Abstract:
The present invention relates to a device for holding disk-shaped plastic substrates for pick-up and deposit. The device includes a holding device having at least one support unit for the plastic substrates, and a pick-up and/or deposit device on which a plastic substrate is mounted and from which the plastic substrate is picked-up or deposited. The holding device has a recess and the disk-shaped base body has a cylindrical protrusion on its side facing the holding device, which can be plugged into and releasably held mechanically or in a permanent-magnetic way in the recess.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a device for holding preferably disk-shaped plastic substrates, such as CDs, DVDs and recording media of this type, so that they can be picked up and deposited, having a holding device on which at least one support unit for the plastic substrate is held, and a pickup and/or deposit device, from which the plastic substrate can be picked up, or respectively on which it can be deposited. 
     BACKGROUND OF THE INVENTION 
     With such a device employed in the course of processing disk-shaped plastic substrates, the support unit has a plate-shaped mask, from whose underside a pin projects, on whose circumference at least one pair of resiliently seated locking spheres are arranged opposite each other. The distance of these spheres from the underside of the mask is equal to or greater than the thickness of the plastic substrates to be processed. With this known device the pin of the support unit is inserted into the centered hole of the plastic substrate, so that the plastic substrate can snap behind the resiliently seated spheres. During transport of the plastic substrate from a pickup station to a transfer station, the plate-shaped mask holding the plastic substrate is held, with the plastic substrate downwardly suspended, with the aid of an electromagnet arranged on a transport arm which is pivotable in the horizontal plane. At the transfer station to a processing device, the plastic substrate provided with the plate-shaped mask is taken over by a vacuum holding device after the electromagnet is switched off. The removal of the plastic substrate from the plate-shaped mask, which in turn is held by an electromagnet, takes place by pulling it off by means of the vacuum. Since this known device requires electromagnets at the support arm and resiliently seated locking spheres at the plate-shaped mask, this device is relatively elaborate in design and therefore only suited for those transport devices which, like the above mentioned pivot arm, only offer two transport spaces. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a device for holding preferably disk-shaped plastic substrates of the type mentioned at the outset, which can be picked up and deposited, is designed in a simpler way and is suitable in particular for those transport devices, which are equipped with several transport spaces and move the plastic substrates in a plane which is different from the horizontal plane. 
     This object is attained by provision of a device for holding preferably disk-shaped plastic substrates of the type mentioned at the outset, which can be picked up and deposited. The device having a support unit with a disk-shaped base body which has on its side facing a holding device a cylindrical protrusion on which a disk-shaped plastic substrate can be placed and which can be plugged into or releasably held mechanically or in a permanent-magnetic way in a recess of the holding device. 
     By means of the steps in accordance with the present invention it is achieved that the disk-shaped plastic substrates can be held in a considerably simpler way and independently of the spatial position of the holding device. In this way holding of the plastic substrates, together with holding of the support unit on the holding device, is achieved without any further steps. It is assured here that when the plastic substrate is received by the support unit, the plastic substrate is unstressed and therefore not placed under a load. The steps in accordance with the present invention are advantageous in particular in connection with transport devices used for cooling the plastic substrates, which had previously been produced by means of an injection molding process. In this case a plurality of transport spaces are provided, which have been designed in a simple manner as pluggable and releasable held pickups, wherein it is not necessary to supply these transport spaces, which are equipped with a holding device, with either electrical energy or with a vacuum or the like. This makes the holding of the plastic substrates structurally particularly simple. Moreover, it is assured that the plastic substrate itself remains unstressed and is therefore not placed under a load, not only when being picked up by the holding device, but also when the plastic substrate is being pulled off the holding device, or respectively is deposited on the deposit device. 
     The pluggable and releasable holding of the support unit at the holding device can be provided by mechanical locking means, for example. However, in a preferred embodiment of the present invention, the support unit can be pulled out of the holding device by means of a vacuum device arranged in the pickup and/or deposit device. This arrangement provides for permanent-magnetic holding. In this case, an advantageous structural design results from the characteristics whereby a permanent-magnetic disk is arranged in the recess of the holding device, and the support unit is at least partially made of a magnetic metal, with the support unit having an axial through-bore which receives a metal bolt. 
     By means of the characteristic whereby the disk-shaped base body of the support unit is provided with a second cylinder protrusion which enters with play into the depression of the pickup and/or deposit device ina centering manner it is achieved that the vacuum required for pulling the plastic substrate off the holding device can be applied to the underside of the base body of the support unit without any further connecting bores. By means of this step it is also achieved that no direct stress is applied to the plastic substrate when removing it from the holding device, because the plastic substrate is not held by the vacuum, but by the support unit, and is separated from the holding device. 
     With the disk-shaped base body of the support unit inserted into a depression of the pickup and/or deposit device flush with the surface are provided, the plastic substrate does not only rest on the base body of the support unit, but also directly on the pickup and/or deposit device. 
     With the pickup and/or deposit device moved toward the holding device, the pickup and/or deposit device is moved toward the holding device for picking up, or respectively depositing the plastic substrate. In this connection it is practical to provide the pickup and/or deposit device with a support for receiving the disk-shaped base body and the disk-shaped plastic substrate, and a pressure plate which is connected with a lift drive, the pressure plate being kept at a distance from the support by a compression spring in order to limit a force possibly acting on the holding device to a minimum. 
     The characteristies of a holding device constituted by a rotating unit provided with several radial arms and a horizontally rotating shaft, and a support unit received on each arm are provided for the use of the device, in particular in connection with one for cooling disk-shaped plastic substrates directly after they have been injection molded, so that the plastic substrates can be cooled in the course of a complete revolution of the rotating unit in the exemplary embodiment. Moreover, an arrangement which saves space in the horizontal plane results from this, which furthermore results in improved cooling, while preventing a heat accumulation. It is practical here in accordance with the characteristic whereby a pickup station and a deposit station, which preferably follows after a full revolution in the direction of rotation are assigned to the rotating unit to provide the pickup and the deposit devices at two separate stations. 
     Further details of the present invention can be found in the subsequent description, in which the invention will be described in greater detail and explained by means of the exemplary embodiment represented in the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 represents, in a schematically cut and sectional view, a device in accordance with a preferred embodiment of the present invention for holding disk-shaped plastic substrates, which can be picked up and deposited, in an initial position, 
     FIG. 2 shows a representation corresponding to FIG. 1, but in a transfer position, 
     FIG. 3 shows the device in accordance with FIGS. 1 and 2 in a reduced and expanded representation, but in a position for picking up a plastic substrate, and 
     FIG. 4 is a representation corresponding to FIG. 3 with the plastic substrate picked up. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The device  10  represented in the drawings is used for holding disk-shaped plastic substrates  11 , such as CDs, DVDs and recording media of this type, which can be picked up and deposited, wherein the device  10  is of particular advantage when it is used for cooling of such disk-shaped plastic substrates  11 , which had previously been produced by means of an injection molding method. 
     In accordance with FIGS. 3 and 4, the device  10  has a hub  12 , rotatingly driven, for example in the direction of the arrow A, which is provided with a horizontal axis of rotation, on which radially projecting holding devices  15  are maintained, each of which has a spoke, or respectively an arm  13  and a pickup head  14  fastened on the end thereof. The arms  13  are arranged at identical angular distances from each other over the circumference of the hub  12 . Each pickup head  14  can be releasably equipped with a support unit  16  for a disk-shaped plastic substrate  11 . To this end the pickup head  14  fastened on the arm  13  has a permanent magnet  22 , which is axially maintained in an axial recess  21  and supported on an O-ring  23  at the rear. 
     The device  10  furthermore has a pickup device  17  for picking up a disk-shaped plastic substrate  11  by means of a pickup head  14  of the holding device  15 . The pickup device  17  can be moved up and down in accordance with the two-headed arrow B in relation to the respective holding device  15 . As will be explained later, the pickup device  17  is used as a station for the sequential pickup of a disk-shaped plastic substrate by means of the holding devices  15  of the device  10 , which rotate past this station. A further station is used for the sequential deposition of the disk-shaped plastic substrates  11 , which have been cooled in the course of a complete or partial circulation. In the exemplary embodiment, the pickup station and the deposit station are identical. 
     The support unit  16  has a disk-shaped base body  26 , which is equipped with two coaxially cylindrical protrusions  27  and  28 , which are oriented toward each other and here have the same diameter and the same length. The support unit  16  has an axial threaded through-bore  29 , into which an externally threaded bolt  33  has been inserted as iron core and which is fixed in place by a radial grub screw screwed into a radial threaded bore  30 . The dynamically balanced support unit  16  can be used in both of its 180° positions. 
     The pickup device  17  essentially consists of a support body  36 , a pressure plate  37  and a clamping block  38 . A piston-cylinder unit, which for example is pneumatic and performs a movement in accordance with the two-headed arrow B, acts in a manner not represented on the clamping block  38 , which is fixedly connected with the pressure plate  37 . The pressure plate  37  is held, movable in a resilient manner, a short distance from the underside of the support body  36  by means of several compression springs  39 . The spring travel  41  between the pressure plate  37  and the support body  36  resulting from this has a length of a few millimeters, for example 2 mm. The compression springs  39  enclose a bolt connection  42  and are supported via adjusting washers  40  at the shoulders  43  and  44  of the respective bores. Centering between the pressure plate  37  and the support body  36  is provided by means of a centering screw arrangement  45 . 
     On its upper side facing away from the pressure plate  37 , the support body  36  has a centered pickup bore  46 , which is provided with stepped coaxial elements and into which the cylindrical protrusion  28 , or respectively the disk-shaped base body  26  fits. The pickup bore  46  starts at a depression  47  of larger diameter, which is bordered at the circumferential edge by a circularly-shaped support  48  for the disk-shaped plastic substrate  11 . In the inserted position in accordance with FIG. 2, the support surface of the circularly-shaped support  48  is co-planar with the upper support surface  31  of the disk-shaped base body  26 . At its inner end, the pickup bore  46  is provided with a connecting bore  51 , which terminates in one or several radial bores  52 , which is/are connected in a manner not shown with a vacuum device. In the position of the support unit  16  represented in FIG. 2, the underside  34  of the disk-shaped base body  26  rests on an annular shoulder  53  of the first bore element of the pickup bore  46 . The bore element connected with this receives the lower cylindrical protrusions  28  with radial play (for example 0.5 mm). A depression exists between the annular shoulder  53  and the pickup bore  46 , through which, a well as through the radial play, the vacuum from the bores  52  and  51  can be applied to a free annular face (vacuum application face) on the underside  34  of the support unit  16 . 
     In accordance with FIG. 1, a support unit  16  in the pickup head  14  is releasably held in a permanent-magnetic manner by the permanent magnet  22  and by the iron core  33  in an initial position. In this position the support surface  31  of the disk-shaped base body  26  of the support unit  16  is at a distance from the underside of the pickup head  14 , which approxinately corresponds to the thickness of the substrate  11 . In order to reach the transfer position represented in FIG. 2, the pickup device  17  is moved upward in accordance with the two-headed arrow B in such a way that the support unit  16  is received in the pickup bore  46  of the support body  36 . In this position a vacuum is applied to the underside  34  of the support unit  16 , so that the support unit  16  is separated in this way from the permanent magnet  22  and therefore is held in the pickup bore  46  of the support body  36 , or respectively remains in it. The pickup device  17  is again moved axially downward while the vacuum is applied. 
     Thereafter, a substrate  11 , provided with a center hole  18 , is placed on the support body  36  by means of a feed device, not represented, as can be seen in FIG.  3 . The plastic substrate, produced in a process not represented, lies on the disk-shaped base body  26  and the circularly-shaped support  48  and is radially held by the cylindrical protrusion  27 , whose exterior diameter approximately corresponds to the interior diameter of the hole  18 . 
     Following this, the support unit  16  connected with the substrate  11  can again be moved to the holding device  15  by lifting the pickup device  17 , since without a vacuum the support unit  16  remains suspended from the permanent magnet  22 . The pickup device  17  is then moved downward again, and this operational position is represented in FIG.  4 . 
     A cushioned adhesion is achieved by means of the resilient connection between the clamping block  38 , or respectively the pressure plate  37 , and the support body  36  during the movement of the pickup device  17  upward towards the pickup head  14 , and therefore a minimum force action is applied to the support unit  16  and the pickup head  14 , or respectively to the entire holding device  15 . 
     Following the pickup of a substrate  11  in accordance with FIG. 4, the hub  12  is moved on by one step in accordance with the arrow A, so that a substrate  11  can be picked up in the just described manner by the subsequent holding device  15 ′. The step- by-step rotating movement of the substrates  11  allows, for example, cooling of the substrates  11 , wherein the length of cooling depends on the location of the following deposit station. For example, the deposition of the cooled substrates  11  can take place after one complete or almost complete revolution. The substrates cooled in this way are then moved away for further processing.