Abstract:
The invention relates to a clamping device for holding a substrate. This clamping device includes a press-on fixture and a lower part, wherein at least the press-on fixture or the lower part includes at least a permanent magnet. If one of the two parts includes a permanent magnet, it suffices if the other part includes magnetizable material. A further permanent magnet can be provided, with which one end of the press-on fixture can be lifted up.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a clamping device for substrates. 
       BACKGROUND OF THE INVENTION 
       [0002]    In sputter installations substrates are frequently moved adjacent a target, from the surface of which particles are sputtered off which are deposited on the substrate. As the substrates can be considered, for example, glass panes, which are transported through an inline sputter installation. These glass panes are embedded in frames connected with a transporting device, and this frame includes a holding apparatus, with which the glass pane can be fixed in this frame. 
         [0003]    For example a device for the mounting of a mask of a ferromagnetic material on a planar substrate is known, in which the substrate is disposed between the mask and a frame (DE 29 707 686 U1). The frame includes at least one permanent magnet disposed in this frame. 
         [0004]    A mounting disposition for the vertical mounting of a substrate is disclosed in DE 10 2004 027 898 A1. This mounting disposition serves for mounting the substrate in the suspended state and includes two clamping elements associated to each other, each element being provided with at least one contact face, between which the substrate is disposed in the mounting state. To secure the clamping elements, blocks are provided which are positioned with machine screws. 
       SUMMARY OF THE INVENTION 
       [0005]    The invention addresses the problem of providing a clamping device for substrates which is simple in structure and can be readily handled. 
         [0006]    Embodiments of the invention consequently provide a clamping device for holding a substrate. This clamping device comprises a press-on fixture and a lower part, at least the press-on fixture or the lower part comprising at least one permanent magnet. If one of the two parts comprises a permanent magnet, it suffices if the other part comprises magnetizable material. Further, a permanent magnet can be provided with which one end of the press-on fixture can be raised. 
         [0007]    This clamping device can simply be attached on a holding apparatus, for example a frame and, if necessary, can also be readily removed again. This has the advantage that a damaged clamping device can be replaced by a new one without great effort. The holding apparatus does not need to be completely disassembled for this purpose. 
         [0008]    Since the clamping device is comprised of a low-cost material, the replacement of a damaged clamping device is cost-effective and readily managed due to the simple assembly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Embodiment examples of the invention are shown in the drawing and will be explained in the following in further detail. 
           [0010]      FIG. 1  is a perspective view of a clamping device with a substrate; 
           [0011]      FIG. 2  is a side view of the clamping device with substrate depicted in  FIG. 1 ; 
           [0012]      FIG. 3  is the clamping device depicted in  FIG. 2  after removal of the substrate; 
           [0013]      FIG. 4  is a top view of the clamping device depicted in FIG.  1 ;, 
           [0014]      FIG. 5  is a sectional view through the clamping device depicted in  FIG. 1 ; 
           [0015]      FIG. 6  is a variant of the clamping device with substrate depicted in  FIG. 2 ; 
           [0016]      FIG. 7  is the clamping device depicted in  FIG. 6  after removal of the substrate; 
           [0017]      FIG. 8  is a variant of the clamping device depicted in  FIG. 1  to  FIG. 5 ; and 
           [0018]      FIG. 9  is a substrate disposed on a frame provided with clamping device. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 1  depicts in perspective view a clamping device  1 , by means of which a substrate  2  is held. The substrate may be, for example, a glass pane which is to be coated. Evident is a lower part  3  with several bores  4  to  7 . These bores  4  to  7  serve the purpose of attaching the clamping device  1  on a frame by means of connecting elements. As the connecting elements may be used, for example, machine screws. However, frame as well as connecting elements are not shown in  FIG. 1 . 
         [0020]    Adjoining the lower part  3  is a block  8 , on which is disposed a press-on fixture  9  by means of a connecting bolt  10 . The press-on fixture  9  includes a front portion  11  arched convexly in the direction of the lower part  3 , which is adjoined by two parallel webs  12 ,  13 , which, in turn, are connected to one another by a transverse web  14 . The webs  12 ,  13  and the transverse web  14  together form a rectangular opening which encompasses the block  8 . Instead of one block  8 , two blocks may also be provided between which the press-on fixture  9  is located. 
         [0021]      FIG. 2  depicts a side view of the clamping device  1  shown in  FIG. 1 , and specifically with view in the direction A. Evident is again the lower part  3  with the block  8  disposed thereon, on which the press-on fixture is located. This press-on fixture  9  is fastened on block  8  by means of the connecting bolt  10 , which includes for example a machine screw  10   a  and a nut  10   b.    
         [0022]    It is also evident that the substrate  2 , which to some extent rests in contact on the lower part  3 , is also in contact with the lower portion  15  of the arched front portion  11 . The substrate is consequently clamped in between a lower portion  15  of the arched front portion  11  and the lower part  3 . 
         [0023]    Since the press-on fixture  9  is only attached on the block  8  by a connecting bolt  10 , the press-on fixture  9  can be moved through a force F acting onto the transverse web  14 , which force acts in the direction of the lower part  3 , i.e. preferably in the direction of arrow  16 . Through this force F the arched front portion  11  is moved in the direction of arrow  17 , i.e. away from lower part  3 , and the transverse web  14  in the direction of arrow  16 , i.e. toward the lower part  3 . The substrate  2  is thereby no longer clamped between the lower part  3  and the lower portion  15  of arched front portion  11 , whereby it can be removed out of the clamping device  1 . 
         [0024]      FIG. 3  shows the clamping device  1 , depicted in  FIG. 2 , shortly after the removal of the substrate  2 . The press-on fixture  9  assumes therein a position in which the arched front portion  11  is moved away from lower part  3  and the transverse web  14  toward the lower part  3 . This permits a substrate to be placed onto the lower part  3 . If force F is no longer engaging, the front portion  11  is again moved in the direction of the lower part, i.e. in the direction of arrow  19 . It must be possible to open the press-on fixture  9  far enough for the substrate  2  to be removed in the forward direction, i.e. perpendicularly away from the carrier. For this purpose in the lower part  3  is provided a recess or cutout  19 . It is also possible to provide a notch at the lower end of block  8 . It is further possible to apply the connecting bolt  10  eccentrically on the block. 
         [0025]      FIG. 4  shows a top view onto the clamping device  1  depicted in  FIG. 1  with the substrate  2  clamped between the lower part  3  and the front portion  11  of the press-on fixture  9  and is thus held. Evident further is that the press-on fixture  9  is movably disposed on block  8  and is held by means of a connecting bolt  10 . However, shown are only the nuts  10   b  and  10   b ′ of the connecting bolt  10 . 
         [0026]      FIG. 5  shows a section through the clamping device  1  depicted in  FIG. 1  in the viewing direction A. Consequently, the depiction of  FIG. 5  corresponds to that of  FIG. 2 , with the difference that  FIG. 5  is a sectional representation. 
         [0027]    Seen can be the lower part  3  and block  8  through which penetrates the connecting bolt  10 . Block  8  and lower part  3  are preferably comprised of the same material, for example Teflon® polymers (polytetrafluoroethylene), PEEK™ polymers (polyetheretherketone) or PVC polymers (polyvinylchloride). These two parts can thereby be produced simply and cost-effectively and the production may be carried out, for example, through injection molding processes. 
         [0028]    In the region of lower part  3 , above which is disposed the arched front portion  11  of the press-on fixture  9 , is placed a magnet  20 . Since the press-on fixture  9  is comprised of a magnetic or magnetizable material, for example sheet metal, a magnetic force acts onto the press-on fixture  9 , which force presses the front portion  11  onto the substrate  2 . The clamping mechanism therefore is based exclusively on magnetic force. It is understood that it is not necessary for the entire press-on fixture  9  to be comprised of magnetizable material. It suffices if only the front portion  11  is comprised of magnetizable material. 
         [0029]    If the substrate  2  is to be removed from the clamping device  1 , onto the transverse web  14  a force F must be exerted, which is stronger than the magnetic force. When this is the case, the front portion  11  is moved away from the lower part  3  and the substrate can be removed. 
         [0030]      FIG. 6  shows a variant of the clamping device depicted in  FIG. 2 . This clamping device  21  also includes a lower part  22  with a block  23  seated thereon, on which a press-on fixture  24  is disposed. As in  FIG. 2 , the press-on fixture  24  is also fastened on the block  23  such that it is movable by means of a connecting element  25 . 
         [0031]    The press-on fixture  24  in  FIG. 6  also comprises a front portion  26 . However, this front portion  26  is not arched on the underside  27 , but has a flattened underside  27 , with which it rests on the substrate  28 . Since the lower part  22  like the lower part  3  of clamping device  1  in  FIG. 5  includes a magnet, the clamping force is also based on the magnetic force obtaining here. In contrast to the clamping device  1 , this clamping device  21  includes an extension  29 . This extension  29  is preferably comprised of the same material as the block  23  and the lower part  22 . 
         [0032]    The extension  29  has the shape of an upside-down “L”, which is obtained by rotation of this “L” by 180 degrees. Through the upper region  30  of the extension  29  is guided a pin  31 , which can be moved in the direction of arrow  32  or  33 , alternatively. This pin includes magnetic material or is entirely comprised of magnetic material. Since the clamping device  21  can be operated entirely without spring force, not only the clamping force between front portion  11  or  26 , alternatively, and the permanent magnetic  20  is generated by means of magnetic attraction but the opened hollow arm  9  or  24 , alternatively, is also moved through magnetic force from the position “open” into the clamping position. When pulling back pin  31 , web  34  is entrained until the magnetic attraction between the permanent magnet  20  and the front position  11  or  26 , alternatively, comes to bear again. 
         [0033]    It is understood that extension  29  can also be implemented differently and even be disposed on block  23  itself. It is only important that it includes an element which fulfills the function of pin  31 , namely that by means of this element the press-on fixture  24  can be moved away from the substrate  28  such that the substrate can be removed from the clamping device  21 . 
         [0034]      FIG. 7  shows the clamping device  21  depicted in  FIG. 6  after the substrate  28  has been removed. To be able to remove the substrate  28 , pin  31  was moved in the direction of arrow  33 . Since the press-on fixture  24  also includes a transverse web  34 , the front portion  26  of the press-on fixture  24  is moved through the force, with which pin  31  acts onto the transverse web  34 , away from the lower part  22 , such that substrate  28  can be removed from clamping device  21 . The force, which is generated through the movement of pin  31  in the direction of arrow  33 , must be greater than the magnetic force, in order for the front portion  26  of press-on fixture  24  to be moved in the direction of arrow  35  until the front portion  26  rests again with its underside  27  on the new substrate. The substrate is subsequently held through the magnetic force, which acts as clamping force. 
         [0035]    Even though it is possible to move the pin  31  manually, it is of advantage if the movement of pin  31  is controlled for example by means of a computer. Since the clamping device  21  is only comprised of few parts, it has low susceptibility to wear. In order to avoid scratches on the substrate  28 , on the lower part  27  of front portion  26  of press-on fixture  24  a synthetic material layer can additionally be disposed. However, such a synthetic material layer is not shown in  FIG. 7 . 
         [0036]      FIG. 8  depicts a variant of the clamping device, in which on the block  23  a transverse web  60  is disposed, through which a pusher  61  is movable in the direction of arrow  62 . This pusher  61  is at least at its lower end magnetic. If only the rearward end of the press-on fixture  24  is magnetizable, with the pusher  61  the rearward end of press-on fixture  24  can be raised. Therewith an additional force between substrate  2  and press-on fixture  24  can be exerted. The mounting for the pusher  61  as well as the driving means with which it is moved, are not shown in  FIG. 8 . The pusher  61  is preferably disposed stationarily on the installation in a robot loading station or unloading station. Such a pusher  61  is electrically actuated through an installation control, such that the substrate can be removed from the installation by a robot or be placed onto a carrier, alternatively. 
         [0037]      FIG. 9  shows a substrate  36  which is disposed on a frame  37 . On this frame  37  are disposed four clamping devices  38  to  41 , each of the clamping devices  38  to  41  being disposed on opposing frame sections  42  or  43 , respectively. Consequently, in each instance two clamping devices  38 ,  41  and  40 ,  39  oppose one another. 
         [0038]    These clamping devices  38  to  41 , which hold the substrate  36 , are structured analogously to the clamping device  21  depicted in  FIG. 6  or  FIG. 7 . 
         [0039]    As with the clamping device  21  depicted in  FIG. 6  or  7 , these clamping devices  38  to  41  also include press-on fixtures  44  to  47 , which are each connected via connecting elements with a block  48  to  51 . However, for the sake of clarity, the connecting elements are not shown in  FIG. 8 . Evident are further the front portions  52  to  55  of the press-on fixtures  44  to  47 , which rest in contact on the margin region of substrate  36 , whereby the substrate  36  is held in the clamping devices  38  to  41 . 
         [0040]    It can also be seen that each clamping device  38  to  41  includes a pin  56  to  59 , through the actuation of which the front portions  52  to  55  of press-on fixtures  44  to  47  are raised. The substrate  36  can thereby be removed and replaced by a new substrate. Instead of a pin, a “pusher” can also be employed. 
         [0041]    A substrate  36 , such as is depicted in  FIG. 9 , can be held by the clamping force of the clamping devices alone, the number of clamping devices being adapted to the weight of the substrate  36 . For very heavy substrates  36  a support ledge or support pins are provided at the lower web  43  of the carrier.