JP2998845B2 - Optical information recording medium - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium such as an optical disk, and more particularly to a write-once (WO) optical disk having a recording layer made of an organic dye. The present invention relates to a suitable optical information recording medium.

[Prior Art] At present, compact discs (CDs) are widely used for music reproduction, but these are dedicated to reproduction and do not have a so-called direct read after write (DRAW) function. Cannot record or edit. Therefore, the emergence of a CD having a DRAW function is desired.
Also, for optical discs other than CDs, the realization of an inexpensive optical disc having a DRAW function is expected.

[Problem to be Solved by the Invention] As an optical recording material having the DRAW function, a perforated optical information recording medium is known. In this optical information recording medium, as shown in FIGS. 15 and 16, a recording layer 22 is formed on a transparent substrate 21, and when the recording layer 22 is irradiated with a laser, the irradiated recording layer 22 The portion is dissolved, and the thickness of the recording layer 22 is reduced only by that portion, or the substrate 21 is exposed to become a recording pit 23 (see FIG. 16). During playback, the reflectance differs only at the recording pit 23,
It can be read as a signal.

However, in this optical information recording medium, since the recording pit 23 has an open hole shape as shown in FIG. 16, dust or the like adheres and accumulates on the recording pit 23, causing an error. Furthermore, the pit ends are likely to be irregular, which causes a reduction in C / N. Further, when the lead light is repeatedly irradiated many times, the pit shape changes, thereby causing a pit error.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide an optical information recording medium excellent in environmental resistance, C / N characteristics and read light resistance.

Means for Solving the Problems To achieve the above object, the present invention provides an optical information recording medium having an optically transparent substrate and a recording layer formed in the shape of the substrate and having a higher refractive index than the substrate. It is intended for.

The recording layer contains an indole cyanine dye having the following general structural formula, and is composed of a material having a property of maintaining a thermally stable, ductile, and expanded state such as aluminum on the recording layer. An upper thin layer is provided to form a hollow recording pit of the recording layer, and a portion of the upper thin layer corresponding to the recording pit swells to the side opposite to the recording layer. Is what you do.

Further, in order to achieve the above object, the present invention is directed to an optical information recording medium having an optically transparent substrate and a recording layer formed on the substrate and having a higher refractive index than the substrate.

The recording layer contains an indole cyanine dye having the following general structural formula, and is composed of a material having a property of maintaining a thermally stable, ductile, and expanded state such as aluminum on the recording layer. An upper thin layer is provided, and a lower thin layer made of a thermally stable and low thermal conductivity material such as phthalocyanine is provided between the recording layer and the substrate. The recording pit is formed, and the portion of the upper thin layer corresponding to the recording pit swells on the side opposite to the recording layer.

Further, in order to achieve the above object, the present invention is directed to an optical information recording medium having an optically transparent substrate and a recording layer formed on the substrate and having a higher refractive index than the substrate.

And at least a lower thin layer, a recording layer and an upper thin layer are provided with the recording layer interposed therebetween, wherein the recording layer contains an indole cyanine dye having the following general structural formula, and the lower thin layer and the upper thin layer Is made of a metal material having high ductility and malleability such as aluminum or gold which is less likely to be thermally deformed than the recording layer, or a material such as phthalocyanine.

General structural formula In the formula, the carbon chain for forming the methine chain is C ₃ to
Consists linear or multi-membered ring of C _17, a hydrogen atom with a carbon atom, a halogen atom, (R ″ may be a C _{1 to} C ₆ linear or aromatic ring).

A and A 'may be the same or different, each represents an aromatic ring, and the hydrogen atom attached to the carbon atom is -I,-
_{Br, -Cl, -C n H 2n} 1 (n = 1~22), - OCH 3, (R is a linear hydrocarbon or an aromatic ring).

B and B 'may be the same or different, and -O-,-
S-, -Se-, -CH = CH-, or (R 'is, CH _3, alkyl group of _{C 2 H 5, C 3 H} 7, C 4 H 9 , etc. C ₁ -C ₄₎ represent.

R and R ', which may be identical or different, represent an alkyl group of C ₁ -C _22, which may be substituted with a sulfonic group or carboxyl group.

X represents an anion such as I, Cl, ClO ₄ , SCN, CF ₃ SO ₃ , and BF ₄ (however, except for hexafluorophosphate ion).

m and n are each an integer of 0 or 1 to 3, and have a relationship of m + n ≦ 3.

[Operation] The recording layer containing the indole-based cyanine dye paired with the counter ion as described above is easier to locally melt, evaporate, and sublimate than the recording layer made of another material. The recording pits formed on the recording layer are sharp. By forming a hollow recording pit in the recording layer, dust and the like are not dull compared to the conventional hole-shaped recording pit, so that the environment resistance is good. In addition, the C / N value is high because the shape of the end of the cavity is more uniform than that of the hole-shaped recording pit. Further, since the recording layer is sandwiched between the upper thin layer and the lower thin layer to form a San-Germanic structure, the change in the pit shape due to the read light is small, and the pit error can be reduced.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a double-sided air sanctuary optical disk according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a main part of the optical disk.

In these figures, reference numeral 1 denotes a disk-shaped substrate made of an optically transparent material, for example, a transparent resin material such as polycarbonate, polymethyl methacrylate, polymethyl pentene, epoxy, or a transparent ceramic such as glass. it can. In this embodiment, a polycarbonate substrate is used. 1a in the figure is the substrate 1
Is the central hole.

Reference numeral 2 denotes a lower thin layer formed on the substrate 1, which has a low absorptance at around 780 nm or 830 nm, which is the wavelength of a semiconductor laser used for recording and reproduction, is thermally stable, and has a smaller thickness than metal. Low thermal conductivity, such as phthalocyanine dyes, silicon dioxide, squarylium
m).

Reference numeral 3 denotes a recording layer, which is made of a poorly water-soluble organic dye-based heat mode recording material. As this recording material, an indole cyanine having the following general structural formula is particularly suitable.

In the formula, the carbon chain for forming the methine chain is C ₃ to
Consists linear or multi-membered ring of C _17, a hydrogen atom with a carbon atom, a halogen atom, (R ″ may be substituted with a C _{1 to} C ₆ linear or aromatic ring).

A and A 'may be the same or different, each represents an aromatic ring, and the hydrogen atom attached to the carbon atom is -I,-
_{Br, -Cl, -C n H 2n} + 1 (n = 1~22), - OCH 3, , −NO ₂ , (R is a linear hydrocarbon or an aromatic ring).

B and B 'may be the same or different, and -O-,-
S-, -Se-, -CH = CH-, or (R 'is, C ₁ -C ₄ alkyl groups such as _{CH 3, C 2 H 5,} C 3 H 7, C 4 H 9) represent.

R and R ', same or different connexion may represents an alkyl group of C ₁ -C _22, which may be substituted with a sulfonyl group or carboxyl group.

X represents an anion such as I, Cl, ClO ₄ , SCN, CF ₃ SO ₃ , and BF ₄ (however, except for hexafluorophosphate ion).

m and n are each an integer of 0 or 1 to 3, and have a relationship of m + n ≦ 3.

FIG. 3 is a diagram showing a typical example of T in the general structural formula,
Other than this example can also be used.

FIG. 4 is a view showing a typical example of A and A 'in the above general structural formula.

5 to 11 show specific examples of various indole cyanine dyes that can be used.

The concentration of the dye or the dye composition is preferably from 0.4 to 20% by weight. If it exceeds 20% by weight, the final thickness of the recording layer becomes too large, and the formation of cavities during recording does not proceed well. On the other hand, when the concentration is lower than 0.4% by weight, defects such as pinholes occur in the recording layer.

The lower thin layer 2 and the recording layer 3 can be uniformly formed by spin coating with good productivity.

Returning to FIG. 2, reference numeral 4 denotes an upper thin layer formed on the recording layer 3. The upper thin layer 4 is made of, for example, aluminum,
It is composed of copper, gold or an alloy containing them, is thermally stable, has good ductility, and has a recording layer 3 as shown in FIG.
Extending along the shape of the cavity 5 formed in the middle of the
It swells to the opposite side of the recording layer 3 and keeps the swelling state. The upper thin layer 4 is formed to a predetermined thickness by, for example, vapor deposition, sputtering, ion plating, or the like.

When recording signals, FIGS. 1 and 2 and FIG.
In FIG. 12, a laser beam is irradiated in a spot shape from the substrate 1 toward the recording layer 3. As the recording conditions, for example, the laser wavelength is 780 nm or 830 nm, the linear velocity is 1.25 m / sec,
The recording power is 5 mW. By irradiating the laser beam in a spot shape, the recording layer 3 is locally melted by heat. There is slight evaporation and sublimation at the same time as this melting,
The generated vapors fill the signal cavities 5 formed by the melting, lose their escape due to the presence of the upper thin layer 4,
The upper thin layer 4 softened by the heat energy of the irradiation beam is expanded toward the side opposite to the substrate 1 as shown in FIG. Then, an appropriate pressure is generated in the closed cavity 5, and this pressure acts three-dimensionally as a force for expanding the cavity 5 more. Therefore, the diffusion of the melt is promoted, and a quicker and clearer pit is formed.

As described above, the lower thin layer 2 has a low absorptivity to laser light, is thermally stable, and has a lower thermal conductivity than metal, so that the heat accumulated in the recording layer 3 is Heat is prevented from being dissipated to one side, and is involved in the formation of the cavity 5.

On the other hand, since the upper thin layer 4 is thermally stable and rich in ductility, the film extends in conformity with the shape of the cavity 5 when the recording pit is formed, and even after the cavity 5 is cooled. It can maintain the swollen shape.

As described above, if the upper and lower surfaces of the thermally unstable recording layer 3 are sandwiched between the thermally stable lower thin layer 2 and upper thin layer 4 in a San-Germanic manner, the recording pitch can be improved. Can have a very sharp and uniform shape.

FIG. 13 and FIG. 14 are views for explaining another embodiment of the present invention.

In this embodiment, the recording layer 3 is made of a cyanine-based organic dye similarly to the above-mentioned embodiment, and the lower thin layer 2 and the upper thin layer 4 are made of a metal material having high ductility and malleability, such as aluminum or gold, or phthalocyanine. It is composed of such materials.

When the lower thin layer 2 and the upper thin layer 4 are both made of a metal material, those layers are formed by a sputtering method or a vapor deposition method. When both the lower thin layer 2 and the upper thin layer 4 are made of an organic material such as phthalocyanine, those layers are formed by spin coating.

Also in this embodiment, when the optical information recording medium is irradiated with laser light, the thermally unstable recording layer 3 undergoes thermal deformation to form hollow pits 5 as shown in FIG. Then, along with the deformation of the recording layer 3, the upper thin layer 4 is also deformed.

In the above-described embodiment, the case of the double-sided air-sandwich type structure has been described. However, the present invention is not limited to this, and can be applied to other types of optical information recording media.

[Effect of the Invention] The recording layer containing the indole-based cyanine dye paired with the counter ion represented by the general structural formula has a local thermal melting, evaporation,
Because the sublimation is easy, the recording pits formed on the recording layer are sharp, and the upper thin layer made of a material that is thermally stable, highly ductile, and maintains a swollen state on the recording layer And a hollow recording pit is formed in the recording layer, and a portion of the upper thin layer corresponding to the recording pit swells to the side opposite to the recording layer.

Since the recording pit has a hollow shape as described above, unlike the conventional hole-shaped recording pit, no dust adheres or accumulates in the recording pit, and the recording pit is excellent in environmental resistance. In addition, the C / N characteristics are high because the shapes of the pit ends are uniform. Further, even if the read light is repeatedly irradiated many times, the pit shape does not change and the pit shape is stable, so that no pit error occurs.

Further, the recording layer containing the indole cyanine dye paired with the counter ion represented by the general structural formula, the local thermal melting compared to the recording layer made of other materials,
Since the recording pit formed on the recording layer is sharp because of easy evaporation and sublimation, the recording pit is made of a material having a property of maintaining a thermally stable, ductile, and expanded state on the recording layer. A thin layer is provided, and a lower thin layer made of a material that is thermally stable and has low thermal conductivity is provided between the recording layer and the substrate, and a hollow recording pit is formed in the recording layer. By expanding the portion of the upper thin layer corresponding to the recording pit to the side opposite to the recording layer, the environmental resistance and C / N characteristics can be further improved, and the occurrence of a pit error can be more reliably prevented. Further, an optical information recording medium with high reliability can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a double-sided air sanctuary optical disk according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a main part of the optical disk, and FIG. FIG. 4 shows a typical example of A and A ′ in the general structural formula, and FIGS. 5 to 11 show specific examples of various indole cyanine dyes. FIG. 12 is a schematic diagram of a recording pit. FIG. 13 is an enlarged sectional view of a main part of an optical disk according to another embodiment of the present invention, and FIG. 14 is a schematic diagram of a recording pit on the optical disk. FIG. 15 is an enlarged sectional view of a main part of a conventional optical disk, and FIG. 16 is a schematic diagram of a recording pit on the optical disk. 1 ... substrate, 2 ... lower thin layer, 3 ... recording layer, 4 ... upper thin layer, 5 ... cavity.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hisamitsu Kamezaki 1-1-88 Ushitora, Ibaraki City, Osaka Prefecture Inside Hitachi Maxell, Ltd. (72) Inventor Masashi Susumu 1-1-88 Ushitora, Ibaraki City, Osaka Hitachi Maxell (56) References JP-A-60-15843 (JP, A) JP-A-63-259854 (JP, A) JP-A-57-55540 (JP, A) JP-A-56-65340 (JP, A) A) JP-A-2-122439 (JP, A) JP-A-59-5048 (JP, U)

Claims (9)

(57) [Claims] 1. An optical information recording medium having an optically transparent substrate and a recording layer formed on the substrate and having a higher refractive index than the substrate, wherein the recording layer has the following general structural formula: An upper thin layer made of a material containing a cyanine dye and having a property of maintaining a thermally expanded, ductile, and expanded state is provided on the recording layer, and a hollow recording pit is formed on the recording layer. The optical information recording medium according to claim 1, wherein a portion of the upper thin layer corresponding to the recording pit swells to the side opposite to the recording layer. In the formula, C ₃ to C ₃ are carbon chains for constituting a methine chain.
_It consists of ₁₇ linear or multi-membered rings, and the hydrogen atom attached to the carbon atom is a halogen atom, (R ″ may be substituted with a C _{1 to} C ₆ linear or aromatic ring.) A and A ′ may be the same or different, each represents an aromatic ring, and a hydrogen atom attached to a carbon atom is −I, −B
_{r, -Cl, -C n H 2n} + 1 (n = 1~22), - OCH 3, (R is a linear hydrocarbon or an aromatic ring). B and B 'may be the same or different, and -O-, -S
-, -Se-, -CH = CH-, or (R 'is, CH _3, alkyl group of _{C 2 H 5, C 3 H} 7, C 4 H 9 , etc. C ₁ -C ₄₎ represent. R and R ', which may be identical or different, represent an alkyl group of C ₁ -C _22, which may be substituted with a sulfonic group or carboxyl group. X represents an anion such as I, Cl, ClO ₄ , SCN, CF ₃ SO ₃ , and BF ₄ (however, except for hexafluorophosphate ion). m and n are each 0 or an integer of 1 to 3,
m + n ≦ 3. 2. An optical information recording medium having an optically transparent substrate and a recording layer formed on the substrate and having a higher refractive index than the substrate, wherein the recording layer has the following general structural formula: An upper thin layer of a material containing a cyanine dye and having a property of maintaining a thermally expanded, ductile, and expanded state is provided on the recording layer, and a thermal layer is provided between the recording layer and the substrate. A lower thin layer made of a material that is stable and has low thermal conductivity is provided, a recording pit on a cavity is formed in the recording layer, and a portion of the upper thin layer corresponding to the recording pit is formed. An optical information recording medium characterized by swelling on the side opposite to the recording layer. In the formula, C ₃ to C ₃ are carbon chains for constituting a methine chain.
_It consists of ₁₇ linear or multi-membered rings, and the hydrogen atom attached to the carbon atom is a halogen atom, (R ″ may be substituted with a C _{1 to} C ₆ linear or aromatic ring.) A and A ′ may be the same or different, each represents an aromatic ring, and a hydrogen atom attached to a carbon atom is −I, −B
_{r, -Cl, -C n H 2H} + 1 (n = 1~22), - OCH 3, (R is a linear hydrocarbon or an aromatic ring). B and B 'may be the same or different, and -O-, -S
-, -Se-, -CH = CH-, or (R 'is, CH _3, alkyl group of _{C 2 H 5, C 3 H} 7, C 4 H 9 , etc. C ₁ -C ₄₎ represent. R and R ', which may be identical or different, represent an alkyl group of C ₁ -C _22, which may be substituted with a sulfonic group or carboxyl group. X represents an anion such as I, Cl, PF ₆ , ClO ₄ , SCN, CF ₃ SO ₃ , and BF ₄ . m and n are each 0 or an integer of 1 to 3,
m + n ≦ 3. 3. An optical information recording medium according to claim 1, wherein said upper thin layer is made of a metal material. 4. The optical information recording medium according to claim 3, wherein said metal material is aluminum. 5. The optical information recording medium according to claim 2, wherein said lower thin layer is made of phthalocyanine. 6. An optical information recording medium comprising an optically transparent substrate and a recording layer formed on the substrate and having a higher refractive index than the substrate, wherein at least a lower thin layer and a recording layer sandwich the recording layer. And an upper thin layer, wherein the recording layer contains an indole cyanine dye having the following general structural formula, and is a layer that is more easily thermally deformed than the lower thin layer and the upper thin layer. Optical information recording medium. In the formula, C ₃ to C ₃ are carbon chains for constituting a methine chain.
_It consists of ₁₇ linear or multi-membered rings, and the hydrogen atom attached to the carbon atom is a halogen atom, (R ″ may be substituted with a C _{1 to} C ₆ linear or aromatic ring.) A and A ′ may be the same or different, each represents an aromatic ring, and a hydrogen atom attached to a carbon atom is −I, −B
_{r, -Cl, -C n H 2n} 1 (n = 1~22), - OCH 3, (R is a linear hydrocarbon or an aromatic ring). B and B 'may be the same or different, and -O-, -S
-, -Se-, -CH = CH-, or (R 'is, CH _3, alkyl group of _{C 2 H 5, C 3 H} 7, C 4 H 9 , etc. C ₁ -C ₄₎ represent. R and R ', which may be identical or different, represent an alkyl group of C ₁ -C _22, which may be substituted with a sulfonic group or carboxyl group. X represents an anion such as I, Cl, PF ₆ , ClO ₄ , SCN, CF ₃ SO ₃ , and BF ₄ . m and n are each 0 or an integer of 1 to 3,
m + n ≦ 3. 7. The optical information recording medium according to claim 6, wherein both the upper thin layer and the lower thin layer are made of a metal material having high ductility and malleability. 8. The optical information recording medium according to claim 7, wherein said metal material is made of aluminum or gold. 9. The optical information recording medium according to claim 6, wherein both the upper thin layer and the lower thin layer are made of phthalocyanine.