JPH0442199B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a writable optical information recording medium having at least a light absorption layer and a reflection layer on a transparent substrate. [Prior Art] A so-called writable optical information recording medium that can record data by irradiation with a laser beam has a metal layer such as Te, Bi, Mn, etc., a dye layer such as cyanine, merocyanine, phthalocyanine, etc. The recording layer is irradiated with a laser beam to deform, sublimate, evaporate, or modify the recording layer to form pits and record data. In optical information recording media having this recording layer, voids are generally provided behind the recording layer in order to facilitate deformation, sublimation, evaporation, denaturation, etc. of the recording layer when forming pits. . Specifically, for example,
A stacked structure called an air sandwich structure is used, in which two substrates are stacked with a space in between. In this optical information recording medium, pits are formed by irradiating laser light from the side of the transparent substrate 1. When playing back the recorded data,
A laser beam having a weaker power than during recording is irradiated from the substrate 1 side, and the signal is read based on the difference in reflected light between the pit and other parts. On the other hand, so-called ROM type optical information recording media, on which data is recorded in advance and cannot be subsequently written or erased, have already been widely put into practical use in the information processing and audio sectors. This type of optical information recording medium does not have the above-mentioned recording layer, but pits for reproducing recorded data are formed in advance on a transparent substrate by means such as pressing, and Au, Ag, etc. A reflective layer made of a metal film such as , Cu, or Al is formed, and this is further covered with a protective layer. The most typical ROM-type optical information recording medium is the compact disk, or so-called CD, which is widely used in audio and information processing departments.
The recording and playback signal specifications for this CD are so-called CD
The playback device that has been standardized and complies with this standard is the compact disc player (CD player).
It is extremely widespread as a. [Problem to be solved by the invention] The above-mentioned writable optical information recording medium also has the following problems:
Because it is a recording method that uses the same laser light as CDs,
When playing, it is strongly desired that the CD be compliant with the already widely used CD. However, writable optical information recording media such as the above-mentioned air sandwich structure record by forming pits on the recording layer rather than on the substrate, and usually do not have a reflective layer, so there is no reflection. It was difficult to increase the reflectance, and it was difficult to satisfy the reflectance specified in the CD standard. There are also optical information recording media that have a recording layer and a reflective layer on a substrate, but there is still no optical information recording medium that can provide a reproduced signal that satisfies the modulation degree, reflectance, etc. required by the CD standard. Nakatsuta. The present invention was made in order to solve the above-mentioned conventional problems, and when reproducing data, an optical signal having a high reflectance of 70% or more and an output signal with a modulation degree compliant with the CD standard can be obtained. The purpose is to provide information recording media. [Means for Solving the Problems] That is, in order to achieve the above object, the gist of the means adopted in the present invention is that a light absorption layer is provided on a transparent substrate directly or via another layer,
In the optical information recording medium in which a reflective layer is provided on the light absorption layer directly or via another layer, the light absorption layer is composed of a layer containing a cyanine dye, and the imaginary part of the complex refractive index kabs is 0.3. The following is an optical information recording medium characterized in that a light reflecting layer is formed of a metal film. Further, in the above optical information recording medium, the cyanine dye forming the light absorption layer is indodicarbocyanine, or in the above optical information recording medium, the cyanine dye forming the light absorption layer is the following general An optical information recording medium characterized by being a compound represented by the formula. (However, A and A' are atomic groups forming a benzene ring or substituted benzene ring, or forming a naphthalene ring or substituted naphthalene ring,
They may be of the same species or different species. B is pentamethine (-CH=CH-CH=CH
-CH=), and each hydrogen atom may be substituted with a halogen atom, an alkyl group, an alkoxy group, a diphenylamino group, etc., or may have a substituted or unsubstituted cyclic side chain spanning multiple carbon atoms. good. R ₁ and R ₁ ′ are substituted or unsubstituted alkyl groups,
Alroxy group, alkylhydroxy group, aralkyl group, alkenyl group, alkylcarboxyl group,
It is an alkylsulfonyl group or an alkylcarboxyl group or an alkylsulfonyl group bonded to an alkali metal ion or an alkyl group, and they may be the same or different. X ₁ ^- is a halogen atom, perchloric acid, borofluoric acid, benzenesulfonic acid, toluenesulfonic acid,
It represents an anion such as alkylsulfonic acid, benzenecarboxylic acid, alkylcarboxylic acid, or trifluorotylcarboxylic acid, and when R ₁ and R ₁ ' have a group bonded to an alkali metal ion, X ₁ ^- is not present. It's okay. ) In the above optical information recording medium, ρ=nabs・dabs/λ given by the real part nads of the complex refractive index of the light absorption layer, the film thickness dabs, and the wavelength λ of the reproduction light is expressed as
It is desirable that 0.05≦ρ≦0.6. [Function] By using a light-transmitting substrate, laser light can be input from the substrate side, thereby giving energy to the light absorption layer. When the light absorption layer is a cyanine dye, since the dye is a material with a high refractive index, a large phase difference can be obtained even if the change in the optical path length of the light absorption layer is small. Therefore, it is possible to easily obtain a modulation degree that satisfies the CD standard. In particular, when indodicarbocyanine is used as the cyanine dye, it is easy to suppress the imaginary part kabs of the complex refractive index to 0.3 or less in the near-infrared semiconductor laser oscillation wavelength range, that is, 740 to 850 nm. Therefore, it is possible to achieve a reflectance that complies with the CD standard. By forming the reflective layer with a metal film, a metal film with high reflectance is formed, so a high reflectance that complies with the CD standard can be easily obtained. Furthermore, the present inventors have discovered that in order for such an optical information recording medium to have a reflectance of 70% or more in accordance with the CD standard, the imaginary part of the complex refractive index of the light absorption layer 2 must be
We found that kabs is an important parameter. Figure 9 shows that in an optical information recording medium that uses an Au film as a reflective layer, the translucency of the light absorption layer made of cyanine dye is changed, and the imaginary part kabs is made close to 0 while keeping the film thickness constant. It is a graph showing the change in reflectance when changing the value from 2.0. Looking at this graph, when kabs exceeds 0.3%,
Reflectance is generally low at 30% or less, especially 0.8 to 0.9
It can be seen that the reflectance is lowest in the vicinity. When kadS exceeds 0.3% and becomes lower than that, the reflectance increases rapidly. From this result, in order for the optical information recording medium to stably maintain high reflectance, the imaginary part of the complex refractive index of the light absorption layer must be 0.3.
It can be said that the following needs to be true. In other words, kabs. If it is larger than 03, it is difficult to obtain high reflectance. The kabs of the light absorption layer is 0.3 or less.
The closer it gets to , the more the reflectance improves. However, the closer it gets to 0, the worse the recording sensitivity becomes, so it needs to be larger than 0. Specifically, a range of 0.1 or less is desirable, and in practice, 0.05
Preferably before and after. Furthermore, in order for the optical information recording medium to stably maintain a reflectance of 70% or more while also enabling recording and playback that satisfies the CD standard, in addition to the above-mentioned KABS, the inventors have determined that Focusing on the fact that ρ=nabs・dabs/λ, which is given by the real part nabs of the complex refractive index of the layer, its film thickness dabs, and the wavelength λ of the reproduction light, is a very important parameter,
As a result of experiments and simulations, the 8th
We were able to obtain the relationship shown in the figure. Figure 8 shows
When a semiconductor laser with a wavelength λ = 780 nm is used as the reproduction light, ρ is given by the real part nabs of the complex refractive index of the light absorption layer of the optical information recording medium, its film thickness dabs, and the wavelength λ of the reproduction light. = nabs・dabs/λ
It is a graph showing the relationship between the reflectance of light incident from the substrate side and the reflectance of light incident from the substrate side. Looking at this graph, it can be seen that when ρ is smaller than 0.6, it is almost certainly possible to secure a reflectance of 70% or more. Areas where ρ is less than 0.05,
Even in a region exceeding 0.6, a reflectance of 70% or more may be obtained. However, if ρ is less than 0.05, the thickness dabs of the light absorption layer should be set to 0.05 μm.
Since it has to be made considerably thinner, it is difficult to form pits for recording data, and the reproduction signal as described above cannot be obtained. Also,
If the area exceeds 0.6, the recording characteristics will vary,
There are practical problems such as I3/Itop being less than 0.3 and jitter error increasing. For this reason, recording and reproducing data is still difficult, and the reproduced signal as described above cannot be obtained. In other words, ρ is 0.05 ~
It can be seen that by setting the value to 0.6, it is possible to record and reproduce data that conforms to the CD format while maintaining the reflectance at 70% or more, which conforms to the CD format. When the above results are summarized, the results shown in FIG. 10 can be obtained. FIG. 10 is a graph showing the critical values of combinations of ρ and kads that comply with the CD standard. As you can see from this graph, the optical information recording medium satisfies the CD standard.
Although it has a reflectance of more than %, it still
In order to enable recording and playback that satisfies the standards, the above kabs should be 0.3 or less, and ρ=nabs・
It can be seen that it is necessary to set dabs/λ in the range of 0.05 to 0.6. In other words, when kabs is less than 0.3,
When ρ is smaller than 0.05, the reflectance may be 70% or more, but the block error rate becomes worse, and when ρ is larger than 0.6, the reflectance becomes low. Furthermore, even if ρ is within the range of 0.05 to 0.6, if kabs is greater than 0.3,
The reflectance becomes extremely low, making it difficult to satisfy all the conditions of the CD standard. Furthermore, ρ=nabs・dabs/λ is 0.05~
A range of 0.6 is desirable, but in order to obtain a sufficient degree of modulation, a range of 0.1 or more is desirable, and in order to obtain stable recording characteristics with a large degree of modulation, a range of 0.45±
A range of 0.1 is most desirable. Note that the present invention can be applied even when there are layers other than those already described. For example, when a transparent layer (for example, an enhancement layer such as SiO ₂ , an undercoat layer, etc.) is provided between the substrate and the light absorption layer,
This layer may be treated as a part of the substrate and the above constants may be treated as a layer between the light absorption layer and the reflection layer (for example,
(adhesive layer, hard layer, etc.), consider these layers as the second absorption layer and calculate ρ = (n ₁ d ₁ +
n ₂ ·d ₂ )/λ, and in the case of multiple layers, it can be treated in the same way as above by setting ρ=Σ(n _i ·d _i /λ (where ai is an integer). In addition, if k is not 0, it can be treated in the same way as in the case of a single layer by calculating the average value of k from the ratio of film thicknesses as K = Σd _i k _i /Σd _i . When a groove is formed on the substrate, dabs is expressed as the average value of the total area of the film thickness of the light absorption layer in the groove and the film thickness of the light absorption layer in the land portion.Optical information recording according to the present invention According to the medium, by irradiating the light absorption layer with laser light from the transparent substrate side, energy is given to the light absorption layer, and pits are formed by the energy.At this time,
Not only may holes be formed in the light absorption layer, but also deformation of layers adjacent to the light absorption layer may occur. The pits formed by the optical information recording medium according to the present invention exhibit the same function as pits formed in advance on the surface of a substrate by pressing or other means such as a CD. Therefore, a playback signal similar to that of a CD can be obtained. [Example] Next, an example of the present invention will be described in detail with reference to the drawings. Examples of the schematic structure of the optical information recording medium according to the present invention are shown in FIGS. 1 to 7. In the same figure, 1
2 is a light-absorbing layer formed on the transparent substrate, which has the function of absorbing irradiated laser light and forming pits in the layer in contact with it. The reference numeral 6 shown only in FIGS. 4 to 7 is an intermediate layer that exists between the transparent substrate 1 and the light absorption layer 2. When this exists, energy is applied to the light absorption layer 2. As a result, the intermediate layer 6 is deformed and pits 5 are formed as shown in FIG. Furthermore, if the intermediate layer 6 is relatively thin, the deformation may extend to the substrate 1, as shown in FIG. Furthermore, if such an intermediate layer 6 does not exist, as shown in FIG.
The interface is deformed, and a pit 5 is formed there. Further, 3 is a reflective layer formed thereon, 4
indicates a protective layer provided on the outside. Figures 2, 4 and 6 show the state before recording with laser light, and Figures 3, 5 and 7 show the state before recording with laser light.
The state after recording by laser light, that is, the state in which pits 5 are formed is schematically shown. The material of the transparent substrate 1 is preferably a highly transparent material with a refractive index in the range of 1.4 to 1.6 with respect to laser light, and a resin with excellent impact resistance. Specific examples include polycarbonate, acrylic, etc., but are not limited to these. The substrate 1 is molded using the materials described above, for example, by injection molding or the like. A preglue may be formed in a spiral shape on such a substrate 1. Prigrug is
Although any conditions may be used as long as they are normally considered, a depth of 50 to 520 nm is preferable, and more preferably a depth of 80 to 180 nm. The pregroove is usually formed by pressing a stamper during injection molding of the substrate 1, but it may also be formed by laser cutting or the 2P method. At this time, if the hardness of the layer on the substrate 1 side adjacent to the light absorption layer 2 is low, the degree of deformation will be greater, and therefore the difference in optical path length between the undeformed region and the deformed region will become large. As a result, it is possible to increase the optical phase difference of the reproduced light during reproduction, which is desirable because the degree of modulation can be increased. An intermediate layer 6 may be provided between the substrate 1 and the light absorption layer 2. In this case, the material for the intermediate layer 6 is as follows:
Examples include polycarbonate, acrylic, and epoxy, and the hardness can be adjusted by changing the molecular weight and composition. Note that, as already explained, the transparent substrate 1 may be deformed without providing the intermediate layer 6, or the intermediate layer 6 may be provided very thinly, and the transparent substrate 1 may be deformed together with the intermediate layer 6. may be deformed. Furthermore, a solvent-resistant layer or an enhancement layer such as SiO ₂ may be coated as an intermediate layer 6 between the substrate 1 and the light absorption layer 2. The cyanine dye contained in the light absorption layer 2 is represented by the following general formula. A dye with a structure in which heterocycles are linked by methine chains. However, in the above chemical formula, Y and Y' are O, S,
Se, NH, -CH=CH-, _CH3 -C-CH3 _, etc., R and R' are alkyl groups, etc., X is a halogen atom, etc., and n is 0, 1, 2, 3... Specifically, indolenine cyanine dyes, thiazole cyanine dyes, etc. can be exemplified, and the following may be mentioned. However, in the above chemical formulas (1) and (2), R ₁ and R ₂
and R ₃ may be the same or different, each represents a C ₁ to _{C 6} alkyl group, and X represents halogen, perhalogen acid, tetrafluoroboric acid, toluenesulfonic acid or alkyl sulfuric acid, A represents a benzene ring or a naphthyl ring, and each ring has a substituent such as alkyl, alkoxy,
Hydroxy, carboxyl, halogen, allyl or alkyl carboxyl may be present or absent, and n represents 0 or an integer from 1 to 3. Furthermore, each carbon forming the methine chain may be substituted with an alkyl group or a halogen atom, and each carbon may be cyclically bonded with a saturated hydrocarbon. Moreover, X may be a metal complex anion shown below. However, in the above formulas (3) to (7), M is Ni, Co,
Indicates transition metals such as Mn, Cu, Pd and Pt, R ₁
to R ₄ may be the same or different, and each represents a substituted or unsubstituted alkyl, aryl, or amino group, and R ₅ to R ₁₂ may be the same or different, and each represents a hydrogen atom. , halogen atom or substituted or unsubstituted alkyl,
Acyl, alkoxy, acyloxy, aryl,
represents an alkenyl or amino group, R ₁₃ represents a substituted or unsubstituted amino group, l, m, n, p,
q and r represent 0 or 1 to 4, and u and v
indicates 0 or 1-2. However, the present invention is not limited to the above-mentioned cyanine dyes, and may include other cyanine dyes, such as quinoline cyanine dyes and oxazole cyanine dyes, as long as they are light-absorbing cyanine dyes. It is also possible to obtain the effects of the present invention. Indodicarbocyanine, which is a more desirable cyanine dye for obtaining the effects of the present invention, is represented by the following formula. However, A and A' are atomic groups forming a benzene ring or a substituted benzene ring, or forming a naphthalene ring or a substituted naphthalene ring,
They may be of the same species or different species. B is pentamethine (-CH=CH-CH=CH
-CH=), and each hydrogen atom may be substituted with a halogen atom, an alkyl group, an alkoxy group, a diphenylamino group, etc., or may have a substituted or unsubstituted cyclic side chain spanning multiple carbon atoms. good. R ₁ and R ₁ ′ are substituted or unsubstituted alkyl groups,
Alkoxy group, alkylhydroxy group, aralkyl group, alkenyl group, alkylcarboxyl group,
It is an alkylsulfonyl group or an alkylcarboxyl group or an alkylsulfonyl group bonded to an alkali metal ion or an alkyl group, and they may be the same or different. X ₁ ^- is a halogen atom, perchloric acid, borofluoric acid, benzenesulfonic acid, toluenesulfonic acid,
It represents an anion such as alkylsulfonic acid, benzenecarboxylic acid, alkylcarboxylic acid, or trifluorotylcarboxylic acid, and when R ₁ and R ₁ ' have a group bonded to an alkali metal ion, X ₁ ^- is not present. It's okay. Substituents A and A' of the cyanine dye represented by the above general formula include a substituted or unsubstituted benzene ring or a substituted or unsubstituted naphthalene ring, and these substituents may be singular or plural. In some cases, an alkyl group, an alkoxy group, a hydroxy group, a carboxyl group, a halogen atom, an allyl group, an alkylcarboxyl group,
Examples include an alkylalkoxy group, an aralkyl group, an alkylcarbonyl group, a sulfonate alkyl group bonded to a metal ion, a nitro group, an amino group, an alkylamino group, an aryl group, a phenylethylene group, and the following.

[Formula] −CH=CH−CN, −NHCOCH ₃ ,

【formula】

[Formula] Furthermore, a mixture of a plurality of indolenine cyanines having each of these substituents can also be used. For example, the substituents attached to the substituents A and A' of these substances can be exemplified by those shown in Table 1.

【table】

[Table] One of the two types of cyanine may be a cyanine other than indodicarbocyanine. The cyclic side chain bonded to B in the above general formula is:
Bonds between multiple carbons of the pentamethine chain, e.g. between the second and fourth carbons, e.g.

【formula】 【formula】

【formula】

【formula】

Examples include bonded chains consisting of carbon and other atoms forming a 4-, 5-, or 6-membered ring such as [Formula], which may have a substituent. B is directly bonded or the substituent R on the cyclic side chain includes, in addition to a hydrogen atom, a halogen atom, a diphenylamino group, an alkoxy group (for example, a lower alkoxy group such as methoxy or ethoxy), an alkyl group (for example, methyl or ethyl). and lower alkyl groups). n=1, 2, 3, 4 n=1, 2, 3, 4 Value of n=1, 2, 3 or 4 R is an alkyl group, Ne or K n=1, 2, 3, 4 n=1, 2, 3, 4 n = 1, 2, 3, 4...8 m ₁ - m ₆ = 0, 1, 2, 3, 4 (all do not include 0) n = 1, 2, 3, 4...8 m ₁ - m ₆ = 0, 1, 2, 3, 4 (all do not include 0) n = 1, 2, 3, 4...8 m ₁ - m ₆ = 0, 1, 2, 3, 4 (all do not include 0) n = 1, 2, 3, 4...8 m ₁ - m ₆ = 0, 1, 2, 3, 4 (all do not include 0) R is an alkyl group, Na or K n=1, 2, 3, 4...8 n=1, 2, 3, 4...8 n=1, 2, 3, 4...8 R is an alkyl group, Na or K n=1, 2, 3, 4...8 n=1, 2, 3, 4...8 R is an alkyl group, Na or K n=1, 2, 3, 4...8 n=1, 2, 3, 4...8 n=1, 2, 3, 4...8 n=1, 2, 3, 4...8 n=1, 2, 3, 4...8 R is an alkyl group, Na or K n=1, 2, 3, 4...8 Specifically, in addition to those listed in the Examples below, those represented by the chemical formulas shown in 1-1 to 5-4 on pages 28 to 37 are exemplified. can. In addition to containing the above organic dye and cyanine dye, this light absorption layer 2 may also contain other dyes, resins (for example, thermoplastic resins such as nitrocellulose, thermoplastic elastomers), liquid rubber, etc. .
Thermoplastic resins include isobutylene, maleic anhydride copolymer, ethylene acetate copolymer, carboxyvinyl polymer, chlorinated polypropylene,
Polyethylene oxide, polyamide (nylon 6, nylon 12, methoxymethylated polyamide, etc.), coumaron resin, ketone resin, vinyl acetate,
polystyrene, PVA (polyvinyl alcohol),
PVE (polyvinyl ester), etc.; cellulose derivatives include carboxymethyl cellulose, nitrocellulose, HPC (hydroxypropyl cellulose), HEC (hydroxyethyl cellulose),
MC (methylcellulose), EC (ethylcellulose), EHEC (ethylhydroxyethylcellulose), CMEC (carboxymethylethylcellulose), etc. are oligomers such as oligostyrene,
Methylstyrene oligomers, etc. are used as elastomers and
Examples of the rubber include styrene block copolymer and urethane thermoplastic elastomer. The light absorption layer 2 is formed by first coating the surface of the substrate 1 with a solution of the cyanine dye dissolved in an organic solvent such as acetylacetone, methyl cellosolve, or toluene.
Examples of means for this purpose include vapor deposition, LB
method, spin coating method, etc., but the film thickness of the light absorption layer 2 can be controlled by adjusting the concentration, viscosity of the paint, drying speed of the solvent, etc.
Spin coating is preferred. The organic solvents mentioned above include methanol, ethanol, propanol, isopropyl alcohol, butanol, amyl alcohol, isoamyl alcohol, hexyl alcohol, heptanol, benzyl alcohol, cyclohexanol,
Alcohols such as furfuryl alcohol, cellosolve, diethyl cellosolve, butyl cellosolve,
Ethanols such as methyl carbitol, carbitol, acetal, dioxane and tetrahydrofuran, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diacetone alcohol, cyclohexanone, acetophenone, ethyl formate, butyl formate, amyl formate, methyl acetate, acetic acid Esters such as ethyl, propyl acetate, butyl acetate, amyl acetate, phenyl acetate, methyl cellosolve acetate, cellosolve acetate,
nitromethane, nitroethane, nitropropane,
Nitrohydrocarbons such as nitrobutanol and nitrobenzene, methyl chloride, methylene chloride, chloroform, methyl bromide, bromoform, methylene iodide, ethyl chloride, ethylene chloride, ethylidene chloride, trichloroethane, trichloroethylene, propylene chloride, butyl chloride, Chlorinated solvents such as dichlorobutane, hexachloropropylene, dichloropentane, amyl chloride, chlorobenzene, 0-dichlorobenzene, trichlorobenzene, chlorotoluene, dichlorotoluene, other paraldehyde, crotonaldehyde, furfural, aldol, acetonitrile, formamide , dimethylformamide, acetol, γ-valerolactone, amylphenol, sulfolane, 2-mercaptoethyl alcohol, dimethyl sulfoxide,
Solvents such as N-methylpyrrolidone and methyl carbamate may also be used. The reflective layer 3 is formed of, for example, gold, silver, aluminum, or an alloy containing these materials by a vapor deposition method, a sputtering method, or the like. Since it is necessary to have a reflectance of 70% or more, it is desirable to use a metal mainly composed of gold or an alloy containing gold. In addition, if a hard layer with a higher thermal deformation temperature and higher hardness is provided on the reflective layer 3 side than the layer on the substrate 1 side, the pits will be formed on the layer on the substrate 1 side rather than the layer on the reflective layer 3 side. can be formed more clearly. Therefore, since no secondary reflected light is generated due to the deformed portion formed on the reflective layer 3 side, distortion of the reproduced waveform can be suppressed, and the block error rate specified in the CD standard can be kept low. can. Furthermore, another layer such as an oxidation-resistant layer for preventing oxidation of the reflective layer 3 may be interposed, and the reflective layer 3 may also function as a protective layer. The hard layer 4 is desirably made of a resin with excellent impact resistance. For example, it is formed by applying an ultraviolet curable resin using a spin coating method and curing it by irradiating it with ultraviolet rays. It may also be formed from epoxy resin, acrylic resin, silicone hard coat resin, or the like. When recording data on such an optical information recording medium, a laser is irradiated from the substrate side. The wavelength of the recording laser beam is 780n due to the relationship with the re-laser beam.
Around m is desirable. In the optical information recording medium recorded by irradiating laser light in this way, the third
As schematically shown in FIGS. 5, 5, and 7, pits 5 convex toward the light absorption layer 2 are formed on the surface portion of the optical recording medium that contacts the light absorption layer 2 on the substrate 1 side after recording.
can be confirmed, and the pit 5 formed in this way
The playback waveform of is similar to that of a CD. Furthermore, since the optical information recording medium according to the present invention can be constructed by laminating thin films such as a light absorption layer 3, a reflection layer 3, a protective layer 4, etc. on the substrate 1, the total thickness can easily be within the range specified by the CD standard. It can be accommodated. Reproduction of the recorded signal is performed by irradiating a reading laser from the substrate side and reading the change in reflectance mainly caused by the optical phase difference between the reflected light from the pit portion and the reflected light from the portion other than the pit. In this example, only the case where the light absorption layer 2 is formed on almost the entire surface of the light-transmitting substrate 1 is explained, but the light-absorption layer 2 may be formed on a part of the light-transmitting substrate. However, the area without the light absorption layer 2 can also be used as a ROM area in which pits for signal reproduction are formed in advance. For example, the surface of the transparent substrate 1
The outer periphery of the transparent substrate 1 is formed by forming pits for signal reproduction in the portion that will become the ROM area using a stamper, etc., and coating only the outer region with the above-mentioned material to form the light absorption layer 2. For example, the light absorption layer 2 is formed only in a part of the edge, and this is used as a recordable area, and a ROM area is formed in a part on the inner circumferential side. By providing a ROM area in this way, certain ROM information and personal postscript information can be stored in one recording medium. Further, the optical information recording medium according to the present invention is not limited to a disk-shaped recording medium, but can be similarly considered to a card-shaped or tape-shaped optical information recording medium. A specific example of this configuration will be described below. Example 1 A 1.2 mm thick spiral pregroup with a width of 0.8 μm, a depth of 0.08 μm, and a pitch of 1.6 μm was formed.
A polycarbonate substrate 1 having an outer diameter of 120 mmφ and an inner diameter of 15 mmφ was molded by injection molding. As an organic dye for forming the light absorption layer 2,
0.65 g of 1,1'dibutyl 3,3,3',3'tetramethyl 4,5,4',5'dibenzoindodicarbocyanine perchlorate (manufactured by Nippon Kanko Shiki Co., Ltd., product number
NK3219) was dissolved in 10 c.c. of diacetone alcohol solvent, and this was applied onto the above substrate 1 by spin coating to form a light absorption layer 2 consisting of a dye film with a thickness of 0.13 μm. The complex refractive index of this light absorption layer 2 is nabs=2.7 and kabs=0.05. As described later, the wavelength λ of the semiconductor laser of the reproduction light is
The wavelength is 780 nm, and ρ=nabs·dabs/λ=0.45. An Au film with a thickness of 400 angstroms was formed on the entire surface of this disk by sputtering method.
A reflective layer 3 was formed. The complex refractive index of this reflective layer 3 is nref=0.16 and kref=4.67. Furthermore, an ultraviolet curable resin is spin-coated on this reflective layer 3 and cured by irradiating ultraviolet rays to a thickness of 10 μm.
A protective layer 4 of m was formed. The optical disc thus obtained is coated with a wavelength of 780 nm.
A semiconductor laser with a linear velocity of 1.2 m/sec and a recording power of 6.0
It was irradiated with mW and the EFM signal was recorded. and,
Insert this optical disc into a commercially available CD player (Aurex
When reproduced with XR-V73 (wavelength of reproduction light λ = 780 nm), the reflectance was 72%, I11/Itop was 0.65, I3/
Itop was 0.35. The CD standard requires a reflectance of 70% or more and an I11/Itop of
0.6 or more, I3/Itop is defined as 0.3 to 0.7,
The optical disc according to this example satisfies this standard. Example 2 On a polycarbonate substrate 1 molded in the same manner as in Example 1 above, 0.5 g of 1,
1'-dibutyl 3,3',3,3'-tetramethyl 5,
A solution of 5′-diethoxyindodicarbocyanine iodide in 10 c.c. of isopropyl alcohol solvent was applied by spin coating, and the film thickness was
A light absorption layer 2 with a thickness of 0.10 μm was formed. The complex refractive index of this light absorption layer 2 is n _abs =2.65, k _abs =0.05, and ρ = n _abs d _abs /λ = 0.34. A Cu film with a thickness of 500 angstroms was formed on the entire surface of this disk by sputtering method.
A light reflecting layer 3 was formed. The complex refractive index of this light reflecting layer 3 is n _ref =0.12 and k _ref =4.89. Furthermore, an ultraviolet curable resin is spin-coated on the light reflective layer 3, and this is cured by irradiating ultraviolet rays to a thickness of 10 μm.
A protective layer 4 of m was formed. The thus obtained optical disk was coated with the above Example 1.
EFM signals were recorded in the same manner. Then, this optical disk was used in the same way as that used in Example 1 above.
When played back on a CD player, the reflectance of the optical disc was 71%, I ₁₁ /I _tpp was 0.63, and I ₃ /I _tpp was 0.33. Therefore, the optical disc according to this embodiment also
Like the above embodiment, it satisfies the CD standard. Example 3 On a glass substrate 1 having the same dimensions as used in Example 1 above, 0.6 g of 1,
1'-diethyl 3,3',3,3'-tetramethyl10-
A solution of chloro9,11-ethylene 4,5,4',5'-dibenzoindodicarbocyanine perchlorate dissolved in 10 c.c. of dichloroethane solvent was applied by spin coating to form a light absorbing film with a thickness of 0.13 μm. layer 2
was formed. The complex refractive index of this light absorption layer 2 is
n _abs = 2.4, k _abs = 0.04, and ρn _abs d _abs /λ = 0.40.
It is. An Au film with a thickness of 400 angstroms was formed on the entire surface of this disk by sputtering method.
A light reflecting layer 3 was formed. The complex refractive index of this light reflecting layer 3 is n _ref =0.16 and k _ref =4.67. Furthermore, an elastomer was spin-coated on this light-reflecting layer 3, and this was heated and cured to form a protective layer 4 having a thickness of 10 μm. The thus obtained optical disk was coated with the above Example 1.
EFM signals were recorded in the same manner. Then, this optical disk was used in the same way as that used in Example 1 above.
When played on a CD player, the reflectance of the optical disc was 72%, I ₁₁ /I _tpp was 0.63, and I ₃ /I _tpp was 0.33. Therefore, the optical disc according to this embodiment also satisfies the CD standard like the above embodiment. Example 4 0.65 g of 1,1'-dibutyl 3,3,5, 1,1'-dibutyl 3,3,5,
A solution of 3′,3′,5′-hexamethylindodicarbocyanine fluoroborate in 10 c.c. of isopropyl alcohol solvent was applied by spin coating to form a light absorption layer 2 with a thickness of 0.11 μm. .
The complex refractive index of this light absorption layer 2 is n _abs = 2.7, k _abs
=0.05, and ρ=n _abs d _abs /λ=0.38. A Cu film with a thickness of 500 angstroms was formed on the entire surface of this disk by sputtering method.
A light reflecting layer 3 was formed. The complex refractive index of this light reflecting layer 3 is n _ref =0.12 and k _ref =4.89. Furthermore, an ultraviolet curable resin is spin-coated on the light reflective layer 3 and cured by irradiating ultraviolet rays to a thickness of 10 μm.
A protective layer 4 of m was formed. The thus obtained optical disk was coated with the above Example 1.
EFM signals were recorded in the same manner. Then, this optical disk was used in the same way as that used in Example 1 above.
When played back on a CD player, the reflectance of the optical disc was 75%, I ₁₁ /I _tpp was 0.65, and I ₃ /I _tpp was 0.35. Therefore, the optical disc according to this embodiment also
Like the above embodiment, it satisfies the CD standard. Example 5 The same transparent substrate 1 as used in Example 1 above
0.60 g of 1,1'-diethyl 3,3,3',3'-tetramethyl 5,5'-dit-
Butyl indodicarbocyanine perchlorate dissolved in 10 c.c. of methyl isobutyl ketone solvent was applied by spin coating to a film thickness of 0.12 μm.
A light absorption layer 2 of m was formed. The complex refractive index of this light absorption layer 2 is n _abs = 2.65, k _abs = 0.06, and ρ =
n _abs d _abs /λ=0.41. An Ag film with a thickness of 450 angstroms was formed on the entire surface of this disk by sputtering method.
A light reflecting layer 3 was formed. The complex refractive index of this light reflecting layer 3 is n _ref =0.086 and k _ref =5.29. moreover,
An ultraviolet curable resin is spin-coated on this light reflective layer 3, and is cured by irradiating ultraviolet rays to increase the thickness.
A protective layer 4 of 10 μm was formed. The thus obtained optical disk was coated with the above Example 1.
EFM signals were recorded in the same manner. Then, this optical disk was used in the same way as that used in Example 1 above.
When played back on a CD player, the reflectance of the optical disc was 73%, I ₁₁ /I _tpp was 0.64, and I ₃ /I _tpp was 0.33. Therefore, the optical disc according to this embodiment also
Like the above embodiment, it satisfies the CD standard. Example 6 The same transparent substrate 1 as used in Example 1 above
0.65 g of 1,1'-dipropyl 3,3,3',3'-tetramethyl 5,5'-bis(dimethanolamino)indodicarbocyanine perchlorate as a cyanine dye was added to diacetone alcohol solvent 10
A solution dissolved in cc was applied by spin coating to form a light absorption layer 2 with a thickness of 0.10 μm. The complex refractive index of this light absorption layer 2 is n _abs = 2.75, k _abs =
0.08, and ρ=n _abs d _abs /λ=0.35. An Al film with a thickness of 500 angstroms was formed on the entire surface of this disk by sputtering method.
A light reflecting layer 3 was formed. The complex refractive index of this light reflecting layer 3 is n _ref =1.87 and k _ref =7.0. Furthermore, an ultraviolet curable resin is spin-coated on this light reflective layer 3, and is cured by irradiating ultraviolet rays to increase the thickness.
A protective layer 4 of 10 μm was formed. The thus obtained optical disk was coated with the above Example 1.
EFM signals were recorded in the same manner. Then, this optical disk was used in the same way as that used in Example 1 above.
When played back on a CD player, the reflectance of the optical disc was 72%, I ₁₁ /I _tpp was 0.61, and I ₃ /I _tpp was 0.31. Therefore, the optical disc according to this embodiment also
Like the above embodiment, it satisfies the CD standard. Example 7 The same transparent substrate 1 as used in Example 1 above
0.65 g of 1,1'-dipropyl 3,3,3',3'-tetramethyl 5,5'-bis(1-phenyl-2-ethylene) dicarbocyanine toluenesulfonate as a cyanine dye was added to isopropyl alcohol. A solution dissolved in 10 c.c. of solvent was applied by spin coating to form a light absorption layer 2 with a thickness of 0.13 μm. The complex refractive index of this light absorption layer 2 is n _abs =2.7,
k _abs =0.04, and ρ = n _abs d _abs /λ = 0.45. An Ag film with a thickness of 600 angstroms was formed on the entire surface of this disk by sputtering method.
A light reflecting layer 3 was formed. The complex refractive index of this light reflecting layer 3 is n _ref =0.086 and k _rfe =5.29. moreover,
An ultraviolet curable resin is spin-coated on this light reflective layer 3, and is cured by irradiating it with ultraviolet rays to increase the thickness.
A protective layer 4 of 10 μm was formed. The thus obtained optical disk was coated with the above Example 1.
EFM signals were recorded in the same manner. Then, this optical disk was used in the same way as that used in Example 1 above.
When played back on a CD player, the reflectance of the optical disc was 72%, I ₁₁ /I _tpp was 0.62, and I ₃ /I _tpp was 0.33. Therefore, the optical disc according to this embodiment also
Like the above embodiment, it satisfies the CD standard. Example 8 0.5 g of 1,1' diethyl 3,3,3',
3'Tetramethyl 5,5'diethoxyindodicarbocyanine iodide dissolved in 10 c.c. of isopropyl alcohol solvent was applied by spin coating to form a light absorption layer 2 consisting of a dye film with a film thickness of 0.10 μm. was formed. The complex refractive index of this light absorption layer 2 is
nabs=2.65, kabs=0.05, and ρ=nabs・
dabs/λ=0.34. A Cu film with a thickness of 500 angstroms was formed on the entire surface of this disk by sputtering method.
A reflective layer 3 was formed. The complex refractive index of this reflective layer 3 is nerf=0.12 and kref=4.89. Furthermore, an ultraviolet curable resin is spin-coated on this reflective layer 3 and cured by irradiating ultraviolet rays to a thickness of 10 μm.
A protective layer of m was formed. The optical disc thus obtained is coated with a wavelength of 780 nm.
A semiconductor laser with a linear velocity of 1.2 m/sec and a recording power of
It was irradiated with 6.0 mW and the EFM signal was recorded. and,
When this optical disc was played back using the same CD player used in Example 1, the reflectance was 71%.
I11/Itop was 0.63 and I3/Itop was 0.33. Therefore, the optical disc according to this embodiment also satisfies the CD standard like the above embodiment. Example 9 A 1.2 mm thick spiral pregroup with a width of 0.5 μm, a depth of 0.15 μm, and a pitch of 1.6 μm was formed.
A polycarbonate substrate 1 having an outer diameter of 120 mmφ and an inner diameter of 15 mmφ was molded by injection molding. As an organic dye for forming the light absorption layer 2,
0.050g of the same dye as in Example 1 and nitrocellulose
0.005 g was dissolved in 10 c.c. of isopropyl alcohol solvent, and this was applied onto the above substrate 1 by a spun coating method to form a light absorption layer 2 consisting of a dye film with an average thickness of 0.025 μm. The complex refractive index of this light absorption layer 2 is nabs=2.0 and kabs=0.04. The wavelength λ of the semiconductor laser of the reproduction light is 780 nm,
ρ=nabs・dabs/λ=0.064. A film with a thickness of 500 mm is coated on the entire surface of this disk using a vapor deposition method.
A reflective layer 3 was formed by depositing an angstrom-thick Au film. The complex refractive index of this reflective layer 3 is nref=
0.16, kref=4.67. Furthermore, this reflective layer 3
An ultraviolet curable resin was spin-coated thereon and cured by irradiating ultraviolet rays to form a protective layer 4 with a thickness of 10 μm. The thus obtained optical disk was subjected to EFM using a semiconductor laser with a wavelength of 780 nm as in Example 1.
The signal was recorded and played back on a commercially available CD player. The reflectance of this optical disc is 82%, and I11/Itop is
0.60, I3/Itop is 0.31, and the optical disc according to this example satisfies the CD standard. Example 10 1,1'dibutyl 3,3,3',3'tetramethyl5,6,5 was used as an organic dye to form a light absorption layer 2 on a polycarbonate substrate 1 molded in the same manner as in Example 1. ',6' Tetramethoxy indodicarbocyanine perchlorate 0.050 g and nitrocellose 0.005 g were dissolved in 10 c.c. of diacetone alcohol solvent, and this was applied onto the above substrate 1 by spin coating method, and the film thickness was determined. A light absorption layer 2 consisting of a 0.020 μm dye film was formed. The complex refractive index of this light absorption layer 2 is nabs=2.9 and kabs=0.29. The wavelength of the semiconductor laser for reproduction light is λ = 780 nm, and ρ =
nabs・dabs/λ=0.051. A film with a thickness of 500 mm is coated on the entire surface of this disk using a vapor deposition method.
A reflective layer 3 is formed by depositing an angstrom-thick Au film, and then an ultraviolet curable resin is spin-coated on the reflective layer 3 and cured by irradiating ultraviolet rays to form a protective layer 4 with a thickness of 10 μm. was formed. The optical disc thus obtained was subjected to EFM using a semiconductor laser with a wavelength of 780 nm as in Example 1.
The signal was recorded and played back on a commercially available CD player. The reflectance of this optical disc is 70%, and I11/Itop is
0.61, I3/Itop is 0.30, and the optical disc according to this example satisfies the CD standard. Example 11 A spiral pre-group with a width of 0.7 μm, a depth of 0.07 μm, and a pitch of 1.6 μm was formed, and the thickness was 1.2 mm.
A polycarbonate substrate 1 having an outer diameter of 120 mmφ and an inner diameter of 15 mmφ was molded by injection molding. As an organic dye for forming the light absorption layer 2,
0.8 g of the same dye as in Example 1 was dissolved in 10 c.c. of acetylacetone solvent, and this was applied onto the above substrate 1 by spin coating to form a light absorption layer 2 consisting of a dye film with a thickness of 0.17 μm. Formed. The complex refractive index of this light absorption layer 2 is nabs=2.7 and kabs=0.05. The wavelength λ of the semiconductor laser of the reproduction light is 780 nm, and ρ=nabs·dabs/λ=0.59. A film with a thickness of 500 mm is coated on the entire surface of this disk using a vapor deposition method.
A reflective layer 3 is formed by depositing an angstrom-thick Au film, and then an ultraviolet curable resin is spin-coated on the reflective layer 3 and cured by irradiating ultraviolet rays to form a protective layer 4 with a thickness of 10 μm. was formed. The optical disc thus obtained was subjected to EFM using a semiconductor laser with a wavelength of 780 nm as in Example 1.
The signal was recorded and played back on a commercially available CD player. The reflectance of this optical disc is 70%, and I11/Itop is
0.62, I3/Itop is 0.32, and the optical disc according to this example satisfies the CD standard. Example 12 A 1.2 mm thick spiral pre-group with a width of 0.5 μm, a depth of 0.18 μm, and a pitch of 1.6 μm was formed.
A polycarbonate substrate 1 having an outer diameter of 120 mmφ and an inner diameter of 15 mmφ was molded by injection molding. As an organic dye for forming the light absorption layer 2,
1,1'diethyl3,3,3',3'tetramethyl5,
0.55 g of 7,5',7'methoxyindodicarbocyanine perchlorate was dissolved in diacetone alcohol solvent.
10 c.c. and coated on the above substrate 1 by spin coating to form a light absorption layer 2 consisting of a dye film with an average thickness of 120 nm. The complex refractive index of this light absorption layer 2 is nabs=2.9 and kabs=0.20. The wavelength of the semiconductor laser for reproduction light is 780 nm, and ρ=nabs·dabs/λ=0.45. A film with a thickness of 500 mm is coated on the entire surface of this disk using a vapor deposition method.
A reflective layer 3 is formed by depositing an angstrom-thick Au film, and then an ultraviolet curable resin is spin-coated on the reflective layer 3 and cured by irradiating ultraviolet rays to form a protective layer 4 with a thickness of 10 μm. was formed. The optical disc thus obtained was subjected to EFM using a semiconductor laser with a wavelength of 780 nm as in Example 1.
The signal was recorded and played back on a commercially available CD player. The reflectance of this optical disc is 70%, and I11/Itop is
0.70, I3/Itop is 0.40, and the optical disc according to this example satisfies the CD standard. [Effects of the Invention] As explained above, according to the present invention, a high reflectance can be obtained by focusing on the imaginary part kabs of the complex refractive index of the light absorption layer of an optical information recording medium and setting it to 0.3 or less. This makes it possible to provide an optical information recording medium that can Furthermore, ρ=nabs・nabs・in the light absorption layer
By setting dabs/λ to 0.05≦ρ≦0.6, CD
Recording and playback that satisfies the standard is now possible, and specifically, I11/Itop, which is indicated as the modulation degree in the CD standard, is now possible.
It is possible to provide an optical information recording medium that can obtain a reproduced waveform with I3/Itop of 0.6 or more and 0.3 to 0.7.

[Brief explanation of drawings]

FIG. 1 is a schematic half-sectional perspective view showing an example of the structure of the optical information recording medium of the present invention, and FIG. 2 is an enlarged partial cross-sectional view taken along the track of the optical information recording medium before recording in FIG. 3 is an enlarged partial sectional view taken along the track of the optical information recording medium after recording shown in FIG. 1, and FIG. 4 is a case in which an intermediate layer is provided in the optical information recording medium of the present invention. FIG. 5 is an enlarged partial cross-sectional view of the optical information recording medium of the present invention before recording, and FIG. 6 is an enlarged partial cross-sectional view of the optical information recording medium of the present invention after recording. FIG. 7 is an enlarged partial cross-sectional view before recording when an intermediate layer is provided, and FIG. 7 is a partial cross-sectional view after recording when an intermediate layer is provided in the optical information recording medium of the present invention and there are two deformable layers. The enlarged view, Figure 8, shows ρ=nabs・dabs/λ of the light absorption layer of the optical information recording medium.
Figure 9 is a graph showing an example of the relationship between reflectance and reflectance.
Figure 10, a graph showing the relationship between the imaginary part kabs of the complex refractive index of the light absorption layer and the reflectance, shows ρ=nabs・
It is a graph showing the region where the reflectance satisfies the CD standard in dabs/λ and kabs. 1...Substrate, 2...Light absorption layer, 3...Reflection layer,
4...Hard layer, 5...Pits, 6...Intermediate layer, 7
...Laser light, 8...Pick up.

Claims (1)

[Claims] 1. A light-absorbing layer is provided on a light-transmitting substrate, either directly or through another layer, and a reflective layer is provided on the light-absorbing layer, either directly or through another layer. In an optical information recording medium, the light absorption layer consists of a layer containing a cyanine dye, and the imaginary part of its complex refractive index kabs
0.3 or less, and the light reflecting layer is formed of a metal film. 2 In claim 1 above, the light absorption layer has a real part nabs of its complex refractive index and a film thickness dabs.
and the wavelength λ of the reproduction light, ρ=nabs・
An optical information recording medium characterized in that dabs/λ satisfies 0.05≦ρ≦0.6. 3. The optical information recording medium according to claim 1 or 2, wherein the cyanine dye forming the light absorption layer is indodicarbocyanine. 4. The optical information recording medium according to any one of claims 1 to 3 above, wherein the cyanine dye forming the light absorption layer is a compound represented by the following general formula. (However, A and A' are atomic groups forming a benzene ring or substituted benzene ring, or forming a naphthalene ring or substituted naphthalene ring,
They may be of the same species or different species. B is pentamethine (-CH=CH-CH=CH
-CH=), and each hydrogen atom may be substituted with a halogen atom, an alkyl group, an alkoxy group, a diphenylamino group, etc., or may have a substituted or unsubstituted cyclic side chain spanning multiple carbon atoms. good. R ₁ and R ₁ ′ are substituted or unsubstituted alkyl groups,
Alkoxy group, alkylhydroxy group, aralkyl group, alkenyl group, alkylcarboxyl group,
It is an alkylsulfonyl group or an alkylcarboxyl group or an alkylsulfonyl group bonded to an alkali metal ion or an alkyl group, and they may be the same or different. X ₁ ^- is a halogen atom, perchloric acid, borofluoric acid, benzenesulfonic acid, toluenesulfonic acid,
It represents an anion such as alkylsulfonic acid, benzenecarboxylic acid, alkylcarboxylic acid or trifluoromethylcarboxylic acid, and when R ₁ and R ₁ ' have a group bonded to an alkali metal ion, X ₁ ^- is not present. It's okay. )