JP2002203317A - Optical recording method, optical recorder and optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the jitter of a reproduced signal when the recording is made by plural linear speeds in a phase change type optical recording medium recordable with high density, especially in a write-once phase type medium. SOLUTION: In this method for recording by the plural linear speeds or continuously changing linear speed, the recording waveform for modulating a recording light includes a DC part and a recording pulse part, and when the intensity of the DC part is expressed as Pbi, the width of an upward pulse is expressed a Tmp, the intensity thereof is expressed as Pw, and the Pw, Pbi, Tmp at the time of recording by the linear speed VL are respectively expressed as PwL, PbiL, TmpL, and also when the Pw, Pbi and Tmp at the time of recording by the linear speed VH which is faster than VL and satisfies 1.1<=VH/VL, are respectively expressed as PwH, PbiH, TmpH, the recording is carried out under the condition satisfying the equations, 1<PbiH/PbiL, (PbiH/ PwH)/(PbiL/PwL)<1, and 1<=TmpH/TmpL.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical recording medium such as a phase change optical recording medium, a method for recording on the medium, and an apparatus for recording on the medium.

[0002]

2. Description of the Related Art In recent years, an optical recording medium capable of high-density recording and capable of erasing and rewriting recorded information has attracted attention. Among the rewritable optical recording media, phase change type optical recording media perform recording by changing the crystal state of the recording layer by irradiating a laser beam, and reflectivity of the recording layer accompanying such a state change. Reproduction is performed by detecting a change. Phase-change optical recording media can be overwritten by modulating the intensity of a single laser beam, and the optical system of the drive is simpler than that of magneto-optical recording media. ing.

In a phase-change type medium that can be rewritten by overwriting, a crystalline recording layer is irradiated with a laser beam having a recording power level to be melted, and is rapidly cooled from a molten state to form an amorphous recording mark. At the time of erasing, an amorphous recording mark is crystallized by irradiating a laser beam of an erasing power level to raise the temperature to a temperature higher than the crystallization temperature of the recording layer and lower than the melting point, and then slowly cooling.

[0004] Some optical recording media are write-once media that can be recorded only once and cannot be rewritten.

[0005] A write-once medium is not suitable for recording public documents or the like in which information is falsified, since recording information cannot be rewritten. As write-once media, CD-R and DVD-
Materials using an organic dye as a recording material, such as R, are widely used. However, when an organic dye is used as a recording material, recording sensitivity tends to be insufficient when high-speed recording is performed by increasing the linear velocity of a medium, and it is difficult to achieve a high transfer rate. Further, since organic dyes have relatively steep spectral absorption characteristics and spectral reflection characteristics, it is necessary to use organic dyes corresponding to recording / reproducing wavelengths. Therefore, for example, when there is an upper format that uses recording / reproducing light of a shorter wavelength, there is a problem that recording / reproducing light for the upper format cannot perform recording / reproducing on a medium of a lower format. There is also a problem that it is difficult to design and obtain an organic dye corresponding to short-wavelength recording / reproducing light.

[0006]

Among the overwritable phase change media, those which have been put to practical use include, for example, CD-RW, DVD-RW and DVD-RAM. The CD-RW has a recording capacity of 640 MB, which is equivalent to a CD-DA (compact disk). With a CD-RW, recording in a linear velocity range of 4 to 10 times that of a CD-DA has been put to practical use. On the other hand, 4.7GB same as DVD-ROM
DVD-RWs and DVD-RAMs having a recording capacity of 1 × (original linear velocity)
Recording at linear velocities more than doubled has not been put to practical use. This is because the recording density of DVD-RW and DVD-RAM is
This is because it is technically difficult to overwrite so that the jitter can be reduced in a wide linear velocity range because it is significantly higher than the RW.

In a write-once medium using an organic dye, the organic dye is decomposed during recording. Therefore, in general, it is said that the linear velocity during recording to double the power of the recording laser beam is required to be 2 ^1/2 times. On the other hand, when a phase-change medium is used as a write-once medium, the portion irradiated with the recording laser beam may reach the melting point. Since the recording layer instantaneously absorbs the laser beam and reaches the melting point, the power of the recording laser beam does not largely depend on the linear velocity during recording. Therefore, even if the linear velocity during recording is doubled,
There is an advantage that the power of the recording laser beam can be slightly increased.

However, according to the study of the present inventors, it has been found that it is difficult to reduce the jitter in a wide linear velocity range even when a phase change type medium is used as a write-once medium.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the jitter of a reproduction signal when recording at a plurality of linear velocities in a phase-change optical recording medium capable of high-density recording, particularly a write-once phase-change medium. .

[0010]

This and other objects are achieved by the present invention which is defined below as (1) to (22). (1) A method of performing recording on an optical recording medium having a recording layer containing a phase change material at a plurality of linear velocities or a linear velocity that continuously changes using recording light intensity-modulated by a recording waveform. The recording waveform has a DC portion and a recording pulse portion for forming a recording mark,
The intensity of the DC portion is represented by Pbi, and in the recording pulse portion having at least three upward pulses, the width of the upward pulse sandwiched between the first upward pulse and the last upward pulse is represented by Tmp, and the intensity thereof is represented by Pw. wherein the plurality of linear velocities, or one of the continuously changing linear velocity as V _L, and Pw for performing recording at a linear velocity V _L, Pbi and Tmp, respectively PwL, and PbiL and TMPL, the plurality of lines speed or faster than V _L of the continuously changing linear velocity, and one of the linear velocity which satisfies 1.1 ≦ V _H / V _L and V _H, performs recording at a linear velocity V _H Pw, Pbi and Tmp at the time are PwH, Pbi, respectively.
An optical recording method for performing recording under a condition satisfying 1 <PbiH / PbiL, (PbiH / PwH) / (PbiL / PwL) <1, where 1 ≦ TmpH / TmpL, where H and TmpH. (2) A method of performing recording at one linear velocity selected from a plurality of linear velocities on an optical recording medium having a recording layer containing a phase change material, using recording light intensity-modulated by a recording waveform. The recording waveform has a direct current portion and a recording pulse portion for forming a recording mark, the intensity of the direct current portion is represented by Pbi, and the upward pulse is at least three times.
In the recording pulse portion having one, the width of the upward pulse sandwiched between the first upward pulse and the last upward pulse is represented by Tmp, its intensity is represented by Pw, and one of the plurality of linear velocities is represented by _VL , Pw, Pbi, and Tmp when recording at the speed _VL are PwL, PbiL, and TmpL, respectively, which are higher than _VL among the plurality of linear velocities and satisfy 1.1 ≦ _VH / _VL . one of the linear velocity and V _H, Pw for performing recording at a linear velocity V _H, Pbi and Tmp, respectively PwH, Pbi
An optical recording method for performing recording under a condition satisfying 1 <PbiH / PbiL, (PbiH / PwH) / (PbiL / PwL) <1, where 1 ≦ TmpH / TmpL, where H and TmpH. (3) In the recording pulse portion having at least three upward pulses, the width of the leading upward pulse is T
Expressed as top, Ttop for recording at linear velocity _VL is TtopL
And then, when the Ttop when performing recording at a linear velocity V _H and TtopH, 1 <the performing recording as TtopH / TtopL (1) or an optical recording method of (2). (4) In the recording pulse portion having at least three upward pulses, the width of the last upward pulse is represented by Tlp, and Tlp at the time of recording at the linear velocity _VL is represented by TlpL.
And then, when the Tlp for performing recording at a linear velocity V _H and TlpH, 1 <the performing recording as TlpH / TlpL (1) one of the optical recording method to (3). (5) pulse intensity and the pulse width used in each of the line velocity V _L and the linear velocity V _H is one of the optical recording method of the above is determined by the test writing to the optical recording medium (1) to (4) . (6) The above (1) to (1) to which are applied to a write-once optical recording medium
The optical recording method according to any one of (5). (7) Applied to a rewritable optical recording medium, the wavelength of the laser beam used for recording is λ, the numerical aperture of the objective lens of the irradiation optical system is NA, the detection window width is Tw, and the signal length corresponding to the shortest recording mark Is the optical recording method according to any one of the above (1) to (5), wherein n.Tw> 20 ns at the fastest linear velocity used for recording. (8) A method for performing recording on an optical recording medium having a recording layer containing a phase-change material by using recording light intensity-modulated by a recording waveform, wherein the recording waveform includes a DC portion and a recording mark. And a recording pulse portion for forming, wherein the intensity of the direct current portion is represented by Pbi, and the recording pulse portion having at least three upward pulses is sandwiched between the first upward pulse and the last upward pulse. The width of the upward pulse is represented by Tmp, and the intensity thereof is represented by Pw. A reference linear velocity and recommended values of Pw, Pbi and Tmp at this linear velocity are given, and the linear velocity is different from the reference linear velocity. By performing the test writing, the Pw, Pbi, and Tmp actually used when actually recording information in the linear speed at the time of the test writing or in the linear speed range including the linear speed are determined. , And one linear velocity serving as the reference linear velocity V _H which satisfies the linear velocity V _L and 1.1 ≦ V _H / V _L, and the other a linear velocity at the time of the test writing, the linear velocity V _L
Pw, Pbi, and Tmp for recording at Pw
L, and PbiL and TMPL, PwH Pw for performing recording at a linear velocity V _H, Pbi and Tmp, respectively, when the pBIH and TmpH, 1 <PbiH / PbiL, (PbiH / PwH) / (PbiL / PwL) <1, 1 ≦ TmpH / TmpL, so that Pw, Pbi and T
Optical recording method to set mp. (9) In the recording pulse portion having at least three upward pulses, the width of the leading upward pulse is T
When represented by top, Ttop at the reference linear velocity
Tt in performing the recommended value is given a, a Ttop when performing recording at a linear velocity V _L and TtopL, a recording at a linear velocity V _H
By setting Ttop at the time of test writing so as to satisfy 1 <TtopH / TtopL when op is TtopH, the information is actually obtained at the linear speed at the time of this test writing or at the linear speed range including this linear speed. (8) The optical recording method according to the above (8), wherein Ttop used for recording is obtained. (10) In the recording pulse portion having at least three upward pulses, the width of the last upward pulse is represented by Tlp, and the recommended value of Tlp at the reference linear velocity is given. Tl when recording with _L
Let p be TlpL, and Tlp when recording at the linear velocity V _H be Tlp
By setting TlpH at the time of test writing so as to satisfy 1 <TlpH / TlpL when H is set, information is actually recorded in the linear speed at the time of this test writing or in the linear speed range including this linear speed. The optical recording method according to the above (8) or (9), wherein Tlp to be used in the recording is obtained. (11) The above (8) applied to a write-once optical recording medium
The optical recording method according to any one of (1) to (10). (12) Applied to a rewritable optical recording medium, the wavelength of the laser beam used for recording is λ, the numerical aperture of the objective lens of the irradiation optical system is NA, the detection window width is Tw, and the signal length corresponding to the shortest recording mark Is the optical recording method according to any one of the above (8) to (10), wherein n.Tw> 20 ns at the fastest linear velocity used for recording. (13) An optical recording apparatus capable of using any one of the optical recording methods (1) to (7), wherein the linear velocity V
The optical recording device holding the pulse intensity and the pulse width used in each of the _L and the linear velocity V _H. (14) An optical recording apparatus capable of using any one of the optical recording methods (1) to (7), wherein the linear velocity V
_A plurality of pulse intensities and pulse widths to be used for each of the _L and the linear velocity V _H are held for each linear velocity. , An optical recording apparatus using test writing on an optical recording medium. (15) An optical recording apparatus capable of using the optical recording method according to any one of the above (1) to (7), wherein the linear velocity V
An optical recording apparatus in which the pulse intensity and pulse width used in each of the _L and the linear velocity _VH are defined as a function of the respective linear velocity, and hold these functions. (16) An optical recording apparatus which can use the optical recording method according to any one of (1) to (7), wherein the linear velocity V
_The pulse intensity and pulse width to be used for each of the _L and the linear velocity V _H are defined as a function of the respective linear velocity, and a plurality of these functions are held for each linear velocity. An optical recording device that uses test writing on an optical recording medium when selecting a function. (17) An optical recording apparatus capable of using the optical recording method according to any one of (8) to (12), wherein a recommended value of pulse intensity and pulse width at the reference linear velocity is held. Optical recording device. (18) In (1) to (7) be any optical recording method applicable optical recording medium, pulse intensity and pulse width used in each of the linear velocity V _L and the linear velocity V _H is recorded Optical recording media. (19) In (1) to (7) be any optical recording method applicable optical recording medium, pulse intensity and pulse width used in each of the linear velocity V _L and the linear velocity V _H is, An optical recording medium in which a plurality of recordings are recorded for each linear velocity, and test writing on the optical recording medium is used when selecting an actually used pulse intensity and pulse width from the plurality of pulse intensities and pulse widths. (20) In (1) to (7) be any optical recording method applicable optical recording medium, pulse intensity and pulse width used in each of the linear velocity V _L and the linear velocity V _H is, An optical recording medium that is defined as a function of each linear velocity and on which this function is recorded. (21) In (1) to (7) be any optical recording method applicable optical recording medium, pulse intensity and pulse width used in each of the linear velocity V _L and the linear velocity V _H is, Defined as a function of each linear velocity,
An optical recording medium in which a plurality of these functions are recorded for each linear velocity, and a test writing to an optical recording medium is used when selecting a function to be actually used from the plurality of functions. (22) An optical recording medium to which any one of the optical recording methods (8) to (12) can be applied, wherein the recommended values of pulse intensity and pulse width at the reference linear velocity are recorded. recoding media.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In general, when recording on a phase-change optical recording medium, recording light is not applied in a DC manner corresponding to the length of a recording mark.
As described in Japanese Patent Application Laid-Open No. 008, JP-A-11-232652, and JP-A-2000-155945, multi-pulse recording is generally performed.

FIG. 1 shows an example of a recording waveform in multi-pulse recording. In this specification, the recording waveform means a drive signal pattern for intensity-modulating the recording light. FIG. 1 shows a 5T signal of the NRZI signal and the 5T signal.
2 shows a recording waveform corresponding to the T signal.

In FIG. 1, Pw is recording power, Pbi is bias power, and Pbo is bottom power. Pbi is
In a recording system capable of overwriting, it is usually called erasing power. This recording waveform has a recording pulse portion for forming a recording mark and a DC portion for erasing the recording mark. The recording pulse portion has a structure in which a combination of an upward pulse (intensity Pw) and a subsequent downward pulse (intensity Pbo) is repeated.
And returns to Pbi. That is, the adjacent recording pulse portions are connected by the DC portion.

In FIG. 1, Ttop is the width of the leading upward pulse, Tmp is the width of the upward pulse (also called multipulse) sandwiched between the leading upward pulse and the trailing upward pulse, and Tlp is the width of the leading pulse. The width of the last upward pulse, and Tcl is the width of a downward pulse (also called a cooling pulse) added after the last upward pulse. These pulse widths are represented by values standardized by the reference clock width (1T). In the illustrated recording waveform, the power (bottom power Pbo) of all downward pulses including the cooling pulse is set lower than the bias power Pbi.

FIG. 2 shows a recording waveform of the 4T signal. The recording pulse portion in this recording waveform is composed of two upward pulses and a downward pulse following each upward pulse. In this recording pulse portion, the width of the top upward pulse is represented by Ttop, and the width of the second upward pulse from the top is represented by Tlp.

FIG. 3 shows EFM Plus (8-16)
5 shows a recording waveform of a 3T signal which is the shortest signal in the modulation. The recording pulse portion in this recording waveform is composed of only one upward pulse and one downward pulse.
In this recording pulse portion, the width of the upward pulse is Ttop
It is represented by

The pulse width in the present specification is a normalized pulse width standardized by a reference clock width. If the modulation method is not changed even if the linear velocity is changed, the reference clock width is changed in inverse proportion to the linear velocity. Therefore, if the recording mark has the same signal, the mark length on the medium does not depend on the linear velocity. It will be constant. That is, the linear recording density (bit density) becomes constant. For example, when the linear velocity is １ ／, the reference clock width is doubled.

In the present invention, recording is performed on a phase-change medium at a plurality of linear velocities or a linear velocity that changes continuously. Then, in order to reduce the jitter in all of the plurality of linear velocities or the linear velocity range in which the linear velocity changes continuously, the pulse intensity (power level) and the pulse intensity (power level) of the recording waveform are changed according to the linear velocity during recording. Control the pulse width. Specifically, it is as follows.

First, the plurality of linear velocities or the continuous
One of the linear velocities that changes to _LAnd the plurality
Linear velocity or V of the continuously changing linear velocity_LYo
And 1.1 ≦ V_H/ V_L Is one of the linear velocities satisfying_HAnd Also, the recording pal
To have at least three upward pulses
Where the linear velocity V_LPw, Pbi and
Tmp is PwL, PbiL and TmpL, respectively, and the linear velocity
Degree V_HPw, Pbi and Tmp when recording with
PwH, PbiH and TmpH. At this time,
In other words, recording is performed under the condition that 1 <PbiH / PbiL, (PbiH / PwH) / (PbiL / PwL) <1, and 1 ≦ TmpH / TmpL. Thereby, V_LAgainst
V_HIf the ratio of
Even when recording, the jitter can be reduced. Rewritable
When the linear velocity is increased when using as a medium,
More energy needed for crystallization
Therefore, Pbi increases as the linear velocity increases. On the other hand, write-once
When the linear velocity is increased when using as a medium,
To assist the rise of the heating of the recording layer, P
Increase bi. And rewritable and write-once
Even in the case of deviation, Pbi / Pw decreases as the linear velocity increases.
Otherwise, the jitter will increase.

The above (PbiH / PwH) / (PbiL / PwL) <1 is synonymous with PbiL / PwL> PbiH / PwH, and is therefore synonymous with PwH / PwL> PbiH / PbiL. That is, in the present invention, as the linear velocity increases, Pbi increases and Pw also increases,
In addition, the rate of increase of Pw is set higher than the rate of increase of Pbi. This makes it easy to keep the jitter within an allowable range over a wide linear velocity range.

The jitter reduction by controlling Pbi / Pw is particularly effective for a write-once medium. In a conventional write-once system using a medium using an organic dye as a recording material,
It is common to perform multi-pulse recording. But,
In a conventional write-once system, it has not been proposed to provide a DC section between adjacent recording pulse sections and control the power level according to the linear velocity.

When recording at the linear velocity V _L , T top is T
and TOPL, Tt the Ttop when performing recording by the linear velocity V _H
When opH is set, in the present invention, recording is preferably performed as 1 ≦ TtopH / TtopL, and more preferably 1 <TtopH / TtopL. This makes it possible to further suppress an increase in jitter due to a change in linear velocity.

Further, when recording at the linear velocity _VL , Tl
The p and Tlpl, when the Tlp when performing recording by the linear velocity V _H and TlpH, in the present invention, preferably as a 1 ≦ TlpH / TlpL, more preferably perform the recording as 1 <TlpH / TlpL. This makes it possible to further suppress an increase in jitter due to a change in linear velocity.

[0024] The V _L and pulse intensity and the pulse width used in each of the V _H is, pBIH / Pbi
L, (PbiH / PwH) / (PbiL / PwL), TmpH
/ TmpL, TtopH / TtopL, and TlpH / TlpL are determined so as to fall within the limits defined in the present invention. The pulse intensity and pulse width at each linear velocity determined in this way may be held by the optical recording device or may be recorded on the medium. That is, these values may be tabulated and stored in a storage unit in the optical recording device, or may be recorded in advance on a medium. Also,
Instead of tabulating, for example, the pulse intensity and pulse width used at each linear velocity may be defined as a function of the linear velocity, and this function may be stored in the storage means or recorded on a medium. .

The present invention relates to a CLV (Constant Linear Velo
This is particularly effective when it is necessary to support a plurality of recording linear velocities in the (city) format, and the difference between the plurality of linear velocities is large. The multiple linear velocities in this case are
Usually, the original linear velocity (for example, in DVD-RW, 3.
The linear velocity is 49 m / s) and an integral multiple thereof, but does not necessarily have to be an integral multiple. Further, it is not necessary for the plurality of linear velocities to include the original linear velocity. For example, the present invention may be applied to a high-speed recording system corresponding to only a linear velocity of at least twice or at least four times the original linear velocity. .

It should be noted that the present invention is characterized in that in a recording system which is in the CLV format and supports a plurality of linear velocities, the relationship between recording conditions at each linear velocity is determined. Therefore, the present invention encompasses performing recording on one medium belonging to such a recording system using only one linear velocity selected from the plurality of linear velocities.

The present invention also relates to CAV (Constant Angul
ar Velocity) format. In the CAV format, recording is performed on a disk-shaped medium at a constant rotation speed, so that recording is performed at a continuously changing linear velocity, and the linear velocity is higher at the outer peripheral part than at the inner peripheral part of the medium. In this specification, the CLV format includes an MCLV (Modified CLV) format, and the CAV format is an MLV format.
It shall include the CAV (Modified CAV) format. The MCLV format and the MCAV format are described, for example, in 223rd of “Optical Disc Technology” published by Radio Engineering Co. on February 10, 1989.
It is listed on the page.

In the present invention, there is no need to continuously control the pulse intensity and pulse width even if the linear velocity increases or decreases continuously. For example, when recording in the CAV format, the linear velocity changes continuously. However, it is not necessary to continuously change the pulse intensity and the pulse width, and several combinations of the pulse intensity and the pulse width are used. Degree. In other words, the area between the lowest linear velocity and the highest linear velocity in the CAV format may be divided into a plurality of linear velocity areas, and one combination of pulse intensity and pulse width may be set in each of the divided linear velocity areas.

A disk-shaped medium having a diameter of about 12 cm
When used in the system, the ratio between the linear velocity at the innermost circumference and the linear velocity at the outermost circumference is generally in the range of 2-3, and is usually about 2.5. In this case, the number of the set combinations is preferably two or more, more preferably three or more. If the number of combinations used is too small, the effect of the present invention will be insufficient. On the other hand, even if the number of combinations to be used is increased, the effect of reducing jitter does not significantly increase, so that the number of combinations does not need to exceed 40. However, the pulse intensity and the pulse width may be continuously changed according to the linear velocity change.

On the other hand, when recording in the CLV format, the linear velocity is usually changed to an integer multiple such as 2 ×, 4 ×, 6 ×, or 8 ×, and V _H / V _L becomes relatively large. It is preferred to vary the pulse intensity and pulse width at speed.

The V _H is a linear velocity selected so that preferably 1.1 ≦ V _H / V _L , more preferably 1.2 ≦ V _H / V _L. When _VH / _VL is small, it is not necessary to set the pulse intensity and the pulse width to different values at both linear velocities. On the other hand, if V _H / V _L is too large, it is difficult to obtain a sufficient effect even if the present invention is applied. Therefore, V _H / V _L ≦ 8 is preferable, and V _H / V _L ≦ 4 is more preferable. And

According to the present invention, there is provided a recording method for determining a pulse intensity and a pulse width used for actual recording by performing test writing at a specific linear velocity before actually recording at a specific linear velocity in the CLV format. Applicable. Before actually recording in CAV format,
By performing test writing at at least one linear speed,
The present invention can be applied to a recording method for determining a pulse intensity and a pulse width used for actual recording.

At the time of trial writing, at least one parameter is selected from parameters relating to pulse intensity and parameters relating to pulse width, the values thereof are changed, and trial writing is performed on the medium. Next, the quality of the reproduced signal is determined by reproducing the test-written signal and measuring errors and / or jitter. And if the quality is poor, change the parameter again and / or
Alternatively, another parameter is changed, and test writing is performed again. By repeating this procedure, the optimum value of the recording condition actually used is obtained. In a disk-shaped medium, since recording is usually performed from the inner peripheral side, test writing is performed at least in the inner peripheral part, and preferably performed in the inner peripheral part and the outer peripheral part. In particular, in the CAV format, since the linear velocities are considerably different between the inner peripheral portion and the outer peripheral portion, it is preferable to perform test writing on both the inner peripheral portion and the outer peripheral portion. Note that the test writing is usually performed in a test writing area provided separately from the data recording area.

Hereinafter, the case where the present invention is applied to a recording method for determining the optimum recording conditions by trial writing will be described.

In the first method using test writing, a plurality of pulse intensities and pulse widths to be used for each of the linear velocities _VL and _VH are provided for each linear velocity. Then, when recording at a specific linear velocity, from the combination of a plurality of pulse intensities and pulse widths prepared for recording at that linear velocity, to select the pulse intensity and pulse width actually used, Trial writing is used. In the first method, the pulse intensity and pulse width used at each linear velocity are defined as a function of the linear velocity, and a plurality of functions may be prepared for each linear velocity. In this case, the function actually used at each linear velocity is determined by trial writing. The combination or function of a plurality of pulse intensities and pulse widths prepared for each of the linear velocities may be held by the optical recording device or may be recorded on a medium.

Next, a second method using test writing will be described.
Will be described. In the second method, a reference linear velocity is given.
Pulse intensity and power at that linear velocity
The recommended value of the loose width must be given. First,
The reference linear velocity is V_LAnd the linear velocity used for test writing
To V_HAnd Linear velocity V_HDoes not work in the CLV format.
This is the linear velocity used for recording. On the other hand, CAV former
As described above, the minimum linear velocity and the maximum linear velocity
Is divided into multiple linear velocity ranges, and
Test linear velocity V_HAnd Trial writing line speed V_H
Is V _LAnd V_H1.1 ≦ V_H/ V_L Is satisfied. Linear velocity V_LPw and Pbi in
And Tmp are recommended for PwL, PbiL and
TmpL, linear velocity V_HPw when performing trial writing with
Pbi and Tmp are respectively PwH, PbiH and Tmp
When H is set, PwH, PbiH and TmpH are set so as to satisfy 1 <PbiH / PbiL, (PbiH / PwH) / (PbiL / PwL) <1, and 1 ≦ TmpH / TmpL.
You can do trial writing. Thereby, the reference linear velocity V_L
Faster linear velocity V_HOptimal recording conditions at and near
Can be reached in a short procedure.

It should be noted that Ttop and Tlp can be similarly considered. That is, the reference linear velocity V
_L TtopL and is given as the recommended value of Ttop at, when the Ttop when performing test writing at a linear velocity V _H and TtopH, 1 <a test writing by setting TtopH to satisfy TtopH / TtopL By doing so, it becomes possible to obtain the optimum value of the linear velocity _VH and the Ttop in the vicinity thereof in a short procedure. Further, a TlpL is given as the recommended value of Tlp at the linear velocity V _L as the reference, Tlp in performing test writing at a linear velocity V _H
Is set to TlpH, by setting TlpH so as to satisfy 1 <TlpH / TlpL, and performing test writing, it is possible to obtain the linear velocity _VH and the optimum value of Tlp in the vicinity thereof in a short procedure. .

Further, the present invention can be similarly applied to test writing when recording at a linear velocity lower than the reference linear velocity. In this case, first, the reference linear velocity is set to _VH, and the linear velocity used for test writing is set to _VL . The test writing linear velocity V _L preferably satisfies 1.1 ≦ V _H / V _L , similarly to the relationship between V _L and V _H described above. Also, P at linear velocity V _H
The recommended values of w, Pbi and Tmp are respectively PwH, Pbi
H and TmpH, and Pw, Pbi, and TmpL when performing test writing at the linear velocity _VL are PwL, PbiL, and TmpL, respectively: 1 <PbiH / PbiL, (PbiH / PwH) / (PbiL / PwL) < It is only necessary to set PwL, PbiL and TmpL so as to satisfy 1, 1 ≦ TmpH / TmpL and perform test writing. As a result, the reference linear velocity V _H
It is possible to reach the optimum recording condition at the lower linear velocity V _L and its vicinity in a short procedure. Also, T
Top and Tlp can be considered in the same manner as described above.

The reference linear velocity and the recommended values of the pulse intensity and pulse width at that linear velocity may be any values as long as the optical recording apparatus can read out the data at the time of trial writing.
For example, the information may be held by an optical recording device or may be recorded on a medium. In this specification, the recommended values of the pulse intensity and the pulse width mean a value recommended by a medium maker, or an optimum value or a recommended value defined in the standard of the recording system.

The reference linear velocity used in the above method is
The original linear velocity in the recording system to which the present invention is applied does not need to be, and may be any value. For example, when the original linear velocity is 3.5 m / s, the reference linear velocity may be double velocity 7 m / s. When this recording method is applied, there is no need to use a plurality of recording linear velocities, and recording may be performed only at a linear velocity that is, for example, four times the reference linear velocity.

The linear velocity range in which the present invention is particularly effective is:
_VH / _VL is within the above range, and the minimum value of the plurality of linear velocities or the continuously changing linear velocity is preferably 2 m / s or more, more preferably 2.5 m / s or more, More preferably, the region is at least 3 m / s.

When V _H / V _L is within the above range, 1 <PbiH / PbiL ≦ 3, 0.5 ≦ (PbiH / PwH) / (PbiL / PwL) <
1, 1 ≦ TmpH / TmpL ≦ 3 1 ≦ TtopH / TtopL ≦ 3, preferably 1 ≦ TlpH / TlpL ≦ 3, 1.01 ≦ PbiH / PbiL ≦ 3, 0.5 ≦ (PbiH / PwH) / (PbiL / PwL) ≦
0.99, 1.01 ≦ TmpH / TmpL ≦ 2 1.01 ≦ TtopH / TtopL ≦ 2.5, 1.01 ≦ TlpH / TlpL ≦ 3 PbiH / PbiL is too large, (PbiH / PwH) / (PbiL / PwL) is too small, TmpH / TmpL is too large, TtopH /
If TtopL is too large or TlpH / TlpL is too large, it becomes difficult to reduce the jitter in the linear velocity range where _VH / _VL is in the above range.

In the present invention, as shown in FIG. 2, even in a recording waveform in which two upward pulses exist in the recording pulse portion, as shown in FIG. 3, only one upward pulse exists in the recording pulse portion. Recording waveforms, PbiH /
PbiL, (PbiH / PwH) / (PbiL / PwL) and TtopH / TtopL are preferably within the above-mentioned limited range. In the recording waveform as shown in FIG. 2, TlpH / T
Preferably, lpL is also within the above-mentioned limited range.

The first upward pulse has a bias power Pbi
Therefore, if the width Ttop of the leading upward pulse is the same as the width Tmp of the other upward pulses, the temperature rise of the recording layer becomes insufficient, and it may be difficult to obtain a recording mark of a predetermined length. . Therefore, it is preferable that Ttop / Tmp> 1. However, if Ttop / Tmp is too large, the effect of multi-pulse recording is impaired. Therefore, preferably, Ttop / Tmp ≦ 3. Further, the length of the recording mark can be adjusted by controlling the width Tlp of the last upward pulse.
However, if Tlp / Tmp is too small or too large, the effect of multi-pulse recording is impaired. Therefore, it is usually preferable to set Tlp such that 0.5 ≦ Tlp / Tmp ≦ 2.

In the present invention, when the intensity of the downward pulse following the upward pulse in the recording pulse portion is represented by Pbo, it is preferable to perform recording under the condition of Pbo ≦ Pbi. This is because the effect provided by the downward pulse is not impaired. However, the power level of the downward pulse needs to be larger than 0 in order to apply the tracking servo. P
If bo = Pbi, the load on the control means of the optical recording apparatus can be reduced. When Pbo is the same for all downward pulses and Pbo = Pbi, there is no cooling pulse. However, the cooling pulse may be controlled independently of other downward pulses.

Note that the intensity of the first upward pulse and the intensity of the last upward pulse may be different from the intensity (Pw) of the upward pulse sandwiched between them. When the intensity of the first upward pulse is represented by Ptop and the intensity of the last upward pulse is represented by Plp, Ptop is made larger than Pw or Tlp is made Tm instead of making Ttop larger than Tmp.
Instead of making it larger or smaller than p, Plp may be made larger or smaller than Pw. Also, Ttop and Pt
op may be controlled together, or Tlp and Plp may be controlled together. However, in order to reduce the load on the control means of the optical recording apparatus, Ptop = Pw and Pl
It is preferable that p = Pw.

When the present invention is applied to a rewritable system, the bias power Pbi is the erasing power.
May be determined according to the composition of the recording layer, the overwrite linear velocity, and the like so that the recording mark can be crystallized. On the other hand, the upper limit of Pbi may be determined so that the recording layer does not become amorphous and that the recording layer is not damaged by repeated irradiation.

When the present invention is applied to a write-once system,
The bias power Pbi is preferably 3 to 3 of the recording power Pw.
It is preferably 60% and 1 mW or more. If Pbi is too low, the effect of assisting the rising of the heating of the recording layer will be insufficient, and the jitter will increase. On the other hand, if the bias power Pbi is too high, the region irradiated with the laser beam at the bias power level may become amorphous or microcrystalline, which is not preferable.

In the present invention, Ttop and Tlp do not need to be the same for all the recording marks having the same signal length. For example, Ttop and Tlp are different for each recording mark according to the length of the immediately preceding recording mark. May be appropriately controlled, or Tlp may be appropriately controlled for each recording mark in accordance with the length of the recording mark immediately thereafter.

Incidentally, the above-mentioned Japanese Patent Application Laid-Open No. 10-1060
No. 08, JP-A-11-232652 and JP-A-2000-155945 describe that in multi-pulse recording, the pulse width and the pulse height are controlled according to the linear velocity. However, JP
-106008 and JP-A-11-232652.
The publication does not describe controlling Pbi and the ratio between Pbi and Pw in accordance with the linear velocity. In addition, JP-A-2
000-155945 describes that PbiL / PwL <PbiH / PwH, contrary to the present invention.

The invention described in Japanese Patent Application Laid-Open No. 2000-155945 was made in consideration of application to a CD-RW having a recording track pitch wider than that of a DVD.
In this publication, an experiment is performed on CD-RW. On the other hand, according to the present invention, the recording track pitch 0.74 μm D
Since the target is a medium having a recording track pitch equal to or smaller than VD-RW, the relationship between PbiL / PwL and PbiH / PwH is completely opposite to that in JP-A-2000-155945. It is considered that Note that the present invention uses a recording track pitch of 0.8
It is particularly effective for media of μm or less. However, for a medium having a recording track pitch that is too narrow, it is difficult to obtain a sufficient effect even if the present invention is applied. Therefore, the present invention is preferably applied to a medium having a recording track pitch of 0.1 μm or more.

Further, the present invention is particularly effective for a write-once type phase change type medium.
It is considered that the result was different from that of the rewritable medium described in Japanese Unexamined Patent Publication (Kokai) Publication. As described above, in the present invention, as the linear velocity increases, Pbi increases and Pw increases.
And the rate of increase of Pw is made higher than the rate of increase of Pbi. When the present invention is applied to a write-once medium, Pbi is used to assist the rising of the heating of the recording layer. A phase-change type write-once medium differs from a rewritable medium in that a recording layer that is difficult to crystallize is used. In this regard, if Pbi is increased according to the linear velocity at an increase rate equal to Pw, jitter is adversely affected. It is considered that a variation in the shape of the applied recording mark occurs.

When the present invention is applied to a rewritable phase-change medium, the wavelength of the laser beam used for recording is λ, the numerical aperture of the objective lens of the irradiation optical system is NA, and the detection window width is T.
w, when the signal length corresponding to the shortest recording mark is n · Tw, it is preferable to perform recording so that n · Tw> 20 ns at the fastest linear velocity used for recording. That is, when recording on a rewritable medium, the signal length corresponding to the shortest recording mark (hereinafter sometimes simply referred to as the shortest signal length) n
The present invention is particularly effective when Tw is equal to or more than a certain value.

The shortest signal length n · Tw is related to the data transfer rate. In order to reduce n · Tw, it is necessary to perform high-density recording by reducing the spot diameter of a laser beam used for recording and reproduction, or to increase the recording linear velocity. When the laser output during recording is kept constant, heat is less likely to accumulate in the recording layer as the recording linear velocity increases. on the other hand,
In order to reduce the beam spot diameter, the laser wavelength is shortened or the numerical aperture of the objective lens of the laser beam irradiation optical system is increased, but in this case, the energy per unit area of the laser beam spot increases,
During recording, heat easily accumulates in the recording layer. Therefore,
Whether heat easily accumulates in the recording layer depends on the beam spot diameter and the recording linear velocity. When heat easily accumulates in the recording layer, during recording, heat conduction in the in-plane direction of the recording layer causes
Self-erasure in which a part of the formed recording mark is recrystallized is likely to occur. When self-erase occurs, jitter increases. According to the experiments of the present inventors, under the condition that the shortest signal length n · Tw exceeds 20 ns,
Since the influence of the recording linear velocity becomes relatively large, the self-erasing hardly occurs. Under the condition that n · Tw is 20 ns or less, the influence of reducing the laser beam spot diameter becomes relatively large. It was found that self-erasing was likely to occur. Therefore, n · Tw is 2
In the case of 0 ns or less, if 1 <PbiH / PbiL according to the present invention, that is, if Pbi is increased as the linear velocity increases, the effect of self-erasing increases, making it difficult to realize the jitter reduction effect of the present invention. Become. Since self-erasing hardly occurs in the write-once type phase change medium, it is not necessary to substantially consider n · Tw.

The shortest signal length n · Tw corresponds to, for example, a 2T signal in 1-7 modulation, in which case n = 2. Also, 8-16 modulation corresponds to a 3T signal, in which case n = 3.

In the recording waveform, the ratio of the width occupied by the upward pulse in the pair of the upward pulse and the succeeding downward pulse, that is, the duty ratio is preferably set to 0.1.
3 to 0.9. If the duty ratio is too small, high power laser light is required, which is not preferable. On the other hand, if the duty ratio is too large, the width, length, and shape of the recording mark tend to be disturbed, and as a result, the jitter tends to increase.

Incidentally, for example, in the above-mentioned JP-A-2000-1559,
As described in Japanese Patent Publication No. 45, a downward pulse (residual heat adjustment pulse) having a lower power level than the erasing power may be provided immediately before the first upward pulse. By providing an upward pulse having a lower intensity than that, a configuration may be adopted in which the temperature rise of the recording layer is assisted.

In the present invention, the width of a recording pulse portion for forming a recording mark having a signal length kT (k is an integer of 1 or more, T is a reference clock width) does not need to be kT. When the laser irradiation time is kT, the recording mark length may be too long due to heat conduction in the recording track length direction. Therefore, the width of the recording pulse portion is generally shorter than the actual signal length. 1 to 3, the number of upward pulses in the recording pulse portion for recording the kT signal is set to k-2, but is not limited thereto, and may be, for example, k-1. Further, in the present invention, the modulation method is not limited.

The present invention is particularly effective when applied to a mark edge recording system.

In the present invention, the following conditions (1) to (4) are given as the conditions that the phase change type medium used as the write-once type should satisfy. In order to use a phase change medium as a write-once medium, it is necessary to satisfy at least one of the following four conditions.

The first condition is that recording is performed on an optical recording medium having a phase change type recording layer so that the CNR of the shortest signal is 45 dB or more, preferably 48 dB or more. After performing an erasing operation by irradiating a laser beam having a power level that does not melt the recording layer from above at the same linear velocity as during recording, the decrease in the carrier of the shortest signal is 20 dB or less, preferably 18 dB or less. I do. If the carrier drop is within this range, it becomes impossible to read the signal recorded again after the erasing operation. Conventionally,
It is known that a phase change type medium can be used as a write-once type. However, conditions to be satisfied for use as a write-once type have not been clarified. It is known that a rewritable phase-change medium can be re-recorded after erasing, that is, rewritable, if the erasing rate is 25 dB or more. Therefore, if the erasure rate is less than 25 dB, it is estimated that rewriting is impossible, that is, the recorded data cannot be falsified. However, according to the study of the present inventors, it has been found that even if the erasing rate is less than 25 dB, the signal re-recorded after the erasing operation can be read if the carrier of the shortest signal is not less than 20 dB.

In the present invention, it is necessary to form an amorphous recording mark on the crystalline recording layer. On the other hand, when the recording mark is formed by a vapor phase growth method such as a sputtering method, the phase change recording layer is usually formed of an amorphous recording mark. Formed as a layer. Therefore, it is necessary to crystallize at least the recording target region of the recording layer before recording. This crystallization is generally called initialization.
However, the recording layer immediately after formation is extremely difficult to crystallize. Therefore, in the present invention, if the design is such that the decrease in the carrier of the shortest signal is extremely small, that is, if the design is such that recrystallization of the recording layer is extremely difficult, it is necessary to perform initialization at an extremely low linear velocity. Properties are significantly reduced. Considering this point, in the first condition,
The decrease in the carrier of the shortest signal due to the erasing operation is preferably 5 dB or more, and when the recording linear velocity is relatively low, the decrease in the carrier is preferably 10 dB or more.

The second condition is that the highest reflection level obtained when a random signal is recorded on an optical recording medium having a phase change type recording layer and a reproducing operation is performed in a recording area of the random signal is defined as Rini. After performing the erasing operation by irradiating the recording area of the random signal with a DC laser beam at the same linear velocity as at the time of the random signal recording, the highest reflection obtained when performing the reproducing operation in the irradiated area. Level is Rtop, lowest reflection level is Rbottom
In this case, (Rtop + Rbottom) / 2Rini <1 should be satisfied, and preferably (Rtop + Rbottom) /2Rini≦0.95 should be satisfied. The reflection level is the amount of light returning to the optical head. Rini is a reflection level of a crystalline region existing between recording marks.

The second condition needs to be satisfied regardless of the power level of the DC laser light. That is, whether the DC laser beam does not melt the recording layer or melts the recording layer, (Rtop + Rbottom) /
2Rini must be in the above range. When the second condition is satisfied when the DC laser beam does not melt the recording layer, it means that crystallization of the recording layer in the solid phase by irradiation of the DC laser beam is impossible. On the other hand, if the second condition is satisfied in the case of melting, it means that the recording layer becomes amorphous when cooled from the molten state. On the other hand, when a rewritable phase-change medium is irradiated with DC laser light while gradually increasing the power level, the recording layer is crystallized in a solid phase or crystallized from a liquid phase, so that (Rtop + Rbottom) / 2Rini ≧ 1
Power level.

The third condition is that a random signal is recorded on an optical recording medium having a phase-change type recording layer, and the random signal is recorded again at the same linear velocity as at the time of recording the random signal so as to overlap the random signal. After that, when the reproducing operation is performed, the signal cannot be reproduced. It is preferable that the random signal be recorded under optimum recording conditions. The optimum recording condition in this case is determined by a standard to which the medium belongs, whether it is a recording condition that minimizes jitter when recording on a recording layer immediately after initialization, or an optimum recording condition recommended by a media manufacturer. This is the optimum recording condition.

The fourth condition is that a random signal is recorded on an optical recording medium having a phase-change type recording layer, and a DC laser beam is applied to the recording area of the random signal at the same linear velocity as when recording the random signal. Irradiation is performed by irradiation, a random signal is recorded again in the irradiated area, and when a reproduction operation is performed, signal reproduction is impossible. Preferably, the random signal is recorded under the above-described optimum recording conditions.

The fourth condition needs to be satisfied regardless of the power of the DC laser light. That is, whether the DC laser beam does not melt the recording layer or melts the recording layer, it is necessary that the random signal recorded after the DC laser beam irradiation cannot be reproduced.
When the fourth condition is satisfied when the DC laser beam does not melt the recording layer, it means that crystallization of the recording layer in the solid phase by irradiation of the DC laser beam is impossible. On the other hand, if the fourth condition is satisfied in the case of melting, it means that the recording layer becomes amorphous when cooled from the molten state. On the other hand, in a rewritable phase-change medium, the recording layer is crystallized in a solid phase or crystallized from a liquid phase by DC laser light irradiation. is there.

[0068] In this specification, signal reproduction is not possible when the clock jitter is preferably more than 13%, more preferably more than 15%.

In the optical recording medium driving device, the driving signal for intensity-modulating the recording / reproducing / erasing laser light includes:
Generally, a high frequency, which is much higher than the recording frequency, for example, a high frequency of about several hundred megahertz is superimposed.
The DC laser light in the present specification includes a laser light driven by a DC signal on which such a high frequency is superimposed.

In order to use the phase change medium as a write-once medium, the crystallization speed of the recording layer and the thermal design of the medium may be controlled according to the recording linear velocity. Specifically, the recording layer has a composition with a low crystallization rate, or a structure in which the recording layer is cooled relatively quickly, that is, a quenching structure, so that recrystallization of the amorphous recording mark becomes difficult. Is preferred. When performing initialization using a bulk eraser that irradiates a large-diameter laser beam, unlike when recording is performed using a small-diameter laser beam, even if the medium has a quenched structure, the cooling rate of the recording layer is not so fast. The required linear velocity does not decrease so much. Therefore, if the medium has a quenching structure, initialization can be performed at a relatively high linear velocity, and recording can be performed at a relatively low linear velocity. In order to form a quenching structure, a metal reflecting layer as a heat dissipation layer is provided on the recording layer with a dielectric layer interposed therebetween, and the dielectric layer is set so that heat of the recording layer is quickly conducted to the reflecting layer. May be reduced, or the thermal conductivity of the dielectric layer and / or the thermal conductivity of the reflective layer may be increased.

Next, an example of the configuration of an optical recording medium to which the present invention is applied will be described.

FIG . 4 shows a structural example of the optical recording medium of the present invention. This optical recording medium has a first dielectric layer 31, a recording layer 4, a second dielectric layer 32, a reflective layer 5, and a protective layer 6 on a translucent substrate 2 in this order. Is incident through the translucent substrate 2.

[0073] light-transmitting substrate 2 light-transmitting substrate 2 has a light-transmitting property with respect to the laser beam for recording or reproduction. The thickness of the translucent substrate 2 is usually
The thickness may be 0.2 to 1.2 mm, preferably 0.4 to 1.2 mm. The translucent substrate 2 may be made of resin, but may be made of glass. A groove (guide groove) 2G usually provided in the optical recording medium is a region existing on the near side as viewed from the laser beam incident side, and a ridge existing between adjacent grooves is a land 2L.

In the present invention, lands and / or grooves can be used as recording tracks.

The first dielectric layer 31 and the second dielectric layer 32 These dielectric layers prevent the recording layer from being oxidized or deteriorated, and block or release heat transmitted from the recording layer during recording in the in-plane direction. Thereby, the support base 20 and the translucent base 2 are protected. Also, by providing these dielectric layers,
The degree of modulation can be improved. Each dielectric layer may have a configuration in which two or more dielectric layers having different compositions are stacked.

As the dielectric used for these dielectric layers, for example, various compounds containing at least one metal component selected from Si, Ge, Zn, Al, rare earth elements and the like are preferable. The compound is preferably an oxide, a nitride or a sulfide, and a mixture containing two or more of these compounds can also be used.

When a rapid cooling structure is desired for the medium, a dielectric layer,
In particular, it is preferable that the second dielectric layer 32 be made of a dielectric having a high thermal conductivity. As a dielectric having high thermal conductivity, for example, a mixture of zinc sulfide and silicon oxide (ZnS-
SiO ₂ ), aluminum nitride, aluminum oxide, silicon nitride, tantalum oxide, and the like are preferable, and an oxide and / or nitride of Al and an oxide and / or nitride of Si are particularly preferable. The ZnS-SiO _2, S
The iO ₂ preferably contains 30 to 60 mol%. S
If the iO ₂ content is too small, the thermal conductivity will be too low. On the other hand, if the content of SiO ₂ is too large, the adhesion to other layers becomes insufficient, so that the layers are likely to peel off during storage for a long period of time.

In the case of a quenching structure, the thermal conductivity of the second dielectric layer is preferably 1 W / mK or more, more preferably 1.5 W / mK.
W / mK or more. Although there is no particular upper limit on the thermal conductivity of the second dielectric layer, a material that can be used as the dielectric layer usually has a thermal conductivity of about 20 W / mK or less. Second in this specification
The thermal conductivity of the dielectric layer is not a measured value in a thin film state,
The value is for bulk materials.

The thicknesses of the first dielectric layer and the second dielectric layer may be appropriately determined so that a protective effect and a modulation degree improving effect can be sufficiently obtained. The thickness is preferably 30 to 300 nm, more preferably 50 to 2 nm.
50 nm, and the thickness of the second dielectric layer 32 is preferably 1
0 to 50 nm. However, in the write-once medium, it is preferable to have a quenching structure so that the amorphous recording mark is hard to be crystallized. For that purpose, the thickness of the second dielectric layer is preferably 30 nm or less, more preferably 25 nm or less. I do.

Each dielectric layer is preferably formed by a sputtering method.

Recording Layer 4 The composition of the recording layer is not particularly limited and may be appropriately selected from various phase change materials, but preferably contains at least Sb and Te. The recording layer composed of only Sb and Te has a low crystallization temperature of about 130 ° C. and has insufficient storage reliability. Therefore, it is preferable to add another element to improve the crystallization temperature. In this case, the additional elements include In, Ag, Au, Bi, Se, Al, P, Ge,
H, Si, C, V, W, Ta, Zn, Ti, Sn, P
At least one selected from b, Pd and rare earth elements (Sc, Y and lanthanoids) is preferred. Of these, the effect of improving storage reliability is particularly high,
At least one selected from the group consisting of rare earth elements, Ag, In and Ge is preferable.

As the composition containing Sb and Te,
The following are preferred. It represents elements excluding Sb and Te, respectively by M, when the atomic ratio of the recording layer constituent elements represented by the formula _{I (Sb x Te 1-x} ) 1-y M y, preferably 0.2 ≦ x ≦ 0. 9, 0 ≦ y ≦ 0.4, more preferably 0.5 ≦ x ≦ 0.85, and 0.01 ≦ y ≦ 0.2. Specifically, x may be appropriately determined depending on whether the medium is used as a rewritable type or a write-once type, and according to the recording linear velocity and the thermal design of the medium.

In the case of the rewritable type, if x representing the content of Sb in the above formula I is too small, the crystallization speed becomes slow, and it becomes difficult to erase the recording mark at a relatively high linear velocity. In addition, since the reflectance in the crystalline region of the recording layer is low, the output of the reproduction signal is low. When x is extremely small, recording becomes difficult. On the other hand, if x is too large, the difference in reflectance between the crystalline state and the amorphous state will be small, and the output of the reproduced signal will be low.

In the case of the write-once type, if x is too small, the crystallization speed becomes too slow, so that it is difficult to initialize the recording layer. In addition, since the reflectance in the crystalline region of the recording layer is low, the reproduction output is low. When x is extremely small, recording becomes difficult. On the other hand, if x is too large, the crystallization speed will be too high, and it will be unsuitable as a recording layer of a write-once medium. On the other hand, if x is too large, the difference in the reflectance between the crystalline state and the amorphous state will be small, and the reproduced output will be low.

The element M is not particularly limited, but it is preferable to select at least one of the above-mentioned elements exhibiting the effect of improving storage reliability. If the value of y representing the content of the element M is too large, the crystallization speed may be too high or the reproduction output may be low.

The thickness of the recording layer is preferably more than 4 nm and 50 nm
Hereinafter, it is more preferably 5 to 30 nm. If the recording layer is too thin, growth of the crystal phase becomes difficult, and crystallization becomes difficult. On the other hand, when the recording layer is too thick, the heat capacity of the recording layer becomes large, so that recording becomes difficult, and the output of a reproduced signal also decreases.

The formation of the recording layer is preferably performed by a sputtering method.

In the present invention, the structure of the recording layer is not particularly limited. For example, the present invention is applicable to a medium having a multilayered recording layer described in JP-A-8-221814 and JP-A-10-226173.

The present invention can be applied to a write-once medium described below. This write-once medium has a recording layer including a phase change layer and a functional layer. The phase change layer contains a phase change material. The functional layer exists in contact with the phase change layer,
At a temperature near the crystallization temperature of the phase change layer, it does not react with the phase change layer, but reacts with the phase change layer at a temperature equal to or higher than the melting point of the phase change layer to generate a reaction product. When recording on this write-once medium, the state immediately after formation, that is, the entire surface of the amorphous phase change layer is crystallized (initialized). Next, by irradiating a single laser beam while modulating the intensity, the phase change layer and the functional layer are reacted to form a reaction product. As a result, a recording mark composed of the reaction product is present in the laminate composed of the crystalline phase change layer and the functional layer.

In this write-once medium, the phase change layer reacts with the functional layer simultaneously with the melting of the phase change layer to form a reaction product. The reflectance of this reaction product does not change even when the temperature is raised to the crystallization temperature of the phase change layer. That is, it is more thermally stable than the amorphous region of the phase change layer. As described above, since the recording mark made of the reaction product is thermally stable, the storage reliability and the reproduction durability of the recording mark are good.
In a normal phase-change medium, during recording, a self-erasing phenomenon occurs in which a part of the formed recording mark is recrystallized due to heat conduction in the in-plane direction of the recording layer, or a recording mark existing in an adjacent track is generated. Cross erase, in which is erased. On the other hand, in the write-once type medium on which a recording mark made of a reaction product is formed, the jitter is extremely small because self-erasing does not substantially occur. Also, since there is virtually no cross-erase,
The recording track pitch can be reduced, and high-density recording can be performed.

In this write-once medium, the composition of the phase change layer is not particularly limited, and may be the same as the recording layer made of the phase change material described above. The thickness of the phase change layer may be the same as the recording layer made of the above phase change material.

Next, the functional layer will be described.

The functional layer reacts with the phase change layer when the temperature of the phase change layer is raised to a temperature equal to or higher than its melting point to generate a reaction product. Therefore, the functional layer constituent material is
What is necessary is just to select suitably according to the constituent material of a phase change layer. For example, in the case of using the above-described phase change material containing Sb and Te as main components, the functional layer constituent material preferably has a melting point of 400 to 1500 ° C., and more preferably 500 to 1200 ° C.
C. is desirable. Examples of such a material include a metal (simple or alloy) containing at least one of Al, Cu, Ag, and Ge. If the melting point of the functional layer constituent material is too low, a reaction is likely to occur in a region where the phase change layer is to be crystallized, that is, in a region where the phase change layer and the functional layer must not be reacted. On the other hand, if the melting point of the functional layer constituent material is too high, the reaction between the phase change layer and the functional layer is less likely to occur. However, even if the melting point is within the above-mentioned preferred range, 15
The group (Vb) and group 16 (VIb) metal elements, particularly the elements contained in the phase change layer and the elements (Sb, Bi and Te) which easily react with the constituent elements of the phase change layer, form a relatively low temperature with the phase change layer. Easy to react. Therefore, when these elements are contained, it is difficult to cause only the crystallization of the phase change layer without causing a reaction in the laser light irradiation region at a low power level. That is, the composition of the phase change layer changes in the region to be crystallized. Therefore, it is preferable that these elements are not used as main components of the functional layer, and it is more preferable that these elements are not included in the functional layer.

As described above, the functional layer preferably has a high reflectance. Specifically, the extinction coefficient at the recording / reproducing wavelength is preferably 1.5 or more, more preferably 2.0 or more. In the present invention, there is no particular upper limit for the extinction coefficient, but the extinction coefficient of the metal constituting the functional layer is usually 10 or less.

The reaction product in the write-once medium is a mixture and / or combination of a material constituting the phase change layer and a material constituting the functional layer. In transmission electron microscopy,
This reaction product is not crystalline, but is observed as an amorphous state, a microcrystalline state, or an amorphous state containing microcrystals. If the reaction product is not crystalline, it is easy to make the light reflectance of the medium in the region where the reaction product is generated lower than the crystallized region of the phase change layer, and the amorphous region of the phase change layer It is easy to make it lower.

The state of the reaction product does not change even when heated to the crystallization temperature of the phase change layer, and the reflectance does not change.
That is, the recording mark made of the reaction product is thermally different from the recording mark formed by amorphization of the crystalline phase change layer and the amorphous phase change layer immediately after the formation. It is stable. The reaction product does not change even when it is further heated to a high temperature, and in many cases eventually melts, but may crystallize in a solid phase at a temperature lower than the melting point. The temperature at which an optical change occurs in the reaction product due to melting or crystallization may be higher than the crystallization temperature (Tcry) of the phase change layer, and is preferably Tcry + 50 ° C. or higher.

When the reaction product is formed by reacting the phase change layer and the functional layer, the phase change layer and the functional layer do not have to react in the entire region in the thickness direction. That is, after the reaction, the phase change layer and / or the functional layer may partially remain in the thickness direction.

In the illustrated example, the order of lamination of the phase change layer and the functional layer is not particularly limited.

The recording layer in the write-once medium may be composed of one phase change layer and one functional layer, or may have a multilayer structure in which at least one is provided in two or more layers. When a total of three or more phase change layers and functional layers are present in the recording layer, the recording layer may have an even layer configuration in which the same number of phase change layers and functional layers are alternately stacked. May be an odd-numbered layer configuration in which both ends in the thickness direction are alternately laminated so as to be the same type of layer. If the number of both layers is too large, the recording layer becomes too thick. Therefore, the number of interfaces between the two layers in the recording layer is preferably 10 or less.

When two or more phase change layers are provided in a case where the recording layer has a multilayer structure, it is possible to thermally block two adjacent phase change layers by a functional layer.
Therefore, for example, when two phase change layers are provided with a functional layer interposed therebetween, one phase change layer existing on the recording light incident side is crystallized by controlling the power of the recording light, and the other phase change layer is formed. Can be kept amorphous.
This area is used as a first recording mark, and both recording layers are crystallized by using a higher power recording light, and then used as a second recording mark. Is generated and used as the third recording mark, quaternary recording can be performed. If the number of phase change layers is increased, further multi-value recording is possible.

Reflective layer 5 The material constituting the reflective layer is not particularly limited, and usually, Al, Au,
It may be composed of a single metal or semimetal such as Ag, Pt, Cu, Ni, Cr, Ti, Si, or an alloy containing at least one of these metals.

When a rapid cooling structure is desired for the medium, it is preferable that the reflective layer be made of a material having high thermal conductivity. Ag or Al is preferable as the material having high thermal conductivity. However, since Ag or Al alone does not provide sufficient corrosion resistance, it is preferable to add an element for improving corrosion resistance.

However, if another element is added, the thermal conductivity decreases. In this case, it is preferable to use Ag having a higher thermal conductivity as a main component element. Examples of the auxiliary component element that is preferably added to Ag include, for example, Mg,
Pd, Ce, Cu, Ge, La, S, Sb, Si, Te
And at least one selected from Zr. It is desirable to use at least one, and preferably two or more of these subcomponent elements. The content of the subcomponent element in the reflective layer is preferably 0.05 for each metal.
To 2.0 atomic%, more preferably 0.2 to 1.0 atomic%
And the total amount of the subcomponents is preferably 0.2 to 5 atomic%, more preferably 0.5 to 3 atomic%. If the content of the subcomponent elements is too small, the effect of containing them becomes insufficient. On the other hand, when the content of the subcomponent element is too large, the thermal conductivity becomes small.

In the case of a quenching structure, the thermal conductivity of the reflective layer is preferably 100 W / mK or more, more preferably 150 W / mK.
W / mK or more. The thermal conductivity can be calculated, for example, from the electric resistance value of the reflective layer obtained by using the four probe method according to the Widemann-Franz law. There is no particular upper limit on the thermal conductivity of the reflective layer. That is, pure silver (thermal conductivity 250 W / mK) having the highest thermal conductivity among materials usable as the reflective layer constituent material can also be used.

The thickness of the reflection layer is usually preferably from 10 to 300 nm. If the thickness is less than the above range, it becomes difficult to obtain a sufficient reflectance. Further, even if the ratio exceeds the above range, the improvement of the reflectance is small, which is disadvantageous in cost. The reflective layer is preferably formed by a vapor phase growth method such as a sputtering method or an evaporation method.

Protective Layer 6 The protective layer 6 is provided for improving scratch resistance and corrosion resistance. This protective layer is preferably composed of various organic substances, and in particular, it is preferably composed of a substance obtained by curing a radiation-curable compound or a composition thereof with an electron beam, radiation such as ultraviolet rays. . The thickness of the protective layer is usually about 0.1 to 100 μm, and may be formed by a usual method such as spin coating, gravure coating, spray coating, and dipping.

FIG . 5 shows a structural example of the optical recording medium of the present invention. This optical recording medium includes a reflective layer 5, a second dielectric layer 32, a recording layer 4, a first layer
It is formed by laminating a dielectric layer 31 and a translucent substrate 2 in this order. Laser light for recording or reproduction enters through the translucent substrate 2. Note that an intermediate layer made of a dielectric material may be provided between the support base 20 and the reflection layer 5.

As the translucent substrate 2 in this configuration example, a resin plate or a glass plate having the same thickness as the translucent substrate 2 in FIG. 4 may be used. However, the high NA of the recording / reproducing optical system
In order to achieve a high recording density by the formation, it is preferable to make the light-transmitting substrate 2 thin. In this case, the thickness of the light-transmitting substrate is preferably selected from the range of 30 to 300 μm. If the light-transmitting substrate is too thin, the optical effect of dust adhering to the surface of the light-transmitting substrate increases. on the other hand,
If the translucent substrate is too thick, it is difficult to achieve a high recording density by increasing the NA.

When the thickness of the light-transmitting substrate 2 is reduced, for example, a light-transmitting sheet made of a light-transmitting resin is attached to the first dielectric layer 31 with various adhesives or adhesives to form a light-transmitting substrate. Alternatively, a light-transmitting resin layer may be formed directly on the first dielectric layer 31 using a coating method to form a light-transmitting substrate.

The support base 20 is provided to maintain the rigidity of the medium. The thickness and the constituent material of the support base 20 may be the same as those of the translucent base 2 in the configuration example shown in FIG. 4, and may be transparent or opaque. As shown in the figure, the groove 2G can be formed by transferring the groove provided in the support base 20 to each layer formed thereon.

In the medium having the structure shown in FIG. 5, the surface roughness of the reflection layer on the laser beam incident side tends to increase due to crystal growth when the reflection layer 5 is formed. As the surface roughness increases, the reproduction noise increases. Therefore, it is preferable to reduce the crystal grain size of the reflective layer or to form the reflective layer as an amorphous layer. To do this, Ag or A
A reflective layer containing l as a main component and containing the above-mentioned additive element is preferable.

Since the thermal conductivity of the reflective layer decreases as the crystal grain size decreases, if the reflective layer is amorphous, it is difficult to obtain a sufficient cooling rate during recording. Therefore, it is preferable to first form the reflective layer as an amorphous layer and then perform a heat treatment to crystallize the layer. Once formed as an amorphous layer and then crystallized, the surface roughness in the amorphous state can be substantially maintained, and the thermal conductivity can be improved by crystallization.

The other layers are the same as in the configuration example shown in FIG.

[0114]

Example 1 An optical recording disk sample having the structure shown in FIG. 4 was manufactured by the following procedure.

A groove (width 0.2 μm, depth 20 nm, arrangement pitch 0.74 μm) is formed on the transparent substrate 2 by injection molding.
m) was used, and a disc-shaped polycarbonate having a diameter of 120 mm and a thickness of 0.6 mm was used.

The first dielectric layer 31 is formed by using a ZnS (85 mol%)-SiO ₂ (15 mol%) target with Ar.
It was formed by a sputtering method in an atmosphere. The thickness of the first dielectric layer was 90 nm.

The recording layer 4 is made of an alloy target,
It was formed by a sputtering method in an atmosphere. The composition (atomic ratio) of the recording layer was (Sb _0.67 Te _0.33 ) _0.9 Ag _0.06 In _0.04 . The thickness of the recording layer was 20 nm.

The second dielectric layer 32 was formed in the same manner as the first dielectric layer 31. The thickness of the second dielectric layer was 20 nm.

The reflection layer 5 was formed by a sputtering method in an Ar atmosphere. The target used was an Al-1.7 at% Cr alloy. The thickness of the reflection layer was 100 nm.

The protective layer 6 was formed by applying an ultraviolet curable resin by spin coating and then curing the resin by irradiation with ultraviolet light. The thickness of the protective layer was 5 μm.

After the sample thus prepared was initialized (crystallized) by a bulk eraser, the laser wavelength was 635 nm and the numerical aperture was 0.1 mm using an optical recording medium evaluation device (DDU-1000 manufactured by Pulstec). 60, a recording signal: a random signal of EFM plus (8-16) modulation, a signal was recorded in the groove, and then the recorded signal was reproduced. Linear velocities V, Pw, Pbi, Pbi during recording
Table 1 shows / Pw, Pbo, Tmp, Ttop, and Tlp, and the jitter of the reproduced signal. In the multi-pulse,
The total of the width of the upward pulse and the width of the downward pulse was 1T. Therefore, the duty ratio is equal to Tmp. In the recording waveforms shown in FIGS. 2 and 3, respectively,
The parameters other than Tmp were the same as the recording waveform shown in FIG. The shortest signal length n · Tw at the time of this recording is:
It is 28.7 ns when the linear velocity V is 14 m / s.

The jitter shown in Table 1 is a clock jitter obtained by measuring a reproduced signal using a time interval analyzer (manufactured by Yokogawa Electric Corporation) and calculating σ / Tw (%) using a window width as Tw. This clock jitter is a temporal fluctuation of the reproduced signal with respect to a frequency corresponding to the reference clock width (1T). Even if the tilt margin is taken into account, that is, even if the increase in jitter due to the tilt of the disk is expected, it can be said that there is no problem in the signal quality if the clock jitter at the time of no tilt is 9% or less.

[0123]

[Table 1]

N shown in Table 1 is a double speed display based on a linear velocity of 3.5 m / s, and N = V / 3.5. In Table 1, between Pw, Pbi, Tmp, Ttop and Tlp at each linear velocity and those at all other linear velocities, 1 <PbiH / PbiL, (PbiH / PwH) / (PbiL / PwL) <1 , 1 ≦ TmpH / TmpL, 1 <TtopH / TtopL, and 1 <TlpH / TlpL. Therefore, the jitter is small at all of the 1 to 4 times speeds.

The track on which the signal was recorded has a linear velocity of 3.5.
Direct current laser light with an output of 2 to 7 mW was applied at m / s to try to erase the recorded mark. When the CNR was measured after the irradiation, the signal attenuation of the shortest signal was 16.5 dB at the maximum. Also, when a random signal was recorded at a linear velocity of 3.5 m / s on the track irradiated with the DC laser beam and the clock jitter was measured, it was at least about 16%, and the use as a reproduced signal was not possible. It turned out to be possible. Therefore, this sample cannot rewrite information.

When the power of the DC laser beam was increased to more than 7 mW, the recording layer was melted and became amorphous after irradiation with the laser beam. That is, even if the laser power was increased, recrystallization of the recording layer was impossible.

Comparative Example 1 The recording conditions of the sample prepared in Example 1 are shown in Table 2.
The measurement was performed in the same manner as in Example 1 except for the following. Table 2 shows the results.

[0128]

[Table 2]

In Table 2, when the case No. 201 (1 × speed) in which the jitter is within the allowable range is considered as the reference case, the relationship between the reference case and case No. 202 (2 × speed) is as follows: 1 <PbiH / PbiL is not established. In addition, reference case and case No. 20
In relation to 3 (double speed), (PbiH / PwH) / (PbiL / PwL) <1 does not hold. In addition, the reference case and No. 204 (3
With respect to (double speed), 1 ≦ TmpH / TmpL is not established. In addition, the reference case and No. 205 (4
(PbiH / PwH) / (PbiL / PwL) <1 does not hold. As a result, case Nos. 202 to 20
In all 5, the jitter exceeded the allowable range.

[0130]

According to the present invention, in multi-pulse recording, the recording waveform is controlled in accordance with the linear velocity, so that the jitter can be reduced in a wide linear velocity range.

[Brief description of the drawings]

FIG. 1 is a graph showing a 5T signal and a recording waveform thereof.

FIG. 2 is a graph showing a recording waveform of a 4T signal.

FIG. 3 is a graph showing a recording waveform of a 3T signal.

FIG. 4 is a cross-sectional view illustrating a configuration example of an optical recording medium.

FIG. 5 is a cross-sectional view illustrating a configuration example of an optical recording medium.

[Description of Signs] 2 translucent base 20 support base 2G groove 2L land 31 first dielectric layer 32 second dielectric layer 4 recording layer 5 reflective layer 6 protective layer

Claims (22)

[Claims] 1. A method in which recording is performed on an optical recording medium having a recording layer containing a phase change material at a plurality of linear velocities or a linear velocity that changes continuously using recording light intensity-modulated by a recording waveform. The recording waveform has a direct current portion and a recording pulse portion for forming a recording mark. The intensity of the direct current portion is represented by Pbi, and in the recording pulse portion having at least three upward pulses, The width of the upward pulse sandwiched between the first upward pulse and the last upward pulse is represented by Tmp, and the intensity thereof is represented by Pw. One of the plurality of linear velocities or one of the continuously varying linear velocities is represented by _VL. , Pw for performing recording at a linear velocity V _L, Pbi
And Tmp, respectively PwL, and PbiL and TMPL, the faster than V _L of the plurality of linear velocities or the continuously changing linear velocity, and the linear velocity which satisfies 1.1 ≦ V _H / V _L One is V _H, and Pw, Pbi, and Tmp for recording at the linear velocity V _H are PwH, Pbi, respectively.
An optical recording method for performing recording under a condition satisfying 1 <PbiH / PbiL, (PbiH / PwH) / (PbiL / PwL) <1, where 1 ≦ TmpH / TmpL, where H and TmpH. 2. A method for performing recording at one linear velocity selected from a plurality of linear velocities on an optical recording medium having a recording layer containing a phase change material, using recording light intensity-modulated by a recording waveform. The recording waveform has a direct current portion and a recording pulse portion for forming a recording mark. The intensity of the direct current portion is represented by Pbi, and in the recording pulse portion having at least three upward pulses, represents the beginning of the width of the upward pulse and the last upward pulse sandwiched between an upward pulse Tmp, and the intensity Pw, one of said plurality of linear velocities and V _L, performs recording at a linear velocity V _L Pw, Pbi and Tmp at the time are PwL and Pbi, respectively.
And L and TMPL, the faster than V _L of the plurality of linear velocities, and one of the linear velocity which satisfies 1.1 ≦ V _H / V _L and V _H, performs recording at a linear velocity V _H Pw, Pbi and Tmp at the time are PwH, Pbi, respectively.
An optical recording method for performing recording under a condition satisfying 1 <PbiH / PbiL, (PbiH / PwH) / (PbiL / PwL) <1, where 1 ≦ TmpH / TmpL, where H and TmpH. 3. A material having at least three upward pulses in the recording pulse section, represents the width of the first upward pulse Ttop, the Ttop when performing recording at a linear velocity V _L and TtopL, the linear velocity V _H The optical recording method according to claim 1, wherein recording is performed as 1 <TtopH / TtopL, where Ttop at the time of recording is set to TtopH. 4. In the recording pulse portion having at least three upward pulses, the width of the last upward pulse is represented by Tlp, Tlp when performing recording at a linear velocity _VL is represented by TlpL, and the linear velocity is represented by Vlp. The optical recording method according to any one of claims 1 to 3, wherein recording is performed as 1 <TlpH / TlpL, where Tlp when recording at _H is TlpH. Pulse intensity and the pulse width used in each of 5. A linear velocity V _L and the linear velocity V _H is one of the optical recording method of claim 1 which is determined by the test writing to the optical recording medium. 6. The optical recording method according to claim 1, which is applied to a write-once optical recording medium. 7. Applied to a rewritable optical recording medium, the wavelength of a laser beam used for recording is λ, the numerical aperture of an objective lens of an irradiation optical system is NA, the detection window width is Tw, and the shortest recording mark corresponds. 6. The optical recording method according to claim 1, wherein when the signal length is n.Tw, n.Tw> 20 ns at the fastest linear velocity used for recording. 8. A method for performing recording on an optical recording medium having a recording layer containing a phase-change material by using recording light intensity-modulated by a recording waveform, wherein the recording waveform includes a DC portion, A recording pulse portion for forming a mark, wherein the intensity of the DC portion is represented by Pbi, and the recording pulse portion having at least three upward pulses is sandwiched between the first upward pulse and the last upward pulse. The width of the upward pulse obtained is represented by Tmp, and its intensity is represented by Pw. A reference linear velocity and recommended values of Pw, Pbi, and Tmp at this linear velocity are given, which are different from the reference linear velocity. By performing the test writing at the linear speed, the linear speed at the time of the test writing or the P actually used when actually recording information in the linear speed region including the linear speed is used.
In determining w, Pbi and Tmp, one of the linear velocity V _L and the linear velocity V _H satisfying 1.1 ≦ V _H / V _L is set as the reference linear velocity, and the other is set as the reference linear velocity. Linear velocity, linear velocity V _L
Pw, Pbi, and Tmp for recording at Pw
L, and PbiL and TMPL, PwH Pw for performing recording at a linear velocity V _H, Pbi and Tmp, respectively, when the pBIH and TmpH, 1 <PbiH / PbiL, (PbiH / PwH) / (PbiL / PwL) <1, 1 ≦ TmpH / TmpL, so that Pw, Pbi and T
Optical recording method to set mp. 9. In a recording pulse portion having at least three upward pulses, when a width of a leading upward pulse is represented by Ttop, a recommended value of Ttop at the reference linear velocity is given, Ttop for recording at linear velocity _VL is TtopL
When Ttop at the time of recording at the linear velocity V _H is TtopH, by setting Ttop at the time of trial writing so as to satisfy 1 <TtopH / TtopL, the linear velocity or the linear velocity at the time of trial writing is set. 9. The optical recording method according to claim 8, wherein Ttop used for actually recording information in a linear velocity region including the linear velocity is obtained. 10. In a recording pulse portion having at least three upward pulses, the width of the last upward pulse is represented by Tlp, and a recommended value of Tlp at the reference linear velocity is given. the Tlp of when recording at a speed V _L and Tlpl, when the Tlp for performing recording at a linear velocity V _H and TlpH, sets the 1 <TlpH during trial writing to satisfy TlpH / TlpL 10. The optical recording method according to claim 8, wherein Tlp used for actually recording information in the linear velocity at the time of the test writing or the linear velocity range including the linear velocity is obtained. 11. The optical recording method according to claim 8, which is applied to a write-once optical recording medium. 12. Applied to a rewritable optical recording medium, the wavelength of a laser beam used for recording is λ, the numerical aperture of an objective lens of an irradiation optical system is NA, the detection window width is Tw, and the shortest recording mark is supported. 11. The optical recording method according to claim 8, wherein when the signal length is n.Tw, n.Tw> 20 ns at the fastest linear velocity used for recording. 13. An optical recording apparatus capable of using either of an optical recording method according to claim 7, pulse intensity used in each of the linear velocity V _L and the linear velocity V _H and the pulse width Optical recording device. 14. An optical recording apparatus capable of using either of an optical recording method according to claim 7, pulse intensity used in each of the linear velocity V _L and the linear velocity V _H and the pulse width An optical recording device which holds a plurality of linear velocity values for each linear velocity and uses test writing on an optical recording medium when selecting an actually used pulse intensity and pulse width from the plurality of pulse intensities and pulse widths. 15. An optical recording apparatus capable of using either of an optical recording method according to claim 7, pulse intensity used in each of the linear velocity V _L and the linear velocity V _H and the pulse width Is defined as a function of the respective linear velocities, and an optical recording device that holds this function. 16. An optical recording apparatus capable of using either of an optical recording method according to claim 7, pulse intensity used in each of the linear velocity V _L and the linear velocity V _H and the pulse width Is defined as a function of the respective linear velocities, and a plurality of these functions are held for each of the linear velocities. When selecting a function to be actually used from the plurality of functions, test writing on an optical recording medium is used Optical recording device. 17. An optical recording apparatus capable of using the optical recording method according to claim 8, wherein a light holding a recommended value of pulse intensity and pulse width at the reference linear velocity. Recording device. 18. The one of the optical recording method applicable optical recording medium according to claim 7, pulse intensity and pulse width used in each of the linear velocity V _L and the linear velocity V _H is recorded Optical recording medium. 19. The one of the optical recording method applicable optical recording medium according to claim 7, pulse intensity and pulse width used in each of the linear velocity V _L and the linear velocity V _H is, each line An optical recording medium in which a plurality of speeds are recorded, and test writing on the optical recording medium is used when selecting an actually used pulse intensity and pulse width from the plurality of pulse intensities and pulse widths. 20. A one of the optical recording method applicable optical recording medium according to claim 7, pulse intensity and pulse width used in each of the linear velocity V _L and the linear velocity V _H, respectively An optical recording medium that is defined as a function of the linear velocity of 21. A one of the optical recording method applicable optical recording medium according to claim 7, pulse intensity and pulse width used in each of the linear velocity V _L and the linear velocity V _H, respectively Is defined as a function of the linear velocity, and a plurality of these functions are recorded for each linear velocity. When selecting a function to be actually used from the plurality of functions, a test recording on an optical recording medium is used. Medium. 22. An optical recording medium to which the optical recording method according to claim 8 can be applied, wherein the optical recording medium records a recommended value of pulse intensity and pulse width at the reference linear velocity. Medium.