JP2005216404A - Monolayer optical disk and double-sided optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a monolayer DVD disk of 12 cm diameter which can maintain compatibility with other disk drives and is thin and light in weight and high in productivity. <P>SOLUTION: A monolayer DVD which is 12 cm in diam. and thinner than 0.6 mm is realized by using a transparent base plate 0.55 mm thick or thicker but 0.57 mm thick or thinner obtained in the process of manufacturing a DVD disk of 12 cm diam. having two layers on a side. Further, by sticking a transparent base plate 0.57-0.643 mm thick used for a monolayer DVD disk of 12 cm diam. to the clamp area of this monolayer optical disk, the clamp area can be made almost the same thickness (approx. 1.2 mm) as specified in the DVD standards, and stable disk clamping can be secured in a disk drive. Moreover, by sticking the above monolayer DVD and a CD approximately 0.9 mm thick each other, the overall thickness of the DVD can be maintained at 1.5 mm or less which is the upperlimit stipulated in the DVD and CD specifications. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a single-layer optical disc such as a DVD (Digital Versatile disk) and a double-sided optical disc.

  The current DVD (DVD-ROM) single-layer disc is provided with a reflective layer having a thickness of several μm to several tens of μm on the information pit forming surface of a transparent substrate having a thickness of 0.57 mm to 0.643 mm. By sticking a transparent substrate of the same thickness on the side, the total thickness is made equal to the standard thickness (about 1.2 mm) of CD (Compact Disk). Thus, in a disk drive capable of multi-reproduction of CD and DVD, stable disk clamping by the clamping mechanism is guaranteed for both CD and DVD.

  In addition, since the upper limit thickness of DVD and CD standards is 1.5 mm, the disc drive clamping mechanism capable of multi-reproduction of CD and DVD can handle discs with a thickness of 1.5 mm without any problem. It is usually designed to guarantee.

  By the way, in recent years, there is also a disc (hereinafter referred to as “CD / DVD disc”) in which a music CD and a DVD containing live video and the like are bonded together. This CD / DVD dual-use disc is a DVD single-layer disc bonded with a CD thinned to a thickness of 0.9 mm, and the total thickness is around 1.5 mm, which is the usual upper limit of guarantee for disc drives. It has become.

For example, Japanese Patent Application Laid-Open No. H10-133707 discloses a technique for bonding two different types of optical disks together to integrate them. This Patent Document 1 describes an optical disc in which different types of DVD discs (DVD-R and DVD-RW) are bonded together.
JP 2000-215445 A (paragraphs 0019-0021)

  However, in the case of a disc for both CD / DVD, if the disc thickness of each CD / DVD is manufactured and the thickness of the adhesive layer is taken into consideration, the total thickness is the upper limit of the thickness in DVD and CD standards (1 .5 mm) in some cases, and there is a problem in that the production yield deteriorates.

  In view of the above situation, the present invention is compatible with existing disk drives, and is thinner and more productive with a single-layer optical disk and a double-sided optical disk, more specifically, a single-layer 12 cm diameter DVD disk and a 12 cm diameter. An attempt is made to provide a double-sided optical disc.

  In order to solve the above problems, the single-layer optical disc of the present invention has a thickness of 0.55 mm or more and less than 0.57 mm, and has a minimum pit length of 0.440 μm and a track pitch of 0.74 μm on one side. A transparent substrate on which information pits are formed, and a reflective layer provided on the information pit forming surface of the transparent substrate.

  Here, the thickness of the substrate of each layer obtained in the manufacturing process of the single-sided dual-layer 12 cm diameter DVD disc is in the range of 0.55 mm or more and less than 0.57 mm, and this is the transparent substrate of the single-layer disc of the present invention. As a result, a single-layer optical disk that is compatible with existing disk drives, thinner, and more productive can be realized.

  The single-layer optical disc of the present invention may further include a substrate for adjusting the thickness attached to the clamping area. By attaching a substrate for thickness adjustment to the clamping area and setting the thickness to, for example, about 1.2 mm, it is possible to stabilize the disk drive with strict restrictions on the minimum disk thickness that guarantees clamping. The effect that the disk clamp is guaranteed can be expected. For example, when a transparent substrate having a thickness of 0.57 mm to 0.643 mm for a conventional single layer 12 cm diameter DVD disk is used as a substrate for adjusting the thickness, the thickness of the clamping area is set to DVD and The value is close to the CD standard thickness (about 1.2 mm), and stable disc clamping in the disc drive clamping mechanism is guaranteed.

  Furthermore, the double-sided optical disc of the present invention has a thickness of 0.55 mm or more and less than 0.57 mm, and a first pit having a minimum pit length of 0.440 μm and a track pitch of 0.74 μm is formed on one surface. A single-layer optical disc having a transparent substrate and a second reflective layer provided on the information pit forming surface of the first transparent substrate, and a thickness greater than that of the first transparent substrate of the single-layer optical disc. A second transparent substrate that is large and has information pits formed on one side thereof, and a second reflective layer that is provided on the information pit forming surface of the second transparent substrate; And an optical disc bonded together.

  According to the double-sided optical disc of the present invention, the entire thickness is set to the upper limit thickness 1 in the DVD and CD standards by bonding a CD disc having a thickness of, for example, about 0.9 mm as an optical disc to a single-layer optical disc. It becomes easy to suppress to 5 mm or less, and a dual-use optical disk with a high production yield can be realized.

  According to the present invention, a single-layer optical disk and a double-sided optical disk that are compatible with existing disk drives, thinner, and more productive are realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing the configuration of a DVD disc that is a single-layer optical disc according to an embodiment of the present invention.

  This DVD disk 10 is a disk-shaped transparent substrate 11 having information pits formed on one surface, which is obtained by injection molding or the like using, for example, polycarbonate having a good light transmission property, and the transparent substrate 11 The reflective layer 12 is formed on the information pit recording surface by vapor deposition of aluminum, and a protective film (not shown) coated on the reflective layer 12.

  Here, the thickness h0 of the transparent substrate 11 is in the range of 0.55 mm or more and less than 0.57 mm, and the thickness of the reflective layer 12 and the protective film (not shown) is negligible with respect to the thickness of the transparent substrate 11 ( Several μm to several tens of μm). Therefore, the thickness of the entire DVD disk 10 is suppressed to less than 0.6 mm. In FIG. 1, the width of the reflective layer 12 is shown in a wider ratio than the actual width with respect to the width of the transparent substrate 11.

  That is, the thickness h0 of the transparent substrate 11 of the DVD disk 10 is about 0.02 mm thinner than the lower limit of the thickness of the conventional single-layer DVD disk.

  However, the spherical aberration of the light spot condensed on the disk increases as the transparent substrate 11 is made thinner. Spherical aberration refers to the position where the light rays near the optical axis and the position near the optical axis are collected in the optical axis direction. This is a distortion of the focus that shifts continuously, and the influence of the spherical aberration of the light spot on the reproduction signal or the like tends to increase as the wavelength of the laser for disk reproduction becomes shorter.

  Therefore, it is preferable to use the following transparent substrate.

  At present, single-layer DVD disks and multi-layer disks, particularly two-layer disks, are widely used. According to the standard, the capacity of a single layer 12 cm diameter DVD disc is 4.7 GB, the minimum pit length is 0.400 μm, and the maximum pit length is 2.054 μm. On the other hand, in the case of a single-sided dual-layer 12 cm diameter DVD disc, the thickness of each disc is in the range of 0.55 mm or more and less than 0.57 mm, which increases the spherical aberration of the light spot when compared with a single-layer DVD disc. Accordingly, the minimum pit length is 0.440 μm and the maximum pit length is 2.054 μm, which is larger than that of the single-layer disc. The track pitch is 0.74 μm for both single layer and double layer on one side. For this reason, the capacity of each layer in a single-sided dual layer 12 cm diameter DVD disc is 4.27 GB, which is smaller than that of a 12 cm diameter single layer DVD disc.

  In this embodiment, each transparent substrate before bonding obtained by the above-described single-sided dual layer 12 cm diameter DVD disk manufacturing process is used as the transparent substrate 11 of the DVD disk 10 of this embodiment. A reflective layer 12 is formed on the information pit recording surface of the transparent substrate 11 by aluminum vapor deposition or the like, and a protective film is coated on the reflective layer 12 to provide a single layer 12 cm diameter DVD disc 10 having a capacity of 4.27 GB. Have gained.

  As a result, a DVD disc 10 having a single-layer 12 cm diameter that is low in cost, excellent in productivity, thin and lightweight can be obtained. Such a DVD disk 10 can be suitably used particularly for media distributed in large quantities by mail, magazine appendix or the like.

  Next, an application example of the single layer 12 cm diameter DVD disk 10 shown in FIG. 1 will be described.

  2 and 3 show that only the clamping area 14 around the center hole 13 of the single layer 12 cm diameter DVD disk 10 shown in FIG. 1 has a thickness conforming to the DVD standard, for example, about 1.2 mm. This is a single-layer DVD disc 20 having a diameter of 12 cm and protruding from the information recording area 15. The information recording area 15 has a cross-sectional configuration similar to that of the single layer 12 cm diameter DVD disk 10 shown in FIG. That is, a disk-shaped transparent substrate 11 having information pits formed on one side thereof, a reflective layer 12 formed on the information pit recording surface of the transparent substrate 11 by aluminum vapor deposition, and further coated on the reflective layer. The protective film is not shown.

  In this way, by making only the clamping area 14 a thickness that conforms to the DVD standard, stable disc clamping is ensured in a disc drive in which the restriction on the minimum disc thickness that guarantees clamping is severe.

  As a method for obtaining such a DVD disc 20, the clamping area 14 on the reflective layer 12 side of the DVD disc formed using the transparent substrate 11 having a thickness h0 of 0.55 mm or more and less than 0.57 mm is used. The transparent substrate 16 having the same thickness or the transparent substrate of a conventional single-layer disc (thickness h1 is 0.57 mm to 0.643 mm) 16 formed in the outer shape corresponding to the clamping area 14 is bonded to the adhesive layer ( (Not shown) may be used. In particular, when a transparent substrate having a thickness of 0.57 mm to 0.643 mm for a single layer 12 cm diameter DVD disk is used, the thickness of the clamping area 14 is a thickness in accordance with the DVD standard (about 1.2 mm). ) And a stable disc clamp is guaranteed by the disc drive clamping mechanism.

  Further, FIG. 4 shows an adhesive layer of an optical disk having a larger thickness than the single-layer 12 cm diameter DVD disk 10 of the present embodiment shown in FIG. 1, for example, a 12 cm diameter CD disk 30 having a thickness h2 of 0.9 mm. This is a CD / DVD dual-use disc 40 obtained by bonding through (not shown). The 12 cm diameter CD disc 30 includes a disc-shaped transparent substrate 31 having information pits formed on one surface thereof, a reflective layer 32 formed by aluminum vapor deposition on the information pit recording surface of the transparent substrate 31, and the reflective layer. 32 is formed of a protective film or the like (not shown) coated on 32.

  The single-layer 12 cm diameter DVD disc 10 is configured based on the transparent substrate 11 having a thickness h0 in the range of 0.55 mm or more and less than 0.57 mm, and the overall thickness is suppressed to less than 0.6 mm. And a 0.9 mm thick 12 cm diameter CD disc 30, the thickness H of the entire disc is kept to a maximum thickness of 1.5 mm or less according to DVD and CD standards, even if the thickness of the adhesive layer is expected. be able to. Therefore, it is possible to realize a CD / DVD dual-use disc with a high manufacturing yield.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the scope of the present invention.

It is sectional drawing which shows the structure of the DVD disc which is a single layer optical disk concerning one Embodiment of this invention. It is a top view which shows the DVD disc which made the clamping area of the single layer 12 cm diameter DVD disc of FIG. 1 thick. It is sectional drawing of the DVD disc of FIG. FIG. 2 is a cross-sectional view of a CD / DVD dual-use disc in which the single layer 12 cm diameter DVD disc and the 12 cm diameter CD disc of FIG. 1 are bonded together.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... DVD disc, 11 ... Transparent substrate, 12 ... Reflective layer, 13 ... Center hole, 14 ... Clamping area, 15 ... Information recording area, 16 ... Transparent substrate, 20 ... DVD disc, 30 ... CD disc, 40 ... CD / DVD disc

Claims (4)

A transparent substrate having a thickness of 0.55 mm or more and less than 0.57 mm, and having an information pit having a minimum pit length of 0.440 μm and a track pitch of 0.74 μm formed on one surface;
And a reflective layer provided on the information pit forming surface of the transparent substrate.   2. The single-layer optical disc according to claim 1, further comprising a substrate for adjusting the thickness, which is attached to the clamping area. A first transparent substrate having a thickness of 0.55 mm or more and less than 0.57 mm, and having an information pit having a minimum pit length of 0.440 μm and a track pitch of 0.74 μm formed on one surface thereof; A single-layer optical disc having a first reflective layer provided on the information pit forming surface of the transparent substrate;
A second transparent substrate having a thickness larger than that of the first transparent substrate of the single-layer optical disc and having information pits formed on one surface thereof; and provided on the information pit forming surface of the second transparent substrate. A double-sided optical disc comprising: a second reflective layer; and an optical disc bonded to the single-layer optical disc.   4. The double-sided optical disk according to claim 3, wherein the entire thickness is less than 1.5 mm.

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