JPH0687322B2 - Magneto-optical disk initialization method - Google Patents

Description

DETAILED DESCRIPTION [Overview] At the same time as irradiating the entire surface of a magneto-optical disk with flash light to heat a magnetic material of a recording film to the vicinity of the Curie point,
A magnetic field larger than the coercive force of the magnetic material at this temperature is applied in the direction perpendicular to the film surface of the magnetic material, whereby the magnetization direction of the magnetic material is applied to the film surface without damaging the pregroup pattern and the substrate. Align vertically.

[Industrial application field]

 The present invention relates to a magneto-optical disk initialization method.

[Conventional technology]

As shown in FIG. 2, the magneto-optical disk records information by changing the magnetization direction of the perpendicular magnetization recording film 1 upward or downward. It is considered that the magnetization direction of the recording film immediately after its formation is not uniform as shown in FIG.
It is necessary to align the magnetization direction upward or downward before recording. To align the magnetization directions, a magnetic field larger than the coercive force of the magnetic substance of the recording layer may be applied in the direction perpendicular to the recording film surface. However, the TbFeCo alloy, which is a typical magnetic material, has a large coercive force of 6KOe at room temperature of 25 ° C in the one shown in Fig. 4, so in order to apply a magnetic field larger than this, the magnetic field generator is the target recording material. It's huge compared to a disk, so it can't actually be done.

In general, magnetic materials have zero coercive force at the Curie temperature. In the case of the TeFeCo alloy shown in FIG. 4, the Curie point Tc is 190 ° C., so that the magnetization directions can be aligned even if a small magnetic field is applied near this temperature. However, as shown in FIG. 5, the TbFeCo alloy recording film 1 is formed on a pre-groove 3 formed on a plastic substrate 2 such as polycarbonate.
Therefore, when heated to around 200 ° C, the pregroove 3
The shape of is damaged. The recording film 1 is usually sandwiched by the protective film 4.

Conventionally, avoiding heating the entire substrate to around 200 ° C., the target track on the pre-groove 3 is irradiated with a laser beam to locally heat the TbFeCo alloy recording film 1 and apply a magnetic field to it. Was applied and the irradiation area of the laser beam was moved along the track for initialization. This takes time and effort.

[Problems to be solved by the invention]

There was no easy and quick way to initialize the magneto-optical disk.

[Means for solving problems]

The above problem is that the entire surface of the magneto-optical disk is irradiated with flash light, whereby the magnetic material of the recording film is heated to a temperature at which its coercive force is 1 kOe or less without damaging the pre-groove pattern and the substrate, and This can be solved by a method of initializing a magneto-optical disk, which is characterized in that a magnetic field larger than the coercive force of the magnetic material is applied in a direction perpendicular to the film surface of the magnetic material.

A xenon lamp is convenient as the light source of the flash light.

〔Example〕

A magneto-optical disk 5 having a recording film 1 of 25 wt% Tb, 13 wt% Co and the balance Fe alloy deposited on a polycarbonate substrate 2.
Is placed on the Sm—Co based permanent magnet 6 as shown in FIG. This magnet can apply a magnetic field of 2 kOe to the magneto-optical disk. The above tbFeCo alloy has a coercive force of 25 at room temperature.
Since it is 6KOe at ℃, it cannot change the magnetization direction at room temperature.

Using a xenon lamp 7 with an output of 2000 J and a light emission time of 100 ms as a light source, and using an Al-coated reflecting mirror 8, a magneto-optical disk
The TbFeCo alloy film momentarily exposed to
Since it is heated to around 0 ° C. and the coercive force at that time is reduced to 1 kOe or less, the magnetic field of the Sm—Co based magnet 6 aligns the magnetization directions of the TbFeCo alloys and initializes the disk. At this time, there is no problem of deformation of the polycarbonate substrate, especially the pregroove.

By this initialization, a noise bell reduction of 11.2 dB was observed compared to immediately after film formation, which indicates that the random magnetization direction became uniform.

〔The invention's effect〕

Even if a plastic substrate is used, a magneto-optical disk having a high coercive force can be initialized in a short time with a simple device.

[Brief description of drawings]

FIG. 1 is an explanatory view of an apparatus for carrying out an initialization method of a magneto-optical disk of the present invention, FIG. 2 is a schematic view showing a magnetization direction of a perpendicular magnetization recording layer, and FIG. FIG. 4 is a schematic view showing a magnetization direction of the film of FIG. 1 before conversion, FIG. 4 is a graph showing a temperature-coercive force relationship of the TbFeCo alloy, and FIG. 5 is a sectional view of a magneto-optical disk. 1 ... TbFeCo recording film, 2 ... Polycarbonate substrate, 3 ... Pregroove, 4 ... Protective film, 5 ... Magneto-optical disk, 6 ... Magnet, 7 ... Xenon lamp, 8 ... Reflecting mirror.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuki Naito 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa, Fujitsu Limited (72) Inventor, Seiji Okada 1015 Kamedota, Nakahara-ku, Kawasaki, Kanagawa Prefecture, Fujitsu Limited ( 56) References JP-A 61-182652 (JP, A) JP-A 61-210549 (JP, A) JP-A 59-34618 (JP, A) JP-A 62-298046 (JP, A)

Claims (2)

[Claims] 1. The entire surface of a magneto-optical disk is irradiated with flash light, and the magnetic material of the recording film is heated to a temperature at which its coercive force is 1 kOe or less without damaging the pre-groove pattern and the substrate. A method for initializing a magneto-optical disk, which comprises applying a magnetic field larger than the coercive force of the magnetic body in the direction perpendicular to the film surface of the magnetic body. 2. The method according to claim 1, wherein the light source of the flash light is a xenon lamp.