JP3403423B2 - Magneto-optical system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium constructed of a magneto-optical recording medium and a drive device for detachably mounting the magneto-optical recording medium to record, reproduce and erase information. In particular, the present invention relates to an arrangement of an external magnetic field necessary for recording, reproducing and erasing information and an information overwriting method.

[0002]

2. Description of the Related Art At least one optical head and at least one external magnetic field are required for recording, reproducing and erasing information on a magneto-optical recording medium. The arrangement method of the optical head and the external magnetic field with respect to the magneto-optical recording medium includes (a) a method of arranging the optical head and the external magnetic field together on one side of the magneto-optical recording medium, and (b) via the magneto-optical recording medium. There is a system in which an optical head and an external magnetic field are separately arranged on both surfaces of the optical head.

In the former case (a), both the optical head and the external magnetic field are mounted on the chassis of the drive device,
Since a mechanism for driving the optical head and the external magnetic field in a direction of approaching or separating from the magneto-optical recording medium is not required, it is advantageous in reducing the thickness, weight and cost of the drive device. On the other hand, on the other hand, it is difficult to place an external magnetic field close to the laser beam irradiation part, so a relatively large external magnetic field is required, and high speed seek performance is inferior, or design around the head becomes very difficult. is there. Under these circumstances, the latter method (b) has been widely used from the past.

There are a so-called optical modulation method and a magnetic field modulation method as a signal recording method for a magneto-optical recording medium. In a drive apparatus of the optical modulation method, a permanent magnet piece is used as an external magnetic field, and a magnetic field modulation method is used. In the above drive device, an electromagnetic head capable of generating a DC magnetic field or an AC magnetic field is used as an external magnetic field.

[0005]

However, the latter (b)
As shown in FIG. 30, when the magneto-optical recording medium (magneto-optical disk) 1 is mounted on the medium driving unit (rotary spindle) 2 provided in the drive device, the optical head 3 and the external magnetic field (magnetic head) 4 must be arranged close to each surface of the magneto-optical disk 1. Therefore, the optical head 3 is set at a predetermined position in advance, and when the magneto-optical disk 1 is mounted on the rotary spindle 2, one surface of the magneto-optical disk 1 and the optical head 3 are arranged with a predetermined space therebetween. In addition to the above, the magnetic head 4 is lowered after the magneto-optical disk 1 is mounted on the rotary spindle 2 so that the magneto-optical disk 1 is disposed at a predetermined distance from the other surface of the magneto-optical disk 1. Alternatively, the optical head 3 and the magnetic head 4 are opposed to each other at a predetermined interval in advance, and both heads 3 and 4 are provided.
After inserting the magneto-optical disk 1 between the two, the magneto-optical disk 1, the optical head 3, and the magnetic head 4 descend while keeping a predetermined gap, and the magneto-optical disk 1 is mounted on the rotary spindle 2. You will need it.

Whichever mechanism is adopted, at least a mechanism for moving the magnetic head 4 up and down is required, and a magnetic head moving space for moving the magnetic head 4 on the medium 1 is provided. In addition, since a control device for controlling the position of the magnetic head 4 and the optical head 3 with high precision is required, the device becomes complicated, thick, heavy and costly. However, since a high-output and high-capacity power source is required, there is a very serious drawback that a portable device using a battery as a power source cannot be used for a long time. Further, since both heads 3 and 4 must be integrally sought in the track arrangement direction, the weight of the head device is large and the high-speed seek performance is poor. Furthermore, because it is a dedicated device for magneto-optical recording media,
Other types of optical information recording media such as a write-once type (write-once type) cannot be used in common, and there are drawbacks such as low versatility. In order to solve the deficiency of the prior art,
It is necessary to devise the structure and arrangement of the external magnetic field.

In addition, since the magneto-optical system is expected as an information recording system having a high recording density, which is an alternative to the magnetic recording system, the effective data transfer rate must be as high as that of magnetic recording. It is necessary to build a magneto-optical system capable of overwriting information.

The present invention has been made to solve the above problems, and an object thereof is to provide a magneto-optical system which is small and lightweight and can be used for a long time with a small battery, and optical information recording of other types. It is an object of the present invention to provide a magneto-optical system excellent in versatility capable of sharing a medium and to provide a magneto-optical system capable of overwriting information.

[0009]

In order to achieve the above object, the present invention provides a magneto-optical disk rotatably housed in a disk cartridge, and a magneto-optical disk which is detachably mounted to record information. In a magneto-optical system constructed of a drive device for reproducing and erasing, a spindle for rotating the magneto-optical disk and a laser beam are radiated to the magneto-optical disk on opposite sides of the disk cartridge as the disk cartridge. Window holes for inserting the optical heads are opened respectively, and shutters capable of individually opening and closing the window holes are attached to the inner surface of the disk cartridge, and recording and reproducing of the information on the inner surface of each of these shutters. As the external magnetic field required for erasing, a structure provided with a vertically magnetized magnet is used.

In order to achieve the above object, the present invention provides the magneto-optical system having the above-mentioned structure, wherein one perpendicular magnetizing magnet is provided for each surface of the magneto-optical disk. An optical head for irradiating a laser beam is provided at a position facing each other at the set position of the perpendicular magnetizing magnet and on the upstream side in the driving direction of the magneto-optical disk.

Further, according to the present invention, in order to achieve the above-mentioned object, in the magneto-optical system having the above-mentioned structure, two perpendicular magnetized magnets are provided for each surface of the magneto-optical disk, and one optical magnet is provided opposite to the magnet. The head is provided.

[0012]

When the external magnetic field is attached to the existing shutter, a special device for attaching the external magnetic field and its driving device are not required. Therefore, the structure around the head is simplified, and the drive device is reduced in size and weight. The cost can be reduced. Further, since only the optical head needs to be driven, the head device to be sought is reduced in weight and the high-speed seek property is improved. Furthermore, the drive device configuration is the same as that of the read-only type or write-once type (write-once type) drive device in which only the optical head is arranged facing the optical information recording medium. By devising the system, it becomes possible to share any optical information recording medium, and the versatility of the device is enhanced.

In the magneto-optical system having the above structure, the magneto-optical disk has a magneto-optical recording film having magnetic anisotropy in a direction perpendicular to a film surface and a perpendicular magnetization auxiliary film magnetized in a direction opposite to an external magnetic field. And a single perpendicular magnetizing magnet for the external magnetic field facing one surface of the magneto-optical disk, and irradiating the magneto-optical recording film with a pulsed signal-modulated laser beam. And a coercive force of the perpendicular magnetization auxiliary film is larger than an external magnetic field acting from the perpendicular magnetizing magnet and larger than a coercive force of the magneto-optical recording film at the time of low-level laser beam irradiation. During high-level laser beam irradiation, the coercive force of the perpendicular magnetization auxiliary film is larger than the external magnetic field acting from the perpendicular magnetization magnet, and If the temperature-coercive force characteristics of the magneto-optical recording film and the perpendicular magnetization auxiliary film are set so that the coercive force of the perpendicular magnetization auxiliary film becomes smaller than the external magnetic field strength from the perpendicular magnetization magnet acting on the magnetic recording film. During irradiation of a low-level laser beam, the magnetic field strength acting on the magneto-optical recording film from the perpendicular magnetization auxiliary film is larger than the external magnetic field strength acting on the magneto-optical recording film from the perpendicular magnetization magnet, and the magneto-optical recording film is protected. Because it is larger than the magnetic force,
The direction of the magnetization of the magneto-optical recording film is aligned with the direction of the magnetization of the perpendicular magnetization auxiliary film regardless of the previous state, and the magnetic field strength that acts on the magneto-optical recording film from the perpendicular magnetization auxiliary film during high-level laser beam irradiation. Becomes smaller than the external magnetic field strength acting on the magneto-optical recording film from the perpendicular magnetized magnet,
Since the direction of magnetization of the magneto-optical recording film is reversed to the direction of the external magnetic field, information can be overwritten.

In the magneto-optical system having the above-mentioned structure, the magneto-optical disk having a magneto-optical recording film having a magnetic anisotropy in a direction perpendicular to the film surface and a perpendicular magnetization auxiliary film is used, and the magneto-optical disk is used. The magnetic recording medium is provided with two strip-shaped perpendicular magnetizing magnets for external magnetic fields having opposite polarities facing each other on one surface of the magnetic disc and facing one strip-shaped perpendicular magnetizing magnet arranged on the downstream side in the rotation direction of the magneto-optical disc. And an optical head for irradiating the magneto-optical recording film with a pulsed signal-modulated laser beam,
At room temperature, the coercive force of the perpendicular magnetization auxiliary film is smaller than the external magnetic field acting from the other strip-shaped perpendicular magnetization magnet arranged on the upstream side in the moving direction of the magneto-optical recording medium, and at the time of low-level laser beam irradiation. In the above, the coercive force of the perpendicular magnetization auxiliary film is larger than the external magnetic field acting from the one strip-shaped perpendicular magnetized magnet and larger than the coercive force of the magneto-optical recording film, and at the time of high-level laser beam irradiation, The temperature-coercive force characteristics of the magneto-optical recording film and the perpendicular magnetization auxiliary film so that the coercive force of the magneto-optical recording film and the perpendicular magnetization auxiliary film is smaller than the external magnetic field acting from the one strip-shaped perpendicular magnetization magnet. If set, the coercive force of the perpendicular magnetization auxiliary film at room temperature will be reduced from the other perpendicular magnetization magnet arranged on the upstream side in the rotation direction of the magneto-optical disk. Since the intensity of the external magnetic field acting on the direct magnetization assisting film becomes smaller than that of the other perpendicular magnetization magnet at the stage of passing through the other perpendicular magnetization magnet regardless of the previous state of the magnetization of the perpendicular magnetization assisting film. When the laser beam is irradiated at a low level, the magnetic field strength acting on the magneto-optical recording film from the perpendicular magnetization auxiliary film is aligned with the magnetization direction, and one of the perpendicular magnetizations is arranged on the downstream side in the rotation direction of the magneto-optical disk. It is larger than the external magnetic field acting on the magneto-optical recording film from the magnet and larger than the coercive force of the magneto-optical recording film, so that the magnetization direction of the magneto-optical recording film does not change regardless of the previous state. When the high-level laser beam is irradiated, the coercive forces of the magneto-optical recording film and the perpendicular magnetization auxiliary film are both produced from the one perpendicular magnetization magnet. Smaller than the external magnetic field intensity, the direction of magnetization of the magneto-optical recording film and a perpendicular magnetization auxiliary film together reversed in the direction of the external magnetic field, information becomes possible overwriting.

Further, in the magneto-optical system having the above-mentioned structure, the magneto-optical disk provided with a magneto-optical recording film having magnetic anisotropy in a direction perpendicular to the film surface is used, and one surface of the magneto-optical disk. A strip-shaped perpendicular magnetizing magnet for external magnetic fields having opposite polarities opposite to each other, and two optical heads respectively arranged opposite to these strip-shaped perpendicular magnetizing magnets for external magnetic fields. Of these two optical heads, one of the two optical heads, which is arranged on the upstream side in the rotation direction of the magneto-optical disk, irradiates the magneto-optical recording film with a laser beam having a constant intensity to erase information, Of the two optical heads, the other optical head, which is arranged on the downstream side in the rotational direction of the magneto-optical disk, outputs a pulse-wise signal-modulated laser beam to the magneto-optical recording. If recording information by irradiating the film,
An erasing optical head is provided by providing an erasing optical head and a perpendicular magnetizing magnet on the upstream side in the rotating direction of the magneto-optical disk and a recording optical head and a perpendicular magnetizing magnet on the downstream side in the rotating direction of the magneto-optical disk. Since the previously recorded information can be erased by using the magnetic recording medium and the perpendicular magnetizing magnet, the information can be recorded subsequently to the track after the erasing by the recording optical head and the perpendicular magnetizing magnet. Overwrite can be realized.

[0016]

EXAMPLE A magneto-optical system according to an example will be described below with reference to FIGS.
This will be described with reference to FIG.

As shown in FIGS. 1 and 2, the disc cartridge 11 has window holes 19a and 19b of the same shape and the same size, which are formed at the opposite positions of the lower half 12 and the upper half 13, and the inner surface of the lower half 12 and Shutters 14a and 14b that can be independently opened and closed are provided on the inner surface of the upper half 13, and magnets 22 and 23 of one line are provided on the inner surfaces of the shutters 14a and 14b, respectively.
It is mounted in the radial direction passing through the center of a. In each of the magnets 22 and 23, the center axis of the light beam of the optical heads 3a and 3b is the center in the width direction of the magnet, even when any recording surface of the double-sided recording type magneto-optical disk 1 faces the optical heads 3a and 3b. It is arranged so as to face the optical head so as to pass through.

The lower half 12 and the upper half 13 are formed in a shallow dish shape in which a joining wall 16 of a constant height is erected along the periphery, and on the side portions on the mounting side of the shutters 14a and 14b. The slider accommodating portion 17 is recessed. Also,
A slider 15a integrally fixed to the shutter 14 is provided on a part of the joining wall 16 that constitutes the slider housing portion 17,
A guide protrusion 18 for attaching 15b and holding it slidably is formed. The height of the guide projection 18 is lower than the height of the joining wall 16.
A rotating spindle 2 for rotating the magneto-optical disk 1 and optical heads 3a, 3b for irradiating the magneto-optical disk 1 with a laser beam are provided in a portion extending from the substantially central portion of the lower half 12 to a portion where the guide projection 18 is formed. Window holes 19a and 19b for inserting the disk cartridge 11 are provided.

The lower half 12 and the upper half 13 are, for example, ABS resin, AS resin, vinyl chloride resin, polypropylene resin, polycarbonate resin, polyacrylate resin, polymethylmethacrylate resin, polytetrafluoroethylene resin, and these resin materials. It can be formed by using a material in which a filler or carbon is mixed.

As the magnets 22 and 23,
(1) Co, Fe, Ni, Co-Ni alloy, Co-Cr
Alloy, Co-P alloy, Co-Ni-P alloy, Al-Co
Alloy, Al-Ni-Co alloy, etc. formed into a strip shape and perpendicularly magnetized, (2) γ-Fe ₂ O ₃ powder, Co-containing F
Magnetic powder such as e ₂ O ₃ powder, Fe ₃ O ₄ powder, Co-containing Fe ₃ O ₄ powder, Fe powder, Co powder, and Fe-Ni alloy powder is applied with a binder and an organic solvent, dried, and then perpendicularly magnetized. (3) Co, Fe, Ni, Co-N
i alloy, Co-Cr alloy, Co-P alloy, Co-Ni-
A ferromagnetic material such as a P alloy, an Al-Co alloy, or an Al-Ni-Co alloy, which is vacuum-deposited by using a vacuum deposition method or a sputtering method and perpendicularly magnetized, (4) Te-F
e-Co alloy, Te-Fe-Co-Cr alloy, Te-F
e-Co-Nb alloy, Gd-Dy-Fe-Co alloy, T
A spontaneous magnetization ferromagnetic perpendicular magnetization film made of an amorphous alloy containing a rare earth element and a transition element as a main component, such as an e-Gd-Fe-Co-Cr alloy, (5) A spontaneous magnetization ferromagnetic perpendicular magnetization similar to (4) above. Ni, Co, Cr on the outer surface of the magnetic film
Any material such as a material coated with a corrosion resistant material such as can be used. Among these, those described in (2) to (5) above are particularly preferable because they can be formed into a thin shape.

The magnets 22 and 23 are set along the radial direction (direction perpendicular to the recording track) of the magneto-optical disk 1. The width can be set to any value in the order of micron order or sub-micron order to the order of 50 mm, but preferably, the window hole 19 is formed when the disk cartridge 11 is inserted into the drive device.
It is set to a value that is larger than the sum of the fluctuation width of the insertion device of the optical heads 3a and 3b inserted in a and 19b and the length of the minimum magnetization domain and the fluctuation width of the laser beam. The length of the magnets 22 and 23 is
The length is formed so as to cover at least the recording area of the magneto-optical disk 1. The magnets 22 and 23 do not necessarily have to be formed in a continuous shape, and fine magnets 22 and 23 may be arranged in a straight line. In this case, the length of each of the fine magnets 22 and 23 can be made larger than the track pitch.

The magnets 22 and 23 are preferably arranged as close to the disk surface as possible, and the surfaces of the magnets 22 and 23 are opposed to the disk surface with a desired narrow gap when the disk rotates. It is used by adjusting the height of the magnet mount or the thickness (film thickness) of the magnets 22 and 23. It should be noted that a smooth coating having excellent abrasion resistance and abrasion heat resistance is applied to the surface of the magneto-optical disk 1 facing the magnet, and a coating having excellent lubricity and abrasion resistance is also formed on the surfaces of the magnets 22 and 23. However, the magnets 22 and 23 can be brought into sliding contact with the disk surface through these films.

The shutters 14a, 14b have window holes 19a,
19b is formed in a flat plate shape that can be opened and closed, and sliders 15a and 15b for operating the shutters 14a and 14b from the outside are attached to one end thereof. The lower half 12 and the upper half 1 are attached to the sliders 15a and 15b.
The guide projection 18 formed on the 3 can be gently inserted into the 2
The grooved grooves 18a and 18b are formed to face each other, and the shutters 14a and 14b are housed in the disk cartridge 11, and the guide projections 18 are inserted into the grooved grooves 18a and 18b. The combination of the slider 14b and the sliders 15a and 15b is slidably attached to the disk cartridge 11, and the shutters 14a and 14b
b is slidably set on the inner surfaces of the lower half 12 and the upper half 13, respectively. At this time, the sliders 15a, 15
Since b is accommodated in the slider accommodating portion 17 provided in the disc cartridge 11 in a recessed manner, it does not project to the outside of the disc cartridge 11.

Shutters 14a, 14b or slider 15
A return spring (not shown) is stretched between a and 15b and the lower half 12. Therefore, unless the sliders 15a and 15b are operated from the outside, the window holes 19a and 19b are closed by the shutters 14a and 14b, and foreign matter such as dust is prevented from entering. When the shutters 14a and 14b are driven in the opening direction against the elastic force of the return spring, the window 1
9a and 19b are opened, and the turntable 2 and the optical head 3 can be inserted into the disc cartridge 11.

The shutters 14a and 14b and the sliders 15a and 15b can be formed using a resin material, a ceramic material, a metal material (in particular, stainless steel) or the like. These shutters 14a and 14b and sliders 15a and 15b
Although it is possible to mechanically bond the two separately formed, it is more preferable that they are integrally molded to facilitate manufacturing.

In FIG. 2, reference numeral 51 is a shutter opening / closing arm provided in the drive device, 52a and 52b are shutter retainers provided on the lower half 12 and the upper half 13, respectively, and 53a and 53b are formed on the sliders 15a and 15b. The shutter opening / closing arm engagement holes 90a and 90b are guide holes for guiding the sliders 15a and 15b. Each of the sliders 15a and 15b has a wide portion 53 having a width substantially equal to the thickness of the disk cartridge 11.
And the narrow portion 54 having a width that is approximately half the thickness of the disc cartridge 11, the planar shape is formed in a substantially L shape. These sliders 15a and 15b are shown in FIG.
As shown in FIG. 5, the narrow width portion 54 of one slider is inserted into the missing portion of the other slider to form a rectangular shape, and then the disk cartridge 11 is assembled.

That is, one slider 15a is slidably attached to the guide projection 18a formed on the lower half 12, and the tip of one shutter 14a formed integrally with the slider 15a has the lower half 12 at its front end. It is slidably engaged with one shutter press 52a formed on the.
The other slider 15b is slidably attached to a guide protrusion 18b formed on the upper half 13, and the other shutter 14b integrally formed with the slider 15b.
The front end of the shutter is slidably engaged with the other shutter retainer 52b formed on the lower half 13. Guide hole 90a,
90b is covered by a slider.

As shown in FIG. 2, the disk cartridge 11 of this embodiment having the above-described structure has one slider 1
The shutter opening / closing arm 5 is inserted into the engagement hole 53a formed in the 5a.
By engaging the front end of the first shutter 14a and urging the shutter 14a integrally formed with the slider 15a in the opening direction A, the shutter 14a and the slider 15
Only a can be opened. Further, the disk cartridge 11 is turned upside down, and as shown in FIG. 7, the tip end portion of the shutter opening / closing arm 51 is engaged with the engagement hole 53b formed in the other slider 15b to be integrally formed with the slider 15b. By biasing the other shutter 14b in the opening direction B, only the other shutter 14b and the slider 15b can be opened.

As the magneto-optical disk 1, a double-sided recording type magneto-optical disk 1 having a perpendicular magnetization auxiliary film is used. 3 to 5 show a magneto-optical disk having a single plate structure provided with a perpendicular magnetization auxiliary film. Double-sided recording type magneto-optical disk 1
Is produced by concentrically attaching two single-plate magneto-optical disks.

The magneto-optical disk 1 shown in FIG.
has a, on the SiO ₂ film 42 of SiO ₂ film 42 a disc-shaped transparent substrate 41 formed on one surface of a transparent substrate 41
The first enhancement film 43 made of an inorganic dielectric material having a slightly higher refractive index than that, the magneto-optical recording film 44, the in-plane magnetization film (horizontal magnetization film) 48, and the perpendicular magnetization auxiliary film 49 having reflectivity.
And a metal reflection film 46 are sequentially laminated, and each of these films 4
3 to 46 are covered with a protective film 47 such as an ultraviolet curable resin. The in-plane magnetized film 48 may be a light reflective film. Further, instead of the in-plane magnetized film 48, a magnetic material that is not spontaneously magnetized, such as magnetic stainless steel, Ni,
An alloy material such as Fe, Co or Cr can also be used.

The magneto-optical disk 1 shown in FIG. 4 has a first enhance film 43, a magneto-optical recording film 44, an in-plane magnetized film 48, and a reflective property on the SiO ₂ film 42 of the transparent substrate 41 similar to the above. And a vertical magnetization assisting film 49 having the above structure are sequentially laminated, and each of these films 43 to 49 is covered with a protective film 47. Also in this example, a light-reflecting film can be used as the in-plane magnetized film 48, and instead of the in-plane magnetized film 48, a magnetic material that does not spontaneously magnetize, for example, magnetic stainless steel, Ni, Fe, Co. Alloy materials such as Cr and Cr can also be used.

In the magneto-optical disk 1 shown in FIG. 5, the first enhance film 43, the first in-plane magnetized film 48a, and the magneto-optical recording film 44 are formed on the SiO ₂ film 42 of the transparent substrate 41 similar to the above.
And a second in-plane magnetized film 48b are sequentially laminated, each of these films 48a to 48b is covered with a light-reflective perpendicular magnetized film 49, and the outer surface of the perpendicular magnetized film 49 is covered with a protective film 47. It has a different structure. Also in the case of this example, a light-reflecting film can be used as the in-plane magnetized films 48a and 48b, and instead of the in-plane magnetized film 48b, a magnetic material that is not spontaneously magnetized, such as magnetic stainless steel, Ni, Fe, Co, C
Alloy materials such as r can also be used.

The materials for the in-plane magnetized films 48a and 48b are Co--Ni alloy, Pt--Co--Ni alloy, and Cr--.
In addition to Co-Ni alloys, [Rh, Pd, Ag, Ir, P
t] at least one selected from the group of elements and [Fe,
At least 1 selected from the group of transition elements of Co, Ni]
An alloy composed of seeds is used.

Even if the in-plane magnetized films 48a and 48b are not specially formed, the same effect as the formation of the in-plane magnetized film can be obtained by performing the following film formation. That is, N
This is to interpose a metal film of i, Tb, Gd, Fe, Co, Cr, Pt or the like. Alternatively, the outer surface of the magneto-optical recording film is subjected to a reaction treatment with oxygen gas or nitrogen gas, exposed to the atmosphere for a certain period of time, or the magneto-optical recording film is formed in the presence of the atmosphere, oxygen or nitrogen. Just do it. Especially, by fixing the transparent substrate in the vacuum sputtering device,
S is applied during air depressurization vacuum of 0 to ³ to 10 to ⁶ Torr.
On the iO ₂ film and the enhancement film (SiN film), Tb-F
By simply forming the magneto-optical recording film of an alloy such as e-Co by sputtering, the surface of the magneto-optical recording film can achieve the same effect as when the in-plane magnetized film is formed separately. Therefore, the magneto-optical recording film subjected to this treatment can be treated in the same manner as the case where the in-plane magnetized film is separately formed.

As a material of the perpendicular magnetization auxiliary film 49,
Te-Fe-Co-Nb alloy, Gd-Tb-Fe alloy,
Te-Fe-Co alloy, Te-Fe-Cr alloy, Te-
Fe-Co-Cr alloy, Co, Fe, Ni, Co-Ni
Alloy, Co-Cr alloy, Pt-Co alloy, Pd-Co alloy, Al-Co alloy, Al-Ni-Co alloy, Co-R
An e alloy, a Co-Rd alloy, a Ce-Pt alloy, or the like is used.

When an in-plane magnetized film is used as the protective film 47,
The material or alloy used for the in-plane magnetized film 48 is formed by vacuum vapor deposition or sputtering (vacuum sputtering), or γ-Fe ₂ O ₃ powder, Fe ₃ O ₄ powder, Co.
A mixture of Fe ₂ O ₃ powder, Fe powder, Co powder, Fe—Ni alloy powder, etc., and an epoxy resin mixed with an adhesive solution consisting of an organic solvent and a binder is applied, dried and magnetized. May be.

If each of the shutters 14a and 14b is provided with two magnets, the perpendicular magnetization auxiliary film 49 is formed.
It is also possible to use a double-sided recording type magneto-optical disk having no. Of course, there is no problem even if a double-sided recording type magneto-optical disk having the perpendicular magnetization auxiliary film 49 is housed in the disk cartridge 11 having two magnets formed on one surface.

FIG. 6 shows an example of a magneto-optical disk having a single plate structure without the perpendicular magnetization auxiliary film 49. That is, the magneto-optical disk of this example has the center hole 1a, and has SiO 2 on one side.
_{2 The} Si of the disk-shaped transparent substrate 41 on which the film 42 is formed
On the O ₂ film 42, a first enhance film 43 made of an inorganic dielectric material having a slightly higher refractive index than the transparent substrate 41, a magneto-optical recording film 44, and an inorganic dielectric material similar to the first enhance film 43. The second enhancement film 45 and the metal reflection film 46
Are sequentially stacked, and each of these films 43 to 46 is covered with a protective film 47 such as an ultraviolet curable resin. The protective film 47 can also be formed by using an in-plane magnetized film having excellent corrosion resistance.

Another example of a double-sided recording disk cartridge applicable to the magneto-optical system according to the first embodiment will be shown below.

FIG. 8 is a partially sectional perspective view showing a second example of the double-sided recording disk cartridge. The sliders 15a and 15b of this example are entirely the disk cartridge 1
1 has a width approximately half the thickness of each slider 1
Engaging step portions 55a and 55b of the shutter opening / closing arm are formed on the upper surfaces of 5a and 15b in directions opposite to each other. Others are the same as in the case of the first example above,
The description is omitted.

FIG. 9 is a plan view of an essential part showing a third example of a double-sided recording disk cartridge, FIG. 10 is its plan view, and FIG.
FIG. 24 is a sectional view taken along the line CC ′ of FIG. 23. In these figures, reference numeral 56 indicates an engaging member of the shutter opening / closing arm, 57 indicates a guide rail of the engaging member 56, and the same reference numerals are displayed on the other portions corresponding to those of FIGS. 1 and 2. ing. As shown in FIG. 11, the guide rail 57 is formed parallel to the guide protrusions 18a and 18b of the sliders 15a and 15b, and the engaging member 56 is formed on the guide rail 57.
It is slidably mounted on. On the other hand, the slider 15a,
15b are arranged on both sides of the engaging member 56, respectively.
Of course, each slider 15a, 15b has a shutter 14
a and 14b are integrally formed.

As shown in FIG. 9, in the disk cartridge of this embodiment having the above-described structure, the tip of the shutter opening / closing arm 51 is engaged with the engaging member 56, and the engaging member 56 is used for one shutter 14a. Opening direction A or the other shutter 1
By biasing in the opening direction B of 4b, each shutter 1
4a and 14b can be opened individually. Others are the same as those in the case of the above-mentioned first example, and therefore description thereof will be omitted.

FIG. 12 is a plan view of an essential part showing a fourth example of a double-sided recording disk cartridge, FIG. 13 is a plan view thereof, and FIG.
4 is a cross-sectional view taken along the line DD ′ of FIG. 12, and FIG. 15 is a perspective view of an essential part partially sectioned. As is clear from these figures, in the double-sided recording disk cartridge of the present example, one ends of the two sliders 15a and 15b are butted against each other, and the shutter opening / closing arm 51 is provided at the butted ends of the respective sliders 15a and 15b. Recessed portions 58a and 58b for engaging the front end portions of the are recessed. Of course, shutters 14a and 14b are integrally formed on the sliders 15a and 15b. The shutters 14a and 14b are structured to slide inside the case. Others Figure 1 above
The same reference numerals are given to the portions corresponding to those in FIG. 2 and the description thereof will be omitted.

As shown in FIGS. 12 and 15, the disc cartridge of this embodiment having the above-described structure has a recessed portion 5 as shown in FIG.
8a and 58b are engaged with the front end of the shutter opening / closing arm 51, and the sliders 15a and 15b are urged in the opening direction A of one shutter 14a or the opening direction B of the other shutter 14b. Can be opened individually.

FIG. 16 is an exploded perspective view showing a fifth example of a double-sided recording disk cartridge, FIG. 17 is a sectional view in a joined state, FIG. 18 is a sectional view showing the principal part of a first example of a disk retainer, and FIG. 19 is a disk. FIG. 20 is a cross-sectional view of an essential part showing a second example of the pressing, and FIG. 20 is a cross-sectional view of an essential part showing the third example of the disk pressing. As is apparent from FIGS. 17 and 20, the double-sided recording disk cartridge of this example has a shutter 14a,
It is characterized in that disk retainers 59a and 59b are provided at positions facing the rotary spindle insertion portion of 14b.
The disk retainers 59a and 59b are formed on a disk having substantially the same diameter as the turntable 5 by using a magnetic material such as a ferromagnetic metal material or a non-magnetic material in which a magnet 60 is embedded in the disk facing surface as shown in FIG. The shutter 14
It is rotatably attached to a and 14b.

The disc retainers 59a and 59b are shown in FIG.
As shown in FIG. 5, the shutters 14a and 14b are provided with a recessed portion 61 on the disk facing surface, and a holding plate 62 for covering a part of the recessed portion 61 is provided on the front surface of the shutters 14a and 14b and the holding plate 62. By gently mounting the mounting portions 63 of the disk retainers 59a and 59b in the space formed by, the shutters 14a and 14b can be rotatably mounted. Further, as shown in FIG. 19, the shutters 14a and 14b are provided with disk holders 59a,
A through hole 64 having a diameter smaller than the diameter of 59b is opened, and
A shutter mounting groove 65 is attached to the disc retainers 59a and 59b.
Is formed and the through hole portion of the shutter is gently installed in the mounting groove 65, so that the shutter can be rotatably mounted on the shutters 14a and 14b. 18 and 19
In the figure, reference numeral 92 in the figure denotes a ferromagnetic plate. Furthermore, as shown in FIG. 20, the recesses 61 are provided on the outer surfaces of the shutters 14a and 14b, and a holding plate 62 that covers a part of the recesses 61 is provided on the front surface of the shutters 14a and 14b. By gently mounting the mounting portions 63 of the disc retainers 59a and 59b in the space formed by the holding plate 62, the disc retainers 59a and 59b can be rotatably attached to the shutters 14a and 14b. Since the other configurations are the same as those of the above-mentioned respective embodiments, the same reference numerals are given to the portions corresponding to the drawings showing the respective embodiments, and the description thereof will be omitted. When the shutter is not provided, the disc retainer 59b and the magnets 22a and 23a are provided.
Even if they are attached directly to the inner wall of the disc cartridge, the same operational effects as when these are attached to the shutter can be obtained.

As shown in FIG. 17, the disc cartridge of this example is opened in the central portion of the magneto-optical disc 1 by opening the lower shutter 14b and inserting the rotary spindle 2 through the opened window hole 19a. The rotary spindle 2 is inserted into the center hole 1a to center the magneto-optical disk 1. Also, the magneto-optical disk 1 is a turntable 5
The magneto-optical disk 1 is placed on the surface and positioned in the surface direction. Then, at this stage, the magnet 66 embedded in the tip of the rotary spindle 2 attracts the disc holder 59a, and the magneto-optical disc 1 is clamped by the attraction force. Therefore, when the disk cartridge of this example is used, it is not necessary to provide a magnetic center hub on the magneto-optical disk 1, so that the structure of the magneto-optical disk 1 is simplified and the clamp member for the magneto-optical disk 1 is provided on the drive device side. The size, weight and cost of the drive device can be reduced as compared with the case of setting.

FIG. 21 is an exploded perspective view showing a sixth example of a double-sided recording disk cartridge, FIG. 22 is a sectional view in a joined state, and FIG. 23 is a sectional view taken along the line DD ′ in FIG. As is clear from these figures, the double-sided recording disk cartridge of the present embodiment is characterized in that the tray 71 is detachably housed in the disk cartridge 11 together with the magneto-optical disk 1. As shown in FIGS. 21 and 22, the tray 71 has a circular recess 72 capable of accommodating the magneto-optical disk 1.
And a window hole 73 is formed in a portion from the end surface on the insertion side into the disc cartridge 11 to the substantially central portion of the concave portion 72.
And a knob 75 formed along one side thereof. on the other hand,
As shown in FIG. 24, a window hole 19 is formed in the lower half 12 and the upper half 13 of the disk cartridge 11.
a and 19b are opened, and the shutters 14a and 1 are provided on the inner surface thereof.
4b is set. Then, each shutter 14a, 1
On the inner surface of 4b, as shown in FIG.
a, 23a or 22b, 23b are provided.

The disc cartridge of this example is composed of the tray 7
Since 1 is removably accommodated, the magneto-optical disk 1 can be taken out from the disk cartridge 11 together with the tray 71 and transported or stored. Since the tray 71 is smaller than the disc cartridge 11, a large number of magneto-optical discs 1 can be stored in a storage box of a fixed capacity, and a large number of discs can be conveyed at one time, and the storage efficiency is also improved. be able to. Further, since the magneto-optical disk 1 can be handled while being placed on the tray 71, it is possible to prevent the magneto-optical disk 1 from being soiled.

In the double-sided recording type magneto-optical system, the double-sided recording type magneto-optical disk 1 is mounted on the turntable 5 with the surface on which signal recording, reproduction and erasing are to be performed facing downward. Only one shutter 14a facing the magneto-optical disk 1 is opened, and the optical heads 3a and 3b are inserted through the lower window hole 19a. The laser beam 6a emitted from the recording optical head 3a is positioned at a portion facing the magnet 22b provided on the shutter 14b which is not opened on the upper side, and the laser beam 6b emitted from the erasing side optical head 3b is magneto-optical. By positioning the disc 1 on the upstream side in the rotation direction, it becomes possible to erase and record a signal on the disc. Further, by positioning the laser beam for reproduction on the recording track, it becomes possible to reproduce the signal. Similarly, by mounting the double-sided recording type magneto-optical disk 1 on the turntable 5 with its front and back reversed, it is possible to record, reproduce, and erase signals on the other disk.

In this example, the two optical heads 3a and 3b for recording and erasing are inserted into the window hole 19a, but by changing the film structure of the magnet and the magneto-optical disk, etc. It is also possible to perform signal recording, reproduction, erasing, etc. by using only one optical head.

A method of recording, reproducing, erasing a signal using the above-mentioned magneto-optical system will be described below with reference to FIGS.

FIG. 24 shows a signal recording, reproducing and erasing method when two magnets and one optical head are used. As shown in the figure, first, the optical head 3 has two magnets 22, It is located in the intermediate position of 23. An actuator (not shown) for swinging the optical axis of the laser beam 6 to the upstream side and the downstream side in the rotation direction of the magneto-optical disk 1 is provided in the optical head 3. On the other hand, the magneto-optical disk 1 is provided with the magneto-optical recording film 44 as a single layer. The magnets 22 and 23 are magnetized in a direction perpendicular to the film surface of the magnets, and each of the magnets 22 and 2 is magnetized.
The directions of magnetization of No. 3 are opposite to each other.

In such a structure, the laser beam 6
Is moved to the upstream side in the rotation direction of the magneto-optical disk 1 and positioned on the setting portion of the magnet 22, and the laser beam 6 having a constant intensity is
When a is irradiated with a, the magneto-optical recording film 44 is heated to near the Curie temperature or the compensation temperature, and the magneto-optical recording film 44 is
Has a coercive force lower than that of the magnet 22 and the magnetization direction of the magneto-optical recording film 44 is aligned with a predetermined initial magnetization direction or erase direction, and the previously recorded signal is erased. Then, in the next stage, the laser beam 6 is swung to the downstream side in the rotational direction of the magneto-optical disk 1 so as to be positioned opposite to the magnet 23, and the laser beam 6b modulated by a desired signal is irradiated.
, The coercive force of the portion heated to near the Curie temperature or the compensation temperature is lower than the magnetization intensity of the magnet 23, the magnetization direction of the portion is inverted to the magnetization direction of the magnet 23, and the signal is recorded. To be done. Thus, in the case of this example, the two laser beams 6a and 6b are focused on the magnets 22 and 23 passing through the optical head 3, and the information is erased by the combination of the laser beam 6a and the magnet 22.
Information can be overwritten by irradiating the magnet 23 with the modulated light beam 6b in focus.

FIG. 25 shows a signal recording, reproducing and erasing method when one magnet and one optical head are used. Two types of beams A and B for irradiating the laser beam 6 on the upstream side and the downstream side in the rotation direction of the magneto-optical disk 1 are introduced into the optical head 3. On the other hand, the magneto-optical disk 1 has a magneto-optical recording film 44 and an in-plane magnetized film 48.
And a perpendicular magnetization auxiliary film 49 having a high reflectance. The perpendicular magnetization auxiliary film 49 has a coercive force of the magnet 2
It is magnetized in advance in a direction opposite to the magnetization direction of the magnet 22 and larger than the strength of spontaneous magnetization of No. 2. The strength of magnetization of the magnet 22 is set to be larger than the strength of magnetization of the perpendicular magnetization auxiliary film 49.

In such a structure, when the laser beam 6a having a constant intensity is irradiated to the upstream side in the rotating direction of the magneto-optical disk 1 and the magneto-optical recording film 44 is heated to near its Curie temperature or compensation temperature, The coercive force of the recording film 44 becomes lower than the magnetization intensity of the perpendicular magnetization auxiliary film 49, and the magnetization direction of the magneto-optical recording film 44 is aligned with the magnetization direction of the magnetization auxiliary film 49, and the previously recorded signal is recorded. Is erased. Therefore, this time, the laser beam is positioned so as to face the magnet 22 of the magneto-optical disk 1 and is irradiated with the laser beam 6b modulated by a desired signal.
The coercive force of the portion heated up to near the Curie temperature or above the compensation temperature is lower than the magnetic field strength of the magnet 22, and the magnetization direction of the portion is inverted to the magnetization direction of the magnet 22. Will be recorded. Here, for example, the Curie temperature of the perpendicular magnetization auxiliary film 49 is magneto-optical so that the magnetization direction of the perpendicular magnetization auxiliary film 49 is not affected by the magnetization intensity of the magnet 22 at the temperature rise of the magneto-optical recording film 44. The material is much higher than the Curie temperature of the film, and the coercive force is larger than the magnetic field strength of the magnet 22 even when the magneto-optical recording film is heated to near the Curie temperature.

FIG. 26 shows a signal recording, reproducing and erasing method when one magnet and two optical heads are used. As shown in FIG. 26, one optical head 3a faces the magnet 22. In addition to being positioned, the other optical head 3b is positioned further upstream than it in the rotational direction of the magneto-optical disk 1. The magneto-optical recording film 44 is sandwiched by in-plane magnetized films 48a and 48b, and a perpendicular magnetization auxiliary film 49 is formed in contact with the in-plane magnetized films 48a and 48b. Magneto-optical recording film 4
4 and the magnetic relationship between the perpendicular magnetization auxiliary film 49 and the magnet 22 are the same as in the case of FIG.

In such a structure, when the laser beam 6a having a constant intensity is irradiated from the other optical head 3a and the temperature of the magneto-optical recording film 44 is raised to near the Curie temperature or the compensation temperature thereof, the magneto-optical recording film 44 is irradiated. The coercive force is lower than the magnetic field strength of the perpendicular magnetization auxiliary film 49, and the magneto-optical recording film 4
The magnetization direction of No. 4 is aligned with the magnetization direction of the perpendicular magnetization auxiliary film 49, and the previously recorded signal is erased. Therefore, this time, when the laser beam 6b modulated by a desired signal is emitted from one of the optical heads 3b, the magneto-optical recording film 4 is formed.
4, the coercive force of the portion heated to near the Curie temperature or the compensation temperature is lower than both the magnetic field strength formed by the magnetic force of the magnet 22 and the magnetic force of the perpendicular magnetization auxiliary film 49, and the perpendicular magnetization auxiliary film. Under the influence of the magnet 22 having a magnetic field strength higher than 49, the magnetization direction of the magneto-optical recording film 44 is inverted to the magnetization direction of the magnet 22, and a signal is recorded.

The effect of the embodiment shown in FIG. 26 is that the optical head first erases the signal at the position 3a, and then the optical head 3
It can also be obtained by an information recording method in which the laser beam is moved to the position of b and is irradiated with the modulated laser beam to reverse the magnetization direction of the magneto-optical recording film 44 to the magnetization direction of the magnet 22. However, if two optical heads are used, there is a special effect that high-speed transfer and overwriting are possible. Alternatively, one optical head uses two laser beams, one laser beam is applied to the position 3a, and the other laser beam is irradiated with the laser beam 3b.
With the method of irradiating the position, the same effect as in the case of using the above two optical heads can be obtained.

FIG. 27 shows a signal recording, reproducing, and erasing method when two magnets magnetized in opposite directions and one optical head are used.
As shown in (b), the optical head 3 is configured to move and be positioned between a portion facing the first magnet 22 and a portion facing the second magnet 23. The magneto-optical recording layer 44 is composed of a single layer.

In such a configuration, as shown in FIG.
As shown in (c), the optical head 3 is positioned so as to face the first magnet 22 provided on the upstream side in the rotation direction of the magneto-optical disk 1, and a laser beam 6a having a constant intensity is emitted from the optical head 3 to emit light. When the temperature of the magnetic recording film 44 is raised to near the Curie temperature or the compensation temperature, the coercive force of the magneto-optical recording film 44 becomes lower than the magnetization intensity of the first magnet 22, and the magnetization of the magneto-optical recording film 44 is reduced. The direction is aligned with the direction of magnetization of the first magnet 22, and the previously recorded signal is erased. Therefore, this time, FIG. 27 (b),
As shown in (d), the optical head 3 is positioned so as to face the second magnet 23 provided on the downstream side in the rotation direction of the magneto-optical disk 1, and the laser beam 6b modulated by a desired signal is emitted from the optical head 3. Upon irradiation, the coercive force of the portion of the magneto-optical recording film 44 heated to near the Curie temperature or the compensation temperature is lower than the magnetization intensity of the second magnet 23, and the magnetization direction of the portion is the second direction. The signal is recorded by being reversed in the direction of the magnetization of the magnet 23. In this case, the drive device is provided with a control circuit for moving the optical head from the position facing the erasing magnet to the recording magnet position. In the embodiment of FIG. 27, if two optical heads are used, information can be erased at the position of the magnet 22 and, at the same time, information can be recorded at the position of the McNet 23 by irradiation with a modulated laser beam. The same effect as is obtained.

Next, an information overwrite method based on the light intensity modulation method will be described.

FIG. 28 is a diagram showing a first example thereof, and as shown in FIGS. 28A and 28B, a magneto-optical disk 1 having a magneto-optical recording film 44 and a perpendicular magnetization auxiliary film 49, 1
The system is constructed by the strip-shaped magnet 22 for the external magnetic field and the optical head 3 for irradiating the magneto-optical recording film 44 with the laser beam which is pulse-modulated. The perpendicular magnetization auxiliary film 49 is magnetized in the direction opposite to the magnetization direction of the magnet 22. Further, the magneto-optical recording film 44 and the perpendicular magnetization auxiliary film 49 have a coercive force H of the perpendicular magnetization auxiliary film 49 when the low-level laser beam (higher than the reproducing beam intensity) shown in FIG. ₄₉ is greater than the external magnetic field H ₂₂ which acts from the magnet 22, and greater than the magnetic field strength H ₄₄ of the magneto-optical recording film 44, FIG. 28
At the time of high-level laser beam irradiation shown in (c), the coercive force H ₄₉ ′ of the perpendicular magnetization auxiliary film 49 causes the magnet 2 to move.
The temperature-coercive force characteristic is set so that it is still larger than the external magnetic field acting from 2.

According to the system of this example, the coercive force H ₄₉ of the perpendicular magnetization assisting film ₄₉ is changed to the magnet 22 when the low-level laser beam is irradiated, as shown in FIG.
Larger than the external magnetic field M ₂₂ acting from and since the magnetic field intensity M ₄₉ perpendicular magnetization auxiliary layer 49 is greater than the magnetic field strength H ₂₂ coercivity H ₄₄ and the magnet 22 of the magneto-optical recording film 44, the magneto-optical recording film The magnetization direction of 44 is aligned with that of the perpendicular magnetization auxiliary film 49 regardless of the previous state. Also, during high-level laser beam irradiation,
Since the magnetic field intensity M ₄₉ perpendicular magnetization auxiliary layer 49 is smaller than the external magnetic field M ₂₂ acting from the magnet 22, the direction of magnetization of the magneto-optical recording film 44 is reversed in the direction of the external magnetic field, the information is overwritten .

FIG. 29 shows a second information overwrite method.
FIG. 30 is a diagram showing an example, and as shown in FIGS. 29A and 29B, a magneto-optical disk 1 having a magneto-optical recording film 44 and a perpendicular magnetization auxiliary film 49, and two stripes whose polarities are opposite to each other. A system is constructed from the band-shaped magnets 22 and 23 for the external magnetic field, and the optical head 3 which is arranged so as to face the band-shaped magnet 23 on the downstream side and irradiates the magneto-optical recording film 44 with a pulsed signal-modulated laser beam. ing. At room temperature, the magneto-optical recording film 44 and the perpendicular magnetization auxiliary film 49 have a coercive force H _{49 ″} of the perpendicular magnetization auxiliary film 49 smaller than the external magnetic field strength M ₂₂ acting from the magnet 22 arranged on the upstream side. 29C, the coercive force H ₄₉ of the perpendicular magnetization auxiliary film 49 is larger than the external magnetic field strength M ₂₃ acting from the magnet 23 and the magneto-optical recording film 44 is irradiated with the laser beam at the low level shown in FIG. When the laser beam is irradiated at a high level which is higher than the magnetic field strength M ₄₄ shown, the coercive force H ₄₄ ′ of the magneto-optical recording film 44 and the coercive force H ₄₉ ′ of the perpendicular magnetization auxiliary film 49 both act from the magnet 23. The temperature-coercive force characteristic is set so as to be smaller than the magnetic field M ₂₃ .

According to the system of this example, at room temperature, the coercive force H _{49 ″} of the perpendicular magnetization auxiliary film 49 causes the magnet 2 to move.
Since it is smaller than the external magnetic field H _{22 which} acts from 2, the perpendicular magnetization auxiliary film 49 is passed through the magnet 22.
Only the direction of magnetization is aligned with the direction of magnetization of magnet 22 regardless of the previous state. Further, at the time of low-level laser beam irradiation, the coercive force H ₄₉ of the perpendicular magnetization auxiliary film 49 causes the external magnetic field strength M acting from the magnet 23.
Greater than _23, and since the magnetic field intensity M ₄₉ indicated by the perpendicular magnetization auxiliary layer 49 is stronger than the magnetic field intensity M ₂₃ showing coercivity H ₄₄ and the magnet 23 of the magneto-optical recording film 44, the magnetization of the magneto-optical recording film 44 Is aligned with the magnetization direction of the perpendicular magnetization auxiliary film 49 regardless of the previous state. Then, at the time of high-level laser beam irradiation, the coercive force H ₄₄ ′ of the magneto-optical recording film 44 and the coercive force H of the perpendicular magnetization auxiliary film 49.
External magnetic field strength M that ₄₉ 'acts from the magnet 23 together
_Since it is smaller than _23, the magnetization directions of the magneto-optical recording film 44 and the perpendicular magnetization auxiliary film 49 are reversed to the direction of the external magnetic field H ₂₃ , and information is overwritten.

[0067]

As described above, according to the present invention,
Since the external magnetic field is attached to the existing shutter, a special device for attaching the external magnetic field and its driving device are unnecessary. Therefore, the structure around the head is simplified, and the drive device can be made smaller, lighter, and lower in cost. Further, since only the optical head needs to be driven, the head device to be sought is reduced in weight and the high-speed seek property is improved. Furthermore, since the internal configuration of the drive device is the same as that of the read-only type and the write-once type (write-once type) drive device, any optical information recording medium can be shared by devising a signal recording / reproducing system. It is also possible to increase the versatility of the device.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing a configuration of a magneto-optical system according to an example.

FIG. 2 is an explanatory diagram showing a first example of a disc cartridge.

FIG. 3 is a main-portion cross-sectional view showing a first example of the film structure of the magneto-optical disk.

FIG. 4 is a cross-sectional view of essential parts showing a second example of the film structure of the magneto-optical disk.

FIG. 5 is a cross-sectional view of essential parts showing a third example of the film structure of the magneto-optical disk.

FIG. 6 is a cross-sectional view of essential parts showing a fourth example of the film structure of the magneto-optical disk.

FIG. 7 is a plan view of the disc cartridge according to the first example.

FIG. 8 is a partially sectional perspective view showing a second example of the disk cartridge.

FIG. 9 is a plan view of an essential part showing a third example of a disk cartridge.

FIG. 10 is a side view of a disk cartridge according to a third example.

11 is a cross-sectional view taken along the line CC ′ of FIG.

FIG. 12 is a plan view showing a fourth example of a disc cartridge.

FIG. 13 is a side view of a disc cartridge according to a fourth example.

14 is a cross-sectional view taken along the line DD ′ of FIG.

FIG. 15 is a perspective view, partly in cross section, of a disk cartridge according to a fourth example.

FIG. 16 is an exploded perspective view showing a fifth example of a disc cartridge.

FIG. 17 is a cross-sectional view of a disk cartridge according to a fifth example in use.

FIG. 18 is a sectional view showing a first example of a disc retainer.

FIG. 19 is a sectional view showing a second example of the disc retainer.

FIG. 20 is a cross-sectional view showing a third example of the disc retainer.

FIG. 21 is an exploded perspective view showing a sixth example of a disc cartridge.

FIG. 22 is a sectional view of a disc cartridge according to a sixth example in a joined state.

23 is a cross-sectional view taken along the line DD ′ of FIG.

FIG. 24 is an explanatory diagram showing a first example of a recording / erasing method.

FIG. 25 is an explanatory diagram showing a second example of a recording / erasing method.

FIG. 26 is an explanatory diagram showing a third example of a recording / erasing method.

FIG. 27 is an explanatory diagram showing a fourth example of a recording / erasing method.

FIG. 28 is an explanatory diagram showing a first example of an information overwrite method.

FIG. 29 is an explanatory diagram showing a second example of the information overwrite method.

FIG. 30 is an explanatory diagram of a conventionally known magneto-optical system.

[Explanation of symbols]

1 Magneto-optical disk 2 rotating spindle 3 (3a, 3b) Optical head 5 turntable 6 laser beam 11 disk cartridge 14a, 14b shutter 15a, 15b slider 19a, 19b window holes 22,23 magnet

Claims (3)

(57) [Claims] 1. A magneto-optical system comprising a magneto-optical disk rotatably housed in a disk cartridge and a drive unit for removably mounting the magneto-optical disk to record, reproduce and erase information. In the disc cartridge, a spindle for rotationally driving the magneto-optical disc and a window hole for inserting an optical head for irradiating the magneto-optical disc with a laser beam are respectively formed in opposite portions on both sides, and The inner surface of the disk cartridge is covered with a shutter capable of opening and closing the windows independently, and the inner surface of each of these shutters is provided with a perpendicular magnetizing magnet as an external magnetic field necessary for recording, reproducing and erasing the information. A magneto-optical system characterized by being used. 2. The magneto-optical system according to claim 1, wherein one perpendicular magnetizing magnet is provided per surface of the magneto-optical disk, and the perpendicular magnetizing magnet is provided at a position facing the magnetizing magnet in the drive device. 2. A magneto-optical system characterized in that an optical head for irradiating a laser beam is provided at each of the set position and the upstream side in the driving direction of the magneto-optical disk. 3. The magneto-optical system according to claim 1, wherein two perpendicular magnetizing magnets are provided for each surface of the magneto-optical disk, and one optical head is provided opposite to the magnet. And magneto-optical system.