JPH0386942A - Optical information recording method and information recording medium - Google Patents

Abstract

PURPOSE:To provide the recording method which has the high C/N of recorded information and modulation degree of signals by irradiating the grooves of pregrooves with a laser beam from a substrate side while rotating the information recording medium provided with a specific recording layer at a specific constant line speed, thereby recording the information. CONSTITUTION:The pregrooves having the depth (h) of the grooves ranging 600 to 1,000Angstrom and the half-amplitude level W of the grooves ranging 0.4 to 0.7mum are formed on a substrate. The information recording medium provided with the recording layer which consists of a metal contg. Se and Te and allows writing and/or reading of the information by the laser beam via an intermediate layer consisting of fluoroplastic having the layer thickness ranging 500 to 1,000Angstrom on the substrate is rotated at 1.2 to 2.8m/sec constant line speed. Further, the grooves of the pregrooves are irradiated with the laser beam from the substrate side to record the information. The recording signals having the excellent C/N of reproduction and modulation degree of the signals, etc., are obtd. in this way and further the good tracking property at the time of recording is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a method for recording information using light and an information recording medium on which information is recorded 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 (CO) have been widely put into practical use for reproducing audio such as music.

Read-only CDs (compact discs) are made based on the CD standard and are read (played) while rotating the CD at a constant linear speed of 1.2 to 1.4 m/s.
Within the range of signal surface inner diameter 45mm and signal surface outer diameter 116mm, bit width 0°8μm, track pitch 1.6μm
It is required to be able to record up 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 ReadA
Writeable CDs have been developed, and some of them have already been put into practical use as optical discs that can be played on commercially available CD players.

In addition, files such as documents, data, and still images can also be stored on CD-ROM (Read Only Memory).
y) or CD-I (Interactive)
Optical discs that can be read by computers are currently being developed. Furthermore, optical discs that can be recorded and played back using playback devices for CD-ROMs, etc.
In other words, CD-WORM is an optical disk floppy that can write and read CD format signals.
(Write 0nce Read Memory) is also being developed. These are attracting attention as recording media that can replace so-called magnetic floppy disks.

DRAW type information recording media (optical disks) are already known, and the basic structure of this information recording medium is a disc-shaped transparent substrate made of plastic, glass, etc., and Bi, Sn, and I provided on this. It has a recording layer made of metal or semimetal such as n, Te, Se, etc. Information is written on an optical disk by, for example, irradiating the optical disk 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 or phases. Information is recorded by causing a chemical change such as a change in 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. Laser beam irradiation for writing and reading information on the optical disc is usually performed at a predetermined position on the disc surface. In order to guide the laser beam so that it accurately follows the intended irradiation position (generally called pregroove or tracking), a rectangular pregroove (tracking guide) as shown in attached Figure 1 is provided on the disk surface. This is common.

Optical discs record information at high linear speeds.
(International Organization for Standardization) compatible types are common and are being actively developed and put into practical use. Since the recording speed of this ISO compatible optical disc is performed at a constant angular velocity, the linear velocity on the outer circumferential side is particularly high.

Since this optical disc is required to have a large degree of signal modulation, recording is generally performed between the grooves of the pregroove (between the grooves), that is, in many cases on the lands. In addition, regarding the dimensions of the pregroove used in 15O (International Organization for Standardization) compatible optical discs, please refer to R-Optical Disc Standardization Trends Explanatory Material J (edited by Optical Industry Promotion Association/Optical Disc Council, p. 113, December 1988). published on the 8th of May).

An optical disk has a basic structure in which a recording layer is provided on a substrate having the pregroove, and it is desired to improve the tracking as well as the recording/reproducing characteristics and durability. In particular, in order to improve the performance of the above-mentioned ISO compatible optical discs, research has been carried out to improve the recording layer thereof, and the above-mentioned materials have been proposed and put into practical use.

On the other hand, CD-type optical discs that record CD format signals at slow linear speeds, unlike ISO-compatible discs, generally record in grooves, and high-density recording is performed with short pit intervals. . As mentioned above, the CD-type optical disc has a particularly high reflectance, and the recorded signal can be played back by a commercially available CD player.
RAW type CD-ROMs and CD-ROMs that do not require particularly high reflectivity but require a high degree of signal modulation.
There is also a CD-WORM type that operates with a playback device or the like. Even if the shapes of these pregrooves are the same as those of the ISO type, which requires recording with a high degree of modulation at a high linear velocity, it is not necessarily possible to obtain excellent recording/reproducing characteristics and tracking performance.

Regarding groove shapes suitable for such CD types, Sony ■ and N.V. Philips of the Netherlands have published Blue Book J (Blue Book
) (Nikkei Electronics, No. 443, 1988.3
Monthly 21st issue, pages 88-89 etc. That is, when recording is performed on the recording layer of an optical disc by laser irradiation, the groove width is 0.4 to 0.4 on a medium whose reflectance decreases after recording (the reflectance of a portion of the mirror is 15 to 45%).
The groove width should be narrow in the range of 0.7 μm, and the groove width should be wide in the range of 1.0 to 1.2 μm for media whose reflectance increases after recording (reflectance of a part of the mirror is 10 to 30%). is listed. Also, the depth of the groove is 1
A range of /7 to 1/9 wavelength is described.

However, what kind of recording layer or other functional layer should be provided in such a groove to ensure that the recording sensitivity when recording the above information and the recording and reproduction characteristics such as C/N are sufficiently satisfied? Or is it possible to obtain a groove signal that allows good tracking both before and after recording?
In particular, it has not been clarified whether the push-pull method provides superior tracking performance.

[Objective of the Invention] The present invention has a high C/N of recorded information and a high degree of signal modulation, almost no deterioration of the C/N when repeatedly reproduced, and also has excellent tracking performance during recording or reproduction.
In particular, the object of the present invention is to provide an optical information recording method with good tracking performance using the push-pull method.

Another object of the present invention is to provide a method for recording information in a groove of a pregroove as a signal with a high C/N and signal modulation degree with good tracking at a slow linear velocity.

Another object of the present invention is to provide a method for recording CD format signals at slow linear speeds.

Furthermore, the present invention provides a CD-WO on which a CD format signal that can be played by the CD-ROM playback device described above is recorded.
An object of the present invention is to provide an RM (CD-ROM type writable) type information recording medium.

[Summary of the Invention] The present invention provides grooves with a depth of 600 to 1000 on the surface.
In the range of X and the half width of the groove is 0.4 to 0.7
On a substrate on which pregrooves in the μm range are formed,
An information recording medium provided with a recording layer made of a metal containing Se and Te on which information can be written and/or read by a laser beam through an intermediate layer made of a fluororesin having a layer thickness in the range of 500 to 10000. , 1, 2~
An optical information recording method comprising recording information by irradiating laser light onto the grooves of the pregroove from the substrate side while rotating at a constant linear speed of 2.8 m/sec, and recording information on the surface of the pregroove. is in the range of 600 to 100 OX and the half width of the groove is in the range of 0.4 to 0.7 μm.
The pregroove of an information recording medium is provided with a recording layer made of a metal containing Se and Te, on which information can be written and/or read by a laser beam through an intermediate layer made of a fluororesin in the range of 0 to 1oooo. There is an information recording medium in which bits are formed in grooves.

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

1) The above information can be recorded on an information recording medium of 1.2 to 1.4
The optical information recording method described above is carried out while rotating at a constant linear velocity of m/sec.

2) The above-mentioned optical information is characterized in that the above-mentioned information is recorded by irradiating a groove of the pre-groove from the substrate side with a laser beam while rotating the information recording medium to record an EFM signal in a CD format. Recording method.

3> The above-mentioned optical information recording method, wherein the information is recorded by irradiating the grooves of the pre-grooves with laser light from the substrate side while rotating the information recording medium to form bits.

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

1) The information recording medium, wherein the depth of the groove is in the range of 650 to 900X.

2) The information recording medium, wherein the depth of the groove is in the range of 750 to 850 mm.

3) The above information recording medium, wherein the half width of the groove is in a range of 0.45 to 0.70 μm.

4) The recording layer is made of Se, Teb Me (however, 0
．． 02≦a≦0.35, O, SO≦b≦0.98.0≦
It is a value in the range of C≦0.45, and M is Pb, In,
Ge%S%Sb, As.

Bi, Sn, AJZ, Ga, TfL%Zn, Cd.

Au, Pt%Ag% Cu, Ni, Pd, Rh.

The above-mentioned information recording medium has a composition represented by (representing at least one metal selected from Cr, Mo, W and Ta).

5) The metal represented by M above is Pb, Ge, Au, P
The above information recording medium is made of at least one metal selected from t and sb.

6) On the recording layer, silicon dioxide, tin oxide, magnesium fluoride, titanium oxide, TeaX (where l≦X≦2
), zirconium oxide, and zinc oxide.

7) The above-mentioned information recording medium, characterized in that a layer consisting of TeaX (1,5≦X≦2) is provided on the above-mentioned recording layer.

8) The information recording medium, wherein the intermediate layer has a thickness in the range of 600 to 15,000 mm.

9) The above information recording medium, wherein the intermediate layer has a layer thickness in a range of 1500 to 2000 mm.

10) The fluororesin is at least one resin selected from polytetrafluoroethylene, polyvinyl fluoride, polytrifluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polychlorotrifluoroethylene, and polycarbon monofluoride. The above-mentioned information recording medium is characterized in that:

11) The information recording medium, wherein the fluororesin is polytetrafluoroethylene.

Note that the half width of the groove is the groove width at the 1/2 height position (h/2) of the groove indicated by W in FIG.

[Effects of the Invention] By the recording method of the present invention, which records CD format signals and the like at a slow linear velocity on an optical disc in which a specific intermediate layer and a recording layer are provided on a substrate having the specific groove shape, playback can be achieved. It is possible to obtain a recording signal with excellent C/N, signal modulation degree, etc., and also to have excellent tracking performance during recording, especially tracking performance using the push-pull method.

Furthermore, as in the optical disc of the present invention, by making the intermediate layer made of fluororesin thicker than the conventional layer thickness,
Excellent playback characteristics such as C/N and modulation of the recorded signal with little deterioration even after repeated playback, and almost no recording and playback characteristics even when exposed to high temperature and high humidity for long periods of time. An information recording medium that does not deteriorate and has good storage durability can be obtained. By providing such an intermediate layer, tracking performance during recording, particularly tracking performance by the push-pull method, becomes particularly excellent.

Further, the optical disc used in the recording method of the present invention is particularly useful for CD-WORM, which requires recording CD format signals with a particularly high degree of modulation.

[Detailed description of the invention] The information recording medium used in the optical information recording method of the present invention is
It has a basic configuration in which a recording layer containing Se and Te is provided on a substrate having pregrooves with an intermediate layer made of fluororesin interposed therebetween. The recording method of the present invention is characterized in that information is recorded in the pregroove while rotating the information recording medium at a slow linear velocity.

As mentioned above, CD-compatible optical discs include the high-reflectance type CD-DRAW and the high-modulation type CD-WORM.
The common feature is that the CD format signal is recorded in the groove rather than the land of the pregroove. In other words, CD-DRAW type optical discs are commercially available C
CD-WORM requires high reflectivity because it needs to be playable on a D-player, and CD-WORM requires particularly high modulation because it needs to be played back on a playback device for CD-ROM, which is an optical disk specifically for playback on computers. degree is required. Therefore, CD-WORM is compatible with CD-DR as described above.
Like AW, it is designed to record CD format signals in a groove at a slow linear velocity, and the recorded signal can also be played back at a slow linear velocity, and unlike CD-DRAW, it does not require particularly high reflectance. is required to have a high degree of signal modulation and is required to operate with the CD-ROM playback device described above.

Regarding the above-mentioned CD-WORM type, the dimensions of the pregroove, etc. are described in Blue Book J, as described above. According to this, for media whose reflectance decreases after recording, the groove width is between 0.4 and 0.
．． A narrow groove width in the range of 7 μm, a wide groove width in the range of 1.0 to 1.2 μm for media whose reflectance increases after recording,
Furthermore, it is said that a range of 1/7 to 1/9 wavelength is appropriate for the depth of the groove.

However, if any kind of recording layer or other functional layer is provided in such a groove, the recording sensitivity when recording information, the recording/reproducing characteristics such as C/N will be sufficiently satisfied, and the Even after recording, a groove signal that allows good tracking can be obtained, and it is not clear whether the push-pull method has particularly good tracking performance.

Therefore, the present inventors and others developed a conventional recordable CD (CD-WO
We have conducted various studies on the media in which the reflectance of a part of the RM) mirror is 15 to 45% in terms of the groove width, depth, and layer structure of the recording layer, etc., and found that the present invention can rotate at a slow linear velocity. For example, when recording information on a CD format signal in the groove of the pregroove while recording a CD format signal, in other words, high density recording can be performed and this can be tracked by the push-pull method. The present invention was achieved by discovering the groove shape and layer structure of the recording layer, etc.

That is, the optical information recording method of the present invention is applied to a substrate on which a pregroove is formed, the depth of the groove is in the range of 600 to 1000X, and the half width of the groove is in the range of 0.4 to 087 μm. , layer thickness is 500~10000
An information recording medium provided with a recording layer made of a metal containing Se and Te on which information can be written and/or read by a laser beam through an intermediate layer made of a fluororesin in the range of It is characterized in that information is recorded by irradiating the grooves of the pregroove with laser light from the substrate side while rotating the substrate. Further, the information recording medium of the present invention is an optical disc on which information is recorded by the above recording method. Generally, information is stored by forming pits in the recording layer of the groove of the pregroove.

In addition, for information recording, the information recording medium is 1.2 to 1.4 m/
According to the present invention, this is carried out by irradiating the grooves of the pregroove with a laser beam from the substrate side while rotating at a constant linear speed of seconds, and recording an EFM signal in CD format on the recording layer above the groove. Preferable in terms of effectiveness.

The specific groove shape used in the present invention is one in which the depth of the groove is in the range of 600 to 1000X and the half width of the groove is in the range of 0.4 to 0.7 μm. Has a groove, Te-5
An information recording medium provided with an e-based recording layer has a C
/N, signal modulation degree and other recording and reproducing characteristics, as well as tracking performance, especially tracking performance using the push-pull method, tend to be excellent. Further, the depth of the groove is preferably in the range of 650 to 900×, particularly preferably in the range of 750 to 850×. Further, the preferable range of the half width of the groove is 0.45 to 0.70 μm.
It is particularly preferably in the range of 0.50 to 0.65 μm.

The optical disc used in the present invention has the above-mentioned specific groove shape of the present invention, and has an intermediate layer made of fluororesin between the substrate and the recording layer, and the layer thickness is 500 mm thicker than the conventional layer thickness.
-10,000, thereby significantly improving the recording and reproducing characteristics and the tracking performance by the push-pull method. Furthermore, the recording/reproducing characteristics such as C/N and modulation of the recorded signal hardly deteriorate even after repeated reproduction, and the recording/reproducing characteristics even when exposed to high temperature and high humidity for a long time. It is possible to obtain an information recording medium that also has good storage durability with almost no deterioration.

The reason why the above-mentioned tracking performance is improved by making the intermediate layer made of fluororesin thicker than the conventional layer thickness, and the recording/reproducing characteristics such as C/N and modulation ratio are improved as follows. It is inferred that

Although fluororesin has excellent durability such as water resistance and heat resistance, it cannot be said that its adhesion to the substrate is sufficient, and the intermediate layer of fluororesin may separate from the substrate due to heating caused by laser irradiation during recording. It is thought that it is easy to peel off and change the shape of pits formed by laser irradiation.

In addition, such peeling tends to cause changes in the shape of the groove. By forming a thick intermediate layer as in the present invention, it is possible to prevent the above-mentioned decrease in peeling, enable the formation of uniform bits, and also make it possible to maintain the shape of the grooves. It is assumed that improvements will be made.

The information recording medium of the present invention is manufactured, for example, 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. 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; polyethylene terephthalate. polyesters: mention may be made of polycarbonates and amorphous polyolefins. Among these, preferred are polymethyl methacrylate, polycarbonate, epoxy resin, amorphous polyolefin, and polyethylene terephthalate in terms of substrate optical properties, flatness, processability, handling, stability over time, and manufacturing cost. and polycarbonate is particularly preferred.

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 (S i 02 Aj! 203, etc.), inorganic fluorides (M
Examples include inorganic substances such as gF2).

In the case of a glass substrate, hydrophilic groups such as styrene/maleic anhydride copolymer and/or maleic anhydride are added to prevent adverse effects on the recording layer due to alkali metal ions and alkaline earth metal ions liberated from the substrate. Preferably, a subbing layer consisting of a polymer containing 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 pre-groove layer may be provided on the substrate for the purpose of tracking grooves, or a pre-pit layer may be provided for the purpose of forming unevenness representing information such as an address signal. 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 pregroove etc. layer is generally 0.05~
In the range of 100 μm, preferably 0.1 to 50 μm
within the range of Furthermore, in the case of a plastic substrate, pregrooves or the like may be formed directly on the substrate surface.

An intermediate layer such as a fluororesin is provided on the substrate of the information recording medium of the present invention (via a pregroove layer and an undercoat layer, if desired). This makes it possible to increase recording sensitivity and reduce reading errors (pit error rate).

Examples of materials for the fluororesin layer include the above-mentioned polytetrafluoroethylene, polyvinyl fluoride, polytrifluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polychlorotrifluoroethylene, polycarbon monofluoride, and polycarbonate. Mention may be made of monofluorides. Preferred is polytetrafluoroethylene.

The fluororesin layer can be provided, for example, by sputtering the above material onto the substrate.

The thickness of the intermediate layer ranges from SOO to 10,000X.

Preferably, the range is from 600 to 2000, particularly preferably from 600 to 15ooX, or from 1500 to 2
It is in the range of 0,000 engineering.

In the range of 600 to 1500X, the intermediate layer can be formed in a particularly short time, and the resulting optical disc has excellent recording and reproducing characteristics.
An optical disc with particularly excellent C/N and durability can be obtained.

A recording layer is provided on the intermediate layer of the fluororesin layer or on the substrate.

The recording layer of the present invention is a layer made of metal containing Se and Te.

Preferably, the metal layer is Se, Teb Me (0.02≦a≦0.35.0.50≦b≦0.98.
It is a value in the range of 0≦C≦0.45, and M is Pb% I
n, Ge, S, Sb, As.

Bi, Sn, Aj! , Ga, T11. % Zn, Cd.

Au, Pt, Ag%Cu, Ni, Pd, Rh, Cr, M
o, W, and Ta). Above M
is preferably at least one metal selected from pb, Ge, Au, Pt and sb, particularly preferably pb.

On the recording layer of the information recording medium of the present invention, silicon dioxide,
Tin oxide, magnesium fluoride, titanium oxide, T e O
w (however, 1≦X≦2), it is preferable that layers made of either zirconium oxide or zinc oxide are laminated.

Among these materials, Tea (however, 1≦X≦
It is preferable that the layers consisting of 2) are laminated. More preferably, X in the TeOx is in the range of 1,5≦X≦2.

Although the recording layer containing Se and Te has particularly excellent recording sensitivity, deterioration in sensitivity tends to occur over time after the recording layer is formed. Although the durability is improved by incorporating Se compared to Te alone, it is not sufficient. Above-
Addition of other metals (M) in the formula has the effect of increasing light absorption, improving reflectance, and improving the flatness of the surface of the recording layer, but it does not improve durability. No contribution is seen. Te0X (however,
When layers of 1≦X≦2 are laminated, not only durability is improved, but also small bits can be easily formed without substantially reducing recording sensitivity. The ease of forming small bits in this way results in particularly high resolution of recorded information and high C//
Improvements in recording and reproducing characteristics can be seen, such as a wider latitude, which represents the applicable range of recording power to obtain N. Furthermore, in terms of durability, C
/N decrease is small, and reproduction deterioration characteristics are improved.

The thickness of the recording layer is preferably in the range of 100 to 3000X from the viewpoint of ease of writing information and reflectance.
Particularly preferred is a range of 200 to 1200λ.

The thickness of the TeO3 layer is preferably in the range of 50 to 1000 mm, particularly preferably in the range of 100 to 500 mm.

The recording layer is formed on the substrate by a known method such as vapor deposition, sputtering, or ion blasting using the above recording layer material. Like the recording layer, the Tea layer is also formed on the substrate by a known method such as vapor deposition, sputtering, or ion blasting.

A protective layer may be provided on top of the Tea 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 polycrethane, polyvinylidene chloride, ethylene/vinyl acetate copolymer, silicone rubber, styrene/butadiene rubber, polyvinylidene chloride, and polyacrylic acid ester. Usually, these are applied onto the recording layer by methods such as solution coating, latex coating, and melt coating, and are subjected to treatments such as drying and heating as necessary to form a soft protective layer.

The thickness of the soft protective layer is normal! It is in the range of 00X to 5 μm, preferably in the range of 0.3 to 3 μm. 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 μm, preferably in the range of 1 to 3 μm.

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, magnesium fluoride, and the above-mentioned TeOx, or thermoplastic resin in order to improve scratch resistance and moisture resistance. A thin film made of a polymeric substance such as a photocurable resin may be provided by a method such as vacuum deposition, sputtering, or coating.

Next, information can be recorded using the above information recording medium by an optical information recording method as described below. Since the present invention is particularly suitable for recording CD format signals, this will be explained as an example.

First, while rotating the information recording medium at a constant linear speed of 1.2 to 1.4 m/sec, a recording light such as a semiconductor laser beam is emitted from the substrate side having a pregroove on the surface to the pregroove. CD by irradiating the groove with laser light
The formatted EFM signal is recorded by forming bits (holes) in the recording layer of the groove. Further, in the present invention, when a Tea layer is provided on the recording layer, bits are formed on both the recording layer and the TeOx layer. Generally, a semiconductor laser beam having an oscillation wavelength in the range of 750 to 850 nm is used as the recording light. Generally recorded with a laser power of 3-15 mW.

As a result, bits having a length of 0.70 to 4.0 μm are formed concentrically or spirally at intervals of 0.70 to 4.0 μm in the recording layer.

During recording, tracking control is performed using the tracking pregroove.

The recording of information according to the invention is carried out in the bottom region of the groove of the pregroove.

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.

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, inner diameter 48 mm~outer diameter 117 mrn, depth 620 x 1 half width 0.56 μm, pitch 1.6 μm grooves are provided in a spiral shape), polytetrafluoroethylene is sputtered to form a layer with a layer thickness of 120 mrn.
An intermediate layer of 0i was formed. Then, on this intermediate layer, T
A recording layer having a layer thickness of 700X was formed by co-sputtering e%Se and PB at a ratio of 78 atomic %: 18 atomic %: 4 atomic %, respectively.

Sputtering TeO2 on this recording layer,
A layer of TeO+6 with a layer thickness of 100X was formed.

In this way, the substrate, intermediate layer, recording layer and Te0I
An information recording medium consisting of 6 layers was manufactured.

The above sputtering conditions are: discharge gas: argon, pressure crab 0.5 Pa, and target and substrate open circuit l! :11
It was 00rn.

[Example 2] In Example 1, the depth of the groove on the substrate was changed from 620 mm to 78 mm.
An information recording medium was manufactured in the same manner as in Example 1 except that the 0X was changed.

[Comparative Example 1] In Example 1, the depth of the groove on the substrate was changed from 620 mm to 50 mm.
An information recording medium was manufactured in the same manner as in Example 1 except that the 0X was changed.

[Comparative Example 2] An information recording medium was manufactured in the same manner as in Example 3 except that in Example 2, the half width of the groove of the substrate was changed from 0.56 μm to 0.3 μm.

[Comparative Example 3] An information recording medium was manufactured in the same manner as in Example 3 except that in Example 2, the half width of the groove of the substrate was changed from 0.56 μm to 0.9 μm.

[Comparative Example 4] In Example 1, the depth of the groove on the substrate was changed from 620X to 11
An information recording medium was manufactured in the same manner as in Example 1 except that the material was changed to 00A.

In Examples 1 to 2 and Comparative Examples 1 to 4, the influence of the shape of the groove on various characteristics was mainly examined.

In Example 2 (reprinted), Example 3, Example 4, and Comparative Example 5 below, the influence of the layer thickness of the intermediate layer on various properties was examined.

[Example '3] In Example 2, the layer thickness of the intermediate layer was changed from 1200X to 50X.
An information recording medium was manufactured in the same manner as in Example 2 except that the material was changed to 00X.

[Example 4] In Example 2, the layer thickness of the intermediate layer was changed from 1200X to 18
An information recording medium was manufactured in the same manner as in Example 2 except that the material was changed to 00 or more.

[Comparative Example 5] In Example 2, the layer thickness of the intermediate layer was changed from i zoooX to 3
An information recording medium was manufactured in the same manner as in Example 2 except that the material was changed to 00 or more.

[Evaluation of information recording medium] Regarding the obtained optical disc, the laser power during recording was 3.0 mW, the linear velocity was 1.3 m/sec, and the pulse width was 4.
A signal of 60 n5ec and a frequency of 0.72 M)Iz was recorded and reproduced at a reproduction power of 0-5 mW, and the performance was evaluated as follows.

Under the above evaluation conditions, the following characteristics are generally C/N≧47dB, 0.07≦pp, ≦0.18, RC in order to suppress signal reading errors, tracking errors, etc. and perform good reproduction. It is preferable to satisfy the following ranges: ≧0.20 and reproduction degradation≦3 dB.

1) C/N The reproduction signal of the signal recorded under the above conditions was input into a spectrum analyzer (TR4135: manufactured by Takeda Riken ■), and the carrier and noise ratios were shown when RBWI was 0 kHz and VBWl was 00 Hz.

2) PPaw (push-pull modulation degree) The signal obtained when the reflected light of the laser during playback is received by a two-split diode on an optical disc on which the above signal is recorded, and the received signal is offset by 0.1 μm from the center of the track. The ratio of the amplitude to the amount of mirror reflected light is expressed as pp.

3) Re (Radial Contrast) Recording and reproduction were performed under the above conditions, and the ratio of the amount of reflected light from the groove to the land during reproduction was determined from the following formula.

2X (IL-1a) RC = 1L, +Ia 1L Nikland reflected light amount IG Nigel loop reflected light amount 4) Reproduction deterioration characteristics Reproduction was performed under the above conditions, and the C/N reduction rate after 106 times is shown.

5) Storage Durability After being left at 80° C. and 80% RH for 500 hours, it was regenerated under the above conditions, and the C/N before and after being left was measured to show the decrease.

The above measurement results are shown in Table 1.

Table 1 with margins below C/N (dB) PPaw RC Reproduction poor Storage durability (dB) Longevity (dB) Example 1 Example 2 0.08 0.09 0.20 0.21 Comparative example 1 Comparative example 2 Comparison Example 3 Comparative Example 4 0.06 0.05 0.10 0.08 0.18 0.25 0.16 0.21 Example 2 Example 3 Example 4 0.09 0.09 0.09 0.21 0.21 0.21 Comparative Example 5 0.09 0.21 From the above results (Examples 1 to 2 and Comparative Examples 1 to 4), it was found that A signal recorded at a slow linear velocity on an information recording medium provided with an intermediate layer and a recording layer has a high C/N during reproduction;
Good tracking performance due to push-pull, and RC
The degree of modulation is also high. That is, Comparative Example 1 has a low RC, Comparative Example 2 has a low PPaw, Comparative Example 3 has a low RC, and Comparative Example 4 has a low C/N.

Further, Examples 2.3 and 4 show that the intermediate layer of the fluororesin having the above-mentioned grooves has particularly excellent storage durability within the thick range of the present invention. In particular, Example 4 is excellent in both C/N and storage durability. In Comparative Example 5, in addition to C/N, durability such as storage durability and playback deterioration characteristics is also insufficient.

[Brief explanation of drawings]

FIG. 1 shows a cross-sectional view of a rectangular pregroove provided on the surface of a substrate of an optical disk according to the prior art and the present invention. h Groove depth, groove half width

Claims (1)

[Claims] 1. On the surface, the depth of the groove is in the range of 600 to 1000 Å and the half width of the groove is 0.4.
On a substrate on which pregrooves in the range of ~0.7 μm are formed, information can be written and/or read by laser light via an intermediate layer made of fluororesin with a layer thickness in the range of 500 to 10,000 Å. and an information recording medium provided with a recording layer containing Te in 1.2 to 2.
An information recording method comprising recording information by irradiating a groove of the pregroove with a laser beam from the substrate side while rotating at a constant linear speed of 8 m/sec. 2. On the surface, the depth of the groove is in the range of 600 to 1000 Å and the half width of the groove is 0.4.
On a substrate on which pregrooves in the range of ~0.7 μm are formed, information can be written and/or read by laser light via an intermediate layer made of fluororesin with a layer thickness in the range of 500 to 10,000 Å. An information recording medium comprising a recording layer containing Te and having information recorded in a groove of the pregroove.