JPS5817553A - Optical recording medium - Google Patents

Abstract

PURPOSE:To perform high-density and high-sensitivity recording by forming a mixed layer of synthetic resin and a light absorber as the surface of a substrate which comes into contact with a recording layer. CONSTITUTION:The surface of a substrate 20 which comes into contact with a recording layer 22 is formed by using a material obtained by mixing a light absorber with synthetic resin, e.g. carbon black with polyvinyl chloride. The recording layer 22 uses a mixture of nitrocellulose and ''Oleosol Fast Yellow 2G ''. The substrate 20, when irradiated with a laser beam 30, absorbs it in the carbon black to generate heat locally. Because of this heat generation, the nitrocellulose disappears to form a pit. Thus, this invention eliminates the need to mixing the light absorber into the recording layer, so small pits are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called optical recording medium in which information is optically read out by physically deforming a recording layer.

Magnetic recording media have traditionally been used as information storage media, but they have limitations in information recording density, limitations in improving noise characteristics, and problems with contact with the media. However, optical recording media have recently attracted attention as an alternative to magnetic recording media.

Among optical recording media, in so-called heat mode recording that uses light as heat, the medium is selectively irradiated with coherent light such as a laser beam to melt or burn the medium to create small holes in the medium. Information is recorded depending on the presence or absence of the information. Known materials for the recording layer used in conventional heat mode recording include tellurium, tellurium selenium-arsenic compounds, and mixtures of nitrocellulose and light absorbers. In the case of each of the above-mentioned materials, the records are permanent and the records cannot be erased or rewritten.
No. 6-51160 proposes an organic polymer material such as a low-heavy compound mainly composed of styrene (for example, styrene oligomer), nylon, or ABS resin, which records information by thermally deforming the recording layer.

FIG. 1 shows an example of the structure of a conventional optical recording medium, where 10 is a substrate, 1
2 is a reflective layer made of an aluminum thin film provided thereon, and 14 is a recording layer. When recording information, the recording layer 14 is selectively irradiated with a laser beam to partially remove or deform the recording layer to form pits, and during reproduction, the layer 14 is irradiated with a weak laser beam to form pits. The presence or absence of pits is detected based on the difference in the amount of reflected light between the areas where the pits exist and the areas where they do not exist. The reflective layer 12 functions to increase the amount of reflected light and S/N.

By the way, in conventional optical recording media, in order to perform high-density optical recording during recording, the particle size of the light absorber must be sufficiently small (for example, 1000X or less), but in general, the particle size of the dye or pigment is When the wavelength becomes smaller and approaches the wavelength of the laser beam, a problem arises in that the light absorption ability is extremely reduced. For example, when a pigment with a particle size of about 0.1 μm is used as an absorbent, the pit diameter is about 3 μm at most. moreover,
For example, when the recording layer 14 is made of nitrocellulose and carbon black is mixed therein as an absorbent, it has the disadvantage that it is difficult to uniformly disperse the carbon black.

However, with conventional optical recording media, it is difficult to perform high-density and high-sensitivity recording.

Therefore, an object of the present invention is to improve the above-mentioned drawbacks of the conventional technology, and the present invention is characterized in that it provides an optical recording medium having a substrate and an optical recording layer on at least one surface of the substrate, at least the surface of the substrate in contact with the recording layer. However, there is an optical recording medium formed by mixing and molding a synthetic resin and a light absorbing agent.

FIG. 2 shows an example of the structure of an optical recording medium according to the present invention, in which numeral 22 shows a substrate and a recording layer having a thickness of about 1 μm formed thereon. At least the surface of the substrate that is in contact with the recording layer n has a structure in which a light absorbing agent is mixed into a synthetic resin. Carbon black is soft, so when it is kneaded with vinyl chloride and compression molded, a smooth, uniform surface with high light absorption ability can be obtained. I can do it.

In FIG. 2, the recording layer n is composed of a thin film of a self-oxidizing resin such as nitrocellulose. At this time, since the light reflectance of nitrocellulose is as low as about 4%, the light reflectance is increased (for example, 10 ), playback output,
and 8/N can be increased.

In the above configuration, when the laser beam 30 is irradiated onto the recording layer n, part of the energy of the laser beam is reflected or absorbed by the recording layer, but most of it reaches the substrate, is absorbed by the carbon black, and is absorbed by the substrate. partially generates heat. Due to this heat generation, self-oxidizing nitrocellulose disappears, and pits that store information are obtained in the disappearing parts. On the other hand, during reproduction, the presence or absence of pits can be detected by irradiating the recording layer with a weak laser beam and detecting the difference in intensity of reflected light between areas with and without pits. At this time, since the recording layer contains a reflective dye, the reflected light is sufficiently strong and a sufficient S/N ratio can be obtained.

There is no need to mix a light absorber into the recording layer.
High-density optical recording can be performed due to the sufficient light absorption ability of the substrate. Although it is difficult to reduce the pit diameter to 3 μm or less with the conventional structure in which carbon black is mixed in the recording layer, the present invention allows pits with a diameter of 1 μm or less.

In addition, since there is no need to provide the l-light reflecting layer 12 made of metal as in the prior art, the structure of the optical recording medium is simplified and the manufacturing cost is reduced.

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BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an example of the structure of a conventional optical recording medium, and FIG. 2 shows an example of the structure of an optical recording medium according to the present invention. addition; substrate n; recording layer

Claims (1)

[Scope of Claims] fl) An optical recording medium having a substrate and an optical recording layer on both sides thereof, wherein the surface of the substrate in contact with the recording layer is coated with a synthetic resin and a light absorbing agent. An optical recording medium characterized in that it is formed by mixed molding. (2) An optical recording medium according to claim 1, in which the optical recording layer is composed of nitrocellulose containing a light-reflecting dye. (3) Light An optical recording medium according to claim 2, in which the reflective dye is oleosole fast yellow 2G. (4) A patent claim, in which at least the surface of the substrate in contact with the recording layer is a mixture of vinyl chloride and carbon black. Optical recording media according to the first item in the range.