JPS619850A - Guide track forming method of photomagnetic recording medium - Google Patents

Abstract

PURPOSE:To form efficiently guide tracks to improve the productivity by giving an external energy to transfer guide tracks to a photomagnetic recording medium in the state where a master plate where prescribed guide track patterns are formed is allowed to face the photomagnetic recording medium. CONSTITUTION:A master plate 1 is provided with a substrate 2 and an optical recording layer 3 consisting of photomagnetic recording materials, and the magnetization direction is inverted to form guide tracks 4 in the optical recording layer 3. Areas where the magnetization direction is not inverted are used as information tracks 5. A photomagnetic recording medium 6 to which patterns of guide tracks 4 of the master plate 1 should be transferred and the master plate 1 are allowed to face each other so that respective optical recording layers 3 and 8 are brought into contact with each other (figure A). An external energy is given in this state, and the floating magnetic field from the master plate 1 is used to transfer prescribed guide tracks 4 to the optical recording layer 8 of the photomagnetic recording medium 6, and guide tracks 9 and information tracks 10 shown in a figure B are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magneto-optical recording medium, and particularly to a method for forming guide tracks thereof.

(Prior Art) In the field of information technology, with the rapid increase in the amount and diversification of information, there has been a marked increase in the demand for a significant increase in the recording density of recording media.

Therefore, as an alternative to the conventional recording method, an optical recording method using an optical recording medium has been proposed. This optical recording method uses, for example, optical recording media using irreversible recording materials such as metal thin films or polymer materials, or optical recording media using reversible recording materials such as thermoplastics, chalcogenide alloys, TeOx, or magneto-optical materials. Media are being put into practical use or being developed.

This reversible recording material is a material that can be rewritten, and magneto-optical materials in particular can be rewritten an unlimited number of times, and the wavelength dependence of recording and reading sensitivity is small, so it depends on the light source used. Because semiconductor lasers can be used without restrictions, they are the most popular material, and research and development into rewritable magneto-optical recording media using them is active.

Not limited to magneto-optical recording media, but in general, optical recording systems using optical recording media require random access, so recording (writing) and reading must be performed along a certain line. However, if a tracking guide track (also called a guide groove) is not formed, random access becomes extremely difficult. Therefore, a guide track is usually provided, for example, adjacent to the information track on the disc.

By the way, there are currently three methods of forming guide tracks in magneto-optical recording media.

The first method is to use a plastic substrate and form the guide tracks together with it during molding.

The second method is to use a glass substrate that does not deform, does not absorb moisture, and has excellent optical properties, and etches the glass substrate to form guide tracks.

A third method is to form guide tracks by forming a magneto-optical recording material on the substrate and then subjecting it to some kind of treatment, without forming guide tracks on the substrate itself.

(Problems to be solved by the invention) However, since the first method uses a plastic material such as polymetal methacrylate or polycarbonate, the material itself is easily deformed and warped. Since it is easily deformed by heat, the formation conditions when depositing the magneto-optical recording material on the substrate become extremely strict.

Optical recording materials are easily corroded because they easily absorb moisture;
It had drawbacks such as birefringence.

In the second method, the etching process involves first applying a photoresist to a glass substrate, then exposing the resulting photoresist film to light using a mask or directly using a laser, etc. The process consists of at least four steps: development, and then processing and etching of the glass substrate.Etching of glass in particular is selective in the etching direction because glass does not have anisotropy. It is extremely difficult to Therefore, the process for forming a pattern of perfectly aligned unevenness becomes complicated, and the formation thereof is also difficult, resulting in low productivity.

Furthermore, in the third method mentioned above, for example, by directly irradiating each magneto-optical recording medium with a powerful laser in accordance with the pattern of the guide track and causing burnout, the shape becomes uneven. However, the difference in reflectance causes a systematic change and forms a guide track, or
For example, by irradiating each medium with a laser in accordance with the pattern of the guide tracks and at the same time applying an external magnetic field as necessary, this allows the guide tracks to be recorded and magneto-optically recorded in the same manner as in normal magneto-optical recording. However, either method has the disadvantage that productivity does not increase because the laser is used to draw directly on each medium.

As described above, the conventional method of forming guide tracks for optical recording media has various problems, and there are many points to be improved.

An object of the present invention is to provide a method for forming guide tracks for a magneto-optical recording medium, which can efficiently form guide tracks for a magneto-optical recording medium and increase productivity.

(Means for Solving the Problem) In order to achieve this object, according to the method for forming a guide track for a magneto-optical recording medium of the present invention, a master plate on which a predetermined guide track pattern is formed is used for magneto-optical recording. The guide track is transferred to the magneto-optical recording medium by applying external energy while facing the medium.

(Operation) According to this method, a master plate on which a predetermined guide track has been formed in advance is opposed to a magneto-optical recording medium with a small gap or in contact with the master plate, and the energy of a magnetic field or thermal energy is A predetermined guide track can be formed on a magneto-optical recording medium using an extremely simple transfer process that involves applying external energy, so a large number of magneto-optical recording media can be created from a master plate, regardless of the type of material of the substrate of the magneto-optical recording medium. Guide tracks can be formed by transfer.

(Example) Hereinafter, an example of the method for forming a guide track for an optical recording medium according to the present invention will be described with reference to the drawings.

First, the master plate used in this invention will be briefly explained with reference to FIG.

FIG. 2 is a perspective view schematically showing a part of the structure of the master plate 1, in which the substrate 2, the optical recording layer 3, the guide track 4, and the information track 5 are emphasized.

This master plate 1 comprises a substrate 2 and an optical recording layer 3 made of a magneto-optical recording material. For example, the substrate 2 is a glass substrate, and a perpendicularly magnetized film of TbFeC:o as the recording layer 3 is deposited thereon to a thickness of about 300 nm by sputtering. Next, this member is placed in a magnetic field of, for example, 7 KOe to orient the magnetization direction of the optical recording layer 3 in a fixed direction, and then an Ar laser is applied to the optical recording layer 3 while a magnetic field of 5000 e is applied. By scanning, the direction of magnetization is reversed in accordance with a predetermined guide track pattern to be formed, thereby forming guide tracks 4 as shown with diagonal lines in the figure. Note that the information track 5 is an area in which the magnetization direction is not reversed.

Note that the above-mentioned Tb is used as the optical recording layer 3 of this master plate I.
Other than FeCo, for example, a perpendicular magnetization film such as TbFe or TbCo, or an in-plane magnetization film such as CrO2 or SmCo can also be used. Furthermore, the master plate 1 itself only needs to have a predetermined guide track pattern formed by reversed magnetization regions, and does not need to have a magneto-optic effect.

Furthermore, the record of guide track 4 of this master version 1 is as follows:
In addition to the method described above, the recording may be performed using, for example, a magnetic recording head, a magnetic needle, a hot needle, or the like, and if necessary, the recording may be performed by supplementally applying energy from the outside.

Next, a method of the present invention for transferring guide tracks to a magneto-optical recording medium using such a master plate 1 will be explained with reference to FIGS. 1(A) and 1(B). These figures are partial route maps shown in cross section in a direction perpendicular to the direction in which the guide track and the information track extend.

First, the magneto-optical recording medium 6 to which the pattern of the guide track 4 of the master plate 1 is to be transferred and the master plate 1 are opposed to each other with their optical recording layers in contact with each other (FIG. 1(A)).

This magneto-optical recording medium 6 also includes a substrate 7 and an optical recording layer 8 formed thereon. In this case, this substrate 7 is a glass substrate, and a magnetic film made of GdCo as an optical recording layer 8 is formed thereon to a thickness of about 1f) Onm.
The optical recording layer 8 is oriented in a certain direction in a magnetic field of e. This magnetization direction is, for example, a direction from the substrate 7 side of the optical recording layer 8 to the surface of this layer 8 (indicated by an arrow) as shown in FIG. 1(A). It is also assumed that the guide track 4 of the master plate 1 is in the direction from the substrate 2 side of the optical recording layer 3 toward the surface of the layer 3 (indicated by an arrow).

External energy is applied while the optical recording layer 3 of the master plate 1 and the optical recording layer 8 of the magneto-optical recording medium 6 are in contact with each other.

On the real/stream side, an external magnetic field of, for example, 5000 e is applied in the opposite direction to the magnetization direction of the magneto-optical recording medium 6, and a stray magnetic field from the master plate l is used to move the predetermined guide track 4 magneto-optically. It is transferred to the optical recording layer 8 of the recording medium 6, and the image shown in FIG.
B) A guide track 9 and an information track 10 as shown in FIG.
and form.

Through this transfer, it is possible to form a guide track similar to the guide track obtained by scanning a conventional magneto-optical recording medium one by one with a laser, and it is also possible to form a guide track similar to the guide track obtained by scanning a magneto-optical recording medium one by one with a conventional laser. , just like the mass production of record version replicas, it can be efficiently produced in large quantities.

The guide track obtained by transfer in this way is processed using the same method as for reading out magneto-optical recording, that is, the Kerr effect,
Alternatively, tracking can be performed using the Faraday effect.

In the above-mentioned embodiment, Gd1ll:o was used as the magnetic film of the optical recording layer 8 of the magneto-optical recording medium 6, but it is not limited to this, -t', and GdFe, TbFe, Dy
It is also possible to use Fe or the like.

Furthermore, external energy was applied to the optical recording layers 3 and 8 while they were in contact with each other, but the transfer was performed with the optical recording layers 3 and 8 facing each other with a small gap that allowed the transfer. Also good.

Furthermore, this external energy is not limited to magnetic field energy, but may also be thermal energy.

In that case, for example, it is possible to heat the magneto-optical recording medium 6 with a hot ray lamp, by applying an electric current, or by applying a magnetic field.
An appropriate method determined from the Curie point or compensation point of the magnetic material of the magnetic material and the magnetic material of the magneto-optical recording medium and the coercive force may be selected and used.

(Effects of the Invention) According to the method of the present invention, a master plate on which a predetermined guide track pattern is formed in advance is used, and the guide track is simply transferred onto the optical recording layer of a magneto-optical recording medium. Since guide tracks can be formed on magneto-optical recording media through the process, such guide tracks can be efficiently formed on a large amount of magneto-optical recording media, significantly improving productivity compared to conventional methods. There are advantages to being able to do it.

[Brief explanation of the drawing]

FIGS. 1(A) and (B) are process diagrams for explaining the method of forming a guide track for a magneto-optical recording medium of the present invention, and FIG. 2 is a process diagram for explaining the structure of a master plate used in the method of the present invention. It is a perspective view of the route. ■... Master version, 2... Board 3... (
Optical recording layer 4 (of the master version)... Guide track 5 (of the master version)... Information track 6 (of the master version)... Magneto-optical recording medium 7... (of the magneto-optical recording medium) Substrate 8... Optical recording layer 9 (of the magneto-optical recording medium)... Guide track 10 (of the magneto-optical recording medium)... Information track (of the magneto-optical recording medium).

Claims (1)

[Claims] 1. In forming a guide track of a magneto-optical recording medium,
A light beam characterized in that the guide tracks are transferred to the magneto-optical recording medium by applying external energy while a master plate on which a predetermined guide track pattern is formed is opposed to the magneto-optical recording medium. A method for forming a guide track on a magnetic recording medium. 2. A method for forming a guide track for a magneto-optical recording medium according to claim 1, wherein the external energy is magnetic field energy. 3. A method for forming a guide track for a magneto-optical recording medium according to claim 1, wherein the external energy is thermal energy.