JP3495751B2 - Optical information recording medium - Google Patents

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 capable of recording or reproducing an information signal by a magneto-optical recording device.

[0002]

2. Description of the Related Art Optical discs such as compact discs (CDs) and optical discs for recording video signals are widely used as optical information recording media. These optical information recording media are those in which a reflection layer for laser light and, if necessary, a protective layer are provided on a substrate on which concavities and convexities corresponding to information signals have been previously formed. It is a read-only type optical disc in which only the reproduction is performed. The reflective layer is made of a material having a high reflectance, that is, a low absorptivity, such as Al or Au.

On the other hand, unlike a read-only optical disc such as a CD, a magneto-optical disc has been proposed as an optical information recording medium capable of writing and erasing information. This magneto-optical disk has a recording magnetic layer, for example, Tb, which has an easy axis of magnetization in a direction perpendicular to the film surface and has a large magneto-optical effect on a substrate.
The recording portion is formed by laminating a rare earth-transition metal alloy amorphous thin film such as FeCo, a reflection layer, and a dielectric layer. As such a magneto-optical disk, a magneto-optical disk having a diameter of 64 mm has been proposed and put into practical use.

[0004]

By the way, if the read-only type optical disc can be reproduced by the recording / reproducing apparatus for the magneto-optical disc, in order to increase the spread and practicality of the read-only type optical disc and the magneto-optical disc system. preferable.
However, in a read-only type optical disc using Al, Au, etc. as a reflective layer, the reflectance for laser light is 70% or more,
Since the reflectance is extremely higher than that of a magneto-optical disk having a reflectance of 15 to 25%, and the degree of signal modulation is different from that of the magneto-optical disk, the signal cannot be reproduced by a recording / reproducing apparatus for the magneto-optical disk. If the recording / reproducing apparatus is equipped with two types of amplifiers capable of reproducing the information signals recorded on the re-dedicated optical disk and the magneto-optical disk, the signal reproduction can be performed. However, the circuit configuration of the recording / reproducing apparatus becomes complicated, which is not practical.

Therefore, the present invention has been proposed in view of such a conventional situation, and reproduction is performed by a recording / reproducing apparatus for a medium having a reflectance of about 15 to 25% such as a magneto-optical disk. It is an object of the present invention to provide an optical information recording medium capable of achieving the above, and to reduce the size and weight of a recording / reproducing apparatus for a medium having such a low reflectance reflective layer.

[0006]

In order to achieve the above-mentioned object, the present invention is directed to a substrate on which an information signal is recorded by a concave or convex pit portion on a land portion, which is reflected on the surface side where the pit portion is formed. In the optical information recording medium having a layer formed thereon, the reflection layer is a dye-containing layer having a reflectance of 15 to 25%, and the dye-containing layer is a combination of a dye, a polymer material and an additive. Counter ions of the cyanine dye contained in the containing layer are at least I ⁻ , ClO ₄ ⁻ , B
The ratio of the amount of reflected light that includes any one of F ₄ ^{− and} is incident from the substrate side and reflected by the land portion to the amount of reflected light that is incident from the substrate side and reflected by the pit portion having the maximum length. The degree of signal modulation of an information signal is 0.3
The optical phase difference ΔS between the pit portion and the land portion of the laser light emitted from the substrate side and reflected by the reflective layer, which is obtained by Equation 4, is ΔS = 2d _sub [n _sub − n _abs (1-d
_abs / d _Sub )] / λ Equation 4 d _sub : Distance between the interface between the substrate and the light reflection layer corresponding to the pit part and the interface between the substrate and the reflection layer corresponding to the periphery of the pit part d _abs : Pit part and the interface between the reflective layer and the air corresponding to the reflective layer that corresponds to the periphery of the pit portion and the air interface of the distance n _sub: real number portion n _abs of the complex refractive index of the _substrate: the real part of the complex refractive index of the reflective layer λ: optical distance difference ND between the land portion and the pit portion, which is obtained from the wavelength formula 5 of the laser light, and ND = (n _sub · d _sub + n _abs · d _ln ) −n
_abs · d _{gr (} 5) n _sub : Real part of complex index of refraction of substrate d _sub : Distance between first interface at pit part and first interface at land part n _abs : Real part of complex index of refraction layer d _ln : film thickness d _gr of the light reflection layer in the land portion The film thickness of the light-reflecting layer in the pit portion is determined by Equation 6 and ΔS = 2ND / λ Equation 6 The optical phase difference ΔS is 0.21 ≦ ΔS ≦ 0.94.

Here, the real part n of the complex refractive index of the reflective layer
Is selected in the range of 1.84 ≦ n ≦ 2.87.

[0008] Here, the counter ion of cyanine dye contained in the dye-containing layer is at least ^I -, ClO
₄ ^-, BF ₄ ^- any one of ions including of.

[0009]

[0010]

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

The optical information recording medium to which the present invention is applied has, as shown in FIG. 1, a concave pit portion 2a and a convex land portion 2b corresponding to information signals, guide grooves, and address code pits. The reflective layer 3 is formed on the substrate 1. In such an optical information recording medium, the information can be read by observing the difference in the reflected light amount between the pit portion 2a and the land portion 2b when the reflective layer 3 is irradiated with laser light from the substrate side.

In the present invention, such an optical information recording medium has a reflectance of 15 to 2 such as a magneto-optical disk.
In order to enable reproduction by a recording / reproducing apparatus for 5% of the medium, a dye is used as the reflection layer 3 of the laser light incident on the optical information recording medium for reading or writing the information signal. A containing layer is used.

The reflectance of the dye-containing layer becomes 15 to 25% which is the reproduction reflectance range of the recording / reproducing apparatus by adjusting the film thickness d, the optical constant and the like. The above object is achieved by using such a dye-containing layer as a reflection layer for laser light.

In the dye-containing layer, the real part n of the complex refractive index is preferably in the range of 1.84≤n≤2.87. By selecting the real part n of the complex refractive index in the above range, the dye-containing layer can have a laser light reflectance of 15 to 25% only by adjusting the film thickness d. Is easy to set.

The dye-containing layer is composed of a dye and a polymer material. In this case, the real part n of the complex refractive index can be adjusted to a desired value by controlling the mixing ratio of the dye and the polymer material.

As the dye contained in the dye-containing layer, if the real part n of the complex refractive index is selected in the range of 1.84 ≦ n ≦ 2.87 when the dye-containing layer is used, Either an organic dye or an inorganic dye may be used. Examples of organic dyes include cyanine dyes shown in Chemical formulas 13 and 14. The cyanine dye shown in Chemical formula 13 is NK52
9, NK3750, NK2670 (above, trade name of Nippon Senso Dye Co., Ltd.), S as the cyanine dye shown in Chemical formula 14
RC-8 (manufactured by Sony Corporation, trade name) and the like are available.

[0024]

[Chemical formula 13]

[0025]

[Chemical 14]

Further, when two or more kinds of dyes are contained in the dye-containing layer, the reflectance fluctuation depending on the irradiation light wavelength is suppressed, especially near the reproduction light wavelength (780 nm),
The playback signal is stable.

That is, the dye-containing layer has a property that the reflectance varies depending on the wavelength of irradiation light. On the other hand, the reproduction laser beam is usually set near the wavelength of 780 nm,
It varies in the range of 10 nm. For this reason, when the reflectance variation amount depending on the irradiation light wavelength of the dye-containing layer is large in the vicinity of 780 nm, the reflectance varies during reproduction, and the reproduction signal becomes unstable. When two or more kinds of organic dyes are contained in the dye-containing layer, the reflectance fluctuation depending on the irradiation light wavelength becomes small, and the reflectance fluctuation due to the wavelength fluctuation of the reproducing laser light is suppressed.

The polymer material in the dye-containing layer is preferably selected in consideration of compatibility with the dye. For example, when the above organic dye is used as the dye, polyvinyl butyral or the like is used.

Further, an additive may be added to the dye-containing layer for the purpose of preventing photobleaching of the dye. As the additive, a material having an electron donating property such as amines, a material having an energy level lower than the energy level of the excited state of the dye such as a nickel complex, and the like are used.

By providing the reflective layer as described above,
The reflectance is adapted to the magneto-optical disk recording / reproducing apparatus, but in order to be reproducible by the recording / reproducing apparatus, the difference between the reflectance and the reflected light amount of the pit portion and the land portion, that is, It is important that the signal modulation degree be adapted to the recording / reproducing apparatus.

The signal modulation degree referred to here is the reflected light amount I _Top of the land portion and the reflected light amount I ₁₁ of the pit portion having the maximum length.
Ratio of I ₁₁ / I _Top , and, for example, a magneto-optical disk having a diameter of 64 mm has a signal modulation degree I ₁₁ / I _Top of 0.3 to 0.6. In order to make a medium having such a signal modulation degree reproducible by a recording / reproducing apparatus, the signal modulation degree I ₁₁ / I _Top also needs to be 0.3 to 0.6. Becomes

The optical information recording medium of the present invention has a reflectance of 1 for the purpose of reproduction by a recording / reproducing apparatus for a disc having a diameter of 64 mm among magneto-optical discs.
5 to 25% and the signal modulation degree I ₁₁ / I
_Top is set to 0.3 to 0.6.

Below, the signal modulation degree I ₁₁ / I _Top is
The conditions for adjusting to 0.3 to 0.6 are shown.

First of all, in such an optical information recording medium, the signal modulation degree I ₁₁ / I _Top is determined by the optics of the light reflected from the reflection layer when the laser light L2 is irradiated from the substrate 2 side of the pit portion and the land portion. It is determined by the optical phase difference ΔS that the signal modulation degree I ₁₁ / I _Top becomes 0.3 to 0.6 when the optical phase difference ΔS is 0.21 to 0.94.

Optical phase difference Δ that determines the degree of signal modulation
When the interface between the substrate and the light reflecting layer is the first interface A ₁ and the interface between the light reflecting layer and the air is the second interface A ₂ , S is the land and the first interface A ₁ corresponding to the pit portion 2a. The distance d _sub of the first interface A ₁ corresponding to the portion 2b, the pit portion 2a
, The distance d _abs between the second interface A ₂ corresponding to and the second interface A ₂ corresponding to the land ₂ b, the real part n _sub of the complex refractive index of the substrate, and the real part n _abs of the complex refractive index of the light reflecting layer.
Depends on The relational expression which is the basis for this is shown below.

That is, the pit portion 2a in the land portion 2b
The second interface A based on the first interface A ₁ in
Optical distance _{X 1} to _{2, X 1 = n sub · d} sub + n abs · d ln
Equation 7 n _sub : Real part of complex refractive index of substrate d _sub : Distance between first interface in pit part and first interface in land part n _abs : Real part of complex refractive index of reflective layer d _ln : Land It is represented by the film thickness of the light reflection layer in the part. Optical distance _{X 2} to the second interface in the case where the first reference surface _{A 1} in the pit portion 2a of the pit portion _{2a, X 2 = n abs · d} gr ··· formula 8 _{n abs:} reflective layer Real part d _gr of complex refractive index of: is represented by the film thickness of the light reflection layer in the pit portion. Therefore, Equation 3, the optical distance difference ND of pits and lands from Equation _{4, ND = (n sub · d} sub + n abs · d ln)
−n _abs · d _gr ... _{Represented by} Formula 9. Here, d _gr + d _abs = d _ln + d _sub , which is replaced by d _gr −d _ln = d _sub −d _abs .. Using this formula 10, the formula for calculating the ND of formula 9 (formula 9) is: ND = n _sub · d _sub −n _sub (d _sub −
d _abs ) ... Replaced with Equation 11. On the other hand, the optical phase difference ΔS between the pit portion 2a and the land portion 2b of the laser beam emitted from the substrate 2 side and reflected by the reflective layer 3 is represented by ΔS = 2ND / λ, and this equation is expressed by Equation 7 By using the ND calculation formula of ΔS = 2d _sub [n _sub −n _abs (1-d
_abs / d _Sub )] / λ ...

From this equation 12, the optical phase difference ΔS is n
_It can be seen that it is determined by _sub , n _abs , d _sub , and d _abs .

Therefore, the signal modulation degree is 0.3 to 0.6.
In order to set the optical phase difference ΔS to be 0.21 to 0.94, n _sub , n _abs , d _sub and d
_Abs is set, and the pit portion 2a is set according to the set value.
The depth, the film thickness of the light reflection layer, etc. may be adjusted. As a result, the present invention can be applied to a recording / reproducing apparatus for a magneto-optical disk whose reflectance and signal modulation are both 64 mm in diameter.

The optical information recording medium having the above structure can also be applied to a write-once type optical information recording medium in which a reflection layer is irradiated with laser light to write an information signal. However, in this case, the information pits are not formed on the substrate, and only the guide groove and the address code pit are formed.

When used as a write-once optical information recording medium, when the reflection layer is irradiated with laser light, the dye contained in the reflection layer absorbs the laser light and generates heat. As a result, the reflective layer is partially thermally expanded to form a raised portion that becomes a pit portion. Even when the pit part is formed in this way,
Since the reflectance of the reflective layer is 15 to 25%, information can be read by the recording / reproducing device for a magneto-optical disk.

The write-once type optical information recording medium having such a structure has a proper reflectance and is thinner than the conventional write-once type optical information recording medium, for example, the standard thickness of a magneto-optical disk having a diameter of 64 mm. It is also possible to set it to about 1.2 mm. Also in this respect, it is highly popular and practical.

Incidentally, the structure of a conventional write-once type optical information recording medium is shown in FIG.

That is, in the conventional write-once type optical information recording medium, a pigment layer 22 made of only a pigment is formed on a substrate 21, and a protective cover 24 is covered on the pigment layer 22 with an air layer 23 interposed therebetween. That is, a pit portion is formed by irradiating the dye layer 22 with laser light to partially remove the dye.

In the above optical information recording medium, for example, the thickness of each component is 1.0 mm for the substrate 21 and the dye layer 2
2 is 40 nm, air layer 23 is 0.5 mm, protective cover 2
4 is 1.0 mm, in this case the total thickness is 2.5
mm or more. Even in such an optical information recording medium, the overall thickness can be reduced to some extent by thinning each constituent element, but there is a limit to the thinning due to the formation of the air layer 23, and the diameter is 64 mm. It is difficult to adjust the standard thickness of the magneto-optical disk to 1.2 mm.

The basic structure of the optical information recording medium of the present invention has been described above. However, in the optical information recording medium of the present invention, the reflective layer 4 can be used in both read-only and write-once applications. A protective film for protecting the reflective layer 4 may be provided on the top. As the protective film, fluorine resin, silicon resin, or the like is used.

[0046]

In the optical information recording medium in which the reflective layer is formed on the surface side of the substrate on which the information signal is recorded by the concave or convex pit portion on the land portion, the reflectance of the reflective layer is 15 to When the 25% dye-containing layer is used, reproduction can be performed by a recording / reproducing apparatus for a medium having a reflectance of 15 to 25% such as a magneto-optical disk.

When the real part n of the complex index of refraction is selected in the range of 1.84≤n≤2.87 as the dye-containing layer, the dye-containing layer has a reflectance within the above range only by controlling the film thickness. It is easy to set the conditions for forming the reflective layer.

By setting the signal modulation degree to 0.3 to 0.6, reproduction can be performed by a recording / reproducing apparatus using a magneto-optical disk having a diameter of 64 mm as a recording medium. Here, the signal modulation degree is determined by the optical phase difference ΔS of the light reflected from the reflection layer when the laser light is emitted from the substrate side of the pit portion and the land portion having the maximum length,
The signal modulation degree I ₁₁ / I _Top becomes 0.3 to 0.6 when the optical phase difference ΔS is 0.21 to 0.94.

The optical information recording medium having the above-mentioned structure is a read-only type optical information recording medium in which an information signal is written in advance on the surface of the substrate, and additionally, an information signal is written by irradiating a laser beam on the reflective layer. It is also used as a mold type optical information recording medium. The write-once type optical information recording medium having such a structure is thinner than the conventional write-once type optical information recording medium and has a diameter of 64.
The standard thickness of the magneto-optical disk is 1.2 mm
It is advantageous to set the degree.

[0050]

EXAMPLES Specific examples of the present invention will be described below based on experimental results.

The dyes, binders, and additives used in the production of the optical information recording medium in this example are as follows.

[0052]   Dye A: NK529 (manufactured by Japan Photosensitive Dye Company, trade name)   Dye B: SRC-8 (Sony, product name)   Binder: polyvinyl acetoacetal, for example PVB-2000AS (electric   (Material C) Product name, manufactured by Ki Kagaku Kogyo Co., Ltd.   Additive: amine compound (Nippon Kayaku Co., Ltd., trade name IRG003)   (Material D)   Solvent: Hydroxymethylbutanone (Tokyo Chemical Industry Co., Ltd.)   (Material E)   The chemical formula of Material D is shown in Chemical formula 15.

[0053]

[Chemical 15]

Experimental Example 1 In this experimental example, the present invention is applied to a read-only optical disc in which a reflective layer is formed on a substrate on which pit portions and land portions corresponding to information signals, guide grooves, and address code pits are formed in advance. Experiments were performed for the case of applying. The reflectances measured in the following experiments are the reflectances of the light reflected when the laser light is irradiated from the substrate side.

(1) Examination of reflectance characteristics of optical information recording medium Dyes A and B and materials C, D and E were mixed in the following composition ratio to prepare a dye-containing composition.

(A + B + C): D: E = 3: 0.2: 1
The composition ratio of the dyes A and B and the material C was changed as shown in Table 1.

Then, the dye-containing composition was spin-coated on a polycarbonate substrate to form a reflective layer, and optical information media (Sample 1 to Sample 5) were produced. here,
The dye-containing composition has a constant film thickness of 10 in Samples 1 to 5.
Deposited at 0 nm to form a reflective layer.

Table 1 also shows the real part n and the reflectance of the complex refractive index of the optical information recording medium thus prepared.
In addition, FIG. 2 shows the results of changes in reflectance with respect to the real part n of the complex refractive index of these samples 1 to 5.

[0059]

[Table 1]

As can be seen from FIG. 2, the real part n of the complex refractive index and the reflectance have a substantially proportional relationship. As described above, when the film thickness is 100 nm, the real part n of the complex refractive index is n.
Is about 1.8 to 2.3, the reflectance is 15 to 2
It turns out that it becomes 5%.

For reference, the above-mentioned optical information recording medium 1 is used.
The wavelength dispersion of the optical constants, that is, the refractive index and the extinction coefficient, was measured on the mirror surface of which the surface of 0 was not recorded.
In FIG. 3, the solid line n shows the change in the refractive index n, and the solid line k shows the change in the extinction coefficient k.

Further, as an example of the optical information recording medium 10, when the real part n of the complex refractive index of the reflective layer 3 is 2.48 and the wavelength λ of the reproduction light is 780 nm, the reflectance is 15 to 25. FIG. 4 shows the result of examining the range of the film thickness which becomes%. In FIG. 4, a region S indicates a range where the reflectance is 15 to 25%, and the film thickness d is about 30 nm to 60, 100 to 1
The range is about 30 nm.

Next, the composition of the dye in the reflective layer was adjusted, and the film thickness dependence of the reflectance was examined when the real part n of the complex refractive index was 1.84 and 2.87. The results are shown in FIGS. 5 and 6.

In FIG. 5, the real part n of the complex refractive index is 1.84.
The film thickness dependence of the reflectance of the reflective layer 3 at the time is shown, and it can be seen that the reflectance of 15% is barely obtained when the film thickness is 100 nm.

On the other hand, in FIG. 6, the real part n of the complex refractive index is 2.
In the case of 87, the film thickness is about 20 to 30 nm, 100
It can be seen that a reflectance of 15 to 25% is obtained when the thickness is about 110 nm.

From these results, the real part n of the complex refractive index
Is set to 1.84 or more, and the film thickness of the reflective layer is appropriately selected to ensure that the reflectance of the reflective layer is 15% or more.
It can be seen that it can be made 5% or less.

Next, an optical information recording medium in which the composition ratio of the dyes A and B in the reflective layer is dye A: dye B = 1: 1, an optical information recording medium containing only dye A, an optical information recording medium containing only dye B, Dye A:
Dye B = 2: 1 optical information recording medium, Dye A: Dye B =
With respect to the 1: 2 optical information recording medium, the wavelength dependence of the reflectance was measured by a self-recording spectrophotometer U3210 (manufactured by Hitachi, Ltd.) in a so-called mirror surface where no information signal was formed. The results are shown in FIGS.
Shown in 1.

First, from FIG. 7, the dye A and the dye B of the reflective layer are formed.
The optical information recording medium containing and in a composition ratio of 1: 1 has a small wavelength dependency of reflectance, and in particular, a constant reflection of about 20% in the range of 780 ± 10 nm which is the wavelength of the reproducing light. It turns out that it has a rate. On the other hand, as can be seen from FIGS. 8 to 11, in the other optical information recording media, the reflectance has wavelength dependency, and in particular, the current reproduction light wavelength is 7
The reflectance changes rapidly in the vicinity of 80 nm ± 10 nm.

Therefore, by incorporating a plurality of dyes in the reflective layer in an appropriate composition ratio, the wavelength dependence of reflectance is eliminated, and an optical information recording medium can be obtained in which a more stable reproduction signal can be obtained. I understood.

(2) Examination of Signal Modulation Degree of Optical Information Recording Medium A 1.2 mm thick polycarbonate substrate having pit portions formed at a track pitch of 1.6 μm was produced by injection molding. The dimensions of the pit portion are as shown in Table 2.

[0071]

[Table 2]

Next, the dyes A and B and the materials C, D and E were mixed in the following composition ratio to prepare a dye-containing composition.

A: B: C: D: E = 1: 1: 1.5:
0.2: 100 Then, the dye-containing composition was applied onto the above-mentioned polycarbonate substrate by a spin coating method to form a reflective layer, thereby preparing an optical information recording medium.

When forming the reflective layer, the film thickness d _{ln at} the land portion and the film thickness d _{gr at the} pit portion of the reflective layer are adjusted as shown in Table 3 by controlling the substrate rotation speed of spin coating. did.

The distance d _sub between the interface between the substrate and the light reflection layer corresponding to the pit portion of the manufactured optical information recording medium and the interface between the substrate and the light reflection layer corresponding to the periphery of the recess, and the light reflection corresponding to the pit portion The distance d _abs between the layer-air interface and the light-reflecting layer-air interface corresponding to the periphery of the recess, the real part n _sub of the complex index of the substrate, the real part n _abs of the complex index of the light-reflecting layer, and these The optical phase difference ΔS calculated from each value is shown in Table 3 together with the above d _ln and d _abs .
Further, the results of the measured signal modulation degree are also shown in Table 3, and the relationship between ΔS and the signal modulation degree is shown in FIG.

[0076]

[Table 3]

As can be seen from Table 3 and FIG. 12, the signal modulation degree in the above optical information recording medium increases proportionally depending on the optical phase difference ΔS. From this, it is understood that the signal modulation degree can be adjusted to a desired value by controlling the optical phase difference.

For example, when the signal modulation degree is 0.3 to 0.6 which is the MD signal modulation degree, ΔS is 0.21 to 0.
It may be 94.

Experimental Example 2 In this experimental example, an experiment was carried out in which the present invention was applied to a write-once optical disc in which a reflective layer for recording information signals was formed on a substrate on which only guide grooves and address code pits were formed. I went. The dye-containing composition was prepared by mixing the dyes A and B and the materials C, D and E in the composition ratios shown below.

A: B: C: D: E = 1: 1: 1: 1.
2: 100 Then, this dye-containing composition was spin-coated on a polycarbonate substrate having a thickness of 1.0 mm to give a film thickness of 0.130 μm.
A reflective layer of m was formed to prepare an optical information recording medium.

With respect to the optical information recording medium thus prepared, information writing / reading was performed with a laser beam having a wavelength of 780 ± 10 nm, and the reproduction signal modulation degree was examined.

As a result, it was confirmed that the optical information recording medium had a sufficient signal modulation degree for obtaining a reproduced signal. Moreover, this signal modulation factor is 0.0.1 which is defined as a standard modulation factor in a magneto-optical disk having a diameter of 64 mm.
It was in the range of 3 to 0.6.

Therefore, from this fact, the optical information recording medium of the present invention can be used as a write-once type optical information recording medium, and the recorded information signal is recorded on an MO disk such as a magneto-optical disk having a diameter of 64 mm. It was found that it can be reproduced by the reproducing device.

Further, it has been found that the above optical information recording medium has a small thickness as a whole and can be adjusted to the standard thickness of 1.2 mm for a magneto-optical disk having a diameter of 64 mm.

[0085]

As is apparent from the above description, in the present invention, a reflective layer is provided on the surface side where the pit portion is formed on the substrate on which the information signal is recorded by the concave or convex pit portion in the land portion. In the formed optical information recording medium, or an optical information recording medium provided on the substrate, a reflective layer in which concave or convex land portions and pit portions are formed by recording an information signal,
By using a dye-containing layer of 15 to 25% as a reflective layer and a signal modulation degree of 0.3 to 0.6, a read-only type optical information recording medium and a write-once type optical information recording medium can be used as a magneto-optical disk. Can be reproduced by a recording / reproducing apparatus using

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an essential part showing a configuration example of an optical information recording medium of the present invention.

FIG. 2 is a characteristic diagram showing the relationship between the real part n of the complex refractive index and the reflectance of the optical information recording medium.

FIG. 3 is a characteristic diagram showing wavelength dispersion of real numbers n and k of a complex refractive index of a reflective layer of an optical information recording medium.

FIG. 4 shows that the real part n of the complex refractive index is 2.
It is a characteristic view which shows the film thickness dependence of the reflectance in the case of 48.

FIG. 5 shows that the real part n of the complex refractive index is 1.
It is a characteristic view which shows the film thickness dependence of the reflectance in the case of 84.

FIG. 6 shows that the real part n of the complex refractive index is 2.
FIG. 38 is a characteristic diagram showing film thickness dependence of reflectance in the case of 87.

FIG. 7 is a characteristic diagram showing the relationship between the irradiation light wavelength and reflectance when the composition ratio of dyes in the reflective layer is dye A: dye B = 1: 1.

FIG. 8 is a characteristic diagram showing the relationship between the irradiation light wavelength and reflectance when the composition ratio of dyes in the reflective layer is dye A: dye B = 1: 0.

FIG. 9 is a characteristic diagram showing the relationship between the irradiation light wavelength and the reflectance when the composition ratio of the dye in the reflective layer is Dye A: Dye B = 0: 1.

FIG. 10 is a characteristic diagram showing the relationship between the irradiation light wavelength and reflectance when the composition ratio of dyes in the reflective layer is dye A: dye B = 2: 1.

FIG. 11 is a characteristic diagram showing the relationship between the irradiation light wavelength and the reflectance when the dye composition ratio in the reflective layer is dye A: dye B = 1: 2.

FIG. 12 is a characteristic diagram showing the relationship between the optical phase difference ΔS and the signal modulation degree.

FIG. 13 is a schematic cross-sectional view of essential parts showing a configuration example of a conventional optical information recording medium.

[Explanation of symbols]

1 substrate, 2 uneven pits and lands, 2a
Pit, 2b land, 3 reflective layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takao Murooka               6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo               Knee Co., Ltd. (72) Inventor Yoshinaga Yanagisawa               6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo               Knee Co., Ltd.                (56) Reference JP-A-3-125331 (JP, A)                 JP-A-6-122276 (JP, A)                 JP-A-2-139733 (JP, A)                 JP-A-4-147449 (JP, A)                 JP-A-2-42652 (JP, A)                 JP-A-4-289532 (JP, A)                 JP-A-3-54744 (JP, A)                 JP 58-224448 (JP, A)

Claims (2)

(57) [Claims] 1. An optical information recording medium in which a reflective layer is formed on a surface of a substrate on which an information signal is recorded by concave or convex pits on a land, and the reflective layer is formed on the surface side on which the pits are formed. The dye-containing layer has a ratio of 15 to 25%, the dye-containing layer is a combination of a dye, a polymer material, and an additive, and the counter ion of the cyanine dye contained in the dye-containing layer is at least I ^−. , _ClO ⁴ -, BF ₄ ^- Noi
Of the information signal, which is a ratio of the amount of reflected light that is incident from the substrate side and is reflected by the land portion and the amount of reflected light that is incident from the substrate side and is reflected by the pit portion that has the maximum length The signal modulation degree is 0.3 to 0.6, and the optical phase difference ΔS between the pit portion and the land portion of the laser light emitted from the substrate side and reflected by the reflective layer, which is obtained by the equation 1, is ΔS. = 2d _sub [n _sub −n _abs (1-d
_abs / d _Sub )] / λ Equation 1 d _sub : Distance between the interface between the substrate and the light reflection layer corresponding to the pit portion and the interface between the substrate and the reflection layer corresponding to the periphery of the pit portion d _abs : Pit portion and the interface between the reflective layer and the air corresponding to the reflective layer that corresponds to the periphery of the pit portion and the air interface of the distance n _sub: real number portion n _abs of the complex refractive index of the _substrate: the real part of the complex refractive index of the reflective layer λ: Optical distance difference ND between the land portion and the pit portion, which is obtained from the wavelength formula 2 of the laser light, and ND = (n _sub · d _sub + n _abs · d _ln ) −n
_abs · d _gr Equation 2 n _sub : Real part of complex refractive index of substrate d _sub : Distance between first interface at pit part and first interface at land part n _abs : Real part of complex refractive index of reflective layer d _ln : film thickness d _gr of the light reflection layer in the land portion The film thickness of the light reflecting layer in the pit portion is determined by Equation 3, and ΔS = 2ND / λ Equation 3 is characterized in that the optical phase difference ΔS is 0.21 ≦ ΔS ≦ 0.94. Optical information recording medium. 2. The optical information recording medium according to claim 1, wherein the real part n of the complex refractive index of the reflective layer is selected as 1.84 ≦ n ≦ 2.87.