JPH11167744A - Optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information recording medium which exhibits a high reflectivity even at a short wavelength and makes it possible to obtain a high recording and reproducing contrast and recording and reproducing method therefor. SOLUTION: This optical information recording medium allows recording and reproducing of information by irradiation with a laser beam and has the layer constitution consisting of a substrate/recording layer/(low-refractive index layer/high-refractive index layer) m (where m is the number of lamination). The recording and reproducing are executed with this recording medium from its substrate side. The recording medium described above is characterized in that (1) m is >=1 and (2) all of the film thickness of the recording layer, the low-refractive index layer and the high-refractive index layer are n1 d1 =λ0 /4 (where n1 is the refractive index of the respective layer materials; d1 is the film thickness of the respective layer materials and λ0 is a recording and reproducing wavelength) at least at the reproduction wavelength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an optical information recording medium,
And its recording method.

[0002]

2. Description of the Related Art In recent years, CD-Rs have appeared on the market, and their usefulness is being recognized. CD-R is CD or CD-R
Compatible with OM, general CD player and CD-R
A disc that can be played back by the OM drive and can be recorded only once. CD-R achieves the same high reflectivity as CD and CD-ROM by applying a gold reflective film to enable reproduction by CD player and CD-ROM drive. A recording layer is applied, and then a gold reflective film is provided, on which a protective layer made of an ultraviolet curable resin is formed.

Further, a cyanine-based dye, a phthalocyanine-based dye, an azo metal complex or the like whose wavelength matching property is optimized to enable recording by a recording laser beam is used as a recording layer. The recording contrast is obtained by a change in the constant or deformation of the substrate. Currently C
With the shift from D-ROMs to DVD-ROMs, research on write-once optical information recording media has been advanced from CD-Rs to DVD-Rs. The recording / reproducing wavelength changes from around 780 (nm) to 635 to 650 (nm) due to the shift from the CD-based media to the DVD-based media, and the recording layer material is changed to cope with this. The CD-R and the DVD-R have the same physical layer configuration.

Patents corresponding to a blue laser include, for example, JP-A-7-304256 (optical recording medium comprising a porphyrin derivative and a polymer having a molecular structure having a coordinating ability in a side chain), and JP-A-7-304257 (porphyrin derivative). And an optical recording medium comprising a molecular compound having a coordination ability and a polymer.

[0005]

The reflectivity of a reflection type optical information recording medium can be set arbitrarily. However, in order to obtain a high contrast, it is preferable that the reflectivity before recording is high. . In the case of a read-only ROM-type optical information recording medium (CD or CD-ROM, etc.), a high reflectance of the optical information recording medium is required in order to reduce drive costs as much as possible. In order to take advantage of the characteristics of the organic material, it is best to increase the reflectance. Further, in the case of a write-once optical information recording medium or a rewritable optical information recording medium, compatibility with a ROM-type optical information recording medium is always important. High reflectivity is important.

However, conventional ROM-type optical information recording media,
And, the optical information recording medium compatible with the ROM type optical information recording medium has a recording layer and a reflective layer on a substrate as a main component, and since a metal is used as a material of the reflective layer,
For example, in the case of gold used in a CD-R or the like, the wavelength dispersibility becomes remarkable from about 600 nm or less, and a significant decrease in reflectance occurs (FIG. 1). For example, gold has a reflectance of about 80% at 550 nm. Therefore, when a gold reflective layer is used, in the configuration of substrate / recording layer / gold reflective layer,
At a wavelength of 550 nm or less, a reflectance of about 50% becomes difficult, and it cannot be said that the reflectance is high. By using aluminum or silver instead of gold, the reflectance can be improved even at a shorter wavelength than gold, but the tendency is the same, and lower reflectance at a shorter wavelength is unavoidable.

In the case where a metal is used, the corrosiveness of the metal and the stability of a chemical / physical reaction with the recording material are often problems. Therefore, even if a low reflectance and a low recording / reproduction contrast are allowed by the reproduction system circuit or the signal processing technology, no matter where the recording / reproduction wavelength is set, high reflection / high recording / reproduction is possible. Contrast is always required from the reproduction side. Further, since the increase in the density of the optical information recording medium is mainly achieved by shortening the wavelength of the laser light source, it is easily imagined that the demand for a high reflectance type optical information recording medium in a short wavelength region will increase.
Therefore, an object of the present invention is to provide an optical information recording medium which exhibits a high reflectance even at a short wavelength and can obtain a high recording / reproducing contrast, and a recording / reproducing method thereof.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on an optical information recording medium which can obtain a high reflectance at an arbitrary wavelength as well as a short wavelength and can perform recording, as an optical information recording medium. An optical information recording medium having a structure in which a recording layer is included in a high-reflection multilayer film, which will be described in detail in Examples later, is extremely excellent in terms of high reflectance and recording contrast, and is easy to realize. And found that the present invention can be achieved.

The major feature of the optical information recording medium of the present invention is that
(1) Do not use a metal reflective layer which has been conventionally required for high reflectivity. (2) As an application of a high reflectivity method using a dielectric laminate coating, a recording layer is partially replaced with a dielectric layer. Was used. According to the present invention, by adopting the above-described configuration, (1) high reflectance type optical information can be obtained even at an arbitrary wavelength where high reflectance cannot be obtained when a conventional metal reflective layer is used. A recording medium is provided, and (2) information of very high contrast can be recorded / reproduced by changing the optical constant of the recording layer by recording.

In the present invention, a dye is used as the most suitable recording layer. In this case, by using anomalous dispersion based on the absorption of the dye, the recording layer can be used as a high refractive index layer or a low refractive index layer. It can also be used as a layer. That is, the wavelength dependence of the complex refractive index of the dye is as shown in FIG. 2, and the real part of the complex refractive index changes largely near the absorption region, and has a high real part of the complex refractive index on the longer wavelength side than the absorption wavelength. Conversely, on the shorter wavelength side than the absorption fatigue length, it has a real part with a low complex refractive index. Moreover, since the absorption coefficient (imaginary part of the complex refractive index) is small in the wavelength region showing the real part of the high complex refractive index and the real part of the low complex refractive index, a laminate of the high-reflectance layer and the low-reflectance layer is small. In this case, the reflectance can be sufficiently increased. As can be seen from FIG. 2, the wavelength region where the real part of the complex refractive index is high and the wavelength region where the real part is low are very close to each other with the absorption band peak at the center. Therefore, if the absorption spectrum of the recording layer changes due to recording, the complex refractive index greatly changes accordingly, so that a large recording / reproducing contrast can be obtained.

Further, as is conventionally known, the effect of a multilayer film is to improve the characteristics of a single-layer film or to provide characteristics that a single-layer film does not have by using a multilayer film. It is. For example, a two-layer or three-layer antireflection film can reduce the reflectance over the entire visible region as compared with a single-layer film, or a multilayer reflection enhancement film can provide a reflectance exceeding 99% in a specific wavelength region. The effect of this multilayer can be easily analyzed by a characteristic matrix derived from the boundary conditions of the electromagnetic field. The analysis using the characteristic matrix is described in detail, for example, in "Applied Optics II, Masao Tsuruta, Baifukan," p142. For example, in a multilayer film having the configuration of air layer / (high refractive index layer / low refractive index layer) m / substrate, the material of the high refractive index layer is TiO ₂ (refractive index n _{1 at} 550 nm = n ₁ =
2.40), the material of the low refractive index layer was MgF ₂ (refractive index n _{2 at} 550 nm = 1.38), and the substrate was BSC7 (55
The refractive index at 0 nm n _s = 1.52) and the refractive index of air to n ₀
If = 1.0, the characteristic matrix is applied as follows. Here, N = 0, 1, 2, 3,....

(Equation 1) Therefore, the energy reflectance R _{m + 1} is

(Equation 2) Becomes This is actually calculated as shown in FIG.
As can be seen from these results, high reflectivity can be obtained by appropriately selecting the film thickness at an arbitrary wavelength by using a multilayer film.

Hereinafter, the recording layer material that can be used in the optical information recording medium of the present invention will be described in detail. For the recording layer, a very wide range of materials can be used, and phthalocyanine and tetraazaporphyrin, azo metal complexes, dyes exhibiting photochromic properties, compounds exhibiting thermochromic properties, etc. conventionally used as optical discs in the present invention. Dyes, dyes exhibiting photochromic properties, and compounds exhibiting thermochromic properties are among the most excellent materials, which are suitable as recording layers. In the case of a dye exhibiting photochromic properties, for example, light causes a ring-opening and ring-closing reaction to cause a change between a colorless body and a colored body, so that a very large spectral change, that is, a very large change in an optical constant occurs. A large recording contrast can be obtained together with an increase in the reflectance when recording is not performed. Examples of the dye exhibiting photochromic properties include fulgides, diarylethenes, azobenzenes, spirobilanes, and stilbenes.

In the case of a compound exhibiting thermochromic properties, for example, a change in the state of molecular assembly or a change in structure due to heat causes a very large change in the spectrum, that is, a very large change in the optical constant. Along with increasing the reflectance, a large recording contrast can be obtained. Examples of the compound exhibiting thermochromic properties include, for example, compounds exhibiting thermochromic properties due to changes in the molecular skeleton, such as bianthrone, polythiophene derivatives, spiropyran and merocyanine, spirooxazine having a 7-ring, quinone and b-hydroxy secondary amine. And azamethine dyes, diazaanthracenophane and the like. Further, as those exhibiting thermochromic properties due to tautomerization, those due to keto-enol tautomerization of azomethines such as N-salicylidenebenzylamine, those exhibiting thermochromic properties due to acid-base reaction, or complexes Cholesteric liquid crystals, polyacetylene, and the like can be given as examples of those exhibiting thermochromic properties due to formation and those exhibiting thermochromic effects due to structural changes in the state of molecular assembly. Also, cyanine (polymethine)
Dyes, tetraazaporphyrin dyes such as phthalocyanine and naphthalosinine, dyes such as porphyrin dyes,
Since it has a large absorption in the range of 300 to 900 nm, it is one of the most suitable materials for the present invention in terms of stability, productivity, and wavelength matching.

The real part n and the imaginary part k of the complex refractive index are connected in a Kramers-Kronig relation (for example, “3rd.
Light pencil “p243 New Technology Communications”.

(Equation 3)

That is, as is apparent from the above equation, n is large on the long wavelength side of the absorption peak wavelength, and conversely, n is small on the short wavelength side of the absorption peak wavelength. Also, from the Kramers-Kronig relationship, the sharper the absorption curve and the stronger the absorption, the larger the n on the long wavelength side near the absorption peak, the smaller the n on the short wavelength side, and the lower the dye as a high refractive index layer. It can also be used as a refractive index layer. On the other hand, when the absorption curve is relatively broad, the change in n near the absorption peak is relatively small, so that the dye does not have characteristics of both the high refractive index layer and the low refractive index layer. May not be desirable. However, if a high refractive index layer or a low refractive index layer has any effect, it is sufficient to use a dye having a relatively broad absorption curve, and the refractive index difference between adjacent layers should be large. In the present invention, the recording layer is not limited to a dye compound, a dye compound exhibiting photochromic properties, or a compound exhibiting thermochromic properties, as long as the optical constant changes at the recording / reproducing wavelength. Therefore, in the present invention, not only a change in the complex refractive index but also a material whose film thickness changes by recording may be used. As such a material whose film thickness changes, a material mainly composed of a general thermoplastic resin or a thermosetting resin, or a shape memory resin such as polynorbornene, polyisoprene, styrene, butadiene copolymer, or polyurethane is used. can give.

In the present invention, the dye layer is preferably formed by vapor deposition. This is because the low-refractive-index layer and the high-refractive-index layer are formed by a dry process such as vapor deposition or sputtering. Is easy to control. That is, in the multilayer film structure utilizing the interference effect in the present invention, the thickness of each layer is very important, but in the conventionally used spin coating method, the type and solvent of the solvent that dissolves the recording layer material such as a dye are conventionally used. Film thickness, the film thickness varies greatly between the inner and outer circumferences of the disc structure, and the film thickness varies greatly depending on the combination of the solvent, the difference between the lots of the solvent, the number of rotations and the rotation pattern, the temperature and humidity of the working environment, etc. Therefore, it is not easy to control the film thickness. On the other hand, when a dye is formed by vapor deposition, the film thickness control becomes very simple. Dyes that can be formed by vapor deposition
For example, "Reversible lasermarki
ng process in anthraquino
ne dyfilms, A .; H. Sporer, AP
PLIED OPTICS / Vo1.26, No. 7 /
1 April 1987, p. 1240 ”and the like.
However, in the present invention, the recording layer material such as the coloring matter cannot be vapor-deposited in all structures, so that a spin coating method can be used depending on the situation.

The high refractive index layer material usable in the present invention includes ZrO ₂ (2.1), TiO ₂ (2.40), ZnS
(2.32), PbCl ₂ (2.20) and the like can be used. As the material of the low refractive index layer, MgF ₂ (1.3
_{8), CeF 3 (1.63)} , A1 2 O 3 (1.62),
SiO ₂ (1.46), Na ₃ AlF ₆ (1.35) and the like can be used.

<< Recording Layer >> As the dye, in addition to the above examples,
For example, polymethine dyes, naphthalocyanine, phthalocyanine, squarylium, coroconium, pyrylium, naphthoquinone, anthraquinone (indanthrene), xanthene, triphenylmethane, azulene, tetrahydrocholine, phenanthrene, triamine Examples include phenothiazine dyes and metal complex compounds, and the above dyes may be used alone or in combination of two or more. In addition, metals and metal compounds such as In, Te, Bi, Al, Be, and Te are contained in the dye.
O ₂ , SnO, As, Cd and the like can be used in the form of dispersion mixing or lamination. Further, various materials such as a polymer material, for example, an ionomer resin, a polyamide resin, a vinyl resin, a natural polymer, silicone, and a liquid rubber, or a silane coupling agent may be dispersed and used in the dye. It can be used together with a stabilizer (for example, a transition metal complex), a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, a plasticizer, and the like for the purpose of improving the properties.

When the coating method is used, the dye or the like is dissolved in an organic solvent, and the coating is performed by a conventional coating method such as spraying, roller coating, dipping and spin coating, or by a vapor deposition method. The vapor deposition method is most preferable due to its characteristics. Examples of the organic solvent generally include alcohols such as methanol, ethanol, and isopropanol; ketones such as acetone, methyl ethyl ketone and cyclohexanone; amides such as N, N-dimethylacetamide and N, N-dimethylformamide; and sulfoxides such as dimethyl sulfoxide. , Tetrahydrofuran, dioxane, diethyl ether, ethers such as ethylene glycol monomethyl ether, esters such as methyl acetate, ethyl acetate, chloroform, methylene chloride, dichloroethane, carbon tetrachloride, aliphatic halogenated carbons such as trichloroethane,
Or benzene, xylene, monochlorobenzene,
Aromatic substances such as dichlorobenzene, cellsolves such as methoxyethanol and ethoxyethanol, and hydrocarbons such as hexane, pentane, cyclohexane, and methylcyclohexane can be used. The film thickness of the recording layer is ₀ recording and reproducing wavelength lambda, when the real part of the complex refractive index of the recording-reproducing wavelength is n, there must be a film thickness near to satisfy nearly nd = λ _0/4 . (Since the absorption coefficient is not 0, the optimum film thickness from nd = λ _0/4 may deviate slightly).

<< Substrate >> The required characteristics of the substrate are that it must be transparent to the laser beam used only when recording / reproducing from the substrate side, and transparent when recording / reproducing from the recording layer side. No need. As the substrate material, for example,
Plastics such as polyester, acrylic resin, polyamide, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, and polyimide, glass, ceramic, and metal can be used.
Note that a guide groove or guide pit for tracking and a preformat such as an address signal may be formed on the surface of the substrate.

<< Intermediate Layer >> Layers provided other than the substrate, the recording layer, and the protective layer, including the undercoat layer and the like, will be referred to herein as intermediate layers. This intermediate layer has (a) improved adhesion and (b)
Water or gas barrier, (c) improvement of storage stability of recording layer, (d) improvement of reflectance, (e) protection of substrate and recording layer from solvent, (f) guide groove, guide pit, It is used for the purpose of forming a preformat or the like. For the purpose of the above (a), various polymer materials such as polymer materials, for example, ionomer resin, polyamide resin, vinyl resin, natural resin, natural polymer, silicone, liquid rubber, and silane coupling For the purposes of (b) and (c), an inorganic compound other than the above-mentioned polymer material, for example, SiO ₂ , MgF ₂ , Si
O, TiO ₂ , ZnO, TiN, SiN and the like can be used. For the purpose (d), an organic thin film having a metallic luster such as a methine dye or a xanthene dye can be used. For the purposes (e) and (f), an ultraviolet curable resin or a thermosetting resin can be used. A resin, a thermoplastic resin, or the like can be used. The thickness of the undercoat layer, enter the recording-reproducing wavelength _0, when the real part of the complex refractive index of the recording-reproducing wavelength is n, it is necessary that a film thickness satisfying the nd = ON _0/4.

<< Protective Layer / Substrate Hard Coat Layer >> The protective layer or the substrate surface hard coat layer (a) protects the recording layer (reflection / absorption layer) from scratches, dust, dirt, etc.
(B) improvement in storage stability of the recording layer (reflection / absorption layer),
(C) Used for the purpose of improving the reflectance. For these purposes, the materials shown in the undercoat layer can be used. As inorganic materials, SiO, SiO ₂
And the like, and, as an organic material, polymethyl acrylate, polycarbonate, epoxy grease, polystyrene, polyester resin, vinyl resin, cellulose, aliphatic hydrocarbon resin, aromatic hydrocarbon resin,
Thermosoftening and heat melting resins such as natural rubber, styrene butadiene resin, chloroprene rubber, wax, alkyd resin, drying oil and rosin can also be used. Among the above materials, the most preferable substance for the protective layer or the hard coat layer on the substrate surface is an ultraviolet curable resin having excellent productivity.

The thickness of the protective layer or the hard coat layer on the substrate surface is 0.01 to 30 when it is on the side opposite to the incident surface.
[mu] m, preferably is suitably 0.05 to 10 [mu] m, when in the incident plane side, entering the recording-reproducing wavelength _0, recording. Assuming that the real part of the complex refractive index at the reproduction wavelength is n, nd = ₀
It is necessary that the film thickness satisfies / 4. In the present invention, the undercoat layer, the protective layer, and the substrate surface hard coat layer each include a stabilizer, a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, and a plasticizer, as in the case of the recording layer. Etc. can be contained.

<< Adhesive Layer >> An adhesive layer may be required when two or more optical information recording media are adhered. Particularly preferred in the present invention are hot melt type (hot melt type) adhesives,
Alternatively, it is an ultraviolet curable adhesive. The ultraviolet curable adhesive is an adhesive which is cured by the initiation of radical polymerization by irradiation with ultraviolet light. The composition is generally composed of (1) an acrylic oligomer, (2) an acrylic monomer, (3) a photopolymerization initiator, and (4) a polymerization inhibitor. The oligomer is a polyester-based, polyurethane-based, or epoxy-based. Acrylic esters and the like, and photopolymerization initiators such as benzophenone and benzoin ether can be used. The hot melt adhesive is one in which a liquid adhesive is hardened by solvent volatilization or reaction and develops an adhesive force, whereas an ordinary-temperature solid thermoplastic resin develops an adhesive force by a physical change of heat melting and cooling and solidification. Hot melt adhesives are EVA, polyester,
A polyamide type, a polyurethane type, or the like can be used.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the optical information recording medium of the present invention and the effects thereof will be described below.

Example 1 (1) Layer structure Substrate / recording layer / (low refractive index layer / high refractive index layer) m / air layer (2) Refractive index of substrate, air layer and each layer Substrate refractive index: 1.52 Refractive index of air layer: 1.0 Refractive index of low refractive index layer 1:38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer and high refractive index layer (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of laminations m: 1 Recording / recording from the substrate side on the optical information recording medium having the above configuration
Reproduction is performed at a recording / reproduction wavelength of ₀ : 550 (nm).

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in the unrecorded state and in the recording state is shown in FIG. Fig. 4 Dependency
(The complex refractive index is assumed to be an arbitrary k, and n is obtained from the relationship of Kramers-Kronig.) The film thickness of the recording layer is d = λ ₀ / [4 × n ( λ ₀ )]. FIG. 5 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From this result, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm (550 nm or less) and having a high recording contrast.

Example 2 (1) Layer structure Substrate / recording layer / (low refractive index layer / high refractive index layer) m / air layer (2) Refractive index of substrate, air layer and each layer Substrate refractive index: 1.52 Refractive index of air layer: 1.0 Refractive index of low refractive index layer 1:38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer and high refractive index layer (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of stacked layers m: 2
Reproduction is performed at a recording / reproduction wavelength of ₀ : 550 (nm).

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in the unrecorded state and in the recording state is shown in FIG. Fig. 4 Dependency
(The complex refractive index is assumed to be an arbitrary k, and n is obtained from the relationship of Kramers-Kronig.) The film thickness of the recording layer is d = λ ₀ / [4 × n ( λ ₀ )]. FIG. 6 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From this result, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm (550 nm or less) and having a high recording contrast.

Example 3 (1) Layer Structure Substrate / (High refractive index layer / Low refractive index layer) p / Recording layer / (Low refractive index layer / High refractive index layer) r / Air layer (2) Substrate, air Refractive index of layers and each layer Substrate refractive index: 1.52 Air layer refractive index: 1.0 Low refractive index layer refractive index 1:38 (MgF ₂ ) High refractive index layer refractive index: 2.40 (TiO ₂ ) (However, the wavelength dependence of the low refractive index layer and the high refractive index layer is not considered.) (3) Thickness of the substrate and each layer Thickness of the substrate: Thickness of the low refractive index layer: d = λ ₀ / (4 × 1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of stacked layers p: 1 Number of stacked layers r: 1 A substrate is provided on the optical information recording medium having the above-described configuration. Record from the side
Reproduction is performed at a recording / reproduction wavelength of ₀ : 550 (nm).

FIG. 7 shows the wavelength dependence of the imaginary part of the complex refractive index of the recording layer between the unrecorded state and the recorded state under the above-mentioned layer structure conditions. Figure 8 shows dependencies
(The complex refractive index is assumed to be an arbitrary k, and n is obtained from the relationship of Kramers-Kronig.) The film thickness of the recording layer is d = λ ₀ / [4 × n ( λ ₀ )]. FIG. 9 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From this result, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 520 nm and a high recording contrast.

Example 4 (1) Layer Structure Substrate / Recording Layer / (Low Refractive Index Layer / High Refractive Index Layer) m / Air Layer (2) Refractive Index of Substrate, Air Layer and Each Layer Substrate refractive index: 1.52 Refractive index of air layer: 1.0 Refractive index of low refractive index layer 1:38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer and high refractive index layer (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of laminations m: 1 Recording / recording from the substrate side on the optical information recording medium having the above configuration
Reproduction is performed at a recording / reproduction wavelength of ₀ : 550 (nm).

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the recording layer between the unrecorded state and the recorded state is shown in FIG. The dependency was tentatively determined as shown in FIG. 11 (this complex refractive index is obtained by assuming an arbitrary k and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 12 shows the result of calculating the reflectivity at the time of recording and at the time of non-recording under the above conditions. From these results, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm and a high recording contrast.

Example 5 (1) Layer Structure Substrate / Recording Layer / (Low Refractive Index Layer / High Refractive Index Layer) m / Air Layer (2) Refractive Index of Substrate, Air Layer and Each Layer Substrate refractive index: 1.52 Refractive index of air layer: 1.0 Refractive index of low refractive index layer 1:38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer and high refractive index layer (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of stacked layers m: 2
Reproduction is performed at a recording / reproduction wavelength of ₀ : 550 (nm).

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the recording layer between the unrecorded state and the recorded state is shown in FIG. The dependency was tentatively determined as shown in FIG. 11 (this complex refractive index is obtained by assuming an arbitrary k and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 13 shows the results of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From these results, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm and a high recording contrast.

Example 6 (1) Layer structure Substrate / (high refractive index layer / low refractive index layer) p / recording layer / (low refractive index layer / high refractive index layer) r / air layer (2) substrate, air Refractive index of layers and each layer Substrate refractive index: 1.52 Air layer refractive index: 1.0 Low refractive index layer refractive index 1:38 (MgF ₂ ) High refractive index layer refractive index: 2.40 (TiO ₂ ) (However, the wavelength dependence of the low refractive index layer and the high refractive index layer is not considered.) (3) Thickness of the substrate and each layer Thickness of the substrate: Thickness of the low refractive index layer: d = λ ₀ / (4 × 1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of layers p: 1 Number of layers r: 0 Substrate on optical information recording medium having the above configuration Record from the side
Reproduction is performed at a recording / reproduction wavelength of ₀ : 550 (nm).

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the unrecorded and recorded layers of the recording layer is shown in FIG. The dependence was tentatively determined as shown in FIG. 15 (this complex refractive index is obtained by assuming an arbitrary k and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 16 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From these results, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm and a high recording contrast.

Example 7 (1) Layer structure Substrate / (high refractive index layer / low refractive index layer) p / recording layer / (low refractive index layer / high refractive index layer) r / air layer (2) substrate, air Refractive index of layers and each layer Substrate refractive index: 1.52 Air layer refractive index: 1.0 Low refractive index layer refractive index 1:38 (MgF ₂ ) High refractive index layer refractive index: 2.40 (TiO ₂ ) (However, the wavelength dependence of the low refractive index layer and the high refractive index layer is not considered.) (3) Thickness of the substrate and each layer Thickness of the substrate: Thickness of the low refractive index layer: d = λ ₀ / (4 × 1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of stacked layers p: 1 Number of stacked layers r: 1 A substrate is provided on the optical information recording medium having the above-described configuration. Record from the side
Reproduction is performed at a recording / reproduction wavelength of ₀ : 550 (nm).

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the recording layer between the unrecorded state and the recorded state is shown in FIG. The dependence was tentatively determined as shown in FIG. 15 (this complex refractive index is obtained by assuming an arbitrary k and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 17 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From these results, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm and a high recording contrast.

Example 8 (1) Layer Structure Substrate / Recording Layer / (Low Refractive Index Layer / High Refractive Index Layer) m / Air Layer (2) Refractive Index of Substrate, Air Layer and Each Layer Substrate refractive index: 1.52 Refractive index of air layer: 1.0 Refractive index of low refractive index layer 1:38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer and high refractive index layer (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of laminations m: 1 Recording / recording from the substrate side on the optical information recording medium having the above configuration
Reproduction is performed at a recording / reproduction wavelength of ₀ : 550 (nm).

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in the unrecorded state and in the recorded state is shown in FIG. The dependence was tentatively determined as shown in FIG. 19 (this complex refractive index is obtained by assuming an arbitrary k and n is determined from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 20 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From these results, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm and a high recording contrast.

Example 9 (1) Layer Structure Substrate / Recording Layer / (Low Refractive Index Layer / High Refractive Index Layer) m / Air Layer (2) Refractive Index of Substrate, Air Layer and Each Layer Substrate refractive index: 1.52 Refractive index of air layer: 1.0 Refractive index of low refractive index layer 1:38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer and high refractive index layer (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of stacked layers m: 2
Reproduction is performed at a recording / reproduction wavelength of ₀ : 550 (nm).

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the recording layer during non-recording and during recording is shown in FIG. The dependence was tentatively determined as shown in FIG. 19 (this complex refractive index is obtained by assuming an arbitrary k and n is determined from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 21 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From these results, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm and a high recording contrast.

Example 10 (1) Layer Structure Substrate / (High refractive index layer / Low refractive index layer) p / Recording layer / (Low refractive index layer / High refractive index layer) r / Air layer (2) Substrate, air Refractive index of layers and each layer Substrate refractive index: 1.52 Air layer refractive index: 1.0 Low refractive index layer refractive index 1:38 (MgF ₂ ) High refractive index layer refractive index: 2.40 (TiO ₂ ) (However, the wavelength dependence of the low refractive index layer and the high refractive index layer is not considered.) (3) Thickness of the substrate and each layer Thickness of the substrate: Thickness of the low refractive index layer: d = λ ₀ / (4 × 1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of layers p: 1 Number of layers r: 0 Substrate on optical information recording medium having the above configuration Record from the side
Reproduction is performed at a recording / reproduction wavelength of ₀ : 550 (nm).

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the recording layer between the unrecorded state and the recorded state is shown in FIG. The dependence was tentatively determined as shown in FIG. 23 (this complex refractive index is assumed to be an arbitrary k and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 24 shows the result of calculating the reflectivity at the time of recording and at the time of non-recording under the above conditions. From these results, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm and a high recording contrast.

Example 11 (1) Layer Structure Substrate / (High refractive index layer / Low refractive index layer) p / Recording layer / (Low refractive index layer / High refractive index layer) r / Air layer (2) Substrate, air Refractive index of layers and each layer Substrate refractive index: 1.52 Air layer refractive index: 1.0 Low refractive index layer refractive index 1:38 (MgF ₂ ) High refractive index layer refractive index: 2.40 (TiO ₂ ) (However, the wavelength dependence of the low refractive index layer and the high refractive index layer is not considered.) (3) Thickness of the substrate and each layer Thickness of the substrate: Thickness of the low refractive index layer: d = λ ₀ / (4 × 1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of stacked layers p: 1 Number of stacked layers r: 1 A substrate is provided on the optical information recording medium having the above-described configuration. Record from the side
Reproduction is performed at a recording / reproduction wavelength of ₀ : 550 (nm).

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the recording layer during non-recording and during recording is shown in FIG. The dependence was tentatively determined as shown in FIG. 23 (this complex refractive index is assumed to be an arbitrary k and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 25 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From this result, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 520 nm and a high recording contrast.

Example 12 (1) Layer structure Air layer / recording layer / (low refractive index layer / high refractive index layer) m / substrate (2) Refractive index of substrate, air layer and each layer Substrate refractive index: 1.52 Refractive index of air layer: 1.0 Refractive index of low refractive index layer 1:38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer and high refractive index layer (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of layers m: 1 Recording / reproducing recording / reproducing on optical information recording medium having the above configuration from the air layer side ₀ : 550 (nm) Do with.

FIG. 26 shows the wavelength dependence of the imaginary part of the complex refractive index of the recording layer between the unrecorded state and the recorded state under the above-mentioned layer structure conditions. The dependency was tentatively determined as shown in FIG. 27 (this complex refractive index is assumed to be an arbitrary k, and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 28 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From these results, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm and a high recording contrast.

Example 13 (1) Layer structure Air layer / recording layer / (low refractive index layer / high refractive index layer) m / substrate (2) Refractive index of substrate, air layer and each layer Substrate refractive index: 1.52 Refractive index of air layer: 1.0 Refractive index of low refractive index layer 1:38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer and high refractive index layer (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of laminations m: 2 Recording / reproduction is performed on the optical information recording medium having the above configuration from the air layer side. Recording / reproduction wavelength input ₀ : 550 (nm) Do with.

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the recording layer during non-recording and during recording is shown in FIG. The dependency was tentatively determined as shown in FIG. 27 (this complex refractive index is assumed to be an arbitrary k, and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 29 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From these results, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm and a high recording contrast.

Example 14 (1) Layer structure Air layer / (High refractive index layer / Low refractive index layer) p / Recording layer / (Low refractive index layer / High refractive index layer) r / Substrate (2) Substrate, air Refractive index of layers and each layer Substrate refractive index: 1.52 Air layer refractive index: 1.0 Low refractive index layer refractive index 1:38 (MgF ₂ ) High refractive index layer refractive index: 2.40 (TiO ₂ ) (However, the wavelength dependence of the low refractive index layer and the high refractive index layer is not considered.) (3) Thickness of the substrate and each layer Thickness of the substrate: Thickness of the low refractive index layer: d = λ ₀ / (4 × 1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of layers p: 1 Number of layers r: 1 Air is applied to the optical information recording medium having the above configuration. Recording and reproduction are performed from the layer side at a recording and reproduction wavelength of ₀ : 550 (nm).

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the unrecorded and recorded layers of the recording layer is shown in FIG. The dependence was tentatively determined as shown in FIG. 31 (this complex refractive index is assumed to be an arbitrary k and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 32 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From this result, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 520 nm and a high recording contrast.

Example 15 (1) Layer structure Air layer / recording layer / (low refractive index layer / high refractive index layer) m / substrate (2) Refractive index of substrate, air layer and each layer Substrate refractive index: 1.52 Refractive index of air layer: 1.0 Refractive index of low refractive index layer 1:38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer and high refractive index layer (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of layers m: 1 Recording / reproducing recording / reproducing on optical information recording medium having the above configuration from the air layer side ₀ : 550 (nm) Do with.

FIG. 33 shows the wavelength dependence of the imaginary part of the complex refractive index of the recording layer between the unrecorded state and the recorded state under the above-mentioned layer configuration conditions. The dependence was tentatively determined as shown in FIG. 34 (this complex refractive index is assumed to be an arbitrary k, and n is obtained from the Kramers-Kronig relation.) The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 35 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From these results, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm and a high recording contrast.

Example 16 (1) Layer structure Air layer / recording layer / (low refractive index layer / high refractive index layer) m / substrate (2) Refractive index of substrate, air layer and each layer Substrate refractive index: 1.52 Refractive index of air layer: 1.0 Refractive index of low refractive index layer 1:38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer and high refractive index layer (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of laminations m: 2 Recording / reproduction is performed on the optical information recording medium having the above configuration from the air layer side. Recording / reproduction wavelength input ₀ : 550 (nm) Do with.

FIG. 33 shows the wavelength dependence of the imaginary part of the complex refractive index of the recording layer between the unrecorded state and the recorded state under the above-mentioned layer structure conditions. The dependence was tentatively determined as shown in FIG. 34 (this complex refractive index is assumed to be an arbitrary k, and n is obtained from the Kramers-Kronig relation.) The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 36 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From these results, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm and a high recording contrast.

Example 17 (1) Layer structure Air layer / (High refractive index layer / Low refractive index layer) p / Recording layer / (Low refractive index layer / High refractive index layer) r / Substrate (2) Substrate, air Refractive index of layers and each layer Substrate refractive index: 1.52 Air layer refractive index: 1.0 Low refractive index layer refractive index 1:38 (MgF ₂ ) High refractive index layer refractive index: 2.40 (TiO ₂ ) (However, the wavelength dependence of the low refractive index layer and the high refractive index layer is not considered.) (3) Thickness of the substrate and each layer Thickness of the substrate: Thickness of the low refractive index layer: d = λ ₀ / (4 × 1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of layers p: 1 Number of layers r: 0 Air is applied to the optical information recording medium having the above configuration. Recording and reproduction are performed from the layer side at a recording and reproduction wavelength of ₀ : 550 (nm).

FIG. 37 shows the wavelength dependence of the imaginary part of the complex refractive index of the recording layer between the unrecorded state and the recorded state under the above-mentioned layer structure conditions. The dependence was tentatively determined as shown in FIG. 38 (this complex refractive index is obtained by assuming an arbitrary k and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 39 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From these results, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 530 nm and a high recording contrast.

Example 18 (1) Layer structure Air layer / (High refractive index layer / Low refractive index layer) p / Recording layer / (Low refractive index layer / High refractive index layer) r / Substrate (2) Substrate, air Refractive index of layers and each layer Substrate refractive index: 1.52 Air layer refractive index: 1.0 Low refractive index layer refractive index 1:38 (MgF ₂ ) High refractive index layer refractive index: 2.40 (TiO ₂ ) (However, the wavelength dependence of the low refractive index layer and the high refractive index layer is not considered.) (3) Thickness of the substrate and each layer Thickness of the substrate: Thickness of the low refractive index layer: d = λ ₀ / (4 × 1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of layers p: 1 Number of layers r: 1 Air is applied to the optical information recording medium having the above configuration. Recording and reproduction are performed from the layer side at a recording and reproduction wavelength of ₀ : 550 (nm).

FIG. 37 shows the wavelength dependence of the imaginary part of the complex refractive index of the recording layer between the unrecorded state and the recorded state under the above-mentioned layer structure conditions. The dependence was tentatively determined as shown in FIG. 38 (this complex refractive index is obtained by assuming an arbitrary k and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 40 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From this result, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 540 nm and a high recording contrast.

Example 19 (1) Layer Structure Air Layer / Recording Layer / (Low Refractive Index Layer / High Refractive Index Layer) m / Substrate (2) Refractive Index of Substrate, Air Layer and Each Layer Substrate refractive index: 1.52 Refractive index of air layer: 1.0 Refractive index of low refractive index layer 1:38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer and high refractive index layer (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of layers m: 1 Recording / reproducing recording / reproducing on optical information recording medium having the above configuration from the air layer side ₀ : 550 (nm) Do with.

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the recording layer during non-recording and during recording is shown in FIG. The dependency was tentatively determined as shown in FIG. 42 (this complex refractive index is assumed to be an arbitrary k, and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 43 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From these results, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm and a high recording contrast.

Example 20 (1) Layer structure Air layer / recording layer / (low refractive index layer / high refractive index layer) m / substrate (2) Refractive index of substrate, air layer and each layer Substrate refractive index: 1.52 Refractive index of air layer: 1.0 Refractive index of low refractive index layer 1:38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer and high refractive index layer (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of laminations m: 2 Recording / reproduction is performed on the optical information recording medium having the above configuration from the air layer side. Recording / reproduction wavelength input ₀ : 550 (nm) Do with.

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the recording layer at the time of non-recording and at the time of recording is shown in FIG. The dependency was tentatively determined as shown in FIG. 42 (this complex refractive index is assumed to be an arbitrary k, and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 44 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From these results, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 550 nm and a high recording contrast.

Example 21 (1) Layer structure Air layer / (High refractive index layer / Low refractive index layer) p / Recording layer / (Low refractive index layer / High refractive index layer) r / Substrate (2) Substrate, air Refractive index of layers and each layer Substrate refractive index: 1.52 Air layer refractive index: 1.0 Low refractive index layer refractive index 1:38 (MgF ₂ ) High refractive index layer refractive index: 2.40 (TiO ₂ ) (However, the wavelength dependence of the low refractive index layer and the high refractive index layer is not considered.) (3) Thickness of the substrate and each layer Thickness of the substrate: Thickness of the low refractive index layer: d = λ ₀ / (4 × 1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of layers p: 1, number of layers r: 0 Recording / reproduction is performed from the air layer side at a recording / reproduction wavelength of ₀ : 550 (nm).

FIG. 45 shows the wavelength dependence of the imaginary part of the complex refractive index of the recording layer between the unrecorded state and the recorded state under the above-mentioned layer structure conditions. The dependence was tentatively determined as shown in FIG. 46 (this complex refractive index is assumed to be an arbitrary k, and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 47 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From this result, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 530 nm (530 nm) and a high recording contrast.

Example 22 (1) Layer structure Air layer / (High refractive index layer / Low refractive index layer) p / Recording layer / (Low refractive index layer / High refractive index layer) r / Substrate (2) Substrate, air Refractive index of layers and each layer Substrate refractive index: 1.52 Air layer refractive index: 1.0 Low refractive index layer refractive index 1:38 (MgF ₂ ) High refractive index layer refractive index: 2.40 (TiO ₂ ) (However, the wavelength dependence of the low refractive index layer and the high refractive index layer is not considered.) (3) Thickness of the substrate and each layer Thickness of the substrate: Thickness of the low refractive index layer: d = λ ₀ / (4 × 1.38) Thickness of high refractive index layer: d = λ ₀ /(4×2.40) (4) Number of stacked layers p: 1, number of stacked layers r: 1 For the optical information recording medium having the above configuration. Recording / reproduction is performed from the air layer side at a recording / reproduction wavelength of ₀ : 550 (nm).

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the unrecorded and recorded layers of the recording layer is shown in FIG. The dependence was tentatively determined as shown in FIG. 46 (this complex refractive index is assumed to be an arbitrary k, and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 48 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From this result, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 530 nm (530 nm) and a high recording contrast.

Example 23 (1) Layer structure Substrate / high refractive index layer / recording layer / (high refractive index layer / low refractive index layer) m / air layer (2) Refractive index of substrate, air layer and each layer Refractive index: 1.52 Air layer refractive index: 1.0 Refractive index of low refractive index layer 1: 38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer, (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) High refractive index Layer thickness: d = λ ₀ /(4×2.40) (4) Number of layers m: 2 Recording / recording from the substrate side on the optical information recording medium having the above-described configuration.
Reproduction is performed at a recording / reproduction wavelength of ₀ : 550 (nm).

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the recording layer during non-recording and during recording is shown in FIG. The dependence was tentatively determined as shown in FIG. 50 (this complex refractive index is assumed to be an arbitrary k, and n is determined from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 51 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From this result, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 500 nm and a high recording contrast.

Example 24 (1) Layer structure Substrate / high refractive index layer / recording layer / (high refractive index layer / low refractive index layer) m / air layer (2) substrate, air layer and refractive index of each layer substrate refraction Refractive index: 1.52 Air layer refractive index: 1.0 Refractive index of low refractive index layer 1: 38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer, (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) High refractive index Layer thickness: d = λ ₀ /(4×2.40) (4) Number of layers m: 2 Recording / recording from the substrate side on the optical information recording medium having the above-described configuration.
Reproduction is performed at a recording / reproduction wavelength of ₀ : 550 (nm).

Under the above-mentioned layer configuration conditions, the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in the unrecorded state and in the recorded state is shown in FIG. The dependence was tentatively determined as shown in FIG. 53 (this complex refractive index is obtained by assuming an arbitrary k and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 54 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From this result, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 500 nm and a high recording contrast.

Example 25 (1) Layer Structure Substrate / High refractive index layer / Recording layer / (High refractive index layer / Low refractive index layer) m / Air layer (2) Refractive index of substrate, air layer and each layer Substrate refraction Refractive index: 1.52 Air layer refractive index: 1.0 Refractive index of low refractive index layer 1: 38 (MgF ₂ ) Refractive index of high refractive index layer: 2.40 (TiO ₂ ) (however, low refractive index layer, (3) Thickness of substrate and each layer Thickness of substrate: Thickness of low refractive index layer: d = λ ₀ /(4×1.38) High refractive index Layer thickness: d = λ ₀ /(4×2.40) (4) Number of layers m: 2 Recording / recording from the substrate side on the optical information recording medium having the above-described configuration.
Reproduction is performed at a recording / reproduction wavelength of ₀ : 550 (nm).

FIG. 55 shows the wavelength dependence of the imaginary part of the complex refractive index of the recording layer between the unrecorded state and the recorded state under the above-mentioned layer structure conditions. The dependence was tentatively determined as shown in FIG. 56 (this complex refractive index is obtained by assuming an arbitrary k and n is obtained from the relationship of Kramers-Kronig). The film thickness of the recording layer is d = λ ₀ / [4 × n (λ ₀ )]. FIG. 57 shows the result of calculating the reflectance at the time of recording and at the time of non-recording under the above conditions. From this result, it is possible to provide an optical information recording medium having a high reflectance in a wavelength region near 500 nm and a high recording contrast.

In the above examples, Examples 1 to 22 are examples in which the recording layer is used as a high refractive index layer, and Examples 23 to 25 are cases in which the recording layer is used as a low refractive index layer. However, these results are merely examples of the present embodiment, and since an arbitrary complex refractive index is assumed in the present embodiment, the unrecorded reflectance and the recording / reproducing contrast may be further improved. In this embodiment, examples of the shift of the spectrum from the unrecorded absorption spectrum to the longer wavelength side include a change in the structure of the dye, a change in the aggregation state, a change in the association state, a change in the crystal state, and a phase change. On the other hand, when the spectrum shifts from the unrecorded absorption spectrum to the shorter wavelength side, similarly, for example, a change in the structure of the dye, a change in the aggregation state, a change in the association state, a change in the crystal state, a phase change, and the like can be given.

Whether an arbitrary material such as a dye moves to a short wavelength or a long wavelength by recording from an absorption spectrum at the time of unrecording depends on the structure of the material, the presence or absence of the substituent, the type of the substituent, and the location of the substituent. And the size of the substituent. This is because, for example, the absorption spectrum of an H-aggregate of a dye generally moves to a short wavelength, and the absorption spectrum of a J-aggregate moves to a long wavelength.
These changes are determined by the type and position of the substituent. The effect of substituents on the formation of aggregates is completely different when the structure and the like change.However, for dyes having a cyanine-based structure, for example, `` Substituents affecting aggregate formation of thiacyanine dyes Impact ", Photographic Society of Japan, vol. 58, No. 4, 1995 (Heisei 7), p.361. In the present invention, the recording layer material can be used as both a low refractive index layer and a high refractive index layer. Further, by forming a laminated structure, the range of the complex refractive index required for the recording layer material is greatly relaxed. As a result, the range of material selection is greatly expanded. This is clear from the fact that high reflectance and high recording contrast are achieved in some examples assuming an arbitrary complex refractive index.

[0078]

According to the present invention, a high reflectance type optical information recording medium can be provided even at a wavelength at which a high reflectance cannot be obtained with a metal reflection layer, because the metal reflection layer which was conventionally required for increasing the reflectance is not required. Provided is a novel optical information recording medium that can record and reproduce high-contrast information by changing an optical constant of a recording layer by recording, and a recording method of the optical information recording medium. This achieves high reflectivity in the wavelength range that could not be achieved with a metal reflective film,
High-contrast recording can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing the wavelength dependence of a gold reflection film.

FIG. 2 is a diagram showing the wavelength dependence of the complex refractive index of a dye.

FIG. 3 is a diagram showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Examples 1 and 2.

FIG. 4 is a diagram showing the wavelength dependence of the real part of the complex refractive index of the recording layer in Examples 1 and 2.

FIG. 5 is a diagram showing the reflectance when recording is not performed and when recording is performed in the first embodiment.

FIG. 6 is a diagram illustrating reflectance when recording is not performed and when recording is performed according to the second embodiment.

FIG. 7 is a diagram showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Example 3.

FIG. 8 is a diagram showing the wavelength dependence of the real part of the complex refractive index of the recording layer in Example 3.

FIG. 9 is a diagram illustrating reflectance when recording is not performed and when recording is performed according to a third embodiment.

FIG. 10 is a diagram showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Examples 4 and 5.

FIG. 11 is a graph showing the wavelength dependence of the real part of the complex refractive index of the recording layer in Examples 4 and 5.

FIG. 12 is a diagram illustrating reflectances when recording is not performed and when recording is performed according to a fourth embodiment.

FIG. 13 is a diagram illustrating reflectance when recording is not performed and when recording is performed according to a fifth embodiment.

FIG. 14 is a diagram showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Examples 6 and 7.

FIG. 15 is a graph showing the wavelength dependence of the real part of the refractive index of the recording layer in Examples 6 and 7.

FIG. 16 is a diagram illustrating reflectances when recording is not performed and when recording is performed according to a sixth embodiment.

FIG. 17 is a diagram illustrating reflectances when recording is not performed and when recording is performed according to a seventh embodiment.

FIG. 18 is a graph showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Examples 8 and 9.

FIG. 19 is a diagram showing the wavelength dependence of the real part of the complex refractive index of the recording layer in Examples 8 and 9.

FIG. 20 is a diagram illustrating reflectances when recording is not performed and when recording is performed in Example 8.

FIG. 21 is a diagram illustrating reflectance when recording is not performed and when recording is performed according to a ninth embodiment.

FIG. 22 is a diagram showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Examples 10 and 11.

FIG. 23 is a diagram showing the wavelength dependence of the real part of the complex refractive index of the recording layer in Examples 10 and 11.

FIG. 24 is a diagram showing the reflectance when recording is not performed and when recording is performed in Example 10.

FIG. 25 is a diagram illustrating reflectances when recording is not performed and when recording is performed in the eleventh embodiment.

FIG. 26 is a graph showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Examples 12 and 13.

FIG. 27 is a graph showing the wavelength dependence of the real part of the complex refractive index of the recording layer in Examples 12 and 13.

FIG. 28 is a diagram illustrating reflectance when recording is not performed and when recording is performed in Example 12.

FIG. 29 is a diagram illustrating reflectance when recording is not performed and when recording is performed according to a thirteenth embodiment.

FIG. 30 is a diagram showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Example 14.

FIG. 31 is a graph showing the wavelength dependence of the real part of the complex refractive index of the recording layer in Example 14.

FIG. 32 is a diagram illustrating reflectances when recording is not performed and when recording is performed in Example 14.

FIG. 33 is a diagram showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Examples 15 and 16.

FIG. 34 is a diagram showing the wavelength dependence of the real part of the complex refractive index of the recording layer in Examples 15 and 16.

FIG. 35 is a diagram showing reflectances when recording is not performed and when recording is performed in Example 15.

FIG. 36 is a graph showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Example 16.

FIG. 37 is a diagram showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Examples 17 and 18.

FIG. 38 is a graph showing the wavelength dependence of the real part of the complex refractive index of the recording layer in Examples 17 and 18.

FIG. 39 is a diagram showing the reflectance at the time of non-recording and at the time of recording in Example 17.

FIG. 40 is a graph showing the reflectance when recording is not performed and when recording is performed in Example 18.

FIG. 41 is a graph showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Examples 19 and 20.

FIG. 42 is a graph showing the wavelength dependence of the real part of the complex refractive index of the recording layer in Examples 19 and 20.

FIG. 43 is a diagram showing reflectance when recording is not performed and when recording is performed in Example 19.

FIG. 44 is a graph showing the reflectance when recording is not performed and when recording is performed in Example 20.

FIG. 45 is a diagram showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Examples 21 and 22.

FIG. 46 is a graph showing the wavelength dependence of the real part of the complex refractive index of the recording layer in Examples 21 and 22.

FIG. 47 is a diagram showing the reflectance when recording is not performed and when recording is performed in Example 21.

FIG. 48 is a graph showing reflectances when recording is not performed and when recording is performed in Example 22.

FIG. 49 is a graph showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Example 23.

FIG. 50 is a graph showing the wavelength dependence of the real part of the complex refractive index of the recording layer in Example 23.

FIG. 51 is a graph showing reflectances when recording is not performed and when recording is performed in Example 23.

FIG. 52 is a graph showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Example 24.

FIG. 53 is a graph showing the wavelength dependence of the real part of the complex refractive index of the recording layer in Example 24.

FIG. 54 is a diagram illustrating reflectance when recording is not performed and when recording is performed in Example 24.

FIG. 55 is a graph showing the wavelength dependence of the imaginary part of the complex refractive index of the recording layer in Example 25.

FIG. 56 is a graph showing the wavelength dependence of the real part of the complex refractive index of the recording layer in Example 25.

FIG. 57 is a diagram showing reflectance when recording is not performed and when recording is performed in Example 25.

FIG. 58 is a diagram showing a change in reflectance depending on the number of stacked multilayer layers.

[Explanation of symbols]

 R reflectance n real part of complex refractive index k imaginary part of complex refractive index A unrecorded state B recorded state

Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 7/24 533 G11B 7/24 533L 533N 7/00 7/00 Q (72) Inventor Yasunobu Ueno 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 Inside Ricoh Co., Ltd. (72) Inventor Yasuhiro Higashi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (18)

[Claims] 1. Recording / reproduction of information is possible by irradiation of a laser beam, and a substrate / recording layer / (low refractive index layer / high refractive index layer)
m (where m is the number of layers) and an optical information recording medium in which recording / reproduction is performed from the substrate side.
(1) m is 1 or more, and (2) the thicknesses of the recording layer, the low refractive index layer, and the high refractive index layer are all at least at the reproduction wavelength.
n _i d _i = input _0/4 (where n _i is the refractive index of each layer material, the thickness of d _i are each material, input ₀ is the recording and reproducing wavelength) optical information recording medium according to Toku傲that it is. 2. Recording and reproduction of information are possible by irradiation of a laser beam, and a substrate / (high refractive index layer / low refractive index layer) p / recording layer / (low refractive index layer / high refractive index layer) r ( However, in an optical information recording medium having a layer configuration of (p and r are the number of laminations) and recording / reproducing is performed from the substrate side, (1) p is 1 or more, r is 0 or 1 or more, and (2) Recording layer, low refractive index layer,
Thickness of the high refractive index layer, in either at least reproduction wavelength, n _i d _i = input _0/4 (where n _i is the refractive index of each layer material,
The film thickness of d _i are each material, the optical information recording medium according to Toku傲that input ₀ is the recording and reproducing wavelength). 3. Recording and reproduction of information can be performed by irradiating a laser beam, and a substrate / high refractive index layer / recording layer / (high refractive index layer /
(1) m is 1 or more, and (2) the recording layer , low refractive index layer, the thickness of the high refractive index layer, in either at least reproduction wavelength, of n _i d _i = input _0/4 (where n _i is the refractive index of each layer material, d _i is each material thickness the optical information recording medium according to Toku傲that input ₀ is the recording and reproducing wavelength). 4. Recording and reproduction of information are possible by irradiation with a laser beam, and it is referred to as low refractive index layer / recording layer / (low refractive index layer / high refractive index layer) m / substrate (where m is the number of layers). In an optical information recording medium having a layer structure and recording / reproducing is performed from the low refractive index layer side, (1) m is 1 or more;
Low refractive index layer, the film thickness of the high refractive index layer, in either at least reproduction wavelength, of n _i d _i = input _0/4 (where n _i is the refractive index of each layer material, d _i is each material thickness, the optical information recording medium according to Toku傲that input ₀ is the recording and reproducing wavelength). 5. Recording and reproduction of information are possible by irradiation of a laser beam, and a high refractive index layer / recording layer / (high refractive index layer / low refractive index layer) m / substrate (where m is the number of layers). In an optical information recording medium having a layer configuration and recording / reproducing is performed from the high refractive index layer side, (1) m is 1 or more;
Low refractive index layer, the film thickness of the high refractive index layer, in either at least reproduction wavelength, of n _i d _i = input _0/4 (where n _i is the refractive index of each layer material, d _i is each material thickness, the optical information recording medium according to Toku傲that input ₀ is the recording and reproducing wavelength). 6. Recording / reproduction of information is possible by irradiating a laser beam, and (high refractive index layer / low refractive index layer) p / recording layer /
(1) In an optical information recording medium having a layer structure of (low refractive index layer / high refractive index layer) r / substrate (where p and r are the number of laminations) and recording / reproducing is performed from the substrate side, p is 1 or more, r is 0 or 1 or more, (2) a recording layer, a low refractive index layer,
Any of the thickness of the high refractive index layer is, at least in reproduction wavelength, n _i d _i = input _0/4 (where n _i is the refractive index of each layer material,
The film thickness of d _i are each material, the optical information recording medium according to Toku傲that input ₀ is the recording and reproducing wavelength). 7. Recording and reproduction of information can be performed by irradiating a laser beam, and (low refractive index layer / high refractive index layer) p / recording layer /
An optical information recording medium having a layer structure of (high refractive index layer / low refractive index layer) r / substrate (where p and r are the number of layers) and recording / reproducing is performed from the low refractive index layer side, (1) p
One or more, r is 0 or 1 or more, (2) recording layer, a low refractive index layer, the film thickness of the high refractive index layer, in either at least reproduction wavelength, n _i d _i = input _0/4 (where n _i is the refractive index of each layer material, the thickness of d _i are each material, the optical information recording medium according to Toku傲that input ₀ is the recording and reproducing wavelength). 8. An optical constant of a real part of a complex refractive index, an imaginary part of a complex refractive index or an optical constant of a film thickness, or a change of two or more optical constants among the three optical constants. An optical information recording medium characterized by the above-mentioned. 9. The optical information according to claim 1, wherein the reflectance at the time of recording is lower than the reflectance at the time of non-recording due to a change in an optical constant. recoding media. 10. The method according to claim 1, wherein the reproduction wavelength is at least 550 nm or less.
The optical information recording medium according to the above. 11. The recording layer according to claim 1, wherein the main component is a dye compound.
11. The optical information recording medium according to 8, 9, or 10. 12. The optical information recording medium according to claim 11, wherein the dye compound is a dye compound exhibiting photochromic properties. 13. The optical information recording medium according to claim 11, wherein the dye compound is formed by a vapor deposition method. 14. The method according to claim 1, wherein a main component of the recording layer is a compound exhibiting thermochromic properties.
The optical information recording medium according to 3, 4, 5, 6, 7, 8, 9 or 10. 15. The optical information recording medium according to claim 14, wherein the compound exhibiting thermochromic properties is formed by a vapor deposition method. 16. The method of claim 1, 2, 3, 4, 5, 6, 7,
By irradiating the optical information recording medium described in 8, 9, 10, 11, 12, 13, 14 or 15 with a laser beam, the real part of the complex refractive index of the recording layer, the imaginary part of the complex refractive index, or the film thickness of the film thickness is reduced. A method of recording an optical information recording medium, wherein a change in an optical constant or an optical constant of two or more of the three optical constants is caused. 17. The recording method for an optical information recording medium according to claim 16, wherein the reflectance at the time of recording is made lower than the reflectance at the time of non-recording by changing the optical constant. 18. The recording method for an optical information recording medium according to claim 16, wherein a reproduction wavelength is 550 nm or less.