JPH01137439A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To enable the protection of an optical recording layer by a protective layer while obtaining a high recording sensitivity by providing a buffer layer which can be freely deformed between the protective layer and the optical recording layer. CONSTITUTION:The buffer layer 17 which can be freely deformed is provided between the protective layer 13 and the optical recording layer 12. The buffer layer 17, therefore, absorbs the deformation of the optical recording layer 12 at the time of forming pits on the optical recording layer 12 by projecting a laser beam hnu on the layer thereby deforming the layer 12. The high recording sensitivity is thereby obtd. without hindering the formation of the pits. Since the superposition of the protective layer 13 on the surface of the optical recording layer 12 via this buffer layer 17 is possible, the thickness of the disk is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical information recording medium in which information is recorded by locally deforming an optical recording layer using a recording laser beam.

[Prior Art] Optical information recording media using optical recording layers comprising metal layers such as Te, Bi, Mn, etc. and dye layers such as cyanine, merocyanine, and phthalocyanine have been developed. This type of optical information recording medium focuses and irradiates the optical recording layer with a laser beam to partially evaporate or sublimate the material forming the recording layer, leaving a trace with a diameter of 1 μm.
Front and rear holes, or bits, are opened to record information.

On the other hand, an optical recording layer is formed using a dye polymer or a metal carbide,
By irradiating the laser beam, the optical recording layer is deformed,
Optical information recording media that form pits have been developed. For example, as shown in FIG. 4(a), the optical recording layer 2 may be deformed into a convex (or concave) shape by irradiation with a laser beam, or as shown in FIG. The surface of the optical recording layer 2, which has irregularities formed therein, is locally flattened to form pits 4.

The latter optical information recording medium, like the former, has less noise caused by deformation of the periphery of the hole forming the pit and less noise caused by flying debris.
Good recording characteristics can be obtained.

[Problems to be Solved by the Invention] However, in the latter optical information recording medium, the optical recording layer 2 is deformed during recording, so when a protective layer is brought into close contact with the surface of the optical recording layer 20, the optical recording The surface of layer 2 is not sufficiently deformed, resulting in low recording sensitivity. For this reason, in conventional disk-shaped optical information recording media, as shown in FIG. A laminated structure called the so-called air sandwich method is adopted.

However, this structure has the disadvantage that the disk becomes considerably thicker. Specifically, it is not possible to obtain a disc with a thickness of 1.5 mm or less, which makes it impossible to share a conventional compact disc player and does not meet the standards set for compact discs.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide an optical information recording medium in which the optical recording layer can be protected by a protective layer while obtaining high recording sensitivity, and which can be made thinner.

[Means for Solving the Problem] That is, the object of the present invention is to provide an optical recording layer 12 on a substrate 11.
An optical information recording medium in which a core layer 12 is covered with a protective layer 13, characterized in that a deformable buffer layer 17 is provided between the protective layer 13 and the optical recording layer 12. This is achieved using an information recording medium.

[Function] In the optical information recording medium according to the present invention, when the optical recording layer 12 is irradiated with a laser beam hv to deform the layer 12 and form pits, the buffer layer 17 is Since it absorbs the deformation of No. 2, it does not interfere with the formation of pits, and high recording sensitivity can be obtained. Furthermore, since the protective layer 13 can be overlapped on the surface of the optical recording layer 12 via the buffer layer 17, compared to the conventional air sandwich method,
The thickness of the disc can be significantly reduced.

[Example] Next, an example of the present invention will be described with reference to the drawings. An optical recording layer 12 is formed on the surface of a transparent substrate 11 using a metal or an organic dye, and a protective layer 13 is formed on the surface side of the optical recording layer 12. At the same time, a buffer layer 17 is provided between the optical recording layer 12 and the protective layer 13.

As the substrate 11, a transparent donut-shaped disk such as a polycarbonate plate, a polymethyl methacrylate plate, an epoxy plate, a glass plate, etc. is used.

Furthermore, for the protective layer 13, a film or sheet made of polycarbonate, polymethyl methacrylate, polyethylene terephthalate, glass, or the like is generally used.

The buffer layer 17 uses a fluid gas, liquid, powder, etc., as well as a solid that can be elastically or plastically deformed. For example, gelatin, rubber, nidistomer, nitrocellulose, cellulose acetate, polyvinyl alcohol, collodion, acrylic resin, polyvinyl formal, polyvinyl butyral,
Foamed urethane, metal powder with a particle size of 1 to 20 μm, particle size of 1 to 2
Ceramic powder with a particle size of 0J1m, resin powder with a particle size of 1 to 2011m, a porous polymer material, and a combination thereof, as well as chlorofluorocarbon gas, air, nitrogen gas, argon gas, etc. In any case, it is preferable to use one that is stable and easy to flow and deform.

When a solid material is used as the buffer layer 17, for example, as shown in FIG. Disc-shaped optical information recording media can be made. On the other hand, when using a fluid or powder as the buffer layer 17, as shown in FIGS. Means are taken to hold it between the layers 13 and 13.

Next, examples of the present invention will be specifically described.

(Example 1) Thickness 1°2 mm with pre-glue and pre-pit
An epoxy resin dyed with naphthol green dye was applied onto a polycarbonate substrate 11 by a spinner method to form an optical recording layer 12 having a thickness of about 1100 nm. Urethane foam was sprayed onto the surface of this optical recording layer 120 to form a buffer layer 17 with a thickness of about 3 μm. Further, on this buffer layer 17, a protective layer 13 with a thickness of about 200 μm is provided.
A polycarbonate film was adhered to the entire surface. Through the above steps, a disc-shaped optical information recording medium was produced. The concept of this structure is shown in FIG.

For this optical information recording medium, a semiconductor laser with a wavelength of 780 nm is used, and a linear velocity of 1.4 m/5eC1 recording frequency of 50 nm is used.
Recording was performed by irradiating the optical recording layer 12 with a 0 kHz laser beam hv from the substrate 11 side. The optimized recording laser power at this time was 4.3 mW. Thereafter, a laser beam hv with an output of 0.3 mW was applied to the optical recording layer 12, and the C/N of the recording surface was measured at the same linear velocity as during recording, and it was found to be 43 dB.

Note that the thickness of the optical information recording medium was 1.4 mm.

(Example 2) A phthalocyanine cobalt salt dispersed in acrylic resin was coated on the surface of a 1.2 mm thick glass substrate 110 with pre-group pre-pits by a spin cord method.
A film was formed to a thickness of 0nrn, and this was further overcoated with a glass layer having a thickness of 20nm to form an optical recording layer 12.

This is introduced into a nitrogen gas stream, and the optical recording layer 12 is
A polymethyl methacrylate film having a thickness of 100 μm was superimposed on the surface of the substrate 11, the inner and outer edges of the substrate 11 were sealed, and nitrogen gas was sealed therein to form a buffer layer 17. A conceptual diagram of this structure is shown in FIG.

When recording and reproducing were performed on this optical information recording medium in the same manner as in Example 1, the C/N of the reproduced signal was as follows.
44 dB, and the optimized recording power was 6.0 mW.

Note that the thickness of the optical information recording medium is also 1.3 mm in this case.
It was below.

(Example 3) Te alloy was vacuum-deposited to a thickness of 50 nm on the surface of a 1.2 mm thick epoxy substrate on which fine irregularities had been formed in advance to form an optical recording layer 12. By spray method,
Polyvinyl alcohol was applied onto the optical recording layer 12 to form a buffer layer 17. Then, as a protective layer 13, an acrylic hard coat was applied on the buffer layer 12.

A conceptual diagram of this structure is shown in FIG.

When recording and reproducing were performed on this optical information recording medium in the same manner as in Example 1, the C/N of the reproduced signal was as follows.
46 dB, and the optimized recording power was 5.4 mW.

The thickness of the optical information recording medium is also 1.3 m in this case.
It was m.

(Comparative Example) In Example 1, without spraying urethane foam on the surface of the optical recording layer 12, a polycarbonate film with a thickness of about 20 OL 1 m was directly adhered to the entire surface of the optical recording layer 12 with adhesive, and the optical recording layer 12 was not sprayed with urethane foam. Created an information recording medium.

For this optical information recording medium, a semiconductor laser with a wavelength of 780 nm is used, and a linear velocity of 1.4 m/5eC1 recording frequency of 50 nm is used.
An attempt was made to record on the four layers 12 by irradiating the optical recording layer 12 with a 0 kHz laser beam from the substrate 11 side, but complete recording was not possible even with a recording power of 8 mW.

[Effects of the Invention] As is clear from the above description, according to the present invention, an optical information recording medium of a type in which recording is performed by locally deforming the optical recording layer 12 by irradiating it with laser light. Since the buffer layer 17 facilitates deformation of the surface of the optical recording layer 120, the optical recording layer 12 is protected by the protective layer 13 without reducing recording sensitivity, and is thinner than the conventional one of the same type. An optical information recording medium is obtained.

[Brief explanation of the drawing]

1 to 3 are longitudinal cross-sectional views of optical information recording media enlarged in the thickness direction showing each embodiment of the present invention, and FIG.
), (b) are longitudinal cross-sectional views of main parts showing the concept of optical recording.
The figure is an enlarged vertical cross-sectional view of a main part in the thickness direction showing a conventional example of an optical information recording medium. 11... Substrate 12... Optical recording 1 13... Protective layer 17... Buffer layer

Claims (4)

[Claims] (1) In an optical information recording medium in which an optical recording layer 12 is formed on a substrate 11 and the layer 12 is covered with a protective layer 13, the protective layer 13
An optical information recording medium characterized in that a deformable buffer layer 17 is provided between the optical recording layer 12 and the optical recording layer 12. (2) An optical information recording medium according to claim 1, in which the buffer layer 17 is made of gas. (3) An optical information recording medium according to claim 1, in which the buffer layer 17 is made of a liquid. (4) An optical information recording medium according to claim 1, in which the buffer layer 17 is made of an elastic body. (5) An optical information recording medium according to claim 1, in which the buffer layer 17 is made of a plastic material. (6) An optical information recording medium according to claim 1, in which the buffer layer 17 is made of powder.