JP2003228847A - Recording method of phase change optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for determining CW erase power optimum for a phase change optical disk, a direct overwrite method using the power determined by the above method as erase power in recording, and a recording/ reproducing device using the CW erase power. <P>SOLUTION: The CW erase of an HF signal recorded by predetermined recording power is carried out by different power (Pe), then the pit level (I11L) of a remaining 11T signal is measured. Assuming that Pe obtained when d(I11L)/ d(Pe) is maximized is Pe1, Pe obtained when d (I11L)/d(Pe) is minimized is Pe2 and Pe2-Pe1 is ΔPe, Pe satisfying the following relational expression is the optimal CW erase power (Pecw): Pe1+0.05×Pe≤Pe≤Pe2-0.05×ΔPe. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct overwrite method for a phase change optical disc and an information recording / reproducing apparatus.

[0002]

2. Description of the Related Art In direct overwrite of a phase change type optical disk, recording means amorphization of a recording layer,
Erasing is crystallization of the recording layer, the reflected signal intensity of the amorphous recording layer is called the pit level, and the reflected signal intensity of the crystallized recording layer is called the land level. Direct overwrite of a conventional phase change optical disc is performed by a recording power (Pw) determined by a drive based on the γ method described in Orange Book and an erasing power (Pw) multiplied by a constant (ε). Pe). According to this method, when the determined Pw is a value higher than the original optimum value, Pe also increases accordingly. Therefore, direct overwriting is performed with excessive Pe, and amorphization occurs, the land level is lowered, jitter is deteriorated, and durability of the recording film is deteriorated. On the contrary, when the determined Pw is lower than the original optimum value, the Pe becomes lower accordingly. Therefore, the signal recorded before the direct overwrite could not be erased sufficiently and the jitter was deteriorated.

On the other hand, an erasing method called CW (or physical) erase by steady laser irradiation is described in the Orange Book. OPC (optimization of recording power) is accompanied by the optimum recording power (Pwo) obtained by the γ method. The erasing power Peo that can vary depending on the CW erase power (Pecw) is not optimal, and the direct overwrite characteristic is degraded in the CW erased part. Erase is used. Further, a hybrid disc having a ROM portion formed by a stamper as a part thereof is coming into practical use. In the case of this disc, if logical erase is applied, RO
Since it is directly overwritten on the M part, its reproduction becomes impossible.

[0004]

SUMMARY OF THE INVENTION The present invention provides a CW erase power determining method most suitable for a phase change type optical disk, and the direct overwrite characteristic is obtained by using the power determined by the method as an erasing power during recording. It is an object of the present invention to provide a direct overwrite method for a phase-change optical disk that improves and obtains good signal quality, and a recording / reproducing apparatus for a phase-change optical disk that uses the CW erase power determined by the method. . Further, it is another object of the present invention to provide a safe erasing method for a hybrid disc and a repair method in case of erroneous erasing.

[0005]

[Means for Solving the Problems] The above problems are solved in the following 1) to
This is solved by the invention 7) (hereinafter referred to as the present inventions 1 to 7). 1) Remaining 11T after CW erase of HF signal recorded with predetermined recording power with different power (Pe)
Measure the pit level (I11L) of the signal and d (I11L)
The value of Pe that maximizes L) / d (Pe) is Pe1, d (I1
1L) / d (Pe) is the minimum Pe is Pe2, and P
A method for determining a CW erase power of a phase-change optical disk, wherein Pe satisfying the following relational expression (1) is set as an optimum CW erase power (Pecw), where e2-Pe1 is ΔPe. Pe1 + 0.05 × ΔPe ≦ Pe ≦ Pe2−0.05 × ΔPe (1) 2) Remaining 11T after CW erase of the HF signal recorded with a predetermined recording power with different power (Pe)
Signal pit level (I11L) and land level (I1
1H) is measured, and Pe that satisfies the following relational expression (2) is set as the optimum CW erase power (Pecw). I11L / I11H> 0.8 (2) 3) The recording power is higher than the optimum recording power (Pwo) obtained by the γ method, and the CW erase power determination of the phase change type optical disk according to 1) or 2). Method. 4) The method for determining the CW erase power of a phase-change optical disc according to any one of 1) to 3), wherein the linear velocity during CW erase is higher than the maximum recording linear velocity of the disc. 5) A direct overwrite method for a phase-change optical disk, characterized in that the optimum CW erase power (Pecw) determined by the method according to any one of 1) to 4) is used as an erasing power (Peo) during recording. . 6) The erase power (Peo) is fixed and β of the HF signal recorded with different recording power is measured, and the recording power at which β is 0 to 8% is set as the optimum recording power (Pwo). 5) The direct overwrite method for the phase change type optical disk described in 5). 7) RO formed at least in part by a stamper
1) ~ for hybrid discs with M section
A recording / reproducing apparatus for a phase-change type optical disc, comprising a means for performing CW erase with the power obtained by the CW erase power determination method according to any one of 4).

The embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a phase change type information recording / reproducing apparatus. The information recording medium 1 composed of a phase-change type optical disk is rotationally driven by a driving means composed of a spindle motor 2, a light source composed of a semiconductor laser is driven by a laser driving circuit 4 which is a light source driving means, and a recording / reproducing pickup 3 Via an optical system not shown,
By irradiating the information recording medium 1 with a laser beam as an electromagnetic wave from the semiconductor laser light source, a phase change occurs in the recording layer of the information recording medium 1, and the reflected light from the information recording medium 1 is received by the recording / reproducing pickup 3. Then, information is recorded on or reproduced from the information recording medium 1. The waveform processing circuit 6 measures the signal level of the reproduced HF signal,
A calculation for obtaining w and Pwo is performed. The optimum recording power of the recording / reproducing pickup 3 is set by a recording power setting circuit / erasing power setting circuit 5 as recording power setting means.

The recording / reproducing apparatus for the information recording medium 1 causes the recording layer of the information recording medium 1 to undergo a phase change by irradiating the information recording medium 1 with a laser beam as an electromagnetic wave by the recording / reproducing pickup 3. A phase-change type information recording / reproducing apparatus capable of recording / reproducing information on / from the medium 1 and rewriting the information, wherein a signal to be recorded is modulated by a modulator and recorded on the information recording medium 1 by a recording / reproducing pickup 3. The recording means for recording is provided. The recording means including this pickup records information on the recording layer of the information recording medium 1 by a so-called PWM recording method in which a signal is recorded as a mark width. At the time of recording, the signal to be recorded is modulated by the modulator using the clock. The modulation method is, for example, EFM (Eight-to-Fourteen) suitable for recording information on a rewritable compact disc.
-Modulation) modulation method or an improved modulation method thereof.

The basic structure of the phase change type optical disk has a first dielectric layer, a recording layer, a second dielectric layer, a metal or alloy layer, and an overcoat layer on a substrate having a guide groove. Further preferably, a printing layer on the overcoat layer,
It has a hard coat layer on the mirror surface of the substrate. The substrate material is usually glass, ceramics, or resin, and a resin substrate is preferable in terms of moldability and cost. Examples of the resin include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, urethane resin, and the like. A polycarbonate resin and an acrylic resin, which are excellent in terms of moldability, optical characteristics and cost, are preferable.
Further, the substrate may have a disk shape, a card shape, or a sheet shape. However, the phase-change type optical disk of the present invention is a rewritable compact disk (CD-
When applied to RW), it is desirable that the following specific conditions be given. The condition is that the width of the guide groove (groove) formed on the substrate to be used is 0.25 to 0.25.
0.65 μm, preferably 0.30 to 0.60 μm, the depth of the guide groove is 150 to 550 Å, preferably 200 to 450
That is Å.

As the quality of the optical disk used in the present invention, especially the phase change type optical disk, not only recording and erasing but also the reproduction stability of the signal and the life of the signal are required at the same time. In order to satisfy these requirements comprehensively and to set the recrystallization linear velocity to 5.0 to 10.0 m / s, at least the material of the recording layer is mainly AgαInβSbγTeδ (α,
β, γ, and δ consist of atomic% and α + β + γ + δ = 100), and it was necessary that α, β, γ, and δ satisfy the following requirements. 0 <α ≦ 10 2 ≦ β ≦ 12 55 ≦ γ ≦ 70 22 ≦ δ ≦ 32 When Ag exceeds 10 atomic%, In exceeds 12 atomic%, and Sb exceeds 70 atomic%, signal reproduction is performed. The stability and signal life were insufficient. Since the content of Te has a great influence on the recrystallization linear velocity, it is necessary to set it to 22 to 32 atomic% even if it is controlled by the film thickness of the recording layer and the thermal conductivity of other layers.

As a method for improving the reproduction stability of the signal and the life of the signal, the deterioration of the reproduction of the signal and the decrease of the life of the signal are caused by the crystallization of the amorphous marks. It was effective to add at least one element selected from 3B group, 4B group, and 5B group. Although this mechanism is not clear, these additional elements are
It is considered that the crystallization of the amorphous mark is suppressed by entering a spatial gap of gInSbTe or forming a chemical bond. Therefore, the atomic radius is small or Ag
An element that has a large chemical bond with InSbTe or has a large number of chemical bonds is effective. Especially B, C, N, S
i, Ge, and Sn are effective. The effective amount of these additional elements is 5 atomic% or less of the recording layer. If it exceeds 5 atomic%, the recording and erasing characteristics originally possessed by the AgInSbTe recording layer are affected, and the unerased portion remains.

The thickness of the recording layer is preferably 10 to 50 nm, preferably 12 to 30 nm. Considering initial characteristics such as jitter, overwrite characteristics and mass production efficiency,
More preferably, it is 14 to 25 nm. When the thickness is less than 10 nm, the light absorption ability is remarkably lowered, and it cannot serve as a recording layer. If it is thicker than 50 nm, it is difficult for a uniform phase change to occur at high speed. Such a recording layer is formed by various vapor deposition methods such as vacuum deposition method, sputtering method, plasma CVD method, photo CVD method, ion plating method,
It can be formed by an electron beam evaporation method or the like. Among them, the sputtering method is excellent in mass productivity and film quality.

As materials for the first dielectric layer and the second dielectric layer
For SiO, SiO_Two, ZnO, SnO_Two, Al_TwoO
_Three, TiO_Two, In_TwoO_Three, MgO, ZrO_TwoSuch as gold
Group oxide; Si_ThreeN_Four, AlN, TiN, BN, ZrN
Such as nitrides; ZnS, In _TwoS_Three, TaS_FourSulfur
Compounds: SiC, TaC, B_FourC, WC, TiC, ZrC
Carbides such as and diamond-like carbon, or those
A mixture of Each of these materials is a protective layer.
However, they may be mixed with each other, and
Impurities may be included if necessary. Furthermore, if necessary
The dielectric layers can be multi-layered. However, the first dielectric
The melting points of the layer and the second dielectric layer must be higher than that of the recording layer.
It is important. Such first dielectric layer and second dielectric layer
Are various vapor phase growth methods such as vacuum deposition method and sputter phosphorus.
Method, plasma CVD method, photo CVD method, ion plate
It can be formed by a coating method, an electron beam evaporation method, or the like.
Above all, the sputtering method is superior in mass productivity and film quality.
There is.

The thickness of the first dielectric layer has a great influence on the reflectance at 650 nm which is the reproduction wavelength of DVD. 780n
In order to satisfy the reflectance of 0.15 to 0.25 which is the standard of CD-RW at the reproducing wavelength of m and 650 nm, the first dielectric layer is required to have a thickness of 65 to 130 nm. Second
The thickness of the dielectric layer is 15 to 45 nm, preferably 2
The thickness is preferably 0 to 40 nm. When the thickness is less than 15 nm, the function as the heat resistant protective layer is not fulfilled and the sensitivity is lowered. On the other hand, when the thickness is more than 45 nm, interfacial peeling is likely to occur and the repetitive recording performance is also deteriorated.

As the alloy or metal layer (reflection heat dissipation layer),
A metal material such as Al, Au, Ag, Cu, Ta, or an alloy thereof can be used. Further, Cr, Ti, Si, Cu, Ag, Pd, Ta and the like are used as the additive element. Such a reflective heat dissipation layer can be formed by various vapor deposition methods such as vacuum deposition method, sputtering method, plasma CVD method, photo CVD method, ion plating method and electron beam evaporation method. The thickness of the alloy or metal layer is 70 to 200 nm, preferably 100 to 200 nm.
It is preferably 160 nm.

It is desirable to have an overcoat layer on the alloy or metal layer as an antioxidation agent. As the overcoat layer, a UV curable resin produced by spin coating is generally used, and its thickness is suitably 5 to 15 μm. When the thickness is less than 5 μm, an increase in error may be observed when the printing layer is provided on the overcoat layer. On the other hand, when the thickness exceeds 15 μm, the internal stress increases, which greatly affects the mechanical properties of the disk. As the hard coat layer, an ultraviolet curable resin produced by spin coating is generally used, and the thickness thereof is 2 to 6 μm.
m is suitable. If it is less than 2 μm, sufficient scratch resistance cannot be obtained. If it exceeds 6 μm, the internal stress becomes large and the mechanical properties of the disk are greatly affected.
The hardness must be H or more, which is a pencil hardness that does not cause a large scratch even if it is rubbed with a cloth. In addition, it is also effective to mix a conductive material as necessary to prevent electrostatic charge and prevent adhesion of dust and the like.

FIG. 2 shows P when a signal is recorded on the initialized phase change type optical disc having the above-mentioned structure and CW erase is performed.
e and the land level (I11H) of 11T of the residual signal,
Pit level (I11L) and d (I11L) / d
The relationship with (Pe) is shown. As you can see from the figure, d (I1
CW erase power (Pe1) that maximizes 1L) / d (Pe) is 6.0mW, d (I11L) / d (Pe)
CW erase power (Pe2) is 10.2
mW, and Pe2-Pe1 (ΔPe) is 4.2 mW. Here, the optimum CW erase power (Pecw)
Is a power with a small residual signal amplitude and a small decrease in reflectance. In the case of this phase change type optical disc, Pecw is 6.2 to 10.0 mW.

In order to measure the residual signal amplitude, if the HF signal previously recorded on the disk is recorded with a recording power higher than the optimum recording power (Pwo) obtained by the γ method so as to easily remain, the signal amplitude becomes large. Pe that can be sufficiently erased even with signals
cw is obtained. From the above result, the following relational expression is obtained (in terms of significant figures, if the second place below the decimal point is rounded off, it will be in agreement with the numerical value of 6.2 to 10.0 mW in the above description). Pe1 + 0.05 × ΔPe ≦ Pecw ≦ Pe2-0.0
From the viewpoint of the utilization efficiency of 5 × ΔPe LD (laser diode), Pecw
Is preferably as small as possible, and in the case of this phase change type optical disc, Pecw is 6.2 mW. Further, at this erase power, I11L and I11H have the following relationship. I11L / I11H> 0.8

In the case of CW erase, erasing can be performed at a higher linear velocity than direct overwriting in which marks must be formed simultaneously with erasing, and erasing can be performed at a higher speed than logical erasing. Next, FIG. 3 shows the relationship between β and Pw when a signal is recorded at Pe = Pecw = 6.2 mW on this phase change type optical disc. As can be seen from the figure, when Pe is fixed, β and Pw have a linear correlation and linear approximation is possible. β is the mark length of the EFM signal
It represents the balance of the pit length, and when the value is in the range of 0 to 8%, few errors occur. From Figure 3, Pw is about 1
It can be seen that at 2.3 mW, β = 4% with the best balance can be obtained as the EFM signal.

FIG. 4 and FIG. 5 show the case where the direct overwrite is repeated at Pe = 6.2 mW for this phase change type optical disk, and the conventional Pe = ε × Pw (ε =
The power margin of the error when the direct overwrite is repeated at 0.5) is shown. It should be noted that FIG. 4 shows data when the direct overwrite is performed twice, and FIG. 5 shows data when the direct overwrite is performed 1000 times. As can be seen from FIGS. 4 and 5, Pe
= 6.2 mW, the power margin of the direct overwrite characteristic is significantly improved. That is, in practical use,
To perform more reliable recording, the erasing power (P
It is advantageous to fix eo). Further, in the case of a hybrid disc having a ROM part formed by a stamper in a part thereof, if the logical erase is applied, the ROM part is directly overwritten. Then, the ROM portion formed by the stamper is not erased and the logical erase pattern is overwritten, which makes the reproduction impossible. Even a hybrid disc that is erroneously erased in this way can be restored by erasing only the logical erase pattern overwritten in the ROM section by CW erase.

[0020]

According to the present inventions 1 and 2, an optimum CW erase power that does not cause unerased residue due to low erase power or amorphization of a recording film due to high erase power can be obtained.
According to the third aspect of the present invention, the CW erase power can be determined under the condition that it is difficult to erase, so that the accuracy of the obtained CW erase power is increased. According to the fourth aspect of the present invention, the CW erase power at a linear velocity higher than the logical erase with the maximum recording linear velocity being the upper limit can be determined, so the work time spent for erasing can be shortened by the logical erase at a high linear velocity. According to the fifth aspect of the invention, since recording is performed with the optimum erasing power regardless of the recording power, it is possible to perform recording with a wide recording power margin. According to the sixth aspect of the present invention, since the optimum recording power when the erasing power is fixed can be determined by using the signal balance as a parameter, recording with good signal quality can be performed. According to the present invention 7, it is possible to obtain a recording / reproducing apparatus capable of safely erasing a hybrid disc by optimal CW erase.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an information recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a residual signal level and erasing power.

FIG. 3 is a diagram showing a relationship between β and an error and recording power.

FIG. 4 is a diagram showing a relationship between an error and a recording power when direct overwrite is performed twice.

FIG. 5 is a diagram showing a relationship between an error and a recording power in the case of 1000 times of direct overwrite.

[Explanation of symbols]

1 Information recording medium 2 spindle motor 3 pickups 4 Laser drive circuit 5 Recording power setting circuit / Erase power setting circuit 6 Waveform processing circuit

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5D090 AA01 AA03 AA07 BB02 BB05                       BB11 CC02 CC11 EE01 EE06                       FF09 KK03 KK20                 5D119 AA23 AA26 AA31 BA01 BA02                       BA05 BB01 BB04 DA02 DA08                       HA17 HA19 HA27 HA52                 5D789 AA23 AA26 AA31 BA01 BA02                       BA05 BB01 BB04 DA02 DA08                       HA17 HA19 HA27 HA52

Claims (7)

[Claims] 1. A pit signal (I11L) of the remaining 11T signal is measured after CW erase of an HF signal recorded at a predetermined recording power with different power (Pe), and d
Pe1 that maximizes (I11L) / d (Pe) is Pe1,
Pe2 is Pe2 that minimizes d (I11L) / d (Pe).
And Pe2-Pe1 is ΔPe, Pe satisfying the following relational expression (1) is the optimum CW erase power (Pe).
cw) of the phase-change optical disk characterized by
How to determine W erase power. Pe1 + 0.05 × ΔPe ≦ Pe ≦ Pe2−0.05 × ΔPe (1) 2. The pit level (I11L) and the land level (I11H) of the remaining 11T signal are measured after CW erase of the HF signal recorded at a predetermined recording power with different powers (Pe), and the following relations are measured. A method for determining a CW erase power of a phase-change optical disk, characterized in that Pe that satisfies Expression (2) is set as an optimum CW erase power (Pecw). I11L / I11H> 0.8 (2) 3. The method for determining CW erase power of a phase change optical disk according to claim 1, wherein the recording power is higher than the optimum recording power (Pwo) obtained by the γ method. 4. The method for determining the CW erase power of a phase-change type optical disk according to claim 1, wherein the linear velocity during CW erase is higher than the maximum recording linear velocity of the disc. 5. The direct of a phase change optical disk, wherein the optimum CW erase power (Pecw) determined by the method according to claim 1 is used as an erasing power (Peo) during recording. Overwrite method. 6. The erasing power (Peo) is fixed and β of HF signals recorded with different recording powers is measured, and β is 0.
6. The direct overwrite method for a phase-change optical disk according to claim 5, wherein the recording power of .about.8% is set to the optimum recording power (Pwo). 7. A hybrid disc having a ROM portion formed at least in part by a stamper,
A recording / reproducing apparatus for a phase-change optical disk, comprising means for performing CW erase with the power obtained by the CW erase power determining method according to claim 1.