JP2006040440A - Image recording method to optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image recording method by which a visible image having excellent contrast can be recorded by using a laser beam to an optical disk provided with an image recording layer on a label surface. <P>SOLUTION: The image recording method to the optical disk provided with the image recording layer in which the visible image is recorded on the label surface by irradiation with the laser beam is characterized in that the image recording layer has a guide groove for tracking in an image recording region, tracking is performed on both groove and land of the guide groove, and recording is performed on the groove and the land. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image recording method for forming a visible image on an optical disc capable of recording a visible image on a label surface (surface opposite to the recording surface).

  Conventionally, an optical disc (optical disc) capable of recording information only once by laser light is known. This optical disk is also called a recordable CD (so-called CD-R), and its typical structure is a recording layer made of an organic dye on a transparent disk-shaped substrate, a light reflecting layer made of a metal such as gold, and a resin. A protective layer made of a metal is provided in this order in a laminated state. Information recording on this CD-R is performed by irradiating the CD-R with a near-infrared laser beam (usually a laser beam having a wavelength near 780 nm), and the irradiated portion of the recording layer emits the light. Information is recorded by absorbing and locally raising the temperature, causing a physical or chemical change (eg, pit generation) and changing its optical properties. On the other hand, reading (reproduction) of information is also performed by irradiating a laser beam having the same wavelength as that of the recording laser beam. Information is reproduced by detecting the difference in reflectance from (part).

  In recent years, optical discs with higher recording density have been demanded. In response to such a demand, an optical disk called a recordable digital vasatile disk (so-called DVD-R) has been proposed. This DVD-R is a transparent disk-shaped substrate in which the guide groove (pre-groove) for tracking the irradiated laser beam is narrower than half of the CD-R (0.74-0.8 μm). On top of that, a recording layer made of a dye, and usually two light reflecting layers on the recording layer, and further a protective layer provided if necessary, or a disk-shaped protective substrate having the same shape as the disk The recording layer has a structure in which the recording layer is bonded inside with an adhesive. Information recording / reproduction on a DVD-R is performed by irradiating visible laser light (usually laser light having a wavelength in the range of 630 nm to 680 nm), and recording at a higher density than CD-R is possible. Has been.

  By the way, in the various optical discs described above, the music title of the music data recorded on the recording surface and the recorded data are identified on the surface (label surface) opposite to the recording surface on which the music data is recorded. There is known a label on which visible information such as a title is attached. Such an optical disc is produced by printing a title or the like on a circular label sheet in advance by a printer or the like and sticking the label sheet on the label surface of the optical disc.

  As described above, when an optical disc in which a desired visible image such as a title is recorded on the label surface is manufactured, a printer is required separately from the optical disc drive. Therefore, after recording on a recording surface of an optical disk using an optical disk drive, the optical disk is taken out from the optical disk drive, and a label sheet printed by a separately prepared printer as described above is attached. Need to do work. In addition, the method of applying a label sheet peels off during use due to durability problems such as adhesives, and the unbalance during rotation of the optical disk increases due to misalignment during lamination, resulting in recording and playback. May not be possible.

In view of this, an optical recording medium has been proposed in which a laser marker is used on the label surface and the contrast between the surface and the background can be changed (for example, see Patent Document 1). Such a recording medium can perform desired image recording on the label surface of the optical disk by an optical disk drive without separately preparing a printer or the like. However, the optical recording medium described in Patent Document 1 has low sensitivity, and a high-power gas laser such as a carbon dioxide gas laser must be used, and a visible image formed by the laser light as described above has a contrast. Was low and inferior in visibility.
On the other hand, a recording medium having a visible image forming layer capable of recording visible information with laser light has also been proposed (see, for example, Patent Document 2). This recording medium has a feature that a visible image can be formed by a low-power laser irradiation without adversely affecting the medium or electronic information recorded on the medium.
In such a recording medium capable of recording visible information on the label surface, there is an increasing demand for improving the visibility of the formed visible image, but for a method for forming a visible image having a sufficiently excellent contrast, The current situation has not yet been obtained.
JP-A-11-66617 JP 2004-103180 A

This invention is made | formed in view of the above conventional trouble, and makes it a subject to achieve the following objectives. That is,
An object of the present invention is to provide an image recording method capable of recording a visible image having excellent contrast by using laser light for an optical disc having an image recording layer (visible image forming layer) on a label surface. It is in.

Means for solving the problems are as follows. That is,
An image recording method for an optical disc of the present invention is an image recording method for an optical disc provided with an image recording layer on a label surface on which a visible image is recorded by laser light irradiation.
The image recording layer has a guide groove for tracking in an image recording area, tracks both the groove and land of the guide groove, and records on the groove and land.

  ADVANTAGE OF THE INVENTION According to this invention, the image recording method which can record the visible image which has the excellent contrast using a laser beam with respect to the optical disk provided with the image recording layer in the label surface can be provided.

The image recording method for the optical disc of the present invention will be described below.
An image recording method for an optical disc of the present invention is an image recording method for an optical disc provided with an image recording layer on a label surface on which a visible image is recorded by laser light irradiation.
The image recording layer has a guide groove for tracking in an image recording area, tracks both the groove and land of the guide groove, and records on the groove and land.
First, an optical disk used in the present invention will be described.

The optical disk used in the present invention needs to have an image recording layer on the label surface on which a visible image is recorded by laser light irradiation.
The type of such an optical disk may be any of a reproduction-only (read-only) type, a write-once type, a rewritable type, etc., but is preferably a write-once type. The recording format is not particularly limited, such as a phase change type, a magneto-optical type, and a dye type, but is preferably a dye type.

Examples of the layer configuration of the optical disc in the present invention include the following configurations.
(1) The recording layer, the reflective layer, and the protective layer are sequentially formed on the substrate, and the image recording layer and the dummy substrate are sequentially provided on the protective layer.
(2) The recording layer, the reflective layer, and the adhesive layer are sequentially formed on the substrate, and the image recording layer and the dummy substrate are sequentially provided on the adhesive layer.
(3) The recording layer, the reflective layer, the protective layer, and the adhesive layer are sequentially formed on the substrate, and the image recording layer and the dummy substrate are sequentially provided on the adhesive layer.
(4) The recording layer, the reflective layer, the protective layer, the adhesive layer, and the protective layer are sequentially formed on the substrate, and the image recording layer and the dummy substrate are sequentially provided on the protective layer.
(5) The recording layer, the reflective layer, the protective layer, the adhesive layer, the protective layer, and the reflective layer are sequentially formed on the substrate, and the image recording layer and the dummy substrate are sequentially provided on the reflective layer.
(6) The recording layer, the reflective layer, the adhesive layer, and the reflective layer are sequentially formed on the substrate, and the image recording layer and the dummy substrate are sequentially provided on the reflective layer.
The layer configurations of (1) to (6) are merely examples, and the layer configuration is not limited to the order described above, and a part of the layer configuration may be replaced or a part of the layer configuration may be omitted. . For example, each layer may be composed of one layer or a plurality of layers.
Hereinafter, each component will be described.

[substrate]
The substrate of the optical disk in the present invention can be arbitrarily selected from various materials used as a substrate of a conventional optical disk.
Examples of substrate materials include acrylic resins such as glass, polycarbonate, and polymethyl methacrylate, vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers, epoxy resins, amorphous polyolefins, and polyesters. You may use them together.
These materials can be used as a film or as a rigid substrate. Among the above materials, polycarbonate is preferable from the viewpoint of moisture resistance, dimensional stability, price, and the like.

  The thickness of the substrate may be determined according to the layer structure of the optical disc, and is generally preferably 0.1 to 1.2 mm, and more preferably 0.2 to 1.1 mm.

The substrate is provided with irregularities (pregrooves) representing information such as tracking guide grooves or address signals.
When the optical disk of the present invention has a CD-R or CD-RW configuration, the pregroove track pitch is preferably in the range of 1.2 to 2.0 μm, and preferably in the range of 1.4 to 1.8 μm. Is more preferable, and a range of 1.55 to 1.65 μm is even more preferable.
The depth of the pregroove (groove depth) is preferably in the range of 100 to 250 nm, more preferably in the range of 150 to 230 nm, and still more preferably in the range of 170 to 210 nm.
The half width of the pregroove is preferably in the range of 400 to 650 nm, more preferably in the range of 480 to 600 nm, and still more preferably in the range of 500 to 580 nm.

When the optical disc of the present invention has a DVD-R or DVD-RW configuration, the track pitch of the pregroove is preferably in the range of 300 to 900 nm, more preferably in the range of 350 to 850 nm, and 400 to 800 nm. More preferably, it is set as the range.
The pregroove depth (groove depth) is preferably in the range of 100 to 160 nm, more preferably in the range of 120 to 150 nm, and still more preferably in the range of 130 to 140 nm.
Furthermore, the groove width (half width) of the pregroove is preferably in the range of 200 to 400 nm, more preferably in the range of 230 to 380 nm, and still more preferably in the range of 250 to 350 nm.

In order to achieve a higher recording density, a substrate on which a pre-groove having a narrower track pitch than a conventional CD-R or DVD-R may be used.
In this case, the track pitch of the pregroove is preferably in the range of 200 to 400 nm, and more preferably in the range of 250 to 350 nm.
Further, the depth of the pregroove (groove depth) is preferably in the range of 20 to 150 nm, and more preferably in the range of 50 to 100 nm.
Furthermore, the groove width (half-value width) of the pregroove is preferably in the range of 50 to 250 nm, and more preferably in the range of 100 to 200 nm.
In addition, the groove inclination angle of the pregroove is preferably in the range of 20 to 80 °, and more preferably in the range of 30 to 70 °.

Further, an undercoat layer is provided on the surface of the substrate on which the recording layer is provided (the surface on which the pregroove is formed) for the purpose of improving the flatness, improving the adhesive force, and preventing the recording layer from deteriorating. Also good.
Examples of the material for the undercoat layer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleic anhydride copolymer, polyvinyl alcohol, N-methylol acrylamide, styrene / vinyl toluene copolymer, chlorosulfone. Polymer materials such as chlorinated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, polyethylene, polypropylene, polycarbonate; and silane coupling And a surface modifier such as an agent. The undercoat layer is formed by dissolving or dispersing the above substances in a suitable solvent to prepare a coating solution, and then applying this coating solution to the substrate surface by a coating method such as spin coating, dip coating, or extrusion coating. can do.
The thickness of the undercoat layer is generally in the range of 0.005 to 20 μm, preferably in the range of 0.01 to 10 μm.

[Recording layer]
The recording layer is a layer on which code information (encoded information) such as digital information is recorded, and examples thereof include a dye type, a write-once type, a phase change type, and a magneto-optical type. Preferably there is.

Specific examples of the dye contained in the dye-type recording layer include a cyanine dye, an oxonol dye, a metal complex dye, an azo dye, and a phthalocyanine dye.
JP-A-4-74690, JP-A-8-127174, 11-53758, 11-334204, 11-334205, 11-334206, 11-334207 No. 2000-43423, 2000-108513, 2000-158818, and the like are preferably used.
Further, as recording materials, organic compounds such as triazole compounds, triazine compounds, cyanine compounds, merocyanine compounds, aminobutadiene compounds, phthalocyanine compounds, cinnamic acid compounds, viologen compounds, azo compounds, oxonol benzoxazole compounds, and benzotriazole compounds are also included. Preferably used. Among these compounds, cyanine compounds, aminobutadiene compounds, benzotriazole compounds, and phthalocyanine compounds are particularly preferable.

The recording layer can be formed by a method such as vapor deposition, sputtering, CVD, or solvent coating, but solvent coating is preferred.
When solvent coating is used, the recording layer is prepared by dissolving a recording substance such as a dye in a solvent together with a quencher, a binder and the like to prepare a coating solution. After forming, it is formed by drying. The concentration of the recording substance in the coating solution is generally in the range of 0.01 to 15% by mass, preferably in the range of 0.1 to 10% by mass, more preferably in the range of 0.5 to 5% by mass, and most preferably. Is in the range of 0.5-3 mass%.

Examples of the solvent of the coating solution include esters such as butyl acetate, ethyl lactate and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane and chloroform; dimethylformamide and the like Amides; Hydrocarbons such as methylcyclohexane; Ethers such as dibutyl ether, diethyl ether, tetrahydrofuran, dioxane; Alcohols such as ethanol, n-propanol, isopropanol, n-butanol, diacetone alcohol; 2,2,3,3-tetra Fluorinated solvents such as fluoropropanol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, etc. And the like can be mentioned recall ethers.
The said solvent can be used individually or in combination of 2 or more types in consideration of the solubility of the pigment | dye to be used. Various additives such as an antioxidant, a UV absorber, a plasticizer, and a lubricant may be further added to the coating solution depending on the purpose.

  When a binder is used, examples include natural organic polymer materials such as gelatin, cellulose derivatives, dextran, rosin and rubber; and hydrocarbon resins such as polyethylene, polypropylene, polystyrene and polyisobutylene; polyvinyl chloride, Vinyl resins such as polyvinylidene chloride and polyvinyl chloride / polyvinyl acetate copolymers; acrylic resins such as polymethyl acrylate and polymethyl methacrylate; polyvinyl alcohol, chlorinated polyethylene, epoxy resins, butyral resins, rubber derivatives, Examples thereof include synthetic organic polymers such as initial condensates of thermosetting resins such as phenol / formaldehyde resins.

  When a binder is used in combination as a material for the recording layer, the amount of the binder used is generally in the range of 0.01 to 50 times the mass of the dye, preferably 0.1 to 5 times the amount. Is in range.

  Examples of the solvent application method include a spray method, a spin coating method, a dip method, a roll coating method, a blade coating method, a doctor roll method, and a screen printing method. The recording layer may be a single layer or a multilayer. The thickness of the recording layer is generally in the range of 10 to 500 nm, preferably in the range of 15 to 300 nm, and more preferably in the range of 20 to 150 nm.

  The recording layer can contain various anti-fading agents in order to improve the light resistance of the recording layer. As the anti-fading agent, a singlet oxygen quencher is generally used. As the singlet oxygen quencher, those described in publications such as known patent specifications can be used. Specific examples thereof include JP-A Nos. 58-175893, 59-31194, 60-18387, 60-19586, 60-19588, 60-35054, 60-36190, 60-36191, 60-44554, 60-44555, 60-44389, 60-44390, 60-54892, 60-47069, 68-209995, JP Listed in publications such as Nos. 4-25492, 1-38680, and 6-26028, German Patent No. 350399, and the Chemical Society of Japan, October 1992, page 1141 Can do.

  The amount of the anti-fading agent such as the singlet oxygen quencher used is usually in the range of 0.1 to 50% by mass, preferably in the range of 0.5 to 45% by mass, more preferably , In the range of 3 to 40% by mass, particularly preferably in the range of 5 to 25% by mass.

Specific examples of the material constituting the phase change recording layer include Sb—Te alloy, Ge—Sb—Te alloy, Pd—Ge—Sb—Te alloy, Nb—Ge—Sb—Te alloy, Pd—Nb—. Ge—Sb—Te alloy, Pt—Ge—Sb—Te alloy, Co—Ge—Sb—Te alloy, In—Sb—Te alloy, Ag—In—Sb—Te alloy, Ag—V—In—Sb—Te Alloys, Ag-Ge-In-Sb-Te alloys, and the like. Among these, Ge—Sb—Te alloy and Ag—In—Sb—Te alloy are preferable because they can be rewritten many times.
The layer thickness of the phase change recording layer is preferably 10 to 50 nm, and more preferably 15 to 30 nm.
Such a phase change recording layer can be formed by vapor phase thin film deposition methods such as sputtering and vacuum deposition.

[Reflective layer]
A reflective layer may be provided adjacent to the recording layer for the purpose of improving reflectivity during information reproduction. The light-reflective substance that is the material of the reflective layer is a substance having a high reflectivity with respect to laser light. Examples thereof include Mg, Se, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W. , Mn, Re, Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Si, Ge, Te, Pb, Po, Sn, Bi Mention may be made of metals such as metals and metalloids or stainless steel. These substances may be used alone or in combination of two or more or as an alloy. Among these, Cr, Ni, Pt, Cu, Ag, Au, Al, and stainless steel are preferable. Particularly preferred are Au, Ag, Al or alloys thereof, and most preferred is Ag, Al or alloys thereof. The reflective layer can be formed on the substrate or the recording layer, for example, by vapor deposition, sputtering or ion plating of the light reflective material. The thickness of the reflective layer is generally in the range of 10 to 300 nm, and preferably in the range of 50 to 200 nm.

[Adhesive layer]
The adhesive layer is an arbitrary layer formed in order to improve the adhesion between the reflective layer and the dummy substrate.
As a material constituting the adhesive layer, a photo-curing resin is preferable, and in particular, a material having a small curing shrinkage rate is preferable in order to prevent the disk from warping. Examples of such a photocurable resin include UV curable resins (UV curable adhesive) such as “SD-640” and “SD-347” manufactured by Dainippon Ink and Chemicals, Inc. it can. The thickness of the adhesive layer is preferably in the range of 1 to 1000 μm, more preferably in the range of 5 to 500 μm, and particularly preferably in the range of 10 to 100 μm in order to give elasticity.

[Protective layer]
The optical disk according to the present invention may be provided with a protective layer for the purpose of physically and chemically protecting the reflective layer and the recording layer.
In the case of adopting the same form as that for the manufacture of the DVD-R type optical disk, that is, a structure in which two substrates (including one of which is a dummy substrate) are bonded with the recording layer inside, the protective layer is not necessarily provided. This is not necessary.

Examples of materials used for the protective layer include inorganic substances such as ZnS, ZnS—SiO ₂ , SiO, SiO ₂ , MgF ₂ , SnO ₂ , and Si ₃ N ₄ , thermoplastic resins, thermosetting resins, and UV curable materials. Organic substances such as resins can be mentioned. The protective layer can be formed, for example, by laminating a film obtained by extrusion of plastic on the reflective layer via an adhesive. Moreover, you may provide by methods, such as vacuum evaporation, sputtering, and application | coating.

  In the case of a thermoplastic resin or a thermosetting resin, it can also be formed by dissolving these in a suitable solvent to prepare a coating solution, and then applying and drying the coating solution. In the case of a UV curable resin, it can also be formed by applying this coating solution and curing it by irradiation with UV light. In these coating liquids, various additives such as an antistatic agent, an antioxidant and a UV absorber may be further added according to the purpose. The thickness of the protective layer is generally in the range of 0.1 μm to 1 mm.

[Image recording layer]
As described above, the optical disk according to the present invention needs to have an image recording layer on the label surface.
Visible images (visible information) desired by the user, such as characters, graphics, and patterns, are recorded on the image recording layer by laser light. Examples of visible images include disc titles, content information, content thumbnails, related patterns, design patterns, copyright information, recording date, recording method, recording format, and the like.

  Here, the visible image recorded in the image recording layer means a visually recognizable image, and includes all visually recognizable information such as characters (columns), designs, and figures. Also, as character information, usable person designation information, use period designation information, usable number designation information, rental information, resolution designation information, layer designation information, user designation information, copyright holder information, copyright number information, manufacturing Information, manufacturer date information, sale date information, dealer or seller information, use set number information, region designation information, language designation information, application designation information, product user information, use number information, and the like.

  The image recording layer only needs to be able to record image information such as characters, images, and patterns by laser irradiation so that the recording material is a recording material (pigment or phase change recording material) described later in the recording layer. ) Can be suitably used.

In the optical disc of the present invention, the constituent components of the recording layer (recording substance: dye or phase change recording material) described later and the constituent components of the image recording layer may be the same or different. Since the required characteristics differ between the recording layers, it is preferable that the constituent components are different. Specifically, the constituent components of the recording layer are preferably excellent in recording / reproducing characteristics, and the constituent components of the image recording layer are preferably those in which the contrast of the recorded visible image is high.
In particular, when a dye is used as a component of the image recording layer, a cyanine dye, a phthalocyanine dye, an azo dye, an azo metal complex, or an oxonol dye is used among the dyes described later from the viewpoint of improving the contrast of a recorded image. It is preferable.
Further, one of the recording layer and the image recording layer may be a phase change type and the other may be a dye type. In this case, the recording layer is preferably a phase change type and the image recording layer is preferably a dye type.

  The image recording layer can be formed by preparing a coating solution by dissolving a dye described later in a solvent and coating the coating solution. As the solvent, the same solvents as those used for preparing the recording layer coating liquid described later can be used. Other additives and coating methods can be carried out in the same manner as the recording layer described later.

  The thickness of the image recording layer is preferably 0.01 to 200 μm, more preferably 0.05 to 100 μm, and still more preferably 0.1 to 50 μm.

The optical disk according to the present invention has a guide groove for tracking in the image recording layer.
In the above layer configuration example, since the image recording layer is formed adjacent to the dummy substrate, the guide groove can be easily provided in the image recording layer by providing a desired groove in the dummy substrate. Since it has an image recording layer in which a guide groove for tracking is formed in this way, the optical disc in the present invention can perform image recording in a state where the laser pickup is tracked by the guide groove, and the position of the pickup is precisely controlled. Therefore, a precise image can be recorded.
Further, by providing the guide groove in the image recording layer, there is an effect that the light interferes and the surface looks like a beautiful rainbow color.

  The shape of the guide groove of the image recording layer is preferably a spiral shape or a concentric shape since tracking is performed while the optical disk is rotated.

  The guide groove shape of the image recording layer can be different from the guide groove shape (pre-groove shape) of the recording layer. Further, the pitch of the guide grooves of the image recording layer and the pitch of the guide grooves of the recording layer can be made different. Specifically, the pitch of the guide grooves of the image recording layer can be made wider than the guide grooves of the recording layer. Since tracking in image recording is the purpose, it is only necessary to be able to record a densely visible image, and it is not necessary to narrow the pitch as the recording layer that narrows the guide groove pitch (track pitch) in order to increase the recording density. It is.

From the viewpoint of the intensity distribution of the recording laser, the pitch of the tracking guide grooves formed in the image recording area of the image recording layer is preferably 0.3 to 2.0 μm, and preferably 0.4 to 1.6 μm. It is more preferable that the thickness be 0.6 to 1.0 μm.
Further, the depth of the guide groove is preferably 50 to 200 nm, more preferably 80 to 150 nm, and still more preferably 100 to 130 nm.
Furthermore, the width of the guide groove is preferably 100 to 600 nm, more preferably 200 to 500 nm, and still more preferably 250 to 450 nm.

In addition, from the viewpoint of improving the contrast of the formed visible image, the ratio of the land portion to the groove portion (land / groove) of the guide groove is preferably in the range of 0.5 to 1.5, A range of 0.7 to 1.3 is more preferable, and a range of 0.8 to 1.2 is still more preferable.
Here, the ratio of the land portion to the groove portion refers to the ratio of the half width of the land portion to the half width of the groove portion.

[Dummy substrate]
For the dummy substrate in the present invention, the same resin material as that of the aforementioned substrate can be used.

As another layer configuration of the optical disc in the present invention, for example, a reflective layer, a recording layer, and a cover layer may be sequentially formed on a substrate, and an image recording layer may be provided on the back surface of the substrate.
In this configuration, the components other than the cover layer are as described above.

[Cover layer]
The cover layer is formed in order to prevent the inside of the optical disk from impact and the like, and is preferably provided on the recording layer via an adhesive layer. The material constituting the cover layer is not particularly limited as long as it is a transparent material, but is preferably polycarbonate, cellulose triacetate, or the like, and more preferably has a moisture absorption rate of 5% or less at 23 ° C. and 50% RH. It is a material.
“Transparent” means that the recording light and the reproduction light are so transparent that the light is transmitted (transmittance: 90% or more).

  The cover layer can be provided as follows, for example. After preparing a coating solution by dissolving the photocurable resin in a suitable solvent, the coating solution is applied onto the recording layer at a predetermined temperature to form a coating film. On the coating film, a transparent sheet (for example, It is formed by laminating a cellulose triacetate film (TAC film) obtained by plastic extrusion and irradiating light on the laminated TAC film to cure the coating film. The TAC film preferably contains an ultraviolet absorber. The thickness of the transparent sheet is in the range of 0.01 to 0.2 mm, preferably in the range of 0.03 to 0.1 mm, and more preferably in the range of 0.05 to 0.095 mm.

In addition, a polycarbonate sheet etc. can also be used as said transparent sheet. Here, the above-mentioned adhesive layer is not necessary in the case where an adhesive is applied to the bonding surface of the transparent sheet.
Moreover, you may form the light transmissive layer which consists of ultraviolet curable resin etc. instead of a cover layer.

  Further, a hard coat layer may be formed on the cover layer. The hard coat layer can be formed on the substrate by forming a reflective layer, a recording layer, or the like, forming a cover layer thereon, and then applying the cover layer on the cover layer. When the cover layer is a transparent sheet, before the transparent sheet is laminated on the recording layer, a hard coat layer is formed on the transparent sheet so that the hard coat layer is the outermost surface, and a transparent sheet is formed. The optical disk of the present invention may be produced by laminating on the recording layer.

  As described above, the optical disk according to the present invention may have a recording layer that can be recorded / reproduced by laser light, and as described above, a recording unit in which information that can be reproduced by laser light is recorded. A so-called read-only optical disc having (pits) may be used.

(Image recording method)
In the present invention, the image recording on the image recording layer of the optical disc is performed by tracking both the groove and land of the guide groove provided in the image recording layer. Here, image recording with respect to the image forming layer is performed by irradiating the image recording layer with laser light to form recording pits to express a color tone difference between the recording part and the non-recording part.
In this image recording, for example, when recording pits are formed only on the groove of the image recording layer, the image recording layer on the adjacent land remains, so that the color tone difference between the recording part and the non-recording part is lowered. However, by using the method of tracking both the groove and land of the guide groove formed in the image recording layer and forming the recording pit in both the groove and land as in the present invention, the recording portion / non-recording As a result, the color tone difference of the portion increases and the contrast can be improved.

In the image recording method of the present invention, the recording power can be made different between the case where the land is recorded with tracking and the case where the land is recorded with tracking. At this time, the recording power to the land / the recording power to the groove is preferably in the range of 0.7 to 1.2, and more preferably in the range of 0.8 to 1.1.
Further, when recording, it is possible to use a method in which either land or groove is tracked and recorded on the entire surface, and then the other is tracked and recorded on the entire surface again. It is also possible to use a method of recording by alternately tracking grooves and lands every time.
The conditions for image recording can be the same as the conditions for information recording to be described later. For example, the power of laser light at the time of image recording is the same as that at the time of information recording to be described later.

Specifically, the image recording method as described above can be performed using the optical disc of the present invention and a recording apparatus capable of recording image information on at least the image recording layer of the optical disc.
Hereinafter, a recording apparatus used for recording on an optical disc in the present invention will be described first.

  In the optical disc of the present invention, recording of an image on the image recording layer and recording of optical information on the recording layer can be performed by one optical disc drive (recording apparatus) having a recording function on both layers. When one optical disk drive is used as described above, after recording on one of the image recording layer and the recording layer, it can be turned over and recording can be performed on the other layer. Examples of the optical disc drive having a function of recording a visible image on the image recording layer are described in JP2003-203348A, JP2003-242750A, and the like.

  A recording apparatus that records optical information on a recording layer and records a visible image on an image recording layer includes at least a laser pickup that emits laser light and a rotation mechanism that rotates an optical disc. The configuration of such a recording apparatus itself is well known.

  When recording a visible image on the image recording layer using the recording apparatus having such a configuration, the recording apparatus tracks both the groove and the land of the tracking guide groove formed in the image recording layer of the optical disc. As described above, the laser pickup is relatively moved along the label surface of the optical disk, and in synchronization with the relative movement, the laser light is modulated in accordance with image data such as characters and pictures to be imaged to form an image recording layer. Irradiate toward and record a visible image. Such a configuration is described in, for example, Japanese Patent Application Laid-Open No. 2002-203321.

(Information recording method)
Next, recording of information (digital information) on the recording layer will be described. When the recording layer is a dye type, first, laser light is irradiated from a laser pickup while rotating the above-mentioned unrecorded optical disk at a predetermined recording linear velocity. By this irradiation light, the dye in the recording layer absorbs the light and the temperature rises locally, and a desired void (pit) is generated and its optical characteristics are changed to record information. The recorded information is reproduced by irradiating a laser beam from a laser pickup toward the recording layer of the rotated optical disk.

The recording waveform of the laser beam may be a pulse train or one pulse when one pit is formed. The ratio to the actual recording length (pit length) is important.
The pulse width of the laser beam is preferably in the range of 20 to 95%, more preferably in the range of 30 to 90%, and still more preferably in the range of 35 to 85% with respect to the length to be actually recorded. Here, when the recording waveform is a pulse train, the sum is in the above range.

The power of the laser beam varies depending on the recording linear velocity, but when the recording linear velocity is 3.5 m / s, the range of 1 to 100 mW is preferable, the range of 3 to 50 mW is more preferable, and the range of 5 to 20 mW is further increased. preferable. When the recording linear velocity is doubled, the preferable range of the laser beam power is ^21/2 times, respectively.

  In order to increase the recording density, the NA of the objective lens used for the pickup is preferably 0.55 or more, and more preferably 0.60 or more.

  In the present invention, a semiconductor laser having an oscillation wavelength in the range of 350 to 850 nm can be used as the recording light.

On the other hand, a case where the recording layer is a phase change type will be described. In the case of the phase change type, the recording layer is made of the above-described material, and the phase change between the crystalline phase and the amorphous phase can be repeated by irradiation with laser light.
At the time of information recording, a concentrated laser light pulse is irradiated for a short time to partially melt the phase change recording layer. The melted portion is rapidly cooled by heat diffusion and solidified to form an amorphous recording mark. During erasing, the recording mark portion is irradiated with laser light, heated to a temperature below the melting point of the recording layer and above the crystallization temperature, and then cooled to crystallize the amorphous recording mark. Return to the unrecorded state.

Claims (1)

An image recording method for an optical disc provided with an image recording layer on which a visible image is recorded by laser light irradiation on a label surface,
An image recording method, wherein the image recording layer has a guide groove for tracking in an image recording region, tracks both the groove and land of the guide groove, and records on the groove and land.