JPH0632996B2 - Optical recording method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical recording method for writing information such as ridge image and sound on an optical recording medium by exposure to ultraviolet light.

[Prior Art] With the advance of laser technology in recent years, optical recording using a laser beam for recording and reproducing information has attracted attention, and many pieces of one information such as a video disc and an audio disc can be duplicated and presented to users. Supply has been put to practical use. Such an optical recording system has an extremely high recording density, has a long life due to non-contact reading, and has a short random access time.Accordingly, advantages that cannot be achieved by conventional analog recording systems such as records and magnetic recording are recognized. Has been.

However, on the other hand, these recording media for video discs and audio discs have small recording pits of 1 μm or less formed by mechanical methods such as injection molding and press molding, and require an expensive precision molding machine. In addition, there are many problems in terms of production technology such as restrictions on the molding material and clogging of the stamper for pit transfer.

The present inventors have studied an optical recording medium that can be produced in a high yield with a simpler device, and previously disclosed JP-A-57-19533.
6 and 57-195341 proposed optical recording system and medium.

That is, these recording systems and media, the desired position of the recording layer containing a compound having absorption in a specific visible to near-infrared wavelength region, ultraviolet rays, the active energy ray of the electronic formula or the like of the compound Utilizing the attenuation of absorption in the visible to near-infrared wavelength region, recording and reading and reproduction are performed with a laser beam having an oscillation wavelength in the visible to near-infrared wavelength region. It has the feature that it does not require any formation.

[Problems to be Solved by the Invention] However, the attenuation of visible to near-infrared absorption corresponding to a reading laser beam when an active energy ray is exposed requires a so-called exposure light source with a large energy for a relatively long exposure time. It is necessary to improve the recording exposure sensitivity.

Therefore, an object of the present invention is to provide an optical recording method capable of improving the above-mentioned exposure sensitivity and performing recording with the improved exposure sensitivity on an optical recording medium used for recording and reproducing based on the above principle. To provide.

[Means for Solving the Problems] The optical recording method according to the present invention has the general formula (I):[In Formula (I), Y is -H, -SO₃ , -SO₃H, −SO₃Na
 Or −SO₃K, l is an integer of 1 to 4, Y '
Is -H, -SO₃H, −SO₃Na or −SO₃K and n is 1
Is an integer from 4 to 4, m is 3 or 4, X Is halo
Gen ion, ClO_FourOr BF_FourMonovalent anion represented by
And Y is -SO₃ X when Does not exist
Optical recording having a recording layer containing a dye having a structure
An optical recording method using a recording medium, comprising:
Irradiate ultraviolet rays with a wavelength of 0 nm or less to the irradiated area
By reducing the absorption of the reproduction laser light in
It is characterized in that rewriting is performed.

As the above-mentioned dye which is an essential component of the recording layer of the present invention,
For example A dye having a structural formula such as the above, and the type of the substituent or the coordinating ion may be changed as represented by the general formula (I), not limited to these, and these dyes may be You may use it in mixture of 2 or more types.

The above dye has a maximum absorption in the visible or near-infrared wavelength region of 700 to 1000 nm, and exhibits strong absorption in the visible or near-infrared wavelength region oscillation wavelength of laser light used for recording and reproduction, while having a wavelength of 400 nm or less. It has the property of irreversibly attenuating the absorption characteristics of light in the visible or near-infrared wavelength region, probably because the chemical structure is changed when it is irradiated with ultraviolet rays.

The above dyes are dissolved in strongly polar solvents such as methanol, ethanol, isopropanol, dimethylformamide, dimethylsulfoxide, tetrahydrofuran, N-methylpyrrolidone, acetone, diacetone alcohol, acetylacetone and ethylene glycol monomethyl ether. On the other hand, resin components soluble in these polar solvents, for example, polymethyl methacrylate, acrylic resins such as polymethyl acrylate, for example, polyvinyl acetate, polyvinyl alcohol esters such as polyvinyl propionate, such as polyvinyl formal, polyvinyl acetal, Polyvinyl butyral, polyvinyl alcohol ethers such as polymethyl vinyl ether, cellulose derivatives such as nitrocellulose, cellulose acetate, cellulose propionate, etc. It is applied to the combined substrate material forming the recording layer was evaporated to remove the organic solvent. The content of the dye in the recording layer is usually 0.1 to 10% by weight and is appropriately selected depending on the thickness of the recording layer and the like.

It is also possible to mix and use a so-called photosensitizer that generates radicals or cations by ultraviolet rays having a wavelength of 400 nm or less in the recording layer.
The absorption of the dye in the visible to near-infrared wavelength region due to the irradiation of ultraviolet rays having a wavelength of 400 nm or less is further promoted, that is, the recording sensitivity is improved. The photosensitizer includes, for example, a substance that generates a photoradical or a substance that generates a cation upon irradiation with ultraviolet rays having a wavelength of 400 nm or less. Examples of the substance that generates a photoradical include benzophenone, p-methylbenzophenone, and p-methylbenzophenone. -T-butylbenzophenone, methylorthobenzoylbenzoate, orthobenzoylbenzoic acid, 4,4 '
-Bisdimethylaminobenzophenone, 4,4'-bisdiethylaminobenzophenone, 4-dichloroacetylbenzophenone and other benzophenone sensitizers; acetophenone, 2,2-diethoxyacetophenone, p-ta-jaributyltrichloroacetophenone and other acetophenone-based sensitizers Sensitizers; 2-hydroxy-2-methyl-propiophenone, propiophenones such as 4'-isopropyl-2-hydroxy-2-methylpropiophenone; benzoin,
Benzoin sensitizers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; anthraquinone sensitizers such as anthraquinone, methylanthraquinone, ethylanthraquinone; benzyl such as benzyl, benzyldimethylketal, and benzyldiethylketal Sensitizers; thioxanthone, 2-chlorothioxanthone, 2-
Thioxanthone-based sensitizers such as methylthioxanthone, 4-isopropylthioxanthone and 2-acetylthioxanthone; ethyl 4-dimethylaminobenzoate, ethyl 2-dimethylaminobenzoate, 2- (n-butoxy)
Benzoic acid ester-based sensitizers such as ethyl 4-dimethylaminohenzoate; azonitriles such as azobisisobutyronitrile and azobisvaleronitrile; benzyl azide, orthonaphthoquinone diazide, polyvinylbenzyl azide, polyvinylbenzyl sulfonyl azide, etc. Examples include azide-based sensitizers. These are used alone or in combination of two or more.

Examples of sensitizers that generate cations upon irradiation with ultraviolet light having a wavelength of 400 nm or less include (i) Group Va element onium salts, (ii) Group VIa element onium salts, and (iii) aromatic halonium salts. (Iv) aromatic diazonium salts and the like are used.

When using a photosensitizer as described above, the amount is usually
It is preferably 0.01 to 5.0% by weight in the recording layer.

The thickness of the recording layer is usually 0.1-10 .mu.m, preferably 0.2-2.
It is desirable to adjust the concentration and thickness of the dye so that the transmittance of the recording layer is 5 to 50% at the oscillation wavelength of the reproducing laser. Particularly, a reflective layer is formed on the surface of the recording layer and the amount of reflected light is used for recording. Transmittance 10 to 50 when reading signal during playback
% Is preferable.

The substrate that is the support of the recording layer is, for example, methacrylic resin,
Transparent sheets or films of various plastics such as polystyrene resin, polycardnate resin, polyester resin, polyvinyl chloride resin, etc., transparent inorganic plates such as glass, translucent ceramics, etc. are usually used, and metal plate or metal having a mirror surface. It is also possible to use vapor-deposited plastic as the reflective layer.

In the recording medium of the present invention having the recording layer obtained as described above, information is written by exposure to ultraviolet light having a wavelength of 400 nm or less.

That is, 600 that corresponds to the oscillation wavelength of the reading laser in the portion that has been exposed to ultraviolet light having a wavelength of 400 nm or less.
The signal is written by the absorption at a wavelength of ~ 1200 nm being attenuated compared to the unexposed area.

The ultraviolet light source used for writing may be any light source having an emission spectrum of 400 nm or less, particularly 200 to 400 nm, for example, a mercury lamp, sodium lamp, cesium lamp, cadmium lamp, metal halide lamp, helium lamp, neon lamp. Lamp, argon lamp,
A krypton lamp, a xenon lamp, a xenon-mercury arc lamp, a dye laser, an excimer laser, etc. are used. In addition, focusing the above laser light having an ultraviolet or oscillation wavelength of 400 nm or less to a spot beam,
Although it is possible to scan the recording layer and write signals, it is possible to perform exposure as described above by exposing to ultraviolet rays having a wavelength of 400 nm or less by contact exposure, projection exposure, etc. through a photomask corresponding to the recording signal. It is particularly preferable to write a signal by attenuating the absorption of 700 to 1000 nm of a part as compared with that of an unexposed part, particularly from the viewpoint of productivity for reproducing a large number of identical information.

In order to read a signal from the optical recording medium of the present invention in which the signal is written as described above, a laser beam having an oscillation wavelength corresponding to the absorption spectrum of the dye contained in the recording layer of the optical recording medium, for example, a semiconductor A laser, a helium neon laser, a YAG laser, or the like, particularly preferably, a spot beam of a semiconductor laser is applied onto the recording layer, and a signal is read out by detecting a change in transmittance or reflectance,
The signal is modulated to reproduce the image, voice and the like.

After writing with ultraviolet light having a wavelength of 400 nm or less, metal can be vapor-deposited on the recording layer to form a reflective layer, and recording can be read from the transparent supporting substrate side using reflected light. It is also possible to apply a metal vapor deposition primer on the recording layer, perform protective coating on the metal vapor deposition layer, or use two optical recording media as a laminated double-sided plate.

[Examples] Hereinafter, embodiments of the present invention will be described more specifically with reference to Examples.

Example 1 1 g of the dye having the structure of 1 and polyvinyl butyral resin 19 g are dissolved in a mixed solution of 100 g of methanol and 20 g of dimethylacetamide, filtered through a cartridge type filter, and then coated with a 100 μ polyester film using a spin coater. Then, it was dried to form a recording layer having a thickness of 0.6 μm. 500mj through a quartz glass photomask
After exposure to ultraviolet rays (high pressure mercury lamp, wavelength 365nm)
Aluminum was deposited on the surface of the recording layer to form a reflective layer. The reflectance of the ultraviolet-exposed area using semiconductor laser light (830 nm) was 55%, and the reflectance of the unexposed area was 25%, and a sufficient reflectance difference was obtained to obtain a clear signal.

Comparative Example 1 Instead of the dye used in Example 1, bis (1,2,3,
The recording layer formation, the ultraviolet exposure and the reflection layer formation were performed in exactly the same manner as in Example 1 except that 4-tetrachloro-5,6-dithiophenolate) nickel (II) tetra-n-butylammonium was used. The reflectance of the UV-exposed area using semiconductor laser light (830 nm) is 38%, and the reflectance of the unexposed area is 28%.
%, A sufficient reflectance difference was not obtained to obtain a clear signal.

Then, in the same manner, 1500 mj, that is, 150 in the first embodiment.
A much larger UV exposure was applied to 0 mj to form a reflective layer. The reflectance of the exposed portion using the semiconductor laser beam (830 nm) was 53%, and the reflectance of the unexposed portion was 28%, and a reflectance difference sufficient to obtain a clear signal was finally obtained.

Example 2 Instead of the dye used in Example 1, The recording layer formation, the UV exposure and the reflection layer formation were performed in exactly the same manner as in Example 1 except that the dye having the structure of was used. The reflectance of the UV-exposed portion using the semiconductor laser light (830 nm) was 60%, and the reflectance of the unexposed portion was 30%, and a sufficient reflectance difference was obtained to obtain a clear signal.

Example 3 0.5 g of benzoin ethyl ether was added to the recording layer forming solution of Example 1 to form a recording layer, ultraviolet exposure and reflection layer formation in the same manner. In the same evaluation as in Example 1, the exposed portion reflectance was 65% and the unexposed portion reflectance was 25%.
A sufficient reflectance difference was obtained to obtain a clear signal.

Example 4 1 g of the dye used in Example 2, 10 g of methyl methacrylate-glycidyl methacrylate copolymer resin, 0.2 g of triphenylsulfonium hexafluoroantimonate were dissolved in a mixed solvent of 100 g of ethylene glycol monomethyl ether and 50 g of dimethylformamide. After filtering and filtering, the recording layer formation, ultraviolet exposure and reflection layer formation were carried out in the same manner as in Example 1. In the same evaluation as in Example 1, the exposed portion reflectance
The reflectance was 52% and the reflectance of the unexposed area was 23%, which was sufficient to obtain a clear signal.

[Effect of the Invention] By specifying the dye to be contained in the recording layer, it is superior to the case of using the optical recording system and the optical recording medium described in JP-A-57-195336 and 57-195341. Optical recording can be performed with recording sensitivity.

Further, since a small recording bit of 1 μm or less is not formed at the time of molding using a stamper, an expensive precision molding machine is not required, there is no restriction on the material of the molding material, and there is no clogging of the stamper. The optical recording method of the present invention is a CD-
It can be suitably used for WO, optical tape, optical card and the like.

Continuation of front page (56) Reference JP-A-57-195336 (JP, A) JP-A-58-112794 (JP, A)

Claims (1)

[Claims] 1. A general formula (I)[In Formula (I), Y is -H, -SO₃ , -SO₃H, −SO₃Na
 Or −SO₃K, l is an integer of 1 to 4, Y '
Is -H, -SO₃H, −SO₃Na or −SO₃K and n is 1
Is an integer from 4 to 4, m is 3 or 4, X Is halo
Gen ion, ClO_FourOr BF_IMonovalent anion represented by
And Y is -SO₃ X when Does not exist
Optical recording having a recording layer containing a dye having a structure
An optical recording method using a recording medium, comprising:
Irradiate ultraviolet rays with a wavelength of 0 nm or less to the irradiated area
By reducing the absorption of the reproduction laser light in
The optical recording method is characterized in that writing is performed.