CN101405807A - Optical disc having a reduced planar thickness - Google Patents

Abstract

In accordance with the teachings of the present invention, an optical disc having a reduced planar thickness is provided. In accordance with a particular embodiment of the present invention, the optical disc includes a central clamping area that defines a central aperture operable to be engaged by a spindle mechanism of an optical disc drive, an optically-readable data storage area substantially surrounding the central clamping area, the optically-readable data storage area having a planar thickness of less than 1.20 mm, and one or more stacker elements coupled to, or integral with, the central clamping area, the stacker elements configured to increase the thickness of the central clamping area above the planar thickness of the optically-readable data storage area. In particular embodiments, the optical disc may further include a magnetic stripe disposed upon one surface of the optical disc.

Description

Optical disc with reduced planar thickness

Cross References to Related Applications

This application claims priority to the following patent applications: U.S. Provisional Application No. 60/658,121, filed March 3, 2005; U.S. Provisional Application No. 60/724,450, filed October 7, 2005; February 2006 U.S. Provisional Patent Application No.____ filed on the 13th; and U.S. Patent Application No.____ filed on February 27, 2006.

technical field

The present invention relates generally to optically readable media and, more particularly, to optical discs having a reduced planar thickness.

Background technique

Optical discs, such as compact discs ("CDs") and digital video discs ("DVDs"), are often used for storing computer readable information. Typically, this information is stored on an optical disc in the form of a single track consisting of "lands" and "pits" that spiral outward from the center of the disc. These lands and pits can be read by an optical disc drive using a tightly focused laser beam. By reading these lands and pits, an optical disc drive can generate voltages that are matched with timing signals to produce a computer-readable binary stream.

Magnetic stripe cards, such as credit and debit cards, are also used to store computer readable information. Typically, such magnetic stripe cards comprise a plastic card with a magnetic strip comprising a magnetically sensitive material. Information (such as credit card account numbers) is then stored on the magnetic strip using conventional magnetic technology. The information encoded on the magnetic strip can then be read by "swiping" the card through a reader that has a magnetic head that senses the magnetic polarity encoded on the magnetic strip.

Previous attempts have been made to combine optical disks and magnetic stripes into a single data storage device. For example, U.S. Patent No. 6,597,653 to Burnett discloses an interactive transaction card that combines these two computer readable media in a single card with magnetically and optically readable memory . However, combining optical and magnetic readable memory into a commercially usable transaction card requires that the resulting transaction card be thin enough to be read by a conventional magnetic stripe reader, which reads The device can only swipe those cards whose thickness is less than about 0.96mm. Accordingly, conventional magnetic stripe cards typically have a planar thickness of from about 0.80 mm to about 0.86 mm. However, a conventional optical disc has a planar thickness of 1.20 mm. In reducing the planar thickness of these discs below 1.20mm, some optical drives struggle with storing There may be problems reading the data for .

Contents of the invention

According to the teachings of the present invention there is provided an optical disc having a reduced planar thickness. According to one embodiment of the invention, an optical disc includes a central clamping region defining a central aperture operable to engage a spindle mechanism of an optical disc drive; an optically readable data storage region substantially surrounding the central clamping a holding area having a planar thickness of less than 1.20 mm; and one or more stacker elements connected to or integral with the central holding area , the one or more stacker elements are arranged to increase the thickness of the central clamping region to be greater than the planar thickness of the optically readable data storage region. In some embodiments, the optical disc may also include a magnetic stripe disposed on one surface of the optical disc.

Technical advantages of certain embodiments of the present invention include enabling optical discs to have a reduced planar thickness with little or no reduction in the readability of data stored on the disc. For example, optical discs according to the teachings of the present invention typically have a planar thickness of less than 1.20 mm, and in some cases less than or equal to about 0.58 mm. To prevent the reduced planar thickness from adversely affecting disc readability, particular embodiments of the invention include one or more stacker elements attached to or integral with the central clamping area . These stacker elements may assist in positioning the disc relative to the read laser of the disc drive and/or facilitate chucking/engagement of the disc with the spindle mechanism of the disc drive.

Another technical advantage of various embodiments of the present invention includes that an optical disc has a magnetic stripe that allows the disc to store both optically and magnetically readable information. Due to the reduced disc thickness, embodiments of the invention can be "swiped" past conventional "swipe" magnetic card readers with little or no adverse effect on the optical disc or magnetic card reader.

Other technical advantages of the present invention can be more easily understood from the following drawings, description and claims. Additionally, while some specific advantages have been enumerated above, various embodiments may include all, some, or none of the enumerated advantages.

Description of drawings

In order to have a more complete understanding of the present invention and its features and advantages, the following detailed description will now be described in conjunction with the accompanying drawings, in which:

Figure 1A illustrates the optically readable side of an optical disc having a reduced planar thickness in accordance with an embodiment of the present invention;

Figure 1B illustrates a perspective view of the optically readable side of the optical disc shown in Figure 1A;

Figure 1C illustrates a perspective view of the non-optical readable side of the optical disc shown in Figures 1A and 1B;

Figure 1D illustrates a side cross-sectional view of the optical disc shown in Figures 1A-1C;

2A-2C illustrate plan views of different optical disc shapes that may be used in accordance with some embodiments of the invention;

Figure 3 illustrates an optical disc including a stacker disc, according to a specific embodiment of the invention;

Figure 4 illustrates an optical disc including a stacker ring, according to a specific embodiment of the present invention;

Figure 5 illustrates an optical disc comprising a plurality of stacker bars, according to a specific embodiment of the present invention.

Detailed ways

According to the teachings of the present invention there is provided an optical disc having a reduced planar thickness. According to a specific embodiment of the present invention, the optical disc includes a central clamping area, an optically readable data storage area, and one or more stacker elements, wherein the central clamping area defines a a central aperture for engaging a spindle mechanism of an optical disc drive, said optically readable data storage area substantially surrounding a central clamping area, having a planar thickness of less than 1.20 mm, said one or more stacker elements being attached to the central clamping area or Integral with this region, the stacker element is arranged to increase the thickness of the central clamping region to be greater than the planar thickness of the optically readable storage region. In various embodiments, the optical disc may further include a magnetic stripe disposed on at least one surface of the optical disc. By reducing the planar thickness of the optical disc to less than 1.20 mm, embodiments of the present invention are able to successfully pass through a "swipe" type magnetic stripe reader. Additionally, the inclusion of one or more stacker elements in the central clamping region helps to make the optical disc readable in conventional optical disc drives despite the reduced thickness of the optical disc.

1A-1D illustrate an optical disc 100 according to a specific embodiment of the present invention. 1A and 1B illustrate a plan view and a perspective view of the optically readable side 102 of the optical disc 100, respectively, FIG. 1C illustrates a perspective view of the non-optical readable side 104 of the optical disc 100, and FIG. side view sectional view.

As shown in FIGS. 1A-1D , optical disc 100 generally includes a central clamping region 108 that defines a central aperture 106 that is engageable with a spindle mechanism of an optical disc drive. The central clamping area 108 is radially surrounded by an optically readable data storage area 110 comprising information encoded in the form of pits and lands on the optical disc which are readable by an optical disc drive. of. In particular embodiments, the data storage area 110 may include embedded data that may be used to optimize, or at least affect, the read speed at which the optical disc drive attempts to read the optical disc 100 .

Generally, the optical disc 100 has a planar thickness of less than 1.20 mm. In some embodiments of the present invention, the optical disc 100 has a planar thickness less than or equal to about 0.95 mm. In some embodiments of the present invention, the optical disc 100 has a planar thickness less than or equal to about 0.85 mm. In some embodiments of the present invention, the optical disc 100 may have a planar thickness less than or equal to about 0.58 mm. In some embodiments of the present invention, optical disc 100 may have a planar thickness of from about 0.80 mm to about 0.86 mm.

As mentioned above, some optical disc readers may have difficulty storing data on optical discs less than 1.20mm thick due to issues with clamping/engaging the disc and/or focusing the optical drive's read laser to the correct depth in the disc. data to read. To alleviate and/or overcome this problem, the optical disc 100 also includes a plurality of stacker elements 122 connected to or integral with the central clamping area 108 . In some embodiments of the invention, stacker element 122 is formed as part of the injection molding process used to form optical disc 100 . In other embodiments, the stacker element 122 may be attached to the optical disc 100 after injection molding. Regardless of the method used to form the stacker element 122 , the stacker element 122 may increase the thickness of the clamping region 108 to be greater than the thickness of the optical data storage region 110 . In some embodiments, these stacker elements 122 may increase the thickness of the central clamping region 108 such that the total thickness of the central clamping region 108 and stacker elements 122 is approximately 1.20 mm (i.e. the thickness of a conventional optical disc) or greater . In some embodiments of the invention, this increased thickness facilitates clamping/engagement of the optical disc 100 by the optical disc drive. In some embodiments, the increased thickness also aids in the positioning of the optical data storage area 110 relative to the optical disc drive's read laser, helping to ensure that the reader's laser is focused to the proper depth for reading the stored data. data on disc.

As shown in FIGS. 1A-1B , the optical disc 100 includes four stacker elements 122 radially outward from the central hole 108 toward the optical data storage area 110 . It should be appreciated, however, that any suitable number, shape, and/or arrangement of stacker elements 122 may be used in accordance with the teachings of the present invention. Accordingly, "stacker element" as used herein means any suitable stacker element including, but not limited to, stacker trays, stacker rings, stacker bars, and/or stacker columns. 3A-5B further illustrate some examples of such stacker elements that may be used in accordance with the present techniques.

3A and 3B illustrate the optically readable side of an optical disc 300 featuring a stacker disc 322 in accordance with an embodiment of the present invention. Similar to optical disc 100 ( FIGS. 1A-1D ), optical disc 300 also includes a central clamping region 308 that defines a central aperture 306 configured to engage a spindle mechanism of an optical disc drive. The optical data storage area 310 radially surrounds the central clamping area 308 and stores data in the form of pits and lands that can be read by the read laser of the optical disc drive. The stacker tray 322 is connected to or integral with the central clamping area 308 and is arranged such that the planar thickness of the central clamping area 308 is increased to be greater than the planar thickness of the optical data storage area 310 . The stacker tray 322 is called a "pan" because its width is much greater than its height, and because it covers a large portion of the central clamping area 308 . In some specific embodiments of the invention, the stacker tray 322 may cover substantially the entire central clamping area 322 . In other embodiments, the stacker tray 322 need only cover a useful portion of the central clamping area 308 .

4A-4B illustrate the optically readable side of an optical disc 400 featuring a stacker ring 422 in accordance with an embodiment of the present invention. Similar to optical disc 300 (FIGS. 3A-3B), optical disc 400 also includes a central clamping region 408 that defines a central aperture 406 configured to engage a spindle mechanism of an optical disc drive. The optical data storage area 410 radially surrounds the central clamping area 408 and stores data in the form of pits and lands that can be read by the read laser of the optical disc drive. Stacker ring 422 is connected to or integral with central clamping region 408 and is configured to increase the planar thickness of central clamping region 408 to be greater than the planar thickness of optical data storage region 410 . Unlike the stacker tray 322 ( FIGS. 3A-3B ), the stacker ring 422 has a generally annular configuration. In some embodiments of the invention, stacker ring 422 may be concentric with central bore 406 . Although only one stacker ring 422 is illustrated in FIGS. 4A-4B , those skilled in the art will appreciate that multiple stacker rings 422 may be used, as well as rings of different radial thicknesses, without departing from the teachings of the present invention. Stacker ring.

5A and 5B illustrate the optically readable side of an optical disc 500 featuring a stacker bar 522 in accordance with an embodiment of the present invention. Similar to optical discs 300 and 400 (FIGS. 3A-4B), optical disc 500 also includes a central clamping region 508 that defines a central aperture 506 configured to engage a spindle mechanism of an optical disc drive. The optical data storage area 510 radially surrounds the central clamping area 508 and stores data in the form of pits and lands that can be read by the read laser of the optical disc drive. A plurality of stacker bars 522 are connected to or integral with the central clamping region 508 and arranged to increase the planar thickness of the central clamping region 508 to be greater than the planar thickness of the optical data storage region 510 . As shown in FIGS. 5A and 5B , the optical disc 500 includes three stacker bars 522 arranged about 120° apart from each other. However, those skilled in the art will appreciate that other numbers of stacker bars 522 may also be used in accordance with the teachings of the present invention. In addition, according to the teaching of the present invention, other stacker 522 arrangements may also be used, including symmetrical arrangements and asymmetric arrangements.

3A-5B illustrate several variations in the shape and configuration of stacker elements that may be employed in accordance with the teachings of the present invention. Through the disclosure of the present invention, those skilled in the art should be able to think of other suitable shapes and configurations of the stacker according to the teaching of the present invention.

Referring again to FIGS. 1A-1D , specific embodiments of the optical disc 100 may further include a magnetic strip 116 ( FIG. 1C ) disposed on at least one surface of the optical disc. In such embodiments, the optical disc 100 may also be used to store magnetically encoded information. In some embodiments, such magnetically encoded information may include credit card account number information, debit card account number information, personally identifiable information, and/or other information. This allows the optical disc 100 to be used as a conventional credit card, debit card, or personal identification card, since an embodiment of the optical disc 100 is thin enough to pass through a conventional "swipe" type magnetic stripe reader. Additional information related to incorporating magnetic stripes into optical discs can be found in US Patent No. 6,597,653 to Burnett, which is hereby incorporated by reference.

Typically, a magnetic strip 116 is disposed on the non-optical readable side 104 of the optical disc 100 . This helps prevent the magnetic stripe 116 from interfering with the readability of data stored in the optical data storage region 110 of the disc 100 . However, in some embodiments of the invention, the magnetic strip 116 may be located on the optically readable side 102 of the optical disc 100 . In such an embodiment, the magnetic strip 116 must be positioned so as not to interfere with the readability of the data stored in the optical data storage area 110 .

To facilitate reading of the magnetic stripe 116 by a magnetic stripe reader, in some embodiments of the invention, the optical disc 100 may include one or more straight edges 114 . In such an embodiment, the magnetic strip 116 is applied to the optical disc 100 generally parallel to and proximate to the straight edge 114 . This allows the magnetic stripe 116 to be read during the linear motion of the optical disc 100 past the magnetic stripe reader.

In order to more easily read the optical disc 100 with a magnetic stripe reader, some embodiments of the present invention may position the stacker element 122 (FIGS. 1A-1B) so that the stacker element 122 does not interfere with the optical disc 100 passing through the "swipe" mode. Movement of the magnetic stripe reader. For example, the stacker elements may be positioned in the central clamping region 108 farther from the straight edge 114 and closer to the lateral centerline of the optical disc 100 as shown in FIGS. 1A and 1B .

Some embodiments of the invention may also smooth the surface of the stacker element 122 so that there are no sharp changes in the thickness of the central clamping region 108 above the thickness of the optical data storage region 110 . This helps prevent the stacker element 122 from snagging on other surfaces and helps prevent chipping, breaking or damage to the optical disc 100 or objects that may come into contact with the optical disc 100 .

As mentioned above, the optical disc 100 may include one or more straight edges 114 . As shown in FIGS. 1A-1C , the optical disc 100 actually includes two straight edges 114 that are parallel to each other. The optical disc 100 also includes two curved edges 112 that are configured to conform to the curvature of conventional round optical discs. In some embodiments, the inclusion of curved edge 112 facilitates placement of optical disc 100 in the tray of a conventional optical disc drive. With two straight edges 114 and two curved edges 112, the optical disc 100 may be said to have a hybrid shape or "hockey rink" shape. It should be understood, however, that optical disc 100 may comprise a variety of shapes, which are consistent with the teachings of the present invention.

2A-2C illustrate examples of other optical disc shapes that may be used in accordance with the present invention. 2A-2C each illustrate an optical disc 200 according to a specific embodiment of the present invention. As shown in FIGS. 2A-2C , each optical disc 200 includes a central hole 206 , two parallel straight ends 214 and two curved ends 212 . As noted above, the inclusion of straight end 214 facilitates swiping of optical disc 200 over conventional "swipe" type magnetic stripe readers. However, other apparent shapes for the optical disc 200 may also be determined by various design considerations, including aesthetics.

1A-1D, since the optical disc 100 can be used as a credit card, debit card or personal identification card, some embodiments of the optical disc 100 can also include other identification information on the non-optical readable side 104 of the optical disc 100. For example, in some specific embodiments, the optical disc 100 may further include a signature block 118 for allowing users to sign their names on the signature block 118 . This allows the merchant to compare the signature of the person attempting to use the optical disc 100 with the authorized user's signature. In some specific embodiments, the optical disc 100 may further include a barcode 120, and the barcode 120 contains more information related to the optical disc and/or the user. For example, in some embodiments, barcode 120 may include a UPC code or barcode representing the disc owner's name and/or account number. The remainder of the side 104 of the disc 100 may be used to display indicia or other graphics. Although identification information (such as signature block 118, barcode 120, and graphics or indicia) has been discussed above with respect to the non-optical readable side 104 of the optical disc 100, those skilled in the art will appreciate that these and other features may also be present on the optical disc. The optically readable side 102 of 100 as long as these features are positioned so as not to restrict the readability of the data stored in the optical data storage area 110 .

Due to the reduced thickness of the optical disc according to the invention, some embodiments of the optical disc may also have a lower mass. This reduction in mass can be problematic for weight sensitive optical disc drives. In particular, the discs of some embodiments of the present invention may be too light to be perceived for such weight sensitive disc drives. To ensure that the disc can be read by these weight-sensitive disc drives, embodiments of the present invention may also include a label on the non-optical readable side 104 of the disc 100 configured to increase the mass of the disc 10 to approximately The quality of traditional discs. In some embodiments, the label is designed to include additional mass near the edge of the disc where the extra mass has a greater effect on the disc being rotated by the disc drive. In addition to applying the extra mass in the form of a label, other embodiments of the invention may embed the extra mass in the disc itself. In such an embodiment, the extra mass may also be included near the edge of the disc, where the extra mass has a greater effect.

Some embodiments of the invention may also include a label attached to the non-optical readable side 104 of the optical disc 100, the label being configured to increase the thickness of the optical disc. In such an embodiment, the thickness of the label may be selected to achieve a desired disc thickness that is greater than the thickness of the disc itself. For example, a 0.10mm thick label can be attached to a 0.65mm thick disc to obtain a 0.75mm thick labeled disc. Likewise, the use of labels that increase the thickness of the disc allows the user greater flexibility in achieving the final disc thickness.

Some embodiments of the present invention may also include a resilient metal layer attached to the non-optical readable side 104 of the optical disc 100 . Such an elastic metal layer can be used to increase the rigidity of the optical disc. This higher stiffness could help improve the disc's durability and facilitate its use as a magnetic stripe card.

Generally, the optically readable side 104 of the optical disc 100 is composed of polycarbonate or other suitable material, which may be transparent or colored. For example, in some embodiments of the invention, the polycarbonate or other material may be of any suitable color, such as black or yellow. In embodiments where the polycarbonate or other material is colored, the material color can be selected to give the material a desired refractive index. Thus, in such embodiments, the material color can be selected to change the depth at which the read laser of the optical disc drive is focused and/or to change the angle at which the laser light is reflected off the pits and/or lands of the optical disc. By selecting a material to adjust the refractive index of that material, some embodiments of the invention may provide enhanced readability. Given the disclosure of this application, one of ordinary skill in the art should be able to select the color to obtain the appropriate refractive index given the thickness of the optical disc.

Although specific embodiments of the method and apparatus of the present invention have been illustrated in the drawings and the foregoing detailed description, it should be understood that the invention is not limited to the specific embodiments disclosed, without departing from the scope of the invention as set forth and defined by the claims. Many adaptations, changes and substitutions are possible within the spirit of the invention.

Claims (37)

1. CD comprises:

Central authorities' clamping zone defines medium pore, and described medium pore can be operated to engage with the mainshaft mechanism of CD drive;

Light readable data storage area, around described central clamping zone, described smooth readable data zone has the planar thickness less than 1.20mm substantially; With

One or more position stacker elements, described one or more position stacker elements is connected to described central clamping zone or forms one with described central clamping zone, and described one or more position stacker elements are arranged to make the thickness of described central clamping zone to increase to planar thickness greater than described smooth readable data storage area.

2. CD according to claim 1, wherein, the planar thickness of described smooth readable data storage area is less than or equal to about 0.95mm.

3. CD according to claim 1, wherein, the planar thickness of described smooth readable data storage area is less than or equal to about 0.85mm.

4. CD according to claim 1, wherein, the planar thickness of described smooth readable data storage area is less than or equal to about 0.58mm.

5. CD according to claim 1, wherein, the planar thickness of described smooth readable data storage area from about 0.80mm to about 0.86mm.

6. CD according to claim 1, wherein, described one or more position stacker elements are arranged to make the distance that reads between the laser instrument of described smooth readable data storage area and CD drive to increase.

7. CD according to claim 1, wherein, described one or more position stacker elements are arranged for ease of described medium pore and engage with the described mainshaft mechanism of described CD drive.

8. CD according to claim 1, wherein, described one or more position stacker elements comprise stacker plate, described stacker plate centers on described medium pore substantially and covers a surface of described clamping zone substantially.

9. CD according to claim 1, wherein, described one or more position stacker elements comprise from the radially outside radial one or more stacker bars of described medium pore.

10. CD according to claim 1, wherein, described one or more position stacker elements comprise the stacker ring concentric with described medium pore.

11. CD according to claim 1 also comprises magnetic stripe, described magnetic stripe is arranged on the surface of described CD.

12. CD according to claim 11, wherein, described magnetic stripe is arranged on the light readable side of described CD.

13. CD according to claim 11, wherein, described magnetic stripe is arranged on the non-smooth readable side of described CD.

14. CD according to claim 1 also comprises the code that embeds in the described smooth readable data storage area, described code can be operated to influence the reading speed of described CD drive.

15. CD according to claim 1 also comprises the label that is connected with the non-smooth readable side of described CD, described label is arranged to make the quality of described CD to increase.

16. CD according to claim 1 also comprises the label that is connected with the non-smooth readable side of described CD, described label is arranged to make the planar thickness of described CD to increase.

17. CD according to claim 1 also comprises the elastic metal layer that is connected with the non-smooth readable side of described CD, described elastic metal layer is arranged to make the rigidity of described CD to increase.

18. CD according to claim 1, wherein, described CD comprises polycarbonate, the selected refractive index to obtain expecting of the color of described polycarbonate.

19. CD according to claim 1, wherein, described CD comprises polycarbonate, and the color of described polycarbonate is selected to strengthen the readability of described CD.

20. a CD comprises:

Central authorities' clamping zone defines medium pore, and described medium pore can be operated to engage with the mainshaft mechanism of CD drive;

Light readable data storage area, around described central clamping zone, described smooth readable data zone has the planar thickness less than 1.20mm substantially;

One or more position stacker elements, described one or more position stacker elements is connected to described central clamping zone or forms one with described central clamping zone, and described one or more position stacker elements are arranged to make the thickness of described central clamping zone to increase to planar thickness greater than described smooth readable data storage area; And magnetic stripe, be arranged on the surface of described CD.

21. CD according to claim 20, wherein, the planar thickness of described smooth readable data storage area is less than or equal to about 0.95mm.

22. CD according to claim 20, wherein, the planar thickness of described smooth readable data storage area is less than or equal to about 0.85mm.

23. CD according to claim 20, wherein, the planar thickness of described smooth readable data storage area is less than or equal to about 0.58mm.

24. CD according to claim 20, wherein, the planar thickness of described smooth readable data storage area from about 0.80mm to about 0.86mm.

25. CD according to claim 20, wherein, described one or more position stacker elements are arranged to make the distance that reads between the laser instrument of described smooth readable data storage area and CD drive to increase.

26. CD according to claim 20, wherein, described one or more position stacker elements are arranged for ease of described medium pore and engage with the described mainshaft mechanism of described CD drive.

27. CD according to claim 20, wherein, described one or more position stacker elements comprise stacker plate, and described stacker plate centers on described medium pore substantially and covers a surface of described clamping zone substantially.

28. CD according to claim 20, wherein, described one or more position stacker elements comprise from the radially outside radial one or more stacker bars of described medium pore.

29. CD according to claim 20, wherein, described one or more position stacker elements comprise the stacker ring concentric with described medium pore.

30. CD according to claim 20, wherein, described magnetic stripe is arranged on the light readable side of described CD.

31. CD according to claim 20, wherein, described magnetic stripe is arranged on the non-smooth readable side of described CD.

32. CD according to claim 20 also comprises the code that embeds in the described smooth readable data storage area, described code can be operated to influence the reading speed of described CD drive.

33. CD according to claim 20 also comprises the label that is connected with the non-smooth readable side of described CD, described label is arranged to make the quality of described CD to increase.

34. CD according to claim 20 also comprises the label that is connected with the non-smooth readable side of described CD, described label is arranged to make the planar thickness of described CD to increase.

35. CD according to claim 20 also comprises the elastic metal layer that is connected with the non-smooth readable side of described CD, described elastic metal layer is arranged to make the rigidity of described CD to increase.

36. CD according to claim 20, wherein, described CD comprises polycarbonate, the selected refractive index to obtain expecting of the color of described polycarbonate.

37. CD according to claim 20, wherein, described CD comprises polycarbonate, and the color of described polycarbonate is selected to strengthen the readability of described CD.

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