JPS5853695Y2 - magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inductive thin film magnetic head formed using thin film manufacturing technology.

Thin-film magnetic heads can be easily manufactured into minute shapes, so
It is attracting attention as a head for high-density magnetic recording and reproduction, and is particularly effective in obtaining a narrow track magnetic head for high-track density recording and reproduction.

However, in order to obtain a narrow track magnetic head with a very narrow track width, if the track width of the magnetic film forming the magnetic pole is made smaller than the yoke length, the magnetization in the magnetic film becomes perpendicular to the track width due to shape anisotropy. It becomes easier to orient yourself.

Therefore, the magnetization mechanism within the magnetic film in response to the reproduction signal magnetic field from the magnetic storage medium or the write signal magnetic field generated from the write current is mainly due to the movement of domain walls, and as a result, during reproduction and writing, The response speed of magnetization of the magnetic film decreases.

Further, due to the magnetization component in the direction perpendicular to the track width, a magnetic charge appears on the surface of the magnetic film forming the magnetic pole facing the magnetic storage medium, and a magnetic field generated from the magnetic charge demagnetizes the signal magnetization on the medium. A problem of so-called regenerative demagnetization occurs.

As described above, it has been difficult to form a high performance narrow track thin film magnetic head using the conventional method.

The purpose of this invention is to provide a high-performance narrow-track thin-film magnetic head, which is characterized by having a core made of a high permeability magnetic material with a gap at one end provided with a winding. By applying a DC magnetic field generated in the vicinity of the gap as a bias magnetic field in the track width direction of the narrow track thin film magnetic head by a DC bias current flowing through the magnetic head, the magnetization in the magnetic film forming the magnetic pole of the thin film head is changed in the track width direction. It's about directing.

That is, the basic configuration of the magnetic head according to the present invention is: a core made of a high magnetic permeability magnetic material having a gap at one end and a winding in a part, and a high permeability magnetic material provided near the gap to form a magnetic pole. A part of the head is formed of a thin film magnetic head.

Next, the present invention will be explained using the drawings.

FIG. 1A schematically shows an embodiment of the present invention, and FIG. 1 particularly shows a narrow track thin film magnetic head on an enlarged scale for easy understanding.

The narrow track thin film magnetic head 1 has a track width W formed on the substrate 2 that is shorter than the magnetic path length, that is, the yoke length, of the high magnetic permeability magnetic films 3 and 4 forming the magnetic poles. The magnetic storage medium 11 is placed in a gap 15 provided at one end of the core 12, and these are placed vertically adjacent to the magnetic storage medium 11.

Here, the magnetic films 3 and 4 are formed with a constant magnetic field applied in the track width direction so that the track width direction is the easy axis direction.

However, if left as is, the magnetization within the magnetic films 3 and 4 tends to be dispersed due to shape anisotropy.

Therefore, by applying a DC bias magnetic field 9 of an appropriate size in the gap 15 in the track width direction by the DC bias current I B K flowing through the winding 14,
Anisotropic dispersion is suppressed, and as a result, the magnetization in the magnetic films 3 and 4 is directed in the track width direction 10 when there is no signal.

(Hereinafter, this state will be referred to as being biased.

) The magnitude of this DC bias magnetic field 9 is the same as that of the magnetic films 3 and 4.
It is sufficient to bias the magnetization direction in the track width direction, but it is enough to not bias the magnetization of the medium 11 (on the order of several to several tens of oersteds), and is adjusted by the current I9 flowing through the winding 14, and the gap 15 It is appropriately selected depending on the size g, the shape and magnetic properties of the magnetic films 3 and 4, the magnetic properties of the medium 11, etc.

There is a magnetic recording/reproducing device described in Japanese Patent Publication No. 53-11452 as a known technique characterized by applying a DC magnetic field in the track width direction of a narrow track thin film magnetic head in this way. are essentially different.

In other words, in the device of Japanese Patent Publication No. 53-11452, the magnetic film that forms the magnetic pole is formed so that the direction perpendicular to the track width is the easy axis, and by applying a DC magnetic field in the track width direction, the easy axis direction is The AC signal magnetic field is detected.

This device certainly has the feature of fast response.

However, when there is no signal, the magnetization in the magnetic film forming the magnetic pole is not oriented in the track width direction, so a magnetization component in the direction perpendicular to the track width exists, and this causes the surface of the magnetic film forming the magnetic pole facing the magnetic recording medium to exist. A magnetic charge appears, and the magnetic field generated from this magnetic charge demagnetizes the signal magnetization on the magnetic recording medium, resulting in the problem of so-called reproduction demagnetization.

In addition, since the easy axis of the magnetic film coincides with the path of the lines of magnetic force during reproduction, the magnetic film is magnetized in a domain wall motion type, which has the disadvantage of producing a lot of Barkhausen noise.

On the other hand, in the present invention, the magnetic film forming the magnetic pole is formed so that the track width direction becomes the easy axis, and the dispersion due to shape anisotropy that occurs at this time is eliminated by applying a DC magnetic field in the track width direction. When there is no signal, the magnetization in the magnetic film constituting the magnetic pole is oriented in the track width direction.

Therefore, in the present invention, when there is no signal, there is no magnetization component in the direction perpendicular to the track width in the magnetic film constituting the magnetic pole, so the problem of reproducing demagnetization as described above does not occur.

Furthermore, by applying a signal magnetic field in the direction of the hard axis, the magnetic film operates in a magnetization rotation mode rather than a domain wall movement type, resulting in high-speed response and reduced Barkhausen noise.

As described above, the difference between the present invention and the magnetic recording/reproducing apparatus described in Japanese Patent Publication No. 11452/1988 is obvious.

A magnetic head whose easy axis is in the track width direction is
IEEE Transactions on Magnetics
Magnetics) MAG-volume 6, page 601 (19
1970), but in order to reduce dispersion due to shape anisotropy, it is necessary to arrange a large number of magnetic films and non-magnetic films stacked alternately, which requires extremely advanced technology and reduces the yield rate. The disadvantage is that it is bad.

The present invention achieves this by applying a DC magnetic field from outside in the track width direction, and has the advantage of being extremely easy to manufacture and having a high yield rate.

An example of materials, shapes, and configurations will be shown to make the present invention more specific.

The magnetic films 3 and 4, which are high permeability magnetic materials forming the magnetic poles of the narrow track thin film magnetic head 1, have a thickness of several square meters,
A conductive layer 6 in which a high magnetic permeability ferromagnetic thin film such as permalloy with a track width of W + □ and a yoke length of several tens to hundreds of microns forms a coil for flowing a write signal current and detecting the induced output during reproduction. The thickness is several thousand angstroms.
Several microns of gold, copper, aluminum, etc. are applied to the magnetic film 3.
, 4 and the conductor 6 is SiO, 5i02 or Al2O3 with a thickness of several thousand angstroms.
However, as the substrate 2, silicon single crystal, glass, ferrite block, etc. are suitable.

As the core 12 forming the magnetic path for generating the DC bias magnetic field 9, it is suitable to use a high permeability magnetic material such as permalloy or ferrite processed into an appropriate size.

The size of the gap g is selected from several tens of square meters to several millimeters depending on the size of the substrate 2, and a DC bias magnetic field 9 of several to several tens of oersteds is generated in the track width direction of the narrow track magnetic head 1. Bias current IB is adjusted accordingly.

FIG. 2 shows a second embodiment of the present invention, in which a narrow track thin film magnetic head 1, a core 12 for generating a DC bias magnetic field 9, and a winding 14 for passing a DC bias current are manufactured using thin film manufacturing technology. They are formed on the same substrate 2.

In FIG. 2, the core 12 for generating a DC bias magnetic field is made of a high permeability magnetic material such as permalloy with a thickness of several to several tens of microns, and the conductive layer 14 is made of gold, copper, etc. with a thickness of several microns to several tens of microns. The insulator 5 that electrically insulates the core 12 and the conductive layer 14 is made of aluminum or the like, and is made of SiO, 5i02, or AI with a thickness of several thousand angstroms.
A thin film such as 203 is suitable.

As the substrate 2, silicon single crystal, glass, or a ferrite block is suitable as in the case of FIG. 1, but in this configuration, the substrate 2 may also serve as a slider formed of ceramic or a ferrite block.

Alternatively, the lower pole 4 of the narrow track thin film magnetic head 1 may be constructed of a ferrite block, which may also serve as the substrate 2 or the slider.

FIG. 3 shows a third embodiment of the present invention, in which a narrow track thin film magnetic head 1 is placed on the side of a gap 15 of a core 12 for generating a DC bias magnetic field.

In this case, due to the DC bias current IB, the gap 1
A DC bias magnetic field 9 generated on the side surface of the narrow track thin film magnetic head 1 is applied in the track width direction of the narrow track thin film magnetic head 1.

Compared to the embodiment shown in FIGS. 1 and 2, this configuration has the following features:
It has the advantage that the size of the gap g can be freely selected.

FIG. 4 shows a fourth embodiment of the present invention, in which a narrow track thin film magnetic head 1 is disposed on the side of a gap 15 of a core 12 for generating a DC bias magnetic field, and a DC bias field is supplied to a winding 14. The bias current IB biases the magnetization in the magnetic films 3 and 4 in the track width direction as in the case of FIG. 3, but the coil 16 connected to the electrode terminal 7 connected to the coil 6 of the narrow track thin film magnetic head However, the core 12
A winding 17 having several to tens of times as many turns as the primary coil is arranged in a part of the core 12 to form a secondary coil. It is characterized in that the coil is provided with an electrode terminal 18, and information is written and reproduced via this terminal 18.

In this configuration, the core 12 serves as a transformer, so the current flowing through the coil 17 during writing can be smaller than in the embodiments shown in Figures 1 to 3, and a large output can be obtained during playback. This is a feature.

In the above explanation, the coil 6 of the narrow track thin film magnetic head 1 to which the present invention is effective has been described as having a half-turn, but it is equally applicable to a so-called multi-turn head in which the coil 6 has two or more turns. It is.

According to the present invention, in order to easily align the magnetization in the magnetic bodies 3 and 4 constituting the magnetic poles of the thin-film magnetic head in the track width direction and prevent dispersion due to shape anisotropy, a simple DC magnetic field consisting of a core and a coil is used. Because it is biased in the easy axis direction by the generator, the magnetic materials 3 and 4 are
The magnetization inside rotates in a direction perpendicular to the track width direction, and this rotational movement of magnetization has a fast response speed and generates little Barkhausen noise during reproduction. Since no magnetic charge is generated in the magnetic field, an excellent narrow track thin film magnetic head without reproduction demagnetization can be constructed.

In the embodiments shown in FIGS. 1 to 4, the high permeability magnetic material constituting the magnetic pole of the thin film magnetic head is entirely formed of a thin film. Even in cases where the permalloy thin film is made of a thin film, the effects of the present invention can be exhibited by applying a similar bias magnetic field to the permalloy thin film.

As described above, according to the present invention, a high performance narrow track thin film magnetic head can be provided.

It goes without saying that the present invention can also be effectively applied to thin film magnetic heads with relatively wide track widths.

[Brief explanation of the drawing]

1 is a diagram showing a first embodiment of the present invention, in which a is a schematic perspective view, b is an enlarged perspective view of the thin film magnetic head portion thereof, and FIG. 2 is a schematic perspective view showing a second embodiment; FIG. 3 is a schematic perspective view showing the third embodiment, and FIG. 4 is a schematic perspective view showing the fourth embodiment. DESCRIPTION OF SYMBOLS 1... Narrow track thin film magnetic head, 2... Substrate, 3
...Top magnetic pole, 4...Bottom magnetic pole, 5...Insulating layer,
6... Coil, 7... Electrode extraction terminal, 8, 10...
・Magnetization in the magnetic film, 9...DC bias magnetic field, 11.
...Magnetic storage medium:, 12...High magnetic permeability magnetic material, 13
...Magnetic flux, 14...Winding, 15...Gap, 1
6...Primary coil, 17...Secondary coil, 18...
・Electrode terminal.

Claims (1)

[Claims for Utility Model Registration] 1. A gap is formed in a part of a core made of a high permeability magnetic material having a winding, and at least a part of the high permeability magnetic material forms a magnetic pole in or on the side of the gap. A thin film magnetic head is installed in which the axis of easy magnetization of the high permeability magnetic thin film is in the track width direction, and the track width of the high permeability magnetic thin film is changed by passing a DC bias current through the winding. (A magnetic head characterized by applying a direct current magnetic field. 2. The core includes a winding that passes a direct current bias current, a winding that serves as a primary coil connected to the coil of the thin film magnetic head, and a winding that serves as a primary coil connected to the coil of the thin film magnetic head. A magnetic head according to claim 1, which is a utility model and has a winding serving as a secondary coil connected to an amplifier used for recording or reproduction.