JP2002288828A - Optical recording method and optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording method which can record with a high density requested to a phase change type recording medium at a high linear recording velocity, and which can obtain the excellent characteristic having a wide linear velocity margin, and an optical recording medium suitable for this method. SOLUTION: The optical recording method is characterized; in that a laser beam for the irradiation of the phase change type recording medium utilizing a reversible phase change between a crystal phase and an amorphous phase is controlled by three values of recording, erasing, and bottom light-emitting powers; in that the erase level is biased to a constant value; in that an on-pulse time which is the recording power irradiation time and an off-pulse time which is the bottom power irradiation time for a mark nT (where T is a reference clock and n is an integer) to be recorded are made to be OP and FP, respectively, which constitute a pair of pulses; and in that the number N of the pulses of a pulse line satisfies the condition that 0<N<n and N>=2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording medium such as a phase-change optical recording medium and a rewritable optical recording medium, and an optical recording method.

[0002]

2. Description of the Related Art With the rapid spread of rewritable phase change type optical recording media in recent years, higher density and higher speed are increasingly required. In a phase change recording material typified by an Ag-In-Sb-Te system, it is possible to increase the capacity by increasing the NA of the objective lens and shortening the wavelength of the LD. Rewritable DV
D is wavelength 635-660 nm, NA 0.60-NA
The recording density is increased by using 0.65 PUH, and the track pitch is set to 0.74 μm, thereby achieving a capacity of 4.7 GB.

In recent years, in order to further increase the density and capacity, the NA of an LD having a wavelength of 400 nm and the NA of an objective lens have been increased to 0.8.
5, a phase change type recording medium having a capacity of 20 GB or more is being developed by recording on both grooves and lands with a narrow track pitch.

[0004] On the other hand, with the increase in capacity, a high transfer rate is also required. Increasing the recording / reproducing speed is a problem of the phase change type recording medium. In order to rapidly change the phase between the amorphous phase and the crystalline phase, it is required to control rapid cooling and slow cooling at high speed. Therefore, the formation of an amorphous phase is easy, but the formation of a crystalline phase is difficult. Therefore, it is necessary to increase the number of layers for promoting crystallization and increase the number of layers.

On the other hand, instead of the medium configuration, a recording method, particularly an LD
(Hereinafter referred to as a recording strategy). Conventionally, the emission pulse on p
The sum of the times of the ulse and off pulse is the reference clock T,
Based on this pulse, depending on the mark length to be recorded,
A recording strategy in which the number of pulses is increased to form a pulse train is used. However, when recording is performed with a high recording density and a high recording linear velocity, the on-pulse and off-pulse times are both short because the reference clock is short. When the on-pulse time is shortened, it is difficult to raise the temperature required to bring the recording layer into a molten state, so that the sensitivity may decrease or recording may not be performed. Also, of
If the f-pulse time is short, rapid cooling is difficult, which causes problems such as difficulty in forming a mark. In the former case, a high-output LD may be used, but the output of the LD is limited.

[0006]

Therefore, on pulse, of
From the case where the sum of f pulses is based on 1T, a recording strategy based on 2T has been considered (M. Horie, N. et al.
Nobukuni, K.kiyono, andT.Ohno, proceeding of SPIE vo
l.4090 (2000) P135). The layer configuration is a four-layer configuration of a lower protective layer, a recording layer, an upper protective layer, and a reflective layer, which is a conventional configuration. Although 2T is basically used, the mark length to be recorded is an even length (2T, 4T, etc.) and an odd length (3T, 5T, etc.).
Etc.) to change the recording strategy. Thus, a high degree of modulation is obtained even at a linear velocity of 20 m / s, but the linear velocity and the pulse waveform are limited. It is necessary to find a recording method capable of responding to a wide range of conditions from a low linear velocity to a high linear velocity, and a recording layer and a layer configuration suitable for the recording method.

The present invention has been made in view of the above circumstances, and an object of the present invention is to enable recording at a higher recording density and a higher recording linear velocity required for a phase change recording medium. An object of the present invention is to provide an optical recording method capable of obtaining excellent characteristics with a wide speed margin and an optical recording medium suitable for the method.

[0008]

In order to solve the above problems, an optical recording method according to the present invention is directed to a phase change recording medium using a reversible phase change between a crystalline phase and an amorphous phase. The irradiating laser light is controlled by three values of light emission power of recording, erasing and bottom, the erasing level is biased to a constant value, and the mark nT to be recorded (T is a reference clock, n is an integer) is recorded. When the on-pulse time, which is the recording power irradiation time, and the off-pulse time, which is the bottom power irradiation time, are OP and FP, respectively, they are OP and FP.
Is characterized in that 0 <N <n and N ≧ 2.

Further, the invention according to claim 2 is the invention according to claim 1, wherein the time of each pulse OPi, FPi (i = 1, 2,..., N) of the pulse train is variable. There is a feature.

Further, according to a third aspect of the present invention, in the first or second aspect of the invention, 0.5T <O in the i-th pulse OPi, FPi of the pulse train.
Pi + FPi <nT (i = 1, 2,..., N).

The invention described in claim 4 is characterized in that, in the invention according to any one of claims 1 to 3, the pulse start time of the leading part is delayed by 0 to T.

According to the first to fourth aspects of the present invention, it is possible to provide a recording method having a high linear velocity and excellent recording characteristics.

According to a fifth aspect of the present invention, a medium recorded by the method according to the first aspect is configured such that a lower protective layer, a recording layer, an upper protective layer, and an upper second protective layer are formed on a transparent substrate. The layers are laminated in this order, and the reflective layer is made of Ag.

According to a sixth aspect of the present invention, the medium configuration recorded by the method of the first aspect is such that a lower protective layer, a recording layer, an upper protective layer, and a reflective layer are sequentially arranged on a transparent substrate. It is characterized by being laminated.

According to a seventh aspect of the present invention, the recording layer according to the fifth or sixth aspect has a Geα Gaβ Inγ S
bδ Teε, and the atomic ratio (at%) of each element is 0 <α <10,
0 <β <10, 0 ≦ γ <10, 55 <δ <85, 10 <ε <3
It is characterized by being 0.

According to the present invention, a recording medium having a high linear velocity and excellent recording characteristics can be provided.

According to a further aspect of the present invention, there is provided the recording medium according to any one of the first to fourth aspects, wherein the recording layer in the crystalline state is irradiated with a constant biased erasing power. When the recording linear velocity is equal to or higher than the linear velocity at which the recording layer changes into an amorphous phase, recording is performed with a constant erasing power that allows sufficient crystallization regardless of the recording power.

According to a ninth aspect of the present invention, there is provided the recording medium according to any one of the first to fourth aspects, wherein the erasing power with a constant bias is applied to the recording medium in a crystalline state. When the recording linear velocity is equal to or lower than the linear velocity at which the recording layer changes to an amorphous phase, recording is performed with the ratio of recording power to erasing power fixed.

According to the eighth and ninth aspects of the present invention, it is possible to provide a recording method capable of coping with a wide linear velocity with a single recording medium at a high linear velocity.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a recording method and an optical recording medium for obtaining excellent recording characteristics in high-speed, high-density recording of a phase change recording medium. In the present invention, the LD wavelength used for recording is from about 400 nm to 780 nm, and the NA is 0.50 or more.
The purpose is to enable recording at a high recording linear velocity exceeding m / s.

First, the recording method will be described. FIG. 1 shows a conventional recording strategy. Mark length nT to be recorded
With respect to (T: reference clock, n ≧ 2), the light emission pulse waveform of the LD is as shown in the figure. The length of a basic pulse having on pulse and off pulse is T, and this pulse has a waveform in which a plurality of pulses are combined according to the mark length. The level of the pulse height is the power of the LD on the recording medium surface, and from the top, the recording power (Pw), the erasing power (Pe), and the bottom power (Pb). The erase power is biased to a constant value, and the bottom power is equal to or less than the read power. However, depending on the recording, it may be higher than the reproducing power. The actual number of light emission pulses is (n-1) or (n-2) less than n. However, the length of the off pulse of the last pulse can be changed without limitation.

Under these conditions, recording at the same recording density and at a high linear velocity also increases the recording frequency and shortens the reference clock. Therefore, when the onpulse is, for example, constant at 0.5 * T, the actual time is shortened and the temperature rise and melting of the recording layer become difficult,
Sensitivity is reduced and an amorphous phase is hardly formed. Also, on pul
When the se time is set to be long, the off pulse time is shortened, and formation of an amorphous phase is also difficult. Increase the recording linear speed,
In addition, if the recording strategy is constant at any position, the recording strategy may be adjusted to the condition. However, if the recording strategy corresponds to a low linear velocity to a high linear velocity, it is necessary that the recording strategy also corresponds to a wide recording linear velocity. In the conventional recording strategy, when the recording linear velocity is low or the recording density is low, sufficient signal characteristics are obtained. However, in higher density, higher linear velocity recording, it is necessary to devise a recording strategy for obtaining sufficient characteristics.

Therefore, of the recording methods used in the present invention,
As a recording strategy for coping with a high speed and a wide linear velocity, recording, erasing, and bottom are controlled by three luminous powers, the erasing level is biased to a constant value, and (1) mark length nT to be recorded. For (T: reference clock, n is an integer), the on-pulse time as the recording power irradiation time and the off-pulse time as the bottom power irradiation time are OP and FP, respectively. The number N of pulses is 0 <N <n, n ≧ 2. (2) The time of each pulse OPi, FPi (where i = 1, 2,..., N) of the pulse train is variable. Optical recording method.

(3) The i-th pulse OPi,
In FPi, 0.5T <OPi + FPi <nT, i = 1,
2, ---, N (4) Recording is performed in such a manner that the pulse start time at the head is delayed by 0 to T.

Further, as a recording medium suitable for this recording method, (5) a lower protective layer, a recording layer, an upper protective layer on a transparent substrate;
The upper second protective layer and the reflective layer are laminated in this order (see FIG. 3),
When the reflective layer is Ag (6) A lower protective layer, a recording layer, an upper protective layer, and a reflective layer are sequentially laminated on a transparent substrate (see FIG. 4). (7) The recording layer is Geα Gaβ Inγ Sbδ Teε, The atomic ratio (at%) of each element is 0 <α <10, 0 <β <10, 0 ≦ γ <1
0, 55 <δ <85, 10 <ε <30, and the use of a recording layer.

Further, in order to enable recording at a wider linear velocity in the recording medium, (8) the recording layer in a crystalline state is irradiated with a constant biased erasing power, and then the recording layer becomes amorphous. When the recording linear velocity is equal to or higher than the linear velocity at which the phase changes, the recording is performed with a constant erasing power that allows sufficient crystallization regardless of the recording power. (9) The erasing power with a constant bias is in a crystalline state. When the recording linear velocity is equal to or lower than the linear velocity at which the recording layer changes to an amorphous phase after irradiating the recording medium, recording is performed with the ratio of recording power to erasing power fixed.

The details will be described below.

Recording on a phase-change optical recording medium at a high recording density and at a higher linear velocity means that
The reference clock T shown in FIG. 1 becomes shorter. In other words, since the time for heating or cooling the recording layer is shortened,
It becomes difficult to form a mark of a predetermined length or to form a mark at a position of a predetermined mark end. Further, there is a limit in adjusting the on-pulse and off-pulse times within the fixed pulse time T. When the ratio of the on-pulse and the off-pulse time is, for example, 4: 6, the time required to heat the recording layer to a molten state is shortened. However, if the cooling time is sufficient, a higher recording power is required. If you can, you can record. However, since the recording power is limited, as the linear velocity increases, the recording characteristics deteriorate. Even if the thickness of the upper protective layer is increased and heat is stored, the quenching rate becomes slower, and the formation of an amorphous phase becomes difficult. FIG. 2 shows a recording strategy in which sufficient characteristics can be obtained without largely changing the medium configuration or the material of the recording layer.

For the mark length nT (T: reference clock, n is an integer) to be recorded, the on-pulse time as the recording power irradiation time and the off-pulse time as the bottom power irradiation time are OP and FP, respectively. In the case of a set of pulses, the number N of pulses in the pulse train is set to 0 <N <n, n ≧ 2, and the individual pulses OPi and FPi of the pulse train (however,
i = 1, 2,..., N) is variable, and in the i-th pulse OPi, FPi of the pulse train, the sum is T /
By setting 2 <OPi + FPi <nT and setting the pulse start time at the head to be delayed by 0 to T, it is possible to obtain sufficient characteristics. D
When recording at a linear velocity of 21 m / s, which is about six times that of a DVD, while maintaining a recording density corresponding to the capacity of VD, the reference clock is 6.5 nsec. On for heating
When the pulse time and the off pulse time for cooling are set to 1: 1, each time is about 3 nsec. When this is recorded at the basic linear velocity of 3.5 m / s, each becomes 19 nsec. Accordingly, both the heating time and the cooling time are shortened, and either the time required for recording is not sufficient, or either the heating or the cooling time is insufficient. Therefore, by making the number of pulses smaller than before and making the time of each pulse equal to or longer than the reference clock, sufficient time for heating and cooling the recording layer is ensured. This makes it possible to form a mark of a predetermined length and a mark at the time of overwriting. In addition, the characteristics of the mark vary depending on how the shape and position of the mark front end and rear end as well as the length can be controlled. Therefore, in order to reduce the influence of thermal interference due to the previous mark, the start time of the leading pulse is delayed, and the recording start time of the mark and the leading pulse time are adjusted so as to be different from the time of the intermediate pulse portion, and the mark The recording start position can be set to a predetermined position. Further, the time of the trailing end pulse may be similarly adjusted.

The configuration and recording layer composition of a recording medium suitable for these recording strategies and also for a conventional strategy of recording at a low linear velocity will be described. When the lower protective layer, the recording layer, the upper protective layer, and the reflective layer are laminated on the transparent substrate in this order, the lower protective layer, the recording layer, the upper protective layer, the second upper protective layer, and the reflective layer are formed on the transparent substrate. The layers may be sequentially stacked. As the transparent substrate, polycarbonate is used. Other examples include acrylic and PMMA. A transparent dielectric protective layer having a refractive index of 1.8 to 2.2 is provided on the substrate. Dielectrics include oxides, nitrides, sulfides, carbides, and mixtures thereof. Above all, ZnS / SiO
₂ , a mixture of ZnS.ZrO ₂ , ZnS.SiC, and the like are preferable. ZnS and SiO ₂ in the ratio of ZNS · SiO ₂ is,
70:30 to 85:15 is preferred. The same applies to other mixtures with ZnS. The same material as the lower protective layer is used for the upper protective layer. The recording layer has Ga, Ge, In, Sb, and Te as main constituent elements, and the atomic ratio (at%) of each element of GeαGaβInγSbδTeε is 0 <α <10, 0 <β <10, 0 ≦. γ <10,
A phase change material with 55 <δ <85 and 10 <ε <30 is used. The amounts of Sb and Te are preferably such that the composition does not change even if the overwriting is repeated many times, that is, near the eutectic composition. The Sb content is increased to cope with a higher linear velocity, but there is a limit to the Sb content alone because the composition change during overwriting becomes large. Therefore, Ga and In
Is added. If these added elements are too large, segregation of the added elements will occur during overwriting. Ge improves the storability in a high-temperature, high-humidity environment. However, if it is too large, the crystallization temperature is high, the crystallization speed is slow, and the recording characteristics are inferior.

The preferred range of each element is 1 <Ge <5, 1 <G
a <7, 0 ≦ In <6, 60 <δ <80, 15 <ε25.
The reflective layer should have high thermal conductivity and good heat dissipation,
The higher the reflectivity, the better. There are Au, Ag, Al, and Cu alone, or alloys of these, or alloys with other metals. Alloying is effective in suppressing corrosion under high temperature and high humidity. In the present invention, the lower protective layer, a recording layer, an upper protective layer, in the case of four-layer structure of the reflective layer, a lower protective layer, an upper protective layer _{ZNS · SiO 2 (ZnS: SiO} 2 = 80: 2
0), the recording layer was GeGaInSbTe, and the reflection layer was Al.
The main structure is a Ti layer. However, when the upper protective layer is made of a material other than ZNS · SiO ₂ , the reflective layer may be made of Ag, and the reflective layer may be made of Ag or an alloy as long as the upper protective layer does not react with Ag and constituent elements under high temperature and high humidity. In this case, as the upper protective layer, SiN, Al ₂ O ₃ , I
There are oxides such as n ₂ O ₃ and AlN, and nitrides. When the upper protective layer is made of ZNS · SiO ₂ and the reflective layer is made of A
In the case of g, it reacts under high temperature and high humidity to form AgS, and the recording characteristics deteriorate. In this case, a reaction is prevented by providing a second upper protective layer between the upper protective layer and the reflective layer. In this case, the second upper protective layer is made of SiN, Al ₂ O ₃ , In ₂
There are nitrides, oxides, and carbides such as O ₃ , AlN, and SiC, and those having higher thermal conductivity than ZNS · SiO ₂ and strong adhesion to Ag are preferable. The film thickness is 2 nm to 10 nm. The thickness of the other layers is 35 nm to 250 n for the lower protective layer.
m, the recording layer is 5 nm to 25 nm, and the upper protective layer is 5 nm to
The thickness of the reflective layer is 30 nm to 50 nm to 250 nm.

While it is possible to optimize the structure, the material of the recording layer and the film thickness of each layer, and obtain sufficient recording characteristics at a high speed and a wide linear velocity, a single medium has been used under one condition of a linear velocity. However, it is also necessary that one medium can handle a wide range of recording linear velocities. In this case, as the recording medium, when the optimum recording power and the erasing power are irradiated with DC at a certain erasing power, when the linear velocity is changed from a low linear velocity to a high linear velocity, the entire recording layer becomes amorphous from a certain linear velocity. Start to turn.

The following Examples 1 to 8 are cases in which the entire recording layer is still in a crystalline phase near the recording linear velocity. In this case, recording is performed while changing the erasing power while changing the recording power. Also, the mark can be formed uniformly with a predetermined length by recording with the bottom power being equal to or less than the reproduction power and increasing the cooling rate. However, increasing the linear velocity as much as possible is the limit. Therefore, as another recording method to correspond to the linear velocity as fast as possible,
This is a method of recording at a recording linear velocity when the recording layer becomes an amorphous phase when DC power is applied to the erasing power. At a linear velocity in the vicinity, an amorphous phase is easily formed by irradiating recording power at which the recording layer is in a molten state. However, when the erasing power is too high, an amorphous phase is easily formed even at this power. . Therefore, the margin of the erasing power becomes narrow.
In the case of this method, when the erasing power is considerably reduced and the crystallization is performed in a solid state, the unerased residue due to overwriting is reduced. Further, in this case, if the bottom power is too low, the cooling is easily promoted. In order to secure a margin for the recording power, a recording method in which the erasing power is constant is suitable. There are the above two methods for recording at a higher linear velocity.

Examples will be described below.

Example 1-4 On a polycarbonate substrate, ZNS / SiO ₂ 78 nm, Ge Ga InSb
Te 17 nm, ZNS / SiO ₂ 15 nm, Al
Ti was produced in the order of 160 nm by a sputtering method. The thickness of the polycarbonate substrate is 0.6m
m, groove shape is groove depth 350nm, groove width is 0.3μm,
The groove pitch is 0.74 μm. A UV-curable resin having a thickness of 3 μm was formed on the reflective layer to form a protective layer. A polycarbonate substrate of the same thickness without a film was further bonded thereon with an ultraviolet-curable resin to form a medium. The recording conditions were a pickup wavelength, NA of 655 nm and NA of 0.65, and recording was performed with each recording linear velocity and a strategy corresponding to the recording linear velocity. In this case, the ratio between the erasing power and the recording power was kept constant. Table 1 shows the composition of the recording layer and the ratio of erasing power / recording power (Pe / Pw). The recording strategy is shown in Table 3.

[0036]

[Table 1]

[0037]

[Table 2]

A pattern is used and varies depending on the recording linear velocity as shown in Table 1. The recording modulation method is (8-16)
Modulation. The shortest mark is 3T, and the mark length is 0.
4 μm. n is 3 ≦ n ≦ 14, and the mark length was recorded at random. Recording power is 12mW ~ 1
It was changed in the range of 6 mW. The results shown in Table 1 are obtained when recording was performed at a recording power of 15 mW. The bottom power is Pb
The reproducing power is 0.1 mW and the reproducing power is 0.7 mW. The reproduction linear velocity is 3.5 m / s. Degree of modulation: {(reflectance of 14T space)-(reflectance of 14T mark)} / (reflectance of 14T space), and the number of DOWs less than or equal to 10% was shown.

Example 5-8 ZNS.SiO ₂ 78 nm, GeGaInSb on a polycarbonate substrate
Te 17 nm, ZNS / SiO ₂ 12 nm, Si
It was produced by a sputtering method in the order of C 3 nm and Ag 160 nm. The thickness of the polycarbonate substrate is 0.6 mm, the groove shape is a groove depth of 350 nm, and the groove width is 0.3
μm, groove pitch 0.74 μm. A UV-curable resin having a thickness of 3 μm was formed on the reflective layer to form a protective layer. A polycarbonate substrate of the same thickness without a film was further bonded thereon with an ultraviolet curable resin to form a medium. Recording conditions were as follows: pickup wavelength, NA 655 nm, NA 0.
65, and recording was performed using each recording linear velocity and a strategy corresponding to the recording linear velocity. In this case, the ratio between the erasing power and the recording power was kept constant. Table 1 shows the composition of the recording layer and the ratio of erasing power / recording power (Pe / Pw). The recording strategy uses the patterns shown in Table 3 and varies according to the recording linear velocity as shown in Table 1. The recording modulation method is (8-1
7) Modulation. The shortest mark is 3T, and the mark length is 0.4 μm. n is 3 ≦ n ≦ 14, and the mark length was recorded at random. The recording power was changed in the range from 12 mW to 16 mW.

The results shown in Table 1 are obtained when recording was performed at a recording power of 15 mW. Bottom power is Pb0.2m
W, the reproduction power is 0.7 mW. Reproduction linear velocity is 3.5
m / s.

(Comparative Example 1-4) The four-layer structure is the same as that of Example 1
The configuration of the four or five layers is the same as that of the embodiment 5-8. The recording strategy was performed by a conventional method.

(Embodiments 9-11) The layer structure is as described in Embodiment 5-8.
The same as when used in. The composition of the recording layer is as shown in Table 2.

[0043]

[Table 3]

The strategy uses pattern 1, and the reference clock uses a value corresponding to each linear velocity. Recording linear velocity is 11
Pe / Pw = 0.53 at m / s and 13 m / s
0.49, and T is 12.1 nsec. , 10.3n
sec. , Pb was set to 0.2 mW.

At 17 m / s, Pe = 4.0 mW
It was fixed and recorded as Pb 1 mW. as a result,
One recording medium can cope with a wide linear velocity.

With the above-described recording method and recording medium, sufficient characteristics can be obtained even when recording is performed at a higher linear velocity and at a higher density.

[0047]

According to the first to fourth aspects of the present invention, it is possible to provide a recording method having a high linear velocity and excellent recording characteristics.

According to the invention described in claims 5 to 7,
A recording medium having a high linear velocity and excellent recording characteristics can be provided.

According to the eighth and ninth aspects of the present invention, it is possible to provide a recording method which has a high linear velocity and can cope with a wide linear velocity with one recording medium.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conventional recording strategy.

FIG. 2 is a diagram showing a recording strategy of the present invention.

FIG. 3 is a stack diagram illustrating a first example of a medium configuration.

FIG. 4 is a stack diagram showing a second example of the medium configuration.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) G11B 7/24 538 B41M 5/26 X (72) Inventor Eiko Suzuki 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 Inside Ricoh Co., Ltd. (72) Yoshiyuki Kageyama, Inventor 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Hiroko Tashiro 1-3-6, Nakamagome, Ota-ku, Tokyo Co., Ltd. F-term in Ricoh (reference) 2H111 EA04 EA23 EA32 EA33 FA12 FA14 FA23 FB05 FB09 FB12 FB21 FB30 5D029 JA01 JB18 LB11 LC21 MA13 5D090 AA01 CC01 DD01 FF21 HH01 KK04 KK05 5D119 AA23 HA01 BB04

Claims (9)

[Claims] 1. A laser beam applied to a phase change recording medium utilizing a reversible phase change between a crystalline phase and an amorphous phase is controlled by ternary light emission power of recording, erasing, and bottom, and the erasing level is controlled. Mark n to be recorded, which is biased to a constant value
With respect to T (T is a reference clock, n is an integer), when the on-pulse time as the recording power irradiation time and the off-pulse time as the bottom power irradiation time are OP and FP, respectively,
When OP and FP are respectively set as a set of pulses,
An optical recording method, wherein the number N of pulses in a pulse train is 0 <N <n, N ≧ 2. 2. Individual pulses OPi, FPi of a pulse train
2. The optical recording method according to claim 1, wherein the time (i = 1, 2,..., N) is variable. 3. The i-th pulse OPi, FP of the pulse train
In i, 0.5T <OPi + FPi <nT (i =
3. The optical recording method according to claim 1, wherein the optical recording method is 1, 2,..., N). 4. The optical recording method according to claim 1, wherein the pulse start time at the head is delayed by 0 to T. 5. A medium configuration recorded by the method according to claim 1, wherein a lower protective layer, a recording layer, an upper protective layer, an upper second protective layer, and a reflective layer are laminated in this order on a transparent substrate. An optical recording medium, wherein the layer is Ag. 6. An optical recording comprising a medium structure recorded by the method according to claim 1 laminated on a transparent substrate in the order of a lower protective layer, a recording layer, an upper protective layer, and a reflective layer. Medium. 7. The recording layer according to claim 5 or 6, wherein the constituent elements and the constituent ratio are Geα Gaβ Inγ Sbδ Teε, and the atomic ratio (at%) of each element is 0 <α <10, 0 <. β <10,
An optical recording medium, wherein 0 ≦ γ <10, 55 <δ <85, and 10 <ε <30. 8. When the recording layer in a crystalline state is irradiated with a constant biased erasing power, and when the recording linear velocity is equal to or higher than the linear velocity at which the recording layer changes to an amorphous phase, the recording power depends on the recording power. 5. The optical recording method according to claim 1, wherein recording is performed with a constant erasing power capable of sufficiently crystallization. 9. A method in which a recording medium in a crystalline state is irradiated with a constant biased erasing power and the recording linear velocity is changed to a linear velocity lower than a linear velocity at which the recording layer changes to an amorphous phase. 5. The optical recording method according to claim 1, wherein recording is performed with a fixed power ratio.