JPH04176033A - Information recording medium - Google Patents

Abstract

PURPOSE:To improve focusing, and to prevent the generation of the read error of a signal by forming a peripheral section on the bit region side of a recording layer in a bit region while crossing the boundaries of a group region and the bit region. CONSTITUTION:An information recording medium is composed of a discoid substrate 1, a recording layer 2 formed on the outer circumferential side of the substrate 1 and consisting of a dyestuff, a reflecting layer 3 formed onto the substrate and the recording layer 2, and a protective layer 4 shaped onto the reflecting layer 3, and has a bit region 5, in which bits as recording signals are formed onto the substrate 1, and a group region 6, in which groups are formed onto the substrate 1 and the recording layer 2 is shaped onto the groups and which can record information. The bits 8, to which information is recorded, are formed in the bit region 5 and pre-groups 9 for guiding a laser for recording in the group region 6. There is the swelling peripheral section of the recording layer 2 formed in the bit region 5. Accordingly, focusing is improved, and the generation of the read error of a signal is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an information recording medium capable of reproducing and recording information using light.

[Technical Background of the Invention] In recent years, information recording media that use high energy density beams such as laser light have been developed and put into practical use. This information recording medium is called an optical disk, and can be used as a video disk, an audio disk, a large-capacity still image file, and a large-capacity computer disk memory. Among these information recording media, compact discs (CDs) are widely used for audio reproduction of music and the like.

General D RA W (Direct Read Af
The basic structure of the terWrite (writable) type information recording medium is a disc-shaped transparent substrate made of plastic, glass, etc., and Bi, Sn, and I
It has a recording layer made of a metal or metalloid such as n, Te, or a dye such as a cyanine dye.

Information is written on a recording medium by, for example, irradiating the recording medium with a laser beam, and the irradiated portion of the recording layer absorbs the light and locally increases in temperature, resulting in physical changes such as pit formation. Alternatively, information can be recorded by causing chemical changes to change its optical properties. Information is also read from an optical disk by irradiating the optical disk with a laser beam, and the information is reproduced by detecting reflected or transmitted light depending on changes in the optical characteristics of the recording layer.

A compact disc (CD), which is an optical disc for information reproduction, generally has an E F format signal such as a CD format signal.
M (Eight to Fourteen Modu
(latio) It consists of a plastic disc-shaped transparent substrate in which holes (pits) containing digital audio signal information are formed in advance, and a reflective thin film such as AIt and a protective film provided thereon. Information from a CD is read by irradiating the optical disc with a laser beam, and CD format signals and the like are read by changes in reflectance depending on the presence or absence of pits. Based on the CD standard, such CDs are classified into 1, 2 to 1.
By rotating and recording at a constant linear speed of 4 m/s,
Within the range of signal surface inner diameter 50mm and signal surface outer diameter 116mm, pit width 0.8μm, track pitch 1.6μm
It is required to have a maximum recording time of 64 to 74 minutes. Conventionally, such audio CDs
is a reproduction-only type with pits formed on the substrate in advance as described above. Also, recently, instead of music information, CD-R discs have been pre-recorded with information such as various documents and still images.
OM (Read Only Mea+ory) has also been put into practical use.

Such optical discs naturally have the disadvantage that information cannot be recorded or edited. Therefore, D RA W
(Direct Read After Write
, writable) type CDs are being developed and some have been put into practical use.

The above-mentioned DRAW type CD is required to be able to reproduce recorded information on a commercially available CD player.

Since it is necessary for an optical disc to have a high reflectance in order to play it on a CD player, an optical disc with a high reflectance is desired. Since the reflectance of both the dye recording layer and the metal recording layer is generally as low as about 30 to 40%, dyes have a manufacturing advantage over metals because they can easily form a recording layer by coating. . Therefore, a DRAW type CD in which a dye recording layer and a reflective layer are laminated on a substrate is being considered. As an example of such a RAW CD, an optical disc with a structure in which a dye recording layer, an Au reflective layer, and a protective layer are laminated in this order on a polycarbonate substrate is published by Nikkei Electronics (p. 107, 1989).
published on the 23rd of May).

RAW CDs (as well as conventional D RAW optical discs) generally have a pit area (generally a playback area) in which pits are formed as recording information such as address information on the inner circumferential side of the substrate. On the outer peripheral side of the pit area, there is a groove area (generally a recording area) in which a pre-groove for guiding a laser for recording information is provided on the substrate.

Furthermore, recently, an optical disc has been proposed that has the functions of both a playback CD and a DRAW type CD in a single disc (Japanese Patent Laid-Open No. 2-42652). That is,
This is an optical disc having a recording area having a groove on the substrate on the outer circumferential side of a CD for reproduction, and a ROM area containing information such as music on the inner circumferential side. This allows the user to record data and memos on the same disc while sharing the same information (music and programs) with other people.

This kind of ROM (pit) area and recording (groove)
A method for creating an optical disc having a region is described in the above-mentioned Japanese Patent Application Laid-Open No.
According to Publication No. 42652, RO with pits on the substrate
The diameter of the board is 80 to 117 m, which is on the outer circumferential side of the M area.
In order to form a dye recording layer on the groove in the range of m,
The recording layer is formed by coating the area outside the diameter of 80 mm using the spin code method. 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 consisting of pits, but is provided only in the groove area.

However, the track width (interval) between pits and grooves is generally about 1.6 μm, and as mentioned above, grooves outside the diameter of 80 mm (see B.
In order to apply the dye coating liquid only to the area ), it is necessary to apply the dye coating liquid so that the inner peripheral edge of the recording layer is not formed on the previous track where the pit is provided. That is, since the track width (interval) is on the order of microns as described above, it is necessary to control coating with extremely high precision. Therefore,
It is extremely difficult in manufacturing to form a 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 a dye recording layer is coated, for example, on the outer peripheral side of a substrate by a spin coding method or the like, it is difficult to accurately separate the layers at the boundaries between pit areas and groove areas. Furthermore, according to studies by the present inventors, the inner periphery (peripheral edge) of the dye recording layer, which is the coating start position, bulges due to surface tension and the layer thickness increases. Even if a dye recording layer is formed only on the recording layer, the layer thickness at the inner peripheral edge of the recording layer becomes thicker, and the reflectance decreases markedly, making it easy to lose focus (defective focusing).
It became clear. When you lose focus,
Since the reproduction signal cannot be obtained, the reproduction stops or goes out of control. Of course, tracking will no longer be possible.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an information recording medium which is an optical disc having a pit area and a groove area, which has good focusing and is free from signal reading errors.

Specifically, an object of the present invention is to provide an information recording medium which is an optical disc having a pit area and a groove area, which has good focusing at the boundary between these two areas, and which does not cause signal reading errors. shall be.

Furthermore, it is an object of the present invention to provide an information recording medium which has a pit area where a CD format signal is recorded and a groove area where the CD format signal can be optically recorded, and which is free from signal reading errors. .

[Summary of the Invention] The present invention provides a disc-shaped substrate with a pit region in which pits are formed and a groove region in which a pregroove is formed, and information can be written on the groove region by a laser. In an information recording medium provided with 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 formed in the groove. The information recording medium is characterized in that the information recording medium exists within 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 above information recording characterized in that the peripheral edge of the recording layer on the pit area side exists within the pit area within a range of 0.1 to 5.0 mm from the boundary between the pit area and the groove area. Medium.

2) The above information recording characterized in that the pit area consists of an information reproduction area on the inner circumferential side and a focusing area on the outer circumferential side, and a peripheral portion of the recording layer on the pit area side exists within the focusing area. Medium.

3) The above 2) characterized in that the information in the focusing area is a lead-out signal in CD format.
information recording medium.

4) The information recording medium according to 2) above, wherein the difference between the outer diameter and the inner diameter indicating the focusing area is in the range of 0.1 to s, Omm.

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

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

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

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

[Effects of the Invention] The information recording medium of the present invention having a pit area and a groove area has one peripheral edge (the peripheral edge and the vicinity of the peripheral edge) of the recording layer that extends beyond the boundary between the pit area and the groove area. Since it exists within the pit area, focusing is good near the boundary between these two areas, and almost no signal reading errors occur. That is, since the vicinity of one peripheral edge of the recording layer exists in the pit area, the raised portion of the dye at the coating start position on the inner peripheral side of the dye recording layer is in the pit area. Therefore, the dye recording layer is formed on the pre-groove in the groove area to a substantially desired layer thickness, so that there is little decrease or fluctuation in reflectance and good focusing is achieved.

In particular, when the information in the pit area is a CD format signal, a focusing area consisting of pits provided on the outer circumferential side of the pit area is provided, and this focusing area contains a CD format lead-out signal and an information playback area. By recording a signal indicating the boundary between the recording area and the recording area, more reliable seeking becomes 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 explained with reference to the accompanying drawings.

FIG. 1 is a half-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 disk-shaped substrate 1, a recording layer 2 made of a dye provided on the outer circumferential side of the substrate, a reflective layer 3 provided on the substrate and the recording layer, and a reflective layer 3 provided on the substrate and the recording layer. It has a structure consisting of a protective layer 4 provided on top of the protective layer 4.

The above-mentioned information recording medium has a pit area 5 on which pits for recording signals are provided on the substrate (almost no recording layer is provided), and a pre-groove on the substrate on which recording is made. It has a groove area 6 in which layered information can be recorded. The peripheral edge of the recording layer (
periphery and its vicinity) are formed. Note that, in general, the substrate surface near the inner peripheral edge and the outer peripheral edge of the substrate is a plain surface on which no pits or grooves are formed (not shown).

Figure 2 shows pit area 5 and groove area @6 in Figure 1 above.
FIG. 2 is a partially enlarged sectional view of the vicinity of the boundary between

On the surface of the disc-shaped substrate 1, pits 8 in which information is recorded are formed in pit areas 5, and pre-grooves 9 for guiding a recording laser are formed in groove areas 6. The dye recording layer 2 includes not only the groove area 6 but also the pit area 5.
It is also formed in part. A reflective layer 3 is provided to cover all of these areas on the substrate and the recording layer, and a protective layer 4 is formed on the reflective layer.

The recording layer formed in the pit area 5 has a particularly raised peripheral edge within the pit area 7 . Such a raised peripheral edge is formed by the action of surface tension between the dye coating liquid and the substrate at the coating start position where the dye coating liquid is applied by a spin code method or the like. If the raised peripheral part of the recording layer is on the groove, the reflectance will drop significantly, but the part where there is no recording layer on the groove is also because there is no recording layer at the bottom of the groove, so the groove is too deep. The reflectance further decreases. Therefore, the raised peripheral portion of the recording layer is likely to have poor focusing, but when it is located on a pit, there is almost no occurrence of poor focusing, although there is a slight decrease in reflectance. This is because the pit region consists of pits and a part of the brain mirror, so the average reflectance is higher than that of the pregroove, which is a continuous groove, so it is thought that the effect of reduced reflectance due to the raised pigment is small. . Therefore, by forming the vicinity of the periphery of the recording layer on the pit as described above, it is possible to prevent the occurrence of focusing defects. Preferably, the peripheral edge portion exists within the pit region within a range of 0.1 to 5.0 mm from the boundary between the pit region and the groove region. Although the pit area is generally used for reproducing information, it may also be used for seeking without reproducing information, or for waiting until the next command arrives.

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 of FIG.
7, and the peripheral edge of the recording layer is formed in this focusing area. Therefore, the substrate consists of a pit area made up of pits and a groove area made up of grooves, and the peripheral edge of the recording layer is on the pit area, which is the same as in FIG. It differs in that it records signals to improve control performance. The focusing area is
This area is not used for reproducing or recording data information and allows focusing. However, some of the above control information within 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 circumferential side of the substrate, a reflective layer 13 provided on the substrate and the recording layer, and a reflective layer 13 provided on the substrate and the recording layer. It has a structure consisting of a protective layer 14 provided on the layer. The information recording medium has a pit area 15 (no recording layer is provided) provided with pits as recording signals on a substrate, a pregroove (groove) provided on the substrate, and a recording layer formed thereon. The groove area 16, in which information can be recorded, and the pit area 15 are divided into an information reproducing area 20 on the inner circumferential side and a focusing area 17 consisting of pits on the outer circumferential side. A peripheral portion of the recording layer is formed in this focusing area. In general, the surface of the substrate near the inner and outer edges of the substrate is a plain surface with no pits or grooves formed (
(not shown).

FIG. 4 is a partially enlarged sectional view of the vicinity of the focusing area 17 shown in FIG. 3 above.

On the surface of the disc-shaped substrate 11, a pit area 15 has pits 18 in which information is recorded, a groove area 16 has a pre-groove 19 for guiding a recording laser, and the pit area 15 has an information reproducing area 20 on the inner circumference side. and a focusing area 17 consisting of a pit on the outer circumferential side. 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 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, in particular, its raised peripheral portion within the focusing area 17 . Such a raised peripheral portion is formed by surface tension between the dye coating liquid and the substrate at the coating start position where the dye coating liquid is applied by a spin code method or the like. In general, if the peripheral edge of the mound of the recording layer is on a groove, the reflectance will drop markedly and poor focusing will likely occur, but if it is on a pit, the reflectance will decrease slightly but poor focusing will occur. There are almost no However, in the peripheral part of the recording layer in the pit area, it may be difficult to reproduce the recorded information in the pit, so when the information in the pit area 15 is a CD format signal, it is read out as the information in the focusing area 17. Preferably, the signal is recorded. By recording the lead-out signal in the focusing area 17 in reverse, it is possible to read the lead-out signal 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 region is in the range of 0.1 to 5.0 mm. It is further preferable that a signal indicating the boundary between the information reproduction area and the recording area is recorded after the lead-out signal.

After the above optical disc has a pit area in which a CD format is recorded and a CD format signal is also recorded in a groove area, in order to successfully reproduce the disc on a commercially available CD player (laser wavelength near 80 nm), the following steps must be taken. Preferably, the pits and grooves have dimensions of .

If the substrate is polycarbonate (refractive index: 1.58), maximum depth of pits: 900-1300, average depth of bits: 450-650X, width of pits: 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 the groove: 1400-1800λ Groove width: 0.4-0.6 μm B) When the refractive index of the recording layer is 2.9; Maximum depth = 800-1000X Groove width: 0.4-0.7 μm However, the solvent used when forming the recording layer was 2°2.3.
3-tetrafluoro-1-propertool. In addition, the average pit depth is defined as the depth measured from the track to the bottom of the pit or between the pits at intervals of 1/10 or less of the minimum pit length for 100 or more pit rows along the track. , say the average value of their 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 of conventional information recording media. Examples of the substrate material of the present invention include glass; polycarbonate: acrylic resin such as polymethyl methacrylate; vinyl chloride resin such as polyvinyl chloride and vinyl chloride copolymer; epoxy resin; amorphous polyolefin and polyester; They may be used together if desired. Note that these materials can be used in the form of a film or as a rigid substrate.

Among the above materials, polycarbonate is preferred in terms of moisture resistance, dimensional stability, cost, and the like.

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

The undercoat layer is formed by, for example, dissolving or dispersing the above substances in a suitable solvent to prepare a coating solution, and then applying this coating solution to the substrate surface using a coating method such as spin code, dip coating, or extrusion coating. can do. The layer thickness of the undercoat layer is generally o, oos ~ 20
It is in the range of μm, preferably in the range of 0.01 to 10 μm.

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

Further, the formation of grooves and the like may be performed by providing a pre-groove layer. As the material for the pregroove 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. The pre-groove layer is first formed by M
A mixture of the above-mentioned acrylic ester and polymerization initiator is applied onto a densely formed matrix (stamper), and a substrate is placed on top of this coating liquid layer, and then stamped through the substrate or matrix. The liquid layer is cured by irradiation with ultraviolet rays, thereby fixing the substrate and the liquid phase. Next, by peeling the substrate from the mother mold, a substrate provided with a pregroove layer is obtained.

The thickness of the pregroove layer is generally in the range of 0.05 to 1.0 .mu.m, preferably in the range of 0.1 to 50 .mu.m.

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

The dyes used in the present invention include, for example, cyanine dyes such as indolenine dyes, imidazoquinoxaline dyes, and indolizine dyes, phthalocyanine dyes, naphthalocyanine dyes, biryllium/thiopyrylium dyes, and azulenium dyes. , squalirium pigment, Ni
, Cr metal complex dyes, naphthoquinone/anthraquinone dyes, indophenol dyes, indoaniline dyes, triphenylmethane dyes, triallylmethane dyes, merocyan dyes, oxonol dyes,
Examples include aminium-based and diimmonium-based dyes and nitroso compounds.

Formation of the dye layer involves adding the above dye, optionally a binder,
Dissolving a metal complex dye or aminium/diimmonium dye (quencher) in a solvent to prepare a coating solution, then applying this coating solution to the substrate surface to form a coating film, and then drying. I can do it.

Examples of the solvent for preparing the dye coating solution include esters such as ethyl acetate, butyl acetate, and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone; halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, and chloroform; Ethers such as tetrahydrofuran, ethyl ether, dioxane, alcohols such as ethanol, n-propatol, impropatol, n-butanol, amides such as dimethylformamide, fluorocarbon solvents such as 2.2.3.3-tetrafluoropropatol etc. can be mentioned. Note that these non-hydrocarbon organic solvents may contain hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents, as long as the amount is within 50% by volume. .

The coating solution also contains antioxidants, UV absorbers, plasticizers,
Various additives such as lubricants may be added depending on the purpose.

When a binder is used, examples of the binder include cellulose derivatives such as gelatin, nitrocellulose, and cellulose acetate; natural organic polymeric substances such as dextran, rosin, and rubber; and carbonized materials such as polyethylene, polypropylene, polystyrene, and polyisobutylene. Hydrogen resins, vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl chloride/polyvinyl acetate copolymers, acrylic resins such as polymethyl acrylate, polymethyl methacrylate,
Examples include synthetic organic polymeric substances such as polyvinyl alcohol, chlorinated polyolefins, epoxy resins, butyral resins, rubber derivatives, and initial condensates of thermosetting resins such as phenol/formaldehyde resins.

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

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

The dye layer may be a single layer or a multilayer, but its layer thickness is generally in the range of 100 to 5,500 λ, preferably 200 λ.
~3000λ.

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

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

The light-reflective substance that is the material of the reflective layer is a substance that has a high reflectance to laser light, and examples thereof include Mg, Se,
, Y, Ti, Zr, Hf, ■, Nb, Ta, C
r, Mo, W, Mn, Re.

Fe, Co, Ni, Ru, Rh, P
d, Ir, Pt, Cu, Ag, Au,
Zn, Cd, Al1, Ga, In, S
i, Ge, Te, Pb, Po.

Mention may be made of metals and metalloids such as Sn and Bi. Among these, preferred are A1, Au, Cr and Ni. These substances may be used alone, or in combination of two or more or as an alloy.

The reflective layer can be formed on the substrate by, for example, vapor deposition, sputtering, or ion-blating the light-reflecting material described above. The layer thickness of the reflective layer is generally in the range of 100 to 3000X.

Further, it is preferable that a protective layer is provided on the reflective layer for the purpose of physically and chemically protecting the recording layer and the like. This protective layer may also be provided on the side of the substrate where the recording layer is not provided for the purpose of increasing scratch resistance and moisture resistance.

Examples of materials used for the protective layer include Si0,5in
2, MgF2, 5n02, Si3N.

Inorganic substances such as: organic substances such as thermoplastic resins, thermosetting resins, and UV curable resins.

The protective layer is formed by applying a film obtained by extrusion of plastic, for example, onto the recording layer (reflection layer) and/or via an adhesive layer.
Alternatively, it can be formed by laminating it on a substrate. Alternatively, it may be provided by methods such as vacuum evaporation, sputtering, and coating. In addition, thermoplastic resin,
In the case of a thermosetting resin, it can also be formed by dissolving the resin in an appropriate solvent to prepare a coating solution, applying this coating solution, and drying it. In the case of a UV curable resin, it can also be formed by preparing a coating liquid as it is or by dissolving it in an appropriate solvent, applying this coating liquid, and curing it by irradiating it with UV light. Various additives such as antistatic agents, antioxidants, and UV absorbers may be added to these coating solutions depending on the purpose. When coating the protective layer forming material directly on the recording layer, coat polybutadiene or the like on the recording layer to protect the recording layer from the dissolving action of the coating liquid for the protective layer (in this case, use a solvent that does not dissolve the recording layer). It is preferable to provide an intermediate layer by using the following method.

The intermediate layer may be formed by depositing a thin film of metal or the like.

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

Furthermore, instead of forming a protective layer on the recording layer, the recording layer may be protected by providing a plastic film on the recording layer by fusing it at the inner and outer peripheries of the substrate.

In the present invention, the information recording medium may be a single board having the above-mentioned structure, or alternatively, two substrates having the above-mentioned structure may be placed facing each other so that the recording layer is on the inside, and adhesive or the like is used. By joining, a laminated type recording medium can also be manufactured. Alternatively, an air sandwich type recording medium is manufactured by using a substrate having the above configuration as at least one of two disc-shaped substrates and joining them via a ring-shaped inner spacer and a ring-shaped outer spacer. You can also.

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

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

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 constant angular velocity, recording light such as semiconductor laser light is irradiated from the substrate side. Irradiation of this light causes pits (
pores) or discoloration of the recording layer.
It is thought that information is recorded by changes in the refractive index due to changes in the association state, etc. 750n as recording light
A semiconductor laser beam with an oscillation wavelength in the range m to 850 nm is used.

The information recorded as above can be reproduced by rotating the information recording medium at the same constant linear velocity as above, irradiating semiconductor laser light from the substrate side, and detecting the reflected light. .

Incidentally, in the case of a flexible disk, etc., the laser beam irradiation may be performed from the recording layer side.

Examples and comparative examples of the present invention are described below. However, these aspects do not limit the present invention.

The following margin [Example 1] The following indolenine dye: 1.7 g and the following dye (IRG-023, manufactured by Nippon Kayaku ■): 0.17 g were combined with 2,2,3,3-tetrafluoropropane. A dye coating solution was prepared by dissolving the dye in a 100 ml tool 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: 1.6 μm, 2) Information playback area: Pit width + 0.55 μm, Pit depth: 1100X, Area: radius 23-32 mm pit information 20D format EFM signal (radius 23
~25mm range is lead-in information, radius 25~32m
m range is music information) 3) Focusing area (17 in Figures 3 and 4); Pit width: 0.55 μm, Pit depth: 1100, Area: radius 32 to 35 mm Pit information: CD format EFM signal (radius 32
~35mm range is lead-out information, radius 33~35
4) Groove area Nigel loop width: 0.47 μm, group depth: 900 mm, area radius 35 mm to 58 mm Rotate the nozzle of the spinner at a speed of 200 Radius of the substrate surface on the side where the RPFLL pregroove is provided 50.0
Start applying the above dye coating liquid at a position of mm, move to a position with a radius of 35.0 mm in 2 seconds, stop moving for 1 second while keeping it applied, and move to a position with a radius of 50.0 mm in 2 seconds. Move the spinner and apply it for 5 seconds while keeping the spinner rotation speed at 200 rpm, and gradually increase the rotation speed by 50 rpm every second until the final rotation speed is 1000 after 16 seconds.
rpm and hold in this state for 30 seconds to dry.
A dye recording layer having a layer thickness of 1400× within the grooves and a layer thickness of 100× between the grooves was formed up to the outer periphery of the substrate. The radius of the formation position of the obtained dye recording layer (inner peripheral edge) is 3
In the range of 4±0.5 mm, the refractive index was 2.8±0.1.

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

Further, on the reflective layer, apply the above-mentioned coating liquid for forming a protective layer (product name: 3070, which is an ultraviolet curable resin, manufactured by Three Pond Co., Ltd.)
Coating was started using a spin code method at a rotational speed of 20 rpm, maintained for 5 seconds to complete the coating, and the rotational speed was increased to a final rotational speed of 1500 rpm for 30 seconds for drying. Next, the coating layer is irradiated with ultraviolet light (
A protective layer having a thickness of 2 μm was formed by applying a 200 W 70 m 2 mercury lamp for 10 seconds.

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

[Example 2 In Example 1, 2.55 g of the following indolenine dye and 0.255 g of the above dye (IRG-023, manufactured by Nippon Kayaku ■) were used as the dye.
4) The same substrate as Example 1 was used except that the depth of the groove in the groove area was set to 1700 mm, and the conditions for applying the dye coating liquid were as follows. An information recording medium was manufactured in the same manner.

Coating conditions: The nozzle of the Nisbiner was rotated at a speed of 200 rpm, and the radius of the substrate surface on the side where the pregroove was provided was 50.
Start applying the above dye coating liquid at the 0 mm position, move to a position with a radius of 35.0 mm in 2 seconds, and continue applying it for 1 minute.
Stop moving for 2 seconds, move to a position with a radius of 50.0 mm in 2 seconds, apply the spinner for 5 seconds while maintaining the spinner's rotation speed of 200 rpm, and gradually increase the rotation speed by 50 rpm per second to 8 After a second, the rotation speed was held at 1500 rpm for 10 seconds, the final rotation speed was set at 2000 rpm, and held for 2 seconds, and then dried until the layer thickness in the groove was 2000 rpm.
A dye recording layer having a layer thickness of 100 OX between the X and grooves was formed up to the outer periphery of the substrate. The refractive index was 2.6±0.1 within a radius of 34±0.5 mm at the formation position (inner peripheral edge) of the resulting dye recording layer.

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

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

[Comparative Example 3] An information recording medium was manufactured in the same manner as in Example 2, except that no pits were provided in the focusing area (3) of the substrate and a blank surface was formed.

[Evaluation of information recording medium] 1) Remove the minimum average reflectance near the boundary between the pit area and the groove area from the CD player (CD-1000, manufactured by Yamaha ■) to an optical disk evaluation machine (DDUlooO, manufactured by Pulstech Industries ■). The optical disk obtained above was reproduced using a device equipped with an optical head (wavelength near 80 nm). A reproduced signal was extracted with DC, and a voltage corresponding to the average reflectance of the reproduced signal was measured with a voltmeter. The reflectance value is determined by measuring a portion of the mirror of a commercially available CD with a reflectance meter (manufactured by Mizojiri Optics), measuring the voltage of the mirror portion as described above, and using this value as a reference to determine the reflection of the optical disc. The rate was calculated.

The optical head was moved over a radius of 32 to 33.5 mm on the optical disk in increments of 1 mm, and the reflectance for each radius was measured, and the minimum value was taken as the minimum average reflectance.

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

The above measurement results are shown in Table 1.

Table 1 below: Minimum average reflectance Continuous reproducibility (%) Example 1 50 Re-example 2 45 Comparable example 1 20 Comparable example 2 28 Comparable example 3 54 Not possible As is clear from Table 1 above The optical disks (Examples 1 and 2) in which the dye recording layer near the inner peripheral edge is formed on the pit area of the present invention have a high minimum average reflectance near the boundary between the pit area and the groove area, so it is difficult to read. Even if a commercially available CD player that requires high reflectance performs a seek across the boundary between the pit area and the groove area, no focusing failure (misalignment) will occur.

In optical discs with low reflectance like Comparative Examples 1 and 2,
When a commercially available CD player performs a seek that jumps over boundaries, focusing failures tend to occur.

Furthermore, as in Comparative Example 3, if the boundary is made into a brain, there is no problem of poor power output when seeking by jumping over the boundary, but continuous playback may become impossible. Furthermore, with such a disc, it is difficult to control the position of the optical head in the recording device.

[Brief explanation of 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 groove area 6 in FIG. 1 above.
FIG. 2 is a partially enlarged sectional view of the vicinity of the boundary between 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 cross-sectional view of the vicinity of the focusing area 17 in FIG. 3 above. Disc-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 = 8.18 Pre-groove: 9.19 Information playback area: 2,

Claims (1)

[Claims] 1. A pit region in which pits are formed and a groove region in which a pregroove is formed are provided on a disc-shaped substrate, and a recording layer made of a dye on which information can be written by a laser is provided on the groove region, In an information recording medium in which a reflective layer made of metal is provided over the entire surface from the pit area to the recording layer, a peripheral edge of the recording layer on the pit area side forms a boundary between the groove area and the pit area. An information recording medium that extends beyond the pit area and exists within the pit area. 2. The information according to claim 1, wherein the pit area consists of an information reproduction area on the inner circumferential side and a focusing area on the outer circumferential side, and a peripheral portion of the recording layer on the pit area side exists within the focusing area. recoding media.