JPH0816990B2 - Optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a read-only optical recording medium.

<Prior Art and its Problems> Optical recording has advantages over magnetic recording in that the recording medium and the head are not in contact with each other and high-density recording is possible. As this optical recording medium, a read-only optical recording medium, an additionally writable optical recording medium, and a rewritable optical recording medium are known. As the read-only optical recording medium according to the present invention, a compact disc or an optical recording medium is used. Video discs and the like have already been put to practical use and are generally commercially available.

These read-only optical recording media are manufactured by recording digital information as a concave-convex pattern on a master original plate by a laser beam or a mechanical engraving method, and based on this, a mold (a stamper) for mass production is recorded. ) Is produced, and the concave-convex pattern is duplicated on the transparent resin plate by a compression molding method, an injection molding method using this mold, or a photopolymer method of injecting an ultraviolet curable resin into the mold to cure it. .

Next, a metal layer with a high reflectance represented by aluminum is formed on the entire surface of the duplicated pattern surface by vacuum evaporation or sputtering, and the separately prepared resin substrate and the metal layer surface are adhered and read-only. To manufacture the optical recording medium.

Although a series of these manufacturing methods are well-known, it is possible to easily reproduce a large amount of a concave-convex pattern by making a mold, which is suitable for mass production. The process of forming is difficult to process a large amount at a time,
Not suitable for mass production.

Further, the reading method adopted in these optical recording media is such that a highly reflective uneven pattern portion formed in the medium is irradiated with coherent light typified by laser light, and the reflected light is minutely reflected. The information is read out as an information signal after being electrically converted by the sensor using such interference, and there are not a few errors that occur during reading.

Of course, it is desirable that this read error be zero, but sufficient reliability cannot be obtained as long as the interference due to the reflected light from the uneven portion is used. Further, since irregularities, scratches and stains directly impede the accurate reproduction of data, it is necessary to handle and store the medium carefully.

On the other hand, as an optical recording medium of another system, a portion having a high optical reflectance and a portion having a low optical reflectance are made of different materials, and a pattern is formed by the light and shade of the optical reflection difference. Optical recording media for recording information are known. In this method, a general light source such as a tungsten lamp can be used for the irradiation light for reading, and a gray signal with a large optical contrast is formed by the reflection and absorption (non-reflection) of the irradiation light, which causes the interference described above. The reliability of data reproduction is superior to that of the system.

A method of forming a light and shade pattern using an optical reflection difference according to this method is, for example, as disclosed in Japanese Patent Laid-Open No. 60-66346, that the above-mentioned two kinds of materials are layered on a substrate. It is formed by removing the layer of one material by an etching technique and exposing the other material on the back surface. However, in this method, the photomask is used every time the light and shade pattern is formed, the resist pattern is formed, and the manufacturing process is complicated because an etching process is further required, which cannot be said to be excellent in mass productivity. The manufacturing cost is also high.

<Purpose> The present invention has been made in view of the above problems of the prior art, by recording a digital information as a concave-convex pattern on a transparent resin substrate by a method using a die having excellent mass productivity,
By distinguishing the concavo-convex pattern with each ink having an optical high reflectance and a low reflectance, a light and shade pattern of digital information with a high contrast ratio is formed by using the optical reflection difference. An object of the present invention is to provide an optical recording medium that is error-free, has high reliability in data reproduction, is excellent in mass productivity, and is low in manufacturing cost.

<Outline> The present invention relates to a first information recording section obtained by filling ink into a concave pattern on a transparent resin substrate on which a concave-convex pattern corresponding to digital information is formed, and a first information recording section of the first information recording section. An ink provides an optical recording medium comprising an ink layer having a different reflection contrast ratio with respect to irradiation light and a second information recording section obtained by forming the ink layer on the first information recording section. Is.

<Detailed Description of the Invention> An embodiment of the optical recording medium of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of the optical recording medium of the present invention.
Reference numeral 8 denotes a transparent resin base material on which an uneven pattern corresponding to digital information is formed. The concave pattern portion is filled with ink 9 having a low reflectance with respect to irradiation light to form a first information recording portion. ing. Further, the high-reflection ink layer 14 having a desired thickness is formed on the first information recording section to form the second information recording section.

Further, a protective layer 16 for protecting the ink layer from external scratches is formed on the second information recording portion.

With the above configuration, the recording portion in the optical recording medium of the present invention comprises the first information recording portion corresponding to the concave pattern of the mold and the second information recording portion corresponding to the convex pattern, and the transparent resin substrate It is possible to obtain an optical recording medium having a light and shade pattern having a contrast formed by an optical reflection difference from one direction.

Next, an embodiment of the method of manufacturing the optical recording medium of the present invention will be described.

The digital information is recorded in advance as a concavo-convex pattern on the master original plate by a known method using laser light or mechanical engraving method, and based on this, a metal for mass production is produced by a mold replication method such as electroforming. A mold (stamper) is produced, and the concavo-convex pattern is duplicated on the transparent resin substrate by any of the methods shown in FIGS. 2, 3, and 4.

FIG. 2 is a schematic diagram of the compression molding apparatus 1 using the compression molding method. As a molding method, the mold 2 is attached to the upper part of the compression molding device 1, the transparent resin base material 3 is placed on the lower part, both are heated and compression-molded by a press method, and then cooled, whereby the transparent resin base material 3 is cooled. A copy of the uneven pattern of the mold 2 is obtained on the top.

FIG. 3 is a schematic cross-sectional view of an injection molding device 4 using an injection molding method, in which a transparent resin base material 3 obtained by heating and melting a transparent resin pellet 3 is injected into a mold 2 sealed under high pressure and cooled. By taking it out from the rear mold 2, a copy of the uneven pattern of the mold 2 can be obtained on the transparent resin substrate 3.

The transparent resin substrate 3 shown in FIG. 2 is not particularly limited as long as it is optically transparent, has desired mechanical and thermal characteristics, and is not deformed or deteriorated in a subsequent step. However, films, sheets, blocks, etc. of polyvinyl chloride, polyvinylidene chloride, acrylic resin, polycarbonate, nylon, polyester resin, etc. can be used, and the transparent resin substrate 3 shown in FIG. The resin pellet 3'heated and melted can be used.

FIG. 4 is a sectional view of a photopolymer method using an ultraviolet curable resin.

A transparent resin substrate 6 is provided on the mold 2, and an ultraviolet curable resin 5 is filled between the mold 2 and the transparent resin substrate 6. The transparent resin substrate 6 is irradiated with an ultraviolet lamp 7 to cure the ultraviolet light. The mold resin 5 is cured.

After curing, by peeling from the mold 2 together with the transparent resin substrate 6 based on the ultraviolet curable resin 5, a copy of the uneven pattern can be obtained.

The ultraviolet curable resin 5 shown in FIG. 4 has excellent optical transparency after curing and has desired mechanical and thermal characteristics,
There is no particular limitation as long as it does not cause deformation or deterioration in the subsequent steps, and liquid ultraviolet curable resins such as acrylic and polyester resins can be used.

Further, as the transparent resin substrate 6, the resin film or sheet used in the compression molding method shown in FIG. 2 can be used.

FIG. 5 is a cross-sectional view of the transparent concavo-convex pattern resin 8 reproduced by the mold 2 by the compression molding method, the injection molding method, and the photopolymer method shown in FIGS. 2, 3, and 4.

The transparent resin substrate 6 exists only when the photopolymer method is used, and does not exist when other molding methods are used.

FIG. 6 shows a method of filling the uneven pattern portion of the transparent uneven pattern resin 8 with the low reflectance ink 9 by a doctor method. The low reflectance ink 9 is preferably a black ink having a high optical transmission density, but is not limited to this as long as it has a high optical transmission density and a high optical contrast ratio with the high reflectance ink 13 shown in FIG. Not something.

As the material of the doctor knife 10, the low-reflectance ink 9 is scraped off by bringing the doctor knife 10 into contact with the transparent uneven pattern resin 8 and moving it in one direction.
Any material such as rubber, ceramic, metal or resin may be used as long as it has a function of exposing the transparent convex pattern portion 11 and at the same time filling the low pattern ink into the concave pattern ink filling portion 12.

FIG. 7 shows a transparent uneven pattern resin 8 filled with the low reflectance ink 9 in the concave pattern ink filling section 12 by the doctor method shown in FIG. As one example, a method for producing a first substrate 15 provided with a high-reflectance ink 13 as a high-reflectance ink layer 14 with a desired thickness by a doctor coating method using a doctor knife 10 will be shown.

As a coating method, in addition to the above method, a bar coating method,
Spinner method, roll coating method, spray method, etc. can also be used.

Further, as a method of providing the high reflectance ink layer 14, a printing method such as gravure printing, offset printing, screen printing can be used, and by using the printing method, design printing of logos, illustrations and the like other than the uneven pattern portion can be performed. It is also possible to perform them at the same time, which leads to simplification of the process.

As the high-reflectance ink 13, a gold ink mainly containing copper powder or a silver ink containing aluminum powder can be used, but the low-reflectance ink 9 has a high optical transmission density.
The optical contrast ratio is not limited to this as long as it is large.

Finally, a protective layer 16 for protecting the ink layer from external damage is adhered to the ink layer surface to form the optical recording medium shown in FIG.

As a bonding method, there is a method using heat fusion or an adhesive.The adhesive can be arbitrarily selected except for a solvent type because the adhesive itself is sealed, and for example, an acrylic type, an epoxy type, etc. A room temperature or thermosetting type can be used.

The material of the protective layer 16 is not particularly limited as long as it has desired mechanical and thermal characteristics, and may be the same as the resin sheet or film used in the compression molding method shown in FIG. 2 according to the present invention. Of course, resin sheets such as polyethylene, polypropylene, and ABS resin, films, or metal plates can also be used.

The thickness of each layer of the optical recording medium shown in FIG. 1 is not particularly limited, and may be set according to the mode of the recording medium according to the application such as a card or a disk.

In the above description, the concave pattern ink filling portion 12 is filled with the low reflectance ink 9 to obtain the high reflectance ink.
A high-reflectance ink layer 14 is formed at 13 and the two are overlapped to form a light and shade pattern consisting of an optical reflection difference. It is also possible to form a light and shade pattern having an optical reflection difference in which a portion where the reflectance ink is used is a low reflectance ink.

<Example> An uneven pattern is formed on a transparent acrylic resin having a thickness of 0.5 mm by compression molding using a mold having an uneven pattern having a dot size of 10 μm square, an uneven step of 5 μm, and a dot pitch of 10 μm. Was duplicated.

Next, black ink is poured onto the concavo-convex pattern surface of the transparent acrylic resin, and the black ink is scraped off with a Teflon resin doctor knife to fill the concave pattern portion with the black ink and the convex pattern portion with transparent acrylic resin. The resin surface was exposed.

This was placed in a drying oven and dried at 80 ° C. for 30 minutes to cure the black ink.

Next, using a silver ink mixed with aluminum powder, a silver ink layer is formed on the entire surface of the transparent acrylic resin surface filled with black ink by the doctor code method, and the ink is dried again at 80 ° C for 30 minutes in a drying oven. , Curing was performed.

Next, a separately prepared white polyvinyl chloride having a thickness of 0.3 mm and the surface of the silver ink layer were adhered to each other with an epoxy-based room temperature curing type adhesive, which corresponded to the uneven pattern of the mold in the optical recording portion. An optical recording medium having a light and shade pattern having a good contrast consisting of an optical reflection difference was obtained.

<Effects of the Invention> According to the present invention, a concave-convex pattern corresponding to digital information is excellent in mass productivity in a read-only optical recording medium that records information by the contrast between an optically high reflectance and a low reflectance. By using a simple mold, a simple method such as printing or coating is performed on a transparent resin substrate to reproduce the uneven pattern from the optical reflection difference with low reflection ink and high reflection ink. It is possible to obtain an optical recording medium which can be formed into a light and shade pattern and which does not require etching or a metal layer vapor deposition step, has extremely high mass productivity and can be manufactured at a reduced cost.

Since the ink used in the present invention does not undergo many chemical treatments, it can be selected from a wide range of materials. When forming a layer of the ink by a printing method, other printing can be performed at the same time. This leads to simplification of the process.

Furthermore, in order to form a light and shade pattern with good contrast that consists of optical reflection differences, instead of coherent light such as laser light, it is irradiated with general tungsten light, LED, etc., and a light receiving element such as CCD The reading device can be simplified as well.

Further, since it is not necessary to use laser light for reading, it is possible to select from a wide range of materials without being affected by the birefringence of the transparent resin substrate.

[Brief description of drawings]

FIG. 1 is a sectional view of the optical recording medium of the present invention.
FIGS. 4 to 4 are schematic views of the molding apparatus, and FIGS. 5 to 7 are enlarged views of the cross section in each step of the present invention. 1: Compression molding device 2: Mold 3: Transparent resin substrate 3 ': Transparent resin pellet 4: Injection molding device 5: UV curable resin 6: Transparent resin substrate 7: UV lamp 8: Transparent uneven pattern resin 9: Low reflectance ink 10: Doctor knife 11: Transparent convex pattern area 12: Concave pattern ink filled area 13: High reflectance ink 14: High reflectance ink layer 15: First substrate 16: Protective layer

Claims (1)

[Claims] 1. A first information recording section obtained by filling ink into a concave pattern section on a transparent resin substrate on which a concave-convex pattern corresponding to digital information is formed, and ink of the first information recording section. Is an optical recording medium comprising a second information recording section obtained by forming an ink layer having a different reflection contrast ratio with respect to irradiation light on the first information recording section.