JP2754373B2 - Optical recording medium and manufacturing method thereof - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, which is an optical ROM (read only memory) medium storing optical read-only information, and a method of manufacturing the same. . 2. Description of the Related Art Among optical recording media, a read-only medium is one in which information is divided into pits in advance and the pits are recorded on the optical recording medium. There are roughly two types of pit recording / reproducing methods. One is to record data as uneven pits, and when irradiating with laser light, the laser light is diffracted with a phase difference caused by the uneven pits. The other is a method in which pits with different reflectivities are recorded as, for example, the presence or absence of a metal thin film, and the read / reproduce is performed as a signal based on the difference in reflectivity when laser light is irradiated. is there. Although an optical card is light and inexpensive, it is thinner than an optical disk (0.76 m in accordance with the magnetic card standard).
m thickness), easy to bend and poor flatness. Therefore, the reading accuracy is low, and the signal reading method is usually a method based on the difference in the reflected light, and the pits are large.
And Usually, a difference in reflectivity is generated in a recording portion by a method of forming a portion where a light-reflective metal thin film exists and a portion where no light-reflective metal thin film exists as described above. As one method of generating the difference in the reflectivity, there is a method in which a low melting point thin film is destroyed by a laser beam used for a write-once optical recording medium to form a low reflectivity pit. Since pits are formed, it takes time and is not suitable for mass production of ROM type optical recording media. [0005] As another method, there is a method by a photo-etching method. In this method, predetermined pits are formed in a silver salt emulsion in advance by a photographic method, a photoresist is applied to a recording medium having a uniform light-reflective thin film, and the pattern of the silver salt emulsion is printed and etched. The thin film is locally etched with a liquid to determine the presence or absence of a light-reflective thin film. Since all data is in a silver salt pit pattern, it can be copied at a time and is suitable for the production of a ROM type optical recording medium. In addition to the above methods, photomechanical methods using the principle of batch duplication have been developed. [0006] However, in the above-mentioned method of collective duplication, a fine pit pattern is optically printed from a photographic master onto a recording medium for duplication, and information by pits is recorded by various post-processing. Therefore, there is a problem that the entire process is long and the probability of generating pit defects is high. In addition, there is a problem that the production cost is high because the production efficiency is relatively low although it is a batch replication. Further, there is a problem that it is difficult to sufficiently increase the yield of non-defective products even if great care is taken to prevent fine dust and the like from being mixed in the manufacturing process. [0007] The present invention has been made to solve the above problems. That is, the invention of claim 1 of the present invention is an optical recording medium which is an optically readable data carrier, wherein the data area of the optical recording medium has a smooth surface portion and reflects light. 1 to 2.0
μm, a pattern of a light scattering surface portion having a regular diffraction grating surface having a depth of 0.05 to 1.0 μm, and a reflection amount of light at the smooth surface portion and the regular diffraction grating portion. An optical recording medium characterized in that a data signal is obtained from the difference. The invention according to claim 3 of the present invention is characterized in that a smooth surface portion and a size corresponding to data recorded on a support are provided. 0.1
The surface of the optical recording medium member is pressed using a master plate in which a pattern with a light scattering surface portion having a regular diffraction grating surface having a thickness of from 2.0 to 2.0 μm and a depth of from 0.05 to 1.0 μm is formed. In the method for manufacturing an optical recording medium in which a master plate pattern is duplicated on an optical recording medium member by creating a data area of the optical recording medium, the master plate is formed on a support having a regular diffraction grating surface. Provide a photosensitive resin layer,
A pattern of a smooth surface portion corresponding to the data and a light scattering surface portion having a regular diffraction grating surface is obtained by exposing a data pattern prepared in advance to the photosensitive resin layer, developing and drying the data pattern. A method of manufacturing an optical recording medium, characterized in that the optical disk is a master plate, wherein the invention has a smooth surface portion corresponding to recorded data and a size of 0.1%. ~ 2.0μ
m, a pattern with a light scattering surface portion having a regular diffraction grating surface having a depth of 0.05 to 1.0 μm is duplicated on a metal plate, and the metal plate is used as a mold by an injection method. A method for manufacturing an optical recording medium, characterized by duplicating a data area of the optical recording medium, is provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic principle of the present invention is to use, as data recording means, a pattern composed of a smooth surface portion and a light scattering surface portion having a regular diffraction grating surface. The press method was used to duplicate the data on a recording medium. Then, the data recorded on the optical recording medium as described above is not read by the phase difference of the laser light, but the light reflectance on the data area surface composed of a regular diffraction grating portion and a smooth surface portion. Is read by the difference of Hereinafter, the principle and operation of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view of an example of an optical recording medium for illustrating the principle of the optical recording medium. With a pattern corresponding to the data to be recorded in the data area 100 on the substrate 1,
The pattern of the smooth surface portion 2 and the light scattering surface portion 3 whose surface is a regular diffraction grating is formed, and the optical recording medium 20 of the present invention is formed.
Is configured. Further, if necessary, the reflective thin film 4 can be coated on the entire surface of the data area, and on the smooth regular surface of the diffraction grating portion. Although the data area 100 is formed on a part of the substrate 1 in FIG. 1, it may be formed on the entire surface of the substrate 1. FIG. 2 is an enlarged partial cross-sectional view of the data area 100 of FIG. 1 for explaining the trajectory of light when the light scattering surface has minute irregularities. In this optical recording medium, as shown in FIG. 2, when a data area is irradiated with a laser beam 5, regular reflection 6 of the incident light 5 occurs on the smooth surface portion 2, and a large reflected light is obtained from this portion. On the other hand, irregular reflection 7 of the incident light 5 occurs on the light scattering surface portion 3, and only a small reflected light can be obtained from this portion. Therefore, if the photodetector is set at a predetermined position,
The recorded data can be read by detecting the difference in the amount of light reflection from the two portions. The smooth surface portion 2 and the light scattering portion 3 may be on the same plane, and if there is unevenness, whichever may form the convex portion. FIG. 3 is a view for explaining the trajectory of light on the optical recording medium of the present invention when the light scattering surface in FIG. 1 is a diffraction grating. In this optical recording medium, when the laser beam 5 is irradiated, on the smooth surface portion, only the specular reflection 6 at the angle θ occurs in the light 5 incident at the angle θ. On the other hand, in the light scattering surface portion 3 where the diffraction grating is formed, the light 5 incident at an angle θ
Produces a specular reflection 8 at an angle θ and a so-called diffracted light 9 reflected at a specific angle α. (9 in the figure is the first-order diffracted light,
Strictly speaking, the n-th order diffracted light is generated, but the first-order diffracted light is the largest, and the second and lower order diffracted lights are omitted because the intensity is small. Assuming that there is no factor other than diffraction, the ratio of the incident light and the reflected light on the light scattering surface portion 3 where the diffraction grating is formed is approximately the following ratio (considering the good reflective thin film). Incident light: specularly reflected light: diffracted light = 100: 70: 30 Accordingly, the photodetector is set at an incident angle α.
If installed at the position of the angle α, the reflection amount of 100 for the incident light 100 can be obtained from the smooth surface portion 2,
Only a maximum of 70 reflections can be obtained from the light scattering surface portion 3. (Actually, a reflection amount of about 50 is obtained because the n-order diffracted light exists.) That is, data can be read by detecting the difference in the light reflection amount.
Further, if the photodetector is installed in the direction of the angle α of the diffracted light on the light scattering surface portion 3, the reflected light cannot be detected from the smooth surface portion 2. 3
Reflected light of about / 10 light amount can be detected, and data can be read based on this difference. In this case, the ratio of the light reflected from the smooth surface portion 2 and the light reflected from the light scattering surface portion 8 is infinite at the position of the detector, and the S / N ratio becomes the best. Incidentally, also in FIG. 2, it is possible to install the photodetector in a direction of an angle other than the regular reflection angle. However, since light is diffusely reflected in all directions on the light scattering surface portion 3,
Unlike the above-mentioned diffracted light, it has no directivity, the amount of reflected light in a specific direction is small, and it is necessary to take measures such as increasing the sensitivity of the photodetector. In addition, scattered light in many directions may be reflected in the reading device in a complicated manner, resulting in noise. DESCRIPTION OF THE PREFERRED EMBODIMENTS (Master Version) In manufacturing an optical recording medium, first, information to be recorded is converted into a predetermined data format.
This data is input to an apparatus for exposing a data pattern to a photosensitive material to produce a master plate. Next, the photosensitive material is subjected to pattern exposure using a minute spot of white light, laser light, an electron beam, or the like, and then developed and dried according to a standard method to obtain a master plate.
Incidentally, it is naturally possible to produce a mask on which a data pattern is formed without using such an apparatus and to perform pattern exposure on the photosensitive material via the mask. As the photosensitive material, a general high-resolution silver salt emulsion or a photosensitive resin can be used. Here, in the conventional method, in the data exposure, the photosensitive material provided on the substrate is directly exposed and developed to obtain a master plate. In the present invention, however, the photosensitive material is pre-processed by pre-processing. A master plate having a regular diffraction grating shape on the surface of the scattering surface is manufactured. The pretreatment is to form a diffraction grating relief having an appropriate diffraction effect over the entire surface of the master plate substrate. This diffraction grating relief has a grating spacing of 0.1 to 2.0 μ and a depth of 0.05 to 1.0 μ.
Of the degree. The relief of such a diffraction grating is obtained by recording the interference fringes of two light beams on a photosensitive material using mechanical precision cutting, etching, precision processing by an electron beam, or holography on the substrate surface. be able to. In this diffraction grating, if the grating interval is constant,
The diffraction angle φ varies depending on the wavelength of light, and if the wavelength of light is constant, the diffraction angle φ varies depending on the lattice spacing.
This relationship is shown by the following equation. λ = d (sin ω + sin φ) λ: wavelength, d: grating interval, ω: incident angle, φ: diffraction angle In general, the wavelength of light used for reading data is determined, and a predetermined diffraction angle φ is obtained by the above method. It is good to determine the lattice spacing for the. Here, when a diffraction grating is produced by using holography, the diffraction grating to be recorded is recorded as a smooth black-and-white lattice if the photosensitive material to be used is a silver halide photographic material, and fine relief is used if it is a photoresist. Is recorded as Since the master plate substrate of the present invention must have fine relief, a smooth black-and-white lattice made of a silver halide photographic material must be printed on a photosensitive material or the like applied to another substrate to produce a new fine relief. Must. In this step, a defect is likely to occur in the grating due to dust or duplication means, and the number of steps itself increases. Therefore, a method of recording a diffraction grating directly on a photoresist is preferable. Next, a photosensitive resin is applied to the master plate substrate surface having the regular diffraction grating relief produced as described above. As the photosensitive resin, those commonly used can be widely used, and may be either a negative type or a positive type. For example, a photosensitive resin for semiconductor production is used. The photosensitive resin on the master plate substrate surface is exposed, developed, and dried by the above-described apparatus for exposing the data pattern or through a mask on which the data pattern is formed, and FIG. Master version 30
Can be obtained. The master plate 30 has a smooth surface portion 12 in which a diffraction grating relief formed on a support 10 is covered with a photosensitive resin film 11 having a pit pattern shape of copied data.
And a portion 13 where the diffraction grating relief is exposed.
Then, the smooth surface portion 1 covered with the photosensitive resin film 11
2 and the portion 13 where the diffraction grating relief is exposed, that is, a data pattern to be recorded is formed by the presence or absence of the diffraction grating. Using this master plate, the data pattern recorded depending on the presence or absence of the diffraction grating can be transferred to the base material of the optical recording medium and duplicated. However, when mass production is intended, the master plate can be replaced with the submaster plate. It is preferable to prepare and use. (Sub-master plate) The sub-master plate is manufactured by the following steps: (1) A curable resin having an appropriate viscosity is applied to the master plate surface and cured, and the substrate for the sub-master plate is bonded to the surface with an adhesive. Then, a sub-master plate in which the pattern of the diffraction grating is duplicated by being separated from the master plate can be obtained. Incidentally, if the adhesiveness between the cured resin and the sub master plate is good, it is not necessary to use an adhesive. As curing resin, heat curing, light curing,
Although a reactive curing resin is used, a resin having a small shrinkage ratio at the time of curing, not generating a reaction product such as gas, and having a high curing strength is preferable in order to duplicate a diffraction grating. (2) A submaster plate can be obtained by applying a thermoplastic resin to the substrate for the submaster plate in advance and pressing the master plate against this surface in a heated state to duplicate the diffraction grating on the substrate for the submaster plate. (3) After the master plate has been sufficiently washed, electroless plating is performed to form a metal thin film, and then electroplating is further performed.
After a metal film is formed on the metal film layer to obtain a required thickness, the metal film is peeled off from the master plate to obtain a metallic submaster plate. As the activating liquid, for example, a liquid mainly containing palladium chloride is used, and as the plating metal, for example, nickel is used. This metal submaster plate has good reproducibility of a regular diffraction grating and high durability and strength. (Manufacture of Optical Recording Medium) An optical recording medium is manufactured using the master plate or sub-master plate obtained as described above. (1) In the case of small-scale production, a curable resin having an appropriate viscosity is applied to the master plate surface and cured, and an optical recording medium substrate is adhered to the surface with an adhesive, and is separated from the master plate to form a diffraction grating. An optical recording medium in which the pattern is duplicated in the data area can be obtained. still,
As long as the adhesiveness between the cured resin and the optical recording medium substrate is good, an adhesive need not be used. As cured resin, thermosetting,
Light-curing or reactive-curing resins are used. However, in order to duplicate the diffraction grating, it is preferable to use a resin having a small shrinkage at the time of curing, generating no reaction products such as gas, and having high curing strength. As the substrate, general plastics, for example, films, sheets and plates of vinyl chloride, polycarbonate, acryl, polymethyl methacrylate and the like are used. (It is not limited to transparency), and the thickness is not particularly limited. Further, in order to increase the reflectance, a reflective thin film layer can be formed in a data area where the pattern of the diffraction grating is duplicated by means such as coating, plating, vapor deposition, and sputtering. Examples of the material for forming the reflective thin film include metals such as Al, metal compounds, alloys, chalcogens, chalcogen compounds, inorganic substances, and organic substances. (2) In the case of mass production After forming a resin layer, preferably a thermoplastic resin layer on a substrate for an optical recording medium, the above-obtained sub-master plate is hot-pressed onto a data area to form a regular pattern. It is possible to obtain an optical recording medium in which a simple diffraction grating pattern is duplicated in the data area. The resin layer in which the pattern is duplicated has excellent storability, durability and physical properties when cured by heat or light. The above-mentioned substrate is used as the substrate, and a reflective thin film can be formed in the data area. After forming a resin layer, preferably a thermoplastic resin layer, on an optical recording medium substrate, a reflective thin film layer is formed by the above-described method, and a reflective thin film layer is formed in advance in a data area. Next, the sub-master plate obtained above is hot-pressed on the reflective thin film layer surface of this data area and the pattern of the diffraction grating is duplicated to obtain an optical recording medium in which the pattern of the diffraction grating is duplicated in the data area. be able to. In this case, since the surface strength is increased due to pressure bonding from the reflective thin film layer surface, it is preferable to use a metal submaster plate having durability. The above-mentioned substrate is used as the substrate, and a reflective thin film can be formed in the data area. The above-mentioned metallic submaster plate is used as a mold, or an injection mold is prepared separately.
By using this, an optical recording medium in which the diffraction grating pattern is duplicated in the data area can be obtained by injection. In the optical recording medium of the present invention obtained as described above, a protective layer for protecting the data area surface from abrasion, adhesion of dust and the like can be formed. This protective layer is formed by uniformly applying a light transmissive (not limited to visual transparency) resin or by laminating a film or sheet having such optical properties, and has a thickness of 0.1.
mm to 1.0 mm, but 0.4 mm to 0.6 m
In the case of m, the optical card as an example of the optical recording medium of the present invention is suitable for preventing erroneous reading due to adhesion of dust or dirt. An acrylic resin or a polycarbonate resin is preferably used as the light-transmitting resin, and a film or sheet made of such a resin is suitably used as the film or sheet. In the above method, if the substrate is a light-transmitting film or sheet, the light-transmitting protective layer does not need to be particularly used. For example, a printed opaque plastic film is used. , A sheet can be used. The optical recording medium of the present invention having the basic structure as described above can be used as a flexible disk, card, tape, or the like, and is applied to, for example, the following uses. (1) Financial distribution industry: cash card, credit card, prepaid card. (2) Medical health industry: health certificate, medical chart, medical card,
Emergency card. (3) Entertainment industry: software media, membership cards, admission tickets, game machine control media, video game media. (4) Transportation travel industry: tourist cards, licenses, commuter passes,
passport. (5) Publishing industry: electronic publishing. (6) Information processing industry: external recording devices and filing of electronic machines. (7) Education industry: Teaching material programs, grade management cards, library access control and book management. (8) Automobile industry: maintenance records, operation management. (9) FA: Program recording medium such as MC, NC, robot, etc. (10) Other: building control, home control, ID card, vending machine medium, cooking card. According to the optical recording medium of the present invention, the data is read by the difference in the light reflectance between the smooth surface portion and the light scattering portion having a regular diffraction grating as data pits. A simpler reading device can be used as compared with a conventional complicated and precise reading device used for reading data using a phase difference of light, in which conventional data pits are simply recorded as unevenness. Further, a data pattern composed of a pattern of a smooth surface portion and a light scattering portion having a regular diffraction grating can be copied by a press method or an injection method that is easy to mass-produce. Further, since the minute irregularities are formed by the diffraction grating, the pit can be detected by the presence or absence of light by installing the photodetector in the direction of the diffracted light. Reading is facilitated and reading accuracy is improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of an example of an optical recording medium for illustrating the principle of the optical recording medium. FIG. 2 is an enlarged partial cross-sectional view of a data area 100 of FIG. 1 for explaining a trajectory of light when a light scattering surface portion of FIG. 1 has minute irregularities. FIG. 3 is a diagram illustrating the trajectory of light on the optical recording medium of the present invention when the light scattering surface portion in FIG. 1 is a diffraction grating. FIG. 4 is an enlarged partial sectional view of a master plate used in the present invention. DESCRIPTION OF SYMBOLS 1 Substrate 2 of optical recording medium 2, 12 Smooth surface portion 3 Light scattering surface portion 4 Light reflective thin film 5 Incident light 6 Regular reflection 7 Diffuse reflection 8 Light scattering surface portion 9 Diffracted light 10 Support 11 Photosensitive resin Reference Signs List 20 optical recording medium 30 master version 100 data area

Claims (1)

(57) [Claims] An optical recording medium which is an optically readable data carrier, wherein a data area of the optical recording medium reflects light with a smooth surface portion, a size of 0.1 to 2.0 μm, and a depth of 0.0.
A data signal is obtained by a difference in the amount of light reflection between the smooth surface portion and the regular diffraction grating portion, which is composed of a pattern of a light scattering surface portion having a regular diffraction grating surface of 5 to 1.0 μm. An optical recording medium characterized by the above-mentioned. 2. 2. The optical recording medium according to claim 1, wherein the data area is covered with a light-reflective thin film. 3. A smooth surface portion and a size of 0.1 to 2.0 μm and a depth of 0.05 to 1.0 corresponding to data recorded on the support.
Using a master plate in which a pattern with a light scattering surface portion having a regular diffraction grating surface made of μm is formed, the master plate pattern is pressed onto the optical recording medium member by pressing the surface of the optical recording medium member. In the method for manufacturing an optical recording medium for duplicating a data area of an optical recording medium, the master plate is provided with a photosensitive resin layer on a support having a regular diffraction grating surface. A master plate in which a pattern of a smooth surface portion corresponding to data and a light scattering surface portion having a regular diffraction grating surface is formed by exposing, developing, and drying a data pattern prepared in advance. A method for manufacturing an optical recording medium, comprising: 4. 4. A light-reflective thin film is formed after duplicating a pattern of a master plate on an optical recording medium member.
The manufacturing method of the optical recording medium according to the above. 5. A pattern of a smooth surface portion corresponding to data to be recorded and a light scattering surface portion having a regular diffraction grating surface having a size of 0.1 to 2.0 μm and a depth of 0.05 to 1.0 μm is formed on a metal plate. And a data area of the optical recording medium is duplicated by an injection method using the metal plate as a mold.