JPS59135641A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain a construction in which writing sensitivity, C/N of reading out and control of tracking are optimum by setting the thickness in the recording track part of a recording layer consisting of a dye or dye compsn. coated film on a base body having grooves for tracking at a specific value or below and detecting the presence or absence of a pit by reflected light. CONSTITUTION:A recording layer 4 is provided on one or both surfaces of a base body having grooves 3 for tracking roughly over the entire region of the base body surface in such a way that the recording layer has substantially a flat surface by filling said grooves. The layer 4 consists of a dye or dye compsn. and the recording layer 4 positioned on the projecting part on the base body surface isolated by the groove 3 is used as a recording track part for forming pits. The thickness in the recording track part of the recording layer positioned on the step of the groove 3 is <=0.2mum. If the thickness exceeds 0.2mum, writing sensitivity decreases. A decrease in reflectivity and a decrease in C/N of reading out are also resulted. The difference in the reflectivity between the recording track part and the other region is eliminated and the tracking control is difficult.

Description

DETAILED DESCRIPTION OF THE INVENTION l BACKGROUND OF THE INVENTION Technical Field The present invention relates to optical recording media, particularly heat mode optical recording media.

Prior art optical recording media have the characteristic that the recording medium does not deteriorate due to wear and tear because the medium and the writing or reading head are not in contact with each other, and for this reason, research and development of various optical recording media are being carried out.

Among such optical recording media, heat mode optical recording media are being actively developed because they do not require image processing in a darkroom.

This heat mode optical recording medium is an optical recording medium that uses writing light as heat. For example, a part of the medium is melted or removed using a recording light such as a laser to form a pit. Some devices perform writing by forming small holes, record information using these bits, and read by detecting the presence or absence of the pits using reflected light from the readout light.

As an example of such a pit-forming medium, a recording layer made of tellurium, tellurium selenium, arsenic, etc. is formed on a substrate by vapor phase deposition such as sputtering, and then melted to form pits. What it does is known.

In such a medium, a tracking groove is formed in the substrate, and a recording layer is deposited with a substantially uniform thickness on the groove and on the surface separated by the groove. The recording layer located at is used as a recording track section for forming pits, and writing is performed on this recording track section, for example, from the surface side of the recording layer.

In such a case, the thickness of the recording layer should be 0.01 to 0.05 to maximize recording sensitivity and reading C/N ratio.
It is said to be on the order of μm.

Additionally, when the writing or reading beam spot is about to deviate from the recording track, the grooves are used to bias the direction of the reflected light to one side for detection due to the interference effect caused by the phase difference based on the depth of the grooves. λ
/4 (λ is the wavelength of the beam light).

By the way, other examples of bit-forming media include those in which a recording layer made of a light-absorbing dye is coated and the dye is melted by the recording light to form bits, and self-oxidizing media such as nitrocellulose. A recording layer containing a thermoplastic resin and a light-absorbing dye is coated to form a pyratra by decomposing nitrocellulose, or a recording layer consisting of a thermoplastic resin and a light-absorbing dye is coated to form a resin and Some are known that melt pigments to form piratra.

Since a medium coated with such a recording layer does not use vacuum deposition, it is easy to manufacture.

However, as mentioned above, when a layer is applied to a substrate having tracking grooves, the coating film has a flat surface regardless of the presence or absence of grooves, and therefore The thickness and reflectance of the recording layer differ between the surface and the surface above the groove step. And it is smaller than the reflected light due to the interference effect due to the phase difference. For this reason, the optimum values for the thickness of the recording layer that maximizes the writing sensitivity and C/N ratio, and the groove dimensions that provide good tracking control have not yet been determined.

■ Purpose of the Invention The present invention was made in view of the above-mentioned circumstances, and its main purpose is to provide a recording layer comprising a coating film of a pigment composition on a substrate having tracking grooves. The present invention aims to provide a structure in which writing sensitivity, reading C/N ratio, and tracking control are optimized in a medium.

Such objects are achieved by the present invention as described below.

That is, the present invention provides tracking grooves formed on at least one surface of a substrate, and a dye or a dye composition formed on the surface having the grooves so that the surface is substantially flat. A recording layer is provided, and the recording layer located on the substrate surface separated by a groove is used as a recording rack section for forming pits, and the total thickness of the recording track section of this recording layer is 0.2 μm.
This optical recording medium is characterized in that writing is performed from the surface side of the recording layer, and the presence or absence of two dots after writing is detected by the reflected light of readout light from the surface side of the recording layer.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

A groove 3 for l-racking is formed on one or both surfaces of the substrate 2 of the optical recording medium 10 of the present invention (see FIG. 1).

Then, on one or both sides of the substrate having the tracking grooves 3, with the grooves filled, the recording layer surface is substantially flat over almost the entire surface of the substrate.
A recording layer 4 is provided. This is because the recording layer is formed by coating, which is different from the case where the recording layer is formed by vapor deposition.

In this case, the surface of the recording layer is substantially flat, meaning that the substrate surface (convex portion) separated by the groove is not exposed from the recording layer, and that the recording layer surface covers almost the entire surface of the substrate. It forms a continuous surface. And the surface of the recording layer is ±
It is preferable to form a flat surface with a surface precision of about 0.002 μm or less, especially about ±001 μm.

The recording layer 4 is made of a dye or a dye composition, and the recording layer 4 located on the convex portions of the substrate surface separated by the grooves 3 serves as a recording track portion for forming pits.

Thickness i of the recording track portion of the recording layer located above the three-step groove difference
When t, tldo must be 2 μm or less.

When the thickness exceeds 0.2 μm, writing sensitivity decreases. Also, the reflectance decreases and the readout C/
N ratio decreases. Furthermore, there is no difference in reflectance between the recording track portion and other areas (above the four groove portions), making tracking control difficult.

In such a case, t is the thickness t that provides the maximum reflectance of the readout light due to multiple reflections. (1o is generally 0.2 μm or less), whereas 0.3 to 1, G to,
More preferably, it is 0.5to to 1.4to.

The thickness t that gives this maximum reflectance. can be determined experimentally. Alternatively, it can be easily calculated by the method described in Kozo Ishiguro's "Optics" (Imori Zensho 56).

That is, when calculated, the reflectance R is given by the following formula.

, and further, in ηl-01-Jk1, = 2.3 ECλ/4π, and in η, N(+-C) +
NdC, where no is the refractive index of air, n2 is the refractive index of the substrate, N is the effective refractive index of the resin component of the dye composition, E is the effective extinction coefficient of the dye, λ is the wavelength used, and Nd is the effective refractive index of the dye. The refractive index and C are the effective weight concentration of the dye (in these cases, when two or more kinds of dyes or resins are contained, the effective value is used for each constant).

Therefore, R can be determined as a function of t from each constant using the above equation. And the value almost agrees with the experimental value.

Figure 2 shows the calculated results and actual measured values (marked with ○) of the reflectance R at 830 nm of the dye composition coating film and the film thickness of the coating film.
An example is shown.

For t obtained in this way, t is 0, 3 to
˜1.6t, the difference in reflectance between the region other than the recording track portion (above the groove recessed portion) where the film thickness differs due to the presence of the groove 3 becomes sufficiently large, and tracking control becomes extremely easy.

In such a case, it is preferable to use a semiconductor laser with a wavelength of 830, 780 to 750 nm as the writing light and reading light in order to miniaturize the entire device. Therefore, t is 0.04 to 0.15 μm1
More preferably, it is 0.05 to 0.1 μm.

On the other hand, the maximum depth d of the groove determines the thickness of other areas other than the recording track portion, and in the present invention, id, t+d
is the thickness of other areas.

As mentioned above, if tffo is set to 2 μm or less and the thickness is set to 0.3 to 1,6 to, the difference in reflectance between the recording track portion and other areas becomes sufficiently large, and tracking becomes difficult. This makes control extremely easy.

In such a case, in the present invention, since writing and reading using reflected light are performed from the surface side of the recording layer, it is preferable to detect failure of tracking control from the surface side of the recording layer.

In such a case, the difference between the reflectance of the readout light and the write light from the recording layer surface side of the recording track portion and the reflectance of other parts (above the groove recesses) is by a factor of 6, especially by a factor of 10 or more. It is preferable. At this time, the tracking error signal due to tracking control becomes extremely large.

Note that in a normal case, the reflectance of the recording track portion is set to be 6 or more, particularly 10 or more, higher than the reflectance of the other portions.

On the other hand, in order to create such a difference in reflectance between the outside and outside of the recording track section, t' must be set as described above.
When using a semiconductor laser etc., the depth d of the groove is usually 0.
．． The thickness may be set to 0.04 μm or more.

Note that in order to increase the read C/N ratio and the track error signal, the reflectance from the recording layer surface side for the read light and write light of the recording track portion should be 15
It is preferable that it is at least H.

Further, the width a of the recording track portion located on the groove step (inside the convex portion) is usually about 0.7 to 1.0 μm. In addition, the gap (width of the groove) b of the recording track portion is usually 1.5
The thickness should be approximately 2.5 μm.

Note that there are no particular restrictions on the shape of the groove.

A recording layer having such characteristics is formed from a dye or a dye composition.

That is, the recording layer may be formed only from the dye.

Various dyes can be used, but especially when using 750, 780, and 830 nm semiconductor lasers as writing light and reading light,
It is advantageous to use carbocyanine dyes in that a reflectance of 10% or more can be obtained.

There are various carbocyanine pigments (,
The rings at both ends of the carbocyanine linking chain may be any thiazole ring, oxazole ring, selenazole ring, imidazole ring, indole ring, pyridine ring, etc. to which a benzene ring, naphthalene ring, phenanthrene ring, etc. may be fused. .

Furthermore, the linking chain may be any known linking group for forming mono-, di-, tri- or tetracarbocyanine dyes, but is preferably a linking group for forming tricarbocyanine dyes. .

Among such carbocyanine dyes, those having an indole ring or benzoindole ring represented by the following formula CD are preferred.

Formula [I] Φ-L, ..., W (X-)m In the above formula CI), Φ and F represent residues of an indole ring or a benzindole ring, among which,
Φ has ten charges on the N atom of the indole nucleus, and 1 is the neutral N
It has atoms.

Each of them may be the same or different, and various substituents can be bonded to them.

Among these, Φ and T are preferably the same, and particularly preferably those represented by the following formulas [1[) to [v].

In this case, the charge symbol (・) attached to the 2-position of the indole ring
represents that 10N> for Φ and N>=1 for W.

Expression [v] (a, ).

In the above formulas [■] to [v], R represents a substituted or unsubstituted alkyl group.

The number of carbon atoms in the alkyl group is preferably 1 to 5, and preferable substitutions and groups include a sulfonic acid group and an alkylcarboxyoxy group.
In addition, examples of the substituent include an alkylamido group, an alkyloxy group, a carboxylic acid group, and a hydroxyl group.

Note that R may be a substituted or unsubstituted oryl group.

In such a case, when m (described later) is 0, R of Φ
has one charge.

Furthermore, R3 and R15 each represent an alkyl group or an aryl group such as a phenyl group, preferably an alkyl group. In this case, the alkyl group is preferably unsubstituted and has 1 or 2, especially 1, carbon atom.

Further, R4 represents a substituent, which may be an alkyl group, an aryl group, a heterocyclic residue, a halogen atom, an alkoxy group, an alkylthio group, an alkylhydroxycarbonyl group, a carbo/acid group, or the like.

Further, p is usually an integer of 0 to 4, and when p is 2 or more, the plurality of R4s may be different from each other.

However, if there is no particular need, p may be 0.

On the other hand, L represents a linking group that forms a mono-, di-, tri- or tetracarbocyanine, especially the following formula [■
] to [■] is preferable.

Formula (■:) CH=CI-1-CH=C-CH=CI-
1-CHl Formula CX ml CH=CH-CH=CH-C=CH-C
l-1=CH-CH formula [: M:] CH=CH-C
Tadashi CH-CH formula [Kari] CH= C-CH Here, Y represents a hydrogen atom or a monovalent group. In this case, the monovalent group includes a lower alkyl group such as a methyl group, a lower alkoxy group such as a methoxy group, a dimethylamino group, a dimethylamino group, a methylphenylamino group, a morpholino group, an imidazolidine group, and an ethoxycarbonylbiverazine group. Preferred examples include di-substituted amino groups such as acetoxy groups, alkylcarbonyloxy groups such as acetoxy groups, alkylthio groups such as methylthio groups, halogen atoms such as Br and C4, cyano groups, and nitro groups.

In addition, among these formulas [■] to [Kari], formulas [■] to [X] of tri or tetracarbocyanine, especially formula [■]
, [■] are preferred.

Furthermore, X- is an anion, and its preferred examples are: -1Br-1CtO-1BF, -1 Note that m is 0 or 1, but when m is O, it is usually Φ
R□ has a single charge and becomes an inner salt.

Specific examples of these carbocyanine dyes will be obvious from the above description. Specific examples of these carbocyanine dyes included in the above formula CI) are shown below, but the present invention is not limited to these.

Dye/f6Φ, F RR2 DI [Tl:] -CH-C
I-13D2 [11]
-C8-C■D3
[:II,:l-CI-1
-CHD5 [ffr] -CH5-CI-(
D 8 [:+v,:ll-C2H3-C
I4D [■]-(CH2)30COCH3
-CI-1r+lo [IV]-CH-CI
-(Dll [l -CH-C
I-1-CH-H[w:] HI I-CH-H[v] HCtO-CH-H[
v:] H--CH-H[]HCtO-CH-H[:] H--Cl-1-H[:w:]' HBF-C
H-H [■] HCzO-CH-H [■]
H1 Such carbocyania dyes are laser-polished at 9°C 8 (
4) They are described in the Comprehensive List of Organic Compounds for Dye Lasers, Dai-Organic Chemistry (Breakfast Shoten), Nitrogen-Containing Heterocyclic Compounds IP 432, and can be synthesized by known methods.

Incidentally, such a dye may be supported and bonded to various resins described below under medium pressure to form a dye.

Such a dye may constitute the recording layer alone.
Alternatively, it is contained in the recording layer together with a self-oxidizing or thermoplastic resin.

In the latter case, crystallization in the layer is suppressed and the physical properties of the film are better than when the recording layer is formed using only the dye.

The self-oxidizing resin contained in the recording layer undergoes oxidative decomposition when the temperature rises.

An example of such a self-oxidizing resin is the patent application published in 1983.
Among these, nitrocellulose is particularly preferred.

In addition, the thermoplastic resin contained instead of or in addition to the self-oxidizing resin softens when the temperature of the light absorber that absorbs the recording light increases. Various known materials can be used as the material.

Among these, thermoplastic resin pressures that can be particularly suitably used include the following.

i) Polyolefin polyethylene, polypropylene, poly4-methylpentene-1, etc.

if) polyolefin copolymers, such as ethylene-vinyl acetate copolymers, ethylene-acrylate copolymers, ethylene-acrylic acid copolymers,
Ethylene-propylene copolymer, ethylene-butene-1
copolymers, ethylene-maleic anhydride copolymers, ethylene propylene terpolymers (EPT), etc.

In this case, the polymerization ratio of the comonomers can be arbitrary.

Vinyl chloride copolymers such as vinyl acetate-vinyl chloride copolymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloride-maleino acid anhydride copolymers, copolymers of acrylic esters or methacrylic esters and vinyl chloride. polymer, acrylonitrile-vinyl chloride copolymer, vinyl chloride ether copolymer,
Ethylene or propylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer with vinyl chloride graft polymerized, etc.

In this case, the copolymerization ratio can be arbitrary.

iv) Vinylidene chloride copolymer Vinyritine chloride-vinyl chloride copolymer, Vinylizo chloride/
- Vinyl chloride-acrylonitrile copolymer, vinylidene chloride-butadiene-vinyl halide copolymer, etc.

In this case, the copolymerization ratio can be set arbitrarily.

V) Polystyrene vi) Styrene copolymer For example, styrene-acrylonitrile copolymer (AS resin), styrene-acrylonitrile-butadiene copolymer (ASB resin), styrene-maleic anhydride copolymer (SMA resin) ), styrene-acrylic ester-acrylamide copolymer, styrene-butadiene copolymer (S
BR), styrene-vinylidene chloride copolymer, styrene-methyl methacrylate copolymer, etc.

In this case, the copolymerization ratio can be arbitrary.

vi) Styrenic polymers such as p-methylstyrene, 2,5-dichlorostyrene, α,β-vinylnaphthalene, α-vinylpyridine,
Acenaphthene, vinylanthracene, etc., or copolymers thereof.

vii) Kumalo/-indene resin Coumaron-inch/-styrene (') combination.

ix) Terpene resin or picolite For example, terpene resin which is a polymer of limonene obtained from α-pinene or picolite obtained from β-pinene.

X) Acrylic resin Particularly preferred are those containing an atomic group represented by the following formula.

Ceremony R-work.

CH-C- C-0RQ.

1 In the above formula, Rlo represents a hydrogen atom or an alkyl group, and R3° represents a substituted or unsubstituted alkyl group. In this case, in the above formula, Rlo is preferably a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms, particularly a hydrogen atom or a methyl group. Also,
R2o may be a substituted or unsubstituted alkyl group, but the alkyl group preferably has 1 to 4 carbon atoms, and when R2o is a substituted alkyl group, a substituted alkyl group The group is preferably a hydroxyl group, a halogen atom or an amine group (particularly a dialkylamino group).

The atomic group represented by the above formula may form a copolymer with other repeating atomic groups to constitute various acrylic resins, but usually one type of atomic group represented by the above formula is used. Alternatively, an acrylic resin is formed by forming a homopolymer or copolymer having two or more repeating units.

xi) Polyacrylonitrile) Acrylic nitrile copolymer such as acrylonitrile-vinyl acetate copolymer, acrylnitrile-vinyl chloride copolymer, acrylonitrile-styrene copolymer, acrylonitrile-vinylidene chloride copolymer, acrylic Nitrile-vinylpyridine copolymer, acrylonitrile-methyl methacrylate copolymer,
Acrylonitrile-7'tadiene copolymer, acrylonitrile-butyl acrylate copolymer, etc.

In this case, the copolymerization ratio can be arbitrary.

X1iI) Dianeptone acrylamide polymer Dianeptone acrylamide polymer made by reacting acrylonitrile with acetone.

xiv) Polyvinyl acetate Xv) Vinyl acetate copolymers, such as copolymers with acrylic esters, vinyl ethers, ethylene, vinyl chloride, etc.

The copolymerization ratio may be arbitrary.

xvi) Polyvinyl ethers such as polyvinyl methyl ether, polyvinyl ethyl ether, polyvinyl butyl ether, etc.

xvi) Polyamide In this case, the polyamide includes nylon 6, nylon 66, nylon 610, nylon 612, nylon 9,
In addition to normal homonylons such as nylon 11, nylon 12, nylon 13, etc., nylon 6/66/610. Copolymers such as nylon 6/66/12 and nylon 6/66/11, or modified nylon in some cases may be used.

i) Polyesters with various dibasic acids such as aliphatic dibasic acids such as oxalic acid, succinic acid, maleic acid, adipic acid, sebastenic acid, or aromatic dibasic acids such as isophthalic acid, terephthalic acid, etc., and ethylene. Condensates and co-condensates with glycols such as glycol, tetramethylene glycol and hexamethylene glycol are suitable. Among these, condensates of aliphatic dibasic acids and glycols and co-condensates of glycols and aliphatic dibasic acids are particularly
Particularly suitable.

Furthermore, for example, a modified gliptal resin, which is a condensation product of phthalic anhydride and glycerin, is esterified and modified with a fatty acid, a natural resin, etc., and the like can also be suitably used.

xix) Polyvinyl acetal resin Both polyvinyl formal and polyvinyl acetic resin obtained by acetalizing polyvinyl alcohol are preferably used.

In this case, the degree of acetalization of the polyvinyl acetal resin can be arbitrary.

xx) Polyurethane resin Thermoplastic polyurethane resin having urethane bonds Particularly suitable are polyurethane resins obtained by condensation of glycols and diisocyanates, especially polyurethane resins obtained by condensation of alkylene glycol and alkylene diisocyanate. .

Field) Polyether styrene formalin resin, ring-opening polymer of cyclic acetal, polyethylene oxide and glycol, polypropylene oxide and glycol, propylene oxide-ethylene oxide copolymer, polyphenylene oxide, etc.

−) Cellulose derivative Organic acid esters, ethers or mixtures thereof.

Tsumugi) Polycarbonate such as polydioxydiphenylmethane carbonate,
Various polycarbonates such as polydioxydiphenylethane carbonate and dioxydiphenylpropane carbonate.

xxiv) A blend of two or more of the above i) to) OaiI), or a blend with other thermoplastic resins.

Note that the self-oxidizing compound and the thermoplastic resin may have various molecular weights.

Such an autooxidizing compound or thermoplastic resin and the above-mentioned dye are usually formed in a wide range of weight ratio of 1:0.1 to 100.

Furthermore, it is preferable that the recording layer contains a -heavycyclic oxygen quencher.

- Various types of heavy ring oxygen quenchers can be used, but in particular, those that greatly improve stability and light resistance, increase absorption of long-wavelength writing laser light, and further reduce reproduction deterioration. Transition metal chelate compounds are preferred because they reduce the amount of carbon dioxide and have good compatibility with dyes.

In this case, as the central metal, Ni, Co, Cu, Pigeon, etc. are preferable, and the following compounds are particularly preferable.

In addition, as a transition metal chelate compound, 700 to 85
Those with absorption in Q nm, especially 700~
It is preferable to have a maximum absorption wavelength at 85 Q nm.

1) Acetylacetonate chelate QI N1(I[)acetylacetonate Q2 Cu(
1) Acetylacetonate Q3 Mn(III) Acetylacetonate Q4 Co(II) Acetylacetonate 2) Bisdithio-α-diketone system Here, d11~di) represents an alkyl group or an alkyl group, and M represents a divalent transition metal atom.

Q5 N1 (II) Jichi 7 Be/Jill Q6　N1(II) Zikoobiacetel ,).

3) Bisphenyldithiol system and U7, N5) and N63 represent an alkyl group such as a methyl group, or a halogen atom such as Ct,
and t is 0 to 4, and M&! Represents a divalent transition metal atom such as Ni.

Moreover, further coordination may be performed above and below M in the above structure.

As such, the following two are commercially available.

Q9PA-1001 (product name manufactured by Mitsui Toatsu Fine Co., Ltd.) QIOPA-1o O2 (same as above) Qll PA-1003 (same as above) Q12 PA-1005 (same as above) Q13 PA-1006 (same as above) 4) Salicylaldehyde In the oxime system, d71 and 8) represent an alkyl group,
M represents a divalent transition metal atom.

Q14 N1(II) 0-(N-isopropylformimidoyl)phenol Q15 N1(1) O-(N-dodecylformimidoyl)phenol Q16 Co(I[) 0-(N-dodecylformimidoyl)phenol Q17 Cu(II) 0-(N-dodecylformimidoyl)phenol QIB N1(II) 2,2'-[trilomethylidine on ethylene bis]-diphenol Q19 Co(II)2,2'-C trilomethylidine on ethylene bis )]-diphenol Q20 N1(U) 2-2' C1,8-naphthylenebis(= l-IJ lometeridine)]-diphenol Q21 N1(I[) -[N-phenylformimidoylsiphenol Q22 Co(TI) -[N-phenylformimidoylsiphenol Q23 Cu(If) -[N-phenylformimidoylsiphenol Q24 N1(II) Salicylaldehyde phenylhydrazone Q25 N1(1) Salicylaldehyde oxime 5) Thiobisferrate chelate system R( 91RQI 芹υ Here, M is the same as above, R(9) and 敞0 represent an alkyl group, and R(4) represents an amino group.

Q26 N1(II) n-butylamino[2,2'-
Thiobis(4-tert-octyl)-phenolate] Q27 N1(II) n-butylamino(2,2'
-Thiobis(4-tert-octyl)-ferulate] Such a doublet acid cumulative quencher is synthesized according to a known method.

The -1 term oxygen quencher is generally 0.05 to 12 mol, particularly 0.1 to 1.2 mol, per 1 mol of the dye.
It is contained in about molar amount.

To form such a recording layer, it is generally necessary to apply it by coating according to a conventional method, and the thickness thereof is generally about 0.03 to 2 μm. Alternatively, when forming the recording layer using only the dye, vapor deposition, sputtering, etc. may be used.

In addition, such records j~ may also contain other polymers or oligomers, various plasticizers, surfactants, antistatic agents, lubricants, flame retardants, stabilizers, dispersants, etc. .

Examples of solvents used for coating include ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, esters such as butyl acetate, ethyl acetate, carpitol acetate, and butyl carpitol acetate, and ethers such as methyl cellosolve and ethyl cellosolve. or aromatic systems such as toluene and xylene, and halogenated alkyl systems such as dichloroethane.

There is no particular restriction on the material of the substrate on which such a recording layer is provided (it may be any of various resins, glass, ceramics, metals, etc.).

In addition, the shape varies depending on the purpose of use, such as tape, disk,
It may be a drum, a belt, etc. Furthermore, there is no particular restriction on the thickness.

Note that the base body 1 may be provided with a base layer such as a heat storage layer, if necessary.

Furthermore, a top protective layer or the like may be provided on the north side of the recording layer, if necessary.

The medium of the present invention may have a recording layer on one surface of such a substrate, or may have recording layers on both surfaces thereof.

In addition, two substrates with recording layers coated on one surface are used, and the recording layers are placed facing each other with a predetermined gap between them. You can also choose not to connect.

(2) Specific Effects of the Invention The medium of the present invention is irradiated with writing light in pulses from the surface side of the recording layer while the medium is running or rotating. At this time, due to the heat generated by the dye in the recording layer, the self-oxidizing resin decomposes or the thermoplastic resin or dye melts.
A pit is formed.

In this case, especially when a tri- or tetracarbocyanine dye is used, very good writing can be achieved when a recording semiconductor laser with a wavelength of 750.780.830 nm is used.

The pits formed in this way are read out by irradiating readout light of the wavelengths listed in the above in a pulsed manner from the surface side of the recording layer while the medium is running or rotating, and detecting the reflected light.

Further, to control tracking, normally, while writing or reading is being performed, the reflected light is divided and introduced into a pair of divided sensors. In this case, when the beam spot begins to deviate from the recording track section, the reflectance differs at the bottom of the groove step due to the presence of the groove, so if the difference between the signals of both sensors is detected, a track error signal can be detected. will be done.

Note that another dedicated light source may be used for tracking control.

Further, as for the optical system, it is preferable to condense light using a lens having an aperture ratio (NA) of about 0.5.

Note that when a thermoplastic resin is used for the recording layer, the pits once formed in the recording layer can be erased with light or heat, and rewriting can be performed on the rows.

Furthermore, a He--Ne laser or the like can also be used as the recording or reading light.

(2) Specific Effects of the Invention According to the present invention, the writing sensitivity and reading C/N ratio are extremely high.

Since the tracking error signal is large, tracking control becomes extremely easy.

The present inventors conducted various experiments to confirm the effects of the present invention.

An example is shown below.

Example 1 Dye/16D1 and nitrogen content 11.5-12.2
%, nitrocellulose with a viscosity of 20 seconds based on JIS K6703, and the above-mentioned -4,l [Quencher-Q13, in weight ratios of 3゜wt%, 55wt%, and 1, respectively.
The solution was dissolved in a solvent (dichloroethane, 2 dichlorohexanone: 1: methyl isobutyl ketone) and coated onto an acrylic disk substrate having a diameter of 15 crn and a thickness of 2.

In this case, the substrate has a width (a) of 2 μm on the coating surface.
and rectangular grooves with a depth d) of 0.07μmρ at intervals (b)
0.1? The one formed in μm was used.

AtGaAs-GaAs semiconductor laser (830 nm
) is shown in FIG. 2, which is a plot of calculated values of reflectance and film thickness when irradiated from the surface side of the recording layer.

Figure 2 ((actual value of reflectance when changing film thickness/)
Gourd It is also written with a 0 mark. In addition, 10 is 007
It was ltm.

Next, a recording layer is coated on the groove-formed surface of the substrate so that the protrusions of the grooves -1- are used as recording track parts, and the recording layer is formed so that the recording (-rack thickness (1)) is as shown in Table 1 below. Layered.

For each medium created in this way, add 1800
While rotating at rpm, A tGaA 5-GaAs
Semiconductor 1/- laser recording light (8301m') is focused to 1μ rich φ with a lens of NA 20.5, condensing section output]Qm
V), the pulse train was irradiated at a predetermined frequency.

Each medium (detsuki) was irradiated by changing the pulse width of the writing light, and the pulse rlJ that gave an extinction ratio of 2.5 was measured.
The reciprocal of the value was taken as the writing sensitivity. Table 1 shows the results.
Shown below.

In this case, the extinction ratio is the degree of attenuation of the reflectance of the readout light on the medium surface, which will be described later, at the pit portion.

Separately, writing was performed with a pulse width of 1QQnsec.

After IR, 1 mW semiconductor 1 noser (830
nm) readout light was irradiated as a pulse of 2 Ml4z with a width of 1 μSeC (lens NA=0.5), and the initial peak-to-peak C/N ratio on the disk surface was measured.

Note that during writing and reading, reflected light was guided to a two-split sensor by a beam splitter, and the difference between the detection signals of both sensors was taken and used as a tracking error signal to control tracking.

The magnitude of the track error signal is also listed in relative values in Table 1 below.

From the results shown in Table 1, the effects of the present invention are clear.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of the present invention, and FIG. 2 is a graph showing an example of the relationship between reflectance and recording layer thickness. 1...... Optical recording medium 2...
・・・・・・Substrate 3・・・・・・・・・・・・Groove 4・・・・・・・・・Recording layer 1 Applicant Tokyo Denki Kagaku Kogyo Co., Ltd. Agent Patent attorney Akira Ishii - Procedural amendment stamp button 6 June 23, 1980 Director-General of the Patent Office Kazuo Wakasugi Patent Application No. 10159 of 1981 ■ 2. Name of the invention
, Optical recording medium 3, Person making the amendment Relationship to this case Patent applicant Location
Nihonbashi-chome 13-1 1, Chuo-ku, Tokyo
1 Name (306) TDC Co., Ltd. Representative: Kan Otoshi 4, Agent Address: 5-17-11 Nishiikebukuro, Toshima-ku, Tokyo 171
Goyabe Building 1st Floor Telephone: 988-1680 The description in column 1 of the Detailed Description of the Invention in 1m3 of the Statement of Contents of the Amendment is amended as follows. nj, 1rNi, Co, Cu, Mn. d and Ptj. ) 3rd + page 1' 1st line ~ 3rd? The information from page number to line is corrected as follows. 1) Acetylacetonate chelate QINi (TI
) Acetylacetonate Q2 Cu(II) Acetylacetonate Q3 Mn(■) Acetylacetonate Q
4GO (II) Acetylacetonate 2) Bisdithio-α-diketone system Here, R (1) and R (4) represent a substituted or unsubstituted alkyl group or aryl group, and M is Ni
, represents a transition metal atom such as Co, Cu, Pd, Pt, etc. In this case, M has a single charge and may form a salt with a cation such as a quaternary ammonium ion. Q5 N1(T'l) dithiobenzyl Q6Ni(II
) Dithiobiacetyl N"(C4H9)4 3) Bisphenyldithiol system (5) (fi) Here, R and R represent an alkyl group such as a methyl group, or a halogen atom such as (11), and M is , Ni, Co. Represents a transition metal atom such as Cu, Pd, or Pt. Furthermore, k and parent are each an integer of 0 or 4 or less. In addition, M in the above structure has a single charge, and represents a cation and a salt. Furthermore, other ligands may be bonded above and below M. Examples of such ligands include the following: QIOPA-1001 (product name: Mitsui Higashi) Qll PA-1002 (same as above) Q12 PA-1003 (same as above) Q13 PA-1005C as above JlNi-bis(dichlorobenzene) Tetra(t-butyl)ammonium] Q14 Same as FA-1006C J-NI-bis(trichlorobenzenedithiol) Tetra(t-butyl)ammonium] Q15 Co-Bis(benzene-1,2-dithiol)tetrabutylammonium Q16 Co- Bis(O-xylene-4,5-dithiol)tetra(t-butyl) ammonium Q17 NI-bis(benzene-1,2-dithiol)tetrabutylammonium Q18 NI-bis(0-xylene-4,5-dithiol) Tetrabutylammonium Q19 NI-bis(5-chlorobenzene-1,2-
dithiol) tetrabutylammonium Q20 Nt-bis(3,4,5,6-tetramethylbenzene-1,2dithiol)tetrabutylammonium(lJ21Ni-bis(3,4,5,6-tetrachlorobenzene-1,2dithiol) ) Tetrabutylammonium 4) Salicylaldehyde oxime system (?) (8) Here, R and R represent an alkyl group, and 1M is Ni, Co, Cu. Represents a transition metal atom such as Pd or Pt. Q22 Ni (TI)o -(N-isopropylformimidoyl)phenol Q23 Ni (II)o -(N-dodecylformimidoyl)phenol Q24 Co(II)o -(N-dodecylformimidoyl)phenol Q25 Cu (II) o -(N-dodecylformimidoyl)phenol Q26 Ni (TI)2.2' (trilomethylidine on ethylene bis)]-diphenol Q27 Co(II)2.2'-(trilomethylidine on ethylene bis)] -Diphenol Q28 N1(II)2.2' -(1,8-
Naphthylenebis trilomethylidine)]-diphenol Q29 N1(II)-(N-phenylformimidoyl)phenol Q30 Co(II)-(N-phenylformimidoyl)phenol Q31 Cu(II)-(N-phenylformimide yl) Phenol Q32 N1(II) Salicylaldehyde Phenylhydrazone Q33 Nt(II) Salicylaldehyde oxime 5) Thiobisferrate chelate system (9) Here, M is the same as above, R(lO) and R are , represents an alkyl group. Further, M has a single charge and may form a salt with a cation. Q34 N1(II) n-butylamino [2゜2'-
Thiobis (4-tert-octi JL/ ) y x
root) (Cyasorb-UV-1084(
7me! J force y shift mid co,,L
td, ) ) Q35 Co(II) n-butylamino [2゜2'-thiobis(4-tert-octyl)
-Felt] Q36 N1(TI)-2,2'-thiobis(4-t
ert-octyl)-ferrate" ■) In the 9th line of page 44, replace l1Q13J with l1Q13J.
Correct as rQ 14j. 241-0

Claims (1)

[Claims] 1. Tracking grooves are formed on at least one surface of the substrate, and a dye or a dye composition is applied to almost the entire surface of the surface having the grooves so that the surface is substantially flat. The recording layer located on the substrate surface separated by the groove is used as a recording track section for forming pits, and the total thickness of the recording track section of this recording layer is 0.2 μm or less, and from the recording layer surface side. An optical recording medium characterized in that writing is performed and the presence or absence of pits after writing is detected by the reflected light of readout light from the surface side of the recording layer. 2. The thickness t of the recording track portion of the recording layer is the thickness ft that provides the maximum reflectance of the read light. When closed, 0.3to≦t≦1.6t. An optical recording medium according to claim 1. 3. The optical recording medium according to claim 2, wherein t is 0.04 to 0.15 μm. 4. Claim 1, wherein the difference between the reflectance of the recording track portion of the recording layer and the reflectance of other areas of the recording layer is 6% or more.
The optical recording medium according to any one of Items 1 to 3. 5. The optical recording medium according to any one of claims 1 to 4, wherein the maximum depth of the groove is 0.04 μm or more. 6. The optical recording medium according to any one of claims 1 to 5, wherein the recording track portion of the recording layer has a reflectance of 15 or more. 7. The optical recording medium according to any one of claims 1 to 6, wherein the recording layer comprises only a dye. 8. The optical recording medium according to any one of claims 1 to 6, wherein the recording layer is made of a dye composition, and the dye composition contains a self-oxidizing or thermoplastic resin together with the dye. 9. The optical recording medium according to any one of claims 1 to 6 or 8, wherein the recording layer is made of a dye composition, and the dye composition contains a singlet oxygen quencher together with the dye. 10. The optical recording medium according to any one of claims 1 to 9, wherein the dye is a carbocyanine dye. 11. The optical recording medium according to any one of claims 1 to 10, wherein the recording layer is formed by coating.