JPH0412885A - Optical recording medium - Google Patents

Abstract

PURPOSE:To perform a ternary recording with a higher reliability by a method wherein a recording layer consists of an organic compound and an inorganic compound, a first recording state is formed by changing the inorganic compound in phase, and a second recording state is formed by deforming the recording layer into projected or recessed form. CONSTITUTION:By irradiating a recording layer 22 provided on a substrate 11 with a light, a first recording state of a recording film with a change in reflectance without a change in shape and a second recording state of a recording film with a change in reflectance subsequent to a change in shape are formed. In an optical recording medium on which information signals are recorded using a difference in reflectance among the first and second recording states and an unrecorded state, the first recording state is formed by changing the inorganic compound in phase, and the second recording state is formed by deforming the recording layer into projected or recessed form. The organic compound contains a cyanine dye shown by a formula I. The inorganic compound contains 50atm% or more Sb and a sulfur as the other component element. R1, R2 and R3 represent 1-6C alkyl; X is halogen or the like; and A represents a benzene ring or a naphthyl ring.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to optical recording media.

[Prior Art] Conventional optical recording media record information using binary signals corresponding to two states of a recording film: a recorded state and an unrecorded state.

As one method to improve recording density, it has been proposed to perform ternary signal recording by forming two types of recording states with different reflectances on the recording film (Japanese Patent Laid-Open No. 1-24
3237, JP-A-1-173432).

The proposed optical recording medium and optical recording method layer two types of recording layers on a substrate and adjust the amount of light absorption of each recording layer to create a recording state in which pits are formed only in the recording layer on the light irradiation side. Two types of recording states are formed: and a recording state in which pits are formed in both recording layers.

1.2 of the prior art shown in Japanese Patent Application Laid-open No. 1-243237.
As shown in the figure. In the figure, 1 represents a substrate, 2 represents a first recording layer, and 3 represents a second recording layer. In this method, the first
A first recording state in which only the recording layer 2 of the recording layer 2 is removed and pits are formed, and a second recording state in which pits are formed by removing both the first and second recording layers 2 and 3 are recorded in the recording layer 2. .3 is selectively formed by adjusting the amount of light absorption.

However, when only the first recording layer 2 is removed and pits are formed, the characteristics (reflectance, flatness) of the second recording layer 3 tend to change, and the characteristics of the second recording layer 3 tend to change between the first recording state and the second recording state. It had the disadvantage that a stable reflectance difference could not be obtained.

Also, regarding recording sensitivity, when a recording layer is removed and two types of recording layers that form pits are stacked, the recording layer sandwiched between the upper and lower layers (or substrate) is deformed and removed.
However, it had the disadvantage that recording sensitivity decreased.

[Problems to be Solved by the Invention] An object of the present invention is to provide an optical recording medium and an optical recording method that enable more reliable ternary recording under these circumstances.

[Means for Solving the Problems] That is, the present invention provides: (1) By irradiating a recording layer provided on a substrate with light,
forming a first recording state in which the reflectance is changed without changing the shape of the recording film and a second recording state in which the reflectance is changed due to a change in the shape of the recording film; In an optical recording medium that records information signals by using a difference in reflectance between a state and an unrecorded state, the recording layer is composed of an organic compound and an inorganic compound, and the first recording state is such that the inorganic compound undergoes a phase change. (2) An optical recording medium characterized in that the second recording state is formed by deforming the recording layer into a convex or concave shape, (2) the recording state according to claim (1) is formed by recording light (3) An optical recording method characterized in that formation is selectively performed by changing irradiation time or recording light intensity; (3) Claim (1) characterized in that the organic compound contains a cyanine dye represented by the following general formula. ), RI R2 RI R2 (wherein RI, R2 and R3 may be the same or different and each represents 01-C6 alkyl,
represents halogen, perhalogen acid, boron tetrafluoride, toluenesulfonic acid, or alkyl sulfuric acid, A represents a benzene ring or naphthyl ring, and on each ring, as a substituent, alkyl, alkoxy, hydroxy, carboxyl, halogen, Allyl or alkyl carboxyl may or may not be present and n is 0 or 1-3
(4) contains an inorganic compound or Sb of 50 atm% or more,
The optical recording medium according to claim 1, further comprising sulfur as another component element.

A typical structure of the optical recording medium of the present invention is shown in FIGS. 3 and 4.

In the simplest configuration of the optical recording medium of the present invention, the third
As shown in the figure, it is sufficient if the recording layer 22 is formed on the substrate 11, but as shown in FIG.
An overcoat layer 44 may be formed between the recording layer 1 and the recording layer 22, and the protective layer 33 may be formed on the recording layer 22.

Further, the direction of incidence of the recording light may be from the substrate side or from the recording layer side.

As the material of the substrate 11, a transparent plastic substrate, a glass substrate, etc. can be used, and specific examples thereof include polycarbonate resin, polyolefin resin, acrylic resin, epoxy resin, quartz glass, and reinforced glass.

Note that a tracking guide hole, a guide pit, and a preformat such as an address signal may be formed on the surface of the substrate.

The recording layer 22 is composed of an inorganic compound and an organic compound, and a first recording state is formed when the inorganic compound undergoes a phase change, and a second recording state is formed when both the inorganic compound and the organic compound deform into a convex or concave shape. A recording state is formed. The inorganic compound and the organic compound need only be held in contact with each other in the recording layer 22, and may be a laminated layer of an inorganic compound layer and an organic compound or a mixed layer of an inorganic compound and an organic compound. In the case of lamination, the number of repetitions of lamination and the order of lamination may be arbitrarily set as long as the characteristics of the recording layer are not deteriorated.

The inorganic compound material used in the present invention is capable of undergoing a phase change upon irradiation with a first amount of recording light (recording light that forms a first recorded state), and which has a first amount of light irradiation. It is possible to use a material that can be deformed into a convex or concave shape together with an organic compound by irradiation with a second light irradiation amount of recording light (recording light that forms a second recording state) that is higher in light irradiation amount than that of the recording light. Ru. A specific material is 5bTe.

5bTeGe, 5bSnS, SbInS.

Examples include GeTe, InSb, etc., and preferably Sb containing 50 atm% or more of Sb, which is easily transformed into an organic compound by irradiation of the recording destination with the second light irradiation amount, and containing sulfur as another component element. b 70S n +sS
+s, S b 701 n +sS +s, etc. are preferable.

As the organic compound material used in the present invention, a material that can be deformed into a convex or concave shape together with an inorganic compound by irradiation with the recording light of the second light irradiation amount can be used. Specific materials include thermoplastic resins such as aliphatic hydrocarbon resins, polyethylene resins, polystyrene resins, polyvinyl chloride resins, acrylic resins, polycarbonate resins, and polyamide resins, cyanine dyes, phthalocyanine dyes, naphthalocyanine dyes, and squarylium. Examples include light-absorbing dyes such as dyes, naphthoquinone dyes, metal indoaniline dyes, and azulenium dyes, and mixtures of these materials.

A particularly preferred material is a material containing a cyanine dye of the following general formula, which can be easily formed into a film by coating, has high sensitivity, and can be decomposed and deformed by light absorption.

RI R2 RI R2 (wherein R1, R2 and R3 may be the same or different and each represents 01-C5 alkyl, X is halogen, perhalokenic acid, boron tetrafluoride, toluenesulfonic acid or alkyl sulfate) , A represents a benzene ring or a naphthyl ring, and each ring may or may not have an alkyl, alkoxy, hydroxy, carboxyl, halogen, allyl or alkyl carboxyl as a substituent, and n is O or an integer from 1 to 3) The thickness of the recording layer 22 varies depending on the material, but is 100 to 3000.
People are preferred.

To form the recording layer 22 on the substrate 11 or the undercoat layer 44, when the recording layer is composed of a laminated layer of an inorganic compound layer and an organic compound layer, the inorganic compound is formed by a vacuum film forming method (evaporation method, sputtering method). etc.), and for the organic compound, conventionally known methods such as liquid coating methods (spinner coating, spray coating, dip coating, etc.) can be adopted.

When the recording layer is composed of a mixed layer of an inorganic compound and an organic compound, it can be formed by reactive sputtering of the inorganic compound using an organic compound gas.

The undercoat layer 44 includes (1) a barrier layer such as water or gas;
It is provided to provide the optical recording medium with functions such as (2) ensuring storage stability of the recording layer, (3) improving reflectance, and (4) forming a pregroove.

The materials for the undercoat layer 44 include the above (1),
If (2) is emphasized, polymer materials (acrylic resin, epoxy resin, etc.), inorganic compounds (Si02.ZnS, TiN
, SiN, AN 203, etc.) and metals and semimetals (Au
, Ni, Cr, Se, etc.), and if (3) is emphasized, inorganic compounds (ZnS, Sb2S3.SnS, I
nS, etc.) and metals (AR, Ag, Au, etc.) can be used, and if (4) is emphasized, various ultraviolet curable resins, thermosetting resins, and thermoplastic resins can be used.

The thickness of the undercoat layer 44 varies depending on the type of material, but is 0.
．． Approximately 1 to 30μ mark is appropriate.

The protective layer 33 (1) protects the recording layer 2 from scratches, dust, dirt, etc., (2) improves the storage stability of the recording layer 2,
(3) It is formed for purposes such as improving reflectance. As the material for forming the protective layer 33, the materials listed for the undercoat layer 44 can be used as they are. The thickness of the protective layer 33 varies depending on the type of material, as in the case of the undercoat layer 44, but is suitably about 0.1 to 100 μm. In addition, as a means for forming the protective layer 33 and the undercoat layer 44, when forming an inorganic material, a vacuum film forming method (
Conventionally known methods such as a solution coating method (spinner coating, spray coating, dip coating, etc.) can be employed when forming an organic material.

Next, an optical recording method for recording on an optical recording medium according to the present invention will be explained. FIGS. 5A and 5S show examples of the recording light pattern irradiated onto the optical recording medium according to the present invention and the recorded state formed.

FIG. 5a is a diagram schematically explaining an example in which the amount of light irradiation is changed depending on the intensity of light irradiation, where C1 is the recording light of the first amount of light irradiation, C2 is the recording light of the second amount of light irradiation, a represents the first recording state, and b represents the second recording state. FIG. 5 is a diagram schematically explaining an example in which the amount of light irradiation is changed depending on the time of light irradiation.

In the optical information recording method of the present invention, in the case of the method shown in FIG. , the first recording light intensity is P I , the second
When the recording light intensity of is P2, there is a relationship of Po<PI<P2.

In this way, in order to perform recording on the optical recording medium according to the present invention, two types of recording light with different light irradiation amounts (recording light with a first and second light irradiation amount) are irradiated onto the recording layer, and the first Selectively form a first recording state (a) by irradiating recording light (C+) with an amount of light irradiation, and selectively form a second recording state (b) by irradiating recording light (C2) with a second amount of light irradiation. do it.

The amount of light irradiation can be controlled to an appropriate amount by changing the irradiation time of the recording light or the irradiation intensity of the recording light.

The optical recording medium and optical recording method of the present invention have two different reflectances.
Since different recording states are formed by different recording mechanisms (phase change and deformation), and the first recording state is a phase change recording state, the recording layer is deformed or removed when forming the first recording state. Since the first recorded state and the second recorded state can be reliably formed without any problems, the reflectance difference between the first recorded state and the second recorded state can be stably obtained.

In addition, since the first recording state by phase change recording can be a recording state with a high reflectance, and the second recording state by deformation recording can be a recording state with a low reflectance, it is possible to make a large difference between the two recording states. It is possible to obtain the reflectance difference.

Furthermore, in the case of a structure in which two types of recording layers are laminated to form a bit by removing the recording layer as in the conventional technology, the recording layer sandwiched between the upper and lower layers (or substrate) is deformed and removed.
However, the optical recording medium of the present invention does not have a structure like that of the prior art, so there is no large decrease in recording sensitivity.

[Example] The present invention will be explained in more detail with reference to Examples below.

Examples 1 to 3 A cyanine dye represented by the following general formula was mixed with methanol and 1,2-dichloroethane onto a polycarbonate resin substrate having a thickness of 1.2II1m and a diameter of 130φmm, on which a spiral guide groove for tracking was molded during injection molding. By dissolving in a mixed solvent and spin-coding, the thickness of approximately 3
00 cyanine dye films were formed.

Next, using a resistance heating type vacuum evaporation device on this dye film, I naoS b6oSS b7o1 n +58
15, Sb and In, Sb and InS, and Sb and S
Formed with a thickness of about 700 nm by dual source co-evaporation of nS,
Optical recording media according to the present invention of No. 1 to No. 3 were created.

Examples 4 to 6 In Examples 1 to 3, thermoplastic aliphatic hydrocarbon resin (trade name Hiretz C-110X) was used instead of the cyanine dye film.
Mitsui Petrochemical Industries) films were spin-coded using cyclohexane as a solvent to a film thickness of approximately 1000 mm, and Nos. 4 to 6 were formed.
An optical recording medium according to the present invention was prepared.

These optical recording media according to the present invention of Nos. 1 to 6 have a laser beam wavelength of 780 nm, N, A, (numerical aperture of the lens) 0.5, and a linear velocity of 5. [im/S% Recording Signal Recording Signal Frequency 2 Re Hz Intensity P. Under the condition of -0.5 mW, the recording light irradiation intensity in FIG. 5(a) was set to PI-2 mW.

With Pz=7 mW, recording was performed from the substrate side while changing the amount of light irradiation depending on the light irradiation intensity, and the reflectance of each recording state was determined from the reproduced signal intensity.

The results are shown in Table 1, and the optical recording medium of the present invention has a stable large reflectance difference of 10% or more between the first and second recorded states and the unrecorded state at all of the many measurement points. I was able to get it.

Table 1 In addition, when recording was performed on the optical recording medium No. 2 by setting the irradiation time C1 to 1/4 of C2 in FIG. 5(b) and changing the light irradiation amount depending on the light irradiation time, Table The same results as in Example 1 were obtained.

Furthermore, when the respective recording states of the optical recording medium of the present invention were observed by SEM, the first recording state (a) was a recording state due to phase change without deformation, and the second recording state (a) was a recording state due to phase change.
In b), deformation of the recording layer was observed, and it was confirmed that the recording state was caused by deformation.

[Effects of the Invention] As explained above, by using the optical recording medium and optical recording method of the present invention, each recording state can be reliably recorded compared to conventionally proposed ternary recording optical recording media and optical recording methods. Can be formed. Furthermore, the configuration is advantageous compared to conventional methods in terms of recording sensitivity. From the above results, it becomes possible to increase the density by more reliable three-level recording.

[Brief explanation of drawings]

Figure 1.2 is an explanatory diagram of a conventional optical recording medium, Figure 3.4 is an explanatory diagram of an optical recording medium of the present invention, and Figures 5 (a) and (b).
FIG. 5(a) is a diagram schematically explaining an example of the recording light pattern irradiated onto the optical recording medium of the present invention and the recording state formed, and FIG. FIG. 5(b) shows an example in which the amount of light irradiation is changed depending on the time of light irradiation.

Claims (4)

[Claims] (1) By irradiating the recording layer provided on the substrate with light,
forming a first recording state in which the reflectance is changed without changing the shape of the recording film and a second recording state in which the reflectance is changed due to a change in the shape of the recording film; In an optical recording medium that records information signals by using a difference in reflectance between a state and an unrecorded state, the recording layer is composed of an organic compound and an inorganic compound, and the first recording state is such that the inorganic compound undergoes a phase change. An optical recording medium, characterized in that the second recording state is formed by deforming the recording layer into a convex or concave shape. (2) An optical recording method characterized in that the recording state according to claim (1) is selectively formed by changing the recording light irradiation time or the recording light intensity. (3) The optical recording medium according to claim (1), wherein the organic compound contains a cyanine dye represented by the following general formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1, R_2 and R_3 may be the same or different and each represents C_1 to C_6 alkyl, and X is halogen, perhalogen acid, boron tetrafluoride, represents toluenesulfonic acid or alkyl sulfuric acid, A represents a benzene ring or a naphthyl ring, and each ring may or may not have alkyl, alkoxy, hydroxy, carboxyl, halogen, allyl or alkyl carboxyl as a substituent. well, and n represents 0 or an integer from 1 to 3) (4) The optical recording medium according to claim (1), wherein the inorganic compound contains 50 atm % or more of Sb and also contains sulfur as another component element.