JPH11162009A - Optical recording medium and optical recording and reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium which has high reflectivity to light of a prescribed wavelength and an excellent signal output characteristic and allows recording and reproducing without reading-out destruction and an optical recording and reproducing method. SOLUTION: This optical recording medium has the constitution sequentially formed with at least a recording layer 2 contg. dyestuffs for absorbing recording light, an intermediate layer 3 and a reflection layer 4 on a transparent substrate 1 and satisfies (ε=ε1 -iε2 ), ε1 >=4 and ε2 >=5 or satisfies 2>=ε1 0 and ε2 <=1 when the real part of the complex specific dielectric constant ε of the recording layer of recording light and the reproducing waveform of reproducing light is defined as ε1 and the imaginary part thereof as ε2 . The optical recording medium satisfies (ε'=ε'1 -iε'2 ), ε'1 >=4 and ε'2 >=5 or satisfies 2>=ε'1 >=0 and ε'2 <=2 when the real part of the complex specific dielectric constant ε' of the recording layer at the reproducing waveform of the reproduction light below the recording wavelength is defined as ε'1 and the imaginary part thereof as ε'2 . This optical recording and reproducing method uses such media.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium and an optical recording / reproducing method, and more particularly, to an optical recording medium using an optical recording medium to which an intermediate layer is added.

[0002]

2. Description of the Related Art As an optical recording medium for reproducing information by a laser beam, a read-only optical disk (hereinafter, referred to as a CD or CD-ROM) is widely used for music reproduction and information terminals.

In this optical recording medium, information is recorded by providing an uneven pit array on one side of a transparent substrate having a thickness of 1.2 mm, and a reflective film of aluminum, gold or the like is formed thereon by sputtering or vapor deposition. It is common to have a configuration in which a protective film is coated thereon.

This optical recording medium has a wavelength of 780n.
When the semiconductor laser light of m is incident through the transparent substrate and is reflected by the reflection film, the change in the reflectance corresponding to the unevenness of the pre-recorded information pit is read, and the pre-recorded information is reproduced. Is what you do.

However, CDs and CD-ROMs are read-only media and do not have an editing function.

Therefore, as recordable optical recording media, write-once optical disks (hereinafter, referred to as CD-R), rewritable optical disks (hereinafter, referred to as phase change type), etc., which can be recorded only once, have been developed and put into practical use. Such recordable optical discs are provided with a playback function of CD, CD,
-Compatible with ROM.

[0007] Due to this reproduction compatibility, an information terminal device equipped with a CD-ROM reproduction device can reliably reproduce recorded CD-R information.

By providing a CD-ROM device with a CD-R recording function, it is possible to provide an information recording device having the same capacity as a CD-ROM and having a capacity of 650 Mbytes per sheet.

For this reason, in recent years, in particular, CD-Rs have come into widespread use as information recording media.

Further, when editing the information content of the CD-ROM, it is necessary to test-produce the CD-ROM.

[0011] Even in such an authoring business as an editing business, a CD-R compatible with a CD-ROM playback function is used.
It is an indispensable key device in the trial operation of CD-ROM.

Here, in the case of CD-Rs, those in which chalcogenite compounds such as Te, rare earth metal compounds, porphyrin compounds, cyanine compounds and naphthalocyanine compounds are applied to the recording layer have been put to practical use. I have.

In recent years, especially for CD-Rs, those using an organic compound such as a dye for the recording layer have become mainstream from the viewpoints of price, pollution-free properties, and complete compatibility of reproduction characteristics with the aforementioned CD-ROM. In this configuration, a laser beam having a relatively large output is made incident in correspondence with an information signal, and the incident laser light is absorbed by an organic compound of the recording layer and converted into heat, thereby causing a chemical reaction of the recording layer. This causes a change or a change in the geometrical shape, and causes additional information to be added.

Further, the information recorded in this manner is irradiated with a relatively low-power laser beam of a fixed value or less to recognize a change in reflectivity, specifically, a change in the amount of reflected light. Information will be reproduced.

Examples of the organic compound used in such a recording layer include, for example, Japanese Patent Application Laid-Open No. 1-145188 for a porphyrin compound, and particularly Japanese Patent Application Laid-Open Nos. 3-1382 and 3-1382 for a tetraazaporphyrin compound. JP-A-13384 and JP-A-7-276804, and the like. Further, phthalocyanine compounds are disclosed in JP-A-2-276676 and the like, and naphthalocyanine compounds are disclosed in JP-B-4-20945. ing.

On the other hand, the development of next-generation high-density optical recording media is actively progressing. A major feature of this next-generation high-density optical recording medium is that the wavelength of laser light is 620 to 690 nm.
The recording density is improved by shortening the wavelength and shortening the interval and length of the track pitch, and 3 to 10 G, which is 5 to 10 times larger than the recording capacity of the current CD-ROM of 650 Mbytes.
It enables handling of digital data of bytes.

However, according to the current standard, this high-density optical recording medium is also used for reproduction only and has no editing function.

For this reason, a recordable high-density write-once optical disc having an editing function has been energetically studied. In particular, it is desired to use an organic material for the recording layer as in the case of the CD-R. I have.

As a specific disclosure, a recording medium in which the light absorption characteristics of a cyanine compound is shifted to a short wavelength is disclosed in JP-A-6-199045, and an indoline imine dye is added to a recording layer. The applied recording medium is disclosed in JP-A-5-305771, JP-A-4-252.
272, etc.

While such a high-density optical recording medium has been developed, a CD-R (hereinafter, referred to as a CD-R) which can be reproduced by a high-density recording-compatible player has been used because of its compatibility with conventional systems which have already been widely used. , CD-R2).

[0021] Conventional CDs and CD-ROMs have a small wavelength dependence of reflectivity, and can be reproduced by players capable of high-density recording.

[0022]

However, the conventional CD-R having a dye in the recording layer has a large wavelength dependence of the reflectance due to the large wavelength dependence of the optical constant of the dye. It is difficult to achieve both recording and reproduction with a CD, CD-ROM player and reproduction with a high-density recording compatible player.

In consideration of this point, for example, Japanese Patent Application Laid-Open No. Hei 8-2
In JP-A-63872, JP-A-8-263873 and JP-A-8-31010, the refractive index, extinction coefficient and film thickness of the light absorbing layer are set in appropriate ranges according to different wavelengths. The reflectance with a near-infrared laser having a wavelength of 770 to 830 nm is 65% or more, and a wavelength of 620
An optical recording medium CD-R2 satisfying a reflectance of 15% or more with a red laser having a wavelength of ｎｍ690 nm has been proposed, but it is not sufficient in terms of recording / reproducing characteristics.

According to the present invention, at least a transparent substrate is provided.
Using an optical recording medium in which a recording layer containing a dye that absorbs recording light, an intermediate layer, and a reflective layer are sequentially formed, good recording and reproduction for light of a predetermined wavelength, that is, high reflectance and excellent signal An object of the present invention is to provide an optical recording medium and an optical recording / reproducing method which have output characteristics and are capable of recording / reproducing without destruction of reading / reading by repeated reproduction.

[0025]

Means for Solving the Problems In order to solve the above problems,
The present invention provides a transparent substrate on which at least recording light is absorbed.
Recording layer, intermediate layer, and reflective layer containing
Recording wavelength of recording light and reproduction wave of reproduction light
The real part of the complex relative permittivity ε of the recording layer₁,
The imaginary part is ε_Two(Ε = ε₁-iε_Two), Ε₁, Ε_TwoBut,
ε₁≧ 4 and ε_TwoSatisfies ≧ 5 or 2 ≧ ε₁≧ 0 and ε_Two
An optical recording medium satisfying ≦ 1 or less than the recording wavelength of the recording light.
Of the complex relative permittivity ε 'of the recording layer at the reproducing wavelength of the reproducing light
The real part is ε ' ₁, The imaginary part is ε '_Two(Ε ′ = ε ′₁-i
ε '_Two), Ε '₁≧ 4 and ε ′_TwoSatisfies ≧ 5 or 2 ≧
ε '₁≧ 0 and ε ′_TwoOptical recording medium satisfying ≦ 2 and this
This is an optical recording / reproducing method using the method.

Here, the complex relative permittivity ε of the recording layer is obtained from the refractive index n and the extinction coefficient k of the recording layer, where ε ₁ = n ² -k ² and ε ₂ = 2nk, where the relative magnetic permeability μ is 1. More specifically, the refractive index n and the extinction coefficient k of the recording layer are determined from the film thickness dependence of the reflectance and the transmittance of the recording layer formed on the quartz substrate.

With such a configuration, on a transparent substrate,
At least, a recording layer containing a dye that absorbs recording light,
Using an optical recording medium in which an intermediate layer and a reflective layer are sequentially formed,
Provided are an optical recording medium and an optical recording / reproducing method capable of performing good recording / reproducing with respect to light having a predetermined wavelength.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 is a transparent
A substrate and a dye provided on the substrate and absorbing recording light;
Recording layer containing, and an intermediate layer provided on the recording layer
And a reflective layer provided on the intermediate layer.
The recording at a recording wavelength of recording light and a reproducing wavelength of reproduction light.
Let the real part of the complex relative permittivity ε of the layer be ε₁, The imaginary part is ε_TwoAnd when
(Ε = ε ₁-iε_Two), Ε₁, Ε_TwoIs ε₁≧ 4 and ε_Two≧ 5
It is a satisfactory optical recording medium.

With such a configuration, an intermediate layer is provided, and the effect of the intermediate layer and the reflective layer of an optical recording medium of the type utilizing the interference effect due to multiple reflection is maximized, so that good recording and reproduction can be performed.

If the ratio is out of the above range, even if an intermediate layer is provided, the effect is hardly observed, and the reflectance is lowered,
Phenomena such as a disturbance of the reproduction signal waveform occur.

Or a transparent substrate according to claim 2;
Contains a dye that is provided on the substrate and absorbs recording light
A recording layer; an intermediate layer provided on the recording layer;
And a reflection layer provided on the inter-layer, and recording the recording light.
Wavelength and the complex ratio of the recording layer at the reproduction wavelength of the reproduction light
Let the real part of the dielectric constant ε be ε₁, The imaginary part is ε_Two(Ε = ε ₁-
iε_Two), Ε₁, Ε_TwoIs 2 ≧ ε₁≧ 0 and ε_TwoSatisfies ≦ 1
Optical recording medium.

With such a configuration, an intermediate layer is provided, and the effect of the intermediate layer and the reflective layer of an optical recording medium of the type utilizing the interference effect due to multiple reflection is maximized, so that good recording and reproduction can be performed. Outside of this range, even if there is an intermediate layer, the effect is hardly seen, and phenomena such as a decrease in reflectivity and a disturbance in a reproduced signal waveform will occur.

Here, as described in claim 3, ε ₂ ≦ ε ₁
Is preferably satisfied. That is, if these conditions are not satisfied, the absorption of the recording layer alone film is too large, the reflectance and / or the transmittance of the recording layer alone film is reduced, and the interference effect of multiple reflection is reduced. It is not preferable because a drop or a disturbance of a reproduced signal occurs.

And, as described in claim 4, further,
'The real part of the epsilon' complex relative dielectric constant of the recording layer in a reproduction beam of reproducing wavelength of less than a recording wavelength of recording light epsilon _1, the imaginary part epsilon _'2
(Ε ′ = ε ′ ₁ −iε ′ ₂ ), a configuration satisfying ε ′ ₁ ≧ 4 and ε ′ ₂ ≧ 5 may be employed.

With such a configuration, even when a reproduction light having a shorter wavelength than the recording light is used, an intermediate layer is provided, and the effect of the intermediate layer and the reflection layer of the optical recording medium of the type utilizing the interference effect by multiple reflection is obtained. Pull out to the maximum, and good recording and reproduction can be performed.

Further, the real part and the imaginary part of the complex relative permittivity ε ′ of the recording layer at the reproduction wavelength of the reproduction light shorter than the recording wavelength of the recording light are defined as ε ′ ₁ . ′ ₂ (ε ′ = ε ′ ₁ −iε ′ ₂ ), ε ′ ₁ and ε ′ ₂ are 2
The configuration may satisfy ≧ ε ′ ₁ ≧ 0 and ε ′ ₂ ≦ 2.

With such a configuration, even when the reproducing light having a shorter wavelength than the recording light is used, the intermediate layer is provided, and the intermediate layer of the optical recording medium of the type utilizing the interference effect by the multiple reflection.
The effect of the reflective layer is maximized, and good recording and reproduction can be performed.

Alternatively, as described in claim 6, a transparent substrate, a recording layer provided on the substrate and containing a dye that absorbs recording light, and an intermediate layer provided on the recording layer,
A reflective layer provided on the intermediate layer, wherein the real part of the complex relative permittivity ε ′ of the recording layer at the reproduction wavelength of the reproduction light shorter than the recording wavelength of the recording light is ε ′ ₁ , and the imaginary part is When ε ′ ₂ (ε ′ = ε ′ ₁ −iε ′ ₂ ), ε ′ ₁ ≧ 4 and ε ′ ₂ ≧ 5
The optical recording medium may satisfy the following.

With such a configuration, even if the reproducing light having a shorter wavelength than the recording light is used, the intermediate layer is provided, and the intermediate layer of the optical recording medium of the type utilizing the interference effect by the multiple reflection.
The effect of the reflective layer is maximized, and good recording and reproduction can be performed.

Alternatively, as described in claim 7, a transparent substrate, a recording layer provided on the substrate and containing a dye that absorbs recording light, and an intermediate layer provided on the recording layer,
A reflective layer provided on the intermediate layer, wherein the real part of the complex relative permittivity ε ′ of the recording layer at the reproduction wavelength of the reproduction light shorter than the recording wavelength of the recording light is ε ′ ₁ , and the imaginary part is Assuming that ε ′ ₂ (ε ′ = ε ′ ₁ −iε ′ ₂ ), 2 ≧ ε ′ ₁ ≧ 0 and ε ′ ₂
An optical recording medium satisfying ≦ 2 may be used.

With such a configuration, even if the reproducing light having a shorter wavelength than the recording light is used, the intermediate layer is provided, and the intermediate layer of the optical recording medium of the type utilizing the interference effect by the multiple reflection.
The effect of the reflective layer is maximized, and good recording and reproduction can be performed.

Here, in the case where a reproduction light having a wavelength shorter than the recording wavelength of the recording light is used, ε ′ ₂ ≦ ε ′ ₁
Is preferably satisfied.

With such a configuration, even when the reproduction light having a shorter wavelength than the recording light is used, the intermediate layer is provided, and the effect of the intermediate layer and the reflection layer of the optical recording medium of the type utilizing the interference effect by the multiple reflection is used. Pull out to the maximum, and good recording and reproduction can be performed.

In the above, it is preferable that the reflection layer is a metal layer because of its good reflection function.

Further, as in the tenth aspect, a structure having a protective layer outside the reflective layer may be adopted.

On the other hand, the present invention according to the method, as described in claim 11, irradiates the optical recording medium according to any one of claims 1 to 10 with a laser beam having a wavelength range of 770 to 830 nm. An optical recording method for recording information, wherein recording is reliably performed by using a laser beam within such a wavelength range.

According to a twelfth aspect, an optical recording method for recording information by irradiating a laser beam having a wavelength range of 620 to 690 nm using the optical recording medium according to any one of the first to tenth aspects. In this case, the recording is reliably performed by using the laser light within the wavelength range.

Alternatively, the recorded information is reproduced by irradiating the optical recording medium according to any one of claims 1 to 10 with a laser beam having a wavelength range of 770 to 830 nm. In this method, the reproduction is reliably performed by using a laser beam within the above wavelength range.

Alternatively, as in claim 14, claim 1
10. An optical reproduction method for reproducing recorded information by irradiating the optical recording medium according to any one of items 1 to 10 with laser light having a wavelength range of 620 to 690 nm, wherein the laser light within the wavelength range is used. Reproduce reliably.

According to a fifteenth aspect, information is recorded by irradiating a laser beam having a wavelength range of 770 to 830 nm or 620 to 690 nm using the optical recording medium according to any one of the third to seventh aspects. And a wavelength range of 770 to 83
0 nm or 620-690 nm laser light,
An optical recording / reproducing method for reproducing recorded information by irradiating a shorter wavelength than the wavelength of the recording light, wherein the wavelength of the reproducing light is within the wavelength range where the recording light and the reproducing light are applied. If it is shorter than this, the recording and reproduction of information are performed reliably.

That is, the present inventor has determined that an optical recording medium in which at least a recording layer containing a dye that absorbs recording light, an intermediate layer, and a reflective layer are sequentially formed on a transparent substrate has a wavelength in a specific range. In order to achieve good recording and reproduction with respect to light,
As a result of intensive studies, it is very important to control the reflectivity between the substrate and the recording layer, between the recording layer and the intermediate layer, and between the intermediate layer and the reflective layer. 1) effectively utilizing the reflectance of the recording layer by suppressing the transmittance of the recording layer alone film; and (2) effectively utilizing the reflectance of the recording layer other than the recording layer by suppressing the reflectance of the recording layer sole film. It has been found that choosing is an important point.

Based on this point, the physical properties of the recording layer were examined in detail, and as a result, it was found that the relative dielectric constant of the recording layer was a very important parameter.

That is, by setting the real part and the imaginary part of the complex relative permittivity of the recording layer to a specific range with respect to the recording light having a specific wavelength and the reproduction light having the same wavelength, good recording and reproduction can be achieved. Good recording and reproduction can be achieved by setting each of these to a specific range with respect to an optical recording medium capable of reproduction, and further, with respect to recording light having a specific wavelength and reproduction light having a shorter wavelength. A possible optical recording medium has been found, and the present invention has been achieved.

In the above, the material of the substrate is basically required to be transparent at the wavelength of the recording and reproducing light, and more preferably the material having a low thermal conductivity. Specifically, for example, polycarbonate resin, acrylic resin, epoxy resin, glass, amorphous polyolefin and the like can be used.

The substrate may be in the form of a plate, a film or a card, but preferably has a disk shape defined by an appropriate thickness and diameter with respect to the focal point of the optical system of the laser light used as the light source. It is more preferable that a guide groove is provided on one side of the substrate, and a substrate that can be formed by cutting or injection molding is preferable.

The recording layer may be formed directly on the transparent substrate or through another layer, and has an appropriate absorption and heat conversion efficiency with respect to the recording light and a relatively strong recording light. By giving energy, physical and chemical decomposition, alteration,
There is no particular limitation as long as it involves deformation.

Specifically, a dye-based dye is preferable, and examples thereof include a phthalocyanine dye, a naphthalocyanine-based dye, a porphyrin-based dye, a detraazaporphyrin-based dye, a cyanine-based dye, and an azo-based dye. Further, these may include a metal.

The recording layer can be formed by using a spin coating method, a vacuum evaporation method, a sputtering method or the like.

In the spin coating method, a recording layer is formed by dissolving an organic dye in a solvent and dropping the dye solution while rotating a transparent substrate.

This dye solution is preferably adjusted to a dye concentration of 0.5 to 5% by weight, and a solvent for preparing the dye solution can be used as long as it dissolves the dye and is harmless to the transparent substrate.

Examples of the solvent include methyl alcohol, ethanol, propanol, butanol, tetrafluoro alcohol, acetone methyl ethyl ketone, diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, dioxane, methyl acetate, ethyl acetate,
Propyl acetate, butyl acetate, benzene, toluene, xylene, naphthalene, hexane, cyclohexane, methyl chloride, dichloromethane, chloroform, carbon tetrachloride,
Dichloroethane, trichloroethane, 2-methoxyethanol, 2-ethoxyethanol, 2-isopropoxyethanol, acetonitrile, triethylamine, dipropylamine, dimethylformamide, etc .; dye solubility, workability, influence on substrates, economic efficiency Is determined in consideration of

Of course, when a dye solution is prepared by dissolving a dye in an organic solvent, a light stabilizer and an antioxidant may be contained. As the light stabilizer, a metal complex or diimonium salt which is a singlet oxygen quencher, a hindered amine compound, a benzotriazole compound, a benzophenone compound as an ultraviolet absorber, a phenolic antioxidant as a primary antioxidant as an antioxidant, Amine-based antioxidants and secondary antioxidants include organic sulfur-based secondary antioxidants and phosphorus-based secondary antioxidants. These light stabilizers and antioxidants may be used alone or in combination. The amount of the dye added was 100
The amount of the additive is preferably about 0.1 to 200 parts per part.

A resin may be added as a binder to the dye solution. These resins may be nitrocellulose, cellulose phosphate, cellulose sulfate, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose myristate, palmitic acid. Cellulose, cellulose acetate and propionate, cellulose esters such as cellulose acetate and butyrate, cellulose ethers such as methyl cellulose, ethyl cellulose, propyl cellulose, butyl cellulose, polystyrene, polyvinyl chloride, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal,
Vinyl resins such as polyvinyl alcohol and polyvinyl pyrrolidone, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer, copolymer resins such as vinyl chloride-vinyl acetate copolymer, polymethyl methacrylate, polymethyl acrylate, poly Acrylic acid,
Acrylic resins such as polymethacrylic acid, polyacrylamide and polyacrylonitrile, polyesters such as polyethylene terephthalate, poly (4,4-isopropylidenediphenylene-co-1,4-cyclohexylene dimethylene carbonate), poly (ethylene Dioxy-
3,3-phenylene thiocarbonate), poly (4,4
-Isopropylidene diphenylene carbonate-co-terephthalate), poly (4,4-isopropylidene diphenylene carbonate), poly (4,4-sec-butylidene diphenylene carbonate), poly (4,4-isopropylidene diphenylene carbonate) −Block−
Polyacrylate resins such as oxyethylene), polyamides, epoxy resins, phenolic resins, and polyolefins such as polyethylene, polypropylene, and chlorinated polyethylene can be used. These resins can be added in the range of 1 to 1000 parts per 100 parts by weight of the dye.

In order to form a recording layer by the spin coating method, the film thickness is adjusted to a desired thickness by adjusting the dye concentration, the number of rotations, and the rotation time.

When the recording layer is formed by a method such as vapor deposition, it is preferable that the recording layer is vapor deposited at a degree of vacuum of 10 ⁻² Pa or less.

Further, a recording layer can be formed by simultaneously vapor-depositing a light stabilizer, an antioxidant and the like which can be vapor-deposited. In this case, the light stabilizer, antioxidant and the like are selected from the compounds described above. In the vapor deposition, the recording layer dye and the additive may be mixed in a predetermined amount and may be deposited by one heat source, or the additive and the dye may be deposited by separate heat sources.

The intermediate layer preferably has a smaller extinction coefficient than the recording layer, but the extinction coefficient does not necessarily have to be zero.

More specifically, organic materials such as phenolic resins, vinyl alcohol resins, butyral resins, polyimide resins, acrylic resins, silicone resins and copolymer resins thereof, silicon, titanium, zirconium, etc. And inorganic materials such as oxides, nitrides, MgF ₂ , and ZnS.

The reflective layer is made of a material having a high reflectance with respect to the wavelength of the light source used. The material to be used is preferably a metal, and is preferably aluminum, silver, gold, iron, nickel, cobalt, tin, zinc, copper or the like, and these can be used alone or as an alloy. This reflective layer is formed to a thickness of about 10 to 200 nm by a sputtering method or the like.

The protective layer is provided for protecting the recording layer or the reflective layer from scratches and stains and for preservation stability. As the inorganic material, SiO or SiO ₂ can be used. Organic materials include polymethyl acrylate, polycarbonate,
Epoxy resin, polystyrene, polyester resin, vinyl resin, cellulose, aliphatic hydrocarbon resin, aromatic hydrocarbon resin, natural rubber, wax, alkyd resin, drying oil, rosin, etc. Can be used. This protective layer may optionally contain a flame retardant,
Stabilizers, antistatic agents and the like can be added. Further, the resin substrates may be bonded together with an adhesive.

Hereinafter, an optical recording medium of the present invention and an optical recording / reproducing method using the same will be described in detail with reference to each embodiment.

(Embodiment 1) FIG. 1 is an enlarged cross-sectional view of an optical recording medium according to the present embodiment.

In FIG. 1, 1 is a transparent substrate, 2 is a recording layer formed on the transparent substrate 1, 3 is an intermediate layer formed on the recording layer 2, 4 is a reflective layer formed on the intermediate layer 3 , And 5
Is a protective layer formed on the reflective layer 4.

The substrate 1 is a transparent disc-shaped substrate made of polycarbonate, having a thickness of 1.2 mm and a pitch of 1.6.
What was injection-molded into a shape of μm, width 0.5 μm, and depth 50 nm was used.

Next, on this substrate 1, as a recording layer 2,
Typically, tin chloride phthalocyanine represented by the following chemical formula (Formula 1) is used to form a film so as to have an average film thickness of 50 nm by a vacuum deposition method, and polycarbonate is formed thereon as an intermediate layer 3 by a vacuum deposition method. Film thickness 100, 120, 14
Films were formed at 0, 160, 180 and 200 nm.

[0076]

Embedded image

Here, the real part and the imaginary part of the complex relative permittivity of the recording layer 2 are ε ₁ = 17.3 at a wavelength of 780 nm.
4, ε ₂ = 6.71 and ε _{1 at} a wavelength of 760 nm
= 10.37, ε ₂ = 20.74, wavelength 750n
epsilon ₁ = 4.68 in m, an _{ε 2 = 23.32, ε 1 =} 0.17 at a wavelength of 635 nm, an _{ε 2 = 1.78, ε 1 =} 0.92 at a wavelength of 600 nm, epsilon ₂ =
0.82, and ε ₁ = 0.9 at a wavelength of 550 nm.
5, ε ₂ = 0.13.

The optical constant of the intermediate layer 3 is such that the refractive index n4 = 1.59 and the extinction coefficient k4 = 0 at all the wavelengths used here.

Next, a gold thin film having a thickness of 100 nm was formed as a reflective layer 4 on the intermediate layer 3 by sputtering.

Further, an ultraviolet curable resin was applied on the reflective layer 4 by a spin coating method, and was cured by irradiating ultraviolet rays. The cured resin was used as a protective layer 5 to prepare 10 optical recording media.
In addition, the following measured value was made into the average value of ten each.

FIG. 2 shows the results obtained by measuring the reflectance of this optical recording medium at 780 nm incident on the substrate surface of the optical recording medium in accordance with the thickness of the intermediate layer 3.

According to FIG. 2, this optical recording medium has a recording layer 2 having an extinction coefficient of 0.79, which is considerably large.
It can be seen that the intermediate layer 3 has an appropriate reflectance over a wide range of 100 to 200 nm in thickness, specifically a value in the range of about 65 to 75%.

Further, since the reflectance changes gradually with respect to the thickness of the intermediate layer 3, it is understood that the process management of the film formation is relatively easy.

The optical recording medium has a wavelength of 78 nm.
Using a semiconductor laser of 0 nm, a linear velocity of 1.2 m / sec
c) An EFM modulation signal was recorded at a recording laser power of 8 mW, and the recorded signal was reproduced by a 780 nm semiconductor laser of 0.5 mW.

In each case, the reflectance at the recording portion was reduced, the modulation was sufficiently large, the jitter was good, and almost no distortion was observed in the waveform of the recording / reproducing signal.

This is because at a wavelength of 780 nm, ε ₁
And it is considered because it satisfies epsilon ₂ conditions.

Further, a signal recorded in the same manner is
As a result of reproducing with an output of 0.5 mW of a semiconductor laser of nm, the reflectance was 40% or more and the jitter was good.

It is considered that this is because at the wavelength of 635 nm, at least the conditions of ε ₁ and ε ₂ are satisfied.

Further, the signal recorded in the same manner is
As a result of reproducing with an output of 0.5 mW of a semiconductor laser of nm, the reflectance was 40% or more and the jitter was good.

This is presumably because the conditions of ε ₁ and ε ₂ are satisfied at a wavelength of 600 nm.

However, comparing the reproduction characteristics reproduced at a wavelength of 635 nm with the reproduction characteristics reproduced at a wavelength of 600 nm,
Although the latter was excellent, if it was reproduced at a wavelength of 600 nm, not only the epsilon ₁ and epsilon ₂ of each condition epsilon ₂
It is considered that the condition of ≦ ε ₁ was satisfied.

The reflectance of the optical recording medium having the above structure at 760 nm incident on the substrate surface is 60 to 70%, and a semiconductor laser having a wavelength of 760 nm is used for these optical recording media to obtain a linear velocity of 1.70. 2m / sec, recording laser power 8
An EFM modulated signal is recorded at mW, and the recorded signal is
When the data was reproduced with a semiconductor laser of 60 nm and 0.5 mW, the reflectance at the recording portion was reduced in each case,
Although the modulation was taken, it seems that there is no practical problem compared with the result of 780 nm, but the result was inferior.

This is because at the wavelength of 760 nm, ε ₁
<Because it is epsilon _2, presumably because that does not satisfy the conditions between these mutually.

The reflectance of the optical recording medium having the above structure at 750 nm incident on the substrate surface is 60 to 70%, and a semiconductor laser having a wavelength of 750 nm is used for the optical recording medium to obtain a linear velocity of 1.70. 2m / sec, recording laser power 8
An EFM modulated signal is recorded at mW, and the recorded signal is
When the data was reproduced with a 50 nm semiconductor laser of 0.5 mW, the reflectance in the recording portion was lowered in each case,
Although the modulation was taken, it seems that there is no practical problem compared with the result of 780 nm, but the result was inferior.

This means that even at a wavelength of 750 nm, ε ₁
<Because it is epsilon _2, conditions between these mutually be because not satisfied.

The reflectance of the optical recording medium having the above-described structure at a substrate surface incidence at 600 nm is 60 to 85%, and a semiconductor laser having a wavelength of 600 nm is used for this optical recording medium to produce a linear velocity of 1.2 m. / Sec, recording laser power 8mW
To record an EFM modulated signal, and the recorded signal is
When reproduction was performed with a semiconductor laser of 0.5 mW, the reflectance in the recording portion was lowered in all cases, the modulation was sufficiently large, the jitter was good, and almost no distortion was observed in the waveform of the recording / reproduction signal. Did not.

This is probably because the condition of ε ₁ and ε ₂ is satisfied at the wavelength of 600 nm.

The reflectance of the optical recording medium having the above-mentioned structure at a substrate surface incidence at 550 nm is 70 to 80%, and a semiconductor laser having a wavelength of 550 nm is used for this optical recording medium at a linear velocity of 1.2 m. / Sec, recording laser power 8mW
The EFM modulation signal is recorded at
When reproduction was performed with a semiconductor laser of 0.5 mW, the reflectance in the recording portion was lowered in all cases, the modulation was sufficiently large, the jitter was good, and almost no distortion was observed in the waveform of the recording / reproduction signal. Did not.

This is because even at a wavelength of 550 nm, ε ₁
And it is considered because it satisfies epsilon ₂ conditions.

(Comparative Example 1) In this comparative example, Embodiment 1
In the optical recording medium in which the film thickness of the intermediate layer is 100 and 120 nm, the recording light has wavelengths of 700, 650 and 635 n.
m semiconductor lasers were used.

The real and imaginary parts of the complex relative permittivity of this recording layer are ε ₁ = −0.68 and ε ₂ =
4.55, and ε ₁ = 0.2 at a wavelength of 650 nm.
2, ε ₂ = 3.04, and ε _{1 at} a wavelength of 635 nm
= 0.17 and ε ₂ = 1.78.

[0102] In the above structure, was confirmed by the recording light and reproducing light in the same wavelength, the reflectance is less than 60%, because there is no case that satisfies epsilon ₁ and epsilon ₂ conditions, be subjected to practical use No recording characteristics were obtained.

Further, using the optical recording medium of the first embodiment, a wavelength range of 770 to 830 nm and a wavelength range of 620 to 690 n
Investigating the same wavelength for recording light and reproduction light with m,
satisfies ε ₁ ≧ 4 and ε ₂ ≧ 5, or 2 ≧ ε ₁ ≧ 0 and ε ₂
When ≦ 1, the reflectance at the recording portion is low, the modulation is sufficiently large, the jitter is good, and the waveform of the recording / reproducing signal is similar to the result of recording / reproducing at the wavelength of 780 nm. Almost no distortion was observed.

In such a case, it has been found that ε ₁ ≧ ε ₂ is more preferable from the viewpoint of the magnitude of the reflectance, the degree of modulation and the like.

The wavelength range of 770 to 830 nm and 6
When the case where the reproducing light is shorter than the recording light at 20 to 690 nm is examined, when ε ₁ ≧ 4 and ε ₂ ≧ 5 are satisfied or 2 ≧ ε ₁ ≧ 0 and ε ₂ ≦ 2, In the recording portion, the reflectance was low, the modulation was sufficiently large, the jitter was good, and almost no distortion was observed in the waveform of the recording / reproducing signal.

In such a case, it was found that ε ₁ ≧ ε ₂ was more preferable from the viewpoint of the degree of modulation and the like.

In the above, the reproduction was repeated 1,000 times, but no change was observed in the reproduction characteristics.

(Embodiment 2) In this embodiment, a polysiloxane resin is formed to a thickness of 100, 120, 140, 160, 180 and 200 nm by spin coating as an intermediate layer. An optical recording medium was produced in the same manner as in Example 1.

In this embodiment, the optical constant of the intermediate layer is
For all wavelengths studied here, the refractive index n4 = 1.
40, the extinction coefficient k4 = 0.

In the optical recording medium having the above-described structure, 7
The reflectivity at 80 nm was all 60-70%.

The optical recording medium has a wavelength of 78 nm.
Using a semiconductor laser of 0 nm, a linear velocity of 1.2 m / sec
c) An EFM modulation signal was recorded at a recording laser power of 8 mW, and the recorded signal was reproduced by a 780 nm semiconductor laser of 0.5 mW.

As a result, in the recording portion, the reflectance was lowered, the modulation was sufficiently large, the jitter was good, and almost no distortion was observed in the waveform of the recording / reproducing signal.

The signal recorded in the same manner is transmitted at a wavelength of 635 n.
As a result of reproducing with an output of 0.5 mW of semiconductor laser of m
The reflectance was 40% or more, and the jitter was the same as that in the first embodiment.

The reflectance of the optical recording medium having the above structure at 550 nm upon incidence on the substrate surface was 70 to 80%.

The optical recording medium has a wavelength of 55 nm.
Using a semiconductor laser of 0 nm, a linear velocity of 1.2 m / sec
c) An EFM modulated signal was recorded at a recording laser power of 8 mW, and the recorded signal was reproduced with a 550 nm semiconductor laser of 0.5 mW.

As a result, in the recording portion, the reflectance was lowered, the modulation was sufficiently large, the jitter was good, and almost no distortion was observed in the waveform of the recording / reproducing signal.

(Comparative Example 2) In this comparative example, Embodiment 2
A semiconductor laser having a wavelength of 700 nm was used for both the recording light and the reproduction light for the optical recording medium in the above.

In each case, the reflectivity was less than 40%, and there was no case where the conditions of ε ₁ and ε ₂ were satisfied. Therefore, even practically usable recording characteristics could not be obtained. Further, using the optical recording medium of the second embodiment, the wavelength range of 770 to 83
When the recording light and the reproducing light were examined at the same wavelength at 0 nm and 620 to 690 nm, it was found that ε ₁ ≧ 4 and ε ₂ ≧ 5 were satisfied, or 2 ≧ ε ₁ ≧ 0 and ε ₂ ≦ 1 were satisfied. Is
As in the case of the above-described recording / reproducing with the wavelength of 780 nm, the reflectance in the recording portion is reduced, the degree of modulation is sufficiently large,
Furthermore, the jitter was good and almost no distortion was observed in the waveform of the recording / reproducing signal.

In such a case, it has been found that ε ₁ ≧ ε ₂ is more preferable from the viewpoint of the magnitude of the reflectance, the degree of modulation and the like.

The wavelength range of 770 to 830 nm and 6
When the case where the reproducing light is shorter than the recording light at 20 to 690 nm is examined, when ε ₁ ≧ 4 and ε ₂ ≧ 5 are satisfied or 2 ≧ ε ₁ ≧ 0 and ε ₂ ≦ 2, In the recording portion, the reflectance was low, the modulation was sufficiently large, the jitter was good, and almost no distortion was observed in the waveform of the recording / reproducing signal.

In such a case, it was found that ε ₁ ≧ ε ₂ is more preferable from the viewpoint of the degree of modulation and the like.

In the above, the reproduction was repeated 1,000 times, but no change was observed in the reproduction characteristics.

(Embodiment 3) In this embodiment, as an intermediate layer, ZrO ₂ is formed to a thickness of 100 by vacuum evaporation.
An optical recording medium was produced in the same manner as in Embodiment 1, except that the film was formed to have a thickness of 120 nm.

In the present embodiment, the optical constant of the intermediate layer is
The refractive index n4 = 2.
21, the extinction coefficient k4 = 0.

In the optical recording medium having the above-described structure, the 7
The reflectance at 80 nm was 60-70%.

The optical recording medium has a wavelength of 78 nm.
Using a semiconductor laser of 0 nm, a linear velocity of 1.2 m / sec
c) An EFM modulated signal was recorded at a recording laser power of 10 mW, and the recorded signal was reproduced by a 780 nm semiconductor laser of 0.5 mW.

As a result, in the recording portion, the reflectance was lowered, the modulation was sufficiently large, the jitter was good, and almost no distortion was observed in the waveform of the recording / reproducing signal.

The recorded signal is converted to a signal having a wavelength of 635.
As a result of reproducing with an output of a semiconductor laser having a wavelength of 0.5 mW, the reflectance was 40% or more, and the jitter was the same as in the first embodiment.

The reflectance of the optical recording medium having the above-mentioned structure at a wavelength of 600 nm upon incidence on the substrate surface was 70 to 80%.

Then, for all of these optical recording media, a semiconductor laser having a wavelength of 600 nm was used and a linear velocity of 1.2 m was used.
The EFM modulation signal was recorded at a recording laser power of 8 mW / sec, and the recorded signal was reproduced by a 600 nm semiconductor laser of 0.5 mW.

As a result, in the recording portion, the reflectance was lowered, the modulation was sufficiently large, the jitter was good, and almost no distortion was observed in the waveform of the recording / reproducing signal.

The reflectance of the optical recording medium having the above structure at 550 nm upon incidence on the substrate surface was 70-80%.

Then, a linear velocity of 1.2 m / sec was applied to the optical recording medium having the above-described structure by using a semiconductor laser having a wavelength of 550 nm.
The EFM modulation signal was recorded at a recording laser power of 8 mW for a second, and the recorded signal was reproduced by a 550 nm semiconductor laser of 0.5 mW.

As a result, in the recording portion, the reflectance was lowered, the modulation was sufficiently large, the jitter was good, and almost no distortion was observed in the waveform of the recording / reproducing signal.

Further, similarly to the first embodiment, when the recording light and the reproducing light have the same wavelength in the wavelength range of 770 to 830 nm and 620 to 690 nm,
When the case where the reproduction light was shorter than the recording light at 830 nm and 620 to 690 nm was examined, similar results were obtained.

(Comparative Example 3) In this comparative example, Embodiment 3
A semiconductor laser having a wavelength of 700 nm was used for both recording light and reproduction light for an optical recording medium having an intermediate layer having a thickness of 100 nm.

The reflectance was less than 40%, and there was no case where the conditions of ε ₁ and ε ₂ were satisfied. Therefore, even practical recording characteristics could not be obtained.

[0138]

As described above, according to the structure of the present invention,
By using an optical recording medium in which at least a recording layer containing a dye that absorbs recording light, an intermediate layer, and a reflective layer are sequentially formed on a transparent substrate, good recording and reproduction can be performed with respect to light having a predetermined wavelength. Possible optical recording media and optical recording / reproducing methods can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a write-once optical recording medium according to a first embodiment of the present invention.

FIG. 2 is a view showing the relationship between the thickness of an intermediate layer and the reflectance of the write-once type optical recording medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Recording layer 3 Intermediate layer 4 Reflective layer 5 Protective layer

Claims (15)

[Claims] 1. A transparent substrate, a recording layer provided on the substrate and containing a dye that absorbs recording light, an intermediate layer provided on the recording layer, and a reflection layer provided on the intermediate layer And the real part of the complex relative permittivity ε of the recording layer at the recording wavelength of the recording light and the reproduction wavelength of the reproduction light is ε ₁ ,
When the imaginary part is ε ₂ (ε = ε ₁ −iε ₂ ), ε ₁ and ε ₂ become
An optical recording medium satisfying ε ₁ ≧ 4 and ε ₂ ≧ 5. 2. A transparent substrate, a recording layer provided on the substrate and containing a dye that absorbs recording light, an intermediate layer provided on the recording layer, and a reflection layer provided on the intermediate layer. And the real part of the complex relative permittivity ε of the recording layer at the recording wavelength of the recording light and the reproduction wavelength of the reproduction light is ε ₁ ,
When the imaginary part is ε ₂ (ε = ε ₁ −iε ₂ ), ε ₁ and ε ₂ become
An optical recording medium satisfying 2 ≧ ε ₁ ≧ 0 and ε ₂ ≦ 1. 3. The optical recording medium according to claim ₁ , wherein ε ₂ ≦ ε ₁ is satisfied. 4. Furthermore, 'the real part epsilon' ₁ the complex relative permittivity of the recording layer epsilon in reproduction wavelength of the reproduction light is less than the recording wavelength of recording light, the imaginary part epsilon 'when the ₂ (epsilon' = Ε ' ₁ -i
satisfies ε ′ ₂ ), ε ′ ₁ ≧ 4 and ε ′ ₂ ≧ 5.
4. The optical recording medium according to any one of items 1 to 3. 5. Furthermore, 'the real part epsilon' ₁ the complex relative permittivity of the recording layer epsilon in reproduction wavelength of the reproduction light is less than the recording wavelength of recording light, the imaginary part epsilon 'when the ₂ (epsilon' = Ε ' ₁ -i
ε ′ ₂ ), ε ′ ₁ , ε ′ ₂ are 2 ≧ ε ′ ₁ ≧ 0 and ε ′ ₂ ≦
4. The optical recording medium according to claim 1, which satisfies condition 2. 6. A transparent substrate, a recording layer provided on the substrate and containing a dye that absorbs recording light, an intermediate layer provided on the recording layer, and a reflection layer provided on the intermediate layer. When the real part and the imaginary part of the complex relative permittivity ε ′ of the recording layer at the reproduction wavelength of the reproduction light shorter than the recording wavelength of the recording light are ε ′ ₁ and ε ′ ₂ (ε ′ = Ε ' ₁ -i
An optical recording medium satisfying ε ′ ₂ ), ε ′ ₁ ≧ 4 and ε ′ ₂ ≧ 5. 7. A transparent substrate, a recording layer provided on the substrate and containing a dye that absorbs recording light, an intermediate layer provided on the recording layer, and a reflection layer provided on the intermediate layer When the real part and the imaginary part of the complex relative permittivity ε ′ of the recording layer at the reproduction wavelength of the reproduction light shorter than the recording wavelength of the recording light are ε ′ ₁ and ε ′ ₂ (ε ′ = Ε ' ₁ -i
ε ′ ₂ ) An optical recording medium satisfying 2 ≧ ε ′ ₁ ≧ 0 and ε ′ ₂ ≦ 2. 8. The method according to claim 4, wherein ε ′ ₂ ≦ ε ′ ₁ is satisfied.
The optical recording medium according to any one of the above. 9. The method according to claim 1, wherein the reflection layer is a metal layer.
The optical recording medium according to any one of the above. 10. The optical recording medium according to claim 1, further comprising a protective layer outside the reflective layer. 11. An optical recording method for recording information by irradiating the optical recording medium according to claim 1 with a laser beam having a wavelength range of 770 to 830 nm. 12. An optical recording method for recording information by irradiating the optical recording medium according to claim 1 with laser light having a wavelength range of 620 to 690 nm. 13. An optical reproducing method for reproducing recorded information by irradiating the optical recording medium according to claim 1 with a laser beam having a wavelength range of 770 to 830 nm. 14. An optical reproducing method for reproducing recorded information by irradiating the optical recording medium according to claim 1 with laser light having a wavelength range of 620 to 690 nm. 15. Using the optical recording medium according to any one of claims 4 to 10, irradiating laser light having a wavelength range of 770 to 830 nm or 620 to 690 nm to record information, and recording the information in a wavelength range of 770 to 830 nm or 620-690
An optical recording / reproducing method for reproducing recorded information by irradiating a laser beam of nm with a wavelength shorter than the wavelength of the recording light.