JPH0883446A - Magneto-optical disk driving device - Google Patents

Abstract

PURPOSE: To improve reliability in setting recording and reproducing conditions by performing the erasure of a magnetic domain in which a test recording is executed after setting an erasing condition right after the test recording and minimizing the fluctuation of recording conditions while preventing the magnetic characteristics fluctuation in a test recording area as much as possible. CONSTITUTION: This device is constituted of a magneto-optical disk drive for performing recording and erasing and a magneto-optical disk for forming a recording magnetic domain and has a test area and a data area on the magneto-optical disk. Then, the erasing of the magnetic domain subjected to the test recording must certainly be performed right after the test recording by setting the erasing condition of an optimum value matched with an ambient temp. and a driving situation. Thus, since the recording sensitivity fluctuation of a recording medium due to the reception of the recording and the erasing is not generated and this device is correctly set to a recording condition matched with a use environment, a recording magnetic domain form can always be correctly controlled to be constant. Especially, when executing mark edge recording, since the setting accuracy of an optimum recording condition is increased, the length of the recording magnetic domain is correctly controlled and then a higher density recording is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical disk drive for performing recording / reproducing / erasing using at least a laser beam and an externally applied magnetic field, and more particularly to a magneto-optical disk drive suitable for high density magneto-optical recording.

[0002]

2. Description of the Related Art In recent years, due to the increasing capacity of OS and application software, and the increasing use of recording image data such as CAD and medical information,
There is an increasing need for inexpensive and large-capacity file memory. Optical recording is attracting attention as a response to this. Among them, the first-generation rewritable magneto-optical disk has been commercialized. Further, research and development are being advanced with the aim of further improving the recording density.

As a method for realizing a high density of a disk, 1) a laser having a short wavelength or a lens having a large NA is used to reduce an optical spot size to make a recording magnetic domain small and to close a magnetic domain interval. Therefore, it is known that it is effective to reduce the bit pitch, 2) reduce the track pitch, 3) use the ZCAV or ZCLV method, and 4) use the mark edge recording method.

However, when the ambient temperature changes, when the recording is performed with the same recording power, the recording temperature changes, which may change the shape of the magnetic domain, particularly the length and width.
In particular, the mark edge recording has been extremely disadvantageous. As a publicly known example examined for these problems, Japanese Patent Laid-Open No. 3-22223 is known. In this known example, a method of controlling the shape of the recording magnetic domain formed by correcting the recording conditions has been proposed.

[0005]

According to the above-mentioned conventional technique, it is possible to correct the fluctuation of the external recording condition, but it is not possible to correct the change of the magnetic characteristic of the recording medium. That is,
In the test recording area, the magnetic characteristics may change due to repeated recording / erasing of the test recording.
As a result, even if the detection of the recording and erasing conditions by the test recording is normal, if the magnetic characteristics of the test area change due to repeated recording / erasing, the recording sensitivity in the test area is different from the data recording area. The size of the magnetic domain recorded in the data recording area is different from the expected size, and when the mark edge recording is performed, the edge position cannot be accurately detected, which is an obstacle to higher density.

The object of the present invention is to set erasure in test recording according to the recording sensitivity and environmental temperature of the disk immediately after recording and not to consider the tracking offset of the drive. By making the erase magnetic domain widths equal to each other, fluctuations in the magnetic characteristics of the recording medium are suppressed to a minimum, thereby increasing the reliability for setting the recording conditions by test recording and enabling more accurate mark edge recording. To provide.

[0007]

In order to achieve the above-mentioned object, it is possible to erase a record in a test recording area as much as possible.
It may be controlled so that the laser power is small.

Therefore, at least in magneto-optical recording in which recording or erasing is performed on a disk using a focused laser beam and an externally applied magnetic field, data is recorded or data already recorded is erased. Or, at the start of the operation of the magneto-optical disk drive, or at the time of mounting the disk in the apparatus, at a fixed time interval or immediately before a recording or erasing operation, a predetermined constant area on the disk is used as a reference condition. Alternatively, the laser power is increased or decreased at regular intervals centering on the conditions that have been set up to that point, test recording is performed using a constant pattern, and the test recording is reproduced, and the operating environment temperature and the magneto-optical property of the magneto-optical disk drive are reproduced. Detects recording conditions according to the temperature of the disc,
When a recording magnetic domain having a constant length and width is formed by controlling the recording or erasing power or the recording pulse width by feeding back the result, the magnetic domain of the previous test recording is erased immediately before the test recording. In this case, it is necessary to consider the difference in drive temperature and operating environment temperature, and the erase laser power must be set to the maximum value. On the other hand, when erasing in test recording is performed immediately after test recording, the erase width of the magnetic domain can be set accurately, and unlike the case of the data area, it is not necessary to consider the tracking offset of the drive. The erase magnetic domain width can be set equal, and the erase magnetic domain width can be made narrower than that in the case of data recording and erasing.

As a result, the test-recorded magnetic domains can be erased with the necessary and minimum laser power.
By suppressing the fluctuation of the magnetic characteristics of the recording medium to a minimum, the reliability with respect to the setting of the recording condition by the test recording is increased, and more accurate mark edge recording becomes possible.

[0010]

By reducing the erasing power of the magnetic domains recorded in the test recording, it is possible to suppress the change in the magnetic characteristics due to repeated recording / erasing, and the number of test recordings can be increased, so that the life of the recording medium is improved. be able to. Alternatively, since the frequency of test recording can be increased, data can be recorded under more stable recording conditions.

[0011]

Embodiment An embodiment of the present invention will be described with reference to the drawings. The sectional structure of the magneto-optical disk manufactured in this example is shown in FIG. A disc having a four-layer structure recording medium formed on a polycarbonate substrate 1 having an uneven guide groove was used.
That is, a silicon nitride layer (75 nm) as the first dielectric layer 2, a TbFeCo magneto-optical recording layer 3 (25 nm), a silicon nitride layer (20 nm) as the second dielectric layer 4, and a reflection layer 5 on the substrate 1.
As a result, Al (40 nm) was sequentially manufactured by the sputtering method. Then, a UV-curable resin protective layer 6 was formed on the surface of the recording medium to obtain a disk.

As the recording method, the ZCAV method and the mark edge recording method were used in combination. For example, recording was performed on the innermost track 7 of the disk shown in FIG. 5 while changing the laser power using the test recording pattern shown in FIG. Here, recording was performed in 16 steps while increasing the recording power by 0.1 mW from the low recording power side.

An example of the reproduction output at this time is shown in FIG. 6 (b). As shown in this figure, the difference between the average of the signals of the longest pattern and the average of the signals of the shortest pattern was obtained, and the condition for eliminating the difference was set as the optimum recording condition.

If optimum conditions were not found in the first 16 steps, test recording was continued while further increasing the recording power in 16 steps of 0.1 mW.

Here, the flow of the erase operation of the recorded test signal is shown in FIG. The erasing was performed at 80% of the maximum recording power used for test recording so that the recording magnetic domain width and the erasing magnetic domain width were equal.

Here, the erasing operation of the recorded test signal was compared between the time immediately after the test recording and the time immediately before the test recording. In the latter case, assuming that the drive used for the previous test recording is different, assuming that the track offset is 0.1 μm as in the case of the data section, an erase power that can be erased 0.4 μm more than the recording magnetic domain width is used. Need to irradiate. Further, since the temperature of the disc or both the drive and the disc is not known immediately after the drive is turned on or immediately after the disc is inserted, it is necessary to irradiate the erasing light assuming that the temperature of the drive and the disc is the lowest.

From the relationship between the erasing power and the erasing magnetic domain width of the magneto-optical disk of this embodiment shown in FIG. 2, the latter is 2 compared with the former.
Irradiation power as high as 5% must be applied. Further, from the relationship between the temperature of the magneto-optical disk of the present embodiment shown in FIG. 3 and the erasing power for making the erasing magnetic domain width constant, the minimum operating temperature of the drive is 0 ° C. and the disk temperature during the test is 25 ° C.
In this case, an erasing power as high as 15% must be applied.

Test recording was performed 10 ⁷ times under both conditions,
The deviation of the recording conditions was compared. 10 ^{7 in the} latter case
The recording setting conditions did not change after the test recording was repeated, whereas the recording setting power of the former decreased by about 15%. This is because by repeating recording and erasing, the magnetism of the recording film is changed, the recording sensitivity of the recording film is increased, and a recording magnetic domain larger than that in the initial stage of disc manufacturing is formed.

Next, after performing test recording 10 ⁷ times, data recording was carried out under the conditions found by the test recording.
The edge shift when the signal was reproduced was measured by a time interval analyzer (TIA). The edge shift was less than ± 2 ns when the present example was used, whereas the edge shift was significantly increased to ± 15 ns when erasing was performed by increasing the erasing power at 40%.

[0020]

According to the present invention, in a magneto-optical disk drive for performing highly precise recording control using test recording, recording sensitivity fluctuation of the recording medium due to repeated recording / erasing does not occur, and recording is performed in an operating environment. Since the conditions can be set accurately, the shape of the recording magnetic domain can always be controlled accurately and constantly.
In particular, in the mark edge recording, since the setting accuracy of the optimum recording condition can be improved, the recording magnetic domain length can be accurately controlled, and higher density recording can be realized.

[Brief description of drawings]

FIG. 1 is a simple explanatory diagram showing a flow of operations for erasing test recording and test signals.

FIG. 2 is an explanatory diagram showing a relationship between erase power and erase magnetic domain width.

FIG. 3 is an explanatory diagram showing a relationship between a disc temperature and an erasing power.

FIG. 4 is an explanatory diagram showing a cross-sectional structure of a disc.

FIG. 5 is an explanatory diagram showing an example of a disc format.

FIG. 6 is an explanatory diagram showing a reproduced signal waveform of test recorded information.

Claims (2)

[Claims] 1. At least in magneto-optical recording for recording or erasing on a disk by using a focused laser beam and an externally applied magnetic field, before recording data or erasing already recorded data. Alternatively, at the start of the operation of the magneto-optical disk drive or at the time of mounting the disk in the apparatus, low recording is performed in a predetermined fixed area on the disk at a fixed time interval or immediately before data recording or erasing operation. Recording is performed while gradually increasing the recording power from the power side, and the recording condition is detected from the reproduction signal according to the operating environment temperature of the magneto-optical disk drive and the temperature of the magneto-optical disk, and the result is fed back for recording or When forming a recording domain with a constant length and width by controlling the erasing power or recording pulse width In the magneto-optical disk drive device, the magnetic domain recorded in the test recording is erased as a series of operations immediately after the test recording. 2. The magneto-optical disk drive device according to claim 1, wherein the erasing condition of the magnetic domain subjected to the test recording is performed by using the erasing power obtained by the test recording or an erasing power smaller than the erasing power.