JPH08235658A - Magetooptical disc - Google Patents

Abstract

PURPOSE: To prevent deterioration of magnetooptical recording film and increase a recording capacity by forming a magetooptical film on the entire part of a single surface of a substrate and then forming a protection film covering the entire part of the magnetooptical recording film. CONSTITUTION: An annular groove 14 having almost the V-shaped cross-section which reaches a substrate 11 through a magnetooptical recording film 12 is provided in the vicinity of external edge 11a of the substrate 11 and the inside of the annular groove 14 is filled with a resin forming a protection film 13. In this case, the magnetooptical recording film 12 in the circumferential side from the annular groove 14 of the magnetooptical disc 10 is used as the recording region. Since the magnetooptical recording film 12 of this region is overed, at the external edge portion 12a, with the protection film 13 filling the annular groove 14, deterioration of such area can be prevented. Moreover, since distance between the external edge 11a of the substrate 11 and external edge 13a of the magnetooptical recording film 12 is extremely short, recording capacity of the magnetooptical disc 10 can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical disk as an optical memory element capable of rewriting information.

[0002]

2. Description of the Related Art In recent years, a magneto-optical disk as an optical memory element capable of rewriting information has been actively developed. As shown in FIG. 5, this magneto-optical disk is basically formed by forming a magneto-optical recording film 2 on a transparent substrate 1.
A desired recording area on the magneto-optical recording film 2 is irradiated with a laser beam or the like to raise the temperature and magnetically record / erase.

By the way, since the magneto-optical recording film 2 is generally made of a rare earth-transition metal amorphous alloy, it is easily deteriorated by coming into contact with air, moisture, etc.
As shown in FIG. 5, a protective film 3 made of resin is usually formed on the magneto-optical recording film 2 to protect the magneto-optical recording film 2. In that case, when the outer peripheral edge portion 2a of the magneto-optical recording film 2 is exposed from the protective film 3, the magneto-optical recording film 2 is exposed to the outer peripheral edge portion 2a.
There is a risk of deterioration.

Therefore, the outer peripheral line portion 2 of the magneto-optical recording film 2 is conventionally used.
a is positioned on the inner peripheral side of the outer peripheral edge portion la of the substrate 1, and the protective film 3 also covers the outer peripheral edge portion 2a of the magneto-optical recording film 2.

As described above, the outer peripheral edge portion 2 of the magneto-optical recording film 2 is
When a is covered with the protective film 3, the magneto-optical recording film 2 is formed by supporting the outer peripheral portion of the substrate 1 with an annular holder 4 as shown in FIG. Etc., the magneto-optical recording green film 2 is formed in a region of the substrate 1 other than the region supported by the holder 4.

[0006]

However, in the magneto-optical disk having the magneto-optical recording film 2 formed as described above, the supporting margin l of the substrate 1 by the holder 4 needs to be about 4 to 5 mm. The outer peripheral edge portion 2a of the magnetic recording film 2 is the substrate 1
The outer peripheral edge portion 1a is positioned on the inner peripheral side by about 4 to 5 mm. Therefore, with these magneto-optical disks,
Since the magneto-optical recording film 2 is not formed in a fairly wide area (about 4 to 5 mm in the radial direction) near the outer peripheral edge portion 1a of the substrate 1, there is a problem that it is disadvantageous in increasing the storage capacity.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above problems by forming a magneto-optical recording film extending as close as possible to the outer peripheral edge of a substrate, and further, forming the outer peripheral edge of the magneto-optical recording film. It is an object of the present invention to provide a magneto-optical disc in which the magneto-optical recording film is covered with a protective film to prevent deterioration of the magneto-optical recording film and increase the recording capacity.

Therefore, in the magneto-optical disk of the present invention, at least the translucent substrate, the magneto-optical recording film, and the resin-made protective film for protecting the magneto-optical recording film are included in the magneto-optical disk. A magneto-optical recording film is formed on the entire surface of one side,
It is characterized in that a protective film is formed to cover the entire surface of the magneto-optical recording film.

According to the structure of the present invention, since the magneto-optical recording film is formed on the entire one surface of the substrate, the recording capacity is increased, and the entire surface of the magneto-optical recording film is covered with the protective film. Therefore, deterioration of the magneto-optical recording film is also prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention.
The explanation is based on the following.

As shown in FIG. 1C, a magneto-optical disk 10 according to this embodiment comprises a transparent substrate 11 and a magneto-optical recording film 12 having an easy axis of magnetization in a direction perpendicular to the film surface. , And a protective film 13 made of resin that covers the magneto-optical recording film 12. An annular groove 14 having a substantially V-shaped cross section that passes through the magneto-optical recording film 12 and reaches the substrate 11 is provided in the vicinity of the outer peripheral edge portion 11a of the substrate 11, and the resin forming the protective film 13 is provided in the annular groove 14. Is filled.

The manufacturing procedure of the magneto-optical disk 10 will be described below.

First, as shown in FIG. 1 (a), glass,
A transparent substrate 1 made of a resin such as polycarbonate or PMMA (polymethylmethacrylate) or a metal.
A magneto-optical recording film 12 is formed on the entire surface of 1 by vapor deposition, sputtering or the like.

Here, when the material of the substrate 11 used is one such as polycarbonate which has a reduced reproduction signal quality C / N due to the effect of birefringence in the vicinity of the outer peripheral edge portion, the substrate 1 is previously prepared.
It is preferable that 1 is formed slightly larger than the product size and the vicinity of the outer peripheral edge is cut and removed. For example, when the substrate 11 having a diameter of 120 mm is used, the diameter of 13
If the substrate 11 is made of polycarbonate or the like, it is possible to secure the C / N in the vicinity of the outer peripheral edge by forming it to about 0 mm and cutting the vicinity of the outer peripheral edge where the C / N decreases. become. Although FIG. 1A shows the substrate 11 having a circular hole in the center thereof, this circular hole is not always necessary.

When the magneto-optical recording film 12 is formed, subsequently, as shown in FIG. 1B, the magneto-optical recording film 12 is formed in a portion near the outer peripheral edge of the substrate 11 and inside the outer peripheral edge. From the side
A narrow annular groove 14 having a substantially V-shaped cross section that passes through the magneto-optical recording film 12 and reaches the substrate 11 is formed. For example, when the diameter of the substrate 11 is 120 mm, the radial distance l ₁ between the outer peripheral edge portion lla of the substrate 11 and the inner peripheral end portion of the annular groove 14 is set to be within about 1 mm.

Next, as shown in FIG. 1C, the protective film 13 is applied to the surface of the magneto-optical recording film 12 including the inside of the annular groove 14 by spin coating, that is, a coating method of dropping the resin while rotating the substrate 11. Then, the protective film 13 is cured. As a material for the protective film 13, a suitable resin such as a thermosetting resin or an ultraviolet curable resin can be used, and the resin is cured by heating or irradiation with ultraviolet rays.

The magneto-optical disk 1 manufactured by the above procedure.
For 0, the magneto-optical recording film 12 on the inner peripheral side of the annular groove 14 is used as a recording area. Then, the outer peripheral edge portion 12a of the magneto-optical recording film 12 in this area is covered with the protective film 13 filled in the annular groove 14, and deterioration of the magneto-optical recording film 12 from the outer peripheral edge portion 12a is prevented. Moreover, the distance l ₁ between the outer peripheral edge portion 11a of the substrate 11 and the outer peripheral edge portion 12a of the magneto-optical recording film 12 is extremely short, about ₁ mm or less, which is advantageous in increasing the storage capacity of the magneto-optical disk 10.

Next, a second embodiment will be described with reference to FIG.

As shown in FIG. 2C, the magneto-optical disk 20 includes a substrate 21, and a tapered portion 2lb is formed at a corner portion of the outer peripheral edge portion 21a of the substrate 21. The magneto-optical recording film 2 is formed on the surface of the substrate 21 excluding the tapered portion 21b.
2 is formed, and the tapered portion 21b and the magneto-optical recording film 22 are formed.
The surface of is covered with a protective film 23.

The manufacturing procedure of the magneto-optical disk 20 will be described below.

First, as shown in FIG. 2A, the substrate 21
A magneto-optical recording film 22 is formed on the entire surface of the substrate by vapor deposition, sputtering or the like.

Next, the corners of the outer peripheral edge portion 2la of the substrate 21 are cut obliquely, and the substrate 2 is cut as shown in FIG. 2 (b).
A tapered portion 21b is formed at one corner. At this time, the magneto-optical recording film 22 on the corner of the substrate 21 is removed. In addition,
The interval l ₂ between the outer peripheral edge portion 22a of the magneto-optical recording film 22 and the outer peripheral edge portion 21a of the substrate 21 after forming the tapered portion 21b is set to about 1 mm or less.

Next, on the surface of the magneto-optical recording film 22 and the substrate 2.
The protective film 23 is formed by applying an appropriate resin on the tapered portion 21b of No. 1 by spin coating or the like.
Forming and curing. In this state, the magneto-optical recording film 22
The outer peripheral edge portion 22a of is covered with the protective film 23 on the tapered portion 21b.

Next, a third embodiment will be described with reference to FIG.

As shown in FIG. 3C, the magneto-optical disk 30 is provided with a substrate 31, and a tapered portion 31b is provided at a corner portion of the outer peripheral edge portion 31a of the substrate 31. A magneto-optical recording film 32 is formed on the surface of the substrate 31 including the tapered portion 31b. Further, the magneto-optical recording film 32
The surface including the outer peripheral edge portion 32 a is covered with a protective film 33.

The procedure for manufacturing the magneto-optical disk 30 will be described below.

First, as shown in FIG. 3A, the substrate 31
Tapered portions 31b are formed at the corners of the outer peripheral edge portion 31a. Here, the radial distance l ₃ between the inner peripheral edge of the tapered portion 31b and the outer peripheral edge portion 31a is set to about 1 mm or less.

Next, as shown in FIG. 3B, a magneto-optical recording film 32 is formed on the surface of the substrate 31 including the tapered portion 31b.

Subsequently, as shown in FIG. 3C, a protective film 33 is applied to the surface of the magneto-optical recording film 32 by spin coating or the like and cured. The resin forming the protective film 33 at the time of application is the magneto-optical recording film 32 on the tapered portion 31b.
Along the edge of the magneto-optical recording film 32 by its own weight, and also covers the outer peripheral edge portion 32a of the magneto-optical recording film 32.

In the magneto-optical disk 30 of this embodiment, the magneto-optical recording film 32 formed on the tapered portion 31b of the substrate 31 may or may not be used for recording. Even if the magneto-optical recording film 32 on the tapered portion 31b is not used for recording, the tapered portion 31b
Has a width of at most about 1 mm in the radial direction, so a sufficient storage capacity can be secured.

Next, a fourth embodiment will be described with reference to FIG.

As shown in FIG. 4C, the magneto-optical disk 40 comprises a substrate 41 and a magneto-optical recording film 42 formed on the entire surface of the substrate 41. The surface of the magneto-optical recording film 42,
In addition, the magneto-optical recording film 42 and the outer peripheral edge portion 42 of the substrate 41
The a and 41a are covered with a protective film 43 made of resin.

The manufacturing procedure of the magneto-optical disk 40 will be described below.

First, as shown in FIG. 4A, the substrate 41
A magneto-optical recording film 42 is formed on the entire surface of the.

Next, as shown in FIG. 4B, the substrate 41
Is positioned and inserted so as to be concentric in a bottomed holder 44 having an inner diameter slightly larger than the outer diameter of the substrate 41 and a depth equal to or greater than the thickness of the substrate 41.

Then, a protective film 43 is formed on the magneto-optical recording film 42.
When the resin constituting the above is dropped by a spin coating method or the like, the resin covers the surface of the magneto-optical recording film 42, and further, the magneto-optical recording film 42 and the outer peripheral portion 42a of the substrate 41
It also flows between 41 a and the inner peripheral surface of the holder 44. When the resin is cured in this state, the surface of the magneto-optical recording film 42, and the outer peripheral edge portion 4 of the magneto-optical recording film 42 and the substrate 41.
A protective film 43 is formed on 2a and 41a. After that, FIG.
As shown in (c), the magneto-optical disk 40 is taken out from the holder 44.

If a release layer 44a made of a material having a good releasability such as tetrafluoroethylene resin (trade name: Teflon) is formed on the bottom surface and the inner peripheral surface of the holder 44, the holder 44 is removed. The magneto-optical disk 40 can be easily taken out.

In each of the above embodiments, a single-sided recording type magneto-optical disk is described, or in the case of a double-sided recording type magneto-optical disk, two magneto-optical disks manufactured by any of the above methods are bonded. It suffices to stick them together with an agent.

[0039]

As described above, the magneto-optical disk of the present invention is a magneto-optical disk having at least a transparent substrate, a magneto-optical recording film, and a resin protective film for protecting the magneto-optical recording film. In the disc, a magneto-optical recording film is formed on the entire surface of one side of the substrate, and a protective film is formed to cover the entire surface of the magneto-optical recording film.

Therefore, the storage capacity can be further increased while the deterioration of the magneto-optical recording film is prevented.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing a procedure for manufacturing a magneto-optical disk according to an embodiment of the present invention.

FIG. 2 is a schematic vertical sectional view showing a procedure for manufacturing a magneto-optical disk according to another embodiment of the present invention.

FIG. 3 is a schematic vertical sectional view showing a manufacturing procedure of a magneto-optical disk according to still another embodiment of the present invention.

FIG. 4 is a schematic vertical cross-sectional view showing the manufacturing procedure of the magneto-optical disk according to another embodiment of the present invention.

FIG. 5 is a schematic vertical sectional view showing a conventional magneto-optical disk.

FIG. 6 is a schematic vertical sectional view showing a film forming process of a magneto-optical recording film in a conventional magneto-optical disk.

[Explanation of symbols]

 10, 20, 30, 40 Magneto-optical disk ll, 21, 31, 41 Substrate lla, 21a, 31a, 41a Outer peripheral edge part 12, 22, 32, 42 Magneto-optical recording film 13, 23, 33, 43 Protective film 14 Ring Grooves 21b, 31b Tapered portion 44 Holder

Front page continued (72) Inventor Zenteru Murakami 22-22 Nagaikecho, Abeno-ku, Osaka, Osaka Within

Claims (1)

[Claims] 1. A magneto-optical disk comprising at least a translucent substrate, a magneto-optical recording film, and a resin protective film for protecting the magneto-optical recording film, wherein the magneto-optical recording film is formed on one entire surface of the substrate. Is formed, and a protective film is formed to cover the entire surface of the magneto-optical recording film.