JPH04195748A - Magnetooptic recording medium - Google Patents

Abstract

PURPOSE:To eliminate a head crush, a rotating irregularity, etc., by reducing the surface roughness of the surface of a wear resistant protective film by smoothing, calendering, etc. CONSTITUTION:A recording section 5 is laminated on one main surface of a board 4 of a magnetooptic disk 1, and further the surface of the section 5 is covered sequentially with an ultraviolet ray curable resin layer 6 and a wear resistant protective film 7. The maximum height Rmax of the surface roughness of the film 7 is 2mum or less. Thus, the film 7 is formed on the sliding surface of a magnetic head. In this manner, durability against a wear, a damage, etc., is sufficiently obtained, and a problem such as an irregularity in rotation, a head crush, etc., is eliminated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magneto-optical recording medium used in a magneto-optical recording method in which recording is performed by sliding a magnetic head on the magneto-optical recording medium. be.

[Summary of the invention]

The present invention provides a magneto-optical recording medium in which a recording magnetic layer is formed on a transparent substrate. This is intended to ensure sufficient durability even when the head is slid.

[Conventional technology]

In the magneto-optical recording method, the temperature of a part of a magnetic thin film is raised above the Curie point or temperature compensation point, and the coercive force in this part is extinguished to reverse the direction of magnetization in the direction of the externally applied recording magnetic field. The basic principle is that optical file systems, computer external storage devices, audio,
It is being put into practical use in video information recording devices and the like.

The magneto-optical recording medium used in this magneto-optical recording method consists of a recording magnetic layer (having an axis of easy magnetization perpendicular to the film surface and having a large magneto-optic effect) on the entire surface of a transparent substrate made of polycarbonate or the like. For example, a recording section is formed by laminating a rare earth-transition metal alloy amorphous thin film), a dielectric layer, and a dielectric layer, and the signal is read by irradiating a laser beam from the transparent substrate side. Are known.

[Problem to be solved by the invention]

By the way, magneto-optical recording methods can be broadly divided into optical modulation methods and magnetic field modulation methods, and because they can be overridden, expectations for the magnetic field modulation methods are increasing.

The above-mentioned magnetic field modulation method writes information signals in a magnetic thin film by reversing the applied magnetic field at high speed, and the application of the magnetic field is usually performed by a magnetic head having a magnetic field generating means.

In this case, a magnetic head that applies a high-speed switching magnetic field can only generate a very small magnetic field due to various restrictions, and it is necessary to move the magnetic head as close to the recording magnetic layer as possible. For example, in the case of a magneto-optical disk for data recording, the distance between the magneto-optical disk surface and the magnetic head must be 0.1M or less.

When the distance between the magneto-optical disk and the magnetic head becomes narrow in this way, it is necessary to improve the dimensional accuracy of the magneto-optical disk to suppress surface runout in order to prevent crashes of the magnetic head.

However, with a magneto-optical disk made of a substrate or polycarbonate, there is a limit to the suppression of surface runout, so a servo is applied to keep the distance between the magnetic head and the magneto-optical disk constant, such as the focus servo of an optical pickup. Or, as with the /%-do disk, there is no choice but to adopt a so-called flying throat.

However, especially in systems with low rotation speeds of around 300 to 600 rpm, the flying throat cannot be used.
Complex servos are required to control the distance.

In addition, in the case of a high-speed rotation system with a rotation speed of about 3,600 rpm, it is possible to use a flying head in which the magnetic head floats via an air bearing, but it is necessary to avoid the problem of crashing when starting and stopping. There is.

Furthermore, even when using servo to maintain a constant distance from the disk, or when using a flying head, the distance between the magnetic head and the magneto-optical disk must be maintained. Also on the magneto-optical disk side, the recording magnetic layer must be a magnetic thin film that allows writing in a low magnetic field.

Therefore, a magneto-optical recording method may be considered in which recording is performed by sliding a magnetic head against a magneto-optical recording medium, but in this case, an important issue is how to ensure durability and runnability.

The present invention was proposed to solve this problem, and has sufficient durability even when the magnetic head is slid.
An object of the present invention is to provide a magneto-optical recording medium that can ensure running performance.

[Means to solve the problem]

In order to achieve the above object, the magneto-optical recording medium of the present invention is a magneto-optical recording medium in which a recording magnetic layer is formed on a transparent substrate, in which a wear-resistant protection is provided on the surface opposite to the transparent substrate. A film is formed thereon, and the wear-resistant protective film has a surface roughness or a maximum height Rm aw of 2 μm or less.

[Effect]

When recording is performed while the magnetic head slides against the magneto-optical recording medium, the distance to the recording magnetic layer becomes sufficiently small, and the magnetic field generated by the magnetic head can be small. Furthermore, no special servo mechanism is required for the magnetic head, and problems such as crashes are eliminated.

However, in this case, an increase in error rate due to wear and damage to the magneto-optical recording medium becomes a problem, but in the magneto-optical recording medium of the present invention, a wear-resistant protective film is formed on the sliding surface of the magnetic head. This ensures sufficient durability against wear and damage.

Further, since the wear-resistant protective film has a surface roughness of 2 μm or less at the maximum height R1,1, problems such as rotational unevenness and head crash are also solved.

〔Example〕

Embodiments to which the present invention is applied will be described in detail below with reference to the drawings.

First, FIG. 1 shows a schematic configuration of a magneto-optical recording device for recording information signals on a magneto-optical disk according to this embodiment.
) between the optical pickup (2) and magnetic head (3).
The magnetic head (3) is placed facing the magneto-optical disk (1) and records signals while sliding the magnetic head (3) on the magneto-optical disk (1).

As shown in FIG. 2, the magneto-optical disk (1) of this embodiment used in such a recording device has a recording section (5) laminated on the -main surface of a substrate (4), and this recording section The surface of (5) is coated with ultraviolet curing resin layer (6) and wear-resistant protective film (7).
).

The substrate (4) is a disk-shaped transparent substrate with a thickness of several meters (for example, 1.2 mm), and its material may include plastic materials such as acrylic resin, polycarbonate resin, polyolefin resin, and epoxy resin. , glass, etc. are also used.

Note that the surface of this substrate (4) includes the recording section (5).
Guide grooves, address code pits, etc. (both not shown) having a depth of approximately one-fourth of the wavelength of the laser light used during reproduction are usually provided on the surface on the side where the information is provided.

The recording section (5) includes a recording magnetic layer (8), a dielectric layer (9),
(10) and a reflective layer (11), and has a four-layer structure consisting of a substrate (4), a first dielectric layer (9), a recording magnetic layer (
8), the second dielectric layer (10), and the reflective layer (11).

Among these, oxides, nitrides, etc. can be used as the first dielectric layer (9) and the second dielectric layer (lO), but in the dielectric layers (9) and (10), Nitride is more preferable since oxygen in the atmosphere may have an adverse effect on the recording magnetic layer (8), and silicon nitride, aluminum nitride, etc. are preferable as substances that do not allow oxygen and moisture to pass through and can sufficiently transmit the laser beam used. is suitable.

Further, the recording magnetic layer (8) is an amorphous magnetic thin film having an easy magnetization direction perpendicular to the film surface, and has not only excellent magneto-optical properties but also a large coercive force at room temperature. , and it is desirable to have a Curie point near 200°C. Recording materials that meet these conditions include rare earth-transition metal alloy amorphous thin films, among which T
bFeC.

Amorphous thin films are preferred. This recording magnetic layer (8) may contain additives such as Cr for the purpose of improving corrosion resistance.

The reflective layer (11) is preferably composed of a film with a high reflectance that reflects 70% or more of the laser beam at the boundary with the second dielectric layer (lO), and is preferably a vapor-deposited film of a non-magnetic metal. be. Further, it is desirable that this reflective layer (11) is a good thermal conductor, and aluminum is suitable in consideration of ease of availability and ease of film formation.

Each of these layers is formed by a so-called vapor plating technique such as vapor deposition or sputtering. At this time, the thickness of each layer can be set arbitrarily, but it is usually set to about several hundred to several thousand. It is preferable that these film thicknesses be determined not only by the optical properties of each layer alone, but also by taking into account the effects of the combination.

For example, when the thickness of the recording magnetic layer (8) is thinner than the wavelength of the laser beam, multiple interference occurs between the laser beam and the light that passes through the recording magnetic layer (8) and is reflected at the boundaries of each layer. This is because the effective optical and magneto-optical properties of the recording magnetic layer (8) vary greatly depending on the combination of thicknesses.

The ultraviolet curing resin layer (6) is provided for the purpose of flattening and protecting the surface of the recording section (5), but may be omitted depending on the case. The thickness of this ultraviolet curable resin layer (6) is about 3 to 5 μm, and acrylic ultraviolet curable resin or the like is usually used.

The above is the basic configuration of the magneto-optical disk (1),
In the magneto-optical recording medium of the present invention, since magnetic field modulation recording is performed while the magnetic head (3) is slid on the disk surface, the magnetic head (3) is placed on the ultraviolet curing resin layer (6) or on the recording section (5). A wear-resistant protective film (7) is provided directly on the magnetic head (3) to suppress wear caused by sliding and ensure running performance of the magnetic head (3). Below, this wear-resistant protective film (7
) will be explained.

First, the wear-resistant protective film (7) formed on the sliding surface of the magnetic head of the magneto-optical disk (1) is basically a resin-cured film made of thermosetting resin, electron beam curing resin, ultraviolet curing resin, etc. or a resin cured film partially blended with electron beam curing resin or ultraviolet curing resin.

For example, by irradiating an electron beam-curable oligomer with an electron beam and curing it to form a wear-resistant protective film (7), a magneto-optical disk that is less likely to be damaged when a magnetic head comes into contact with it can be obtained. In this case, the molecular weight of the oligomer used is 2
000 or less is preferable.

Similarly, a strong film can be formed by blending an ultraviolet curable resin into the wear-resistant protection M (7) and curing it by irradiating it with ultraviolet rays immediately after forming the protective film (7).

Alternatively, when forming the wear-resistant protective film (7), a curing agent may be added internally to improve the film strength and increase durability. In this case, the molecular structure and type of the curing agent used are arbitrary, and it is also possible to use multiple types of curing agents. The amount of curing agent added depends on the type of curing agent used, but is usually 0.00 parts by weight per 100 parts by weight of the resin.
The amount is preferably 1 to 50 parts by weight. In addition, the curing temperature is arbitrary, and curing at room temperature is possible, or because the curing speed is slow, create a predetermined temperature environment (for example, above the glass transition point) in a constant temperature bath, and cure by placing it in that temperature for a certain period of time. It is preferable to increase the speed.

The heat curing treatment is advantageous not only in shortening the reaction time but also in terms of removing residual solvent and moisture and improving film hardness. As curing progresses and the curing agent becomes glassy, the film quality can be made harder and durability can be improved.

When the cured resin film is used as the abrasion-resistant protective film (7) as described above, suitable methods for forming it include a method using a doctor blade, a method using a spin cord, and the like.

For example, by placing paint uniformly on a flat adapter between a doctor blade and a magneto-optical disk (+) and moving the doctor blade toward you, a coating film with a uniform thickness is formed. Alternatively, by attaching the magneto-optical disk (1) to the motor rotation shaft and supplying paint onto the magneto-optical disk (1) while rotating to form a coating film, a coating film with even thickness can be formed. . These methods are not only easy to form a film, but also allow for uniform film thickness.
Furthermore, by controlling the solid content and viscosity of the paint, it is possible to control the surface roughness and film thickness.

In addition, when mass production is considered, a gravure method, a sandblast transfer method, an offset method, etc. are also suitable.

In the gravure method, for example, a magneto-optical disk (1) is mounted on the outer peripheral surface of a disk holder with the magnetic head side surface facing outward, paint is supplied from a paint nozzle between an inkneri roll and a gravure roll, and the disc holder is By running the gravure roll while pressing it with a back roll, the paint on the surface of the gravure roll is transferred to the magnetic head side surface of the magneto-optical disk (1). When transferring paint, the thickness can be controlled by the position of the back roll and the pattern depth of the gravure roll. After the paint is transferred, it is flattened and dried with a dryer to form a paint film. Note that the back roll does not necessarily have to be cylindrical, and may be configured to serve as a conveyor belt of a disc holder. Further, the position and rotation of the ink roll and the paint nozzle for supplying the paint are arbitrary.

The sandblast transfer method transfers paint using a sandblast roll whose surface has been roughened by sandblasting, and the basic device configuration is the same as the gravure method described above. However, inkneri roll is not necessary,
Film thickness is controlled by the position of the back roll, peripheral speed of the sandblasting roll, and surface roughness.

The offset method has the same equipment configuration as the gravure method except that it uses an offset roll with a flat surface, and the film thickness is controlled by the position of the back roll, the circumferential speed of the offset roll, and the distance between the offset roll and the inkneri roll.

These methods are excellent in terms of uniformity of film thickness, ease of thickness control, reproducibility, and surface roughness, and the coating speed can be set to 100 m per minute or more, making it easy to mass-produce. It is very advantageous in this respect.

Of course, the wear-resistant protective film (7) is not limited to the above-mentioned cured film; for example, it may be formed using a wear-resistant material such as AA or Ni by plating, vapor deposition, or sputtering, or may be made of polytetrafluoroethylene. It may also be a coating of a lubricious polymeric material such as, etc. or a nonwoven fiber such as silk. Polytetrafluoroethylene is widely used as a solid lubricant, and methods for forming a film include directly rubbing it on the disk surface, vapor deposition, and spin-coding after dissolving it in a solvent. Non-woven fibers have a fiber diameter of 500μ
It is preferable to use fibers with a diameter of less than m, and the type of fibers may be natural or synthetic. Furthermore, it is also possible to use an abrasive-based nonmagnetic film or a lubricant film, and it is also possible to form the film by depositing lubricant powder. In this case, as the lubricant, any known lubricant such as fatty acids and fatty acid esters can be used, and the type and composition do not matter. As the lubricating powder, powder of a substance with a small coefficient of friction such as carbon or polytetrafluoroethylene may be used, but it is preferable that the hardness of the powder is lower than that of the substrate (4). The particle size of the lubricating powder used is approximately #8 to #200,000.

Moreover, the above-mentioned wear-resistant protective film (7) does not necessarily have to be a single layer, but can also be multilayered. In this case, by selecting the type of resin and the type of additives for each layer, it becomes possible to meet various demands. Alternatively, when the wear-resistant protective film (7) is made of a metal material, the lower layer is a hard metal film (or a non-metal film such as ceramics may be used), and the upper layer is made of Au, Ag, etc.
It is also possible to use a soft metal film such as Pb to reduce impact and friction.

Furthermore, a solid filler such as lubricating powder or abrasive material is added to the above-mentioned wear-resistant protective film (7) to improve running performance.

The durability may be further improved.

The type of lubricating powder and abrasive material does not matter, but carbon (carbon black, graphite powder, etc.) is the lubricating powder.
or polytetrafluoroethylene powder (so-called Teflon powder), etc., and alumina, chromium oxide (so-called green), etc. are suitable as the abrasive material. It is also possible to add multiple types at the same time.

The above-mentioned solid filler is generally added internally to the wear-resistant protective film (7), and in this case, the particle size is preferably within twice the film thickness at most. It is also possible to mix the solid filler with a small amount of binder or apply the solid filler alone to the surface of the wear-resistant protective film (7), in which case the maximum particle size is Protective film (7)
The film thickness shall be equal to or less than that of

Furthermore, lubricants, extreme pressure agents, coupling agents, etc., which are widely used in the field of magnetic recording media, etc., are added or applied to the wear-resistant protective film (7) to prevent damage when the magnetic head comes into contact with it. It may be possible to prevent this.

All kinds of lubricants can be used as lubricants, such as higher fatty acids such as oleic acid and fatty acid esters, and extreme pressure agents include phosphorus-based extreme pressure agents, sulfur-based extreme pressure agents, halogen-based extreme pressure agents, Any conventionally known extreme pressure agent such as a metal-based extreme pressure agent or a composite extreme pressure agent can be used. As the coupling agent, various coupling agents such as a silane coupling agent, a titanium coupling agent, a zircoaluminate coupling agent, etc. can be used. By using these coupling agents, the resin constituting the wear-resistant protective film (7) and the substrate, as well as the powder components such as abrasives, are chemically bonded, increasing the strength of the film and its adhesion to the substrate. Is possible.

In addition, γ-FetOz acicular magnetic powder, Co-impregnated (doped) γ-FetOz acicular magnetic powder, CO-coated γ-Fetus acicular magnetic powder, metal magnetic powder, C
It is also possible to use magnetic powder such as rO or barium ferrite as the abrasive. Magnetic coatings containing these magnetic powders have been proven to be highly durable when used with magnetic tapes, etc., and their high magnetic permeability means that even a small magnetic field can sufficiently apply a magnetic field to the recording section (5). There is.

When these magnetic powders are dispersed in the wear-resistant protective film (7), the orientation direction of the magnetic powders is non-oriented, circumferential direction (including cases where the magnetic powder is oriented obliquely to the film surface), and radial direction. (one direction within the plane), vertical direction, etc. are arbitrary, but
Various advantages can be obtained by selecting the orientation direction.

For example, in the case of non-oriented magnetic powder, the magnetic powder is oriented in random directions even at the same position within the plane of the magneto-optical disk (1).
It is considered that the magnetic influence exerted on the recording magnetic layer (8) is the same in any part, and the influence of bit length, noise, etc. is eliminated. Even when oriented in the circumferential direction, magneto-optical disks (
1) has the same orientation in any part of the recording magnetic layer (8
), there are few factors that give local magnetic anisotropy;
There is no change in pit length, noise, etc. depending on the location.

On the other hand, in the case of perpendicular orientation, the magnetization direction of the recording magnetic layer (8) and the easy magnetization axis direction of the magnetic powder coincide, and since the magnetic permeability in this direction is high, a larger magnetic field is applied to the recording magnetic layer (8).
8), making it possible to record with a small magnetic field.

Any method used for magnetic recording media can be used as the orientation method. For example, to achieve non-orientation, a pair of orientation magnets is arranged so that the opposing directions of the magnetic poles are perpendicular to each other within the film surface of the coating film. However, an alternating current voltage may be applied to each of these orientation magnets before the coating film dries.

For circumferential orientation, both widthwise edges must be N
Using a long magnet with poles and south poles, one longitudinal end of this magnet is placed at the center of the magneto-optical disk (1), and the magnet is moved in the circumferential direction of the disk with this one end as the center. Just rotate it. When oriented in the radial direction, both edges in the radial direction are the N pole and
It is sufficient to use a long magnet with an S pole and move it in parallel in the width direction of the magnet on the magneto-optical disk (1). In the case of vertical alignment, a DC magnet may be arranged so that magnetic flux passes perpendicularly to the disk surface of the magneto-optical disk (1), and the magneto-optical disk (1) may be rotated.

In addition, in the above-mentioned abrasion-resistant protective film (7), by imparting color by selecting a pigment or the like, it is possible to ensure durability and at the same time give designability and increase the commercial value.

In the wear-resistant protective film (7) having the above configuration,
In order to perform good magnetic field modulation recording, it is necessary to set the film thickness to an appropriate value.

In other words, the thickness of the wear-resistant protective film (7) determines the distance between the magnetic head (3) and the recording section (5), or how far the magnetic head (3) is from the recording section (5). However, it is not necessary that the magnetic field be separated by a certain distance, but the minimum magnetic field necessary for recording must be within a range that reaches the recording magnetic layer (8) of the recording section (5). From the side of the magnetic head (3), the distance must be such that the recording current can be made sufficiently small to apply the same magnetic field to the recording magnetic layer (8). For example, in order to generate a magnetic field of ±200 Oe in the recording magnetic layer (8), the magnetic head (3) and the recording magnetic layer (
8) When the distance is 0.4 mm (400 μm), a recording current of approximately ±IA is required, whereas when the distance is 0.04 m (40 μm), a recording current of approximately ±0.
The recording current to 5 is sufficient.

Regarding the lower limit, it is sufficient that the film thickness is sufficient to ensure durability, and the range is such that even if this wear-resistant protective film (7) is slightly scratched, it will not damage the recording section (5). do it.

In view of these points, the thickness of the wear-resistant protective film (7) is preferably 0.01 to 50 μm. If the film thickness exceeds 50 μm, the strength of the magnetic field reaching the recording magnetic layer (8) will be small, and a large recording current will be required during recording. On the other hand, if the film thickness is less than 0.01 μm, it will be difficult to ensure sufficient durability, and there is a risk that the recording section (5) will be damaged by scratches or the like.

Incidentally, the surface roughness of the above-mentioned wear-resistant protective film (7) affects the rotation of the disk and the running of the magnetic head. For example, if a paint pattern (paint shear pattern) or the like remains on the surface of the wear-resistant protective film (7) and the surface is uneven, there is a risk that frictional force etc. will vary and uneven rotation will occur. Alternatively, the magnetic head may collide with the protrusions on the surface, causing a so-called head crash, which may disrupt normal operation.

Therefore, in this embodiment, the surface roughness of the wear-resistant protective film (7) is set to 2 μm or less at the maximum height R,1, to eliminate the above-mentioned disadvantage.

In order to set the surface roughness of the wear-resistant protective film (7) within the above range, a surface smoothing treatment may be performed after the wear-resistant protective film (7) is applied and before drying.

This surface smoothing treatment involves bringing smoothers placed at predetermined intervals (corresponding to the film thickness) into contact with the surface of the paint film to smooth out unevenness on the paint film surface and make the thickness uniform. As the smoother, a bar smoother, a sheet smoother, or the like can be used.

Preferably, the bar smoother is a metal rod, and the surface in contact with the coating film is a curved surface.

For example, it is a compound curved surface or a single curved surface with a radius of about 5 to 10,000 mm. Of course, the material of the bar smoother is not limited to the above-mentioned metals, but may also be a solvent-resistant resin, a resin coated with the same on the surface, stone, ceramics, or the like. However, the surface roughness of the smoother is determined by the Japanese Industrial Standards (J
IS) It is desirable that the finish symbol be below.

As the sheet-like smoother, elastic plain paper or the like is used, and by bringing it into contact with the surface of the coating film before drying, it is possible to smooth out irregularities on the surface of the coating film to obtain a uniform thickness. The thickness of the plain paper used is approximately 2 to 1000 μm, and the surface roughness thereof is also given the following JIS finishing symbol. Note that the material of the sheet-like smoother is not limited to the above-mentioned plain paper, and solvent-resistant resins, resins coated with the same on the surface, metal thin films, etc. can also be used.

Furthermore, after drying the coating film, a so-called calendaring process is carried out by bringing a heated roll into contact with the wear-resistant protective film (7) at a predetermined pressure.
) can also be controlled to a small value.

In this case, the heat roll is preferably a metal roll, the backup roll is preferably a metal roll or an elastic roll, and the temperature of the heat roll is preferably 30 to 500°C. Further, the processing time is arbitrary.

By applying calender treatment in this way, surface roughness can be reduced, and the backing condition of the coating film can also be improved, increasing hardness, which is extremely advantageous in terms of durability. .

Next, we actually created a magneto-optical disk, recorded data by sliding the magnetic head, and evaluated its characteristics.

The recording portion of the produced magneto-optical disk had a four-layer structure, and the film thickness was as follows.

First dielectric layer: 512N4 1000 people Recording magnetic layer: Tb-Fe-Co-Cr230 people Second dielectric layer - Si3N4 500 people Reflective layer: AI! 700 UV curable resin layer: 3. czm
A wear-resistant protective film was formed on the ultraviolet curable resin layer of the magneto-optical disk having the above structure by the following method.

Composition of paint Carbon (average particle size 200μ)...100 parts by weight Vinyl chloride-vinyl acetate copolymer...100 parts by weight Vinyl chloride-vinyl acetate-vinyl alcohol copolymer
...400 parts by weight The above composition was kneaded with a mixed solvent of methyl ethyl ketone, toluene, and cyclohexanone (1:1:I) in a ball mill for 40 hours.

Next, 20 parts by weight of a thermosetting agent (trade name Coronate) and 1.5 parts by weight of an aliphatic hydrocarbon lubricant (olive oil) were added and stirred for 20 minutes.

This was applied onto the ultraviolet curable resin layer using a transfer roll at a coating speed of 5 m/min, and after applying a metal bar smoother (surface roughness: JIS finishing symbol) to eliminate unevenness, it was dried. The thickness of the coating film after drying was 20 μm, and the surface roughness was 0.4 μm at the maximum height R.

Further, the surface of this abrasion-resistant protective film was subjected to calendering by pressing a heat roll (temperature 200° C.) with a diameter of 20 strokes under pressure. As a result, the surface roughness of the wear-resistant protective film was 0.1 μm or less at the maximum height R,6.

The magneto-optical disk obtained in the above manner was extremely excellent in durability and runnability, and did not suffer from uneven rotation.

〔Effect of the invention〕

As is clear from the above explanation, in the magneto-optical recording medium of the present invention, since a wear-resistant protective film is formed on the surface, it is possible to significantly suppress wear caused by sliding of the magnetic head. Therefore, it is possible to ensure durability. In addition, the surface of the abrasion-resistant protective film is made to have a small surface roughness by smoothing treatment, calendering treatment, etc., so it exhibits good characteristics in terms of runnability.
It is possible to eliminate head crashes, uneven rotation, etc.

On the other hand, if the magneto-optical recording medium of the present invention is used, the distance between the magnetic head and the recording magnetic layer can be stably maintained at a small value without the need for complicated servos, etc. by sliding the magnetic head against the magneto-optical recording medium. I can do something. Therefore, a magnetic field modulation magnetic head can be used even if the generated magnetic field is small, and if it has the ability to generate a large magnetic field, it is possible to reduce the applied current and save power. . Furthermore, it becomes possible to ensure the frequency characteristics of the magnetic head up to a high frequency range, and it becomes possible to achieve a high transfer rate and high density.

In addition, when viewed from the magneto-optical recording medium side, it is no longer necessary to have a recording magnetic layer with high magnetic field sensitivity, and if the recording magnetic layer is a film that can be recorded in a low magnetic field, it is necessary to have a wide margin against the magnetic field. becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining a sliding type magneto-optical recording system to which the magneto-optical recording medium of the present invention is applied. FIG. 2 is an enlarged sectional view of a main part showing an example of the configuration of a magneto-optical recording medium to which the present invention is applied. l...Magneto-optical disk 2...Optical pickup 3...Magnetic head 5...Recording section 7...Wear-resistant protective film

Claims (1)

[Claims] In a magneto-optical recording medium in which a recording magnetic layer is formed on a transparent substrate, a wear-resistant protective film is formed on a surface opposite to the transparent substrate, and the wear-resistant protective film is Maximum surface roughness height R_m_
A magneto-optical recording medium characterized in that a_x is 2 μm or less.