JPH02139733A - Optical recording medium and its recording method - Google Patents

Abstract

PURPOSE:To form such pits from which output signals with modulation factors conforming to the CD standards can be obtained by specifying the Rockwell hardness of the part in a light-transmitting substrate adjacent to a light absorbing layer. CONSTITUTION:A hard layer 4 is provided on the side facing to a reflecting layer 3 of the light-absorbing layer 2 and may be used as a protective layer. The hardness of the layer 4 may be same as that of the part in the light- transmissing substrate 1 adjacent to the light-absorbing layer 2, or preferably more harder. By this method, waveforms of reproducing signals show little distortion. For example, the hardness is preferably equal to or over M90 Rockwell hardness by ASTM D785, or regarded as H or harder by pencil scratching test. Moreover, the layer 4 is preferably composed of such material having excellent shock resistance. Thus, reproduction signals with >=70% reflectance conforming to the CD standards can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial 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, and a recording method thereof.

[Prior art] So-called writable optical information recording media that can record data by irradiation with laser light account for 18%
It has a recording layer consisting of a metal layer such as BitMn, a dye layer such as cyanine, merocyanine, phthalocyanine, etc., and the pits are formed by deforming, sublimating, evaporating, or modifying the recording layer by irradiation with laser light. form and record data. In optical information recording media having this recording layer, a void is 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 substrate 1 which has the above-mentioned light-transmitting property. When reproducing the recorded data, a laser beam with 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 stored 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 a recording layer as described above, but pits for reproducing recorded data are formed in advance on a transparent substrate by means such as pressing, and Au
A reflective layer made of a metal film such as AgX Cus A1 is formed, and this is further covered with a protective layer.

The most typical type of ROM-type optical information recording medium is the compact disc, or so-called CD, which is widely used in the audio and information processing sectors. standardized as a standard,
Playback devices conforming to this are extremely widespread as compact disc players (CD players).

[Problems to be Solved by the Invention] Since the above-mentioned writable optical information recording medium is a recording means that uses the same laser beam as a CD, upon reproduction,
It is strongly desired to comply with the already widely used CD.

However, in the writable optical information recording medium such as the above-mentioned air sandwich structure, recording is performed by forming pits in the recording layer instead of on the substrate.
To facilitate the formation of pits in this recording layer,
Because it has a void layer, etc., the thickness (meaning the thickness from the front surface to the back surface, hereinafter referred to as "total thickness") becomes thicker. Therefore, it is difficult to satisfy the total thickness specified in the CD standard. In addition, optical information recording media in which a recording layer and a reflective layer are provided on a substrate have already been proposed, but an optical information recording medium that can obtain a reproduced signal that satisfies the modulation degree required by the CD standard has not yet been proposed. It had not been done.

The present invention has been made to solve the above conventional problems, and has a total thickness within the range specified by the CD standard, a high reflectance of 70% or more during data reproduction, and a CD
It is an object of the present invention to provide an optical information recording medium in which pits can be formed so as to obtain an output signal with a modulation degree that complies with the D standard, and an optical information recording method suitable for the optical information recording medium.

[Means for Solving the Problems] In other words, the gist of the means adopted in the present invention to achieve the above object is to provide a light absorbing device that absorbs laser light directly or through another layer on a transparent substrate. layer, and a reflective layer and a hard layer are provided directly or through another layer on the light absorbing layer, and the Rockwell hardness of the portion in contact with the light absorbing layer that is closer to the transparent substrate than the light absorbing layer. ASTM D785
An optical information recording medium and an optical information recording method using the optical information recording medium are characterized in that the optical information recording medium is M90 or less.

Furthermore, in the optical information recording medium, ρ=nabs-dabs/, which is given by the real part nabs of the complex refractive index of the light absorption layer, the film thickness dabs, and the wavelength λ of the reproduction light.
It is desirable that λ satisfies 0.05≦ρ≦0.6 and that the imaginary part k abs of the complex refractive index of the light absorption layer is 0.3 or less.

[Function] According to the optical information recording medium of the present invention, when energy is given to the light absorption layer by irradiating the light absorption layer with laser light from the transparent substrate side, the substrate in contact with the light absorption layer Part of the side part is deformed. At this time, if the hardness of the deformed part is low, the degree of deformation will be greater, so the difference in optical path length between the undeformed area and the deformed area will be large (as a result, the reproduced light during reproduction will be The optical phase difference becomes thicker, and the degree of modulation can be increased.

According to experiments and simulations by the present inventors, in the structure of the optical information recording medium according to the present invention, in order to form bits that can obtain a reproduced signal with a modulation degree that complies with the CD standard, it is necessary to The hardness of the part in contact with the light absorption layer on the substrate side is Rockwell hardness ASTM D78.
It has been found that M90 or less is required for M5.

In Figure 8, a deformable layer is provided on a polycarbonate substrate, a light absorbing layer made of cyanine dye is provided on top of the deformable layer, a gold reflective layer is provided on top of that, and a hard layer of UV curing resin (hardness is In an optical information recording medium equipped with a Rockwell hardness ASTM D785 (M2O), the hardness of the part in contact with the light absorption layer on the transparent substrate side is changed by changing the molecular weight and composition. 3 is a graph showing the relationship between the modulation degree of the reproduction signal and the modulation degree of the reproduced signal.

As can be seen from Figure 8, in order to obtain a modulation degree that satisfies the CD standard, the hardness of the portion of the transparent substrate that is in contact with the light absorption layer must be M90 or less in terms of Rockwell hardness ASTM D785. , preferably M8
5 or less, more preferably M75 or less.

Further, since the optical information recording medium according to the present invention is provided with a hard layer on the reflective layer side, the bits can be formed more clearly on the transparent substrate side than on the reflective layer side. Therefore, since no secondary reflected light is generated due to the deformed portion formed on the reflective layer side, distortion of the reproduced waveform can be suppressed, and the block error rate specified in the CD standard can be suppressed to a low level.

Furthermore, since the optical information recording medium according to the present invention is configured such that the substrate is provided with at least thin films such as a light absorption layer, a reflective layer, and a hard layer, the total thickness can be easily kept within the range specified by the CD standard. Can be done.

The bits formed by the optical information recording medium according to the present invention have the same function as bits formed in advance on the surface of a substrate by means such as pressing, such as CDs. Therefore, C
A reproduced waveform similar to D can be easily obtained.

In addition, the present inventors have found that in order to obtain an output signal with a reflectance of 70% or more that complies with the CD standard with the optical information recording medium according to the present invention, it is necessary to part n abs and its film thickness d abs,
ρ=n abs-d given by the wavelength λ of the reproduction light
Focusing on the fact that abs/λ is a very important parameter, we conducted experiments and simulations and were able to obtain the relationship shown in FIG. 9. Figure 9 shows the real part n abs of the complex refractive index of the light absorption layer of the optical information recording medium, its film thickness d abs, and the reproduction light when a semiconductor laser with a wavelength λ = 780 nm is used as the reproduction light. wavelength λ
7 is a graph showing the relationship between ρ=nabs·dabs/λ given by 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 possible to almost certainly ensure a reflectance of 70% or more. Even in a region where ρ is less than 0.05 or a region where ρ exceeds 0.6, a reflectance of 70% or more may be obtained. However, in the case where ρ is less than 0.05, the film thickness of the light absorption layer dabs must be made considerably thinner, at 0.05 μm or less, so it is difficult to form bits for recording data. This makes it difficult to obtain the reproduced signal as described above. Furthermore, in the case of a region exceeding 0°6, it becomes difficult to control the film thickness to be uniform, resulting in variations in recording characteristics, and I3/Itop may be less than 0.3.
This causes practical problems such as an increase in jitter errors. That is, it can be seen that by setting ρ to 0.05 to 0°6, the reflectance can be increased to 70% or more as specified in the CD standard.

The inventors further studied these results and found that simply setting ρ within the range of 0.05 to 0.6 does not necessarily guarantee a stable output signal as stipulated by the CD standard. imaginary part k ab of the complex refractive index of the light absorption layer
It was found that s is an important parameter. 1st
Figure 0 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.
7 is a graph showing changes in reflectance when the imaginary part kabs is changed from a value close to O to 2.0 while keeping ρ constant.

Looking at this graph, it can be seen that the closer kabs is to 0, the higher the reflectance becomes. Based on the results of experiments and simulations, the present inventors found that ρ was 0605 to 0.
．． In order to maintain a stable high reflectance within the range of Even if ρ is within the range of 0.05 to 0°6, it is difficult to ensure a reflectance of 70% or more when kabs is larger than 0.3.

From these results, results as shown in FIG. 11 can be obtained. Figure 11 shows that C
It is a graph which shows the critical value of the combination based on D standard.

As can be seen from this graph, in order to provide an optical information recording medium that can obtain a recording signal that complies with the CD standard, ρ=nabs-dabs/λ must be 0.05.
It can be seen that it is necessary for the k abs to be in the range of ~0.6 and 0.3 or less.

Furthermore, it is desirable that ρ = n abs - d abs /λ be in the range of 0°05 to 0.6, but in order to obtain a sufficient degree of modulation, it is desirable that it be in the range of 0.1 or more. In order to obtain stable recording characteristics, 0.45±0
．． A range of 1 is most desirable.

On the other hand, if kabs is 0.3 or less, the reflectance improves as it approaches 0. Therefore, this range is most desirable. However, the closer it gets to 0, the worse the recording sensitivity becomes, so it is necessary that it be larger than 0. Specifically, a range of 0.1 or less is desirable, and in reality, 0.0
Around 5 is desirable.

Note that the present invention can be applied even when there is a layer other than the above-mentioned laminate. For example, if a transparent layer (for example, an enhancement layer such as 5i02, an undercoat layer, etc.) is provided between the substrate and the light absorption layer, the above constants may be treated with this layer as part of the substrate. When a layer (for example, adhesive layer, hard layer, etc.) is provided between the light absorption layer and the reflection layer, these layers are considered as the second absorption layer, and 1) = (r
l"d++12" d2)/λ, and in the case of multiple layers, ρ=Σ(rr+・dl)/λ (however, i
is an integer), it can be treated in the same way as above.

Further, when k is not 0, it can be handled in the same way as in the case of a single layer by calculating the average value k from the ratio of film thicknesses as k=Σd++/Σd1.

In addition, if groups are formed on the substrate, da
bs is the average value of the total area of the film thickness of the light absorption layer in the group and the film thickness of the light absorption layer in the land portion.

[Embodiments] Next, embodiments 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 figure, 1 is a light-transmitting substrate, and 2 is a light-absorbing layer formed thereon, which has the function of absorbing irradiated laser light and forming bits in a layer in contact with it. The reference numeral 6 shown only in FIGS. 4 to 7 is an intermediate layer existing between the transparent substrate 1 and the light absorption layer 20, and when this exists, energy is given to the light absorption layer. As shown in Figure 5,
The intermediate layer 6 is deformed and the bit 5 is formed. 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 of the substrate 1 is deformed and a bit 5 is formed there. Further, 3 indicates a reflective layer formed thereon, and 4 indicates a protective layer provided outside thereof.

2, 4, and 6 show the state before recording with laser light, and FIGS. 3, 5, and 7 show the state after recording with laser light, that is, when bit 5 is formed. This diagram schematically shows the state in which

The material of the transparent substrate 1 has a refractive index of 1 with respect to laser light.
．． A resin with high transparency in the range of 4 to 1.6 and excellent impact resistance is desirable. Specific examples include polycarbonate, acrylic, etc., but are not limited to these.

The substrate 1 is molded using the above-mentioned materials, for example, by injection molding or the like.

A pre-group may be formed in a spiral shape on such a substrate l. The pre-group may be under any conditions that can be considered normally, but
The depth is preferably 50 to 250 nm, more preferably 80 to 180 nm.

The pre-group 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.

The intermediate layer 6 in contact with the light absorption layer 2 can be made of polycarbonate, acrylic, epoxy, etc., and its hardness can be adjusted by changing the molecular weight and composition. As already explained, there may be no intermediate layer 6, and the light-transmitting substrate 1 may be in direct contact with the light absorption layer 2, or there may be a plurality of intermediate layers 6.

Between the substrate 1 and the light absorption layer 1, in addition to the intermediate layer 6, 5
It may be coated with a solvent-resistant layer or an enhancement layer such as i02.

The material of the light-absorbing layer 2 is preferably a light-absorbing organic dye.
Examples include cyanine dyes, polymethine dyes, triarylmethane dyes, biryllium dyes, phenanthrene dyes, tetradehydrocholine dyes, triarylamine dyes, squarylium dyes, croconic methine dyes, etc.
The present invention is not limited to these materials (although the effects of the present invention can also be obtained with recording materials such as known low-melting point metals).

Note that the light absorption layer 2 may contain other dyes and resins (for example, thermoplastic resins such as nitrocellulose, thermoplastic elastomers).
, liquid rubber, etc. may be included.

The light absorption layer 2 is a light-transmitting substrate on which pre-groups are formed by dissolving the above-mentioned dye and any additives in a known organic solvent (for example, ketone alcohol, acetylacetone, methyl cellosolve, toluene, etc.), or Furthermore, it is formed by coating other layers on the substrate l.

Formation methods in this case include vapor deposition method, LB method, spin code method, etc.; Law is preferable.

The reflective layer 3 is preferably a metal film, and is formed of, for example, gold, silver, aluminum, or an alloy containing these by means such as vapor deposition or sputtering.

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. Further, other layers such as an oxidation-resistant layer for preventing oxidation of the reflective layer may be interposed.

Note that it is desirable that the layer closer to the reflective layer 3 than the light absorbing layer 2 has a higher thermal deformation temperature and higher hardness than the layer closer to the substrate 1. This configuration is effective in reducing the block error rate of recording signals.

The hard layer 4 is a layer provided closer to the reflective layer 3 than the light absorbing layer 2, and may also function as a protective layer. The hardness may be the same as that of the part of the light-transmitting substrate 1 that is in contact with the light absorption layer 2, but it is preferable that the material has a higher hardness than this, so that the reproduced waveform will not be distorted. It becomes difficult. Specifically, Rockwell hardness ASTM
Even if it is D75 or higher and the pencil hardness is HB or higher,
It is possible to obtain the effects of the present invention depending on the combination with other conditions. However, considering that the block error rate BLER is good (Rockwell hardness ASTM
It is desirable to have M90 or higher in D785 and H or higher in pencil hardness. Furthermore, it is desirable that the hard layer 4 be formed of a resin with excellent impact resistance. For example, it is formed by applying an ultraviolet curable resin using a spin code method and curing it by irradiating it with ultraviolet rays.

As schematically shown in FIGS. 3, 5, and 7, the optical information recording medium on which data is recorded by irradiation with laser light has a surface area in contact with the light absorption layer 2 on the substrate 1 side. The bit 5 which is convex toward the light absorption layer 2 side can be confirmed, and it is known that the reproduced waveform of the bit 5 formed in this way is similar to that of a CD.

Reproduction of the recorded signal is performed by irradiating a reading laser from the substrate side and reading the optical phase difference between the reflected light from the bit portion and the reflected light from the portion other than the bit.

In this example, only the case where the light absorption layer 2 is formed on almost the entire surface of the light-transmitting substrate l is described, 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 bits for signal reproduction are previously formed. For example, a bit for signal reproduction is previously formed in a standby on a portion of the surface of the transparent substrate 1 that will become the ROM region, and the light absorption layer 2 is formed by coating only the outer region with the above-mentioned material. In this way, the light absorption layer 2 is formed only on a part of the transparent substrate near the outer periphery, and this area is used as a recordable area, and a ROM area is formed on the inner periphery side. By providing a ROM area in this manner, certain ROM information and personal additional information can be stored in one storage 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 optical information recording medium.

A specific example of this configuration will be described below.

(Example 1) Width 0. 8μrrh depth 0. 08μff
h Thickness: 1.6 mm with spiral pre-groups 8 formed at a pitch of 1.6 μm. 2mrrh outer diameter 120mm
φ1 A polycarbonate substrate 1 having an inner diameter of 15 mmφ was molded by injection molding. The Rockwell hardness ASTM D785 of this polycarbonate substrate 1 was equivalent to the M75 pencil hardness HB, and the heat distortion temperature ASTM D848 was 4.6 kg/cm2.121°C.

As a dye for forming the light absorption layer 2, (1,6
5 g of 1,1' dibutyl3. 3. 3'3'tetramethyl4. 5. 4', 5' dibenzoindodicarbocyanine verchlorate (manufactured by Nippon Kanko Shiki Kenkyushin, product number NK3219) was dissolved in diacetone alcohol solvent 10c.
c and coated on the surface of the above-mentioned substrate 1 by a spin code method to form a light-absorbing layer 2 made of a photosensitive dye film with a thickness of 130 nm. ρ=nabsdabs/λ given by the real part nabs of the complex refractive index of the light absorption layer 2, its film thickness dabs, and the wavelength λ of the reproduction light is 0.45, and the above complex refractive index imaginary part k ab
s was 0.05.

Next, an Au film with a thickness of 80 nm was formed on the entire surface of the disk with a diameter of 45 to 118 mm by sputtering to form a reflective layer 3. Furthermore, this reflective layer 3
An ultraviolet curable resin was spin-coded on top of the resin and cured by irradiating it with ultraviolet rays to form a protective layer 4 having a thickness of 10 μm. Rockwell hardness AST after curing of this protective layer 4
M D785 is M2O, heat distortion temperature ASTM
D648 is 4. E3kg/cm2.135°C.

A semiconductor laser with a wavelength of 780 nm was applied to the optical disc thus obtained at a linear velocity of 1.2 m/5eas and a recording power of 6.0 m.
It was irradiated with W and the EFM signal was recorded. Thereafter, this optical disc is inserted into a commercially available CD player (Aurex
When reproduced with V73 (wavelength of reproduction light λ=780 nm), the reflectance of the semiconductor laser was 72%, I++/It. .

is 0. 68, Ia/It6e was 0.35, and block error rate BLER was 1.2X10-2. Further, the total thickness of this optical disc was 1.2 mm.

According to the CD standard, the total thickness is 1. 1-1. 5mrrh reflectance is 70% or more, I eye/l10o is o, e or more, I
3/It. , is defined as 0.3 to 0.7, and the block error rate BLER is defined as 3×10 −2 or less, and the optical disc according to this embodiment satisfies these standards.

Furthermore, when the protective layer 4 and light reflective layer 3 of the optical disc after recording were peeled off and the surface of the light absorbing layer 2 was observed, minute linear irregularities, which appeared to be the outlines of pits, were observed. Further, when the light absorption layer 2 was cleaned and removed with a solvent and the surface of the substrate 1 was observed, it was confirmed that optically modified pits 5 were formed thereon.

The layer structure of this optical disk is schematically shown in FIG. 2, and the state after optical recording is schematically shown in FIG.

(Example 2) Same as Example 1 above except that a hard layer with a thickness of 1100 nm was provided between the light absorption layer 2 and the light reflection layer 3 by spin-coding epoxy resin. An optical disc was produced in the same manner. The Rockwell hardness ASTM D785 after curing of this epoxy resin is M2O, and the heat distortion temperature ASTM D648 is 4.6 kg.
/ crn 2.135°C.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When played back on a commercially available CD player, the reflectance and playback signal output characteristics of the semiconductor laser were the same as in Example 1, and the block error rate BLER was 3.0.
It was XIO-3. Also, the total thickness of the optical disc is 1.
It was 2 mm.

Furthermore, when the surface of the substrate 1 of the optical disk after recording was observed in the same manner as in Example 1, it was confirmed that pits 5 were formed there.

(Example 3) In the above Example 1, instead of the epoxy resin formed on the upper surface of the light absorption layer 2 between the light absorption layer 2 and the light reflection layer 3, a hard silicone acrylic resin with a film thickness of 1100 nm was used. A layer made of epoxy resin is provided on the upper surface of this hard layer.
Optical discs were manufactured in the same manner as in Example 1 above, except that the binding layers of %m were formed by the spin cord method. The Rockwell hardness ASTM D785 after curing of the silicone acrylic resin scrap is Mloo, and the heat distortion temperature ASTM D648 is 4.6 kg/
c~2,100°C.

EFM signals were recorded on the thus obtained optical disc at a recording power of 7.0 mW in the same manner as in Example 1, and then this optical disc was placed in the same CD player as in Example 1 (Aurex XR-V73, with a reproduction light beam of Wavelength 780n
When reproduced with m, the reflectance of the semiconductor laser was 75%,
■++/I't. , is 0.83, I3/It. . is 0.
35, block error rate) BLER is 2.5X10-
It was 3. Also, the total thickness of this optical disc is 1.2m.
It was m.

Furthermore, when the surface of the substrate 1 of the optical disc after recording was observed in the same manner as in Example 1, it was confirmed that pits 5 were formed there.

(Example 4) In the above Example 1, the light reflection layer 3 is placed on the light absorption layer 2.
An alloy film of gold and antimony in a ratio of 9=1 was formed by vacuum evaporation, and on this reflective layer 3, an ultraviolet curable resin was formed via a 20% binder layer made of epoxy resin. An optical disc was manufactured in the same manner as in Example 1 above, except that the protective layer 4 was formed. The light reflecting layer 3 has a pencil hardness of rHJ or higher.

EFM signals were recorded on the optical disc thus obtained at a recording power of 6.2 mW in the same manner as in Example 1, and then this optical disc was played back using the same CD player as in Example 1. rate is 72%, 1
0/Ito.

is 0. 62, I3/I too was 0.32, and block error rate BLER was 3.5 x 10-3. Further, the total thickness of this optical disc was 1.2 mm.

Furthermore, when the surface of the substrate l of the optical disk after recording was observed in the same manner as in Example 1, it was confirmed that bits 5 were formed thereon.

(Example 5) In Example 1 above, an ultraviolet curable hard coat resin was spin-coded on the light incident side of the polycarbonate substrate 1, a substrate protective layer with a thickness of 1 μm was provided, and a light The absorption layer 2 is formed, and on this light absorption layer 2, a light reflection layer 3 of 3= of iridium and gold is formed.
An optical disc was manufactured in the same manner as in Example 1 above, except that the alloy film having a ratio of 1:1 was formed by the sputtering method. The light reflecting layer 3 has a pencil hardness of "5".
It has a hardness of H" or higher.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When reproduced using the same CD player as in Example 1, the reflectance of the semiconductor laser was 70%, I/It. , is 0.6
2, I3/1,. , was 0.37, and the block error rate BLER was 3.7X10-3. Further, the total thickness of this optical disc was 1.2 mm.

Furthermore, when the surface of the substrate l of the optical disc after recording was observed in the same manner as in Example 1, it was confirmed that bits 5 were formed there (Example 6). The reflective layer 3 was formed of a silver film with a thickness of 60% m, and a silicone hard coating agent was spin-coded on it, and this was heated and cured to a thickness of 3 μm.
An optical disc was manufactured in the same manner as in Example 1 above, except that the hard protective layer 4 of m was formed. Note that the protective layer 4
has a pencil hardness equal to or higher than rHBJ.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When reproduced using the same CD player as in Example 1, the reflectance of the semiconductor laser was 71%, I++/It. , is 0. 6
3, I3/It. .

is 0.35, block error rate BLER is 2.8X
It was 10-3. Also, the total thickness of this optical disc is 1
．． It was 2 mm.

Furthermore, when the surface of the substrate l of the optical disc after recording was observed in the same manner as in Example 1, it was confirmed that bits 5 were formed there (Example 7). A silicone hard coat is applied on the light reflection layer 3 made by vacuum vaporizing a 50 nm thick Au film through a 30% m binder layer formed by spin-coding a polysulfide-added epoxy resin diluted with dicrycidyl ether. An optical disc was manufactured in the same manner as in Example 1, except that the hard protective layer 4 having a thickness of 3 μm was formed by spin-coding the agent and heating and curing it.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When played back using the same CD player as in Example 1, the reflectance of the semiconductor laser was 72%, and it was 72%. , is 0.6
5, I3/Ito.

is 0.35, block error rate) BLER is 2.5X
The total thickness of this optical disc was 10-".
．． It was 2 mm.

Furthermore, when the surface of the substrate 1 of the optical disk after recording was observed in the same manner as in Example 1, it was confirmed that pits 5 were formed there.

(Example 8) In the above Example 1, Ll' dibutyl 3.3.3'
, 3'tetramethyl5.5'diethoxyindodicarbocyanine perchlorate was used to form the light absorption layer 2, and on the light reflection layer 3, 110 made of epoxy resin was formed.
An optical disc was manufactured in the same manner as in Example 1, except that a 0n hard layer was formed, and a 10 μm thick ultraviolet curable resin was further formed on the hard layer to form the protective layer 4. Note that ρ=n abs-d abs/λ of this light absorption layer 2 is 0
．． 44, and kabs was 0.03.

EFM signals were recorded on the thus obtained optical disc in the same manner as in Example 1, and then this optical disc was
When played back using the same CD player as in Example 1, the reflectance of the semiconductor laser was 74% and I++/Itop was 0.
．． 88, Is/It. .

is 0.34, block error rate BLER is 8.3X
It was 10-3. Also, the total thickness of this optical disc is 1
．． It was 2 mm.

Furthermore, when the surface of the substrate 1 of the optical disc after recording was observed in the same manner as in Example 1, it was confirmed that pits 5 were formed there.

(Example 9) An acrylic resin dissolved in diisobutyl ketone was spin-coded onto the surface of the same polycarbonate substrate 1 used in Example 1 to form an intermediate layer 6 with a thickness of 40 nm. Rockwell hardness of this intermediate layer 6 ASTM
D785 is M85, heat distortion temperature ASTM D
848 was 4.6 kg/cm2.100°C.

0.6g as an organic dye for forming the light absorption layer 2
1.1' dipropyl, 3. 3. 3'3'tetramethyl 5.5' dimethoxyindodicarbocyanine iodide was dissolved in isopropyl alcohol solvent 10c.
c and coated on the surface of the above-mentioned substrate 1 by a spin code method to form a light-absorbing layer 2 made of a photosensitive dye film with a thickness of 120 nm. ρ” n abs d mbs/ given by the real part n5bs of the complex refractive index of the light absorption layer 2, its film thickness d abs and the wavelength λ of the reproduction light
λ is 0.41, and the imaginary part ka of the above complex refractive index
bs was 0.02.

Next, a silicone acrylic resin dissolved in cyclohexane was spin-coded onto this, and the thickness was IO On ms, pencil hardness was 2H, and heat distortion temperature was ASTMD648, 4.8 kg.
/cm2.A silicon acrylic resin layer is formed at 120°C, and a 50 nm thick A layer is deposited on it by sputtering.
A reflective layer 3 was formed by depositing a u film. Furthermore, an ultraviolet curable resin was spin-coded on the reflective layer 3 and cured by irradiating ultraviolet rays to form a protective layer 4 having a thickness of 10 μm. Rockwell hardness A after curing of this protective layer 4
STM D785 is M2O, heat distortion temperature AST
MD648 is 4.13kg/cm2.135°C
Met.

A semiconductor laser with a wavelength of 780 nm was applied to the optical disc thus obtained at a linear velocity of 1.2 m/5ect and a recording power of 7.5 m.
It was irradiated with W and the EFM signal was recorded. Thereafter, when this optical disc was played back on the same CD player as in Example 1, the reflectance of the semiconductor laser was 74%, the /It0=0°62, and I3/It. , is 0.31. The block error rate BLER was 4.0XIO-3. Further, the total thickness of this optical disc was 1.2 mm.

Furthermore, the protective layer 4 and the light reflection layer 3 of the optical disc after recording are peeled off, the light absorption layer 2 is washed and removed with a solvent,
When the surface of the intermediate layer 6 was observed, it was confirmed that pits 5 were formed there.

(Example 10) In Example 9, except that a silicate layer with a thickness of 0°01 μm was provided on the intermediate layer 6 by spin-coding a silicone coating agent, and the light absorption layer 2 was formed on the silicate layer. An optical disc was manufactured in the same manner as in Example 9 above.

EFM signals were recorded on the thus obtained optical disc at a recording power of 7.8 mW in the same manner as in Example 9, and then this optical disc was played back using the same CD player as in Example 9. rate is 73%, 1
Mouth/I top is 0.62, Ia/It. , is 0.
31. Block error rate BLER is 3.4X10-
It was 3. The total thickness of this optical disc is 162m.
It was m.

Furthermore, when the surface of the intermediate layer 6 of the optical disc after recording was observed in the same manner as in Example 9, it was found that bits 5
was confirmed to be formed.

(Example 11) In the above Example 9, a glass substrate was used as the substrate l, and an isocyanate resin dissolved in a 1=1 solvent of toluene and methyl ethyl ketone was formed on the reflective layer by a spin coding method. An optical disc was manufactured in the same manner as in Example 9 above, except that a 20 nm thick binding layer was formed.

EFM signals were recorded on the thus obtained optical disc at a recording power of 7.2 mW in the same manner as in Example 9, and then this optical disc was played back using the same CD player as in Example 9. rate is 72%, I
z/Itap is 0.65, I3/Itop is 0.33,
The block error rate BLER was 3.6×10 −3 . The total thickness of this optical disc is 1. It was 2 mm.

Furthermore, when the surface of the intermediate layer 6 of the optical disc after recording was observed in the same manner as in Example 9, it was found that bits 5
was confirmed to be formed.

(Example 12) In Example 9 above, a silicate layer having a thickness of 0.01 μm was provided on the intermediate layer 6 by spin-coding a silicone coating agent, and the light absorption layer 2 was formed on the silicate layer, and An optical disc was manufactured in the same manner as in Example 9 above, except that a 20 nm thick binding layer made of polybutadiene by spin coding was formed on the reflective layer.

EFM signals were recorded on the thus obtained optical disc at a recording power of 7.2 mW in the same manner as in Example 9, and then this optical disc was played back using the same CD player as in Example 9. rate is 72%, I
II/'It. .

is 0.6B, Ia/It. , was 0.35, and the block error rate BLER was 3.5X10-3. Also,
The total thickness of this optical disc was 1.2 mm.

Furthermore, when the surface of the intermediate layer 60 of the optical disc after recording was observed in the same manner as in Example 9, it was found that the bit 5
was confirmed to be formed.

(Example 13) In the above Example 9, the thickness of the intermediate layer 6 was set to 20 nm, the silicon acrylic resin layer was not provided, and an alloy film of iridium and gold at a ratio of l: 9 was sputtered as the reflective layer 3. An optical disc was manufactured in the same manner as in Example 9 above, except that it was formed by the method. In addition,
The pencil hardness of the alloy film was 2H.

EFM signals were recorded on the thus obtained optical disc at a recording power of 7.0 mW in the same manner as in Example 9, and then this optical disc was played back using the same CD player as in Example 9. rate is 71%, I
z/Itop is 0.63, Ia/It. , is 0.32,
Block error rate) BLER was 3.3X10-3. The total thickness of this optical disc is 1. It was 2 mm.

Furthermore, when the surface of the intermediate layer 6 of the optical disc after recording was observed in the same manner as in Example 9, it was found that there were bits 5 and 5.
was confirmed to be formed. Since the intermediate layer 6 is thin, the bit 5 is formed to reach the surface of the substrate.

The layer structure of this optical disk is schematically shown in FIG. 6, and the state after optical recording is schematically shown in FIG.

(Example 14) In Example 9, a silicon coating agent was spin-coded on the intermediate layer 6 to form a silicate layer with a thickness of 0.01 μm, and the light absorption layer 2 was formed on the silicon coating agent. An optical disc was manufactured in the same manner as in Example 9, except that the acrylic resin layer was not provided and an alloy film of iridium and gold at a ratio of 1:9 was formed by sputtering as the reflective layer 3.

EFM signals were recorded on the thus obtained optical disc at a recording power of 7.8 mW in the same manner as in Example 9, and then this optical disc was played back using the same CD player as in Example 9. rate is 71%, I
Eye/It0p is 0. 64.1s/l10=0.3
2. Block error rate) BLER is 2.8X10-3
Met. The total thickness of this optical disc is 1. 2m
It was m.

Furthermore, when the surface of the intermediate layer 6 of the optical disc after recording was observed in the same manner as in Example 9, it was found that there were pits.
was confirmed to be formed.

(Example 15) In the above Example 9, the silicon acrylic resin layer is not provided and the reflective layer 3 is made of iridium and gold at l:9.
An alloy film with a ratio of An optical disc was manufactured in the same manner as in Example 9 above, except that the protective layer 4 was formed.

EFM signals were recorded on the optical disk thus obtained at a recording power of 7.4 mW in the same manner as in Example 9, and then this optical disk was played back using the same CD player as in Example 9. rate is 72%, I
++/It. .

is 0.64, I3/Ir. , is 0632, and the block error rate BLER is 4. It was lXl0-3. Also,
The total thickness of this optical disc is 1. It was 2 mm.

Furthermore, when the surface of the intermediate layer 6 of the optical disc after recording was observed in the same manner as in Example 9, it was found that there were pits.
was confirmed to be formed.

(Example 16) In Example 9, the silicon acrylic resin layer was not provided, a copper film with a thickness of 50% m was formed as the reflective layer 3, and bisphenol diluted in diglycidyl ether solvent was used as the protective layer 4. An optical disc was manufactured in the same manner as in Example 9, except that the curable epoxy resin was spin-coded to form an epoxy resin layer with a thickness of 50% m. The protective layer has a Rockwell hardness of AST.
Since MD785 is Mllo, it functions as a hard layer.

EFM signals were recorded on the thus obtained optical disc at a recording power of 7.0 mW in the same manner as in Example 9, and then this optical disc was played back using the same CD player as in Example 9. rate is 75%, I
++/It. .

is 0.64, Is/It. , was 0.33, and the block error rate BLER was 2.9XlO-3. Also,
The total thickness of this optical disc was 1.2 mm.

Furthermore, when the surface of the intermediate layer 6 of the optical disc after recording was observed in the same manner as in Example 9, it was found that there were pits.
was confirmed to be formed.

(Example 17) In the above Example 9, a silicate layer with a thickness of 0.01 μm was provided on the intermediate layer 6 by spin-coding a silicon coating agent, and the light absorption layer 2 was formed on the silicon coating agent. No acrylic resin layer was provided, a copper film with a thickness of 50% m was formed as the reflective layer 3, and as the protective layer 4, a bisphenol curing type epoxy resin diluted with diglycidyl ether solvent was spin-coded to a thickness of 50 nm. An optical disc was manufactured in the same manner as in Example 9 above, except that the epoxy resin layer was formed.

EFM signals were recorded on the thus obtained optical disk at a recording power of 7.0 mW in the same manner as in Example 9, and then this optical disk was played back using the same CD player as in Example 9. rate is 74%, I
z/I top is 0. 64, I a/ I t
OP is 0.33, block error rate) BLER is 3.
It was 5X10-3. The total thickness of this optical disc is 1. It was 2 mm.

Furthermore, when the surface of the intermediate layer 6 of the optical disc after recording was observed in the same manner as in Example 9, it was found that there were pits.
was confirmed to be formed.

(Example 18) In the above Example 9, the silicon acrylic resin layer was not provided, a copper film with a thickness of 50 nm was formed as the reflective layer 3 by vacuum evaporation, and on the reflective layer 6 of toluene and methyl ethyl ketone was added. : The protective layer 4 was formed via a 20 nm thick binder layer formed by spin cording polyvinyl acetate resin dissolved in the solvent of 4, and a bisphenol curing type diluted with diglycidyl ether solvent as the protective layer 4. An optical disc was manufactured in the same manner as in Example 9, except that the epoxy resin was spin-coated to form an epoxy resin layer with a thickness of 50 nm.

EFM signals were recorded on the optical disc thus obtained at a recording power of 7.4 mW in the same manner as in Example 9, and then this optical disc was played back using the same CD player as in Example 9. rate is 74%, 1
Eye/I top is 0.64, I3/It- is 0.3
3. Block error rate BLER is 3.6X10-3
Met. The total thickness of this optical disc is 1. 2m
It was m.

Furthermore, when the surface of the intermediate layer 6 of the optical disc after recording was observed in the same manner as in Example 9, it was found that there were pits.
was confirmed to be formed.

(Example 19) Width 0.5 μnh Depth O-15 μrrh Pitch 1°6
Thickness 1 with μm spiral pregroove formed
．． A polycarbonate x-plate 1 having a diameter of 2 mm5, an outer diameter of 120 mm, and an inner diameter of 15 mm was molded by injection molding.

Example 1 as an organic dye for forming the light absorption layer 2
0.065g of the same dye and 0.005g of nitrocellulose
Dissolve g in 10 cc of isopropyl alcohol solvent,
This was coated on the above substrate l by a spin code method, and a light absorption layer 2 consisting of a dye film with an average thickness of 0.025 μm was formed.
was formed. The complex refractive index of this light absorption layer 2 is nabs
=2. 01kabs=0. It is 04. The wavelength of the semiconductor laser for reproduction light is λ = 780 nm, and ρ = n
abs-d abs /λ=0.064.

A reflective layer 3 was formed by depositing an Au film with a thickness of 500 angstroms on the entire surface of this disk by vapor deposition. The double refractive index of this reflective layer 3 is nref =0. 16,k
ref=4. It is 67.

Further, an ultraviolet curable resin similar to that in Example 1 was spin-coded on the reflective layer 3, and was cured by irradiating ultraviolet rays to form a protective layer 4 with a thickness of 10 μm.

EFM signals were recorded on the optical disc thus obtained using a semiconductor laser with a wavelength of 780 nm, as in Example 1, and reproduced with a commercially available CD player.

The total thickness of this optical disc is 1. 2mrrh Reflectance is 82%, I11/I top is 0.63, I3/
I top is 0.31, and the optical disc according to this example satisfies the CD standard.

(Example 20) As an organic dye for forming a light absorption layer 2 on a polycarbonate substrate l molded in the same manner as in Example 1, 1,1'
Diptyl 3. 3. 3', 3tetramethyl5.
6. 5', 8-Tetramethoxyindodicarbocyanine perchlorate O00050g and nitrocellulose 0.005g were mixed with 10cc of diacetone alcohol solvent.
This was applied onto the above-mentioned substrate 1 by a spin code method to form a light absorption layer 2 made of a dye film with a thickness of 0.020 μm. The complex refractive index of this light absorption layer 2 is 1
abs=2.0, kabs=0.29. The wavelength of the semiconductor laser for reproduction light is λ = 780 nm, and ρ = n
abs-d abs /λ=0°051.

An Au film with a thickness of 500 angstroms was formed on the entire surface of this disk by vapor deposition to form a reflective layer 3, and then an ultraviolet curable resin similar to that in Example 1 was applied by spin cord on the reflective layer 3. This was then cured by irradiation with ultraviolet rays to form a protective layer 4 with a thickness of 10 μm.

EFM signals were recorded on the optical disc thus obtained using a semiconductor laser with a wavelength of 780 nm, as in Example 1, and reproduced with a commercially available CD player.

The total thickness of this optical disc is 1. 2mm5 Reflectance is 70%, I II/I top is 0.64.13/I
top is 0.30, and the optical disc according to this example satisfies the CD standard.

(Example 21) Width 0. 7 μms depth 0.07 u fib Thickness 1.0 mm with spiral pre-groups formed at pitch 1° 6 μm. 2mrrh Outer diameter 120mmφ, inner diameter 15
A polycarbonate substrate 1 with a diameter of mm was molded by injection molding.

Example 1 as an organic dye for forming the light absorption layer 2
0.8g of the same dye as above, 10cc of acetylacetone solvent
This was applied onto the above-mentioned substrate 1 by a spin code method to form a light absorption layer 2 consisting of a dye film having a thickness of 0.times.17 .mu.m. The complex refractive index of this light absorption layer 2 is na
bs=2.7, l<abs=0. It is 05. The wavelength of the semiconductor laser for reproduction light is λ=780 nm, and ρ=n
abs-d abs /λ=0.59.

An Au film with a thickness of 500 angstroms is formed on the entire surface of this disk by vapor deposition to form a reflective layer 3. Further, an ultraviolet curable resin is spin-coded on the reflective layer 3, and ultraviolet rays are applied to this. Irradiate and harden to a thickness of 10 μm.
A protective layer 4 was formed.

EFM signals were recorded on the optical disc thus obtained using a semiconductor laser with a wavelength of 780 nm, as in Example 1, and reproduced with a commercially available CD player.

The total thickness of this optical disc is 1.2 mm1 and the reflectance is 72
%, I11/I top is 0.62, I3/I t
OP is 0.32, and the optical disc according to this example satisfies the CD standard.

(Example 22) Width 0.5μrrh Depth 0. 18μms pitch 1
Thickness: 1.6 μm spiral pre-group formed. 2mryh Outer diameter 120mmφ, inner diameter 15mm
A polycarbonate substrate 1 having a diameter of φ was molded by injection molding.

As an organic dye for forming the light absorption layer 2, ■, 1'
Diethyl 3. 3. 3', 3'tetramethyl5
．． 7. 5', ? - Dissolve 0.55 g of methoxyindoxycarpodianine perchlorate in 10 cc of diacetone alcohol solvent, and apply this onto the above substrate 1 by a spin code method to form a light absorption layer consisting of a dye film with an average thickness of 120 nm. 2 was formed. The complex refractive index of this light absorption layer 2 is nabs: 2.9 and kabs = 0.20. The wavelength λ of the semiconductor laser of the reproduction light is 780 nm, and ρ=nabs-dabs/λ=0. 45
It is.

An Au film with a thickness of 500 angstroms is formed on the entire surface of this disk by vapor deposition to form a reflective layer 3. Further, an ultraviolet curable resin is spin-coded on the reflective layer 3, and ultraviolet rays are applied to this. Irradiate and harden to a thickness of 10 μm.
A protective layer 4 was formed.

EFM signals were recorded on the optical disc thus obtained using a semiconductor laser with a wavelength of 780 nm, as in Example 1, and reproduced with a commercially available CD player.

The total thickness of this optical disc is 1.2mtrh, the reflectance is 70%, and I11/Itop is 0.70.13/I
top 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, I 11 / I top shown as the modulation degree is 0°6 in the total thickness range of 1.1 to 1.5 mm specified in the CD standard. Above, 13/I
It is possible to provide an optical information recording medium that can obtain a reproduced waveform with a top of 0.3 to 0.7, and a recording method thereof.

Furthermore, ρ in the light absorption layer = n abs-d ab
By setting s/λ to 0.05≦ρ≦0.6 and k abs to 0°3 or less, the reflectance 7 conforms to the CD standard.
It is possible to provide an optical information recording medium from which a reproduction signal of 0% or more can be obtained.

[Brief explanation of the drawing]

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. figure,
FIG. 3 is an enlarged partial cross-sectional view taken along the track of the optical information recording medium after recording shown in FIG. 1, and FIG. 4 shows recording when 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 after recording when an intermediate layer is provided, and FIG. Enlarged partial cross-sectional view before recording when a layer is provided, No. 7
The figure is an enlarged partial sectional view after recording in the case where the optical information recording medium of the present invention has two deformable layers provided with an intermediate layer, and FIG. 8 is a graph showing the relationship between the hardness of the deformable layer and the degree of modulation. , FIG. 9 shows ρ=n abs of the light absorption layer of the optical information recording medium.
A graph showing an example of the relationship between −d abs /λ and reflectance, FIG. 10, shows the imaginary part k abs of the complex refractive index of the light absorption layer.
A graph showing the relationship between ρ and reflectance, Figure 11, shows ρ= n
It is a graph showing the region where the reflectance satisfies the CD standard in abs-d abS/λ and k abs. l...Substrate 2...Light absorption layer 3...Reflection layer 4
...Hard layer 5...Pit 6...Intermediate layer 7.
...Laser light 8...Pickup

Claims (3)

[Claims] (1) Optical information recording in which a light-absorbing layer is provided on a light-transmitting substrate, either directly or through another layer, and a reflective layer and a hard layer are provided on the light-absorbing layer, directly or through another layer. In the media,
An optical information recording medium characterized in that the Rockwell hardness ASTM D785 of a portion closer to the light-transmitting substrate than the light-absorbing layer and in contact with the light-absorbing layer is M90 or less. (2) In claim 1 above, the light absorption layer is defined by ρ=n given by the real part n_a_b_s of the complex refractive index of the light absorption layer, the film thickness d_a_b_s, and the wavelength λ of the reproduction light.
_a_b_s・d_a_b_s/λ is 0.05≦ρ≦
0. 6, and the imaginary part k_a_b of the complex refractive index of the light absorption layer
An optical information recording medium characterized in that __s is 0.3 or less (3) A light-absorbing layer that absorbs laser light is provided on the light-transmitting substrate, either directly or through another layer, and a reflective layer and a hard layer are provided on the light-absorbing layer, either directly or through another layer. Using an optical information recording medium in which the Rockwell hardness ASTM D785 of the part in contact with the light-absorbing layer, which is closer to the light-transmitting substrate than the light-absorbing layer, is M90 or less, a laser beam is applied to the light-absorbing layer from the light-transmitting substrate side. An optical information recording method that deforms the part of the light-transmitting substrate that is in contact with the light-absorbing layer by applying energy to the light-absorbing layer, thereby forming pits in the same part.