JPH06180818A - Magnetic head - Google Patents

Abstract

PURPOSE:To improve the magnetic flux efficiency of the magnetic head and to enhance its efficiency and resolving power. CONSTITUTION:Magnetomotive force is generated in a yoke 1 at the time of recording and a coil 5 for detecting a change in a magnetic flux at the time of reproduction is provided. Further, a gap 2 part for generating the leakage magnetic field of the yoke 1 is provided with a conductive layer 15. Eddy current is generated by the induced current which is generated by the presence of this conductive layer 15 and the leak magnetic flux is increased by a diamagnetic field.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing head of a magnetic recording apparatus, a magnetic head of a magnetic field modulation type overwrite magneto-optical disk drive apparatus, or the like.

[0002]

2. Description of the Related Art In magnetic recording, a magnetic field generated by a magnetic head is applied to a magnetic body having magnetic hysteresis (history).
Recording is performed by arranging the magnetic domains according to the information, the magnetic field generated by the magnetic material is detected during reproduction, and the information is restored from the array.

For example, in VTRs and recorders, γ-Fe203 (gamma hematite) is used as a medium and a ring head formed by winding a ferrite yoke having a gap is used as a head. At the time of recording, a current is passed through the winding while the gap is brought close to the information recording medium (medium) and relative movement is performed. In this way, a magnetomotive force is generated,
Magnetic flux is generated in the yoke. Although the magnetic flux flows along the yoke, since there is a gap in the middle of the magnetic circuit, the magnetic flux spreads at that portion and becomes a leakage magnetic flux. This leakage magnetic flux is given to the medium and magnetizes the magnetic domain in the direction of the magnetic field. Therefore,
It is this leakage magnetic flux that is effectively used for magnetic recording.

Next, the mode of magnetization of the medium will be described. There are two modes, longitudinal mode and vertical mode. The longitudinal mode is the mode that magnetizes the media in the direction of relative motion, and the vertical mode is that it is vertical. Although these two modes have advantages and disadvantages, they are currently almost longitudinal recording modes. The ring head can generate a recording (leakage) magnetic field suitable for this longitudinal recording. Since the longitudinal recording is targeted here, the ring head will be described.

The conditions for the head capable of high density recording in this mode are as follows.

(1) A strong magnetic field can be generated (sufficient magnetization is given to the medium).

(2) A narrow magnetic field can be generated (only a narrow portion of the medium can be magnetized).

(3) A magnetic field can be generated up to a high frequency
(The recording magnetic field can generate up to high frequency).

The head satisfying the above conditions is a head capable of high density recording. Development has progressed in this direction, but it has been made possible by improving the magnetic properties of the yoke. Specifically, the characteristics are as follows.

(1) High saturation magnetic flux density.

(2) High magnetic permeability and constant up to high frequencies.

As a material satisfying the above two characteristics, M
Examples thereof include n-Zn ferrite and Ni-Zn ferrite.
Ferrite has been widely used because of its high hardness and high wear resistance. However, when magnetizing a medium having a higher recording energy or when generating a steeper magnetic field, a material having a higher saturation magnetic flux density has been required. A material that satisfies the requirement is a magnetic material such as a metal such as permalloy, which has a smaller specific resistance than ferrite, so that there is a problem that eddy currents are generated at high frequencies and the magnetic permeability decreases, and high-speed recording is performed. Was impossible. Therefore, the invention was invented in JP-A-51-140708 and JP-A-
It is a head called MIG (Metal In Gap) shown in Japanese Patent Publication No. 55-77024. This MIG head has excellent high frequency characteristics of ferrite and high saturation magnetic flux density of a metal magnetic material, and is manufactured by a conventional method. Not so difficult compared to the head.

FIG. 4 is an explanatory view showing the structure of a conventional MIG head, wherein 1 is a yoke which is a soft magnetic member, 2 is a gap which is a void portion formed under the yoke 1, and 3 is a space of the yoke 1. A metal layer formed on the inner wall of the portion, 4 is a glass body provided in the gap 2, and 5 is a winding provided in a part of the yoke 1, that is, a part of a magnetic path A circulated by the yoke 1. It is a coil. Incidentally, 10 in the figure is a magnetic recording body on which a magnetic film is formed.

FIG. 4 shows a state at the time of recording, in which a write current controlled based on the record information data flows in the coil 5 to generate a magnetomotive force. As a result, magnetic flux is generated in the yoke 1. This magnetic flux flows along the yoke 1, but a gap 2 exists in the middle of the magnetic path A thereof. Here, the magnetic flux expands spatially due to a rapid change in magnetic permeability. This is the driving force for the formation of magnetization in the magnetic recording body 10 by so-called leakage magnetic flux. The horizontal component, which is the moving direction, of this magnetic flux becomes an effective component that magnetizes the magnetic recording medium 10 in the direction shown in the figure, and forms residual magnetization corresponding to the recorded information.

Here, the metal layer 3 reinforces the magnetic characteristics of the ferrite generally used as the yoke 1, and has a function of generating a steep magnetic flux near the gap 2 due to its high saturation magnetic flux density. Therefore, the MIG head
It exhibits excellent high-frequency characteristics due to the high specific electric resistance of ferrite, and excellent characteristics that combine the high saturation magnetic flux density and magnetic permeability of metallic magnetic materials.

FIG. 5 shows a state at the time of reproduction, and the magnetic recording medium 10
A minute voltage is induced in the yoke 1 based on the change in magnetic flux due to the residual magnetization, and the data read voltage is obtained by detecting this voltage change in the coil 5.

[0017]

However, in the above-mentioned conventional MIG head, since the magnetic resistance of the magnetic circuit is reduced by the metal layer 3, the leakage magnetic flux is reduced. As a result, the magnetic flux efficiency may decrease and the sensitivity may decrease. In that case, although it is better to reduce the depth of the gap 2, there arises a problem that the sensitivity is significantly reduced against wear and the sensitivity is greatly varied during manufacturing.

It is an object of the present invention to provide a magnetic head capable of improving magnetic flux efficiency and achieving high efficiency and high resolution.

[0019]

In order to achieve the above object, the present invention forms a magnetic path that circulates by a soft magnetic member, provides a winding on a part of this magnetic path, and generates a leakage magnetic field. Is provided, and a conductive layer is provided in this void.

A soft magnetic layer having a high magnetic permeability and a high saturation magnetic flux density is provided between the soft magnetic member and the conductive layer.

Further, the width of the soft magnetic layer in the direction orthogonal to the relative movement direction with respect to the magnetic recording body is smaller than the width of the magnetic path.

[0022]

According to the above means, the eddy current is generated by the dielectric current in the conductive layer provided in the gap (gap). The demagnetizing field increases the leakage magnetic flux rather than the loss due to the eddy current, and the effective recording magnetic field increases. Therefore, a steep magnetic field is formed and a high recording density is achieved.

Further, by providing a soft magnetic layer which is a high magnetic permeability layer in which magnetic flux is concentrated, a stronger magnetic field can be given to the magnetic recording medium.

Further, by making the width of the soft magnetic layer smaller than the width of the magnetic path, the magnetic flux is strongly concentrated in a narrow area, and the track density can be increased.

[0025]

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

FIG. 1 is an explanatory view showing the structure of the first embodiment of the present invention. The members corresponding to the members of the conventional example described with reference to FIGS. Is omitted.

In this embodiment, the process in which the magnetic flux is generated and propagated along the yoke 1 is the same as that in the conventional example. Here, the difference from the conventional example is that another conductive layer of the magnetic layer is provided inside the gap 2.
This is the point where 15 is provided. Reference numeral 16 is a write current source.

As shown in the diagram of FIG. 2, when the magnetic flux 20 penetrates the conductive layer 15, an induced current generally called an eddy current 21 flows. On the contrary, this eddy current 21 generates a magnetic flux 20, and the direction thereof is a direction that prevents the change of the magnetic flux 20 applied from the outside.

Therefore, when the write current is increased or decreased, an eddy current is generated correspondingly, and its direction is a direction in which the change of the magnetic flux flowing in the yoke 1 is obstructed. Therefore, in the vicinity of the gap 2, the magnetic flux is bent due to the influence of this demagnetizing field, and the distribution expands outward. This means that the leakage magnetic flux is significantly increased. Further, this effect is proportional to the time change of the magnetic flux, and therefore increases as the recording current becomes high frequency.

Therefore, since the leakage magnetic field increases at the rising and falling portions of the write current, the temporal rise and fall of the magnetic field in the gap portion becomes sharp and the change point of the residual magnetization becomes sharp. Become. Further, since the leakage magnetic flux is larger than that of the conventional head, a high magnetic field extends far, so that the distance between the magnetic recording body 10 and the head can be wide, and the head and the magnetic recording body 10 are generated by floating dust. It is also possible to reduce the probability of a head crash accident due to a collision of.

A similar effect occurs in the case of reproduction. That is, similar to the flow of the reproducing magnetic flux in FIG.
The magnetic flux generated by the residual magnetization 10 flows into the yoke 1 and interlinks with the coil 5 to generate an electromotive force. The magnetic flux further propagates through the yoke 1 and finally returns to the magnetic pole of the magnetic recording body 10.
In this case, all the magnetic flux flowing into the yoke 1 does not interlink the coil 5, but there is a portion that jumps over the gap 2 and directly returns to the magnetic pole. As a result, the magnetic flux efficiency of the magnetic recording body 10 is lowered, and the sensitivity is lowered.

However, in the present embodiment, even in the flow of the magnetic flux during reproduction, a demagnetizing field is generated with respect to the magnetic flux passing through the gap 2, and the magnetic flux is pushed toward the yoke 1 side. As a result, the magnetic flux efficiency is improved and the sensitivity is improved. As a result, the rising of the magnetic flux,
Since the effect occurs at the trailing edge, a sharp reproduction waveform with little jitter can be obtained.

In the above embodiment, the yoke 1 and the conductive layer are
Since the metal layer 3 which is a soft magnetic layer having a high magnetic permeability and a high saturation magnetic flux density is provided between the magnetic recording medium 10 and the magnetic field 15, the magnetic flux can be concentrated and a strong magnetic field can be applied to the magnetic recording body 10. it can.

FIG. 3 is a perspective view showing an essential part of the second embodiment of the present invention. In the second embodiment, the metal layer 3 having a high magnetic permeability is provided for the yoke 1 forming the magnetic path A. Is small. That is, the magnetic recording body 10 in the metal layer 3
The width in the direction orthogonal to the relative movement direction (arrow direction) with respect to is smaller than the width of the magnetic path.

Therefore, since the magnetic flux flows along the metal layer 3 having a high magnetic permeability, the recording magnetic field has a high distribution in this metal layer 3. That is, the magnetic field can be concentrated on the narrow portion of the track 30 in the width direction. As a result, recording and reproduction can be performed on a narrow track, and a high track density can be achieved.

In the above embodiment, since the magnetic flux efficiency can be increased even though the magnetic head has a narrow gap, a high magnetic field can be applied to the magnetic recording medium during recording, and the magnetic recording medium can be effectively magnetized with a small current. It becomes possible to do.

During reproduction, the magnetic flux generated by the magnetic recording medium can be effectively linked to the coil, and high reproduction efficiency can be obtained.

As described above, it is possible to provide a magnetic head having high resolution and high efficiency, especially in a high recording frequency region, though it is a magnetic head manufactured by the same easy method as that of the conventional MIG head. .

[0039]

As described above, according to the magnetic head of the present invention, according to the structure of claim 1, the magnetic flux in the gap portion is more likely to be present in the recording layer of the magnetic recording body than in the case without the conductive layer. It is possible to give a stronger magnetic field.

According to the second aspect of the invention, since the magnetic flux is concentrated on the high magnetic permeability layer, it is possible to apply a stronger magnetic field to the recording layer.

According to the third aspect of the invention, since the magnetic flux can be strongly concentrated in a narrow area, a high track density (narrow track width) can be achieved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a first embodiment of a magnetic head of the present invention.

FIG. 2 is an explanatory diagram of induction current generation.

FIG. 3 is a perspective view showing a main part of a second embodiment of the present invention.

FIG. 4 is an explanatory diagram (during recording) showing a configuration of a conventional MIG head.

FIG. 5 is an explanatory diagram (during reproduction) showing a configuration of a conventional MIG head.

[Explanation of symbols]

1 ... Yoke (soft magnetic member), 2 ... Gap (void),
3 ... Metal layer (soft magnetic layer), 4 ... Glass body, 5 ... Coil (winding), 10 ... Magnetic recording body, 15 ... Conductive layer, A ... Magnetic path.

Claims (3)

[Claims] 1. A magnetic path that circulates is formed by a soft magnetic member, a winding is provided in a part of the magnetic path, and a void portion is provided for generating a leakage magnetic field, and a conductive layer is provided in the void portion. A magnetic head characterized in that 2. The magnetic head according to claim 1, wherein a soft magnetic layer having a high magnetic permeability and a high saturation magnetic flux density is provided between the soft magnetic member and the conductive layer. 3. The magnetic head according to claim 2, wherein a width of the soft magnetic layer in a direction orthogonal to a relative movement direction with respect to the magnetic recording body is smaller than a width of a magnetic path.