Abstract:
The present invention concerns a device for transporting substrates through vacuum chambers, especially coating machines with a substrate carrier on or at which the substrates can be arranged, wherein the substrate carrier has at least one guide rail which extends along at least one side of the substrate carrier, and wherein the guide rail is kept spaced apart from the substrate carrier by one or just a few spaced bearings.

Description:
PRIORITY 
     This application claims priority under 35 U.S.C. §119(a) to EP 06111908.7, filed Mar. 29, 2006, the entire disclosure of which is incorporated herein by reference for all purposes. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention refers to a device for the transport of substrates through vacuum chambers, especially coating machines with a substrate carrier, on or at which the substrate may be arranged, wherein the substrate carrier has at least one guide rail which extends along at least one side of the substrate carrier. 
     2. Prior Art 
     From CH 691 680 A5 and DE 297 15 535 U1 is known a transport device for work pieces in a vacuum machine in which the substrate carriers may be arranged for, especially, flat and large-surface substrates, such as glass panes on a corresponding plate-like, disk-like or frame-like substrate carrier, with the substrate carrier having permanent magnets at its upper side that interact with a magnetically soft U-shaped holder, which is also fitted with magnets, such that the substrate carrier is transported at its upper side without contact. Disclosure of the aforementioned documents is fully incorporated into the present disclosure by way of reference. 
     Although this solution already yields very good results, the arrangement of the magnetic rail at the residual substrate carrier, for example a carrier plate or a frame arrangement, leads to the problem that, in the case of large-surface substrates having a substrate carrier of certain dimensions, due to the differential heating of the parts, namely magnet guide rail on one hand and carrier on the other, especially in the case of cyclical repetitive heating, which is often the case in coating machines, the parts of the substrate carrier rub against each other. Moreover, through the stresses and strains of the large-surface substrates or substrate carriers during transport, undefined deformation is introduced, such as torsion of the whole carrier, bending of the plates etc, which can lead to further relative movement of the magnet guide rail and the substrate carrier on one hand and, on the other, to frictional contact with and grinding or bumping at the magnetic holder in which the substrate carrier with its magnet guide rail is normally guided in the machine without contact, such that, in some circumstances, not unsubstantial wear may be generated that can disadvantageously impact on the quality of the coatings performed therein. 
     BRIEF SUMMARY OF THE INVENTION 
     Technical Object 
     It is therefore the object of the present invention to remedy this problem and especially to achieve a reduction of contamination of a vacuum chamber by guiding the substrate carrier at its upper side. At the same time, the solution to be provided should be simple to realize and be reliable and cost efficient in use. 
     Technical Solution 
     This object is achieved with a device having the features of claim  1 . Advantageous embodiments are the object of the dependent claims. 
     In accordance with the present invention, the above object is achieved by arranging the guide rail at the substrate carrier such that it is held by one or several bearings spaced apart from the substrate carrier, such that, in the event of differential deformation of guide rail and the rest of the substrate carrier as a consequence of temperature and process influences, no mutual frictional surfaces or only slight or defined frictional surfaces are present, such that abrasion may be reduced or prevented. Additionally such a solution offers the possibility of allowing twisting or deformation or general movement of the substrate carrier, while, at the same time, the guide rail in the magnetic holder of the transport system may be moved un-deformed, such that no collisions occur between the substrate carrier or the guide rail and the other machine parts, especially no grinding of the guide rail at the counter rail in the magnetic transport or holding system. In this way, abrasion can also be substantially reduced or totally prevented. Moreover, this enables production inaccuracies to be compensated or larger production tolerances to be allowed. 
     In preferably flat, plate-like, disk-like and/or frame-like substrate carriers, on or at which large-surface, flat substrates, especially large-surface glass substrates, such as for display production or architectural glazing, may be arranged, the guide rail is preferably arranged along one longitudinal side of the substrate carrier in the longitudinal direction, with its being advantageous here to mount the guide rail in a central area at the substrate carrier, preferably via a single, central bearing. This has the advantage that no additional bearing movements need to be feared or taken into account. 
     In the arrangement of the central bearing, the arrangement region about the central axis of symmetry can be chosen in a wide range to suit the other requirements. A large central arrangement is, however, advantageous, as it facilitates uniform, symmetrical mounting of the guide rail. 
     The central bearing may be a fixed or movable bearing, especially a pivot bearing. 
     In the case of a fixed bearing, a stiff and rigid connection is made between guide rail and the rest of the substrate carrier, with differential movement or deformation of guide rail and the rest of the substrate carrier essentially executed or dissipated in these components. It has proved advantageous in this regard if especially the substrate carrier part, especially a corresponding frame part, connected to the fixed bearing is made from an elastic material in order that the differential deformation there may be facilitated. It has especially proven advantageous to provide a “soft”, thin metallic plate, such as an aluminum plate, with a thickness of approx 12 mm, which acts like a leaf spring. 
     Alternatively, the central bearing may also be a movable bearing, especially a pivot bearing, which facilitates a certain movement of guide rail relative to the rest of the substrate carrier by virtue of its bearing properties. Such a movable bearing may preferably be a pivot bearing whose rotation axis is in the plane of the substrate carrier and/or is essentially aligned perpendicularly to the side, especially the upper side, of the substrate carrier. Thus, the ends of the guide rail may be rotated relative to the ends of the rest of the substrate carrier or the substrate carrier plate. 
     Such a pivot bearing may preferably be made from a plastic material especially in the form of PEEK bearing blocks with a stainless steel shaft as the rotation axis. 
     Preferably, the central bearing may be the sole bearing. Admittedly, given corresponding dimensions of the substrate carrier, one or more side bearings, especially in the form of movable bearings, may be necessary. 
     Preferably, such a side movable bearing is formed as a ball or roller bearing, which facilitates movement of the ends of the guide rail perpendicularly to the substrate carrier plane, i.e. the rotation axis is aligned parallel with the longitudinal side of the substrate carrier. 
     Preferably, a device for limiting rotation or movement is provided between guide rail and substrate carrier, said device facilitating limitation of mutual movement of guide rail and substrate carrier towards each other. In this way, excessive movement or deformation of the individual parts is prevented from leading to collisions during transport of the substrate carrier in the vacuum machine. 
     A corresponding rotation or movement limiter may be designed as a separate part or be integrated into a corresponding bearing, especially side movable bearings. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Further advantages, characteristics and features of the present invention are apparent from the following detailed description of preferred embodiments. The drawings show in purely schematic form in 
         FIG. 1  a partial side view of a first substrate carrier; 
         FIG. 2  a three-dimensional view of a bearing of the guide rail of the substrate carrier from  FIG. 1 ; 
         FIG. 3  a plan view of the bearing from  FIG. 2 ; 
         FIG. 4  a cross-sectional view along the cross-section line A-A from  FIG. 3 ; 
         FIG. 5  a side view of the bearing from  FIGS. 2 to 4 ; 
         FIG. 6  a partial side view of a further substrate carrier; 
         FIG. 7  a three-dimensional view of the pivot bearing of the substrate carrier from  FIG. 6 ; 
         FIG. 8  a plan view of the pivot bearing from  FIG. 7 ; 
         FIG. 9  a cross-sectional view along the cross-section line A-A from  FIG. 8 ; 
         FIG. 10  a three-dimensional view of the roller bearing of the substrate carrier from  FIG. 6 ; 
         FIG. 11  a plan view of the roller bearing from  FIG. 10 ; 
         FIG. 12  a cross-sectional view of the roller bearing from  FIG. 11  along the cross-section line A-A; 
         FIG. 13  a side view of the roller bearing from  FIGS. 10 to 12 ; 
         FIG. 14  a partial side view of a further substrate carrier; 
         FIG. 15  a three-dimensional view of a movement limiter of the substrate carrier from  FIG. 14 ; 
         FIG. 16  a plan view of the movement limiter from  FIG. 15 ; and in 
         FIG. 17  a cross-sectional view of the movement limiter from  FIG. 16  along the cross-section line A-A; 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a partial side view of a substrate carrier  1  in accordance with the invention that is assembled from several frame parts  2  to  4  and can accommodate a substrate  5  in the centre. 
     The frame part  3  shown in the form of a longitudinal plate in the top of  FIG. 1  has at its centre a fixed bearing  6  above which at the upper longitudinal side of the substrate carrier  1  is arranged a guide rail  7 , which may have one or more magnets (not shown). By virtue of the fact that the guide rail  7  is spaced apart from the upper frame part  3  by the fixed bearing  6 , a gap  8  is created between the guide rail  3  and the substrate carrier  1  or the upper frame part  3 . This means that the free ends of the guide rail  7  can move relative to the substrate carrier  1  or the upper frame part  3 , without abrasion occurring between the guide rail  7  and the upper frame part  3 . In particular, the “soft” design of the upper frame part  3 , for example in the form of an aluminum plate, makes it possible for the substrate carrier  1  to twist relative to the guide rail  7 , without the possibility of particle abrasion occurring that could lead to a load on the vacuum chamber or interference with electrical or mechanical devices or the coating processes performed therein or the coatings applied therein. 
     The fixed bearing  6  is shown in more detail in  FIGS. 2 to 5 . 
       FIG. 2  is a three-dimensional illustration of the fixed bearing, whereas  FIG. 3  is a plan view and  FIG. 4  a cross-sectional view along the cross-section line A-A of  FIG. 3 .  FIG. 5  is a side view of the narrow side of the fixed bearing  6 . 
     As may be seen in  FIGS. 2 to 5 , the fixed bearing  6  has a bearing body  9  in which are provided bore holes or cutouts for accommodating screws  11  and  10  which may be screwed into the corresponding thread recesses or bore holes of the frame part  3  or the guide rail  7 . Consequently, a spaced and, at the same time, fixed and rigid connection can be achieved between the frame part  3  of the substrate carrier  1  and the guide rail  7 . 
       FIG. 6  shows a further embodiment of a substrate carrier  100  in accordance with the invention which also is assembled from frame parts  102  to  104  and can accommodate a substrate  105 . 
     The guide rail  107  is in turn connected via a central bearing  106  to the upper frame part  103 , with additionally further bearings  109  (side movable bearings) provided at the ends of the guide rail  107 . In this embodiment, too, the guide rail  107  is spaced apart from the frame part  103 , such that a gap  108  is formed between these parts that largely prevents abrasion in the event of movement by guide rail  107  and frame part  103  towards each other. 
     In the embodiment of the substrate carrier  100 , a pivot bearing  106  is provided as a central bearing which has two counter rotatable bearing bodies  112  and  115 , as shown in the three-dimensional drawing, plan view and cross-sectional view in  FIGS. 7 to 9 . 
     The two rotatable bearing bodies  112  and  115  may, for example, be made from a plastic, with in this case especially a plastic suitable for high-vacuum conditions, such as PEEK plastic, capable of being chosen. A shaft  114 , which may be formed for example from stainless steel, is provided for the rotatable connection between the bearing bodies  112  and  115 . 
     The two bearing bodies  112  and  115  are each arranged via screws  110  or  111  at the guide rail  107  or the upper frame part  103  of the substrate carrier  100 . 
     As is especially apparent from  FIG. 9 , at the shaft  114  can be provided a region  113  which, for example, through interaction with a corresponding transverse lug or a threaded bolt, serves as an axial mounting or lock for the upper bearing part. As for the rest, however, the spaced pivot bearing of the guide rail  107  from the upper frame part  103  facilitates low-friction rotation or twisting of the guide rail  107  relative to the rest of the substrate carrier  100 . 
     As is apparent from  FIG. 6 , in addition to the axial or central bearing  106  the ends of the guide rail  107  are mounted via roller bearings  109 , which facilitate movement of the ends of the guide rail  107  perpendicularly to the plane of the substrate carrier. Correspondingly, the rotation axis of the roller bearing  109  is also arranged parallel with the guide rail  107  or the longitudinal side of the substrate carrier  100 . 
       FIG. 10  is a three-dimensional view of the roller bearing  109 , wherein the bearing has two bearing bodies  116  and  117 , each of which is connected via screw connections  119  and  118  to the respective components, namely guide rail  107  and upper frame part  103  of the substrate carrier  100 . Between the bearing bodies  116  and  117  a rotatable roller  120  is provided which, as is particularly evident from  FIG. 12 , is rotatable about an axle shaft  121  and thus facilitates a movement of the upper bearing body  117  relative to the lower bearing body  116 . 
     As  FIGS. 10 to 13  show, the lower bearing body  116  is wider than the upper bearing body  117 , with bars  122  provided along the longitudinal sides at the lower bearing body  116 , said bars limiting the movement of the upper bearing body  117 . 
     Instead of a roller bearing, other bearings, such as ball bearings and the like, may be provided. 
       FIG. 14  is a partial side view, which is comparable to the views of  FIGS. 1 and 6 , and shows a third embodiment of a substrate carrier  200  in accordance with the invention, said carrier again being formed by frame parts  202 ,  203 ,  204 , which between them accommodate substrate  205 . In this embodiment, too, a pivot bearing  106  is provided centrally at the upper frame part  203 , said bearing being identical with the embodiment of  FIG. 6  and facilitating spaced rotatable mounting of the guide rail  207  from the upper frame part  203 , such that here again a gap  208  is formed between guide rail  207  and upper frame part  203  of the substrate carrier  200 . 
     Instead of the roller bearings  109  provided at the ends of the guide rail  107  in the embodiment of the substrate carrier  100 , the ends of the guide rail  207  shown in embodiment of the substrate carrier  200  in  FIG. 14  are provided with movement limiters  209 , which are shown in more detail in  FIGS. 15 to 17 .  FIG. 15  is a three-dimensional diagram of the movement limiter  209 , while  FIGS. 16 and 17  are a plan view ( FIG. 16 ) and a cross-sectional view along the cross-section A-A line of  FIG. 16  ( FIG. 17 ). 
     The movement limiter  209  has two limiter bodies  212  and  213  spaced apart from each other, each of which is arranged via screw connections  210  and  211  at the guide rail  207  and the upper frame part  203 . In the arranged condition at the substrate carrier components, the two movement limiters  212  and  213  form between them a gap such that contact-free movement of the limiter bodies  212  and  213  towards each other is possible. 
     In the limiter body  213 , as is especially evident from  FIG. 17 , a cylindrical cutout  215  is provided into which, through the upper limiter body  212 , a screw  214  with its threaded pin projects. Instead of such a screw construction, another screw design, such as an integral screw design, may be provided at the limiter body  212  or the provision of a corresponding bolt or the like may be considered. The essential aspect is that the screw pin is merely restricted in its freedom of movement by the cutout  215 , such that the screw  214  strikes the lower limiter body  213  after a certain degree of movement and thus limits mutual movement of guide rail  207  and upper frame part  203 .