JP2006338800A - Optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of compatibility in two optical recording mediums having writing speeds different from each other and to provide an optical recording medium capable of support a wide linear speed range. <P>SOLUTION: The optical recording medium 100 is formed by sticking a first disk 10 and a second disk 20 to each other by using an adhesive layer 110. The first disk 10 is provided with a recording layer 14 containing Bi<SB>7</SB>Ge<SB>43</SB>Te<SB>50</SB>(at%) on a substrate 11 wherein a physical format of a DVD-RAM is formed and write speed information of 2×-5× speed is stored via other layers. The second disk 20 is provided with a recording layer 24 containing Bi<SB>12</SB>Ge<SB>38</SB>Te<SB>50</SB>(at%) on a substrate 21 wherein a physical format of a DVD-RAM is formed and write speed information of 6×-16× speed is stored via other layers. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical recording medium, and more particularly to an optical recording medium that can cope with a wide linear velocity region.

  In recent years, various optical recording media such as a CD (Compact Disk) and a DVD (Digital Versatile Disk) have been widely recognized and are widely used because they can record a large amount of information. As the optical recording medium, a write-once type optical recording medium that can be written once and a rewritable optical recording medium that can be repeatedly written have been developed. In a write-once type optical recording medium, a recording mark is formed by condensing a laser beam on a recording layer containing an organic dye compound, exothermic decomposition of the organic dye compound, and deforming the adjacent substrate surface and reflection layer. Examples of such a recordable optical recording medium include DVD-R / + R (DVD-Recordable). The rewritable optical recording medium includes a recording layer containing a phase change material such as GeSbTe. By irradiating the recording layer with laser light, the atomic arrangement of the phase change material reversibly changes between the amorphous phase and the crystalline phase, and information is recorded according to such two different atomic arrangement states. A rewritable optical recording medium using a phase change material is particularly inexpensive, so that it is widely used for consumer use. Particularly, it is rapidly spreading as a home video recording medium (see Patent Document 1). Examples of such a recordable optical recording medium include a DVD-RW (DVD-ReWriteable) and a DVD-RAM (DVD-Random Access Memory).

Japanese Patent Laying-Open No. 2005-038568

Recently, DVD recorders with a hard disk have become widespread, and video in the hard disk is dubbed to a DVD. A large amount of data stored in the hard disk of a personal computer is also backed up to a DVD. Under such circumstances, a DVD capable of high-speed recording is desired.
Until now, the write speed of the DVD has already reached 16-times speed, for example, for a write-once type optical recording medium such as DVD-R, and it is within one standard from 1-times speed to 16-times speed recording. On the other hand, in the case of a rewritable optical recording medium, there are two standards for DVD-RW: 1 × to 2 × speed and 2 × to 6 × speed. As for DVD-RAM, products corresponding to the standards of writing speeds of 2 times speed, 2 times speed to 3 times speed, and 2 times speed to 5 times speed have been developed. Furthermore, standards for 6 × to 16 × speed are being developed as products that support higher speeds in the future.

  Although such DVD-RW and DVD-RAM have the same physical format, there are several types of products on the market because the linear speed range of the writing speed is different. In addition, unlike a write-once optical recording medium that is standardized by one standard, a DVD-RW that is a rewritable optical recording medium has two standards for writing speed. In the drive corresponding to DVD-RW, there exists a problem that it cannot record on a 6 times speed disk. Such a problem that the recording compatibility due to the different writing speeds is not guaranteed is considered to be the same for DVD-RAMs for which standards for 6 × to 16 × speed are being developed.

The present invention has been made in order to solve such a problem related to a rewritable optical recording medium using a phase change material.
That is, an object of the present invention is to solve the compatibility problem between two types of optical recording media having different writing speeds and to provide an optical recording medium that can cope with a wide linear velocity range.

In order to solve the above-described problems, the present invention employs a double-sided, dual-layer disc structure in which two discs having the same physical format are bonded together.
That is, according to the present invention, the first phase change recording layer is provided directly or via another layer on the first substrate in which the predetermined physical format is formed and the first writing speed information is stored. The first disk substrate and the second substrate that has the same physical format as the first substrate and stores second writing speed information different from the first substrate are directly or other A second disk substrate provided with a second phase change recording layer through the layers, and the first disk substrate and the second phase change recording layer so that the first phase change recording layer and the second phase change recording layer are inside. There is provided an optical recording medium comprising an adhesive layer for bonding two disk substrates.
As described above, an optical recording medium having a recording layer containing a phase change material to which the present invention is applied is formed on both sides formed by bonding two disks formed in the same physical format and having different data writing speeds. By having a two-layer disc structure, it is possible to deal with a wide linear velocity region with a single disc, even if the writing speed standard is different, as in the write-once type optical recording medium.

Here, it is preferable that the physical format of the two disks bonded together is the DVD-RAM format.
In addition, as a combination of the speed information about the writing speed stored in each of the two disks formed in the same physical format, (1) the first writing speed information corresponds to 2 to 5 times speed, The second writing speed information corresponds to 6 × to 16 × speed, (2) the first writing speed information corresponds to 2 × to 5 × speed, and the second writing speed information corresponds to 6 × to 12 × speed. (3) The first writing speed information corresponds to 2 to 5 times speed, and the second writing speed information corresponds to 6 to 10 times speed.
Further, the physical format of the two disks bonded together can be formed in the DVD-RW format.

According to the present invention, there is also provided a double-sided dual-layer disc type optical recording medium in which the same physical format is formed and two substrates each provided with a phase change recording layer are bonded to each other. There is provided an optical recording medium characterized in that the stored writing speed information is different.
Here, when the physical format is formed based on the DVD-RAM standard, the phase change recording layer preferably contains a BiGeTe alloy.
In addition, when the physical format is formed based on the DVD-RAM standard, the writing speed information stored in one of the two substrates corresponds to 2 to 5 times speed and is stored in the other substrate. It is preferable that the writing speed information corresponds to 6 × to 16 × speed.

Further, when the optical recording medium to which the present invention is applied is viewed from the viewpoint of a recording layer containing a phase change material, it is a double-sided dual-layer optical recording medium on a substrate on which a DVD-RAM physical format is formed. In addition, a phase change recording layer corresponding to an information writing speed of 8.16 (m / s) to 21.23 (m / s) corresponding to 2 to 5 times speed is provided through another layer. A phase change recording layer corresponding to a second writing speed larger than the information writing speed is provided on one disk substrate and a substrate on which the same physical format as the first disk substrate is formed via another layer. There is provided an optical recording medium comprising: a second disk substrate, wherein the first disk substrate and the second disk substrate are bonded together.
Here, it is preferable that the second writing speed is 24.48 (m / s) to 67.92 (m / s) corresponding to 2 to 5 times speed. In addition, since the phase change recording layer contains a BiGeTe alloy, high-speed recording becomes possible.

  According to the optical recording medium of the present invention, it is possible to deal with a wide linear velocity region.

Hereinafter, the best mode (embodiment) for carrying out the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary. Also, the drawings used are used to describe the present embodiment and do not represent the actual size.
(Optical recording medium)
FIG. 1 is a diagram for explaining a first embodiment of an optical recording medium to which the present embodiment is applied. In FIG. 1, two disks (first disk 10) formed in a physical format based on the DVD-RAM standard version 2.0 (hereinafter sometimes referred to as Ver. 2) and having different data writing speeds. , An optical recording medium 100 having a double-sided dual-layer disc structure on which a second disc 20) is bonded is shown.
As shown in FIG. 1, the first disk (first disk substrate) 10 of the optical recording medium 100 is a DVD-RAM standard Ver. 2 on a substrate 11 (first substrate) formed in a physical format based on 2 on a lower dielectric layer 12, a lower interface layer 13, 2 to 5 times speed (8.16 m / s to 21.23 m / s) ( Recording layer 14 (first phase change recording layer), upper interface layer 15, upper dielectric layer 16, adjustment layer 17, heat dissipation layer 18 and protection formed of a phase change material corresponding to (first writing speed information) The layer 19 has a structure in which the layers 19 are sequentially stacked.

Here, the substrate 11 is formed of, for example, a light-transmitting resin such as polycarbonate resin, and is formed in a disk shape having a diameter of 120 mm and a thickness of 0.6 mm. A tracking pregroove 11a having a track pitch of 615 nm and a groove depth of 65 nm is spirally formed on the surface of the substrate 11. The pre-groove 11a is configured such that grooves and lands are alternately and continuously connected. The recording method is land / groove recording in which a land and a groove are automatically switched once per round. Furthermore, an embossed pit header is formed between the land and the groove.
Examples of the phase change material included in the recording layer 14 include a GeSbTe alloy and a BiGeTe alloy. In the first embodiment, the recording layer 14 is formed by sputtering a Bi ₇ Ge ₄₃ Te ₅₀ (at.%) Target in an Ar gas atmosphere so as to correspond to 2 × to 5 × speed. It is formed with a thickness.

The lower dielectric layer 12 and the upper dielectric layer 16 are layers for protecting the recording layer 14. The lower dielectric layer 12 is formed with a thickness of 140 nm by sputtering (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%). Similarly, the upper dielectric layer 16 is formed to a thickness of 33 nm by sputtering (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%).
The lower interface layer 13 is a layer for preventing the constituent elements of both layers from entering, diffusing and chemically reacting between the lower dielectric layer 12 and the recording layer 14. The lower interface layer 13 is formed with a thickness of 2 nm by sputtering (Cr ₂ O) ₆₀ (Ta ₂ O ₅ ) ₄₀ (mol%).
The upper interface layer 15 is a layer for preventing the constituent elements of both layers from entering, diffusing and chemically reacting between the upper dielectric layer 16 and the recording layer 14. The upper interface layer 15 is formed with a thickness of 2 nm by sputtering a Cr ₂ O ₃ target in an Ar gas atmosphere.
The adjustment layer 17 is a layer for absorbing a part of the laser light L so that the absorptance of the crystal part in the recording layer 14 is larger than the absorptivity of the amorphous part. The adjustment layer 17 is formed to a thickness of 28 nm by sputtering Cr ₈₅ (Cr ₂ O ₃ ) ₁₅ (mol%).
The heat dissipation layer 18 is a layer for releasing heat generated during recording / reproduction of information. The heat dissipation layer 18 is formed with a thickness of 100 nm by sputtering Ag ₉₉ Cu ₁ (wt.%).
The protective layer 19 is a layer for protecting each of the above layers. The protective layer 19 is formed with a thickness of 7 μm using an ultraviolet curable resin.

Next, the second disk (second disk substrate) 20 has a structure similar to that of the first disk 10, and the DVD-RAM standard Ver. 2 on the substrate 21 (second substrate) formed on the basis of 2, the lower dielectric layer 22, the lower interface layer 23, the recording layer 24 (second phase change recording layer), the upper interface layer 25, and the upper dielectric layer. 26, the adjustment layer 27, the heat dissipation layer 28, and the protective layer 29 are sequentially stacked. Each of these layers constituting the second disk 20 is formed using the same material as each of the layers constituting the first disk 10 described above.
Here, the recording layer 24 has Bi ₁₂ Ge ₃₈ Te ₅₀ (at.%) So as to correspond to 6 to 16 times speed (24.48 m / s to 67.92 m / s) (second writing speed information). The target is sputtered in an Ar gas atmosphere and formed with a thickness of 9 nm.
The heat dissipation layer 28 is formed with a thickness of 150 nm by sputtering Ag ₉₉ Cu ₁ (wt.%).

  As shown in FIG. 1, the first disk 10 and the second disk 20 are bonded so that the protective layer 19 and the protective layer 29 are opposed to each other with an adhesive layer 110 interposed therebetween. A recording medium 100 is configured. The adhesive layer 110 was formed by applying a slow-acting adhesive to the protective layer 19 and the protective layer 29, and applying pressure after UV irradiation to bond the first disk 10 and the second disk 20 together.

FIG. 2 is a diagram for explaining the recording area R of the first disk 10. The second disk 20 also has the same recording area R as the first disk 10.
As shown in FIG. 2, the recording area R of the first disc 10 has a recording information management area R-Info provided on the innermost side of the disc. The recording information management area R-Info stores speed information (first writing speed information) corresponding to a writing speed of 2 to 5 times. The recording area R has a lead-in area R-in provided outside the recording information management area R-Info and a data area DA provided outside the lead-in area R-in. Further, the recording area R has a lead-out area R-out provided outside the data area DA. The data area DA is divided into a plurality of 35 zones.
The second disk 20 also has a recording area R similar to that of the first disk 10, and the speed information corresponding to the writing speed of 6 to 16 times in the recording information management area R-Info of the second disk 20 is shown. (Second writing speed information) is stored.

  FIG. 3 is a diagram for explaining the data area DA of the first disk 10. As shown in FIG. 3, the physical format is DVD-RAM standard Ver. The data area DA of the first disk 10 formed based on 2 is divided into 35 zones (zone 1, zone 2, zone 3... Zone 33, zone 34, zone 35) concentrically in the radial direction. ing. A ZCLV (Zone Constant Linear Velocity) method in which the rotation speed is constant in each zone is adopted. Each zone is divided by a plurality of sectors Se on which land / groove recording is performed, and a header Hd with embossed pits is formed at the head of the sector Se. In the innermost zone 1, there are 17 sectors per track, and in the outermost zone 35 there are 41 sectors (DVD-RAM standard Ver. 2).

  FIG. 4 is a diagram for explaining the format of the sector Se of the first disk 10. As shown in FIG. 4, the sector Se is divided into a header area HA formed at the head portion, a mirror area MA, and a 2048-byte recording area RA, and one sector (1Se) is constituted by these. Further, the header area HA is divided into four areas (first area to fourth area), and exists between the groove G and the land L. The first region and the second region are disposed on the outer peripheral side of the land track as viewed from the land track, and the third region and the fourth region are disposed on the inner peripheral side of the land track. The beam spot BS detects an address by emboss pits formed in the land / groove wobble W and the header area HA.

Next, the characteristic evaluation (repetitive rewriting test) of the optical recording medium 100 prepared in the first embodiment was performed as follows using a predetermined information recording apparatus.
The information recording apparatus includes a semiconductor laser (wavelength 655 nm, numerical aperture 0.6) for irradiating the optical recording medium 100 with light when recording and reproducing information, a laser driver for controlling the output of the semiconductor laser, and recorded information Are provided with a waveform generator for generating the recording pulse generated according to the above, a waveform equivalent circuit, and a binarization circuit.
Information recording was performed using 8-16 modulation, and mark edge recording type recording marks were formed on the recording layer 14 of the first disk 10 and the recording layer 24 of the second disk 20. The shortest mark length of the recording mark was 0.42 μm. Further, a random pattern of 3T to 14T was recorded as information, and the recorded random pattern was reproduced.
Recording and reproduction of the first disk 10 in which speed information corresponding to a writing speed of 2 to 5 times speed was stored was performed at a linear speed of 8.2 m / s corresponding to 2 times speed. Further, recording on the second disk 20 in which speed information corresponding to the writing speed of 6 × to 16 × is stored is performed at a linear speed of 67.9 m / s corresponding to 16 × speed, and reproduction of the recorded information is 6 It was performed at a linear speed of 24.5 m / s corresponding to double speed.

As a result, the first disk 10 storing speed information corresponding to a writing speed of 2 to 5 times speed and the second disk 20 storing speed information corresponding to a writing speed of 6 to 16 times speed are described. Both the land and groove jitter were 9% or less of the specification value.
As described above, the optical recording medium 100 of the first embodiment is a DVD-RAM standard Ver. A double-sided, double-layered disk structure in which two disks with different data writing speeds are bonded together, with a physical format based on 2 and a wide linear speed range from 2x to 16x It becomes possible to cope with. As a result, recording compatibility of rewritable optical recording media having different writing speeds is guaranteed.

In the first embodiment, the DVD-RAM standard Ver. Although the double-sided dual-layer disc structure in which two discs formed in a physical format based on 2 are bonded together has been described, the double-sided dual layer in which two discs formed in a physical format based on the DVD-RW standard are bonded together It is also possible to have a disk structure.
In this case, the speed information is formed in a physical format based on the DVD-RW standard, and the writing speed is 1 to 2 times (3.49 m / s to 6.98 m / s) in the recording information management area R-Info. Is written in a physical format based on the DVD-RW standard in the same manner, and the writing speed is double to six times (6.98 m / s to 20.94 m) in the recording information management area R-Info. / S), each of which is prepared with a second disk storing speed information corresponding thereto, and the first disk and the second disk are bonded together via an adhesive layer, and light having a double-sided dual-layer disk structure is prepared. A recording medium can be configured.

Although not shown, the first disk and the second disk of the physical format based on the DVD-RW standard are usually formed as follows. That is, a substrate on which lead-in data, addresses, track servo grooves, and the like are formed based on the DVD-RW format in the range of 45.0 mm to 117.0 mm in diameter using polycarbonate resin or the like. The substrate has an outer diameter of 120 mm, an inner diameter of 15 mm, and a thickness of 0.6 mm. A tracking pregroove with a track pitch of 740 nm is formed in a spiral shape.
Next, a transparent dielectric layer, a recording layer made of a phase change material, a transparent dielectric layer, and a reflective layer made of an Al alloy are sequentially laminated on the signal surface of the substrate by sputtering in the range of 40 mm to 119 mm in diameter. Next, an ultraviolet curable resin is applied on the reflective layer to a thickness of about 10 μm by spin coating, and cured by ultraviolet irradiation to form a protective film layer.

FIG. 5 is a diagram for explaining a second embodiment of an optical recording medium to which the present embodiment is applied. FIG. 5 shows the DVD-RAM standard Ver. The first disk 10 is formed in a physical format based on 2 and stores speed information corresponding to a data writing speed of 2 to 5 times, and a data writing speed of 6 to 12 times. An optical recording medium 200 having a double-sided, double-layer disc structure in which a second disc 30 storing information is bonded is shown.
As shown in FIG. 5, the first disk 10 in the optical recording medium 200 has the same structure as the first disk 10 in the optical recording medium 100 of the first embodiment, and thus the description thereof is omitted. The second disk 30 is a DVD-RAM standard Ver. 2 on a substrate 31 formed in a physical format based on 2 by a phase change material corresponding to a lower dielectric layer 32, a lower interface layer 33, and 6 to 12 times speed (24.48 m / s to 50.94 m / s). The formed recording layer 34, upper interface layer 35, upper dielectric layer 36, adjustment layer 37, heat dissipation layer 38, and protective layer 39 are sequentially stacked. A tracking pregroove 31a having a track pitch of 615 nm and a groove depth of 65 nm is spirally formed on the surface of the substrate 31.

Each of these layers constituting the second disk 30 is formed using the same material as each of the layers constituting the first disk 10 described above.
Here, the recording layer 34 is formed to a thickness of 9 nm by sputtering a Bi ₁₀ Ge ₄₀ Te ₅₀ (at.%) Target in an Ar gas atmosphere so as to correspond to 6 × to 12 × speed. . The heat dissipation layer 38 is formed with a thickness of 150 nm by sputtering Ag ₉₉ Cu ₁ (wt.%).
As shown in FIG. 5, the first disk 10 and the second disk 30 are bonded to each other with the protective layer 19 and the protective layer 39 facing each other with the adhesive layer 120 interposed therebetween. A recording medium 200 is configured.

  Next, as in the first embodiment, the characteristic evaluation (repetitive rewriting test) of the optical recording medium 200 was performed using a predetermined information recording apparatus. As a result, the first disk 10 storing speed information corresponding to a writing speed of 2 to 5 times speed and the second disk 30 storing speed information corresponding to a writing speed of 6 to 12 times speed are described. Both the land and groove jitter were 9% or less of the specification value.

FIG. 6 is a diagram for explaining a third embodiment of an optical recording medium to which the present embodiment is applied. FIG. 6 shows DVD-RAM standard Ver. The first disk 10 is formed in a physical format based on 2 and stores speed information corresponding to a data writing speed of 2 to 5 times, and a data writing speed of 6 to 10 times. An optical recording medium 300 having a double-sided dual-layer disk structure in which a second disk 40 storing information is bonded is shown.
As shown in FIG. 6, the first disk 10 in the optical recording medium 300 has the same structure as the first disk 10 in the optical recording medium 100 according to the first embodiment, and a description thereof will be omitted. The second disk 40 is a DVD-RAM standard Ver. 2 on a substrate 41 formed in a physical format based on 2 with a lower dielectric layer 42, a lower interface layer 43, and a phase change material corresponding to 6 × 10 to 10 × speed (24.48 m / s to 42.45 m / s). The recording layer 44, the upper interface layer 45, the upper dielectric layer 46, the adjustment layer 47, the heat dissipation layer 48, and the protective layer 49 are sequentially stacked. A tracking pregroove 41a having a track pitch of 615 nm and a groove depth of 65 nm is spirally formed on the surface of the substrate 41.

Each of these layers constituting the second disk 40 is formed using the same material as each of the layers constituting the first disk 10 described above.
Here, the recording layer 44 is formed to have a thickness of 9 nm by sputtering a Bi ₁₀ Ge ₄₀ Te ₅₀ (at.%) Target in an Ar gas atmosphere so as to correspond to 6 × to 10 × speed. . The heat dissipation layer 48 is formed to a thickness of 100 nm by sputtering Ag ₉₉ Cu ₁ (wt.%).
As shown in FIG. 6, the first disk 10 and the second disk 40 are bonded to each other with the protective layer 19 and the protective layer 49 facing each other with an adhesive layer 130 interposed therebetween. A recording medium 300 is configured.

  Next, as in the first embodiment, the characteristic evaluation (repetitive rewriting test) of the optical recording medium 300 was performed using a predetermined information recording apparatus. As a result, the first disk 10 storing speed information corresponding to a writing speed of 2 to 5 times speed and the second disk 40 storing speed information corresponding to a writing speed of 6 to 10 times speed are described. Both the land and groove jitter were 9% or less of the specification value.

  As described above, according to the present invention, the linear velocity region can be obtained by having a double-sided dual-layer disc structure in which two discs that are formed in the same standard physical format and have different data writing speeds are bonded together. When using a drive that is not compatible with each other, it is possible to deal with a wide linear velocity range with a single disc. For example, in the case of the DVD-RAM format, a first disk compatible with 2 × to 5 × speed and a second disk compatible with 6 × to 16 × speed are bonded together to form a DVD-RAM format with a single disk. Recording and playback are possible with all the drives on the market that support this recording, and a disc with improved compatibility is provided.

It is a figure for demonstrating Embodiment 1 of the optical recording medium to which this Embodiment is applied. It is a figure for demonstrating the recording area of a 1st disc. It is a figure for demonstrating the data area of a 1st disk. It is a figure for demonstrating the format of the sector of a 1st disk. It is a figure for demonstrating Embodiment 2 of the optical recording medium with which this Embodiment is applied. It is a figure for demonstrating Embodiment 3 of the optical recording medium to which this Embodiment is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... 1st disk, 11, 21, 31, 41 ... Board | substrate, 11a, 21a, 31a, 41a ... Pregroove, 12, 22, 32, 42 ... Lower dielectric layer, 13, 23, 33, 43 ... Lower interface 14, 24, 34, 44 ... recording layer, 15, 25, 35, 45 ... upper interface layer, 16, 26, 36, 46 ... upper dielectric layer, 17, 27, 37, 47 ... adjustment layer, 18 , 28, 38, 48 ... heat dissipation layer, 19, 29, 39, 49 ... protective layer, 20, 30, 40 ... second disc, 100, 200, 300 ... optical recording medium, 110, 120, 130 ... adhesive layer

Claims (12)

A first disk substrate having a first physical phase change recording layer formed directly or via another layer on a first substrate having a predetermined physical format and storing first write speed information;
The second physical layer is formed on the second substrate having the same physical format as the first substrate and storing second writing speed information different from the first substrate, either directly or via another layer. A second disk substrate provided with a phase change recording layer of
An adhesive layer for bonding the first disk substrate and the second disk substrate so that the first phase change recording layer and the second phase change recording layer are inside. Optical recording media.   2. The optical recording medium according to claim 1, wherein the physical format is a DVD-RAM.   3. The optical recording medium according to claim 2, wherein the first writing speed information corresponds to 2 to 5 times speed, and the second writing speed information corresponds to 6 to 16 times speed.   3. The optical recording medium according to claim 2, wherein the first writing speed information corresponds to 2 to 5 times speed, and the second writing speed information corresponds to 6 to 12 times speed.   3. The optical recording medium according to claim 2, wherein the first writing speed information corresponds to 2 to 5 times speed, and the second writing speed information corresponds to 6 to 10 times speed.   The optical recording medium according to claim 1, wherein the physical format is DVD-RW. A double-sided, dual-layer optical recording medium in which the same physical format is formed and two substrates each provided with a phase change recording layer are bonded together,
An optical recording medium characterized in that writing speed information stored in each of the two substrates is different.   8. The optical recording medium according to claim 7, wherein the physical format is formed based on a DVD-RAM standard, and the phase change recording layer includes a BiGeTe alloy.   The physical format is formed on the basis of the DVD-RAM standard, and the writing speed information stored in one of the two substrates corresponds to 2 to 5 times speed, and is stored in the other substrate. 8. The optical recording medium according to claim 7, wherein the writing speed information corresponds to 6 to 16 times speed. A double-sided dual-layer optical recording medium,
A phase change recording layer corresponding to an information writing speed of 8.16 (m / s) to 21.23 (m / s) is provided on a substrate on which a physical format of DVD-RAM is formed via another layer. A first disk substrate;
A second disk in which a phase change recording layer corresponding to a second writing speed larger than the information writing speed is provided on a substrate on which the same physical format as the first disk substrate is formed via another layer. A substrate,
An optical recording medium, wherein the first disk substrate and the second disk substrate are bonded together.   11. The optical recording medium according to claim 10, wherein the second writing speed is 24.48 (m / s) to 67.92 (m / s).   The optical recording medium according to claim 10, wherein the phase change recording layer contains a BiGeTe alloy.

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