JPH03219438A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To prevent the change in bit shape by constituting a recording layer of a material which is easily thermally deformable, providing an upper thin layer having excellent thermal ductility thereon and forming cavity-like recording pits on the recording layer to inflate the upper thin-film layer. CONSTITUTION:A lower thin layer 2 and the recording layer 3 consisting of the heat mode recording material of an org. dye system which is hardly soluble in water are provided on a transparent substrate 1 and the upper thin layer 4 is provided thereon. The layer 4 is thermally stable, has the high ductility, elongates along the shapes of the cavity parts 5 formed in the intermediate part of the layer 3, inflates to the opposite side of the layer 3 and maintains the inflated state. The layer 3 is locally thermally melted when the layer is irradiated with a laser beam. There are simultaneously slight evaporation and sublimation and the formed vapor fills the cavity parts 5 for signals formed by the melting and is deprived of the places to escape by the presence of the layer 4 to inflate this layer to the counter substrate 1 side. A proper pressure is then generated in the cavity parts 5 and this pressure acts three-dimensionally so as to escape from the cavity parts 5. The diffusion of the melt is, therefore, accelerated and the rapid and distinct bits are formed.

Description

Detailed Description of the Invention [Industrial Application Fields] - The irradiated portion of the recording layer 22 melts, and the thickness of the recording layer 22 decreases in that portion, or the substrate 21 is exposed and recording is not performed. This becomes a pit 23 (see Figure 17). During reproduction, since the reflectance differs only in the recording pit 23 portion, it can be read out as a signal.

However, in this optical information recording medium, since the recording pits 23 are in the form of open holes as shown in FIG. 17, dust and the like adhere to and accumulate in the recording pits 23, causing errors. Furthermore, the pit edges tend to be irregular, which causes a decrease in C/N. Furthermore, when the read light is repeatedly irradiated many times, the pit shape changes,
This causes pit errors.

The purpose of the present invention is to eliminate such drawbacks of the prior art,
The object of the present invention is to provide an optical information recording medium that has excellent environmental resistance, C/N characteristics, and read light resistance characteristics.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides optically one! - The present invention relates to an optical information recording medium such as an optical disk, and more particularly to an optical information recording medium that includes a recording layer made of an organic dye and is suitable for a write-once (WO) type optical disk.

[Prior Art] Currently, compact discs (CDs) are widely used for music playback, but they are playback-only and do not have a so-called direct read after write (DRAW) function, so users can use them freely. Cannot record or edit. Therefore, the emergence of a CD having a DRAW function is desired. Furthermore, it is expected that inexpensive optical discs with a DRAW function will be realized for optical discs for uses other than CDs.

[Problems to be Solved by the Invention] A punch-type optical information recording medium is known as an optical recording material having the second DRAW function. This optical information recording medium is mounted on a transparent substrate 21, as shown in FIGS. 16 and 17. When the recording layer 22 is formed and a laser is irradiated toward the recording layer 22, -4? - The target is an optical information recording medium having a transparent substrate and a recording layer formed on the substrate and having a higher refractive index than the substrate.

The recording layer is made of a thermally deformable material such as a cyanine-based organic dye, and the recording layer is made of a material such as aluminum that is thermally stable, highly ductile, and has a property of maintaining a swollen state. A lower thin layer made of a material is provided, and a hollow recording pit is formed in the recording layer, and a portion of the lower thin layer corresponding to the recording pit bulges on the side opposite to the recording layer. It is characterized by this.

Furthermore, 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 is made of a thermally deformable material such as a cyanine-based organic dye, and a material such as aluminum that is thermally stable, ductile, and maintains a swollen state is placed on top of the recording layer. A lower thin layer made of a material is provided, and a lower thin layer made of a thermally stable material with low thermal conductivity such as phthalocyanine is provided between the recording layer and the substrate, The recording layer is characterized in that a hollow recording pit is formed in the recording layer, and a portion of the lower thin layer corresponding to the recording pit bulges on the side opposite to the recording layer.

Furthermore, 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.

At least a lower thin layer, a recording layer, and a lower thin layer are provided sandwiching the recording layer, and the @ layer is made of a material such as a cyanine-based organic dye that is more easily deformed by heat than the lower thin layer and the lower thin layer. The lower thin layer and the lower thin layer are made of a metal material with high ductility and malleability, such as aluminum or gold, or a material such as phthalocyanine, which is less susceptible to thermal deformation than the recording layer. It is.

− Transparent ceramics such as lath can be used.

A polycarbonate substrate is used in this embodiment. Note that 18 in the figure is the center hole of the substrate 1.

2 is a lower thin layer formed on the substrate 1, which has a wavelength of 780 nm or 83 nm, which is the wavelength of the semiconductor laser used for recording and reproducing.
They have low absorption at around 0 nm, are thermally stable, and have lower thermal conductivity than metals, such as phthalocyanine dyes, silicon dioxide, and squalylium (s).
quaryl iul'I).

Reference numeral 3 denotes a recording layer, which is composed of a water-repellent and soluble organic dye-based heat mode recording material. As this recording material, for example, polymethine dyes, anthraquinone dyes, cyanine dyes, xanthine dyes, triphenylmethane dyes, pyrylium dyes, azulene dyes, metal-containing azo dyes, etc. can be used. In this example, cyanine dyes are used. Among the cyanine dyes, the following general dyes are used. By forming hollow recording pits, compared to conventional hole-shaped recording pits, dust and the like do not get stuck, so environmental resistance is better. Furthermore, since the shape of the end of the cavity is more uniform than that of a hole-shaped recording pit, the C/N value is high. Furthermore, since the recording layer is sandwiched between the lower thin layer and the lower thin layer to form a sandwich structure, the pit shape is less likely to change due to read light, and pit errors can be reduced.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

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

In these figures, l is a disk-shaped substrate made of an optically transparent material, such as a transparent resin material such as polycarbonate, polymethyl methacrylate, polymethyl pentene, epoxy, or glass! - Indole cyanines having the structural formula are preferred.

■ in the formula is a carbon chain for constituting a methine chain, and C2~
It consists of a C07 straight chain or multi-membered ring, and the hydrogen atoms attached to the carbon atoms may be substituted with halogen atoms or aromatic rings.

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 r CQ + CnHgn+z (
n0 ring).

B and B' may be the same or different, -〇-, -9
-, -3e -, CH=CH+ or C, H7, C4H
(C-4 alkyl groups such as 9).

R and R' may be the same or different, and 01 to C2□
The alkyl group may be substituted with a sulfonyl group or a carboxyl group.

X is I, CQ, PFG, Cf1O4, SCN.

It rains anions such as CF, So, BF4.

m and n are each O or an integer from ] to 3,
They have a relationship of m+n≦3.

FIG. 3 is a diagram showing typical examples of T in the above-mentioned -shell structural formula, and it is also possible to use values other than this example.

FIG. 4 is a diagram showing representative examples of A and A' in the above-mentioned -shell structural formula, and it is also possible to use values other than these examples.

5 to 12 show various usable insulators, and in FIG. 13, laser light is irradiated in a spot from the substrate 1 side toward the recording pI3. As this recording condition, for example, the laser wavelength is 780nm or 830nm.
m, the linear velocity was 1.25 m/sec, and the recording power was 5 mW. By irradiating the laser beam in a spot shape in this manner, the recording layer 3 is locally thermally melted. At the same time as this melting, there is a slight evaporation and sublimation, and the generated vapor fills the signal cavity 5 formed by the melting, has no place to escape due to the presence of the lower thin layer 4, and is affected by the thermal energy of the irradiation beam. The softened upper plating layer 4 is expanded toward the side opposite to the substrate 1 as shown in FIG. Appropriate pressure is generated within the closed cavity 5, and this pressure acts three-dimensionally as a force to further expand the cavity 5. Therefore, the diffusion of the melt is promoted and the pits are formed more quickly and clearly.

As mentioned above, the lower thin layer 2 has a low absorption rate for laser light, is thermally stable, and also has a lower thermal conductivity than metal, so the /3-dol accumulated in the recording layer 3 Specific examples of cyanine dyes are shown below.

The concentration of the dye or dye composition is preferably 0.4 to 20% by weight. If it exceeds 20% by weight, the final film thickness of the recording layer will become too thick, and cavity formation during recording will not proceed properly. On the other hand, if the concentration is lower than 0.4% by weight, defects such as pinholes will occur in the recording layer.

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

Returning to FIG. 2 again, 4 is a lower thin layer formed on the recording layer 3. This lower thin layer 4 is made of, for example, aluminum, copper, gold, or an alloy containing these, and is thermally It is stable and highly ductile, and as shown in FIG.
Extending along the shape of the cavity 5 formed in the middle part of
It swells to the opposite side of the recording layer 3 and maintains its swollen state.

This lower thin layer 4 is formed to a predetermined thickness by, for example, vapor deposition, sputtering, ion blasting, or the like.

When recording a signal, in FIGS. 1 and 2, 1/Me heat is prevented from being radiated to the substrate 1 side, and participates in the formation of the cavity 5.

On the other hand, since the lower thin layer 4 is thermally stable and has high ductility, it stretches to match the shape of the cavity 5 when recording pits are formed, and even after the cavity 5 has cooled. It can hold its swollen shape.

In this way, if the upper and lower surfaces of the thermally unstable recording layer 3 are sandwiched between the thermally stable lower thin layer 2 and the lower thin layer 4, the ends of the recording pits The parts can be made into very sharp and uniform shapes.

FIG. 14 and FIG. 15 are diagrams for explaining other embodiments of the present invention.

In the case of this embodiment, the recording layer 3 is made of a cyanine-based organic dye as in the previous embodiment, and the lower thin layer 2 and the lower thin layer 4 are made of a metal material with high ductility and malleability, such as aluminum or gold, or phthalocyanine. It is composed of materials such as.

When both the lower thin layer 2 and the lower thin layer 4 are made of metal materials, one of them is formed by sputtering or vapor deposition. Further, when both the lower thin layer 2 and the lower thin layer N4 are composed of an organic material such as phthalocyanine, these layers are formed by a spin-coding method.

In this embodiment as well, by irradiating the optical information recording medium with laser light, only the recording layer 3, which is thermally unstable, undergoes thermal deformation and hollow pits 5 are formed, as shown in FIG. It is formed.

In the above embodiment, a double-sided air sand inch structure was described, but the present invention is not limited to this, and can be applied to other types of optical information recording media.

[Effects of the Invention] As described above, the present invention has a recording layer made of a thermally deformable material, and a material that is thermally stable, highly ductile, and maintains a swollen state on top of the recording layer. A lower thin layer is provided, and hollow recording pits are formed in the recording layer, and portions of the lower thin layer corresponding to the recording pits are formed in an optical information recording medium having a height opposite to that of the recording layer. can be provided.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a double-sided air sand inch optical disk according to an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of the main part of the optical disk, and FIG. 3 is a T in the -shell structural formula. The figure which shows the representative example. Figure 4 is a diagram showing representative examples of A and A' in the -shell structural formula; Figures 5 to 12 are diagrams showing specific examples of various indole cyanine dyes; Figure 13 is a recording pit. FIG. FIG. 14 is an enlarged sectional view of a main part of an optical disc according to another embodiment of the present invention, and FIG. 15 is a schematic diagram of recording pits in the optical disc. FIG. 16 is an enlarged sectional view of a main part of a conventional optical disc, and FIG. 17 is a schematic diagram of recording pits in the optical disc. 77 It is designed to inflate to what size. Since the recording pits are hollow in this way, unlike conventional hole-shaped recording pits, dust does not adhere or accumulate inside the recording pits, and the recording pits have excellent environmental resistance. Furthermore, since the pit edges have a uniform shape, the C/N characteristics are high. Furthermore, even if the read light is repeatedly irradiated many times, the pit shape does not change and is stable, so no pit errors occur. Further, as described above, the present invention has a recording layer made of a material that is easily deformed thermally, and a material that is thermally stable, highly ductile, and maintains a swollen state on top of the recording layer. A lower thin layer is provided between the recording layer and the substrate, and the lower thin layer is made of a thermally stable material with low thermal conductivity, and hollow recording pits are formed in the recording layer. In addition, by expanding the portion of the lower thin layer corresponding to the recording pit toward the opposite side of the recording layer, environmental resistance and C/N characteristics can be further improved, and pit errors can be more reliably prevented from occurring. 7. Substrate, 2. Lower thin layer, 3. Recording layer, 4. Lower thin layer, 5. Cavity. 72-- Figure 13 5 Figure 11/6 Figure 17 Figure 4 Figure 5

Claims (11)

[Claims] (1) In 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 is made of a material that is easily deformed thermally, An upper thin layer made of a thermally stable, highly ductile material that maintains an expanded state is provided on the recording layer, and hollow recording pits are formed in the recording layer.
An optical information recording medium characterized in that a portion of the upper thin layer corresponding to the recording pit bulges on the side opposite to the recording layer. (2) In 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 is made of a material that is easily deformed thermally, An upper thin layer made of a material that is thermally stable, ductile, and maintains an expanded state is provided on the recording layer, and is thermally stable and conducts heat between the recording layer and the substrate. A lower thin layer made of a material with a low density is provided, and a hollow recording pit is formed in the recording layer, and a portion of the upper thin layer corresponding to the recording pit is on the opposite side of the recording layer. An optical information recording medium characterized by being bulged. (3) In claim (1) or claim (2),
An optical information recording medium, wherein the recording layer is composed of a cyanine-based organic dye. (4) The optical information recording medium according to any one of claims (1) to (3), wherein the upper thin layer is made of a metal material. (5) The optical information recording medium according to claim (4), wherein the metal material is aluminum. (6) The optical information recording medium according to claim (2), wherein the lower thin layer is made of phthalocyanine. (7) In 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, at least a lower thin layer, an upper recording layer, and an upper thin layer with the recording layer in between. 1. An optical information recording medium, wherein the recording layer is made of a material that is more easily deformed by heat than the lower thin layer and the upper thin layer. (8) The optical information recording medium according to claim (7), wherein the recording layer is composed of a cyanine-based organic dye. (9) The optical information recording medium according to claim (7), wherein both the upper thin layer and the lower thin layer are made of a metal material with high ductility and malleability. (10) The optical information recording medium according to claim (9), wherein the metal material is made of aluminum or gold. (11) The optical information recording medium according to claim (7), wherein both the upper thin layer and the lower thin layer are made of phthalocyanine.