JP3088510B2 - 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 a writable information recording medium, and more particularly to an information recording medium having a light absorbing layer and a light reflecting layer on a light transmitting substrate.

[0002]

2. Description of the Related Art It is generally well known that a recording film of a so-called writable information recording medium uses, for example, a cyanine-based or phthalocyanine-based organic dye.

As a writing method for such an information recording medium, a laser beam is focused on a very small area of a recording film, converted into heat energy, and the properties of the recording film are changed (pit formation). ing. In order to smoothly change the properties of the recording film, the medium may have a so-called air sandwich structure in which two recording films are provided on a substrate and the recording films are arranged to face each other. General.

A writing laser beam used for such an information recording medium is irradiated from the transparent substrate side to form optically readable pits in the recording film. The read laser beam for reproducing the recorded data has a lower output than the write laser beam, and the contrast between the portion where the pit is formed and the other portion is read as an electric signal.

On the other hand, unlike the above-mentioned medium, a so-called ROM (read only memory) on which data is already recorded in advance.
There are also y) type media, which are widely used in the fields of audio recording and information processing. However, this does not have a writable recording film as described above. That is, prepits corresponding to data to be reproduced are already formed on a plastic substrate by press molding, and a reflective layer made of a metal such as Au, Ag, Cu, or Al is formed thereon, and a protective layer is further formed thereon. A layer is formed. A typical medium of this ROM type is a compact disk called a so-called CD. The specifications of the recording and reading signals of the CD are standardized, and a CD reproducing apparatus is widely used as a compact disk player (CD player) according to the standard.

The writable information recording medium is similar to a CD in that a laser beam is used, and the medium is also similar to a CD in that the medium has a disk shape. Therefore, there has been a strong demand for the development of a writable medium that can be used as it is in a CD player, conforming to the CD specification standard, and actual samples have begun to be presented to meet this demand.

[0007]

However, although the actual sample satisfies the standard in its initial characteristics, it cannot control the recording sensitivity without the light fastness of the recording film, which is weak against repeated reading with large jitter. In view of such circumstances, the present invention has been invented, and its object is to reduce the so-called jitter, improve the repetitive readout performance and the light resistance of the recording film, and control the recording sensitivity of writable. An object of the present invention is to provide an information recording medium.

[0008]

According to the present invention, there is provided a light-absorbing layer on a light-transmitting substrate having a pregroove formed on one side surface, and a light-absorbing layer on the light-absorbing layer. In the information recording medium having a reflective layer, the light absorbing layer is a first cyanine dye having a light absorption band in a wavelength region of recording light or reproduction light, and a shorter wavelength side than the first cyanine dye. A second cyanine dye having a light absorption band and having a small light absorption in the wavelength range of the recording light or the reproduction light, and a first quencher for preventing light deterioration of the cyanine dye.
A second quencher of a diphenylamine compound, wherein the weight ratio of the second cyanine dye to the first cyanine dye is α, the weight ratio of the first quencher to the second quencher is β, the first cyanine When the ratio of the added weight of the first quencher and the second quencher to the added weight of the system dye and the second cyanine dye is γ, α
= 1 to 3, β = 0.5 to 1, γ = 0.25 to 0.5, α
-Contained so as to satisfy the condition of γ <1.1.

FIG. 1 is a schematic perspective view in which a part of the information recording medium of the present invention is cut away. Information recording medium 1 of the present invention
A light absorbing layer 12 is provided on a light transmitting substrate 11,
A light reflecting layer 13 is provided on the light absorbing layer 12, and a protective layer 14 is provided on the light reflecting layer 13.

Light absorbing layer 12 formed on substrate 11
A first cyanine dye having a light absorption band in the wavelength region of the recording light or reproduction light, and a light absorption band on a shorter wavelength side than the first cyanine dye, and the recording light or the reproduction light It contains a second cyanine dye having low light absorption in a wavelength region, a first quencher for preventing photodegradation of the cyanine dye, and a second quencher of a diphenylamine compound.

In the present invention, the wavelength range of the recording light or the reproduction light is, for example, a wavelength range of 770 to 830 nm. Therefore, the first cyanine dye is represented by the following general formula [I]. Cyanine dyes are used.

[0012]

Embedded image In the general formula [I], R ₁ and R ₂ each represent an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 3 to 5 carbon atoms. When the carbon number exceeds 8, deterioration is accelerated in a high-temperature and high-humidity test. Further, there is an inconvenience that waxing occurs and handling becomes inconvenient.

[0013] X ^- represents a counter ion, ClO ₄ specifically ^-, I ^-, Br ^-, and the like. on the other hand,
As the second cyanine dye, a cyanine dye represented by the following general formula [II] is used.

[0014]

Embedded image In the general formula [II], R ₃ and R ₄ each represent an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 3 to 5 carbon atoms. When the number of carbon atoms exceeds 8, the same disadvantages as in the case of the above general formula [I] occur. X ^- represents a counter ion, it has the same meaning as above.

Further, the light absorbing layer 12 contains a first quencher for preventing the cyanine-based dye from being deteriorated by light. As the first quencher, a metal complex is effective. For example, a N complex represented by the following general formula [III] is used.
i-complexes are preferred.

[0016]

Embedded image In the formula, R ₅ , R ₆ , R ₇ and R ₈ each represent hydrogen or an alternative substituent.

As the substituent, CH ₃ O—, CH ₃ OC
_{H 2 CH 2 O-, CH 3} COO -, (n-C 3 H 7) 2
_{N -, (C 2 H 5} ) 2 N-, Cl- , and the like.

Specific examples of such a first quencher include those of the following structural formulas [Q-1] to [Q-4].

[0019]

Embedded image

[0020]

Embedded image

[0021]

Embedded image

[0022]

Embedded image Among these quenchers, those represented by the above structural formula [Q-1] are particularly preferable in terms of preventing photo-deterioration of the cyanine dye.

The light absorbing layer 12 of the present invention contains a second quencher in addition to the first quencher. The second quencher is a diphenylamine compound represented by the following general formula [IV]. The second quencher is included in order to prevent the structure of the cyanine-based dye from being destroyed by recording, that is, pit formation, and to prevent the compound constituting the decomposition residue from deteriorating with time.

[0024]

Embedded image In this formula, R ₉ , R ₁₀ , and R ₁₁ each represent hydrogen, a nitroso group, a substituted or unsubstituted amino group, or a substituted or unsubstituted aryl group. Above all, the wavelength of the light absorption peak is 400 to 500 when the cyanine reaction residue has absorption.
A diphenylamine compound having a thickness of nm is particularly preferable, and specific examples include compounds represented by the following structural formulas [A-1] to [A-3]. If the wavelength of the light absorption peak is out of the above range, especially if it exceeds 500 nm, it may start to have absorption at the recording wavelength and the overall recording and reproduction characteristics may change. On the other hand, if it is less than 400 nm, it is a mere ultraviolet absorber, which matches the short wavelength absorption of the dye, and is meaningless.

[0025]

Embedded image

[0026]

Embedded image

[0027]

Embedded image In the present invention, the content of the first cyanine dye, the second cyanine dye, the first quencher, and the content of the second quencher of the diphenylamine compound are contained so as to satisfy the following conditions. . That is, the weight ratio of the second cyanine dye to the first cyanine dye is α, the weight ratio of the first quencher to the second quencher is β, the first cyanine dye and the second cyanine dye When the ratio of the added weight of the first quencher and the second quencher to the added weight of γ is γ, α = 1 to 3 β = 0.5 to 1 γ = 0.25 to 0.5 α · γ <1 1. It is contained so as to satisfy the condition of 1.

If these conditions are not satisfied, the reflectivity decreases in the laser wavelength range of the reproduction light. Further, in recording, the recording sensitivity decreases and the recording power increases. Also,
There is a disadvantage that light deterioration due to the reproduction light and light deterioration in a wavelength region other than the reproduction light are promoted.

The light absorbing layer 12 containing such a cyanine dye and a quencher is applied by, for example, a conventional means such as a spin coating method, and at the time of application, the first cyanine dye and the second If the concentration of the mixture with the cyanine-based dye is too low, the absorption sensitivity is reduced, so that a signal cannot be recorded with a semiconductor laser, and if the concentration is too high, the dye becomes difficult to dissolve in the solvent. Inconvenience occurs.

The thickness of the light absorbing layer 12 to be applied is 30 to
It is 900 nm, preferably 100 to 300 nm.
If this value is less than 30 nm, the absorption is reduced, so that the sensitivity in the semiconductor laser wavelength range is reduced, and a signal cannot be recorded. In this case, if the value exceeds 900 nm, the dye becomes too thick and the absorption increases. As a result, there is a disadvantage that the reflectance is reduced.

As the solvent used for coating, various known solvents are used, and examples thereof include diacetone alcohol, ethyl cellosolve, methyl cellosolve, isophorone, methanol, tetrafluoropropanol and the like.

As shown in FIG. 3, a tracking pre-groove 70 is formed concentrically or spirally on one side plane of the light transmitting substrate 11 on which the light absorbing layer 12 is provided. ing.

The pregroove 70 has a groove depth h of λ.
/6.5n to λ / 2.5n, more preferably λ / 4.7
It is preferable to form them so as to be n to λ / 3.6n. here
Where λ is the wavelength (nm) of the recording light or reproduction light, and n is the substrate
Represents the refractive index of The value of the groove depth h is λ / 6.5n
If less than this, crosstalk will increase and CD play
So-called three-beam tra necessary for stable playback
Locking error (TE _3b) Becomes smaller
And the value of the groove depth h exceeds λ / 2.5n
Increases the amount of dye applied to the grooves and increases absorption
Causes the disadvantage that the required reflectance decreases.
Occurs.

Incidentally, the wavelength of the recording light or the reproduction light to be used is usually 770 to 830 nm. Further, the pre-groove 70 has a groove width W of 0.35 to 0.47.
μm, more preferably 0.37 to 0.45 μm. If the value of the groove width W is less than 0.35 μm, the push-pull tracking error (TE _PP ) is reduced, and the recording sensitivity and the recording amplitude are disadvantageously reduced. The value of the groove width W is 0.47 μm.
When m exceeds m, the value of TE _PP decreases and crosstalk increases. The pre-group 70
As shown in FIG. 3, the cross-section of the groove is generally substantially trapezoidal, so that the groove width W in the present invention is a half of the groove depth h, that is, the width (μm) at the position of h / 2. Is defined by

As the substrate 11 having such a pre-groove 70, it is preferable to use a so-called integrally formed injection-molded resin substrate from the viewpoint of improving productivity. And a transparent material such as polymethyl methacrylate resin (PMMA). In particular, the average molecular weight is 32,000 to 40,000
It is preferable to use the polycarbonate resin (PC). Further, the substrate is not limited to an injection molded resin substrate formed integrally, but may be a substrate formed by a so-called 2P (photo-polymer) method. The thickness of such a substrate 11 is 1.0 to
It is about 1.5 mm.

The light absorbing layer 1 applied on the substrate 11
A light reflection layer 13 is provided on 2. Light reflection layer 13
Is made of a metal such as Au, Ag, Cu, or Al, and is formed by vacuum deposition, sputtering, ion plating, or the like. The thickness of such a light reflecting layer 13 is
It is about 0.02 to 2.0 μm.

The light absorbing layer 1 is usually provided on the light reflecting layer 13.
A protective layer 14 is provided to protect the light reflecting layer 2 and the light reflecting layer 13. The protective layer 14 is generally formed by spin-coating an ultraviolet-curable resin and then irradiating with ultraviolet light to cure the coating. In addition, an epoxy resin, an acrylic resin, a silicone resin, a urethane resin, or the like is used as a material of the protective layer 14. The thickness of such a protective layer 14 is
Usually, it is about 0.1 to 100 μm.

An intermediate layer for protecting the substrate 11 from a solvent may be provided between the substrate 11 and the light absorbing layer 12. Further, an intermediate layer may be provided between the light absorption layer 12 and the light reflection layer 13 to increase the efficiency of light absorption.

[0039]

Hereinafter, the present invention will be described in more detail with reference to specific examples. As the first cyanine dye and the second cyanine dye contained in the light absorbing layer, [D-1] and [D-2] shown below are used as the first quencher and the above [Q-1] ] Was used as the second quencher, [A-1] above.

First Cyanine Dye [D-1] In the above general formula [I], R ₁ and R ₂ are respectively nC ₄ H ₉ and X ⁻ is ClO ₄ ⁻ .

Second Cyanine Dye [D-2] In the above formula [II], R ₃ and R ₄ are respectively nC ₃ H ₇ and X ⁻ is I ⁻ .

Each of these dyes and quencher was dissolved in a solvent of ethyl cellosolve, and this was dissolved to a diameter of 1
25mm on a 20mm, 1.2mm thick polycarbonate substrate
It was applied to a thickness of 0 nm. The substrate used had a spiral groove previously formed by injection molding. A light reflecting layer made of Au was further formed on the light absorbing layer to a thickness of 0.1 μm by a vacuum evaporation method. Further, a protective layer of a photopolymer was provided on the light absorbing layer to prepare an information recording medium sample. In making the sample,
Various kinds of information recording medium samples were prepared by variously changing the combination of the first cyanine dye, the second cyanine dye, the first quencher, and the second quencher.

With respect to each of these samples, the power of the recording light capable of actually recording was measured. The results are shown in Table 1 below.
Shown in In Table 1, the mixing ratios are α, β,
It is converted to γ and α · γ value.

[0044]

[Table 1] From the results of the recording power shown in Table 1, the sample of the present invention can perform stable recording and control the recording sensitivity by adjusting the content ratio of the first cyanine dye and the second cyanine dye. Can be.

Next, a test of the repeated reading performance was performed in the following manner. That is, as the sample of the present invention, the sample No. One was used. As Comparative Sample 1, the sample of the present invention (Sample No.
The first quencher of 1) was changed to a quencher represented by the following structural formula [Q *]. As Comparative Sample 2, the first quencher of the sample of the present invention (Sample No. 1) was not used. As Comparative Sample 3, a sample from another company was used.

[0046]

Embedded imageFor these samples, the repeat reading time
I_topValue and I _ThreeValues and jitter over time
Specified. The results are shown in FIGS. 4, 5 and 6. these
From the results, it can be seen that the present invention has extremely repetitive read performance.
It turns out that it is excellent.

Next, a light resistance test was performed in the following manner. That is, as the sample of the present invention, the sample No. One was used. As a comparative sample, the second quencher of the sample of the present invention (Sample No. 1) was excluded, and the weight ratio α of the first cyanine dye [D-1] and the second cyanine dye [D-2] was α. Is set to 3, and the first quencher [Q-1] is replaced with the above [D-1] and [D-2]
1/6 of the added weight of

The samples were subjected to a light exposure test in the following manner. Light exposure test An FL tube having a spectrum very close to sunlight and a UV tube emitting ultraviolet light were placed close to each other, and a disk sample was placed 15 cm below the tube and tested. Light intensity is about 20
000 lx (lux). Evaluation is Block Error Rate
Was performed. The test results are shown in FIG. FIG. 7 is a graph showing the relationship between the elapsed time and the error rate, where a white circle indicates a sample of the present invention and a black circle indicates a comparative sample. From this graph, it can be seen that the present invention does not increase the error rate over time and is extremely excellent in light resistance.

Further, the recording medium having the light absorbing layer samples 1 to 4 shown in Table 1 was subjected to the light exposure test as described above. FIG. 8 shows the results. From this graph, the light resistance becomes poor when the compounding ratio of the cyanine dye and the quencher constituting the light absorption layer is out of the range of the present invention, while those in the range of the present invention have excellent light resistance. Recognize.

Further, the sample of the present invention (sample No. 1 in Table 1) used in the above-mentioned test of the repeated reading performance.
And Comparative Sample 1 (in which the first quencher of Sample No. 1 was changed to the quencher represented by the above structural formula [Q *]) under the same conditions as in the above-mentioned light exposure test, I _l (land) (Potential) and I _g (groove potential) and the change with time were examined. The results are shown in FIG. According to this graph, the samples of the present invention are I _l , I
_It can be seen that the electric potential of _g is both high, the change with time due to light exposure is extremely small, and the light resistance is excellent.

Next, in order to investigate the influence of the groove width W of the pre-groove, one substrate (diameter 120 mm, thickness 1.2 mm) having various groove widths as shown in Table 2 below was used.
mm polycarbonate substrate). Band No.
Becomes larger at the position outside the substrate.

[0052]

[Table 2] The groove width W is equal to the groove depth h as described above.
, Ie, the width at the position of h / 2 (μ
m). Groove width W and groove depth h
Are respectively a coordinate measurement scanning electron microscope (EMM-30)
00: Elionix Co., Ltd.).

On this substrate, a light absorbing layer containing a cyanine dye and a quencher was provided. That is, the sample Nos. The dye and the quencher were each dissolved in a solvent of ethyl cellosolve so as to obtain the composition shown in No. 1, and this was applied on the substrate to a thickness of 250 nm. On this light absorbing layer, a light reflecting layer made of Au was further formed to a thickness of 0.1 μm by a vacuum evaporation method. Further, a protective film of a photopolymer was provided on the light reflecting layer to prepare an information recording medium sample.

EFM signals were recorded and reproduced on the various medium samples prepared under the above conditions under the following conditions. EFM signal recording conditions Wavelength: 778 nm Linear velocity: 1.4 m / s Write power: 6.0 mW Read power: 0.5 mW For the medium recorded under the above conditions, the land potential I _l ,
Groove portion potential Ig, 11T (196 KHz) of the recording signal Potential I _top of the brightest portion of the amplitude, 11T (1
96KHz) amplitude potential I _11T , 3T (720KHz) amplitude potential I _{3T of} the recording signal, push-pull tracking error potential T
E _pp and the three-beam tracking error potential TE _3b were measured.

The measurement results are shown in FIGS. FIG.
0 is a graph showing a potential change of the land area potential I _l and groove portion potential I _g, FIG 11 is a graph showing a change of a push-pull tracking error potential TE _pp before and after recording, FIG. 12 FIG. 13 is a graph showing a potential change of the three-beam tracking error potential TE _3b , and FIG.
_top, is a graph showing a potential change of the I _11T, I _3T.

[0056] To evaluate in each sample From the results shown in these graphs, in order to conform the reproduced signal to the CD format, I _l, the relationship I _g, it must be an I _l> I _g It is.

Push-pull tracking error potential T
E _pp needs to be 0.04 V or more. This is because the tracking servo is applied stably and recording is performed reliably.

Three-beam tracking error potential TE _3b
Needs to be 2.5 V or more, which is almost the same as TE _{3b of} a commercially available CD. This is for stably reproducing the recording signal (pit) with a CD player.

I_top, I_11T, And I_3TIn the relationship
And I_topIs above due to the rule that the reflectance is 65% or more
In the recording / reproducing condition, 0.45 V or more is required._11T
/ I _topIs not less than 60%, I_3T/ I_topIs 30
% Or more and 70% or less. Enough anti
This is because the emissivity and the degree of modulation are increased.

As can be seen from the graphs of FIGS. 10 to 13, band No. 1 satisfies all of these evaluation conditions.
8 to 11 (groove width W = 0.35 to 0.47 μm).

Next, the groove width W of the pre-groove provided on the substrate is fixed at 0.44 μm, and the groove depth h is
From λ / 7.0n to λ / 3.8n angstroms ()
And the effect of the groove depth h was examined. In preparing the sample, an information recording medium sample was prepared using the same light absorbing layer, light reflecting layer, and protective film as those used for examining the effect of the groove width W.

The measurement results are shown in FIGS. FIG.
Graph 4 is a graph showing a potential change of the mirror surface part potential I _o and the groove portion potential Ig (I _o> must be a I _g), FIG. 15, showing a variation of push-pull tracking error potential TE _pp FIG. 16 shows I _top ,
FIG. 17 is a graph showing potential changes of I _11T and I _3T , and FIG. 17 is a graph showing potential changes of the three-beam tracking error potential TE _3b .

According to the graphs of FIGS. 14 to 17, when the groove width W is fixed to 0.44 μm, all of the above evaluation conditions are satisfied as λ / 4.5n to λ / 3.8.
n (where λ is the wavelength (nm) of recording light or reproduction light,
n represents the refractive index of the substrate). Note that the groove width W is set to 0.35 to 0.47 μm.
When the same experiment as described above was performed by changing the above, it was confirmed that good results were obtained in the groove depth range of λ / 6.5n to λ / 2.5n.

[0064]

According to the present invention, the light absorbing layer comprises a first cyanine dye having a light absorption band in the wavelength range of recording light or reproduction light, and a light absorption layer having a shorter wavelength than the first cyanine dye. A second cyanine dye having a band, and having a small light absorption in a wavelength range of recording light or reproduction light, a first quencher for preventing light deterioration of the cyanine dye, and a second quencher of a diphenylamine compound And the weight ratio of the second cyanine dye to the first cyanine dye is α, the weight ratio of the first quencher to the second quencher is β, the first cyanine dye and the second cyanine When the ratio of the added weight of the first quencher and the second quencher to the added weight with the system dye is γ, α = 1 to 3,
β = 0.5-1, γ = 0.25-0.5, α · γ <1.
Since it is configured so as to satisfy the condition (1), it is possible to provide a writable information recording medium capable of reducing jitter, improving repetitive read performance and light resistance of a recording film, and controlling recording sensitivity. .

[Brief description of the drawings]

FIG. 1 is a schematic perspective view in which a part of an optical recording medium of the present invention is cut away.

FIG. 2 is a partially enlarged cross-sectional view of a notch in FIG.

FIG. 3 is an enlarged sectional view of a substrate, particularly a pre-groove.

FIG. 4 is a graph showing a change over time of an I _top value with respect to a repeated read time.

FIG. 5 is a graph showing a change over time of an I ₃ value with respect to a repeated read time.

FIG. 6 is a graph showing a change in jitter over time with respect to a repetitive read time.

FIG. 7 is a graph showing a relationship between a light exposure time and an error rate.

FIG. 8 is a graph showing a relationship between a light exposure time and an error rate.

9 is a graph showing the relationship between the light exposure time and the land portion potential I _l Oyohi groove portion potential I _g.

FIG. 10 shows a land portion potential I ₁ and a groove portion potential I _g
5 is a graph showing a change in potential of the hologram.

FIG. 11 is a graph showing changes in a push-pull tracking error potential TE _pp before and after recording.

FIG. 12 is a graph showing a potential change of a three-beam tracking error potential TE _3b .

FIG. 13 is a graph showing potential changes of I _top , I _11T , and I _3T .

FIG. 14 shows a land portion potential I ₁ and a groove portion potential I _g.
5 is a graph showing a change in potential of the hologram.

FIG. 15 shows a push-pull tracking error potential TE _pp
6 is a graph showing a change in the graph.

FIG. 16 is a graph showing potential changes of I _top , I _11T , and I _3T .

FIG. 17 is a graph showing a potential change of a three-beam tracking error potential TE _3b .

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Information recording medium 11 ... Light transmissive substrate 12 ... Light absorption layer 13 ... Light reflection layer 14 ... Protective layer 70 ... Pregroove

Continuation of the front page (72) Inventor Fumio Matsui 6-1-1, Fujimi, Tsurugashima-shi, Saitama Prefecture Pioneer Corporation General Research Institute (56) References (JP, A) JP-A-64-27995 (JP, A) JP-A-4-185381 (JP, A) JP-A-2-300288 (JP, A) JP-A-3-232844 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) B41M 5/26 CAPLUS (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. A light having a pregroove formed on one side plane.
A light-absorbing layer on the transparent substrate, and light on the light-absorbing layer;
In an information recording medium having a reflective layer, the light absorbing layer absorbs light in a wavelength range of recording light or reproduction light.
A first cyanine dye having a band and the first cyanine dye;
Light absorption band on the shorter wavelength side than
Or a second cyanine with low light absorption in the reproduction light wavelength range
Dyes to prevent photodegradation of cyanine dyes
One quencher and the second
And a second cyanine dye with respect to the first cyanine dye.
Weight ratio α, first quench to second quencher
Weight ratio of β, the first cyanine dye and the second
Quencher and second for added weight with
When the ratio of the added weight to the quencher is γ, α = 1 to 3 β = 0.5 to 1 γ = 0.25 to 0.5 α · γ <1.1Contained to satisfy the conditions of The first cyanine dye has the following general formula Embedded image A cyanine dye represented by the formula: ₁ And R _Two Is it
An alkyl group having 1 to 8 carbon atoms, X ^- Is counterio
). The second cyanine dye has the following general formula: Embedded image A cyanine dye represented by the formula: _Three And R _Four Is it
An alkyl group having 1 to 8 carbon atoms, X ^- Is counterio
). The first quencher has the following general formula Embedded image A Ni complex represented by the formula: _Five , R ₆ , R ₇ And R
₈ Represents hydrogen or a substituent substituted for each of them)
An information recording medium, characterized in that: 2. The second quencher has the following general formula : A diphenylamine compound represented by the formula (wherein R ₉ ,
R ₁₀ and R ₁₁ are hydrogen, a nitroso group, substituted or unsubstituted
Represents an amino group or a substituted or unsubstituted aryl group)
The information recording medium according to claim 1, wherein
body. 3. The pre-groove has a groove depth of λ / 6.5n to λ / 2.5n (where λ is the wavelength (nm) of recording light or reproduction light, and n is the refractive index of the substrate. 3. The information recording medium according to claim 1, wherein the groove width is 0.35 to 0.47 μm.