JPS59152552A - Photo magnetic disk - Google Patents

Abstract

PURPOSE:To isolate completely a magnetic recording medium from the air in order to prevent the deterioration of characteristic of the medium due to oxidation, etc., by coating with a metallic film over the exposed whole surface of a synthetic resin film formed on a glass substrate having a tracking groove and the recording medium formed on the synthetic resin film. CONSTITUTION:A plastic film 10 having a tracking groove is formed on the surface of a glass substrate 9 with a photopolymer, and a recording medium 11 of GdTbFe is formed on the film 10. Then both the film 10 and the medium 11 are cut from the inner and outer circumferences of a disk. The vapor deposited metallic aluminum 15 is put on an evaporation boat 14 under vacuum, and at the same time a semimanufactured photomagnetic disk 16 is attached to a rotary shaft 17 in parallel to the aluminum 15. Then the boat 14 is heated while revolving said disk 16, and the aluminum 15 is vapor deposited to the exposed area of the surface of the medium 11 and the substrate 9. The shaft 17 is tilted by 45 deg., and the aluminum 15 is vapor deposited on the outer circumferential surfaces of the film 10 and the medium 11 to form a metallic layer 12. Then a scratch-resistance plastic protection coat 13 is applied to the surface of the layer 12.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a magneto-optical disk.

Conventional configurations and their problems Magneto-optical disks have been widely studied as memory media that can be recorded, reproduced, and erased, and are capable of high-density, large-capacity, and high-speed access. Application products are being considered in a wide range of fields, including audio discs, video discs, discs for editing machines, document file discs, and still image file discs.

The recording media used in magneto-optical disks are generally iron-based, such as iron and cobalt, and cadrinium.

Rare earth elements such as terbium and dysprosium are often used and tend to be easily oxidized. Therefore, it is necessary to maintain complete sealing to prevent metal oxidation.

If we consider the conventionally used optical discs,
Currently, most read-only discs use a method that reads changes in 1 reflectance.

The metal thin film used is aluminum.

There are many relatively stable materials such as chill, hydrogen oxide, and tellurium alloys. Therefore, many structures are used, such as a two-layer air gear assembly method as shown in FIG. 1, a direct two-layer assembly method as shown in FIG. 2, and a single-plate coating method as shown in FIG. 8. Note that (1) is a plastic substrate, (2) is a recording medium, (3) is a spacer, (4) is an air layer, and (5)
(6) is a protective cover, (6) is a metal film, (7) is a scratch-resistant plastic protective coat, and (8) is a plastic film with tracking grooves formed on its surface. Plastic is used as the constituent material, and the air permeability is high.

If we apply the two-layer bonding method shown in Figures 1 and 2 to magneto-optical disks, even if we use a glass substrate instead of a plastic substrate (glass substrate), we would still have to use plastic for the tracking guide. Because it doesn't happen,
The bonding temperature must be kept below 80'C. Therefore, it is impossible to bond inorganic materials that require high temperatures, and organic materials are used to bond the outer and inner periphery, which has air permeability at the edges, and the recording medium (2) is oxidized from the edges. There are drawbacks.

Next, the veneer coating method shown in FIG.
If there is a notch at the end as shown in Figure 01), if a glass substrate is used instead of the plastic substrate (1) and a protective metal film (6) is formed on the surface of the recording medium (2), the plastic film ( 8) has a thickness of 50 to 100/7 m, so the edges and parts are not covered with the metal film (6) but only with the scratch-resistant plastic protective coat (7), so it has breathability. , oxidation of the recording medium (2) occurs.

Moreover, if there is no notch at the end, as shown in FIG. 8(C), there is no problem because the recording medium (2) would be directly exposed to the atmosphere.

As described above, magneto-optical disks are required to be more moisture resistant than other optical disks, and a highly airtight structure is desired, but so far there has been no one that has been fully satisfactory.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art, and aims to provide a magneto-optical disk in which the recording medium is completely shielded from the atmosphere and does not suffer from deterioration of characteristics such as oxidation.

Structure of the Invention In order to achieve the above object, the magneto-optical disk of the present invention has the following features:
a glass substrate, a synthetic resin film having a tracking groove formed on the glass substrate, a magnetic recording medium formed on the synthetic resin film, and covering the entire exposed surfaces of the synthetic resin film and the magnetic recording medium. This configuration includes a metal film.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Fig. 4 is a cross-sectional view of the main part of the magneto-optical disk before applying the protective coat, and Fig. 5 is a cross-sectional view of the main part of the magneto-optical disk after the protective coat is applied. I
0 is a plastic film having a tracking groove, 0υ is a recording medium, 0 is a metal film, and 03 is a scratch-resistant plastic protective coat. This magneto-optical disk is placed on the glass substrate (9) l for a sufficient distance from the edge of the glass substrate (9).
After forming a plastic film OI at a distance and forming a recording medium 01 on its surface, a metal film @ is laminated on the recording medium θ, and the outer peripheral surface and inner surface of the recording medium and the plastic film (1 A metal film 0 is formed on the peripheral surface and the exposed portion of the surface of the glass substrate (9), and this is further covered with a scratch-resistant plastic protective coat θ.

Next, specific examples will be described. First, the outer diameter is 120ffff
.

A plastic film 00 with a layer thickness of 70 μm and having a trunking groove with a depth of 700 mm (rack pitch 25 μm; A recording medium 0 made of GdTbFe is formed by sputtering on the surface of the polymer.
0, the plastic film OQ and the recording medium Ql)
Five rounds were cut from the inner and outer peripheries of the disk. after that,
As shown in Fig. 6, a vapor-deposited metal aluminum 00 is placed on an evaporation boat (Ml) in a vacuum, and the semi-finished magneto-optical disk θQ is attached to the rotating shaft α so that it is parallel to it and rotated. While heating the deposition boat (14),
Aluminum OQ was deposited to a thickness of 5000 on the exposed portions of the recording medium Ql) surface and the glass substrate (9) surface.

Next, as shown in FIG. 7, the rotation axis 0? ) was tilted at an angle of 45 degrees, and 0% aluminum was vapor-deposited on the outer peripheral surfaces of the plastic film Q1 and the recording medium Q to form a metal layer. Thereafter, a scratch-resistant plastic protective coat θ was applied to the surface. Note that although the outer circumferential portion of the disk has been described, the same procedure was performed for the inner circumferential portion.

Figure 8 is an explanatory diagram of the results of a magneto-optical disk storage test, under conditions of a temperature of 50'C and a humidity of 70% RH. , and the magneto-optical disk according to an embodiment of the present invention shown in FIG. (the initial value is 1), and the horizontal axis is the standing time. Note that the solid line (a) shows the case of a magneto-optical disk according to an embodiment of the present invention, and the solid line (b) shows the case of a conventional magneto-optical disk.

As described in detail, according to the present invention, it is possible to effectively prevent the deterioration of the recording medium starting from the disk 914 portion.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional near-gap two-layer magneto-optical disk, Figure 2 is a cross-sectional view of a conventional two-layer direct-layer magneto-optical disk, and Figure 3 (5) is a conventional Cross-sectional view of a magneto-optical disk using a single-plate coating method, same figure ()
3) is an enlarged sectional view of the main part of the same magneto-optical disk with a notch at the end, FIG. 5 is a sectional view of the main part of the magneto-optical disk before the protective coating is applied in an embodiment of the present invention, FIG. 5 is a sectional view of the main part of the same magneto-optical disk after the protective coating is applied, and FIGS. The figure is an explanatory diagram of the manufacturing process of the magneto-optical disk, and FIG. 8 is an explanatory diagram of the results of a storage test of the magneto-optical disk. (9)-Glass substrate, 00... plastic film, θυ
・Recording medium, αa... Metal film agent Yoshihiro Morimoto Figure 1 Figure 5 Figure 7 Figure 7 101) /l) θθ release￥B!
1 hour

Claims (1)

[Claims] l. A glass substrate, a synthetic resin film having a tracking groove formed on the glass substrate, a magnetic recording medium formed on the synthetic resin film, and the synthetic resin film and magnetic recording medium described above. and a metal film covering the exposed surface of the silkworm body.