JPH04143938A - Information recording medium - Google Patents

Abstract

PURPOSE:To improve focusing and to prevent tracking and reading error by providing a recording layer consisting of a dye which allows writing by a laser on the outer peripheral edge of a annular recording region and focusing region and providing a metallic reflection layer thereon. CONSTITUTION:The information recording medium is constituted of the disk- shaped substrate 1, the recording layer 2 which is provided on the outer periphery thereof and consists of the dye to allow writing by the laser, the metallic reflection layer 3 on the layer 2 and a protective layer 4 thereon. The recording medium is provided with a reproducing region 5 provided with pits on the inner peripheral side substrate, the recording region 6 which is formed with grooves and is recordable on the outer peripheral side substrate, and a focusing region 7 which is formed with grooves between the region 7 which is formed with grooves between the regions 5 and 6. The peripheral edge of the recording layer 2 is formed in the region 7. Cyanine dyes, such as indolenine dyes and imidazoquinolisane dyes, and phthalocyanine dyes, etc., are used for the dyes of the layer 2.

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 DRAW (formerly rect Read After
The basic structure of the write (writable) type information recording medium is a disc-shaped transparent substrate made of plastic, glass, etc., and a Bi, Sn, In, Te, etc.
It has a recording layer made of a metal or metalloid such as, 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 bit 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.

The compact disc (CD), which is an optical disc for information reproduction, generally has a CD format signal, etc.c7) E
F M (Eight to Fourteen M
(duration) It consists of a plastic disc-shaped transparent substrate in which holes (bits) containing digital audio signal information are formed in advance, and a reflective thin film such as An 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 have a CD rating of 1.2~
By rotating and recording at a constant linear velocity of 1.4 m/sec, a bit width of 0.81 Lm and a track pitch of 1.
It is required to have a maximum recording time of 74 minutes at 6gm. Conventionally, such audio CDs
As mentioned above, this is a reproduction-only device with bits formed on the substrate in advance. Also, recently, instead of music information, CD-R discs have been pre-recorded with information such as various documents and still images.
OM (ReadOn17 Memory) has also been put into practical use.

Such optical discs naturally have the disadvantage that information cannot be recorded or edited. Therefore, D RAN (
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).

This (7) RAW type CD (conventional (7) DRAW
In general, there is a playback area (bit area) in which pits are formed for recording information such as address information on the inner circumference of the substrate, and a playback area (bit area) for recording information on the outer circumference of the pit area. A pregroove for guiding the laser has a recording area (group area) provided on the substrate. In addition, recently, an optical disc has been proposed that has the functions of both a playback CD and a DRAW type CD on a single disc (Japanese Patent Application Laid-Open No. 2-42652). A ROM that has a recording area with groups on the board and stores information such as music on the inner circumference side.
It is an optical disc having a region. This allows the user to record data and memos on the same disc while sharing the same information (music and programs) with other people.

According to the above-mentioned Japanese Unexamined Patent Application Publication No. 2-42652, a method for creating an optical disc having such a ROM area and a recording area is as follows: According to the above-mentioned Japanese Patent Laid-Open No. 2-42652, the diameter of the substrate is 80 to 117 mm, which is on the outer circumferential side of the reproduction area (ROM area) having bits on the substrate. In order to form a dye recording layer on a group in the range of , the recording layer is formed by coating the portion outside the diameter of 80 mm by a spin code method. A reflective layer is formed on the ROM area and the recording layer. That is, a recording layer is not formed in the ROM area consisting of pits, but a recording layer is provided only in the group area.

However, the beat and group track widths (
The spacing (distance) is generally about 1.6 pm, and in order to apply the dye coating liquid only to the R (group) area outside the diameter of 80 mm that has the group as described above, the inner periphery of the recording layer must be provided with pits. In other words, since the track width (interval) is on the order of microns as described above, it is necessary to control the coating with extremely high precision. Therefore, it is difficult in manufacturing to form the dye recording layer only in the recording area from the boundary between the reproduction area of the peat and the recording area of the group.

[Purpose of the Invention] As described above, when a dye recording layer is coated on, for example, the outer circumferential side of a substrate by a spin coding method, it is difficult to accurately separate the areas between pit reproduction areas and group recording 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, swells due to surface tension and becomes thicker, so even if the pit reproduction area and group Even if the dye recording layer is formed only on the group on the recording area side from the boundary with the recording area, the layer thickness at the inner peripheral edge of the recording layer (i.e. near the boundary) will become thicker, the reflectance will drop markedly, and the focus will be lost. It has become clear that it is easy to lose focus (defective focusing). If focus is lost, playback stops or goes out of control because a playback signal cannot be obtained. Of course, tracking will no longer be possible.

The present applicant has already filed an application for an information recording medium that solves the above problems (Japanese Patent Application No. 2-218704).
It provides a new and different solution.

The inventors further investigated the above problem and found that when the dye coating liquid is applied on the group, when it is applied on the pit, and when it is applied on the mirror, the inner peripheral edge of the coating layer is It has become clear that the planar shapes shown in a), b), and C) of FIG. 3 are formed. Third
The figure 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 a) groups, b) pits, and c) mirrors.

That is, as shown in a) of FIG. 3, the dye coating layer CD) formed on the substrate having groups (G) and lands (L) has its inner peripheral edge along the groups, and the roundness is uneven. It is formed in a high shape, that is, in a uniform arc shape. Of course, in this peripheral area, the thickness of the dye layer becomes thicker and the reflectance becomes lower.

For this reason, focusing tends to be defective (the jump area cannot be jumped over).

The dye coated layer (D) formed on the substrate having P) (P) is formed on the same track because its inner peripheral edge is not formed along the track, as shown in b) of Fig. 3. Even for a given pit, some are covered with the dye layer and some are not, and the layer thickness and shape of the dye layer are non-uniform. However, in the pit region, pits and a portion of mirrors coexist, so the reflectance is relatively high.

A dye coating layer (
As shown in C) of FIG. 3, in D), the inner peripheral edge does not follow the track, and the thickness and shape of the dye layer are non-uniform. However, unlike the pits and group parts, the mirror part has a high reflectance, but since tracking is impossible in the mirror part, continuous reproduction from the reproduction area to the recording area is generally impossible.

In this way, when a dye recording layer is coated and formed on a group, the layer thickness of the dye layer becomes thick at the periphery, and the reflectance decreases markedly, which tends to cause poor focusing (the jump area cannot be skipped). Furthermore, in some parts of the mirror, continuous reproduction from the reproduction area to the recording area is generally not possible. Furthermore, when the inner periphery of the dye layer exists on the pit, good focusing can be obtained because the 1 reflectance is relatively high, but the inner periphery of the dye layer can be seen from b) in Figure 3. so that it is uneven. For this reason, the unrecordable area must be large, which is disadvantageous from the standpoint of high-density recording.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an information recording medium which is an optical disc having a reproduction area and a recording area, which has good focusing, and does not cause tracking errors or signal reading errors.

Specifically, the present invention provides an information recording medium that is an optical disc having a reproduction area and a recording area, which has good focusing when moving from the reproduction area to the recording area, and does not cause tracking errors or signal reading errors. The purpose is to

Another object of the present invention is to provide an information recording medium that is an optical disc that has a playback area and a recording area, has a small area that cannot be used for both the playback area and the recording area, and is suitable for high-density recording.

Furthermore, the present invention provides an information recording medium which has a playback area where a CD format signal is recorded and a recording area where the CD format signal can be optically recorded, and which is free from tracking errors and signal reading errors. With the goal.

[Summary of the Invention] The present invention provides a regeneration area consisting of pits formed in an annular shape on a disk-shaped substrate, and a circular area having a radial width of 0.1 to 5.0 mm in contact with the outer peripheral edge of the regeneration area. A focusing area formed in an annular shape and consisting of a group having a shallower depth than the group of recording areas described below, and a recording area consisting of a group formed in an annular shape in contact with the outer periphery of the focusing area are provided, and the recording area and at least the focusing area are provided. A recording layer made of a dye on which information can be written by a laser is provided on the outer peripheral edge of the area, and a reflective layer made of metal is provided on the entire surface from the reproduction area to the recording layer. It's in the medium.

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

l) The radial width of the focusing area is 061~
The above-mentioned information recording medium is characterized in that it is in the range of 2.5 mm.

2) The information recording medium described above, wherein the depth of the focusing area group is deeper than half the depth of the pits in the reproduction area and shallower than the depth of the recording area group.

3) The depth of the focusing area group is 800
The above-mentioned information recording medium is characterized in that it is in the range of 1500H to 1500H.

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

5) The information recording medium described above, wherein the depth of the focusing area group gradually increases from the reproduction area side to the recording area side.

6) The information recording medium, wherein the information on the reproduction 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, pyrylium dyes, thiopyrylium dyes, naphthalocyanine dyes, and phthalocyanine dyes.

[Effects of the Invention] In the information recording medium of the present invention having a reproduction area and a recording area, the inner peripheral edge part (the peripheral edge and the vicinity of the peripheral edge) of the recording layer is between the reproduction area and the recording area. The focusing area consists of groups of shallow depth provided. Therefore, a high reflectance can be obtained even in the focusing area provided between the reproduction area and the recording area.
Good focusing and almost no tracking errors or signal reading errors. Therefore, it is possible to jump between the playback area and the recording area, and continuous playback from the playback area to the recording area is possible. It is possible.

In other words, since the inner peripheral edge of the recording layer exists in the focusing area consisting of groups with a shallow depth, the raised part of the dye at the coating start position on the inner peripheral side of the dye recording layer naturally falls within the focusing area. It is in. In the focusing area, the depth of the group is shallow, and the inner peripheral edge of the dye coating layer formed in the focusing area is formed in a highly circular shape along the group. Since the thickness is averaged (that is, there is no extreme layer thickness unevenness), there is little decrease or fluctuation in the reflectance, good focusing, and almost no tracking failure.

Furthermore, since the focusing area is formed in such a way that the inner peripheral edge of the dye coating layer has a highly circular shape along the group, the focusing area can be set with a narrow width. It can be said that it 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 mentioned above, when the boundary between the reproducing area of a pit and the recording area of a group is a group, the thickness of the dye layer becomes thicker at the periphery of the dye recording layer coated on the group, and the reflectance decreases markedly. If the boundary is a partial boundary, continuous reproduction from the reproduction area to the recording area is generally impossible. In addition, when the boundary is a pit, even if the layer thickness at the inner peripheral edge of the dye recording layer becomes thicker, there is also a mirror part in addition to the bit, so the reflectance is relatively high and good focusing can be obtained, but one dye layer The inner peripheral edge of b) in Fig. 3
As you can see, it is non-uniform. For this reason, it is necessary to make the unrecordable area large, which is disadvantageous from the viewpoint of high-density recording.

The present invention solves the above problem. That is,
The inner peripheral edge of the dye layer is formed in groups as shown in FIG. 3a). By making this region a region (focusing region) consisting of shallow groups, the reflectance is improved and good focusing is maintained. Furthermore, in the focusing area, the inner peripheral edge of the dye recording layer is formed in a uniform arc shape along the group, so the area can be set to a narrow width, making the information recording medium capable of high-density recording.

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 showing 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. It has a structure consisting of a reflective layer 3 provided on the substrate and the recording layer, and a protective layer 4 provided on the reflective layer.

The information recording medium has a reproduction area 5 in which pits are provided as recording signals on the inner substrate, a recording area 6 in which information can be recorded in groups (pre-grooves) formed on the outer substrate, and the above-mentioned information recording medium. A focusing area 7 in which groups are formed is provided between the reproduction area 5 and the recording area 6. A peripheral portion of the recording layer is formed in this focusing area 7. Note that, in general, the vicinity of the inner peripheral edge and the vicinity of the outer peripheral edge of the substrate are plain surfaces on which no pits or groups are formed (not shown).

FIG. 2 is a partially enlarged sectional view of the vicinity of the focusing area 7 in FIG. 1.

The surface of the disc-shaped substrate 1 includes a reproduction area 5 consisting of pits 8 in which information is recorded, and a recording area 6 consisting of groups (pre-grooves) 9 for guiding a laser for recording (or reproduction).
, and a focusing region 7 consisting of a group 10 between both regions.The zero dye R layer 2 is formed not only in the recording region 6 but also in a part of the focusing region 7. 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 depth of group IO in the focusing area of the present invention is shallower than the depth of group 9 in the recording area.

This makes the reflectance high in the focusing area. In other words, the recording layer formed in the focusing area 7 has its raised peripheral edge in particular within the focusing area 7. Such a raised grating edge portion is formed by the 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. Generally, the raised peripheral part of this recording layer is
If it is on a group, the reflectance will drop markedly and poor focusing will likely occur, but in the present invention, the group is shallow, and although the reflectance is slightly lower than on the reproduction area, no focusing fault occurs.

Furthermore, as shown in Figure 3 a), since the dye recording layer is formed only on the group, the inner peripheral edge of the recording layer is
It has a uniform arc shape, and there is no so-called coating unevenness on the inner peripheral edge, and the area (focusing area) that cannot be used for recording or reproduction can be reduced.

What is the depth of the group in the focusing area above?

Generally, the depth is deeper than half of the pit depth in the reproduction area and shallower than the depth of the group in the recording area. The depth of the focusing area group is preferably in the range of 800-1500, more preferably 1000-1500, and the depth of the focusing area group is substantially equal to the bit depth of the reproduction area. It is advantageous and preferable to make the group the same in the focusing area.Although the depth of the group in the focusing area is generally the same in any track within the focusing area, as long as it is shallower than the depth of the group in the recording area, the depth of the group in the focusing area is The depth may vary, and it is particularly preferable that the depth gradually increases from the reproduction area side to the recording area side.

Also, the radial width of the focusing area is 0.1 to 5
mm, preferably from 0.1 to 2.5 mm, more preferably from 0.5 to 2.5 mm, and most preferably from 1 to 2 mm.

By setting the focusing area in this manner, it is possible to obtain an information recording medium that has little decrease or fluctuation in reflectance, provides good focusing, does not become impossible to track, and is suitable for high-density recording.

Furthermore, the above-mentioned optical disc has a playback area in which the CD format is recorded, and after the CD format signal is also recorded in the recording area, in order to perform good playback on a commercially available CD player (laser wavelength near 80 nm). Useful.

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 resins such as polymethyl methacrylate; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers; epoxy resins: amorphous polyolefins and polyesters; 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 glolsulfonated 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 0.005 to 20
．． wm, preferably 0.01 to 10 μm.

On the disk-shaped substrate (or undercoat layer) of the present invention, pits representing information such as address signals, music information, etc. and tracking groups (pregrooves) are formed. When using a resin material such as polycarbonate, the bits and groups are preferably provided directly on the substrate by injection molding or extrusion molding of the resin material.

In addition, the formation of groups etc. may be performed by providing a pre-groove layer.As a material for the pre-groove layer, at least one monomer (or oligomer) selected from monoester, diester, triester and tetraester of acrylic acid is used. ) and a photoinitiator can be used. The pre-groove layer is formed by first coating a mixture of the above acrylic ester and polymerization initiator on a precisely made matrix (stamper), then placing the substrate on top of this coating solution layer. The liquid layer is cured by irradiation with ultraviolet rays through the substrate or the mother mold to fix the substrate and the liquid phase.Next, the substrate is peeled from the mother mold to obtain a substrate provided with a pregroove layer.

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

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, pyrylium/thiopyrylium dyes, and azulenium dyes. , squalirium pigment, Ni
, metal complex dyes such as Cr, naphthoquinone/anthraquinone dyes, indophenol dyes, indoaniline dyes, triphenylmethane dyes, triallylmethane dyes, merocyan dyes, oxonol dyes,
Examples include aminium-based and diimmonium-based dyes and nitrone 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, l,2-dichloroethane, and chloroform; Ethers such as tetrahydrofuran, ethyl ether and dioxane, alcohols such as ethanol, n-propatool, impropatool and n-butamer, amides such as dimethylformamide, fluorocarbons such as 2.2.3.3-tetrafluoropropatol Examples include solvents. 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 coating method, a dip method, a roll coating method, a blade coating 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 5,500X, preferably 200X.
~3000X range.

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, V, Nb, Ta, Cr, Mo
, W, Mn, ReFe, C01Ni, Ru, Rh, Pd
, Ir, PL, Cu, Ag, Au, Z
n, Cd, An, Ga, In,
S i , Ge, Te, Pb, P.

Mention may be made of metals and metalloids such as Sn and Bi. Among these, preferred are An, 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 5iO1S i
o: , MgF2 , SnO, : , S 13NA, and other inorganic substances; examples include organic substances such as thermoplastic resins, thermosetting resins, and UV-curable resins.

The protective layer is formed by applying a film obtained by extruding 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 deposition, sputtering, and coating.
In the case of a thermosetting resin, it can also be formed by dissolving these in a suitable solvent to prepare a coating solution, then 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 further added to these coating liquids 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 the intermediate layer by using

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 1100 JL.

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, each of these aspects does not limit the invention.

Below is kinpaku [Example 1] The following Drenin pigment: g and the following dyes (IRG 023, Nippon Kayaku ■ (manufactured by): g and 3-tetrafluoro Property tool 1 0m ■ Apply ultrasound for 1 hour to A dye coating solution was prepared by dissolving the dye.

Polycarbonate substrate l) Dimensions; Outer diameter: 120mm, Inner diameter: 15mm, Thickness: 1.2mm, Refractive index + 1.58 Track pitch = 1.6Km, 2) Information reproduction (pit) area: Pit radius: 0.55L m・Pit depth: 11001, Area 2 radius 23-35 mm Pit information Wl: cD format EFM signal (radius 2
Lead-in information ranges from 3 to 25 mm, radius 25 to 34
3) Focusing (group) area (7 in Figure 2) Nigel loop radius: 0-47 tiles m Group depth: 1100X, area: radius Range of 35-36.5mm 4) Recording (group) area Nigel loop radius: 0.47 pot m, group depth: 1600X, area two radius range of 36.5mm-58mm Spinner nozzle rotation speed 20 Orpm pre-groove Start applying the dye coating liquid (application diameter: 35 mm) at a position with a radius of 50.0 mm on the substrate surface on the side where
Move to a position with a radius of 35.0 mm in 1 second, stop moving for 1 second while coating, move to a position with a radius of 50.0 mm in 2 seconds, and continue coating while keeping the spinner rotation speed at 200 rpm. Apply it for 5 seconds while holding it, and gradually increase the rotation speed by 50 rpm, reaching a final rotation speed of 1000 after 16 seconds.
rp intestine, held in this state for 30 seconds, and dried.
A dye recording layer having a layer thickness of 1400× within a group and a layer thickness of 100× between groups was formed up to the outer periphery of the substrate. The radius of the formation position M (inner peripheral edge) of the obtained dye recording layer is 3
In the range of 4±Q-5mm, the refractive index was 2.8±0.1. Au was deposited on the above substrate and the dye recording layer using a DC sputtering device under the conditions of Ar pressure of 2 Pa and power of 200 W. Then, sputtering was performed to form a reflective layer with a thickness of 1000λ 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 cord method at a rotational speed of 20 rpm, maintained for 5 seconds, coating was completed, and the rotational speed was increased to a final rotational speed of 150° rpm for 30 seconds to dry. Next, the coating layer is irradiated with ultraviolet light (
A protective layer having a layer thickness of 2 gm was formed by applying a 200 W/cm2 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, as a polycarbonate substrate, the above 3) focusing (group) area (7 in Fig. 2) was set such that the loop width: 0.47 m, the depth of the group: the innermost circumference was 1100X An information recording medium was manufactured in the same manner as in Example 1 using the same substrate except that the radius was set in the range of 35 to 36.5 mm. .

[Comparative Example 1] In Example 1, as a polycarbonate substrate, the above 3) tracking (group) area was not provided, and the area of the above 4) recording (group) area was set to a radius of 35 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 58 mm.

[Comparative Example 2] In Example 1, as a polycarbonate substrate, the above 3) tracking (group) area was not provided, and the area of the above 2) recording (pit) area was set with a radius of 23 m to 36 m.
．． Example 1 using the same substrate except that the range was 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 1 using the same substrate as in Example 1 except that the above 3) tracking (group) area was made into a full-surface mirror as a polycarbonate substrate. did.

[Evaluation of information recording media] 1) Measurement of reflectance near the tracking area or near the boundary between the playback area and the recording area (presence of low reflectance area and reflectance of 30% or less) Optical disk evaluation machine (DDU 1000. Pulse check) The optical disc obtained above was played back using a device equipped with an optical head (wavelength near 80 nm) removed from a CD player (CD-1000, Yamaha Automobiles Co., Ltd.) (manufactured by 2ku Kogyo Co., Ltd.). The reproduced signal was extracted with DC, and the voltage corresponding to the average reflectance of the reproduced signal was measured with a voltmeter. The reflectance value was measured using a reflectance meter (manufactured by Mizojiri Optics) using a mirror part of a commercially available CD.
The voltage of a portion of the mirror was measured as described above, and the reflectance of the optical disk was determined based on this value.

The optical head was moved in 0.1 mm increments over a radius range of 32 to 37 mm on the optical disk, and the reflectance for each radius was measured.The area where the reflectance was less than 50% was determined as the area's convergence. The presence or absence of areas with a rate of 30% or less was investigated.

2) Continuous Reproduction Using the above device, it was investigated whether continuous reproduction was possible while focusing a three-beam optical head to a radius of 32 mm to 37 mm on an optical disk.

The above measurement results are shown in Table 1.

'81 Table Low reflectance area (mm) Reflectance 30% Continuous or less area Reproducibility Example 1 Example 2 1, O O, 8 Comparative Example 1 1.5 Yes Comparable Example 2
2.5 None Comparable example 33.5
No No As is clear from Table 1 above,
In the optical discs (Examples 1 and 2) in which the dye recording layer near the inner peripheral edge is formed on the tracking region 4 of the present invention, the area with high average reflectance near the boundary between the reproduction area and the recording area is large. In a commercially available CD player that requires high reflectivity for playback, focusing fails (out of focus) even when seeking beyond the boundary between the playback area and recording area.
It is thought that there is no occurrence of this. Continuous playback is also good.

In Comparative Example 1, a portion with a reflectance of 30% or less occurs, and when a commercially available CD player performs a seek that jumps over the boundary between the playback area and the recording area, focusing failure (misalignment) is likely to occur.

In Comparative Example 2, there is no part with extremely low reflectance and there is no problem with continuous reproduction, but the low reflectance area is wide and the area that cannot be used for recording becomes large.

In addition, as in Comparative Example 3, if the boundary is made of a mirror, there will be no problem of poor force shifting when seeking across the boundary, but the low reflectance area will be large and the area that cannot be used for recording will be large, and the continuous Playback is also impossible. moreover,
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 is a partially enlarged cross-sectional view of the vicinity of the tracking area 7 in FIG. 1 above. FIG. 3 is a plan view showing the shape of the inner periphery when the dye recording layer is formed on each of the group portions, pit portions, and mirror portions of the surface of the substrate. Disc-shaped substrate = 1 Dye recording layer = 2 Reflection M: 3 Protective layer: 4 Reproducing area: 5 Recording area = 6 Tracking area = 7 Pit: 8, P Group: 9.10, G Land: L Mirror: M Dye coating Layer=D

Claims (1)

[Scope of Claims] 1. A reproduction area consisting of pits formed in an annular shape on a disk-shaped substrate, and a radial width of 0.
A focusing area formed in an annular shape in the range of 1 to 5.0 mm and having a shallower depth than the recording area group described below, and a recording area consisting of a group formed in an annular shape in contact with the outer periphery of the focusing area are provided. A recording layer made of a dye on which information can be written by a laser is provided on the recording area and at least the outer peripheral edge of the focusing area, and the entire surface from the reproduction area to the recording layer is made of metal. An information recording medium provided with a reflective layer.