JPH0395740A - Magneto-optical disk - Google Patents

Abstract

PURPOSE:To protect information, which are written at the maker side, by providing a write protect board composed of a high magnetic permeability material on the surface of a disk to a recording area to which write protect is executed. CONSTITUTION:The necessary information are written into a prescribed area 2a in the outer peripheral part of a disk 2 by a magneto-optical recording system at the maker side and afterwards, a circular write protect board 1 is made. Thus, in an area where the write protect board 1 is not provided, when a vertical magnetic field 5 is applied in the recording on a user side, a laser beam 4 is image-formed in a recording layer 2-2 as a light beam spot since the magnetic field 5 is operated to the recording layer 2-2 on a substrate 2-4 protected by a protecting layer 2-1. Accordingly, in this recording layer 2-2, the direction of a magnetic domain can be set according to the information. In the area where the protect board 1 is provided, however, the vertical magnetic field 5 is guided into the write protect board since it is composed of the high magnetic permeability material. Thus, the vertical magnetic field does not arrive at the recording layer 2-2.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a magneto-optical disk as a recording medium used in a magneto-optical recording/reproducing device that writes and reads information using the magneto-optic effect. .

(Prior Art) Conventionally, in a magneto-optical disk used in a magneto-optical recording/reproducing device, a light beam spot is directed onto a recording layer formed on a substrate, and a perpendicular imffl field is applied to the spot to determine the direction of the magnetic domain. It is designed so that information can be recorded by changing the Generally, a Curie point recording method or a compensation point recording method is adopted as such a recording method.

In addition, pits for tracking and address reading have been present on the surface of magneto-optical disks from the beginning.

The magneto-optical disk generally has a hub 3 at the center of the disk 2, as shown in FIG. 5, and a spindle motor (not shown) applies rotational driving force to the hub 3. In addition, the disk 2 itself has a substrate 2-
A recording layer 2-2 sandwiched between protective layers 2-1 and 2-3 is provided on a substrate 2-4, and a laser beam 4 is irradiated from the substrate 2-4 side to form a light beam spot of a required size. An image is formed on the recording layer 2-2, and correspondingly, a perpendicular magnetic field 5 is applied to the recording layer 2-2 to set the direction of the magnetic domain and record information. Further, information can also be read from the reflected light of the laser beam 4 due to the force effect in each magnetic domain.

(Problem to be solved by the invention) Such magneto-optical disks are often provided to the user after being partially subjected to magneto-optical recording by the manufacturer. In order to do this, it is necessary to create this at the same time when creating the original disc.It is okay to use pits that are not likely to be changed later, such as pits for servo control. Regarding information, there is a practical problem in creating it at an early stage.Therefore, information is written onto the disk formed by the manufacturer using the magneto-optical recording method as described above. The information written in is the information that will be updated,
At that time, not all of the information is changed at once, but often only some of it is changed. This information is updated by the manufacturer, and the latest information is continuously updated and provided to the user. However, since the information recorded using the magneto-optical recording method can be easily accessed by the user, if the laser beam is accidentally irradiated and a magnetic field is applied, the information written by the manufacturer may be lost. There is a risk that some parts may be destroyed.

(Objective of the Invention) The present invention has been made based on the above circumstances, and it is an object of the present invention to provide a magneto-optical disk in which information written by the manufacturer before being distributed to the user can be write-protected. That is.

(Means for Solving the Problems) Therefore, in the present invention, information is recorded by shining a light beam spot on the recording layer formed on the substrate and applying a perpendicular magnetic field to the relevant location to change the direction of the magnetic domain. In a magneto-optical disk capable of carrying out this process, a write protect plate made of a high AI transmittance material is provided on the disk surface for a recording area to be write protected.

(Function) Therefore, since there is a high magnetic permeability material in this area, the external magnetic field does not reach the recording layer, so the information recorded here is protected and cannot be erased or rewritten by the user. It's fleeting.

(Example) Hereinafter, an example of the present invention will be specifically described with reference to the drawings. The first example of Ribbon is shown in Figure 1. Here, on the manufacturer's side,
After necessary information is written in a predetermined area 2a on the outer periphery of the disk 2 by magneto-optical recording, an annular write protect plate 1 is attached. Therefore, as shown in FIG. 2(a), when the user attempts to record in an area without the write protection plate 1, when a perpendicular magnetic field 5 is applied, the area is not protected by the protective layer 2-1. Recording layer 2- on the substrate 2-4
Since a magnetic field 5 acts on the recording layer 2-2, the laser beam 4 is imaged as a light beam spot on the recording layer 2-2, thereby making it possible to set the direction of the magnetic domain here according to the information.

However, as shown in FIG. 2(b), in some areas of the write protect plate 1, since the write protect plate 1 is made of a high magnetic permeability material, the vertical magnetic field 5 is generated within the write protect plate. The magnetic field is induced in the recording layer 2-2.
Therefore, even if the laser beam 4 is imaged as a light beam spot on the recording layer 2-2, the direction of the magnetic domain there will not be changed and rewriting or erasing will not be performed.

In the embodiment shown in FIG. 3, the area 2b of information to be recorded by one manufacturer is set at the inner circumference of the disk 2.
In yet another embodiment shown in FIG. 4, sector areas 2c and 2c'' are provided by the manufacturer symmetrically with respect to the rotational axis of the disk 2. This is a recording area on the side, and cut-out annular write protect plates 1 and 1' are mounted symmetrically with respect to the rotational axis.

In these embodiments, in the embodiment shown in FIG. 1, since the write protect plate 1 is provided on the outer circumferential side, the moment of inertia of the disk 2 increases, so that stable rotational interlocking can be obtained. Furthermore, in the case of the embodiment shown in FIG. 3, since the write protect plate l is provided on the inner circumferential side, the above-mentioned inertial effect is not sufficient. , can be set roughly, improving manufacturing yield. In the embodiment shown in Fig. 4, write protection can be performed in sector units, but due to rotational balance,
As mentioned above, it is necessary to provide the write protect plate 1.1' axially symmetrically. (Effects of the Invention) The present invention has been described in detail above, and by providing a write protect plate made of a high magnetic permeability material in a part of the magneto-optical disk, it is possible to protect the magneto-optical recording data provided by the manufacturer. , it is possible to avoid erroneous operations such as rewriting or deleting this on the user's side. Also, by visually checking whether the write protect plate is attached, it is possible to determine whether information has been written by the manufacturer. Furthermore, this write protection plate increases the moment of inertia of the disk, making it possible to obtain stable rotation.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of the present invention, Fig. 2(a)
3 and 4 are perspective views showing different embodiments, and No. 5I2I is a perspective view showing a conventional example. l...Write protect plate (high magnetic permeability material) 2...
Disc 2-1.2-3...Protective layer 2-2...Recording layer 2-4...Substrate 3...Hub

Claims (1)

[Claims] A record that should be write-protected in a magneto-optical disk in which information can be recorded by shining a light beam spot on a recording layer formed on a substrate and applying a perpendicular magnetic field to the area to change the direction of the magnetic domain. 1. A magneto-optical disk characterized in that a write protect plate made of a high magnetic permeability material is provided on the surface of the disk for a region.