JP2529131B2 - Information recording medium - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an information recording medium capable of reproducing and recording information by light.

[Technical background of the invention] In recent years, information recording media using a high energy density beam such as a laser beam have been developed and put into practical use. This information recording medium is called an optical disc,
It can be used as a disk, an audio disk, and a large capacity still image file and a large capacity computer disk memory. Among these information recording media, compact discs (CDs) have been widely put into practical use for reproducing audio such as music.

A general DRAW (Direct Read After Write, writable) type information recording medium has a disk-shaped transparent substrate made of plastic, glass or the like as a basic structure and a Bi, Sn, In, Te, etc. provided on the transparent substrate. And a recording layer made of a dye such as a metal or metalloid or a cyanine dye.
Writing of information to the recording medium is performed by, for example, irradiating the recording medium with a laser beam, and the irradiated portion of the recording layer absorbs the light and locally rises in temperature, resulting in a physical change such as pit formation. Alternatively, information is recorded by making chemical changes that alter its optical properties. The reading of information from the optical disk is also performed by irradiating the optical disk with a laser beam, and the information is reproduced by detecting the reflected light or the transmitted light according to the change of the optical characteristics of the recording layer.

A compact disc (CD), which is an optical disc for reproducing information, generally has an EFM (Eight
to Fourteen Modulation) A plastic disk-shaped transparent substrate in which holes (pits) having digital audio signal information are formed in advance, and a reflective thin film such as Al and a protective film provided thereon. Reading of information from a CD is performed by irradiating a laser beam to the optical disk, and a CD format signal or the like is read by a change in reflectance depending on the presence or absence of pits. Based on the CD standard, such a CD can be recorded by rotating the CD at a constant linear velocity of 1.2 to 1.4 m / sec for recording.
Pit width 0.8 μ within 45 mm and signal surface outer diameter 116 mm
It is required to have a maximum recording time of 74 minutes at a track pitch of 1.6 μm. Conventionally, such an audio CD is a reproduction-only disc in which pits are formed in advance on the substrate as described above. Further, recently, instead of music information, a CD-ROM (Read Only Memory) in which information such as various documents and still images is recorded in advance has been put into practical use.

Such an optical disc naturally has a drawback that information cannot be recorded or edited. Therefore, DRAW (Direct
Read After Write, writable) type CDs are being developed and some have been put to practical use.

The above DRAW type CD is required to be able to reproduce the recorded information on a commercially available CD player. Since it is necessary for the optical disc to have a high reflectance in order to be played back by a CD player, an optical disc having a high reflectance is desired. The reflectance of both the dye recording layer and the metal recording layer is generally 30.
Since it is as low as about 40%, the dye, which can easily form the recording layer by coating, has a manufacturing advantage over the metal. Therefore, a DRAW type CD in which a dye recording layer and a reflective layer are laminated on a substrate is under study. like this
As an example of a DRAW-type CD, an optical disc having a structure in which a dye recording layer, a reflective layer of Au, and a protective layer are laminated in this order on a polycarbonate substrate is Nikkei Electronics (page 107, 1989).
(Issued January 23, 2004).

Such a DRAW type CD (as well as a conventional DRAW type optical disc) generally has a reproduction area (pit area) and a pit area in which pits as recording information such as address information are formed on the inner peripheral side of the substrate. A pregroove for guiding a laser for recording information has a recording area (groove area) provided on the substrate on the outer peripheral side. Further, recently, an optical disc having both the functions of a reproducing CD and a DRAW-type CD in a single disc has been proposed (Japanese Patent Laid-Open No. Hei.
42652 publication). That is, it is an optical disc having a recording area having a groove on the substrate on the outer peripheral side of a reproducing CD and a ROM area containing information such as music on the inner peripheral side.
This allows the user to record data and notes on the same disc while sharing the same information (music and programs) with other people.

According to the above-mentioned Japanese Patent Laid-Open No. 2-42652, a method of producing an optical disk having a ROM area and a recording area has a substrate diameter of 80 to 117 mm, which corresponds to the outer peripheral side of the reproduction area (ROM area) having the pits of the substrate. Diameter by spin coating to form a dye recording layer on the groove
The recording layer is formed by coating the portion outside 80 mm.
Then, a reflective layer is formed on the ROM area and the recording layer. That is, the recording layer is not formed in the ROM area formed of pits, and the recording layer is provided only in the groove area.

However, the track width (spacing) of pits and grooves is generally about 1.6 μm, and recording (grooves) outside the diameter of 80 mm with grooves as described above.
In order to apply the dye coating liquid only to the area, it is necessary to apply so that the inner peripheral edge of the recording layer is not formed on the track before the pits are provided. That is, since the track width (spacing) is on the micron order as described above, it is necessary to control the coating with extremely high accuracy. Therefore, it is difficult to manufacture the dye recording layer only in the recording area from the boundary between the pit reproduction area and the groove recording area.

[Object of the Invention] As described above, when the dye recording layer is formed by coating on the outer peripheral side of the substrate, for example, by a spin coating method, it is difficult to separate the pit reproducing region and the groove recording region accurately. . Furthermore, according to a study by the present inventors,
Since the inner peripheral edge (peripheral end) of the dye recording layer, which is the coating start position, rises due to surface tension and the layer thickness increases,
Even if the dye recording layer is formed only on the groove on the recording area side of the boundary between the pit reproduction area and the groove recording area, the layer thickness at the inner peripheral edge of the recording layer (that is, near the boundary) increases and the reflectance is increased. It became clear that it was remarkably lowered and it was easy to lose focus (improper focusing). When the focus is lost, the reproduction signal cannot be obtained, so that the reproduction is stopped or the runaway occurs. Of course, you can no longer track.

The applicant has already applied for an information recording medium that solves the above problems (Japanese Patent Application No. 2-218704). The present invention offers another alternative solution.

When the present inventors further investigated the above problems, when the dye coating solution was applied on the groove, when applied on the pit, and when applied on the mirror, the inner peripheral edge of the coating layer was It has become clear that it is formed into a planar shape as shown in a), b) and c) of FIG. FIG. 3 is a partial plan view showing the shape of the peripheral edge of the recording layer when the dye recording layer is formed on the substrate of which the surface is a) groove, b) pit, and c) mirror.

That is, the dye coating layer (D) formed on the substrate having the groove (G) and the land (L) is a) in FIG.
, The inner peripheral edge portion is formed along the groove in a shape with a high roundness, that is, in a uniform arc shape. Of course, in this peripheral portion, the layer thickness of the dye layer becomes thick and the reflectance becomes low. Therefore, focusing failure tends to occur (the jump area cannot be jumped).

The dye coating layer (D) formed on the substrate having the pits (P) is on the same track because its inner peripheral edge is formed not along the track as shown in FIG. 3 b). Some pits are covered with the dye layer and some are not, so that the layer thickness and shape of the dye layer are non-uniform. However, since the pit and the mirror portion coexist in the pit area, the reflectance is relatively high.

As shown in FIG. 3 (c), the dye coating layer (D) formed on the substrate whose surface is the mirror (M) does not have its inner peripheral edge along the track and the layer thickness and shape of the dye layer are It is uneven. However, unlike the pit and groove portions, the mirror portion has a high reflectance, but since the mirror portion cannot perform tracking, continuous reproduction from the reproduction area to the recording area is generally impossible.

As described above, when the dye recording layer is formed by coating on the groove, the layer thickness of the dye layer becomes thicker at the peripheral portion thereof, the reflectance remarkably decreases, and focusing failure tends to occur (the jump region cannot be jumped). Further, in the mirror section, continuous reproduction from the reproduction area to the recording area is generally impossible. Further, when the inner peripheral edge of the dye layer is present on the pit, good focusing can be obtained because the reflectance is relatively high, but the inner peripheral edge of the dye layer can be seen from FIG. 3 b). So uneven. For this reason, it is necessary to make a large area that cannot be recorded, which is disadvantageous in terms of high density recording.

Therefore, it is an object of the present invention to provide an information recording medium which is an optical disc having a reproduction area and a recording area, has good focusing, and is free from tracking errors and signal reading errors.

More specifically, the present invention provides an information recording medium that is an optical disc having a reproduction area and a recording area, has good focusing when moving from the reproduction area to the recording area, and is free from tracking errors and signal reading errors. The purpose is to

It is another object of the present invention to provide an information recording medium which is an optical disc having a reproduction area and a recording area and has a small area which cannot be used as the reproduction area or the recording area and which is suitable for high density recording.

Further, the present invention provides an information recording medium having a reproduction area in which a CD format signal is recorded and a recording area in which a CD format signal can be optically recorded, and having no tracking error or signal reading error. With the goal.

SUMMARY OF THE INVENTION According to the present invention, a reproduction area composed of pits formed in an annular shape is formed on a disk-shaped substrate, and formed in an annular shape having a radial width in the range of 0.1 to 5.0 mm in contact with the outer peripheral edge of the reproduction area. And a recording area including a focusing area formed of a groove having a depth smaller than that of the recording area and a recording area formed in an annular shape in contact with an outer peripheral edge of the recording area, the recording area and at least the outside of the focusing area. In the information recording medium, a recording layer made of a dye capable of writing information with a laser is provided on the peripheral portion, and a reflective layer made of metal is provided on the entire surface from the reproduction area to the recording layer. .

Preferred embodiments of the information recording medium of the present invention are as follows.

1) The width of the focusing area in the radial direction is 0.1 to
The information recording medium described above, which is in the range of 2.5 mm.

2) The information recording medium, wherein the depth of the groove in the focusing area is deeper than half the depth of the pits in the reproducing area and shallower than the depth of the groove in the recording area.

3) The depth of the groove in the focusing area is 800
The information recording medium as described above, which is in the range of up to 1500Å.

4) The information recording medium as described above, wherein the depth of the groove in the focusing area is substantially the same as the depth of the pit in the reproducing area.

5) The information recording medium, wherein the depth of the groove of the focusing area gradually increases from the reproducing area side to the recording area side.

6) The information recording medium, wherein the information in the reproduction area is a CD format signal.

7) The information recording medium as described above, wherein the recording layer has a layer thickness in the range of 50 to 250 nm.

8) The dye is a cyanine dye, an oxonol dye,
The above information recording medium, which is at least one selected from the group consisting of merocyanine dyes, pyrylium dyes, thiopyrylium dyes, naphthalocyanine dyes and phthalocyanine dyes.

EFFECTS OF THE INVENTION An information recording medium having a reproduction area and a recording area of the present invention has an inner peripheral edge portion (peripheral edge and vicinity of the peripheral edge) of the recording layer.
Exist in a focusing area formed by a groove having a shallow depth provided between the reproduction area and the recording area. Therefore, a high reflectance can be obtained even in the focusing area provided between the reproducing area and the recording area, so that the focusing is good and the tracking error and the signal reading error hardly occur. Therefore, it is possible to skip in the jump area between the reproduction area and the recording area, and it is possible to perform continuous reproduction from the reproduction area to the recording area.

That is, since the inner peripheral edge portion of the recording layer exists in the focusing area composed of a groove having a shallow depth, the swelled portion of the dye at the coating start position on the inner peripheral side of the dye recording layer is naturally in the focusing area. It is in. The depth of the groove is shallow in the focusing area, and the dye coating layer formed in the focusing area has an inner peripheral edge formed in a shape with high circularity along the groove. Since the thicknesses are averaged (that is, there is no extreme layer thickness unevenness), the reflectance is less likely to decrease or fluctuate, and the focusing is good, and tracking hardly occurs.

Further, the focusing area, as described above, the dye coating layer, the inner peripheral edge portion is formed in a shape having a high roundness along the groove, it is possible to set a narrow focusing area, high It can be said that this is an information recording medium suitable for density recording.

Detailed Description of the Invention The information recording medium of the present invention has a basic structure in which a recording layer made of a dye and a reflective layer are laminated in this order on a substrate.

As described above, when the boundary between the reproduction area of the pit and the recording area of the groove is a groove, the peripheral portion of the dye recording layer formed by coating on the groove has a large thickness of the dye layer and the reflectance is significantly lowered. , Focusing failure tends to occur (cannot jump over the jump area). When the boundary is the mirror portion, continuous reproduction from the reproduction area to the recording area is generally impossible. Further, when the boundary is a pit, even if the layer thickness of the inner peripheral edge of the dye recording layer is thick, since there is a mirror portion other than the pit, the reflectance is relatively high, so good focusing can be obtained. The inner peripheral edge of the is uneven, as can be seen from FIG. 3b). For this reason, it is necessary to make a large area that cannot be recorded, which is disadvantageous in terms of high density recording.

The present invention solves the above problem. That is, the inner peripheral edge of the dye layer is formed on the groove as shown in a) of FIG. Then, by making this region a region having a shallow depth (focusing region), the reflectance is improved and good focusing is maintained. Furthermore, since the inner peripheral edge of the dye recording layer is formed in a uniform arc along the groove in the focusing area, the area can be set to a narrow width, which is an information recording medium capable of high density recording.

The configuration of the information recording medium of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a perspective view of a judgment surface showing an example of the information recording medium of the present invention.

The information recording medium shown in FIG. 1 comprises a disk-shaped substrate 1, a recording layer 2 made of a dye provided on the outer peripheral side of the substrate, a reflective layer 3 provided on the substrate and the recording layer, and The protective layer 4 is provided on the reflective layer. The information recording medium has a reproducing area 5 having pits as recording signals on the inner peripheral substrate, a recording area 6 having grooves (pre-grooves) formed on the outer peripheral substrate for recording information, and A focusing area 7 having a groove is provided between the reproducing area 5 and the recording area 6. The peripheral area of the recording layer is formed in the focusing area 7. In general, the vicinity of the inner peripheral edge and the vicinity of the outer peripheral edge of the substrate are plane surfaces on which no pits or grooves are formed (not shown).

FIG. 2 is a partial enlarged cross-sectional view of the vicinity of the focusing area 7 of FIG.

The surface of the disk-shaped substrate 1 has a reproduction area 5 composed of pits 8 in which information is recorded, a recording area 6 composed of a groove (pre-groove) 9 for guiding a recording (or reproduction) laser, and between both areas. It comprises a focusing area 7 consisting of a groove 10. The dye recording layer 2 is formed not only in the recording area 6 but also in a part of the focusing area 7. The reflective layer 3 is provided so as to cover all of these regions and the recording layer on the substrate, and the protective layer 4 is formed on the reflective layer.

The depth of the groove 10 in the focusing area of the present invention is shallower than the depth of the groove 9 in the recording area. As a result, the reflectance is high in the focusing area. That is, in the recording layer formed in the focusing area 7, the raised peripheral edge portion is present in the focusing area 7. In such a raised peripheral portion, the dye coating liquid at the coating start position where the dye coating liquid is coated by the spin coating method or the like is formed by the surface tension with the substrate. Generally, when the raised peripheral portion of the recording layer is on the groove, the reflectance is significantly lowered and focusing failure is likely to occur, but in the present invention, the groove is shallow and the reflectance is higher than that on the reproduction area. However, there is no focusing defect.

Further, as shown in a) of FIG. 3, since the dye recording layer is formed only on the groove, the inner peripheral edge portion of the recording layer has a uniform arc shape, and the inner peripheral edge portion has a so-called so-called arc shape. It is possible to reduce the area (focusing area) where there is no coating unevenness and which cannot be used for recording or reproduction.

The depth of the groove in the focusing area is generally deeper than half the depth of the pits in the reproducing area and shallower than the depth of the groove in the recording area. The depth of the groove in the focusing area is preferably 800 to 1500Å, more preferably 1000 to 1500Å. It is also advantageous and preferable in manufacturing that the depth of the groove in the focusing area is substantially the same as the depth of the pit in the reproducing area. The depth of the groove in the focusing area is generally the same in any track in the focusing area, but as long as the depth of the groove is shallower than the depth of the groove in the recording area, the depth may change in the focusing area. It is preferable to gradually increase from the reproduction area side to the recording area side.

Also, the radial width of the focusing area is 0.1-5 mm.
The range of 0.1 to 2.5 mm is preferable, and further 0.
A range of 5 to 2.5 mm is preferred. Most preferably 1-2 mm
Range.

By setting the focusing area in this way,
It is possible to obtain an information recording medium suitable for high-density recording, in which the reflectance does not decrease or fluctuate, focusing is good, tracking is not impossible.

Further, the optical disc has a reproduction area in which a CD format is recorded, and after a CD format signal is recorded in the recording area, a commercially available CD player (laser wavelength: 780
nm) is useful for good reproduction.

The information recording medium of the present invention can be manufactured, for example, by the method described below.

The disc-shaped substrate of the present invention can be arbitrarily selected from various materials used as a substrate of a conventional information recording medium. Examples of the substrate material of the present invention include glass; polycarbonate; acrylic resins such as polymethyl methacrylate; polyvinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymer; epoxy resins; amorphous polyolefin and polyester; You may use together if desired. Note that these materials can be used as a film or as a rigid substrate. Among the above materials, polycarbonate is preferable from the viewpoints of moisture resistance, dimensional stability, price, and the like.

An undercoat layer may be provided on the surface of the substrate on which the recording layer is provided, for the purpose of improving flatness, improving adhesive strength, improving sensitivity, and preventing deterioration of the recording layer. Examples of the material for the undercoat layer include polymethylmethacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleinate copolymer, polyvinyl alcohol, N-methylolacrylamide, styrene / vinyltoluene copolymer, chlorosulfonated polyethylene. , Polymeric materials such as nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, polyethylene, polypropylene, polycarbonate; and silane coupling agents, etc. The organic substances can be mentioned.

The undercoat layer is prepared, for example, by dissolving or dispersing the above substances in a suitable solvent to prepare a coating solution, and then coating the coating solution on the substrate surface by a coating method such as spin coating, dip coating, or extrusion coating. Can be formed. The thickness of the undercoat layer is generally 0.005 to 20 μm
The range is 0.01 to 10 μm.

On the disc-shaped substrate (or undercoat layer) of the present invention, pits and tracking grooves (pre-grooves) representing information such as address signals or music information are formed. When the resin material such as polycarbonate is used, it is preferable to form the pits and grooves directly on the substrate by injection molding or extrusion molding of the resin material.

Also, the formation of a groove or the like may be performed by providing a pre-groove layer. As a material for the pre-groove layer, a mixture of at least one monomer (or oligomer) of acrylic acid monoester, diester, triester and tetraester and a photopolymerization initiator can be used. To form the gregrove layer, first, apply a mixed solution of the above acrylic ester and a polymerization initiator onto a precisely prepared mother die (stamper),
Further, a substrate is placed on this coating liquid layer, and then the liquid layer is cured by irradiation of ultraviolet rays through the substrate or the mother die to fix the substrate and the liquid phase. Then, the substrate is separated from the mother die to obtain a substrate provided with a pre-groove layer.

The layer thickness of the pregroove layer is generally in the range of 0.05 to 100 μm, preferably 0.1 to 50 μm.

A recording layer made of a dye is provided on the disk-shaped substrate.

Dyes used in the present invention include, for example, indolenine dyes, imidazoquinoxaline dyes, cyanine dyes such as indolizine dyes, phthalocyanine dyes, naphthalocyanine dyes, pyrylium and thiopyrylium dyes, and azulenium dyes , Squarylium dye, N
Metal complex salt dyes such as i, Cr, naphthoquinone dyes / anthraquinone dyes, indophenol dyes, indoaniline dyes, triphenylmethane dyes, triallylmethane dyes, merocyanine dyes, oxonol dyes, aminium dyes Mention may be made of diimmonium dyes and nitroso compounds.

The dye layer is formed by dissolving the above dye, and optionally a binder, a metal complex salt dye or an aminium-diimmonium dye (quencher) in a solvent to prepare a coating liquid, and then applying this coating liquid to the substrate surface. It can be carried out by applying the composition to form a coating film and then drying it.

As the solvent for preparing the dye coating solution, ethyl acetate,
Butyl acetate, esters such as cellosolve acetate, ketones such as methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone, halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, chloroform, ethers such as tetrahydrofuran, ethyl ether, dioxane, ethanol, n- Examples thereof include alcohols such as propanol, isopropanol and n-butanol, amides such as dimethylformamide, and fluorinated solvents such as 2,2,3,3-tetrafluoropropanol. The amount of these non-hydrocarbon organic solvents is 50% by volume.
A hydrocarbon solvent such as an aliphatic hydrocarbon solvent, an alicyclic hydrocarbon solvent, or an aromatic hydrocarbon solvent may be contained as long as it is within the range.

In addition, antioxidant, UV absorber, plasticizer,
Various additives such as a lubricant may be added depending on the purpose.

When the binder is used, examples of the binder include cellulose derivatives such as gelatin, nitrocellulose and cellulose acetate, natural organic polymer substances such as dextran, rosin and rubber; and carbonization such as polyethylene, polypropylene, polystyrene and polyisobutylene. Hydrogen resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl chloride
Thermosetting of vinyl resin such as polyvinyl acetate copolymer, acrylic resin such as polymethyl acrylate and polymethyl methacrylate, polyvinyl alcohol, chlorinated polyolefin, epoxy resin, butyral resin, rubber derivative, phenol / formaldehyde resin, etc. Examples thereof include synthetic organic polymer substances such as initial condensates of organic resins.

Examples of the coating method include a spray method, a spin coating method, a dipping method, a roll coating method, a blade coating method, a doctor roll method and a screen printing method.

When a binder is used in combination as a material for the dye layer, the ratio of the dye to the binder is generally in the range of 0.01 to 99% (weight ratio), preferably in the range of 1.0 to 95% (weight ratio).

The dye layer may be a single layer or multiple layers, but the layer thickness is generally in the range of 100 to 5500Å, preferably 200 to 3000Å
Is in the range.

Between the recording layer and the substrate, chlorinated polyolefin,
An intermediate layer made of nitrocellulose or fluororesin may be provided.

 A reflective layer is provided on the substrate and the recording layer.

The light-reflecting substance that is the material of the reflecting layer is a substance having a high reflectance for laser light, and examples thereof include Mg, Se, and
Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, F
e, Co, Ni, Ru, Rh, Pd, Ir, Pt, Cu, Ag, Au, Zn, C
Metals and metalloids such as d, Al, Ga, In, Si, Ge, Te, Pb, Po, Sn and Bi can be mentioned. Among these, Al, Au, Cr and Ni are preferred. These substances may be used alone or in combination of two or more kinds or as an alloy.

The reflective layer can be formed on the substrate by, for example, vapor deposition, sputtering or ion plating of the light reflective material. The layer thickness of the reflective layer is generally in the range of 100 to 3000Å.

A protective layer is preferably provided on the reflective layer for the purpose of physically and chemically protecting the recording layer and the like. This protective layer may be provided on the side of the substrate on which the recording layer is not provided for the purpose of enhancing scratch resistance and moisture resistance.

Examples of materials used for the protective layer include SiO, SiO ₂ , and M.
Examples thereof include inorganic substances such as gF ₂ , SnO ₂ and Si ₃ N ₄ ; organic substances such as thermoplastic resins, thermosetting resins and UV curable resins.

The protective layer can be formed, for example, by laminating a film obtained by extrusion processing of plastic on the recording layer (reflection layer) and / or the substrate via the adhesive layer. Alternatively, it may be provided by a method such as vacuum vapor deposition, sputtering, and coating. Further, in the case of a thermoplastic resin or a thermosetting resin, it can also be formed by dissolving these in an appropriate solvent to prepare a coating solution, applying the coating solution, and then drying. In the case of a UV curable resin, it can also be formed by preparing a coating solution as it is or by dissolving it in an appropriate solvent, applying this coating solution, and irradiating it with UV light to cure it. Various additives such as an antistatic agent, an antioxidant and a UV absorber may be further added to these coating solutions depending on the purpose. When the protective layer forming material is directly coated on the recording layer, polybutadiene or the like is coated on the recording layer in order to protect the recording layer from the dissolving action of the coating liquid for the protective layer (at this time, a solvent which does not dissolve the recording layer is used as a solvent). It is preferable to provide the intermediate layer. The intermediate layer may be formed by depositing a thin film of metal or the like.

 The layer thickness of the protective layer is generally in the range of 0.1 to 100 μm.

Further, instead of forming the protective layer on the recording layer, the recording layer may be protected by providing a plastic film on the recording layer by fusion bonding on the inner circumference and the outer circumference of the substrate.

In the present invention, the information recording medium may be a single plate having the above-mentioned structure, or further, two substrates having the above-mentioned structure are faced so that the recording layer is on the inside.
A bonding type recording medium can also be manufactured by bonding with an adhesive or the like. Alternatively, an air sandwich type recording medium is manufactured by using at least one of the two disk-shaped substrates with the substrate having the above-mentioned configuration and bonding them via a ring-shaped inner spacer and a ring-shaped outer spacer. You can also do it.

The information recording medium of the present invention can be manufactured by the above method.

The information recording and reproducing method is performed, for example, as follows using the above information recording medium.

First, while rotating the information recording medium at a constant linear velocity (1.2 to 1.4 m / sec in the case of CD format) or a constant angular velocity, light for recording such as semiconductor laser light is irradiated from the substrate side. It is considered that this light irradiation records information by forming pits (holes) in the recording layer or changing the refractive index in the recording layer due to discoloration, change in association state, or the like. A semiconductor laser beam having an oscillation wavelength in the range of 750 nm to 850 nm is used as the recording light.

The information recorded as described above can be reproduced by irradiating the semiconductor laser light from the substrate side while rotating the information recording medium at the same constant linear velocity as above, and detecting the reflected light. . Incidentally, the irradiation of the laser beam may be performed from the recording layer side in the case of a flexible disk or the like.

Examples and comparative examples of the present invention will be described below. However, each of these examples does not limit the present invention.

Example 1 The following indolenine dyes: 1.7 g and the following dye (IRG-023, manufactured by Nippon Kayaku Co., Ltd.): 0.17 g and 2,2,3,3-tetrafluoropropanol 100 m
A dye coating solution was prepared by dissolving ultrasonic waves in 1 while applying ultrasonic waves for 1 hour.

Polycarbonate substrate 1) Dimensions; Outer diameter: 120 mm, Inner diameter: 15 mm, Thickness: 1.2 mm, Refractive index: 1.58 Track pitch: 1.6 μm, 2) Information reproduction (pit) area; Pit width: 0.55 μm, Pit depth : 1100Å, Area: radius 23-35mm range Pit information: CD format EFM signal (radius 23-25mm range is lead-in information, radius 25-34mm range is music information, radius 34-35mm range is lead-out Information) 3) Focusing (groove) area (7 in Fig. 2); Groove width: 0.47 μm, Groove depth: 1100Å, Area: radius 35-36.5 mm 4) Recording (groove) area; Groove width: 0.47 μm, groove depth: 1600 Å, area: radius 36.5 mm to 58 mm Spinner nozzle speed 200 rpm Radius 50.0 mm on the surface of the substrate where the pre-groove is provided. Start coating (coating diameter: 35 mm) and Move to a position with a radius of 35.0 mm, stop moving for 1 second with coating, move to a position with a radius of 50.0 mm for 2 seconds, and apply for 5 seconds while coating at a spinner speed of 200 rpm. After coating, gradually increase the number of revolutions by 50 rpm every 16 seconds and make the final number of revolutions 1000 rpm, keep this state for 30 seconds and dry, the layer thickness in the groove is 1400 Å and the layer thickness between the grooves is 1000 Å The dye recording layer was formed up to the outer peripheral edge of the substrate. The radius of the formation position (inner peripheral edge) of the obtained dye recording layer was within a range of 34 ± 0.5 mm, and the refractive index was 2.8 ± 0.1.

Au was sputtered on the substrate and the dye recording layer with a DC sputtering device under the conditions of Ar pressure of 2 Pa and power of 200 W to form a reflective layer having a layer thickness of 1000 Å up to a substrate outer diameter of 118 mm.

The coating liquid for forming the protective layer (trade name: UV-curable resin: 3070, manufactured by Three Bond Co.) is further applied on the reflective layer by spin coating at a rotation speed of 200 rpm and maintained for 5 seconds. Was completed, the rotation speed was increased, and the substrate was dried by rotating at a final rotation speed of 1500 rpm for 30 seconds. Then, the coating layer was irradiated with ultraviolet rays ( ²⁰⁰ w / cm ² mercury lamp for 10 seconds) to form a protective layer having a thickness of 2 μm.

Thus, an information recording medium (see FIGS. 3 and 4) in which the dye recording layer, the reflective layer and the protective layer were provided on the substrate was manufactured.

[Example 2] In Example 1, as a polycarbonate substrate, the above 3) focusing (groove) region (7 in Fig. 2); groove width: 0.47 µm, groove depth: innermost circumference gradually increased from 1100Å And the outermost
An information recording medium was manufactured in the same manner as in Example 1 using the same substrate except that the region was formed with a gradient to 1600Å: the radius was 35 to 36.5 mm.

Comparative Example 1 In Example 1, as the polycarbonate substrate, the above 3) tracking (groove) regions were not provided,
The area of the recording (groove) area in 4) above is a radius of 35 mm to 58 mm.
An information recording medium was manufactured in the same manner as in Example 1 except that the same substrate was used except that the range was set to mm.

Comparative Example 2 In Example 1, as the polycarbonate substrate, the above 3) tracking (groove) regions were not provided,
The radius of the recording (pit) area of 2) above is 23m to 36.5m.
An information recording medium was manufactured in the same manner as in Example 1 using the same substrate except that the range was changed to m.

[Comparative Example 3] In Example 1, an information recording medium was manufactured in the same manner as in Example 1 using the same substrate as in Example 1 except that the above-mentioned 3) tracking (groove) region was changed to a full mirror as the polycarbonate substrate. did.

[Evaluation of Information Recording Medium] 1) Measurement of reflectance near the tracking area or near the boundary between the reproduction area and the recording area (low reflectance area and presence / absence of reflectance of 30% or less) Optical disc evaluation machine (DDU1000, Pulstec Industrial Co., Ltd.) CD player (CD-1000, Yamaha Corp.)
The optical disk obtained above was reproduced using an apparatus equipped with an optical head (wavelength: 780 nm) removed from the product.
The reproduced signal was taken out at DC and the voltage corresponding to the average reflectance of the reproduced signal was measured with a voltmeter. The reflectance value is
The mirror portion of the CD was measured with a reflectometer (manufactured by Mizojiri Optical Co., Ltd.), the voltage of the mirror portion was measured as described above, and the reflectance of the optical disk was determined based on this value.

Set the optical head to 0.1 m in the range of 32 to 37 mm on the optical disk.
The reflectance is measured for each radius by moving m, and the reflectance is 5
Determine the width of the area that shows less than 0%, and reflectivity 30%
The presence or absence of the following areas was examined.

2) Continuous Playability Using the above-mentioned device, it was investigated whether or not continuous playback is possible with a three-beam optical head on the optical disc from a radius of 32 mm to 37 mm while focusing.

 The above measurement results are shown in Table 1.

As is apparent from Table 1 above, the optical discs (Examples 1 and 2) in which the vicinity of the inner peripheral edge of the dye recording layer is formed on the tracking area of the present invention (Examples 1 and 2), the average reflection near the boundary between the reproduction area and the recording area. Since the area with a high rate is large, there is no focusing defect (defocus) even when performing a seek that jumps over the boundary between the playback area and the recording area with a commercially available CD player that requires high reflectance for playback. Conceivable. Continuous reproduction is also good.

In Comparative Example 1, a portion having a reflectance of 30% or less was generated, and when seek was performed to jump over the boundary between the reproduction area and the recording area with a commercially available CD player, focusing failure (lost)
Is easy to occur.

In Comparative Example 2, there is no portion where the reflectance is extremely low and there is no problem in continuous reproduction, but the low reflectance area is large and the area that cannot be used for recording is large.

Further, as in Comparative Example 3, when the boundary is a mirror, there is no problem of focusing problem at the time of seeking over the boundary, but the low reflectance area is wide and the area unusable for recording becomes large. Regeneration is also impossible. Further, in such a disc, it becomes difficult to control the position of the optical head in the recording device.

[Brief description of drawings]

FIG. 1 is a half cross-sectional perspective view of an example of the information recording medium of the present invention. FIG. 2 is a partially enlarged sectional view of the vicinity of the tracking area 7 in FIG. FIG. 3 is a plan view showing the shape of the inner peripheral edge portion when the dye recording layer is formed on each surface of the groove portion, the pit portion and the mirror portion on the surface of the substrate. Disc-shaped substrate: 1 Dye recording layer: 2 Reflective layer: 3 Protective layer: 4 Playback area: 5 Recording area: 6 Tracking area: 7 Pit: 8, P groove: 9, 10, G land: L Mirror: M Dye coating Layer: D

Claims (1)

(57) [Claims] 1. A reproduction area consisting of pits formed in an annular shape on a disk-shaped substrate, and formed in an annular shape having a radial width in the range of 0.1 to 5.0 mm in contact with the outer peripheral edge of the reproduction area. A focusing area having a depth shallower than the groove of the recording area and a recording area having an annular groove formed in contact with the outer peripheral edge of the recording area are provided, and the recording area and at least the outer peripheral edge of the focusing area are provided. An information recording medium in which a recording layer made of a dye capable of writing information by a laser is provided, and a reflective layer made of metal is provided on the entire surface from the reproduction area to the recording layer.