JP2002245678A - Optical information recording medium and method for recording and reproducing in this recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid such a phenomenon that a tracking error signal from a pregroove or the information signal from a prepit greatly vary according to the coating conditions of dyes and to optimize the tracking error signal from the pregroove for a write-once-read-many optical information recording medium or to optimize both of signals from the pit in a ROM part and the tracking error signal from the pregroove at a time for a hybrid optical information recording medium. SOLUTION: The optical information recording medium used for the method is produced by successively depositing a metal reflection layer 11, a recording layer 12 containing dyes formed by a solvent coating method, and a protective layer 13 on a substrate 10 having guide grooves for tracking with the track pitch P (μm) satisfying 0.6×λ/NA<=P<=0.8×λ/NA, wherein λ is the wavelength (μm) for recording and reproducing and NA is the numerical aperture of the objective lens. The wavelength for recording and reproducing ranges from 400 nm to 550 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium and a recording / reproducing method for the recording medium, and more particularly, to irradiating a light beam with an optical information recording medium such as a transmission coefficient and a reflection coefficient. Optical information recording medium on which information can be recorded, reproduced, and additionally recorded, and the tracking error signal from the pre-groove and the information signal from the pre-pit fluctuate greatly depending on the dye application conditions. The present invention relates to an optical information recording medium having a high density and a narrow track pitch which can be produced at a low cost with high productivity and a method for recording / reproducing the recording medium.

[0002]

2. Description of the Related Art At present, a CD-ROM has completely established itself as one of data storage media for personal computers, and a CD-ROM drive is being standardly installed in most personal computers. Compatibility with CD-ROM media is one of the differentiating requirements as removable media.
It is one. CD- is a CD-based write-once media
R has a reflectance of 60 to 70% or more in an unrecorded state,
In addition, it is possible to perform recording in which the reflectance is lowered by recording, so that information recorded on a CD-R can be read by a CD-ROM drive (compatibility). Conventionally, this CD-R was also used for professional purposes such as authoring, but from the viewpoint of drive price reduction and high compatibility,
In recent years, demands for data distribution media, software production media, and data storage media similar to general removable media have been greatly increased.

Conventionally, a CD1 having a capacity of 640 MB
A 74-minute digital video can be stored even on a single disc (video CD). This video CD uses a video compression and encoding technique called MPEG1, but the playback time is short and the screen resolution of the video is half that of a normal television image. Since the CD standard has been born as a digital storage medium for music, it is not suitable for digital video storage because of its capacity and data transfer speed. What was developed there was a DVD, which enables a single movie to be reproduced at the same size as a CD with the quality of a television, and the next generation DVD is expected as a key technology for multimedia. As with the above-mentioned CD, development of a write-once medium (DVD-R) in which a user can write information only once, a rewritable medium (DVD-RAM), and the like are being advanced. . In these CD-R and DVD-R media, basically, a dye is formed on a substrate having a guide groove by a spin coating method, and a gold reflection layer is provided thereon, which is an essential configuration for compatibility. It has become.

There is an inevitable tendency to increase the capacity, and as a method of physically increasing the recording density (reducing the diameter of the recording mark: shortening the laser wavelength, super-resolution technology, narrow track, etc.). Pitching), compression, and coding techniques are becoming more efficient. As for the development of the coating type high density media, it is possible to respond to the shortening of the wavelength by newly developing a recording material that is sensitive to the wavelength. appear.
Conventionally, tracking of a medium uses an optical path difference between a land portion and a groove portion of a substrate guide groove. In the case of a coating type medium (for example, DVD-R media), an effective land portion and groove portion formed at the dye / metal reflection layer interface when a dye coating film is provided on a substrate and a metal reflection layer is further provided thereon. And the optical path difference between them. At this time, the dye film thickness is large on the groove of the substrate and thin on the land portion, and the optical path difference formed on the dye surface after the dye application becomes smaller (the groove is filled) than the optical path difference of the substrate alone. . This effect is greater as the track pitch becomes narrower. In a narrow track pitch medium aiming at increasing the capacity, the groove cannot be filled by the conventional coating method, an effective optical path difference cannot be obtained, and tracking cannot be performed.

Conventionally, in the case of a write-once optical disk using a dye, a recording material containing the dye is formed by a spin coating method on a substrate in which a tracking groove (pre-groove) or the like is previously cut. The pregroove carved on the substrate is extremely important for positioning of recording and reproduction of the laser spot, and it is necessary to sufficiently output a so-called tracking error signal required for the positioning. However, in a write-once CD-R, DVD-R, or the like, the tracking error signal is determined not only by the reflectance of the interface between the substrate and the dye but mainly by the reflectance of the interface between the dye and the gold reflective layer. Sometimes optimized groove shapes such as pre-pits and pre-grooves have little meaning. That is, it is very important how the dye is filled in the groove formed on the substrate.

The degree of filling of the dye in the groove varies not only in the type of the dye itself but also in the case of a mixture, the composition, the solvent dissolving the dye and its composition, the spin coat pattern, the temperature and humidity, etc. Therefore, it is difficult to control it, which adversely affects the production cost and significantly reduces the research and development efficiency. In addition, in the conventional method, the degree of filling of the dye in the groove is determined by using a solvent or application conditions,
Since the optimization is performed in accordance with the coating environment, there is also a disadvantage that the tracking error signal and the like in the disk, particularly in the inner circumference and the outer circumference, vary greatly.
Further, the shape of the pre-groove is trapezoidal, but the surface shape in a state where the dye is buried in the pre-groove is V-shaped or U-shaped.
It is shaped like a letter. Therefore, it also causes an increase in jitter and crosstalk.

As a solution to this problem, a method of depositing a dye may be considered. However, considering that the merit of the organic material lies in its film forming property (productivity) and that spin coating is possible, This is not practical because the range of material selection is limited. In recent years, the demand for so-called hybrid media, which has both a ROM section in which information is written in advance and a write-once section in which a user can write information, has been increasing in recent years, and this demand is increasing as the capacity of a disk increases. It is thought that it will be noticeable. In this hybrid media, as shown in FIG. 1, a ROM portion and a write-once portion are separated, but the depth of the pre-pit portion required for the ROM portion is different from the depth of the pre-groove required for the write-on portion. .

Generally, the pre-pit depth is set to λ / 4n so that the degree of modulation is maximum, and the pre-groove depth is set to λ / 8n so that the tracking error signal is maximum (where λ is set to λ / 8n). The recording / reproducing wavelength, n is the refractive index of the incident medium, usually the substrate). As described above, the pit depth of the ROM portion is different from the pre-groove depth of the write-on portion, and when a dye film is formed on this substrate by spin coating, the dye flowing into the pre-pits of the ROM portion and the pre-groove portion of the write-on portion are different. The amount of dye flowing into the groove is different, ROM
There is a high risk that the degree of embedding of the dye in the pre-pit of the portion and the degree of embedding of the dye in the pre-groove of the additional recording portion are completely different. Hybrid media is provided with a gold reflective film after dye application, but the signal from the prepits in the ROM section and the tracking error signal from the pregroove in the write-on section are mainly determined at the interface between the dye and the gold reflective film. The degree of dye embedding is extremely important. In this hybrid media, it is extremely difficult to optimize both the signal from the pre-pits in the ROM section and the tracking error signal from the pre-groove in the write-once section by the spin coating method. Therefore, at the time of producing the hybrid media, the ROM part and the write-once part are separately applied, or the stamper is optimized in consideration of the difference in the degree of embedding of the dye in the pre-pit of the ROM part and the pre-groove of the write-on part, It was necessary to adjust the type and composition of the solvent for dissolving the dye, the coating pattern, and the like.

However, in this method, the degree of embedding of the dye in the pre-pits of the ROM portion and the pre-grooves of the write-on portion is completely changed by the working environment such as temperature and humidity, the minute impurities mixed in the solvent, and the composition fluctuation. More often. Furthermore, hybrid CD-R, hybrid DV
In the research and development stage of DR, it is necessary to evaluate the disk characteristics of many types of dyes. However, the viscosity, optimum solvent, and composition of the dye solution differ for each dye, so the optimum stamper changes each time the dye changes. It is necessary to search for the optimum solvent, composition, and application pattern conditions each time the dye is changed using a substrate obtained from the same stamper.

Even if the optimum solvent, composition, and coating conditions are set, if the design of the stamper is different, that is, if the width or groove depth of the prepit or pregroove is changed, the previous optimum solvent, composition, In addition, the application conditions may become meaningless. For this reason, the efficiency of research and development is extremely low, and the productivity is greatly reduced.

Further, in the conventional layer structure and manufacturing method,
From the viewpoints described above, it has been difficult to provide a ROM section and a write-once section at arbitrary locations on a disk, or to have a plurality of ROM sections or write-once sections on a disk. In addition, since the signal characteristics of the optical information recording medium change depending on how the dye is applied by the spin coating method as described above, the change in the film forming conditions of the dye is within a range allowed by shortening the recording / reproducing wavelength. Becomes severe. As a result, it is expected that the shortening of the wavelength will significantly reduce productivity and cost. The substrate used for DVD has a thickness of 0.6.
mm, and is bent by its own weight, so that it is manufactured using a method of bonding two thin substrates. For example, FIG.
As shown in FIG. 1, in the case of a read-only DVD disk, there are a single-layer disk (SL) and a double-layer disk (DL) (Reference material: No. 199 Opplus E, June 1996, p.
80 etc.).

[0012]

SUMMARY OF THE INVENTION The present invention solves such a conventional problem and avoids a situation in which the tracking error signal from the pre-groove and the information signal from the pre-pit greatly vary depending on the dye application conditions. In the case of a write-once optical information recording medium, a tracking error signal from a pre-groove is used. In the case of a hybrid optical information recording medium, a signal from a pit in a ROM section and a tracking error signal from a pre-groove in a write-once section are recorded. Both are optimized at the same time, and this optimization eliminates the phenomenon that varies greatly depending on the dye application conditions, resulting in high productivity and cost reduction,
Further, it is an object of the present invention to provide an optical information recording medium capable of greatly improving the efficiency of research and development and responding to high density by shortening the wavelength of laser light, and a recording and reproducing method for the recording medium. Is the subject.

[0013]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive studies focusing on a track pitch and a method of forming a recording layer containing a dye, and as a result, have specified a track pitch. The present inventors have found that the above problems can be solved by forming the recording layer by a solvent coating method, and have completed the present invention based on this finding.

That is, according to the present invention, first, the following equation (1): 0.6 × λ / NA ≦ P ≦ 0.8 × λ / NA (1) The pitch (μm), λ indicates the recording / reproducing wavelength (μm), and NA indicates the numerical aperture of the objective lens.] A metal reflective layer, a solvent, A recording / reproducing wavelength of 400 to 550 n, wherein a recording layer containing a dye formed by a coating method and a protective layer are sequentially laminated.
Second, an optical information recording medium is provided, and secondly, a ROM portion in which information is recorded in advance on a single substrate, and a write-once area where P is expressed by the above formula (1) A metal reflective layer, a recording layer containing a dye formed by a solvent coating method, and a protective layer are sequentially laminated on a substrate having a portion provided with a guide groove for tracking composed of in advance. An optical information recording medium having a recording / reproducing wavelength of 400 to 550 nm is provided.

According to the present invention, thirdly, information recording and reproduction are performed from the protective layer side.
And a recording / reproducing method for the optical information recording medium.
According to the present invention, fourthly, a metal reflective layer and a dye formed by a solvent coating method are provided on a first substrate having a guide groove for tracking consisting of P represented by the above formula (1). A recording / reproducing wavelength of 400 to 550n, wherein a recording layer, an adhesive layer and a second substrate are sequentially laminated.
Fifth, an optical information recording medium is provided. Fifth, on a single substrate, a ROM portion in which information is recorded in advance, and a write-once area, which is represented by P A metal reflective layer, a recording layer containing a dye formed by a solvent coating method, an adhesive layer, and a second substrate are sequentially formed on a first substrate having a portion provided with a guide groove for tracking composed of in advance. Recording / reproducing wavelength 400 characterized by being laminated
An optical information recording medium of 〜550 nm is provided. The fourth and fifth inventions include an optical information recording medium in which the adhesive layer is made of a hot-melt adhesive material and an optical information recording medium in which the adhesive layer is made of an ultraviolet-curable adhesive material.

According to the present invention, sixthly, there is provided the fourth and fifth optical information recording / reproducing methods for recording and reproducing information from the second substrate. .

[0017]

A feature of the present invention is that the amount of reflected light from the pre-pit signal of the ROM section and the amount of tracking error signal from the pre-groove of the additional recording section are determined on the boundary surface having the largest reflection coefficient (that is, the boundary surface has the largest reflection coefficient). It is determined by the amount of phase change between a recorded portion and a non-recorded portion or a place where a pre-groove is and is not present at a boundary surface having a large reflection coefficient), a substrate, a recording layer containing a dye, a reflective layer, a protective layer, and the like. When the conventional layer constituting material is used, the fact that the boundary surface having the largest reflection coefficient is the interface between the dye and the gold reflective layer is used. Therefore, if the interface between the dye and the gold reflective layer can have a clear, phase change due to unevenness, it is not necessary to consider the degree of filling of the grooves in the pre-pit and pre-groove portions of the dye. .

More specifically, as described in the prior art, in the conventional reproducing method, a portion where a prepit or a pregroove is carved and a portion where a prepit or a pregroove is not formed are caused by interference of reflected light. Recording information and a tracking error signal are generated. FIGS. 3A to 3E show the state of the interference, and the depressions in the drawings are prepits or pregrooves. In the case of a CD-ROM or DVD-ROM without a dye recording layer, the shape and depth of the prepits or pregrooves engraved on the substrate are directly reflected on the reproduction signal and the tracking error signal. This is because the reflection of incident light mainly depends on the interface between the substrate and the reflective layer. In a CD-R, DVD-R or hybrid CD-R or hybrid DVD-R provided with a dye recording layer, the reflection of incident light is mainly determined by the interface between the dye-containing recording layer and the reflective layer. Therefore, the interference of the reflected light at the part where the pre-pit or pre-groove is carved and at the part where the pre-pit or pre-groove is not present,
The degree of filling of the dye into the grooves of the prepits and pregrooves is not dependent on the groove shape and depth of the prepits and pregrooves provided in advance on the substrate, and is governed by the filling shape.

Next, the layer constitution, recording and reproduction of the present invention will be described.
4 (a) to 4 (e). In the present invention, in order to stably obtain signals necessary for reproducing and tracking recorded information, it is sufficient that main reflection can be obtained from the interface of prepits or pregrooves that have been previously engraved on the substrate. To achieve this, a reflective layer and a recording layer containing a dye are basically formed on a substrate on which prepits and pregrooves have been cut in advance, and recording and reproduction are performed from the recording layer side. .

According to the present invention, the main reflection from the prepits and pregrooves is at the interface between the dye layer and the reflective layer, and the interface between the dye layer and the reflective layer depends on the shape of the reflective layer. The shape of the pre-pits or pre-grooves after the layer is provided almost directly reflects the shape of the pre-pits or pre-grooves on the substrate. That is, the reproduction signal and the tracking error signal do not largely depend on the shape of the dye provided on the reflective layer, in other words, the degree of filling of the dye in the grooves of the pre-pits or pre-grooves provided with the reflective layer, and the shape of the dye. It is possible to do.

In order to obtain an appropriate reproduction signal or tracking error signal, it is sufficient that main reflection of incident light occurs at a pre-pit or pre-groove interface provided on the substrate. It has the following problems. (1) In order to maintain the interface shape of the prepits and pregrooves, the thickness of the recording layer containing the dye may be made extremely thin.
It cannot be used as a write-once type. (2) Conversely, if the recording layer has a certain thickness or more in order to obtain a good recording contrast, the dye is buried in the prepits and pregrooves more than necessary, and the reproduction signal and the tracking error signal are weakened. (The phase difference changes greatly.) (3) In the hybrid type having both the ROM section and the write-on section, since the pre-pits and the pre-grooves have different optimum groove depths, the degree of embedding of the dye in the pre-pits and the pre-grooves by spin coating is controlled so that both become optimum. It is extremely difficult to do. Therefore, it is necessary to use a substrate whose groove shape and depth have been optimized in advance in consideration of the degree of filling of the dye in the groove, film formation conditions, and the like.

On the other hand, in the present invention, the degree of embedding of the dye is as follows:
Since the influence on the reproduction signal and the tracking error signal can be reduced, the allowable width of the dye film thickness is widened, and even in the hybrid type, the filling degree of the dye is determined by the pre-pit portion of the ROM portion and the pre-recording portion of the write-on portion. Even if the groove portions are completely different, the possibility of causing a problem is reduced. As a result, the problems (1) to (3), which have conventionally been problems, can be solved at once.

According to the conventional configuration (FIG. 3), the phase difference between the portion where the pre-groove or the pre-pit is present and the portion where the pre-groove or the pre-pit is not present is given by (4π _{/ λ) {(n 0 d} 1 + n 1 d 2 -n 1 (d 1 + d 2 -d 3)} = (4π / λ) {(n 0 -n 1) d 1 + n 1 d 3} ‥ ...... In the formula (2), λ is the recording / reproducing wavelength, n ₀ is the complex refractive index of the substrate, n ₁ is the complex refractive index of the dye-containing recording layer,
d ₁ , d ₂ and d ₃ are the values shown in FIG. ]

On the other hand, according to the configuration of the present invention (FIG. 4), the phase difference between the portion where the pre-groove or the pre-pit exists and the portion where the pre-groove or the pre-pit does not exist is based on the pre-groove or the pre-pit portion. , (4π / λ) {(n ₁ d ₂ − (n ₀ d ₃ + n ₁ (d ₁ + d ₂ −d ₃ )))} = (4π / λ) ｛(n ₁ −n ₀ ) d ₃ −n ₁ d ₁ ｝ ‥‥‥‥‥ (3) [where λ is the recording / reproducing wavelength, n ₀ is the complex refractive index of the recording layer containing the dye, and n ₁ is the complex refractive index of the adhesive layer. , D ₁ , d ₂ , d ₃ : values shown in FIG. 4.]

By the way, when pre-pits and pre-grooves are optimized, that is, when the stamper is manufactured, d ₁ is set. In the conventional configuration, the phase difference is smaller than d ₁ as can be seen from the above equation (2). Rather, it can be seen that d ₃ , that is, the degree of embedding of the dye in the pre-pits or pre-grooves greatly depends on [d ₁ and d ₃ are obviously n ₁ > (n ₁ −n ₀ ). is there〕. On the other hand, in the present invention,
As seen from the above equation (3), the phase difference is substantially determined by d ₁ , and it is understood that d ₃ , that is, the degree of embedding of the dye layer in the pre-pits or pre-grooves is not so affected. In other words, in the conventional method, no matter how much the pre-pits and pre-grooves are optimized at the time of stamper production, the characteristics vary greatly depending on the application state of the dye, and the design of the pre-pits and pre-grooves is repeated many times.
Further, it is necessary to optimize the coating conditions.

In the present invention, the pre-pit or pre-groove depth set at the time of stamper production is utilized as it is even if the disc is formed. FIGS. 5 and 6 visualize this. However, in the calculation, n ₀ = 1.5,
n ₁ = 2.7-i0.05, the recording and reproducing wavelength 550 (nm)
And

FIG. 5 shows a conventional method, and FIG. 6 shows the present invention.
Pre-groove or pre-pit on the horizontal axis
Groove depth d₁, The vertical axis is the pre-groove or pre-pit
D representing the degree of embedding of the dye and the dye layer in the grooves of_ThreeAnd
Pre-groove or pre-pit when both change
Pre-groove or pre-pit
It is a result of calculating a phase difference of a portion that does not exist. As a result
Therefore, the conventional method (FIG. 5) uses the pre-groove or pre-pip
G groove depth d ₁Together with the phase difference dependence on
D representing the degree of filling of the dye in the groove of the groove or prepit
_ThreeIt can be seen that the contribution rate of the to the phase difference is high. On the other hand,
In the method according to Akira, the pre-groove or pre-pit
D indicating the degree of embedding of the dye layer in the groove of_ThreeTo the phase difference
It can be seen that the contribution rate has dropped significantly.

By the way, in FIGS. 5 and 6, the upper left in the figures is an unrealistic combination of d ₁ and d ₃ . this is,
As shown in FIGS. 7 and 8, FIG. 7 shows the ROM state at d ₁ = d ₃ , and this situation is the limit that can be formed by actual spin coating. ₃ <cases as d ₁ next 8 is because not without realistic. Therefore, the desired phase difference,
For example, in order to obtain a phase difference of π (or -π) in the pre-pit portion and π / 2 (or -π / 2) in the pre-groove portion, d ₁ and d ₃ are restricted. That is, due to the nature of the spin coating method, d _{3p in} the pre-pit portion having a deep groove is always larger than d _{3g in the} pre-groove portion having a shallow groove. Thereby, in the hybrid optical information recording medium, even if the groove depth d ₁ of the pre-pit portion and the pre-groove portion is optimally set, d _3g of the pre-groove portion and d _3p of the pre-pit portion are formed by spin coating. Technique is required. This situation is shown in FIGS.
In the conventional method, for example, the groove depth of the pre-groove is set to 110 (nm), and d ₃ at that time is set to 20 (n).
m), in the pre-pit section, d ₃ is 20
(Nm) or more, the groove depth of the pre-pit portion needs to be about 200 (nm).

In the present invention, the groove depth of the pregroove is set to 40
(Nm), and if d ₃ at that time is 20 (nm), the depth of the pre-pit portion is 70 even if the condition that d ₃ is 20 (nm) or more is imposed in the pre-pit portion.
(Nm) or more, and a desired phase difference can be satisfied with a shallow groove, which is advantageous for high density. Figure 1
1 and 12 show d ₃ given to the phase difference between the present invention and the conventional method.
And corresponds to the groove filling situation in FIGS. As described above, in the conventional method (FIG. 11), the degree of filling of the groove in the pre-groove or the pre-pit causes
Desired for to achieve the phase difference must be largely changed the initial groove depth d _1, filled if not adjust or dyes and the type of solvent degree of dye, when changing the composition ratio or the like, etc. Must design a new stamper.

On the other hand, in the method of the present invention, even if the degree of filling of the groove in the pre-groove or the pre-pit slightly changes, the groove depth for achieving the desired phase difference does not change significantly. Even if the type and composition ratio are changed, the phase difference can be adjusted by the application conditions. This effect is more pronounced in high-density narrow track pitch media. As the track pitch becomes narrower, the difference (d ₃ -d ₁ ) in the thickness of the dye layer formed by the solvent coating method on the groove unevenness becomes larger. as a result,
In the conventional R structure, as the track pitch becomes narrower, the tracking signal decreases sharply, and tracking becomes impossible. Also, with the same effect with the conventional hybrid structure, the stamper is optimized by taking into account the difference in the degree of embedding of the pre-pit and the additional recording portion in the pre-groove, and adjustment of the type and composition of the solvent that dissolves the dye, application pattern, etc. It is more limited, and the narrower the track pitch, the more difficult it becomes to realize.

On the other hand, in the structure of the present invention, the
Difference in dye layer thickness on unevenness (d_Three-d ₁) Has little effect
For high density, narrow track pitch media
It is possible. Next-generation optical disk
As the wavelength, a blue laser (oscillation wavelength 400 nm to 550)
nm) is expected to be used. Laser beam diameter (λ
/ NA: λ is the recording / reproducing wavelength (μm), NA is the objective lens
The relationship between the track pitch and the track pitch
Exceeds 0.8 times the laser beam diameter, radial recording
Redundancy of density has increased, and high density cannot be achieved.
When the laser beam is 0.6 times or less, crosstalk and
The error rate increases. The media structure of the present invention
In the conventional structure, an oscillation wavelength of 400 nm to 550
The track pitch for recording / reproducing using a
Dye coating type with 0.6 to 0.8 times the diameter of the laser beam
It will be applied to optical recording media.

Hereinafter, the recording layer will be described. Examples of the dye include a polymethine dye, a squarylium-based, a pyrylium-based, a porphyrin-based, a porphyrazine-based, an azo-based, an azomethine-based, a dye, and a metal complex compound thereof,
UV absorbers and the like are mentioned, and these dyes may be used alone or in combination of two or more. Also,
Metals, metal compounds such as In, T
e, Bi, Al, Be, TeO ₂ , SnO, As, Cd
And the like can be used in the form of dispersion mixing or lamination.

Further, various materials such as an ionomer resin, a polyamide resin, a vinyl resin, a natural polymer, silicone, a liquid rubber, or a silane coupling agent are dispersed and mixed in the above dye. It may be used, and may 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 properties. When using a coating method, the above dyes and the like are dissolved in an organic solvent, and spraying, roller coating, dipping or spin coating is performed by a conventional coating method.From the nature of the present invention, spin coating is most preferable. .

Examples of the organic solvent 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; sulfoxides such as dimethylsulfoxide; ethers such as tetrahydrofuran, dioxane, diethylether and ethylene glycol monomethylether; and esters such as methyl acetate and ethyl acetate. , Chloroform, methylene chloride, dichloroethane, carbon tetrachloride, trichloroethane, etc., aliphatic halogenated carbons, benzene, xylene, monochlorobenzene, dichlorobenzene, etc., aromatics such as methoxyethanol, ethoxyethanol, etc., hexane, pentane ,
Hydrocarbons such as cyclohexane and methylcyclohexane can be used. The thickness of the recording layer is 100 to
1 .mu.m, preferably 200.degree.

Next, the substrate will be described. As a necessary characteristic of the substrate, the substrate must be transparent to the laser beam used only when recording and reproduction are performed from the substrate side, and need not be transparent when recording and reproduction are performed from the recording layer side. Therefore, in the present invention, when only one substrate is used, the substrate does not need to be transparent. When two substrates are used in a sandwich form, if only the second substrate is transparent, the first substrate is used. Both transparent and opaque. As the substrate material, for example, plastic such as polyester, acrylic resin, polyamide, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, polyimide, or glass, ceramic, metal, or the like can be used. Note that when only one layer of the substrate is used or when two substrates are used in a sandwich shape, the surface of the first substrate is
It is necessary that a guide groove and a guide pit for tracking, and a preformat such as an address signal be formed.

Further, the intermediate layer will be described. Layers provided other than the substrate, the recording layer, the reflective layer, and the protective layer, including the undercoat layer and the like, are herein referred to as intermediate layers. This intermediate layer comprises (a) improved adhesion, (b) a barrier against water or gas, (c) improved storage stability of the recording layer, (d) improved reflectance, and (e) substrate from solvent. And protection of the recording layer,
(F) It is used for the purpose of forming guide grooves, guide pits, preformats and the like.

For the purpose of (a), various polymer materials such as ionomer resin, polyamide resin, vinyl resin, natural resin, natural polymer, silicone, liquid rubber, etc. A ring agent can be used. For the purposes of (b) and (c), besides the above-mentioned polymer materials, inorganic compounds such as SiO ₂ , M
gF ₂ , SiO, TiO ₂ , ZnO, TiN, SiN and other metals or metalloids such as Zn, Cu, Ni, Cr, G
e, Se, Au, Ag, Al and the like can be used.
For the purpose of (d), a metal such as Al,
Ag or the like, or an organic thin film having a metallic luster, such as a methine dye or a xanthene dye, can be used.
For the purposes of (e) and (f), an ultraviolet curable resin,
A thermosetting resin, a thermoplastic resin, or the like can be used. The thickness of the intermediate layer is 0.01 to 30 μm, preferably 0.1 to 30 μm.
It is suitably from 05 to 10 μm.

Next, the protective layer and the hard coat layer on the substrate surface will be described. The protective layer or the substrate surface hard coat layer protects (a) the recording layer (reflection / absorption layer) from scratches, dust, dirt, etc., (b) improves the 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 above-mentioned intermediate layer can be used. Further, as an inorganic material, Si
O, SiO _{2 and the} like can also be used.
Polymethyl acrylate, polycarbonate, epoxy resin, polystyrene, polyester resin, vinyl resin,
Thermosoftening and heat-melting resins such as cellulose, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, 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 substrate surface hard coat layer is 0.01 to 30 μm, preferably 0.05 to 1 μm.
0 μm is appropriate. In the present invention, the intermediate layer, the protective layer and the substrate surface hard coat layer, like the recording layer, a stabilizer, a dispersant, a flame retardant, a lubricant, an antistatic agent,
Surfactants, plasticizers and the like can be contained.

Next, the metal reflection layer will be described. The reflective layer is made of a metal, semi-metal, or the like that is highly resistant to corrosion and that can provide a high reflectance by itself, and is made of Au, Ag,
Examples thereof include Cu, Cr, Ni, and Al, with Au and Al being preferred. These metals and metalloids may be used alone or as two or more alloys. Further, a dielectric multilayer film may be used. Examples of the film forming method include vapor deposition and sputtering, and the film thickness is 50 to 30.
00 °, preferably 100 to 1000 °.

Finally, the adhesive layer will be described. A transparent polymer compound can be used for the adhesive layer. In the present invention, particularly preferred is a hot melt type (hot melt type) adhesive or an ultraviolet curable type adhesive. An ultraviolet-curable adhesive is an adhesive that starts radical polymerization by ultraviolet irradiation and cures. The composition generally comprises an acrylic oligomer, an acrylic monomer, a photopolymerization initiator, and a polymerization inhibitor. The oligomer is a polyester-based, polyurethane-based, epoxy-based acrylate, or the like. As the agent, benzophenone, benzoin ether or the like can be used.

In a hot melt adhesive, a liquid adhesive is cured by volatilization or reaction of a solvent, and an adhesive force is developed. On the other hand, an ordinary temperature solid thermoplastic resin develops an adhesive force by a physical change of heat melting and cooling and solidification. Is what you do. As the hot melt adhesive, EVA, polyester, polyamide, polyurethane and the like can be used.

[0042]

The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the present invention.

Examples 1, 2, 3, 4 As shown in FIG. 13, the depth d (Å) and the half width w (μ
m), on a 0.6 mm thick injection molded polycarbonate substrate (first substrate) 10 having guide grooves (spiral direction is opposite to the conventional direction) with a track pitch p (μm), a reflection layer of 2000 mm of gold is formed by sputtering. 11 were provided. Then, a 1,1,2,2-tetrafluoropropanol solution of the following compound 1 was spinner-coated to obtain a second recording material.
Organic dye layer 1 is formed to a thickness such that the reflectance from the substrate side becomes 70%.
2 was formed. Further, a smooth injection-molded polycarbonate substrate having a thickness of 0.6 mm (the second substrate 17 was adhered thereto using a hot melt adhesive 15 thereon) to produce a recording medium.

Embedded image

Embodiments 5, 6, 7, 8 As shown in FIG. 13, the depth d (Å) and the half width w (μ
m), on a 0.6 mm thick injection-molded polycarbonate substrate (first substrate) 10 having a guide groove (spiral direction is opposite to that of the conventional one) with a track pitch p (μm), a reflective layer 11 of 2000 mm of gold is formed by sputtering. Was provided. A 1,1,2,2-tetrafluoropropanol solution of the compound 1 was spin-coated thereon, and the organic dye layer was formed to a thickness such that the reflectance from the second substrate side when the recording material was obtained was 70%. No. 12 was formed. Furthermore, a protective layer 16 having a thickness of 5 μm was provided thereon with a hexane solution of petroleum resin, and a 0.6 m thick
m smooth injection molded polycarbonate substrate (second substrate)
17 was adhered using an acrylic photopolymer 15 to prepare a recording medium.

Comparative Examples 1, 2, 3, 4, 5, 6 Depth d (Å), half width w (μm), track pitch p
A 1,1,2,2-tetrafluoropropanol solution of the above compound 1 was spin-coated on a 0.6 mm-thick injection-molded polycarbonate substrate (first substrate) having a (μm) guide groove, and a recording medium was prepared. The organic dye layer was formed so as to have a reflectance of 70% when the organic dye layer was formed. Next, a reflective layer of 2000 mm of gold was provided by a sputtering method, and a smooth injection-molded polycarbonate substrate (second substrate) having a thickness of 0.6 mm was further adhered thereon with an acrylic photopolymer to form a recording medium.

Comparative Example 7 A recording medium was manufactured in the same manner as in Example 1 except that only the track pitch was changed. For the recording medium prepared in this manner, the semiconductor laser light having the oscillation wavelength λ (nm) and the beam diameter r (μm) was used.
In the comparative example, a tracking error (TE) signal was observed from the first substrate side from the substrate side. Table 1 shows these conditions and results.
Shown in

[0047]

[Table 1] The evaluation levels of the TE signal are as follows. ：: Level that can be sufficiently detected as a servo signal. Δ: Level that can be detected as a servo signal. X: Level that cannot be detected as a servo signal.

[0048]

According to the present invention, the phenomenon that the tracking error signal from the pre-groove or the information signal from the pre-pit greatly varies depending on the application condition of the dye, is avoided.
In the case of a write-once optical information recording medium, a tracking error signal from a pre-groove is used. In the case of a hybrid optical information recording medium, both a signal from a pit in a ROM section and a tracking error signal from a pre-groove in a write-once section are used. At the same time, and eliminates the phenomenon that this optimization varies greatly depending on the dye application conditions, resulting in high productivity, cost reduction, and significant improvement in research and development efficiency. In addition, an optical information recording medium and a recording / reproducing method for the recording medium capable of coping with high density by shortening the wavelength are provided, which greatly contributes to the optical information recording field.

[Brief description of the drawings]

FIG. 1 is a diagram showing a surface of an optical information recording medium having a ROM section and a write-once section in one optical information recording medium.

FIG. 2 shows a conventional disk (CD-ROM, DVD-RO)
M) It is a figure which shows the kind of structure.

FIG. 3 is a diagram illustrating a state of occurrence of a phase difference in a conventional structure.

FIG. 4 is a diagram for explaining a state of occurrence of a phase difference in the structure of the present invention.

FIG. 5 is a diagram showing an influence of a groove depth of a prepit or pregroove and a degree of filling of a groove of a dye on a phase difference in a conventional structure.

FIG. 6 is a diagram showing an influence of a groove depth of a prepit or a pregroove and a degree of filling of a groove of a dye on a phase difference in the structure of the present invention.

FIG. 7 is a diagram illustrating an example of how a dye is embedded in a prepit or a pregroove.

FIG. 8 is a diagram showing an example of the degree of embedding of a dye in a prepit or a pregroove.

FIG. 9 is a diagram showing an example of allowable conditions of a groove depth of a prepit or a pregroove and a degree of groove filling of a dye in a hybrid type having a conventional structure.

FIG. 10 is a diagram showing an example of allowable conditions of a groove depth of a prepit or a pregroove and a degree of filling of a groove of a dye in a hybrid type structure of the present invention.

FIG. 11 is a diagram showing an influence of a groove filling state of a dye on a phase difference in a conventional structure.

FIG. 12 is a diagram showing the influence of the degree of filling of the grooves of the dye on the phase difference in the structure of the present invention.

FIG. 13 is a diagram showing a layer configuration used in an example of the present invention.

[Explanation of symbols]

 Reference Signs List 10 first substrate 11 reflective layer 12 dye-containing recording layer 13 protective layer (or adhesive layer and substrate) 14 protective layer 15 adhesive layer 16 intermediate layer 17 second substrate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 7/004 G11B 7/004 Z (72) Inventor Tatsuya Tomura 1-3-6 Nakamagome, Ota-ku, Tokyo No. Ricoh Co., Ltd. (72) Inventor Yasunobu Ueno 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Yasuhiro Higashi 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. F term (reference) 5D029 JA04 JB09 JB47 MA18 RA02 RA29 RA30 RA45 RA48 WB11 5D090 AA01 BB03 CC01 DD01 EE02 FF04 FF08 GG07 KK06

Claims (8)

[Claims] 1. Expression (1): 0.6 × λ / NA ≦ P ≦ 0.8 × λ / NA (1) [In Expression (1), P represents a track pitch (μm), and λ represents recording / reproduction. The wavelength (μm), NA indicates the numerical aperture of the objective lens], a metal reflective layer and a dye formed by a solvent coating method on a substrate having a guide groove for tracking composed of P. A recording / reproducing wavelength of 400 to 550n, wherein a recording layer and a protective layer are sequentially laminated.
m optical information recording medium. 2. A ROM section in which information is recorded in advance on one substrate, and an area where additional writing is possible, wherein
A metal reflective layer, on a substrate having a portion provided with a guide groove for tracking consisting of P represented by
An optical information recording medium having a recording / reproducing wavelength of 400 to 550 nm, wherein a recording layer containing a dye formed by a solvent coating method and a protective layer are sequentially laminated. 3. The recording / reproducing method for an optical information recording medium according to claim 1, wherein recording and reproduction of information are performed from a protective layer side. 4. A metal reflective layer, a recording layer containing a dye formed by a solvent coating method, on a first substrate having a guide groove for tracking consisting of P represented by the above formula (1), An optical information recording medium having a recording / reproducing wavelength of 400 to 550 nm, wherein an adhesive layer and a second substrate are sequentially laminated. 5. A ROM section in which information is recorded in advance on a single board, and an area where additional writing is possible, wherein
A metal reflective layer, a recording layer containing a dye formed by a solvent coating method, an adhesive layer, and a first layer having a portion provided with a guide groove for tracking consisting of P represented by An optical information recording medium having a recording / reproducing wavelength of 400 to 550 nm, wherein two substrates are sequentially laminated. 6. The optical information recording medium according to claim 4, wherein the adhesive layer is made of a hot-melt type adhesive material. 7. The optical information recording medium according to claim 4, wherein the adhesive layer is made of an ultraviolet-curable adhesive material. 8. The recording / reproducing method for an optical information recording medium according to claim 4, wherein recording and reproduction of information are performed from the second substrate.