JP2003170664A - Information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic dye recording layer and a light reflection layer on a light-transmitting substrate as a first disk and a light reflection layer and an organic dye recording on a light-transmitting substrate as a second disk. Layer, the dye protective layer is laminated, the light reflective layer of the first disk and the dye protective layer of the second disk, in a recording medium bonded by an adhesive layer, from the light transmissive substrate side of the first disk, Provided is an optical recording medium capable of performing good recording on first and second disks. SOLUTION: The light transmitting substrate 1 as shown in FIG.
On the optical recording medium composed of the organic dye recording layer 2, the light reflection layer 3, the adhesive layer 4, the dye protection layer 5, the organic dye recording layer 22, the light reflection layer 32, and the light transmitting substrate 12, the following: Use techniques. When the dye used for the organic dye recording layer 2 is applied to the light transmitting substrate, the absorption maximum λ1 (nm) closest to the recording laser wavelength of the dye film is applied, and the dye used for the organic dye recording layer 22 is applied to the light transmitting substrate. When the absorption maximum λ2 (nm), which is the closest to the recording laser wavelength of the dye film at this time, is satisfied, 30 ≧ λ2−λ1> 0 (nm).

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium having a recording layer and a reflection layer on a transparent light transmitting substrate. [0002] An organic dye recording layer that absorbs laser light directly or with another layer interposed on a transparent light-transmitting substrate;
A write-once optical disc, which is an optical recording medium having a metal reflective layer directly on the recording layer or with another layer interposed therebetween, is widely known. DVD is one of the write-once optical disks.
-R. DVD-R is 4.7mm on one side with a thickness of 0.6mm
Disk with GB recording capacity, same thickness 0.6m
A single-sided recordable DVD-R with a capacity of 4.7 GB in the form of two dummy disks that cannot be written with a capacity of 4.7 m
There are two types of DVD-R, a double-sided recording type DVD-R having a capacity of 9.4 GB, in which two disks having a recording capacity of 4.7 GB on one side are bonded together, and recording and reproduction are performed using laser from both sides. [0003] The double-sided recording type DVD-R, which performs recording and reproduction using a laser from both sides, has a large capacity of 9.4 GB. However, in a recording / reproducing apparatus, a recording / reproducing laser is installed above and below the disk surface. I have to do it. For this reason, the recording / reproducing apparatus becomes expensive, and a single-sided recording type DVD-R is generally used.
R is often used. This DVD-
R has an authoring standard and a general standard, but there is no difference between them in terms of capacity. If an optical recording medium in which two disks are bonded together and recording is performed by irradiating a laser beam from one side can be produced, it can be advantageous in terms of both capacity and drive structure. However, there may be a problem in manufacturing such an optical recording medium. In an optical recording medium having an organic dye recording layer, pits are formed at a temperature at which the applied dye can be decomposed by a laser irradiated at the time of recording, and recording is performed. The dye used in the organic dye recording layer has an absorption maximum when formed into a dye film on the shorter wavelength side than the recording / reproducing wavelength. As a result, the refractive index at the reproduction wavelength can be increased, and the degree of modulation during reproduction can be increased. That is, by adjusting the maximum absorption value when the dye film is formed, the maximum peak of the refractive index can be set to the wavelength value of the reproduction laser. [0005] In an optical recording medium having an organic dye recording layer, pits are formed at the temperature at which the dye absorbs the laser wavelength at the recording laser wavelength and can be decomposed, and recording is performed. When the maximum absorption wavelength is shorter than the recording wavelength and two dyes whose wavelengths are not so different are compared, the reflectance at the time of recording and the refractive index which affects the modulation at the time of reproduction are good. At the maximum absorption wavelength when recording and reproducing
The absorbances of both dyes are almost the same. In general, the dye used in the organic dye recording layer gradually loses its absorption when the wavelength becomes longer than the maximum absorption wavelength. That is, if the maximum absorption wavelength position existing at a wavelength shorter than the recording laser wavelength approaches the recording laser wavelength position, the absorption at the recording laser wavelength position tends to increase. In a dye having the same absorbance at the maximum absorption wavelength, the absorption at the recording / reproducing wavelength decreases as the maximum absorption wavelength is shorter than the recording wavelength. That is,
By adjusting the absorption maximum, the absorption of the recording laser by the dye at the recording laser wavelength position can be adjusted. Here, in a disk where two disks are bonded and recording is performed by irradiating a laser from one side, the same dye is used on the recording surface of the disk near the laser incident surface and on the recording surface of the distant disk. When recording is performed on both discs, in such a disc, a farther disc has more layers through which the laser passes than a disc closer to the laser incidence surface.
Light amount loss increases. The laser penetrates more layers in order for the dye in the organic dye recording layer of the disk to reach the same temperature as the temperature at which the dye in the organic dye recording layer of the disk near the laser incident surface is decomposed reaches the same temperature. It is necessary to apply a large power in consideration of the loss of light quantity to bring the dye in the organic dye recording layer of the distant disk to the decomposition temperature. In an optical recording medium having an organic dye recording layer, pits are formed at a temperature at which the dye absorbs the laser wavelength at the recording laser wavelength and can be decomposed, and recording is performed. Therefore, by using a dye with smaller absorption at the recording laser wavelength for the organic dye recording layer of the disk near the laser incident surface, it is possible to reach more laser power to the dye of the organic dye recording layer of the distant disk. it can. In other words, in order to perform recording with the same power on both disks by laminating two disks and recording with laser incident from one side, the absorbance at the recording laser wavelength must be The dye used on the recording surface of a distant disk may be smaller than the dye used on a disk near the laser incident surface. That is,
The absorption maximum of the dye used in the organic dye recording layer of a farther disk may be higher than that of a disk closer to the laser incidence surface. As a standard of the absorption maximum difference, 5 nm is desirable. If the absorption maximum difference is smaller than this, the difference in recording power becomes large, making it difficult to perform good recording.
However, if a material having a low thermal conductivity and a material having a high transmittance at the recording wavelength, which can surely suppress the heat loss, is used, it is possible to reduce the absorption maximum difference. If the absorbance of the dye used on the recording surface of a distant disk is too high than the dye used on the disk near the laser incident surface, the absorption of the recording laser on the recording surface of the disk distant from the laser incident surface is too high. And pits are easily formed with low power. Therefore, there is a difference in power between the recording surface of the disk near the laser incident surface and the recording surface of the distant disk. It is desirable to make the maximum absorption difference of the dye used on the recording surface of a distant disk smaller than 30 nm than the dye used. SUMMARY OF THE INVENTION An object of the present invention is to record data on an optical recording medium having a structure in which two single-sided recording disks are bonded by using a laser only from one side of the disk. It is an object of the present invention to provide an optical recording medium which performs the recording on both disks satisfactorily and performs recording with the same laser power when recording on both disks. Thus, it is not necessary to perform the optimum recording laser power for both disks, and the optimum recording laser power can be determined at once. Means for Solving the Problems As shown in FIG.
An organic dye recording layer 2, a light reflection layer 3,
The following method is used for an optical recording medium composed of the adhesive layer 4, the dye protective layer 5, the organic dye recording layer 22, the light reflection layer 32, and the light transmitting substrate 12. When the dye used for the organic dye recording layer 2 is applied to the light transmitting substrate, the absorption maximum λ1 (nm) closest to the recording laser wavelength of the dye film is applied, and the dye used for the organic dye recording layer 22 is applied to the light transmitting substrate. Absorption maximum λ2 (n
When m), 30 ≧ λ2−λ1> 0 (nm) is satisfied. By the above method, an optical recording medium excellent in good recording can be provided. Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments. First,
The method of creating the first disc is described below. As the light transmissive substrate 1, a transparent material, a resin represented by a polycarbonate resin, an acrylic resin, an epoxy resin, an ABS resin or the like, glass, or the like is used. A transparent resin material such as a polycarbonate resin or a polymethyl methacrylate resin can be used as the easily handled resin. The light transmissive substrate can be manufactured by injection molding of these transparent resin materials, but is not limited to this manufacturing method, and can be manufactured by 2P (Photo-Po
lymer) method. On at least one surface of the light-transmitting substrate, tracking pre-grooves may be formed concentrically or spirally at intervals of 0.3 μm to 1.6 μm. Is 100 nm to 250 nm in order to obtain a reproduced signal amplified by utilizing the light interference effect.
It is desirable that On the surface of the light transmissive substrate, a predetermined pattern such as a pre-pit on which information is recorded or a groove or the like for tracking or addressing is provided as necessary. The organic dye recording layer 2 is provided directly on the above-mentioned light-transmitting substrate 1 or via another inorganic or organic layer. The recording layer can be formed by a spin coating method, an evaporation method, or the like, and a spin coating method using a solvent is particularly preferable. As a solvent used at the time of film formation, for example, ethyl cellosolve, methyl cellosolve, methanol, tetrafluoropropanol, or the like can be used. The thickness of the recording layer to be formed is 20 nm to 200 nm.
Is preferred. As the dye of the dye thin film forming the organic dye recording layer, a dye having a property of causing chemical changes such as decomposition, sublimation, melting, and vaporization by irradiation of a recording laser is used. Organic dyes that meet this condition include cyanine dyes, squarylium dyes, croconium dyes,
Azulenium dyes, triarylamine dyes, anthraquinone dyes, metal-containing azo dyes, dithiol metal complex dyes, indoaniline metal complex dyes, phthalocyanine dyes, naphthalocyanine dyes, intermolecular CT complex dyes, etc. is there. These dyes may be used alone or in combination in the organic dye recording layer of the invention. Further, in the organic dye recording layer, in addition to the recording dye, an antioxidant, a quencher such as a dithiol complex, nitrocellulose, cellulose acetate, a ketone resin, an acrylic resin,
A binder such as polyvinyl butyral, polycarbonate, and polyolefin may be added. The light reflecting layer 3 includes, but is not limited to, Ag, Al, Au, Cu, Cr, Ni, Pt, Pd, etc. on the above-mentioned organic dye recording layer. The light reflection layer 3 can be formed by vacuum deposition, sputtering, ion plating, or the like. The thickness of the reflective layer to be formed is
0.01 μm to 0.2 μm is preferred. Next, a method of creating the second disk will be described below. A light reflecting layer 32 is formed on the light transmitting substrate 12 similar to the light transmitting substrate 1, similarly to the light reflecting layer 3. The thickness of the reflective layer to be formed is preferably from 0.1 μm to 0.2 μm. The organic dye recording layer 22 is applied on the light reflection layer 32 in the same manner as the organic dye recording layer 2. Next, the organic dye recording layer 22
The dye protective layer 5 is formed thereon. The dye protective layer includes an inorganic compound and an organic compound, but is not particularly limited. Examples of inorganic compounds include rare earths containing Yu, Au, Ag, Al,
As, Ba, Be, Bi, Ca, Co, Cu, Fe, Ga, Ge, Hf, In, M
g, Ni, Pb, Pd, Rh, Sc, Si, Sn, Ta, Ti, V, W, Zn, Z
Metals such as r and their oxides, sulfides, nitrides, halides, fluorides, carbonates, sulfates, nitrates, nitrites and the like. Examples of the organic compound include resins such as vinyl acetate resin and vinyl chloride resin, resins such as polydimethylsiloxane, and organic substances such as sucrose, tartaric acid, and paraffin. When used as a separate layer, these may be used alone, or mixed and laminated. The thickness of the dye protective layer 5 to be formed is
0.005 μm to 0.04 μm is preferred. Finally, the light reflecting layer 3 of the first disk and the dye protective layer of the second disk are bonded. As the adhesive layer 4, an organic material such as an ultraviolet-curable acrylic resin, an ultraviolet-curable resin such as an ultraviolet-curable epoxy resin, an ultraviolet-curable adhesive, an epoxy adhesive, a silicone resin, a silicone adhesive, and a hot melt adhesive is used. can do. The thickness of the protective layer is preferably from 0.1 μm to 100 μm. The adhesive layer 4 can be formed by a usual method such as spin coating, gravure coating, spray coating, roll coating and the like. Here, the absorption maximum λ closest to the recording laser wavelength of the dye film when the dye used for the organic dye recording layer 2 is applied to the light-transmitting substrate in the first and second disks.
When the absorption maximum is λ2 (nm), which is the closest to the recording laser wavelength of the dye film when the dye used for the organic dye recording layer 22 is applied to the light-transmitting substrate, 30 ≧ λ2
−λ1> 0 (nm) is satisfied. According to the above-described method, for a disc having a structure in which the first and second single-sided recording discs are bonded to each other, a light beam for performing recording / reproduction satisfactorily on both discs using a laser only from one side of the disc. It is possible to provide a recording medium. Further, the maximum absorption value of the dye used in the present invention was obtained by applying the dye on a polycarbonate light-transmitting substrate having a thickness of 0.6 mm and then measuring the ultraviolet absorption spectrum. EXAMPLES In order to specifically show the effects of the present invention,
This will be specifically described with reference to the drawings. The present invention will be specifically described with reference to examples, but embodiments of the present invention are not limited thereto. (Embodiment 1) FIG. 1 shows an example of the structure of an optical recording medium according to the present invention. First, a method for manufacturing the first disk will be described below. Using an injection molding machine equipped with a stamper on which a preformat pattern is formed, a polycarbonate resin is injection-molded to have a diameter of 120 mm.
The light transmissive substrate 1 having a thickness of 0.6 mm and a plate thickness of 0.6 mm was produced.
On the obtained light transmissive substrate 1, a pre-groove for tracking was formed concentrically with a track pitch of 0.8 μm and a groove width of 0.3 μm. On the light transmitting substrate 1 on which the pre-groove was formed, an organic dye recording layer was formed as follows.
A solution having a concentration of 1% by weight of the azo dye represented by the structural formula (Chemical Formula 1) was prepared and applied to a thickness of 200 nm by spin coating to form an organic dye recording layer 2. Embedded image When applying the dye, tetrafluoropropanol was used as a solvent to form an azo dye solvent, and the mixture was filtered through a filter to remove insolubles. When this organic dye was applied to a light-transmitting substrate, the absorption maximum of the dye film was 580 nm. The light transmitting substrate 1 coated with the organic dye was dried at 70 ° C. for 1 hour after the dye was coated. Au was formed as a light reflection layer 3 on the organic dye recording layer 2 by sputtering to a thickness of 0.020 μm. Next, a method for creating the second disk will be described below. The light-transmitting substrate 12 on which the pregroove was formed was manufactured in the same manner as the light-transmitting substrate 1. A light reflecting layer 32 is formed on the light transmitting substrate 12 on which the pregroove is formed.
u was formed into a film having a thickness of 0.1 μm by sputtering similarly to the light reflection layer 3. The organic dye recording layer 22 was applied on the light reflection layer 32 in the same manner as the organic dye recording layer 2. However, when an azo dye represented by the structural formula (Formula 2) was used as the organic dye recording layer, and the organic dye was applied to a light transmitting substrate, the absorption maximum of the dye film was 588 nm. Embedded image On the organic dye recording layer 22, as a dye protective layer 5, Au was sputtered to a thickness of 0.015 μm.
A film was formed with a thickness of μm. Finally, after forming the adhesive layer 4 on the light reflection layer of the first disk, the adhesive layer 4 is bonded to the dye protective layer 5 of the second disk, and irradiated with ultraviolet light of a predetermined light intensity using an ultraviolet irradiation machine. The adhesive layer 4 was cured. (Example 2) to (Example 3) (Example 2) and (Example 3) use (Chem. 2) and (Chem. 3) for the organic dye recording layer 2 and the organic dye recording layer 22. Other than
A sample was prepared in the same manner as in (Example 1). Here, the absorption maximum of the dye film when the azo dye represented by the structural formula (3) was applied to the light-transmitting substrate was 593 nm. (Comparative Example) (Comparative Example 1) to (Comparative Example 3)
A sample was prepared in the same manner as in Example 1 except that the same organic dye was used for the organic dye recording layer 2 and the organic dye recording layer 22. (Comparative Example 4) A sample was prepared in the same manner as in (Example 1) except that (chemical formula 1) was used for the organic dye recording layer 2 and (chemical formula 4) was used for the organic dye recording layer 22. Produced. Here, the absorption maximum of (Chemical Formula 4) was 612 nm. Embedded image Embedded image Data recording / reproducing was performed on the optical disks of the respective samples of (Example 1) to (Example 3) and (Comparative Example 1) to (Comparative Example 4) using an optical disk evaluation device DDU1000 manufactured by Pulstec Industrial. Was. 40m radius of optical recording medium
At m, a laser beam having a wavelength of 650 nm was irradiated as a recording laser beam with a power having an optimum jitter value to record image data information. Then, the wavelength of 650 nm
Was irradiated with a power of 0.5 mW to reproduce the recorded image data information and measure the jitter value. Table 1 shows the results. [Table 1] In the samples of the present invention in Examples 1 to 3, the difference between the recording powers when the jitter value becomes minimum is small in the first and second disks, and good recording and reproduction are possible. Was completed. On the other hand, (Comparative Example 1) to
When the same organic dye was used for the organic dye recording layer as in (Comparative Example 3),
The recording power when the jitter became minimum was smaller for the first disk than for the second disk, and there was a large difference in the recording power. As in (Comparative Example 4), when the maximum absorption wavelength of the dye used in the organic dye recording layer of the first and second disks is extremely high, the jitter of the first and second disks is minimized. The recording power of the first disk became too large compared to the second disk, resulting in a large difference in recording power. From the above results, the present invention, when good recording is performed on the first and second disks from the light-transmitting substrate side of the first disk, with the same laser power when recording on both disks It has been clarified that it is possible to provide an optical recording medium for recording. According to the first aspect of the present invention,
An organic dye recording layer and a light reflection layer are stacked on a light-transmitting substrate as a first disk, and a light reflection layer, an organic dye recording layer and a dye protection layer are stacked on a light-transmitting substrate as a second disk. In a recording medium in which the light reflective layer of the first disk and the dye protective layer of the second disk are bonded with an adhesive layer, recording is performed on both disks by using a laser from the light transmitting substrate side of the first disk. In addition, there is an effect that recording is performed satisfactorily, and recording is performed with the same laser power when recording on both disks.

[Brief description of the drawings] FIG. 1 is a sectional view of an information recording medium according to the present invention. [Explanation of symbols] 1 Light transmissive substrate (1st disc) 2 Organic dye recording layer (1st disc) 3 Light reflective layer disc 1) 4 Adhesive layer 5 Dye protective layer (2nd disc) 12 Light transmissive substrate (2nd disc) 22 Organic dye recording layer (2nd disc) 32 Light reflective layer (2nd disc)

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Claims (1)

Claims: 1. An organic dye recording layer and a light reflection layer are stacked on a light-transmitting substrate as a first disk, and a light reflection layer and an organic layer are formed on a light-transmitting substrate as a second disk. A dye recording layer and a dye protection layer are laminated, and the light reflection layer of the first disk and the dye protection layer of the second disk are bonded to each other with an adhesive layer. When the dye used in the organic dye recording layer of the second disk is applied to the light-transmitting substrate, the absorption maximum is λ1 (nm), which is the closest to the recording laser wavelength of the dye film when the dye to be used is applied to the light-transmitting substrate. An optical recording medium that satisfies the following expression when the absorption maximum λ2 (nm) of the dye film closest to the recording laser wavelength is satisfied. 30 ≧ λ2-λ1> 0 (nm)