JP2003085756A - Method and device for recording optical information recording medium, and optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for recording an optical information recording medium, which easily determines the most suitable pulse in a short time. SOLUTION: In the case of recording at least the longest mark, one first pulse, one or more multi-pulses, and one last pulse are radiated in order; and when four parameters of the laser irradiation start position and the laser irradiation end position for the first pulse and those for the last pulse are changed to obtain the most suitable recording waveform, only at least two parameters of the laser irradiation start position for the first pulse and the laser irradiation start or end position for the last pulse out of four parameters are changed to determine the most suitable recording waveform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium recording method, recording apparatus, and recording method for recording information on a pre-groove or between pre-grooves using a substrate on which pre-grooves are formed. The present invention relates to an optical information recording medium.

[0002]

2. Description of the Related Art In recent years, with the diversification of information, a large-capacity optical information recording medium has attracted attention. The optical information recording medium includes
There are a read-only information recording medium, a write-once information recording medium capable of additional recording, and a rewritable information recording medium capable of rewriting information.

Of these, when a write-once type information recording medium or a rewritable type information recording medium on which a user can record information is used, a long pulse is emitted with high power in the track direction depending on the content of information. There is.

However, when a laser beam having a long power and a long power is irradiated in the track direction, the temperature becomes higher toward a later-irradiated portion due to heat conduction, and the width of the area to be recorded or erased in the radial direction of the disk becomes large. , The shape becomes teardrop.

When a signal is reproduced from a portion having such a shape, the reproduced signal waveform is distorted and the S / N is deteriorated. In the case of the bit edge detection method, a reproduced signal which corresponds to the recorded signal cannot be obtained correctly. There is a drawback that.

In order to solve this problem, Japanese Patent Laid-Open No. 9-28
An information recording method as described in Japanese Patent No. 2662 has been proposed. This method divides a long-width pulse (original pulse) into two or more pulse trains, and tries to reduce the average irradiation energy toward the rear part of the original pulse. Specifically, it is a method of increasing the number of divisions or the number of stages of power change in a portion where irradiation with a high power level continues for a long time.

FIG. 4 is a recording waveform diagram showing an example of this information recording method in which the number of divisions in the rear part is increased. In the figure, W is a recording power level, E is an erasing power level, and R is a reading power level.

[0008]

When the proposed method of recording information is adopted, the disadvantage that the rear part of the pulse spreads in the radial direction of the disk and the shape becomes teardrop-shaped is solved, and a well-shaped long shape is formed. It was possible to obtain a circular shape, and it was possible to solve the problems such as the error rate of the reproduction signal, the unerased portion during erasing, and the increase in noise due to deformation, but it is not without problems.

That is, in this recording method, consideration is given to determining the optimum pulse, that is, consideration is given to the irradiation start position of the first pulse, the irradiation end position of the first pulse, the irradiation start position of the last pulse, the irradiation end position of the last pulse, and the like. However, there is a problem in that it takes time to determine the pulse and it is complicated.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, to provide an optical information recording medium recording method, recording apparatus, and optical information recording medium in which the optimum pulse can be easily determined and can be performed in a short time. To provide.

[0011]

To achieve the above object, the first means of the present invention is an optical information recording medium for recording information by irradiating a recording layer of the optical information recording medium with a laser beam. In the recording method, when recording at least the longest mark, one first pulse, one or more multi-pulses, and one last pulse are sequentially irradiated, and the laser irradiation start position, laser irradiation end position, and last pulse of the first pulse are recorded. When the optimum recording waveform is obtained by changing the four parameters of the laser irradiation start position and the laser irradiation end position, the first pulse laser irradiation start position and the last pulse laser irradiation start position or the laser are selected from the four parameters. Optimum recording waveform is determined by changing at least two parameters of irradiation end position And it is characterized in Rukoto.

According to a second aspect of the present invention, in the first aspect, the optical information recording medium is a phase change type optical information recording medium.

According to a third aspect of the present invention, in a recording apparatus of an optical information recording medium for recording information by irradiating a recording layer of the optical information recording medium with a laser beam, at least the longest mark is 1 One fast pulse, one or more multi-pulses, one last pulse are irradiated in this order, and four parameters of the laser irradiation start position and the laser irradiation end position of the first pulse, the laser irradiation start position and the laser irradiation end position of the last pulse When the optimum recording waveform is obtained by changing, the optimum by changing at least two parameters of the laser irradiation start position of the first pulse and the laser irradiation start position or the laser irradiation end position of the last pulse among the above four parameters. The recording waveform is determined, and the laser light is determined based on the determined recording waveform. It is characterized in that the irradiation.

According to a fourth aspect of the present invention, in the third means, the optical information recording medium is a phase change type optical information recording medium.

A fifth means of the present invention is an optical information recording medium for recording information by irradiating a recording layer with laser light,
When recording at least the longest mark, one fast pulse, one or more multi-pulses, and one last pulse are sequentially irradiated, and the laser irradiation start position and the laser irradiation end position of the first pulse, and the laser irradiation start of the last pulse are started. When obtaining the optimum recording waveform by changing the four parameters of the position and the laser irradiation end position, the laser irradiation start position of the first pulse and the laser irradiation start position or the laser irradiation end position of the last pulse are selected from among the four parameters. An optimum recording waveform is determined by changing only at least two parameters, and information is recorded by irradiating a laser beam based on the determined and determined recording waveform.

A sixth means of the present invention is characterized in that, in the fifth means, the recording layer is a phase change type recording layer.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 3 is a partially enlarged cross-sectional view of a bonded type phase change optical disk used in the embodiment of the present invention. 1, 1'in the figure is a transparent substrate, 2, 2'is a dielectric layer, 3, 3 '
Is a reflectance adjusting layer, 4, 4'is an interface layer, 5, 5'is a recording layer, 6, 6'is an interface layer, 7, 7'is an intermediate layer, 8 and 8'is an absorptance correction layer, 9, 9'is a reflective layer, 10 and 10 'are absorptance correction layers, 11 and 11' are protective layers, and 12 is an adhesive layer.

Next, a method of manufacturing this optical disk will be described. A transparent substrate 1 in which irregularity pits (pre-pits) including address information and U-shaped grooves (pre-grooves) having a pitch of 1.23 μm are formed in advance on the surface of a polycarbonate resin plate having an outer diameter of 120 mm and a thickness of 0.6 mm. Prepared. The widths of the U-shaped grooves (lands) between the grooves are substantially equal and are set to about 0.6 μm.

This substrate 1 has a plurality of sputtering chambers,
It is ideal for sputtering equipment with excellent film thickness uniformity and reproducibility.
It was placed in one sputtering chamber. ZnS and S as targets
iO ₂ Of argon and a thickness of 125 n in argon gas.
m (ZnS)₈₀(SiO₂)₂₀ Consists of (mol%)
The dielectric layer 2 was formed. This substrate is then placed in a second spa
Al as a target after moving to the chamber₂ O₃ For
Al with a thickness of 10 nm in argon gas₂ O₃ Empty
The reflectance adjusting layer 3 was formed.

Further, this substrate was moved to a third sputtering chamber, and a Cr ₂ O ₃ target was used to form an interface layer 4 made of Cr ₂ O ₃ having a thickness of 1 nm in argon gas. Then, the substrate was moved to the fourth sputtering chamber, and a Ge _28.9 Sb _16.9 Te _54.2 (atomic%) sintered body was used as a target.
Ge _28.9 Sb _16.9 Te _54.2 (atomic%) in argon gas
The recording layer 5 made of 8 nm was formed.

Next, the substrate is moved to the fifth sputtering chamber and C
r₂ O₃ Using the target, Cr ₂ O₃ An interface consisting of
Layer 6 was formed to 3 nm. Then, the substrate is placed in the sixth sputtering chamber.
To a thickness of 40n in the same manner as the formation of the dielectric layer 2.
m (ZnS)₈₀(SiO₂)₂₀ (Mol%) middle layer
Formed 7. Then, in the sixth sputtering chamber, Cr- (Cr
₂ O₃ ) Using an alloy as a target, Cr₉₅(Cr₂ 
O₃ )_Five (Mol%) of the absorptance correction layer 8 having a thickness of 30 nm is formed.
It was

Next, using Al ₉₉ Ti ₁ (wt%) as a target in the eighth sputtering chamber, a reflective layer 9 made of Al ₉₉ Ti ₁ was formed to a thickness of 30 nm. Finally, in the ninth sputtering chamber, Ti was used as a target, and a stress adjusting layer 10 made of Ti was formed to a thickness of 100 nm. The substrate on which the film was formed was taken out from the sputtering apparatus, and the ultraviolet curable resin protective layer 11 was formed on the uppermost layer by spin coating.

Similarly, on another similar substrate 1 '
(ZnS)₈₀(SiO₂ )₂₀ (Mol%) dielectric layer
2 ', Al₂ O₃ Reflectance adjusting layer 3 ', Cr₂ O₃ World of
Face layer 4 ', Ge_28.9Sb_16.9Te_54.2Record (atomic%)
Layer 5 ', Cr₂ O₃ Interface layer 6 ', (ZnS)₈₀(Si
O₂ )₂₀ (Mol%) intermediate layer 7 ', Cr₉₅(Cr₂ O
₃ )_Five (Mol%) Absorbance correction layer 8 ', Al₉₉Ti₁ (Heavy
%) Reflective layer 9 ', Ti stress adjusting layer 10', ultraviolet light
A protective layer 11 'of cured resin is sequentially formed.

The two substrates 1 and 1 ′ were bonded together by the adhesive layer 12 with the UV-curable resin protective layers 11 and 11 ′ inside. At this time, if the diameter of the adhesive layer 12 was set to 118 nm or more, peeling of the adhesive layer 12 due to an impact such as dropping did not occur easily.

A double-sided laminated type optical disk manufactured as described above was used, with a wavelength of 810 nm and a beam major axis of 75 μm.
Initialization was performed by irradiating a laser beam having an elliptic beam with a diameter of m and a short diameter of 1 μm.

After that, the optical disc is moved to a linear velocity of about 8.5 m.
/ S, and a semiconductor laser beam having a wavelength of 650 nm is condensed by an objective lens having a numerical aperture (NA) of 0.6 and irradiated onto the recording layer 5 through the substrate 1 to record information.
Played back. Laser power of 11.5 mW for recording,
An 8-16 modulated random signal was recorded using a waveform modulated between two values of 4.5 mW. Recording was done on the pregroove.

FIG. 1 is a schematic diagram of a recording waveform (recording strategy) when recording information by irradiating the laser beam. As shown in the figure, when recording at least a long mark, four pulses are sequentially formed in the order of one fast pulse, one or more (two in this embodiment) multi-pulse, one last pulse, and one cooling pulse. It is divided and output. And the multi-pulse and the cooling pulse have a fixed start position and end position of laser irradiation,
Other pulses make the start position and end position of laser irradiation variable.

In the figure, Tsfp indicates the laser irradiation start position of the first pulse, and Tefp indicates the laser irradiation end position of the first pulse. Further, Tslp indicates the laser irradiation start position of the last pulse, and Telp indicates the laser irradiation end position of the last pulse. These Tsfp, Tefp, Ts
Jitter was optimized using L18 of the experimental design method with four parameters of lp and Telp as experimental factors.

Tefp (start position of first pulse)
32 ns, 25 ns, 18 ns, Tslp (start position of last pulse) is 5 ns, 0 ns, -7 ns, Tsf
p (the end position of the first pulse) is set to 2ns, -5n
s, -8 ns, Telp (end position of the last pulse) were selected as 20 ns, 15 ns and 8 ns, respectively, and set as the first, second and third levels. The recording power Pp was set so that the asymmetry of the 6T repetitive signal was 5%. The erasing power was constant.

For each of 18 recording strategies (recording waveforms), jitter (Jow) when 8-16 random signals were overwritten 10 times on a single track
10) Jitter after 10,000 times (Jow 10K) and jitter 10 times when a signal was recorded on an adjacent track (Jo
w10CT) was measured. The jitter values of 18 recording strategies were converted into S / N using the following formula.

S / N [db] = 10 log (β ² / σ ² ) Expression (1) Here, β corresponds to the length of the reproduction signal with respect to the length of the input signal. This time it is assumed to be approximately 1. σ is a noise component, which corresponds to jitter in this experiment. By taking the logarithm, a relation of addition is established to the factor effect by the combination of control factors.

The characteristics when the optimization is performed are shown in FIG. That is, this figure is a characteristic diagram showing the dependence of each pulse position on the total jitter, and the horizontal axis shows Tefp, Tslp,
The pulse positions of Tsfp and Telp are plotted with S / N on the vertical axis, and Jow10, Jow10K, J at each position are shown in the figure.
The measured values of ow10CT are plotted.

From this figure, Tefp is 32 ns, Tslp
Is 0 ns, Tsfp is 2 ns, and Telp is 15 ns. The optimum pulse position is obtained (high S / N).

In order to confirm the tendency of the experimental factors, an experiment was conducted in which only one factor was changed. The tendency of Tefp was investigated. T
For the parameters other than efp, the level having the highest S / N was selected, and Tefp was set to 25 ns and 32 ns. Two strategies were constructed and jitter was measured.
Jitter 9.0%, 25n when Tefp is 32ns
At the time of s, 9.26% was obtained.

On the other hand, from the result of the experimental design method L18, Te
The difference in S / N between when fp is 32 ns and when fp is 25 ns is 0.4 db, which is 0.6% when converted to the difference in jitter by the above equation (1). These agree with the measured values. As a result, for Tefp, a result reflecting the tendency of the experimental design method L18 was obtained.

In the present invention, the effect is greatest when a phase change type optical information recording medium is used, but the present invention is not limited to this. For example, a magneto-optical information recording medium or a hole forming information recording medium. It is also applicable to other optical information recording media.

[0037]

In the present invention, first, the pulse position of Tefp (first pulse laser irradiation start position) is arbitrarily selected. This is an independent parameter. Next, by optimizing only at least two parameters of Tsfp (first pulse laser irradiation start position) and Tslp (last pulse laser irradiation start position) or Telp (last pulse laser irradiation end position), Excellent jitter characteristics can be obtained.

As described above, according to the present invention, it is possible to provide a recording method, a recording device, and an optical information recording medium for an optical information recording medium in which the optimum pulse can be easily determined and which can be performed in a short time.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a recording waveform (recording strategy) according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing the dependence of each pulse position on the total jitter.

FIG. 3 is a partially enlarged cross-sectional view of a phase change type optical information recording medium according to an embodiment of the present invention.

FIG. 4 is a waveform chart showing an example of a conventionally proposed information recording method.

[Explanation of symbols]

1,1 'transparent substrate 2,2 'dielectric layer 3,3 'reflectance adjusting layer 4,4 'interface layer 5,5 'recording layer 6,6 'interface layer 7,7 'middle layer 8,8 'absorption rate correction layer 9,9 'reflective layer 10,10 'absorption coefficient correction layer 11,11 'protective layer 12 Adhesive layer Laser irradiation start position of Tefp first pulse Laser irradiation end position of Tsfp first pulse Laser irradiation start position of Tslp last pulse Laser irradiation end position of Telp last pulse

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Rejin Tamura             Hitachima, 1-88, Torora, Ibaraki City, Osaka Prefecture             Within Kucsel Co., Ltd. F-term (reference) 5D090 AA01 BB05 CC01 DD03 EE01                       HH01 KK02 KK20

Claims (6)

[Claims] 1. A recording method of an optical information recording medium for recording information by irradiating a recording layer of the optical information recording medium with a laser beam, wherein at least one long pulse is recorded when recording the longest mark. Optimal recording is performed by sequentially irradiating the multi-pulse and the last pulse, and changing four parameters of the laser irradiation start position and the laser irradiation end position of the first pulse, the laser irradiation start position and the laser irradiation end position of the last pulse. When determining the waveform, the optimum recording waveform is determined by changing only at least two parameters of the laser irradiation start position of the first pulse and the laser irradiation start position or the laser irradiation end position of the last pulse among the four parameters. A recording method for a characteristic optical information recording medium. 2. The recording method for an optical information recording medium according to claim 1, wherein the optical information recording medium is a phase change type optical information recording medium. 3. A recording device for an optical information recording medium, which records information by irradiating a recording layer of the optical information recording medium with a laser beam, when recording at least the longest mark, one fast pulse, one or more pulses. Optimal recording is performed by sequentially irradiating the multi-pulse and the last pulse, and changing four parameters of the laser irradiation start position and the laser irradiation end position of the first pulse, the laser irradiation start position and the laser irradiation end position of the last pulse. When obtaining the waveform, the optimum recording waveform is determined by changing only at least two parameters of the laser irradiation start position of the first pulse and the laser irradiation start position or the laser irradiation end position of the last pulse among the four parameters, and Characterized by deciding and irradiating laser light based on the recording waveform Recording apparatus for an optical information recording medium. 4. The recording apparatus for an optical information recording medium according to claim 3, wherein the optical information recording medium is a phase change type optical information recording medium. 5. An optical information recording medium for recording information by irradiating a recording layer with laser light, wherein at least a longest mark is recorded by one fast pulse, one or more multi-pulses and one last pulse. When the optimum recording waveform is obtained by changing the four parameters of the laser irradiation start position and the irradiation end position of the first pulse, the laser irradiation start position and the laser irradiation end position of the last pulse,
Of the four parameters, the optimum recording waveform is determined by changing only at least two parameters of the laser irradiation start position of the first pulse and the laser irradiation start position or the laser irradiation end position of the last pulse, and the determined recording waveform is determined. An optical information recording medium characterized in that information is recorded by irradiating a laser beam based on the above. 6. The optical information recording medium according to claim 5, wherein the recording layer is a phase change type recording layer.