Abstract:
A device for polishing digital storage discs including a polishing plate rotatably driven about a vertical axis, the upper side of which has a polishing cloth, wherein the polishing cloth is interrupted by a ring-shaped recess concentric with the axis of the polishing plate, at least one circular load-applying plate from the planar lower side of which a projection centrally protrudes to appropriately engage the central hole of the storage disk, a roller holder which has at least one idling roller and one driven roller against which the circumference of said load-applying plate gets into engagement when said plate is carried along while lying on said polishing plate, a drive for said driven roller, and mechanism for feeding a polishing medium to said polishing cloth.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     CD&#39;s, DVD&#39;s or similar optically readable discs storage discs are formed from a suitable plastic material and are “written on” subsequently. The area on one side on which a written record or sound record is made leaves a vacant area which is concentric with the central opening and adjacent thereto. 
     What frequently occurs is that damage is caused to the area bearing a written record or sound record on such a storage disc. The result of merely a slight damage in the form of scratches or the like can be already that the playback can no longer be effected without faults or is no longer possible. This can be counteracted by polishing the storage disc. 
     It is the object of the invention to provide a device for polishing digital storage discs which allows polishing a plurality of storage discs at a time in a simple machining manner. 
     BRIEF SUMMARY OF THE INVENTION 
     The inventive device has a polishing plate rotatably driven about a vertical axis the upper side of which has a polishing cloth. Polishing plates with a polishing cloth to which a polishing medium is fed are known as such for the various applications. 
     The polishing cloth of the invention is interrupted by a ring-shaped recess of the polishing plate that is arranged concentrically with the axis of the polishing plate. The disc to be polished is held, with regard to the arrangement described for the polishing cloth, in such a way that the central area which is not to be polished is located above the ring-shaped recess. Further, according to the invention, at least one circular load-applying plate is provided the planar lower side of which is centrally fitted with a slightly protruding projection to appropriately engage the central hole of the storage disk. During loading, the storage disk is positioned on the polishing plate and the load-applying plate is centrically placed onto the storage disk. To accomplish a relative motion while the polishing plate rotates the load-applying plate is prevented from being carried along by the polishing plate by means of two radially spaced rollers which are supported on a roller holder. One roller is an idling roller whereas the other roller is driven by an appropriate drive. During the polishing procedure, the load-applying plate is pressed against the two rollers by its circumference. Furthermore, the load-applying plate is rotated by means of the driven roller, by which an efficient polishing operation is achieved. 
     The position of said rollers is such that the projection of said load-applying plate is located above said ring-shaped recess when said load-applying plate bears on the rollers. What can be deduced from the description of the inventive device is that the storage disks which need polishing can be loaded and unloaded in a simple way. The polishing procedure itself is automatic and can be terminated either manually by an operator or even automatically via an appropriate program. The inventive device is of an extremely simple construction and, therefore, involves little manufacturing expenditure. It is understood that it is an advantage, in particular, that a major number of load-applying plates which are evenly spaced are on the polishing plate to allow a major number of storage discs to be polished at a time. The roller holders are preferably arranged at equal spacings above the polishing plate. 
     According to an aspect of the invention, the polishing plate is disposed in a tray. The tray serves for catching the excessive polishing medium which may be passed to a collection container from the tray. 
     According to an aspect of the invention, the polishing cloth is positioned on two annular surfaces of the polishing plate which are separated by said ring-shaped recess with the polishing plate having an indentation in a tray shape adjacent to the inner annular surface of the polishing plates. Polishing medium may run into this indentation and may flow off through at least one discharge duct leading to the tray surrounding it. This discharge duct preferably crosses the ring-shaped recess so that the polishing medium gathering in the ring-shaped recess may also be discharged therethrough. 
     According to another aspect of the invention, the polishing medium is fed by means of at least one nozzle arranged above the polishing plate which communicates with a source of polishing medium. The nozzle is preferably adjustable in cross-section to vary the feed volume. The nozzle is led to the polishing cloth via an appropriate flow communication path. Although it is imaginable to use a line or pipe as a flow communication path there is a risk of the path to be jammed. Therefore, an aspect of the invention proves that the flow communication path is formed by a wire along which the polishing medium runs downwards. 
     Another aspect of the invention provides that a chamber communicating with the source of the polishing medium is arranged above said nozzle and a return line communicates with said chamber to permanently agitate the polishing medium between the source and chamber. The polishing medium may then be fed to the polishing cloth by gravity through at least one nozzle. 
     A separate drive is useful for the driven roller. It preferably comprises an electric motor which is preferably mounted on the roller holder with the driven roller mounted on the vertical shaft of the electric motor, according to a further aspect of the invention. 
     The roller holder may be adjustably mounted on a stationary support for setting purposes. 
     The drive of the load-applying plate is preferably a frictional drive. For this purpose, the driven roller may be circumferentially fitted with at least one flexible ring which frictionally interacts with the circumference of the load-applying plate. For this purpose, the load-applying plate circumferentially may also have a roughened area to improve the frictional engagement. 
     To prevent the loaded disc from being stuck to the planar lower side of the load-applying plate a suitable cloth is adhered to the lower side of the load-applying plate, according to a further aspect of the invention. 
     According to a further aspect of the invention, the projection existing on the lower side of the load-applying plate is defined by an exchangeable pin which protrudes only slightly beyond the lower edge of the load-applying plate and the storage disk to make it easier to position the load-applying plate on the memory disc. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       An embodiment of the invention will be explained in more detail below with reference to the drawings. 
         FIG. 1  shows a plan view of a schematically illustrated device according to the invention. 
         FIG. 2  shows a section through the representation of  FIG. 1  along line  2 — 2  with not all details illustrated. 
         FIG. 3  shows a plan view of a load-applying plate and a roller holder of the device of FIG.  2 . 
         FIG. 4  shows a section through the representation of  FIG. 3  along line  4 — 4 . 
         FIG. 5  shows a section through a nozzle block of the device of FIG.  1 . 
         FIG. 6  shows a plan view of the nozzle block of the device of FIG.  5 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While this invention may be embodied in many different forms, there are described in detail herein a specific preferred embodiment of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiment illustrated. 
     A tray  10  is shown arranged on a stand  12  drawn in dotted lines. A polishing plate  14  which rotates about a vertical axis is rotatably supported in the centre of the tray. As ensues from the cross-sectional illustration of  FIG. 2  the circular polishing plate  14  is centrally fitted with a circular tray-like indentation  16 . A ring-shaped groove-like recess  18  which runs concentrically is provided farther towards the edge. Annular surfaces  20 ,  22  to which a polishing cloth (not shown) is adhered are arranged on the two sides of the ring-shaped recess. Further, a radial bore  24  can be seen which joins the central indentation  16  to the circumference of the polishing plate. The bore  14  crosses the ring-shaped recess  18 . As a result, the indentation  16  and the recess  18  communicate with the outer surface of the plate  14  and, hence, the interior of the tray  10 . 
     Eight circular or cylindrical load-applying plates  26  are shown arranged on the polishing plate  14 . Their diameter corresponds to the width between the inner periphery of the inner annular surface  22  and the outer periphery of the outer annular surface  20 . Their centre is located approximately in the middle of the ring-shaped recess  18 . The load-applying plates  26  are held by rollers of eight evenly spaced roller holders  28  which are fixed in an appropriate way. Reference will be made below to the construction of the roller holders  28  and load-applying plates  26 . 
     It can be seen from  FIG. 4  that the load-applying plates  26  are massive and centrally receive a pin  30  which slightly protrudes at  32  beyond the planar lower side of the load-applying plate  26 . The pin portion  32  is sized so as to appropriately fit into the standardized opening of storage discs, e.g. CD&#39;s or DVD&#39;s. When the load-applying plate  26  is placed onto such a storage disc the portion  32  will protrude only slightly beyond the lower side of the storage disc. A suitable cloth is adhered to lower side of the load-applying plate  26 , which is not shown, however. 
     The roller holder  28  is formed from a suitable, solid sheet metal material and, on one side, has an arcuated contour  34  which is of approximately the same radius than is the circumference of the load-applying plate  26 . At the end of the contour that is left-hand in  FIG. 3 , an idling roller  36  is rotatably supported about a vertical axis. An the other end, a driven roller  38  rotatably supported about a vertical axis with either roller  36 ,  38  being in engagement with the circumference of the load-applying plate  26  when the load-applying plate  26  is moved against the roller or roller holder  28 . The length of arc between rollers  36 ,  38  is less than 180°. The roller holder  28  is also arcuated on the opposed side. However, this does not play a role for its operation. 
     As can be seen from  FIG. 4  the idling roller  36  is rotatably supported by means of a stud  40 , which is mounted on the roller holder  28 , and a roller bearing. The driven roller  38  is seated on the vertical shaft  42  of an electric motor  44  which drives the shaft  42  via a gearing  46 . The casing of the geared motor  44 ,  47  is seated in a circular recess of a retaining component  48  which is appropriately fixed to the roller holder  28  (by a bolted mount  50 ) as can be seen in FIG.  3 . The driven roller  38  is mounted on the shaft  42  by means of a pin screw  52 . 
     Three side-by-side rings  54  which are square-shaped in cross-section and are made of a flexible material are arranged in an appropriate groove at the circumference of the driven roller  38 . The outer circumference slightly protrudes beyond the outer circumference of the roller  38 . The driven roller  38  is in a frictional engagement with the circumference of the load-applying plate  26  via these rings. The circumference of the load-applying plate  26  may be fitted with a fluting or the like to improve the frictional engagement. 
     The roller holder  28  is slidingly mounted in a component  58  to enable a displacement of the roller holder  28  in its radial position. A threaded bolt  60  extends through an elongate-hole opening  62  in the component  56  to fix the roller holder  28  in place. Seated on the bolt  60  is a nut  64  on which a handle  66  is mounted to locate the roller holder  28  in a desired position. The mounting of the component  56  as such is not shown in detail. 
     In operation, one storage disc each is positioned on the polishing plate  14  between adjacent roller holders  28 , namely in the area as is shown in FIG.  1 . Subsequently, the load-applying plates  26  are centrically placed onto the storage discs. The polishing plate  14  is set into rotation afterwards. The result is that the load-applying plates  26 , along with the storage discs, automatically get into the positions illustrated in FIG.  1 . The electric motors  44  are triggered simultaneously or subsequently so that they drive the rollers  38 , which causes the storage discs to rotate with the load-applying plates  26 . This is the way the polishing process is carried out. The process requires a polishing medium which is fed from top, namely by means of a device as is illustrated in  FIGS. 5 and 6 . 
     A square-shaped block  70  is centrally located above the polishing plate  14  and is kept stationary by means of a retaining plate  72  in a way which is not shown in detail. The upper side of the block  70  has disposed thereon an indentation  74  which is closed by a lid  76 , thus forming a chamber  78 . The chamber communicates with a feed line  78  ( FIG. 6 ) for a flowable polishing medium, and with a return line  80 . The two lines  78 ,  80  communicate with a source of the polishing medium that is not shown, e.g. a reservoir and a pump. The bottom  82  of the block  70  has screwed therein four valve blocks  84 , which have an axial through bore  86 , in a square arrangement. Pins  88  which are externally fitted with a handle  90  for turning the pins are inserted transversely to the through bore. The pins have a transverse through bore  92  which, when turned, are capable of varying the cross-section of flow. Thus, polishing medium from the chamber  78  flows downwards through the bores  86 . The lower side of each valve block has joined thereto a wire  94 . It is clamped in place in a respective bore, which is aligned with the through bore  86 , by means of a pin screw  96 . The wires  94  initially run downwards vertically and are then bent away towards the side. The lower end  98  of the wires terminates shortly above the polishing cloth on the annular surface  22  (FIG.  1 ). The polishing medium runs along the wires  94  and, in this way, reaches the polishing cloth on the annular surface  22 . Since the load-applying plates  26  rotate the polishing medium will also transferred to the polishing cloth on the annular surface  22 . Since the polishing medium can be relatively aggressive the elements described are made of a little corrodible material. Thus, for example, the wires  94  are of stainless steel. 
     The lid  76  has connected thereto an air relief tube  100  which ascertains whether there is a polishing medium in the chamber  78 . If this is not the case a corresponding signal is emitted. 
     As was mentioned already excessive polishing medium which gathers in the indentation  16  and the ring-shaped recess  18  can get to the outside through the ducts  24  and flow into the tray  10 , from which place it is passed to a suitable collection container. 
     The above Examples and disclosure are intended to be illustrative and not exhaustive. These examples and description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternative and variations are intended to be included within the scope of the attached claims. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims attached hereto.