JPH08124165A - Recording method for phase change type optical disk - Google Patents

Abstract

PURPOSE: To perform trial writings for obtaining an optimum recording condition in a phase change type optical disk. CONSTITUTION: In an algorithm obtaining the optimum values of recording and erasing LD powers recordings are performed by changing simultaneously respectively the recording LD power and the erasing LD power and thereafter optimum LD powers are obtained from their reproducing signals. In the case the interchanges of media, etc., are performed, when a command is present to a drive so as to perform trial writings before recording data, the drive moves an LD light to a trial writing area specified from a media format. The LD light is set to the first LD power of trial writings which is previously set in the drive. The drive performs the trial writing of data with the set LD power. When the final trial writing is completed, the LD light is moved to the leading of the trial writing area to be shifted to reproducing operations. The states of reproduced signals are detected to be stored. Then, the recording and the erasing powers of the best recording state are selected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording method for a phase change optical disk, and more particularly to a method for detecting optimum recording LD (semiconductor light emitting device) power in a phase change optical disk drive. For example, it is applied to a phase change type optical disc drive (DATA system, CD-PC, etc.).

[0002]

2. Description of the Related Art In optical discs, the recording format of the data area is largely dependent on the recording film of the disc used, write-once recording (Worm Type) and rewritable recording (Rewriteabl).
e Type). Rewritable recording includes magneto-optical recording (Magneto-Optical Memory) and phase change recording (Phas
e Change Memory). In a phase change recording type disk, data is recorded by utilizing the fact that the reflectance is different between the amorphous state (amorphous state) which is the two transition states of the recording film and the crystalline state.

As a known document describing a conventional optical disk recording method, for example, Japanese Patent Laid-Open No. 63-2540.
There is publication No. 8. In this publication, in order to determine the optimum value of the recording light intensity and always perform good recording, a signal is first recorded while changing the intensity of the recording light, and the recorded signal is reproduced and reproduced. After determining the optimum value of the recording light intensity that gives the best signal, the signal recording is performed while controlling the recording light intensity to be the optimum value. That is, trial writing is performed to determine the optimum recording power before recording data.

[0004]

As described above, in the recordable optical disk, the optimum condition is corrected by correcting the deterioration of the medium and the LD (semiconductor light emitting element) with time, the sensitivity change due to the dust adhesion, the light emission power change, and the like. Need to record in. One method for obtaining this optimum condition is trial writing. In the standardized optical disc, a trial writing area is secured in the media format. Before recording data, the recording LD power is changed in that area to perform trial writing, and then this area is reproduced to optimize the reproduction signal state. The optimum recording condition is determined, and thereafter, the data recording is performed under the optimum recording condition. Such a trial writing is necessary even for a phase change type optical disk, but since there are a plurality of recording LD power values that determine the recording state, the optimum LD power detection algorithm that has been conventionally used cannot be used as it is and the trial writing is performed. The method is not established.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a recording method for a phase-change optical disk for performing trial writing for obtaining the optimum recording condition for the phase-change optical disk.

[0006]

In order to solve the above-mentioned problems, the present invention provides (1) an optimum value of the recording and erasing semiconductor light emitting element power of an apparatus for optically recording and reproducing information on a phase change recording medium. This is a recording method to be sought, in which test writing is performed by simultaneously changing the recording and erasing semiconductor light emitting element powers according to the set rate of change, and the optimum recording and erasing semiconductor light emitting element power is determined from the reproduction signal in the trial writing area. Further, (2) the change rates of the recording and erasing semiconductor light emitting device powers are made equal, or
(3) A recording method for obtaining an optimum value of the recording and erasing semiconductor light emitting element power of a device for optically recording and reproducing information on a phase change recording medium, wherein the recording semiconductor light emitting element power and the erasing semiconductor light emitting element power are independent. To perform optimum test writing, and determine the optimum recording and erasing semiconductor light emitting element power from the reproduction signal of the test writing area.
(4) In (3), the optimum value of the erase semiconductor light emitting element power is determined to be a value that minimizes a demodulation error of a reproduction signal, and (5) in (3), the trial writing area. Erasing is performed while changing the erase semiconductor light emitting element power in the data recorded area of the recording medium at regular time intervals, and the optimum value of the erase semiconductor light emitting element power is determined from the reproduction signal level of the area. In (3), erasing is performed while changing the erase semiconductor light emitting element power in the data recorded area in the trial writing area at regular intervals, and the erase semiconductor light emitting element power is optimized from the level of the reproduction differential signal in the area. Determining the value,
Further, (7) in the above (4), (5) or (6), the optimum erase semiconductor light emitting device power is set to a lower value among the set powers that satisfy the conditions, and (8) ) In (3) above, after fixing the erase semiconductor light emitting element power to an optimum value, the recording semiconductor light emitting element power is changed to perform trial writing, and the optimum recording semiconductor light emitting element power is determined from the reproduction signal level of the area. (9) In (8), the optimum value of the recording semiconductor light emitting element power is determined to be a value that minimizes the asymmetry of the reproduction signal (difference between the reproduction signal average levels of the short mark and the long mark). It is characterized by doing.

[0007]

According to the recording method of the phase change type optical disk of the present invention having the above structure, the recording and erasing LD (semiconductor light emitting element) power of the apparatus for optically recording / reproducing information on / from the phase change recording medium is determined to obtain the optimum value. The method is as follows: (1) Since the recording and erasing LD powers are simultaneously changed in the trial writing area according to the set rate of change, the trial writing firmware sequence or media format other than the phase change type optical disc should be used almost as it is. In addition, the optimum recording and erasing LD power can be efficiently obtained in a short time. Also, due to the characteristics of the medium, recording and erasing LD
When the power sensitivity is different, the recording LD power and the erase L
It can be finely adjusted by changing the value of the change rate of D power.

(2) Since the change rates of the recording LD power and the erasing LD power are made equal to each other, the optimum LD can be efficiently and accurately selected when the sensitivities to the recording and erasing LD powers are equally changed due to deterioration of the LD or the medium over time. You can ask for power. (3) Recording LD power and erasing LD in the trial writing area
Since the power is independently changed and the optimum value is individually calculated, the optimum recording and erasing LD power can be calculated when the trial writing media format for the phase change optical disc and the firmware sequence are used.

(4) Since the optimum value of the erasing LD power is determined to be the value that minimizes the demodulation error of the reproduction signal, the optimum erasing LD power that suppresses the generation of unerased recording marks and defective recording marks is obtained. be able to. (5) Since the erasing operation is performed by changing the erasing LD power in the recorded trial writing area and the unerased portion is detected from the reproduction signal level, the optimum erased LD power without the unerased portion can be obtained.

(6) Since the erasing operation is performed by changing the erasing LD power in the recorded trial writing area and the unerased portion is detected from the differential signal level of the reproduced signal, the optimum erased LD power without the unerased portion is obtained. It can be calculated more accurately. (7) Since a low value is selected among the erasing LD setting powers that satisfy the optimum condition, the lifespan of the LD and the medium can be improved, and the power consumption can be suppressed low.

(8) Determine the optimum value of the erase LD power,
Since the recording LD power is changed and recording is performed after fixing to that value, and the optimum recording LD power is obtained from the reproduction signal level, it is possible to obtain the optimum recording LD power that suppresses the generation of recording marks such as unerased portions and formation defects. . (9) Since the optimum value of the erasing LD power is determined and fixed to this value, the recording LD power is changed and recording is performed, and the optimum recording LD power is determined to a value that minimizes the assistance of the reproduction signal. The recording LD power for forming an accurate recording mark can be obtained.

[0012]

Embodiments will be described below with reference to the drawings. 2 (a) and 2 (b) are diagrams showing the difference in the recording LD (semiconductor light emitting device) emission waveforms of the phase change type optical disc and another optical disc (for example, WORM). FIG. 2 (a) shows the phase change type optical disc. An optical disc and FIG. 2B show the case of a WORM type optical disc. In the phase change type optical disc, at least two different LD powers for recording and erasing are required for overwriting recording.

The recording mechanism is that the recording film is heated to a temperature above its melting point with a high recording LD power, and when it is rapidly cooled, the film becomes amorphous, and the recording film is heated to a crystallization temperature with a relatively low erasing LD power.
When cooled, it crystallizes (Figs. 3 (a)-(c)). Information is recorded by utilizing the fact that the reflectance is different in these two states. In the figure, IP indicates isolated pulse without erase power, W.
P. is the recording power (Write power), E.P. is the erasing power (Erase power), NM is the new mark (New mark), O.
M. is the old mark, ER is the erase ring (Era
sed ring), MP is the melting point, CP
Is the crystallization temperature (Crystallization point).

Both of these binary LD powers are closely related to the recording state, and if recording is not performed with the optimum LD power, reproduction of data such as unerased previous data or defective recording mark formation will occur. Will cause an error.
Although the recording LD power and the erasing LD power may take a plurality of values, respectively, the reference recording and erasing L
This can be handled by determining the ratio from the D power.

FIG. 1 is a flow chart for explaining an embodiment (Embodiments 1 and 2) of a trial writing method for a phase change optical disk according to the present invention. Below, each step (S)
Will be described in order. In Example 1 (claim 1) and Example 2 (claim 2), in the algorithm for obtaining the optimum value of the recording and erasing LD power, the recording LD power and the erasing LD power were changed at the same time and recording was performed. In addition, the optimum LD power is obtained from the reproduced signal.

Step 1 : First, when a medium is replaced or the like, and the drive is instructed to perform trial writing before data recording, the LD light is moved to the trial writing area defined by the media format. Table 1 below shows the media information zone layout of a data type optical disc (90 mm) as an example of the trial writing area. The drive for the inner circumference test zone is the test writing area.

[0017]

[Table 1]

[0018] step2: Next, set to test writing first LD power that is set in advance (I = 1, t =
0). Table 2 shows a list of settings.

[0019]

[Table 2]

With respect to the set values, the central values of the recording and erasing LD powers are set to P _{w ref} and P _{b ref} , respectively, and the rate of change a and b changes in (2n + 1) steps as I changes. In Table 2, the first set value is the smallest value, but it is not limited to this. In the first embodiment, the sizes of a and b are not specified. This is because when the sensitivities of the recording and erasing LD powers are different due to the characteristics of the medium, the values of a and b are changed so as to cope with them.

Step 3 : Test writing of data (a special pattern is also possible) with the set LD power. After the lapse of a prescribed time (t = I * t ₀ ), the recording is interrupted, the number of trial writings (I) is confirmed, and if it is not completed (I = 2n + 1),
The setting is changed to a new LD power setting value (I = I + 1), and trial writing is continued. step4 : If the last trial writing is completed (I = 2n + 1), move the LD to the beginning of the trial writing area (I = 1, t =
0), move to playback operation. step 5 : The reproduced signal state is detected and stored for each (t = I * t ₀ ). step6 : When the data is detected up to the last trial writing area (I = 2n + 1) and the storage is completed, the recording and erasing LD power of the best recording state is selected from the reproduction signal state storage data and used for the subsequent data recording. Optimal recording and erasing LD
Use as power.

The second embodiment is characterized in that the change rates a and b of the trial writing LD power set value are made equal. In the trial writing method of the first and second embodiments, since the trial writing is performed by simultaneously changing the recording and erasing LD powers, the trial writing firmware sequence or media format other than the conventional phase change type optical disc can be used almost as it is.

FIGS. 4 and 5 are flow charts for explaining another embodiment (Embodiments 3 to 9) of the recording method of the phase change type optical disk according to the present invention. Hereinafter, each step (S) will be described in order. Examples 3 to 9 (claim 3)
9 to 9) are algorithms for obtaining the optimum values of the recording and erasing LD powers, in which the recording LD power and the erasing LD power are changed independently to perform recording, and then the optimal LD power is obtained from the reproduced signal. In the third to seventh embodiments, either the optimum recording or erasing LD power value may be determined first. In the eighth and ninth embodiments, the optimum value of the erase LD power is first determined. The order of determining the optimum value follows the order of erasing and recording LD power as an example, but this is not the case for Examples 3 to 7. This is similar to the case where the flowchart of the first embodiment is divided into recording and erasing LD powers and performed twice consecutively.

Step 11 : First, the LD light is moved to the trial writing area. step12 : Next, in order to determine the erasing LD power, it is set to the preset LD power value of the first trial writing (J = n + 1, K = 1, t = 0). Table 3 shows a list of settings.

[0025]

[Table 3]

With respect to the set values, the central values of the recording and erasing LD powers are set to P _{w ref} and P _{b ref} , respectively, and the rate of change a and b changes in (2n + 1) steps as J and K change. In Table 3,
The first set value is the smallest value, but it is not limited to this. step13 : The recording LD power is fixed and the erasing LD power is changed to perform trial writing. step14 : The state of the reproduction signal is detected and stored from the beginning of the trial writing area, and the optimum erase LD power is determined. step15 : In order to determine the recording LD power, set the LD power value at the beginning of the trial writing that has been set in advance (J
= 1, K = x, t = 0). However, the erase LD power is the optimum value obtained in the first half of the flowchart. step16 : Erase LD power is fixed, recording LD power is changed, and trial writing is performed. step17 : The state of the reproduction signal is detected and stored from the beginning of the trial writing area, and the optimum recording LD power is determined. step18 : End detection of optimum recording and erasing LD power.

In the third embodiment, the order of determining the recording LD power and the erasing LD power in the above flow is not limited to this, and the optimum LD power is obtained independently. Examples 4 to 7 described below relate to determination of the erase LD power in step 13 and step 14 in the flowchart of FIG.

FIGS. 6A to 6F are views for explaining the fourth embodiment. FIG. 6A is old data, FIG. 6B is overwrite data, and FIG. An accurate reproduction signal, FIG. 6 (d) is accurate detection data, FIG. 6 (e) is a reproduction signal with an unerased portion, and FIG. 6 (f) is detection data with an error. As shown in FIG. 6, when the overwrite data is recorded on the old data, if there is not the optimum erasing LD power, a reproduction signal having an unerased portion is detected. When this is binarized and demodulated, the error information is different from the recorded overwrite data. The value that minimizes the amount of this error is the optimum erase LD power value. In addition, the data used for trial writing is predetermined data,
In particular, it is possible to more accurately obtain the optimum value with a special pattern that is prone to error.

FIGS. 7A to 7C are views for explaining the fifth and sixth embodiments. FIG. 7A shows old data and FIG. 7B.
Is a reproduced signal after erasing, and FIG. 7C is a reproduced differential signal after erasing. In the fifth embodiment, the recorded area is erased only by the erasing LD power (data is not recorded), and the value of the remaining unerased signal amplitude (r1) remaining in the reproduction signal of the area is the optimum erasing LD power value. And In the sixth embodiment, the recorded area is erased only by the erasing LD power (data is not recorded), and the value of the residual unerased signal amplitude (r2) remaining in the differential signal of the reproduction signal of the area is erased LD Use the optimum power value.

FIG. 8 is a block diagram for detecting the unerased information of the fifth and sixth embodiments. In the figure, 1 is a differentiation circuit, 2 is an AC power supply device, 3 is a slice level generation circuit, and 4 is binarization. circuit,
5 is a counter. The reproduced signal or the reproduced differential signal differentiated by the differentiating circuit 1 is removed by the AC coupler 2 for low frequency components, and is erased by the binarizing circuit 4 with the unerased determination signal level generated by the slice level generating circuit 3 as a reference. The remaining data is generated and erased by the counter 5, and the remaining amount is digitized.

In the seventh embodiment, a criterion is set when there are a plurality of erase LD power setting values that satisfy the optimum erase condition. If the LD power is high, there is a demerit that the life of the LD and the medium is shortened. Therefore, the LD power that is as low as possible is adopted within the set values that satisfy the optimum conditions. In the eighth embodiment, the description of the flowchart of FIG. 4 described above is substituted. The order of obtaining the optimum recording LD power after optimizing the erasing LD power is defined. Example 9 is
Recording L of step16 and step17 in the flowchart of FIG.
Regarding the determination of D power. Recording with fixed erasing power L
When data is recorded by changing the D power, the asymmetry of the reproduced signal changes. This state is shown in FIGS.
Shown in This waveform is observed by AC coupling the reproduced signal. FIG. 9A shows a case where the recording LD power is strong and the mark is long as a whole. FIG. 9B shows a case where recording is performed with the optimum recording LD power. FIG. 9 (c)
Indicates the case where the recording LD power is weak and the mark is short overall.

Usually, asymmetry is represented by β = (A ₁ + A ₂ ) / (A ₁ -A ₂ ), where A + and -side amplitude maximum values of the AC-coupled reproduced signal are A ₁ and A ₂ , respectively. Be done. That is, the asymmetry can be said to be the difference between the reproduction signal average levels of the short mark and the long mark. Example 9
Then, the recording LD for which this asymmetry is the minimum (≈0)
The power is the optimum recording condition.

[0033]

【The invention's effect】

(1) Effect corresponding to claim 1: Since the recording and erasing LD powers are simultaneously changed in the trial writing area according to the set change rate, a trial writing firmware sequence or media format other than the phase change type optical disc Can be used as it is, and the optimum recording and erasing LD power can be efficiently obtained in a short time. Further, when the sensitivities of the recording and erasing LD powers are different due to the characteristics of the medium, it is possible to make a fine adjustment by changing the value of the change rate of the recording LD power and the erasing LD power. (2) Effect corresponding to claim 2: Since the change rates of the recording LD power and the erasing LD power are made equal, the efficiency is improved when the sensitivities to the recording and erasing LD powers are changed equally due to deterioration of the LD and the medium over time. The optimum LD power can be obtained accurately and accurately. (3) Effect corresponding to claim 3: The recording LD power and the erasing LD power are changed independently in the trial writing area,
Since the optimum value is individually calculated, the optimum recording and erasing LD power can be calculated when the trial write media format for the phase change optical disk and the firmware sequence are used. (4) Effect corresponding to claim 4: Since the optimum value of the erasing LD power is determined to be the value that minimizes the demodulation error of the reproduction signal, it is an optimum value that suppresses the generation of recording marks such as unerased parts and formation defects. The erase LD power can be obtained. (5) Effect corresponding to claim 5: Since the erasing operation is performed by changing the erasing LD power in the recorded trial writing area, and the unerased portion is detected from the reproduced signal level, optimum erasing without the unerased portion The LD power can be calculated. (6) Effect corresponding to claim 6: Since the erasing operation is performed by changing the erasing LD power in the recorded trial writing area, and the unerased portion is detected from the differential signal level of the reproduced signal, there is no unerased portion. The optimum erase LD power can be obtained more accurately. (7) Effect corresponding to claim 7: In order to select a low value among the erase LD setting powers that satisfy the optimum condition, L
It is possible to improve the lifespan of the D and the medium, and also to keep the power consumption low. (8) Effect corresponding to claim 8: The optimum value of the erasing LD power is determined, fixed to this value, the recording LD power is changed and recording is performed, and the optimum recording LD power is obtained from the reproduction signal level, so the erasing is performed. It is possible to obtain the optimum recording LD power that suppresses the occurrence of recording marks such as remaining marks and formation defects. (9) Effect corresponding to claim 9: The optimum value of the erasing LD power is determined, fixed to this value, and then the recording LD power is changed for recording, and the optimum recording LD is set to a value at which the asymmetry of the reproduction signal is minimized. Since the power is determined, the recording LD power for forming an accurate recording mark can be obtained.

[Brief description of drawings]

FIG. 1 is a flowchart for explaining one embodiment (Embodiments 1 and 2) of a trial writing method for a phase change optical disk according to the present invention.

FIG. 2 is a diagram for explaining LD light emission and mark formation in the present invention.

FIG. 3 is a diagram for explaining a temperature distribution of a beam spot in the present invention.

FIG. 4 is a flowchart (No. 1) for explaining another embodiment (Embodiment 3) of the recording method for the phase-change optical disk according to the present invention.

FIG. 5 is a flowchart (No. 2) for explaining another embodiment (Example 3) of the recording method for the phase-change optical disk according to the present invention.

FIG. 6 is a diagram for explaining still another embodiment (Example 4) of the recording method for the phase-change optical disk according to the present invention.

FIG. 7 is a diagram for explaining still another embodiment (Examples 5 and 6) of the recording method of the phase change optical disk according to the present invention.

FIG. 8 is a block diagram for realizing Embodiments 5 and 6 of the present invention.

FIG. 9 is a diagram showing asymmetry of a reproduced signal according to the present invention.

[Explanation of symbols]

1 ... Differentiating circuit, 2 ... AC coupler, 3 ... Slice level generating circuit, 4 ... Binarizing circuit, 5 ... Counter.

Claims (9)

[Claims] 1. A recording method for obtaining an optimum value of a recording and erasing semiconductor light emitting element power of an apparatus for optically recording and reproducing information on a phase change recording medium, wherein the recording and erasing semiconductor light emitting element power is set respectively. A recording method for a phase-change optical disk, which is characterized in that test writing is carried out while simultaneously changing according to a rate of change, and optimum recording and erasing semiconductor light emitting element power is determined from a reproduction signal in the test writing area. 2. The recording method for a phase-change optical disk according to claim 1, wherein the recording and erasing semiconductor light emitting device powers have the same rate of change. 3. A recording method for obtaining an optimum value of the recording and erasing semiconductor light emitting element power of an apparatus for optically recording and reproducing information on a phase change recording medium, the recording semiconductor light emitting element power and the erasing semiconductor light emitting element power being set. A method of recording on a phase-change optical disk, which is characterized in that test writing is performed by changing it independently, and an optimum recording and erasing semiconductor light emitting element power is determined from a reproduction signal in the test writing area. 4. The recording method for a phase-change optical disc according to claim 3, wherein the optimum value of the power of the erasing semiconductor light emitting device is determined to be a value at which the demodulation error of the reproduction signal is minimized. 5. The erased semiconductor light emitting element power is erased while changing the power of the erased semiconductor light emitting element in a data recorded area in the trial write area at regular intervals, and the optimum value of the erased semiconductor light emitting element power is determined from the reproduction signal level of the area. 4. The method for recording a phase change type optical disc according to claim 3, wherein 6. The optimum value of the erase semiconductor light emitting device power is erased from the level of the reproduction differential signal of the region in the data recorded area of the trial writing area while changing the erase semiconductor light emitting element power at regular intervals. 4. The method for recording a phase-change optical disk according to claim 3, wherein 7. The recording method for a phase-change optical disk according to claim 4, wherein the optimum erase semiconductor light emitting device power is a lower value among set powers satisfying the conditions. 8. The optimum recording semiconductor light emitting element power is determined from the reproduction signal level of the area by fixing the erase semiconductor light emitting element power to an optimum value and then changing the recording semiconductor light emitting element power. 4. The recording method for a phase change type optical disc according to claim 3, wherein 9. The recording method for a phase-change optical disk according to claim 8, wherein the optimum value of the power of the recording semiconductor light emitting device is determined to a value at which the asymmetry of the reproduction signal is minimized.