JP2709904B2 - Optical recording method and optical recording medium - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording method using a heat mode type optical recording medium and a recording medium recorded by the recording method. [0002] Generally, a magnetic recording system is widely known for recording and reproducing information. For example, magnetic tape,
Magnetic recording media such as a magnetic disk and a magnetic card can be used. One use example is a magnetic card used as a cash card or the like. As is well known, the magnetic recording / reproducing system can easily record, erase, and re-record information. Therefore, a magnetic card using this method has low reliability of information such as recorded information being changed when it is abused or placed in a magnetic field by a magnet or the like. Also,
Magnetic cards can only record low-density information due to the limitations of the magnetic head, and because of the size of the card,
There is a disadvantage that only a very small amount of information can be recorded. [0004] Therefore, it is impossible to take a complicated signal form to prevent abuse due to the above-mentioned restrictions on the magnetic card. In order to improve these disadvantages, a recording and reproducing method based on an optical principle has been recently proposed. An optical disk, an optical card, and the like can be cited as those using the optical recording and reproducing method. [0005] Among them, optical cards have a wide range of applications, such as bank cards, credit cards, identification cards, driver's licenses, commuter passes, public telephone cards, and gasoline purchase cards. Expected. Incidentally, there is a heat mode as an optical recording medium applicable to an optical card. The heat-mode optical recording medium is an optical recording medium that uses recording light as heat. As an example, a part of the medium is melted or removed by recording light such as a laser, and is called a pit. There is a pit formation type in which a small hole is formed, writing is performed, information is recorded by the pits, and the pits are detected by a reading light and read out. In the case of such a pit formation type medium, particularly a medium using a semiconductor laser capable of downsizing the apparatus, a Te
In most cases, the recording layer is made of a material mainly composed of a metal such as JP-A-58-50046.
No. 2). The mechanism of recording information on a recording layer mainly composed of metal is as follows. The metal film is heated by light irradiation and melts, and the metal in a liquid state is formed because the upper part is free space. It is drawn to the surroundings by surface tension to form pits. However, in the case of such a recording layer mainly composed of metal, a space is required above the metal film due to the problem of the recording mechanism as described above, and a so-called air sandwich structure is indispensable. It is said that
The overall thickness is large, and it has been desired to reduce the thickness. The issue was how to make the card thin, especially. Therefore, in recent years, there has been an increasing number of proposals and reports on the use of an organic material-based recording layer mainly composed of various dyes in place of a metal-based recording layer because higher sensitivity is required. For example, Journal of applied Polymer Scien
In ce, Vol. 24, a dye-based recording layer is provided on a resin substrate, and the dye of the recording layer is irradiated with laser light to diffuse the dye into the substrate, deform the substrate together with the recording layer, and change the pit depth. Attempts have been made to increase the size. However, these proposals have been stopped so far, and no actual recording medium has been realized so far. For example, in an optical recording medium, particularly an optical card,
In order to prevent damage to the recording layer, it is necessary to form a protective film on the recording layer.
In the recording layer of urnal of applied Polymer Science, the upper part is open and it is an open system, but if a protective layer is provided, the layers are in close contact both at the top and bottom, and it becomes a closed system. No attempt has been made to determine whether pits can be formed without any problem. Then, in the case of such a closed system, the above Journal
Even if pits are formed by the same mechanism as in the case of applied polymer science, naturally the contrast near the pits is reduced (the reflectivity of the entire film is reduced, and the rise of the dye around the pits can be formed). The sensitivity is expected to decrease. SUMMARY OF THE INVENTION An object of the present invention is to provide an optical recording method using a thin heat mode optical recording medium having a high contrast and a high S / N ratio, and an optical recording method using this recording method. Recording medium. [0012] Such an object is achieved by the present invention described in the following (1). (1) A heat mode optical recording medium, which is a laminate having a resin substrate, a recording layer, and a protective film, wherein the recording layer includes a dye layer and a metal layer, is irradiated with recording light. An optical recording method in which a recording layer and a substrate are simultaneously deformed to form a space inside and perform recording. (2) A heat mode optical recording medium having a resin substrate, a recording layer, and a protective film, wherein the recording layer is a laminate including a dye layer and a metal layer, and is irradiated with recording light. An optical recording medium on which recording is performed by simultaneously deforming the recording layer and the substrate to form a space therein. When recording is performed using the heat mode type recording medium of the present invention, the recording layer and the substrate are simultaneously deformed by irradiation of the recording light to form a space inside and provide a metal layer. As a result, the contrast and the S / N ratio are improved. The specific configuration of the present invention will be described below in detail. FIG. 1 shows an embodiment of the present invention. As shown in FIG. 1, a heat mode optical recording medium 1 according to the present invention has a substrate 2. The substrate 2 is usually made of a thermoplastic resin material, and may be any of acrylic resin, polycarbonate, polyvinyl chloride, nylon, polyolefin, polyester and the like. As described later, the recording layer and the substrate are simultaneously deformed by the irradiation of the recording light to form a space inside the medium, and the printing property, the lamination property, the moisture resistance,
Considering the strength and the like, a polyvinyl chloride polymer is preferred. Examples of the polyvinyl chloride polymer include vinyl chloride homopolymer, vinyl chloride-vinyl acetate,
It may be a vinyl chloride copolymer such as vinyl chloride-maleic acid. The thickness of the substrate 2 is about 0.1 to 1.0 mm. Note that a tracking groove may be formed in such a substrate 2. On the substrate 2, a recording layer 3 is provided. Although not shown in FIG. 1, the recording layer 3 of the present invention is composed of a laminate including a dye layer and a metal layer. As described above, the recording layer preferably exhibits high reflectivity to recording light or reproduction light, and generally preferably exhibits a reflectance of 25% or more. Such a recording layer has a total thickness of 0.01 to 1
The thickness may be 0 μm, and particularly preferably 0.05 to 0.1 μm. The dye layer may be composed of a dye alone or a dye composition. The dye to be used may be appropriately determined according to the wavelengths of the writing light and the reading light, from those that effectively absorb the light. In this case, it is preferable to use a semiconductor laser as the light source from the viewpoint that the device can be miniaturized. Therefore, the dyes are cyanine, phthalocyanine, anthraquinone, azo, triphenylmethane, pyrylium or pyrylium. Thiapyrylium salts and the like, which are highly reflective, are preferred. When a coloring composition is used, it may contain a self-oxidizing resin such as nitrocellulose or a thermoplastic resin such as polystyrene or nylon. In addition, a quencher can be contained in order to prevent oxidative deterioration of the dye. Further, other additives may be contained. In such a case, a mixture of an indolenine-based cyanine dye and a quencher such as a bisphenyldithiol-based dye is particularly preferable. It is also preferable to use these as an ion binder of the cation of the dye and the anion of the quencher. In such a case, the layer of the dye layer is formed of a ketone, an ester, an ether, an aromatic,
The coating may be performed using a solvent such as an alkyl halide or an alcohol. The metal layer is made of Ag, Au, Bi, In,
It is formed of a single metal or alloy such as Sn, Al, Ga, Ni, and Cr. In such a case, the formation of the metal layer may be performed by vapor deposition, sputtering, or the like. As shown conceptually in FIG. 1, the recording layer 3 is configured to be deformed simultaneously with the above-mentioned substrate 2 by irradiation of recording light. The above Journal of applied Polymer Scien
As is well known from ce and the like, and as conceptually shown in FIG. 1, in order to simultaneously deform the resin substrate and the recording layer, the dye layer of the recording layer is And a metal layer is preferably disposed thereon. This is because the diffusion of the dye to the substrate is performed on condition that the dye is in contact with the substrate. Such a recording layer alone may be used as an optical recording section. Alternatively, an optical recording section can be formed by providing an upper layer or a base layer on the recording layer. Such an optical recording portion is provided in a stripe shape, a rectangular shape, or the like on the entire surface or a part of the substrate, depending on the use of the optical recording medium, particularly, a card or the like. As shown in FIG. 1, a protective film 4 is provided on the optical recording section. The protective film 4 can be formed by coating, but is usually formed by fusing or bonding a film body. As the material of the protective film 4, various resins are suitable, and the above-mentioned polyvinyl chloride-based polymer is particularly preferable from the viewpoints of moisture absorption, cracking resistance and the like. And
Its thickness is about 0.1 to 1.0 mm. This is because if the thickness is less than 0.1 mm, the strength becomes insufficient, and if it exceeds 1.0 mm, it becomes practically inappropriate. The protective film 4 may have a coating layer for preventing various cracks. Further, the substrate may have an optical recording layer and a protective layer on both surfaces thereof, and these may be provided on only one surface. In the latter case, a protective layer may be formed on the back surface of the substrate. Such a protective film 4
Is usually in close contact with the optical recording layer 3 as shown in FIG. As described above, by irradiating the recording layer 3 with recording light, the recording layer 3 is configured to deform simultaneously with the above-described substrate 2 as conceptually shown in FIG. ing. At this time, the metal layer in the recording layer 3 is the same as that disclosed in the above-mentioned prior art section.
As can be seen from Japanese Patent Publication No. 00462, it is natural that in the case of metal, since the layer or film is not destroyed even if deformed, it becomes thin as shown in FIG. Deforms so that it hangs slightly. The recording layer may be irradiated with light from the protective layer side or the substrate side. When the recording layer is irradiated from the substrate side, it is preferable to use a transparent substrate as the substrate. As described above, the pits 21 are formed in the heat mode optical recording medium 1 of the present invention. The pits 21 are formed by melting and deforming a part of the substrate together with the recording layer by recording light such as laser light. The diameter of the pit is usually about 0.8 to 10 μm, and the depth of the pit (the depth from the lower surface of the protective layer to the bottom of the recess formed in the substrate) is usually about 0.05 to 1 μm. . The size and number of the pits may be determined in consideration of the necessary information storage capacity and various technical problems. According to the present invention, since the recording layer and the substrate are simultaneously deformed by irradiation of the recording light, a heat mode type optical recording medium having improved contrast and S / N ratio can be obtained. The present inventors have conducted various experiments to confirm the effects of the present invention. An example is shown below. EXPERIMENTAL EXAMPLE 1,1 ', 3,3,3', 3'-Hexamethyl-2,2'-indoritriene at a thickness of 0.08 μm on a 85 × 54 × 0.3 mm vinyl chloride resin sheet. Carbocyanine perchlorate (2 parts by weight) and IRA-PA-1006
[Mitsui Toatsu Chemicals Bisphenyldithiol Ni
Complex) (1 part by weight). Then, a metal film made of Au was formed thereon with a thickness of 0.02 μm by sputtering. The thickness of the recording layer is 0.1
μm. On this, a 0.3 mm thick sheet made of a vinyl chloride resin was heat-sealed. In addition, the substrate and the recording layer were configured to be simultaneously deformed by irradiation of recording light (semiconductor laser). The pit formed by the deformation has a depth of 0.
The width was 3 μm, the width was 5 μm, and the interval was 20 μm. When recording / reproducing was performed using a semiconductor laser, the contrast was remarkably improved as compared with the case where the substrate and the recording layer were not simultaneously deformed by applying an Si-based undercoat on the substrate. did. Further, the contrast was improved about 1.5 times as compared with the recording layer having only the dye layer.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual sectional view of one example of a heat mode type optical recording medium of the present invention. FIG. 2 is a more accurate cross-sectional view of FIG. FIG. 3 is a more accurate cross-sectional view of FIG. [Description of Signs] 1 Heat mode type optical recording medium 2 Substrate 3 Recording layer 4 Protective film 21 Pits 3-1 Metal layer

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hiroshi Hosaka               1-5-1, Taito, Taito-ku, Tokyo Tokyo               Inside Magnetic Printing Co., Ltd. (72) Inventor Shohei Mimura               1-5-1, Taito, Taito-ku, Tokyo Tokyo               Inside Magnetic Printing Co., Ltd.                (56) References JP-A-54-89605 (JP, A)                 Special Table 1983-500462 (JP, A)

Claims (1)

(57) [Claims] Using a heat mode type optical recording medium that has a resin substrate, a recording layer, and a protective film, wherein the recording layer is a laminate including a dye layer and a metal layer, and irradiates recording light to perform recording. Deform the layer and the substrate simultaneously,
An optical recording method in which recording is performed by forming a space inside. 2. A heat mode optical recording medium having a resin substrate, a recording layer, and a protective film, wherein the recording layer is a laminate including a dye layer and a metal layer, and is irradiated with recording light. Deform the recording layer and the substrate at the same time,
An optical recording medium on which recording is performed by forming a space inside.