JPS63282946A - Magneto-optical recording method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an improvement in a magneto-optical recording method using a magnetic field modulation method.

The conventional magneto-optical recording method involves applying a magnetic field in a fixed direction to a magneto-optical recording medium (basically a transparent substrate with micro grooves for guide tracks and a magnetic recording layer), while applying a laser beam. There are two types: an optical modulation method that applies a blinking signal, and a magnetic field modulation method that applies a magnetic field signal while continuously irradiating the recording medium with laser light. Currently, the optical modulation method is the mainstream, but from the point of view of override (immediately recording after erasing), the magnetic field modulation method% method%. Both the 1 signal and the 0 signal are recorded under the same conditions. If the areas between the recording tracks of the recording layer are magnetized uniformly (only in one direction), a certain amount of information between these tracks is also read out during reading, so the reproduced signal is biased to a DC bias. This can lead to a high error rate. Also, during recording, even if the 1 signal and the O signal are equally reversed, the magnetic field created by the magnetization of the recording layer between the recording tracks is applied to the recording area, and the direction of the magnetization is the same as the direction of the magnetization between the recording tracks. There is a difference in the magnetic field applied to the actual recorded portion when recording in one direction and when recording in the opposite direction, and as a result, an imbalance occurs in the recording of each signal, which also causes an increase in the error rate.

Object The object of the present invention is to provide a magneto-optical recording method using a magnetic field modulation method, which reduces the error rate by eliminating the influence on the signal due to the magnetization direction of the portion between recording tracks of the recording layer.

Structure The magneto-optical recording method of the present invention is a magneto-optical recording method in which a magnetic field signal is applied while continuously irradiating a laser beam to a magneto-optical recording medium in which a magnetic recording layer is provided on a transparent substrate with micro grooves for guide tracks. Figure 1 (In the figure, 1 is a recording layer, 2 is a transparent substrate, 3 is a recording track, 4 is a guide track, 5 is a recording layer, 2 is a transparent substrate, 3 is a recording track, 4 is a guide track,
゜6 is a portion between recording tracks) As shown in FIG.
This is characterized in that the magnetization directions (indicated by arrows) of No. 6 are reversed for each track. There is no problem if the recording tracks are concentric, but if they are spiral, "for each track" means "J for each round of the track."

In the method of the present invention, when recording on a magneto-optical recording medium using the magnetic field modulation method, as described above, by reversing the magnetization direction of the portion between each recording track of the recording layer, the right side and left side of each recording track are The direction of magnetization is reversed, and regardless of whether digitally recorded signals 1 and 0 correspond to upward or downward magnetization, both will always be under the same conditions after recording (see Figure 2).

In order to mutually reverse the magnetization direction of the portion between each recording track in a magneto-optical recording medium, for example, as shown in FIG.
10 is a 174 wavelength plate, 11 is an objective lens, 12 is a half mirror, 113 is a knife lens, 14.16 is a two-split photodiode, 15 is an amplifier for focus error, 17
An ordinary magneto-optical recording device (denoted as a tracking error amplifier, 18 as a magnet, 19 as a magneto-optical disk with a guide track, and 20 as a motor) may be operated as follows. That is, first, adjustment is made so that the laser beam is irradiated onto the intermediate portion between the recording tracks of the magneto-optical disk 19. Note that the laser beam is reflected from the laser light source 7 at right angles by the mirror 8, passes through the polarizing beam splitter 9 and the wave plate 10, and is further focused by the lens 11. This laser beam is continuously irradiated to the intermediate portion of the magneto-optical disk 19 with normal recording power, and at the same time, the irradiated portion is magnetized while reversing the direction of the magnetic field from the back of the magneto-optical disk 19 for each track. Let's do it.

Next, in order to record on a magneto-optical disk in which the magnetization direction of the portion between each recording track is reversed, first, the laser beam is adjusted so that it is irradiated onto the recording track, and then the laser beam is irradiated as before. It is sufficient to continuously irradiate the recording track of the magneto-optical disk 19 with a normal recording power and at the same time apply a magnetic field signal to the irradiated portion using the magnet 18 to perform magnetization in accordance with the signal. Note that the reproduction method is exactly the same as before.

The magneto-optical recording medium used in the method of the present invention is basically a rare earth transition metal amorphous alloy, magnetoplum, on a transparent substrate such as a plastic or glass plate having micro grooves for concentric or spiral guide tracks. Ordinary materials provided with a recording layer made of a magnetic material such as bite ferrite, Co-spinel ferrite, Bi-substituted garnet, etc. can be used.

The present invention will be explained below by way of examples.

EXAMPLE A magneto-optical disk 19 (a recording layer made of a TbFcCo amorphous alloy film and a protective layer made of Si3N on a glass substrate having a microgroove for a spiral guide track) was set in the apparatus shown in FIG. After adjusting the laser beam to be irradiated to the intermediate portion between the recording tracks of the disk, the intermediate portion is continuously irradiated with a 20 mW laser beam at a disk linear velocity of 25 m1 second, and at the same time, this irradiated portion is magneto-optically applied. Magnetization was performed for each track from the back of the disk 19 using a magnet 18 at a magnetic field strength of 2000 e while reversing the direction of the magnetic field.

Next, the magneto-optical disk with the magnetization direction of the portion between each recording track reversed is used in the recording/reproducing apparatus shown in FIG. 4 (in the figure, 21 is a semiconductor laser, 22 is a collimator lens,
23 is a mirror, 24, 26, 27 are half mirrors 1
25 is an objective lens, 28.32 is a two-split photodiode, 29 is a track error amplifier, 30 is a spot lens, 31 is a knife lens, 33 is a focus error amplifier, 34 is a 172 wavelength plate, and 35 is a polarizing beam splitter 136a. .

36b is a photodiode, 37 is an RF signal amplifier,
38 is an electromagnet, 40 is a spindle motor, and 41a.

41b is a spot lens), and this disc 1
After adjusting so that the laser beam is irradiated onto the recording track No. 9, the recording track portion is heated at a disc linear velocity of 3 m/min.
Recording was performed by applying a magnetic field signal from the electromagnet 38 while continuously irradiating a laser beam of 5IIIll per second.

Next, when the thus recorded magneto-optical disk 19 was reproduced by irradiating a laser beam of 1 mW, the error rate was 10-S%.

On the other hand, for comparison, recording and reproduction were performed in the same manner except that the direction of magnetization of the intermediate portion was not reversed for each track, and the error rate was 10-4%.

Effects As described above, in the method of the present invention, in magneto-optical recording using the magnetic field modulation method, the magnetization directions of the portions of the recording medium between the recording tracks are reversed for each track in advance, so that the magnetic field of the recording layer between the tracks is D of the reproduced signal depending on the direction of magnetization
This method has the advantage that the C bias and the unbalance of the magnetic field when recording 1,0 signals are eliminated, and therefore the error rate is significantly lower than that of the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the magnetization direction of the portion between each recording track of the magneto-optical recording medium after the preliminary step in the method of the present invention;
Fig. 2 is a state diagram when magnetic field modulation recording is performed on the magneto-optical recording medium shown in Fig. 1, and Fig. 3 is an example of an apparatus for forming the magnetization direction as shown in Fig. 1 on the magneto-optical recording medium. 4 are diagrams of an example of an apparatus for recording and reproducing according to the method of the present invention. 1... Magnetic recording layer 2... Transparent substrate with micro grooves for guide track 3...
Recording track 4... Guide track 5.6...
Portion between recording tracks 7... Laser light source 18... Magnet 19... Magneto-optical disk

Claims (1)

[Claims] 1. In a magneto-optical recording method in which a magnetic field signal is applied while continuously irradiating a laser beam to a magneto-optical recording medium in which a magnetic recording layer is provided on a transparent substrate with micro grooves for guide tracks,
A magneto-optical recording method characterized in that the magnetization directions of the portions of the recording layer between the recording tracks are reversed for each track in advance.