JPH03183049A - Information recording and erasing method for magneto-optical recording media - Google Patents

Abstract

PURPOSE:To enlarge the margin of a reproducing power level and to practically improve the durability of recording by maintaining the optical power level at a required low level during a prescribed period just before/after recording and erasing. CONSTITUTION:Through a bias magnetic field driving circuit 6 and a laser driving circuit 5 to be respectively controlled by a control circuit 4, a bias magnetic field is impressed by an electromagnet 7 and the optical power is impressed by an optical head 3 to execute recording and erasing. Then, reproduction is executed by optical power at a high level. Just before recording and erasing, this circuit 4 switches the power level at a lever lower than the reproducing power level simultaneously when or before the bias magnetic field is activated. Further, even just after recording and erasing, the power level is maintained at the level lower than the similar reproducing power level as well until the activation of the bias magnetic field is reduced. Therefore, a bit pattern to be preserved is prevented from being revealed and degraded at an unnecessarily high temperature in the high magnetic field. Thus, the margin of the reproducing power level is enlarged and the recording durability can be practically improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an information recording and erasing method for a magneto-optical recording medium. [Prior Art] Magneto-optical disks have been put into practical use as rewritable optical disks. The recording and/or erasing of information on this magneto-optical disk and the retention of recorded information utilize the property that the magnitude of the magnetization reversal magnetic field of the perpendicularly magnetized film decreases in areas where the temperature is higher than the ambient temperature. It is done. That is, under a bias magnetic field of an appropriate magnitude, the medium is irradiated with a focused laser beam to locally heat the medium, so that the magnetization of this local region is oriented in the direction of the bias magnetic field.

In the optical modulation method, while the disk is rotating, the recorded area is erased in advance by continuous irradiation with a radar under a bias magnetic field in a fixed direction, and then information is erased under a bias magnetic field in the opposite direction. A modulated laser 'fc nocellus is applied to the magnetic field to form pictographs as a row of reversed magnetic domains.

On the other hand, when reproducing recorded information (magneto-optical signals), when a perpendicularly magnetized film is irradiated with a polarized laser beam, the polarization planes of the reflected and/or transmitted light are in opposite directions depending on the direction of magnetization. The property of rotation is used. At this time, the radar nosower level (Pi) must be moderately strong in order to obtain good reproduction signal quality, and at the same time must be low enough so that heating of the medium by the reproduction laser does not deteriorate the recorded pits. It won't happen.

Conventionally, when the operating state of a magneto-optical disk device is pressed, a laser of a power level (PR) necessary for reproducing the above-mentioned magneto-optical signal is continuously irradiated, and even during recording and/or erasing, the button is pressed. While a bias magnetic field for erasing is being applied, this reproduction/4-power level (PR) laser is irradiated immediately before and after the high-level laser for recording and/or erasing is irradiated.

[Problem that the invention is trying to solve]

However, conventionally, there has been a problem that the above-mentioned reproduction power level (PR) margin is narrow and reproduction durability is insufficient. In particular, immediately before and after recording and/or erasing, there is a delay in the rising and falling of the recording and/or erasing bias magnetic field, so the reproducing power (PR) in the magnetic field is
There was a high risk of deterioration due to regeneration due to heating.

The present invention aims to solve the above-mentioned conventional problems, widen the margin of the reproduction power level, and improve the substantial reproduction durability. And, the laser power level immediately before erasing is switched to a level slightly lower than that of the p4 power level at the same time as or before the recording and/or erasing magnetic field rises. and maintain the laser power level immediately after recording and/or erasing until the execution of erasing, at least at a level lower than the reproduction power level of the magneto-optical signal in a case where the bias magnetic field for recording and/or erasing has sufficiently fallen. This is achieved by the information recording/erasing method of the magneto-optical recording medium of the present invention, which is characterized in that the information recording and erasing method of the magneto-optical recording medium is maintained.

[Effect]

In the operating state of a magneto-optical disk device, it is necessary to constantly irradiate the radar in order to read out preformed information such as sir & information and addresses. However, in general, the control accuracy and noise tolerance of the laser/thrower required at this time are greater than the tolerances required when reading out the magneto-optical signal. If only information or pre-7ohmakt information is to be read out, even if a conventional optical system is used, it is possible to use a wide dynamic range and set a lower i4 power.

Furthermore, conventionally, immediately before and after recording and/or erasing, 5
Since the time of about m5ec was spent seeking the address, there was almost no opportunity to read out the magneto-optical signal. On the other hand, the time required for the rise and fall of the recording and/or erasing bias magnetic field is approximately 5 m5 ec or less.

Based on the above considerations, the present invention sets the current level immediately before recording and/or erasing to be lower than the reproduction level of the magneto-optical signal at the same time as or before the recording and/or erasing bias magnetic field rises. Switch to a lower level and maintain it until recording or/and erasure is performed.
By maintaining the Al power level immediately after erasing at a level lower than the reproduction level of the magneto-optical signal at least until the recording and/or erasing bias magnetic field has sufficiently fallen, the pictograph to be preserved can be kept at a high level. This prevents deterioration due to unnecessary exposure to high temperatures in a magnetic field.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

(Example 1) Laser /? before and after erasing records The quabell and bias magnetic field were set as shown in FIG. Record nosewar P
W, erasure power P II t-6rnWs reproduction power P.

t" 1.5 mW. Also, the recording bias magnetic field Hw1c+4000@, the erasing bias magnetic field Hmt-6
000*. At the same time as starting the application of the bias magnetic field H+ for erasing, the laser beam J? The power level was changed to the power level P8, which is also lower than the reproduction power pi.

/4' power level Psi was set to 0.5 mW. Seek the desired address at power level PI and erase power P1
I executed the deletion. At the same time as erasing is completed, the application of the erasing bias magnetic field HEO is stopped, and then the recording bias magnetic field H is continued.
Application of w was started. The laser z4 power level is maintained at the chinosowar level ps immediately after erasing.
In this state, the erased address was sought and recorded using the recording nose Pw. At the same time as the recording ended, HWO application was stopped, and after the recording was completed, it was maintained at the radar power level tP @ for 5 m + l @ e, and then switched to the playback and 4 warp PR. In this state, the recorded address was sought and the magneto-optical signal was reproduced. In this way, in this embodiment, only before and after erasing recording is the ray-f-i4? War level 7 playback/
I chose Nozewarepel PG, which is lower than Zewar PR in J04.

FIG. 2 is a schematic diagram of an embodiment of a magneto-optical disk recording and reproducing apparatus for implementing the method of the present invention.

In the figure, a disk-shaped recording medium 1 is rotated by a spindle motor 2, and an optical beam 3 irradiates the recording medium 1 with a light beam for recording, erasing, and reproducing information.

The optical hept 3 converts information based on reflected light from the recording medium 1 into an electrical signal and outputs it to the control circuit 4 . The control circuit 4 controls the laser drive circuit 5 based on this electric signal.
It also controls the noise magnetic field drive circuit 6t. Although a method in which the bias magnetic field is controlled by the electromagnet 7 is described here, a method using a mechanical drive of a permanent magnet may also be used.

With the above system υ, it is possible to realize the above-mentioned method.

1 magneto-optical disk divided into 17 sectors,
While rotating at 1800 rpm, one sector of a track with a radius of 30 m was repeatedly recorded and erased using the method of this embodiment described above. At this time, the archival life t of the information previously recorded in the adjacent sector was checked.

As a comparative example, even if the data is written immediately before and after erasing the record, the reproduction no.
A case where a small amount of recording was erased was investigated under the same conditions and method as above, except that the laser beam of 1.5 mW, which is a single level, was continued to be irradiated.

As a result, the device in which recording and erasing was performed using the method of the embodiment of the present invention showed no change in the bit error rate of adjacent sectors even after repeated recording and erasing 109 times, and had good operational durability. was confirmed.

On the other hand, when a small amount of records were erased using the method of the comparative example,
After repeatedly erasing records 10 times, the pit error rate of adjacent sectors worsened by about one digit.

(Example 2) Recording/4' power Pws erasing puff-PI was set to 6 mW, and reproduction power pHl't of the magneto-optical signal was set to 1.5 mW. The power level Pg of the power f-t4, which is applied to other operation modes, was set to 0.5 mW. That is, with the tracking sensor and focus sensor applied to the nose level Ps, the address is sought, the header signal by the phase pictogram is read out, and then the laser power is recorded, the eraser Pw, the eraser Pg, Regenerated nosewarp wing 9
J') and executed the respective operations of erasing → recording → reproducing. Immediately after each operation was completed, the ledenometer level was returned to P. Among them, the recording bias magnetic field HW
, the applied magnetic field level and the method of applying the erasing bias magnetic field H are the same as in the first embodiment described above. This embodiment differs from the first embodiment not only before and after erasing records, but also when erasing and erasing records.
The reason is that the entire period other than the recording/reproducing operation is designated as Warepel PI.

A magneto-optical disk divided into l tracks and 17 sectors is
While rotating at 1800 rpm, one sector of a track with a radius of 30 m was repeatedly recorded and erased using the method of this embodiment. At this time, we investigated the archival life of the information that had been recorded in advance in the adjacent sector.

As a comparative example, the reproduction jl power of the magneto-optical signal is 0.5rn.
W, and the case where υ recording was erased under the same conditions and method as above was investigated, except that the laser of /9 watts was continued to be irradiated immediately before and after erasing the record.

As a result, in the case where υ recording and erasing were performed using the method of the embodiment of the present invention, no change was observed in the bipto error rate of the adjacent sector even after 102 repeated recording and erasing, and good operational durability was observed. It was confirmed that the

On the other hand, when recording and erasing was performed under the conditions and method of the comparative example, although there was no problem in repeat durability, good reproduced signal quality of the magneto-optical signal could not be obtained.

C. Effects of the Invention] As explained in detail above, according to the information recording and erasing method of the present invention, the margin of reproduction power for obtaining good reproduction signal quality and not causing reproduction deterioration is widened, and the margin is substantially improved. This has the effect of improving playback durability.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the laser drive circuit and the bias magnetic field in the process of erasing → recording → reproducing according to the first embodiment. FIG. 2 is a schematic diagram of an embodiment of a magneto-optical disk recording and reproducing apparatus for realizing the method of the present invention. l...Recording medium, 2...Spindle motor 3.
...Optical head, 4...Control circuit, 5...Laser drive circuit, 6...Bias magnetic field drive circuit, 7...Electromagnet.

Claims (1)

[Claims] (1) The power level immediately before recording and/or erasing is switched to a level lower than the reproduction power level of the magneto-optical signal at the same time as or before the recording and/or erasing bias magnetic field rises. A light that is maintained until erasing is executed, and that maintains the power level immediately after recording and/or erasing at a level lower than the reproduction power level of the magneto-optical signal, at least until the bias magnetic field for recording and/or erasing has sufficiently fallen. Information recording and erasing method for magnetic recording media.