JPS61148687A - Cartridge for photomagnetic disk - Google Patents

Abstract

PURPOSE:To improve a bias magnetizing characteristic by using a magnetizing member for a magnetic circuit section of a bias field of a cartridge accommodating a photomagnetic disk. CONSTITUTION:An electromagnet 16 is disposed so as to form a vertical field on a photomagnetic disk surface, and excited by a coil 18 for forming the field wound on a magnetic circuit 17. At an opposing side to the electromagnet with respect to the surface of the photomagnetic disk, an oscillating device 19 of a laser beam is placed, and the laser beam is irradiated on the photomagnetic disk as shown by arrows through an objective lens 20. A magnetic circuit 21 disposed in a cartridge is provided at an edge section of an opening section 22 of the cartridge on which the laser beam is irradiated and as a magnetizing material, for instance, soft iron and the like can be used. While the photomagnetic disk 11 shown by dotted lines is accommodated in the cartridge, the magnetic material 21 is placed in an edge section of the opening section 22 at the laser irradiating side 15 of the cartridge.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cartridge for protecting a magneto-optical disk, and more particularly to a structure of a magneto-optical disk cartridge for improving the magnetization characteristics of a bias magnetic field.

[Conventional technology]

In magneto-optical recording using a magneto-optical disk, recording and reproduction are performed on the surface of the magneto-optical disk using a laser beam irradiated from an optical head. In order to keep the magneto-optical disk in a constant magnetized state, a bias magnetic field is applied by a magnetic field forming electromagnet.

FIG. 5 is a perspective view of a conventional electromagnet for forming a magnetic field,
In this electromagnet, a magnetic field forming coil 1 magnetizes a magnetic pole 2 to form magnetic lines of force 3. In particular, the shorter the distance between the tip of the magnetic pole and the magneto-optical disk surface, the better the magnetization characteristics to the magneto-optical disk surface. If the distance is about 2 to 3 III, an effective magnetic field can be obtained and a predetermined bias magnetic field can be applied to the magneto-optical disk surface.

On the other hand, in order to protect the optical-magnetic disk surface, magneto-optical disks are housed in cartridges.
If magneto-optical recording is performed while the magneto-optical disk is stored in the cartridge, the thickness of the cartridge will be added to the thickness of the magneto-optical disk, increasing the overall thickness and increasing the distance between the tip of the electromagnet and the surface of the magneto-optical disk. 4-5III+
As a result, the magnetization efficiency of the bias magnetic field required for recording and reproduction deteriorates, so it has not been practical to perform magneto-optical recording while the magneto-optical disk is housed in a cartridge.

Furthermore, in order to bias magnetize the magneto-optical disk surface, it is most effective to apply a perpendicular effective magnetic field, but in the conventional electromagnet structure, the magnetic field is diffused at the tip of the magnetic pole to form a perpendicular magnetic field. The structure is inappropriate for this purpose.

[Problem that the invention seeks to solve]

If magneto-optical recording is performed with the magneto-optical disk having the above configuration stored in the cartridge, the thickness of the cartridge will be added, which will increase the gap between the electromagnet and the surface of the magneto-optical disk, deteriorating the magnetic field characteristics. Another problem is that the structure of the electromagnet is not suitable for applying a magnetic field perpendicular to the magneto-optical disk surface, so it has become practical to perform magneto-optical recording with the magneto-optical disk still in the cartridge. This will cause the problem that it is not done properly.

[Means for solving problems]

The present invention provides a magneto-optical recording device that solves the above-mentioned problems, and the present invention provides a magneto-optical disk device in which a bias magnetic field is applied to a magneto-optical disk and is equipped with a laser irradiation device. This can be achieved by a magneto-optical disk cartridge in which a magnetic circuit portion for the bias magnetic field is made of a magnetic material.

[Effect]

The present invention provides a method for performing magneto-optical recording in a magneto-optical recording device with a magneto-optical disk housed in a cartridge.
A magnetic body is provided in a portion of the magneto-optical cartridge corresponding to the bias magnetic field to form a magnetic circuit, and the reluctance of the magnetic circuit is reduced to reduce the effective gap between the magneto-optical disk and the magnetic pole. As a result, it is possible to apply an effective bias magnetic field to the magneto-optical disk.

〔Example〕

FIG. 1 is a perspective view for explaining a magneto-optical disk cartridge which is an embodiment of the present invention.

The magneto-optical disk 11 consists of a recording layer 12 as an intermediate layer and transparent plastic layers 13 formed on both sides of the recording layer 12.
This magneto-optical disk has an upper surface 14 and a lower surface 15 of the cartridge made of non-magnetic material such as aluminum.
It is stored in the gap and protected.

The electromagnet 16 is arranged so as to form a perpendicular magnetic field on the magneto-optical disk surface, and is excited by a magnetic field forming coil 18 wound around a magnetic circuit 17. On the opposite side of the magneto-optical disk surface from the electromagnet, there is a laser beam. There is a light oscillation device 19,
The laser beam is irradiated onto the magneto-optical disk through the objective lens 20 as shown by the arrow.

According to the present invention, the magnetic circuit 21 provided in the cartridge is provided at the edge of the opening 22 of the cartridge to which the laser beam is irradiated, and soft iron or the like may be used as the magnetic material.

FIG. 2(a) is a plan view of the electromagnet side of the cartridge of the present invention shown in FIG. 1, and FIG. 2(b) is a plan view from the laser irradiation direction.

A magneto-optical disk 11 indicated by a dotted line in FIG. 2 (bl) is housed in a cartridge, and a magnetic material 21 is disposed at the edge of an opening 22 on the laser irradiation side 15 of the cartridge.

FIG. 3 shows another embodiment of a magneto-optical disk cartridge of the present invention, in which a magnetic body 31 is provided on the electromagnetic side of the cartridge to form a magnetic circuit to improve the efficiency of bias magnetization. The numbers are according to Figure 1.

FIG. 4(a) is a plan view of the electromagnet side of the cartridge of the present invention in FIG. 3, and FIG. 2(b) is a plan view from the direction in which the laser is irradiated.

A magneto-optical disk 11 indicated by a dotted line in FIG. 4(a) is housed in a cartridge, and a magnetic body 31 is arranged in a portion of the cartridge corresponding to the magnetic pole portion 17 of the electromagnet.

In addition, according to the present invention, it is possible to further improve the magnetization efficiency by providing a magnetic material on both sides of the cartridge in a combined state of FIG. 1 and FIG. 3, thereby further improving the magnetization characteristics. I can do it.

〔Effect of the invention〕

As described above in detail, the magneto-optical disk cartridge of the present invention has the great effect of improving bias magnetization characteristics and providing a high-quality magneto-optical disk device.

[Brief explanation of drawings]

FIG. 1 is a perspective view for explaining the magneto-optical disk cartridge of the present invention, FIG. 2(a) is a top view of the magneto-optical disk cartridge of the present invention, FIG. 2(b) is a bottom view, and FIG. 3 is a perspective view for explaining another embodiment of the magneto-optical disk cartridge of the present invention, FIG. 4(a) is a top view of the magneto-optical disk cartridge of the present invention, and FIG. 4(b) is a perspective view for explaining another embodiment of the magneto-optical disk cartridge of the present invention. The bottom view, FIG. 5, is a perspective view of a conventional magnetic field forming electromagnet.
1 is a magneto-optical disk, 12 is a recording layer, 13 is a transparent plastic layer, 14 is an upper surface of a cartridge, 15 is a lower surface of a cartridge, 16 is an electromagnet, 17 is a magnetic circuit, 18 is a coil for forming a magnetic field, and 19 is a laser beam generator. An oscillator, 20 is an objective lens, 21 is a magnetic material at the edge of the opening, 22 is an opening of the cartridge, and 31 is a magnetic material provided in the cartridge on the electromagnet side.

Claims (1)

[Claims] A magneto-optical disk device in which a bias magnetic field is applied to a magneto-optical disk and is equipped with a laser irradiation device, characterized in that a magnetic circuit portion of the bias magnetic field of a cartridge that accommodates the magneto-optical disk is made of a magnetic material. Cartridge for discs.