JP2000285453A - Write-once-type phase change optical recording medium, write-once-type phase change optical recording method and write-once-type phase change optical recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a write-once-type phase change optical recording method which is most suitable for recording information on a write-once-type phase change optical recording medium with a laser pulse beam. SOLUTION: A write-once-type phase change recording method is such that a laser beam is applied to an amorphous phase recording layer and a crystal phase recording mark is formed to record information. A laser beam is outputted as a pulse beam comprising a leading pulse train P1, a following pulse train P2 following the leading pulse train and a tail pulse series P3. The leading pulse train P1, the following pulse series P2 and the tail pulse train P3 are composed of on-pulses P1on, P2on and P3on with predetermined output values and off-pulses P1off, P2off and P3off with output values lower than those of on-pulses P1on, P2on and P3on and, further, the output values and time constants of the leading pulse train P1, the following pulse train P2 and the tail pulse train P3 are individually controlled respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a write-once phase change optical recording medium, a write-once phase change optical recording method, and a write-once phase change optical recording apparatus.

[0002]

2. Description of the Related Art At present, as a write-once optical recording medium on which information can be recorded only once, a CD-R (Compact Disc-Record) using an organic dye material is used.
able) has already been commercialized. The organic dye-based material is advantageous in that the process cost can be reduced, but it is necessary to take measures against light deterioration and deterioration due to heat. Therefore,
A write-once optical disc is converted to a DVD (Digital Vi
In order to have a capacity similar to that of a (deo disc) -ROM, it is necessary to use an inorganic material for a write-once optical disc. As an example of using an inorganic material for a write-once optical disc, for example, JP-A-7-93806 is listed. Japanese Patent Application Laid-Open No. Hei 7-93806 relates to a diffusion alloy type optical disk in which a two-layer recording film made of different materials is provided, and this recording film is irradiated with a laser beam and thermally diffused.

[0003] In a rewritable phase change recording medium,
It is known that high-density information can be stably recorded by using a pulsed laser beam for recording information. An example of such a laser beam is a pulse beam as shown in FIG. The laser beam shown in FIG. 4 is provided with an amorphous phase recording layer on a previously crystallized (initialized) recording layer, and is a CD-RW which is a commercially available rewritable phase change medium.
(Compact Disc-Record Writ
ab) standard recording method.

An example of overwriting information with a single pulsed laser beam is disclosed in JP-A-8-2355.
No. 88 is listed. The invention described in JP-A-8-235588 relates to a recording method for forming a recording mark of an amorphous phase in a crystalline phase. Then, the beam power is biased to the erasing level, the pulse width of the laser to be irradiated is limited, and the recording layer that has been made amorphous is rapidly cooled in order to prevent recrystallization.

[0005]

There has been a demand for a write-once phase change optical disk to additionally write information using a pulse laser beam as used in the above-mentioned rewritable phase change recording medium, thereby further increasing the information recording density. is there. However, the write-once phase change optical disk is configured to form a recording mark of a crystalline phase on a recording layer of an amorphous phase, as opposed to a rewritable optical disk. For this reason, a power higher than the erase level cannot be applied to a region where a recording mark is not formed, and when the recording layer is rapidly cooled, the recording layer once heated above the melting point becomes amorphous. Furthermore, a recording method for a write-once optical disc requires that recorded information is not accidentally rewritten. From the above points, the laser pulse light of the rewritable optical disc cannot be applied to the information recording of the write-once phase change optical disc.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and is directed to a write-once phase-change optical recording method and a write-once write-once phase-change optical recording medium which are optimal for recording information on a write-once phase change optical recording medium by laser pulse light. It is an object of the present invention to provide a changeable optical recording device, and to provide a write-once phase change optical recording medium on which information can be stably recorded at higher density.

[0007]

The above-mentioned problems are solved by the following means. That is, the invention according to claim 1 is a write-once type phase-change optical recording method in which a non-crystalline recording layer is irradiated with a laser beam to record information by providing a crystalline phase recording mark. It is output as a pulse light having a first pulse train, a succeeding pulse train following this, and a last pulse train output thereafter, and a first pulse train,
The subsequent pulse train and the last pulse train are configured as a pulse train composed of an ON pulse having a predetermined output value and an OFF pulse having an output value lower than the ON pulse, and the output value and time constant of the first pulse train, the subsequent pulse train, and the last pulse train Are controlled independently of each other.

With this configuration, the conditions such as the output value and the time constant of the first pulse train, the succeeding pulse train, and the last pulse train can be set independently, and the degree of freedom in setting the conditions is expanded. Therefore, in forming a recording mark,
The laser light can be further optimized.

According to a second aspect of the present invention, the off-pulse of the first pulse train and the subsequent pulse has an output value higher than that of the laser beam applied to the recording layer on which no recording mark is formed.

With this configuration, the temperature decrease rate of the recording layer during the irradiation of the first pulse train and the subsequent pulse train is moderated, and the once liquefied recording layer can be prevented from becoming amorphous.

According to a third aspect of the present invention, the on-pulse of the last pulse train has an output value higher than at least the on-pulse of the subsequent pulse train, and the off pulse of the last pulse train has an output value lower than at least the off-pulse of the subsequent pulse train. It is characterized by having.

With this configuration, after the temperature rises due to the irradiation of the last pulse train with the laser beam, the cooling rate is increased. Therefore, the portion irradiated with the laser beam of the last pulse train becomes amorphous.

According to a fourth aspect of the present invention, the on-pulse of the last pulse train has a wider pulse width than at least the on-pulse of the succeeding pulse train, and the off-pulse of the last pulse train has an output value lower than at least the off-pulse of the subsequent pulse train. It is characterized by having.

With this configuration, after the temperature rises due to the irradiation of the last pulse train with the laser beam, the cooling rate is increased. Therefore, the portion irradiated with the laser beam of the last pulse train becomes amorphous.

According to a fifth aspect of the present invention, the on-pulse of the last pulse train has at least a higher output value and a wider pulse width than the on-pulse of the subsequent pulse train, and the off-pulse of the last pulse train has at least the output pulse of the subsequent pulse train. It is characterized by having an output value lower than the off pulse.

With this configuration, after the temperature rise due to the irradiation of the last pulse train with the laser beam, the cooling rate is further increased. For this reason, the portion irradiated with the laser beam of the last pulse train becomes sufficiently amorphous.

According to a sixth aspect of the present invention, the last pulse train is output on condition that at least the first pulse train has been output.

With this configuration, it is possible to eliminate the possibility that the last pulse train is irradiated on the entire surface of the recording layer and the stored information is falsified.

According to a seventh aspect of the present invention, there is provided a head pulse train,
It has a recording mark formed by irradiating a pulsed laser beam having a succeeding pulse train following this, and a tail pulse train output thereafter, while relatively moving the amorphous recording layer. A write-once type phase-change optical recording medium, wherein a recording mark has a crystalline phase mark portion formed by a first pulse train and a subsequent pulse train, and an amorphous mark portion formed by a last pulse train. The mark portion is characterized in that the size in the direction orthogonal to the direction of movement of the laser beam is formed larger than the crystal mark portion.

With this configuration, it is possible to prevent the erasing of the crystal mark.

An eighth aspect of the present invention is a write-once type phase change optical recording apparatus for forming a recording mark by irradiating a laser beam onto an information recording medium and crystallizing an amorphous recording layer. The laser light is a pulse light having a first pulse train, a subsequent pulse train following this, and a last pulse train output thereafter, and the first pulse train, the subsequent pulse train, and the last pulse train are turned on pulses having a predetermined output value. A laser light output unit that outputs a pulse train composed of an off pulse having an output value lower than the on pulse, and a pulse train control unit that independently controls output conditions of the first pulse train, the subsequent pulse train, and the last pulse train. It is characterized by the following.

With this configuration, it is possible to independently set the conditions such as the output value and the time constant of the first pulse train, the succeeding pulse train, and the last pulse train, and to provide a write-once type phase change optical recording apparatus having a wide degree of freedom in setting conditions. Can be configured. Therefore, a more optimal laser beam can be generated when forming a recording mark.

According to a ninth aspect of the present invention, the pulse train control means includes a leading rise time control means for controlling a rise delay time of a leading pulse train, an on pulse width / off pulse width ratio of a succeeding pulse train, an on pulse width of a trailing pulse train, A pulse width setting means for independently setting the off pulse width, and a non-formation output value P0 which is an output value of laser light in a region of the recording layer where a recording mark is not formed,
On pulse output value P1 _on and _off pulse output value P1 _{off of} the first pulse train, on pulse output value P2 of the subsequent pulse train
_on and off pulse output value P2 _off, and a last pulse train on-pulse output value P3 _on and off pulse output value P3 _off, is characterized in that an output value setting means for setting the following conditions. P3 _off ≤ P0 P1 _off > P0, P2 _off > P0 P2 _on > P2 _off P3 _on ≥ P2 _on

With this configuration, a write-once type phase-change optical recording apparatus that generates a more optimal laser beam when forming a recording mark can be configured.

According to a tenth aspect of the present invention, the laser light output means outputs the last pulse train on condition that at least the first pulse train has been output.

With this configuration, the risk that the last pulse train is irradiated onto the entire surface of the recording layer and the stored information is falsified can be eliminated on the device side.

[0027]

Embodiments of the present invention will be described below. FIG. 1 shows an optical disc 10 which is a write-once type phase change optical recording medium of the present invention.
FIG. 2B is an external view in which a part of 0 is cut away, and FIG.
It is the figure which expanded and showed the cross section shown by a in the inside. Also,
FIG. 2 is a diagram for explaining a pulsed laser beam used to form the recording mark M in FIG. 1, and FIG. 3 is a postscript allowing additional recording of information on the optical disk 10 shown in FIG. It is a block diagram for explaining a phase change optical recording device.

As shown in FIG. 1, an optical disk 10 according to the present invention has a lower protective layer 5 directly formed on a transparent substrate 6. The recording layer 4, the upper protective layer 3, the reflective layer 2, and the overcoat layer 1 are formed in this order from the lower protective layer 5 to the upper layer. PC (polycarbonate) is used for the transparent substrate 6, and ZnS. S
iO ₂ , SiNx and the like can be used. Here, Z
nS. It is assumed that SiO ₂ is used.

The recording layer 4 is an amorphous film. Typical examples of the material include TeO _x and Sb.
-Se. In this embodiment, an SbSe phase change film is deposited to a thickness of 5 to 25 nm by a sputtering method and used as a recording film. Further, as a material of the upper protective layer 3, ZnS. SiO ₂ , SiNx, etc. can be used. In this case, ZnS. SiO ₂ (film thickness 20 nm) is used. At this time, the recording layer below the upper protective layer 3 is stored in an amorphous state.

The material of the reflection layer 2 is Al,
An Al alloy, Au, Ag, or the like can be used. Here, an Al alloy (Al-Ti: 1 wt%: 120 nm) is used. On this upper layer, as an overcoat layer 1, UV
The curable resin is applied, and the optical disc 10 is completed.

In the optical disc 10 described above, a recording mark M is formed on the recording layer 4 in an amorphous state by a pulsed laser beam. The recording mark M has a crystal mark portion c and an amorphous mark portion a as shown in FIG. Further, the pulsed laser beam forming such a recording mark M has a leading pulse train P1, a succeeding pulse train P2 following this, and a trailing pulse train P3 output thereafter. The crystal mark portion c is formed by the first pulse train P1 and the subsequent pulse train P2, and the non-crystal mark portion a is formed by the last pulse train P3.

The first pulse train P1, the subsequent pulse train P2, and the last pulse train P3 each have on-pulses (P1 _on , P2 _on , P3 _on ) having predetermined output values and off-pulses (P1 _off) having lower output values than the _on- pulses. , P2 _off , P3
_off ). The ON / OFF pulse output value, output time (pulse width), ON / OFF duty ratio, and rise time and time constant of the first pulse train P1, the subsequent pulse train P2, and the last pulse train P3 are shown in FIG. Each pulse train is independently controlled by the write-once phase change optical recording apparatus.

The write-once phase-change optical recording apparatus shown in FIG. 3 uses a recording waveform generator 11 for generating a pulse wave (recording waveform) having the shape shown in FIG. 2 and a clock signal output from an external clock generator 12. The laser diode (LD) driver 1 receives the input and synchronizes with the waveform generated by the recording waveform generator 11.
And a recording system control unit 13 for controlling the optical recording head unit 15. Laser diode driver 14
Is a configuration in which the optical disk 10 is rotated, and the optical recording head unit 15 is configured to move a head that outputs laser light in the radial direction of the optical disk 10 while focusing the optical disk 10. As a result of the rotation of the disk 10 and the movement of the optical recording head 15, the optical recording head 15
The upper part relatively moves in the direction of arrow A shown in FIG.

Next, the operation of the write-once phase change optical recording apparatus shown in FIG. 3 will be described, and this write-once phase change optical recording method and the optical disk 10 (write-once type phase change optical recording medium) formed will be described in more detail. When an instruction to start the additional recording process is input, the recording waveform generator 11 generates the recording waveform shown in FIG. The recording system controller 13 causes the optical recording head 15 to output a pulsed laser beam based on the recording waveform.

The laser beam of the pulse-shaped, as described above, the on-pulse P1 _on, off pulse P1 leading pulse train P1 and a _off, on-pulse P2 _on, subsequent pulse train having an off-pulse P2 _off P2, on-pulse P3 _on, off pulse P3 _off and the last pulse train P3 having _off . The output values of the _on- pulses P1 _on , P2 _on and P3 _on are set so as to give sufficient power to raise the recording layer 4 to a temperature higher than the crystallization temperature.

Further, as is well known, a recording layer in which the atomic arrangement is in a disordered liquid state due to a rise in temperature is crystallized when the recording layer is kept at a temperature higher than the crystallization temperature for a certain time. Therefore, the _off pulses P1 _off , P2 _off , P3 _off
Is set so that the cooling rate of the recording layer 4 is moderated and the area of the recording layer 4 where the recording mark M is to be formed is kept at the crystallization temperature or higher for a predetermined time. Further, the output value P0 of the laser beam to be applied to the area where the recording mark M is not formed (mark non-forming area) is set lower than any of the off-pulses so as not to damage the amorphous layer of the recording layer 4. I have.

The crystal mark portion c of the recording mark M is formed by a first pulse train P1 and a subsequent pulse train P2, and the amorphous mark portion a is formed by a last pulse train P3. For this reason, the off-pulses of the first pulse train P1 and the subsequent pulse train P2 are set to the same output value so that the crystal state of the crystal mark part c is continuously uniform. However, the output values of the on-pulses of the first pulse train P1 and the subsequent pulse train P2 may be the same or different.

The formation start end s and formation end end e of the recording mark M are important parts for determining the edge of the recording mark. The formation start end s is determined by the rise time τ _Fp and the time constant of the leading pulse train P1. For this reason, the rise time τ _Fp and the time constant are set to values optimized in advance by experiments and the like. On the other hand, the formation end end e of the recording mark M is determined by the size of the non-crystalline mark portion a.
For this reason, the last pulse train P3 forming the amorphous mark portion a is set so that its output value and output time can form the amorphous mark portion a having a desired size.

That is, in the last pulse train P3, the temperature given to the recording layer 4 by the _on- pulse P3 _on is rapidly lost, and the recording layer 4 is easily made amorphous. Therefore, in the present embodiment, the _on- pulse P3 _on is higher than the on-pulses of the leading pulse train P1 and the succeeding pulse train P2, and the off-pulse P3 _off is lower than the off-pulses of the leading pulse train P1 and the succeeding pulse train P2. (It is even lower than the laser output value P0 applied to the area).

In the present embodiment, the off pulse P3
_Off is set low, and the _on- pulse P3 _on of the last pulse train P3 has a wider pulse width than the _on- pulses of the succeeding pulse train P2 and the last pulse train P3, so that the temperature of the amorphous mark portion a is sufficiently raised. I have. As a result, the crystallization range is expanded, and the size of the non-crystal mark portion a becomes larger than the crystal mark portion c in the direction of movement of the laser beam, that is, in the direction perpendicular to the arrow A, and the recording mark M remains The deterioration of the jitter of the optical disk 10 is prevented.

The conditions of the above-described first pulse train P1, subsequent pulse train P2, and last pulse train P3 are summarized as follows. P3 _off ≤ P0 P1 _off > P0, P2 _off > P0 P2 _on > P2 _off P3 _on ≥ P2 _on By setting the first pulse train P1, the subsequent pulse train P2, and the last pulse train P3 in this manner, the edge of the recording mark M is set. The positional accuracy is improved, the quality of the optical disk 10 can be improved, and information can be recorded on the write-once phase change optical recording medium under the optimum laser beam condition.

Incidentally, the write-once phase change optical recording medium is characterized in that information over time can be stored without tampering. Therefore, in the present invention, when the last pulse train P3 is generated, the entire surface of the recording layer 4 is made amorphous to prevent the information from being rewritten, provided that at least the first pulse train P1 is generated. Like that. Further, it is also possible to configure such a lock mechanism for the output of the last pulse train P3 in the recording system control unit 13 as a laser beam output unit.

Next, information was recorded on the optical disk 10 of the embodiment described above by the write-once phase change optical recording method of the embodiment using the write-once phase change optical recording apparatus of the embodiment. The results will be described. Recording conditions Minimum recording bit length 0.267 μm Recording linear velocity 3.5 m / s First pulse train P1, subsequent pulse train P2 ON pulse output value
7 to 13 mW First pulse train P1, subsequent pulse train P2 Off pulse output value
1 to 4 mW Last pulse train P3 on pulse output value 11 to 15 mW Last pulse train P3 off pulse output value 1 mW Subsequent pulse train P2 Duty ratio 50% (fixed)

In the present embodiment, the recording performed under the above conditions was evaluated by the data-to-clock jitter (hereinafter simply referred to as a jitter value) between the data signal read from the recording mark M and the clock signal. In this evaluation, a jitter value of 11% or less was obtained by optimizing the rise time τ _FP and the time constant and pulse width of the last pulse train P3. Under the following conditions, a jitter value of 8.
3% was obtained, and the result was obtained that the write-once type phase-change optical recording having the capacity compatibility with the DVD-ROM became possible. First pulse train P1, subsequent pulse train P2 ON pulse output value
10mW First pulse train P1, subsequent pulse train P2 Off pulse output value
1 mW Last pulse train P3 on pulse output value 14 mW Last pulse train P3 off pulse output value 1 mW

[0045]

The present invention described above has the following effects. That is, according to the first aspect of the present invention, it is possible to further optimize the laser beam when forming the recording mark. For this reason, a recording mark can be written more stably and at a high density on the write-once type phase change optical recording medium.

According to the second aspect of the present invention, it is possible to prevent the once liquefied recording layer from being in an amorphous state, and to form a recording mark having a good crystal phase. Therefore, the data-to-clock jitter of the formed recording mark can be improved.

According to the third aspect of the present invention, it is possible to form a recording mark having a better crystal phase by eliminating the unerased portion of the recording mark. Therefore, the data-to-clock jitter of the formed recording mark can be improved.

According to the fourth aspect of the present invention, it is possible to eliminate the unerased portion of the recording mark and to form a recording mark having a better crystal phase. Therefore, the data-to-clock jitter of the formed recording mark can be improved.

According to the fifth aspect of the present invention, it is possible to surely eliminate the unerased portion of the recording mark and to form a recording mark having a better crystal phase. Therefore, the data-to-clock jitter of the formed recording mark can be further improved.

The invention described in claim 6 eliminates the possibility that the stored information is falsified, and can prevent the reliability of the write-once type phase change optical recording medium from lowering.

According to the seventh aspect of the present invention, it is possible to provide a write-once type phase change optical recording medium of higher quality by preventing erasure of a crystal mark.

The invention according to claim 8 can provide a write-once type phase-change optical recording apparatus capable of generating a more optimum laser beam when forming a recording mark. Therefore, a recording mark can be written more stably and at a high density on the write-once phase change optical recording medium.

According to the ninth aspect of the present invention, a write-once type phase-change optical recording apparatus that generates a more optimum laser beam when forming a recording mark can be configured. Therefore, a recording mark can be written more stably and at a high density on the write-once phase change optical recording medium.

According to the tenth aspect of the present invention, the possibility that the stored information is falsified can be eliminated on the device side, and the reliability of the write-once type phase change optical recording medium can be reliably prevented from lowering. As described above, according to the present invention, the write-once type phase-change optical recording method and the write-once type phase-change light recording method are optimal for recording information on a write-once type phase-change optical recording medium by laser pulse light. By providing a recording device, it is possible to provide a write-once type phase change optical recording medium on which information can be stably recorded at a higher density.

[Brief description of the drawings]

FIG. 1 is an optical disc which is a write-once type phase change optical recording medium of the present invention, wherein (a) is an external view of the optical disc with a part cut away, and (b) is shown in (a). It is the figure which expanded and showed the cross section.

FIG. 2 is a diagram for explaining pulsed laser light used to form a recording mark in FIG. 1;

FIG. 3 is a block diagram for explaining a write-once type phase-change optical recording apparatus capable of additionally writing information on the optical disc shown in FIG. 1;

FIG. 4 is a diagram showing pulse light that is substantially the same as that used in a recording method that is a well-known CD-RW standard.

[Description of Signs] 1 Overcoat layer 2 Reflective layer 3 Upper protective layer 4 Recording layer 5 Lower protective layer 6 Transparent substrate 10 Optical disk 11 Recording waveform generator 12 External clock generator 13 Recording system controller 14 Laser diode driver 15 Optical recording Head part

Claims (10)

[Claims] 1. A method for irradiating a laser beam to a recording layer of an amorphous phase,
A write-once phase change optical recording method for recording information by providing a recording mark of a crystal phase, wherein the laser beam has a leading pulse train, a succeeding pulse train following this, and a trailing pulse train output thereafter. Output as a pulsed light, the first pulse train, the subsequent pulse train, the last pulse train, while forming a pulse train consisting of an ON pulse having a predetermined output value and an OFF pulse having an output value lower than the ON pulse, the first pulse train, A write-once type phase change optical recording method, wherein an output value and a time constant of a succeeding pulse train and a last pulse train are independently controlled. 2. The write-once type phase change according to claim 1, wherein the off-pulse of the first pulse train and the subsequent pulse has a higher output value than a laser beam applied to a recording layer on which a recording mark is not formed. Optical recording method. 3. The on-pulse of the last pulse has an output value higher than at least the on-pulse of the subsequent pulse, and the off-pulse of the last pulse has an output value lower than at least the off-pulse of the subsequent pulse. The write-once phase change optical recording method according to claim 2, wherein: 4. The on-pulse of the last pulse has a wider pulse width than at least the on-pulse of the subsequent pulse, and the off-pulse of the last pulse has an output value lower than at least the off-pulse of the subsequent pulse. The write-once phase change optical recording method according to claim 2, wherein: 5. The on-pulse of the last pulse has at least a higher output value and a wider pulse width than the on-pulse of the subsequent pulse, and the off-pulse of the last pulse is at least lower than the off-pulse of the subsequent pulse. 3. The write-once phase change optical recording method according to claim 2, wherein the write-once phase change optical recording method has a low output value. 6. The write-once phase change optical recording according to claim 1, wherein the last pulse is output on condition that at least the first pulse is output. Method. 7. A non-crystalline recording layer is irradiated with a pulsed laser beam having a first pulse train, a succeeding pulse train following the first pulse train, and a last pulse train output thereafter while being relatively moved. A write-once phase change optical recording medium having a recording mark formed by the above, wherein the recording mark is formed by a crystal phase mark portion formed by the first pulse train and the subsequent pulse train, and formed by the last pulse train A non-crystalline mark portion, wherein the size of the non-crystalline mark portion in a direction orthogonal to the moving direction of the laser beam is formed larger than that of the crystal mark portion. Phase change optical recording medium. 8. A write-once type phase-change optical recording apparatus that irradiates a laser beam to an information recording medium and crystallizes an amorphous recording layer to form a recording mark, A first pulse train, a subsequent pulse train following this, a pulse light having a last pulse train output thereafter, the first pulse train, the subsequent pulse train, the last pulse train, an on-pulse having a predetermined output value, the on-pulse, Laser light output means for outputting a pulse train composed of an off pulse having a lower output value, and pulse train control means for independently controlling output conditions of the first pulse train, the subsequent pulse train, and the last pulse train. Write-once phase change optical recording device. 9. The pulse train control means according to claim 1, wherein:
Rise time control method for controlling the rise delay time of
An on-pulse width and an off-pulse width ratio of the subsequent pulse train;
On-pulse width and off-pulse width of the last pulse train
A pulse width setting means for independently setting, and a recording layer in a region where a recording mark is not formed in a recording layer.
When the non-formed output value P0 which is the output value of the laser beam is set,
In both cases, the on-pulse output value P1 of the first pulse train _onAnd
And off pulse output value P1_off, The on-pulse of the following pulse train
Loose output value P2_onAnd off-pulse output value P2_offAnd said
On-pulse output value P3 of the last pulse train_onAnd off-path
Loose output value P3_offAnd output value setting to set the following conditions.
9. The postscript according to claim 8, further comprising:
Phase change optical recording device. P3_off≤P0 P1_off> P0, P2_off> P0 P2_on> P2_off P3_on≧ P2_on 10. The write-once phase change optical recording according to claim 8, wherein the laser light output means outputs the last pulse on condition that at least the first pulse is output. apparatus.