JPH08106664A - Magnetic head - Google Patents

Abstract

(57) [Abstract] [Purpose] A magnetic head that optically reproduces magnetic information. By concentrating a magnetic flux on a magnetic thin film made of a magneto-optical material, the rotation angle of magnetization on the surface of the magnetic thin film increases and (EN) A magnetic head capable of obtaining an output reproduction signal and significantly improving reproduction sensitivity in high density recording. A magnetic gap 5 is provided on the surface side of a magnetic recording medium 6, and a first magnetic core 1 and a second magnetic core 2 face each other with the magnetic gap 5 in between. A magnetic head in which a closed magnetic path 12 is formed by a magnetic thin film 3 made of a magneto-optical material that connects the second magnetic core 2 and a conductive member 4 as a magnetic flux concentrating member along the magnetic thin film 3. Is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head for optically reproducing information magnetically recorded on a magnetic recording medium.

[0002]

2. Description of the Related Art Recently, in the fields of information communication and audiovisual,
High-density (small size / large capacity) information recording / reproducing devices are being actively developed.

Among them, the progress of magnetic recording is remarkable,
The recording density has been increased, the size has been reduced, and the transfer speed has been increased, and the recording density has been improved about 10 times in 10 years.

In the high density recording of the longitudinal magnetization system which is currently widely applied to magnetic disk devices, in order to shorten the shortest bit interval and improve the linear recording density, the recording level should be as low as possible. It is possible to keep the arc-shaped magnetization mode as high as possible by either shallowly magnetizing only the surface layer or thinning the magnetic layer thickness of the medium to less than half (1/4 wavelength) of the shortest bit interval. is necessary.

In order to reduce the track pitch and improve the track recording density, the head is positioned on an arbitrary track at high speed and with high precision, and the 1-bit recording area is reduced according to the bit length. Therefore, it is necessary for the head to detect a small high-frequency magnetic field from the medium with high sensitivity.

That is, as the problems of high density recording / reproducing of magnetic recording by the longitudinal magnetization method, high sensitivity of the reproducing head, high speed and high accuracy of positioning of the recording / reproducing head, high coercive force of the magnetic recording medium and high output of the recording head. There is a change.

However, the increase in the holding power of the medium is not only limited by the writing ability of the recording head, but also the reproduction voltage is rapidly attenuated as the density is increased due to various losses during reading, and the practical recording density is the theoretical value. The current situation is much lower than

That is, in order to increase the density of magnetic recording, it is essential to improve the writing ability of the recording head and the reproduction sensitivity of the reproducing head.

Therefore, as a longitudinal magnetization (in-plane magnetization) method of reproducing a magnetization signal, a method has been proposed in which a medium magnetization signal is transferred to a ferromagnetic thin film and the magneto-optical effect of the ferromagnetic thin film is applied. (For example, JP-B-56-33781, JP-A-61-214258, and JP-B-3-5.
5894).

An example of a conventional magnetic head will be described below with reference to the drawings.

FIG. 5 is a sectional view showing the principle of a conventional magnetic head. In FIG. 5, 1 is a first magnetic core, 2 is a second magnetic core, 5 is a magnetic gap (usually made of glass), 6 is a magnetic recording medium, and 16 is a magnetic body made of a magneto-optical material. The first magnetic core 1 and the second magnetic core 2 face each other via the magnetic gap 5, and the magnetic recording medium 6
The magnetic flux generated from the magnetization 13 due to the information signal recording recorded in (1) forms the closed magnetic path 12 by the first magnetic core 1, the second magnetic core 2 and the magnetic body 16 made of a magneto-optical material.

The operation of the magnetic head having the above structure will be described below with reference to FIG.

Depending on the magnitude and direction of the magnetization 13 due to the information signal recording of the magnetic recording medium 6, the magnetization of the magnetic body 16 made of a magneto-optical material provided in the magnetic head changes.
When the polarized light is incident on the magnetic body 16, the plane of polarization is rotated depending on the magnitude and direction of the magnetization, and the photodetector detects the polarization angle of the reflected light as an electric signal.

[0014]

However, the above-mentioned structure has a problem that the reproduction signal is lowered when reproducing a medium recorded at high density. That is, the 1-bit recording area becomes small, and the size of the magnetization 13 due to the information signal recording on the magnetic recording medium 6 becomes small. Further, since the magnetic body 16 made of the magneto-optical material provided in the magnetic head increases the magnetic resistance of the magnetic head, the leakage magnetic flux of the magnetic core increases, and the effective magnetic flux in the magnetic body 16 made of the magneto-optical material decreases. To do. As a result, the amount of change in the magnitude and direction of the magnetization in the magnetic body 16 is reduced, and the output is reduced. Further, if the thickness of the magnetic body 16 made of a magneto-optical material is increased in order to reduce the magnetic resistance of the magnetic head, the magnetic flux density of the magnetic body is reduced and the amount of change in the magnitude and direction of the magnetization is reduced, so that the output is reduced. Had the problem of doing.

In view of the above circumstances, it is an object of the present invention to provide a magnetic head capable of remarkably improving the reproducing sensitivity in high density recording as compared with the conventional method.

[0016]

A first magnetic head according to the present invention has a magnetic gap on the surface side of a magnetic recording medium, and the first magnetic core and the second magnetic core are connected via the magnetic gap. A magnetic head that faces each other and has a closed magnetic path formed by the first magnetic core, the second magnetic core, and a magnetic thin film made of a magneto-optical material that connects both magnetic cores. The magnetic flux concentrating member is arranged along the thin film.

The second magnetic head according to the present invention is
A magnetic gap is provided on the surface side of the magnetic recording medium, and the first magnetic core and the second magnetic core face each other through the magnetic gap, and the first magnetic core and the second magnetic core A magnetic head in which a closed magnetic path is formed by a magnetic thin film made of a magneto-optical material that connects both magnetic cores, wherein the surface of the first magnetic core faces the second magnetic core, or the second magnetic core. The magnetic shielding member is disposed on at least one of the surfaces of the magnetic core facing the first magnetic core.

[0018]

In the first magnetic head according to the present invention, the presence of the magnetic flux concentrating member along the magnetic thin film concentrates the magnetic flux on the magnetic thin film made of the magneto-optical material, thereby increasing the rotation angle of the magnetization on the surface of the magnetic thin film. A reproduction signal of high output is obtained, and reproduction sensitivity in high density recording is improved.

Further, in the second magnetic head according to the present invention, the presence of the magnetic shielding member arranged on the surfaces of the magnetic cores facing each other reduces the leakage magnetic flux in the vicinity of the magnetic gap and reduces the magnetization of the magnetic thin film. The rotation angle becomes large and the reproduction output becomes large.

[0020]

Embodiments of the magnetic head of the present invention will be described with reference to the drawings.

(First Embodiment) A magnetic head according to the first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the magnetic head of the first embodiment. FIG. 2 is a sectional view taken along the section line CD of FIG. 1 and 2, 1 is the first magnetic core,
Reference numeral 2 is a second magnetic core, 3 is a magnetic thin film made of a magneto-optical material (for example, a permalloy film vapor-deposited with an electron beam having a thickness of 20 nm), 4 is a conductive member (for example, copper) that generates an eddy current as a magnetic flux concentration member, 5 is a magnetic gap usually made of glass; 6 is a magnetic recording medium; 7 is a light source; 8 is incident light;
Is a half mirror, 10 is reflected light, and 11 is a light receiving element. The first magnetic core 1 and the second magnetic core 2 face each other via a magnetic gap 5 arranged on the magnetic recording medium 6 side, and from the magnetization 13 recorded on the magnetic recording medium 6 by the information signal recording. The generated magnetic flux forms a closed magnetic circuit 12 by the first magnetic core 1, the second magnetic core 2 and the magnetic thin film 3 made of a magneto-optical material, and along the lower surface of the magnetic thin film 3 serves as a magnetic flux concentrating member. A conductive member 4 is provided.

The operation of the magnetic head configured as described above will be described below with reference to FIGS. 1 and 2.

Since the direction of the closed magnetic path 12 inside the magnetic head is repeatedly reversed at high speed as the magnetic recording medium 6 moves at high speed, an eddy current is generated inside the conductive member 4 as a magnetic flux concentrating member, which causes a reaction. A magnetic field is generated. As a result, the magnetic flux in the magnetic thin film 3 is reduced, and the magnetic flux inside the magnetic thin film 3 is concentrated on the upper side (the side on which light is incident), the magnetic field strength is increased, and the rotation angle of the magnetization of the surface of the magnetic thin film 3 is increased. Grows.

Closed magnetic path 12 and magnetization 14 in the magnetic thin film 3.
2 will be described with reference to FIG. 3, which is a view taken in the direction of arrow E in FIG. As shown in FIG. 3, the magnetization 14 rotates depending on the direction of the magnetic path 12 in the magnetic thin film 3. When the magnetic path is in the direction of 12F, the magnetization rotates like 14F, and when the magnetic path is in the direction of 12G, the magnetization rotates like 14G. As the magnetic field strength of the magnetic thin film 3 increases, the angle of rotation increases. The playback output is increased.

Even if the magnetic thin film 3 becomes thick,
Due to the reaction magnetic field generated in the conductive member 4 as the magnetic flux concentrating member, the magnetic flux density in the upper part (on the side where light is incident) of the magnetic thin film 3 does not decrease, the rotation angle of magnetization does not decrease, and the output does not decrease. . In this way, the magnetization 14 of the magnetic thin film 3 is rotated by the change in the size and direction of the magnetic path 12 inside the magnetic head. The deflected incident light 8 generated from the light source 7 is
The direction of polarized light is rotated by the magnetic thin film 3 by the magneto-optical effect. The reflected light 10 is reflected by the half mirror 9, converted into an electric signal by the light receiving element 11, and a reproduction output is obtained.

In this embodiment, the magnetic thin film has a thickness of 20 nm.
However, other magnetic thin films having a magneto-optical effect and other film thicknesses have the same effect.

Further, in the present embodiment, copper is arranged as the conductive member as the magnetic flux concentrating member for concentrating the magnetic flux in the magnetic thin film made of the magneto-optical material, but another conductive member having high conductivity is used. However, a superconducting member having a Meissner effect also has the same effect.

(Second Embodiment) A magnetic head according to a second embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a sectional view showing the magnetic head of the second embodiment. In FIG. 4, reference numeral 15 denotes a conductive member, such as copper, that generates an eddy current as a magnetic shield member. The conductive member 15 faces the second magnetic core 2 of the first magnetic core 1 and the second magnetic core 2. Is different from the first embodiment in that a conductive member 15 for generating an eddy current is arranged on the surface facing the first magnetic core 1, and other points are the same as the above-described first embodiment. Therefore, the same reference numerals are given and the description will be omitted.

The operation of the magnetic head having the above structure will be described below with reference to FIG.

In the first embodiment, the magnetic thin film 3 made of a magneto-optical material has an extremely thin thickness of 20 nm, so that the magnetic resistance becomes large, the leakage magnetic flux becomes large in the vicinity of the magnetic gap 5, and the magnetic thin film 3 is formed. It has a tendency that the effective magnetic flux of is decreased and the rotation angle of the magnetization is decreased.

On the other hand, in this embodiment, the surface of the first magnetic core 1 facing the second magnetic core 2 and the surface of the second magnetic core 2 facing the first magnetic core 1 are magnetized. By providing the conductive member 15 as the shield member, the leakage magnetic flux in the vicinity of the magnetic gap 5 is reduced by the reaction magnetic field due to the eddy current, so that the rotation angle of the magnetization in the magnetic thin film 3 increases.
The reproduction output becomes large.

In this embodiment, the magnetic thin film is 20 nm thick.
However, other magnetic thin films having a magneto-optical effect and other film thicknesses have the same effect.

In this embodiment, the second magnetic core of the first magnetic core is used.
Copper is arranged as a conductive member as a magnetic shielding member on the surface of the second magnetic core facing the first magnetic core and the surface of the second magnetic core facing the first magnetic core. The same effect can be obtained by either the conductive member or the superconducting member having the Meissner effect.

In this embodiment, the second magnetic core of the first magnetic core is also used.
Of the second magnetic core and the surface of the second magnetic core facing the first magnetic core are each provided with a conductive member in which an eddy current is generated in order to prevent a leakage magnetic flux, but only one surface is made conductive. Even if the members are arranged, the same effect can be obtained.

Further, in this embodiment, the magnetic head having a magnetic flux concentrating member for concentrating the magnetic flux in the magnetic thin film made of the magneto-optical material is provided with a surface facing the second magnetic core of the first magnetic core. Although the magnetic shield member is arranged on the surface of the second magnetic core facing the first magnetic core in order to prevent the leakage magnetic flux, a magnetic head having no magnetic flux concentrating member has the same effect.

[0038]

According to the first magnetic head of the present invention, since the magnetic flux is concentrated on the magnetic thin film made of the magneto-optical material due to the presence of the magnetic flux concentration member along the magnetic thin film, the rotation of the magnetization of the surface of the magnetic thin film is rotated. As the angle becomes larger, a high output reproduction signal can be obtained, and the reproduction sensitivity in high density recording can be remarkably improved.

Further, according to the second magnetic head of the present invention, since the magnetic flux leakage near the magnetic gap is reduced by the presence of the magnetic shielding member arranged on the surfaces of the magnetic cores facing each other, the magnetic thin film The rotation angle of the magnetization is increased to obtain a high output reproduction signal, and the reproduction sensitivity in high density recording can be significantly improved.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a magnetic head according to a first embodiment of the invention.

FIG. 2 is a sectional view illustrating a magnetic head according to the first embodiment of the invention.

FIG. 3 is a view for explaining the direction of magnetization on the surface of the magnetic thin film having the magneto-optical effect of the present invention.

FIG. 4 is a sectional view illustrating a magnetic head according to a second embodiment of the present invention.

FIG. 5 is a sectional view illustrating a conventional magnetic head.

[Explanation of symbols]

 1 ... First magnetic core 2 ... Second magnetic core 3 ... Magnetic thin film made of magneto-optical material 4 ... Conductive member (magnetic flux concentrating member) 5 ... Magnetic gap 6 ... Magnetic recording medium 7 ... ... Light source 8 ... Incident light 9 ... Half mirror 10 ... Reflected light 11 ... Light receiving element 12 ... Closed magnetic path 13 ... Magnetization 14 ... Magnetization 15 ... Conductive member (magnetic shielding member) 16 ... Magnetic Magnetic material made of optical material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Sozo 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Makoto Kuwamoto 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A magnetic recording medium has a magnetic gap on the surface side, and a first magnetic core and a second magnetic core face each other via the magnetic gap, and the first magnetic core and the second magnetic core face each other. A magnetic head in which a closed magnetic path is formed by a magnetic core and a magnetic thin film made of a magneto-optical material connecting both magnetic cores, wherein a magnetic flux concentrating member is arranged along the magnetic thin film. Characteristic magnetic head. 2. The magnetic head according to claim 1, wherein the magnetic flux concentration member is made of a conductive material. 3. The magnetic head according to claim 1, wherein the magnetic flux concentrating member is made of a superconducting material. 4. A magnetic gap is provided on the side of the magnetic recording medium, and the first magnetic core and the second magnetic core face each other through the magnetic gap, and the first magnetic core and the second magnetic core face each other. A magnetic head in which a closed magnetic circuit is formed by a magnetic core and a magnetic thin film made of a magneto-optical material connecting both magnetic cores, the surface of the first magnetic core facing the second magnetic core. Alternatively, a magnetic shielding member is provided on at least one of the surfaces of the second magnetic core facing the first magnetic core. 5. The magnetic head according to claim 4, wherein the magnetic shield member is made of a conductive material. 6. The magnetic head according to claim 4, wherein the magnetic shield member is made of a superconducting material.