JPS63259854A - Optical information recording method and optical information recording medium - Google Patents

Abstract

PURPOSE:To permit high-accuracy reading by a commercially marketed CD player by forming a metallic recording layer having >=50% reflectivity on a substrate via an org. matter layer which has >=100 deg.C sublimination or decomposition temp. and is insoluble in water. CONSTITUTION:The org. matter layer which has >=100 deg.C sublimination or decomposition temp. and is insoluble in water is formed to 50-1,000Angstrom thickness on the substrate and further, the metallic recording layer having >=50% reflectivity is formed to 100-2,000Angstrom layer thickness thereon. Bubbles of 0.7-4mu diameter are formed concentrically or spirally at 0.7-4mu intervals on the recording layer and CD format signals are written thereon when <=10mW light is projected on this recording medium while the medium is kept rotating at 1.2-1.4m/sec speed. Light energy is effectively utilized by the intervention of the org. matter layer, by which the recording of good resolution is executed with the small bubble diameters and the distinct boundaries.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a method for recording a CD format signal and an information recording medium on which the CD format signal is recorded.

[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 (CN) have been widely put into practical use for reproducing audio such as music.

Compact discs (CDs) generally contain EFM (Eight to Four) signals such as CD format signals.
teenModulat 1on) Consists of a plastic disk-shaped transparent substrate in which holes (pits) containing digital audio signal information are pre-formed, and a reflective thin film and protective film made of metal such as aluminum provided on this substrate. There is. 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, the CD length is 1.2 to 1.4 m.
By rotating and recording at a constant linear speed of /second, the pit width is 0.8 pLm and the track pitch is 1.6 pLm within the range of a signal surface inner diameter of 45 mm and a signal surface outer diameter of 116 mm.
m is required to have a maximum recording time of 63 to 74 minutes. Conventional audio CDs have pits formed on the substrate in advance (therefore, they do not have a recording layer) and are only for playback, and have the disadvantage that information cannot be recorded or edited. Therefore, D RA W (Direct
ReadAfter Write, writable)
It is desired to develop a type CD.

In addition, files such as documents, data, and still images can also be stored on CD-ROM (Read Only Memory).
) or CD-I (Interactive) DRAW type optical discs are desired.

The basic structure of a normal DRAW type information recording medium is as follows:
A disc-shaped transparent substrate made of plastic, glass, etc.
A recording layer made of a metal or semimetal such as Bi, Sn, In, or Te5 is provided on the second side. 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, causing a local temperature rise, resulting in physical phenomena such as pit formation. Information is recorded by changing its optical properties by causing chemical changes such as physical or phase changes. 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.

However, in such conventional DRAW-type information recording media, since the optical disk is rotated at a high linear velocity during recording, information cannot be recorded unless a wide pit interval is maintained, and it is not possible to record information at a high density at a slow linear velocity. Depending on the CD method used for recording, information could not be written.

Further, even if information could be recorded, commercially available CD players, which require a high reflectance to the laser beam during reproduction, could not read the information.

As an optical disc for recording CD format signals, an optical disc having a recording layer made of a dye or a pigment composition on a substrate, and an optical information recording method using the optical disc have been proposed (Japanese Patent Laid-Open No. 61-237239).
However, these optical discs cannot be said to be sufficient for practical use in terms of recording sensitivity, reproduction sensitivity, etc.

[Summary of the Invention] The present invention provides a method for optically recording a CD format signal on a DRAW type information recording medium, and an information recording method in which a CD format signal is recorded by the method, and the signal can be played back by a commercially available CD player. Its main purpose is to provide a medium.

The present invention provides an information recording medium comprising, on a substrate, a metal recording layer having a sublimation or decomposition temperature of 100° C. or higher and a reflectance of 60% or higher via an organic layer that is insoluble in water. The optical information recording method comprises recording a CD format signal in a bubble mode by irradiating the recording layer with light while rotating the disc at a constant linear velocity of 1.2 to 1.4 m/sec.

[Effect of the invention] Since the recording layer of the information recording medium on which the CD format signal is recorded in bubble mode using the above method has a high reflectance, the recorded signal can be used with high precision on a commercially available CD player. can be read.

The information recording medium used in the present invention can write EFM signals with an irradiation power of 10 mW or less, exhibits a reflectance of 60% or more on a plain surface, and can be read by a commercially available CD player. Therefore, it can be used as a DRAW type compact disc.

[Detailed description of the invention] The information recording medium used in the optical information recording method of the present invention is
For example, it can be manufactured by the following method.

The substrate used in the present invention can be arbitrarily selected from various materials used as substrates for conventional information recording media. Optical properties, flatness, processability of the substrate,
In terms of ease of handling, stability over time, and manufacturing cost,
Examples of substrate materials include glass such as soda lime glass; acrylic resins such as cell cast polymethyl methacrylate and injection molded polymethyl methacrylate; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers; epoxy resins; and polycarbonate. ; Examples include amorphous polyolefins. Among these, preferred are polymethyl methacrylate, polycarbonate, epoxy resin, amorphous polyolefin and glass.

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 and preventing deterioration of the recording layer. Examples of materials for the undercoat layer include polymethyl methacrylate, acrylic acid/methacrylic acid copolymer, nitrocellulose, polyethylene,
Polymer substances such as polypropylene and polycarbonate; organic substances such as silane coupling agents; and inorganic oxides (Si02, A-203, etc.), inorganic fluorides (MgF2)
Examples include inorganic substances such as.

In the case of a glass substrate, in order to prevent adverse effects on the recording layer due to alkali metal ions and alkaline earth metal ions liberated from the substrate, wood-philic groups such as styrene/maleic anhydride copolymer and/or maleic anhydride are added. Preferably, a subbing layer made of a polymer having acid groups is provided.

The undercoat layer can be formed by, for example, dissolving or dispersing the above-mentioned substance in a suitable solvent, and then applying this coating solution to the substrate surface by a coating method such as spin cording, dip coating, or extrusion coating.

Further, a layer of pregrooves may be provided on the substrate for the purpose of tracking grooves, or a layer of prepits may be provided for the purpose of forming unevenness representing information such as address signals. As the material for the layer such as the pregroove, 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 layer thickness of the layer such as pregroove is generally 0.05 to 100
JLm, preferably 0.1 to 50 gm. Furthermore, in the case of a plastic substrate, pregrooves or the like may be formed directly on the substrate surface.

An organic layer is provided on the substrate of the information recording medium of the present invention (via a layer such as a pregroove or an undercoat layer, if desired). This makes it possible to reduce the loss of thermal energy due to laser beam irradiation from the recording layer to the substrate due to thermal conduction, and the absorbed heat can be effectively used to thermally deform the recording material. can do. Furthermore, since the recording material in the thermally deformed area is organic and easily aggregates into small spheres, the boundary between the recorded trace and the non-irradiated area becomes clear, resulting in recording with good resolution.

There are various organic substances that can be used in the present invention. The necessary conditions for such an organic substance are that it is solid at a temperature of 100° C. or lower, does not sublimate or decompose, is insoluble in water, and has properties that allow it to be formed into a film in vacuum. Furthermore, it is preferred that the melting point and sublimation temperature are as low as possible. Examples of such organic substances include pyrene,
perylene, anthraquinone, thianthrene, quanine,
Mention may be made of hexamethylbenzene, benzoin, anthracene, trans-stilbene, phenothiazine, fluorene, diphenylurea and fluoranthene.

The organic material layer of the present invention is formed using one or more of the above organic materials by a known method such as vacuum evaporation, sputtering, or ion blasting. The layer thickness is
It is preferably within the range of 50 to too much.

As the material for the metal recording layer, metals with a low melting point and low reflectance are generally preferred because they provide good recording sensitivity. For example, M
g, Mn, Cu, Zn, A! 2. , Ge, In, Sn,
Bi etc. are practical. The metal recording layer of the present invention has a reflectance of 60% or more and an information recording medium of 1.2 to 1.
．． A CD format signal can be recorded in bubble mode by irradiating light onto the recording layer while rotating at a constant linear velocity of 4 m/sec. That is, the recording layer of the information recording medium of the present invention is required to have high reflectance because recorded signals need to be read with high precision by a commercially available CD player. Metal recording layers with high reflectance generally tend to have low recording sensitivity, but in addition to the synergistic effect of the combination of the organic material layer and the following metals, they also have a constant linear velocity (1, 2 to 1.4 m/sec), the recording layer of the information recording medium of the present invention is fully capable of recording CD format signals in bubble mode by irradiating the recording layer with light. It is.

The material for the metal recording layer is a metal with a reflectance of 60% or more, such as Al, Zn, Sb, Cd, Ga, Au, Ag.
, Te, Bi, Ti, Fe, Ge, Cu, Rh, In,
One or more metals are selected from Pb and the like. Preferably, it is selected from Al, Pb, Ge and In.

The layer thickness may be any thickness that can provide a reflectance of 60%, and is preferably in the range of 100 to 2000.

The recording layer is formed into an organic layer using the above recording layer material by a known method such as vapor deposition, sputtering, or ion blasting. However, if desired, an intermediate layer may be interposed between the organic layer and the recording layer. The recording layer may be a single layer or a multilayer.

Preferably, a protective layer is provided on the recording layer. The protective layer is preferably a laminate of a soft protective layer made of a soft resin material and a hard protective layer made of a hard resin material. This laminate is laminated on the recording layer with the soft protective layer side facing the recording layer side. Examples of the soft resin material include polyurethane, polyvinylidene chloride, ethylene/vinyl acetate copolymer, silicone rubber, styrene/butadiene rubber, polyvinylidene chloride, and polyacrylic acid ester. Typically these are solution applied, latex applied,
It is applied onto the recording layer by a method such as melt coating, and is subjected to treatments such as drying and heating if necessary to form a soft protective layer. The thickness of the soft protective layer is usually in the range of 100~5 #L, m, preferably in the range of 0.3~3 gm. Examples of hard resin materials include ultraviolet curing resins and thermosetting resins. Usually, these are applied onto a soft protective layer by a method such as solution coating, and if necessary, a treatment such as ultraviolet irradiation or heating is performed to form a hard protective layer. The thickness of the hard protective layer is usually in the range of 0.1 to 10 JLm, preferably in the range of 1 to 3 pm.

The surface of the substrate opposite to the side on which the recording layer is provided is coated with inorganic substances such as silicon dioxide, tin oxide, and magnesium fluoride, or thermoplastic resins and photocurable resins to improve scratch resistance and moisture resistance. A thin film made of a polymeric substance such as a molded resin may be provided by a method such as vacuum evaporation, sputtering, or coating. In a bonded type information recording medium, two substrates having the above structure are bonded together with an adhesive. It can be manufactured by joining using etc. In an air sandwich type recording medium, at least one of the two disk-shaped substrates has the above-described structure, and the substrate is attached to one or both of the substrates via a ring-shaped outer spacer and an inner spacer, or to one or both of the substrates. It can be manufactured by joining via provided protrusions.

Next, information can be recorded using the above information recording medium by the optical information recording method of the present invention as described below.

First, while rotating the information recording medium at a constant linear velocity within the range of 1.2 to 1.4 m/sec, recording light such as semiconductor laser light is irradiated from the substrate side. Generally, a semiconductor laser beam having an oscillation wavelength in the range of 750 to 850 nm is used as the recording light. The information recording medium of the present invention can record with a laser power of 10 mW or less, and has high sensitivity.

By the above recording method, bubbles with an aperture of 0.70 to 4.07 zm are formed on the surface of the recording layer in contact with the organic layer.
They are formed concentrically or spirally at intervals of 0.70 to 4.0 gm. A CD format signal is then written to the recording layer.

During recording, it is preferable to perform tracking control using a tracking pregroove. When a pregroove is provided on the recording medium, the signal may be recorded either at the bottom of the group or in the area between the groups.

With this method, for example, if the inner diameter of the signal surface is 50 mm,
A recording medium with an outer diameter of 115 mm allows recording for 60 minutes or more.

Information can be reproduced by rotating the recording medium at the same constant linear velocity as described above, irradiating semiconductor laser light from the substrate side, and detecting the reflected light. In the present invention, since the recording layer has a high reflectance of 60% or more on a plain plane, it can be read satisfactorily using a reprint CD player.

Note that the information recording medium of the present invention includes a CD-ROM, a CD-ROM, and a CD-ROM.
It is wood-compatible with media recorded in CD format such as I.

Next, examples of the present invention will be described. However, each of these aspects does not limit the invention.

[Example 1] Disc-shaped polycarbonate substrate with tracking grooves (outer diameter = 120 mm, inner diameter: 15 mm, thickness: 1.2
mm, depth 0.0mm in the range of inner diameter 45mm to outer diameter 116mm.
07gm, width 0.8Ji, m, pitch 1.671. m grooves are provided in a spiral shape), anthraquinone is added as an organic material to a layer thickness of 200X,
A film was formed by vacuum evaporation to provide an organic layer. Next, 60% by weight of each of In and An was added onto this organic layer.
: 40% by weight was co-evaporated to form a recording layer with a thickness of too much.

[Evaluation of information recording medium] A disc evaluation device (Naka
michi Disk evaluation device 0MS-1000) and E
Using an FM encoder (KEN-WOOII), the reference signal (8.15 Hz) was converted to EFM-CD near-o? at a recording power of 9.0 mW and a constant linear velocity of 1.3 m/sec. −／
When recording was performed using the default signal, recording was possible.

Next, the information recorded on the recording medium was reproduced using a commercially available CD player (Sony, D-50MKII). The obtained reproduced signal was at a good level.

Claims (1)

[Claims] 1. On the substrate, through an organic layer having a sublimation or decomposition temperature of 100°C or higher and insoluble in water, a layer with a reflectance of 6.
While rotating an information recording medium comprising a metal recording layer having a metal recording layer of 0% or more at a constant linear velocity of 1.2 to 1.4 m/sec, the recording layer is irradiated with light to generate a CD format signal in a bubble. An optical information recording method comprising recording in a mode. 2. The organic layer contains pyrene, perylene, anthraquinone, thianthrene, guanine, hexamethylbenzene,
2. The optical information recording method according to claim 1, which comprises one or more organic substances selected from benzoin, anthracene, trans-stilbene, phenothiazine, fluorene, diphenylurea, and fluoranthene. 3. The optical information recording method according to claim 1, wherein the thickness of the organic layer is within a range of 50 to 1000 Å. 4. The optical information recording method according to claim 1, wherein the metal recording layer is made of one or more metals selected from Al, Pb, Ge, and In. 5. The optical information recording method according to claim 1, wherein the thickness of the metal recording layer is within a range of 100 to 2000 Å. 6. On the substrate, the sublimation or decomposition temperature is 100°C or higher,
An optical information recording medium comprising a metal recording layer having a reflectance of 60% or more via an organic layer insoluble in water, and a CD format signal being recorded in bubble mode on the information recording medium. . 7. The organic layer contains pyrene, perylene, anthraquinone, thianthrene, guanine, hexamethylbenzene,
7. The optical information recording medium according to claim 6, comprising one or more organic substances selected from benzoin, anthracene, trans-stilbene, phenothiazine, fluorene, diphenylurea, and fluoranthene. 8. The optical information recording medium according to claim 6, wherein the thickness of the organic layer is within a range of 50 to 1000 Å. 9. The optical information recording medium according to claim 6, wherein the metal recording layer is made of one or more metals selected from Al, Pb, Ge, and In. 10. The optical information recording medium according to claim 6, wherein the thickness of the metal recording layer is within the range of 100 to 2000 Å.