JPH0410259A - Method and device for magnetizing magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To arrange the direction of magnetizing an entire magnetic film to a fixed direction in a short time by heating a magnetic film side roll, among a pair of rolls for conveying a base having the magnetic film on one side, at a high temperature and impressing a magnetic field to the heated magnetic film. CONSTITUTION:Among a pair of rolls 24 and 26 for conveying a base 12 having a magnetic film 14 on one side, the roll 24 on the side of the magnetic film 14 is incorporated with a heater and held at the prescribed high temperature higher than 100 deg.C, and the magnetic film 14 is heated by getting the roll 24 in contact with the magnetic film 14 of the base 12. Thus, the coersive force of the magnetic film 14 is lowered and when the magnetic field is impressed, the magnetization in the magnetic film 14 directed at random is easily made parallel to the direction of the impressed magnetic field. Then, the magnetizing direction of the entire magnetic film 14 can be fixed in a short time. In this case, when the magnetic field is impressed to the magnetic film 14 by magnets 28 and 30 provided on the surface of a pair of rolls 24 and 26, the magnetizing direction can be put in order while heating the magnetic film 14, and the processing can efficiently be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for magnetizing a magneto-optical recording medium suitable for uniformly magnetizing a magnetic film made of a magneto-optical recording material.

[Conventional technology]

Magneto-optical disks, which are magneto-optical recording media, are designed to read out information by irradiating a magnetic recording film with laser light and detecting the reflected laser light, making it possible to record large amounts of information. Since it is possible to rewrite data without contact, it is being actively developed in various fields. Various studies have been conducted regarding the composition of magnetic films that record information, and it has been found that materials with a large coercive force (Hc) near room temperature can improve recording density and provide good results in read and write characteristics. It is being

A rare earth-transition metal magnetic film is an example of a magnetic film having such a high coercive force. For example, Tb-FecoM using Tb as a rare earth metal and Fe and Co as transition metals! The coercive force Hc of the L film at room temperature varies depending on the Tb concentration as shown in FIG.

That is, in a magnetic film made of Tb-FeCo, when the concentration of Tb exceeds 15 at%, the coercive force increases rapidly.
The coercive force reaches its peak when the Tb concentration is approximately 23 at%, and when the Tb concentration exceeds approximately 23 at%, the hysteresis loop of the Kerr rotation angle changes from counterclockwise to clockwise, and Tb - The coercive force of the FeCo magnetic film shows a change that decreases rapidly. Therefore, if a TbFeCo magnetic film with a Tb concentration of about 22 to 24 atomic % is used, the coercive force can be changed to about 15 kOe at room temperature.

This magnetic film (recording film) made of rare earth-transition metals is generally formed by sputtering, and it is difficult to align the direction of magnetization of the magnetic film in a constant direction during film formation.
The direction of magnetization is random. If there are parts of the magneto-optical disk where the magnetic domains have different directions between the tracks, this will cause noise, albeit slightly. Therefore, it is desirable to align the magnetization of the formed magnetic film in a certain direction.

However, as mentioned above, the magnetic film of the magneto-optical disk has a large coercive force Hc near room temperature.
In order to align the direction of magnetization, it is necessary to apply a magnetic field larger than the coercive force, and unlike conventional magnetic tapes with small coercive force, the 74M3 stone makes it possible to align the direction of magnetization of the entire magnetic film at once. Can not. For this reason, when aligning the magnetization direction of the magnetic film of a magneto-optical disk, conventionally, after completing the magneto-optical disk, the entire surface of the magneto-optical disk is tracked using an erasing beam, in the same way as when erasing information. I was going.

[Problem to be solved by the invention]

However, due to the above laser beam, the holding force HC is 15
In order to erase a disk that has more than kOe, a large number of trunks must be erased one by one, so it takes a long time to process one magneto-optical disk, which is very inefficient. Furthermore, it is not possible to process the areas between the tracks, and there are areas between the trunks with different magnetization directions, which causes noise as described above.

The present invention has been made in order to eliminate the drawbacks of the prior art, and aims to provide a method for magnetizing a magneto-optical recording medium that can align the direction of magnetization of a magnetic film in a short time. It is an object of the present invention to provide a magnetizing device that can easily magnetize a magnetic film.

[Means to solve the problem]

Even if a magnetic material has a large coercive force at room temperature, the coercive force decreases as the temperature rises.

For example, in the case of a magnetic film made of the rare earth-transition metal described above, the coercive force Hc exhibits temperature dependence as shown in FIG.

As can be seen from the figure, the coercive force of the rare earth-transition metal magnetic film having a transition metal-rich composition gradually decreases as the temperature rises from room temperature. On the other hand, in rare earth-transition metal magnetic films with a composition rich in rare earth metals, a compensation temperature exists between room temperature and the Curie point, and as the temperature rises from room temperature, the coercive force increases and the temperature exceeds the compensation temperature. When the coercive force decreases and the temperature reaches 100° C. or more, the coercive force becomes much less than 10 kOe.

The method of magnetizing a magneto-optical recording medium of the present invention was developed by focusing on the fact that the coercive force decreases as the temperature rises as described above. The method is characterized in that the roll on the magnetic film side of the rolls is heated to a high temperature to heat the magnetic film, and a magnetic field is applied to the heated magnetic film.

Application of a magnetic field to the magnetic film can be performed by arranging magnets with mutually different polarities on the surfaces of a pair of rolls.

A first aspect of the magneto-optical recording medium magnetizing device of the present invention includes means for transporting a magneto-optical recording medium having a magnetic film on one side, and a magnet having the same polarity over the entire circumferential surface and arranged on the magnetic film side. A first roll provided with a heater inside, and a second roll disposed opposite to the first roll and provided with magnets of opposite polarity to the first roll over the entire circumferential surface. It is characterized by being

The second aspect of the magnetizing device of the present invention is a conveying means for conveying a magneto-optical recording medium having a magnetic film on one side, a hot melt resin melting tank for protecting the magnetic film, and a lower end of the melting tank. a resin roll in which part is immersed, a transfer part of the hot melt resin from the resin roll on the peripheral surface; a heat insulating part inside the transfer part; and a magnet part having the same polarity as a whole inside the heat insulating part. It is characterized by being composed of a roll and a second roll which is disposed opposite to the first roll and has magnets of opposite polarity to the first roll provided on its entire circumferential surface.

Furthermore, the third feature of the magnetizing device of the present invention is a conveying means for conveying a magneto-optical recording medium having a magnetic film on one side, a hot melt resin melting tank for protecting the magnetic film, and a lower end of the melting tank. a first roll having a transfer part of the hot melt resin from the resin roll on the circumferential surface; a second roll disposed opposite to the first roll; It is characterized by having a gap through which the optical recording medium passes, and comprising a group of magnets disposed close to and facing the first and second rolls.

[Effect]

In the present invention configured as described above, the roll on the magnetic film side of a pair of rolls that transports a substrate having a magnetic film on one side is heated to a high temperature. , the magnetic film is heated by a high-temperature roll, and its coercive force decreases.Therefore, when a magnetic field is applied to the magnetic film whose coercive force has decreased, the magnetization in the magnetic film, which is oriented in a random direction, changes due to the applied magnetic field. The magnetization direction of the entire magnetic film can be easily aligned in a fixed direction in a short time.Moreover, unlike conventional tracking, there are no regions between tracks where the direction of the magnetic domain differs. In addition, the roll on the opposite side to the magnetic film side is at a low temperature, so even if the substrate is made of heat-sensitive material such as plastic, heat will not be transmitted to the substrate. adverse effects can be avoided.

By applying a magnetic field to the magnetic film using magnets installed on the surface of a pair of rolls, the direction of magnetization can be aligned while heating the magnetic film, making processing more efficient and simplifying the processing equipment. I can figure it out.

The magnetic film can be easily heated by providing a heater inside the first roll disposed on the magnetic film side, as in the first magnetizing device of the present invention. In addition, as in the first magnetizing device of the present invention, when hot melt resin for protecting the magnetic film is supplied to the first roll placed on the magnetic film side, the process of forming the protective resin and the magnetization These steps can be performed at the same time, and the steps can be simplified. Moreover, since the surface of the magnet is insulated, it is possible to prevent the performance of the magnet from deteriorating due to the heat of the hot melt resin.

Furthermore, according to the third aspect of the magnetizing device of the present invention, the magnet for applying a magnetic field to the magnetic film is provided separately from the roll.
The structure of the roll becomes simple and the cost of the device can be reduced.

(Embodiments) Preferred embodiments of the magneto-optical recording medium magnetizing method and magnetizing device of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram of a magneto-optical recording medium magnetizing apparatus according to an embodiment of the present invention.

In FIG. 1, a magneto-optical disk 10, which is a magneto-optical recording medium, has a magnetic film 14 made of a rare earth-transition metal or the like on one side (upper side in the figure) of a substrate 12 made of plastic material such as polycarbonate. . This magnetic film 14 is made of, for example, TbFeC.

It is a perpendicularly magnetized film having a coercive force of about 15 koe, which is formed on the substrate 12 by sputtering or the like via a dielectric layer such as SiN, and has a SiN layer and a protective resin film laminated on the upper surface. (None shown). The magneto-optical disk 10 is conveyed to the left in the figure as indicated by an arrow 20 by a conveyor 16, 18 serving as a conveying means. Further, a pair of first and second rolls 24.26 are disposed between the conveyor 16 and the conveyor 18, and a magneto-optical beam is formed between the first and second rolls 24.26. A gap is provided to allow the disk 10 to pass through.

The first roll 24 on the magnetic film 14 side of the substrate 12, that is, on the upper side, has a built-in heater (not shown), for example.
It is maintained at a predetermined high temperature of 0° C. or higher, and contacts the magnetic film 14 side of the substrate 12 to heat the magnetic film 14. Also,
The entire circumferential surface of the rolls 24, 26 has opposite polarity (
For example, the magnet 28 is placed so that the surface of the upper first roll 24 is the north pole and the surface of the lower second roll 26 is the south pole.
．． 30 is arranged so that a magnetic field can be applied to the heated magnetic film 14. The magnet 28 provided on the roll 24 of the 14 magnetic films is, for example, a samarium cobalt magnet, which applies a magnetic field sufficient to magnetize the magnetic film 14 when the roll 24 is held at a predetermined high temperature. membrane 14
Use the one that can be applied to.

The operation of the embodiment configured as described above is as follows.

The magneto-optical disk 10 is placed on the conveyor 16 with the side on which the magnetic film 14 is provided facing up. Conveyor 16
The magneto-optical disk 10 is conveyed from the right direction to the left direction in the figure, and is fed between the first roll 24 and the second roll 26.

The first roll 24 of the 14 magnetic films is maintained at a predetermined temperature of 100° C. or higher, for example, by a heater (not shown), and the upper surface of the magneto-optical disk 10 passing between it and the second roll 26 and touch the magnetic film 14 to 100
Heat to a temperature above °C. Also, each roll 24.26
Since the surface of the roll 24 is a north pole and the surface of the roll 26 is a south pole by magnets 28 and 30 arranged on the circumferential surface, a magnetic field is applied to the magneto-optical disk 10 passing between them, and the magnetic flux is is transmitted through the magneto-optical disk 10 from the roll 24 side to the roll 26 side.

The magnetic film 14 of the magneto-optical disk 10 is coated on rolls 24 and 26.
When passing through the gap, it is heated by the roll 24, the coercive force is reduced to 10 kOe or less, and the direction of magnetization is aligned with the direction of the magnetic field by the magnetic field generated by the magnet 28.30 provided on the roll 24.26.

Therefore, it is not necessary to track the magneto-optical disk 10 and erase the entire surface as in the conventional case, and the direction of magnetization of the magnetic film 14 can be aligned in a fixed direction in a very short time. Moreover, random magnetization between tracks can be eliminated, and noise generation can be reduced. In addition, in the embodiment, the second roll 26 on the side opposite to the magnetic film 14 is kept at a low temperature, so even if the substrate 12 is made of resin such as polycarbonate, the second roll 26 on the opposite side to the magnetic film 14 side There is almost no thermal influence on the substrate 12, and deformation of the substrate 12 can be prevented.

The second view is an explanatory diagram of another embodiment.

In FIG. 2, a magneto-optical disk 10 has a magnetic film 14 provided on a substrate 12 via a SiN layer, as in the previous embodiment, and a SiN layer is laminated on this magnetic film 14. However, in this embodiment, the protective resin film is not provided on the upper surface of the magneto-optical disk 10 that is fed between the first and second rolls 24 and 26 by the conveyor 16.

The first roll 24 of the 14 magnetic films has an outer peripheral portion 32 formed of silicone rubber or the like, and serves as a transfer portion to which hot melt resin is transferred as described later.
A magnet 28 is provided inside the transfer section with a heat insulating material 34 interposed therebetween. This magnet 28 has an outer peripheral side of N, similar to the embodiment described above.
It is arranged as a pole. Furthermore, the inside of the first roll 24 is hollow, and through holes (not shown) are formed in both end faces so that the magnet 28 can be cooled by air.

On the other hand, the resin is transferred to the roll 24 from the resin roll 36, and this resin is applied to the upper surface of the magneto-optical disk 10 to form a protective resin film. That is, the lower end of the resin roll 36 is inserted into a resin tank (melting tank) 38 and immersed in a hot melt resin 40 for forming a protective resin film for the magneto-optical disk 10, as shown by an arrow 42. The hot melt resin 40 heated to about 120'C is attached to the surface by rotating counterclockwise in the figure, and is transferred onto the roll 24 and continuously supplied. Therefore, the hot melt resin 40 adheres to the outer circumferential portion 32 of the first roll 24, which is the transfer portion, and applies the adhered resin onto the substrate 12.

The magnetic film 14 of the magneto-optical disk 10 is heated by the applied hot melt resin 40 and the first roll 24 heated by the hot melt resin 40. and second roll 26
The directions of magnetization are aligned by magnets 28 and 30 provided at both ends.

In this embodiment configured in this way, the magnetic film 14 is
The magnetization directions of the two can be aligned, and steps can be omitted. In addition, in this embodiment, the magnets 28 of the 24 rolls are
is provided through the heat insulating material 34, so the roll 24
Even if the outer circumferential portion 32 of the magnet 28 becomes hot, the performance of the magnet 28 can be prevented from deteriorating.

FIG. 3 shows the main part of yet another embodiment.

In FIG. 3, the first and second rolls 24 and 26 through which the magneto-optical disk 10 passes are formed of a non-magnetic material such as silicone rubber, and the first roll 24 on the magnetic film side is magneto-optical. A hot melt resin for a protective resin film is applied to the upper surface of the disk 10. And each roll 24.
Along the conveyance path of the magneto-optical disk 10 and at the entrance and exit sides of the magneto-optical disk 10, there are rolls 24 and 26.
Magnets 44, 46, 48, 50 are arranged close to. Among these magnets, the magnets 44 and 48 located above the magneto-optical disk 10 that pass between the rolls 24 and 26 have the north pole closer to the roll 24, and the magnets 44 and 48 that are located above the magneto-optical disk 10 that pass between the rolls 24 and 26 have the N pole. The magnet 46.50 located on the roll 2
The one closer to 6 is the S pole.

Also in this embodiment configured in this way, the hot melt resin coated with the magnetic film 14 is heated by the heat of the roll 24, and the heated portion is connected to the magnet 44.26 disposed close to the roll 24.26. The direction of magnetization is aligned by the magnetic field generated by 46.48.50. In the Motoyama embodiment, since the rolls 24 and 26 are made of silicone rubber, there is no risk of damaging the magneto-optical disk 10. Note that this embodiment can also be applied to magnetizing the magnetic film of the magneto-optical disk 10 having a protective resin film.

Further, the direction of the magnetic field may be opposite to that in each of the above embodiments.

〔Effect of the invention〕

As explained above, according to the present invention, the roll on the magnetic film side of a pair of rolls that transports a substrate having a magnetic film on one side is heated to a high temperature, and when the substrate passes between the pair of rolls, When a magnetic film is heated with a high-temperature roll to reduce its coercive force, and a magnetic field is applied to the magnetic film after the coercive force is reduced,
The magnetizing force 5 in the magnetic film facing in a random direction becomes parallel to the direction of the applied magnetic field and the container, and the direction of magnetization of the entire magnetic film can be aligned in a fixed direction in a short time.

Moreover, unlike the case of conventional tracking, there are no regions in which the magnetic domain directions differ between trunks, and noise can be eliminated. Further, since the roll on the side opposite to the magnetic film side is at a low temperature, even if the substrate is made of plastic or other heat-sensitive material, adverse thermal effects on the substrate can be avoided.

By applying a magnetic field to the magnetic film using magnets installed on the surface of a pair of rolls, the direction of magnetization can be aligned while heating the magnetic film, making processing more efficient and simplifying the processing equipment. I can figure it out.

The magnetic film can be easily heated by providing a heater inside the first roll disposed on the magnetic film side, as in the first magnetizing device of the present invention. Also,
As in the first magnetizing device of the present invention, when hot melt resin for protecting the magnetic film is supplied to the first roll placed on the magnetic film side, the process of forming the protective resin and the magnetization process are performed. This can be done at the same time, simplifying the process. Moreover, since the surface of the magnet is insulated, it is possible to prevent the performance of the magnet from deteriorating due to the heat of the hot melt resin.

Furthermore, according to the third aspect of the magnetizing device of the present invention, the magnet for applying a magnetic field to the magnetic film is provided separately from the roll.
The structure of the roll becomes simple and the cost of the device can be reduced.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an S magnetic device of a magneto-optical recording medium according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of another embodiment, and FIG. 3 is an explanatory diagram of still another embodiment. FIG. 4 is a diagram showing the dependence of coercive force on rare earth metal concentration in a TbFeCo magnetic film, and FIG. 5 is a diagram showing TbFeCo magnetic film. FIG. 3 is a diagram showing the temperature dependence of coercive force in a magnetic film. 10---- magneto-optical recording medium (magneto-optical disk), 1
2-----One substrate, 14----One magnetic film, 24 first
roll of, 26-----Second roll of, 28.30
--- Magnet, 3 B-1 --- Resin tank, 40, ---
hot melt resin.

Claims (5)

[Claims] (1) Of a pair of rolls through which a substrate having a magnetic film on one side passes, the roll on the magnetic film side is heated to a high temperature to heat the magnetic film, and a magnetic field is applied to the heated magnetic film. A method of magnetizing a magneto-optical recording medium. (2) Magnetizing the magneto-optical recording medium according to claim 1, wherein the application of the magnetic field to the magnetic film is performed by arranging magnets with mutually different polarities on the surfaces of the pair of rolls. Method. (3) a means for conveying a magneto-optical recording medium having a magnetic film on one side; a first roll disposed on the magnetic film side and having a magnet of the same polarity on its entire circumferential surface and a heater therein; A magnetizing device for a magneto-optical recording medium, characterized in that the second roll is disposed opposite to the first roll and has a magnet with a polarity opposite to that of the first roll provided on the entire circumferential surface of the second roll. . (4) A conveying means for conveying a magneto-optical recording medium having a magnetic film on one side, a hot-melt resin melting tank for protecting the magnetic film, a resin roll whose lower end is immersed in the melting tank, and a peripheral A first roll having a transfer portion of the hot melt resin from the resin roll on its surface, a heat insulation portion inside the transfer portion, and a magnet portion having the same polarity as a whole inside the heat insulation portion, and facing the first roll. 1. A magnetizing device for a magneto-optical recording medium, characterized in that the second roll is arranged as follows, and a second roll is provided with magnets having a polarity opposite to that of the first roll over its entire peripheral surface. (5) A conveying means for conveying a magneto-optical recording medium having a magnetic film on one side, a hot-melt resin melting tank for protecting the magnetic film, a resin roll whose lower end is immersed in the melting tank, and a peripheral A first roll having a transfer portion of hot melt resin from the resin roll on its surface, a second roll disposed opposite to the first roll, and a gap through which the optical recording medium passes. A magneto-optical recording medium magnetizing device comprising: a group of magnets arranged close to and facing the first and second rolls.