JPH03203845A - Initializing method for magneto-optical disk - Google Patents

Abstract

PURPOSE:To shorten the initialization time of a magneto-optical disk and to facilitate the initializing operation by irradiating the magneto-optical disk provided in the rotating state with light energy and applying a magnetic field to a magnetic recording film in the temperature raised state to uniformize the direction of magnetization. CONSTITUTION:The magneto-optical disk is provided in the rotating state, and a prescribed area in the radial direction of the magneto-optical disk is irradiated with light energy, and finally, the temperature of the whole of the magnetic recording film of the magneto-optical disk is raised to a prescribed value at a time or successively to reduce the coercive force throughout at a time or successively. When the coercive force of the magnetic recording film is reduced, the direction of magnetization is easily uniformed even with a relatively weak magnetic field. In this case, the magnetic recording is magnetized throughout in one direction. Thus, the direction of magnetization of the magnetic recording film including guide grooves which are not related to information recording of a magneto-optical memory element is uniformized, and noise is prevented from being mixed in recording and reproduced signals. Thus, the initialization time of the magneto-optical disk is shortened and the initializing operation is facilitated.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is directed to a magneto-optical disk in which information can be recorded, reproduced, and erased using light such as a laser beam, in which the direction of magnetization in the magnetic recording film is uniform. The present invention relates to a method for initializing a magneto-optical disk in which the disk is aligned in the same direction.

[Conventional technology]

Magneto-optical disks are expected to develop in the future as large-capacity memories in which information can be rewritten. As shown in FIG. 3, a magneto-optical disk is basically a disk in which a magnetic recording film 2 is formed by sputtering or the like on a transparent substrate 1 made of glass or polycarbonate, and is used to actually store information. Before recording, it is necessary to initialize the spontaneous magnetization M of the magnetic recording film 2 by aligning it in one direction perpendicular to the film surface.

Therefore, in the conventional initialization process, the coercive force (H6
), a method was adopted in which the direction of magnetization M was forced to be unidirectional by applying a magnetic field H stronger than that of the magnetic field H.

[Problem to be solved by the invention]

Incidentally, as the magnetic recording film 2 described above, a film made of rare earth metals and transition metals is mainly used. The rare earth transition metal film is a ferrimagnetic material in which the spins of rare earth and transition metal atoms are aligned antiparallel. It is known that a ferrimagnetic material forms a perpendicularly magnetized film suitable for a magneto-optical memory element near a compensation point where adjacent spins cancel each other out.

However, in this nearby structure, the coercive force becomes very large, typically between 10 KOe and 20 KOe. It also has the characteristic that the coercive force changes significantly even with a slight change in the nearby structure. For this reason,
The magnetic field generating device described above is required to be capable of generating a very strong magnetic field H of 10 KOe to 20 KOe or more.

Moreover, it is difficult to form the magnetic recording film 2 uniformly over its entirety, and even when the film is formed aiming at the above-mentioned compensation point, a part of the film structure may differ from the film structure at the above-mentioned compensation point. Usually, the neighboring tissues are shifted by about 1 to 2%. Even if there is a deviation of only 1 to 2%, the coercive force in the surrounding tissue often changes by 5 to 10 KOe.
If there is a portion having such a neighboring structure, a problem arises in that even when a strong magnetic field H is applied from the outside, there will be a portion where the magnetization M is not aligned in one direction.

Furthermore, ferrimagnetic materials have a characteristic that their coercive force decreases as the temperature increases. Recording and erasing of information in a magneto-optical memory element utilizes this property, and it is conceivable to use this property to perform an initialization process of the magneto-optical memory element. That is, by performing a normal erasing operation using a magneto-optical drive, the magnetization direction of the heated portion irradiated with the light beam can be aligned in one direction. However, since the above-mentioned light beam is focused by a lens to a diameter of about 1 μmΦ, it is extremely difficult to erase information from the entire surface of the magneto-optical memory element. For this reason, it is conceivable to erase only the inside of the recording guide groove where the information is recorded. This method is extremely useful because it can also be used to inspect the quality of the recording guide groove and film defects.

However, in such a method, the direction of magnetization M is still not aligned in the guide groove that is not involved in recording information, and noise is generated in the recorded/reproduced signal due to the unevenness of magnetization M. It has the disadvantage of being intrusive. Furthermore, since a laser light source that irradiates a light beam has a relatively short lifespan, the number of magneto-optical disks that can be initialized by one laser light source is small, resulting in high initialization costs.

Note that it is also possible to align the direction of magnetization M in the guide groove in one direction by the above method, but for this purpose,
Since the guide groove is also irradiated with the light beam, it takes twice as much time. Furthermore, since the guide groove has an uneven relationship with the recording guide groove, it is necessary to apply a servo opposite to that of the recording guide groove, and the polarity of the servo must be reversed. This will cause inconvenience.

[Means to solve the problem]

In order to solve the above-mentioned problems, a method for initializing a magneto-optical disk according to the present invention is a method for initializing a magneto-optical disk in which the direction of magnetization of a magnetic recording film is aligned in one direction. Light energy is irradiated to at least a predetermined area extending in the radial direction of the magneto-optical disk provided on the disk, and this light energy is absorbed by the magnetic recording film to increase its temperature. It is characterized by applying a relatively weak magnetic field to the magnetic recording film from the outside to align the direction of magnetization in one direction.

[For production]

According to the above configuration, the magneto-optical disk is provided in a rotating state, and the optical energy is irradiated to at least a predetermined area extending in the radial direction of the magneto-optical disk, so that the magneto-optical disk is finally The temperature of the entire magnetic recording film is raised to a predetermined temperature at the same time or in sequence, and the coercive force is decreased throughout the entire magnetic recording film at the same time or in sequence.

When the coercive force of the magnetic recording film decreases, the direction of magnetization is easily aligned in one direction even with a relatively weak magnetic field. Moreover, since the magnetization is made in one direction over the entire magnetic recording film, it is possible to make the magnetization in one direction including the inside of the guide groove that is not involved in recording information in the magneto-optical memory element. Problems such as noise entering can be resolved. Furthermore, compared to the case of initializing with a laser beam without tracking, the initialization time of the magneto-optical disk can be shortened and the initialization operation can be made easier.

Furthermore, it is not necessary to use a laser light source with a short life as a means for irradiating light energy, and for example, a halogen lamp with a relatively long life can be used. A magnetic disk can be initialized. Furthermore, since the magneto-optical disk is rotated, it is not necessary to irradiate the entire magneto-optical disk with optical energy at once, and the means for irradiating optical energy can be downsized.

[Example 1] An example of the present invention will be described below based on FIGS. 1 and 2.

As shown in FIG. 1, the device used to carry out the magneto-optical disk initialization method includes a halogen lamp 5 which is a means for irradiating optical energy onto the magneto-optical disk 3.
, a magnetic field generator 6 which is a means for applying a magnetic field to the magneto-optical disk 3, and a disk rotation motor 4 which rotationally drives the magneto-optical disk and the disk 3.

As shown in FIG. 2, the halogen lamp 5 is long in the radial direction of the magneto-optical disk 3, and is adapted to irradiate light energy onto a predetermined area extending in the radial direction.

The magnetic field generator 6 is composed of an electromagnet that generates a relatively weak magnetic field H of approximately 100 to 50,000 e, for example, and generates the magnetic field H in the thickness direction (perpendicular direction) of the magneto-optical disk 3.
can be generated and applied to a predetermined area extending in the radial direction of the magneto-optical disk 3. A fixing means 7 for supporting and fixing the magneto-optical disk 3 is provided at the tip of the rotating shaft 4a of the disk rotation motor 4.

To initialize the magneto-optical disk 3, while the magneto-optical disk 3 is rotated at a relatively high rotational speed by the disk rotation motor 4, a halogen lamp 5 is used to apply light to a predetermined area in the radial direction of the magneto-optical disk 3. irradiate light energy. The light from the halogen lamp 5 reaches the magnetic recording film 3a of the magneto-optical disk 3, and the fact that the magneto-optical disk 3 is rotating and the optical energy is applied to a predetermined area extending in the radial direction of the magneto-optical disk 3. By being irradiated with
The temperature of the whole of a rises to 80° C. at the same time, and the coercive force decreases at the same time over the whole. and,
When the coercive force has decreased in this way, the magnetic field generator 6 generates a magnetic field. This magnetic field is applied to a predetermined area extending in the radial direction of the magneto-optical disk 3, but since the magneto-optical disk 3 is rotating, the magnetic field is sequentially applied to the entire area of the magnetic recording film 3a.

When the coercive force of the magnetic recording film 3a decreases, the direction of magnetization is easily aligned in one direction even by the above-mentioned relatively weak magnetic field H. Moreover, while the magnetization is made in one direction over the entire area of the magnetic recording film 3a, it is possible to make the magnetization in the same direction even in the guide grooves that are not involved in recording information on the magneto-optical disk 3.・It is possible to eliminate problems such as noise entering the reproduced signal. Further, as described above, the initialization is completed in about one minute, and the initialization time of the magneto-optical disk 3 can be shortened and the initialization operation can be facilitated.

Furthermore, it is not necessary to use a laser light source with a short life as a means for irradiating light energy, and for example, a halogen lamp 5 or the like with a relatively long life is used, so a single light energy irradiation means can produce a large number of sheets. A magneto-optical disk can be initialized. Furthermore, by rotating the magneto-optical disk 3, it is not necessary to irradiate the entire magneto-optical disk 3 with optical energy at once, and the halogen lamp 5 can also be made smaller.

[Example 2] Other embodiments of the present invention will be described as follows.

In this embodiment, the initialization is completed by simply rotating the magneto-optical disk 3 once. In other words, when a predetermined area of the magneto-optical disk 3 passes above the λ rogen lamp 5 once, the magnetic recording film of the passing portion becomes 80''.
The magneto-optical disk 3 is rotated at a rotation speed that raises the temperature to C, or the light irradiation energy of the halogen lamp 5 is adjusted.

In this case, the magnetic field generator 6 is replaced by a halogen lamp 5.
The magnetic field generator 6 sequentially sets the magnetization M of the magnetic recording film 3a in the heated portion in a constant direction. As a result, when the magneto-optical disk 3 completes one rotation, the entire magnetic recording film 3a is initialized. That is, the temperature of the entire magnetic recording film of the magneto-optical disk 3 is sequentially raised to sequentially lower its coercive force, and the portions where the coercive force is lowered are initialized in order.

In this embodiment, the halogen lamp 5 is used as a means for irradiating light energy, but the present invention is not limited to this, and an infrared heater or the like may be used. In addition, although the magnetic field generator 6 that generates the magnetic field H is equipped with an electromagnet,
A permanent magnet or the like may be used instead of this, and its specific form is not limited. Furthermore, in this embodiment, the magnetic field generator 6 applies the magnetic field only to a predetermined area extending in the radial direction of the magneto-optical disk 3 in order to reduce the size of the magnetic field generator 6.
The range of magnetic field application may be widened so that the magnetic field is simultaneously applied to the entire area. Furthermore, a halogen lamp 5 is provided on the side of the magnetic recording film 3a of the magneto-optical disk 3;
This halogen lamp 5 is connected to the transparent substrate 3 of the magneto-optical disk 3.
Even if it is provided on the b side, the optical energy passes through the transparent substrate 3b and reaches the magnetic recording film 3a, so it is possible to raise the temperature of the magnetic recording film 3a.

〔Effect of the invention〕

As described above, the magneto-optical disk initialization method according to the present invention irradiates optical energy to at least a predetermined area extending in the radial direction of the magneto-optical disk provided in a rotating state. The structure is such that the magnetization is absorbed into the magnetic recording film to raise its temperature, and a relatively weak magnetic field is applied from the outside to the magnetic recording film in this heated state to align the direction of magnetization in one direction.

This reduces noise in recording and playback signals, improving the quality of magneto-optical disks, and reduces the cost of magneto-optical disks by shortening initialization time and facilitating initialization operations. be able to. In addition to this, it is also possible to downsize the means for irradiating light energy.

FIG. 3 is a sectional view of the magneto-optical disk.

3 is a magneto-optical disk, 3a is a magnetic recording film, 3b is a transparent substrate, 4 is a disk rotation motor, 5 is a halogen lamp, 6
is a magnetic field generator.

[Brief explanation of drawings]

1 and 2 show one embodiment of the present invention. FIG. 1 is a side view showing a state in which a magneto-optical disk is rotated while being irradiated with optical energy and a magnetic field is applied thereto. FIG. 2 is a plan view thereof.

Claims (1)

[Claims] 1. In a method for initializing a magneto-optical disk by aligning the direction of magnetization of a magnetic recording film in one direction, the magneto-optical disk is arranged in a rotating state at least in the radial direction thereof. A predetermined area over the area is irradiated with light energy, and this light energy is absorbed by the magnetic recording film to raise its temperature. At the same time, a relatively weak magnetic field is applied from the outside to this heated magnetic recording film. A method for initializing a magneto-optical disk characterized by aligning the direction of magnetization in one direction.