JPS61248251A - Case for storing photomagnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent a recording main from being erased and to maintain information stably by applying an external magnetic field in the same direction as that of a recording case to an photomagnetic recording medium even at the time of storage. CONSTITUTION:Permanent magnets 3, 4 and iron plates 5, 6 are fixed on upper and lower covers 1, 2 respectively and a magnetic field 7 oriented always in the same direction is generated in a case. About the center hole 10 of a photomagnetic disk 8, the diameter of the upper surface is different from that of the lower surface, also a disk holding board 11 of the lower cover 2 has a 2-stage shape, and only when the disk 8 is loaded so that the upper surface is correctly turned to the upper direction, the disk 8 can be stored in the case. If the permanent magnets 3, 4 are set up so as to be contacted with each other when the disk 8 is correctly stored, the upper and lower covers 1, 2 are locked by magnetic force and can not be easily opened. The magnetic field 7 oriented always in the same direction is printed on a magnetic film 9 of the disk 8.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a storage case for storing a magneto-optical disk or a case for a magneto-optical recording medium such as a cartridge, and particularly to a case for preventing the disappearance of recorded information during disk storage. The present invention relates to the structure of a suitable storage container.

[Background of the invention]

The substrate of an optical disk is made of a glass plate or plastic plate, and it is easy to get dirt or scratches on the disk substrate.

In order to prevent damage, they are stored in a cartridge in advance or in a case during storage (for example, see Japanese Patent Laid-Open No. 157879/1983).

The storage environmental conditions for magneto-optical disks are such that they can be used in offices and households in the same way as general magnetic tape and consumer optical disks.

There are no particularly strict rules. In read-only compact discs and video discs, information is recorded by the uneven bit shape of the disc reflective film, so the information does not disappear even during long-term storage. However, in magneto-optical disks, information is recorded by forming domains with different magnetization directions in the magnetic film, and the magnetization direction inside the domain differs by 180 degrees from the magnetization direction outside the domain. The resulting domain is locally unstable. Therefore, there is a risk that the recording domain diameter may decrease or disappear due to changes in storage environmental conditions such as temperature.

In conventional storage cases and cartridges for magneto-optical disks, no particular consideration has been given to preventing the above-mentioned recorded information from disappearing.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a storage container for a magneto-optical recording medium, which has a simple structure and is inexpensive, which can prevent information from disappearing during storage of the magneto-optical recording medium.

[Summary of the invention]

In a magneto-optical disk device, the present invention temporarily raises the temperature by irradiating the magnetic film with a light beam while applying an external magnetic field in the direction opposite to the magnetization direction of the unrecorded portion of the magnetic film, and then when cooling, the external magnetic field is applied. Focusing on the fact that information is recorded by magnetizing it in the direction of This prevents domains from disappearing and enables stable information storage.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. 1 and 2 are a perspective view and a sectional view showing an embodiment of the present invention, which is applied to a storage case for a magneto-optical disk. FIG. 1 is an external view of the case, where 1 is the upper cover of the case and 2 is the lower cover of the case. Figure 2 shows the first
This is a cross section taken along the line AA' in the figure.For convenience of explanation, the upper lid 1
There is a gap between the lower cover 2 and the disk 8. Permanent magnets 3 and 4 and iron plates 5 and 6 are connected to upper cover 1 and lower cover 2, respectively.
A magnetic field 7 is always generated in a fixed direction within the case. For example, the center hole 10 of the magneto-optical disk 8 has different hole diameters on the top and bottom surfaces, as shown in the figure, and the bottom differential 2
The disc holding stand 11 also has a two-tiered shape as shown in the figure, and is designed to be stored in the case only when the disc 8 is correctly placed with its top facing upward. When stored correctly, if permanent magnets 3 and 4 are in contact with each other,
There is also the effect that the upper lid 1 and lower lid 2 are locked by magnetic force, making them difficult to open. A magnetic field 7 in a constant direction is always applied to the magnetic film 9 of the disk 8 .

The principle of the present invention, which prevents erasure of information recorded on a magneto-optical disk by applying a constant magnetic field 7 during storage of the disk, will be explained with reference to FIG. Reference numeral 9 denotes a magnetic film, which is magnetized in the downward direction indicated by an arrow 13 perpendicular to the film surface. When the disk is mounted in a recording device and information is recorded, the magnetic film 9 is irradiated with a laser spot (not shown) while applying an external magnetic field H in the upward direction indicated by the arrow 15 opposite to the arrow 13. The magnetization rises and the magnetization disappears, and then, upon cooling, domains 12 magnetized in the same direction of the arrow 14 as the external magnetic field H are formed. In Figure 3.

The recording domain area is indicated by 10, and the area outside the domain is indicated by -. The recorded domain is unstable because the direction of magnetization is reversed inside and outside the domain.

Therefore, if the environmental temperature rises during disk storage, the domain diameter may become smaller or disappear. Therefore, if an external magnetic field H is applied during storage in the same direction as the arrow 15 during recording, the recording domain 12 will become stable.
It never disappears.

4 and 5 are a perspective view and a sectional view showing another embodiment of the present invention, which is applied to a magneto-optical disk cartridge. FIG. 4 is an external view of the cartridge body 20. For example, the cartridge body 20 is used to identify the top and bottom surfaces of the disk when the magneto-optical disk device is installed.
There is an uneven mark 22 only on the top surface. FIG. 5 is a sectional view taken along line BB' in FIG. 4. Windows 23 and 24 are provided on the upper and lower surfaces of the main body 20 for allowing an optical head or a magnetic head (electromagnet) to approach the disk 8 when a magneto-optical disk device is installed.
It's open. 21 is a hole for a spindle for rotating the disk 8. A permanent magnet 25 and iron plates 26 and 27 are fixed inside the cartridge body 20, and an iron plate 28 for keeping the windows 23 and 24 closed during storage.
and 29, a magnetic field 30 in a fixed direction is applied to the magnetic film 9 of the disk 8. Therefore, as described above, the action of the magnetic field 30 can prevent information recorded on the disk from disappearing.

〔Effect of the invention〕

According to the present invention, an inexpensive storage container for a magneto-optical recording medium having a simple structure has the effect of preventing information recorded on a magneto-optical recording medium from disappearing.

[Brief explanation of drawings]

1114 is an external view of a storage case for a magneto-optical disk showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A' in FIG. 11, and FIG. 3 is an illustration of the operating principle of the present invention. FIG. 4 shows another embodiment of the present invention, an external view of a cartridge for a magneto-optical disk, and FIG. 5 is a cross section taken along the line BB' in FIG. 4. It is a diagram. 1.2...Case, 3,4...Permanent magnet, 5,6...
... iron plate, 8 ... magneto-optical disk, 9 ... magnetic film,
20...Cartridge body, 25...Permanent magnet, 2
6.27゜＼Elm/ 1st mouth, 'fJ 2 ro

Claims (1)

[Claims] A storage container for a magneto-optical recording medium, characterized in that it is equipped with a permanent magnet and a magnetic circuit for always applying a static magnetic field in a fixed direction to the magneto-optical recording medium.