JPH04157627A - Recording method for optical information - Google Patents

Abstract

PURPOSE:To record a signal having excellent recording/reproducing characteristics on a dye recording type optical disk with a reflecting layer by satisfying specific relationship among the type of a dye recording layer, thickness of the layer and a pulse width of a laser at the time of recording. CONSTITUTION:When information is recorded on an information recording medium having a dye recording layer 2 and a reflecting layer 32, the information is recorded under a condition that the thickness of the layer 2 and a shortened width of a pulse ofa laser at the time of recording satisfy a formula I. In the formula I, d (mum) is the thickness of the layer of the bottom of a group of the recording layer, dma (mum) is the minimum thickness of the layer of the bottom of the group of the recording layer in which reflectivity from the group is maximum, and alpha is a ratio of the thickness of the layer of the bottom of the group to the thickness of the layer of a land of the recording layer. Pdir (ns) is a predetermined width shortened when a pulse width of the same length as that of a bit to be recorded is modulated with a pulse width at the time of recording, and dmdm (ns) is a minimum pulse width of the pulse width of the same length as that of the bit to be recorded. Thus, a signal having excellent recording/reproducing characteristics can be recorded on a dye recording layer type optical disk with a reflecting layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an optical information recording method for recording information on an information recording medium using a laser.

[Technical Background of the Invention] In recent years, information recording media using high energy density beams such as laser light have been developed and put into practical use. This information recording medium is called an optical disk, and can be used as a video disk, an audio disk, a large-capacity still image file, and a large-capacity computer disk memory. Among these information recording media, compact discs (CDs) are widely used for audio playback such as music, but CDs
is for playback only and cannot record information.

An information recording medium that can record general information (DRAW (
Direct Read After Write)
) has a basic structure of a disc-shaped transparent substrate made of plastic, glass, etc., and Bi, Sn provided on this.
, a recording layer made of a metal or metalloid such as In, Te, or a dye such as a cyanine dye.

In addition, the recorded information may be stored on the above compact disc (CD).
DRAW-type CDs that can be played on commercially available CD players have also been developed, and some of them have been put into practical use.

Recording of information on such an information recording medium is generally performed by irradiating a laser beam onto a pregroove provided on a substrate for guiding a laser to a predetermined position. Information is recorded by absorbing the light in the irradiated portion of the layer and causing a local temperature increase, resulting in physical or chemical changes such as the formation of pits, which change its optical properties. The laser emitted in this case generally consists of pulses with a pulse width that corresponds to the pit length to be recorded.

For example, in the case of a recording layer or a metal layer provided on a substrate, recording is generally performed using a laser beam with a pulse width shorter than the pit length to be recorded by a certain width. There is. In other words, metals generally have higher thermal conductivity and faster heat conduction than organic substances such as dyes, so the heat generated when the laser irradiates the metal recording layer does not accumulate in the laser-irradiated portion of the metal layer. , tends to spread. Therefore, the pit formation area tends to be larger than the laser irradiation area. In addition, pits in the metal recording layer are formed when the metal is melted by the heat of the laser, and the energy generated from the difference in surface tension between the molten metal and the substrate surface pushes the molten metal away from the laser irradiation area from the substrate surface. be done. For this reason,
The resulting pit shape depends on the melting point of the metal material used for the recording layer,
It tends to change due to surface tension, and the area is larger than the laser irradiation area and tends to be non-uniform. From this point of view, information recording by laser irradiation on the metal recording layer is generally performed by irradiating the metal recording layer with a laser having a pulse whose pulse width is a certain width shorter than the pit length to be recorded, as described above.

On the other hand, a recording layer made of a dye has a C/C ratio compared to a metal recording layer.
Although practical application has been delayed due to the low N content, an optical disc in which a reflective layer of Au is provided on the dye recording layer has recently been proposed (Nikkei Electronics, p. 107, published on January 23, 1989), and is being studied. There is. As described above, optical discs having a dye recording layer with a reflective layer have improved reflectance and generally have improved C/N.

Unlike the above-mentioned metals, pigments have low thermal conductivity, and unlike metals, they do not melt due to heat, but have the property of decomposing or sublimating. For this reason, when the dye recording layer is irradiated with a laser, the irradiated area decomposes or sublimates and disappears without thermal conduction, so it is thought that pits approximately the same size as the irradiated area are formed. Therefore, if the pulse width of the laser irradiated to the dye recording layer is the same as the pit length to be recorded, it is thought that pits with approximately the same length as the pit length to be recorded will be formed. .

However, in optical discs consisting of a substrate and a dye recording layer, and in optical discs in which a reflective layer is provided on the dye recording layer,
It is not clear what kind of pulse width laser should be used to achieve good recording.

[Purpose of the Invention] The present inventors have intensively studied a method for recording signals with excellent recording and reproducing characteristics, particularly jitter, on an optical disk formed on a substrate with a dye recording layer and a reflective layer, or in this order. Ta. As a result, it became clear that this is possible as long as the type and thickness of the dye recording layer and the pulse width of the laser during recording satisfy specific relationships, leading to the present invention.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical information recording method that can record signals with excellent recording and reproducing characteristics on a dye recording layer type optical disc with a reflective layer.

Another object of the present invention is to provide an optical information recording method that can record signals particularly with excellent jitter on a dye recording layer type optical disc with a reflective layer.

Furthermore, the present invention provides a suitable combination of the layer thickness of the recording layer of a high-reflectance optical disc and the recording pulse width of the laser of an optical drive used to record a CD format EFM signal on the optical disc. Therefore, it is an object of the present invention to provide an optical information recording method that can perform recording with excellent reproduction characteristics.

[Summary of the Invention] The present invention provides a recording layer consisting of a pigment layer capable of recording information using a laser and a reflective layer consisting of a metal provided on a disk-shaped substrate having pregrooves in the following order: An optical information recording method in which information is recorded by irradiating a recording medium with a laser from one side of the substrate, wherein the pulse width of the laser corresponding to the pit length to be recorded is expressed by the following formula (I): pa+do+0 , 3 ... (1) [However, d (μm) represents the layer thickness at the bottom of the group of recording layers, and d,, a (μm) represents the group of recording layers where the reflectance from the group becomes maximum. represents the minimum layer thickness at the bottom,
α represents the ratio of the layer thickness at the group bottom of the recording layer to the layer thickness at the land portion of the recording layer, and pdif (nS) is the pulse width of the same length as the pit length to be recorded, which is modulated to the pulse width during recording. and pmd+m
(nS) represents the minimum pulse width among pulse widths having the same length as the pit length to be recorded] The optical information recording method is characterized by having a pulse that satisfies the following.

Preferred embodiments of the optical information recording method of the present invention are as follows.

1) The above-mentioned optical information recording method, wherein the above-mentioned d(u+++) is in a range of 0.05 to 0.25 μm.

2) The above d, (μm) is 0.04 to 0.30 μm
The above-mentioned optical information recording method is characterized in that the optical information recording method is within the range of .

3) The above optical information recording method, wherein the above α is in a range of 0.9 to 3.0.

4) The optical information recording method described above, wherein the pd+t (nS) is in a range of 0 to 400 nS.

5) The above optical information recording method, wherein the above ads (nS) is in a range of 40 to 900 ns.

6) The above pd i f/pwadm is 0≦pdif/
The above-mentioned optical information recording method is characterized in that it satisfies psdm <1/2.

7) The above-mentioned optical information recording method, characterized in that a protective layer is formed on the reflective layer.

8) The optical information recording method described above, wherein the information is an EFM signal in CD format.

9) The above optical information recording method, wherein the dye is at least one selected from the group consisting of cyanine dyes, oxonol dyes, merocyanine dyes, biryllium dyes, thiopyrylium dyes, naphthalocyanine dyes, and phthalocyanine dyes.

[Effects of the Invention] In the present invention, when recording information by irradiating an information recording medium having the dye recording layer and the reflective layer from the substrate side with a laser having a pulse having a shortened pulse width, the dye recording layer Information is recorded under the conditions that the layer thickness and the shortening width of the laser pulse during recording satisfy the above formula (I).

In this way, the shortening width of the pulse of the optical drive used for recording information (the shortening width may be 0), the layer thickness of the recording layer of the optical disk, and the maximum reflectance layer thickness (generally known from the type of dye) can be adjusted. By adjusting the information, information can be recorded well. That is, the formation of the recording layer is performed by determining the maximum reflectance layer thickness of an arbitrary dye, and then determining the layer thickness of the recording layer that satisfies the above formula (1) according to the pulse width during recording. It can be done. In particular, signals recorded in this way have excellent jitter during playback.

Furthermore, it is also possible to manufacture optical discs that are applicable to many types of optical drives.

[Detailed description of the invention] The information recording medium used in the optical information recording method of the present invention is
It has a basic structure in which a recording layer made of a dye and a reflective layer are laminated in this order on a substrate.

The optical information recording method of the present invention will be explained with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view for explaining an example of the optical information recording method of the present invention.

FIG. 1 shows a disc-shaped substrate l having a pregroove, a recording layer 2 made of a dye provided on the substrate, a reflective layer 3 made of metal provided on the recording layer, and a reflective layer 3 provided on the reflective layer. A state in which a laser 6 is irradiated from the substrate side and focused on the recording layer on the pregroove bottom 5 of the substrate while rotating the information recording medium 10 made of the protective layer 4 is shown.

Specifically, information is recorded by moving the information recording medium 10 at a constant linear velocity (1.5 mm in the case of CD format) as shown in FIG.
This is done by forming pits by irradiating the recording layer with a semiconductor laser beam modulated to the pulse width of the recording signal from the substrate side while rotating at a constant angular velocity (2 to 1.4 m/sec) or at a constant angular velocity. It can be done. The pits are formed, for example, by forming cavities in the recording layer or between the recording layer and the reflective layer, or by changing the refractive index by causing discoloration or a change in the association state of the recording layer. Further, as the recording light, a semiconductor laser beam having an oscillation wavelength in the range of 500 nm to 900 nm (preferably 650 to 85 nm) is generally used. In the present invention,
A laser beam having a pulse width that is the same as the pit length to be recorded on the information recording medium having the dye recording layer and the reflective layer but shortened by a certain width (PDIF below) is irradiated from the substrate side to provide information. In this recording method, information is recorded under conditions such as the thickness of the dye recording layer and the shortening width of the laser pulse during recording that satisfy the above formula (1).

The information recorded as above can be reproduced by rotating the information recording medium at the same constant linear velocity as above, irradiating semiconductor laser light from the substrate side, and detecting the reflected light. .

FIG. 2 shows an information recording medium 10 for showing the layer thickness of the recording layer.
FIG.

d represents the layer thickness of the recording layer 2 at the bottom of the group, and dl represents the layer thickness of the land (between groups) portion of the recording layer 2. Therefore, α below can be expressed as (layer thickness at the bottom of the recording layer group)/(layer thickness at the land portion of the recording layer), that is, d/dl. d□ is the minimum value of the recording layer thickness at which the reflectance becomes maximum.

This value is generally a value specific to the dye, but different types of dye may have the same value, and the same dye may have different values depending on the formation method.

Therefore, in the present invention, it is defined as a characteristic of the recording layer as described above.

In Figure 3, a) shows a pit to be recorded, b) shows a pulse having the same pulse width (ns: nanoseconds) as the pit to be recorded, and C) shows a pulse when actually recording. A modulated pulse is shown.

In a), there are two types of pits p with different pit lengths to be recorded.
t (ns) and pt' (ns) are shown.

In b), a pulse with a pulse width of pmd (ns) and a pulse with a pulse width of I'+ad' (ns) are shown, in which the laser emitted from the light source is modulated with the recording signal. These are two types of pit pt.
(ns) and pt' (ns), and have the same pit length and pulse width.

C) the pulse shown in b) is further modulated;
The actually recorded modulation pulse is shown. pdIt
(nS) is the shortening width (time) when modulating the original pulse width of the recording signal to the recording pulse width, and PLd (ns
) is the pulse width modulated by shortening the time of the above p ad (ns) by pdif (nS), and ρLd' (nS) is also the pulse width of the above p, d" (ns)
is the similarly modulated pulse width. Then, pits are formed in the recording layer corresponding to this pulse width.

The value of pH1d-pLd and the value of I)ad'-pLd' are also equal to pdif(r+s), and the shortening width is I)dir (nS) for all pulse widths, which are preferably the same. However, in the present invention, 1) dir may be 0. Further, as long as the following formula (I) is satisfied, the shortening width 1) dlt may be different for each pulse width. pmd@(ns) shown in the following equation (1) is the minimum pulse width of the original recording signal, which is p in b) of FIG. d, CD format EFM signal (3T to 11T
) corresponds to 3T.

In the optical information recording method of the present invention, the layer thickness of the recording layer of the recording medium shown in FIG. 2 and the pulse width corresponding to the pit length to be recorded by the laser during recording shown in FIG. 3 are as follows. Formula (I).

1" ad, 10, 3... (1) [However, d (μm) represents the layer thickness at the bottom of the group of the recording layer, and d and a (μm) represent the thickness at which the reflectance from the group reaches its maximum. represents the minimum layer thickness at the group bottom of the recording layer, α
represents the ratio of the layer thickness at the group bottom of the recording layer to the layer thickness at the land portion of the recording layer, and pchrf (nS) is the ratio when a pulse width of the same length as the pit length to be recorded is modulated to the pulse width during recording. represents the shortened constant width of and pwadw+
(nS) represents the minimum pulse width among pulse widths of the same length as the pit to be recorded] It is necessary to satisfy the following.

In the above formula (I), d (μm) is 005 to 0.
The range of 25 μm is preferable, and the above dma (μm) is 0
．． A range of 0.04 to 0.30 μm is preferred. In addition, the above α
is preferably in the range of 0.9 to 3.0.

The upper m2pdtr (nS) preferably has a range of 0 to 400 ns, and the Peds (nS) preferably has a range of 40 to 900 ns. The present invention can be applied even when the pulse width during laser recording is not shortened as long as the above formula (1) is satisfied; in this case, pd+v becomes O.

Further, it is preferable that the information to be recorded is an EFM signal in CD format. Furthermore, in the case of an optical drive for CD-DRAW, I) di f/pmdm is 0
By setting the optical disc or optical drive to satisfy ≦ pdif / p + dm < 1 / 2,
This is preferable because the servo gain of the three beams becomes large.

In the present invention, information is recorded on an information recording medium having the thickness of the dye recording layer described above by irradiating a laser having the modulated (shortened) pulse width as described above from the substrate side. Therefore, if the modulated (shortened) pulse width of the laser during recording of the optical drive used is known, the maximum reflectance layer thickness of the dye to be used can be determined by experiment. By substituting the above equation (1), the layer thickness of the dye recording layer of the information recording medium for better recording can be determined. As a result, if an information recording medium having the above-mentioned recording layer is manufactured, good recording (in particular, excellent jitter) can be performed with an optical drive having a known modulation pulse width.

Furthermore, if the maximum reflectance layer thickness and layer thickness of the dye recording layer of an optical disk are known, the modulation pulse width for good recording on the information recording medium can be determined from the above equation (1). A suitable optical drive can be found by adjustment, improvement, etc.

In the present invention, it is sufficient that the layer thickness of the dye recording layer, the maximum reflectance layer thickness, and the shortened pulse width satisfy the above formula (1). Therefore, any type of dye used in the recording layer and any method for forming it may be used. As mentioned above, the maximum reflectance layer thickness may be the same even if the type of dye is different, and it also differs depending on the formation method such as coating, so the above layer thickness as a recording layer is It is sufficient if formula (1) is satisfied.

Therefore, by using the recording method of the present invention, an optical disc for any optical drive can be manufactured.

The reason can be considered as follows.

That is, generally, the formation of pits in a metal recording layer according to information is performed by irradiating a laser beam with a pulse width shorter than the pulse width corresponding to the pit length of the recording signal, as described above. This is done because the pit shape tends to expand due to heat conduction, so it is necessary to balance the shape so that good regeneration can be achieved. However, in optical discs that have a basic structure in which a dye recording layer and a reflective layer are formed in this order on a substrate, the degree of absorption of laser energy tends to vary due to differences in the layer thickness of the dye recording layer. This is believed to be because pits of the same shape cannot be obtained on recording layers of different thicknesses even if laser irradiation with a pulse width is performed, and good reproduction cannot be performed.

Therefore, by adjusting the pulse width and the recording layer thickness using the above formula (1), it is possible to create an optical disc that is compatible with the optical drive, and an optical disc that has wide applicability.

The information recording medium used in the recording method of the present invention can be manufactured, for example, by the method described below.

The disk-shaped substrate of the present invention can be arbitrarily selected from various materials used as substrates for conventional information recording media. Examples of the substrate material of the present invention include glass; polycarbonate; acrylic resin such as polymethyl methacrylate; vinyl chloride resin such as polyvinyl chloride and vinyl chloride copolymer; epoxy 4!1i; amorphous polyolefin and polyester. I can,
They may be used together if desired. Note that these materials can be used in the form of a film or as a rigid substrate. Among the above materials, polycarbonate is preferred from the viewpoint of moisture resistance, dimensional stability, and cost.

The surface of the substrate on which the recording layer is provided has improved flatness,
An undercoat layer may be provided for the purpose of improving adhesive strength, improving sensitivity, and preventing deterioration of the recording layer. Examples of materials for the undercoat layer include polymethyl methacrylate, acrylic acid/methacrylic acid copolymer, styrene/maleinate anhydride copolymer, polyvinyl alcohol, N-methylolacrylamide, styrene/vinyltoluene copolymer, and chlorosulfonated polyethylene. , nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, boimide, vinyl acetate/vinyl chloride copolymer, ethylene/vinyl acetate copolymer, polyethylene, polypropylene, polycarbonate, and other polymeric substances: and silane coupling agents, etc. organic substances can be mentioned.

The undercoat layer is formed by, for example, dissolving or dispersing the above substances in a suitable solvent to prepare a coating solution, and then applying this coating solution to the substrate surface using a coating method such as spin code, dip coating, or extrusion coating. can do. The layer thickness of the undercoat layer is generally o, oos ~ 20
It is in the range of μm, preferably in the range of 0.01 to 10 μm.

On the disk-shaped substrate (or undercoat layer) of the present invention, pits representing information such as address signals, music information, etc. and tracking groups (pregrooves) are formed. When using a resin material such as polycarbonate, it is preferable to form pits and groups directly on the substrate by injection molding or extrusion molding the resin material.

Further, the formation of groups etc. may be performed by providing a pre-groove layer. As the material for the pregroove layer, a mixture of at least one monomer (or oligomer) of acrylic acid monoester, diester, triester, and tetraester and a photopolymerization initiator can be used. The pre-groove layer is formed by first coating a mixture of the above acrylic ester and polymerization initiator on a precisely made matrix (stambar), then placing the substrate on top of this coating layer. Then, the liquid layer is cured by irradiation with ultraviolet rays through the substrate or the matrix, thereby fixing the substrate and the liquid phase. Next, by peeling the substrate from the mother mold, a substrate provided with a pregroove layer is obtained.

The layer thickness of the pregroove layer is generally in the range from 0.05 to 100 μm, preferably in the range from 0.1 to 50 μm.

The shape of the pregroove preferably has a depth in the range of 500 to 2500λ, particularly preferably in the range of 500 to 2500λ. Further, the half width is preferably in the range of 0.2 to 0.9 μm, particularly preferably in the range of 0.2 to 0.9 μm.

A recording layer made of a dye is provided on the disk-shaped substrate.

The dyes used in the present invention include, for example, cyanine dyes such as indolenine dyes, imitazoquinoxaline dyes, and indolizine dyes, phthalocyanine dyes, naphthalocyanine dyes, pyrylium/thiopyrylium dyes, and azulenium dyes. pigments, squalirium pigments, N
i, Cr and other metal complex dyes, naphthoquinone/anthraquinone dyes, indophenol dyes, indoaniline dyes, triphenylmethane dyes, triallylmethane dyes, merocyan dyes, oxonol dyes, aminium dyes, etc. Mention may be made of diimmonium dyes and nitroso compounds.

Formation of the dye layer involves adding the above dye, optionally a binder,
Dissolving a metal complex dye or aminium/diimmonium dye (quencher) in a solvent to prepare a coating solution, then applying this coating solution to the substrate surface to form a coating film, and then drying. I can do it.

Examples of the solvent for preparing the dye coating solution include esters such as ethyl acetate, butyl acetate, and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone; halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, and chloroform; Ethers such as tetrahydrofuran, ethyl ether, dioxane, alcohols such as ethanol, n-propatol, impropatol, n-butanol, amides such as dimethylformamide, fluorinated solvents such as 2.2.3.3-tetrafluoropropatol etc. can be mentioned. Note that these non-hydrocarbon organic solvents may contain hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents, as long as the amount is within 50% by volume. good.

The coating solution also contains antioxidants, UV absorbers, plasticizers,
Various additives such as lubricants may be added depending on the purpose.

When a binder is used, examples of the binder include cellulose derivatives such as gelatin, nitrocellulose, and cellulose acetate; natural organic polymeric substances such as dextran, rosin, and rubber; and carbonized materials such as polyethylene, polypropylene, polystyrene, and polyisobutylene. Hydrogen resins, vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl chloride/polyvinyl acetate copolymers, acrylic resins such as polymethyl acrylate, polymethyl methacrylate,
Examples include synthetic organic polymeric substances such as polyvinyl alcohol, chlorinated polyolefins, epoxy resins, butyral resins, rubber derivatives, and initial condensates of thermosetting resins such as phenol/formaldehyde resins.

Examples of the coating method include a spray method, a spin code method, a dip method, a roll coat method, a plate coat method, a doctor roll method, and a screen printing method.

When a binder is used as a material for the dye layer, the ratio of the dye to the binder is generally 0.01 to 99% (weight ratio).
It is preferably in the range of 1.0 to 95% (weight ratio).

The dye layer may be a single layer or a multilayer, but its layer thickness is generally in the range of 0.01 to 0.55 .mu.m, preferably in the range of 0.05 to 0.25 .mu.m.

An intermediate layer made of chlorinated polyolefin, nitrocellulose, or fluororesin may be provided between the recording layer and the substrate.

A reflective layer is provided on the recording layer.

The light-reflective substance that is the material of the reflective layer is a substance that has a high reflectance to laser light, and examples thereof include Mg, Se,
, Y, Ti%Zr, Hf, ■, Nb, Ta, Cr, Mo
, W, Mn, Re.

Fe, Co, Ni, Ru, Rh,
Pd, 1r, Pt, Cu, Ag, Au
, Zn, Cd, Aft, Ga, In,
Si, Ge, Te, Pb, Po, S
Mention may be made of metals and metalloids such as n, Bi, etc. Among these, preferred are Al, Au, Cr and Ni. These substances may be used alone, or in combination of two or more or as an alloy.

The reflective layer can be formed on the substrate by, for example, vapor depositing, sputtering or ion-blading the light reflective material described above. The thickness of the reflective layer is generally in the range of 100 to 3000λ.

Further, it is preferable that a protective layer is provided on -F of the reflective layer for the purpose of physically and chemically protecting the recording layer and the like. This protective layer may also be provided on the side of the substrate where the recording layer is not provided for the purpose of increasing scratch resistance and moisture resistance.

Examples of materials used for the protective layer include 5iO1S1
Examples include inorganic substances such as 02, -MgF2.5nOz and S 13 Na, and organic substances such as thermoplastic resins, thermosetting resins, and υV curable resins.

The protective layer is formed by applying a film obtained by pressing plastic, for example, onto the recording layer (reflection layer) and/or the film through an adhesive layer.
Alternatively, it can be formed by laminating it on a substrate. Alternatively, it may be provided by methods such as vacuum deposition, sputtering, and coating. In addition, thermoplastic resin,
In the case of a thermosetting resin, it can also be formed by dissolving these in a suitable solvent to prepare a coating solution, then applying this coating solution and drying it. In the case of LIV curable resin, it can also be formed by preparing a coating liquid as it is or by dissolving it in an appropriate solvent, applying this coating liquid, and curing it by irradiating it with UV light. Various additives such as antistatic agents, antioxidants, and UV absorbers may be further added to these coating liquids depending on the purpose. When coating the protective layer forming material directly on the recording layer, coat polybutadiene or the like on the recording layer to protect the recording layer from the dissolving action of the coating liquid for the protective layer (in this case, use a solvent that does not dissolve the recording layer). It is preferable to provide the intermediate layer by using

The intermediate layer may be formed by depositing a thin film of metal or the like.

The thickness of the protective layer is generally in the range of 0.1 to 100 μm.

Furthermore, instead of forming a protective layer on the recording layer, the recording layer may be protected by providing a plastic film on the recording layer by fusing it at the inner and outer peripheries of the substrate.

In the present invention, the information recording medium may be a single board having the above-mentioned structure, or alternatively, two substrates having the above-mentioned structure may be placed facing each other so that the recording layer is on the inside, and adhesive or the like is used. By joining, a laminated type recording medium can also be manufactured. Alternatively, an air sandwich type recording medium is manufactured by using a substrate having the above configuration as at least one of two disc-shaped substrates and joining them via a ring-shaped inner spacer and a ring-shaped outer spacer. You can also.

The information recording medium used in the present invention can be manufactured by the method described above.

Examples and comparative examples of the present invention are described below. However, each of these aspects does not limit the invention.

[Preparation of information recording medium A] 1.7 g of the following indolenine dye and the following dye (IRG-023, manufactured by Nippon Kayaku ■).

0,. A dye coating solution was prepared by dissolving 17 g of 2,2,3,3-tetrafluoropropanol in 100 ml of 2,2,3,3-tetrafluoropropanol while applying ultrasonic waves for 1 hour.

Polycarbonate board (diameter: 120mm, inner diameter: 15
The above pigment coating liquid was applied through the nozzle of a spinner onto the surface (mm, thickness + 1.2 mm, refractive index = 1.58, track pitch: 1.6 μm, group width 20.45 μm, loop depth: 900λ). Apply for 5 seconds at a rotational speed of 200 rpm, and gradually increase the rotation speed by 50 rpi+ per second until the final rotation speed is 1000 rpm after 16 seconds.
B, hold this state for 30 seconds and dry, and the layer thickness within the group is 14001 and the layer thickness between the groups is 10
A dye recording layer of 00λ was formed.

Ar
Sputtering was performed under conditions of a pressure of 2 Pa and a power of 200 W to form a reflective layer with a layer thickness of xoooX up to a substrate outer diameter of 118 mm.

Further, on the reflective layer, apply the above-mentioned coating liquid for forming a protective layer (product name: 3070, which is an ultraviolet curable resin, manufactured by ThreeBond).
Using the spin code method, coating was started at a rotational speed of 200 rpm, maintained for 5 seconds to complete the coating, and the rotational speed was increased to a final rotational speed of 1500 rpm+m for 30 seconds for drying. Next, the coated layer was irradiated with ultraviolet rays (200 W/cm2 mercury lamp for 10 seconds) to form a protective layer having a layer thickness of 2 μm. The layer thickness of the outer peripheral edge of the protective layer was 2 to 10 μm.

In this way, an information recording medium A was manufactured in which a dye recording layer, a reflective layer, and a protective layer were provided on a substrate.

[In the preparation of information recording medium B [Creation of information recording medium A], 1.7 g of dye A in the dye coating liquid was changed to 2.3 g, and 80.17 g of dye was changed to 0.23 g.
Information was prepared in the same manner as [Preparation of information recording medium A] except that the layer thickness of the obtained dye recording layer, that is, the inner group layer thickness was changed from 1400 λ to 1900 λ and the intergroup layer thickness was changed from 100 OX to 1350 λ. A recording medium was manufactured.

[Creation of information recording medium C] In [Creation of information recording medium A], 1.7 g of dye A in the dye coating liquid was changed to 2.0 g, and 317 g of dye BO was changed to 0.20 g.
g, and the layer thickness of the obtained dye recording layer, that is, the inner group layer thickness was changed from 1400 to 1750X, and the intergroup layer thickness was changed from 1000^ to 1250X, in the same manner as [Preparation of information recording medium A]. An information recording medium was manufactured.

[Creation of information recording medium] In [Creation of information recording medium A], instead of using a polycarbonate substrate with a group depth of 900 mm, a polycarbonate substrate with a group depth of 15 oz and the other dimensions being the same was used, and the dye coating was applied. 1.7 g of dye A in the liquid was changed to 2.6 g of dye C below, and 80.17 g of dye was changed to 0.26 g, and the layer thickness of the obtained dye recording layer, that is, the inner layer thickness of the group, was changed from 1400 to 2000 and the group An information recording medium was manufactured in the same manner as [Preparation of information recording medium A] except that the interlayer thickness was changed from 1000X to 11801X.

Dye C: C.I.O.

[Creation of information recording medium E] In [Creation of information recording medium], 2.2 g of dye C2, 6 g of the dye coating liquid and 0.22 g of dye 80.26 g were added.
[Information recording medium was prepared in the same manner as above, except that the layer thickness of the obtained dye recording layer, that is, the inner group layer thickness was changed from 2000λ to 1700X, and the intergroup layer thickness was changed from 1180λ to 1000X. A recording medium was manufactured.

[Recording of the information recording medium] Using an optical disc evaluation machine (DDUloooo, manufactured by Pulstec Kogyo ■) equipped with an optical head for optical discs with a wavelength of 780 nm and NAO and S, record the information recording medium (A-E) in CD format. EFM signal at a constant linear speed of 1.2 m/
The laser emission pulse during self-recording was recorded using the following pulses at a recording power that minimized jitter in minutes.

1) Pulse 1: EFM signal (3T: 694.2ns) with the same pulse width (so-called duty 50% recording) 2) B) Li miss: Pulse width is set to 0 from the EFM signal
．． Pulse width shortened by 5 clocks (115,7ns) 3) Pulse 3: Pulse width shortened by 1 clock (231,4ns) from the EFM signal Pulse 4: Pulse width shortened by 1 clock from the EFM signal
．． Pulse width shortened by 5 clocks (347.1 ns) [Comparative Example 1] Information was recorded on the above information recording medium A by a recording method using the above pulse 1 to create a recorded information recording medium A.

[Example 1] Information was recorded on the information recording medium A by the recording method using the pulse 2 described above to create a recorded information recording medium A.

[Comparative Example 2] Information was recorded on the information recording medium A by the recording method using the pulse 3 described above to create a recorded information recording medium A.

[Comparative Example 3] Information was recorded on the above information recording medium A by the recording method using the above pulse 4 to create a recorded information recording medium A.

The recorded information recording medium A on which recording was performed using the above four types of pulses was evaluated.

[Evaluation of Recorded Information Recording Medium A] 1) Jitter during playback Using the above optical disk evaluation machine (DDUlooO, manufactured by Pulstec Kogyo ■), the recording signal of the above information recording medium was evaluated.
Reproduction was performed at a constant linear velocity of 1.2 m/sec and a reproduction power of 0.5 mW. The obtained RF reproduction signal is connected to a pulse jitter counter (TR5835, manufactured by Atpan Test) using a reproduction signal output AC coupling (window width 2 lower side 575n).
s.

Upper side 575ns, polarity: 10, slide level: OV)
Jitter was measured under these conditions.

The above measurement results are shown in Table 1.

Margins below Table 1 Recording medium A A A A m Ujidem Pulse 1 Pulse 2
Pulse 3 Pulse 4 outside yyujl" (
X) 900 900 900
900g y 11J! 014
0゜14 0,14 0.14(
d) (μm) iノJ O, 140, 140, 140, 14
(d,,,)(μ[11) dan 1.4 1.4
1.4 1.4 Red-spotted 3
47. + 234.1 115.7 0.0(1
) str) *) Stomach, ku'1 0,27 0.00
-0.18 -0.43<-0,15≦X/
d≦+015) Jitter (ns) 32 23
30 32 X in Table 1 above is the formula (1)
Represents the inside.

Next, recording was performed on the information recording medium B using the above four types of pulses in the same manner as on the information recording medium A.

[Comparative Example 4] Information was recorded on the information recording medium B by the recording method using the pulse 1 described above to create a recorded information recording medium B.

[Comparative Example 5] Information was recorded on the information recording medium B by the recording method using the pulse 2 described above to create a recorded information recording medium B.

[Example 2] Information was recorded on the above-mentioned information recording medium B by a recording method using the above-mentioned pulse 3 to create a recorded information recording medium B.

[Example 3] Information was recorded on the information recording medium B by the recording method using the pulse 4 described above to create a recorded information recording medium B.

The recorded information recording medium B on which recording was performed using the above four types of pulses was evaluated in the same manner as the recorded information recording medium A.

The above measurement results are shown in Table 2.

Margin below Table 2 Recording medium BB BB 翫JL 方j人 Pulse 1 Pulse 2
Pulse 3 Pulse 42 Enji) lK'
(λ)9[10900900900g&-)JJ
O, 190, 190, 190, 19 (d) (μ
m) 1 dog layer J O, 140, +4 0.14
0.14 (d,,,) (μm) 1.4 +, 4
1.4 1.4i collapse 1” decoy 347.1 234.1 11
5.7 0.0 (ps+t) *2←2ku”1 0.45 0.26
0.13 -0.13 (-0,15≦X/
d≦+0.15) Jitter (ns) 40 3
3 28 27 Next, recording was performed on the information recording medium C using the four types of pulses described above in the same manner as on the information recording medium A.

[Comparative Example 6] Information was recorded on the information recording medium C by the recording method using the pulse 1 described above to create a recorded information recording medium C.

[Comparative Example 7] Information was recorded on the information recording medium C by the recording method using the pulse 2 described above to create a recorded information recording medium C.

[Example 4] Information was recorded on the information recording medium C by the recording method using the pulse 3 described above to create a recorded information recording medium C.

[Example 5] Information was recorded on the information recording medium C by the recording method using the pulse 4 described above to create a recorded information recording medium C.

The recorded information recording medium C on which recording was performed using the above four types of pulses was evaluated in the same manner as the recorded information recording medium A.

The above measurement results are shown in Table 3.

Ran■Kihin c c c c 5 ji vertical pulse 1 pulse 2
Pulse 3 Pulse 4 Higokyu 1 (again) 900
900 900 900 guyyujJJ
O, 1750, 1750, 1750, 17
5(d) (μm) iUJjJ O, 140, 140, 140,
L4 (d,,,,,) (μm) 1.1 1.4
1.4 1.4 New Year's Eve is the 1st year 347. + 234.1 1
15.7 0.0 (pd, f) *y2/]down 0.4] 0 211
0.03 -0.12(-0,] 5
≦X/d≦+015) Jitter (ns) 36
3] 25 29 Next, five recordings were performed on the information recording medium using the above four types of pulses in the same manner as for information recording medium A.

[Comparative Example 8] Information was recorded on the above information recording medium by the recording method using the above pulse 1 to create a recorded information recording medium.

[Example 6] Information was recorded on the above information recording medium by the recording method using the above pulse 2 to create a recorded information recording medium.

[Comparative Example 9] Information was recorded on the above information recording medium by the recording method using the above pulse 3 to create a recorded information recording medium.

[Comparative Example 10] Information was recorded on the above information recording medium by the recording method using the above pulse 4 to create a recorded information recording medium.

The recorded information recording medium on which recording was performed using the above four types of pulses was evaluated in the same manner as recorded information recording medium A.

The above measurement results are shown in Table 4.

Recording medium D D D D 21 Table 2] Pulse 1 Pulse 2
Pulse 3 Pulse 44N 211 sly (X) 1600 +600 1
5DO1IliOO previous = U kidney J O, 20
0,200,200,20(d)(μm) Mutual contact Wγ 0.20 0.20
0.20 0.20(d,,,)<μm
) Dan 1.7 1.7
1.7], 7i New Year's Day 1J Tsukasa 347.1 234. +1
15.7 0.0(Illd+f) *'! Llj↓ 0.47 0.07
-0.31 -0.70 (-0,15≦X
/d≦+Q, 15) Jitter (ns) 31
25 30 32 Next, recording was performed on the information recording medium E using the above four types of pulses in the same manner as on the information recording medium A.

[Comparative Example 11] Information was recorded on the information recording medium E by the recording method using the pulse 1 described above to create a recorded information recording medium E.

[Example 7] Information was recorded on the information recording medium E by the recording method using the pulse 2 described above to create a recorded information recording medium E.

[Comparative Example 12] Information was recorded on the information recording medium E by the recording method using the pulse 3 described above to create a recorded information recording medium E.

[Comparative Example] 3] Information was recorded on the information recording medium E by the recording method using the pulse 4 described above to create a recorded information recording medium E.

The recorded information recording medium E on which recording was performed using the above four types of pulses was evaluated in the same manner as the recorded information recording medium A.

The above measurement results are shown in Table 5.

II 7 12 13 Recording medium
EE E E
1600 1600 +600):! UXjJ
PLM O, 170, 17 [1, 170, 1
7(d) (μm) Shinoguta 4jv O, 200, 200, 20
0,20(d,,a)(μm) 1.7 1.7
1.7 1. Full E Kuzuritan 1” 347.1 234.1 11
5.7 f), 0(pd・f) ”Ll2d O,37-0,08-0,5
4-1,00 (-0,15≦X/d≦÷0.15)
Jitter (ns) 30 24 30
33 As is clear from Tables 1 to 5 above, it can be seen that the signals obtained by the recording method of the present invention are superior to jitter during reproduction and have good reproduction characteristics.

When information is recorded using a combination of recording layer thickness and pulse width that does not satisfy the formula (I) of the present invention (comparative example), the jitter is large and the reproduction characteristics cannot be said to be good.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view for explaining an example of the optical information recording method of the present invention. FIG. 2 is a partially enlarged sectional view of the information recording medium IO. FIG. 3 shows a) a pit to be formed, b) a pulse having the same pulse width as the length of the pit, and C
) is a diagram showing pulses when actually recording. Disc-shaped base: 1 Dye recording layer: 2 Reflective layer: 3 Protective layer 4 d is the layer thickness at the bottom of the group of the recording layer 2 d1: is the layer thickness d of the runt (between groups) of the recording layer 2 (
μl): is the layer thickness of the recording layer at the bottom of the group pmd (ns)
, P+ad' (ns): The pulse width pdrt (nS) of the signal during recording is the shortened constant width p+, c+ when modulated from the pulse width of the same length as the pit width to be recorded to the pulse width during recording. (ns) : pwd(ns) 6)l
Pulse width shortened by lld+r (ns) 1) Ld' (ns): pmd' (ns) is pd
Pulse width with time reduced by ir (nS) Patent applicant: Fuji Photo Film Co., Ltd. Representative: Yasushi Yanagawa, patent attorney Figure 3: Time

Claims (1)

[Claims] 1. Information is recorded by irradiating a laser from the substrate side onto an information recording medium in which a recording layer made of a dye and a reflective layer made of metal are provided in this order on a disc-shaped substrate having pregrooves, and information can be recorded using a laser. In this optical information recording method, the pulse width corresponding to the pit length to be recorded is determined by the following formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・(I ) [However, d (μm) represents the layer thickness at the bottom of the groove of the recording layer, d_m_a (μm) represents the minimum layer thickness at the bottom of the groove of the recording layer where the reflectance from the groove becomes maximum,
α represents the ratio of the layer thickness at the groove bottom of the recording layer to the layer thickness at the land portion of the recording layer, and P_d_i_f (ns) is the pulse width of the same length as the pit length to be recorded, which is modulated to the pulse width during recording. and P_m
d_m(ns) represents the minimum pulse width among pulse widths having the same length as the pit length to be recorded] An optical information recording method characterized by having a pulse that satisfies the following.