JPS61229243A - Method for recording and reproducing optical information - Google Patents

Abstract

PURPOSE:To attain recording/reproduction with high sensitivity and less deterioration in reproduction by using an optical information recording medium having a recording layer using a monomolecular accumulated film as a major layer, using light having a wavelength higher than the optical absorption of the recording layer at writing of information to write the information and using light having a wavelength with high light reflectance of the recording layer at read of information to read the information. CONSTITUTION:The information is written by using light having a wavelength with higher optical absorption of the recording layer at writing of optical information in the recording/ reproduction to/from the optical information recording medium consisting of the monomolecular accumulated film, while the information is read by using light having a wavelength with higher light reflectance of the recording layer at reading of the optical information. That is, in using the optical information recording medium for recording/reproduction of the information, the information is recorded by physical changes, chemical changes caused by the interaction of light and heat with the recording layer due to the irradiation of the write layer light or the optical characteristic changes attended with the change in the molecular aggregated structure. On the other hand, the information is reproduced by irradiating the read laser light to sense the change in the reflectance of the recording layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a recording and reproducing method for an optical information recording medium composed of a monomolecular cumulative film.

[Prior Art] Conventionally, in information recording and reproducing methods, writing and reading are performed using light of the same wavelength. In this case, the wavelength of the light is selected to have high absorption so as to achieve high sensitivity during writing, so it is natural that the reading light will also have high absorption and will gradually deteriorate as playback is repeated. I can't avoid it. Particularly, when a low melting point substance is used as a recording medium, this reproduction deterioration becomes a problem.

Therefore, one of the challenges for optical information recording media is how to reduce the reduction in the C/N ratio, that is, the reproduction deterioration caused by repeated reproduction.

[Purpose] The present invention has been made in view of the above problems, and its purpose is to provide recording and reproduction with high sensitivity and little reproduction deterioration in an optical information recording medium having a recording layer mainly composed of a monomolecular cumulative film. The purpose is to provide a method.

[Structure] In order to achieve the above object, the information recording and reproducing method according to the present invention writes information using light of a wavelength higher in optical absorption of the recording layer when writing optical information, and when reading out primary information. It is assumed that reading is performed using light of a wavelength having a higher light reflectance of the recording layer. Such a method of the present invention was made based on the following findings regarding the absorption spectrum and the opposite spectrum of a monomolecular cumulative film.

In other words, in films composed of ordinary monomers or powders, the absorption spectrum and specular reflection spectrum are gradually broadened without very sharp peaks, whereas in monomolecular cumulative films, the absorption spectrum and specular reflection spectrum are generally wide. Both spectra undergo a longer wavelength shift and the peak becomes sharper (this is thought to be due to the formation of J-disassembly).
By utilizing this fact, even a dye having an absorption peak around 70 Ona can be made into a monomolecular cumulative film to obtain a recording medium that can be used in a semiconductor laser in the near-infrared region with around 800 layers. In this way, when a monomolecular cumulative film is formed, both the absorption and reflection spectra have sharp peaks, but the peak wavelengths of the absorption spectrum and specular reflection spectrum are generally different (this means that the reflectance takes the peak value). By using this, recording is performed at a wavelength where absorption peaks, and when reading, changing the wavelength and performing at a wavelength where reflectance peaks, the readout light becomes smaller. Since the absorption is small, regeneration deterioration is reduced.

The "mono-molecule cumulative film" constituting the recording layer of the optical information recording medium used in the present invention is a layered structure in which molecules are regularly arranged (
Ml). Typical examples of this monomolecular cumulative film include, for example, the Langmuir-Prodgett method [for example, H. Kuhn et al.'s [Techniques of Chemistry].
Chemistry) J Volume ■, Bart IIIB
(John Wiley and Sons, New York, 197
Langmuir cumulative film (see 3rd year)
There is a ``I'LB membrane'' (hereinafter abbreviated as ``I'LB membrane''), which generally develops a solution of an organic compound on a liquid that is incompatible with the solvent of this solution and is inert to the solution and the substrate,
The monomolecular film is formed by immersing the substrate in this under a predetermined surface pressure to accumulate the monomolecular film on the substrate surface. The LB film obtained in this way is denser, more uniform, and has better mechanical strength than films produced by conventional film formation methods, but in order to further increase the mechanical strength, light or heat is applied to the film surface to polymerize it. Or it can be hardened. In addition to the above-mentioned Langmuir-Prodgett method (vertical dipping method), general methods for forming monomolecular cumulative films include the horizontal deposition method, in which the substrate is held horizontally with the monomolecular film without being immersed, and brought into contact with the monomolecular film and transferred. Alternatively, a method can be used in which a prism is brought into contact with a monomolecular film on the water surface and rotated with its axis horizontal, thereby transferring the prism continuously to the solid surface. Any method that can form a molecular assembly with controlled distance and molecular orientation can be used.

Furthermore, in order for such a monomolecular cumulative film to function as a recording layer of an optical information recording medium according to the present invention, the monomolecular cumulative film according to the present invention condenses the following functional molecules with molecules forming the following cumulative film. Alternatively, it can be produced by mixing (coexisting with) functional molecules including the functional molecules described below or derivatives thereof with molecules that form a cumulative film described below to form a cumulative film.

11 Yutachi L1 Polymethine dyes (merocyanine, cyanine, etc.), anthraquinone dyes, naphthoquinone dyes, phthalocyanine dyes, porphyrin dyes, xanthine dyes, phenanthrene dyes, triphenylmethane dyes, biryllium dyes, truffles Ettiazine dyes, croconium dyes, azulene dyes, tetrahydrocholine dyes, dioxazine dyes, dithiol metals (Ni, Go, Mn, Cu, Pt, Pd), aminium salt dyes, azo dyes, Carbazole quotient, pyrene compounds, alloxazine compounds, spiropyran compounds, squarylium dyes, pyridinium TCNQ complexes, etc.

- Long chain saturated fatty acids and their derivatives Cn H2n, acids represented by IC0OH (n-12 to 25), such as myristic acid, pentadecanoic acid, valmitic acid, heptadecanoic acid, stearic acid, nonadecanoic acid, eicosanoic acid, heneicosanoic acid , behenic acid and tetracosanoic acid. Hydrogen in the alkyl group may be substituted with other substituents.

Fatty acids can also be metal salts, such as Cd, Mn, C
o.

It may be a salt of Ca, 3a, or may be esterified or amidated.

・Long-chain unsaturated fatty acids and their derivatives a) Fatty acids with unsaturated bonds at the alkyl end or near the carboxyl group CH2=CH-GCH2Σ-7173 COOH (n=
12-25) (n=23, ω-tricosenic acid) (m-n'-1-25) (n'=17, m=o, α-octadecyl acrylic acid) b) Diacetylene derivative C-13 (C G (2) gi C Mi C
-10"C+cH2) ・C0OH (m-n-i~25) etc., c) II fatty acid unsaturated alcohol ester CH3 (CH
2). -〇〇〇H = CH(CH2) m ・H (m-n-1 to 25), etc., such as octadecyl acrylate, octadecyl acrylic acid amide, 1-n octadecyloxy-2,3-diacryloyloxypropane, octadecyl methacrylate,
Octadecylurea, octadecyl vinyl ether, vinyl stearate, ethyl stearate, elaidic acid, α-octadecyl acrylic acid, ω-tricosenoic acid,
ω-tricosenoic acid pentadionate, 10-12-
Heneicosenoic acid, 10-12-docosatuinic acid,
10-12-tetracosatuic acid, octadecyl fumaric acid cadmium salt, etc.

Furthermore, examples of solvents include chloroform, benzene, acetone, and mixtures thereof.

Water as a developing solution contains Cd ” + M n + G ′ I Ca to improve the stability of LBWA.
Embodiment ions such as "lB a "10÷ can be added.

In addition, since the monomolecular cumulative film of the present invention has molecules arranged regularly, (1) the directions of the transition dipoles are aligned, increasing the absorption coefficient and reflectance of the film; (2) the molecules The optical information recording medium used in the present invention exhibits the following characteristics: (3) improved density uniformity and increased density; and (4) improved film thickness uniformity. characteristics: high sensitivity, high contrast,
It contributes to higher recording density, improved stability against heat and light, and lower noise (higher S/N).

The recording layer of the optical information recording medium used in the method of the present invention is
Although it is formed by depositing a monomolecular film on a substrate (plastic, glass, etc.), it may be combined with two or more types of LB films to improve recording characteristics and stability. , tetrahydrocholine series, dioxazine series, triphetchazine series, phenanthrene series, polymethine (cyanine, merocyanine) series, anthraquinone (indanthrene) series, xanthine series, triphenylmethane series, croconium series, azulene series, biryllium series, squarylium series type, naphthoquinone type, etc. or metals such as In, 3n, Te.

It may be laminated with a+, AfL, sθ, As, Qd, etc. or a metal compound such as T e O2, S II O, etc. Furthermore, in the formation of the recording layer, stabilizers, dispersants,
Flame retardants, lubricants, antistatic agents, surfactants, plasticizers, etc. may be included. The thickness of the recording layer is in the range of 508 to 5 μm, preferably 100 to 1 μm.

The optical information recording medium used in the present invention basically has a recording layer mainly composed of a monomolecular cumulative film on a substrate. A protective layer can be provided on top of the underlayer and the recording layer. Necessary characteristics and constituent materials of the substrate, undercoat layer, and protective layer will be explained below.

The necessary characteristics of the substrate include that it must be transparent to the laser beam used only when recording and reproducing from the substrate side. Substrate materials include plastics such as polyester, polycarbonate, acrylic resin, polyimide, polyolefin resin, phenol resin, and epoxy resin, and commonly used recording material supports such as glass, quartz plate, metal, ceramics, and paper. Can be used. Note that in order to efficiently read and reproduce the optical information recording medium, it is preferable that a guide groove (pre-groove) be provided on the substrate.

The functions of the subbing layer are (a) improvement of adhesion, (b) barrier for water drainage or gas, (C) improvement of storage stability of the recording layer, (d) improvement of reflectance, and (e) solvent. It is used for the purpose of protecting the substrate from scratches and (f) forming pregrooves. For the purpose of (a), various polymeric materials such as ionomer resins, polyamide resins, vinyl resins, natural polymers, silicones, liquid rubbers, etc. and silane coupling agents can be used; (b) , (
For the purpose of C), inorganic compounds such as Si 02 , MgF2 , SiO, Ti 0
2, ZnO.

T+N, s+N, etc., metal or metalloid e.g. zn
, Cu, S, Ni, Cr, Ge, Se, C
d.

A (If, A1, etc.) can be used, and for the purpose of (d), metals such as Te, Ag, Al, and pigments with metallic luster such as methine dyes, xanthine dyes, biryllium dyes, etc. are used. can, and (e)
For the purpose of , m, ultraviolet curing resin, thermosetting resin, thermoplastic resin, etc. can be used. The thickness of the undercoat layer is in the range of 200 to 20 μm.

In addition, the protective i layer is provided for the purpose of protecting the recording layer from scratches, dirt, dirt, etc., improving the storage stability of the recording layer, and improving the reflectance, and its material is the same as that of the undercoat layer. material can be used.

The thickness of the protective layer is in the range of 1000 to 300 μm.

Furthermore, the formation of the subbing layer and the rII layer may be carried out by a dry method such as vapor deposition, CVD, sputtering, etc. or a wet method such as a solution coating method such as dip coating, spray coating, spray coating, blade coating, roller coating, curtain coating, etc. I can do it.

Further, the undercoat layer and the protective layer may contain stabilizers, dispersants, flame retardants, lubricants, antistatic agents, surfactants, plasticizers, and the like.

Further, the optical information recording medium used in the present invention may have an air-1 Nand-Gerch structure in which the pair of recording media configured as described above are sealed with another substrate with the recording layer inside through a space. Alternatively, it may have a close contact IJ bonding structure (laminated) with adhesive bonded via a protective layer.

When the optical information recording medium of the present invention is used for recording and reproducing information, information is recorded by physical shape change, chemical change, or molecular aggregation caused by interaction between the recording layer and its light or heat by irradiation with a writing laser beam. It is recorded by changes in optical properties due to changes in structure. On the other hand, information is reproduced by sensing changes in the reflectance of the recording layer upon irradiation with a reading laser beam.

[Example] The present invention will be specifically explained by giving an example below, but it is not limited thereto.Thickness: 1.211Il1
A chloroform solution with a molar ratio of 1:2 and arachidic acid was spread on the water surface on polymethyl methacrylate (PMMA) and repeatedly immersed at a surface pressure F of 25 dyne/cIR-1, resulting in a film thickness of about 400 people. ! I was formed and a recording medium was produced. The absorption spectrum and specular reflection spectrum of this recording medium are shown in FIG. The absorption spectrum is 5
The peak is around 990 people, and the specular reflection spectrum is 6.
The number peaks at around 090 people. A to this recording medium
Writing and reading were performed using an r laser-excited dye laser. Writing was performed at a wavelength of 5990 mm and a power of 3.0 mW, with a recording frequency of 0.7 from the substrate side.
Information was written at MHz and linear velocity of 1.2 m/Sec. This written information was then read out using light with a wavelength of 6090 nm and a power of 0.3 mw. C/
Compared to N, the C/N ratio hardly changes even after repeated reading at 52 dB 1 million times, indicating that reproduction deterioration is less likely to occur.

The IN2 diagram shows the absorption spectrum and specular reflection spectrum of the same pigment powder, and it can be seen that in LBll, the absorption spectrum is shifted by about 80 layers, and the specular reflection spectrum is shifted by about 10M.

[Effects] According to the present invention, a method for recording and reproducing information on an optical information recording medium with high sensitivity and little reproduction deterioration can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the reflection/absorption spectrum of the recording medium according to the present invention, and FIG. 2 is a diagram showing the reflection/absorption spectrum of the dye powder. Patent applicant Rico Co., Ltd. - 2 others

Claims (1)

[Claims] Using an optical information recording medium that has a recording layer mainly composed of a monomolecular cumulative film, when writing information, information is written using light of a wavelength for which the optical absorption of the recording layer is higher, while when reading information, the optical absorption of the recording layer is A method for recording and reproducing information, which is characterized by reading out using light of a wavelength with higher optical reflectance.