JP2000113535A - Optical recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording method capable of avoiding the deterioration of an optical recording medium in recording information on the optical recording medium through irradiation of recording light. SOLUTION: This is an optical recording method for recording information through the irradiation of recording light which is modulated to the binary of at least a low power level PL and a high power level PH, the method is provided with a procedure 1 which as test recording, records reference information in a prescribed area of an optical recording medium, a procedure 2 which obtains a reproducing signal of the reference information from the prescribed area of the medium and a procedure 3 which decides the power levels PL1, PH1 of the recording light at a normal recording time by carrying out the procedures 1, 2 by varying the power levels PL, PH of the recording light into various values. In this method, in the case of varying the power level of the recording light by the procedure 3, as the PL value is large, the ratio of the PH value to the PL value is set smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording method for recording information on an optical recording medium by irradiating recording light.

[0002]

2. Description of the Related Art In recent years, with the development of a highly information-oriented society, the need for a large-capacity file memory is increasing. In response, optical recording has received the most attention. Optical recording media include phase change optical disks and magneto-optical disks. All of these optical recording media are capable of high-density recording by forming recording marks of 1 μm or less using laser light, and are capable of repetitive recording utilizing the reversibility of the state. Further, in order to shorten the rewriting time, those optical recording media to which new information is directly written from old information, that is, a so-called overwrite method has been introduced to the market. The most common type of the overwrite type magneto-optical disk is an optical modulation overwrite type in which a layer for performing a recording operation is provided in addition to a memory layer on which information is recorded.

[0003] Such a light modulation overwrite method is,
JP-A-62-175948 (Patent No. 252190)
No. 8). The medium disclosed in the above publication has two layers, a memory layer 142 and a recording layer 143, as shown in FIG. In the light modulation overwrite method, while erasing old information in the memory layer 142 by irradiation with a relatively low laser power (PL1), new information is recorded on the recording layer 143 by irradiation with a high laser power (PH1). Will be

[0004] Of these, PH1 needs to have a power sufficient to write new information into the recording layer 143. On the other hand, it is necessary to set PL1 to a power that is sufficient for erasing old information in the memory layer 142 and lower than a temperature at which information is written to the recording layer 143. In addition, the appropriate power levels (PL1, PH1) differ for each disk and each recording surface on the disk due to the difference in characteristics.

[0005] This means that from the recording / reproducing apparatus side,
Since the recording sensitivity and the erasing sensitivity are different, it is necessary to set an optimum power level for each loaded optical disc. And, since the characteristics of the laser diode generally mounted as a light source are easily affected by the environmental temperature,
It is required to appropriately change the set value of the power level.
Therefore, in the recording / reproducing apparatus, in order to properly perform “normal recording” in which information to be actually recorded is written, “test recording” (test writing) is performed when a disc is loaded, at regular time intervals, or whenever the environmental temperature changes. ) To obtain an appropriate power level setting value.

Next, a conventional test recording method will be described with reference to FIGS. FIG. 16A is a diagram showing the relationship between the high power level PH and the low power level PL of the recording laser beam during test recording, and FIG.
FIG. 6 is a diagram illustrating a relationship between a low power level PL and the number of errors. FIG. 17 is a diagram showing a temporal change in the power level of the recording laser beam during test recording.

In test recording, an operation of recording reference information in a test area of a disk and reproducing the same under the same conditions as in actual reproduction is performed a plurality of times while changing the recording power. Thereafter, based on the relationship between the recording power and the recording accuracy, an optimum set value of the recording power is obtained. For example, as shown in FIG. 17, a recording laser beam is modulated into a low power level PL and a high power level PH according to reference data. At this time, as shown in FIG. 16A, the high power level P with respect to the low power level PL
Test recording and reproduction are repeated by changing the power of the recording laser beam while maintaining the ratio with H at a predetermined value. Thereafter, the number of errors included in the reproduction data is counted for each recording power.

FIG. 16 (2) shows the relationship between the number of errors thus obtained and the low power level PL. The number of errors decreases with an increase in the value PL, and the value P
When L is within a certain range, the number of errors is minimized. If the value PL is larger than the range, the number of errors increases with an increase in PL. Therefore, the optimum recording power is determined from the range of the recording power where the number of errors is equal to or less than the allowable number of errors of the reproducing system. Since the optimum recording power is the power with the largest power margin in the range, for example, the upper limit Pb and the lower limit P
The value is set to a value ((Pb + Pa) / 2) which is intermediate with the value a.

[0009]

By the way, as described above, when searching for a range in which the number of errors is the allowable number of errors,
In order to find the upper limit Pb of the range, it is necessary to perform test recording with a recording power larger than the finally set appropriate power.
As shown in (1), the case where the heating is performed beyond the allowable upper limit temperature (for example, the high power level PH becomes equal to or higher than the value PJ) often occurs.

Therefore, if this test recording is performed every time the recording / reproducing device is replaced or frequently in response to a change in environmental temperature, the reversibility of the test area is lost, and the reproduced signal such as an increase in noise is lost. It causes quality deterioration and changes in characteristics. In particular, among the magneto-optical disks of the light modulation overwrite type, there is a magneto-optical disk in which an initialization layer in which the magnetization directions are aligned in one direction can be provided and one of the external magnetic fields can be omitted. If heated even once, the magnetization direction is partially reversed and the desired function cannot be achieved. This means that the test area has been partially destroyed.

In any case, the original test recording function cannot be performed on an optical disk having a deteriorated test area. In order to prevent such a problem, for example, it is conceivable that the recording power at the time of test recording does not exceed the upper limit PJ. However, in this case, the range of the recording power for performing the test recording is narrowed.
There is a possibility that the optimum value cannot be set because b cannot be found. Therefore, the power margin of the light source is reduced, and stable recording cannot be performed.

[0012] A similar problem also exists in a phase-change type optical disk capable of overwriting. In other words, the phase-change optical disk is heated to the transition temperature between the non-crystal and the crystal at the time of recording. However, if the test recording at a high temperature is repeated, the material flow easily occurs, and the reversibility between the non-crystal and the crystal is lost. I do. Specifically, it is conceivable that flow occurs between the recording layer made of Ge, Sb, and Te and the protective layer made of Zn and S, and the characteristics of the recording layer change.

An object of the present invention is to provide an optical recording method capable of avoiding deterioration of an optical recording medium when setting a power level of optical recording.

[0014]

According to the first aspect of the present invention, at least a low power level PL and a high power level P
An optical recording method in which recording is performed by irradiating a binary-modulated recording light with H. A procedure 1 in which reference information is recorded in a predetermined area of the optical recording medium as test recording; A procedure 2 for obtaining a reproduction signal of the reference information from the area, and a procedure 1 and a procedure 2 in which the power level (PL, PH) of the recording light is changed to various values, perform the recording light in the normal recording. Power level (PL1, P
H1) is determined by changing the power level of the recording light in step 3.
The ratio of the value PH to the value PL is set to be smaller as the value PL is larger.

According to a second aspect of the present invention, in the optical recording method of the first aspect, when the power level of the recording light is changed in step 3, if the value PL is smaller than a predetermined value, the value PL Is set to a constant value, and the value P
If L is equal to or greater than a predetermined value, the value PH with respect to the value PL
Is set to a constant value smaller than the constant value.

According to a third aspect of the present invention, in the optical recording method according to the second aspect, when changing the power level of the recording light in step 3, if the value PL is smaller than a predetermined value, the value PL Is set to a constant value, and the value P
When L is equal to or greater than a predetermined value, the value PH is set to a constant value equal to the product of the predetermined value and the constant value. The invention according to claim 4 is an optical recording method for performing recording by irradiating at least binary recording light of a low power level PL and a high power level PH, wherein an optical recording medium is used as test recording. Of recording reference information in a predetermined area of the optical recording medium, procedure 2 of obtaining a reproduction signal of the reference information from the predetermined area of the optical recording medium, and changing the power level (PL, PH) of the recording light to various values. In the optical recording method including the procedure 3 for determining the power level (PL1, PH1) of the recording light at the time of normal recording by performing the procedure 1 and the procedure 2, in the procedure 3, the power level at the time of the change is changed. PH greater than ratio PH / PL
1, wherein PL1 is determined to be the power level of the recording light during normal recording.

According to a fifth aspect of the present invention, in the optical recording method according to any one of the first to fourth aspects, the optical recording medium is a magneto-optical recording medium to which an optical modulation overwrite system is applied. It is characterized by being. According to a sixth aspect of the present invention, in the optical recording method according to any one of the first to fifth aspects, test recording and normal recording are performed in the following manner.
The pulse train recording method modulates recording light at a frequency higher than the frequency corresponding to the bit string.

(Operation) According to the first aspect of the present invention, test recording and reproduction are performed while changing the power level of the recording light, and the power level of the recording light during normal recording is determined, as in the prior art. However, in this process, when changing the power level of the recording light, an operation of setting the ratio of the value PH to the value PL to be smaller as the value PL is larger is performed.
As a result, the rate of increase of the high power level becomes smaller than that of the low power level, so that the maximum value of the power level of the recording light at the time of test recording can be suppressed to be smaller than in the related art. Therefore, deterioration of the optical recording medium can be prevented.

According to a second aspect of the present invention, in the first aspect of the present invention, when the low power level of the recording light is larger than a predetermined value, the rate of increase of the high power level with respect to the low power level is determined by the predetermined rate. Make it smaller than when it is less than or equal to the value. This setting can be realized by a simple calculation as compared with the first aspect. This makes it possible to perform appropriate test recording while suppressing deterioration of the medium more easily than in the first aspect of the present invention.

According to a third aspect of the present invention, in the second aspect of the invention, test recording is performed by changing the low power level while setting an upper limit on the high power level of the recording light. This makes it possible to reliably prevent the deterioration of the optical recording medium by suppressing the high power level to be equal to or less than the upper limit value.

According to the fourth aspect of the present invention, test recording and reproduction are performed while changing the power level of the recording light to determine the power level of the recording light during normal recording. The power level ratio (PH1 / PL1) to be set during normal recording is set larger than the power level ratio (PH / PL) set at the time.

Therefore, it is possible to suppress the maximum value of the power level to be irradiated at the time of test recording, and to secure the difference between the high power level and the low power level at the time of normal recording. That is, the degree of deterioration of the optical recording medium can be kept low, and normal recording can be performed stably. In this case, the low power level PL1 during normal recording is determined based on the relationship of the reproduction signal to the power level PL obtained in such test recording, and the high power level PL1 during normal recording is determined. PH1 can be determined by calculation from the determined value PL1 and a predetermined ratio.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the optical recording medium is a magneto-optical recording medium to which an optical modulation overwrite method is applied. . That is, the setting of the recording light of the optical modulation overwrite method is appropriately performed while preventing the deterioration of the optical recording medium. In the invention described in claim 6, the invention described in any one of claims 1 to 5 is applied to a pulse train recording method.

A recording mark to be formed on an optical recording medium may be deformed due to heat accumulation, which hinders high-density recording. Therefore, a pulse having a higher frequency than that of the bit string is used to form the recording mark in an appropriate shape, so that such a problem is solved.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a main configuration of a recording / reproducing apparatus for implementing the recording method of the present invention. The recording / reproducing apparatus includes an optical head 11, a laser diode driving circuit (LD driving circuit) 13, a recording waveform generating circuit 12, a reproducing circuit 16, a central processing unit (CPU).
14, a memory 15, a magnetic field generation circuit (not shown) and the like.

The optical head 11 mounts a laser diode, an optical system (a lens, a diffraction grating, etc.), a photodetector, and the like. During recording and reproduction, the optical head 11 irradiates a recording or reproduction laser beam, which is obtained by condensing light emitted from a laser diode, onto a track of the optical disk 10 whose rotation is controlled. At the time of reproduction, the optical head 1
Numeral 1 converts the light reflected by the optical disk into an electric signal corresponding to the polarization angle and supplies the electric signal to the reproducing circuit 16.

At the time of recording, the recording waveform generating circuit 12 generates a recording waveform according to the data bit string of the recording data output from the CPU 14, and converts the waveform into the LD driving circuit 1
Output to 3. This recording waveform is represented by the data bit string "
This is a timing waveform which is generated in accordance with 1 "" 0 "and defines the timing at which the recording laser beam becomes the high power level PH and the low power level PL. In terms of the power level of the recording laser beam, there are, for example, those shown in FIGS.

The LD drive circuit 13 drives the laser diode mounted on the optical head according to the timing and level indicated by the recording waveform. Specifically, a current value corresponding to the level of the recording waveform is given to the laser diode at the timing indicated by the recording waveform. Note that the current value corresponding to each level is a set value set in advance by the CPU 14. During reproduction, the LD drive circuit 13
The CPU 14 drives the laser diode according to the value set for reproduction, and emits continuous light.

The reproducing circuit 16 generates reproduced data by amplifying the electric signal obtained from the optical head 11 and performing A / D conversion. The memory 15 stores a test program for implementing the test recording method of each embodiment, in addition to a general recording / reproduction control program. This test program includes, for example, the procedures shown in FIG. 2, FIG. 4, FIG. 6, and FIG.

The CPU 14 controls each unit based on a program stored in the memory 15 to realize various functions of the recording / reproducing apparatus. That is, at the time of recording, when information to be recorded and an area designation on the optical disk to which the information is to be written are input from outside, the optical head 11 and the optical disk 1
By controlling the relative position of 0, the exit of the optical head 11 is directly opposed to the designated area. Then, the CPU 14 supplies the recording data to the recording waveform generation circuit 12 and the LD driving circuit 1
Set the recording power to 3. Specifically, the current value to be supplied to the optical head 11 by the LD drive circuit 13 is set to a value for recording. During this recording, a recording magnetic field is applied to the optical disk 10 by driving a magnetic field generation circuit (not shown).

At the time of reproduction, the current value to be applied to the optical head 11 is set to a value for reproduction, so that the LD drive circuit 13 is set to a reproduction power lower than the recording power. In the embodiment of the present invention, the CPU 14
Executes the test program stored in the memory 15 at the time of test recording, and performs an operation for obtaining an optimum recording power. Note that test recording is performed at the time of startup, at the time of disc loading, or at regular intervals during operation of the recording apparatus.

The operation of the recording / reproducing apparatus during test recording will be described below. First, a first embodiment will be described with reference to FIGS. In the first embodiment,
It corresponds to Claims 1-3. FIG. 2 is an operation flowchart of the CPU 14 in the first embodiment. FIG.
FIG. 3A is a diagram showing the relationship between the high power level PH and the low power level PL (set value) of the recording laser beam in the first embodiment, and FIG. FIG. 9 is a diagram illustrating a relationship with data error numbers. As shown in FIG. 3, the high power level PH has a value of 1
0.8 mW is set as the upper limit value PJ (limit power). Note that the limit power PJ in the first embodiment is an upper limit value that does not deteriorate any optical disc that can be loaded in the recording / reproducing apparatus.

In FIG. 2, in S1, the CPU 14
For the LD drive circuit 13, the recording power is set to the starting power level, for example, (PH, PL) = (6.40 mW,
1.60 mW) (FIG. 3 (1) (a)). Then, the CPU 14 controls the movement of the irradiation position of the optical head 11 and emits the recording laser light having the set start power level.
Irradiate the test area of the optical disk 10 to record the reference data (S2).

The test area corresponds to the optical disk 10
It is assumed that the track is other than the user area such as the innermost peripheral area and the outermost peripheral area. In addition, the reference data is
This is data forming a mixed pattern in which short marks and long marks are randomly arranged. Further, the modulation mode of the recording laser beam is determined according to the reference data stored in the memory 15.
One of the various modulation modes shown in FIGS. 12 to 14 is assumed.

Next, the CPU 14 operates the LD driving circuit 13.
Then, a set value for reproduction is given, and a laser beam for reproduction composed of continuous light is applied to the test area of the optical disc 10. That is, the CPU 14 determines the measurement start point (FIG. 3 (1) (a)).
The reproduction data at is obtained (S3). CPU14
Compares the reproduction data obtained as a result of S3 with the reference data stored in the memory 15 and counts the number of errors included in the reproduction data. Then, the CPU 14 stores the counted number of errors (the value 45 in FIG. 3 (2) (c)) in the memory 15 in association with the set value of the low power level PL (1.60 mW) (S4). .

Then, the CPU 14 determines whether or not the set high power level PH has reached the limit power PJ (S5). If the result of the determination is negative (NO), C
The PU 14 sets the value of the next measurement point in S6, returns to S2, and performs S3, S4, and S5. The setting in S6 at this time is a value obtained by increasing the recording power without changing the ratio (PH / PL). For example, the low power level PL is increased by 0.1 mW (FIG. 3A).

In the first embodiment, the CPU 14 sets the range (PH <10.8 mW, P <10.8 mW) until the set high power level PH reaches the limit power PJ.
L <2.70 mW), the data acquisition (S2 to S6) is repeated while keeping the ratio (PH / PL) constant and increasing the low power level PL by 0.1 mW at a time.

Then, the high power level PH reaches the limit power PJ (PH ≧ 10.8 mW) (FIG. 3).
(1) (e)), that is, if the determination in S5 is affirmative (YES), in the next S7, the CPU 14 sets the set low power level PL to the end power PLE (for example, 3.30).
mW). At the measurement point (e), the result of the determination is negative (NO), and the CPU 14
At S8, the value of the next measurement point is set, and the process returns to S2, where S3, S
4. Perform steps S5 and S7.

In the setting of S8, the CPU 14 increases only the low power level PL without changing the high power level PH. Here, the low power level PL is increased by 0.1 mW. Thus, in the range (2.70 mW ≦ PL <3.30 mW) until the set low power level PL reaches the end power PLE, the CPU 14 changes the low power level PL without changing the high power level PH. The data acquisition (S2 to S5, S7, S8) is repeated while increasing by 0.1 mW.

When the low power level PL becomes the end power PLE, the recording power to be set at the time of normal recording is determined (S9). Here, the relationship between the low power level stored in the memory 15 and the number of errors is shown in FIG.
As shown in (2). The CPU 14 refers to the relationship between the recording power and the number of errors stored in the memory 15 by the test recording to determine the range of the low power level PL in which the allowable number of errors of the reproduction system is 20 or less. Assuming that the acquired range is, for example, a range of 1.8 mW to 3.1 mW, the center value 2.4 mW of the range is stored in the memory 15 as the set value of the low power level PL during normal recording. The set value of the high power level corresponding to the set value of the low power level is 9.6 mW according to FIG.
Therefore, this value is also stored in the memory 15.

Generally, an optical recording medium to which an optical recording method is applied includes a phase change optical disk and a magneto-optical disk. However, as described in the prior art, these may deteriorate when heated to a certain temperature or higher. There is. Therefore, at the time of test recording, it was necessary to suppress the high power level PH of the recording light to a level that would not cause deterioration. Based on this, in the first embodiment, when changing the power level of the recording light, the ratio of the value PH to the value PL is allowed to change, thereby preventing the high power level from exceeding the upper limit value PJ. In.

This is because the test range for the high power level PH is narrower than in the conventional case where the power level of the recording light is changed under a fixed ratio. However, test recording is originally performed because the power margin of the low power level PL is narrow, and the main purpose is to obtain an optimum value for the low power level PL instead of the ratio (PH / PL). . Therefore, the first embodiment that allows the ratio (PH / PL) to change and changes the low power level in a desired range can achieve this object.

In short, in the first embodiment, the optimum set value of the power level of the recording light is accurately obtained while preventing the medium from being deteriorated during the test recording. Then, the recording / reproducing apparatus performs stable recording that is hardly affected by a change in external temperature according to the set value. Next, a second embodiment will be described. The second embodiment corresponds to claims 1 and 2.

FIG. 4 shows a CPU 1 according to the second embodiment.
4 is an operation flowchart of FIG. FIG. 5A shows the second embodiment.
High power level P of recording laser light in the embodiment
FIG. 5B is a diagram illustrating a relationship between H and a low power level PL (set value), and FIG. 5B is a diagram illustrating a relationship between the low power level PL and the number of errors in reproduced data. In FIG. 4, the same parts as those in FIG. 2 are denoted by the same reference numerals. Hereinafter, only the portion according to the second embodiment will be described.

In the second embodiment, unlike the first embodiment, the limit power PJb is smaller than the upper limit allowed for the optical disc. For example, in FIG.
b = 9.20 mW. And high power level PH
Of the end power PHEb, which is equal to the limit power PJ in the first embodiment (10.8 m
W). Note that the end power P of this high power level
HEb corresponds to end power PLEb at a low power level.

In the second embodiment, similarly to the first embodiment, the CPU 14 sets the recording power to the starting power (FIG. 5).
(1) (a)) is set (S1). By the way, FIG.
(1) In (a), the starting power level is (PH, PL) =
(8.00 mW, 3.48 mW), and the initial value of the ratio (PH / PL) is 2.30. Then, the CPU 14 sets the range (PH <9.2) until the set high power level PH reaches the limit power PJb.
0 mW), the ratio (PH / PL) is set to the initial value (2.3
The data acquisition (S2 to S6) is repeated while increasing the recording power while keeping 0). This is the same as in the first embodiment.

In the second embodiment, the CPU 14 sets the range (9.20 m) until the set high power level PH reaches the limit power PJb to the end power PHEb.
In the case of W ≦ PH <10.8 mW, the ratio (PH / P
L) is fixed to a value (for example, 2.20) smaller than the initial value, and the test recording S2 is performed while increasing the recording power.
To S5, S7 'and S8' are repeated. That is, the difference from the first embodiment is that PJb smaller than PHE is defined, and within this range, the recording power ratio (PH / P
L) is smaller than the initial value (S7 ′, S7 ′).
8 ').

When the high power level PH becomes the end power PHE (10.8 mW), the CPU 14 proceeds to S9.
, The recording power to be set during normal recording is set to the first
It is determined in the same manner as in the embodiment. In short, in the second embodiment, when the high power level PH to be set is smaller than the limit power PJb (9.20 mW), data acquisition is performed with the slope of the initial value. In a range equal to or more than the limit power PJb and smaller than the end power PHEb, data is acquired with a recording power ratio (PH / PL) smaller than an initial value.

Therefore, the same operation and effect as those of the first embodiment can be obtained. That is, the optimum set value of the power level of the recording light is accurately obtained while preventing deterioration of the medium during test recording. Thereby, the recording / reproducing device
It is possible to perform stable recording which is hardly affected by the external temperature change. Next, a third embodiment will be described. The third embodiment corresponds to claim 1. FIG. 6 is an operation flowchart of the CPU 14 in the third embodiment. FIGS. 7A and 7B are diagrams for explaining test recording in the third embodiment. In FIG. 7, the end power PHE defined by the high power level PH is set to a value (10.8 mW) equal to the limit power PJ in the first embodiment.
And Note that the end power P of this high power level
HE corresponds to the end power PLE at the low power level.

In the third embodiment, steps S5 and S6 in the operation flowchart shown in FIG. 2 are omitted, and the CPU 14 sets the ratio (PH / PH) until the set low power level PL reaches the end power PLE (S7). PL) is reduced and PL is increased (S8 ') to acquire data (S8').
2 to S4), the optimum recording power is determined (S9). In short, in the third embodiment, unlike the above-described second embodiment, the power ratio is changed to be smaller each time the recording power is increased, so that the higher power with respect to the lower power level PL is obtained as shown in FIG. The power level PH is changed in a curved shape.

Further, the CPU 14 determines the recording power ratio (P
H / PL) for each of a plurality of measurement points,
The relationship can be a polygonal line as shown in FIG. The change of the recording power ratio (PH / PL) may be performed any number of times as long as the lower the power level PL, the smaller the ratio. In any case, the same operation and effect as those of the first and second embodiments are obtained.

Next, a fourth embodiment will be described. Book 4
The embodiment corresponds to claim 4. FIG. 8 is an operation flowchart of the fourth embodiment. FIG. 9 is a diagram showing the relationship (set value) between the high power level PH and the low power level PL of the recording laser light in the fourth embodiment. In the fourth embodiment, the end power PHE defined at the high power level PH is set to a value equal to the limit power PJ in the first embodiment. The end power PHE of the high power level PH is equal to the low power level P
L corresponds to the end power PLE.

In FIG. 8, the same parts as those in FIG. 2 are denoted by the same reference numerals. Hereinafter, only the portion according to the fourth embodiment will be described. In the fourth embodiment,
S5 and S6 of the operation flowchart shown in FIG. 2 are omitted,
The CPU 14 keeps the ratio (PH / P) until the set low power level PL reaches the end power PLE (S7).
With L) fixed, the low power level PL is increased (S6 ″) to acquire data (S2 to S4), and the optimum low power level PL1 is determined (S9 ′).

In the fourth embodiment, the ratio (PH / PL) fixed at this time is a value smaller than the initial value of the first to third embodiments. That is, as shown in FIG. 9A, the CPU 14 acquires data at a small inclination. Then, based on the optimum low power level PL1, an optimum high power level PH1 is obtained by calculation (S10). Specifically, the desired relationship between the high power level PH and the low power level PL is, for example, PH / P
If L = 4 (FIG. 9B), the optimum high power level PH1 is obtained as (4 × PL1). This allows
The power margin of the high power level PH is also secured.

In short, at the time of test recording, the recording power is set on the characteristic curve having a small slope shown in FIG. 9A to prevent the optical disk from deteriorating. By setting on the characteristic curve having a large inclination shown in FIG. 9B, stable recording is performed. Further, the fourth embodiment has an advantage that the number of operations is smaller than that of each of the above-described embodiments because the ratio (PH / PL) is fixed at the time of data acquisition.
That is, the operation time for setting the recording power can be shortened.

In each of the above-described embodiments, the measurement points are changed in the order from the lower power level PL to the higher power level PL. However, if the lower limit and the upper limit of the allowable error number range are found, , In any order. In each of the above-described embodiments, the test recording and the reproduction are repeatedly performed. However, after performing the test recording for various low power levels PL, the information recorded in the test recording may be reproduced at a time. .

Further, in each of the above-described embodiments, the number of errors in the reproduced data is obtained as the recording accuracy. However, the deviation of the amplitude of the reproduced signal from the reference value is measured, and the recording accuracy is obtained from the deviation. Good.

In each of the above-described embodiments, the test area to be subjected to test recording is a single area.
However, when the rotation speed of the optical disk is constant, the appropriate recording power differs depending on the radial position of the area where writing is performed. In this case, for example, the test recording of each of the above-described embodiments may be performed for each area of the optical disc having different radial positions, and the optimum setting value of the recording power may be obtained for each of the areas. In another example, the test recording of each of the above-described embodiments is performed in a certain test area of the optical disc to obtain a set value, and then, based on a known relation “the relation of the correction value to the radial position”. Alternatively, a set value of the recording power may be obtained for each area having a different radial position.

In each of the above-described embodiments, the optical disk applied may be, for example, a magneto-optical disk 30 of an optical modulation overwrite type having an initialization layer 35 as shown in FIG. The magneto-optical disk 30 is formed by laminating a magnetic film of a memory layer 32, a recording layer 33, a switching layer 34, and an initialization layer 35 in this order, and does not require a large magnetic field for initialization for a recording / reproducing apparatus. Useful for

FIG. 10B is a diagram showing the temperature characteristics of each layer of the magneto-optical recording medium 30. In FIG. 10 (2),
The horizontal axis and the vertical axis show the temperature and the coercive force of each layer. The Curie temperatures of the memory layer 32, the recording layer 33, the switching layer 34, and the initialization layer 35 are Tcm, Tcw, Tc, respectively.
cs, Tci, memory layer 3 at room temperature To
2. The coercive forces of the recording layer 33, the switching layer 34, and the initialization layer 35 are indicated by Hcm, Hcw, Hcs, and Hci, respectively. In addition, regarding the Curie temperature of each layer, Tcs <
Tcm <Tcw <Tci, and the coercive force of each layer at room temperature is Hcs <Hcw <Hcm <Hc
i.

In the magneto-optical disk 30, the recording magnetic field H
w is set opposite to the magnetization direction of the initialization layer 35, and the temperature is raised to the high process temperature TH or the low process temperature TL, so that the memory layer 32 is initialized.
Or the magnetization direction of the external recording magnetic field Hw. In other words, without modulating the initialization magnetic field, just by modulating the power of the recording laser light,
Information can be recorded in the memory layer 32.

Therefore, the initialization layer 35 shown in FIG.
Needs to always maintain the magnetization direction in the direction opposite to the recording magnetic field Hw. If the initialization layer 35 is heated above the Curie temperature Tci in test recording, the magnetization is reversed by the external recording magnetic field Hw. Therefore, it is considered that the first embodiment described above is applied to the test recording on the magneto-optical disk 30.

FIG. 11 is a diagram for explaining test recording on the magneto-optical disk 30. In FIG. 11, the low power level P
Let the end power PLE specified in L be 4.48 mW,
The limit power PJ specified for the high power level PH is 10.2 mW. First, high power level PH,
The initial value of the low power level PL is 8.00 m each.
W, 3.20 mW (FIG. 11A). The ratio between the high power level PH and the low power level PL (PH /
The reference data is recorded while increasing the high power level PH by 0.2 mW while maintaining PL) at about 2.5. Then, the high power level PH is the value 1 of the limit power PJ.
After reaching 0.2 mW, the value PH is fixed at 10.2 mW, and test recording is performed while raising only the low power level PL until the end power PLE reaches the value of 4.48 mW. As a result, the range of the low power level PL where the number of errors allowed by the reproduction system is 20 or less is (3.36 mW to 4.24 mW) as shown in FIG. 11B, and the high power level PH corresponding to this is set. The range is (8.4 mW to 1
0.2 mW). Therefore, the recording power to be set during normal recording can be determined based on these ranges.

In this test recording, the upper limit value PJ of the high power level PH is set to 10.2 mW. The upper limit value generally indicates the temperature of the magneto-optical disk 30 described above, as shown in FIG. Curie temperature Tc of the passivation layer 35
It does not rise to i. Therefore, according to this test recording, deterioration of the magneto-optical disk 30 can be prevented.

In each of the embodiments described above, the recording power is modulated in accordance with the binary information, but a pulse train recording method may be applied to adjust the size of the recording mark. In a simple binary pulse recording method,
Due to the accumulation of heat, the rear end of the recording mark becomes larger than the front end, so that a so-called teardrop-shaped recording mark is easily formed. However, the problem can be avoided in the pulse train recording method using a pulse having a higher frequency than the bit string. . Hereinafter, the pulse train recording method will be described.

FIGS. 12 and 13 are diagrams showing the change over time of the power of the recording laser light. In FIG.
(2) and (3) show the same data as the pulse shown in (1). In FIG. 1 (2), the high power levels are PH1 and PH1.
In FIG. 1 (3), the low power level further changes to two levels PL1 and PL2.

FIGS. 13 (1), (2) and (3) all show a method of modulating the low level PL power irradiation time at an interval shorter than the bit string. 14 (1) and 14 (2),
A method of modulating the power irradiation time of the high level PH at intervals shorter than the bit string will be described. Also in these pulse train recording methods, it is necessary to surely set the ultimate temperature of the optical disk to the high process temperature TH or the low process temperature TL in order to erase and write the recording marks. In FIGS. 12 to 14, the high power level PH1 and the low power level PL1 determine the ultimate temperature of the optical disk.

Therefore, also in the pulse train recording method, by determining the high power level PH1 and the low power level PL in the same manner as in the above-described embodiments,
Media deterioration can be prevented.

The pulse train recording method is not limited to the above-mentioned waveform, but may be set to any value for the modulation cycle and each level as long as the recording mark is formed in a desired shape.

[0070]

According to the first aspect of the present invention, the increase rate of the high power level of the recording light at the time of test recording is smaller than that of the low power level, so that the maximum value of the power level can be suppressed to be smaller than in the prior art. . Therefore, deterioration of the optical recording medium can be prevented.

According to the second aspect of the present invention, the same test recording as that of the first aspect can be realized by a simple operation. This makes it possible to perform appropriate test recording while suppressing deterioration of the medium more easily than in the first aspect of the present invention. According to the third aspect of the present invention, since the high power level is suppressed to the upper limit or less in the first and second aspects, the deterioration of the optical recording medium can be reliably prevented.

According to the fourth aspect of the present invention, the maximum value of the power level irradiated during test recording can be suppressed, and the difference between the high power level and the low power level can be ensured during normal recording. That is, the degree of deterioration of the optical recording medium can be kept low, and normal recording can be performed stably. According to a fifth aspect of the present invention, there is provided a magneto-optical recording medium of an optical modulation overwrite type.
The inventions described in (1) to (4) are applied. Therefore, the setting of the recording light of the light modulation overwrite method is appropriately performed while preventing the deterioration of the recording medium.

In the invention according to claim 6, the invention according to claims 1 to 5 is applied to the pulse train recording method. Therefore, the setting of the recording light of the pulse train recording method is appropriately performed while preventing the deterioration of the optical recording medium.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a main configuration of a recording / reproducing apparatus.

FIG. 2 is an operation flowchart of a CPU according to the first embodiment.

FIG. 3 is a diagram illustrating test recording according to the first embodiment.

FIG. 4 is an operation flowchart of a CPU according to a second embodiment.

FIG. 5 is a diagram illustrating test recording according to a second embodiment.

FIG. 6 is an operation flowchart of a CPU according to a third embodiment.

FIG. 7 is a diagram illustrating test recording according to a third embodiment.

FIG. 8 is an operation flowchart of a CPU according to a fourth embodiment.

FIG. 9 is a diagram illustrating a relationship (set value) between a high power level PH and a low power level PL of a recording laser height according to a fourth embodiment.

FIG. 10 is a diagram illustrating a magneto-optical disk having an initialization layer. FIG. 1A is a conceptual diagram of a magneto-optical disk having an initialization layer, and FIG. 2B is a diagram illustrating the relationship between the temperature of each layer and the coercive force.

FIG. 11 is a diagram illustrating test recording on the magneto-optical disk 30.

FIG. 12 is a diagram showing a temporal change in power of a recording laser beam.

FIG. 13 is a diagram showing a temporal change in power of a recording laser beam.

FIG. 14 is a diagram showing a temporal change in power of a recording laser beam.

FIG. 15 is a diagram illustrating a light modulation overwrite method.

FIG. 16 is a diagram illustrating a conventional test recording.

FIG. 17 is a diagram showing a temporal change in power of a recording laser beam.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Optical disk 11 Optical head 12 Recording waveform generation circuit 13 Laser diode drive circuit 14 Central processing unit 15 Memory 30, 140 Magneto-optical disk 32 Memory layer 33 Recording layer 34 Switching layer 35 Initialization layer 141 Recording laser beam 142 Memory layer 143 Recording layer

Claims (6)

[Claims] 1. An optical recording method for performing recording by irradiating at least a binary modulated recording light of a low power level PL and a high power level PH, wherein a test recording is performed on a predetermined area of an optical recording medium. Procedure 1 for recording reference information, Procedure 2 for obtaining a reproduction signal of the reference information from the predetermined area of the optical recording medium, and changing the power level (PL, PH) of the recording light to various values By performing Procedure 1 and Procedure 2, the power level (PL1, PH1) of the recording light during normal recording
In the optical recording method having the step 3 of determining 1), when the power level of the recording light is changed in the step 3, the ratio of the value PH to the value PL is set to be smaller as the value PL is larger. Characteristic optical recording method. 2. The optical recording method according to claim 1, wherein when the power level of the recording light is changed in the step 3, if the value PL is smaller than a predetermined value, the ratio of the value PH to the value PL. Is set to a constant value, and when the value PL is equal to or greater than the predetermined value, the ratio of the value PH to the value PL is set to a constant value smaller than the constant value. 3. The optical recording method according to claim 2, wherein when the power level of the recording light is changed in the step 3, if the value PL is smaller than a predetermined value, a ratio of the value PH to the value PL. Is set to a constant value, and when the value PL is equal to or greater than the predetermined value, the value PH is set to a constant value equal to the product of the predetermined value and the constant value. 4. An optical recording method for performing recording by irradiating at least binary recording light of a low power level PL and a high power level PH, wherein the test recording is performed in a predetermined area of an optical recording medium. Procedure 1 for recording reference information, Procedure 2 for obtaining a reproduction signal of the reference information from the predetermined area of the optical recording medium, and changing the power level (PL, PH) of the recording light to various values By performing Procedure 1 and Procedure 2, the power level (PL1, PH1) of the recording light during normal recording
In the optical recording method including the step 3 of determining 1), in the step 3, the power level ratio PH at the time of the change is changed.
An optical recording method characterized in that PH1 and PL1 having a ratio larger than / PL are determined as power levels of recording light during normal recording. 5. The optical recording method according to claim 1, wherein the optical recording medium is a magneto-optical recording medium to which a light modulation overwrite method is applied. Optical recording method. 6. The optical recording method according to claim 1, wherein the test recording and the ordinary recording modulate the recording light at a frequency higher than a frequency corresponding to a bit string. An optical recording method characterized by a pulse train recording method.