JP4299216B2 - Phase change optical recording medium and optimum recording power prediction method for high-speed recording - Google Patents

Description

  The present invention relates to a phase-change optical recording medium that records and reproduces information by causing optical changes in a recording layer material by irradiating a light beam, and is rewritable and compatible with high linear velocity recording. (DVD + RW optical disc that has the same capacity as a DVD-ROM and can be recorded at a scanning speed of 8 times or more the reproduction speed of 3.49 m / s), test recording is performed in a predetermined area of the lead-in zone of the optical recording medium The present invention relates to a method for predicting the optimum recording power during high linear velocity recording, and a phase change optical recording medium suitable for this method.

Patent Document 1 discloses a γ method that is widely used as a method for obtaining the optimum recording power, but this technique is for determining the optimum recording power at a desired recording speed. There is no description about a method for predicting the optimum recording power in the high speed recording.
In Patent Document 2, recording is performed by changing the recording power stepwise at two or more different recording linear velocities, reproducing the recording, measuring the signal amplitude at each recording power, and different recording linear velocities. Discloses a method for determining an optimum recording power at a recording linear velocity faster than that at the time of test recording (trial writing) by obtaining a linear approximation formula of the recording power with respect to the linear velocity for the recording power having the same signal amplitude. However, the present invention relates to a method for predicting the optimum recording power at a high recording linear velocity from two or more types of recording linear velocities, and is different from the present invention. In addition, it takes time for test recording and reading, and there is a problem that it takes time when the user uses the optical disc.

In Patent Document 3, when the optical disk is divided into a plurality of recording areas in the radial direction according to the amount of data to be recorded using the CAV rotation method, the recording portion at the end of each recording area is reproduced. Based on the result, the recording power of the next recording area is calculated and corrected while correcting the approximate expression, so that recording of uniform characteristics over the entire surface of the optical disk medium is possible regardless of the interruption or resumption of the recording operation. In other words, an invention for determining an optimum recording power according to a recording linear velocity proportional to the radial direction is disclosed. However, the method is different from the present invention in which the optimum recording power at the high recording linear velocity is predicted only from the test recording in the predetermined area on the innermost circumference of the optical recording medium.
In Patent Document 4, test recording is performed on a PCA area of an optical disc at a predetermined basic linear velocity, and an optimum recording power at the basic linear velocity is determined based on the result, and recording is performed at a linear velocity different from the basic linear velocity. An invention of a method for determining a recording power based on a result obtained by performing a predetermined calculation on an optimum recording power at a basic linear velocity is disclosed, whereby high-quality recording can be performed even in a high-speed region. There is a description. However, the present invention relates to an information recording method, and there is no description about a method for newly describing physical format information in a lead-in zone of an optical recording medium and predicting an optimum recording power at a high recording linear velocity.
The technique disclosed in Patent Document 5 is similar to the present invention in that an optimum recording power determination method using the γ method is used. However, it is possible to perform repetitive recording at a scanning speed of 8 times or more that of a DVD-ROM. There is no description regarding a method for predicting the optimum recording power at a high linear velocity, which is not intended for an optical recording medium.

Japanese Patent No. 3124721 JP 2003-91824 A JP 2002-208139 A JP 2004-30919 A JP 2003-67925 A

At present, there are many optical recording apparatuses capable of recording information by the CAV rotation method in which the rotational speed is constant at any radial position of the optical recording medium, and many optical recording media used therefor. The reason why the CAV rotation method is widely used is that it has an advantage of reducing the power consumption of the optical recording apparatus. Since there is no need to change the rotational speed of the motor for each radial position of the disc, power for changing the rotational speed is not required, and when the optical recording device searches for content recorded on the optical recording medium. There is no need to change the motor speed. Therefore, the search operation can be performed in a short time because there is no time lag compared to the CLV rotation method in which the linear velocity is constant at any radial position.
OPC (Optimum Power Control), which determines the optimum recording power by performing test recording (trial writing) by changing (changing) the recording power to a predetermined area of the disc by this CAV rotation method, and determining the optimum recording power. ) Is used in optical disk drives. The method used to determine the optimum recording power is to use the asymmetry of the signal obtained from the test recording to determine the recording power, or to use the modulation curve and gamma curve of the signal obtained from the test recording to determine the recording power. There are methods to use.

Of these methods, the present invention utilizes the γ method widely used for determining the optimum recording power in a phase change optical recording medium. The γ method is a method of using a gamma curve calculated from a modulation degree curve of a recording mark for determining recording power. Test recording of this method is performed in a power calibration area (PCA) in an area called a lead-in zone of the optical disk (radial position from the center of the disk is approximately 23 mm).
A rewritable DVD + RW phase change optical recording medium that can be recorded at a scanning speed of 1 to 4 times the speed currently on the market is subjected to OPC at a rotational speed corresponding to the scanning speed to be recorded. For example, the rotational speed at 1 × speed is about 1500 rpm, and the rotational speed at 4 × speed is about 6000 rpm, and there is room for the allowable rotational speed of the spindle motor. However, when developing a DVD + RW phase change optical recording medium that can record even at a scanning speed of 8X or higher, if the OPC is performed by the CAV rotation method, the rotation speed of the spindle motor corresponding to the linear speed to be recorded is close to the limit. Therefore, the optical recording medium cannot be rotated at a higher rotational speed. For example, if the recording linear velocity at the innermost circumference is set to 6 times speed (about 20.9 m / s), the rotational speed becomes about 9000 rpm, the rotational speed approaches the allowable limit, and the recording linear velocity at the innermost circumference. Becomes 8 × speed (about 27.9 m / s), the rotational speed becomes about 12000 rpm, and the rotational speed greatly exceeds 10,000 rpm. That is, when performing test recording with PCA, an allowable range is up to a scanning speed corresponding to 6 times the reproduction speed of the DVD-ROM.
Accordingly, the present invention provides a rewritable phase change type optical recording medium having the same capacity (4.7 GB) as that of a DVD-ROM and capable of recording even at a scanning speed of 8 times or more of a reproduction speed of 3.49 m / s. A method for predicting an optimum recording power Ppo (V0) corresponding to a recording linear velocity V0 (21 m / s ≦ V0 ≦ 42 m / s) higher than 6 × speed from an OPC result at a velocity V equal to or lower than the double velocity, and this An object of the present invention is to provide a phase change optical recording medium suitable for the method.

The above problems are solved by the following inventions 1) to 5 ) (hereinafter referred to as the present inventions 1 to 5 ).
1) Test recording was performed in a linear velocity range slower than the recording linear velocity actually used for recording in a predetermined area of the lead-in zone of the phase change optical recording medium having a recordable linear velocity range of 21 to 42 m / s. From this result, the optimum recording power Ppo (V0) at the high recording linear velocity V0 is predicted, and the EFM + modulation method is adopted as the modulation method for recording the mark in the test recording, and the shortest mark length (3T). Is set to 0.38 to 0.42 μm, and a pulse condition for recording a mark is a 2T cycle strategy [one pulse when recording a 3T mark, and a (3 + N) T mark (N is a natural number) is recorded. In this case, a recording strategy in which one pulse is added every time N increases by 2), and one type of recording linear velocity V (where V0 / Test recording is performed while changing the recording power Pp at 2 ≦ V <V0) , and the modulation curve m (Pp, V) is adopted as test data obtained by reproducing the recorded information. ) To (iii) for prediction , an optimum recording power prediction method at a high recording linear velocity of a phase change optical recording medium.
(I) Using a modulation degree curve m (Pp, V) and a coefficient arithmetic expression A [Pp] preformatted in the lead-in zone of the phase change optical recording medium, A modulation degree curve m (Pp0, V0) is predicted.
m (Pp0, V0) = m (Pp × A [Pp], V)
(Ii) P _target (V0) is predicted using the modulation degree curve m (Pp0, V0) and the Modulation _target preformatted in the lead-in zone of the phase change optical recording medium .
(Iii) The optimum recording power Ppo (V0) is predicted using P _target (V0) and ρ (V0) preformatted in the lead-in zone of the phase change optical recording medium.
2) Test recording was performed in a linear velocity range slower than the recording linear velocity actually used for recording in a predetermined area of the lead-in zone of the phase change optical recording medium having a recordable linear velocity range of 21 to 42 m / s. From this result, the optimum recording power Ppo (V0) at the high recording linear velocity V0 is predicted, and the EFM + modulation method is adopted as the modulation method for recording the mark in the test recording, and the shortest mark length (3T). Is set to 0.38 to 0.42 μm, and a pulse condition for recording a mark is a 2T cycle strategy [one pulse when recording a 3T mark, and a (3 + N) T mark (N is a natural number) is recorded. In this case, a recording strategy in which one pulse is added every time N increases by 2), and one type of recording linear velocity V (where V0 / Gamma calculated from the modulation curve m (Pp, V) as the test data obtained by performing test recording while changing the recording power Pp at 2 ≦ V <V0) and reproducing the recorded information by the following equation: A method for predicting optimum recording power at a high recording linear velocity of a phase change optical recording medium, wherein a curve γ (Pp, V) is employed and prediction is performed by the following procedures (i) to (iii) .
γ (Pp, V) = [dm (Pp, V) / dPp] × [Pp / m (Pp, V)]
(I) using gamma curve gamma (Pp, V) and the phase-change optical recording medium of the read coefficient calculation formula B which is pre-formatted in zone [Pp], gamma in the high-speed recording linear velocity V0 by the following formula A curve γ (Pp0, V0) is predicted.
γ (Pp0, V0) = γ (Pp × B [Pp], V)
(Ii) P _target (V0) is predicted using the gamma curve γ (Pp0, V0) and γ _target preformatted in the lead-in zone of the phase change optical recording medium.
(Iii) The optimum recording power Ppo (V0) is predicted using P _target (V0) and ρ (V0) preformatted in the lead-in zone of the phase change optical recording medium.
3 ) It has at least a transparent substrate and a recording layer, the recordable linear velocity range is 21 to 42 m / s, and P _IND , Modulation _target or γ _target ρ (V0) at a plurality of recording linear velocities in the lead-in zone And the coefficient calculation formula A [Pp] or B [Pp] are preformatted, and the phase-change optical recording medium to which the optimum recording power prediction method described in 1) or 2) can be applied .
4 ) The recording layer is made of a phase change material containing at least three elements of Ga, Sb, and Sn. Information is recorded by forming an amorphous material, and information is erased by forming a crystalline material. 3. The phase change optical recording medium according to 3) , wherein the recording can be repeated by alternately repeating the quality and the crystalline.
5 ) The phase according to 3) or 4) , wherein the transparent substrate has meandering grooves having a track pitch of 0.74 ± 0.03 μm, a groove depth of 22 to 40 nm, and a groove width of 0.2 to 0.3 μm. Changeable optical recording medium.

Hereinafter, the present invention will be described in detail.
According to the first aspect of the present invention, by performing test recording at a single recording linear velocity V in a predetermined area of the lead-in zone of the medium, it is possible to predict the optimum recording power at a high recording linear velocity of the target DVD 8 × or higher. It becomes possible. By multiplying the test data obtained by the test recording by a coefficient arithmetic expression preformatted in the lead-in zone of the medium, the test data at the high recording linear velocity V0 can be predicted. Thereafter, the method for determining the optimum recording power by the conventional γ method described above may be followed. Since test recording at one type of recording linear velocity V is sufficient, test recording and reading time can be minimized, and time can be prevented from being consumed by the user when using the optical disc.

  The reason why the 2T cycle strategy is adopted is that the recording linear velocity has been greatly increased. The conventional recording method for the phase change type optical recording medium compatible with DVD 1 to 4 times speed is a method in which one set of heating irradiation pulse and cooling irradiation pulse is repeated every clock cycle since the scanning linear velocity of the medium is slow ( 1T cycle strategy). In this recording method, when recording an amorphous mark having a length nT (n: a natural number of 3 or more), (n-1) heating irradiation pulses and cooling irradiation pulses are alternately irradiated. However, as the recording linear velocity is improved, the clock cycle is shortened. Therefore, when the heating irradiation pulse and one set of cooling pulse are performed in the 1T cycle as in the conventional case, sufficient cooling time cannot be obtained. In other words, even if an amorphous mark is formed by irradiation with a certain heating pulse and cooling pulse, the amorphous mark once formed is recrystallized due to the residual heat generated from the heating pulse after the next 1T cycle. In particular, there is a problem that a long mark becomes thin and it is difficult to obtain a modulation degree. In order to solve such a problem, it is essential to take as long a cooling pulse irradiation time as possible. Therefore, in high-speed recording exceeding 4 × speed, a thick and uniform amorphous mark can be formed by employing a recording method in which one set of heating irradiation pulse and cooling irradiation pulse is repeated every two clock cycles. And a high degree of modulation can be ensured. In this recording method, when recording an amorphous mark having a length of nT, assuming that the number of heating irradiation pulses is m (m: a natural number of 1 or more), n = 2m + 1 when n is an odd number, and n is When the number is even, n = 2m (n: a natural number of 3 or more). Considering the clock cycle and the time width of the heating and cooling irradiation pulses, the usable upper limit linear velocity of the 2T cycle strategy can be said to be up to about 12 × (41.9 m / s).

In order to obtain the optimum recording power Ppo (V0) at the high-speed recording linear velocity V0, it is necessary to predict P _target (V0) at the high-speed recording linear velocity V0. In order to predict P _target (V0), the modulation degree curve m (Pp0, V0) at the high recording linear velocity V0 must be predicted. Thus, the modulation curves m (Pp, V) as in the present invention 1 as the test data is good to use. From this modulation degree curve, m (Pp0, V0) can be derived. Here, P _target (V0) is a recording power at a high-speed recording linear velocity V0 corresponding to a preformatted γ _target . It is a power value for obtaining Ppo (V0) to the last, not a power value actually used for information recording.
As the method, one obtained from the test recording at a recording linear velocity V modulation curve m and (Pp, V), a function of Pp have preformatted the lead-in zone of the phase-change optical recording medium It is preferable to obtain from the following formula using a certain coefficient calculation formula A [Pp].
m (Pp0, V0) = m (Pp × A [Pp], V)
That is, the modulation degree curve m (Pp0) at the high recording linear velocity V0 is moved by moving the modulation degree curve m (Pp, V) at the recording linear velocity V by multiplying by the coefficient A [Pp] in the recording power Pp direction. , V0). A [Pp] may be a constant function or a complex function as long as it is a function specific to the optical recording medium used at that time. Thus, if the value of Modulation _target determined in advance using the concept of the conventional γ method is used, the P _target at the high recording linear velocity V 0 can be obtained from the modulation degree data without calculating the gamma curve. = P _target (V0)] can be predicted . Then, the optimum recording power Ppo (V0) at the high-speed recording linear velocity V0 is obtained from the equation of Ppo (V0) = ρ (V0) × P _target (V0) using a predetermined ρ (V0). it is possible.

Further, as in the present invention 2 , in order to predict P _target (V 0) at the high recording linear velocity V 0, it is calculated from the modulation degree curve m (Pp, V) obtained from the test recording at the recording linear velocity V. Gamma curve γ (Pp, V) = [dm (Pp, V) / dPp] × [Pp / m (Pp, V)] is predicted from the gamma curve γ (Pp0, V0) at the high recording linear velocity V0. You may do it.
As the method, the lead-in zone of one of the recording linear velocity modulation curve obtained from test recording at V m (Pp, V) and γ is calculated from (Pp, V), phase-change optical recording medium It is preferable to obtain from the following equation using the coefficient calculation equation B [Pp], which is a function of Pp preformatted to:
γ (Pp0, V0) = γ (Pp × B [Pp], V)
That is, the gamma curve γ (Pp0, V0) at the high recording linear velocity V0 is predicted by moving the gamma curve at the recording linear velocity V by multiplying the coefficient B [Pp] in the recording power Pp direction. B [Pp] may be a constant function or a complex function as long as it is a function specific to the optical recording medium used at that time. As a result, in the same way as the concept of the conventional γ method, it is possible to predict P _target [= P _target (V0)] at a high recording linear velocity V0 by using a predetermined value of γ _target. Become . Then, as in the case of the present invention 1, using [rho (V0) that is predetermined, from the equation Ppo (V0) = ρ (V0 ) × P target (V0), the high-speed recording linear velocity V0 The optimum recording power Ppo (V0) can be obtained .
FIG. 1 is a flowchart until the optimum recording power Ppo at a certain recording linear velocity is obtained, and FIG. 2 predicts the optimum recording power Ppo (V0) at a high recording linear velocity V0 by the method of the present invention. It is a flowchart until it does.

The present invention 3 provides physical format information necessary for determining the optimum recording power using the conventional γ method in the lead-in zone of the medium, that is, P _IND , Modulation _target or γ _target at a plurality of recording linear velocities. , Ρ (V0), and a coefficient arithmetic expression A [Pp] or B [Pp] that can apply the present invention 1 or 2 is preformatted. Thereby, it is possible to provide a phase change optical recording medium capable of obtaining an optimum recording power at a high recording linear velocity by the method of the present invention 1 or 2 . P _IND is an estimated value for determining P _{target in the} recording apparatus, and is a value used as an initial value for performing trial writing in a certain power range before and after P _IND . Modulation _target or γ _target ρ (V0) is a value determined in advance by the media manufacturer. After obtaining the modulation curve or gamma curve as the test data, _{Modulation target} or γ corresponding to the _{target P target} is uniquely determined. [rho (V0) is a value used to determine the optimum recording power Ppo, is defined as _{ρ (V0) = Ppo / P} target (V0).

Further, by the coefficient computing expressions A [Pp] or B [Pp] be pli format, provides a phase-change optical recording medium capable of predicting the optimum recording power Ppo (V0) at high speed recording linear velocity it can.
In the conventional 1 to 4 times speed DVD + RW, since it is sufficient to perform OPC at the linear speed to be recorded, physical format information such as A [Pp] and B [Pp] is not necessary. However, in developing a rewritable DVD + RW optical recording medium capable of recording even at a scanning speed of 8 × or more of the reproduction speed of DVD-ROM 3.49 m / s, OPC at a high recording linear velocity V0 is difficult. Therefore, it is necessary to add new physical format information to the lead-in zone of the optical recording medium.
As shown in FIG. 2, in order to predict the optimum recording power Ppo (V0) from the modulation degree curve, the coefficient arithmetic expression A [Pp] is required as physical format information, and the optimum recording power Ppo is derived from the gamma curve. In order to predict (V0), a coefficient arithmetic expression B [Pp] is required as physical format information. Accordingly, at least one of these pieces of information needs to be preformatted in the lead-in zone of the phase change optical recording medium.

By using the phase change material described in the present invention 4 , it is possible to provide a phase change type optical recording medium capable of repetitive recording at a scanning speed of 8 times or higher speed of DVD-ROM.
The phase change type recording layer material based on AgInSbTe used in conventional 1 to 4 times speed DVD + RW has a low crystallization speed inherent to the material and is not suitable for high speed recording. Therefore, it is amorphous at a recording scanning speed of 8 times or more. The mark cannot be recorded accurately. Accordingly, there is a demand for the discovery of a novel phase change recording layer material that enables recording even at a recording scanning speed of 8 × speed or higher. So far, recording layer materials such as a GaSbSn tri-element system, GaSbSnGe, GaSbSnIn 4-element system, and GaSbSnGeIn 5-element system have been discovered. By changing the composition ratio of these elements, it is possible to provide a crystallization speed that is compatible with high-speed recording. Further, by striking the composition ratio of each element within a range of several percent, it becomes possible to realize a recording layer material that can cope with recording at 8 × speed or higher.
Specific preferred examples of the phase change recording layer material include Ga _11.9 Sb _73.1 Sn _15.0 , Ga ₅ Sb ₇₀ Sn ₁₇ Ge ₈ , Ga ₂ Sb ₇₄ Sn ₁₀ Ge ₉ In _{5 and the} like. The composition ratio is not limited to these, and the optimum recording power prediction method of the present invention can be applied.

By using the substrate described in the present invention 5 , it is possible to provide a DVD + RW optical recording medium having good recording characteristics and signal characteristics at 8 × speed or higher. In a DVD disc having a track pitch of 0.74 ± 0.03 μm, a push-pull signal is mainly extracted as a signal used to detect a tracking error. The push-pull signal can obtain the maximum signal intensity when the groove depth is 55 nm at the laser wavelength of 660 nm used in DVD. In order to adjust the reflectivity low and increase the amplitude of the error signal, the groove depth is preferably deep, but in consideration of recording characteristics, it is preferably in the range of 22 to 40 nm. The groove width is preferably in the range of 0.2 to 0.3 μm in consideration of recording characteristics and signal characteristics.

  According to the present invention, a rewritable phase change optical recording medium having the same capacity (4.7 GB) as a DVD-ROM and capable of recording even at a scanning speed of 8 times or more of a reproduction speed of 3.49 m / s. A method for predicting an optimum recording power Ppo (V0) corresponding to a recording linear velocity V0 (21 m / s ≦ V0 ≦ 42 m / s) higher than 6 × speed from an OPC result at 6 × speed or less, and to this method A suitable phase change optical recording medium can be provided.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited by these Examples.

Example 1
On a transparent substrate having a guide groove with a track pitch of 0.74 μm, a groove depth of 27 nm, and a groove width of 0.27 μm, a lower protective layer made of ZnS—SiO _{2 with a} thickness of 60 nm, and an interface layer made of SiO _{2 with a} thickness of 2 nm , Ga ₅ Sb ₇₀ Sn ₁₇ Ge ₈ (atomic%) with a 16 nm-thickness phase change recording layer, ZnS—SiO _{2 with a} 7 nm-thick upper first protective layer, SiC with a 4 nm-thickness upper second protective layer A protective layer and a reflective layer made of Ag and having a thickness of 140 nm were laminated in this order by a sputtering method to obtain a phase change optical recording medium (disk). Subsequently, it initialized with the initialization apparatus for phase change discs. Initialization uses an optical head with a condensing beam diameter of 75 μm, power of 1500 mW (here, LD power consumption, different from irradiation power), scanning speed of 18.5 m / s, feed of 50 μm / rotation. It was performed by crystallization under conditions.
Recording experiments were performed on the phase change optical recording medium obtained as described above.
Information is recorded on the phase change recording layer by forming a peak power Pp for forming a recording mark by forming an amorphous state, a bottom power Pb for facilitating the formation of an amorphous mark by applying a quenching effect, and forming a crystalline material. This was performed using a 2T periodic recording strategy that was intensity-modulated with three levels of erase power Pe (Pp>Pe> Pb) for erasing information. DTG-5274 manufactured by Nippon Tektronix Co., Ltd. is used as the strategy pulse generator, and the setting resolution is 0.026159 × 16 × v [GHz] when the recording scanning speed v ≦ 27.9 m / s. When the speed v> 27.9 m / s, 0.026159 × 12 × v [GHz]. Since the resolution increases as the recording scanning speed increases and exceeds the resolution specification (3.5 GHz) of DTG-5274, it is necessary to reduce the resolution of the strategy, particularly at v> 27.9 m / s. . The evaluation apparatus used is DDU-1000 manufactured by Pulse Tech Co., Ltd., with NA = 0.65 of the objective lens and laser wavelength λ = 660 nm used for recording / reproduction. The recording power specifications are 40 mW at the maximum for Pp and 18 mW at the maximum for Pe. Further, Pb has a power as small as possible to give a rapid cooling effect, so recording was carried out with fixing at 0.1 mW. The modulation degree curve was calculated by performing test recording 10 times on one track.
FIG. 3 shows the result of test recording performed at a recording linear velocity V = 20.9 m / s. Since the modulation degree curve of the high-speed recording linear velocity V0 = 27.9 m / s cannot be written in the innermost circumference, data for prediction is obtained in the middle circumference area of the optical disc.
According to FIG. 3, V0 is obtained by multiplying the modulation degree curve m (Pp, V = 20.94) at the recording linear velocity V = 20.9 m / s by the coefficient arithmetic expression A [Pp] = 1.11. The modulation degree curve m (Pp0, V0 = 27.9) at = 27.9 m / s can be predicted.

Example 2
The phase change was performed in the same manner as in Example 1 except that the interface layer was eliminated, the recording layer material was changed to Ga ₇ Sb ₆₉ Sn ₁₈ Ge ₆ (atomic%), and the thickness of the upper first protective layer was changed to 5 nm. Type optical recording media were prepared and recording experiments were conducted.
FIG. 4 shows the results of test recording performed at a recording linear velocity V = 20.9 m / s. Since the modulation degree curve of the high-speed recording linear velocity V0 = 27.9 m / s cannot be written in the innermost circumference, data for prediction is obtained in the middle circumference area of the optical disc.
According to FIG. 4, V0 is obtained by multiplying the modulation degree curve m (Pp, V = 20.9) at the recording linear velocity V = 20.9 m / s by the coefficient arithmetic expression A [Pp] = 1.1. The modulation degree curve m (Pp0, V0 = 27.9) at = 27.9 m / s can be predicted.

Example 3
Recording experiments were performed using the same phase change optical recording medium as in Example 2.
FIG. 5 shows the result of test recording performed at a recording linear velocity V = 14 m / s. Since the modulation degree curve of the high-speed recording linear velocity V0 = 27.9 m / s cannot be written in the innermost circumference, data for prediction is obtained in the middle circumference area of the optical disc.
According to FIG. 5, the modulation factor curve m (Pp, V = 14) at the recording linear velocity V = 14 m / s is multiplied by the coefficient arithmetic expression A [Pp] = 0.0003Pp ² −0.024Pp + 1.6159. Thus, the modulation degree curve m (Pp0, V0 = 27.9) at V0 = 27.9 m / s can be predicted.
In this case, since the recording linear velocity V is about half of the high-speed recording linear velocity V0, the predicted curve and the actual high-speed recording linear velocity are 27.9 m / in comparison with the cases of the first and second embodiments. The fitting with the modulation degree curve at s deteriorated.
In the case of the linear velocity condition (predicting the power condition of 27.9 m / s under the condition of 14 m / s) in this embodiment, a good fitting is still obtained, so the power prediction in the actual drive is performed. Even if it is performed, there is no significant effect on the recording characteristics, but the error increases when a linear velocity slower than 14 m / s is used. The tolerance of error is generally estimated that the medium itself is 15% on the minus side from the optimum power and the drive setting error is estimated to be 10%. Therefore, the error range for power prediction should be suppressed to about ± 5%. . If the actual high-speed recording linear velocity is about 27.9 m / s, it is possible to stay within the error range even if it is less than 14 m / s. For example, the high-speed of 42 m / s, which is considered to be the application limit of the 2T period recording strategy. Experiments have confirmed that when the recording linear velocity condition is satisfied, the linear velocity less than 1/2 times may exceed the allowable range of ± 5%. For this reason, the range of the recording linear velocity V used for test recording must satisfy V0 / 2 ≦ V ≦ V0.

Example 4
A phase change optical recording medium was prepared and a recording experiment was conducted in the same manner as in Example 2 except that the material of the phase change recording layer was changed to Ga ₅ Sb ₇₀ Sn ₁₇ Ge ₈ (atomic%).
FIG. 6 shows the result of test recording performed at a recording linear velocity V = 14 m / s. Since the modulation degree curve of the high-speed recording linear velocity V0 = 27.9 m / s cannot be written in the innermost circumference, data for prediction is obtained in the middle circumference area of the optical disc.
According to FIG. 6, the modulation factor curve m (Pp, V = 14) at the recording linear velocity V = 14 m / s is multiplied by the coefficient arithmetic expression A [Pp] = 0.0003Pp ² −0.0215Pp + 1.5194. Thus, the modulation degree curve m (Pp0, V0 = 27.9) at V0 = 27.9 m / s can be predicted.

Example 5
Recording experiments were performed using the same phase change optical recording medium as in Example 2.
FIG. 7 shows the result after the test recording was performed at the recording linear velocity V = 20.9 m / s and the gamma curve was calculated. Since the gamma curve of high-speed recording linear velocity V0 = 27.9 m / s cannot be written in the innermost circumference, the modulation degree data for prediction is taken in the middle circumference area of the optical disk and converted to the gamma curve. It is.
According to FIG. 7, by multiplying the gamma curve γ (Pp, V = 20.9) at the recording linear velocity V = 20.9 m / s by the coefficient arithmetic expression B [Pp] = 1.1, V0 = A gamma curve γ (Pp0, V0 = 27.9) at 27.9 m / s can be predicted.

Example 6
Recording experiments were performed using the same phase change optical recording medium as in Example 4.
FIG. 8 shows the result after the test recording was performed at the recording linear velocity V = 14 m / s and the gamma curve was calculated. Since the gamma curve of high-speed recording linear velocity V0 = 27.9 m / s cannot be written in the innermost circumference, the modulation degree data for prediction is taken in the middle circumference area of the optical disk and converted to the gamma curve. It is.
According to FIG. 8, by multiplying the gamma curve γ (Pp, V = 14) at the recording linear velocity V = 14 m / s by the coefficient arithmetic expression B [Pp] = 1.27, V0 = 27.9 m / s. The gamma curve γ (Pp0, V0 = 27.9) at s can be predicted.

The flowchart until the optimum recording power Ppo at a certain recording linear velocity is obtained. 6 is a flowchart for predicting an optimum recording power Ppo (V0) at a high recording linear velocity V0 by the method of the present invention. The figure which shows the result of having performed the test recording of Example 1. FIG. The figure which shows the result of having performed the test recording of Example 2. FIG. The figure which shows the result of having performed the test recording of Example 3. FIG. The figure which shows the result of having performed the test recording of Example 4. FIG. The figure which shows the result of having performed the test recording of Example 5. FIG. The figure which shows the result of having performed the test recording of Example 6. FIG. The figure showing the relationship between the test data and value used by (gamma) method.

Claims (5)

From the result of test recording in a linear velocity range slower than the recording linear velocity actually used for recording in a predetermined area of the lead-in zone of the phase change optical recording medium having a recordable linear velocity range of 21 to 42 m / s. A method for predicting an optimum recording power Ppo (V0) at a high recording linear velocity V0 , which employs an EFM + modulation method as a modulation method for recording a mark in test recording, and has a minimum mark length (3T) of 0. .38 to 0.42 .mu.m, and 2T cycle strategy as a pulse condition for recording a mark [when recording a 3T mark, one pulse is used, and when a (3 + N) T mark (N is a natural number) is recorded. is, N is adopted write strategy] for one pulse added to each 2 increases, the innermost predetermined region of a phase change optical recording medium, one recording linear velocity V (however, V0 / 2 ≦ <Varying the recording power Pp at V0) while performing test recording, degree of modulation curves m (Pp, V) was employed as the test data obtained by reproducing the recorded information, the following (i) ~ ( A method for predicting optimum recording power at a high recording linear velocity of a phase change optical recording medium , wherein the prediction is performed according to the procedure of iii) .
(I) Using a modulation degree curve m (Pp, V) and a coefficient arithmetic expression A [Pp] preformatted in the lead-in zone of the phase change optical recording medium, A modulation degree curve m (Pp0, V0) is predicted.
m (Pp0, V0) = m (Pp × A [Pp], V)
(Ii) P _target (V0) is predicted using the modulation degree curve m (Pp0, V0) and the Modulation _target preformatted in the lead-in zone of the phase change optical recording medium .
(Iii) The optimum recording power Ppo (V0) is predicted using P _target (V0) and ρ (V0) preformatted in the lead-in zone of the phase change optical recording medium. From the result of test recording in a linear velocity range slower than the recording linear velocity actually used for recording in a predetermined area of the lead-in zone of the phase change optical recording medium having a recordable linear velocity range of 21 to 42 m / s. A method for predicting an optimum recording power Ppo (V0) at a high recording linear velocity V0 , which employs an EFM + modulation method as a modulation method for recording a mark in test recording, and has a minimum mark length (3T) of 0. .38 to 0.42 .mu.m, and 2T cycle strategy as a pulse condition for recording a mark [when recording a 3T mark, one pulse is used, and when a (3 + N) T mark (N is a natural number) is recorded. is, N is adopted write strategy] for one pulse added to each 2 increases, the innermost predetermined region of a phase change optical recording medium, one recording linear velocity V (however, V0 / 2 ≦ <V0) in the recording power Pp is carried out for the test recording while changing the modulation degree of the curve m (Pp as test data obtained by reproducing the recorded information, the gamma curve calculated from V) by the following equation gamma ( Pp, V) is adopted, and the optimum recording power prediction method at a high recording linear velocity of the phase change type optical recording medium , wherein prediction is performed by the following procedures (i) to (iii) .
γ (Pp, V) = [dm (Pp, V) / dPp] × [Pp / m (Pp, V)]
(I) using gamma curve gamma (Pp, V) and the phase-change optical recording medium of the read coefficient calculation formula B which is pre-formatted in zone [Pp], gamma in the high-speed recording linear velocity V0 by the following formula A curve γ (Pp0, V0) is predicted.
γ (Pp0, V0) = γ (Pp × B [Pp], V)
(Ii) P _target (V0) is predicted using the gamma curve γ (Pp0, V0) and γ _target preformatted in the lead-in zone of the phase change optical recording medium.
(Iii) The optimum recording power Ppo (V0) is predicted using P _target (V0) and ρ (V0) preformatted in the lead-in zone of the phase change optical recording medium. Having at least a transparent substrate and a recording layer, a recordable linear velocity range of 21 to 42 m / s, and P _IND , Modulation _target or γ _{target at} a plurality of recording linear velocities in the lead-in zone, and ρ (V0), and 3. The phase change optical recording medium to which the optimum recording power prediction method according to claim 1 or 2 is applied, wherein the coefficient arithmetic expression A [Pp] or B [Pp] is preformatted. The recording layer is made of a phase change material containing at least three elements of Ga, Sb, and Sn. Information is recorded by forming an amorphous material, and information is erased by forming a crystalline material. 4. The phase change optical recording medium according to claim 3 , wherein recording can be repeated by alternately repeating the crystalline. 5. The phase change type according to claim 3 , wherein the transparent substrate has meandering grooves having a track pitch of 0.74 ± 0.03 μm, a groove depth of 22 to 40 nm, and a groove width of 0.2 to 0.3 μm. Optical recording medium.

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