JPS63222350A - Method for initialization of magneto-optical disk - Google Patents

Abstract

PURPOSE:To initialize a magneto-optical disk quickly with a simple device by projecting flash light over the entire surface of the magnetic material of a recording film of the disk to heat the surface up to temp. near the Curie point and impressing a magnetic field thereto in the direction perpendicular to the film plane. CONSTITUTION:The magneto-optical disk 5 formed by depositing the recording film by evaporation on a substrate is disposed on a permanent magnet 6. The magnetic material of the recording film is instantaneously heated up to the temp. near the Curie point and the coercive force decreases when the entire surface of the disk 5 is projected by using a xenon lamp 7 and using a reflecting mirror 8. The magnetic field larger than the coercive force of the magnetic material is, thereupon, impressed by the magnet 6 in the direction perpendicular to the film plane, by which the initialization of the disk is executed. Generation of deformation in the substrate and particularly the pregrooves thereof is obviated at this time. The quick initialization of the disk with the simple device is thereby permitted without giving damages to the pregroove pattern and the substrate.

Description

[Detailed Description of the Invention] [Summary] At the same time, the magnetic material of the recording film is heated to near the Curie point by irradiating the entire surface of the magneto-optical disk with flash light.
A magnetic field larger than the coercive force of the magnetic material at this temperature is applied perpendicularly to the film surface of the magnetic material, thereby changing the magnetization direction of the magnetic material relative to the film surface without damaging the pregroove pattern or the substrate. Align vertically.

[Industrial application field]

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

[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 thought that the magnetization direction of this recording film immediately after being deposited is not uniformly aligned, 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 greater than the coercive force of the magnetic material of the recording layer may be applied in a direction perpendicular to the surface of the recording film.

However, the typical magnetic TbFeCo alloy shown in Figure 4 has a coercive force of 6 KO at room temperature of 25°C.
Since e is large, in order to apply a larger magnetic field,
Since the magnetic field generator is huge compared to the target recording disc, this cannot be done in practice.

Generally, the coercive force of a magnetic material becomes zero at the temperature of the Curie point. The TbFeCo alloy shown in FIG. 4 has a Curie point Tc of 190° C., so it is possible to align the magnetization direction even if a small magnetic field is applied near this temperature. However, as shown in the TbFeCo alloy recording film alloy recording film diagram, a pregroup 3 is formed on a plastic substrate 2 such as polycarbonate, and a film is formed thereon.

Therefore, when heated to around 200° C., the shape of the pre-group 3 is damaged. Note that the recording film 1 is usually sandwiched between protective films 4.

Conventionally, to avoid heating the entire substrate to around 200°C, a laser beam was irradiated onto the track on the target pre-group 3 to heat the TbFeCo alloy recording film. Initialization was performed by applying a magnetic field and moving the laser beam irradiation area along the track.This requires time and effort.

[Problem that the invention seeks to solve]

There was no way to initialize a magneto-optical disk easily and quickly.

[Means for solving problems]

The above problem can be solved by irradiating the entire surface of the magneto-optical disk with flash light, thereby heating the magnetic material in the recording film to a temperature near the Curie point without damaging the pregroove pattern or the substrate. This problem can be solved by a magneto-optical disk initialization method characterized by applying a magnetic field larger than the coercive force in a direction perpendicular to the film surface of the magnetic material.

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

〔Example〕

As shown in FIG. 1, a magneto-optical disk 5 on which a recording film l of an alloy of 25% by weight Tb and 13% by weight CO and the balance Fe is deposited on a polycarbonate substrate 2 is placed on a 5s-Co permanent magnet 6. Deploy. This magnet can apply a magnetic field of 2 kOe to the magneto-optical disk. The above TbFeC
O alloy has a coercive force of 6 kOe at room temperature of 25° C., so the direction of magnetization cannot be changed at room temperature.

When a xenon lamp 7 with an output of 2000 J and a light emitting time of 10 S is used as a light source, and the magneto-optical disk 5 is irradiated using a /l coated reflector 8, the TbFeCo alloy film is instantaneously heated to around the Curie point of 190°C. At that time, the coercive force decreases to less than l kOe, so the magnetization direction of the TbFeCo alloy is aligned by the magnetic field of the 5s-Co magnet 6, and the disk is initialized. At this time, the problem of deformation of the polycarbonate substrate, especially its pregroup, does not occur.

Due to this initialization, it was observed that the noise bell was reduced by 11.2 dB compared to immediately after film formation, which indicates that the random magnetization direction became uniform.

〔Effect of the invention〕

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 explanation of drawings]

FIG. 1 is an explanatory diagram of an apparatus for implementing the magneto-optical disk initialization method of the present invention, FIG. 2 is a schematic diagram showing the magnetization direction of the perpendicular magnetization recording layer, and FIG. FIG. 4 is a graph showing the relationship between temperature and coercive force of the TbPeCo alloy, and FIG. 5 is a cross-sectional view of the magneto-optical disk. 1...-TbFeCo recording film, 2... Polycarbonate substrate, 3... Pre-group, 4... Protective film, 5... Magneto-optical disk, 6... Magnet, 7... Xenon lamp, 8...Reflector. Initialization method of magneto-optical disk Fig. 1 Perpendicular magnetization recording film Fig. 2 Recording film before initialization Fig. 4 Fig. 4 1... Recording film 5... Magneto-optical disk 4... Protective film 8. ...Cross-sectional view of a reflective magneto-optical disk Figure 5

Claims (1)

[Claims] 1. The entire surface of the magneto-optical disk is irradiated with flash light, thereby heating the magnetic material of the recording film to a temperature near the Curie point without damaging the pregroove pattern or the substrate. A method for initializing a magneto-optical disk, the method comprising: applying a magnetic field greater than the coercive force of the magnetic material in a direction perpendicular to the film surface of the magnetic material. 2. The method according to claim 1, wherein the light source of the flash light is a xenon lamp.