JP2009110657A - Optical recording medium, and method and device for recording/reproducing optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To instantaneously change recording and reproducing conditions, for example, a recording pulse strategy, recording power and reproducing power, in accordance with a recording layer for recording or reproducing information in a single-sided incident type optical recording medium. <P>SOLUTION: A control part reads layer information from one recording layer of an optical recording medium where the layer information is respectively recorded on a plurality of recording layers on/from which information can be recorded or reproduced by irradiation with a laser beam from one side by detecting whether the whole address information is expressed by two's complement (layer information reading step) and controls so that recording or reproduction is performed on the recording/reproduction condition in accordance with the recording layer specified by the layer information (recording control step). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical recording medium having a plurality of recording layers capable of recording or reproducing information by irradiating laser light from one side, such as a DVD-R, a recording / reproducing method of the optical recording medium, and a recording / reproducing of the optical recording medium Relates to the device.

Currently, various optical recording media such as CD-R, CD-RW, and MO can store a large amount of information and are easily accessible at random, so that they are widely recognized as external storage devices in information processing apparatuses such as computers. It is becoming popular. In such an optical recording medium, it is desired to increase the storage density as the amount of information handled increases.
Among various optical recording media, an optical recording medium (optical disc) having a recording layer containing an organic dye (also referred to as a dye-containing recording layer) such as CD-R, DVD-R, and DVD + R is relatively inexpensive, and Since it is compatible with a reproduction-only optical disk, it is particularly widely used.

As an example, a medium such as a CD-R that is representative of an optical disk having a dye-containing recording layer has a dye-containing recording layer and a reflective layer in this order on a transparent disk substrate. It has a laminated structure having a protective layer for covering, and performs recording / reproduction with a laser beam through a substrate.
Similarly, a typical single-sided DVD-R has a dye-containing recording layer, a reflective layer, and a protective layer covering them in this order on the first transparent disk substrate, and further has an adhesive layer on the protective layer. With or without intervening, a laminated structure in which a so-called dummy disk having a reflective layer formed on a second disk substrate (which may be transparent or opaque) is provided, and laser light is applied from one side through the first transparent disk substrate. Recording / playback. The dummy disk may be only a transparent or opaque disk substrate, or a layer other than the reflective layer may be provided. DVD + R
Is substantially the same configuration as the DVD-R, and is therefore representative in the description of the DVD-R.

  In order to further increase the recording capacity of the optical recording medium, the above single-sided DVD-R is bonded to form a medium having two recording layers, and each recording layer is irradiated with laser light from both sides. (I.e., irradiate laser light from one side of the medium and record / reproduce the recording layer closer to this one side, while irradiating laser light from the other side of the medium) A double-sided DVD-R is also known which records and reproduces the recording layer closer to the other side.

In addition, optical recording media (optical discs) having a phase change recording layer such as CD-RW and DVD-RW are also widely used. Generally, in a rewritable optical recording medium having a phase change recording layer, protective layers are provided above and below the recording layer.
By the way, in recent years, in an optical recording medium having a plurality of recording layers, the recording / reproducing apparatus is not enlarged and complicated, and a laser is applied from one side to enable continuous reproduction over a plurality of recording layers. It is desired to realize a single-sided incident type optical recording medium (for example, single-sided incident type DVD-R) capable of performing recording / reproducing on these plural recording layers by irradiating light.

For this reason, for example, as a single-sided optical recording medium having the following configuration, a dual-layer type single-sided DVD-R having two recording layers has been proposed (see, for example, Patent Document 1).
For example, a dual-layer type single-sided DVD-R includes a first recording layer made of an organic dye capable of optically recording information by irradiation with a recording laser beam on a first translucent substrate, and a reproduction laser. A first reflective layer composed of a semi-transparent reflective film capable of transmitting a part of light, an intermediate layer having translucency with respect to a recording laser beam and a reproducing laser beam, and a recording laser beam A second recording layer made of an organic dye that can optically record information by irradiation, a second reflective layer that reflects the laser beam for reproduction, and a second translucent substrate are sequentially laminated.

Japanese Patent Laid-Open No. 11-066662

By the way, a single-sided incident optical recording medium having a plurality of recording layers, such as a dual-layer type single-sided incident DVD-R, has a recording pulse strategy (recording strategy, write strategy), recording power, etc. for each recording layer. The optimum recording / reproduction conditions such as reproduction power are greatly different.
Therefore, in a recording / reproducing apparatus that records or reproduces information with respect to each recording layer of a single-side incidence type optical recording medium having a plurality of recording layers, for example, according to the recording layer, a recording pulse strategy, recording power, reproduction power, etc. It is desirable to be able to switch the recording / reproducing conditions such as to enable accurate and reliable recording or reproduction of information.

In particular, in order for the recording / reproducing apparatus to perform random access to each recording layer of the optical recording medium to record or reproduce information, the recording / reproducing conditions must be switched instantaneously according to the recording layer. There is.
In addition, for example, it is conceivable to add address information continuously over a plurality of recording layers and determine which layer is based on the read address information in the recording / reproducing apparatus. It is difficult to judge immediately.

  The present invention has been devised in view of such problems, and in an optical recording medium that records or reproduces information on a plurality of recording layers by irradiating laser light from one side, information is recorded or reproduced. Optical recording medium, recording / reproducing method of optical recording medium, and optical recording, which can instantaneously switch recording / reproducing conditions such as recording pulse strategy, recording power, and reproducing power according to the recording layer to be performed An object of the present invention is to provide a medium recording / reproducing apparatus.

  For this reason, in the recording / reproducing method of the optical recording medium of the present invention, the control unit is a light in which layer information is recorded on each of a plurality of recording layers on which information can be recorded or reproduced by irradiation of laser light from one side. A layer information reading step for reading the layer information by detecting whether or not the entire address information is represented by two's complement from one recording layer of the recording medium, and a recording unit in which the control unit is specified by the layer information And a recording / reproducing control step for controlling the recording / reproducing to be performed under the recording / reproducing condition corresponding to the layer.

  The recording / reproducing apparatus for an optical recording medium of the present invention is a recording layer of an optical recording medium in which layer information is recorded on each of a plurality of recording layers capable of recording or reproducing information by irradiation with laser light from one side. From this, it is detected whether or not the entire address information is represented in two's complement, and recording or reproduction is performed under a layer information reading unit that reads out layer information and a recording / reproduction condition corresponding to the recording layer specified by the layer information And a recording / reproducing control unit for controlling the recording / reproducing operation to be performed (claim 2).

  An optical recording medium of the present invention is an optical recording medium recorded or reproduced by the optical recording medium recording / reproducing method according to claim 1, wherein a plurality of information can be recorded or reproduced by irradiation with laser light from one side. A method for determining whether or not the entire address information is represented by a two's complement in two adjacent recording layers of the plurality of recording layers. Layer information is recorded by (claim 3).

  Moreover, it is preferable to have two recording layers as a plurality of recording layers.

  Each recording layer is preferably a dye-containing recording layer.

  As described above in detail, according to the optical recording medium, the recording / reproducing method of the optical recording medium, and the recording / reproducing apparatus of the optical recording medium of the present invention, depending on the recording layer on which information is to be recorded or reproduced, for example, There is an advantage that recording / reproducing conditions such as a recording pulse strategy, recording power, and reproducing power can be instantaneously switched.

1 is a schematic diagram showing an overall configuration of an optical recording medium (type 1) according to an embodiment of the present invention. It is a schematic diagram which shows the whole structure of the optical recording medium (type 2) concerning one Embodiment of this invention. 1 is a schematic diagram showing an overall configuration of an optical recording medium recording / reproducing apparatus according to an embodiment of the present invention. It is a flowchart which shows the process performed by the control part of the recording / reproducing apparatus of the optical recording medium concerning one Embodiment of this invention.

Hereinafter, an optical recording medium (recordable optical recording medium), an optical recording medium recording / reproducing method, and an optical recording medium recording / reproducing apparatus according to an embodiment of the present invention will be described with reference to FIGS. explain.
The optical recording medium according to the present embodiment has a plurality of recording layers, and can irradiate light (laser light) from one side to record or reproduce information on each recording layer. It is a recording medium.

In the present embodiment, as a single-sided incident type optical recording medium (single-sided incident type DVD-R), for example, a dual layer type single-sided incident type DVD-R (recordable optical recording medium) having two recording layers will be described as an example. .
(1) Structure of Optical Recording Medium First, two types of optical recording media (optical disks) having different laminated structures will be described as the optical recording medium according to the present embodiment.
(A) Type 1
FIG. 1 is a schematic cross-sectional view showing an optical recording medium (type 1, laminated single-sided incidence type optical recording medium) according to the present embodiment.

  The type 1 optical recording medium according to the present embodiment is a first recording containing a dye on a disk-shaped transparent (light transmissive) first substrate (first substrate, first light transmissive substrate) 1. Layer (first recording layer, first dye-containing recording layer) 2, translucent first reflective layer (hereinafter also referred to as translucent reflective layer) 3, intermediate resin layer (intermediate layer) 4, and second containing dye A recording layer (second recording layer, second dye-containing recording layer) 5, a second reflective layer 6, an adhesive layer 7, and a second substrate (second substrate) 8 are provided in this order. The light beam is irradiated from the first substrate 1 side, and recording or reproduction is performed.

  In the present embodiment, being transparent (having light transmission) means being transparent (having light transmission) with respect to a light beam used for recording or reproduction on an optical recording medium. Further, the transparent (light-transmitting) layer includes a layer that absorbs a light beam used for recording or reproduction to some extent. For example, if the wavelength of the light beam used for recording or reproduction is 50% or more, preferably 60% or more, it is substantially light transmissive (transparent).

  Concavities and convexities (lands and grooves) are respectively formed on the transparent first substrate 1 and the intermediate resin layer 4, and a recording track is constituted by the concave portions and / or the convex portions. Here, the recording track 11 on the transparent first substrate 1 is constituted by a groove portion of the first substrate 1, that is, a convex portion with respect to the light incident direction. The recording track 12 on the intermediate resin layer 4 is also constituted by a groove portion of the intermediate resin layer 4, that is, a convex portion with respect to the light incident direction. Note that the recording tracks 11 and 12 may be constituted by concave portions with respect to the light incident direction, or may be constituted by both concave portions and convex portions with respect to the light incident direction. It is preferable that the projection is formed with respect to the incident direction. Unless otherwise specified, in the present invention, the unevenness is defined with respect to the incident direction of light used for recording or reproduction.

  These recording tracks 11 and 12 are slightly meandered in the radial direction with a predetermined amplitude and a predetermined frequency (this is called wobble). An isolated pit (address pit) according to a certain rule is formed in the land between the recording tracks 11 and 12 (this is called a land pre-pit, LPP; Land Pre-Pit). Address information is recorded in advance. In addition, it may have uneven pits (pre-pits) as necessary. Information can also be recorded by reversing the direction of the wobble or modulating the frequency.

Next, each layer will be described.
(A) About the 1st board | substrate 1 It is desirable for the 1st board | substrate 1 to be excellent in optical characteristics, such as being transparent and low birefringence. Moreover, it is desirable that the moldability is excellent, such as easy injection molding. Furthermore, it is desirable that the hygroscopicity is small because warpage can be reduced.

Furthermore, it is desirable to provide shape stability so that the optical recording medium has a certain degree of rigidity. However, as long as the second substrate 8 has sufficient shape stability, the first substrate 1 may not have high shape stability.
Examples of such materials include those made of resins such as acrylic resins, methacrylic resins, polycarbonate resins, polyolefin resins (particularly amorphous polyolefins), polyester resins, polystyrene resins, epoxy resins, and the like. Can be used. Or the 1st board | substrate 1 may consist of a several layer, for example, what provided the resin layer which consists of radiation curable resin, such as photocuring resin, on base | substrates, such as glass and resin, can be used. Radiation is a general term for light (ultraviolet rays, visible rays, infrared rays, etc.), electron beams, and the like.

Polycarbonate is preferable from the viewpoints of high productivity such as optical characteristics and moldability, cost, low hygroscopicity, and shape stability. Amorphous polyolefin is preferred from the standpoint of chemical resistance and low hygroscopicity. Moreover, a glass substrate is preferable from the viewpoint of high-speed response.
The first substrate 1 is preferably thin, and usually the thickness is preferably 2 mm or less, more preferably 1 mm or less. This is because the coma aberration tends to decrease as the distance between the objective lens and the recording layer decreases and the substrate becomes thinner, and the recording density is easily increased. However, in order to obtain sufficient optical properties, hygroscopicity, moldability, and shape stability, a certain amount of thickness is necessary, and is usually preferably 10 μm or more, more preferably 30 μm or more.

In the present optical recording medium, it is desirable to appropriately adjust the distance between the objective lens and both recording layers in order to perform good recording or reproduction on both the first recording layer 2 and the second recording layer 5. For example, it is preferable that the focal point of the objective lens is approximately at the midpoint between the two recording layers so that both recording layers can be easily accessed.
More specifically, in DVD-ROM and DVD-R systems, the distance between the objective lens and the recording layer is adjusted to be optimal when the substrate thickness is 0.6 mm.

Accordingly, in the case of DVD-ROM compatibility in this layer configuration, the thickness of the first substrate 1 is most preferably a thickness obtained by subtracting one half of the thickness of the intermediate resin layer 4 from 0.6 mm. preferable. At this time, the substantially middle point between both recording layers is about 0.6 mm, and it is easy to apply focus servo to both recording layers.
When there are other layers such as a buffer layer and a protective layer between the second recording layer 5 and the first reflective layer 3, the thickness of these layers and the intermediate resin layer 4 is 2 from the thickness of 0.6 mm. Most preferably, the thickness is reduced by a factor of one.

  The first substrate 1 is provided with irregularities in a spiral shape or a concentric shape to form grooves and lands. Normally, information is recorded or reproduced on the first recording layer 2 using such grooves and / or lands as recording tracks. In the case of a so-called DVD-R disc in which recording or reproduction is performed by condensing a laser having a wavelength of 650 nm with an objective lens having a numerical aperture of 0.6 to 0.65, the first recording layer 2 is usually formed by coating. A thick film is formed at the groove, which is suitable for recording or reproduction.

  In the present optical recording medium, it is preferable that the groove portion of the first substrate 1, that is, the convex portion with respect to the light incident direction is the recording track 11. Here, a recessed part and a convex part say the recessed part and convex part with respect to the incident direction of light, respectively. Usually, the groove width is about 50 to 500 nm, and the groove depth is about 10 to 250 nm. When the recording track is spiral, the track pitch is preferably about 0.1 to 2.0 μm. In addition, it may have uneven pits such as land prepits as necessary.

From the viewpoint of cost, the substrate having such irregularities is preferably manufactured by injection molding from a stamper having irregularities. When a resin layer made of a radiation curable resin such as a photocurable resin is provided on a substrate such as glass, irregularities such as recording tracks may be formed on the resin layer.
(B) About the first recording layer 2 The first recording layer 2 is usually a single-sided recording medium (for example, CD-R, DVD-R, DVD + R).
The sensitivity is the same as that of the recording layer used for the above.

In order to realize good recording / reproducing characteristics, it is desirable that the dye has a low heat generation and a high refractive index.
Furthermore, in the combination of the first recording layer 2 and the first reflective layer 3, it is desirable that the reflection, transmission and absorption of light be in an appropriate range. The recording sensitivity can be increased and the thermal interference during recording can be reduced.

  Examples of such organic dye materials include macrocyclic azaannulene dyes (phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, etc.), pyromethene dyes, polymethine dyes (cyanine dyes, merocyanine dyes, squarylium dyes, etc.), anthraquinone dyes, Examples include azulenium dyes, metal-containing azo dyes, and metal-containing indoaniline dyes.

  Among the above-mentioned various organic dyes, metal-containing azo dyes are preferable because they are excellent in recording sensitivity and excellent in durability and light resistance. In particular, the following general formula (I) or (II)

(Ring A ¹ and A ² are each independently a nitrogen-containing aromatic heterocyclic ring that may have a substituent, and Ring B ¹ and B ² may each independently have a substituent. X is an alkyl group having 1 to 6 carbon atoms which is substituted with at least two fluorine atoms.
The organic dye used in the recording layer of the present optical recording medium is preferably a dye compound having a maximum absorption wavelength λmax in the visible light to near infrared region of about 350 to 900 nm and suitable for recording with a blue to near microwave laser. . A near-infrared laser having a wavelength of about 770 to 830 nm (typically 780 nm, 830 nm, etc.) used for a CD-R or a red laser having a wavelength of about 620 to 690 nm (typically used for a DVD-R) 635 nm, 650 nm, 680 nm, etc.), or a dye suitable for recording with a so-called blue laser having a wavelength of 410 nm or 515 nm is more preferable.

One kind of dye may be used, or two or more kinds of the same kind or different kinds may be used in combination. Furthermore, it is also possible to use an optical recording medium corresponding to recording with laser light in a plurality of wavelength regions by using a combination of dyes suitable for recording in each of the recording light with the plurality of wavelengths.
In addition, the recording layer has a transition metal chelate compound (for example, acetylacetonate chelate, bisphenyldithiol, salicylaldehyde oxime, bisdithio-α-diketone, etc.) as a singlet oxygen quencher to improve the stability and light resistance of the recording layer. In order to improve the recording sensitivity, a recording sensitivity improving agent such as a metal compound may be contained. Here, the metal compound refers to a compound in which a metal such as a transition metal is contained in the compound in the form of atoms, ions, clusters, etc., for example, an ethylenediamine complex, an azomethine complex, a phenylhydroxyamine complex, a phenanthroline complex, Organic metal compounds such as dihydroxyazobenzene complex, dioxime complex, nitrosoaminophenol complex, pyridyltriazine complex, acetylacetonate complex, metallocene complex and porphyrin complex can be mentioned. Although it does not specifically limit as a metal atom, It is preferable that it is a transition metal.

  Furthermore, a binder, a leveling agent, an antifoaming agent and the like can be used in combination in the recording layer of the optical recording medium, if necessary. Preferable binders include polyvinyl alcohol, polyvinyl pyrrolidone, nitrocellulose, cellulose acetate, ketone resin, acrylic resin, polystyrene resin, urethane resin, polyvinyl butyral, polycarbonate, polyolefin and the like.

The film thickness of the recording layer varies depending on the recording method and the like, and is not particularly limited. However, in order to obtain a sufficient degree of modulation, it is usually preferably 5 nm or more, more preferably 10 nm or more, Especially preferably, it is 20 nm or more. However, in the present optical recording medium, since it is not necessary to be too thick in order to transmit light moderately, it is usually 3 μm or less, preferably 1 μm or less, more preferably 200 nm or less. The film thickness of the recording layer is usually different between the groove part and the land part, but in this optical recording medium, the film thickness of the recording layer is the film thickness in the groove part of the substrate.

Examples of the method for forming the recording layer include vacuum film forming methods, sputtering methods, doctor blade methods, cast methods, spin coating methods, dipping methods, and the like, but from the viewpoint of mass productivity and cost, A spin coating method is preferred. From the viewpoint that a recording layer having a uniform thickness can be obtained, the vacuum vapor deposition method is preferable to the coating method.
In the case of film formation by spin coating, the rotation speed is preferably 10 to 15000 rpm, and after spin coating, treatment such as heating or application to solvent vapor may be performed.

  The coating solvent for forming the recording layer by a coating method such as a doctor blade method, a casting method, a spin coating method, or a dipping method may be any solvent that does not attack the substrate and is not particularly limited. For example, ketone alcohol solvents such as diacetone alcohol and 3-hydroxy-3-methyl-2-butanone; cellosolv solvents such as methyl cellosolve and ethyl cellosolve; chain hydrocarbon solvents such as n-hexane and n-octane Cyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, n-butylcyclohexane, tert-butylcyclohexane and cyclooctane; perfluoroalkyl alcohols such as tetrafluoropropanol, octafluoropentanol and hexafluorobutanol Examples of the solvent include hydroxycarboxylic acid ester solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate.

In the case of the vacuum deposition method, for example, an organic dye and, if necessary, recording layer components such as various additives are put in a crucible installed in a vacuum vessel, and the inside of the vacuum vessel is 10 ⁻² to After evacuating to about 10 ⁻⁵ Pa, the crucible is heated to evaporate the recording layer components and vapor deposited on a substrate placed facing the crucible to form a recording layer.
(C) About the 1st reflective layer 3 The 1st reflective layer 3 is a reflective layer with a certain amount of light transmittance. That is, the reflective layer has a small absorption of recording / reproducing light, a light transmittance of 40% or more, and an appropriate light reflectance (usually 30% or more). For example, an appropriate transmittance can be provided by providing a thin metal with high reflectivity. Moreover, it is desirable that there is some degree of corrosion resistance. Further, it is desirable that the first recording layer 2 is blocked so that the first recording layer 2 is not affected by the seepage of the upper layer (here, the intermediate resin layer 4) of the first reflective layer 3.

In order to ensure high transmittance, the thickness of the first reflective layer 3 is usually preferably 50 nm or less. More preferably, it is 30 nm or less. More preferably, it is 25 nm or less. However, since the first recording layer 2 is not affected by the upper layer of the first reflective layer 3, a certain thickness is required, and usually 3 nm or more. More preferably, it is 5 nm or more.
As the material of the first reflective layer 3, a material having a reasonably high reflectance at the wavelength of the reproduction light, for example, Au, Al, Ag, Cu, Ti, Cr, Ni, Pt, Ta, Pd, Mg, Se, Hf , V, Nb, Ru, W, Mn, Re, Fe, Co, Rh, Ir, Zn, Cd, Ga, In, Si, Ge, Te, Pb, Po, Sn, Bi, and rare earth metals and semi-metals It is possible to use a metal alone or as an alloy. Among these, Au, Al, and Ag have high reflectivity and are suitable as materials for the first reflective layer 3. In addition to these as main components, other components may be included.

Among these, those containing Ag as a main component are particularly preferable from the viewpoint of low cost and high reflectance. Here, the main component means one having a content of 50% or more.
Since the first reflective layer 3 has a small film thickness and large crystal grains in the film cause reproduction noise, it is preferable to use a material with small crystal grains. Since pure silver tends to have large crystal grains, Ag is preferably used as an alloy.

Among these, it is preferable to contain 0.1 to 15 atomic% of at least one element selected from the group consisting of Ag, Ti, Zn, Cu, Pd, Au, and rare earth metals. When two or more of Ti, Zn, Cu, Pd, Au, and rare earth metal are included, each may be 0.1 to 15 atomic%, but the total of these is preferably 0.1 to 15 atomic%. .
A particularly preferable alloy composition contains 0.1 to 15 atomic% of at least one element selected from the group consisting of Ti, Zn, Cu, Pd, and Au, containing Ag as a main component, and at least one rare earth element. Is contained in an amount of 0.1 to 15 atomic%. Of the rare earth metals, neodymium is particularly preferred. Specifically, AgPdCu, AgCuAu, AgCuAuNd, AgCuNd, and the like.

As the first reflective layer 3, a layer made only of Au is suitable because it has small crystal grains and is excellent in corrosion resistance. However, it is more expensive than Ag alloy.
It is also possible to use a layer made of Si as the first reflective layer 3.
It is also possible to form a multilayer film by alternately stacking a low refractive index thin film and a high refractive index thin film using a material other than metal, and use it as a reflective layer.

Examples of the method for forming the first reflective layer 3 include sputtering, ion plating, chemical vapor deposition, and vacuum vapor deposition. Further, a known inorganic or organic intermediate layer or adhesive layer is provided between the first substrate 1 and the first reflective layer 3 in order to improve reflectance, recording characteristics, adhesion, etc., for example. It may be provided. For example, an intermediate layer (or adhesive layer), a first recording layer 2, an intermediate layer (or adhesive layer), and a first reflective layer 3 are laminated on the first substrate 1 in this order, so that the first substrate 1 and the first substrate 1 are stacked together. An intermediate layer (or adhesive layer) may be provided between the recording layer 2 and an intermediate layer (or adhesive layer) may be provided between the first recording layer 2 and the first reflective layer 3.
(D) About the intermediate resin layer 4 In addition to the intermediate resin layer 4 being required to be transparent, grooves and pits must be formed by unevenness. Further, it is preferable that the adhesive strength is high and the shrinkage rate at the time of curing and bonding is small, the shape stability of the medium is high.

The intermediate resin layer 4 is preferably made of a material that does not damage the second recording layer 5. However, since the intermediate resin layer 4 is usually made of a resin, it is easily compatible with the second recording layer 5. In order to prevent this and prevent damage, it is desirable to provide a buffer layer described later between the two layers.
Furthermore, the intermediate resin layer 4 is preferably made of a material that does not damage the first reflective layer 3. However, in order to suppress damage, a buffer layer described later can be provided between both layers.

  In the present optical recording medium, it is preferable to control the film thickness of the intermediate resin layer 4 accurately. The film thickness of the intermediate resin layer 4 is usually preferably 5 μm or more. In order to separately apply focus servo to the two recording layers, it is necessary to have a certain distance between the two recording layers. Although it depends on the focus servo mechanism, it is usually required to be 5 μm or more, preferably 10 μm or more. In general, the higher the numerical aperture of the objective lens, the smaller the distance tends to be. However, if it is too thick, it takes time to adjust the focus servo to the two recording layers, and the moving distance of the objective lens becomes long, which is not preferable. Moreover, since there are problems such as requiring time for curing and lowering productivity, the thickness is usually preferably 100 μm or less.

The intermediate resin layer 4 is provided with irregularities in a spiral shape or concentric shape to form grooves and lands. Normally, information is recorded or reproduced on the second recording layer 5 using such grooves and / or lands as recording tracks. Usually, since the second recording layer 5 is formed by coating, it becomes thick at the groove and is suitable for recording or reproduction. In this optical recording medium, it is preferable that the groove of the intermediate resin layer 4, that is, the convex portion with respect to the light incident direction is the recording track 12. Here, a recessed part and a convex part say the recessed part and convex part with respect to the incident direction of light, respectively. Usually, the groove width is about 50 to 500 nm, and the groove depth is about 10 to 250 nm. When the recording track is spiral, the track pitch is preferably about 0.1 to 2.0 μm. In addition, it may have uneven pits such as land prepits as necessary.

From the viewpoint of cost, such irregularities are preferably produced by transferring and curing from a resin stamper having irregularities to a curable resin such as a photocurable resin. Hereinafter, such a method may be referred to as a 2P method (Photo Polymerization method).
Examples of the material of the intermediate resin layer 4 include a thermoplastic resin, a thermosetting resin, an electron beam curable resin, an ultraviolet curable resin (including a delayed curable type), and the like.

  A thermoplastic resin, a thermosetting resin, or the like can be formed by dissolving in an appropriate solvent to prepare a coating solution, coating it, and drying (heating). The ultraviolet curable resin can be formed by preparing a coating solution as it is or by dissolving it in a suitable solvent, and then applying the coating solution and curing it by irradiating with ultraviolet light. There are various types of ultraviolet curable resins, and any of them can be used as long as it is transparent. These materials may be used alone or in combination, and may be used not only as a single layer but also as a multilayer film.

  As a coating method, a method such as a spin coating method or a casting method is used as in the recording layer, and among these, the spin coating method is preferable. Alternatively, a resin having a high viscosity can be formed by screen printing or the like. It is preferable to use an ultraviolet curable resin that is liquid at 20 to 40 ° C. because it can be applied without using a solvent. The viscosity is preferably adjusted to 20 to 1000 mPa · s.

As the ultraviolet curable adhesive, there are a radical ultraviolet curable adhesive and a cationic ultraviolet curable adhesive, both of which can be used.
As the radical ultraviolet curable adhesive, all known compositions can be used, and a composition containing an ultraviolet curable compound and a photopolymerization initiator as essential components is used. As the ultraviolet curable compound, monofunctional (meth) acrylate or polyfunctional (meth) acrylate can be used as the polymerizable monomer component. These can be used alone or in combination of two or more. Here, in the present invention, acrylate and methacrylate are collectively referred to as (meth) acrylate.

  Examples of polymerizable monomers that can be used in the present optical recording medium include the following. Examples of the monofunctional (meth) acrylate include methyl, ethyl, propyl, butyl, amyl, 2-ethylhexyl, octyl, nonyl, dodecyl, hexadecyl, octadecyl, cyclohexyl, benzyl, methoxyethyl, butoxyethyl, phenoxyethyl, Nonylphenoxyethyl, tetrahydrofurfuryl, glycidyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-chloro-2-hydroxypropyl, dimethylaminoethyl, diethylaminoethyl, nonylphenoxyethyl tetrahydrofurfuryl, caprolactone modified tetrahydrofurfuryl, isobornyl , (Meth) acrylate having a group such as dicyclopentanyl, dicyclopentenyl, dicyclopentenyloxyethyl and the like.

Examples of the polyfunctional (meth) acrylate include 1,3-butylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol. Di (meth) such as neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, tricyclodecane dimethanol, ethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol Di (meth) acrylate of diol obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of acrylate, tris (2-hydroxyethyl) isocyanurate di (meth) acrylate, neopentyl glycol Diol di (meth) acrylate obtained by adding 2 mol of ethylene oxide or propylene oxide to 1 mol of bisphenol A, triol obtained by adding 3 mol or more of ethylene oxide or propylene oxide to 1 mol of trimethylolpropane Di or tri (meth) acrylate, di (meth) acrylate of diol obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of bisphenol A, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) Acrylate, poly (meth) acrylate of dipentaerythritol, ethylene oxide modified phosphoric acid (meth) acrylate, ethylene oxide modified alkylated phosphoric acid (meth) acrylate, etc. It is.

Moreover, what can be used together with the polymerizable monomer includes polyester (meth) acrylate, polyether (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate and the like as polymerizable oligomers.
Furthermore, as the photopolymerization initiator used in the present optical recording medium, any known one that can cure an ultraviolet curable compound represented by a polymerizable oligomer and / or a polymerizable monomer can be used. As the photopolymerization initiator, a molecular cleavage type or a hydrogen abstraction type is suitable for the optical recording medium.

  Examples of such include benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, benzyl, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-benzyl-2-dimethylamino-1- ( 4-morpholinophenyl) -butan-1-one, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, etc. are preferably used, and other molecular cleavage types 1-hydroxycyclohexyl phenyl ketone, benzoin ethyl ether, benzyldimethyl ketal, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methyl Propan-1-one and -Methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one or the like may be used in combination, and further a hydrogen abstraction type photopolymerization initiator, benzophenone, 4-phenylbenzophenone, isophthalphenone 4-benzoyl-4′-methyl-diphenyl sulfide and the like can be used in combination.

Examples of sensitizers for photopolymerization initiators include trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N, N-dimethylbenzyl. An amine that does not cause an addition reaction with the polymerizable component, such as an amine and 4,4′-bis (diethylamino) benzophenone, can also be used in combination. Of course, it is preferable to select and use the photopolymerization initiator and the sensitizer that are excellent in solubility in the ultraviolet curable compound and do not inhibit the ultraviolet transmittance.

Further, as the cationic ultraviolet curable adhesive, all known compositions can be used, and an epoxy resin containing a cationic polymerization type photoinitiator corresponds to this. Examples of cationic polymerization type photoinitiators include sulfonium salts, iodonium salts, and diazonium salts.
An example of an iodonium salt is as follows. Diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis (pentafluorophenyl) borate, bis (dodecylphenyl) iodonium hexafluorophosphate, bis (dodecylphenyl) iodonium hexafluoroantimonate Bis (dodecylphenyl) iodonium tetrafluoroborate, bis (dodecylphenyl) iodonium tetrakis (pentafluorophenyl) borate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium hexafluorophosphate, 4-methylphenyl-4 -(1-Methylethyl) phenyliodonium hexafluoroa Ntimonate, 4
-Methylphenyl-4- (1-methylethyl) phenyliodonium tetrafluoroborate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium tetrakis (pentafluorophenyl) borate, and the like.

The epoxy resin can be any of various types such as bisphenol A-epichlorohydrin type, alicyclic epoxy, long chain aliphatic type, brominated epoxy resin, glycidyl ester type, glycidyl ether type, and heterocyclic type. It doesn't matter.
As the epoxy resin, it is preferable to use an epoxy resin having a low free chlorine and chlorine ion content so as not to damage the reflective layer. The amount of chlorine is preferably 1% by weight or less, more preferably 0.5% by weight or less.

  The ratio of the cationic polymerization type photoinitiator per 100 parts by weight of the cationic ultraviolet curable resin is usually 0.1 to 20 parts by weight, preferably 0.2 to 5 parts by weight. A known photosensitizer can be used in combination in order to use the near-ultraviolet region and the visible region of the ultraviolet light source more effectively. Examples of the photosensitizer at this time include anthracene, phenothiazine, benzylmethyl ketal, benzophenone, and acetophenone.

In addition, UV curable adhesives include, as necessary, other additives such as thermal polymerization inhibitors, antioxidants typified by hindered phenols, hindered amines, phosphites, plasticizers and epoxy silanes, mercapto. Silane coupling agents represented by silane, (meth) acrylic silane and the like can also be blended for the purpose of improving various properties. These are selected from those having excellent solubility in ultraviolet curable compounds and those that do not impair ultraviolet transparency.
(E) Second Recording Layer 5 The second recording layer 5 is usually a single-sided recording medium (for example, CD-R, DVD-R, DVD + R).
It has higher sensitivity than the recording layer used for the above. In the present optical recording medium, since the power of the incident light beam decreases due to the presence of the first recording layer 2 and the first reflecting layer 3, etc., it is necessary to have particularly high sensitivity in order to record at about half the power. It is.

In order to realize good recording / reproducing characteristics, it is desirable that the dye has a low heat generation and a high refractive index.
Further, in the combination of the second recording layer 5 and the second reflective layer 6, it is desirable that the reflection and absorption of light be in an appropriate range. The recording sensitivity can be increased and the thermal interference during recording can be reduced.
Since the material of the second recording layer 5, the film forming method, and the like are described in substantially the same manner as in the first recording layer 2, only different points will be described.

  The film thickness of the second recording layer 5 is not particularly limited because it varies depending on the recording method and the like. However, in order to obtain a sufficient degree of modulation, it is usually preferably 10 nm or more, more preferably 30 nm or more. And particularly preferably 50 nm or more. However, since it is not necessary to be too thick in order to obtain an appropriate reflectance, it is usually 3 μm or less, preferably 1 μm or less, more preferably 200 nm or less.

The materials used for the first recording layer 2 and the second recording layer 5 may be the same or different.
(F) About the 2nd reflective layer 6 The 2nd reflective layer 6 needs to be a high reflectance. Moreover, it is desirable that it is highly durable.
In order to ensure a high reflectance, the thickness of the second reflective layer 6 is usually preferably 20 nm or more. More preferably, it is 30 nm or more. More preferably, it is 50 nm or more. However, in order to shorten the production tact time and reduce the cost, it is preferable to be thin to some extent, and is usually 400 nm or less. More preferably, it is set to 300 nm or less.

  As a material of the second reflective layer 6, a material having a sufficiently high reflectance at the wavelength of the reproduction light, for example, a metal such as Au, Al, Ag, Cu, Ti, Cr, Ni, Pt, Ta, and Pd is used alone or in an alloy. Can be used. Among these, Au, Al, and Ag have high reflectivity and are suitable as materials for the second reflective layer 6. In addition to these as main components, the following components may be included as other components. Examples of other components include Mg, Se, Hf, V, Nb, Ru, W, Mn, Re, Fe, Co, Rh, Ir, Cu, Zn, Cd, Ga, In, Si, Ge, Te, Pb Mention may be made of metals and metalloids such as Po, Sn, Bi and rare earth metals.

Among them, those containing Ag as a main component are particularly preferred because they are low in cost, easily exhibit high reflectivity, and when a print receiving layer described later is provided, a white and beautiful ground color can be obtained. Here, the main component means one having a content of 50% or more.
In order to ensure high durability (high corrosion resistance), the second reflective layer 6 is preferably used as an alloy rather than pure silver.

Among these, it is preferable to contain 0.1 to 15 atomic% of at least one element selected from the group consisting of Ag, Ti, Zn, Cu, Pd, Au, and rare earth metals. When two or more of Ti, Zn, Cu, Pd, Au, and rare earth metal are included, each may be 0.1 to 15 atomic%, but the total of these is preferably 0.1 to 15 atomic%. .
A particularly preferable alloy composition contains 0.1 to 15 atomic% of at least one element selected from the group consisting of Ti, Zn, Cu, Pd, and Au, containing Ag as a main component, and at least one rare earth element. Is contained in an amount of 0.1 to 15 atomic%. Of the rare earth metals, neodymium is particularly preferred. Specifically, AgPdCu, AgCuAu, AgCuAuNd, AgCuNd, and the like.

As the second reflective layer 6, a layer made only of Au is preferable because of its high durability (high corrosion resistance). However, it is more expensive than Ag alloy.
A multilayer film can be formed by alternately stacking a low refractive index thin film and a high refractive index thin film using a material other than metal, and can be used as the second reflective layer 6.
Examples of the method for forming the second reflective layer 6 include sputtering, ion plating, chemical vapor deposition, and vacuum vapor deposition. In addition, a known inorganic or organic intermediate layer or adhesive layer may be provided above and below the second reflective layer 6 in order to improve reflectance, recording characteristics, adhesion, and the like.
(G) Adhesive layer 7 The adhesive layer 7 does not need to be transparent, but it is preferable that the adhesive strength is high and the shrinkage rate at the time of curing adhesion is small, the medium has high shape stability.

The adhesive layer 7 is preferably made of a material that does not damage the second reflective layer 6. However, a known inorganic or organic protective layer may be provided between both layers in order to suppress damage.
In the present optical recording medium, the film thickness of the adhesive layer 7 is usually preferably 2 μm or more. In order to obtain a predetermined adhesive strength, a certain film thickness is required. More preferably, it is 5 μm or more. However, in order to make the optical recording medium as thin as possible, and there is a problem that it takes time for curing and productivity is lowered.

The material of the adhesive layer 7 can be the same as the material of the intermediate resin layer 4, and a pressure-sensitive double-sided tape or the like can also be used. The adhesive layer 7 can be formed by sandwiching and pressing a pressure sensitive double-sided tape between the second reflective layer 6 and the second substrate 8.
(H) Regarding the second substrate 8 The second substrate 8 preferably has shape stability so that the optical recording medium has a certain degree of rigidity. That is, it is preferable that mechanical stability is high and rigidity is large. Moreover, it is desirable that the adhesiveness with the adhesive layer 7 is high.

As described above, when the first substrate 1 does not have sufficient shape stability, the second substrate 8 needs to have particularly high shape stability. In this respect, it is desirable that the hygroscopicity is small. However, the second substrate 8 does not need to be transparent. The second substrate 8 may be a mirror substrate, and it is not necessary to form irregularities, so that the transferability by injection molding is not necessarily good.
As such a material, the same material as that which can be used for the first substrate 1 can be used. For example, an Al alloy substrate such as an Al—Mg alloy containing Al as a main component, or an Mg alloy as a main component, for example. An Mg alloy substrate such as an Mg—Zn alloy, a substrate made of any of silicon, titanium, and ceramics, a substrate that combines them, and the like can be used.

Polycarbonate is preferred from the viewpoints of high productivity such as moldability, cost, low hygroscopicity, and shape stability. Amorphous polyolefin is preferred from the standpoint of chemical resistance and low hygroscopicity. Moreover, a glass substrate is preferable from the viewpoint of high-speed response.
In order to give the optical recording medium sufficient rigidity, the second substrate 8 is preferably thick to some extent, and the thickness is preferably 0.3 mm or more. However, the thinner one is advantageous for thinning the recording / reproducing apparatus, and it is preferably 3 mm or less. More preferably, it is 1.5 mm or less.

The second substrate 8 may be a mirror substrate having no irregularities, but is preferably manufactured by injection molding from the viewpoint of ease of production.
As an example of a preferable combination of the first substrate 1 and the second substrate 8, the first substrate 1 and the second substrate 8 are made of the same material and have the same thickness. Since the rigidity is equal and balanced, it is preferable that the medium is difficult to be deformed against environmental changes. In this case, it is preferable that the degree and direction of deformation when the environment changes are the same for both substrates.

As an example of another preferable combination, the first substrate 1 is as thin as about 0.1 mm, and the second substrate 8 is as thick as about 1.1 mm. The objective lens is preferable because it easily approaches the recording layer and easily increases the recording density. At this time, the first substrate 1 may be in the form of a sheet.
(I) Other layers In the above laminated structure, any other layers may be sandwiched as necessary. Alternatively, any other layer may be provided on the outermost surface of the medium. Specifically, the intermediate layer is provided between the first reflective layer 3 and the intermediate resin layer 4, between the intermediate resin layer 4 and the second recording layer 5, between the second reflective layer 6 and the adhesive layer 7, and the like. A buffer layer may be provided.

The buffer layer prevents the two layers from mixing and prevents compatibility. The buffer layer may also serve other functions than preventing the mixing phenomenon. Further, another intermediate layer may be interposed as required.
The material of the buffer layer is not compatible with the second recording layer 5 or the intermediate resin layer 4 and needs to have a certain degree of light transmittance, but known inorganic and organic materials can be used. In view of characteristics, an inorganic material is preferably used. For example, (i) metal or semiconductor, (ii) metal or semiconductor oxide,
Nitride, sulfide, oxysulfide, fluoride or carbide, or (iii) amorphous carbon is used. Among them, a layer made of a substantially transparent dielectric or a very thin metal layer (including an alloy) is preferable.

Specifically, silicon oxide, particularly silicon dioxide, oxides such as zinc oxide, cerium oxide, yttrium oxide; sulfides such as zinc sulfide and yttrium sulfide; nitrides such as silicon nitride; silicon carbide; oxide and sulfur A mixture thereof (oxysulfide); and alloys described later are suitable. Further, a mixture of about 30:70 to 90:10 (weight ratio) of silicon oxide and zinc sulfide is also suitable. A mixture of sulfur, yttrium dioxide and zinc oxide (Y ₂ O ₂ S—ZnO) is also suitable.

  As the metal or alloy, silver or a material containing 0.1 to 15 atomic% of at least one element selected from the group consisting of titanium, zinc, copper, palladium, and gold, which is mainly composed of silver, is preferable. is there. Further, those containing silver as a main component and containing 0.1 to 15 atomic% of at least one rare earth element are also suitable. As this rare earth, neodymium, praseodymium, cerium and the like are suitable.

In addition, a resin layer may be used as long as it does not dissolve the dye in the recording layer when the buffer layer is produced. In particular, a polymer film that can be produced by vacuum deposition or CVD is useful.
The thickness of the buffer layer is preferably 2 nm or more, more preferably 5 nm or more. If the thickness of the buffer layer is excessively thin, there is a possibility that the prevention of the above mixing phenomenon will be insufficient. However, it is preferably 2000 nm or less, more preferably 500 nm or less. If the buffer layer is excessively thick, it is not only unnecessary for preventing mixing but also may reduce the light transmittance. In the case of a layer made of an inorganic material, it takes a long time to form a film, and the productivity may be lowered or the film stress may be increased. In particular, in the case of a metal, about 20 nm or less is preferable because the light transmittance is excessively lowered.

A protective layer may be provided to protect the recording layer and the reflective layer. The material of the protective layer is not particularly limited as long as it can protect the recording layer and the reflective layer from external force. Examples of the material of the organic substance include a thermoplastic resin, a thermosetting resin, an electron beam curable resin, and an ultraviolet curable resin. Examples of the inorganic substance include silicon oxide, silicon nitride, MgF ₂ , SnO _{2 and the} like.

  A thermoplastic resin, a thermosetting resin, etc. can be formed by dissolving in an appropriate solvent to prepare a coating solution, and applying and drying the coating solution. The ultraviolet curable resin can be formed by preparing a coating solution as it is or by dissolving it in a suitable solvent, and then applying the coating solution and curing it by irradiation with UV light. As the ultraviolet curable resin, for example, acrylate resins such as urethane acrylate, epoxy acrylate, and polyester acrylate can be used. These materials may be used alone or in combination, and may be used not only as a single layer but also as a multilayer film.

As a method for forming the protective layer, a coating method such as a spin coating method and a casting method, a sputtering method, a chemical vapor deposition method, and the like are used as in the recording layer. Among these, a spin coating method is preferable.
The thickness of the protective layer is generally in the range of 0.1 to 100 μm, but in the present optical recording medium, 3 to 50 μm is preferable.

Furthermore, the above optical recording medium can be printed on a surface that is not the incident surface of recording light or reproducing light as required by various printers such as inkjet and thermal transfer, or various writing tools. A layer may be provided.
Alternatively, a recording layer may be provided in addition to the main layer configuration, and the recording layer may be three or more layers. Further, it is possible to make a larger-capacity medium having four recording layers by laminating two optical recording media of this layer configuration and the first substrate 1 facing outside.
(B) Type 2
FIG. 2 is a schematic sectional view showing the optical recording medium (type 2) according to the present embodiment.

  The type 2 optical recording medium (bonded single-sided optical recording medium) according to the present embodiment is a disc-shaped transparent (light transmissive) first substrate (first substrate, first light transmissive property). On a substrate 21, a first recording layer (first recording layer, first dye-containing recording layer) 22 containing a dye, a semitransparent first reflective layer (hereinafter also referred to as a semitransparent reflective layer) 23, and transparent adhesion Layer (intermediate layer) 24, buffer layer 28, second recording layer containing dye (second recording layer, second dye-containing recording layer) 25, second reflective layer 26, disk-shaped transparent second substrate (first 2 substrates) 27 in this order. The light beam is irradiated from the first substrate 21 side, and recording or reproduction is performed. The term “transparent” means transparent to a light beam used for recording or reproduction on an optical recording medium.

Concavities and convexities are formed on the first substrate 21 and the second substrate 27, respectively, and constitute recording tracks. The recording track 31 on the first substrate 21 has a convex portion with respect to the light incident direction. The recording track 32 on the second substrate 27 is constituted by a concave portion with respect to the light incident direction.
The recording track 31 is configured by a groove portion of the first substrate 21, that is, a concave portion with respect to the light incident direction, and the recording track 32 is a groove portion of the second substrate 27, that is, a convex portion with respect to the light incident direction. In general, the recording track 31 is preferably formed of a convex portion with respect to the light incident direction, and the recording track 32 is preferably formed of a concave portion with respect to the light incident direction. In addition, there may be uneven pits as necessary. Unless otherwise specified, in this embodiment, the unevenness is defined with respect to the incident direction of light used for recording or reproduction.

Next, each layer will be described.
The first substrate 21, the first recording layer 22, the first reflective layer 23, the second recording layer 25, and the second reflective layer 26 of the type 2 optical recording medium according to the present embodiment are each of the type 1 optical recording medium. The first substrate 1, the first recording layer 2, the first reflective layer 3, the second recording layer 5, and the second reflective layer 6 are substantially the same.
The transparent adhesive layer 24 as an intermediate layer is substantially the same as the intermediate resin layer 4 of the type 1 optical recording medium, except that it is not necessary to form grooves or pits due to unevenness. In the type 2 optical recording medium, the grooves and pits are formed on the second substrate 27 described later.

Furthermore, the buffer layer 28 as an intermediate layer has substantially the same configuration as the buffer layer described in the first embodiment. This buffer layer may be formed as necessary.
The second substrate 27 is preferably transparent and has shape stability so that the optical recording medium has a certain degree of rigidity. That is, it is preferable that mechanical stability is high and rigidity is large.

Examples of such materials include those made of resins such as acrylic resins, methacrylic resins, polycarbonate resins, polyolefin resins (particularly amorphous polyolefins), polyester resins, polystyrene resins, epoxy resins, and the like. Can be used.
Concavities and convexities are provided on the second substrate 27 in a spiral shape or concentric shape to form grooves and lands. Normally, information is recorded or reproduced on the second recording layer 25 using such grooves and / or lands as recording tracks. Usually, since the second recording layer 25 is formed by coating, it becomes thick at the groove and is suitable for recording or reproduction. In the present optical recording medium, it is preferable that the groove portion of the second substrate 27, that is, the concave portion with respect to the light incident direction is the recording track 32. Here, a recessed part and a convex part say the recessed part and convex part with respect to the incident direction of light, respectively. Usually, the groove width is about 50 to 500 nm, and the groove depth is about 10 to 250 nm. When the recording track is spiral, the track pitch is preferably about 0.1 to 2.0 μm. In addition, it may have uneven pits such as land prepits as necessary.

From the viewpoint of cost, the second substrate 27 having such irregularities is preferably manufactured by injection molding using a resin from a stamper having irregularities. When a resin layer made of a radiation curable resin such as a photocurable resin is provided on a substrate such as glass, irregularities such as recording tracks may be formed on the resin layer.
Here, the write-once type optical recording medium (here, DVD-R) including the dye-containing recording layer has been described, but the optical recording medium is not limited to this, and information is obtained by irradiation with laser light from one side. The optical recording medium may be provided with a plurality of recording layers capable of recording or reproducing data. For example, as a recording layer, for example, a rewritable optical recording medium (for example, DVD-RW, DVD + RW, DVD-RAM, etc.) or a magneto-optical type optical recording medium including a magnetic recording layer as a recording layer.

Here, when the optical recording medium is a DVD-RW, address information may be recorded in advance by land pre-pits as in the case of the above-described DVD-R. When the optical recording medium is DVD + RW, the address information may be preliminarily recorded by superimposing it on the wobble (this is called ADIP; Address in Pre-groove).
Further, when the present invention is applied to a rewritable optical recording medium including a phase change recording layer, both the first recording layer and the second recording layer of the optical recording medium in the above-described embodiment are the first protective layer. , An information recording layer, and a second protective layer.

  Here, as a material of the information recording layer, it is preferable to use a material whose optical constants (refractive index n, extinction coefficient k) change when irradiated with laser light. Such materials include Te and Se-based chalcogenides such as Ge—Sb—Te, Ge—Te, Pd—Ge—Sb—Te, In—Sb—Te, Sb—Te, and Ag—In—Sb. -Te, Ge-Sb-Bi-Te, Ge-Sb-Se-Te, Ge-Sn-Te, Ge-Sn-Te-Au, Ge-Sb-Te-Cr, In-Se, In-Se-Co Etc., and alloy systems in which nitrogen, oxygen or the like is appropriately added to these.

  In addition, as materials for the first protective layer and the second protective layer, suppression of noise increase due to thermal damage of the protective substrate, the information recording layer, etc. at the time of laser light irradiation, reflectivity for laser light, absorption rate, and reflected light For the purpose of adjusting the phase or the like, it is preferable to use a material that is physically and chemically stable, has a melting point and a softening temperature higher than those of the information recording layer, and is incompatible with the material of the information recording layer. Examples of such materials include oxides such as Y, Ce, Ti, Zr, Nb, Ta, Co, Zn, A1, Si, Ge, Sn, Pb, Sb, Bi, and Te, Ti, Zr, and Nb. , Ta, Cr, Mo, W, B, A1, Ga, In, Si, Ge, Sn, Pb and other nitrides, Ti, Zr, Nb, Ta, Cr, Mo, W, Si and other carbides, Zn, Examples thereof include a dielectric such as sulfide such as Cd, a selenide or telluride, a fluoride such as Mg and Ca, a simple substance such as C, Si and Ge, or a mixture thereof, or a material equivalent to the dielectric. In addition, although the same material can also be used for the first protective layer and the second protective layer, different materials may be used as necessary.

  By the way, as described above, there are a plurality of (here, two) recording layers 2 and 5 (22 and 25), and each layer 2 and 5 (22 and 25) is irradiated with laser light from one side. In a single-sided incident optical recording medium for recording or reproducing information (for example, dual-layer type single-sided DVD-R), optimum recording / reproducing conditions such as recording pulse strategy, recording power, reproducing power, etc. for each recording layer Will be very different. Note that the recording / reproducing conditions include a recording condition such as a recording pulse strategy (write strategy) and recording power, and a reproducing condition such as reproducing power.

In particular, it is important to optimize the recording conditions. This means that even if the playback conditions are slightly different, it is unlikely that playback will not be possible, but if the recording conditions are not optimal, it will not be possible to write, or even if the information can be played back, This is because the signal quality is not good.
Therefore, in the recording / reproducing apparatus (drive) for recording / reproducing information on / from each recording layer 2, 5 (22, 25) of the single-sided incident type optical recording medium having a plurality of recording layers, the recording layers 2, 5 In accordance with (22, 25), for example, it is desired to be able to switch recording / reproduction conditions such as recording pulse strategy, recording power, reproduction power, etc., so that information can be recorded or reproduced accurately and reliably. In particular, since it is important to optimize the recording conditions as described above, it is possible to switch to the optimum recording conditions according to the recording layers 2 and 5 (22 and 25), and to record information. Want to be able to do it accurately and reliably.

In this case, for example, it is conceivable to add address information continuously over a plurality of recording layers 2, 5 (22, 25), and to determine which layer is based on the read address information in the recording / reproducing apparatus. However, it is difficult to instantly determine which layer it is.
Therefore, in the present embodiment, for example, a recording pulse strategy (recording strategy, write strategy), recording power, reproducing power, etc., according to the recording layers 2 and 5 (22, 25) to record or reproduce information. Layer information (information relating to the recording layer number; layer 0, layer 1) is recorded in each of the recording layers 2, 5 (22, 25) of the optical recording medium so that the recording / reproducing conditions can be switched instantaneously. Yes.

Here, as a recording method of the layer information, for example, the following methods (i) and (ii) can be considered.
(i) Recording is performed, for example, by prepits (land prepits) or wobbles in a recording management area (RMA; Recording Management Area, for example, control track, innermost part) of each recording layer 2, 5 (22, 25).
(ii) Recording is performed over almost the entire recording area of each recording layer 2, 5 (22, 25) by, for example, pre-pits (land pre-pits) or wobbles. Here, in order to record “substantially the entire surface”, when recording is performed on the entire recording area including the recording management area of each recording layer 2, 5 (22, 25) (for example, recording is performed as a part of the address in the recording management area). And the case of recording on the entire surface of the recording area excluding the recording management area of each recording layer 2, 5 (22, 25). In particular, when layer information cannot be recorded in the recording management area, it is effective to record over the entire recording area except the recording management area. It is also effective when recording or reproducing information with random access.

  For example, it may be recorded as a part of wobble or pre-pit (land pre-pit) address information. Thereby, layer information can be recorded on each recording layer 2, 5 (22, 25) by a simple method. Also, by recording layer information as part of the address information, when performing random access based on the address information and recording or reproducing information, the layer information can be obtained simply by accessing the desired address and applying focus servo. Since information can be read, recording / reproducing conditions such as recording pulse strategy, recording power, and reproducing power can be instantaneously switched based on the information.

Here, as a method for recording the layer information as a part of the address information, for example, the following methods (i) to (v) are conceivable.
(i) First, as a method of recording as a part of wobble address information (for example, ADIP; Address in pre-groove), wobble address information (for example, ADIP; for example) in two recording layers 2 and 5 (22, 25). There is a method of inverting the sync pattern (synchronization pattern) included in (Address in pre-groove).

For example, the direction of the sync pattern (synchronization pattern) included in the ADIP of the second recording layer 5 (25) is reversed with respect to the direction of the sync pattern (synchronization pattern) included in the ADIP of the first recording layer 2 (22). The direction (reversal) may be set.
(ii) As a method of recording as part of address information of wobbles and land prepits formed in the recording areas (including the recording management area) of the recording layers 2, 5 (22, 25), There is a method in which the value of the reserve bit is different in 2, 5 (22, 25).

For example, the value of the reserved bit of the wobble or LPP address information formed in the recording area (including the recording management area) of the first recording layer 2 (22) is set to the recording area (recording) of the second recording layer 5 (25). It may be different from the value of the reserved bit of the address information of wobbles and land prepits formed in the management area).
Here, the reserved bit refers to a bit in a portion not currently used in an area where address information is recorded. For recording information in the reserved bits, the same modulation scheme and recording scheme as the address information may be applied. Further, when a plurality of recording layers are provided, it is necessary to increase the number of reserved bits to be used according to the number of recording layers. For example, in the case of having two recording layers, one bit is used as a reserve bit, and the first layer and the second layer may be distinguished depending on whether this value is 0 or 1. In addition, if 2 bits are used as reserved bits, four values of 00, 01, 10, and 11 can be expressed by 2 bits, so that the four recording layers can be distinguished. Similarly, if 3 bits are used as reserve bits, 8 values can be expressed, so that 8 recording layers can be distinguished. That is, if n bits are used as reserved bits, 2 ⁿ recording layers can be distinguished. Note that the number of reserved bits to be used can be reduced by combining with other methods such as the above method (i) and the following methods (iii) to (v).
(iii) As a method of recording as part of wobble and land prepit address information formed in the recording area (including the recording management area) of each recording layer 2, 5 (22, 25), two recordings are performed. There is a method in which the entire address information of wobbles or land prepits in any one of the recording layers 2 and 5 (22 and 25) is bit-inverted.

For example, when the address 3000 to 4FFF (Hex) is placed in the first recording layer 2 (22) and the address 5000 to 6FFF (Hex) is placed in the second recording layer 5 (25), the second recording layer 5 (25 ) Only, and the address is set to AFFF to 9000 (Hex).
Here, in order to simplify the explanation, it has been described with only 16 bits (4 digits in hexadecimal), but in reality, for example, in DVD-R, the address information is 48 bits (12 digits in hexadecimal). Therefore, the address of the first recording layer 2 (22) is 000000003000 to 000000004FFF (Hex), and the address of the second recording layer 5 (25) is FFFFFFFFAFFF to FFFFFFFF9000 (Hex).

The drive needs to have information that associates which range of addresses belongs to which layer so that the layer can be identified when the address is read.
(iv) As a method of recording as part of address information of wobbles and land prepits formed in the recording areas (including the recording management area) of the recording layers 2 and 5 (22 and 25), two recordings are performed. There is a method in which the entire address information of the wobble or land pre-pit of one of the recording layers in layers 2 and 5 (22, 25) is represented by 2's complement (overall bit inversion + 1).

For example, when the address 3000 to 4FFF (Hex) is placed in the first recording layer 2 (22) and the address 5000 to 6FFF (Hex) is placed in the second recording layer 5 (25), the second recording layer 5 (25 ) Is represented by 2's complement (overall bit inversion +1), and the address may be B000 to 9001 (Hex).
Here, in order to simplify the explanation, it has been described with only 16 bits (4 digits in hexadecimal), but in reality, for example, in DVD-R, the address information is 48 bits (12 digits in hexadecimal). Therefore, the address of the first recording layer 2 (22) is 000000003000 to 000000004FFF (Hex), and the address of the second recording layer 5 (25) is FF.
FFFFFFB000 to FFFFFFFF9001 (Hex).

The drive needs to have information that associates which range of addresses belongs to which layer so that the layer can be identified when the address is read.
(v) Further, as a method of recording as part of address information of wobbles and land prepits formed in the recording areas (including the recording management area) of each recording layer 2, 5 (22, 25), two recordings are performed. There is a method of recording in the most significant bit of wobble or land pre-pit address information in one of the recording layers in layers 2 and 5 (22, 25).

For example, the value obtained by bit-inverting the value of the most significant bit of the address information of the wobble or land prepit of one of the first recording layer 2 (22) and the second recording layer 5 (25) The wobble or land pre-pit address information of the other recording layer is put in the most significant bit.
Specifically, for example, when the address 000000003000 to 000000004FFF (Hex) is inserted into the first recording layer 2 (22) and the address 000000005000 to 000000006FFF (Hex) is inserted into the second recording layer 5 (25), the second recording is performed. Only the most significant bit of the layer 5 (25) needs to be inverted.

  In this case, when bit inversion is performed in binary, “0” becomes “1”, but when this is expressed in hexadecimal (Hex), “0” becomes “8”. Therefore, the address of the first recording layer 2 (22) is 000000003000 to 000000004FFF (Hex), and the address of the second recording layer 5 (25) is 800000000000 to 8000000006FFF (Hex). The drive needs to recognize the most significant 1 bit of the address as layer information.

Here, the case where the present invention is applied to an optical recording medium having two recording layers capable of recording or reproducing information by irradiation with a laser beam from one side has been described, but the present invention is not limited to this. For example, the above-described layer information recording method may be applied alone or in combination to an optical recording medium having three or more recording layers and capable of recording or reproducing information by laser light irradiation from one side. it can. In this case, the layer information recording method described above may be applied to two adjacent recording layers among the plurality of recording layers.
(2) Recording / Reproducing Method of Optical Recording Medium Hereinafter, an outline of a recording / reproducing method of the optical recording medium configured as described above will be described.

In recording on the optical recording medium (type 1 and type 2) obtained as described above, a laser beam focused on the recording layer with a diameter of about 0.5 to 1 μm is irradiated from the first substrate 1 and 21 side. By doing. In the portion irradiated with the laser beam, thermal deformation of the recording layer such as decomposition, heat generation, and melting due to absorption of laser beam energy occurs, and the optical characteristics change.
The recorded information is reproduced by reading the difference in reflectance between the portion where the change in optical characteristics has occurred and the portion where the change has not occurred with the laser beam.

  In addition, recording or reproduction is individually performed on the two recording layers as follows. The first recording layers 2 and 22 and the second recording layers 5 and 25 can be distinguished from each other by the focus error signal obtained by the knife edge method, astigmatism method, Foucault method or the like on the focusing position of the focused laser. That is, when the objective lens for focusing the laser beam is moved up and down, S-shaped curves are respectively obtained at the positions corresponding to the first recording layers 2 and 22 and the positions corresponding to the second recording layers 5 and 25, respectively. can get. Depending on which S-curve is used for the focus servo, it is possible to select which of the first recording layers 2 and 22 and the second recording layers 5 and 25 is to be recorded or reproduced.

In the type 1 optical recording medium, preferably, as shown in FIG. 1, the first substrate 1 and the intermediate resin layer 4 are respectively provided with irregularities, and the convex portions of the first substrate 1 and the intermediate resin layer 4 are formed. Recording or reproduction is performed as a recording track. Usually, since the dye recording layer is formed by coating, it becomes thick at the groove and is suitable for recording or reproduction. In the type 1 optical recording medium, the groove portion of the first substrate 1, that is, the convex portion with respect to the light incident direction is used as the recording track 11, and the groove portion of the intermediate resin layer 4, ie, the convex portion is recorded with respect to the light incident direction. The track 12 is preferable.

  In the type 2 optical recording medium, preferably, as shown in FIG. 2, the first substrate 21 and the second substrate 27 are respectively provided with irregularities, and the convex portions of the first substrate 21 and the concave portions of the second substrate 27 are formed. Is recorded or reproduced as a recording track. Note that the polarity of the tracking servo may be reversed between the first recording layer 22 and the second recording layer 25. In the type 2 optical recording medium, the groove portion of the first substrate 21, that is, the convex portion with respect to the light incident direction is used as the recording track 31, and the groove portion of the second substrate 27, that is, the concave portion with respect to the light incident direction is used as the recording track. 32 is preferable.

The laser light used for this optical recording medium (type 1 and type 2) is N ₂ , He−
Cd, Ar, He—Ne, ruby, semiconductor, dye laser, and the like can be given. A semiconductor laser is preferable because it is lightweight, compact, and easy to handle.
The laser beam used is preferably as short as possible for high-density recording, but a laser beam of 350 to 530 nm is particularly preferable. Typical examples of such laser light include laser light having center wavelengths of 405 nm, 410 nm, and 515 nm.

  An example of laser light having a wavelength in the range of 350 to 530 nm can be obtained by using a high-power semiconductor laser of 405 nm, 410 nm blue or 515 nm blue-green, but for example, (a) the fundamental oscillation wavelength is Either a semiconductor laser capable of continuous oscillation of 740 to 960 nm, or (b) a solid laser capable of continuous oscillation excited by a semiconductor laser and having a fundamental oscillation wavelength of 740 to 960 nm is generated by a second harmonic generation element (SHG). It can also be obtained by wavelength conversion.

The SHG may be any piezoelectric element that lacks inversion symmetry, but KDP, ADP, BNN, KN, LBO, a compound semiconductor, and the like are preferable. As a specific example of the second harmonic, in the case of a semiconductor laser having a fundamental oscillation wavelength of 860 nm, a harmonic of 430 nm, and in the case of a solid-state laser excited by a semiconductor laser, a Cr-doped LiSrAlF ₆ crystal (basic oscillation wavelength of 860 nm) 430 nm of the double wave from.
(3) Optical Recording Medium Recording / Reproducing Device By the way, as described above, light for recording or reproducing information on an optical recording medium in which information relating to the recording layer number (layer information) is recorded in each recording layer. A recording / reproducing apparatus for a recording medium is configured as follows.

The recording / reproducing device (drive) may be any device that can record or reproduce information recorded on the optical recording medium. For example, a recording device (writer) that performs only recording, or a reproducing device that performs only reproduction. (Reader), and a recording / reproducing apparatus (reader / writer) that performs both recording and reproduction.
As shown in FIG. 3, the recording / reproducing apparatus 60 includes a spindle motor 51 that rotates the optical recording medium 50, a motor driver 52 that drives the spindle motor 51, an optical pickup 53, and a light that drives the optical pickup 53. A pickup driver 54, a servo processor 55 used to perform various servo controls, a signal processing unit (reproduction processing unit) 56 for processing a signal detected by the optical pickup 53, and other computers are sent. A data processing unit (recording processing unit) 57 that processes incoming information (data) and a control unit 58 (for example, a microcomputer including a CPU 58A and a memory 58B) that controls each device are configured.

Here, the optical pickup 53 is configured to include, for example, a laser diode, a photodetector (for example, a photodetector), a pickup actuator used for focusing and tracking, and the like.
As shown in FIG. 3, the optical pickup driver 54 includes a laser driver (laser diode driver) 54A for driving a laser diode, a focus driver 54B for driving a pickup actuator, a tracking driver 54C for driving the pickup actuator, and 54C. And is configured to include.

Here, the laser driver 54A is configured to include a reproducing laser driver 54Aa for driving a reproducing laser diode and a recording laser driver 54Ab for driving a recording laser diode.
The servo processor 55 includes a focus servo circuit 55A for performing focus servo and a tracking servo circuit 55B for performing tracking servo.

  The signal processing unit 56 amplifies a signal detected by the optical pickup 53, a focus error signal, a tracking error signal, a wobble or land prepit address signal [address information (address information) from the detection signal amplified by the preamplifier 56A. Matrix circuit 56B for generating a data signal (information including layer information)], and a demodulation circuit for demodulating an address signal [address information; including recording layer number (layer information)] generated by the matrix circuit 56B 56C. The data signal is processed through a binarization circuit and a demodulation circuit (not shown) and then sent to a computer or the like.

When the address information including the layer information is recorded by pre-pits (ROM pits) when the optical recording medium 50 is manufactured, the signal processing unit 56 includes a matrix circuit, a binarization circuit, a demodulation circuit, What is necessary is just to comprise as what is provided.
The data processing unit 57 modulates data sent from another computer or the like together with address information, and controls recording pulses for the recording laser driver 54Ab based on the modulated data (recording pulse And a recording strategy circuit (write strategy circuit) 57B that performs multi-pulse modulation.

Next, regarding processing (recording / reproducing method, recording method, reproducing method of optical recording medium) performed by the control unit 58 of the recording / reproducing apparatus 60 of the optical recording medium configured as described above executing a predetermined program, This will be described with reference to FIG.
Here, there is a case where information is recorded (or reproduced) on an optical recording medium 50 having two recording layers 2 and 5 (22, 25) and layer information recorded on almost the entire surface of the recording layer. Explained as an example.

  The optical recording medium recording / reproducing device (drive) 60 receives a recording command from a computer such as a personal computer (or via an input unit such as a button provided in the drive itself), for example, the control unit 58. However, the table of contents information area included in the recording area of the medium is accessed to determine which address is writable. Then, based on the address determined to be writable, it is determined in which recording layer recording is to be performed (step S10). When accessing the table of contents information area when the medium is set in the drive and reading out the table of contents information in advance, it is possible to write to which address using the table of contents information read out in advance. It may be determined.

Here, when the layer information is included in the address information, it is possible to determine which recording layer is recorded by detecting the layer information included in the address information, and the address information on the drive side. When a table that associates layer information with layer information is provided, layer information can be determined from address information using this table.
On the other hand, when a reproduction command is input from a computer such as a personal computer (or via an input unit such as a button provided in the drive itself), the control unit 58 is based on the address information included in the reproduction command. The recording layer to be recorded is determined (step S10).

Here, when the medium is set in the drive, the table of contents information (information indicating which information is recorded at which address) is read from the medium, and an icon is displayed on the computer screen, for example. When clicked, a playback command including address information may be input to the drive.
As described above, when the recording command (or reproduction command) is input, the control unit 58 specifies the recording layer to be recorded (or reproduced). The function of the control unit 58 is called a recording layer determining unit (recording layer specifying unit).

  When a recording command (or playback command) is input, the control unit 58 issues a focus servo command to the focus servo circuit 55A, and the focus servo circuit 55A that has received this command receives the focus driver 54B or the pickup. By controlling the optical pickup 53 via the actuator, focus servo is applied to any one of the first recording layer 2 (22) and the second recording layer 5 (25) (step S20). . The function of the control unit 58 is referred to as a focus servo control unit.

  Here, when layer information is recorded as a part of the address information on almost the entire surface of each recording layer 2, 5 (22, 25) of the optical recording medium 50, a desired address is accessed based on the address information. It is sufficient to apply the focus servo in this state. On the other hand, when layer information is recorded in the recording management area of the optical recording medium 50, the focus servo may be applied in this recording management area.

When information is recorded (or reproduced) on an optical recording medium having a plurality of recording layers, focus servo may be applied to any one of the plurality of recording layers.
Next, the control unit 58 reads out layer information (layer information) recorded in one recording layer to which focus servo is applied, via the preamplifier 56A, the matrix circuit 56B, and the demodulation circuit 56C as the signal processing unit 56. (Step S30). The function of the control unit 58 is referred to as a layer information reading unit.

Then, the control unit 58 determines whether or not the recording layer specified by the layer information read in step S30 is the recording layer specified as the recording layer to be recorded or reproduced in step S10 (step S40). ). The function of the control unit 58 is called a recording layer determination unit.
As a result of this determination, if it is determined that the recording layer specified by the read layer information is the recording layer specified as the recording layer to be recorded (specific recording layer to be recorded), the control unit 58 A recording command is issued to the optical pickup 53 via the processing unit 57 and the recording laser driver 54Ab, and the laser diode is driven in response thereto, and is specified by the address information of one recording layer to which focus servo is applied. Tracking is performed via the tracking servo circuit 55B and the tracking driver 54C under a recording condition (recording / reproducing condition) such as a recording pulse strategy and recording power corresponding to the recording layer (the recording layer specified by the layer information). For example, information sent from a personal computer or other device (data The recording is performed (step S50). The function of the controller 58 is called a recording controller (recording / reproducing controller).

  Note that the recording / reproduction conditions may be determined based on the data recorded in advance on the optical recording medium, and may be determined based on this, or may be determined based on the information stored in advance in the recording / reproducing apparatus according to the layer information. May be. For example, the recommended recording power or the recommended reproduction power may be recorded on the optical recording medium, and the drive may read these and determine the recording power or the reproduction power based on these.

Further, the recommended recording power or the recommended reproduction power is stored in the drive in accordance with the layer information, and the recommended recording power or the recommended reproduction power corresponding to the layer information is read based on this, and the read recommended recording power or The recording power or the reproduction power may be determined based on the recommended reproduction power.
Further, in some cases, after the recommended recording power is read out, the recording power may be determined by performing OPC (Optimum Power Control).

  On the other hand, as a result of the determination described above, when it is determined that the recording layer specified by the read layer information is the recording layer specified as the recording layer to be reproduced (specific recording layer to be reproduced), the control unit 58 Issues a reproduction command to the optical pickup 53 via the reproduction laser driver 54Aa, under reproduction conditions (recording / reproduction conditions) such as reproduction power corresponding to the recording layer (recording layer specified by the layer information). The information recorded at the address specified by the address information of one recording layer to which the focus servo is applied is reproduced through the signal processing unit 56 while tracking is performed through the tracking servo circuit 55B and the tracking driver 54C. (Step S50). The function of this control unit is called a reproduction control unit (recording / reproduction control unit).

  Meanwhile, if the control unit 58 determines in step S40 that the recording layer specified by the read layer information is not a recording layer to be recorded (or reproduced), the control unit 58 returns to step S20 and performs other recording. The same processing (steps S20 to S40) is performed until focus servo is applied to the layer and thereafter it is determined that the recording layer specified by the read layer information is a recording layer to be recorded (or reproduced). ) Is repeated.

Therefore, according to the optical recording medium, the optical recording medium recording / reproducing method, and the optical recording medium recording / reproducing apparatus according to the present embodiment, the recording pulse strategy, for example, according to the recording layer on which information is to be recorded or reproduced. There is an advantage that recording / reproducing conditions such as recording power and reproducing power can be instantaneously switched.
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

1,21 First substrate (first substrate)
2,22 First recording layer (first recording layer)
3,23 1st reflective layer 4 Intermediate resin layer (intermediate layer)
5, 25 Second recording layer (second recording layer)
6, 26 Second reflective layer 7 Adhesive layer 8, 27 Second substrate (second substrate)
28 Buffer Layer 11, 12, 31 Recording Track Consisting of Protrusions 24 Transparent Adhesive Layer (Intermediate Layer)
32 Recording Track Consisting of Recess 50 Optical Recording Medium 51 Spindle Motor 52 Motor Driver 53 Optical Pickup 54 Optical Pickup Driver 54A Laser Driver 54Aa Playback Laser Driver 54Ab Recording Laser Driver 54B Focus Driver 55 Servo Processor 55A Focus Servo Circuit 56 Signal Processing Part (reproduction processing part)
56A Preamplifier 56B Matrix circuit 56C Demodulator circuit 57 Data processing unit (recording processing unit)
57A Modulation circuit 57B Recording strategy circuit 58 Control unit (microcomputer)
58A CPU
58B Memory 60 Recording / playback device (drive)

Claims (5)

From the recording layer of one optical recording medium in which the layer information is recorded on each of the plurality of recording layers capable of recording or reproducing information by irradiation of laser light from one side, the control unit has the entire address information of 2 A layer information reading step of reading layer information by detecting whether it is represented by a complement;
A recording / reproduction control step for controlling the recording unit to perform recording or reproduction under a recording / reproduction condition corresponding to a recording layer specified by the layer information. Method. The entire address information is represented by two's complement from one recording layer in which the layer information is recorded on each of the plurality of recording layers capable of recording or reproducing information by irradiation of laser light from one side. A layer information reading unit that reads layer information by detecting whether or not
A recording / reproducing apparatus for an optical recording medium, comprising: a recording / reproducing control unit that performs control so that recording or reproduction is performed under a recording / reproducing condition corresponding to the recording layer specified by the layer information. An optical recording medium recorded or reproduced by the optical recording medium recording / reproducing method according to claim 1,
Provided with a plurality of recording layers capable of recording or reproducing information by laser light irradiation from one side,
Layer information is recorded in each of the recording layers, and the layer information is determined by a method of determining whether or not the entire address information is represented by two's complement in two adjacent recording layers of the plurality of recording layers. Is recorded on the optical recording medium.   The optical recording medium according to claim 3, wherein the plurality of recording layers include two recording layers.   5. The optical recording medium according to claim 3, wherein each recording layer is a dye-containing recording layer.

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