DESCRIPTION OPTICAL RECORDING DISK AND METHOD OF MANUFACTURING THE SAME
[0001]
BACKGROUND OF THE INVENTION
Field of Invention
The present invention relates to an optical recording medium, and in particular to an optical disc having an image-recording layer (sometimes referred as a visible information recording layer) that allows recording of a visible image and a method for forming the optical recording disk. [0002] Description of the Related Art
Optical recording media (optical discs) where information is recorded only once by laser beam irradiation are known. Such optical discs, often called record able CD's (so-called CD-R), have a typical structure wherein a recording layer containing an organic dye, a light-reflectance layer of a metal such as gold, and a resin protective layer are formed on a transparent disk-shaped substrate in that order. Information is recorded on a CD-R by irradiation of a laser beam in the near-infrared region onto the CD-R (normally, laser beam at a wavelength of around 780 nm). In the irradiated area of the recording layer light is absorbed, there is a resulting localized increase in temperature, and this changes its physical and chemical properties (e.g., pit generation). Because of these physical and chemical changes the optical properties are changed and information can be recorded. Reading of the information (reproduction) is also carried out by irradiating with a laser beam having a wavelength the same as that of the recording laser beam. Information is reproduced by detecting the difference in reflectance between areas where the optical properties of the recording layer have been changed (recorded area) and areas where they are not changed (unrecorded area). [0003]
Recently, there is an increasing need for optical recording media higher in recording density. To satisfy this need, an optical disc called a Digital Versatile Disc (so-called DVD-R) has been proposed. The DVD-R has a structure wherein two discs, each consisting of a recording layer containing a dye, normally a reflectance layer over each recording layer, and also a protective layer as needed, are formed on transparent disk-shaped substrates. On the disk-shaped substrates there are guiding grooves (pregrooves) for tracking an irradiation laser beam, formed of a narrow width (such as

0.74 to 0. ) comparing to pitches (track pitches) of a CD-R. These twodisks are laminated together, with an adhesive, on the recording layer side. Alternatively two disks of the above construction can be laminated together with a disc shaped protective layer laminated between them on the recording layer side. Recording and reproduction of information on and from the DVD-R are carried out by irradiation of a visible laser beam (normally, a laser beam having a wavelength in the range of 630 to 680 nm), and the recording density of a DVD-R can be made higher than that of a CD-R. [0004]
There are some known optical discs whereon a label is adhered onto the surface opposite to the recording surface. Such a label carries printed visible image information such as the song title of the audio data recorded on the recording surface, and other titles for identifying the recorded data, and the like. Such optical discs are prepared by printing the titles and the like on a circular label sheet by using, for example, a printer, and then affixing the label on the surface opposite to the recording surface of the optical disc. [0005]
However, as described above, preparation of an optical disc carrying a label, on
which desired visible images such as title are recorded, demands a printer in addition to
an optical disc drive. Accordingly, it requires the cumbersome procedure of recording
information on the recording surface of an optical disc in an optical disc drive, then
removing the optical disc from the optical disc drive, and affixing a label printed by a
separate printer.
[0006]
Here, proposed were optical-disk recording apparatuses that allow not only the
recording and reproduction of information, but, as well, the drawing of an image on a
label surface using a laser beam (for example, JP-ANo. 2003-203348). The optical-disk
recording apparatuses use an optical disk having a thermosensitive layer on the label
surface, and form a visible image on the thermo sensitive layer (image-recording layer)
by irradiating it in the image shape with a laser beam, by scanning the laser pickup, and
thus discoloring the irradiated area.
[0007]
Such optical disks having an image-recording layer on the label face are
produced, for example, by adhering a protective layer of a first lamination body,
containing at least an information-recording layer and a reflection layer formed on a
substrate, to a second lamination body, containing at least an image-recording layer and

a reflection layer formed on another substrate, via an adhesive layer.
If a radiation-curing resin is used as an adhesive for bonding the films, generally it is not possible to harden the radiation-hardening adhesive sufficiently, because each of the laminated bodies has a reflection layer and most of the radiation beam, whichever direction it is irradiated from, does not reach the radiation-curing resin as it is blocked by a reflection layer. Use of a slow radiation-curing resin for adhesion, similarly to the methods for preparation of conventional double-faced DVD-R's, could be considered if optical disks of such embodiment are being formed. However, the slow radiation-curing resin is generally coated by screen printing, and is known to generate air bubbles in the resulting coated film. Further, these air bubbles lead to insufficient hardening of the adhesive layer, unevenness of film thickness, and deformation of the reflection layer, causing a problem of adverse effects on the mechanical properties of the optical disk.
[0008]
SUMMARY OF THE INVENTION The present invention has been accomplished in consideration of the above conventional problems. That is, the invention provides a method of forming an optical disc comprising adhering a first lamination body and a second lamination body so that a first reflection layer provided on the first lamination body and a second reflection layer provided on the second lamination body are faced toward each other across an adhesive layer, wherein: the first lamination body comprises a first substrate, an information recording layer or pits, and the first reflection layer provided in this order; the second lamination body comprises a second substrate, an image-recording layer that is capable of undergoing recording of a visible image by irradiation of laser Ught, and the second reflection layer provided in this order; the adhering comprises curing a radiation-curing resin so as to form the adhesive layer; and the curing comprises irradiating the radiation-curing resin with radiation rays from the side of the second substrate. [0009]
The invention further provides an optical disc formed by the above-described method, wherein a thickness of the second reflection layer is in a range of 40 to 100 nm.
[0010]
BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a partial cross-sectional view illustrating a layer structure of an optical disk according to the present invention.
Figure 2 is a graph showing a relationship between a wavelength of light source and relative intensity.
Figure 3 is a graph showing a relationship between a wavelength of the light penetrating the substrate and a penetration efficiency.
Figure 4 is a graph showing a relationship between a wavelength of the light penetrating the adhesive layer and the absorbency of the adhesive layer.
Figure 5 is a graph showing a relationship between a wavelength of the irradiated light, and a reflectivity and a penetration efficiency of the first reflection layer
Figure 6 is a graph showing a relationship between a wavelength of the irradiated light, and a reflectivity and a penetration efficiency of the second reflection layer.
Figure 7 is a graph showing a relationship between a light amount of the light having penetrated the second reflection layer and the wavelength of the light provided, taking a light amount of the light before penetration into the second reflection layer as 100%.
Figure 8 is a graph in which the graph of the absorbency of the adhesive layer shown in Figure 4, taking the maximum absorbency thereof as 100%5 and the graph shown in Figure 7, showing a light amount (ratio) of the light having penetrated the second reflection layer, are combined.
Figure 9 is a block diagram showing a configuration of an optical-disk recording apparatus using the optical disk according to the invention.
Figure 10 is a view illustrating a configuration of an optical pickup, a component of the optical-disk recording apparatus above.
Figure 11 is a view of an optical disk for showing how content of image data is used in forming a visible image on the image-recording layer of the optical disk in the optical-disk recording apparatus.
Figures 12A and 12B are charts for showing the method of controlling laser-beam irradiation for expressing image density, when a visible image is formed on an image-recording layer of an optical disk according to the invention in an optical-disk

recording apparatus.
Figures 13 A and 13B are charts showing a method of a controlling laser beam when a visible image is formed on the image-recording layer of the optical disk according to the invention in the optical-disk recording apparatus.
Figure 14 is a chart showing a method of controlling laser power by a laser power-controlling circuit, a component of the optical-disk recording apparatus.
Figure 15 is a chart showing the return light of a laser beam irradiated from the optical pickup of the optical-disk recording apparatus to the image-recording layer of the optical disk.
Figure 16 is chart showing an FG pulse generated according to rotation of a spindle motor by the frequency generator 21, a component of the optical-disk recording apparatus, and the clock signal generated based on the FG pulse.
Figure 17 is a flowchart showing operation of the optical-disk recording apparatus.
Figure 18 is another flowchart showing operation of the optical-disk recording apparatus.
Figure 19 is a view of the optical disk above showing a disk ID recorded on the image-recording layer.
Figure 20 is a chart showing the shape of the laser-beam return light received by the light-receiving device in the optical pickup of the optical-disk recording apparatus.
Figures 21A and 21B are charts for showing the size of the beam spot diameter of the laser beam irradiated on the image-recording layer of the optical disk from the optical pickup of the optical-disk recording apparatus.
Figure 22 is a chart for showing a method of detecting that the laser-beam irradiation position of the optical-disk recording apparatus has passed the reference position of the optical disk.
Figure 23 is a view of an optical disk showing a method of detecting that the laser-beam irradiation position of the optical-disk recording apparatus has passed the reference position of the optical disk.
Figure 24 is a timing chart for showing operation of the optical-disk recording apparatus when a visible image is formed on the image-recording layer of the optical

disk by irradiation of laser beam.
Figure 25 is a view of the image-recording layer of the optical disk on which a laser beam is irradiated in the optical-disk recording apparatus.
[0011]
DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the optical recording medium according to the invention and the image-recording method will be described. [0012]
The method of forming an optical disc of the invention includes at least adhering a first lamination body and a second lamination body so that a first reflection layer provided on the first lamination body and a second reflection layer provided on the second lamination body are faced toward each other across an adhesive layer. The first lamination body has at least a first substrate, an information recording layer or pits, and the first reflection layer provided in this order. The second lamination body has at least a second substrate, an image-recording layer that is capable of undergoing recording of a visible image by irradiation of laser light, and the second reflection layer provided in this order. The adhering includes at least curing a radiation-curing resin so as to form the adhesive layer. Further, the curing includes irradiating the radiation-curing resin with radiation rays from the side of the second substrate.
The optical disc of the invention includes at least a first lamination body and a
second lamination body adhered so that a first reflection layer provided on the first
lamination body and a second reflection layer provided on the second lamination body
are faced toward each other across an adhesive layer. The first lamination body
comprises a first substrate, an information recording layer or pits, and the first reflection
layer provided in this order. The second lamination body comprises a second substrate,
an image-recording layer that is capable of undergoing recording of a visible image by
irradiation of laser light, and the second reflection layer provided in this order. The
adhesive layer is formed by curing a radiation-curing resin. Further, a thickness of the
second reflection layer is in a range of 40 to 100 nm. [0013]
While the optical recording medium according to the invention may be any
kind of medium among read-only, recordable, rewritable, and other media depending on
the configuration of the first substrate or the image-recording layer, it is preferably a

recordable medium. In addition, while the recording method is not particularly limited and may be phase-transition recording, photomagnetic recording, or dye-assisted recording, it is preferably dye-assisted recording. In addition, the optical disk according to the invention is preferably applied to devices such as DVD (as well as DVD-R, DVD-RW, HD DVD, and others), i.e., laminated optical disks at least having an information-recording layer on the first substrate and an image-recording layer on the second substrate. [0014]
Figure 1 is a partial cross-sectional view illustrating the layer structure of an optical disk according to the invention 500. The optical disk 500 has a first lamination body 520 having an information-recording layer 514 and first reflection layer 516 on a first substrate 512 in that order, and a second lamination body 528 having an image-recording layer 524, where a visible image is recorded by irradiation of laser beam, and a second reflection layer 526 on the second substrate 522 in that order; and the first lamination body 520 and the second lamination body 528 are laminated to each dther via an adhesive layer 530, with the first reflection layer 516 and the second reflection layer 526 facing each other. While a groove is formed on the second substrate 522, the groove may either be formed or not be formed thereon.
Hereinafter, the step of laminating the first and second laminated bodies will be described, and then, respective laminated bodies are described in detail. [0015]
In the invention and in the configuration above, the first and second laminated bodies are disposed so that the first and second reflection layers face each other. A radiation-curing resin is disposed between the first and second laminated bodies. The first and second laminated bodies are adhered to each other by hardening the radiation-curing resin. The thus hardened radiation-curing resin becomes an adhesive layer. In a specific embodiment, the radiation-curing resin is coated onto the first lamination body, and then the second lamination body is disposed onto the radiation-curing resin.
The radiation-curing resin is hardened by irradiation of radiation from the second substrate side of the second lamination body. The radiation irradiated from the second substrate side penetrates the second substrate, the image-recording layer, and the

second reflection layer into the radiation-curing resin, thus the radiation-curing resin is hardened. In this way, an adhesive layer is formed by hardening of the radiation-curing resin. In such a configuration^ it is possible to irradiate the radiation after the first and second laminated bodies adhere to each other and to harden the radiation-curing resin tightly and quickly.
Conventional optical disks having such a configuration as described above generally cannot be provided with adhesive layers by the above-described manner and require use of a slow radiation-hardening adhesive since a radiation-curing resin is not hardened by radiation irradiated to the state in which the first and second laminated bodies adhere to each other because the irradiated ray (light) is reflected by the reflection layer formed on the first or second lamination body. However, since the second lamination body of the optical disk of the invention is provided with the reflection layer having the specific configuration, it is possible to harden the radiation-curing resin in the state in which the first and second laminated bodies adhere to each other, and thus there is no need to use a slow radiation-hardening adhesive. Accordingly, it is possible to make both laminated bodies adhere tightly and instantly to each other without the problem of air bubbles described above. [0016]
In the invention, because the radiation should permeate the second reflection layer as described above, the amount of the radiation irradiated is preferably 1 J/cm^ or more, more preferably 1.2 to 2.4 J/cm , and still more preferably 1.4 to 2.2 J/cm .
The amount of the radiation irradiated is determined, for example, by using a common ultraviolet illuminometer, when ultraviolet rays are used. Although there are many common ultraviolet illuminometers with different detection wavelengths, it is preferable to use an illuminometer having a detection peak in the range of 300 to 400 nm, which corresponds to the absorption wavelength of the polymerization initiator for the ultraviolet-hardening resin. [0017]
Examples of the radiation used in the invention include ultraviolet, electron beam, X ray, y ray, infrared, and the like; and ultraviolet is particularly preferable from the point of flexibility in use. The light source emitting ultraviolet rays is not particularly limited, and examples thereof include high-pressure mercury lamp, metal

halide lamp, flash lamp (such as a xenon flash lamp)^ and the like. In particular in the invention an irradiation intensity of 1 J/cm^ or more is preferable, as described above, and use of a flash lamp is preferable, because and the temperature increase during hardening thereby is lower. Specific examples of the flash lamp include the xenon flash lamp manufactured by Ushio Inc. [0018]
In the invention, the second reflection layer is preferably 40 to 100 nm in thickness. A thickness of less than 40 nm may result in generation of interference fringes by interference between the light that permeates the adhesive layer and that which is reflected by the first reflection layer and the light reflected by the second reflection layer, while a thickness of more than 100 nm may result in a decrease of the amount of the radiation reaching the radiation-curing resin for forming the adhesive layer, and lead to insufficient hardening of the radiation-curing resin. The thickness of the second reflection layer is more preferably 45 to 90 nm and still more preferably 50 to 80 run. [0019]
In the invention, the radiation-curing resin for use as the adhesive layer is preferably a radical-polymerization radiation-curing resin, i.e., a fast radiation-curing resin. Favorable examples of the radiation-curing resins include (meth)acrylate-based ultraviolet-hardening resins. The radiation-hardening adhesive is a resin that hardens by irradiation of an electromagnetic wave such as ultraviolet, electron beam, X ray, y ray, or infrared. Examples of the radical-polymerization ultraviolet-hardening resins among the radiation-curable resins include SD640 and SD661 (trade names) manufactured by Dainippon Ink and Chemicals, Inc., SK6100, SK6300, and SK6400 (trade names) manufactured by Sony Chemicals Corp, and KAYARAD DVD721 (trade name) manufactured by Nippon Kayaku Co., Ltd, The thickness of the adhesive layer is preferably in the range of 1 to 100 |am, more preferably in the range of 5 to 80 |j,m, and particularly preferably in the range of 20 to 70 ^im, for giving the layer with favorable elasticity. [0020]
A preferable wavelength of the radiation ray used for adhering the first and second lamination bodies will be described in detail. In the invention, the radiation rays

irradiated from the second-substrate side when the first and second lamination bodies are adhered to each other penetrate the second lamination body and reach the adhesive layer Therefore, the radiation ray preferably has a high penetration efficiency with respect to the second substrate and the second reflection layer, and a wavelength such that an absorbency in the adhesive layer is high. Hereinafter, a preferable wavelength of the radiation array irradiated when the adhesive layer is hardened will be examined based on an actual measurement result. [0021] Light Source
First, a light source (radiation ray source) used in the actual measurement in order to harden the adhesive layer when the first and second lamination bodies are adhered to each other is as follows.
Xenon light: Xenon flash lamp (manufactured by USHIO INC.)
Lamp power: 21IJ (energy supplied by lamp per irradiation)
Irradiation time: four-pulse irradiation (irradiation time is
approximately 0.6 second)
Fig. 2 shows a relative intensity of the light source used with respect to the wavelength. [0022] Penetration Efficiency of the Second Substrate
Fig. 3 is a graph showing a relationship between the wavelength of the light penetrating the second substrate and the penetration efficiency. In the example, a substrate with a thickness of 0.66 mm formed from polycarbonate resin (trade name: MD1500, manufactured by Idemitsu Petrochemical Co., Ltd.) was used as the second substrate. It is necessary for the second substrate to have a penetration efficiency of at least a certain level with respect to the light so that the light can reach the adhesive layer It is understood that the penetration efficiency of the substrate of the example shown in Fig. 3 exceeds zero when the wavelength of the light is approximately 270 nm or more. [0023]
Next, the adhesive layer and an adhesive used therein for the adhesion are shown below. Penetration Efficiency of the Adhesive Layer

Adhesive: ultraviolet-hardening resin (KAYARAD DVD721: described above)
Layer thickness: approximately 50 \im
Fig. 4 shows the relationship between the wavelength of the light penetrating the adhesive layer and the absorbency of the adhesive layer. It is known from Fig. 4 that two maximum values of the absorbency are generated in the range of approximately 260 to 350 nm (in particular, 260 to 340 nm), and the irradiation of the ultraviolet ray within the relevant wavelength range is suitable for hardening the adhesive layer. [0024] Reflectivity and Penetration Efficiency of the First Reflection layer
Fig. 5 is a graph showing a relationship between the wavelength of the irradiated light, and a reflectivity and a penetration efficiency of the first reflection layer A material used for the first reflection layer shown in Fig. 5 is pure silver (purity of 99.99% or more), and a layer thickness thereof is 145 nm. As shown in Fig. 5, the reflectivity of the first reflection layer is lowered in a wavelength smaller than approximately 350 nm and is slightly increased in a wavelength between 300 to 350 nm. [0025] Reflectivity and Penetration Efficiency of the Second Reflection layer
Fig. 6 is a graph showing a relationship between the wavelength of the irradiated light, and a reflectivity and a penetration efficiency of the second reflection layer. A material used for the second reflection layer shovm in Fig. 6 is pure silver (purity of 99,99% or more), and a layer thickness thereof is 65 nm. As described above, it is necessary for the second reflection layer to have a penetration efficiency of at least a certain level so that the light can reach the adhesive layer. The penetration efficiency of the second reflection layer shown in Fig. 6 is increased in a wavelength of approximately 250 to 350 nm (in particular, 300 to 350 nm), and it is presumed that the ultraviolet ray is hardened with the light of the wavelength (radiation ray) within that range.
Fig, 7 is a graph showing a relationship between a light amount of the light having penetrated the second reflection layer and the wavelength of the light provided, taking a light amount of the light before penetration into the second reflection layer as 100%. It is known from Fig. 7 that the light amount is increased in the wavelength of approximately 250 to 350 nm (in particular, 300 to 350 nm), and the light within the

relevant wavelength range is suitably used. [0026]
Fig. 8 is a graph in which the graph shown in Fig. 4 and the graph shown in Fig. 7 are combined. As can be understood from the graph shown in Fig. 8, the light amount penetrating the second reflection layer and the light amount absorbed by the adhesive layer are increased in a wavelength region smaller than 350 nm in the optical disc according to the invention. Therefore, the radiation-curing adhesive can be hardened in the state where the first and second lamination bodies adhere to each other in the optical disc according to the invention. As a result, the adhesive layer can be sufficiently hardened in the optical disc according to the invention, and the optical disc can be thereby efficiently manufactured. It can be understood from the foregoing description that the wavelength of the light irradiated when the adhesive layer is hardened is preferably 270 to 350 nm. [0027]
The first and second laminated bodies are adhered and hardened, for example, by dripping a radiation-curing resin on either the surface of the first reflection layer of the first lamination body or the surface of the second reflection layer of the second lamination body, spreading the resin uniformly thereon by spinning the lamination body carrying the dripped radiation-curing resin, adhering the other lamination body thereto, and irradiating the layer with radiation from the second substrate side. Alternatively, it may be formed by adding the radiation-curing resin dropwise on either the surface of the first reflection layer of the first lamination body or the surface of the second reflection layer of the second lamination body, adhering the other lamination body thereon, spinning the laminate at high speed while removing the excessive resin, and irradiating the layer with radiation.
Hereinafter, respective layers in the laminated bodies of the optical disk according to the invention will be described. [0028] Information recording layer
The information recording layer, a layer wherein coded information such as digital information is recorded. While it is not particularly limited, and examples thereof include dye-containing, recordable, phase-transition, photomagnetic, and other layers.

the recording layer is preferably a dye-containing layer. [0029]
Specific examples of the dyes contained in the dye-containing recording layer include cyanine dyes, oxonol dyes, azo dyes, phthalocyanine dyes, triazole compounds (the scope thereof includes benzo triazole compounds), triazine compounds, merocyanine compounds, aminobutadiene compounds, cinnamic acid compounds, benzotriazole compounds, pyrromethene compounds^ squarylium compounds and the like. These dyes and compounds may have a metal atom in a coordination center thereof Specific examples of the dyes further include the dyes described in JP-ANos. 4-74690, 8-127174, 11-53758, 11-334204, 11-334205, 11-334206, 11-334207, 2000-43423, 2000-108513, 2000-158818 and others.
When the optical disk formed in accordance with one aspect of the invention is a compact disk, preferable examples of the dyes used therein include cyanine dyes, azo dyes and phthalocyanine dyes. When the optical disk formed in accordance with one aspect of the invention is a DVD, preferable examples of the dyes used therein include cyanine dyes, oxonol dyes, azo dyes (the scope thereof includes Ni complexes and Co complexes), and pyrromethene compounds. When the optical disk formed in accordance with one aspect of the invention is a blue-ray disk, preferable examples of the dyes used therein include cyanine dyes, oxonol dyes, azo dyes, phthalocyanine dyes^ benzotriazole compounds, and triazine compounds.
Among the above-described compounds, when the optical disk formed in accordance with one aspect of the invention is a compact disk, particularly preferable examples of the dyes used therein include cyanine dyes, azo dyes and phthalocyanine dyes. When the optical disk formed in accordance with one aspect of the invention is a DVD, particularly preferable examples of the dyes used therein include cyanine dyes, oxonol dyes and azo dyes (the scope thereof includes Ni complexes and Co complexes). When the optical disk formed in accordance with one aspect of the invention is a blue-ray disk, particularly preferable examples of the dyes used therein include cyanine dyes, oxonol dyes, azo dyes, and phthalocyanine dyes. [0030]
The information recording layer can be formed by preparing a coating liquid by dissolving the recording material such as dye, with a binder, and the like in a suitable solvent, then forming a coated layer by applying the coating solution onto a substrate, and drying. The concentration of the recording material in the coating liquid for the recording material is generally in the range of 0.01 to 15 % by weight, preferably in the range of 0.1 to 10 % by weight, more preferably in the range of 0.5 to 5 % by weight,

and particularly preferably in the range of 0.5 to 3 wt %, relative to the total mass of the
coating liquid.
[0031]
While the recording layer can be formed, for example, by vapor deposition, sputtering, CVD, or solvent application, it is preferable that solvent application is utilized. [0032]
Examples of solvents for the coating liquid include: esters such as butyl acetate, ethyl lactate or cellosolve acetate; ketones such as methylethylketone, cyclohexanone or methylisobutylketone; chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane, or chloroform; amides such as dimethylformamide; hydrocarbons such as methylcyclohexane; ethers such as dibutylether, diethylether, tetrahydrofiiran, or dioxane; alcohols such as ethanol, n-propanol, iso-propanol, n-butanol, or diacetone alcohol; fluorochemical solvents such as 2,253,3-tetrafluoropropanol; and glycol ethers such as ethylene glycol monomethylether, ethylene glycol monoethylether, or propylene glycol monomethylether.
With consideration to the solubility of dyes used, the solvents above may be used alone or in combinations of two or more. The coating liquid may further contain various additives such as antioxidants, UV absorbents, plasticizers, or lubricants according to the intended use. [0033]
When a binder is used in the invention, examples thereof include: natural organic polymers such as gelatin, cellulose compounds, dextran, rosins or rubbers; and synthetic organic polymers, including hydrocarbon resins such as polyethylene, polypropylene, polystyrene^ or polyisobutylene, vinyl resins such as polyvinyl chloride, polyvinylidene chloride, or polyvinyl chloride-polyvinyl acetate copolymers, acrylic resins such as polymethyl acrylate or polymethyl methacrylate, and initial condensates of thermosetting resins such as polyvinyl alcohol, chlorinated polyethylene, epoxy resin, butylal resin, rubber compounds, or phenol-formaldehyde resin. [0034]
When a binder is additionally used as the material for the information recording layer, the amount of the binder used is generally in the range of 0.01 to 50 times and preferably 0.1 to 5 times the weight of the dye contained in the information recording layer. [0035]
Examples of the methods of application of the coating liquid for forming the

information recording layer include a spraying method, a spin coating method, a dipping method, a roll coating method, a blade coating method, a doctor roll coating method, and a screen-printing method. The recording layer may have a configuration formed of either a single layer or multiple layers. The thickness of the recording layer is generally in the range of 10 to 500 nm, preferably in the range of 15 to 300 mn, and more preferably in the range of 20 to 150 nm. [0036]
The information recording layer may contain various discoloration inhibitors for improvement of the light fastness of the information recording layer. Commonly, a singlet-oxygen quencher is used as the discoloration inhibitor. Any known singlet oxygen quencher described in literature, including patent specifications, may be used. Specific examples thereof include those described in JP-ANos. 58-175693, 59-31194, 60-18387, 60-19586, 60^19587, 60-35054, 60-36190, 60-36191, 60-44554, 60-44555, 60-44389, 60-44390, 60-54892, 60-47069, 68-209995, and 4-25492, Japanese Patent Application Publication Nos. 1-38680 and 6-26028, German Patent. No. 350399, and Nippon Kagakukaishi JP, Oct. 1992, p.l 141, and others. [0037]
The amount of the discoloration inhibitor such as the singlet oxygen quencher is usually in the range of 0.1 to 50 % by weight, preferably in the range of 0.5 to 45 % by weight, more preferably in the range of 3 to 40 % by weight, and particularly preferably in the range of 5 to 25 % by weight relative to the weight of the dye contained in the information recording layer. [0038]
Specific examples of the materials for forming a phase-transition 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 alloy, and Ag-Ge-In-Sb-Te alloy. Among them, Ge-Sb-Te and Ag-In-Sb-Te alloys are preferable, as the layers thereof are re-recordable a great number of times.
The thickness of the phase-transition recording layer is preferably in a range of 10 to 50 nm and more preferably in a range of 15 to 30 nm.
The phase-transition recording layer described above can be formed, for example, by gas-phase thin film deposition methods such as sputtering and vacuum deposition. [0039] First substrate and Second substrate

The first substrate and the second substrate used in the optical recording medium of the invention may be selected from various materials hitherto used as the substrates for conventional optical recording media.
Examples of the substrate materials include glass, acrylic resins such as polycarbonate or polymethyl methacrylate, polyvinyl chlorides such as polyvinyl chloride or vinyl chloride copolymers, epoxy resins, amorphous polyolefins and polyesters, and these resins may be used in combination if desired.
These materials may be used in the film shape or the rigid plate shape. Among the materials above, polycarbonate is preferable in view of humidity resistance, dimensional stability, and cost. [0040]
The thicknesses of the first and second substrates are preferably in a range of 0.1 to 1.2 mm and more preferably in a range of 0.2 to 1.1 mm. It is basically preferable that a groove or a servo signal for tracking is formed on the first substrate. Further, a substrate having such a groove or a servo signal for tracking formed thereon may be used as the second substrate. The track pitch of the groove of the first substrate is preferably in the range of280to450nm and more preferably in the range of 300 to 420 xun. The depth of groove (groove depth) is preferably in the range of 15 to 150 nm and more preferably in the range of 25 to 100 nm. [0041]
The groove for tracking may be further formed on the second substrate in order
to record an image having high accuracy. In such a case, a track pitch of the groove is
preferably in a range of 0.3 to 200 |im, more preferably in a range of 0.4 to 100 ^m, and
still more preferably in a range of 0.6 to 50 |am in view of the distribution of intensity of
recording laser. [0042]
When tracking is performed during image recording and a thickness of the
substrate on the side from which laser light incidents is 0.6 mm, a depth of the groove is
preferably in a range of 50 to 200 nm, more preferably in a range of 80 to 150 nm, and
still more preferably in a range of 100 to 130 nm. A width of the groove is preferably in
a range of 100 to 600 nm, more preferably in a range of 200 to 500 nm, and still more
preferably in a range of 250 to 450 nm. The most preferable range of a shape of the
groove may vary depending on a wavelength of laser light, NA, a thickness of the
substrate and the like.
[0043]

An undercoat layer may be formed on the surface of the first substrate (the face whereon the groove is formed) for improving the planarity and adhesiveness, and preventing deterioration of the recording layer.
Examples of materials for forming the undercoat layer include polymer materials such as polymethyl methacrylate, acrylic acid-methacrylic acid copolymers, styrene-maleic anhydride copolymers, polyvinyl alcohol, N-methylol acrylamide, styrene-vinyl toluene copolymers, chlorosulfonated polyethylene, nitrocellulose, polyvinylchloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate-vinyl chloride copolymers, ethylene-vinyl acetate copolymers, polyethylene, polypropylene, or polycarbonate; and surface modification agents such as silane coupling agents. The undercoat layer can be prepared by preparing a coating liquid by dissolving or dispersing the materials in a suitable solvent, and applying the coating liquid onto a substrate surface by^ for example, a suitable application method such as spin coating, dip coating, or extrusion coating.
The thickness of the undercoat layer is generally in the range of 0.005 to 20 (am and preferably in the range of 0.01 to 10 |im. [0044]
It is preferable to roughen the surface of the second substrate for preventing reflection from the surroundings by specular reflection in the area of the visible image drawn on the image-recording layer. [0045]
The surface-roughening method is not particularly limited, and the surface-roughening of the second substrate may be performed by various methods, and among them, the following first to fifth methods are preferable. [0046]
(1) In the first surface-roughening process, the surface of the second substrate on which the image-recording layer is formed is roughened by using a stamper having a roughened surface on the face that contacts with the second substrate. Specifically, the surface of the stamper for use in preparing the second substrate is first roughened. The surface of the stamper is roughened to a desirable roughness by, for example, sand blasting. In addition, the surface may be processed chemically as described in the fifth

surface-roughening process. The stamper is then set in a mold with its surface-roughened face in contact with the resin material of second substrate; and the second substrate, having a roughened surface only on one face, is obtained by processing in the mold by a known method. As for the "desired roughness", for example, the maximum height (Rz) of the face is preferably 0.3 to 5 [im and the mean width of roughness profile elements (RSm) is 10 to 500 |im. [0047]
(2) In the second surface-roughening process, the surface of the second,
substrate on which the image-recording layer is to be formed is roughened by using a
molding mold surface-roughened on the face that contacts which the molded second
substrate. Specifically, one face of the molding mold for the second substrate is
surface-roughened in advance. The method of surface-roughening is the same as that in
the first surface-roughening process, and it is possible to prepare the second substrate,
having a surface-roughened face only on one face, by molding in the mold by a known
method.
[0048]
(3) In the third surface-roughening process, the surface of the second substrate
on which the image-recording layer is to be formed is roughened by applying and
hardening a resin containing dispersed fine particles on the surface of the side of the
image-recording layer of the second substrate. Examples of the resins for use include
acrylate-based ultraviolet-hardening resin, epoxy resins, isocyanate-based thermosetting
resins, and the like.
[0049]
Examples of the fine particles include inorganic fine particles such as SiOi or AI2O3, and organic fine particles such as of polycarbonate or acrylic resin. The volume average diameter of the fine particles is preferably 0.3 to 200 |xm and more preferably 0-6 to 100 |j.m. It is possiWe to adjust the degree of surface-roughening by adjusting the particle diameter and the amount of the fine particles used, [0050]
(4) In the fourth surface-roughening process, the surface of the second
substrate carrying image-recording layer is roughened by processing the surface on the
side on which the image-recording layer of the second substrate is to be formed. Various

processing methods may be applied to the mechanical processing, but application of a
blasting method such as sand blasting is preferable.
[0051]
(5) In the fifth surface-roughening process, after forming the second substrate, the surface on which the image-recording layer will be formed is roughened by carrying out chemical processing on that surface of the second substrate. The chemical processing can be performed by, for example, etching by coating or spraying of a solvent on the face of the second substrate after molding. The solvent is preferably an organic solvent such as dimethylformamide, and, in addition, acidic solvents such as nitric acid, hydrochloric acid, or sulfuric acid may also be used. It is possible to obtain a desired roughness by adjusting the normality of the acidic solvent and the duration of coating. [0052] First reflection layer and Second reflection layer
A first reflection layer and a second reflection layer are formed adjacent to the recording layer or the image-recording layer for improvement of reflectance during reproduction of information. The light-reflecting material used for the reflection layer is a material having a high reflectance for laser beam, and examples thereof include metals and semimetals such as Mg^ Se, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, 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, and Bi, and stainless steel. These materials may be used alone, in combinations of two or more, or as alloys. The reflection layer is formed on the substrate or recording layer, for example, by vapor deposition, sputtering, or ion plating of the light-reflecting material.
The thickness of the first reflection layer is generally in the range of 10 to 300 nm, preferably in the range of 50 to 200 nm, more preferably in the range of 80 to 200 nm, and ftirther preferably in the range of 100 to 200 nm. Preferable examples of a material for forming the first reflection layer include Cr, Ni, Pt, Cu, Ag, Au, Al and stainless steel. Particularly preferable examples of the material for forming the first reflection layer include Au metal, Ag metal, Al metal and alloys thereof Most preferable examples of the material for forming the first reflection layer include Ag metal, Al metal and alloys thereof
The thickness of the second reflection layer is preferably in the range of 40 to 100 nm, more preferably in the range of 40 to 90 nm, further preferably in the range of 45 to 90 nm, particularly preferably in the range of 40 to 80 nm, and most preferably in

the range of 50 to 80 nm. If the thickness of the second reflection layer exceeds the upper limit, the hardening of the resin tends to be insufficient since radiation rays do not pass through the second reflection layer. On the other hand, if the thickness of the second reflection layer is smaller than the lower limit, the functions of the second reflection layer as a reflection layer of the image information recording layer ends to be insufficient. Preferable examples of a material for forming the second reflection layer include silver and silver alloys. More preferable examples of a material for forming the second reflection layer include silver metal and silver alloys having 90 wt% or more of silver. Further preferable examples of a material for forming the second reflection layer include silver metal and silver alloys having 95 wt% or more of silver. Most preferable examples of a material for forming the second reflection layer include pure silver [0053] Adhesive layer
The adhesive layer is a layer for adhering the fiirst lamination body 20 and the second lamination body 28 shown in Fig. 1, and is disposed between the first reflection layer 16 and the second reflection layer 26. Detail of the adhesive layer is described above, [0054] Image-recording layer
As described above, the optical recording medium according to the invention has an image-recording layer that is formed on the opposite side of the optical recording medium to the information-recording layer. Visible images (image information) desired by users, such as characters/letters, graphics, and pictures are recorded on the image-recording layer. Examples of visible images include: the title of the disc; content information; thumbnails of the content; related pictures; pictures for design of the disc; copyright information; recording date; recording method; recording format; and bar codes. The image-recording layer (visual information recording layer) may be either a visual information recording layer to which visual information is recorded by plural times of irradiation of laser light onto approximately the same trace or a visual information recording layer to which visual information is recorded by swinging of laser light outward in the radial direction of the optical disk and by plural times of irradiation of laser hght onto approximately the same trace. [0055]
The visible image to be recorded in the image-recording layer means an image which is visually recognizable, and examples thereof include all visually recognizable information such as any characters/letters (lines), pictures, and graphics. Examples of

character/letter information include authorised user identification infoimation,
expiration date information, designated allowable number of times of use information,
rental information, resolution-specifying information, layer-specifying information,
user-specifying information, copyright holder information, copyright number
information, manufacturer information, production date information, sales date
information, dealer or seller information, usage set-number information, area
identification information, language-specifying information, application-specifying
information, product user information, and usage number information.
[0056]
The only requirement of the image-recording layer is to be able to visibly
record image information such as character, image, and picture by irradiation of laser
light. The dyes described in the above explanation about the information recording layer
can also be preferably used as the material for forming the image-recording layer. [0057]
In the optical disk according to the invention, the components for the information-recording layer (colorant or phase-change recording material) and the components for the image-recording layer may be the same as each other or different from each other, but are preferably different from each other, because the required properties of the information-recording layer and the image-recording layer are different. Specifically, components superior in recording and reproduction characteristics are favorably used as the components for information-recording layer, while components effective in increasing the contrast of the recorded image are favorable as the components for image-recording layer. Examples of the dye that is used in the image recording layer and is preferable ui view of improving contrast of the recorded image include cyanine dyes, phthalocyanine dyes, azo dyes, azo metal complex dyes, and oxonol dyes. Preferable examples of the dyes further include the combinations of: cyanine and cyanine dyes; oxonol and oxonol dyes; metal complex and metal complex dyes; cyanine and oxonol dyes; cyanine and metal complex dyes; cyanine dyes and phthalocyanine dyes; oxonol dyes and cyanine dyes; oxonol dyes and phthalocyanine dyes; and the like. [0058]
Leuco dyes may also be used. Favorable examples thereof include crystal violet lactone; phthalide compounds such as

3,3-bis(l-ethyl-2-methylindol-3"yl)phthalide and 3-(4-diethylamino-2-ethoxyphenyI)-3-(l-ethyl-2- methylmdol-3-yl)-4-azaphthalide;
fluorane compounds such as 3-cyclohexylmethylamino-6-methyl-7-aiiilmofluorane,
2-(2-chloroamlino)-6-dibutylaminofluorane, 3-diethylamino-6-methyl-7-anilinofluorane; 3-diethylamino-6-methyl-7-xylidinofluorane, 2-(2-chloroamlino)-6-diethylaminofluorane5 2-anilino-3-methyl-6-(N-ethylisopentylamino) fluorane, 3-diethylamino-6-chloro-7-aiiilinofluorane, 3-benzylethylamino-6-methyl-7-anilinofluorane, or 3-methylpropylamino-6-methyl-7-anilinofluorane; and the like. [0059]
The image-recording layer can be formed by preparing a coating solution by dissolving a colorant described above in a solvent and applying the coating solution. Examples of the solvents include the solvents used in preparing the coating solution for information-recording layer. Other additives and application methods are the same as those described above for the recording layer, but application by spin coating is preferable. [0060]
The thickness of the image recording layer is preferably in a range of 0.01 to 200 iim^ more preferably 0.02 to 100 jxm, and still more preferably in a range of 0.04 to 50 i-im. [0061] Protective layer
A protective layer may be formed for physical and chemical protection of the first reflection layer, the information recording layer, the second reflection layer, or the image recording layer.
[0062]
Examples of materials for use in the protective layer include: inorganic materials such as ZnS, ZnS-SiOi, SiO, SiOi, MgF2, SnOi, or Si3N4; and organic materials such as thermoplastic resins, thermosetting resins, or UV-curing resins. [0063]

When a thermoplastic or thermosetting resin is used^ the layer may be formed by preparing a coating liquid by dissolving the resin in a suitable solvent, applying the coating liquid, and drying the coated liquid so as to form a film. When a UV-curing resin is used^ the layer may be formed by using the resin as it is or preparing a coating liquid by dissolving the resin in a suitable solvent^ applying the coating liquid, and curing the resin by UV ray irradiation. The coating liquid may further contain various additives such as antistatic agent, antioxidant, or UV absorbent according to its application. The thickness of the protective layer is generally in the range of 0.1 |-im to 1 mm. [0064]
As is described above, the optical disc of the invention can be used in the application for what is called a read-only disc, in which the first substrate has a recording area (pit) in which information that can be reproduced by laser light is recorded. [0065] Image-recording method
The image-recording method according to the invention uses the optical disc of the invention and a recording device that is capable of recording image information onto the image recording layer of the optical disc of the invention.
Hereinafter, the recording device used in the invention is described in detail. [0066] Recording device for optical disc
In the optical disc according to the invention, image recording on the image
recording layer and optical information recording on the information recording layer
thereof can be performed by using a single optical disc drive (recording device) capable
of recording information on both layers. When only one optical disc drive is used in
this manner, information is first recorded on either an image recording layer or an
information recording layer and then, after the optical disc is reversed, information is
ftirther recorded on the other layer.
[0067]
The above-described optical disc according to the invention can be specifically
preferably used in the devices and methods described in the followings.
[0068]
A favorable embodiment of the optical-disk recording apparatus using the
optical disk according to the invention described above is (1) an optical-disk recording
apparatus, recording information by irradiating a recording face (e.g., colorant recording

layer (recording layer)) of an optical disk with a laser beam, comprising: an optical pickup irradiating the optical disk with a laser beam; an irradiation-position adjusting means of adjusting the position on the optical disk of the laser beam irradiated by the optical pickup; an image-formation controlling means, controlling the optical pickup and the irradiation-position adjusting means so that, when an optical disk having the recording layer on one face and an image-recording layer on the other face is placed with the image-recording layer facing the optical pickup, a visible image corresponding to image information is formed on the image-recording layer of the optical disk; and a beam-spot controlling means of controlling the optical pickup so that, when the visible image is formed, the beam spot diameter of the laser beam from the optical pickup irradiating the image-recording layer becomes larger than the beam spot diameter of the laser beam from the optical pickup irradiation the recording face during information recording. [0069]
In the configuration (1) above, it is possible to form a visible image corresponding to image data by irradiating the image-recording layer of optical disk with laser beam according to the image data, because the reflectivity of the image-recording layer changes image wise according to changes in the absorbance of the image-recording layer By widening the beam spot diameter of the laser beam irradiated on the image-recording layer of the optical disk during formation of the visible image, it is possible to irradiate a wider region with the laser beam in one rotation of the optical disk and shorten the duration needed for forming a visible image. The optical disk according to the invention described above also allows recording of a favorable visible image even by such a method. [0070]
Another favorable embodiment of the optical-disk recording apparatus is (2) an optical-disk recording apparatus, recording information by irradiating a recording face of an optical disk with a laser beam, comprising: an optical pickup irradiating the optical disk with the laser beam; an irradiation-position adjusting means, adjusting the position on the optical disk of the laser beam irradiated by the optical pickup; a means of controlling the optical pickup and the irradiation-position adjusting means so that, when an optical disk having the recording face on one face and the image-recording

layer on the other face is placed with the image-recording layer facing the optical pickup, a visible image corresponding to image information is formed on an image-recording layer of the optical disk^ and the irradiation-position adjusting means also controlling the intensity of the laser beam of the optical pickup irradiating the image-recording layer on the basis of the image information to a first intensity, at which the image-recording layer substantially does not change^ or a second intensity, larger than the first intensity and at which the image-recording layer does change; and a servo means, detecting information related to the laser beam irradiated to the optical disk by the optical pickup and controlling the optical pickup to irradiate a desired laser beam based on the detected result, wherein, when a duration of the laser beam, irradiated according to control based on the image information from the optical pickup continuously at the second intensity, exceeds a specific duration, the image-formation controlling means controls the intensity of the laser beam irradiated from the optical pickup to the first intensity for a specific duration independently of the content of the image information, and the servo means controls the optical pickup based on the detected result of information related to the laser beam irradiated at the first intensity. [0071]
In the configuration (2) above, it is possible to form a visible image corresponding to image data by irradiating the image-recording layer of an optical disk with a laser beam according to the image data, because the reflectivity of the image-recording layer changes imagewise according to changes in the absorbance of the image-recording layer. During formation of the visible image, when the intensity of the laser beam for image data is sustained at the second intensity, that leads to change of the image-recording layer, for an extended period of time, control is made of the laser beam to the laser beam at the first intensity, that leads to almost no change of the image-recording layer,, independently of the image data. Thus, it is possible to control the laser beam based on the irradiation result. An optical disk according to the invention described above is also able to undergo recording of a favorable visible image even by such a method. [0072]
Yet another favorable embodiment of the optical-disk recording apparatus is (3) an optical-disk recording apparatus, recording information by irradiating a recording

face of an optical disk with a laser beam^ comprising: an optical pickup, irradiating the optical disk with the laser beam; an irradiation-position adjusting means, adjusting the position on the optical disk of the laser beam irradiated by the optical pickup; an image-formation controlling means, controlling the optical pickup and the irradiation-position adjusting means so that, when an optical disk having the recording face on one face and the image-recording layer on the other face is placed with the image-recording layer facing the optical pickup, a visible image corresponding to image information is formed on the image-recording layer of the optical disk; and a relative-position adjusting means, adjusting the relative position of the optical pickup and the face of the optical disk facing the optical pickup when the optical disk is set in the optical-disk recording apparatus, based on whether the face of the optical disk facing the optical pickup is the image-recording layer or is the recording face. [0073]
In the configuration (3) above, it is possible to form a visible image corresponding to image data by irradiating the image-recording layer of an optical disk with a laser beam according to the image data because the reflectivity of the image-recording layer changes imagewise according to changes in the absorbance of the image-recording layer. It is possible to adjust the relative position between the optical pickup and the face facing the optical pickup, based on whether the image-recording layer or the recording face is placed facing the optical pickup when the optical disk is set. Thus, it is possible to eliminate problems such as the inability to undertake various controls, for example focus control, due to a difference in the distance between the optical pickup and the face facing the same, even if the distance thereof is different depending on whether the recording face or the image-recording layer is placed facing the optical pickup. The optical disk according to the invention described above also allows recording of a favorable visible image even in such a method. [0074]
Yet another favorable embodiment of the optical-disk recording apparatus is (4) an optical-disk recording apparatus, recording information by irradiating a recording face of an optical disk with a laser beam* comprising: an optical pickup, irradiating the optical disk with the laser beam; an irradiation-position adjusting means, adjusting the position on the optical disk of the laser beam irradiated by the optical pickup; a servo

means, controlling, based on the reflected laser beam from the optical disk irradiation, the irradiation-position adjusting means to make the optical pickup irradiate the laser beam along guide grooves when an optical disk, having a recording face on one face and an image-recording layer on the other face, and having helical guide grooves formed on the recording face, is set with the image-recording layer facing the optical pickup; and an image-formation controlling means, controlling the laser beam irradiated from the optical pickup so that a visible image corresponding to image information is formed on the image-recording layer of the optical disk while the irradiation position of the laser beam is being moved along the guide grooves by the servo means. An optical disk according to the invention described above is also able to undergo recording of a favorable visible image even by such a method. [0075]
In the configuration (4), it is possible to form a visible image corresponding to image data by irradiating the image-recording layer of optical disk with a laser beam according to the image data, because the reflectivity of the image-recording layer changes imagewise according to changes in the absorbance of the image-recording layer. It is possible in this case to form a visible image on the recording face without complicated laser-beam-irradiation-position control, detecting the guide grooves formed on the recording face and altering the laser-beam irradiation position along the detected guide grooves. [0076]
Yet another favorable embodiment of the optical-disk recording apparatus is (5) an optical-disk recording apparatus, recording information by irradiating a recording face of an optical disk with laser a beam, comprising: an optical pickup irradiating the optical disk with the laser beam; a rotation drive means, rotating the optical disk; a clock signal output means, outputting a clock signal at a frequency corresponding to the rotation speed of the optical disk rotated by the rotation drive means; an image-formation controlling means, controlling the optical pickup so that, when an optical disk having a recording layer on one face and an image-recording layer on the other face is set with the image-recording layer facing the optical pickup, a visible image corresponding to image information is formed on the image-recording layer of the optical disk, the image-formation controlling means also controlling the laser beam

irradiated from the optical pickup based on the image information sent in each clock-signal cycle from the signal output means; a rotation detecting means, detecting one rotation from the reference position of the optical disk as driven by the rotation drive means; and an irradiation-position adjusting means, altering the irradiation position of the laser beam from the optical pickup a predetermined radial distance of the optical disk set in the optical-disk recording apparatus when one rotation of the optical disk from the predetermined reference position is detected by the rotation detecting means, while the laser beam is being irradiated from the optical pickup for forming the visible image on the image-recording layer of the optical disk. [0077]
In the configuration (5), it is possible to form a visible image corresponding to image data by irradiating the image-recording layer of optical disk with a laser beam according to the image data, because the reflectivity of the image-recording layer changes imagewise according to changes in the absorbance of the image-recording layer. Because, when forming the visible image, laser-beam irradiation control for forming the visible image is performed for each clock-signal cycle at a frequency corresponding to the rotational velocity of optical disk, i.e., each time the optical disk rotates a specific angle, a visible image can be formed with image data with contents (e.g., density) corresponding to the positions at the specific angles on the optical disk. An optical disk according to the invention described above is able to undergo recording of a favorable visible image even by such a method. [0078]
Yet another embodiment of the optical-disk recording apparatus is (6) an optical-disk recording apparatus, recording information by irradiating the recording face of an optical disk with a laser beam comprising: an optical pickup irradiating the optical disk with the laser beam; a rotation drive means, rotating the optical disk; a rotation detecting means, detecting one rotation by the rotation drive means of the optical disk, from a reference position; an image-formation controlling means, controlling the optical pickup so that, when an optical disk having a recording layer on one face and an image-recording layer on the other face is placed with the image-recording layer facing the optical pickup, a visible image corresponding to image information is formed on the image-recording layer of the optical disk; and an irradiation-position adjusting means,

altering the irradiation position of the laser beam from the optical pickup a predetermined radial distance of the optical disk set in the optical-disk recording apparatus when one rotation of the optical disk from the predetermined reference position is detected by the rotation detecting means, while the laser beam is being irradiated from the optical pickup for forming the visible image on the image-recording layer of the optical disk; wherein the image-formation controlling means controls the optical pickup so as to irradiate the laser beam for forming the visible image on the optical disk rotated by the rotation drive means from the predetermined reference position of the image-recording layer, and controls so as not to irradiate the laser beam for forming the visible image onto a region from a position a particular distance prior to the predetermined reference position up to the predetermined reference position of the optical disk. [0079]
In the configuration (6), it is possible to form a visible image corresponding to image data, by irradiating the image-recording layer of optical disk with a laser beam according to the image data because the reflectivity of the image-recording layer changes imagewise according to changes in the absorbance of the image-recording layer. A visible image is formed by irradiating the optical disk from the reference position of the optical disk with the laser beam while the optical disk is rotated during formation of the visible image; and no laser beam for forming a visible image is irradiated on the region immediately before the laser-beam irradiation position returns back to the reference position. Thus, even when the laser-beam irradiation position control is somehow disturbed, for example, by unstable rotation of the optical disk, or when a laser beam is irradiated on the optical disk from the reference position for one rotation and goes back to its original irradiation reference position and the irradiation position of the laser beam goes to a position overlapping with where the laser beam has already been irradiated, it is possible to prevent irradiation of the visible image forming laser beam fat that position, and consequently, to improve the quality of the formed visible image. [0080]
Yet another embodiment of the optical-disk recording apparatus is (7) an optical-disk recording apparatus, recording information by irradiating a recording face

of an optical disk with a laser beam, comprising: an optical pickup irradiating the optical disk with the laser beam; an irradiation^position adjusting means, adjusting the position on the optical disk of the laser beam irradiated by the optical pickup; a disk identifying means, obtaining disk identification information for identifying the kind of the optical disk set in the optical-disk recording apparatus; an image-formation controlling means, controlling the optical pickup and the irradiation-position adjusting means so that, when an optical disk having a recording layer on one face and an image-recording layer on the other face is placed with the image-recording layer facing the optical pickup, a visible image corresponding to image information is formed on the image-recording layer of the optical disk, and the image-formation controlling means also controlling the optical pickup and the irradiation-position adjusting means according to the kind of the optical disk identified by the disk identifying means. [0081]
In the configuration (7), it is possible to form a visible image corresponding to image data by irradiating the image-recording layer of optical disk with a laser beam according to the image data because the reflectivity of the image-recording layer changes imagewise according to changes in the absorbance of the image-recording layer. It is possible to control the conditions of forming the visible image according to the kind of the disk that has been set during formation of the visible image. [0082]
Yet another embodiment of the optical-disk recording apparatus is (8) an optical-disk recording apparatus having an optical pickup irradiating the optical disk with a laser beam, a modulation means, modulating information supplied from outside, and a laser beam control means, controlling the laser bean irradiated from the optical pickup according to the information supplied from the modulation means, further comprising; a modulation prohibiting means, prohibiting modulation of the image information supplied from outside by the modulation means when a visible image is formed on an image-recording layer of an optical disk having a recording face on one face and the image-recording layer on the other face; and an image-formation controlling means, controlling the laser beam, when the optical disk is set with the image-recording layer facing the optical pickup, so that a visible image corresponding to the image information not modulated by the modulation means is formed on the

image-recording layer of the optical disk. [0083]
In the configuration (8), it is possible to form a visible image corresponding to image data by irradiating the image-recording layer of optical disk with a laser beam according to the image data, because the reflectivity of the image-recording layer changes imagewise according to changes in the absorbance of the image-recording layer. The image data is not modulated during formation of the visible image, because the modulation of the recording data by the modulation means is prohibited when information is being recorded on the recording face. Thus, there is no need to install an additional data transfer means for forming a visible image according to the image data, and for that purpose common use of the data transfer means used in recording information on the recording face can made. [0084]
Yet another favorable embodiment of the optical-disk recording apparatus is (9) an optical-disk recording apparatus, recording information by irradiating a recording face of an optical disk with a laser beam, comprising: an optical pick up of irradiating the optical disk with the laser beam; an irradiation-position adjusting means, adjusting the irradiation position on the optical disk of the laser beam irradiated by the optical pickup; and an image-formation controlling means, controlling the optical pickup and the irradiation-position adjusting means so that, when an optical disk having a recording face on one face and an image-recording layer on the other face is set with the image-recording layer facing the optical pickup, a visible image corresponding to image information is formed on the image-recording layer of the optical disk, wherein the image-formation controlling means controls the laser beam irradiated from the optical pickup according to the gradation indicated in the image information. [0085]
In the configuration (9), it is possible to form a visible image corresponding to the image data by irradiating the image-recording layer of optical disk with a laser beam according to the image data, because the reflectivity of the image-recording layer changes imagewise according to changes in the absorbance of the image-recording layer. It is possible during formation of the visible image to control the laser beam at each position (each set of coordinates) on the image-recording layer and form a visible image

with gradations according to the gradations indicated in the image data. [0086]
Yet another favorable embodiment of the optical-disk recording apparatus is (10) an optical-disk recording apparatus, recording information by irradiating a recording face of an optical disk with laser beam, comprising: a rotating means, rotating the optical disk; an optical pickup, irradiating from one face the optical disk rotated by the rotating means with a laser beam, the optical pickup being movable in substantially a radial direction of the optical disk; and a laser-beam-level controlling means, adjusting the laser beam irradiated from the optical pickup when a visible image is formed on the image-recording layer, based on the image data related to the visible image to be formed, the laser-beam-level controlling means adjusting the level of the laser beam irradiated from the optical pickup either to a first intensity, causing substantially no change in the recording and image-recording layers of the optical disk, or to a second intensity, causing substantially no change in the recording layer but causing a change in color in the image-recording layer,. [0087]
In the apparatus (10), it is possible to record information on a recording layer of an optical disk according to the invention by irradiation of a laser beam and form a visible image on an image-recording layer in a similar manner to conventional methods. Further, it is also possible to record information and form an image on one face of an optical disk by irradiation of a laser beam from the same single side, eliminating the tedious operations of turning over and resetting the optical disk by the user. [0088]
The image-forming process of forming an image in the image-recording layer of an optical disk according to the invention is a method of forming a visible image on an image-recording layer formed on the face of an optical disk that is opposite to the recording face by using an optical-disk recording apparatus having an optical pickup, recording information on the recording face of an optical disk by irradiation of a laser beam, wherein the optical pickup controls the irradiated laser beam so that a visible image corresponding to image information is formed on the image-recording layer of the optical disk while the irradiation position of the laser beam from the optical pickup is being moved along a predetermined helical or concentric route. When a region.

containing a predetermined number of sub-regions along the route in each of radial sector regions dividing the optical disk, is called a unit region, the timing of the laser beam irradiated at each sub-region along the route belonging to one of the unit regions is controlled so that by the density of the unit regions the visible image is displayed.
It is possible, by this method, to form a visible image corresponding to the image data by irradiating the image-recording layer of optical disk with laser beam according to the image data, because the reflectivity of the image-recording layer changes imagewise according to changes in the absorbance of the image-recording layer. It is possible during formation of the visible image to control the laser beam at each position (set of coordinates) on the image-recording layer and form a visible image with gradations according to the gradations indicated in the image data. [0089] A. Typical configuration of Optical-disk recording apparatus according to the invention
The optical-disk recording apparatus is an optical-disk recording apparatus recording information by irradiating the recording face of an optical disk with a laser beam that has a function for recording information on the recording face and also a function for forming a visible image corresponding to the image data by irradiating with a laser beam an image-recording layer of an optical disk having an image-recoding layer formed on the face opposite to the recording face. In such an apparatus, it is possible to record a visible image not only on the image-recording layer but also on the recording layer for recording normal digital data, if the optical disk contains a particular colorant. [0090] Example of the configuration of optical-disk recording apparatus
Figure 9 is a block diagram illustrating the configuration of an optical-disk recording apparatus. As shown in Figure 9, the optical-disk recording apparatus 100 is connected to a host personal computer (PC) 110, and has an optical pickup 10, a spindle motor llj a RF (Radio Frequency) amplifier 12, a servo circuit 13, a decoder 15, a control unit 16, an encoder 17, a strategy circuit 18, a laser driver 19, a laser power-controlling circuit 20, a frequency generator 21, a stepping motor 30, a motor driver 31, a motor controller 32, a PLL (Phase Locked Loop) circuit 33, a FIFO (First In First Out) memory 34, a drive pulse-generating unit 35, and a buffer memory 36. [0091]

The spindle motor 11 is a motor rotating and driving the optical disk D on which the data is recorded, and the rotating speed is controlled by the servo circuit 13. In the optical-disk recording apparatus 100 of this embodiment, which operates under the CAV (Constant Angular Velocity) mode, the spindle motor 11 rotates at the constant angular velocity instructed from^ for example, the control unit 16. [0092]
The optical pickup 10 is a unit irradiating the optical disk D, rotated by the spindle motor 11, with a laser beam, and the configuration thereof is shown in Figure 10. As shown in Figure 10, the optical pickup 10 has a laser diode 53, emitting a laser beam B, a diffraction grating 58, an optical system 55 condensing the laser beam B onto the face of the optical disk D, and a light-receiving device 56 receiving the reflected light. [0093]
In the optical pickup 10, the laser diode 53 emits a laser beam B according to the intensity of the drive current supplied from the laser driver 19 (see Figure 9). The optical pickup 10 divides the laser beam emitted from the laser diode 53 into a main beam, an advance beam and a delayed beam by the diffraction grating 58, and converges the three laser beams, via a polarized beam splitter 59, collimator lens 60, a quarter wavelength plate 61, and an object lens 62, onto the surface of the optical disk D. The three laser beams reflected from the surface of the optical disk D are then transmitted through the object lens 62, the quarter wavelength plate 61, and the collimator lens 60, reflected by the polarized beam splitter 59, and sent, via a cylindrical lens 63, into the light-receiving device 56. The light-receiving device 56 outputs a photo-reception signal and this is then supplied via the RF amplifier 12 (see Figure 9), to the control unit 16 and the servo circuit 13. [0094]
The object lens 62 is movable in the optical-axis direction of the laser beam B and in the radial direction of the optical disk D, and is held by a focus actuator 64 and a tracking actuator 65. The focus actuator 64 and the tracking actuator 65 move the object lens 62 in the optical-axis and radial directions respectively according to the focus error signal and the tracking error signal supplied from the servo circuit 13 (see Figure 9). The servo circuit 13 generates the focus error signal and the tracking error signal according to the photo-reception signal supplied from the light-receiving device 56 and

the RP amplifier 12, and performs focus control and tracking control by relocating the
object lens 62 as described above.
[0095]
The optical pickup 10 has a front monitor diode not shown in Figure 10; when the laser diode 53 emits laser beam, a current is generated in the front monitor diode that received the outgoing light, and current is supplied, via the optical pickup 10, to the laser power-controlling circuit 20 shown in Figure 9. [0096]
The RF amplifier 12 amplifies the EFM (Eight to Fourteen Modulation)-modulated RP signal supplied from the optical pickup 10^ and outputs the amplified RF signal to the servo circuit 13 and the decoder 15. During reproduction, the decoder 15 demodulates the EFM-modulated RF signal supplied from the RF amplifier 12 and generates reproduction data. [0097]
An instruction signal from the control unit 16, a FG pulse signal at a frequency corresponding to the rotation speed of the spindle motor 11 supplied from the frequency generator 21, and the RF signal from the RF amplifier 12 are supplied to the servo circuit 13. The servo circuit 13 performs rotation control of the spindle motor 11 and focus control and tracking control of the optical pickup 10, based on these supplied signals. The driving mode of the spindle motor 11, when information is recorded on the recording face of the optical disk D (see Figure 1) or a visible image is formed on the image-recording layer of the optical disk D (see Figure 1), may be a CAV (Constant Angular Velocity) mode of driving the optical disk D at a constant angular velocity, or a CLV (Constant Linear Velocity) mode of driving the opticaPdisk at a constant recording linear velocity. The optical-disk recording apparatus 100 shown in Figure 9 and below is operated under the CAV mode, in which the servo circuit 13 rotates the spindle motor 11 at the constant angular velocity instructed by the control unit 16. [0098]
The buffer memory 36 stores the information to be recorded on the recording face of the optical disk D (hereinafter, referred to as recording data) supphed from the host PC no and the information corresponding to the visible image to be formed on the image-recording layer of optical disk D (hereinafter, referred to as image data). The

recording data stored in the buffer memory 36 are outputted to the encoder 17, while the
image data to the control unit 16.
[0099]
The encoder 17 EFM-modulates the recording data supplied from the buffer memory 36 and outputs the modulated data to the strategy circuit 18. The strategy circuit 18 performs time-base compensation of the EFM signal supplied from the encoder 17 and outputs the corrected data to the laser driver 19. [0100]
The laser driver 19 drives the laser diode 53 of the optical pickup 10 (see Figure 10) with a signal modulated according to the recording data supplied from the strategy circuit 18 under the control of the laser power-controlling circuit 20. [0101]
The laser power-controlling circuit 20 controls the power of the laser irradiated from the laser diode 53 in the optical pickup 10 (see Figure 10). Specifically, the laser power-controlling circuit 20 controls the laser driver 19 to make the optical pickup 10 emit a laser beam at the optimal laser power instructed by the control unit 16. The laser power control in the laser power-controlling circuit 20 is a feedback control for controlling a laser beam from the optical pickup 10 at a desirable intensity by using the current supplied from the front monitor diode in optical pickup 10. [0102]
The image data, supplied from the host PC 110 £uid stored in the buffer memory 36, are sent via the control unit 16 to the FIFO memory 34 and stored therein. The image data stored in the FIFO memory 34^ i.e., the image data supplied from host PG 110 to the optical-disk recording apparatus 100, contain the following information. The image data are data for forming a visible image on the surface of the disk-shaped optical disk D, and include information on the density of each of the n set of coordinates (shovvn as black spots in the Figure) on each of the multiple concentric circles around the center O on the optical disk D, as shown in Figure 11, The image data are data including information on the density at these set of coordinates , from the sets of coordinates Pll, P12...Pln on the innermost circle, the sets of coordinates P21, P22.. .2n on the next circle, the sets of coordinates on the next circle, to sets of coordinates up to Pmn on the outermost circle; and the information containing the

density at respective sets of coordinates is sent to the FIFO memory 34 in the above sequence. Figure 11 is a schematic view illustrating the geographic relationship among the sets of coordinates, and actual sets of coordinates are placed at a density much denser than that shown in the Figure. When the image data for forming an image on the photosensitive face of the optical disk D are formed with common bitmap fonts in the host PC 110, the bitmap data are preferably converted to the data in polar coordinate form, and the converted image data are transmitted from the host PC 110 to the optical-disk recording apparatus 100. [0103]
As described above, a clock signal for image recording is supplied from the PLL circuit 33 to the FIFO memory 34 when a visible image is formed on the image-recording layer of optical disk D based on the image data supplied. Upon reception of the clock pulse of the clock signal for image recording, the FIFO memory 34 outputs the information on the gradation of the set of coordinates stored earliest, to the drive pulse-generating unit 35. [0104]
The drive pulse-generating unit 35 generates a drive pulse for controlling the timing of the laser-beam irradiation from the optical pickup 10 and the like. The drive pulse-generating unit 35 then generates a drive pulse at a pulse width corresponding to the information on the gradation of each set of coordinates supplied from the FIFO memory 34. For example, a drive pulse having a larger pulse width at the light level (second intensity) as shown in Figure 12A is generated when the gradation at a set of coordinates is relatively large (higher density), while a drive pulse having a smaller pulse width at the light level when the gradation of the set of coordinates is relatively small, as shown in Figure 12B. The light level is a power level at which irradiation of the laser beam causes change in the image-recording layer of optical disk D and thus in reflectivity thereof, and, when such a drive pulse is supplied to the laser driver 19, a laser beam at the light level is irradiated from the optical pickup 10 for the period according to the pulse width. Thus, a laser beam at the light level is irradiated for a longer period when the gradation is larger, and the reflectivit)' of the image-recording layer of optical disk D changes in the greater region of a unit region, and consequently, the users recognize visually that the region is a region higher in density. In the present

embodiment, the density of the image data is displayed by making the length of the region where the reflectivity is changed per unit region (per unit length) variable. The servo level (first intensit)^ is a power level at which irradiation of the laser power causes almost no change in the image-recording layer of the image-recording layer of optical disk D, and a laser beam at the servo level is irradiated, instead of the laser beam at the light level, to the region where no change in the reflectivity is required, [0105]
The drive pulse-generating unit 35 generates a drive pulse according to the information indicating the gradation of respective sets of coordinates described above, and, independently of the information indicating the gradation, inserts a pulse at the light level or at the servo level for a very short period, if needed, for laser power control by the laser power-controlling circuit 20 and for focus control and tracking control by the servo circuit 13. For example, as shown in Figure 13A5 if a laser beam at the light level should be irradiated for a period of Tl for displaying a visible image according to the gradation at a set of coordinates in the image data and the period Tl is longer than the servo cycle ST predetermined for control of the laser power, a servo system-ofF pulse (SSPl) for a very short period t is inserted at the point when the servo cycle ST elapsed after the pulse at the light level is generated. On the other hand, as shown in Figure 13B, if it is necessary to irradiate a laser beam at the servo level for a period of servo cycle ST or more to display a visible image according to the gradation at a set of coordinates in the image data, a servo system-on pulse (SSP2) is inserted at the point when the servo cycle ST elapsed after the pulse at the servo level is generated. [0106]
As described above, the laser power control by the laser power-controlling circuit 20 is performed based on the current supplied from the front monitor diode (corresponding to the intensity of the irradiated laser beam) that receives the laser beam irradiated from the laser diode 53 in optical pickup 10 (see Figure 10). More specifically, as shown in Figure 14. the laser power-controlling circuit 20 sample-holds the value corresponding to the intensity of the irradiated laser beam detected by the front monitor diode 53a (S201 and S202). Based on the result of a sample held when a laser beam is irradiated at a light level of desired value (Ai), i.e., when a drive pulse at the light level is generated (see Figures 12 and 13), the laser power-controlling circuit 20 performs

laser power control (S203); so that the laser beam is irradiated at the light level of the desirable value supplied from the control unit 16. Alternatively, the laser power-controlling circuit 20 performs laser power control, to make the laser beam irradiated at the servo level of the desirable value supplied from the control unit 16 (S204), based on the result of sample held when a laser beam is irradiate at the servo level of desired value (As)^ i.e., when a drive pulse at the servo level is generated (see Figures 12 and 13). Thus, if the pulse at the light or servo level is not outputted for a period longer than a particular servo cycle ST (sample cycle), it is possible to perform the laser power control at each level by forcibly inserting a servo sy stem-off pulse SSPl or a servo system-on pulse SSP2, independently of the content of the image data as described above. [0107]
As described above, insertion of the servo system-off pulse SSPl is not only for control of the laser power, but also for focus control and tracking control by the servo circuit 13. The tracking and focus control is performed, based on the RF signal detected by the light-receiving device 56 in optical pickup 10 (see Figure 10), i.e., the retum light (reflected light) from the optical disk D of the laser beam irradiated from the laser diode 53. Figure 15 shows an example of a signal detected by the light-receiving device 56 when a laser beam is irradiated. As shovra in Figure 15, the reflected light when a laser beam at the light level is irradiated contains two components, a peak region Kl immediately after irradiation of laser beam and a shoulder region K2 where the hght level is stabilized, and the hatched region in the Figure can be considered to be the energy used for forming an image in the image-recording layer. The energy used for forming an image in the image-recording layer is not always a stable value, and seems to fluctuate according to various conditions. Thus, the shape of the hatched region in the Figure seems to vary every time, and thus, it is not always possible to obtain stabilized reflected light from the laser beam at the light level, because the reflected light contains a lot of noise, and use of such a reflected light may inhibit accurate focus control and tracking control. Accordingly, as described above, if a laser beam at the light level is irradiated continuously for an long period it is not possible to obtain the reflected light of the laser beam at the servo level and consequently to perform accurate focus control and tracking control.

For that reason, as described above, the reflected light of the laser beam at the servo level is obtained periodically by inserting a servo system-off pulse SSPl, and the focus and tracking control is performed based on the obtained reflected light. Unlike when recording in the recording layer, it is not necessary to trace the previously formed pregrooves (guide grooves) or the like when a visible image is formed on the image-recording layer of optical disk D. Thus, in the present embodiment, the desired tracking control value is a fixed value (fixed offset voltage). Such a control method is applicable not only for formation of image information on an image-recording layer but also for forming image information on a recording face.
That is, it is possible to form an image on the recording face, similarly to on the image-recording layer, by using a material that changes its reflectivity as well as color when a laser beam is irradiated, as the material for the recording face (recording layer). When a visible image is formed on the recording face, it is not possible to use the region where the visible image is formed for its primary purpose, data recording, and thus^ it is preferable to separate in advance a data-recording region and a visible image-forming region. [0109]
As described above, the insertion time of the servo system-off pulse SSPl or the servo system-off pulse SSP2 is preferably as short as possible without impairing the various servo controls such as laser power control, tracking control or focus contro,; and a shortened insertion period allows the various servo controls above to be undertaken almost without adverse influence on the visible image formed. [0110]
Back in Figure 9, the PLL circuit (signal output means) 33 multiplies the FG pulse signal at a frequency corresponding to the rotational velocity of spindle motor 11 supplied from the frequency generator 21, and outputs a clock signal for use in forming a visible image described below. The frequency generator 21 outputs an FG pulse signal at a frequency corresponding to the spindle rotating speed by using the back electromotive force obtained by the motor driver of spindle motor 11. For example, as shown in the top line of Figure 16, when the frequency generator 21 generates eight FG pulses during one rotation of the spindle motor H, i.e., during one rotation of the optical

disk D, as shown in the bottom line of Figure 16, the PLL circuit 33 outputs a clock signal amplified from the FG pulse (e.g., five times larger in frequency than the FG pulse signals, 40 pulses at the H level during one rotation of the optical disk D), that is it outputs a clock signal at a frequency corresponding to the rotational velocity of the optical disk D driven by the spindle motor 11. Thus, a clock signal amplified from the FG pulse signal is outputted from the PLL circuit 33 to the FIFO memory 34, and data indicating the gradation at one set of coordinates is outputted from the FIFO memory 34 to the drive pulse-generating unit 35 at every cycle of the clock signal, that is for every rotation of the disk D of a certain angle. The clock signal amplified from the FG pulse may be generated in the PLL circuit 33 as described above, but, when a motor with sufficiently stabile rotation and drive performance is used as the spindle motor 11, the clock signal amplified from the FG pulse, i.e., the clock signal at a frequency corresponding to the rotational velocity of the optical disk D, may be generated in a crystal oscillator, which is installed replacing the PLL circuit 33. [0111]
The stepping motor 30 is a motor that moves the optical pickup 10 above the optical disk D in the radial direction of the optical disk D. The motor driver 31 drives the stepping motor 30 to rotate an amount corresponding to the pulse signal supplied from the motor controller 32. The motor controller 32 generates a pulse signal of a traveling distance and traveling direction, according to the travel-initiation instruction, including the traveling direction and traveling distance in the radial direction of the optical pickup 10, instructed from the control unit 16, and outputs the pulse signal to the motor driver 31. The laser-beam irradiation position of the optical pickup 10 can thus be moved freely to various positions of the optical disk D, by the optical pickup 10 being moved by the stepping motor 30 in the radial direction of the optical disk D and the optical disk D being rotated by the spindle motor 11, and thus, these components constitute the irradiation-position adjusting means. [0112]
The control unit 16 consists of a CPU (Central Processing Unit), a ROM (Read Only Memory) and a RAM (Random Access Memory), and others, and controls respective units in the optical-disk recording apparatus 100 and integrally controls recording on the recording face of optical disk D and image forming on the

image-recording layer of optical disk D according to the program stored in the ROM.
The configuration of the optical*disk recording apparatus 100 in the present
embodiment configuration has been described above.
[0113]
B. Operation of Optical-disk recording apparatus
Hereinafter, the operation of the optical-disk recording apparatus 100 in the configuration above will be described. As described above, the optical-disk recording apparatus 100 is configured to record information such as audio data supplied from the host PC 110 on the recording face of an optical disk D and form a visible image corresponding to the image data supplied from the host PC 110 on the image-recording layer of the optical disk D. Hereinafter, the operation of the optical-disk recording apparatus 100 allowing processing such as information recording or visible image forming will be described with reference to Figures 17 and 18. [0114]
When an optical disk D is placed in the optical-disk recording apparatus 100, the control unit 16 examines the format of the face of the placed optical disk D facing the optical pickup 10^ by controlling the optical pickup 10 and and the like. For example, it detects presence or absence of a land pre-pit signal or prerecord signal in the case of DVD-R, and an ADIP (Address in Pregroove) in the case of DVD+R. If such information is not recorded, the disk is not recognized as an optical disk. [0115]
When there is a land pre-pit signal or a prerecord signal in the case of DVD-R, or an ADIP in the case of DVDH-R, detected from the placed optical disk D, the control unit 16 judges that the optical disk D is placed with its recording face facing the optical pickup 10 and performs control for recording the recording data supplied from the host PC 110 on the recording face (step Sa2). The control for recording the recording data is the same as that for recording data on conventional optical-disk recording apparatuses (DVD-R and DVD+R drive apparatuses), and the description thereof is omitted. [0116]
On the other hand, when there is no pre-pit signal indicating that the optical disk is writable detected from the placed optical disk D, the control unit 16 judges that the optical disk D is placed with its image-recording layer facing the optical pickup 10,

and examines whether it is possible to obtain a disk ID from the optical disk D (step Sa3). The disk ID of the optical disk D may be stored in a pre-pit signal. Also, for example as shown in Figure 19, a visible image corresponding to the coded disk ID information can be written in advance on the outermost circle on the image-recording layer of optical disk D. As shown in Figure 19, the disk ID is written on the outermost circle in the image-recording layer of optical disk D, by forming reflecting regions 301a and non-reflecting regions 301b, each at a length corresponding to the code above. The control unit 16 obtains the disk ID, by changing the laser-beam-irradiation position of the optical pickup 10 to along the outermost circle on optical disk D and examining its reflected light. [0117]
Thus, if there is no reflecting regions 301a and non-reflecting regions 301b corresponding to the disk ID formed on the outermost surface region of the image-recording layer, the optical disk D judges that the disk placed is a general purpose optical disk (CDR, DVD-R, or the like) having no image-recording layer. When there is no disk ID obtained, the control unit 16 judges that the disk D is an optical disk prohibiting visible image formation (step Sa4), and notifies the fact to the user. [0118]
Altematively if there is a disk ID obtained from the optical disk D, the control unit 16 waits until an image-forming instruction, containing image data, is sent from the host PG 110 (step Sa5); and, when there is an image-forming instruction, the control unit 16 performs control for preparation of forming a visible image on the image-recording layer of optical disk D (step Sa6). More specifically, the control unit 16 controls the servo circuit 13 to rotate the spindle motor 11 at a particular angular velocity, and drives the stepping motor 30 by sending an instruction for moving the optical pickup 10 to the initial position, i.e., at the innermost position in the radial direction of the optical disk D, to the motor controller 32. [0119]
In the initialization control for image formation, the control unit 16 may instruct, to the servo circuit 13, a desired focus-control value to make a laser beam having a beam spot diameter larger than that when information is recorded on the recording face irradiated on the image-recording layer of optical disk D.

I ; ; !
\ {^ V.' i
The focus control performed, as described above, when such a desi! instructed is now described more specifically. The focus control by the ser is performed, based on the signal outputted from the light-receiving device 'f> lu ; .! \, pickup 10. When information is recorded on the recording face of optical di-k 11 \\w servo circuit 13 (see Figure 10) drives the focus actuator 64, to make a circular i liirn light focus (indicated by A shown in Figure 20) at the center of four areas ^'M "f >^ 56c, and 56donthe light-receiving device 56. Specifically, it controls the loca: aeniah.; 64 to make the value (a+c)-(b+d)=05 wherein the light-receiving intensities m iln ai^ a 56ei, 56b, 56c, and 56d are designated respectively as a, b, c, and d. [0121]
On the other hand, when a visible image is formed on the image-rec* )]\\\ny. layer of optical disk D, the focus control is performed to make a laser beam )ia\UIL a diameter larger than that when information is recorded on the recording lace n i adiaied on the image-recording layer, as described above. When the shape of the rcium 1 ILIII received by the Hght-receiving device 56 shown in Figure 20 is elliptic (indicaicd b\ W and C in Figure 20), the spot size of the laser beam is greater than that in ilic i IK le lui ID A, and thus, the servo circuit 13 drives the focus actuator 64 to make such an eihiMu return light received by the Ught-receiving device 56, Specifically, it drives tlu locus actuator 64 to make the hght-receiving intensities satisfy the equation (a+c) a b * ^ i (M o is not 0). Thus, in the present embodiment, the control unit 16 and the ser\ (»(irejui 1 ■> constitute the beam-spot controlling means. [0122]
As described above, in the initialization control for forming a visible m la^^ described above, if the control unit 16 instruct a (not 0) to the servo circuii 1 ■ ii ; possible to make a laser beam having a spot size larger than that when in ion i.. 111 ^ a; s recorded on the recording face irradiated on the image-recording layer of < -pi i. .! I' i. I)
f V T
By irradiating a laser beam having a spot size larger than that \\lir. a information is recorded on the recording face in this manner when a ^ isibi. a i a : i formed on the image-recording layer of optical diskD, it is possible lo obaaa i; following advantageous effects. Namely in the present embodiment. \^ image is formed, a laser beam is irradiated as the optical disk D

when information is recorded on the recording face. Thus, by expanding the beam spot size of the laser beam, it is possible to form a visible image on the entire region of the image-recording layer of optical disk D in a shorter period of time. The reason will be described hereinafter with reference to Figures 21A and 2IB, As shovm schematically in Figures 21A and 218^ the area of image-forming region in one rotation of the optical disk D is larger when the beam spot diameter BS of the laser beam irradiated is larger (Figure 21 A) than when it is smaller (Figure 2IB). Accordingly, when the beam spot diameter BS is smaller, it is necessary to rotate the optical disk D more times and thus, demands a longer period to form an image on the entire region (4 rotations with the beam with greater BS, vs. 6 rotations with the beam with smaller BS in the Figure). For the reason above, a laser beam having a spot diameter larger than that when information is recorded on the recording face is irradiated in the optical-disk recording apparatus 100 when a visible image is formed. [0123]
In the initialization control for image forming, the control unit 16 instructs desired values of the light and servo levels to the laser power-controlling circuit 20 to make laser beams irradiated from the optical pickup 10 at the light level and the servo level suitable for capturing disk ID. The ROM in control unit 16 stores the desired values of the light and servo levels for multiple kinds of disk ID's, and the control unit 16 reads out the desired values of the hght and servo levels corresponding to the captured disk ID and instructs these desired values to the laser power-controlling circuit 20. [0124]
The desired power values are allocated according to the disk ID, because of the following reasons. The properties of the colorant in the image-recording layer may vary according to the kind of the optical disk D used, and if the properties are different, then naturally the relationship between the intensity of the laser beam irradiated and the reflectivity also changes. As a result, even if it is possible to change the reflectivity of the irradiation region sufficiently by irradiating an image-recording layer of a particular optical disk D with a laser beam at a particular light level, it is not necessarily possible to change the reflectivity of the irradiated region when a laser beam at the same light level is irradiated on the image-recording layer of another optical disk D. Thus in the

present embodiment, as described above desired values of the light and servo levels favorable for accurate image forming are determined in advance by experiment for optical disks corresponding to each disk ID. By storing the determined desired values corresponding to each disk ID in the ROM, it is possible to control the power optimally according to the properties of the image-recording layer of optical disk D. [0125]
When the initialization control described above is performed by the control unit 16, forming of a visible image on the image-recording layer of optical disk D can be carried out. As shown in Figure 18, the control unit 16 first transfers the image data supplied from the host PC 110 via the buffer memory 36 to the FIFO memory 34 (step Sa7). The control unit 16 then judges whether a predetermined reference position of the optical disk D rotated by the spindle motor 11 has passed the laser-beam irradiation position of the optical pickup 10 from the FG pulse signal supplied from the frequency generator 21 (step Sa8), [0126]
The method of detecting the particular reference position and whether it passed the laser-beam irradiation position will be described hereinafter^ with reference to Figures 22 and 23. As shovra in Figure 15, the frequency generator 21 outputs a certain number of FG pulses (8 in the example of Figure 22) during one rotation of the spindle motor 11, i.e., one rotation of the optical disk D. Thus, the control unit 16 outputs a reference position-detecting pulse, synchronized with the start-up timing of any one of the FG pulses supplied from the frequency generator 21 ^ as a reference pulse, and then, generates a reference position-detecting pulse signal for outputting the reference position-detecting pulse, synchronized with the start-up timing of the pulse that is the number of pulses of one rotation after the reference position-detecting pulse (the eighth pulse in Figure 22), By generating such reference position-detecting pulses, it is possible to judge that the laser-beam irradiation position of optical pickup 10 passes through the reference position of optical disk D when the pulse is generated. Thus as shown in Figure 23, if the laser-beam irradiation position of optical pickup 10 at the timing of the first reference position-detecting pulse generated is as shown by the thick line in Figure 23 (the irradiation position is shown as a line because the optical pickup 10 is movable in the radial direction), then when the reference position-detecting pulse

IS generatea arter one rotation, tne laser-Deam irraaiaiion posmon oi optical picKup lu is, of course, on the thick line in Figure 23. The line in the radial direction of the laser-beam irradiation position at the timing when the first reference position-detecting pulse is generated represents the reference position; and as described above, the control unit 16 detects that the laser-beam irradiation position passes the reference position of optical disk D, based on the reference position-detecting pulse signal generated in every rotation of the optical disk D. The dotted line in Figure 23 shows an example of the traveling locus of the laser-beam irradiation position during a period from when one reference position-detecting pulse is generated to when the next reference position-detecting pulse is generated. [0127]
When the control unit 16 detects, according to the method above, that the reference position of optical disk D passes the laser-beam irradiation position after receiving an image-forming instruction from the host PC 110, it increments the parameter R by 1, indicating the number of rotatations (step Sa9), and then, judges whether R is an odd number (step SalO). [0128]
When the position of optical disk D passes the laser-beam irradiation position for the first time after reception of the image-forming instruction, the value R is 0 (initial value)+l=l, and in such a case, R is judged to be an odd number in step SalO. When R is found to be an odd number, the control unit 36 controls the optical pickup 10 to form a visible image on the image-recording layer of optical disk D by irradiation of the laser beam (step Sail). More specifically, from the time of receipt of the reference position-detecting pulse^ the control unit 16 controls respective units to output image data from the FIFO memory 34 one by one in synchrony with the clock signal outputted from the PLL circuit 33.
As shovm in Figure 24, by the control, the FIFO memory 34 outputs information indicating the density of one set.of coordinates to the drive pulse-generating unit 35 whenever the clock pulse is supplied from the PLL circuit 33, and the drive pulse-generating unit 35 generates a drive pulse having a pulse width according to the density shown in the information and outputs it to the laser driver 19, As a result, the optical pickup 10 irradiates laser beam on the image-recording layer of optical disk D at

the light level for a period corresponding to the density of each set of coordinates, and forms a visible image similar to that shown in Figure 25 by the change in reflectivity in the irradiation region. [0129]
As shown schematically in the Figure, because the optical disk D is rotated by the spindle motor 11, the laser-beam irradiation position of the optical pickup 10 travels along the circle for the region C shown in the Figure per cycle of clock signal (period from a start-up timing to the next start-up timing of the pulse). By changing the period of the laser beam irradiated at the light level according to the density during the laser-beam irradiation position passes through the region C as described above, it is possible to change the reflectivity of different area in each region C according to the different density, as shown in the Figure. Thus by changing the period of the laser beam irradiated at the light level according to the density of each set of coordinates during the laser beam irradiation position passes through the region C, it is possible to form a visible image corresponding to the image data on the image-recording layer of optical disk D. [0130]
As described above, after the control for forming a visible image by irradiating a laser beam according to the image data, the processing in the control unit 16 returns to step Sa7, and the image data supplied from the buffer memory 36 is transferred to the FIFO memory 34. It is then examined whether the laser-beam irradiation position of optical pickup 10 passes the reference position of optical disk D, and, if it passed the reference position, one is added to R, When R becomes an even number as a result, the control unit 16 controls respective units in the apparatus, to terminate visible image formation by the laser-beam irradiation control described above (step Sal2). More specifically, it controls the FIFO memory 34 so as not to undertake the output of the information, indicating the gradation of each set of coordinates in synchrony with the clock signal supplied from the PLL circuit 33, to the drive pulse-generating unit 35. Thus, the control unit 16 prohibits the laser-beam irradiation from causing change in the reflectivity of the image-recording layer during the period after one rotation of the disk D during which a visible image is formed by irradiation of a laser beam at the light level on the image-recording layer of optical disk D.

When the laser-beam irradiation for forming a visible image is terminated, the control unit 16 instructs the motor controller 32 to relocate the optical pickup 10 outward in the radial direction by a certain distance (step Sal3); the motor controller 32 drives the stepping motor 30 via the motor driver 31 according to the instruction; and the optical pickup 10 is relocated outward by the certain distance. [0132]
The certain distance of the optical pickup 10 being relocated in the radial direction of the optical disk D may be determined properly according to the beam spot diameter BS of the laser beam irradiated from the optical pickup 10 (see Figure 21), as described above. When a visible image is formed on the image-recording layer of disk-shaped optical disk D, it is necessary to make the laser-beam irradiation position of optical pickup 10 travel over almost the entire face of the optical disk D, without leaving gaps, in order to obtain a higher*quality image. Thus by making the unit traveling distance of the optical pickup 10 in the radial direction substantially identical to the beam spot size BS of the laser bean irradiated on the optical disk D, it is possible to irradiate the laser beam almost entirely all over the face of the optical disk D and obtain a higher-quality image. Occasionally, color develops in a region greater than that of the beam spot diameter of the laser beam irradiated, depending on various factors including the properties of the image-recording layer, and in such a case, the unit traveling distance is decided while considering the width of the coloring region, so that neighboring coloring regions do not superimpose.
In the present embodiment, the beam spot diameter BS is set to a value larger than that for recording on the recording face (for example, approximately 20 |im), and thus, the control unit 16 controls the motor controller 32 and drives the stepping motor 30 to make the optical pickup 10 travel in the radial direction to a distance almost identical to that of the beam spot diameter BS. Many recent stepping motors 30 allow control of the traveUng distance at units of 10-|j.m by using microstepping technology, and thus, it is sufficiently practical to make the optical pickup 10 travel in the radial direction at the 20-|im unit by using a stepping motor 30. as described above. [0133]
After control for relocation of the optical pickup 10 in the radial direction by a

certain distance, as described above, the control unit 16 then instructs the desirable light level value at which the laser beam at the light level is to be irradiated after change to the laser power-controlling circuit 20, to alter the desirable light level of the laser beam therein (step Sal 4). In the present embodiment, the visible image is formed in the CAV mode of irradiating laser beam, while the optical disk D is rotated at a constant angular velocity, and, as described above, relocation of the optical pickup 10 toward external surface results in an increase in the linear velocity. Thus, when the optical pickup 10 is relocated outward in the radial direction (to the external surface), as described above, the desirable value at the light level of the laser beam is increased from that before; and a laser power at an intensity sufficient for changing the reflectivity of the image-recording layer of optical disk D is irradiated, even though the linear velocity varies. [0134]
After control for moving the optical pickup 10 outward in the radial direction and the change of the desirable value at the light level, as described above, the control unit 16 judges whether there is not-yet-processed image data, i.e., image data not supplied to the drive pulse-generating unit 35, for visible image forming, and if there is no such image data, the processing thereby is terminated, [0135]
On the other hand, if there is not-yet-processed image data not yet supplied to the motor controller 32, the processing goes back to step Sa7, and the processing for forming a visible image is continued. The image data is transferred from the control unit 16 to the FIFO memory 34 (step Sa7); and it is judged whether the laser-beam irradiation position passes the reference position of optical disk D (step Sa8). If it passes the reference position, one is added to the variable R indicating the number of rotations (step Sa9); and it is judged whether the R after addition is an odd number (step SalO). If R is an odd number, the control unit 16 controls respective units of the apparatus to from a visible image by irradiating a laser beam; and if R is an even number, it terminates the laser-beam irradiation for forming a visible image (still irradiating a laser beam at the servo level), and perform control for moving the optical pickup 10 outward in the radial direction and for changing the desirable value at the light level. When laser-beam irradiation for image formation (including at the light level) is performed on

the optical disk D in one particular revolution, the control unit 16 controls so as not to perform laser-beam irradiation for image formation in the next revolution, but to make the optical pickup 10 move outward in the radial direction in that revolution. Thus by controlling so as not to perform laser-beam irradiation for image formation in the next revolution so as to make the optical pickup 10 move outward in the radial direction in that revolution, it is possible to perform laser-beam irradiation for image formation without image formation during changing the irradiation radial position and changing the intensity of the irradiated laser beam associated with the control, and image formation can be carried out when the irradiation position and the intensity of laser beam are stabilized. It is thus possible to prevent deterioration in the quality of the visible image due, for example, to control for moving the optical pickup 10 outward in the radial direction. [0136]
So far described is the primary operation of the optical-disk recording apparatus 100, and it is possible to form a visible image corresponding to the image data by irradiating the image-recording layer of an optical disk D with a laser beam in the optical-disk recording apparatus 100, by making the best use of the optical pickup 10 and the like, for use in recording information on the recording face, without using an additional printing means or the like. [0137]
Because the laser-beam irradiating timing is controlled, based on the clock signal generated by using the FG pulse generated according to the rotation of the spindle motor 11, i,e., the clock signal generated according to the amount of rotation of the optical disk D in the present embodiment, it is possible to determine the laser-beam irradiation position in the optical-disk recording apparatus 100, without obtaining, for example, positional information from the optical disk D side. As a result, the optical-disk recording apparatus 100 is free from restrictions demanding a specially-finished optical disk D such as having pregrooves (guide grooves) for the image-recording layer, and it is possible to form a visible image corresponding to the image data even on an image-recording layer having no pregroove or position information formed in advance. [0138]

Hereinafter, the method of recording information (digital information) on the information-recording layer will be described. When the information-recording layer is a layer containing a colorant, the unrecorded optical disk described above is exposed to laser beam from a laser pickup while rotated at a predetermined recording linear velocity. The colorant in the information-recording layer absorbs the irradiation beam, causing a local rise in temperature and formation of the desired bits, and information is recorded by the associated change in optical properties. [0139]
The recording waveform of the laser beam may be a pulse train or a single pulse for forming a single pit. The length ratio of the information to be actually recorded (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 of the information to be actually recorded. When the recording waveform is a pulse train, the sum of the pulses is in the range above. [0140]
The power of the laser beam may vary according to the recording linear velocity, but is preferably, when the recording linear velocity is 3.5 m/s, in the range of 1 to 100 mW, more preferably in the range of 3 to 50 mW, and still more preferably in the range of 5 to 20 mW. Alternatively when the recording linear velocity is twice that, the power of the laser beam is preferably 2 times that of the preferable ranges above, [0141]
The NA of the objective lens used in the pickup is preferably 0.55 or more, more preferably 0.60 or more, for improvement in recording density. [0142]
In the invention, a semiconductor laser having an oscillation wavelength in the range of 350 to 850 nm as recording beam is favorably used. [0143]
Hereinafter, a case where the information-recording layer is a phase-change layer will be described. The phase-change layer, which is prepared from the materials described above, can undergo repeated phase changes between crystalline and amorphous phases by laser irradiation.

During information recording, gathered laser-beam pulses are irradiated for a short period, partly melting the phase-change recording layer. The melted region is rapidly chilled by thermal diffusion, and solidifies, leaving a recorded mark in the amorphous state. Alternatively, during erasure, the recorded mark region is heated to a temperature not lower than the crystallization temperature and not higher than the melting point of the information-recording layer by irradiation of laser beam, and then cooled gradually, crystallizing the recorded mark in the amorphous state back to the unrecorded state.
[0144]
EXAMPLES
Hereinafter, the present invention will be described in detail with reference to the Examples, while it should be understood that the invention is not limited to these Examples. [0145] Example 1
Example 1 relates to an optical disc formed by adhering a first lamination body and a second lamination body. The method of preparing the optical disc will be described below.
A substrate (first substrate) of 0.6 mm in thickness and 120 mm in diameter having a spiral groove (depth: 130 nm, width: 300 nm, and track pitch: 0.74 ^im) was prepared by injection molding of a polycarbonate resin. After preparation of a coating hquid (1) by dissolving 1.50 g of the following dye (A) in 100 ml of 2,2,33-tetrafluoro-l-propanol, an information recording layer was prepared by applying the coating liquid (1) onto the grooved surface of the substrate by spin coating. Then, a first reflection layer of silver having a film thickness of 120 nm was formed on the information recording layer by sputtering. The first lamination body was thus prepared. [0146] Dye (A)


Subsequently, a substrate (second substrate) of 0.6 mm in thickness was
prepared by injection molding using a stumper having no spiral groove. Further, a
coating liquid (2) containing 1.40 g of the following dye (B) and 0.60 g of the following
dye (C) in 100 ml of 252353-tetrafluoro-l-propanol was prepared. An image-recording
layer having a thickness of 0.1 ^m was then formed, by applying the coating liquid (2)
onto the second substrate by spin coating. Then, a second reflection layer of silver
having a film thickness of 80 nm was formed on the image recording layer by sputtering.
The second lamination body was thus prepared.
[0148]
Dye (B) Dye (C)
N
(n)C4H9
o

o

-IS02NH(CH2)30CH(CH3)2)n

CI04'

[0149]
Subsequently, in order to adhering the first lamination body and the second lamination body so as to form an optical disc, following processes were performed. First, a radical-polymerizable UV curing resin (trade name: SD640, manufactured by Dainippon Ink and Chemicals, Inc.) was ejected onto the first reflection layer of the first lamination body, and the side of the first reflection layer of the first lamination body on which the UV curing resin was ejected was adhered to the side of the second reflection layer of the second lamination body. Further, pressure was applied from the side of the second lamination body so as to spread the UV curing resin. Furthermore, the laminated composition was rotated with a high speed so as to spin-off excessive amounts of the UV curing resin by centrifugal force so as to form an adhesive layer (before curing) having a uniform thickness throughout internal to peripheral circumferences. The UV curing resin was then cured by irradiation with ultraviolet light using a high-pressure mercury lamp with UV irradiation output of 1.8 J/cm"^ from the side of the second lamination body so as to form an adhesive layer [0150] Example 2
An optical disc of Example 2 was prepared in the same manner as Example 1 except that the thickness of the second reflection layer was changed to 40 nm.

Example 3
An optical disc of Example 3 was prepared in the same manner as Example 1 except that the thickness of the second reflection layer was changed to 100 nm. [0152] Comparative example 1
A first lamination body of Comparative example 1 was prepared in the same manner as the first lamination body of Example 1, except that: after the formation of the silver reflection layer (the first reflection layer) in the first lamination body, a protective layer was farther provided by coating a UV curing resin (trade name: SD640, described above) onto the first reflection layer by spin coating and irradiating with UV for curing the UV curing resin. Similarly, a second lamination body of Comparative example 1 was prepared in the same manner as the second lamination body of Example 1, except that: after the formation of the silver reflection layer (the second reflection layer) in the second lamination body, another protective layer was fiarther provided by coating a UV curing resin (trade name: SD640, described above) onto the second reflection layer by spin coating and irradiating with UV for curing the UV curing resin.
Subsequently, in order to adhering the first lamination body and the second lamination body so as to form an optical disc, following processes were performed. First, a slow-acting cation-polymerization adhesive (trade name: SDK7000, manufactured by Sony Chemicals Corp.) was printed (applied) onto the first and second protective layers by screen printing. Then, after irradiation with ultraviolet light using a metal halide lamp, the first and second lamination bodies were laminated together via the protective layers, and the resulting disc was pressed from both sides for 5 minutes, to provide an optical disc of Comparative example 1. [0153] Comparative example 2
An optical disc of Comparative example 2 was prepared in the same manner as Example 1 except that the thickness of the second reflection layer was changed to 35 nm. [0154] Comparative example 3
An optical disc of Comparative example 3 was prepared in the same manner as Example 1 except that the thickness of the second reflection layer was changed to 110 nm.

Evaluation
The thus prepared optical discs of Examples 1 to 3 and Comparative Examples
1 to 3 were evaluated by the following tests.
[0156]
Hardening efficiency
The hardening efficiency was evaluated by repeating the test of dropping the optical disk thus prepared onto the floor from a height of 1 m ten times and then, examining separation of the adhesive layer of the optical disk. The results are evaluated according to the following criteria. Evaluation results are summarized in Table 1.
A: No separation after ten drop tests.
B: Separation in ten drop tests.
X: Separation in the first drop test. [0157]
Mechanical properties
The tilts in the radial and tangential directions and the vertical deviation of the optical disk thus prepared were analyzed by using a mechanical property analyzer (DLD-4000, manufactured by Japan EM.). Measurement results are summarized in Table 1. [0158]

CLAIMS
1. A method of forming an optical disc comprising:
Forming a first lamination body comprising a first substrate an information recording layer or pits, and the first reflection layer provided in this order;
Forming a second lamination body comprising a second substrate, an image-recording layer that is capable of undergoing recording of a visible image by irradiation of laser hght, and a second reflection layer having a thickness of 40 to 100 nm provided in this order; and
adhering the first lamination body and the second lamination body so that the first reflection layer provided on the first lamination body and the second reflection layer provided on the second lamination body are faced toward each other across an adhesive layer, wherein:
the adhering comprises hardening a radiation-curing resin so as to form the adhesive layer; and
the hardening comprises irradiating the radiation-curing resin with radiation ray from the side of the second substrate.
2. The method of forming an optical disc according to claim 1, wherein the forming of the second lamination body comprises forming the second reflection layer to have a thickness of in a range of 45 to 90 nm.
3. The method of forming an optical disc according to claim 1, wherein the forming of the second lamination body comprises forming the second reflection layer to have a thickness of in a range of 50 to 80 nm.
4. The method of forming an optical disc according to claim 1, wherein the forming of the second lamination body comprises forming the second reflection layer using silver or a silver alloy.
5. The method of forming an optical disc according to claim 1, wherein the forming of the second lamination body comprises forming the second reflection layer using silver or a silver alloy having 90 wt% or more of silver.
6. The method of forming an optical disc according to claim L wherein the forming of the second lamination body comprises forming the second reflection layer

using silver or a silver alloy having 95 two or more of silver.
7. The method of forming an optical disc according to claim 1, wherein the
forming of the second lamination body comprises forming the second reflection layer
using pure silver.
8. The method of forming an optical disc according to claim 1, wherein an
amount of the radiation applied to the radiation-curing resin is equal to or more than 1
J/cm'.
9. The method of forming an optical disc according to claim wherein the
radiation-curing resin is a radical polymerizable radiation-curing resin,
10. The method of forming an optical disc according to claim 1 wherein the
radiation-curing resin is an acryl ate resin or a methacrylate resin.
11. The method of forming an optical disc according to claim, wherein the
hardening of the radiation-curing resin is conducted by using light having a wavelength
of 350 nm or less,
12. The method of forming an optical disc according to claim 1, wherein an
absorbance of the radiation-curing resin against light having a wavelength of 350 nm or
less is equal to or higher than 15.
13. The method of forming an optical disc according to claim, wherein a
light source of the radiation ray is a flush lamp.