Abstract:
A Flexible VCD Having Domed Center and Method of Making Thereof is disclosed. The disc will has a flat data storage section of its substrate that is less than 0.7 millimeters thick, while the central region of the disc is defined by a dome structure adjacent to the spindle aperture that is of standard digital disc thickness. The disc is thin enough such that its substrate is flexible. The dome structure is shaped to provide the widest compatibility with player/recorders, as well as with disc printing systems. Disc versions are available that provide conical dome structures, as well as slivered dome structures of both conical and rectangular cross-section. The method for manufacturing the discs simply requires the replacement of the conventional stamper holder with a stamper holding having a non-flat face.

Description:
[0001]    This application is a continuation-in-part of application Ser. No. 11/799,208, filed Apr. 30, 2007, now pending. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates generally to digital recording media and, more specifically, to a Flexible VCD Having Domed Center and Method of Making Thereof. 
         [0004]    2. Description of Related Art 
         [0005]    Portable storage of digital electronic data is a rapidly-developing field. The focus of the present invention is that of laser-readable (and writable) discs. Laser-readable disc types are generally Compact Discs (including CDs-prerecorded, CDRs-recordable, and CDRWs-rewritable) and Digital Video Discs (including DVDs-prerecorded, DVRs-recordable, and DVRWs-rewritable). Each of these disc designs and formats have similar basic structural configurations, as depicted in  FIG. 1 . 
         [0006]      FIG. 1  is a perspective view of a conventional laser-readable disc  10 . The conventional disc  10  has a plastic substrate  12  defined by a central spindle hole  14  formed therethrough. Standard CDs and DVDs have a substrate  12  defined by a 120 millimeter diameter  16  and a thickness  18  of 1.2 millimeters. While the standard disc  10  has a perimeter edge  20  that is circular, other shapes (and sizes) are readily available—of particular note is the business-card-sized disc. Data is stored on the disc via a laser readable (and optionally writable and rewritable) surface depicted here as the data storage area  21 . The basics of the laser reading/writing technology will be discussed in connection with  FIG. 2 . 
         [0007]      FIGS. 2A and 2B  are partial cutaway side views of conventional compact and digital video discs, respectively. The conventional compact disc (CD, CDR, CDRW)  10 A is defined by a substrate  12  having a thickness  18  that is 1.2 millimeters both at the perimeter edge  20  and at the central spindle hole  14 . The substrate  12  is further defined by a top (recording) surface  22  and a bottom (read) surface  24 . This is to say that the disc player/recorder&#39;s laser projects upwardly towards the disc substrate  12  from the bottom (at least in the depicted orientation). The laser light actually passes through the substrate  12  until it is reflected back by the bottom side of the top (recording) surface  22 . The digital data is stored as a sort of texture on the top (recording) surface  22 ; the texture effects the way in which the laser light is reflected back down to the laser reader, which is interpreted as data in a standardized format. Of course other important elements are a part of CDs and DVDs, such as the type of reflective coating applied to the recording surface (which can determine whether the disc is rewritable or recordable), as well as any decorative films or colorations applied above that. 
         [0008]      FIG. 2A  depicts the structure of a conventional digital video disc (DVD, DVR, DVRW). The conventional DVD is actually comprises of two thin discs bonded together. While the overall disc thickness  18  is 1.2 millimeters at the perimeter edge  20  and the spindle hole  14 , this overall substrate thickness is actually made up of a top substrate element  12 A bonded atop the bottom substrate element  12 B. The bottom substrate element  12 B is actually the data-storing portion of the disc  10 B. The top (recording) surface  22  is actually the top surface of the bottom substrate element  12 B. Of course, the bottom (read) surface  24  is the bottom surface of the bottom substrate element  12 B. The bottom substrate element  12 B has a disc thickness of 0.6 millimeters, which means that the depth of the disc as read by the laser is only 0.6 millimeters. 
         [0009]    The top substrate element  12 A, which is also 0.6 millimeters thick, provides really no functional benefit to the disc  10 B beyond making it stiffer than the bottom substrate  12 B alone would be, and further providing the additional thickness necessary to provide an overall disc thickness  18  of 1.2 millimeters. 
         [0010]    A critical aspect of the configuration of CDs and DVDs is the thickness of the disc substrate directly adjacent to the spindle hole  14 . When a disc is loaded for playing/recording in a disc player, the player will actually clamp down on the disc over the spindle hole  14 . The player will then conclude by that the disc top surface  22  or  26  is at the same level as the top of the disc clamp. The laser will then be energized to determine the disc depth/thickness to the top (recording) surface  22 . In the case of a CD  10 A, the player/recorder will detect a depth of 1.2 millimeters, while in the case of a DVD  10 B, the player/recorded will detect a depth of 0.6 millimeters. This detected depth is a way for the player/recorder to confirm whether the disc is a CD or a DVD. As such, conventional CD and DVD players and recorders rely upon the thickness of the disc under the disc clamp (in the player) to determine whether a CD or a DVD is being read. If there is a non-standard depth, or a non-standard disc thickness  18  adjacent to the spindle hole  14 , the error will prevent the disc from being reliably read on all player/recorders. 
         [0011]    As discussed above, the extra substrate element included with a conventional DVD is not involved in the actual data recording and reading (at least beyond giving the player its initial focus check). There are, however, limitations to the usefulness of the DVD introduced because of this extra thickness. First, if the DVD was thinner (i.e. 0.6 millimeters), it would be flexible. A flexible DVD could be very popular in the context of mass mail advertising (such as in magazines); now the discs have to remain flat. Furthermore, the second substrate is simply wasted material; its elimination would be cost effective and more environmentally conscious. Finally, less material will reduce mold processing time as well as eliminating a production step involving the bonding of the top substrate element  12 A to the bottom substrate element  12 B. 
       SUMMARY OF THE INVENTION 
       [0012]    In light of the aforementioned problems associated with the prior systems and methods, it is an object of the present invention to provide a Flexible VCD Having Domed Center and Method of Making Thereof. The preferred disc will have a flat data storage section of its substrate that is less than 0.7 millimeters thick, while the region of the disc should be defined by a dome structure adjacent to the spindle aperture that is of standard digital disc thickness. The disc should be thin enough to allow its substrate to be flexible. The dome structure should be shaped to provide the widest compatibility with player/recorders, as well as with disc printing systems. Disc versions should be available that provide conical dome structures, as well as slivered dome structures of both conical and rectangular cross-section. The method for manufacturing the discs should be limited to replacing the conventional stamper holder with a stamper holding having a non-flat face. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The objects and features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages, may best be understood by reference to the following description, taken in connection with the accompanying drawings, of which: 
           [0014]      FIG. 1  is a perspective view of a conventional laser-readable disc; 
           [0015]      FIGS. 2A and 2B  are partial cutaway side views of conventional compact and digital video discs, respectively; 
           [0016]      FIG. 3  is a cutaway side view of a preferred embodiment of the flexible digital video disc of the present invention; 
           [0017]      FIGS. 4A and 4B  are top and bottom perspective views of the disc of  FIG. 3 ; 
           [0018]      FIG. 5  is an exploded cutaway side view of the mold assembly for a conventional digital video disc; 
           [0019]      FIG. 6  is a cutaway side view of the mold assembly of  FIG. 5  in its closed position; 
           [0020]      FIG. 7  is an exploded cutaway side view of the mold assembly for the disc of  FIG. 3 ; 
           [0021]      FIG. 8  is a cutaway side view of the mold assembly of  FIG. 7  in its closed position; 
           [0022]      FIG. 9  is a block diagram of the preferred method of making the flexible digital video disc of  FIG. 3 ; 
           [0023]      FIGS. 10A-10C  are top and partial cutaway side views, respectively, of a first alternative embodiment of the flexible digital video disc of the present invention; 
           [0024]      FIGS. 11A and 11B  are a top and a partial cutaway side view, respectively, of a second alternative embodiment of the flexible digital video disc of the present invention; 
           [0025]      FIGS. 12A-12C  are top and partial cutaway side views, respectively, of a third alternative embodiment of the flexible digital video disc of the present invention; and 
           [0026]      FIGS. 13A-13C  are top and partial cutaway side views, respectively, of a fourth alternative embodiment of the flexible digital video disc of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    The following description is provided to enable any person skilled in the art to make and use the invention and sets forth the best modes contemplated by the inventor of carrying out his invention. Various modifications, however, will remain readily apparent to those skilled in the art, since the generic principles of the present invention have been defined herein specifically to provide a Flexible VCD Having Domed Center and Method of Making Thereof. 
         [0028]    The present invention can best be understood by initial consideration of  FIG. 3 .  FIG. 3  is a cutaway side view of a preferred embodiment of the flexible digital video disc  30  of the present invention. Unlike the conventional digital video disc discussed above in connection with  FIG. 2B , this disc  30  is not of a uniform thickness across its cross-sectional profile. Instead, the disc  30  has a thin outer portion  36 , and a thick center portion  34 . Directly adjacent to the spindle hole, the disc thickness  46  is 1.2 millimeters, while the thin outer portion  36  of the substrate  32  is only 0.6 millimeters. 
         [0029]    The “domed” center portion  34  of this disc  30  exhibits a specific profile in its cross section. The thickness of the substrate  32  first begins to gradually thicken beginning at 45 millimeters from the perimeter edge  20  of the convention circular disc. This is precisely 55 millimeters from the center of the disc (a non-circular disc would use this center-centric dimension). The purpose of this thickened center portion  34  is to “fool” the digital disc player/recorder into believing that the entire disc  30  is of standard thickness (i.e. 1.2 millimeters). The profile of this embodiment of the domed center portion  34  is to slope upwardly to form a flat-topped cone, with the slope raising 0.6 millimeters (rise) over the span of 7.0 millimeters (run). While other profiles may be suitable, as will be discussed below in connection with  FIGS. 10-12 , this particular profile has been demonstrated to give substantial benefits. 
         [0030]    The thin outer portion  36  makes the disc  30  deformable, or “flexible,” which enables the disc  30  to be used in a wider variety of applications. Specifically, this flexible digital video disc  30  can be safely enclosed within a magazine without fear that curling the magazine will break the disc  30 . Now turning to  FIGS. 4A and 4B , we can see the entire form of the disc  30 . 
         [0031]      FIGS. 4A and 4B  are top and bottom perspective views of the disc  30  of  FIG. 3 . As discussed above, the center dome  34  in this disc version has a flat-topped conical shape defined by a sloped top surface  48  protruding upwardly from the top (recording) surface  40 . The shape of this center dome  34  has at least two significant benefits over any other versions of flexible digital discs—it has demonstrated universal compatibility with player/recorders, and it is compatible with standard disc printing processes (i.e. when indicia is added to the top surface  40  of the disc  30 , such as for labeling). 
         [0032]    Not all player/recorders clamp digital discs at the same location or in the same manner. Some player/recorders clamp directly adjacent to the spindle hole  14 , while others tend to have a wider clamping ring area. Furthermore, some clamps are not continuous around the circumference of the spindle hole  14 , but instead have a series of ridges or partial rings clamping down on the top of the disc. If a particular player/recorder does not “register” the correct 1.2 millimeter thickness of the disc, it will not play. The sloped top surface  48  of this embodiment of the disc  30  has proven to achieve universal compatibility with any and all player/recorders. 
         [0033]    Regarding the printing of indicia atop the top surface  40  of the disc  30 , the standard printing process involves the use of software to lay out the art work for the top of the disc, which then controls the printing or ink stamping of the indicia onto each disc. The software is designed to work with a standard, flat, smooth top surface  40 . Any sharp protrusions from the top surface  40  tend to interfere either with the layout of the artwork, or with the actual functioning of the print head or stamp. The sloped top surface  48  of this embodiment of the disc  30 , due to its gradual upslope and absence of sharp edges, has proven to be fully compatible with standard software and printing or stamping systems. Since the print function is conducted in mass production on standard equipment, it is critical that no special operational or equipment modifications are necessary. 
         [0034]    As depicted in  FIG. 4B , as with a standard CD or DVD, the disc  30  also has a centering ring  50  protruding downwardly from the bottom (read) surface  38  of the disc  30 . The centering ring  50  engages a cooperatively located groove in the platter of the player/recorder in order to assist in centering the disc  30  within the player/recorder. Now that we have discussed the structural aspects of the present disc  30  embodiment, we can turn to the novel production process by first discussing the prior art method of disc production. 
         [0035]      FIG. 5  is an exploded cutaway side view of the mold assembly  52  for a conventional digital video disc. The manufacturing process for a conventional digital disc is typically by injection molding. A pelletized plastic material is injected into a mold form; once full, the mold is heated to a predetermined temperature which causes the pellets or beads to expand and/or coagulate into a solid plastic piece. The molded disc is then cooled and removed from the mold. The top (recording) surface of the disc is molded either with the data (for laser reading) formed into it, or if a recordable or rewritable disc, the top (recording) surface is prepared with no data recorded therein. Later processing steps include the application of specialized metalized layers atop the plastic top surface of the disc, which enables the laser to read and/or record the data on the top (recording) surface of the disc. 
         [0036]    The conventional mold assembly  52  is comprised of a stationary mold half  54  and a moving mold half  56 . In the depicted version, the bottom half is stationary and the top half is moving (or movable), however a variety of equipment types are available (e.g. the moving and stationary halves could be the reverse from that depicted here), and the depicted arrangement is only one example. 
         [0037]    The stationary mold half  54  has a recessed section  58 , which generally is the mold form for the bottom (read) surface of the disc. Although not depicted here, there would normally be a groove in the bottom surface of the recessed portion  58  to create the centering ring (see  FIG. 4B ) in the bottom surface of the disc. The plastic beads are injected into the mold  52  via the plastic injection port  60 , shown here generally centered in the stationary mold half  54 . 
         [0038]    The moving mold half  56  also has a recessed section  72 , however this section  72  does not create a molded surface of the disc, but rather is a “pocket” for receiving a stamper  68 . The stamper  68  is the form to create the top surface of the disc. The molding equipment must be standardized to form the perimeter and bottom surface disc shape, but the top surface of the disc must be customizable so that the same molding equipment can produce custom discs (e.g. prerecorded, recordable or rewritable). To change a disc&#39;s data or its recordability, only the top surface of the disc will be different from other discs. As such, only the stamper  68  need be changed to set up the equipment to run a different type (or having different prerecorded data thereon). 
         [0039]    The stamper  68  has a patterned face  70  that is a “negative” of the prerecorded data from the data master recording. The stamper  68  is held within the recessed section  72  of the moving mold half  56  by the stamper holder  62 . The stamper holder  62  has a head  64  that actually holds the stamper  68  within the recessed portion  72 . The head  64  is defined by a face  66  on its bottom side. As should be apparent, the face  66  forms a portion of the disc at its very center (that portion of the disc inside of the data recording zone), and generally is simply a flat smooth surface (or has a hole formed within it to allow a punch to form the spindle hole in the disc). Just prior to plastic injection, the mold assembly  52  will appear as shown in  FIG. 6 . 
         [0040]      FIG. 6  is a cutaway side view of the mold assembly  52  of  FIG. 5  in its closed position. Here, the moving mold half  56  is pressed against the stationary mold half  54  to form the disc mold  72 . The disc mold  72  is the void between the stamper patterned face  70  and stamper holder face  66  (on the top here) and the recessed portion formed within the stationary mold half  54 . Once closed, plastic beads are injected into the mold  72  via the plastic injection port  60 . The disc will be shaped as the “negative” of the disc mold  72 . Now turning to  FIG. 7 , we can examine how the disc of the present invention is manufactured using standard equipment. 
         [0041]      FIG. 7  is an exploded cutaway side view of the mold assembly  74  for the disc of  FIG. 3 . Virtually all of the components of the mold assembly  74  are unchanged from the conventional assembly of FIGS.  5  and  6 —the stationary mold half  54 , the moving mold half  56  (and their recessed sections  56  and  58 ), and even the stamper  69  are unmodified from the standard versions discussed above. The stamper  69  is shown here as being thicker than that shown in  FIGS. 5 and 6  because the disc being formed in this mold assembly  74  is thinner than a standard CD. In fact, it is the same thickness as the bottom substrate element (see  FIG. 2B ) of a DVD, which is the standard thickness for that type of disc. 
         [0042]    What is new here is the modified stamper holder  76 . The modified stamper holder  76  operates and is formed virtually identical to a conventional stamper holder, with one exception—the head  78  and face  80 . The modified stamper holder  76  has a domed face  80  to create the raised center portion of the disc of  FIG. 3 . As shown in  FIG. 8 , when the mold assembly  74  is in a closed position, the disc mold  82  will have a domed section centered in the top surface of the disc, with the disc itself being one-half the thickness of the CD-type disc shown in  FIGS. 5 and 6 . Turning to  FIG. 9 , we will see that the manufacturing method, while unique, is fully compatible with conventional manufacturing equipment. 
         [0043]      FIG. 9  is a block diagram of the preferred method  84  of making the flexible digital video disc of  FIG. 3 . First, the conventional stamper  68  (see  FIG. 5 ) is replaced with a modified stamper  69  (see  FIG. 7 ) if necessary, and the conventional stamper holder  62  (see  FIG. 5 ) is replaced with a modified stamper holder  76  (see  FIG. 7 )  100 . Next, the mold assembly  74  (see  FIG. 7 ) is assembled  102 , and the mold assembly  74  (see  FIG. 8 ) is closed  104 . Plastic beads are then injected  106  and the mold is heated  108  in order to form the disc  30  (see  FIG. 3 ). The mold is later opened  110  (sometimes after cooling and other processing), and the disc is removed  112 . 
         [0044]    The only step in the method  84  that really differs from the conventional disc manufacturing method is the first one identified (step  100 )—the exchange of the conventional stamper and stamper holder with modified stamper and stamper holder. No other modification to the conventional mold assembly is necessary. 
         [0045]    Having fully discussed first embodiments of the present invention, we will examine several alternate embodiments of the disc of the present invention, commencing with the disc shown in  FIGS. 10A-10C . 
         [0046]      FIGS. 10A-10C  are top and partial cutaway side views, respectively, of a first alternative embodiment  30 A of the flexible digital video disc of the present invention. The disc  30 A is formed in the same manner as discussed above in connection with  FIG. 9 , however the stamper holder face is formed so that a plurality of “dome slivers”  34 A, rather than a solid “dome” is formed adjacent to the spindle hole  14 . The outer thin portion  36 A will then actually reach the spindle hole  14  in alternating arcs around its circumference. There may be three or more slivers  34 A in spaced relation around the hole  14 . 
         [0047]    As shown in  FIG. 10B , each dome sliver  34 A may be sloped in its cross-sectional profile, just as with the first embodiment of the disc ( FIG. 3 ). Alternatively, as shown in  FIG. 10C , the slivers  34 A may have a sharp edge, rather than a sloped top surface. In either case, the method of  FIG. 9  will be suitable for forming the profile. 
         [0048]      FIGS. 11A and 11B  depict yet another preferred version  30 B of the disc of the present invention. Rather than a sloped dome, this version has a dome ring  34 B that is has squared edges and a thickness  35  of approximately 3 or 4 millimeters. This thin dome ring  34 B has been determined to be functional with many player/recorders, and tends to use less material than the first disc embodiment. 
         [0049]      FIGS. 12A-12C  depict another version  30 C of the disc of the present invention.  FIGS. 12A-12C  are top and partial cutaway side views, respectively, of this third alternative embodiment. This disc version  30 C is essentially a combination of the two versions shown in  FIGS. 10A-10C  and  11 A- 11 B, that is, there is a combination ring/sliver dome  34 C adjacent to the spindle hole  14 . The cross-section may be as shown in  FIG. 12B , with a central ring portion  34 B of 3-4 millimeters, from which sloped dome slivers  34 A extend radially. Alternatively, as shown in  FIG. 12C , the dome slivers  34 C may have squared edges. While more complex than the previous versions, this type will tend to be fully compatible with all player/recorders, while still providing modest material savings over the sloped dome version of  FIG. 3   
         [0050]    Finally,  FIGS. 13A-13C  are top and partial cutaway side views, respectively, of a fourth alternative embodiment  30 D of the flexible digital video disc of the present invention. The ring/sliver dome  34 C adjacent to the spindle hole  14  comprises a central ring portion  34 B surrounded by a plurality of dimple-shaped dome slivers  34 A in equal spaced relation, as shown. Here, there are three dimple-shaped dome slivers  34 A, positioned at 120 degree arc increments around the spindle hole  14 . 
         [0051]    As discussed above, the diameter of the spindle hole  14  is conventionally  15  millimeters. The central ring portion  34 B preferably extends from a 15 (fifteen) millimeter diameter at its inner edge to 19 (nineteen) or 20 (twenty) millimeters in diameter at its outer edge. The height of the central ring portion  34 B is preferably 0.6 millimeters (i.e. above the top surface of the disc  30 D). 
         [0052]    Each dimple-shaped dome sliver  34 A is circular in shape when viewed from atop the disc  30 D, with its center located at approximately the 32 (thirty-two) or 33 (thirty-three) diameter arcs. As mentioned earlier, where there are three dimple-shaped dome slivers  34 A, they will be equally spaced to surround the spindle hole  14  at a point that is separated from the adjacent dimple-shaped dome slivers  34 A by 120 degrees. In the depicted version, each dimple-shaped dome sliver  34 A has its own diameter of approximately 0.2 millimeters in diameter. 
         [0053]    As shown in  FIG. 13B , the outer edge of the central ring portion  34 B could have a sloped or curved edges. Another version is shown in  FIG. 13C , wherein the outer edge of the central ring portion  34 B is a sharp or square edge. 
         [0054]    Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiment can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.