JPH05242555A - Magnetic head for magneto-optical disk and magneto-optical disk - Google Patents

Abstract

(57) [Summary] [Structure] In the sliding recording method, the resistance of the slider surface of the magnetic head for the magneto-optical disk and the surface of the protective film of the magneto-optical disk is kept as low as less than 10 ¹³ Ω / □. [Effect] The coefficient of dynamic friction between the slider and the protective film is reduced, and further, the adhesion of dust on the protective film and the slider is prevented,
The slidability between the magneto-optical disk and the magnetic head becomes good.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical disk suitable for a sliding recording system and a magnetic head for the magneto-optical disk.

[0002]

2. Description of the Related Art In a magneto-optical recording system, a magnetic thin film is partially heated above a Curie point or a temperature compensation point to eliminate the coercive force of this portion and magnetize in the direction of a recording magnetic field applied from the outside. The basic principle is to reverse the direction of the above, and it is being put to practical use in an optical file system, an external storage device of a computer, a recording device of audio and video information, and the like.

As a magneto-optical disk used in this magneto-optical recording system, a recording magnetic layer having a large magneto-optical effect, which has an easy axis of magnetization in the direction perpendicular to the film surface, on one main surface of a transparent substrate made of polycarbonate or the like. A recording portion is formed by stacking layers (for example, a rare earth-transition metal alloy amorphous thin film), a reflection layer, and a dielectric layer, and is further formed on the recording portion so as to cover a protective film made of an ultraviolet curable resin or the like. Things are known.

By the way, the magneto-optical recording method is roughly classified into an optical modulation method and a magnetic field modulation method. Among them, the magnetic field modulation method is noted because it can be overwritten, and is, for example, a general-purpose type. Adoption is being considered as a recording method for a small magneto-optical disk (so-called mini disk) having a diameter of about 64 mm.

The above-mentioned magnetic field modulation method writes information in a magnetic thin film by reversing the applied magnetic field at high speed, and the magnetic field is normally applied by a magnetic head having magnetic field generating means. In this case, a magnetic head applying a high-speed reversal magnetic field can generate only a very small magnetic field due to various restrictions, and the magnetic head must be as close to the recording magnetic layer as possible.

Therefore, in such a magnetic field modulation method, adoption of a sliding recording method in which a magnetic head is brought into direct contact with the disk surface of a magnetic disk and recording is performed while sliding is being considered. If this sliding recording method is adopted, a sufficient magnetic force can be applied to the recording magnetic layer and a large magnetic field can be generated even when the magnetic field generated like the magnetic head that applies the high-speed reversal magnetic field is small. If so, the applied power can be reduced to save power. In addition, the method in which the head floats above the disk surface requires a complicated servo mechanism to keep the distance between the disk surface and the head constant, but the sliding recording method does not require such a servo mechanism. Is. Therefore,
It is also advantageous in simplifying and downsizing the device.

[0007]

By the way, a magnetic head used in the sliding recording system is provided with a slider for smooth sliding at a portion which directly contacts the disk surface. The slider is usually made of sheet-shaped plastic, and is attached so as to cover, for example, the magnetic field generating portion of the magnetic head. The magnetic head to which the slider is attached in this manner is arranged on the protective film side of the magneto-optical disk, and the magnetic field is applied to the magneto-optical disk while the slider is in sliding contact with the protective film surface. ..

However, when such a slider made of plastic is brought into sliding contact with the protective film surface, the slider and the protective film surface are partially charged. As a result, the frictional force between the two becomes large, and further, dust adheres to the surface of the slider and the protective film, which causes troubles in sliding. Therefore, the present invention has been proposed in view of such a conventional situation, and when the magnetic head is slid on the magneto-optical disk, the slider and the protective film are not charged and good sliding is achieved. It is an object of the present invention to provide a magnetic head for a magneto-optical disk and a magneto-optical disk, which can obtain excellent properties.

[0009]

In order to achieve the above object, a magnetic head for a magneto-optical disk according to the present invention comprises a magnetic head for a magneto-optical disk having a magnetic field generating means and a slider sliding on the magneto-optical disk. In the head, the resistance of the surface of the slider is less than 10 ¹³ Ω / □.

Further, the magneto-optical disk of the present invention is a magneto-optical disk in which a recording magnetic layer and a protective film are sequentially formed on a transparent substrate, and the resistance of the surface of the protective film is 10 ¹³ Ω.
It is characterized by being less than / □.

[0011]

When the resistance of the surface of the slider of the magnetic head and the surface of the protective film of the magneto-optical disk is kept as low as less than 10 ¹³ Ω / □, the protective film and the sliding caused by the sliding contact between the protective film and the slider. The charging of the child is prevented. Therefore, the increase in the frictional force between the protective film and the slider, which is induced by the electrification of the slider, and the adhesion of dust and the like to the protective film and the slider are suppressed. When I went to
Scratches and the like will not occur on the slider and protective film.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described with reference to the drawings.

First, FIG. 1 is a schematic block diagram of a magneto-optical recording apparatus for recording an information signal on the magneto-optical disk of this embodiment. Optical pickup 2 and magnetic head 3
Are opposed to each other, and signal recording is performed while the magnetic head 3 slides on the magneto-optical disk 1.

The magnetic head 3 is, as shown in FIG.
An external magnetic field is generated by having a magnetic field generating means 34 and a slider 32 that is in sliding contact with the magneto-optical disk 1 and supplying a drive current controlled by a magnetic head drive circuit to the magnetic field generating means 34. To do. The slider 32 is provided for smooth sliding of the magnetic head 3 with respect to the magneto-optical disk 1, and is made of sheet-shaped plastic.
It is attached so as to cover the lower end of the magnetic field generating means 34.

In the present invention, in order to make the sliding contact between the slider 32 and the magneto-optical disk 1 smoother, the surface resistance of the slider 32 is suppressed to less than 10 ¹³ Ω / □. By suppressing the surface resistance of the slider 32 to less than 10 ¹³ Ω / □, the charging generated when the slider 32 and the magneto-optical disk 1 are in sliding contact with each other is prevented, and between the sliding element and the magneto-optical disk caused by the charging. The increase in the frictional force and the adhesion of dust to the slider and the magneto-optical disk are suppressed, and the sliding contact becomes smooth.

The plastic sheet used as the slider 32 is
For example, by including conductive carbon or the like, the surface resistance can be suppressed to less than 10 ¹³ Ω / □. Also,
Further, when the plastic sheet is bent into a so-called corrugated plate having concave and convex portions, the coefficient of friction between the magneto-optical disk and the slider is reduced, which is advantageous in obtaining good sliding characteristics. .. When the plastic sheet has a corrugated plate shape, it is preferable that the plastic sheet has a corrugated shape in which the width of the ridge portion is larger than that of the concave portion on the side in contact with the magneto-optical disk. Further, the height of the irregularities (corresponding to the amplitude of the wave) is preferably 10 μm or less.

The magnetic head 3 is attached to a magnetic head support 38 attached to a support arm 40 via a pressure spring 39, for example. The support arm 40
Can be moved around the shaft 41 to the inner and outer circumferences of the magneto-optical disk. Therefore, the magnetic head 3
Means that a magnetic field is applied to the entire surface of the signal recording area while being pressed against the magneto-optical disk 1 by the pressing spring 39 at a predetermined pressure.

On the other hand, the magneto-optical disk 1 slid by such a magnetic head has a substrate 4 as shown in FIG.
The recording portion 5 is laminated on one main surface of the recording head 5, and the surface of the recording portion 5 is covered with a protective film 6. The protective film 8 is brought into sliding contact with the slider 32 of the magnetic head 3. ..

The substrate 4 is a disk-shaped transparent substrate having a thickness of about several millimeters, and as its material, a plastic material such as an acrylic resin, a polycarbonate resin, a polyolefin resin, an epoxy resin, or the like, or a glass or the like is used. To be done. Incidentally, of the surface of the substrate 4 on the side where the recording section 5 is provided, a guide groove, an address code pit, or the like having a depth of about ¼ of the wavelength of the laser beam used during normal reproduction (whichever Is also omitted).

The recording section 5 includes a recording magnetic layer 7, a dielectric layer 8,
9 and a reflective layer 10 have a four-layer structure, and a first dielectric layer 8, a recording magnetic layer 7, a second dielectric layer 9,
The reflective layers 10 are stacked in this order.

Of these, the first dielectric layer 8 and the second dielectric layer 8
The dielectric layer 9 may be made of an oxide, a nitride, or the like, but a nitride is more preferable because oxygen in the dielectric may adversely affect the recording magnetic layer. Silicon nitride, aluminum nitride, or the like is suitable as the substance that does not transmit and can sufficiently transmit the used laser beam.

The recording magnetic layer 7 is an amorphous magnetic thin film having an easy magnetization direction in a direction perpendicular to the film surface, and it has excellent magneto-optical characteristics and a large coercive force at room temperature. It is desirable to have a Curie point around 200 ° C. As a recording material satisfying such conditions, a rare earth-transition metal alloy amorphous thin film and the like can be mentioned, and among them, a TbFeCo based amorphous thin film is preferable. An additive element such as Cr may be added to the recording magnetic layer 7 for the purpose of improving the corrosion resistance.

The reflective layer 10 is preferably formed of a film having a high reflectance that reflects 70% or more of the laser light at the boundary with the second dielectric layer 9, and is preferably a non-magnetic metal vapor deposition film. .. Further, it is desirable that the reflective layer 10 is a good thermal conductor, and aluminum is suitable in consideration of availability and film formation.

Each of these layers 7, 8, 9 and 10 is formed by a so-called vapor phase plating technique such as vapor deposition or sputtering. At this time, the film thickness of each layer can be set arbitrarily, but is usually set to several hundreds to several thousands Å. These film thicknesses are preferably determined not only by considering the optical properties of each layer alone, but also by considering the effect of combination. this is,
For example, when the film thickness of the recording magnetic layer 7 is smaller than the wavelength of the laser light, the laser light causes multiple interference with the light transmitted through the recording magnetic layer 7 and reflected at each layer boundary, and the recording magnetic layer is combined by the combination of the film thicknesses. This is because the effective optical and magneto-optical characteristics of No. 7 largely fluctuate.

Further, the protective film 6 made of an ultraviolet curable resin or the like is formed on the recording portion 5. The protective film 6 is provided for the purpose of isolating the recording portion from water and oxygen in the atmosphere, and in the present embodiment, particularly for the purpose of protecting the recording portion 5 from the sliding magnetic head.

Here, in the present invention, the slider 3 is used.
The surface of the protective film 6 which is slidably contacted with 2 also has a resistance as low as less than 10 ¹³ Ω / □ as in the case of the slider 32. By suppressing the surface resistance of the protective film 6 to less than 10 ¹³ Ω / □, the slider 32 and the protective film 6 are more reliably prevented from being charged, and the magnetic head 3 slides more smoothly.

In order to suppress the surface resistance of the UV curable resin which becomes the protective film 6 to less than 10 ¹³ Ω / □, for example, conductive fine particles of antimony oxide, indium oxide, tin oxide or the like are added to the UV curable resin. Good. At this time, it is appropriate that the conductive fine particles have a particle size of several tens of liters. A lubricant such as diglycerin tetralaurylate may be added to the ultraviolet curable resin in order to improve sliding performance.

Next, the following experiment was conducted in order to investigate the effect of actually setting the surface resistance of the slider 32 and the protective film 6 to less than 10 ¹³ Ω / □.

First, a first silicon nitride dielectric film, a TbFeCo recording magnetic layer, a second silicon nitride dielectric film, and an aluminum reflecting layer are formed on a polycarbonate substrate to form a recording portion, and this recording portion is further formed. A magneto-optical disk (disk 1, disk 2, comparative disk 1) was manufactured by forming various protective films on the top.

In the protective film of each magneto-optical disk, the disk 1 was prepared by dispersing 30% by volume of antimony oxide fine particles having a particle size of 10Å and 2% of diglycerin tetralaurate (DGTL) as a lubricant in an ultraviolet curable resin. What
The disk 2 contains 30% by volume of indium oxide fine particles and tin oxide fine particles having a particle size of 10Å and DG in the ultraviolet curable resin.
TL containing 2% of TL dispersed therein, Comparative Disc 1 is a DGTL containing ultraviolet curable resin containing no conductive fine particles.
Only 2% dispersedly contained. Table 1 shows the surface resistance of each of the above protective films.

[0031]

[Table 1]

A magnetic head having various sliders (head 1,
The head 2, the comparative head 1, and the comparative head 2) were slid. In the plastic sheet used as the slider in each magnetic head, the head 1 is made of conductive carbon.
6,6-nylon sheet containing 0%, head 2 is formed by corrugating 6,6-nylon sheet containing 30% conductive carbon, and comparative head 1 is 6,6-nylon containing no conductive carbon Seat and comparison head 2
Is a corrugated 6,6-nylon sheet containing no conductive carbon. Table 2 shows the surface resistance of the slider.

[0033]

[Table 2]

Coefficient of dynamic friction between the protective film and the slider when a magnetic head having various sliders is slid on each of the above magneto-optical disks, the state of dust adhesion, and after 2 million passes. Table 3 shows the abrasion depth of the protective film.

[0035]

[Table 3]

As can be seen from Table 3, when the surface resistance of at least one of the protective film and the slider is less than 10 ¹³ Ω / □, the coefficient of dynamic friction between the protective film and the slider is reduced, and Adhesion is also prevented, and scratches and the like hardly occur on the protective film even after 2 million passes. Also,
If both the surface resistance of the protective film and the surface resistance of the slider are less than 10 ¹³ Ω / □, the coefficient of dynamic friction is further reduced and the adhesion of dust is reduced.

Therefore, from the above, it is effective to suppress the surface resistance of the slider and the protective film to less than 10 ¹³ Ω / □ in order to improve the slidability between the magnetic head and the magneto-optical disk. I understood.

[0038]

As is apparent from the above description, in the present invention, the surface resistance of the protective film of the magneto-optical disk and the slider of the magnetic head is suppressed to a low value of less than 10 ¹³ Ω / □, and therefore the protective film. -The coefficient of dynamic friction between the sliders is reduced, dust is prevented from adhering to the protective film and the slider, and the slidability between the magneto-optical disk and the magnetic head is improved.

Therefore, according to the present invention, the reliability and practicality of the sliding recording system can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a sliding type magneto-optical recording method.

FIG. 2 is a schematic diagram showing a configuration example of a magnetic head for a magneto-optical disk to which the present invention is applied.

FIG. 3 is an enlarged sectional view of an essential part showing a configuration example of a magneto-optical disk to which the present invention is applied.

[Explanation of symbols]

 1 ... Magneto-optical disk 2 ... Optical pickup device 3 ... Magnetic head 4 ... Substrate 5 ... Recording part 6 ... Protective film 31 ... Magnetic field generating means 32 ... Sliding Child

Claims (2)

[Claims] 1. A magnetic head for a magneto-optical disk having a magnetic field generating means and a slider that slides on the magneto-optical disk, wherein the resistance of the surface of the slider is less than 10 ¹³ Ω / □. Magnetic head for magneto-optical disk. 2. A magneto-optical disk having a recording magnetic layer and a protective film sequentially formed on a transparent substrate, wherein the surface of the protective film has a resistance of less than 10 ¹³ Ω / □. ..