JPH11154350A - Optical recording medium and optical recording/ reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium and an optical recording/ reproducing method performing recording/reproducing with high reflectivity and an excellent signal output characteristic for light of a prescribed wavelength and without read-out destruction. SOLUTION: These optical recording medium and optical recording/ reproducing method are the recording medium provided with the constitution successively formed with a recording layer 2 containing at least dyestuffs absorbing recording light and a reflection layer 3 on a transparent substrate 1, and satisfied with T<=0.2 or 0.8<=T when the transmissivity of the single film of the recording layer in the recording wavelength of the recording light and a reproducing wavelength of reproducing light is defined T, and the optical recording medium satisfying with T'<=0.4 or 0.6<=T' when the transmissivity of the single film of the recording layer in the reproducing wavelength of the reproducing light of the recording wavelength or below of the recording light in such a constitution is defined T', and the optical recording/reproducing method using it.

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 a method using an optical recording medium having no intermediate layer.

[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 and a reflective layer are sequentially formed, good recording / reproduction for light of a predetermined wavelength, that is, high reflectivity and excellent signal output characteristics. It is an object of the present invention to provide an optical recording medium and an optical recording / reproducing method capable of performing recording / reproduction without reading / destroying by repeated reproduction.

[0025]

Means for Solving the Problems In order to solve the above problems,
The present invention has a configuration in which at least a recording layer containing a dye that absorbs recording light and a reflective layer are sequentially formed on a transparent substrate, and the recording layer at the recording wavelength of the recording light and the reproducing wavelength of the reproducing light. When the transmittance of a single film is T, T ≦ 0.2
Alternatively, T ′ ≦ 0.4 or 0, where T ′ is the recording medium satisfying 0.8 ≦ T, and T ′ is the transmittance of the single layer of the recording layer at the reproduction wavelength of the reproduction light shorter than the recording wavelength of the recording light. An optical recording medium that satisfies 0.6 ≦ T ′ and an optical recording / reproducing method using the same.

Here, the reflectance, the transmittance, and the
The absorptance is determined by calculation from the refractive index and the extinction coefficient determined from the film thickness dependence of the reflectance and transmittance for 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,
Provided are an optical recording medium and an optical recording / reproducing method capable of performing good recording / reproducing with respect to light of a predetermined wavelength by using an optical recording medium on which a reflective layer is sequentially formed.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1, wherein a transparent substrate, a recording layer provided on the substrate and containing a dye that absorbs recording light, and a reflective layer provided on the recording layer And T is the transmittance of the single film of the recording layer at the recording wavelength of the recording light and the reproducing wavelength of the reproducing light,
The optical recording medium satisfies ≦ 0.2 or 0.8 ≦ T.

With such a configuration, the effects of the recording layer and the reflective layer can be maximized, and good recording and reproduction can be performed. If these conditions are not satisfied, the reflectance may decrease,
Phenomena such as a disturbance of the reproduction signal waveform occur.

Here, when the reflectance of the single layer of the recording layer at the recording wavelength of the recording light and the reproducing wavelength of the reproducing light is R, the transmissivity is T, and the absorptance is A (claim 2). R
+ T + A = 1), α = α given by A / (A + R)
Is 0.2 ≦ α ≦ 0.6 and 0.8 ≦ when T ≦ 0.2
When T, it is preferable to satisfy 0.9 ≦ α.

With such a configuration, the balance between the absorption and the reflection can be achieved, and more favorable recording and reproduction can be performed.

And, as described in claim 3, further,
Assuming that the transmittance of the single layer of the recording layer at the reproducing wavelength of the reproducing light less than the recording wavelength of the recording light is T ', T' ≦ 0.4 or 0.6 ≦ T ′ may be satisfied.

Even with such a configuration, when the reproducing light having a wavelength shorter than the recording wavelength of the recording light is used, the effect of the recording layer and the reflective layer can be maximized, good recording and reproducing can be performed, and the T 'can be improved. Conditions are relaxed.

According to a fourth aspect of the present invention, there is provided a transparent substrate, a recording layer provided on the substrate and containing a dye that absorbs recording light, and a reflective layer provided on the recording layer. When the transmittance of the single layer of the recording layer at the reproduction wavelength of the reproduction light shorter than the recording wavelength of the recording light is T ′, T ′ ≦
The optical recording medium may satisfy 0.4 or 0.6 ≦ T ′.

According to such a configuration, when the reproducing light having a wavelength shorter than the recording wavelength of the recording light is used, the effect of the recording layer and the reflective layer can be maximized, and good recording and reproducing can be performed. Conditions are relaxed.

In the case where the reproducing light having a wavelength shorter than the recording wavelength of the recording light is used, the reflectivity of the single film of the recording layer at the reproducing wavelength of the reproducing light having a wavelength shorter than the recording wavelength of the recording light is set forth. Is R ′, transmittance is T ′, and absorptance is A ′ (R ′ + T ′ + A ′ = 1), α ′ = A ′ / (A ′ +
R ′) is 0.2 when T ′ ≦ 0.4.
When ≦ α ′ ≦ 0.8 and 0.6 ≦ T ′, it is preferable to satisfy 0.8 ≦ α ′.

With such a configuration, the balance between the absorption and the reflection is achieved, and better recording / reproducing becomes possible.

In the above, as described in claim 6, it is preferable that the reflective layer is a metal layer having that function because of its good reflective function.

Further, as described in claim 7, a protective layer may be provided outside the reflective layer.

On the other hand, the present invention according to the method, as described in claim 8, uses the optical recording medium according to any one of claims 1 to 7 to irradiate a laser beam having a wavelength range of 730 to 830 nm. This is an optical recording method for recording information, and recording is reliably performed using a laser beam within such a wavelength range. You.

Alternatively, as described in claim 9, claim 1
7. An optical recording method for recording information by irradiating a laser beam having a wavelength range of 530 to 690 nm using the optical recording medium according to any one of items 1 to 7, wherein recording is performed reliably by using a laser beam within the wavelength range. .

Alternatively, the recorded information is reproduced by irradiating the optical recording medium according to any one of claims 1 to 7 with a laser beam having a wavelength range of 730 to 830 nm. This is a method of reproducing light, and the reproduction is surely performed by 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 7 with a laser beam having a wavelength range of 530 to 690 nm. This is a method of reproducing light, and the reproduction is surely performed by the laser light within the wavelength range.

According to a twelfth aspect, information is recorded by irradiating a laser beam having a wavelength range of 730 to 830 nm or 530 to 690 nm using the optical recording medium according to any one of the third to seventh aspects. And a wavelength range of 730 to 83
0 nm or 530-690 nm laser light,
This is an optical recording / reproducing method for reproducing recorded information by irradiating a wavelength shorter than the wavelength of the recording light, and recording / reproducing is surely performed by a laser beam within the wavelength range.

That is, the present inventor has proposed that an optical recording medium in which at least a recording layer containing a dye for absorbing recording light and a reflective layer are sequentially formed on a transparent substrate, light of a specific range of wavelengths can be obtained. As a result of diligent studies to achieve good recording and reproduction, it is very important to control the reflectance between the substrate and the recording layer, and between the recording layer and the reflective layer. As a guideline, (1) effectively utilize the reflectance of the recording layer by suppressing the transmittance of the recording layer alone film;
(2) It has been found that it is an important point to select either one of increasing the transmittance of the recording layer alone film and effectively utilizing the reflectance other than the recording layer.

Specifically, assuming that the transmittance of a single film of the recording layer at the recording wavelength of the recording light and the reproducing wavelength of the reproducing light is T, the light is controlled so as to satisfy T ≦ 0.2 or 0.8 ≦ T. It has been found that designing a recording medium is very important. When the reflectance of the recording layer alone film is R and the absorptance is A, R + T + A = 1.

That is, by setting this T in a specific range for a recording light of a specific wavelength and a reproducing light equivalent thereto, an optical recording medium capable of excellent recording and reproduction can be obtained. By setting this T to a specific range for a recording light of a specific wavelength and a reproducing light of a shorter wavelength, respectively, an optical recording medium capable of good recording and reproduction was found, and the present invention was reached. Things.

In the above description, 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 small 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 on the transparent substrate directly or via another layer, and has an appropriate absorption and heat conversion efficiency for 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, dyes are preferred, but phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, detraazaporphyrin dyes, cyanine dyes, azo dyes and the like can be mentioned. 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.

Further, resins may be added to the dye solution as a binder, and 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, a desired film thickness is adjusted by 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 deposited at a degree of vacuum of 10 ⁻² Pa or less.

A recording layer can also be formed by simultaneously vapor-depositing a vaporizable light stabilizer, an antioxidant and the like. 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 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, the optical recording medium of the present invention and an optical recording / reproducing method using the same will be described in detail.

(Embodiment 1) FIG. 1 is an enlarged view of a cross section of an optical recording medium of the present embodiment.

In FIG. 1, 1 is a transparent substrate, 2 is a recording layer formed on the transparent substrate 1, 3 is a reflective layer formed on the recording layer 2, and 4 is a protective layer formed on the reflective layer 3. Layer.

The substrate 1 is a disc-shaped transparent 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,
A tin chloride phthalocyanine represented by the following chemical formula (Formula 1) is typically used, and the average film thickness is 50, 10
The film was formed to have a thickness of 0 and 150 nm.

[0068]

Embedded image

Next, a gold thin film having a thickness of 100 nm was formed as a reflective layer 3 on the recording layer 2 by sputtering.

Further, an ultraviolet curable resin was applied on the reflective layer 3 by a spin coating method, and was cured by irradiating ultraviolet rays, and this was used as a protective layer 4 to prepare 10 optical recording media.
In addition, the following measured value was made into the average value of ten each.

Here, the reflectance R, transmittance T, absorptance A and α of the recording layer single film having a film thickness of 50 nm are 760 nm wavelength.
R = 0.56, T = 0.04, A = 0.40
Where α = 0.41 and at a wavelength of 750 nm, R =
0.58, T = 0.02, A = 0.40, α = 0.4
1, R = 0.57 and T =
0.03, A = 0.40, α = 0.42, and at a wavelength of 700 nm, R = 0.26, T = 0.21, A =
0.53, α = 0.66, and at a wavelength of 650 nm, R = 0.18, T = 0.31, A = 0.51, α
= 0.75, R = 0.03 at 600 nm wavelength, T
= 0.67, A = 0.30, α = 0.91, R = 0.01, T = 0.81, A at wavelength 575 nm
= 0.18, α = 0.93, R = 0.00, T = 0.93, A = 0.07 at a wavelength of 550 nm,
α = 0.98.

The reflectance R, transmittance T, absorptance A, and α of a single layer of a recording layer having a thickness of 100 nm have a wavelength of 760 nm.
R = 0.48, T = 0.01, A = 0.51 at m
And α = 0.51, and at a wavelength of 750 nm, R =
0.53, T = 0.00, A = 0.47, α = 0.4
7, R = 0.55, T =
0.00, A = 0.45, α = 0.45, and at a wavelength of 700 nm, R = 0.35, T = 0.26, A =
At 0.59, α = 0.62, and at a wavelength of 650 nm, R = 0.26, T = 0.11, A = 0.63, α
= 0.71 and R = 0.0 at a wavelength of 600 nm.
6, T = 0.47, A = 0.47, α = 0.62, and R = 0.03 and T = 0.6 at a wavelength of 575 nm.
8, A = 0.29, α = 0.91, wavelength 550
R = 0.00, T = 0.86, A = 0.1 in nm
At 4, α = 0.97.

The reflectance R, transmittance T, absorptivity A, and α of the recording layer single film having a thickness of 150 nm are 760 nm wavelength.
m = 0, R = 0.50, T = 0.00, A = 0.50
And α = 0.50, and at a wavelength of 750 nm, R =
0.53, T = 0.00, A = 0.47, α = 0.4
7, R = 0.55, T =
0.00, A = 0.45, α = 0.45, and at a wavelength of 700 nm, R = 0.34, T = 0.21, A =
0.65, α = 0.65, and at a wavelength of 650 nm, R = 0.24, T = 0.04, A = 0.72, α
= 0.75, and R = 0.0 at a wavelength of 600 nm.
6, T = 0.31, A = 0.63, α = 0.91, and at a wavelength of 575 nm, R = 0.02 and T = 0.5.
7, A = 0.41, α = 0.94, wavelength 550
R = 0.00, T = 0.80, A = 0.2 in nm
At 0, α = 0.98.

In the optical recording medium having the above-described structure, the light incident on the substrate surface 7
The reflectance at 60 nm was 60-70%.

The optical recording medium has a wavelength of 76.
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 converted to a 760 nm semiconductor laser 0.5
Played back at 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 presumably because the conditions of T and α are satisfied at the wavelength of 760 nm.

Further, a signal recorded in the same manner is transmitted at a wavelength of 650 nm.
As a result of reproducing with an output of 0.5 mW of semiconductor laser of m
The reflectance was 40% or more, the degree of modulation was sufficiently large, the jitter was good, and almost no distortion was observed in the recording / reproducing signal waveform.

This is considered to be because the reproduction at the wavelength of 650 nm satisfies the conditions of T and α when the reproduction light has a shorter wavelength than the recording light.

The reflectance of the optical recording medium having the above structure at 750 nm incident on the substrate surface was 60 to 70%.

An EFM modulated signal was recorded on these optical recording media using a semiconductor laser having a wavelength of 750 nm at a linear velocity of 1.2 m / sec and a recording laser power of 8 mW, and the recorded signal was converted to a semiconductor laser having a wavelength of 750 nm of 0.5 mW. Played with.

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.

It is considered that this is because the conditions of T and α are satisfied at the wavelength of 750 nm.

The reflectance of the optical recording medium having the above structure at 740 nm incident on the substrate surface was 60 to 70%.

An EFM modulated signal was recorded on these optical recording media at a linear velocity of 1.2 m / sec and a recording laser power of 8 mW using a semiconductor laser having a wavelength of 740 nm, and the recorded signal was converted to a semiconductor laser having a wavelength of 740 nm of 0.5 mW. Played with.

In each case, the reflectance at the recording portion 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.

This is probably because the condition of T and α is satisfied at the wavelength of 740 nm.

The reflectance of the optical recording medium having the above-mentioned structure at a wavelength of 700 nm incident on the substrate surface was 60 or less.

An EFM modulated signal was recorded on these optical recording media using a semiconductor laser having a wavelength of 700 nm at a linear velocity of 1.2 m / sec and a recording laser power of 8 mW. Played with.

In each case, practically sufficient recording / reproducing characteristics were not obtained. This is probably because the condition of T and α is not satisfied at the wavelength of 700 nm.

The reflectance of the optical recording medium having the above-mentioned structure at 600 nm incident on the substrate surface was 60 or less.

An EFM modulated signal was recorded on these optical recording media using a semiconductor laser having a wavelength of 600 nm at a linear velocity of 1.2 m / sec and a recording laser power of 8 mW. Played with.

In each case, practically sufficient recording / reproducing characteristics were not obtained. This is considered to be because the condition of T and α is not satisfied at the wavelength of 600 nm.

The reflectivity of the optical recording medium having the above-mentioned structure at 575 nm incident on the substrate surface is such that the thickness of the recording layer is 50 nm.
77%, and 5% when the thickness of the recording layer is 100 nm.
9%, and 32% when the thickness of the recording layer was 150 nm.

On these optical recording media, an EFM modulation signal was recorded at a linear velocity of 1.2 m / sec and a recording laser power of 8 mW using a semiconductor laser having a wavelength of 575 nm, and the recorded signal was converted to a 575 nm semiconductor laser of 0.5 mW. Played with.

When the thickness of the recording layer was 50 nm, the reflectance was lowered in the recording portion, 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 considered to be because in such a case, the conditions of T and α are satisfied. On the other hand, when the thickness of the recording layer was 100 nm or 150 nm, practically sufficient recording / reproducing characteristics were not obtained in any case.

This is probably because the condition of T was not satisfied. In addition, the reflectance of the optical recording medium having the above configuration at 550 nm when the light was incident on the substrate surface was 70 to 80%.

An EFM modulated signal was recorded on these optical recording media at a linear velocity of 1.2 m / sec and a recording laser power of 8 mW using a semiconductor laser having a wavelength of 550 nm, and the recorded signal was converted to a 0.5 mW semiconductor laser having a wavelength of 550 nm. Played with.

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.

It is considered that this is because the condition of T and α is satisfied at the wavelength of 550 nm.

Further, when the recording light and the reproduction light were examined at the same wavelength in the wavelength ranges of 730 to 830 nm and 530 to 690 nm, the above wavelength was determined when T ≦ 0.2 or 0.8 ≦ T was satisfied. Similar to the result of recording / reproducing at 760 nm, the reflectance in the recording portion 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.

In such a case, from the viewpoint of the degree of modulation, when α is T ≦ 0.2, 0.2 ≦ α ≦
It has been found that satisfying 0.9 ≦ α when 0.6 and 0.8 ≦ T is preferable from the viewpoint of the reflectance and the degree of modulation.

The wavelength range of 730 to 830 nm and 5
The case where the reproducing light is shorter than the recording light at 30 to 690 nm is examined. When T ≦ 0.4 or 0.6 ≦ T is satisfied, the reflectance decreases in the recording portion and the modulation degree is sufficiently large. Also, the jitter was good, and almost no distortion was observed in the waveform of the recording / reproducing signal.

In such a case, from the viewpoint of the degree of modulation, when α is T ≦ 0.4, 0.2 ≦ α ≦ 0.
It has been found that it is more preferable to satisfy 0.8 ≦ α when 8 and 0.6 ≦ T.

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

[0107]

As described above, according to the structure of the present invention,
Using an optical recording medium in which at least a recording layer containing a dye that absorbs recording light and a reflective layer are sequentially formed on a transparent substrate, light capable of performing good recording and reproduction with respect to light of a predetermined wavelength. A recording medium and an optical recording / reproducing method 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.

[Explanation of symbols]

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

Claims (12)

[Claims] 1. A recording substrate comprising: a transparent substrate; a recording layer provided on the substrate and containing a dye that absorbs recording light; and a reflective layer provided on the recording layer. And an optical recording medium satisfying T ≦ 0.2 or 0.8 ≦ T, where T is the transmittance of the single layer of the recording layer at the reproduction wavelength of the reproduction light. 2. When the reflectance of a single film of the recording layer at the recording wavelength of the recording light and the reproducing wavelength of the reproducing light is R, T is the transmittance, and A is the absorptance (R + T + A = 1), α = A / (A
+ R) is 0.2 ≦ α when T ≦ 0.2
2. The optical recording medium according to claim 1, wherein 0.9 ≦ α is satisfied when ≦ 0.6 and 0.8 ≦ T. 3. When the transmittance of a single layer of the recording layer at the reproduction wavelength of the reproduction light shorter than the recording wavelength of the recording light is T ′, T ′ ≦ 0.4 or 0.6 ≦ T ′ is satisfied. The optical recording medium according to claim 1. 4. A recording layer comprising a transparent substrate, a recording layer provided on the substrate and containing a dye that absorbs recording light, and a reflective layer provided on the recording layer, wherein the recording layer has a wavelength less than the recording wavelength of the recording light. An optical recording medium which satisfies T ′ ≦ 0.4 or 0.6 ≦ T ′ when the transmittance of the single layer of the recording layer at the reproduction wavelength of the reproduction light is T ′. 5. When the reflectance of a single layer of the recording layer at the reproducing wavelength of the reproducing light shorter than the recording wavelength of the recording light is R ′, the transmissivity is T ′, and the absorptance is A ′ (R ′ + T ′ + A). '=
1), α ′ given by α ′ = A ′ / (A ′ + R ′)
Is 0.2 ≦ α ′ ≦ 0.8 and 0.
5. The optical recording medium according to claim 3, wherein 0.8 ≦ α ′ is satisfied when 6 ≦ T ′. 6. The reflection layer is a metal layer.
The optical recording medium according to any one of the above. 7. The method according to claim 1, wherein a protective layer is provided outside the reflective layer.
7. The optical recording medium according to any one of items 1 to 6. 8. 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 730 to 830 nm. 9. 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 530 to 690 nm. 10. An optical reproduction method for reproducing recorded information by irradiating the optical recording medium according to claim 1 with laser light having a wavelength range of 730 to 830 nm. 11. 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 530 to 690 nm. 12. An optical recording medium according to claim 3, wherein information is recorded by irradiating a laser beam having a wavelength range of 730 to 830 nm or 530 to 690 nm, and a wavelength range of 730 to 830 nm or 530-690
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.