Abstract:
An optical disk substrate recovering apparatus A includes an optical disk storing portion  10,  an abrader  20  for abrading a reflecting layer and a recording layer of the optical disk D, a powder collecting device  30  for collecting powdered reflecting materials and recording materials, and an optical disk transferring device  40  for transferring the optical disk D from the optical disk storing portion  10  to the abrader  20  one by one and for transferring the abraded disk substrate  1  to the abraded disk substrate storing portion  50.  The devices  20, 30, 40  are sequentially operated to thereby obtain a pure and transparent abraded disk substrate 1 made of synthetic resin from which the reflecting layer and the recording layer are removed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a method of recovering an optical disk substrate and an optical disk substrate recovering apparatus. More particularly, it relates to a method of recovering an optical disk substrate from an optical disk including a write-once optical disk called “CD-R”, a read only disk called “CD-ROM” and an optical magnetic disk, and also relates to an optical disk substrate recovering apparatus for recovering the optical disk substrate from the optical disk. 
     2. Description of Related Art 
     Recently, a write-once optical disk called “CD-R” is getting widely used for developing computer programs or recording account data in secret. For example, in a company developing computer programs, several hundreds of CD-Rs are used in one day. 
     However, since the majority of such CD-Rs include uncompleted programs or wrong data, they are to be disposed. Such a disk to be disposed may include confidential matter or data. Therefore, it is required to destroy the recorded data before disposing the disk so as not to leak out the confidential matter or data. 
     Japanese Unexamined Laid-open Patent Publication No. 09-097432 A (hereinafter referred to as “JP&#39; 432) discloses a method of destroying the data of the optical disk. In the method, a coating material is applied on the recording surface of the optical disk, or a high power radiation is irradiated onto the disk. 
     Japanese Unexamined Laid-open Patent Publication No. 10-214424 A (hereinafter referred to as “JP&#39; 424) discloses a method of making impossible to read the recorded data. In the method, the heat of 80° C. to 150° C. is applied to an optical disk to cause a thermal change around the periphery of the data pits. 
     Japanese Unexamined Laid-open Patent Publication No. 05-166231 A (hereinafter referred to as “JP&#39; 231) discloses a method of making impossible to read the recorded data. In this method, taking into account of the poor adhesion of the reflection layer to the light absorption layer, an adhesive tape is adhered to the surface of the protective layer on the reflection layer and the upward force is applied thereto, by which the light absorption layer and the reflection layer are separated at the boundary thereof. 
     Furthermore, Japanese Unexamined Laid-open Patent Publication No. 05-210873 A (hereinafter referred to as “JP&#39; 873) discloses a method of making impossible to read the recorded data. In this method, the recording layer is polished while supplying water thereto with a polisher consisting of a cylindrical polishing sheet manufactured by mixing grinding grains and an adhesive to a supporting material and molding the mixture by hot pressing. 
     However, according to the methods disclosed in JP&#39; 432 and JP&#39; 424, the disk with destroyed data still includes metallic films constituting the light absorption layer and the reflection layer made of aluminum and/or gold on the transparent disk substrate made of transparent synthetic resin. Therefore, disposing the disk as it is has problems in environmental safeguard because the plastic materials and the metallic materials are not separated. Furthermore, in order to re-use these optical disks, it is required to separate the optical disk into the synthetic materials of the disk substrate and the metallic materials of the reflection layer. 
     According to the method of JP&#39; 231, although the optical absorption layer as a recording layer and the reflection layer are separated with each other, the optical absorption layer is not separated from the disk substrate. Therefore, in order to recycle the synthetic resin disk substrate, It is required to remove the optical absorption layer from the disk substrate. Although the removal of the optical absorption layer from the disk substrate may not be technically difficult, the work is inefficient because the aforementioned removal of the optical absorption layer is performed in addition to the removal of the reflection layer. 
     According to the method of JP&#39; 873, since the polishing of the optical disk is performed while supplying water thereto, it is troublesome to treat the wasted water including the powder generated by polishing the optical disk as well as to extract noble metals which may be included in the reflection layer. Furthermore, it is required to protect the electric parts of the apparatus from water, which complicates the manufacturing of the apparatus. 
     SUMMARY OF THE INVENTION 
     The present invention is made in view of the aforementioned technical drawbacks. 
     It is an object of the present invention to provide a method of recovering an optical disk substrate from an optical disk and an optical disk substrate recovering apparatus, by which the data of the optical disk can be destroyed, the disk substrate can be recovered by removing the recording layer and the reflecting layer from the optical disk, and the powdered recording materials and reflecting materials can be easily treated. 
     According to one aspect of the present invention, a method of recovering an optical disk substrate from an optical disk having a recording layer and a reflecting layer laminated on the optical disk substrate made of synthetic resin by removing the reflecting layer and the recording layer included the steps of: abrading the reflecting layer and the recording layer of the optical disk into powdered reflecting materials and recording materials without supplying water to obtain an abraded disk substrate while collecting the powdered reflecting materials and recording materials, and collecting the abraded disk substrate. 
     With this method of recovering an optical disk substrate from an optical disk, the recording layer and the reflecting layer can be assuredly removed from the optical disk substrate made of synthetic resin to thereby recover the synthetic resin disk substrate to which no material constituting the recording layer and the reflecting layer is adhered. In addition, the abrasion of the optical disk is performed without supplying water thereto while collecting the powdered recording materials and reflecting materials, which enables an easy treatment of the powdered recording materials and reflecting materials. 
     Another aspect of the present invention resides in an optical disk substrate recovering apparatus for recovering an optical disk substrate from an optical disk having a recording layer and a reflecting layer laminated on the optical disk substrate made of synthetic resin by removing the reflecting layer and the recording layer. The apparatus includes an optical disk storing portion for storing a plurality of the optical disks, an abrader for abrading the reflecting layer and the recording layer of the optical disk into powdered reflecting materials and recording materials to obtain an abraded disk substrate, an optical disk transferring device for transferring the optical disk from the optical disk storing portion to the abrader one by one, a powder collecting device for collecting the powdered reflecting materials and recording materials, an abraded disk substrate storing portion for storing the abraded disk substrate, and an abraded disk substrate transferring device for transferring the abraded disk substrate to the abraded disk substrate storing portion. 
     With this apparatus, the recording layer and the reflecting layer can be assuredly removed from the optical disk substrate made of synthetic resin to thereby recover the synthetic resin disk substrate to which no material constituting the recording layer and the reflecting layer is adhered. In addition, by operating the apparatus after storing a plurality of optical disks into the optical disk storing portion, the optical disk substrates can be recovered automatically. Furthermore, by discharging the powdered reflecting materials and recording materials out of the apparatus, harmful influences to the motor due to the powdered materials can be prevented, resulting in a trouble-free operation of the apparatus. 
     It is preferable to absorb the powdered reflecting materials and recording materials by means of a vacuum pump, which causes air turbulence to thereby prevent a temperature rise of the disk substrate due to the friction heat generated during the abrasion of the optical disk. 
     It is preferable to agitate ambient air around the optical disk, which enhances the collection of the powdered reflecting materials and recording materials by the vacuum pump. 
     The optical disk transferring device and the abraded disk substrate transferring device may be independent devices or a common device. In a case where the optical disk transferring device and the abraded disk substrate transferring device are independent devices, the time required to recover the optical disk can be shortened. On the other hand, in a case where the optical disk transferring device and the abraded disk substrate transferring device are a common device, the structure can be simplified. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features, and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments with reference to the attached drawings, wherein: 
     FIG. 1 is a front view showing an optical disk substrate recovering apparatus according to an embodiment of the present invention; 
     FIG. 2 is a side view of the optical disk substrate recovering apparatus; 
     FIG. 3 is a side cross-sectional view showing the abrader and a part of the disk holder; 
     FIG. 4A is a schematic plan view showing an optical disk storing portion, and FIG. 4B is a schematic plan view showing an abraded disk substrate storing portion; 
     FIG. 5 is a bottom view showing a holding plate of the abrader; and 
     FIG. 6A is an enlarged cross-sectional view showing the optical disk, and FIG. 6B is an enlarged cross-sectional view showing the abraded disk substrate. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An optical disk substrate recovering apparatus according to the preferred embodiment of the present invention will be explained with reference to the drawings. 
     Since the method of recovering an optical disk substrate from an optical disk will be apparent from the explanation of the optical disk substrate recovering apparatus, the following explanation will be directed to the optical disk substrate recovering apparatus. 
     FIGS. 1 and 2 show a schematic view of the optical disk substrate recovering apparatus A. 
     The optical disk substrate recovering apparatus A is provided with an outer casing B having a size corresponding to a size of a microwave oven for household use. Provided in the outer casing  8  are an optical disk storing portion  10  for storing a plurality of optical disks D, an abrader  20  for abrading the recording layer  2  and the reflecting layer  3  of the optical disk D and an abraded disk substrate storing portion  50  for storing the abraded disk substrates  1 . In the front wall of the outer casing  8 , a lid  9  which opens upwardly is provided. By opening the lid  9 , optical disks D can be stored in the optical disk storing portion  10  and the abraded disk substrates  1  can be taken out from the abraded disk substrate storing portion  50 . 
     As shown in FIG. 4A, the optical disk storing portion  10  is provided with positioning poles  11  at equal intervals so as to touch the outer peripheral edge of the optical disk D, whereby a plurality of optical disks D can be orderly stacked. This allows a descending movement of a disk holder  41  provided to a transferring device  40  which will be detailed later. In the optical disk storing portion  10 , the optical disk D should be stored with the disk substrate  1  facing upward. In other words, the optical disk D should be stored with the recording layer  2  and the reflecting layer  3  facing downward. 
     As shown, in FIG. 1, the abraded disk substrate storing portion  50  is provided with a holding pole  51  for holding the abraded disk substrate  1  with the holding pole  51  inserted in the central hole of the abraded disk substrate  1 . The abraded disk substrate  1  from which the recording layer  2  and the reflecting layer  3  are removed by the abrader  20  is transferred, and then dropped from above the holding pole  51 . As a result, the abraded disk substrate  1  is stored in the abraded disk substrate storing portion  50  with the holding pole  51  inserted in the central hole of the abraded disk substrate  1 . For easy insertion of the holding pole  51  into the central hole of the abraded disk substrate  1 , the upper end portion of the holding pole  51  is formed to have a cone shape. 
     As shown in FIGS. 2 and 3, the abrader  20  is provided with a pair of driving motors  21  and a pair of abrading members  24  each driven by the respective motor  21 . Each driving motor  21  is suspended from a holding plate  22  with the rotation shaft  21   a  of the motor  21  upwardly protruded through the holding plate  22 . 
     At the center-portion of the holding plate  22 , a supporting rod  23  having a hub  23   a  to be fitted in the central hole of the optical disk D is upwardly protruded. The position where the hub  23   a  is engaged with the central hole of the optical disk D is an abrading position  29 . 
     The rotation shaft  21   a  of the driving motor  21  is provided with the abrading member  24  of a plate shape and an agitating rotational plate  25  by way of a fixing sleeve  26 . As shown in FIG. 3, the abrading member  24  is detachably attached to a circular holding plate  27  integrally fixed to the upper portion of the fixing sleeve  26 . The abrading member  24  and the circular holding plate  27  are provided with a plurality of penetrated apertures  24   a,    27   a  so as to correspond with each other, so that the powdered materials generated by abrading the optical disk D can be downwardly introduced into the apertures  24   a,    27   a.  The agitating rotational plate  25  provided below the circular holding plate  27  is equipped with a base plate  25   a  and a plurality of wings  25   b  upwardly protruded from the upper surface of the base plate  25   a.  These wings  25   b  agitate air above the agitating rotational plate  25  in accordance with the rotation of the driving motor  21 , so that the powdered materials downwardly passed through the penetrated apertures  24   a,    27   a  of the abrading member  24  and the circular holding plate  27  is introduced toward the hollow portion  31  to enhance the collection of the powdered materials by the collecting device  30 , as shown in FIG.  2 . Furthermore, as shown in FIG. 3, above and below the agitating rotational plate  25 , powder prevention walls  28   b,    28   a  for preventing the powder materials generated from the optical disk D are provided. In addition, a powder prevention wall  28   c  is also provided so as to be located above the level of the abrading position  29  and to surround the periphery of the optical disk D placed at the abrading position  29 . 
     The collecting device  30  includes, as shown in FIG. 2, the hollow portion  31  formed beside the agitating rotational plate  25 , a vacuum pump  32  placed at the end of the hollow portion  31  and an exhaust pipe  33  for exhausting the powdered materials out of the outer casing  8 . The exhaust pipe  33  is introduced into a powder collecting case (not shown) located outside the outer casing  8 . 
     The transferring device  40  is used to transfer the optical disk D from the optical disk storing portion  10  to the abrading position  29  and also used to transfer the abraded disk substrate  1  from the abrading position  29  to the abraded disk substrate storing portion  50 . The transferring device  40  is provided with the disk holder  41  for holding the optical disk D/the abraded disk substrate  1 , and transfers the disk D/the substrate  1  by shifting rightward, leftward, upward or downward. 
     As shown in FIG. 3, the disk holder  41  includes a holder plate  42  and a rubber plate  43  adhered on the lower surface of the holder plate  42 . The rubber plate  43  is to be fitted to the optical disk substrate  1 . Both the holder plate  42  and the rubber plate  43  are provided with air passages  44 . The disk holder  41  is also provided with an air passage  45  communicated with the air passages  44 . As shown in FIG. 2, the air passage  45  is connected to an end of a sucking pipe  46 . The other end of the sucking pipe  46  is connected to the vacuum pump  47 . Therefore, the operation of the vacuum pump  47  allows the optical disk D and the disk substrate  1  to be absorbed to the rubber plate  43  before or after the abrasion. The disk holder  41  is rotated in a horizontal plane by a geared motor  48  at a reduced rotational rate. The disk holder  41  is positioned above either the optical disk storing portion  10  or the abraded disk substrate storing portion  50  before the operation of the optical disk substrate recording apparatus A. 
     Next, the operation of the aforementioned optical disk substrate recording apparatus A will be explained. 
     First, a plurality of optical disks D from which disk substrates  1  are to be recovered are stored in the optical disk storing portion  10  via an opening made by opening the lid  9 . By throwing the optical disks D with the disk substrate  1  facing upward into a space defined by the positioning poles  11 , these disks D will be piled up orderly. 
     Then, the lid  9  is closed and the switch (not shown) is turned on to start to operate the apparatus A, causing a descending of the disk holder  41  located above the optical disk storing portion  10 , which results in an abutment of the rubber plate  43  on the upper most optical disk D. Before or at the same time of the abutment, the pump  47  of the transferring device  40  starts to operate, whereby the uppermost optical disk D is absorbed by the disk holder  41 . When the optical disk D is assuredly absorbed by the disk holder  41 , the disk holder  41  moves so as to be located above the abrader  20 . Accordingly, the optical disk D is also transferred so as to be located above the abrader  20 , as shown in FIGS. 1 and 2. Then, from this height, the disk holder  41  slowly descends, so that the hub  23   a  of the supporting rod  23  is fitted in the central hole of the optical disk D. This results in a slight pressing of the optical disk D onto the abrading member  24 . Then, the abrading members  24  start to rotate by the respective driving motor  21  of the abrader  20 . As a result, the protecting layer  4 , the reflecting layer  3  and the recording layer  2  of the optical disk D are abraded in this order. Thus, the materials constituting each layer is removed in a powdered state. 
     The powdered materials generated by the abrasion and fell down through the penetrated apertures  24   a,    27   a  are agitated by the agitating rotational plate  25 , and absorbed by the collecting device  30 . Then, the powdered materials will be gathered in a powder collecting case (not shown) located outside the outer casing  8 . In the case of CD-R, since the collected powdered materials include gold constituting the reflecting layer, the gold can be easily recovered by subjecting to an appropriate treatment. 
     After the completion of the predetermined depth abrasion, the disk holder  41  ascends while holding the abraded disk substrate  1  so as to detach the central hole of the abraded disk substrate  1  from the hub  23   a  of the supporting rod  23 . As shown in FIG. 3, it is enough to ascend the abraded disk substrate  1  to the height slightly above the powder prevention wall  28   c.    
     Then, while holding the abraded disk substrate  1 , the disk holder  41  horizontally moves to the position above the abraded disk substrate storing portion  50  so that the center hole of the abraded disk substrate  1  is located just above the holding pole  51 . Then, the disk holder  41  starts to descend, and stops when the center hole of the abraded disk substrate  1  approaches the upper end of the holding pole  51 . When the disk holder  41  stops to descend, the pump  47  also stops to operate, resulting in a termination of absorbing the abraded disk substrate  1  by the disk holder  41 . Accordingly, the abraded disk substrate  1  is detached from the disk holder  41  and falls down. Thus, the abraded disk substrate  1  is stored in the abraded disk substrate storing portion  50  with its central hole penetrated by the holding pole  51 . 
     Thus, the sequence of the operations by which one disk substrate  1  is recovered from an optical disk D is completed. 
     After the completion of the recovery of the disk substrate  1  from an optical disk D, the disk holder  41  ascends up to the position where the disk holder  41  can move horizontally, and then moves horizontally toward the position above the optical disk storing portion  10 . After the disk holder  40  arrived at the position above the optical disk storing portion  10 , the aforementioned sequence of the operations will be repeated until the lowermost optical disk D is processed. 
     As mentioned above, according to the method of recovering an optical disk substrate from an optical disk, the reflecting layer  3  and the recording layer  2  of the optical disk D are abraded into powdered reflecting materials and recording materials, the destruction of the data and recovery of the pure disk substrate  1  can be performed at a time. Thus, the leakage of the secret data recorded in an unnecessary optical disk D can be assuredly prevented. Furthermore, the recycling of the disk substrate  1  can be easily performed. 
     In addition, since the abrasion of the optical disk D is performed without supplying water, the treatment of the powdered materials generated by abrading the optical disk D can be easily performed. Furthermore, an optical disk substrate recovering apparatus A is not required to provide any special waterproofing, resulting in a reduction of the manufacturing cost. 
     Furthermore, since the powdered materials are collected, the treatment of the powdered materials can be performed easily. 
     In a case where a vacuum pump  32  is used as a collecting device  30 , since the pump  32  causes air turbulence by absorbing air around the abrading portion, the temperature rise due to the friction heat caused by the abrasion is reduced, resulting in a prevention of the melt of the disk substrate  1  to be recovered. 
     In a case where the abrasion of the optical disk D is performed while agitating air around the abrasion position, the collection and absorption of the powdered materials can be effectively performed. This agitation also reduces the temperature rise due to the friction heat caused by the abrasion. 
     According to the optical disk substrate recovering apparatus of the present invention, since the recovering of the disk substrates  1 , from a plurality of optical disks D can be continuously performed, the data can be assuredly destroyed, and the recycling of the disk substrate  1  can be easily performed. 
     Since the optical disk substrate recovering apparatus A is provided with a powder collection device  30  for collecting the powdered materials constituting the abraded recording layer  2  and the reflecting layer  3 , the possible influence of the powdered materials to the driving motor  21  during the operation of the apparatus A can be decreased, resulting in a smooth operation. In addition, the recovering of noble metals such as gold constituting the reflecting layer  3  can be easily performed. 
     In a case where the optical disk transferring device  40  for transferring the optical disk D from the optical disk storing portion  10  to the abrader  29  and the abraded disk substrate transferring device  40  for transferring the abraded disk substrate  1  to the abraded disk substrate storing portion  50  are a common transferring device, the structure of the optical disk substrate recovering apparatus A can be simplified. 
     The present invention claims a priority based on Japanese Patent Application No. 11-92299 filed on Mar. 31, 1999, the content of which is incorporated hereinto by reference in its entirety. 
     The terms and descriptions in this specification are used only for explanatory purposes and the present invention is not limited to these, but many modifications and substitutions may be made without departing from the spirit of the scope of the present invention which is defined by the appended claims.