a wafer of semiconductor material used in semiconductor technology. The carrier 5 can be displaced in the primary coordinate direction X by the so-called linear translation drive 11, while it can be displaced in the secondary coordinate direction Y by a similar translation drive 13. At the same time, a third translational drive 15 similar to the drives 11, 13 serves to rotate the carrier 5 at an angle Ψ _z around the Z axis, which is shown by the coordinate system in FIG. 1. The XY plane is a horizontal plane, on which the top surface of the object 9 should be placed. The translational movement in the X and Y directions and the rotation around the Z axis can be made independently or simultaneously, for example by computer control of the drives 11, 13, 15. Such a drive will be described in more detail in FIG. In the present case, the work point P on the upper surface of the object 9 should coincide with the vertical optical axis 17 of the optical device 19 (see FIG. 2) for exposing the photosensitive layer on the wafer 9. . To this end, the translational motion in the X and Y directions and the rotation Ψ _z around the Z axis can be determined by the method described in US Pat. No. 3466514.

The drives 11, 13, 15 have straight rods 21, 23, 25 and the rods can perform translation in the X, Y and Y 'directions, respectively, and the Y5 "direction is parallel to the Y direction. The rotation Ψ _z can be obtained by displacing the rods 23, 25 to different lengths within a given period by the drive body 15. The rods 21, 23, 25 are shown in FIG. Each of the supporting legs 27, 29 and 31 is supported feet fixed to the rod by a pivot which will be described in more detail.The supporting legs 27 are part of a thrust and tension bearing that exerts compressive and tensile forces in the X direction, respectively. The support legs 29 and 31 are each provided with a part of the thrust bearing and the tension bearing which respectively apply compressive and tensile forces in the Y direction and the Y 'direction, respectively. And tensile bearings are the same and at 6, 7, 8 and 10 degrees On the support leg 27 (also also on the support legs 29, 31) three rectangular plate-shaped permanent magnets 33, 35, 37 are arranged, which are two rectangular plate magnet yokes of good magnetic conducting material. Separated from each other by (39, 41) The assembly of the permanent magnet and the magnet yoke is located in a box-shaped holder 43 made of a material having poor magnetic conduction, such as aluminum, for example. Separated by another two rectangular plate magnet yokes 45, 47. In this case, the permanent magnets are samarium-cobalt magnets, and all of the magnet yokes are of mild steel, opposite the permanent magnets 33, 35, 37. The plate 49 of a good magnetic conducting material, such as, for example, chromium steel, is arranged in the carrier 5. The plate 49 forms a second part of the thrust and tension bearing, respectively. ) Is magnetized in the Z direction. Is fixed to a rectangular block of aluminum 51. The block 51 and the circular plate 53 is installed formed on, which is manufactured of steel in one piece with a relatively short round wire 55 and the cylinder block 57. The rod 21 is provided with a flange 59 for receiving a screw 61 screwed to the block 57.

The flange 59 is secured to a cylindrical sleeve 63 formed of an annular diaphragm 65 with a thick circular magnetic field 67 screwed to the plate 53. The sleeve 63, the diaphragm 65 and the magnetic field 67 are integrally made of steel. The diaphragm 65 pivots with the wire 55, whereby the support leg 27 is inclined in a vertical plane (plane of FIG. 6) and a horizontal plane (perpendicular to the plane of FIG. 6) with respect to the flange 59. Can be. As such, the coupling between the support leg 27 and the flange 59 is strong against torsion, which means that a great resistance is provided to the rotation of the support leg 27 about the X axis. The block 51 is provided with a conduit 69 connected to an extruded air source (not shown) for supplying air to the air gap between the support leg 27 and the plate 49 and the carrier 5. For this purpose, conduit 69 is connected to two lateral conduits 71, 73 and the lateral conduits are located on both sides of the magnet assembly (FIG. 9). 2 schematically shows the connection of the support leg 27 and the rod 21 of the support leg 27 (only one magnet is shown). Thus, the areas of air bearing and magnetic prestress are separated from each other. The support legs 27, 29, 31 form thrust and tension bearings, respectively, with the corresponding plate 49 and the associated air gaps, which are capable of transferring extrusion and tensile forces from the rods 21, 23, 25 to the carrier 5. Can be. Typically viscous contactless bearings can only transmit compressive forces. However, the pneumatic hydrodynamic bearings of the present disclosure can also transmit tensile forces. This is due to the fact that the bearings are pre-stressed magnetically by the permanent magnets 33, 35, 37. The magnetic pretension must be greater than the maximum tensile force exerted by the rod 21 on the carrier 5.

The tensile force at the rods 21 is twice the tensile force at each rod 23, 25. The maximum tensile force is mainly determined by the acceleration and deceleration forces required for the translational and rotational movement of the carrier 5, respectively. The minimum possible mass of the carrier 5 and the object 9 is aimed at. In order to obtain a bearing with optimum characteristics, it is desirable to select the magnetic prestress stress such that the least possible variation of the size of the air gap occurs with the change of the bearing rod in order to obtain the bearing with optimum rigidity. The optimization of the bearing is described in FIG. 10, where the size of the air gap Ha is indicated on the transverse axis and the bearing capacity W and the magnetic attraction force F on the longitudinal axis.

로 특징지워지고 베어링 능력치 W₁및 W₂사이에 위치한다. 작업점 R과 관련된 베어링 능력은 W_R이다. 그와 같은 특징을 가지는 공기 베어링이 통상적이다. 작업점 R에서 작동되어야 한다면 공기 베어링에 WR과 같은 힘으로 부하하는 것이 필요하다. 본원의 경우, 이러한 부하는 자기 예비 인장력 F_V=W_R에 의해 얻어지고, 이것은 로드(21)에서의 최대로 생기는 인장력 및 압출력보다 역시 크다. 따라서, 베어링의 최대 부하는 자기 예비 인장력 FV와 최대 압축력과의 합이고, 반면 베어링의 최소 부하는 예비 인장력 F_V에서 최대 인장력을 뺀 것이다. 양호하게는 최대 부하는 W₂보다 작게 선택되고 최소 부하는 W₁보다 크게 선택된다. 점 R에 해당하는 자기 예비 인장력을 얻기 위하여 자기 인력 F의 곡선 Ⅱ(곡선 Ⅱ의 직선 부분만이 도시되어 있음)가 점 R과 일치하는 베어링 능력 W의 곡선Ⅰ과의 교차점을 가질 것이 필요하다. 일반적으로 자기 예비 인장력 F_V는 공기 갭 Ha max-Ha min(Hm＞Ha max)의 영역 외측에 위치하는 자기 갭 Hm에 해당하기 때문에, 곡선Ⅰ 및 Ⅱ의 교차점이 작업점으로 선택되는 점 R과 일치하도록 특수한 단계가 취해져야 한다. 이러한 단계는 공기 갭 Ha에 S양만큼 부과한 자기 갭 Hm이 사용되는데 있다. 제10도에 상세히 도시된 바와같이, 이것은 지지다리(27)에서의 공기 갭으로부터 거리 S로 자석(33, 35, 37)을 배치하거나 또는 자기적으로 공가와 같이 작동하는 층(75)을 가진 캐리어(5)의 관련면을 제공함으로써 달성된다. 이때 층(75)은 자기 전도판(49)을 덮고 있다.In Figure 10, curve I represents the bearing's capacity. Assume that work point R is located in the middle of the region of curve I, which is an almost constant intensity

And is located between the bearing capabilities W ₁ and W ₂ . The bearing capacity associated with work point R is W _R. Air bearings with such features are common. If it is to be operated at work point R, it is necessary to load the air bearing with the same force as WR. In the case of the present application, this load is obtained by the magnetic pre-tension force F _V = W _R , which is also greater than the maximum occurring tensile and extrusion forces in the rod 21. Therefore, the maximum load of the bearing is the sum of the magnetic pre-tension force FV and the maximum compressive force, while the minimum load of the bearing is the pre-tension force F _V minus the maximum tensile force. Preferably the maximum load is selected smaller than W ₂ and the minimum load is selected larger than W ₁ . It is necessary for curve II of magnetic attraction force F (only the linear part of curve II is shown) to have an intersection with curve I of bearing capacity W that coincides with point R in order to obtain the magnetic pretension force corresponding to point R. In general, since the magnetic preliminary tensile force F _V corresponds to the magnetic gap Hm located outside the region of the air gap Ha max-Ha min (Hm> Ha max), the intersection of curves I and II is selected as the work point R and Special steps should be taken to match. This step is to use the magnetic gap Hm imposed by the amount of S on the air gap Ha. As shown in detail in FIG. 10, it may be arranged to place the magnets 33, 35, 37 at a distance S from the air gap in the support leg 27 or to have a layer 75 magnetically acting like a cantilever. By providing the associated surface of the carrier 5. At this time, the layer 75 covers the magnetic conductive plate 49.

를 목표로 하므로 부하 변동은 공기 갭의 크기와 그리고 변위될 물체의 위치에 가능한한 최소의 영향을 미친다.In the present application, the magnets 33, 35, 37 are arranged on the support legs 27, 29, 31 with a distance S away from the air gap. In the detailed view of the magnet arrangement shown in FIG. 10 this is shown in dashed lines. The carrier 5 is supported on the table 1 in the vertical direction Z by the special layer 87 as will be described in detail later. The relatively large strength of the air bearings in the relatively large area of the air gap (Ha max-Ha min) as arranged so that a very accurate displacement is performed

As a result, load fluctuations have the smallest possible influence on the size of the air gap and the position of the object to be displaced.

In FIG. 10, it can be seen that the linear relationship between the magnetic attraction force F and the magnetic gap Hm operates in the region of the magnetic gap in which it exists. Thus, the part of curve II used is in fact a straight line, which is roughly the case when the air gap is large enough and the value of the magnetic saturation of the magnet yokes 39, 41, 45, 47 is relatively high. However, materials for magnetic yokes 39, 41, 45, 47 have relatively low magnetic saturation values such that the magnet yokes 39, 41, 45, 47 are magnetically saturated in the region Ha max-Ha min (e.g. Mild steel). The effect of magnetic saturation generation in the magnet yokes 39, 41, 45, 47 will be described with reference to curve III in FIG.

Assuming that the bearing load undergoes the variation ΔWα, the air gap Ha and the magnetic gap Mm change to ΔHa. The variation in the magnetic attraction force F corresponding to the amount ΔHa is the case of curves IIΔF _{II and} the cases of curves III, ΔF _III . It is evident that Δ _II is greater than ΔF _III due to the flatter slope of curve III in the relevant region of the air gap. _Due to the variation of the magnetic attraction forces F of the values ΔF _II and ΔF _III , the load W also changes to _{ΔW amII} and _{ΔW amIII ′} . Since curve _{ΔW amII} is greater than _{ΔW amIII ′ for} curve II, the threshold W ₂ will be reached earlier than for curve III with load variations exceeding ΔWa. This means that the region of optimum bearing strength W ₂ -W ₁ remains earlier in the unsaturated magnet yoke than in the saturated magnet yoke. It is preferable to select a magnet shape that fluctuates as shown in curve III. An ideal case occurs when curve III on the left of work point R approaches the line corresponding to the horizontal line via F _V = W _R. This line then forms the asymptote of curve III.

In the case of the rectangular carrier 5, the thrust bearing 7 can be arranged near the corner of the carrier as shown in FIG. 1 or shown in FIGS. 2, 6, 7, 8 and 11. It may be located near the center of the side of the carrier as shown. The thrust bearing 7 for supporting the carrier 5 in the Z direction is preferably arranged as shown in FIGS. 2, 6, 7, 8 and 11 to simplify the structure. Each of the four thrust bearings 7 consists of an assembly of nine samarium-cobalt permanent magnets 77 separated from one another by eight magnet yokes 79 of good magnetic conducting material such as mild steel. The assembly of nine magnets 77 is separated from the box-shaped holder 81 of poor magnetic conducting material such as aluminum by two magnet yokes 83 and 85 of mild steel. The magnet 77 and the magnet yoke 79, 83, 85 are plate-shaped and rectangular. The magnetization direction of the two magnet 77 assemblies extending parallel to the X direction is parallel to the X direction, and the magnetization direction of the two magnet 77 assemblies extending parallel to the Y direction is parallel to the Y direction (seventh) Degrees, 8 degrees and 11). However, this magnetization direction may be a direction rotated by 90 ° with respect to the above-described direction as shown in FIG. For example, the upper surface of the table 1 made of a weak magnetic material such as mild steel is covered with a replica layer 87. This replica layer 87 consists of an epoxy resin with a filler, such as aluminum oxide, which magnetically behaves like air (shown in detail in FIGS. 6 and 10). By the replica layer 87, the magnetic air gap is effectively enlarged by the amount S and thus Hm = Ha + S. As mentioned above, the curve of the magnetic attraction force F has an intersection with the curve of the bearing capacity W at the work point R. In addition, the replica layer 87 protects the carrier 5 of mild steel from corrosion. The very flat master plate allows the replica layer 87 to flatten during curing. This means that the upper surface of the table 1 need not be very flat. Delicate flatness is obtained in a simple and time-saving manner by one master plate for many carriers. In summary, this means that the replica layer 87 has three functions. Due to the fact that the table 1 is made of a weak magnetic material with low current magnetism, there is a risk of minor impact during the movement of the carrier 5 by the region with residual electricity induced by the magnet 77 in the table surface. Is reduced to a minimum. The carrier 5 is provided with a circumferential air conduit 89 connected to a compressed air source (not shown). The air conduit 89 has a plurality of lateral conduits 91, which are evenly distributed on the circumference of the carrier (FIGS. 6, 7 and 8 degrees) and between the carrier 5 and the table 1. Is opened to the air gap. As a result, an air bearing is obtained on most circumferences of the carrier 5. There is no lateral conduit 91 in the region of the magnet 77, whereby the air bearing and the region of magnetic prestress are separated from each other.

The air bearing 7 is magnetically prestressed with a force F _V which is significantly greater than the maximum load in the Z direction of the bearing. Preferably F _V is chosen such that the working point of the bearing is located again at point R in FIG. Therefore, in this case, the magnetic preliminary tensile force is not necessary when absorbing the tensile force. Structure of the carrier may be selected light as possible, with the result that the total load in the Z direction is made by the load of the carrier 5 and the object 9 is only a portion of the magnetic tensile force F _V. The same is taken into account for the variation in the load of the bearing 9 as already indicated in FIG. 10 for the Ha and Hm variations. The criterion is that the variation of Ha and Hm in the variation of the load should be as small as possible. It can be seen that the magnet shape in this case is preferably selected to produce magnetic saturation. For this purpose the material of the magnet yokes 79, 83, 85 should have a fairly low saturation.

In the second embodiment of the displacement arrangement shown in FIG. 2 there are only two coordinate directions X and Y, and the drive body in the third coordinate direction Y 'is omitted in this case. In addition, the rod 23 is strongly connected to the support leg 29 at the point 93. However, the rod 21 is pivotally connected to the support leg 24 in the same manner as the displacement arrangement shown in FIGS. 1, 2, 3 and 6 degrees. As a result, a small angle adjustment amount α can be obtained if alignment of the carrier 5 with respect to the table 1 is required. The small displacement of the rod 23 in the Y direction makes it possible to obtain such an angle adjustment amount α. This angle adjustment actually precedes the displacement that brings the object to the working point P as a preliminary adjustment or correction. The support legs 27 and 29 are also provided with permanent magnets, magnet yokes and air supply conduits, while the carrier 5 is provided with a magnetic conducting plate as described in the positioning device shown in FIG. A first positioning device shown in Figure 4 is within the scope rotates Ψ _z about the vertical Z-axis is not required to position the object.

The third embodiment of the positioning device shown in FIG. 5 belongs to the category that rotation Ψ _z around the vertical Z axis is possible. In this case, the rotation Ψ _z is obtained by the rods 23, 25. The support legs 27 have the same form as those of the first positioning device, while the support legs 29 and 31 are omitted. The rods 23, 25 are pivotally connected to the beam-shaped guides 95, which are longer than the distance between the rods and are made of a magnetically conductive material, for example mild steel. The connection between the rod 23 and the guide 95 is the same as the connection between the rod 21 and the support leg 27, while the connection between the rod 25 and the guide 95 is only a constant length of wire ( Since only 55 is included, guide 95 can pivot about rods 23 and 25. The carrier 5 accommodates two assemblies of permanent magnets 77. The magnet shape is the same as that described in the positioning device shown in FIG. In order to obtain a magnetic gap Hm larger than the air gap Ha ', the magnet 77 is arranged such that its end face is positioned with a distance S away from the air gap. Alternatively, the replica layer having a thickness S can be used. This layer is then provided on the side of the guide 95 facing the magnet. On the carrier 5 an object 9 is arranged, for example a circular semiconductor substrate, while the center P 'must coincide with the work point P. An advantage of the positioning device shown in FIG. 5 is that it is relatively strong against the rotation of the carrier 5 around the vertical Z axis. In addition, in this arrangement it is possible to carry out a relatively large displacement parallel to the X direction with a relatively small mass of the carrier 5.

In all the above-described positioning devices, the drive bodies 11, 13, and 15 to be described later with reference to FIG. 12 are used. The translational drive shown in FIG. 12 includes a direct current motor 97, which drives the shaft 109 through a flexible coupling 99 and a series of friction wheels 101, 103, 105, 107. Drive it. The rods 21, 23, 25 have two planes 115, 117 extending longitudinally on the same plane, respectively, and are loaded by two pairs of free rotating pressure rollers 111, 113 separated by a constant distance. , 23, 25 are pressed against the associated drive shaft 109 by planes 115, 117. The pressure rollers 111, 113 are inclined with respect to the vertical plane and are journaled in a block 119 provided by a spring (not shown) and actuated by the compression force 121. Rolling friction between the shaft 109 and the planes 115, 117 of the rods 21, 23, 25 improves the translational motion of the rods in the X, Y and Y 'directions. The rods 21, 23, 25 have strip-shaped measurement scales 123 extending in the X, Y and Y 'directions, respectively, which serve as light beams 125 projected by the mirror 127 and the lens 129. It has alternating regions that alternate with relatively strong or relatively weak reflectances. The reflected light beam is detected by a light detector disposed in the measuring device 131. The measurement signal thus obtained is processed in the electric servo loop and fed back to the electric motor 97. Since the optical measuring device mentioned above roughly is conventional, a detailed description thereof will be omitted. The measurement directions coincide with the X, Y and Y 'directions, respectively, so that so-called Abbe errors or slope errors are avoided.

In all the above-mentioned positioning devices, air of the gas bearing is used for the vertical actuating thrust bearing 7. However, liquid may also be used as a viscous medium in the thrust bearing 7. In such a case, it is necessary for the outflow liquid to be collected satisfactorily. Although liquid can essentially be used as a viscous medium for horizontal actuating thrust-tension bearings, gas is well used because of the relatively complex collection means required for the liquid. Vertical thrust bearings can also be replaced with accurate roller or bowl bearings, and sliding bearings are also possible. The pretension of a viscous contactless bearing can be obtained by weight, vacuum, spring or electromagnetic for vertical actuating thrust bearings and by vacuum, spring or electromagnetic for horizontal actuating thrust-tension bearings. In the case of electromagnetic pretension, the permanent magnet is replaced by an electromagnet with an excitation that can be controlled by a sensor that measures the size of the air gap. The magnetic attraction can then be controlled such that the excitation in the load of the air bearing or liquid bearing is fully compensated by the excitation adopted. The fluctuation of the magnetic attraction F is indicated by the dashed dashed line 1V in FIG. Conventional electromagnetic bearings that do not use a viscous medium generated from a pressure source do not fall within the scope of the present invention. Such electromagnetic bearings are dynamic in form, while the present invention employs static viscous bearings with an external pressure source.

Instead of an assembly of permanent magnets, a single permanent magnet can be used according to the invention for each rod 21, 23, 25. Essentially, it is also possible to use a single magnet for the vertical support of the carrier. The strength required for the inclination of the carrier 5 can be obtained more easily by several magnets or several assemblies of magnets. Although the present invention describes a translational drive or linear drive with friction coupling, other known linear drives may also be used. Such a linear drive may be, for example, a screw and nut drive or a drive with an axis guided by a roller or bowl. Essentially, a drive body can be used that allows the carrier 5 to be reciprocated in any reciprocating direction by the action of a force from one side of the carrier 5. Static viscous bearings with an external pressure source can be of different types with respect to the limitations used between the pressure source and the gas and liquid gaps, respectively. In particular, mention is made of the use of diaphragm compensated viscous bearings. Such bearings, well known in nature, can achieve a high degree of strength.

Claims (8)

A horizontal plate carrier 5 which is slidably supported on the flat table 1 and displaceable in two rectangular coordinate directions X and Y, and compresses the compressive force to the carrier 5 in the first coordinate direction X. A first translational drive 11 connected to the carrier 5 for application and a second connection to the carrier for applying a compressive force to the carrier 5 in a second coordinate direction Y perpendicular to the first coordinate direction X. In the positioning device having a translational drive 13, the force exerted on the carrier 5 by the first and second drives 11, 13 is to act in one horizontal plane, the first drive body. (11) is connected to the carrier (5) in a contactless manner by means of a first horizontal actuating static trust and tension bearing which is formed in part by a support leg (27) via a viscous medium, and the second drive (13) is To the second horizontal actuating thrust and tension bearing which is formed in part by the support legs 29 through the viscous medium. Connected to the carrier 5 in a contactless manner, the first and second trust and tension bearings being respectively between the first and second drives 11, 13 on one side and the carrier 5 on the other side. And prestressed in the first and second coordinate directions (X, Y) with a force greater than the maximum tensile force generated at. A third translational drive (15) according to claim 1, wherein said device has a third translational drive (15) connected to the carrier (5) for applying compressive and tensile forces to the carrier (5) in a direction (Y ') parallel to the second coordinate direction (Y). ), And each of the first, second and third drives (11, 13, 15) is pivotable about a vertical axis with respect to the carrier. 3. The third drive body (15) according to claim 2, wherein the third drive member (15) is connected to the carrier (5) by means of a third horizontal actuating static trust and tension bearing, which is formed in part by a support leg (31) via a viscous medium. The bearing is characterized in that the three bearings are prestressed in parallel to the second coordinate direction (Y) with a force greater than the maximum tensile force occurring between the third drive body (15) and the carrier (5). 4. Positioning device according to claim 3, characterized in that the first, second and third bearings are prestressed by permanent magnets (33, 35, 37). 5. A positioning device according to claim 4, wherein a part of the magnet yoke (39, 41, 45, 47) corresponding to the permanent magnet (33, 35, 37) is in a state of magnetic saturation. 5. A positioning device according to claim 4, wherein the viscous medium is air. 5. Positioning device according to claim 4, characterized in that the second and third bearings are prestressed by a plurality of permanent magnets (77) which act in common on both bearings arranged in the carrier (5). 8. The second and third bearings of claim 7 are connected to each other by beam guides 95 which can pivot about the second and third drives 13, 15 around the vertical axis, while Positioning device, characterized in that the drive body (11) can pivot about a vertical axis with respect to the carrier (5).

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