JP2529133B2 - 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 pitted within a signal surface inner diameter of 50 mm and a signal surface outer diameter of 116 mm by recording the CD by rotating it at a constant linear velocity of 1.2 to 1.4 m / sec. Width 0.8
It is required to have a maximum recording time of 64-74 minutes at a track pitch of 1.6 μm and 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. Also 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 on a substrate are laminated has been studied. like this
As an example of a DRAW-type CD, an optical disc having a structure in which a dye recording layer on a polycarbonate substrate, a reflective layer of Au, and a protective layer are laminated in this order 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 pit area (generally a reproduction area) and a pit where pits as recording information such as address information are formed on the inner peripheral side of the substrate. A groove area (generally a recording area) provided on the substrate with a pre-groove for guiding a laser for recording information is provided on the outer peripheral side of the area. Further, recently, an optical disc has been proposed in which one disc has both the functions of a reproducing CD and a DRAW-type CD (Japanese Patent Laid-Open No. 2-42652). That is, a recording area having a groove on the substrate is provided on the outer peripheral side of the reproducing CD,
It is an optical disc that has a ROM area on the inner circumference side that contains information such as music. This allows the user to record data and notes on the same disc while sharing the same information (music and programs) with other people.

A method for producing an optical disc having such a ROM (pit) area and a recording (groove) area is disclosed in the above-mentioned Japanese Patent Laid-Open No. 2-42
According to Japanese Patent No. 642, a portion outside the diameter of 80 mm is formed by spin coating in order to form a dye recording layer on the groove having a diameter of 80 to 117 mm of the substrate, which is on the outer peripheral side of the ROM area having the pits of the substrate. To form a recording layer. 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 the grooves (recording) outside the diameter of 80 mm having the grooves as described above are recorded.
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 extremely difficult to manufacture the dye recording layer only in the groove area from the boundary between the pit area and the groove area.

[Object of the Invention] As described above, when the dye recording layer is formed by spin coating or the like on the outer peripheral side of the substrate, for example, it is difficult to separate the dye recording layer accurately at the boundary between the pit area and the groove area. Further, 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 only on the groove in the groove area. It has been clarified that even if the dye recording layer is formed, the thickness of the inner peripheral edge portion of the recording layer is increased, the reflectance is remarkably lowered, and it is easy to lose focus (defective 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't even track.

Therefore, it is an object of the present invention to provide an information recording medium which is an optical disc having a pit area and a groove area, has good focusing and does not cause a signal reading error.

More specifically, the present invention is an optical disc having a pit area and a groove area, and an object of the present invention is to provide an information recording medium having good focusing and no signal reading error at the boundary between the two areas. And

It is another object of the present invention to provide an information recording medium having a pit area in which a CD format signal is recorded and a groove area in which a CD format signal can be optically recorded and having no signal reading error. .

SUMMARY OF THE INVENTION According to the present invention, a pit area in which pits are formed and a groove area in which a pre-groove is formed are provided on a disk-shaped substrate, and information can be written on the groove area and by laser. In an information recording medium having a recording layer made of a dye, and a reflective layer made of metal provided on the entire surface from the pit area to the recording layer, the peripheral edge of the recording layer on the pit area side is the groove. An information recording medium is characterized in that it exists in the pit area beyond the boundary between the area and the pit area.

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

1) The information recording medium as described above, wherein the peripheral portion of the recording layer on the pit area side is present in the pit area within a range of 0.1 to 5.0 mm from the boundary between the pit area and the groove area.

2) The information recording medium, wherein the pit area comprises an information reproducing area on the inner peripheral side and a focusing area on the outer peripheral side, and the peripheral area on the pit area side of the recording layer exists in the focusing area. .

3) The information recording medium as described in 2) above, wherein the information in the focusing area is a lead-out signal in a CD format.

4) The difference between the outer diameter and the inner diameter that indicate the focusing area is
The information recording medium according to 2) above, which is in the range of 0.1 to 5.0 mm.

5) The information recording medium according to 2), wherein the information in the focusing area comprises a lead-out signal of the CD format and a signal indicating the boundary between the pit area and the groove area after the lead-out signal. .

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

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

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

[Effects of the Invention] In an information recording medium having a pit area and a groove area of the present invention, one peripheral edge (the peripheral edge and the vicinity of the peripheral edge) of the recording medium exceeds the boundary between the pit area and the groove area. Since it exists in the pit area, focusing is good near the boundary between the two areas and almost no signal reading error occurs. That is, since the vicinity of one peripheral edge of the recording layer exists in the pit area, the portion where the dye swells at the coating start position on the inner peripheral side of the dye recording layer is in the pit area. Therefore, since the dye recording layer is formed on the pre-groove in the groove region with a substantially desired layer thickness, the reflectance is not lowered or fluctuated, and the focusing is good.

In particular, when the information in the pit area is a CD format signal, a focusing area composed of pits provided on the outer peripheral side of the pit area is provided, and a CD format lead-out signal and an information reproducing area and a recording area are provided in this focusing area. By recording a signal indicating the boundary between and, more reliable seek is possible.

[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.

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

FIG. 1 is a half cross-sectional perspective view of an example of the information recording medium of the present invention.

The information recording medium shown in FIG. 1 includes a disc-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 reflection layer. The protective layer 4 is provided on the layer. In the above information recording medium, a pit area 5 in which pits as recording signals are provided on the substrate (almost no recording layer is provided) and a pre-groove (groove) is provided on the substrate, and a recording layer is formed thereon. Groove area 6 capable of recording the recorded information. The peripheral portion of the recording layer (the peripheral edge and its vicinity) is formed on the pit area side of the boundary between the pit area 5 and the groove area 6. In general, the substrate surface near the inner peripheral edge and the outer peripheral edge of the substrate is a plain surface in which no pits or grooves are formed (not shown).

FIG. 2 is a partially enlarged sectional view near the boundary between the pit area 5 and the groove area 6 in FIG.

On the surface of the disk-shaped substrate 1, pits 8 in which information is recorded are formed in the pit area 5, and pregrooves 9 for guiding a recording laser are formed in the groove area 6.
The dye recording layer 2 is formed not only in the groove area 6 but also in a part of the pit area 5. 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 recording layer formed in the pit area 5 has a raised peripheral edge portion in the pit area 7. On such a raised peripheral portion, the dye coating liquid at the coating start position where the dye coating liquid is applied by spin coating or the like is formed by the action of surface tension with the substrate. When the raised peripheral edge of the recording layer is on the groove, the reflectance is remarkably reduced, but the portion without the recording layer on the groove is too deep because the recording layer is not on the bottom of the groove. The reflectance is further reduced. Therefore, the raised peripheral edge portion of the recording layer is apt to have poor focusing, but when it is on the pit, the reflectance is slightly lowered but the focusing defect is hardly generated. Because the pit area is composed of pits and a plain mirror portion, the average reflectance is higher than that of the pre-groove which is a continuous groove, and it is considered that the influence of the lowered reflectance due to the raised pigment is small. Therefore, by forming the vicinity of the peripheral edge of the recording layer on the pit as described above, it is possible to prevent the occurrence of focusing defects. It is preferable that the peripheral portion is present in the pit area within a range of 0.1 to 5.0 mm from the boundary between the pit area and the groove area. The pit area is generally used for reproducing information, but may be used for seeking without reproducing information or for waiting until the next command comes.

FIG. 3 is a half sectional perspective view showing another example of the information recording medium of the present invention.

In FIG. 3, the pit area shown in FIG. 1 is a focusing area 17 composed of an information reproducing area 20 on the inner peripheral side and a pit on the outer peripheral side.
The peripheral area of the recording layer is formed in this focusing area. Therefore, in that the substrate is composed of a pit area composed of pits and a groove area composed of grooves, and the peripheral portion of the recording layer is on the pit area,
Although it is the same as FIG. 1, it is different in that a signal for improving control performance such as seek other than recording information is recorded in the focusing area. The focusing area is an area in which focusing can be performed without using it for reproducing or recording data information. However, part of the control information in the focusing area may be reproduced.

The information recording medium shown in FIG. 3 includes a disk-shaped substrate 11, a recording layer 12 made of a dye provided on the outer peripheral side of the substrate, the substrate and a reflective layer 13 provided on the recording layer, and the reflective layer. The protective layer 14 is provided on the layer. In the above information recording medium, a pit area 15 (a recording layer is not provided) in which a pit as a recording signal is provided on a substrate, a pre-groove (a groove) is provided on the substrate, and a recording layer is formed thereon. A groove area 16 capable of recording information, and a pit area 15 is an information reproducing area on the inner peripheral side.
It is divided into 20 and a focusing area 17 composed of pits on the outer peripheral side. A peripheral portion of the recording layer is formed in this focusing area. In general, the substrate surface near the inner peripheral edge and the outer peripheral edge of the substrate is a plain surface in which no pits or grooves are formed (not shown).

FIG. 4 is a partially enlarged sectional view in the vicinity of the focusing area 17 of FIG.

On the surface of the disk-shaped substrate 11, a pit 18 in which information is recorded is formed in the pit area 15, a pre-groove 19 for guiding a recording laser is formed in the groove area 16, and the pit area 15 is an information reproducing area 20 on the inner peripheral side. And a focusing area 17 consisting of outer pits. The dye recording layer 12 is formed not only in the groove area 16 but also in a part of the focusing area 17. A reflective layer 13 is provided so as to cover all of these areas on the substrate and the recording layer, and a protective layer 14 is formed on the reflective layer.

The recording layer formed in the focusing area 17 has a raised peripheral edge portion in the focusing area 17. Such a raised peripheral edge portion is formed by the surface tension of the dye coating liquid at the coating start position where the dye coating liquid is applied by spin coating or the like. In general, the raised peripheral portion of the recording layer has a markedly reduced reflectance when it is on the groove, and a focusing defect is likely to occur, but when it is on a pit, the reflectance is slightly lowered but the focusing defect is poor. Almost no occurrence. However, in the peripheral part of the recording layer of the pit area, it may be difficult to reproduce the recorded information of the pit. Therefore, when the information of the pit area 15 is a CD format signal, it is read out as the information of the focusing area 17 above. It is preferable to record the signal. By repeatedly recording the readout signal in this focusing area 17,
The lead-out signal can be read in the portion of the focusing area 17 where there is no recording layer. In order to enable such reproduction, it is preferable that the difference between the outer diameter and the inner diameter of the focusing area is in the range of 0.1 to 5.0 mm. Further, it is more preferable that a signal indicating the boundary between the information reproducing area and the recording area is recorded after the read-out signal.

The above optical disc has a pit area in which the CD format is recorded, and after the CD format signal is recorded in the groove area, a commercially available CD player (laser wavelength: 780n
For good reproduction in m), it is preferable to have pits and grooves having the following dimensions.

 If the substrate is polycarbonate (refractive index: 1.58), maximum pit depth: 900-1300Å average pit depth: 450-650Å pit width: 0.4-0.7 μm, for example, A) or B) groove is preferred .

A) When the refractive index of the recording layer is 2.6; Maximum depth of groove: 1400 to 1800Å Groove width: 0.4 to 0.6 μm B) When the refractive index of the recording layer is 2.9; Maximum depth of groove: 800 to 1000Å Groove width: 0.4 to 0.7 μm However, the solvent used when forming the recording layer is 2,2,3,3-
It is tetrafluoro-1-propanol. Also, with the average depth of pits, 100 or more pit rows along the track, the depth from the track to the pit bottom or between the pits is measured at intervals of 1/10 or less of the minimum pit length, Say the average of those depths.

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 substrates for conventional information recording media. Examples of the substrate material of the present invention include glass; polycarbonate; acrylic resins such as polymethylmethacrylate; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers; epoxy resins; amorphous polyolefins and polyesters. If desired, they may be used in combination. 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. , Nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethitel / vinyl acetate copolymer, polyethylene, polypropylene, polycarbonate, and other polymeric substances; 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.

Grooves (pre-grooves) for pitting and tracking are formed on the disk-shaped substrate (or undercoat layer) of the present invention, which represent information such as address signals or music information. 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.

The formation of the grooves and 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 pre-groove 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 pressure 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, ester such as cellosolve acetate, ketone such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone, halogenated hydrocarbon such as dichloromethane, 1,2-dichloroethane and chloroform, ether such as tetrahydrofuran, ethyl ether and dioxane, ethanol, n -Alcohols such as propanol, isopropanol and n-butanol, amides such as dimethylformamide, and fluorinated solvents such as 2,2,3,3-tetrafluoropropanol. The content of these non-hydrocarbon organic solvents is 50% by weight.
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 an intermediate layer by using). 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 configuration, or, further, two substrates having the above-mentioned configuration are faced so that the recording layer is on the inside.
A bonding type recording medium can also be manufactured by joining with an adhesive. 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 the irradiation of light causes information to be recorded by forming pits (holes) in the recording layer or by 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.

Hereinafter, examples and comparative examples of the present invention will be described. 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: 120mm, Inner diameter: 15mm, Thickness: 1.2mm, Refractive index: 1.58 Track pitch: 1.6μm, 2) Information reproduction area; Pit width: 0.55μm, Pit depth: 1100Å, Area: radius 23 to 32 mm Pit information: EFM signal in CD format (lead-in information in radius 23 to 25 mm, music information in radius 25 to 32 mm) 3) Focusing area (see Fig. 3 and 4) 17); Pit width: 0.55 μm, pit depth: 1100Å, area: radius 32 to 35 mm range Pit information: CD format EFM signal (radius 32 to 35 mm range is lead-out information, radius 33 to 35 mm range The pit area consists of 2) and 3) above. 4) Groove area; Groove width: 0.47 μm, Groove depth: 900Å, Area: radius 35 mm to 58 mm range Spinner nozzle 200 rpm pregroove is provided Start coating of the dye coating solution at a position of radius 50.0 mm on the substrate surface on the side where it moves, move to a position of radius 35.0 mm in 2 seconds, stop moving for 1 second with coating applied, and stop for 2 seconds To a position with a radius of 50.0 mm and spinner spins at a speed of 200 rpm for 5 seconds while applying, and 50 rpm for every second.
While gradually increasing the number of revolutions each, after 16 seconds the final number of revolutions is 1000
The dye recording layer having a layer thickness of 1400Å in the groove and a layer thickness of 1000Å between the grooves was formed up to the outer peripheral edge of the substrate at a rpm of 30 rpm for 30 seconds. 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 electric 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, the following indolenine dyes were used as dyes: 2.55 g and the above dye (IRG-023, manufactured by Nippon Kayaku Co., Ltd.)
The same substrate as in Example 1 except that the same substrate was used except that the groove depth of the groove area was set to 1700Å and the coating conditions of the dye coating solution were as follows. An information recording medium was manufactured.

Coating conditions: Spinner nozzle is rotated at a speed of 200 rpm to start coating the above dye coating solution at a position of a radius of 50.0 mm on the surface of the substrate where the pregroove is provided, and a position of a radius of 35.0 mm in 2 seconds. The rotation of the spinner was 200r, which stopped moving for 1 second with the coating applied, and moved to a position with a radius of 50.0mm in 2 seconds.
Apply for 5 seconds while applying at pm speed, 50 / s
Rotation speed 1500 rpm after 8 seconds while gradually increasing the rotation speed by rpm
Hold for 10 seconds at 2000 rpm for 2 seconds,
Then, it was dried to form a dye recording layer having a layer thickness of 2000Å in the groove and a layer thickness of 1000Å between the grooves 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 in the range of 34 ± 0.5 mm, and the refractive index was 2.6 ± 0.1.

[Comparative Example 1] In Example 2, the nozzle stop position (radius 35.0 mm) on the substrate of the spinner of the dye coating liquid was set to be 37.0 mm, and
The radius of the formation position (inner peripheral edge) of the obtained dye recording layer is 36 ±.
An information recording medium was manufactured in the same manner as in Example 2 except that the range was 0.5 mm.

[Comparative Example 2] In Example 2, the nozzle stop position (radius 35.0 mm) on the substrate of the spinner of the dye coating liquid was set to 36.0 mm, and
The radius of the formation position (inner peripheral edge) of the obtained dye recording layer is 35 ±.
An information recording medium was manufactured in the same manner as in Example 2 except that the range was 0.5 mm.

[Comparative Example 3] An information recording medium was manufactured in the same manner as in Example 2 except that the focusing area of the substrate 3) was not provided with pits and had a plain surface.

[Evaluation of Information Recording Medium] 1) Minimum average reflectance in the vicinity of the boundary between the pit area and the groove area A CD player (CD-1000, Yamaha Corporation) is used for an optical disk evaluation machine (DDU1000, manufactured by Pulstec Industrial Co., Ltd.).
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 a radius of 32 to 33.5 mm on the optical disk.
The reflectance was measured for each radius while moving by 1 mm, and the smallest value among them was taken as the smallest average reflectance.

2) Continuous reproducibility Using the above device, move the optical head to a radius of 32 on the optical disk.
We investigated whether continuous playback is possible from mm to 37 mm while tracking.

 The above measurement results are shown in Table 1.

As is clear from Table 1 above, in the optical discs (Examples 1 and 2) in which the vicinity of the inner peripheral edge of the dye recording layer was formed on the pit area of the present invention (Examples 1 and 2), the minimum average near the boundary between the pit area and the groove area was obtained. Since the reflectivity is high, it is considered that no focusing failure (disappearance) will occur even if a commercially available CD player, which requires a high reflectivity for reproduction, seeks over the boundary between the pit area and the groove area. .

In the low reflectance optical discs such as Comparative Examples 1 and 2,
Focusing failure is likely to occur when a commercially available CD player seeks beyond the boundary.

Further, as in Comparative Example 3, if the boundary is a plane, there is no problem of focusing failure at the time of seeking over the boundary, but continuous reproduction may be impossible. Further, in such a disc, it becomes difficult to control the position of the optical head in the recording device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a half sectional perspective view of an example of the information recording medium of the present invention. FIG. 2 shows the pit area 5 and the groove area 6 of FIG.
It is a partial expanded sectional view near the boundary with. FIG. 3 is a half sectional perspective view of another example of the information recording medium of the present invention. FIG. 4 is a partially enlarged sectional view of the vicinity of the focusing area 17 of FIG. Disk-shaped substrate: 1, 11 Dye recording layer: 2, 12 Reflective layer: 3, 13 Protective layer: 4, 14 Pit area: 5, 15 Groove area: 6, 16 Focusing area: 17 Pit area: 8, 18 Pre-groove area: 9, 19 Information playback area: 20

Claims (2)

(57) [Claims] 1. A recording comprising a pit area in which pits are formed and a groove area in which pregrooves are formed on a disk-shaped substrate, and a recording material made of a dye on which information can be written by a laser on the groove area. In an information recording medium in which a layer is provided, and a reflective layer made of metal is provided on the entire surface extending from the pit area to the recording layer, the pit area side peripheral portion of the recording layer is the groove area and the groove area. An information recording medium characterized by existing in a pit area beyond a boundary with the pit area. 2. The pit area comprises an information reproducing area on the inner peripheral side and a focusing area on the outer peripheral side, and the peripheral area on the pit area side of the recording layer is present in the focusing area. The information recording medium according to item 1.